FN Thomson Reuters Web of Science™ VR 1.0 PT J AU BROWN, DA PEREZ, MR YUSEFZADEH, F AF BROWN, DA PEREZ, MR YUSEFZADEH, F TI RADIO-CONTINUUM OBSERVATIONS OF THE HERBIG AE/BE STARS HD-163296 AND HR-5999 SO ASTRONOMICAL JOURNAL LA English DT Article ID BE-TYPE STARS; CIRCUMSTELLAR DUST; LINE-PROFILES; HOT STARS; VARIABILITY; EMISSION; SPECTRA; SHELLS AB Very Large Array1 observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda3.6 and 20 cm. We report the detection of a radio source at lambda3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 X 10(-8) M . D yr-1 if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km s-1. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE OBSERV,GREENBELT,MD 20771. RP BROWN, DA (reprint author), NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208, USA. NR 48 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD NOV PY 1993 VL 106 IS 5 BP 2000 EP 2004 DI 10.1086/116781 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ME684 UT WOS:A1993ME68400023 ER PT J AU SION, EM SHORE, SN READY, CJ SCHEIBLE, MP AF SION, EM SHORE, SN READY, CJ SCHEIBLE, MP TI THE ONSET OF WOLF-RAYET WIND OUTFLOW AND THE NATURE OF THE HOT COMPONENT IN THE SYMBIOTIC NOVA PU VULPECULA SO ASTRONOMICAL JOURNAL LA English DT Article AB We have analyzed temporal variations in the far ultraviolet He II (1640), Si IV (1393, 1402), and C IV (1548, 1550) line profiles in eight high dispersion, International Ultraviolet Explorer Short Wavelength Prime spectra of the symbiotic nova PU Vul by comparatively examining these profiles on a common velocity scale. We see clear evidence of the onset of a Wolf-Rayet-like wind outflow from the bloated, contracting white dwarf hot component with terminal velocity of almost-equal-to - 550 to - 600 km/s. We have quantitatively analyzed the complicated He II (1640) emission region for the first time and show that the discrete absorption features seen in the He II region occur at precisely the same velocities in each spectrum, thus demonstrating that the absorbing source is steady and not affected by any orbital motion. We demonstrate that there is an underlying He II wind emission feature whose true shape is hidden by superposed absorption due to the foreground red giant wind flowing in front of the white dwarf and obscuring the white dwarf's wind outflow. We present synthetic spectra of He II emission behind an absorbing slab with v = 20 km/s, T = 5000 K, and column densities in the range N = 1 X 10(22) and 1 X 10(23)/cm2 which explain these absorptions. Our analysis of the Si IV and C IV resonance doublets, in velocity space, reveal temporal variations in the profile between 1987 and 1991 with the emergence of clear P Cygni profiles in Si IV by 1990. A nebular emission feature in C III] 1909 also appears in the most recent spectra (e.g., SW42538H) while it was absent or extremely weak in the earliest spectra (e.g., SW36332H), thus strengthening evidence that the nebular emission, as seen in permitted and semiforbidden lines, intensifies in step with the onset of the hot, fast, wind outflow. We also report the first detection of narrow interstellar (circumbinary shell?) absorption lines near - 1 km/s, most strongly in Al III (1854, 1862) and Si iv (1392, 1402). We have carried out a rough quantitative analysis of the He II wind emission by using the theoretical He II Wolf-Rayet profiles of Hamann & Schmutz [A&A, 174, 173 (1987)]. We obtain a lower limit to the He II net emission equivalent width of approximately 1 angstrom, a hot component temperature in the range 25 000 to 35 000 K, a hot component radius in the range 5R. to 30R., a maximum wind velocity of almost-equal-to - 600 km/s and a rough upper limit to the mass-loss rate of < 1 X 10(-5) M./yr. To our knowledge, this is the first quantitative wind analysis, albeit crude, to be carried out for the hot component of a symbiotic nova or symbiotic variable. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAM,GREENBELT,MD 20771. RP SION, EM (reprint author), VILLANOVA UNIV,DEPT ASTRON & ASTROPHYS,VILLANOVA,PA 19085, USA. NR 10 TC 11 Z9 11 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD NOV PY 1993 VL 106 IS 5 BP 2118 EP 2125 DI 10.1086/116789 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ME684 UT WOS:A1993ME68400031 ER PT J AU PARMAR, AN ANGELINI, L ROCHE, P WHITE, NE AF PARMAR, AN ANGELINI, L ROCHE, P WHITE, NE TI THE DISCOVERY AND PROPERTIES OF THE ULTRA-SOFT X-RAY TRANSIENT EXO-1846-031 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, INDIVIDUAL, EXO-1846-031; X-RAYS, BURSTS; X-RAYS, STARS; ACCRETION DISKS; BLACK HOLE PHYSICS ID BLACK-HOLE; LUMINOSITY DEPENDENCE; PULSAR EXO-2030+375; ACCRETION DISKS; NOVA; BINARIES; CATALOG AB We report the discovery of a previously uncatalogued ultra-soft X-ray transient EXO 1846-031 which was in outburst during 1985 April to September. The X-ray spectrum consists of an ultra-soft component and a high-energy power-law tail that extends to at least 25 keV. The ultra-soft component may be modeled by either a cutoff power-law or a multicolor blackbody disk model. The latter model allows the evolution in spectrum and intensity observed during the outburst to be accounted for by the change in a single parameter - the temperature at the innermost disk radius. We demonstrate that at least one other accretion disk model is able to account for these changes by the variation of a single parameter. During one of the three EXOSAT observations, EXO 1846-031 exhibited significant intensity variability which probably originates from the power-law component. We derive a position for this unidentified source and present the results of a search for the optical counterpart. C1 UNIV SPACE RES ASSOC, WASHINGTON, DC USA. UNIV SOUTHAMPTON, DEPT PHYS, SOUTHAMPTON SO9 5NH, HANTS, ENGLAND. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP PARMAR, AN (reprint author), ESA, DEPT SPACE SCI, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 39 TC 14 Z9 14 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 1993 VL 279 IS 1 BP 179 EP 187 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG680 UT WOS:A1993MG68000025 ER PT J AU ALTWEGG, K BALSIGER, H GEISS, J GOLDSTEIN, R IP, WH MEIER, A NEUGEBAUER, M ROSENBAUER, H SHELLEY, E AF ALTWEGG, K BALSIGER, H GEISS, J GOLDSTEIN, R IP, WH MEIER, A NEUGEBAUER, M ROSENBAUER, H SHELLEY, E TI THE ION POPULATION BETWEEN 1300 KM AND 230000 KM IN THE COMA OF COMET P/HALLEY SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMETS, GENERAL; COMETS, INDIVIDUAL, P/HALLEY ID GIOTTO IMS EXPERIMENT; MASS-SPECTROMETER; DYNAMICS; HALLEY; FLOW; ABUNDANCES; CHEMISTRY; AMMONIA AB During the encounter of the spacecraft Giotto with Comet Hailey the two sensors of the ion mass spectrometer (IMS), HERS and HIS, measured the mass and the three-dimensional velocity distributions of cometary ions. HIS looked mainly at the cold, slow part of the distribution close to the nucleus, HERS at the more energetic pick-up ions further out. After a thorough recalibration of the HIS flight spare unit and an extensive data analysis we present here continuous ion density-, composition-, velocity- and temperature profiles for the water group ion (mass range 16-19 amu/e) along Giotto's inbound trajectory from 230000 to 1300 km from the comet nucleus. The two sensors are in very good agreement in the region where their measurements overlap thus giving an excellent data base for the discussion of theoretical comet models. The most prominent feature where models and observations disagree is the so called pile up region between 8000 and 15 000 km from the nucleus. C1 JET PROP LAB, PASADENA, CA 91109 USA. MAX PLANCK INST AERON, D-37191 KATLENBURG DUHM, GERMANY. LOOKHEED PALO ALTO RES LAB, PALO ALTO, CA 94306 USA. RP ALTWEGG, K (reprint author), UNIV BERN, INST PHYS, CH-3012 BERN, SWITZERLAND. NR 19 TC 51 Z9 51 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 1993 VL 279 IS 1 BP 260 EP 266 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG680 UT WOS:A1993MG68000034 ER PT J AU BOHLIN, RC DEUTSCH, EW MCQUADE, KA HILL, JK LANDSMAN, WB OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP AF BOHLIN, RC DEUTSCH, EW MCQUADE, KA HILL, JK LANDSMAN, WB OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING TELESCOPE - GLOBULAR-CLUSTERS IN M31 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M31); GLOBULAR CLUSTERS, GENERAL; ULTRAVIOLET, GALAXIES ID EARLY-TYPE GALAXIES; PHOTOELECTRIC PHOTOMETRY; STELLAR-SYSTEMS; STAR-CLUSTERS; METALLICITY; SPECTRA; LUMINOSITY; CATALOG; SEARCH AB Two 40' fields of M31 observed with the Ultraviolet Imaging Telescope (UIT) during the Astro-1 mission in 1990 December are searched for known globular clusters. The flux of 20 clusters in the nucleus field and 23 clusters in the disk field are measured in a near ultraviolet (NUV approximately 2500 angstrom) bandpass. In the far-ultraviolet (FUV approximately 1500 angstrom), only four clusters are detected with certainty, and six others are possible detections. The NUV photometry of the M31 globulars that are detected by UIT do not have a UV excess in comparison to their Galactic counterparts. The spectral energy distributions of the globular clusters from the NUV to V fall within the range of predictions of the Buzzoni models for a 15 Gyr old population. However, two of the three classical globular clusters with red NUV and visible colors that are detected in the FUV have a ''UV upturn'' with fluxes that are greater in the FUV than in the NUV. The other seven FUV detections have optical colors that are too blue for classical globular clusters and are probably the nuclei of compact OB associations. C1 HUGHES STX,LANHAM,MD 20706. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BOHLIN, RC (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 48 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1993 VL 417 IS 1 BP 127 EP 144 DI 10.1086/173297 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD103 UT WOS:A1993MD10300012 ER PT J AU HOWARTH, ID BOLTON, CT CROWE, RA EBBETS, DC FIELDUS, MS FULLERTON, AW GIES, DR MCDAVID, D PRINJA, RK REID, AHN SHORE, SN SMITH, KC AF HOWARTH, ID BOLTON, CT CROWE, RA EBBETS, DC FIELDUS, MS FULLERTON, AW GIES, DR MCDAVID, D PRINJA, RK REID, AHN SHORE, SN SMITH, KC TI TIME-SERIES OBSERVATIONS OF O STARS .3. IUE AND HST SPECTROSCOPY OF ZETA-OPHIUCHI AND IMPLICATIONS FOR THE PHOTOSPHERIC CONNECTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EARLY-TYPE; STARS, INDIVIDUAL (ZETA-OPHIUCHI); STARS, MASS LOSS; ULTRAVIOLET, STARS ID DRIVEN STELLAR WINDS; ULTRAVIOLET-SPECTRUM; LINE; OSCILLATIONS; VARIABILITY; RESOLUTION; DEPENDENCE; ROTATION AB Stellar-wind variability in the archetypal nonradially pulsating O star zeta Oph (O9.5 V) is discussed on the basis of new time-series IUE and HST spectroscopy and archival results. Time-variable ''discrete absorption components'' are first observed at high velocities (greater than or similar to 10(3) km s-1 congruent-to 0.8v(infinity)) and then migrate blueward; the recurrence time scale for the phenomenon is approximately 20 hr. This is the first record of this type of variability in a luminosity-class V star and provides support for the previously inferred ubiquity of such behavior across the O-star regime. The accelerations are slower than predicted by steady state wind models and are unlikely to represent the time-averaged velocity law of the outflow. The UV results are discussed in the context of simultaneous optical observations (Paper II); no evidence is found to suggest that nonradial pulsations have any direct role in determining the gross observational characteristics of discrete absorption components, on either long (years) or short (hours) time scales. The line-driven instability provides a promising mechanism to account for variability observed in the UV P Cygni profiles of zeta Oph, and, by extension, in all other O stars. C1 UNIV TORONTO,DAVID DUNLAP OBSERV,RICHMOND HILL L4C 4Y6,ONTARIO,CANADA. UNIV HAWAII,DEPT PHYS & ASTRON,HILO,HI 96720. UNIV TORONTO,DEPT ASTRON,TORONTO M5S 1A1,ONTARIO,CANADA. BALL AEROSP SYST GRP,BOULDER,CO 80306. UNIV DELAWARE,BATROL RES INST,NEWARK,DE 19716. GEORGIA STATE UNIV,DEPT PHYS & ASTRON,ATLANTA,GA 30303. UNIV TEXAS,DIV EARTH & PHYS SCI,SAN ANTONIO,TX 78285. NASA,GODDARD SPACE FLIGHT CTR,GHRS SCI TEAM,COMP SCI CORP,ASTRON PROGRAM,GREENBELT,MD 20771. RP HOWARTH, ID (reprint author), UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,GOWER ST,LONDON WC1E 6BT,ENGLAND. NR 56 TC 33 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1993 VL 417 IS 1 BP 338 EP 346 DI 10.1086/173316 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD103 UT WOS:A1993MD10300031 ER PT J AU FAJARDOACOSTA, SB TELESCO, CM KNACKE, RF AF FAJARDOACOSTA, SB TELESCO, CM KNACKE, RF TI DETECTION OF SILICATES IN THE 51-OPHIUCHI SYSTEM SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, INDIVIDUAL (51-OPHIUCHI) ID STARS; OLIVINE; 20-MU-M; EXCESS AB We have detected a prominent 10 mum silicate emission feature in 51 Oph, a B9.5 Ve star with circumstellar emission. 51 Oph shows the ''Vega phenomenon,'' probable disk emission from a main-sequence star. We obtained narrow-band spectrophotometry (DELTAlambda almost-equal-to 1 mum) of the inner 5'' diameter region. The emission feature is more than 25 times stronger than the photospheric flux at 10 mum. We estimate that the temperatures of grains within 180 AU of the star range between 400 and 1000 K. The total flux density at the peak of the emission feature is approximately 1.4 times the underlying dust continuum, implying particle sizes smaller than approximately 8 mum. The shape of the silicate feature in 51 Oph resembles those in beta Pictoris and in cometary spectra, but the grains around 51 Oph are warmer and probably larger than those around beta Pic. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. PENN STATE UNIV,ERIE,PA 16563. RP FAJARDOACOSTA, SB (reprint author), SUNY STONY BROOK,DEPT EARTH & SPACE SCI,STONY BROOK,NY 11794, USA. NR 18 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1993 VL 417 IS 1 BP L33 EP L36 DI 10.1086/187087 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD104 UT WOS:A1993MD10400009 ER PT J AU PALMER, DM AF PALMER, DM TI RADIO DISPERSION AS A DIAGNOSTIC OF GAMMA-RAY BURST DISTANCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GAMMA-RAYS, BURSTS; ISM, GENERAL; METHODS, OBSERVATIONAL; RADIATION MECHANISMS, MISCELLANEOUS ID CASCADE MODEL; PULSARS AB If gamma-ray bursts sources emit even a small fraction of their energy in the radio spectrum, dispersion measurements of this emission would determine the distance to the source and thereby greatly constrain theoretical models. If a GRB is at z approximately 1, or is beyond the Galactic center and in the Galactic plane, the signal at low frequencies (approximately 25 MHz) will be delayed by approximately 1 hr, which is enough time to allow a radio telescope to be pointed toward the GRB location. Such a measurement could detect a GRB with L(Radio)/L(gamma-ray) greater than or similar to 10(-7), while an observation at higher frequencies could detect a GRB with L(R)/L(gamma) greater than or similar to 10(-8), both of which are much more sensitive than the current upper limit of L(R)/L(gamma) less than or similar 10(-3.5). A dispersion measurement for an extragalactic GRB would also observe for the first time the intergalactic plasma, which may be the dominant form of baryonic matter in the universe. RP PALMER, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 28 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1993 VL 417 IS 1 BP L25 EP L28 DI 10.1086/187085 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD104 UT WOS:A1993MD10400007 ER PT J AU IVANOV, GR FREEDMAN, WL MADORE, BF AF IVANOV, GR FREEDMAN, WL MADORE, BF TI A CATALOG OF BLUE AND RED SUPERGIANTS IN M33 SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE CATALOGS; GALAXIES, INDIVIDUAL (M33); GALAXIES, STELLAR CONTENT; SUPERGIANTS; TECHNIQUES, PHOTOMETRIC ID SPIRAL GALAXY M33; STELLAR CONTENT; LUMINOSITY FUNCTION; LOCAL GROUP; STARS; ASSOCIATIONS; M-33; MORPHOLOGY; COMPLEXES; HYDROGEN AB We present a catalog of blue and red stars in M33 based on photographic photometry of over 65,000 objects extracted from plates taken with the 3.6 m Canada-France-Hawaii Telescope (CFHT) and the 2.0 m Rozhen (Bulgarian) Telescope. The completeness limit of the various surveys are estimated here to be V = 19.5 mag for those star's situated in crowded associations, and V = 20.0 mag for stars in the interarm fields. We list magnitudes and positions for 2112 blue stars, defined by ( U - V) < 0.0 mag, (U - B) < 0.0 mag, and V < 19.5 mag, and 389 red stars defined by (B - V) > 1. 8 mag and V < 19.5 mag. Of these, 1156 are candidate 0 stars on the basis of (U - V) < -0.9 mag. C1 CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. RP IVANOV, GR (reprint author), UNIV SOFIA,DEPT ASTRON,5 JAMES BOURCHIER ST,BU-1126 SOFIA,BULGARIA. NR 32 TC 38 Z9 39 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 1993 VL 89 IS 1 BP 85 EP 122 DI 10.1086/191840 PG 38 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ME476 UT WOS:A1993ME47600004 ER PT J AU BHATIA, AK KASTNER, SO AF BHATIA, AK KASTNER, SO TI THE OPTICALLY THICK C-III SPECTRUM .2. LEVEL TERM POPULATIONS AND LINE MULTIPLET INTENSITIES USING AN IMPROVED HYBRID MODEL SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article AB An improved hybrid level/term calculation is employed to obtain C III level/term populations and line/fractional multiplet intensities over the extended range of electron density 4.0 less-than-or-equal-to log N(e) less-than-or-equal-to 12.0, for column lengths L ranging from zero (optically thin) to 10(20) cm-2 (moderately optically thick), at electron temperatures T(e) approximately 40,000 K (log T(e) = 4.6), T(e) approximately 63,000 K (log T(e) = 4.8), T(e) approximately 79,500 K (log T(e) = 4.9), and T(e) = 100,000 K (log T(e) = 5.0). The tabulated results are relevant to the interpretation of space observations obtained over extended spectral ranges by new and planned facilities including the Hopkins Ultraviolet Telescope (HUT) and the Far-Ultraviolet Spectrographic Explorer (FUSE). C1 MATH SCI CONSULTANTS INC,GREENBELT,MD 20770. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 1993 VL 89 IS 1 BP 227 EP 257 DI 10.1086/191846 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ME476 UT WOS:A1993ME47600010 ER PT J AU FRASER, RS AF FRASER, RS TI OPTICAL-THICKNESS OF ATMOSPHERIC DUST OVER TAJIKISTAN SO ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS LA English DT Article DE REMOTE SENSING; AEROSOLS; DUST ID SATELLITE MEASUREMENTS; SCATTERING; ALGORITHM; PARTICLES; AEROSOLS; IMAGERY AB The aerosol dust optical thickness during a dust experiment in Tadzhikistan is derived from satellite measurements of reflected sunlight. The method estimates the surface reflectance on days with low optical thickness for the same ground area where dust occurs. In order to avoid changes in the surface bidirectional reflectance between the dusty and clear days, nearly identical geometry between the solar and view directions is obtained eight days before a dust storm. Lookup tables are utilized to obtain the surface reflectance on the clear day, and another set of lookup are tables is used to assign an optical depth to the dust. The optical depth lookup tables utilize Mie scattering for a representative size distribution and index of refraction for the dust aerosol. The observed similarity of size distributions and indices of refraction for dust aerosols at many locations over the earth justify this method. A map of the dust optical thickness is given. RP FRASER, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 20 TC 10 Z9 14 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0004-6981 J9 ATMOS ENVIRON A-GEN PD NOV PY 1993 VL 27 IS 16 BP 2533 EP 2538 DI 10.1016/0960-1686(93)90026-U PG 6 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA MJ816 UT WOS:A1993MJ81600010 ER PT J AU BHATIA, AK DOSCHEK, GA AF BHATIA, AK DOSCHEK, GA TI ATOMIC DATA AND SPECTRAL-LINE INTENSITIES FOR C-LIKE SI-IX SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID ELECTRON-IMPACT EXCITATION; CROSS-SECTIONS; TRANSITIONS C1 USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 12 TC 27 Z9 27 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD NOV PY 1993 VL 55 IS 2 BP 281 EP 314 DI 10.1006/adnd.1993.1023 PG 34 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA MR225 UT WOS:A1993MR22500003 ER PT J AU BHATIA, AK DOSCHEK, GA AF BHATIA, AK DOSCHEK, GA TI ATOMIC DATA AND SPECTRAL-LINE INTENSITIES FOR C-LIKE NE-V SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID EXCITATION C1 USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 12 TC 30 Z9 30 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD NOV PY 1993 VL 55 IS 2 BP 315 EP 348 DI 10.1006/adnd.1993.1024 PG 34 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA MR225 UT WOS:A1993MR22500004 ER PT J AU SCHAFER, LE BAGIAN, JP AF SCHAFER, LE BAGIAN, JP TI OVERHEAD AND FORWARD REACH CAPABILITY DURING EXPOSURE TO +1 TO +6 GX LOADS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB The lack of reach performance data obtained under spaceflight conditions has led to questions regarding the operational impact of higher G loads on crew performance. This investigation studied the effect of increasing G loads on reach capability. Ten subjects were exposed in a stepwise fashion to increasing accelerations resulting in G loads of from +1 to +6 Gx in the Brooks AFB centrifuge. Four subjects wore the pre-Challenger Launch Entry Helmet (LEH) ensemble and six the current Launch Entry Suit (LES). The subjects performed standardized reach sweeps at each G level. These sweeps were recorded on videotape and subsequently analyzed using a 3-dimensional motion analysis system. Significant differences in forward and overhead reach were determined using the General Linear Models (GLM) procedure of the Statistical Analysis System (SAS) program. The results from this study suggest that purposeful movement can be realistically performed in the LEH at the 5 G level and in the LES up to the 4 G level. C1 NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,MAIL CODE CB,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,ANTHROPOMETRY & BIOMECH LAB,HOUSTON,TX 77058. NR 3 TC 2 Z9 2 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 1993 VL 64 IS 11 BP 979 EP 984 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA ME955 UT WOS:A1993ME95500001 PM 8280045 ER PT J AU MATNEY, ML BOYD, JF COVINGTON, PA LEANO, HJ LIMERO, TF JAMES, JT AF MATNEY, ML BOYD, JF COVINGTON, PA LEANO, HJ LIMERO, TF JAMES, JT TI AIR-QUALITY ASSESSMENTS FOR 2 RECENT SPACE-SHUTTLE FLIGHTS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID ORGANIC-COMPOUNDS AB Degradation of air quality in the Space Shuttle environment through chemical contamination and high solid-particulate levels may affect crew performance and health. A comprehensive study of the Shuttle atmosphere was undertaken during the STS-40 (Spacelab Space Life Sciences 1) and STS-42 (Spacelab International Microgravity Laboratory 1) missions to determine the effectiveness of contaminant control procedures by measuring concentrations of volatile organic compounds and analyzing particulate matter trapped on air filters. Analysis of volatile contaminants showed that the air was toxicologically safe to breathe during both missions with the exception of one period during STS-40 when the Orbiter Refrigerator/Freezer was releasing noxious gases into the middeck. Chemical analyses of selected particles collected on air filters facilitated their positive identification. Trace amounts of rat hair and food particles were found in the STS-40 Spacelab filters; a trace amount of soilless plant-growth media was detected in the STS-42 Spacelab filter. The low levels of particles released from these Spacelab experiments indicate that containment measures were effective. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,SD4,HOUSTON,TX 77058. NR 7 TC 0 Z9 0 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 1993 VL 64 IS 11 BP 992 EP 1000 PG 9 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA ME955 UT WOS:A1993ME95500003 PM 8280047 ER PT J AU ELLIS, S KIRBY, LC GREENLEAF, JE AF ELLIS, S KIRBY, LC GREENLEAF, JE TI LOWER-EXTREMITY MUSCLE THICKNESS DURING 30-DAY 6-DEGREES HEAD-DOWN BED REST WITH ISOTONIC AND ISOKINETIC EXERCISE TRAINING SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SKELETAL-MUSCLE; IMMOBILIZATION; MEN AB Muscle thickness was measured in 19 bed-rested (BR) men (32-42 year) subjected to isotonic (ITE, cycle ergometer) and isokinetic (IKE, torque ergometer) lower extremity exercise training, and no exercise (NOE) training. Thickness was measured with ultrasonography in anterior thigh-rectus femoris (RF) and vastus intermedius (VI), and combined posterior leg-soleus, flexor hallucis longus, and tibialis posterior (S + FHL + TP)-muscles. Compared with ambulatory control values, thickness of the (S + FHL + TP) decreased by 9%-12% (p < 0.05) in all three test groups. The (RF) thickness was unchanged in the two exercise groups, but decreased by 10% (p < 0.05) in the NOE. The (VI) thickness was unchanged in the ITE group, but decreased by 12%-16% (p < 0.05) in the IKE and NOE groups. Thus, intensive, alternating, isotonic cycle ergometer exercise training is as effective as intensive, intermittent, isokinetic exercise training for maintaining thicknesses of rectus femoris and vastus intermedius anterior thigh muscles, but not posterior leg muscles, during prolonged BR deconditioning. C1 NASA,AMES RES CTR,DIV LIFE SCI,HUMAN GRAVITAT PHYSIOL LAB 23911,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV,SAN JOSE,CA 95192. NR 25 TC 16 Z9 16 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 1993 VL 64 IS 11 BP 1011 EP 1015 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA ME955 UT WOS:A1993ME95500006 PM 8280033 ER PT J AU KUMAR, KV WALIGORA, JM POWELL, MR AF KUMAR, KV WALIGORA, JM POWELL, MR TI EPIDEMIOLOGY OF DECOMPRESSION-SICKNESS UNDER SIMULATED SPACE EXTRAVEHICULAR ACTIVITIES SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Review ID MODELS; DIVERS AB Several ground-based trials were conducted by NASA at the Lyndon B. Johnson Space Center, Houston, TX, during 1982-90 to examine the risk of altitude decompression sickness (DCS) during space extravehicular activities. There were 22 different pressure profiles involving single and staged decompression procedures, each lasting from 180 to 360 min at the final altitude. A total of 164 healthy subjects participated in 426 exposures to altitude. Symptoms of DCS occurred in 17% (74/426) and circulating microbubbles by precordial Doppler ultrasound were detected in 42% (179/426) of all exposures. About 27% (20/74) of exposures with symptoms resulted in test abort, and one-third of all test aborts required treatment in the hyperbaric chamber. There was about 3.20 times (95% Confidence Interval [95% Cl] = 1.56-6.66) higher risk of symptoms in the presence of Doppler-detectable microbubbles. Examination of individual risk factors showed that there was about 4.3 times (95% Cl = 1.62-11.50) higher risk of symptoms with increasing number of exposures. These findings emphasize the importance of evaluating risk factors from ground-based trials for application in operational decision-making and treatment strategies. C1 NASA,LANGLEY RES CTR,SPACE BIOMED RES INST,HAMPTON,VA 23665. RP KUMAR, KV (reprint author), KRUG LIFE SCI,ENVIRONM PHYSIOL LAB,HOUSTON,TX 77058, USA. NR 29 TC 19 Z9 19 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 1993 VL 64 IS 11 BP 1032 EP 1039 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA ME955 UT WOS:A1993ME95500009 PM 8280036 ER PT J AU LISTON, GE BROWN, RL DENT, J AF LISTON, GE BROWN, RL DENT, J TI APPLICATION OF THE E-EPSILON TURBULENCE CLOSURE-MODEL TO SEPARATED ATMOSPHERIC SURFACE-LAYER FLOWS SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID BOUNDARY-LAYER; KINETIC-ENERGY; PLANT CANOPY; SHEAR FLOWS; DISPERSION; GAS AB Neutrally buoyant atmospheric surface-layer flow over a thin vertical wall has been studied using a turbulence closure scheme designed specifically to address flow problems containing high shears. The turbulent flow model consists of a general solution of the time averaged, steady state, two-dimensional Navier-Stokes equations, where the E-epsilon turbulence model has been used to close the system of equations. Model output compares favorably with measurements made in both a full-scale field study and in an atmospheric wind tunnel. In the simulation of flow over a solid wall, two recirculation eddies are produced. The smallest eddy is located windward of the wall with a separation point located at x/h = -0.8, and the largest is located in the lee of the wall at x/h = 5.8. Immediately downwind of the wall top, the turbulent kinetic energy, the energy dissipation rate, and the momentum flux all reach a local maximum. These peak values generally maintain their height position z/h = 1.0, but decrease progressively downwind. The turbulent viscosity is strongly modified under the influence of the wall, with a local maximum forming in the lee of the wall top, and a local minimum forming at a height z/h = 2.0 above the lee recirculation eddy. The surface momentum flux reduction due to the presence of the wall begins at x/h = - 10.0. Minimum zero fluxes occur at the surface separation points, and a local peak in momentum flux is produced at the centers of each recirculation eddy. Downwind of the wall, the modeled surface flux reaches an equilibrium at roughly x/h = 30.0. C1 MONTANA STATE UNIV,DEPT CIVIL & AGR ENGN,BOZEMAN,MT 59717. RP LISTON, GE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771, USA. NR 42 TC 8 Z9 8 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD NOV PY 1993 VL 66 IS 3 BP 281 EP 301 DI 10.1007/BF00705479 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MB096 UT WOS:A1993MB09600005 ER PT J AU Lieske, JH AF Lieske, J. H. TI ALGORITHM FOR IAU NORTH POLES AND ROTATION PARAMETERS Which way is up ? SO CELESTIAL MECHANICS & DYNAMICAL ASTRONOMY LA English DT Article DE Poles; IAU north; rotation rates; prime meridian AB In 1970 the IAU defined any object's north pole to be that axis of rotation which lies north of the solar system's invariable plane. A competing definition in widespread use at some institutions followed the 'right hand rule' whereby the 'north' axis of rotation was generally said to be that that of the rotational angular momentum. In the case of the latter definition, the planet Neptune and its satellite Triton would have their 'north' poles in opposite hemispheres because Triton's angular momentum vector is in the hemisphere opposite from that of Neptune's rotation angular momentum. The IAU resolutions have been somewhat controversial in some quarters ever since their adoption. A Working Group has periodically updated the recommended values of planet and satellite poles and rotation rates in accordance with the IAU definition of north and the IAU definition of prime meridian. Neither system is completely satisfactory in the perception of all scientists, and some confusion has been generated by publishing data in the two different systems. In this paper we review the IAU definitions of north and of the location of prime meridian and we present the algorithm which has been employed in determining the rotational parameters of the natural satellites. The IAU definition of the prime meridian contains some ambiguities which in practice have been 'specified' by the numerical values published by the IAU working group but which have not yet been explicitly documented. The purpose of this paper is to explicitly document the algorithm employed by the IAU working group in specifying satellite poles and rotation rates. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lieske, JH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 301-150, Pasadena, CA 91109 USA. NR 21 TC 0 Z9 0 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0923-2958 J9 CELEST MECH DYN ASTR JI Celest. Mech. Dyn. Astron. PD NOV PY 1993 VL 57 IS 3 BP 473 EP 491 DI 10.1007/BF00695716 PG 19 WC Astronomy & Astrophysics; Mathematics, Interdisciplinary Applications SC Astronomy & Astrophysics; Mathematics GA V05NL UT WOS:000207132600004 ER PT J AU TORRANCE, P AF TORRANCE, P TI NOT A CHICKEN-AND-EGG STORY SO CHEMICAL ENGINEERING LA English DT Letter RP TORRANCE, P (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 SN 0009-2460 J9 CHEM ENG-NEW YORK JI Chem. Eng. PD NOV PY 1993 VL 100 IS 11 BP 10 EP 10 PG 1 WC Engineering, Chemical SC Engineering GA MH100 UT WOS:A1993MH10000005 ER PT J AU STIEGMAN, AE ECKERT, H PLETT, G KIM, SS ANDERSON, M YAVROUIAN, A AF STIEGMAN, AE ECKERT, H PLETT, G KIM, SS ANDERSON, M YAVROUIAN, A TI VANADIA SILICA XEROGELS AND NANOCOMPOSITES SO CHEMISTRY OF MATERIALS LA English DT Note ID PARTIAL OXIDATION; MOLECULAR-OXYGEN; GEL; COMPOSITE; GLASSES; METHANE; OXIDE C1 UNIV CALIF SANTA BARBARA,DEPT CHEM,GOLETA,CA 93106. RP STIEGMAN, AE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Eckert, Hellmut/G-3176-2012 NR 42 TC 55 Z9 57 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD NOV PY 1993 VL 5 IS 11 BP 1591 EP 1594 DI 10.1021/cm00035a001 PG 4 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA MJ090 UT WOS:A1993MJ09000001 ER PT J AU PALEY, MS FRAZIER, DO MCMANUS, SP ZUTAUT, SE SANGHADASA, M AF PALEY, MS FRAZIER, DO MCMANUS, SP ZUTAUT, SE SANGHADASA, M TI DIACETYLENE AND POLYDIACETYLENE DERIVATIVES OF 2-METHYL-4-NITROANILINE OR 2ND-HARMONIC GENERATION SO CHEMISTRY OF MATERIALS LA English DT Article ID THIN-FILMS; OPTICAL-PROPERTIES; POLY(DIACETYLENES); GROWTH; MONOMERS; MODEL AB A novel diacetylene derivative of 2-methyl-4-nitroaniline (MNA), a well-known material for second-harmonic generation (SHG), is synthesized. This monomer (diacetylene methylnitroaniline, DAMNA) is characterized by means of the Kurtz technique at 1064 nm and is found to have an SHG powder efficiency 62.5 % that of MNA itself. Thin crystalline films of DAMNA are grown onto quartz, Teflon, and Kapton substrates by means of vapor deposition in vacuum. These films are then polymerized in the solid state by exposure to long-wavelength UV radiation to give crystalline polydiacetylene thin films (PDAMNA). The films are next characterized for SHG, using an unpolymerized DAMNA film as a reference. Interestingly, films grown onto Teflon exhibit greater orientation and significantly greater SHG than those grown onto quartz and Kapton. This result is promising in that it demonstrates the potential of PDAMNA as both a crystalline and polymeric material for SHG applications, in which highly oriented thin films are desired. Computational modeling (using AM1) is also carried out on DAMNA and is compared to the experimental results. C1 UNIV ALABAMA,MAT SCI PROGRAM,HUNTSVILLE,AL 35895. RP PALEY, MS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 21 TC 14 Z9 14 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD NOV PY 1993 VL 5 IS 11 BP 1641 EP 1644 DI 10.1021/cm00035a010 PG 4 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA MJ090 UT WOS:A1993MJ09000010 ER PT J AU ZAK, M AF ZAK, M TI IRREVERSIBILITY AND CREATIVITY IN NEURODYNAMICS SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Article ID NEURAL NETWORKS; TURBULENCE; MEMORY; CHAOS AB This paper presents an approach to formalization of the concept of creativity in connection with the new architecture of neural networks based upon non-Lipschitzian dynamics. A new nonlinear phenomenon-terminal chaos caused by failure of the Lipschitz condition at equilibrium points of dynamical systems is introduced. It is shown that terminal chaos has a well-organized probabilistic structure which can be predicted and controlled. This gives an opportunity to exploit this phenomenon for information processing. It appears that chaotic states of neurons activity are associated with a higher level of cognitive processes such as generalization and abstraction. The relationship between creativity, irreversibility and unpredictability in neurodynamics are discussed. The theory is illustrated by examples. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,NEURAL COMPUTAT & NONLINEAR SCI GRP,PASADENA,CA 91109. NR 19 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP 401 EP 418 DI 10.1016/0045-7906(93)90017-L PG 18 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700002 ER PT J AU TAWEL, R AF TAWEL, R TI LEARNING IN ANALOG NEURAL-NETWORK HARDWARE SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Article AB Hardware implementations of neuroprocessor architectures are currently enjoying commercial availability for the first time ever. This development has been caused in part by the requirement for real-time solutions to time critical neural network applications. Massively parallel asynchronous neuromorphic representations are inherently capable of very high computational speeds when properly cast in the ''right stuff'', i.e. electronic or optoelectronic hardware. However, hardware based learning in such systems is still at a primitive stage. In practise, simulations are typically performed in software, and the resulting synaptic weight capturing the input-output transformation subsequently quantized and down-loaded onto the neural hardware. However, because of the numerous discrepancies between the software and hardware, such systems are inherently poor in performance. In this paper we report on chip-in-the-loop learning systems assembled from custom analog ''building blocks'' hardware. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,MICRODEVICES LAB,PASADENA,CA 91109. NR 33 TC 0 Z9 0 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP 453 EP 467 DI 10.1016/0045-7906(93)90021-I PG 15 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700006 ER PT J AU TOOMARIAN, N AF TOOMARIAN, N TI MULTITARGET TRACKING IN DENSE THREAT ENVIRONMENTS SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Article AB A new approach to multi-target tracking is presented for the mid-course stage of the Strategic Defense Initiative (SDI). This approach is based upon a continuum representation of a cluster of flying objects. The velocities of the flying objects are assumed to be embedded into a smooth velocity field. This assumption is based upon the impossibility of encounters in a high-density cluster between the flying objects. Therefore, the problem is reduced to that of identifying a moving continuum based upon consecutive time frame observations. In contradistinction to the previous approaches, here each target is considered as a center of a small continuous neighborhood subjected to a local-affine transformation, and therefore, the target trajectories do not mix. Obviously, their mixture in plane of sensor view is apparent. The approach is illustrated by an example. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. NR 8 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP 469 EP 479 DI 10.1016/0045-7906(93)90022-J PG 11 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700007 ER PT J AU VENKATARAMAN, ST HAYATI, S AF VENKATARAMAN, ST HAYATI, S TI SHARED TRADED CONTROL OF TELEROBOTS UNDER TIME-DELAY SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Article AB In this paper, we describe the design and development of a robotic system with Traded and Shared Control capability. This system will be able to accept and execute commands both from a hand controller (teleoperation) and an autonomous system, or a combination of the two. We begin by justifying the need for such a system, especially for space applications. Our efforts are directed towards building a system that retains the advantages of each mode (autonomous or teleoperated), while allowing for its shortcomings to be overcome by the other. We consider a two-tiered robotic system here; the higher generates task-level programs, and the lower, actually executes them on a robot. Shared control is implemented in both of these two levels. The operator can provide task level commands to either modify or supplement the autonomous task planner as well as modify or influence the position and force trajectories at the servo level. Finally, a control architecture is presented to realize the above notions of Traded and Shared Control. This includes a description of the hardware and the software of the system. C1 JET PROP LAB,PASADENA,CA 91109. NR 11 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP 481 EP 494 DI 10.1016/0045-7906(93)90023-K PG 14 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700008 ER PT J AU BARHEN, J GULATI, S AF BARHEN, J GULATI, S TI CHAOTIC RELAXATION IN CONCURRENTLY ASYNCHRONOUS NEURAL NETWORKS SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Article ID TIME-SERIES; SYSTEMS; MODEL AB In this paper we analyze a fundamental issue which directly impacts the scalability of current theoretical neural network models to applicative embodiments, in both software as well as hardware. This pertains to the inherent and unavoidable concurrent asynchronicity of emerging fine-grained computational ensembles and the consequent chaotic manifestations in the absence of proper conditioning. The latter concern is particularly significant since the computational inertia of neural networks in general and our dynamical learning formalisms manifests itself substantially, only in massively parallel hardware-optical, VLSI or opto-electronic. We introduce a mathematical framework for systematically reconditioning additive-type models and derive a neuro-operator, based on the chaotic relaxation paradigm whose resulting dynamics are neither ''concurrently'' synchronous nor ''sequentially'' asynchronous. Necessary and sufficient conditions guaranteeing concurrent asynchronous convergence are established in terms of contracting operators. Lyapunov exponents are also computed to characterize the network dynamics and to ensure that throughput-limiting ''emergent computational chaos'' behavior in models reconditioned with concurrently asynchronous algorithms was eliminated. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. NR 29 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP 507 EP 523 DI 10.1016/0045-7906(93)90025-M PG 17 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700010 ER PT J AU RAO, NSV GULATI, S IYENGAR, SS MADAN, RN AF RAO, NSV GULATI, S IYENGAR, SS MADAN, RN TI PARALLEL AND DISTRIBUTED COMPUTING FOR INTELLIGENT SYSTEMS SO COMPUTERS & ELECTRICAL ENGINEERING LA English DT Editorial Material C1 OLD DOMINION UNIV,DEPT COMP SCI,NORFOLK,VA 23529. JET PROP LAB,PASADENA,CA 91109. LOUISIANA STATE UNIV,DEPT COMP SCI,BATON ROUGE,LA 70803. OFF NAVAL RES,DIV ELECTR,ARLINGTON,VA 22217. LOUISIANA STATE UNIV,ROBOT RES LAB,BATON ROUGE,LA 70803. NR 8 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7906 J9 COMPUT ELECTR ENG JI Comput. Electr. Eng. PD NOV PY 1993 VL 19 IS 6 BP R5 EP R8 PG 4 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MG567 UT WOS:A1993MG56700001 ER PT J AU BRYSON, S AF BRYSON, S TI VIRTUAL-REALITY IN SCIENTIFIC VISUALIZATION SO COMPUTERS & GRAPHICS LA English DT Article AB The use of virtual environments in scientific visualization is discussed. Successful examples are surveyed in depth. Lessons about the usefulness and applicability of virtual environments to scientific visualization are drawn. Lessons learned from these applications for the development of virtual environments are also drawn. Difficulties in the application of virtual environments to scientific visualization are discussed. Problems encountered in virtual reality implementations of scientific visualization systems are briefly surveyed. Possible futures are briefly examined. RP BRYSON, S (reprint author), NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT SYST,APPL RES BRANCH,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 10 TC 7 Z9 7 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0097-8493 J9 COMPUT GRAPH JI Comput. Graph. PD NOV-DEC PY 1993 VL 17 IS 6 BP 679 EP 685 DI 10.1016/0097-8493(93)90117-R PG 7 WC Computer Science, Software Engineering SC Computer Science GA MP685 UT WOS:A1993MP68500008 ER PT J AU VOELLMER, G AF VOELLMER, G TI A PASSIVE END-EFFECTOR CHANGE-OUT MECHANISM FOR ON-ORBIT ROBOTIC SERVICING SO COMPUTERS IN INDUSTRY LA English DT Article DE END EFFECTOR CHANGE-OUT MECHANISM; TOOL EXCHANGE; ROBOTICS; ZERO GRAVITY AB This paper presents an end effector change-out mechanism (EECM) which embodies all the features and satisfies all the requirements necessary to perform zero-gravity robotic tool exchanges safely. Analysis of the mechanism has shown the exchange procedure to be sufficiently secure, and the latch mechanisms to have sufficient strength margins, to meet space flight requirements. Laboratory testing of the hardware has verified that the exchange procedure is secure and smooth, and has validated the operator feedback scheme. The final EECM design has proved so simple and easy to integrate that it is believed to have commercial potential. C1 NATL AERONAUT & SPACE ADM,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 0 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-3615 J9 COMPUT IND JI Comput. Ind. PD NOV PY 1993 VL 23 IS 1-2 BP 65 EP 74 DI 10.1016/0166-3615(93)90116-I PG 10 WC Computer Science, Interdisciplinary Applications SC Computer Science GA MU596 UT WOS:A1993MU59600007 ER PT J AU POPE, KO OCAMPO, AC DULLER, CE AF POPE, KO OCAMPO, AC DULLER, CE TI SURFICIAL GEOLOGY OF THE CHICXULUB IMPACT CRATER, YUCATAN, MEXICO SO EARTH MOON AND PLANETS LA English DT Article ID CRETACEOUS-TERTIARY BOUNDARY; MELT ROCK; DISSOLUTION; PENINSULA; DEPOSITS; BEARING; SITES AB The Chicxulub impact crater in northwestern Yucatan, Mexico is the primary candidate for the proposed impact that caused mass extinctions at the end of the Cretaceous Period. The crater is buried by up to a kilometer of Tertiary sediment and the most prominent surface expression is a ring of sink holes, known locally as cenotes, mapped with Landsat imagery. This 165 +/- 5 km diameter Cenote Ring demarcates a boundary between unfractured limestones inside the ring, and fractured limestones outside. The boundary forms a barrier to lateral ground water migration, resulting in increased flows, dissolution, and collapse thus forming the cenotes. The subsurface geology indicates that the fracturing that created the Cenote Ring is related to slumping in the rim of the buried crater, differential thicknesses in the rocks overlying the crater, or solution collapse within porous impact deposits. The Cenote Ring provides the most accurate position of the Chicxulub crater's center, and the associated faults, fractures, and stratigraphy indicate that the crater may be approximately 240 km in diameter. C1 NASA,AMES RES CTR,MS 2424,MOFFETT FIELD,CA 94035. JET PROP LAB,MS 183601,PASADENA,CA 91109. RP POPE, KO (reprint author), GEO ECO ARC RES,2222 FOOTHILL BLVD,SUITE E-272,LA CANADA FLINTRIDGE,CA 91011, USA. NR 38 TC 42 Z9 43 U1 1 U2 12 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD NOV PY 1993 VL 63 IS 2 BP 93 EP 104 DI 10.1007/BF00575099 PG 12 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA MY040 UT WOS:A1993MY04000002 PM 11539441 ER PT J AU CHANG, SW AF CHANG, SW TI ANALYSIS OF FISHERY RESOURCES - POTENTIAL RISK FROM SEWAGE-SLUDGE DUMPING AT THE DEEP-WATER DUMPSITE OFF NEW-JERSEY SO FISHERY BULLETIN LA English DT Article ID NEW-YORK BIGHT; REPRODUCTION; SITE AB Analytical and statistical procedures were applied to bottom trawl survey data in tests of hypotheses about potential effects of sewage sludge dumping at a 106-mile dumpsite (106-MDS) off New Jersey on fishery resources assessed on the continental shelf and upper slope. Sludge dumping, even in deep ocean waters, was not discounted as one of several ecological and environmental perturbations influencing these resources measured as temporal, spatial, and seasonal differences in abundance. Species abundances of silver and red hakes (Merluccius bilinearis and Urophycis chuss), summer flounder (Paralichthys dentatus), goosefish (Lophius americanus), and black sea bass (Centropristis striata) declined significantly over temporal and spatial scales during the disposal of contaminant-laden sewage sludge at the deepwater 106-MDS. There was also a decline in the array of all aggregated species, but to a lesser degree. Results of these analyses of assessment data are considered in relation to effects of ocean dumping in shallow waters at the southern California sewage outfalls and in the New York Bight apex, and in relation to increased contamination of the ecosystem around the 106-MDS. Further, large-scale coordination of environmental research surveys with fishery resource assessments would allow tests of more specific hypotheses and allow a more definitive interpretation of offshore resource population data as presented here. RP CHANG, SW (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 64 TC 1 Z9 1 U1 1 U2 2 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD NOV PY 1993 VL 91 IS 4 BP 594 EP 610 PG 17 WC Fisheries SC Fisheries GA ML937 UT WOS:A1993ML93700002 ER PT J AU BRILL, RW HOLTS, DB AF BRILL, RW HOLTS, DB TI EFFECTS OF ENTANGLEMENT AND ESCAPE FROM HIGH-SEAS DRIFTNETS ON RATES OF NATURAL MORTALITY OF NORTH PACIFIC ALBACORE, THUNNUS-ALALUNGA SO FISHERY BULLETIN LA English DT Note ID RNA-DNA RATIO; CONDITION INDEXES; OTOLITH WEIGHT; FISH; GROWTH; AGE; LEUCOCRIT; HEALTH C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,LA JOLLA LAB,LA JOLLA,CA 92038. RP BRILL, RW (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 33 TC 0 Z9 0 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD NOV PY 1993 VL 91 IS 4 BP 798 EP 803 PG 6 WC Fisheries SC Fisheries GA ML937 UT WOS:A1993ML93700018 ER PT J AU SCHULZE, N AF SCHULZE, N TI SUMMARY OF 7TH UNITED-STATES-JAPAN D-HE-3 WORKSHOP, CHAMPAIGN, ILLINOIS, MARCH 16-18, 1993 SO FUSION TECHNOLOGY LA English DT Editorial Material RP SCHULZE, N (reprint author), NASA HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER NUCLEAR SOCIETY PI LA GRANGE PK PA 555 N KENSINGTON AVENUE, LA GRANGE PK, IL 60525 SN 0748-1896 J9 FUSION TECHNOL JI Fusion Technol. PD NOV PY 1993 VL 24 IS 3 BP 341 EP 344 PG 4 WC Nuclear Science & Technology SC Nuclear Science & Technology GA ME115 UT WOS:A1993ME11500014 ER PT J AU SHU, FH JOHNSTONE, D HOLLENBACH, D AF SHU, FH JOHNSTONE, D HOLLENBACH, D TI PHOTOEVAPORATION OF THE SOLAR NEBULA AND THE FORMATION OF THE GIANT PLANETS SO ICARUS LA English DT Article; Proceedings Paper CT Planet Formation Program of the Institute-for-Theoretical-Physics CY JUL-DEC -, 1992 CL UNIV CALIF SANTA BARBARA, SANTA BARBARA, CA SP INST THEORET PHYS HO UNIV CALIF SANTA BARBARA ID T-TAURI STARS; ECCENTRIC GRAVITATIONAL INSTABILITIES; TIDAL INTERACTION; ACCRETION DISKS; PROTOPLANETARY DISK; ANGULAR-MOMENTUM; OUTER PLANETS; PLANETESIMALS; EVOLUTION; ACCUMULATION C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SHU, FH (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720, USA. NR 74 TC 107 Z9 107 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1993 VL 106 IS 1 BP 92 EP 101 DI 10.1006/icar.1993.1160 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MM299 UT WOS:A1993MM29900008 ER PT J AU CUZZI, JN DOBROVOLSKIS, AR CHAMPNEY, JM AF CUZZI, JN DOBROVOLSKIS, AR CHAMPNEY, JM TI PARTICLE GAS-DYNAMICS IN THE MIDPLANE OF A PROTOPLANETARY NEBULA SO ICARUS LA English DT Article; Proceedings Paper CT Planet Formation Program of the Institute-for-Theoretical-Physics CY JUL-DEC -, 1992 CL UNIV CALIF SANTA BARBARA, SANTA BARBARA, CA SP INST THEORET PHYS HO UNIV CALIF SANTA BARBARA ID PRIMORDIAL SOLAR NEBULA; DIRECT NUMERICAL SIMULATIONS; TURBULENT EKMAN LAYER; ISOTROPIC TURBULENCE; CIRCUMSTELLAR DISKS; PLANETARY ACCRETION; PLANETESIMALS; DUST; CONVECTION; EVOLUTION C1 UNIV CALIF SANTA CRUZ,SANTA CRUZ,CA 95064. RP CUZZI, JN (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 89 TC 268 Z9 269 U1 0 U2 8 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1993 VL 106 IS 1 BP 102 EP 134 DI 10.1006/icar.1993.1161 PG 33 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MM299 UT WOS:A1993MM29900009 ER PT J AU WARD, WR AF WARD, WR TI DENSITY WAVES IN THE SOLAR NEBULA - PLANETESIMAL VELOCITIES SO ICARUS LA English DT Article; Proceedings Paper CT Planet Formation Program of the Institute-for-Theoretical-Physics CY JUL-DEC -, 1992 CL UNIV CALIF SANTA BARBARA, SANTA BARBARA, CA SP INST THEORET PHYS HO UNIV CALIF SANTA BARBARA ID GRAVITATIONAL-FIELD; ACCRETION; ACCUMULATION; GROWTH; RINGS; GAS; ECCENTRICITIES; PROTOPLANET; EVOLUTION; PLANETS C1 JET PROP LAB,PASADENA,CA 91109. SAN JUAN CAPISTRANO RES INST,SAN JUAN CAPISTRANO,CA. NR 49 TC 48 Z9 49 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1993 VL 106 IS 1 BP 274 EP 287 DI 10.1006/icar.1993.1171 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MM299 UT WOS:A1993MM29900019 ER PT J AU TREMAINE, S DONES, L AF TREMAINE, S DONES, L TI ON THE STATISTICAL DISTRIBUTION OF MASSIVE IMPACTORS SO ICARUS LA English DT Article; Proceedings Paper CT Planet Formation Program of the Institute-for-Theoretical-Physics CY JUL-DEC -, 1992 CL UNIV CALIF SANTA BARBARA, SANTA BARBARA, CA SP INST THEORET PHYS HO UNIV CALIF SANTA BARBARA ID TERRESTRIAL PLANETS; ORIGIN; HYPOTHESIS; EVOLUTION; MANTLE; EARTH; MOON C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP TREMAINE, S (reprint author), UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,MCLENNAN LABS,60 ST GEORGE ST,TORONTO M5S 1A7,ONTARIO,CANADA. RI Tremaine, Scott/M-4281-2015 OI Tremaine, Scott/0000-0002-0278-7180 NR 27 TC 10 Z9 11 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1993 VL 106 IS 1 BP 335 EP 341 DI 10.1006/icar.1993.1175 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MM299 UT WOS:A1993MM29900023 ER PT J AU NAYAK, DK WOO, JCS YABIKU, GK MACWILLIAMS, KP PARK, JS WANG, KL AF NAYAK, DK WOO, JCS YABIKU, GK MACWILLIAMS, KP PARK, JS WANG, KL TI HIGH-MOBILITY GESI PMOS ON SIMOX SO IEEE ELECTRON DEVICE LETTERS LA English DT Article ID HETEROSTRUCTURES; LAYERS AB A new p-channel GeSi-SIMOX device is presented. The device consists of a Si/Ge0.3Si0.7/Si channel, which is grown pseudomorphically on a SIMOX substrate. Due to reduced vertical electric field and band bending at the surface of a GeSi-SIMOX device, hole confinement in the buried channel is improved over that of a GeSi-bulk device. Experimentally, the effective channel mobility of this device is found to be 90% higher than that of an identically processed conventional SIMOX device. C1 UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,SOLID STATE ELECTR LAB,LOS ANGELES,CA 90024. AEROSP CORP,EL SEGUNDO,CA 90245. JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,DEVICE RES LAB,LOS ANGELES,CA 90024. NR 14 TC 34 Z9 35 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD NOV PY 1993 VL 14 IS 11 BP 520 EP 522 DI 10.1109/55.258002 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA MF783 UT WOS:A1993MF78300005 ER PT J AU FRIEDMAN, GL AF FRIEDMAN, GL TI THE TRUSTWORTHY DIGITAL CAMERA - RESTORING CREDIBILITY TO THE PHOTOGRAPHIC IMAGE SO IEEE TRANSACTIONS ON CONSUMER ELECTRONICS LA English DT Article RP FRIEDMAN, GL (reprint author), CALTECH,JET PROP LAB,ADV ENGN & PROTOTYPE GRP,PASADENA,CA 91109, USA. NR 6 TC 152 Z9 168 U1 1 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0098-3063 J9 IEEE T CONSUM ELECTR JI IEEE Trans. Consum. Electron. PD NOV PY 1993 VL 39 IS 4 BP 905 EP 910 DI 10.1109/30.267415 PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA MM709 UT WOS:A1993MM70900025 ER PT J AU YOUNG, PG ALTEROVITZ, SA MENA, RA SMITH, ED AF YOUNG, PG ALTEROVITZ, SA MENA, RA SMITH, ED TI RF PROPERTIES OF EPITAXIAL LIFT-OFF HEMT DEVICES SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID GAAS-MESFET; SUBSTRATE; DC AB Epitaxial layers containing GaAs HEMT and P-HEMT structures have been lifted-off the GaAs substrate and attached to other host substrates using an AlAs parting layer. The devices were on-wafer RF probed before and after the lift-off step showing no degradation in the measured S-parameters. The maximum stable gain indicates a low frequency enhancement of the gain of 1-2 dB with some devices showing an enhancement of F(max). F(T) consistently shows an increase of 12-20 % for all lifted-off HEMT structures. Comparison of the Hall measurements and small signal models show that the gain is improved and this is most probably associated with an enhanced carrier concentration. C1 NASA,LEWIS RES CTR,SOLID STATE TECHNOL BRANCH,CLEVELAND,OH 44135. RP YOUNG, PG (reprint author), UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606, USA. NR 10 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD NOV PY 1993 VL 40 IS 11 BP 1905 EP 1909 DI 10.1109/16.239727 PG 5 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA ME783 UT WOS:A1993ME78300001 ER PT J AU JAIN, RK FLOOD, DJ AF JAIN, RK FLOOD, DJ TI INFLUENCE OF THE DISLOCATION DENSITY ON THE PERFORMANCE OF HETEROEPITAXIAL INDIUM-PHOSPHIDE SOLAR-CELLS SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID SURFACE RECOMBINATION VELOCITY; CHEMICAL VAPOR-DEPOSITION; INP; SI; GAAS; GROWTH AB Heteroepitaxial indium phosphide solar cells developed to date have low efficiency due to misfit dislocations. Dislocations act as recombination centers and strongly influence the solar cell performance. Calculations have been made to study the dependence of heteroepitaxial InP solar cell efficiency on dislocation density. The effects of surface recombination velocity and cell emitter thickness are also considered. Calculated results are compared with the available experimental results on representative InP solar cells. It is shown that heteroepitaxial InP cells with over 20% AMO efficiency could be fabricated if dislocation density can be reduced to < 10(5) cm-2 and the surface recombination velocity reduced to < 10(5) cm/s. RP JAIN, RK (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 35 TC 9 Z9 9 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9383 EI 1557-9646 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD NOV PY 1993 VL 40 IS 11 BP 1928 EP 1934 DI 10.1109/16.239730 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA ME783 UT WOS:A1993ME78300004 ER PT J AU NEUDECK, PG LARKIN, DJ POWELL, JA MATUS, LG AF NEUDECK, PG LARKIN, DJ POWELL, JA MATUS, LG TI HIGH-VOLTAGE 6H-SIC RECTIFIERS - PROSPECTS AND PROGRESS SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Meeting Abstract C1 NASA,CLEVELAND,OH 44135. NR 1 TC 3 Z9 3 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD NOV PY 1993 VL 40 IS 11 BP 2130 EP 2130 DI 10.1109/16.239811 PG 1 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA ME783 UT WOS:A1993ME78300086 ER PT J AU FREHLICH, R AF FREHLICH, R TI CRAMER-RAO BOUND FOR GAUSSIAN RANDOM-PROCESSES AND APPLICATIONS TO RADAR PROCESSING OF ATMOSPHERIC SIGNALS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID DOPPLER SPECTRA; MAXIMUM-ENTROPY; WEATHER ECHOES; WIDTH; COMPONENTS AB Calculations of the exact Cramer-Rao Bound (CRB) for unbiased estimates of the mean frequency, signal power, and spectral width of Doppler radar/lidar signals (a Gaussian random process) are presented. Approximate CRB's are derived using the Discrete Fourier Transform (DFT). These approximate results are equal to the exact CRB when the DFT coefficients are mutually uncorrelated. Previous high SNR limits for CRB's are shown to be inaccurate because the discrete summations cannot be approximated with integration. The performance of an approximate maximum likelihood estimator for mean frequency approaches the exact CRB for moderate signal to noise ratio and moderate spectral width. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ELECTROOPT BRANCH EB54,HUNTSVILLE,AL 35812. NR 35 TC 29 Z9 33 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1993 VL 31 IS 6 BP 1123 EP 1131 DI 10.1109/36.317450 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MQ906 UT WOS:A1993MQ90600001 ER PT J AU KEALY, PS HOOK, SJ AF KEALY, PS HOOK, SJ TI SEPARATING TEMPERATURE AND EMISSIVITY IN THERMAL INFRARED MULTISPECTRAL SCANNER DATA - IMPLICATIONS FOR RECOVERING LAND-SURFACE TEMPERATURES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SEA-SURFACE; SATELLITE; REGION; IMAGES; MODEL AB This paper evaluates the accuracy of three techniques for recovering surface kinetic temperature from multispectral thermal infrared data acquired over land. The three techniques are the reference channel method, the emissivity normalization method, and the alpha emissivity method. The first two methods have been widely used with data from the thermal infrared multispectral scanner (TIMS); the third is a new method. The methods were used to recover the temperature of artificial radiance data derived from a wide variety of materials and convolved with the filter response functions of TIMS and the advanced spaceborne thermal emission reflectance radiometer (ASTER). ASTER is scheduled to fly on the first EOS platform and will have five channels in the thermal infrared with a spatial resolution of 90 m. The results indicate that the emissivity normalization and alpha emissivity techniques are the most accurate, and recover the temperature of the majority of the artificial radiance spectra to within 1.5K; the reference channel method produces less accurate results. The primary advantage of the alpha emissivity method over emissivity normalization method is that it works well in terrains of widely varying emissivities, e.g., those dominated by vegetation and igneous rocks' By contrast, the emissivity normalization method works well only if the emissivity used for normalization is close to the maximum emissivity of the spectra in the scene. The temperature errors for the ASTER convolved data are greater for the emissivity normalization and reference channel methods than for the data convolved to TIMS. The alpha emissivity method is equally accurate for both instruments. In summary, the new alpha emissivity method described herein, should permit more accurate recovery of land surface temperatures from remotely sensed multispectral thermal infrared radiance data, for materials with widely varying and unknown emissivities. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP EUROPEAN SPACE AGCY, ESTEC, DIV EARTH SCI, 2200 AG NOORDWIJK, NETHERLANDS. NR 25 TC 141 Z9 146 U1 0 U2 17 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1993 VL 31 IS 6 BP 1155 EP 1164 DI 10.1109/36.317447 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MQ906 UT WOS:A1993MQ90600004 ER PT J AU BRANGER, H RAMAMONJIARISOA, A BLIVEN, LF AF BRANGER, H RAMAMONJIARISOA, A BLIVEN, LF TI A KU-BAND LABORATORY EXPERIMENT ON THE ELECTROMAGNETIC BIAS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SEA-STATE BIAS; NONLINEAR RANDOM SEA; RADAR ALTIMETRY; GEOSAT ALTIMETER; RANGE MEASUREMENTS; JOINT DISTRIBUTION; SURFACE ELEVATION; ROUGH-SURFACE; WATER-WAVES; WIND AB Sea-surface electromagnetic bias (EM bias), the difference between the mean reflecting surface and the geometric mean sea level, must be accurately determined to realize the full potential of satellite altimeters. A uniformly valid algorithm relating the normalized (or nondimensional) EM bias, i.e., ''bias/significant wave height,'' to physical variables has not yet been established, so we conducted laboratory experiments to guide model development. Simultaneous and collocated measurements of surface topography and altimeter back-scattered power were made in the large IMST wind-wave facility for a wide range of wind and mechanically generated wave conditions. A small microwave footprint on the water surface was produced by a focused-beam 13.5 GHz radar system that has a high signal-to-noise ratio. Consequently specular facets are easily identifiable and the data show that troughs are on average better reflectors than crests. Dimensional relations seldom yield robust algorithms and in fact, although rather high correlation is found between normalized EM bias and either wind speed or wave height, the laboratory coefficients are considerably greater than those of in situ algorithms. Nondimensional parameterization is more useful for deriving scaling laws, and when the normalized EM bias is displayed as a function of wave height skewness or wave age, laboratory and field data converge into consistent trends. In particular, normalized bias decreases with wave age, but unfortunately, even the wave age model does not account for the effects of mechanically generated waves, which produce appreciable scatter relative to the pure wind cases. Thus, we propose a two-parameter model using 1) a nondimensional wave height, which is computed for local winds, and 2) a significant slope, which is computed for nonlocally generated waves. Analysis of the laboratory data shows that the normalized EM bias for mixed conditions is well modeled as a product of these two parameters. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. RP BRANGER, H (reprint author), INST MECAN STAT TURBULENCE,12 LECLERC AV,F-13003 MARSEILLE,FRANCE. RI bliven, francis/E-1450-2012; Branger, Hubert/E-1879-2016 OI Branger, Hubert/0000-0002-9888-681X NR 51 TC 8 Z9 8 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1993 VL 31 IS 6 BP 1165 EP 1179 DI 10.1109/36.317446 PG 15 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MQ906 UT WOS:A1993MQ90600005 ER PT J AU YUEH, SH NGHIEM, SV KWOK, R AF YUEH, SH NGHIEM, SV KWOK, R TI SYMMETRIZATION OF CROSS-POLARIZED RESPONSES IN POLARIMETRIC RADAR IMAGES USING RECIPROCITY SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID CALIBRATION AB A new method for symmetrizing polarimetric scattering matrices is applied to the polarimetric synthetic aperture radar (SAR) images acquired over Mt. Shasta. This method symmetrizes the cross-polarized responses in the polarimetric images using a 2 x 2 matrix derived from the image itself based on the reciprocal property of natural distributed targets. The covariance parameters of the in-scene trihedral reflectors are presented to demonstrate the effectivenes of this method. The results are also compared with those obtained by the symmetrization technique employed by POLCAL, before and after crosstalk removal. Before the channel crosstalk was removed from the images, there were no significant differences between the results obtained by the POLCAL method and the new method for the covariance parameters of trihedral reflectors. However, after the images were further processed by a crosstalk removal algorithm using distributed targets with reflection symmetry, the results indicate that the new symmetrization method outperforms the method employed by POLCAL for data symmetrization. It is shown that when the crosstalk is small, both methods offer comparable performance, while if the crosstalk is not negligible, the images symmetrized by the new method allow the crosstalk to be reduced to the noise floor defined by data compression algorithm. RP YUEH, SH (reprint author), JET PROP LAB,MAIL STOP 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 11 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1993 VL 31 IS 6 BP 1180 EP 1185 DI 10.1109/36.317445 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MQ906 UT WOS:A1993MQ90600006 ER PT J AU OPALSKY, D HUMPHREY, FB AF OPALSKY, D HUMPHREY, FB TI MEASUREMENT OF THE HBL NUCLEATION FIELD AND VBL COERCIVITY IN MAGNETIC GARNET-FILMS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1993 IEEE International Magnetics Conference (INTERMAG 93) CY APR 13-16, 1993 CL STOCKHOLM, SWEDEN SP IEEE, MAGNET SOC AB A sampling optical microscope is integrated with computer controlled instrumentation and a digital image processor. The system is used to make quantitative measurements of magnetic domain wall motion. The system can measure the average stripe width, over an 8.7 mum length, with 0.003 mum precision and 2 ns temporal resolution. With this system, the threshold for horizontal Bloch line (HBL) nucleation and the coercivity of a vertical Bloch line (VBL) is measured in straight walls in bubble garnet material. C1 BOSTON UNIV,DEPT ECS ENG,BOSTON,MA 02215. RP OPALSKY, D (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 2 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD NOV PY 1993 VL 29 IS 6 BP 2512 EP 2515 DI 10.1109/20.280970 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA MQ945 UT WOS:A1993MQ94500052 ER PT J AU KATTI, RR DOOLEY, JA MENG, A AF KATTI, RR DOOLEY, JA MENG, A TI PARTIALLY GROOVED DOMAIN STABILIZATION STRUCTURES FOR VERTICAL BLOCH LINE MEMORY SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1993 IEEE International Magnetics Conference (INTERMAG 93) CY APR 13-16, 1993 CL STOCKHOLM, SWEDEN SP IEEE, MAGNET SOC AB Bias field stability ranges were measured and numerically simulated for magnetic domains in garnets stabilized by partially grooved rectangular and ring grooves. Simulation results agree favorably with experimental results when finite slope effects of the groove walls are included. As bias fields increase, rectangular and ring domains both destabilize through stripe head recession. As bias fields decrease, destabilization in rectangular and ring domains occur by runout and midstripe domain buckling, respectively. While ring domains-are stable at lower bias fields than rectangular domains, bias field stability ranges are approximately equal; so for the same partial grooving depth, rectangular domains are preferred because they offer higher storage density potential for Vertical Bloch Line storage as long as bit propagation margins at stripe ends are sufficient. RP KATTI, RR (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD NOV PY 1993 VL 29 IS 6 BP 2578 EP 2580 DI 10.1109/20.280948 PN 1 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA MQ945 UT WOS:A1993MQ94500074 ER PT J AU ROHRER, NJ VALCO, GJ BHASIN, KB AF ROHRER, NJ VALCO, GJ BHASIN, KB TI HYBRID HIGH-TEMPERATURE SUPERCONDUCTOR/GAAS 10 GHZ MICROWAVE-OSCILLATOR - TEMPERATURE AND BIAS EFFECTS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Hybrid YBa2Cu3O7-x superconductor/GaAs microwave oscillators have been designed, fabricated and characterized. The planar oscillators were built on a single 10 mm x 10 mm LaAlO3 substrate. The active elements in the hybrid oscillators were GaAs MESFETs. A ring resonator was used to select and stabilize the frequency. A superconducting ring resonator had a loaded Q at 77 K which was 8 times larger than the loaded Q of a ring resonator fabricated out of copper. S-parameters of the GaAs FET were measured at cryogenic temperatures and used to design the oscillator, which had a reflection mode configuration. The transmission lines, Tf chokes and bias lines were all fabricated from YBa2Cu3O7-x superconducting thin films. The performance of the oscillators was measured as a function of temperature. The rate of change of the frequency as a function of temperature was smaller for an oscillator patterned from a pulsed laser deposited film than for an oscillator patterned from a sputtered film. As a function of bias at 77 K, the best circuit had an output power of 11.5 dBm and a maximum efficiency of 11.7%. The power of the second harmonic was 25 dB to 35 dB below that of the fundamental, for every circuit. At 77 K, the best phase noise of the superconducting oscillators was -68 dBc/Hz at an offset frequency of 10 kHz and less than -93 dBc/Hz at an offset frequency of 100 kHz. At an offset frequency of 10 kHz, the superconducting oscillator Rad 12 dB less phase noise than the copper oscillator at 77 K. The superconducting oscillators at 77 K had 26 dB less phase noise than the copper oscillator operating at 300 K. C1 NASA,LEWIS RES CTR,DIV SPACE ELECTR,SOLID STATE TECHNOL BRANCH,CLEVELAND,OH 44135. RP ROHRER, NJ (reprint author), OHIO STATE UNIV,DEPT ELECT ENGN,COLUMBUS,OH 43210, USA. NR 12 TC 7 Z9 7 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD NOV PY 1993 VL 41 IS 11 BP 1865 EP 1871 DI 10.1109/22.273410 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA MN048 UT WOS:A1993MN04800001 ER PT J AU SIEGEL, PH DENGLER, RJ MEHDI, I OSWALD, JE BISHOP, WL CROWE, TW MATTAUCH, RJ AF SIEGEL, PH DENGLER, RJ MEHDI, I OSWALD, JE BISHOP, WL CROWE, TW MATTAUCH, RJ TI MEASUREMENTS ON A 215-GHZ SUBHARMONICALLY PUMPED WAVE-GUIDE MIXER USING PLANAR BACK-TO-BACK AIR-BRIDGE SCHOTTKY DIODES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB This paper presents design and performance data for a 215-GHz subharmonically pumped waveguide mixer using an antiparallel-pair of planar air-bridge-type GaAs Schottky-barrier diodes. The waveguide design is a prototype for a 640-GHz system and uses split-block rectangular waveguide with a 2:1 width-to-height ratio throughout. The measured mixer noise and conversion loss are below that of the best reported whisker contacted or planar-diode mixers using the subharmonic-pump configuration at this frequency. In addition, the required local oscillator power is as low as 3 mW for the unbiased diode pair, and greater than 34 dB of LO noise suppression is observed. Separate sideband calibration, using a Fabry-Perot filter, indicates that the mixer can be tuned for true double sideband response at an intermediate frequency of 1.5 GHz. Microwave scale model measurements of the waveguide mount impedances are combined with a mixer nonlinear analysis computer program to predict the mixer performance as a function of anode diameter, anode finger inductance, and pad-to-pad fringing capacitance. The computed results are in qualitative agreement with measurements, and indicate that careful optimization of all three diode parameters is necessary to significantly improve the mixer performance. C1 UNIV VIRGINIA,SEMICOND DEVICE LAB,CHARLOTTESVILLE,VA. RP SIEGEL, PH (reprint author), CALTECH,JET PROP LAB,MICROWAVE OBSERVAT SYST SECT,PASADENA,CA 91109, USA. NR 23 TC 18 Z9 18 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD NOV PY 1993 VL 41 IS 11 BP 1913 EP 1921 DI 10.1109/22.273416 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA MN048 UT WOS:A1993MN04800007 ER PT J AU ZWEBEN, M DAVIS, E DAUN, B DEALE, MJ AF ZWEBEN, M DAVIS, E DAUN, B DEALE, MJ TI SCHEDULING AND RESCHEDULING WITH ITERATIVE REPAIR SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS LA English DT Article AB The paper describes the GERRY scheduling and rescheduling system being applied to coordinate Space Shuttle Ground Processing. The system uses constraint-based iterative repair, a technique that starts with a complete but possibly flawed schedule and iteratively improves it by using constraint knowledge within repair heuristics. In this paper we explore the tradeoff between the informedness and the computational cost of several repair heuristics. It is shown empirically that some knowledge can greatly improve the convergence speed of a repair-based system, but that too much knowledge, such as the knowledge embodied within the MIN-CONFLICTS look-ahead heuristic, can overwhelm a system and result in degraded performance. C1 NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE BRANCH,MOFFETT FIELD,CA 94035. LOCKHEED SPACE OPERAT CO,LOCKHEED AI CTR,PALO ALTO,CA. NR 32 TC 50 Z9 56 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9472 J9 IEEE T SYST MAN CYB JI IEEE Trans. Syst. Man Cybern. PD NOV-DEC PY 1993 VL 23 IS 6 BP 1588 EP 1596 DI 10.1109/21.257756 PG 9 WC Computer Science, Cybernetics; Engineering, Electrical & Electronic SC Computer Science; Engineering GA MT274 UT WOS:A1993MT27400009 ER PT J AU DENSMORE, AC JAMNEJAD, V AF DENSMORE, AC JAMNEJAD, V TI A SATELLITE-TRACKING K-BAND AND K-ALPHA-BAND MOBILE VEHICLE ANTENNA SYSTEM SO IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY LA English DT Article ID ARRAY ANTENNA AB This paper describes the development of the K- and K-a-band, satellite-tracking mobile-vehicular antenna system for NASA's ACTS Mobile Terminal (AMT) project. ACTS is NASA's Advanced Communications Technology Satellite, which will be launched into its geostationary orbit in September 1993. The AMT task will make the first experimental use of the satellite soon after the satellite is operation, to demonstrate mobile communications via the satellite from a van on the road. The AMT antenna system consists of a mechanically steered small reflector antenna that uses a shared aperture for both frequency bands and fits under a radome of 23 cm diameter and 10 cm height, and an antenna controller that tracks the satellite as the vehicle moves about. The RF and mechanical characteristics of the antenna and the antenna tracking control system are discussed. Laboratory measurements of the antenna performance are presented. RP DENSMORE, AC (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 32 TC 29 Z9 30 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9545 J9 IEEE T VEH TECHNOL JI IEEE Trans. Veh. Technol. PD NOV PY 1993 VL 42 IS 4 BP 502 EP 513 DI 10.1109/25.260761 PG 12 WC Engineering, Electrical & Electronic; Telecommunications; Transportation Science & Technology SC Engineering; Telecommunications; Transportation GA ML176 UT WOS:A1993ML17600016 ER PT J AU RORVIG, ME FITZPATRICK, SJ LADOULIS, CT VITTHAL, S AF RORVIG, ME FITZPATRICK, SJ LADOULIS, CT VITTHAL, S TI A NEW MACHINE CLASSIFICATION METHOD APPLIED TO HUMAN PERIPHERAL-BLOOD LEUKOCYTES SO INFORMATION PROCESSING & MANAGEMENT LA English DT Article ID RETRIEVAL AB Human beings judge images by complex mental processes, whereas computing machines extract features. By reducing scaled human judgments and machine extracted features to a common metric space and fitting them by regression, the judgments of human experts rendered on a sample of images may be imposed on an image population to provide automatic classification. C1 UNIV TEXAS,CTR MEASUREMENT & EVALUAT,AUSTIN,TX 78712. MERCY GEN CATHOLIC HOSP,DEPT PATHOL,DARBY,PA 19023. HALLIBURTON SERV CO,RESERVOIR RES & ENGN,DUNCAN,OK 73536. RP RORVIG, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SOFTWARE TECHNOL BRANCH,PT4,HOUSTON,TX 77058, USA. NR 7 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0306-4573 J9 INFORM PROCESS MANAG JI Inf. Process. Manage. PD NOV-DEC PY 1993 VL 29 IS 6 BP 765 EP 774 DI 10.1016/0306-4573(93)90105-M PG 10 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA ME322 UT WOS:A1993ME32200007 ER PT J AU KAUFMAN, H NEAT, GW AF KAUFMAN, H NEAT, GW TI ASYMPTOTICALLY STABLE MULTIPLE-INPUT MULTIPLE-OUTPUT DIRECT MODEL-REFERENCE ADAPTIVE CONTROLLER FOR PROCESSES NOT NECESSARILY SATISFYING A POSITIVE REAL CONSTRAINT SO INTERNATIONAL JOURNAL OF CONTROL LA English DT Article AB This paper presents an asymptotic output tracking stability proof for a new modification to a direct model reference adaptive control procedure. This modification, which alleviates a very restrictive positive rear constraint, greatly expands the class of processes that can now be controlled with zero output error. This paper presents illustrative examples demonstrating the utility of the algorithm. C1 JPL,PASADENA,CA 91109. RP KAUFMAN, H (reprint author), RENSSELAER POLYTECH INST,DEPT ELECT COMP & SYST ENGN,TROY,NY 12180, USA. NR 13 TC 12 Z9 12 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0020-7179 J9 INT J CONTROL JI Int. J. Control PD NOV PY 1993 VL 58 IS 5 BP 1011 EP 1031 DI 10.1080/00207179308923041 PG 21 WC Automation & Control Systems SC Automation & Control Systems GA ME234 UT WOS:A1993ME23400003 ER PT J AU KASSEMI, M NARAGHI, MHN AF KASSEMI, M NARAGHI, MHN TI ANALYSIS OF RADIATION NATURAL-CONVECTION INTERACTIONS IN 1-G AND LOW-G ENVIRONMENTS USING THE DISCRETE EXCHANGE FACTOR METHOD SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID ENCLOSURES AB A new numerical method is presented for the analysis of combined natural convection and radiation heat transfer with applications in many engineering situations such as materials processing, combustion and fire research. Because of the recent interest in the low gravity environment of space, attention is devoted to both l-g and low-g applications. The two-dimensional mathematical model is represented by a set of coupled nonlinear integro-partial differential equations. Radiative exchange is formulated using the Discrete Exchange Factor method (DEF). This method considers point to point exchange and provides accurate results over a wide range of radiation parameters. Numerical results show that radiation significantly influences the flow and heat transfer in both low-g and l-g applications. In the low-g environment, convection is weak, and radiation can easily become the dominant heat transfer mode. It is also shown that volumetric heating by radiation gives rise to an intricate cell pattern in the top heated enclosure. C1 MANHATTAN COLL,DEPT MECH ENGN,RIVERDALE,NY 10471. RP KASSEMI, M (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 21 Z9 21 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD NOV PY 1993 VL 36 IS 17 BP 4141 EP 4149 DI 10.1016/0017-9310(93)90076-I PG 9 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA ME614 UT WOS:A1993ME61400008 ER PT J AU KIM, FD CELI, R TISCHLER, MB AF KIM, FD CELI, R TISCHLER, MB TI FORWARD FLIGHT TRIM AND FREQUENCY-RESPONSE VALIDATION OF A HELICOPTER SIMULATION-MODEL SO JOURNAL OF AIRCRAFT LA English DT Article AB This article describes a new trim procedure that includes the calculation of the steady-state response of the rotor blades and is applicable to straight flight and steady coordinated turns. This article also describes the results of a validation study for a high-order linearized model of helicopter flight dynamics that includes rotor, inflow, and actuator dynamics. The model is obtained by numerical perturbations of a nonlinear, blade element-type mathematical model. Predicted responses are compared with flight test data for two values of airspeed. The comparison is carried out in the frequency domain. Numerical simulations and comparisons with flight test data show that the trim algorithm is accurate and preserve the periodicity of the aircraft states. The results also indicate that the predictions of the on-axis frequency response are overall in good agreement with flight test data, especially at medium and high frequencies. RP KIM, FD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 12 Z9 13 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 854 EP 863 DI 10.2514/3.46427 PG 10 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600011 ER PT J AU TALBOT, PD PHILLIPS, JD TOTAH, JJ AF TALBOT, PD PHILLIPS, JD TOTAH, JJ TI SELECTED DESIGN ISSUES OF SOME HIGH-SPEED ROTORCRAFT CONCEPTS SO JOURNAL OF AIRCRAFT LA English DT Article AB A study of vehicle concepts for high-speed rotorcraft applications has been undertaken at Ames Research Center with the objective of defining their technology needs. The design guidelines include a low downwash velocity in hover, good low-speed maneuver capabilities, and cruise speeds up to 450 kt. Four contractors and a systems analysis effort within NASA have defined promising configurations which may be capable of meeting these goals. This article addresses challenging problems associated with some of the configurations in the areas of aerodynamics, propulsion, weights, and aeroelastic stability. RP TALBOT, PD (reprint author), NASA,AMES RES CTR,DIV AIRCRAFT TECHNOL,ROTORCRAFT TECHNOL BRANCH,MS 237-11,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 864 EP 871 DI 10.2514/3.46428 PG 8 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600012 ER PT J AU GALLMAN, JW SMITH, SC KROO, IM AF GALLMAN, JW SMITH, SC KROO, IM TI OPTIMIZATION OF JOINED-WING AIRCRAFT SO JOURNAL OF AIRCRAFT LA English DT Article AB The joined wing is an innovative aircraft configuration with a rear wing that has its root attached near the top of the vertical tail and a tip that sweeps forward to join the trailing edge of the main wing. This study demonstrates the application of numerical optimization to aircraft design and presents a quantitative comparison of joined-wing and conventional aircraft designed for the same medium-range transport mission. The computer program developed for this study used a vortex-lattice model of the complete aircraft to estimate aerodynamic performance, and a beam model of the lifting-surface structure to calculate wing and tail weight. Weight estimation depended on a fully stressed design algorithm that included a constraint on buckling and a correlation with a statistically based method for total lifting-surface weight. A variety of ''optimum'' joined-wing and conventional aircraft designs are compared on the basis of direct operating cost, gross weight, and cruise drag. Maximum lift and horizontal tail buckling were identified as critical joined-wing design issues. The addition of a buckling constraint is shown to decrease the optimum joined-wing span and increase direct operating cost by about 4%. The most promising joined-wing designs were found to have a joint location at about 70% of the wing semispan, a fuel tank in the tail to trim, and a flap spanning 70% of the wing. These designs are shown to cost 3% more to operate than a conventional configuration designed for the same medium-range mission. RP GALLMAN, JW (reprint author), NASA,AMES RES CTR,M-S 227-2,MOFFETT FIELD,CA 94035, USA. NR 0 TC 20 Z9 22 U1 3 U2 13 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 897 EP 905 DI 10.2514/3.46432 PG 9 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600016 ER PT J AU PRITCHARD, JI ADELMAN, HM WALSH, JL WILBUR, ML AF PRITCHARD, JI ADELMAN, HM WALSH, JL WILBUR, ML TI OPTIMIZING TUNING MASSES FOR HELICOPTER ROTOR BLADE VIBRATION REDUCTION AND COMPARISON WITH TEST DATA SO JOURNAL OF AIRCRAFT LA English DT Article AB This article describes the development and validation of an optimization procedure to systematically place tuning masses along a rotor blade span to minimize vibratory loads. The masses and their corresponding locations are the design variables that are manipulated to reduce harmonics of hub shear for a four-bladed rotor system without adding a large mass penalty. The procedure incorporates a comprehensive helicopter analysis to calculate the airloads. Predicting changes in airloads due to changes in design variables is an important feature of this research. The procedure was applied to a one-sixth, Mach-scaled rotor blade model to place three masses and then again to place six masses. In both cases the added mass was able to achieve significant reductions in the hub shear. In addition, the procedure was applied to place a single mass of fixed value on a blade model to reduce the hub shear for three flight conditions. The analytical results were compared to experimental data from a wind-tunnel test performed in the Langley transonic dynamics tunnel (TDT). The correlation or the mass location was good and the trend of the mass location with respect to flight speed was predicted fairly well. However, it was noted that the analysis was not entirely successful at predicting the absolute magnitudes of the fixed-system loads. RP PRITCHARD, JI (reprint author), NASA,LANGLEY RES CTR,AEROSTRUCT DIRECTORATE,HAMPTON,VA 23681, USA. NR 0 TC 4 Z9 5 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 906 EP 910 DI 10.2514/3.46433 PG 5 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600017 ER PT J AU WOODWARD, RP LOEFFLER, IJ AF WOODWARD, RP LOEFFLER, IJ TI IN-FLIGHT SOURCE NOISE OF AN ADVANCED LARGE-SCALE SINGLE-ROTATION PROPELLER SO JOURNAL OF AIRCRAFT LA English DT Article AB A large-scale advanced single-rotation turboprop engine was installed on the left wing of a Gulfstream II aircraft for in-night aeroacoustic tests. This program, designated propfan test assessment (PTA), involved aeroacoustic tests of the propeller over a range of flight conditions. Data was taken both near the source propeller at flight conditions and on the ground, resulting in a unique set of data which is valuable for evaluating acoustic propagation models for cruise noise ground measurements. The in-flight data reported herein was taken for seven test cases. An acoustically instrumented Learjet was flown in formation with the Gulfstream II to acquire noise measurements, and acoustic data was also acquired on the Gulfstream II aircraft. These acoustic measurements defined source levels and directivities for input into long-distance propagation models to predict en route noise. The sideline tone directivities measured by the Learjet showed maximum levels near 105 deg from the propeller upstream axis. Azimuthal directivities based on the maximum observed sideline tone levels showed highest levels below the aircraft (with a + 3-deg propeller axis angle of attack). An investigation of the effect of propeller tip speed (with other engine parameters, such as thrust, shaft power, flight speed, and altitude, held constant) showed that the tone level reduction associated with reductions in propeller tip speed is more significant in the horizontal plane than below the aircraft. RP WOODWARD, RP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 918 EP 926 DI 10.2514/3.46435 PG 9 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600019 ER PT J AU EKATERINARIS, JA SCHIFF, LB AF EKATERINARIS, JA SCHIFF, LB TI NUMERICAL PREDICTION OF VORTICAL FLOW OVER SLENDER DELTA-WINGS SO JOURNAL OF AIRCRAFT LA English DT Article AB Three-dimensional Navier-Stokes numerical simulations are necessary to correctly predict the complex leeward-side flow characteristics over delta wings, including leading-edge separation, secondary separation, and vortex breakdown. This article presents Navier-Stokes solutions of subsonic vortical flow over a 75-deg sweep delta wing with a sharp leading edge. The sensitivity of the solution to the numerical scheme is examined using both a partially upwind scheme and a central-differencing scheme. The effect of numerical grid density is also investigated. An embedded grid approach is implemented to enable higher resolution in selected isolated flow regions, such as the leeward-side surface flow region, and the leading-edge vortical now region. RP EKATERINARIS, JA (reprint author), NASA,AMES RES CTR,NAVY NASA JOINT INST AERONAUT,MOFFETT FIELD,CA 94035, USA. NR 0 TC 10 Z9 10 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 935 EP 942 DI 10.2514/3.46437 PG 8 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600021 ER PT J AU NOLL, TE AUSTIN, E DONLEY, S GRAHAM, G HARRIS, T KAYNES, I LEE, BHK SPARROW, J AF NOLL, TE AUSTIN, E DONLEY, S GRAHAM, G HARRIS, T KAYNES, I LEE, BHK SPARROW, J TI IMPACT OF ACTIVE CONTROLS TECHNOLOGY ON STRUCTURAL INTEGRITY SO JOURNAL OF AIRCRAFT LA English DT Article AB This article summarizes the findings of an investigation conducted under the auspices of the technical cooperation program (TTCP) to assess the impact of active controls technology on the structural integrity of aeronautical vehicles, and to evaluate the present state-of-the-art for predicting loads caused by a flight-control system modification and the resulting change in the fatigue life of the flight vehicle. Important points concerning structural technology considerations implicit in applying active controls technology in new aircraft are summarized. These points are well founded and based upon information received from within the aerospace industry and government laboratories, acquired by sponsoring workshops which brought together experts from contributing and interacting technical disciplines, and obtained by conducting a case study to independently assess the state of the technology. This article concludes that communication between technical disciplines is absolutely essential in the design of future high-performance aircraft. RP NOLL, TE (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,HAMPTON,VA 23681, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 985 EP 992 DI 10.2514/3.46443 PG 8 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600027 ER PT J AU MEHTA, UB AF MEHTA, UB TI AEROSPACE PLANE DESIGN CHALLENGE - CREDIBLE COMPUTATIONS (VOL 30, PG 519, 1993) SO JOURNAL OF AIRCRAFT LA English DT Correction, Addition RP MEHTA, UB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1993 VL 30 IS 6 BP 1009 EP 1009 DI 10.2514/3.56897 PG 1 WC Engineering, Aerospace SC Engineering GA ML016 UT WOS:A1993ML01600032 ER PT J AU CHUBB, DL LOWE, RA AF CHUBB, DL LOWE, RA TI THIN-FILM SELECTIVE EMITTER SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID THERMOPHOTOVOLTAICS AB Direct conversion of thermal energy into electrical energy using a photovoltaic cell is called thermophotovoltaic energy conversion. One way to make this an efficient process is to have the thermal energy source be an efficient selective emitter of radiation. The emission must be near the band-gap energy of the photovoltaic cell. One possible method to achieve an efficient selective emitter is the use of a thin film of rare-earth oxides. The determination of the efficiency of such an emitter requires analysis of the spectral emittance of the thin film including scattering and reflectance at the vacuum-film and film-substrate interfaces. Emitter efficiencies (power emitted in emission band/total emitted power) in the range 0.35-0.7 are predicted. There is an optimum optical depth to obtain maximum efficiency. High emitter efficiencies are attained only for low (less-than-or-equal-to 0.05) substrate emittance values, both with and without scattering. The low substrate emittance required for high efficiency limits the choice of substrate materials to highly reflective metals or high-transmission materials such as sapphire. C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP CHUBB, DL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 25 TC 32 Z9 32 U1 1 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD NOV 1 PY 1993 VL 74 IS 9 BP 5687 EP 5696 DI 10.1063/1.354184 PG 10 WC Physics, Applied SC Physics GA MG597 UT WOS:A1993MG59700061 ER PT J AU BAKER, DN GOLDBERG, RA HERRERO, FA BLAKE, JB CALLIS, LB AF BAKER, DN GOLDBERG, RA HERRERO, FA BLAKE, JB CALLIS, LB TI SATELLITE AND ROCKET STUDIES OF RELATIVISTIC ELECTRONS AND THEIR INFLUENCE ON THE MIDDLE ATMOSPHERE SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article AB Magnetospheric electrons from hundreds of keV to over 10 MeV in energy have been systematically measured at geostationary altitude (6.6 R(E)) for well over a decade. We find evidence of significant diurnal, solar-rotational (27-day), annual, and solar-cycle (11-yr) variations in the fluxes of the relativistic electron component. We have also used low-altitude satellite data and sounding rocket measurements to characterize the location and strength of the relativistic electron precipitation into the atmosphere. We conclude that the magnetospheric electrons, when dumped into the middle atmosphere, represent a very significant ionization source which affects the pattern of conductivity, electric fields, and atmospheric chemistry. These measurements-when combined with global atmospheric modeling-suggest that relativistic electrons provide a robust coupling mechanism to impose long-term solar wind and magnetospheric variability onto the Earth's deep atmospheric regions. A strong 11-yr cycle of relativistic electron effects is found in available atmospheric data sets. C1 AEROSP CORP,LOS ANGELES,CA 90009. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP BAKER, DN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Goldberg, Richard /E-1881-2012 NR 19 TC 45 Z9 45 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD NOV PY 1993 VL 55 IS 13 BP 1619 EP 1628 DI 10.1016/0021-9169(93)90167-W PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LV677 UT WOS:A1993LV67700001 ER PT J AU ATLAS, R WOLFSON, N TERRY, J AF ATLAS, R WOLFSON, N TERRY, J TI THE EFFECT OF SST AND SOIL-MOISTURE ANOMALIES ON GLA MODEL SIMULATIONS OF THE 1988 UNITED-STATES SUMMER DROUGHT SO JOURNAL OF CLIMATE LA English DT Article ID NORTH-AMERICAN DROUGHT; PARAMETERIZATION AB A series of simulations of the late spring and early summer of 1988 were conducted in order to study the relative importance of different boundary forcings to the Goddard Laboratory for Atmospheres model's simulation of the heat wave and drought over the Great Plains of the United States during this time period, Separate 60-day simulations were generated from 10, 20, and 30 May 1988 with a variety of boundary condition datasets. For the control experiment, climatological boundary conditions were used. This was followed by experiments in which either the observed 1988 sea surface temperatures (SST) or derived 1988 soil moisture values, or both, were used in place of the climatological fields. Additional experiments were conducted in which only tropical or midlatitude SST anomalies were used. The impact of the different boundary forcings was evaluated relative to the control simulations of the precipitation and surface air temperature over the Great Plains. It was found that the tropical SST anomalies had a significant effect in reducing precipitation in this area, while the midlatitude anomalies did not. Due to the prescribed climatological soil moistures for the SST experiments, a significant increase in surface temperature did not occur in these simulations. In contrast, the simulations with the anomalous 1988 soil moistures produced both a larger reduction of precipitation and a significant increase in surface temperature over the Great Plains. The simulations with both anomalous SST and soil moisture showed only a slight augmentation of the heat wave and drought relative to the experiments with anomalous soil moisture alone. C1 UNIV SPACE RES ASSOC, GREENBELT, MD USA. GEN SCI CORP, GREENBELT, MD USA. RP ATLAS, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, SATELLITE DATA UTILIZAT OFF, CODE 9104, GREENBELT, MD 20771 USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 21 TC 125 Z9 129 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1993 VL 6 IS 11 BP 2034 EP 2048 DI 10.1175/1520-0442(1993)006<2034:TEOSAS>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MH539 UT WOS:A1993MH53900003 ER PT J AU NEGRI, AJ ADLER, RF MADDOX, RA HOWARD, KW KEEHN, PR AF NEGRI, AJ ADLER, RF MADDOX, RA HOWARD, KW KEEHN, PR TI A REGIONAL RAINFALL CLIMATOLOGY OVER MEXICO AND THE SOUTHWEST UNITED-STATES DERIVED FROM PASSIVE MICROWAVE AND GEOSYNCHRONOUS INFRARED DATA SO JOURNAL OF CLIMATE LA English DT Article ID DIURNAL CYCLE; SSM/I DATA; CLOUD; PRECIPITATION AB A three-year climatology of satellite-estimated rainfall for the warm season for the southwest United States and Mexico has been derived from data from the Special Sensor Microwave Imager (SSM/I). The microwave data have been stratified by month (June, July, August), year ( 1988, 1989, 1990), and time of day (morning and evening orbits). A rain algorithm was employed that relates 86-GHz brightness temperatures to rain rate using a coupled cloud-radiative transfer model. Results identify an early evening maximum in rainfall along the western slope of the Sierra Madre Occidental during all three months. A prominent morning rainfall maximum was found off the western Mexican coast near Mazatlan in July and August. Substantial differences between morning and evening estimates were noted. To the extent that three years constitute a climatology, results of interannual variability are presented. Results are compared and contrasted to high-resolution (8 km, hourly) infrared cloud climatologies, which consist of the frequency of occurrence of cloud colder than -38-degrees-C and -58-degrees-C. This comparison has broad implications for the estimation of rainfall by simple (cloud threshold) techniques. By sampling the infrared data to approximate the time and space resolution of the microwave, we produce ratios (or adjustment factors) by which we can adjust the infrared rain estimation schemes. This produces a combined microwave/infrared rain algorithm for monthly rainfall. Using a limited set of raingage data as ground truth, an improvement (lower bias and root-mean-square error) was demonstrated by this combined technique when compared to either method alone. The diurnal variability of convection during July 1990 was examined using hourly rain estimates from the GOES precipitation index and the convective stratiform technique, revealing a maximum in estimated rainfall from 1800 to 2100 local time. It is in this time period when the SSM/I evening orbit occurs. A high-resolution topographic database was available to aid in interpreting the influence of topography on the rainfall patterns. C1 NOAA,ERL,NATL SEVERE STORMS LAB,NORMAN,OK 73069. SCI SYST & APPLICAT INC,LANHAM,MD. RP NEGRI, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771, USA. NR 17 TC 36 Z9 36 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1993 VL 6 IS 11 BP 2144 EP 2161 DI 10.1175/1520-0442(1993)006<2144:ARRCOM>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MH539 UT WOS:A1993MH53900009 ER PT J AU LATHERS, CM CHARLES, JB AF LATHERS, CM CHARLES, JB TI USE OF LOWER-BODY NEGATIVE-PRESSURE TO COUNTER SYMPTOMS OF ORTHOSTATIC INTOLERANCE IN PATIENTS, BED REST SUBJECTS, AND ASTRONAUTS SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article ID HEART-RATE RESPONSE; SHY-DRAGER SYNDROME; HYPOTENSION; MIDODRINE; SPACE; AGENT; MANAGEMENT; MECHANISMS; BEDREST; HUMANS AB This report briefly discusses some aspects of autonomic cardiovascular dysfunction as related to changes in orthostatic function in patients, bed rest subjects, and astronauts. This relationship is described in normal individuals to provide the basis for discussion of parameters that may be altered in patients, bed rest subjects, and astronauts. The relationships between disease states, age, periods of weightlessness during space flight, and autonomic dysfunction, and their contribution to changes in orthostatic tolerance are presented. The physiologic effects of lower body negative pressure are illustrated by presenting data obtained in bed rest subjects and in astronauts. Finally, the usefulness of lower body negative pressure to counter symptoms of orthostatic intolerance in patients, bed rest subjects, and astronauts is discussed. RP LATHERS, CM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,CARDIOVASC LAB,SD 5,HOUSTON,TX 77058, USA. NR 49 TC 12 Z9 12 U1 1 U2 1 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD NOV PY 1993 VL 33 IS 11 BP 1071 EP 1085 PG 15 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA MJ272 UT WOS:A1993MJ27200009 PM 8300890 ER PT J AU KOHL, RL SANDOZ, GR RESCHKE, MF CALKINS, DS RICHELSON, E AF KOHL, RL SANDOZ, GR RESCHKE, MF CALKINS, DS RICHELSON, E TI FACILITATION OF ADAPTATION AND ACUTE TOLERANCE TO STRESSFUL SENSORY INPUT BY DOXEPIN AND SCOPOLAMINE PLUS AMPHETAMINE SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article ID SPACE MOTION SICKNESS; HEALTHY-VOLUNTEERS; DRUGS; ANTIDEPRESSANTS; AMITRIPTYLINE; STABILITY; KINETICS AB This work characterizes a new methodologic and pharmacologic approach to control terrestrial and space motion sickness (SMS). The experimental design allowed separate evaluation of drug action on susceptibility and adaptability, and used repeated measures to approximate the chronic stressful motion of microgravity. Daily exposure to cross-coupled angular acceleration for 5 consecutive days demonstrated that the efficacy of doxepin and scopolamine plus amphetamine in the prevention of autonomic system dysfunction was not only apparent on the first test day (P < .01), but was also evident in the substantially enhanced resistance developed over the 5-day test period (P < .01) as compared with placebo. This indicates that daily use of these medications does not diminish therapeutic efficacy (tolerance). The efficacy of doxepin was anticipated because it possesses pharmacologic properties similar to those of established anti-motion sickness drugs. Comparable efficacy after doxepin loading for 4 hours, 3 days, or 21 days suggests a mechanism distinct from its antidepressant effects, possibly related to its potent antihistaminergic actions. Use of doxepin has operational significance to the National Aeronautics and Space Administration, in comparison with current preparations of scopolamine plus amphetamine, because of doxepin's minimal impact on cognitive performance, and most importantly, its favorable pharmacokinetic profile, particularly its long half-life. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,DIV MED SCI,MAIL CODE SD,HOUSTON,TX 77058. KRUG LIFE SCI INC,HOUSTON,TX. UNIV TEXAS,MED BRANCH,DEPT PHARMACOL & TOXICOL,GALVESTON,TX 77550. NR 46 TC 0 Z9 0 U1 1 U2 3 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD NOV PY 1993 VL 33 IS 11 BP 1092 EP 1103 PG 12 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA MJ272 UT WOS:A1993MJ27200011 PM 8300892 ER PT J AU STEHLIK, LL AF STEHLIK, LL TI DIETS OF THE BRACHYURAN CRABS CANCER IRRORATUS, C-BOREALIS, AND OVALIPES OCELLATUS IN THE NEW-YORK BIGHT SO JOURNAL OF CRUSTACEAN BIOLOGY LA English DT Article ID MID-ATLANTIC BIGHT; ROCK CRAB; CHESAPEAKE BAY; NATURAL DIET; PORTUNIDAE; REPRODUCTION; PREDATION; CRUSTACEA; DECAPODA; BIOLOGY AB The stomach contents of 146 Atlantic rock crabs, Cancer irroratus, 87 Jonah crabs, Cancer borealis, and 47 northern lady crabs, Ovalipes ocellatus collected from the area surrounding the former 12-Mile Sewage Sludge Dumpsite in the New York Bight were analyzed. In the dumpsite area, all 3 species principally ate, as quantified by frequency of occurrence and volume, polychaetes, especially Pherusa affinis, as well as mollusks (including squid), crustaceans, fish, and echinoderms. The proportion of mollusks by volume was significantly less in the diet of C. irroratus than in the other 2 species. Many of the taxa in the diets of the 3 species of crabs were among the dominant macrobenthic taxa, as determined by concurrent grab samples at 3 of the stations. At those stations, crustaceans were positively selected by C. irroratus, while cnidarians and rhynchocoels were not selected. In addition, the stomach contents of 27 O. ocellatus from False Hook Channel, a nearby shallower, sandy habitat, were examined. The diet of O. ocellatus at this site was > 80% mollusks by volume, and the most frequently occurring prey was the Atlantic surf clam Spisula solidissima. RP STEHLIK, LL (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 39 TC 37 Z9 39 U1 0 U2 5 PU CRUSTACEAN SOC PI SAN ANTONIO PA 840 EAST MULBERRY, SAN ANTONIO, TX 78212 SN 0278-0372 J9 J CRUSTACEAN BIOL JI J. Crustac. Biol. PD NOV PY 1993 VL 13 IS 4 BP 723 EP 735 DI 10.2307/1549103 PG 13 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA MF524 UT WOS:A1993MF52400011 ER PT J AU MANKBADI, RR WU, XS LEE, SS AF MANKBADI, RR WU, XS LEE, SS TI A CRITICAL-LAYER ANALYSIS OF THE RESONANT TRIAD IN BOUNDARY-LAYER-TRANSITION - NONLINEAR-INTERACTIONS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SHEAR FLOWS; WAVE INTERACTIONS; UPPER BRANCH; ROLL-UP; INSTABILITY AB A systematic theory is developed to study the nonlinear spatial evolution of the resonant triad in Blasius boundary layers. This triad consists of a plane wave at the fundamental frequency and a pair of symmetrical, oblique waves at the subharmonic frequency. A low-frequency asymptotic scaling leads to a distinct critical layer wherein nonlinearity first becomes important, and the critical layer's nonlinear, viscous dynamics determine the development of the triad. The plane wave initially causes double-exponential growth of the oblique waves. The plane wave, however, continues to follow the linear theory, even when the oblique waves' amplitude attains the same order of magnitude as that of the plane wave. However, when the amplitude of the oblique waves exceeds that of the plane wave by a certain level, a nonlinear stage comes into effect in which the self-interaction of the oblique waves becomes important. The self-interaction causes rapid growth of the phase of the oblique waves, which causes a change of the sign of the parametric-resonance term in the oblique-waves amplitude equation. Ultimately this effect causes the growth rate of the oblique waves to oscillate around their linear growth rate. Since the latter is usually small in the nonlinear regime, the net outcome is that the self-interaction of oblique waves causes the parametric resonance stage to be followed by an 'oscillatory' saturation stage. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,CLEVELAND,OH 44135. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,DEPT MATH,LONDON SW7 2BZ,ENGLAND. RP MANKBADI, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 37 TC 32 Z9 35 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD NOV PY 1993 VL 256 BP 85 EP 106 DI 10.1017/S0022112093002721 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA ML311 UT WOS:A1993ML31100004 ER PT J AU BLAISDELL, GA MANSOUR, NN REYNOLDS, WC AF BLAISDELL, GA MANSOUR, NN REYNOLDS, WC TI COMPRESSIBILITY EFFECTS ON THE GROWTH AND STRUCTURE OF HOMOGENEOUS TURBULENT SHEAR-FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID MACH NUMBER; SIMULATION; LAYERS; FLUID AB Compressibility effects within decaying isotropic turbulence and homogeneous turbulent shear flow have been studied using direct numerical simulation. The objective of this work is to increase our understanding of compressible turbulence and to aid the development of turbulence models for compressible flows. The numerical simulations of compressible isotropic turbulence show that compressibility effects are highly dependent on the initial conditions. The shear flow simulations, on the other hand, show that measures of compressibility evolve to become independent of their initial values and are parameterized by the root mean square Mach number. The growth rate of the turbulence in compressible homogeneous shear flow is reduced compared to that in the incompressible case. The reduced growth rate is the result of an increase in the dissipation rate and energy transfer to internal energy by the pressure-dilatation correlation. Examination of the structure of compressible homogeneous shear flow reveals the presence of eddy shocklets, which are important for the increased dissipation rate of compressible turbulence. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, STANFORD, CA 94305 USA. RP BLAISDELL, GA (reprint author), PURDUE UNIV, SCH AERONAUT & ASTRONAUT, W LAFAYETTE, IN 47907 USA. NR 62 TC 98 Z9 99 U1 0 U2 13 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD NOV PY 1993 VL 256 BP 443 EP 485 DI 10.1017/S0022112093002848 PG 43 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA ML311 UT WOS:A1993ML31100016 ER PT J AU TOBISKA, WK AF TOBISKA, WK TI RECENT SOLAR EXTREME-ULTRAVIOLET IRRADIANCE OBSERVATIONS AND MODELING - A REVIEW SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID THERMOSPHERIC NITRIC-OXIDE; LYMAN ALPHA-FLUX; X-RAY-EMISSION; EUV FLUX; RADIO FLUX; TEMPORAL VARIATIONS; REFERENCE SPECTRUM; TRANSITION REGION; ENERGY-BALANCE; 10.7-CM FLUX AB For more than 90 years, solar extreme ultraviolet (EUV) irradiance modeling has progressed from empirical blackbody radiation formulations, through fudge factors, to typically measured irradiances and reference spectra as well as time-dependent empirical models representing continua and line emissions. A summary of recent EUV measurements by five rockets and three satellites during the 1980s is presented along with the major modeling efforts. The most significant reference spectra are reviewed and three independently derived empirical models are described. These include Hinteregger's 1981 SERF1, Nusinov's 1984 two-component, and Tobiska's 1990/1991 SERF2/EUV91 flux models. They each provide daily full-disk broad spectrum flux values from 2 to 105 nm at 1 AU. All the models depend to one degree or another on the long time series of the Atmosphere Explorer E (AE-E) EUV database. Each model uses ground- and/or space-based proxies to create emissions from solar atmospheric regions. Future challenges in EUV modeling are summarized including the basic requirements of models, the task of incorporating new observations and theory into the models, the task of comparing models with solar-terrestrial data sets, and long-term goals and modeling objectives. By the late 1990s, empirical models will potentially be improved through the use of proposed solar EUV irradiance measurements and images at selected wavelengths that will greatly enhance modeling and predictive capabilities. RP TELOS, JPL, MS 264765, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 106 TC 63 Z9 63 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 18879 EP 18893 DI 10.1029/93JA01943 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700001 ER PT J AU HOYT, DV SCHATTEN, KH AF HOYT, DV SCHATTEN, KH TI A DISCUSSION OF PLAUSIBLE SOLAR IRRADIANCE VARIATIONS, 1700-1992 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAUNDER MINIMUM; SURFACE-TEMPERATURE; LUMINOSITY; CLIMATE; CYCLE; MECHANISM; CONSTANT; SUNSPOTS; RECORD; TRENDS AB From satellite observations the solar total irradiance is known to vary. Sunspot blocking, facular emission, and network emission are three identified causes for the variations. In this paper we examine several different solar indices measured over the past century that are potential proxy measures for the Sun's irradiance. These indices are (1) the equatorial solar rotation rate, (2) the sunspot structure, the decay rate of individual sunspots, and the number of sunspots without umbrae, and (3) the length and decay rate of the sunspot cycle. Each index can be used to develop a model for the Sun's total irradiance as seen at the Earth. Three solar indices allow the irradiance to be modeled back to the mid-1700s. The indices are (1) the length of the solar cycle, (2) the normalized decay rate of the solar cycle, and (3) the mean level of solar activity. All the indices are well correlated, and one possible explanation for their nearly simultaneous variations is changes in the Sun's convective energy transport. Although changes in the Sun's convective energy transport are outside the realm of normal stellar structure theory (e.g., mixing length theory), one can imagine variations arising from even the simplest view of sunspots as vertical tubes of magnetic flux, which would serve as rigid pillars affecting the energy flow pattern by ensuring larger-scale eddies. A composite solar irradiance model, based upon these proxies, is compared to the northern hemisphere temperature departures for 1700-1992. Approximately 71% of the decadal variance in the last century can be modeled with these solar indices, although this analysis does not include anthropogenic or other variations which would affect the results. Over the entire three centuries, approximately 50% of the variance is modeled. Both this analysis and previous similar analyses have correlations of model solar irradiances and measured Earth surface temperatures that are significant at better than the 95% confidence level. To understand our present climate variations, we must place the anthropogenic variations in the context of natural variability from solar, volcanic, oceanic, and other sources. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HOYT, DV (reprint author), RES & DATA SYST CORP,7855 WALKER DR,SUITE 460,GREENBELT,MD 20770, USA. NR 62 TC 272 Z9 285 U1 2 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 18895 EP 18906 DI 10.1029/93JA01944 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700002 ER PT J AU SCHATTEN, KH AF SCHATTEN, KH TI HELIOGRAPHIC LATITUDE DEPENDENCE OF THE SUNS IRRADIANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ACTIVE REGIONS; MODULATION AB It has recently been reported that the total radiative emission variations from solar type stars exceeds the currently observed solar constant variations (from spacecraft over the last decade) by a factor near 4. Aside from other remote alternatives, this suggests three clear possibilities: (1) the Sun may undergo irradiance variations several times larger than any we have seen; (2) our Sun is highly unusual with regard to its radiative output; or (3) our terrestrial position in the heliosphere provides a special vantage point which reduces the observed solar irradiance variations. We investigate the last possibility by considering the influence of observer latitude upon calculated irradiance variations using a simple model for emission from solar contrast features. We consider modeled sunspots, faculae, and network structures. As the latitude angle of the observer rises relative to the heliographic equator, sunspot deficit contributions diminish and facular plus network contributions escalate. We find that the observing latitude can influence the irradiance variations by a factor near 6. When we integrate the irradiance variations, over the celestial sphere, they average to 3 times the terrestrial effect, suggesting that the solar cycle luminosity variations are proportionally, 3 times larger than the solar constant variations. Thus we suggest the Sun's luminosity output varies even more strongly with the solar cycle than is apparent in the solar constant variations. The influence of the observer viewing angle relative to stellar spin axis, studied here, may be possible to investigate with a thorough statistical examination of other solar type stars. Additionally, the rotational modulation due to active regions (as a function of observer viewing angle) may also be a valuable area for future investigation. RP SCHATTEN, KH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 914,GREENBELT,MD 20771, USA. NR 14 TC 23 Z9 23 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 18907 EP 18910 DI 10.1029/93JA01941 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700003 ER PT J AU LAWRENCE, JK TOPKA, KP JONES, HP AF LAWRENCE, JK TOPKA, KP JONES, HP TI CONTRAST OF FACULAE NEAR THE DISK CENTER AND SOLAR VARIABILITY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IRRADIANCE VARIATIONS; MAGNETIC-FIELDS; ACTIVE REGIONS; PHOTOMETRY; SUNSPOTS; SUN AB We analyze simultaneous, or near-simultaneous, coregistered, digital, photometric images of solar photospheric intensity and line-of-sight magnetic field. Images were made with the Lockheed tunable filter instrument at the Swedish Solar Observatory, La Palma, with the video spectra-spectroheliograph system at the San Fernando Observatory and with the new NASA spectromagnetograph at the National Solar Observatory at Kitt Peak. We study the disk center contrasts of small magnetic elements. While active region faculae are dark at disk center quiet Sun network features are bright. The populations of magnetic field elements that make up these two kinds of features are quite different. Different contrast center-limb functions must be used when estimating their irradiance or luminosity contributions. The disk center contrasts of active region faculae are color dependent and indicate a depth effect related to the H- opacity of the facular atmosphere. This result is important for calibration of monochromatic observations of faculae to bolometric irradiance fluctuations. We emphasize the value of cooperative observations among installations whose differing strengths are complementary. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,SW SOLAR STN,NATL SOLAR OBSERV,TUCSON,AZ 85726. LOCKHEED PALO ALTO RES LABS,SOLAR & ASTROPHYS LAB,DEPT 9130,B252,PALO ALTO,CA 94304. RP LAWRENCE, JK (reprint author), CALIF STATE UNIV NORTHRIDGE,DEPT PHYS & ASTRON,SAN FERNANDO OBSERV,NORTHRIDGE,CA 91330, USA. NR 31 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 18911 EP 18918 DI 10.1029/93JA01942 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700004 ER PT J AU WOO, R AF WOO, R TI SOLAR-CYCLE VARIATION OF INTERPLANETARY DISTURBANCES OBSERVED AS DOPPLER SCINTILLATION TRANSIENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; WHITE-LIGHT; WIND; SPACECRAFT; SHOCKS; IPS AB Interplanetary disturbances characterized by plasma that is more turbulent and/or moves faster than the background solar wind are readily detected as transients in Doppler scintillation measurements of the near-Sun solar wind. Systematic analysis of over 23,000 hours of Pioneer Venus Orbiter Doppler measurements obtained inside 0.5 AU during 1979-1987 have made it possible for the first time to investigate the frequency of occurrence of Doppler scintillation transients under solar minimum conditions and to determine its dependence on solar cycle. On the basis of a total of 142 transients, Doppler scintillation transient rates vary from a high of 0.22 in 1979 (one every 4.6 days) to a low of 0.077 transients/d in 1986 (one every 13 days), a decrease by almost a factor of 3 from solar maximum to solar minimum. This solar cycle variation, the strongest yet of any solar wind Doppler scintillation property, is highly correlated with both solar activity characterized by sunspot number and the coronal mass ejection rates deduced from Solwind and Solar Maximum Mission (SMM) coronagraph observations. These results indicate that coronal mass ejections and Doppler scintillation transients are closely related not just during solar maximum, as occasional individual comparisons have shown in the past, but throughout the entire solar cycle, and strengthen the notion that the Doppler scintillation and optical transients are different manifestations of the same physical phenomenon. The magnitudes of the transients, as described by the ratio of peak to pretransient scintillation levels (EF for enhancement factor), and their distribution with heliocentric distance also vary with solar cycle. While EF tends to diminish with increasing heliocentric distance during high solar activity, it is more evenly distributed during low solar activity. EF is also lower during solar minimum, as 13% of the transients during solar maximum have values exceeding 23, the highest EF observed during solar minimum. These results are consistent with the fact that occasional major fast-moving interplanetary shocks that are observed during solar maximum are very rare during solar minimum. RP WOO, R (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 27 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 18999 EP 19004 DI 10.1029/93JA01990 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700012 ER PT J AU CARPENTER, DL GILES, BL CHAPPELL, CR DECREAU, PME ANDERSON, RR PERSOON, AM SMITH, AJ CORCUFF, Y CANU, P AF CARPENTER, DL GILES, BL CHAPPELL, CR DECREAU, PME ANDERSON, RR PERSOON, AM SMITH, AJ CORCUFF, Y CANU, P TI PLASMASPHERE DYNAMICS IN THE DUSKSIDE BULGE REGION - A NEW LOOK AT AN OLD TOPIC SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID MAGNETOSPHERIC ELECTRIC-FIELDS; ION MASS-SPECTROMETER; RING CURRENT; PLASMAPAUSE-PLASMASPHERE; WHISTLER EVIDENCE; THERMAL PLASMA; COLD-PLASMA; CONVECTION; MODEL; DENSITY AB Data acquired during several multiday periods in 1982 at ground stations Siple, Halley, and Kerguelen and on satellites DE 1, ISEE 1, and GEOS 2 have been used to investigate thermal plasma structure and dynamics in the duskside plasmasphere bulge region of the Earth. The distribution of thermal plasma in the dusk bulge sector is difficult to describe realistically, in part because of the time integral manner in which the thermal plasma distribution depends upon the effects of bulk cross-B flow and interchange plasma flows along B. While relatively simple MHD models can be useful for qualitatively predicting certain effects of enhanced convection on a quiet plasmasphere, such as an initial sunward entrainment of the outer regions, they are of limited value in predicting the duskside thermal plasma structures that are observed. Furthermore, use of such models can be misleading if one fails to realize that they do not address the question of the formation of the steep plasmapause profile or provide for a possible role of instabilities or other irreversible processes in plasmapause formation. Our specific findings, which are based both upon the present case studies and upon earlier work, include the following: (1) during active periods the plasmasphere appears to become divided into two entities, a main plasmasphere and a duskside bulge region. The latter consists of outlying or outward extending plasmas that are the products of erosion of the main plasmasphere; (2) in the aftermath of an increase in convection activity, the main plasmasphere tends (from a statistical point of view) to become roughly circular in equatorial cross section, with only a slight bulge at dusk; (3) the abrupt westward edge of the duskside bulge observed from whistlers represents a state in the evolution of sunward extending streamers; (4) in the aftermath of a weak magnetic storm, 10 to 30% of the plasma ''removed'' from the outer plasmasphere appears to remain in the afternoon-dusk sector beyond the main plasmasphere. This suggests that plasma flow from the afternoon-dusk magnetosphere into the boundary layers is to some extent impeded, possibly through a mechanism that partially decouples the high altitude and ionospheric-level flow regimes; (5) outlying dense plasma structures may circulate in the outer duskside magnetosphere for many days following an increase in convection, unless there is extremely deep quieting; (6) a day-night plasmatrough boundary may be identified in equatorial satellite data; (7) factor-of-2-to-10 density irregularities appear near the plasmapause in the postdusk sector in the aftermath of weak magnetic storms; (8) during the refilling of the plasmatrough from the ionosphere at L = 4.6, predominantly bidirectional field aligned and equatorially trapped light ion pitch angle distributions give way to a predominantly isotropic distribution (as seen by DE 1) when the plasma density reaches a level a factor of about 3 below the saturated plasmasphere level; (9) some outlying dense plasma structures are effectively detached from the main plasmasphere, while others appear to be connected to that body. C1 UNV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52244. CTR RECH PHYS ENVIRONN,CNET,F-92131 ISSY MOULINEAUX,FRANCE. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV POITIERS,SIGNAUX & COMMUN LAB,F-86800 MIGNALOUX BEAUVOI,FRANCE. LAB PHYS & CHIM ENVIRONNEMENT,CNRS,ORLEANS,FRANCE. NERC,BRITISH ANTARCTIC SURVEY,CAMBRIDGE CB3 0ET,ENGLAND. RP CARPENTER, DL (reprint author), STANFORD UNIV,STAR LAB,STANFORD,CA 94305, USA. NR 121 TC 114 Z9 115 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 19243 EP 19271 DI 10.1029/93JA00922 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700035 ER PT J AU WINGLEE, RM MENIETTI, JD PETERSON, WK BURCH, JL WAITE, JH GILES, B AF WINGLEE, RM MENIETTI, JD PETERSON, WK BURCH, JL WAITE, JH GILES, B TI MAGNETOSHEATH-IONOSPHERIC PLASMA INTERACTIONS IN THE CUSP CLEFT .1. OBSERVATIONS OF MODULATED INJECTIONS AND UPWELLING ION FLUXES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID POLAR CUSP; CYCLOTRON RESONANCE; O+ IONS; WAVES; MAGNETOSPHERE; ACCELERATION; SIMULATIONS; FREQUENCY; PARALLEL; CONICS AB Insitu observations of the cusp/cleft are important as they allow a direct investigation of coupling solar wind energy to the ionosphere, plus they provide an opportunity for the remote sensing of the magnetopause. High time resolution observations from DE 1 are used to investigate these processes. It is shown that in the spacecraft frame the injection in modulated or pulsating with a period of approximately 18 - 30 s with the injection duration possibly being as short as 6 s. This modulation indicates that there may be fast time scale and/or short scale length processes modulating the injection of the magnetosheath plasma across the magnetopause. In addition, the pulsating injection is seen to modulate the outflow of upwelling ionospheric ions to the magnetosphere. These upwelling ions are seen prior to the magnetosheath ion injection and therefore are not directly created by the injection. During the injection itself, the intensity of the upwelling ions is seen to dramatically decrease but their average energy increases. At end of the magnetosheath injections, the intensity of the upwelling ion flux is seen to increase to levels comparable to levels prior to the magnetosheath injection. On two occasions during the encounter, the particle fluxes we sufficiently high that enhanced downward flows of perpendicularly heated ions, of presumably ionospheric origin, are observed in association with a reduction in the intensity of the upwelling ions. These observations are probably the first detection of. downward conics and suggest that there is momentum transfer between the magnetosheath and ionospheric ions. This momentum transfer eventually leads to an enhanced outflow of heated ionospheric plasma where their energy has been raised from a few tens of eV to a few hundred eV. C1 SPACE SCI LAB,DEPT 91-20,PALO ALTO,CA 94304. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78228. RP WINGLEE, RM (reprint author), UNIV WASHINGTON,GEOPHYS PROGRAM AK-50,SEATTLE,WA 98195, USA. RI Peterson, WK/A-8706-2009 OI Peterson, WK/0000-0002-1513-6096 NR 36 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 19315 EP 19329 DI 10.1029/93JA01743 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700039 ER PT J AU OHTANI, S ANDERSON, BJ SIBECK, DG NEWELL, PT ZANETTI, LJ POTEMRA, TA TAKAHASHI, K LOPEZ, RE ANGELOPOULOS, V NAKAMURA, R KLUMPAR, DM RUSSELL, CT AF OHTANI, S ANDERSON, BJ SIBECK, DG NEWELL, PT ZANETTI, LJ POTEMRA, TA TAKAHASHI, K LOPEZ, RE ANGELOPOULOS, V NAKAMURA, R KLUMPAR, DM RUSSELL, CT TI A MULTISATELLITE STUDY OF A PSEUDO-SUBSTORM ONSET IN THE NEAR-EARTH MAGNETOTAIL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ALIGNED CURRENT SIGNATURES; MAGNETIC-FIELD; PLASMA SHEET; SYNCHRONOUS ORBIT; MAGNETOSPHERIC SUBSTORMS; CURRENT DISRUPTION; AURORAL-ZONE; TAIL REGION; EXPANSION; MODEL AB This paper reports the multisatellite and ground observations of two pseudo-substorm onset events that occurred successively at 0747 UT and 0811 UT, May 30, 1985, with more attention to the 0747 UT onset. The distinguishing features of the 0747 UT event are as follows. (1) The substorm-associated tail reconfiguration started in a very localized region in the near-Earth magnetotail. (2) The magnitude of the current disruption decreased markedly as the disruption region expanded tailward. (3) On the ground the onset of a very small negative bay (approximately 40 nT) was observed simultaneously with the onset of the current disruption, but over a much wider local time sector than the near-Earth tail reconfiguration. Positive bay onsets at mid-latitudes also had a longitudinally wide distribution. From these features we infer that in the present event the current disruption took place filamentarily near AMPTE/CCE at approximately 8.8 R(E). It is also inferred that pseudo-substorm onsets are distinguished from standard substorm onsets by the absence of a global expansion of the current disruption, and that the spatial scale of the onset region in the magnetosphere is not a major difference between the two. The present study suggests that the spatial distribution of the magnetic distortion before onsets is an important factor to determine the expansion sr-ale of the current disruption. It is also suggested that the current disruption is basically an internal process of the magnetosphere. C1 UNIV MARYLAND,COLL PK,MD 20742. UNIV CALIF LOS ANGELES,DEPT PHYS,LOS ANGELES,CA 90024. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA 442,JAPAN. RP OHTANI, S (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,JOHNS HOPKINS RD,LAUREL,MD 20723, USA. RI Sibeck, David/D-4424-2012; Anderson, Brian/I-8615-2012; Nakamura, Rumi/I-7712-2013; Ohtani, Shinichi/E-3914-2016; OI Nakamura, Rumi/0000-0002-2620-9211; Ohtani, Shinichi/0000-0002-9565-6840; Lopez, Ramon/0000-0001-5881-1365 NR 52 TC 72 Z9 72 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 19355 EP 19367 DI 10.1029/93JA01421 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700042 ER PT J AU TSYGANENKO, NA STERN, DP KAYMAZ, Z AF TSYGANENKO, NA STERN, DP KAYMAZ, Z TI BIRKELAND CURRENTS IN THE PLASMA SHEET SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; GEOMAGNETIC NEUTRAL SHEET; MAGNETIC-FIELD; TAIL; AVERAGE; MODEL; POSITION; SHAPE; MAGNETOPAUSE AB A search was conducted for the signatures of Birkeland currents in the Earth's magnetic tail, using observed values of B(x) and B(y) from large sets of spacecraft data. The data were binned by x and y for - 10 > x(GSM) > -35 and \y(GSM)\ less-than-or-equal-to 20R(E) (less-than-or-equal-to 30R(E) for x(GSM) less-than-or-equal-to -25R(E)) and in each bin their distribution in the (B(z), B(y)) plane was fitted by least squares to a piecewise linear function. That gave average x-y distributions of the flaring angle between B(x), and the x direction, as well as that angle's variation across the thickness of the plasma sheet. Angles obtained in the central plasma sheet differed from those derived near the lobe boundary. That is the expected signature if earthward or tailward Birkeland current sheets are embedded in the plasma sheet, and from this difference we derived the dawn-dusk profiles of the tail Birkeland currents for several x(GSM) intervals. It was found that (1) the Birkeland currents have the sense of region 1 currents, when mapped to the ionosphere; (2) both the linear current density (kiloamperes/R(E)) and the net magnitude of the field-aligned currents decrease rapidly down the tail; (3) the total Birkeland current at x almost-equal-to - 10R(E) equals almost-equal-to 500-700 kA, which is approximately 30% of the net region 1 current observed at ionospheric altitudes, in agreement with model mapping results; and (4) the B(z) and B(y) components of the interplanetary magnetic field influence the distribution of Birkeland currents in the tail. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. RP TSYGANENKO, NA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 27 TC 24 Z9 24 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 19455 EP 19464 DI 10.1029/93JA01922 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700050 ER PT J AU BARBOSA, DD KURTH, WS GURNETT, DA SITTLER, EC AF BARBOSA, DD KURTH, WS GURNETT, DA SITTLER, EC TI ELECTROSTATIC WAVE EXCITATION IN PLANETARY MAGNETOSPHERES - APPLICATION TO NEPTUNE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SATURNS MAGNETOSPHERE; VOYAGER-2; TORUS; ELECTRONS AB Voyager 2 observations of electrostatic electron and ion cyclotron harmonic waves in Neptune's magnetosphere are addressed. A model of electron Bernstein modes generated by a loss cone distribution of superthermal electrons is scaled to Neptune parameters and a comparison of theory with the observed electron flux shows good agreement. A model of proton Bernstein modes generated by a ring distribution of Tritonogenic nitrogen ions is also investigated and satisfactory agreement with the data are obtained compatible with known properties of the magnetosphere. The success of the model in accounting for electrostatic emissions observed by Voyager over a wide range of sampled parameters recommends its general applicability to planetary magnetospheres. C1 UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP BARBOSA, DD (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024, USA. NR 20 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1993 VL 98 IS A11 BP 19465 EP 19469 DI 10.1029/93JA01988 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MG097 UT WOS:A1993MG09700051 ER PT J AU FRANKLIN, JA ENGELLAND, SA AF FRANKLIN, JA ENGELLAND, SA TI DESIGN AND PILOTED SIMULATION OF INTEGRATED FLIGHT PROPULSION CONTROLS FOR STOVL AIRCRAFT SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB An integrated flight/propulsion control system has been designed for operation of short takeoff and vertical landing (STOVL) fighter aircraft over the low-speed, powered-lift flight envelope. The control system employs command modes for attitude, flightpath angle, and nightpath acceleration during transition, and translational velocity command for hover and vertical landing. In this paper, only the longitudinal modes of control are discussed. Piloted evaluations of the control system have been conducted on Ames Research Center's Vertical Motion Simulator. Results indicate that level 1 flying qualities are achieved during transition and vertical landing over a wide range of wind, atmospheric turbulence, and visibility conditions. RP FRANKLIN, JA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 993 EP 998 DI 10.2514/3.21119 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800001 ER PT J AU BURKEN, JJ AF BURKEN, JJ TI FLIGHT-DETERMINED MULTIVARIABLE STABILITY ANALYSIS AND COMPARISON OF A CONTROL-SYSTEM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID DESIGN AB Singular value analysis can give conservative stability margin results. Applying structure to the uncertainty can reduce this conservatism. This paper describes flight-determined stability margins for the X-29A lateral-directional, multiloop control system. These margins are compared with the predicted unscaled structured singular values, scaled structured singular values, and conventional single-loop phase and gain margins. The algorithm was further evaluated with flight data by changing the roll-rate-to-aileron-command-feedback gain by +/- 20%. Minimum eigenvalues of the return difference matrix that bound the singular values are also presented. Extracting multiloop singular values from flight data and analyzing the feedback gain variations validates this technique as a measure of robustness. This analysis can be used for near-real-time night monitoring and safety testing. RP BURKEN, JJ (reprint author), NASA,DRYDEN FLIGHT RES FACIL,DYNAM & CONTROL BRANCH,MAIL STOP D4840,POB 273,EDWARDS AFB,CA 93523, USA. NR 12 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1026 EP 1031 DI 10.2514/3.21123 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800005 ER PT J AU POWELL, RW BRAUN, RD AF POWELL, RW BRAUN, RD TI 6-DEGREE-OF-FREEDOM GUIDANCE AND CONTROL ANALYSIS OF MARS AEROCAPTURE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A six-degree-of-freedom (6DOF) simulation has been developed to investigate the control and guidance issues of a Mars aerobraking vehicle. The guidance algorithm used is a predictor-corrector guidance formulation designed to control the exit orbital apoapsis and wedge angle using bank angle modulation. Major features of this predictor-corrector guidance algorithm include 1) integration of the 3DOF equations of motion within an inner-loop simulation, 2) load-relief logic, 3) finite roll rates, and 4) an aerodynamic feedback multiplier. The algorithm has been shown to be capable of successfully guiding the vehicle through combinations of atmospheric density dispersions, aerodynamic mispredictions, and off-nominal atmospheric interface conditions. This study demonstrated that the addition of vehicle dynamics to the Mars aerobraking simulation does not significantly impact mission feasibility. That is, a good control system design coupled with an adaptive guidance algorithm can ensure mission success (as measured by the required postaerocapture propulsive maneuvers) in the presence of numerous off-nominal conditions. RP POWELL, RW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23681, USA. NR 16 TC 19 Z9 19 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1038 EP 1044 DI 10.2514/3.21125 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800007 ER PT J AU WIE, B LIU, Q BAUER, F AF WIE, B LIU, Q BAUER, F TI CLASSICAL AND ROBUST H-INFINITY CONTROL REDESIGN FOR THE HUBBLE-SPACE-TELESCOPE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID UNMODELED DYNAMICS; UNCERTAINTY; DESIGN AB A control redesign problem of the Hubble Space Telescope for reducing the effects of solar array vibrations on telescope pointing jitter is investigated. Both classical and H(infinity) control design methodologies are employed for such a control problem with a noncollocated actuator and sensor pair. This paper successfully demonstrates the effectiveness of a dipole concept for precision line-of-sight pointing control in the presence of significant structural vibrations. Proposed controllers with two dipoles effectively reduce the effects of the solar array induced disturbances at 0.12 and 0.66 Hz on pointing jitter. C1 NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,GREENBELT,MD 20771. RP WIE, B (reprint author), ARIZONA STATE UNIV,DEPT MECH & AEROSP ENGN,TEMPE,AZ 85287, USA. NR 18 TC 22 Z9 28 U1 1 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1069 EP 1077 DI 10.2514/3.21129 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800011 ER PT J AU LEE, AY AF LEE, AY TI COMPONENT MODES DAMPING ASSIGNMENT METHODOLOGY FOR ARTICULATED, MULTIFLEXIBLE BODY STRUCTURES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB To simulate the dynamical motion of articulated, multiflexible body structures, one can use multibody simulation packages such as DISCOS. To this end, one must supply appropriate reduced-order models for all of the flexible components involved. The component modes projection and assembly model reduction (COMPARE) methodology is one way to construct these reduced-order component models, which when reassembled capture important system input-to-output mapping of the full-order model at multiple system configurations of interest. In conjunction, we must also supply component damping matrices which when reassembled generate a system damping matrix that has certain desirable properties. The problem of determining the damping factors of components' modes to achieve a given system damping matrix is addressed here. To this end, we must establish from first principles a matrix-algebraic relation between the system's modal damping matrix and the components' modal damping matrices. An unconstrained/constrained optimization problem can then be formulated to determine the component modes' damping factors that best satisfy that matrix-algebraic relation. The effectiveness of the developed methodology, called ModeDamp, has been successfully demonstrated on a high-order, finite element model of the Galileo spacecraft. RP LEE, AY (reprint author), JET PROP LAB,GUIDANCE & CONTROL SECT,PASADENA,CA 91109, USA. NR 18 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1101 EP 1108 DI 10.2514/3.21133 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800015 ER PT J AU HORTA, LG JUANG, JN LONGMAN, RW AF HORTA, LG JUANG, JN LONGMAN, RW TI DISCRETE-TIME MODEL-REDUCTION IN LIMITED FREQUENCY RANGES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SYSTEMS AB A mathematical formulation for model reduction of discrete-time systems such that the reduced-order model represents the system in a particular frequency range is discussed. The algorithm transforms the full-order system into balanced coordinates using frequency-weighted discrete controllability and observability grammians. In this form a criterion is derived to guide truncation of states based on their contribution to the frequency range of interest. Minimization of the criterion is accomplished without need for numerical optimization. Balancing requires the computation of discrete frequency-weighted grammians. Closed-form solutions for the computation of frequency-weighted grammians are developed. Numerical examples are discussed to demonstrate the algorithm. RP HORTA, LG (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 9 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1125 EP 1130 DI 10.2514/3.21136 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800018 ER PT J AU GIESY, DP LIM, KB AF GIESY, DP LIM, KB TI H-INFINITY NORM SENSITIVITY FORMULA WITH CONTROL-SYSTEM DESIGN APPLICATIONS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SPACE AB An analytic formula for the sensitivity of singular value peak variation with respect to parameter variation is derived. As a corollary, the derivative of the H(infinity) norm of a stable transfer function with respect to a parameter is presented. It depends on the first derivative of the transfer function with respect to the parameter. If the transfer function has a linear system realization whose matrices depend on the parameter, then an analytic formula for this derivative is derived, and an efficient algorithm for calculating the H(infinity) norm sensitivity is described. Examples are given that provide numerical verification of the H(infinity) norm sensitivity formula and that demonstrate its utility in designing control systems satisfying H(infinity) norm constraints. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP GIESY, DP (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666, USA. NR 15 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1993 VL 16 IS 6 BP 1138 EP 1145 DI 10.2514/3.21138 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MF998 UT WOS:A1993MF99800020 ER PT J AU KELLEY, RL MOSELEY, SH STAHLE, CK SZYMKOWIAK, AE JUDA, M MCCAMMON, D ZHANG, J AF KELLEY, RL MOSELEY, SH STAHLE, CK SZYMKOWIAK, AE JUDA, M MCCAMMON, D ZHANG, J TI DEVELOPMENT OF MICROCALORIMETERS FOR HIGH-RESOLUTION X-RAY SPECTROSCOPY SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY ID THERMAL DETECTORS AB We have been developing microcalorimeters for use in X-ray spectroscopy. These devices have very high spectral resolution (several eV) and high intrinsic quantum efficiency, making them particularly useful for astrophysical applications. Work has evolved over a 10 year period from simple proof-of-concept devices to functional arrays. An energy resolution of 7.3 eV at 6 keV has been demonstrated for the smallest absorbers used, and a resolution of approximately 12 eV for devices with a pixel area of approximately 1/4 mm2. Present work is focused on making 36 pixel monolithic arrays with individual pixel areas of up to approximately 1 mm2. As the size of the absorbing area is increased, high spectral resolution is more difficult to achieve not only because of the increased heat capacity, but also because of problems with uniform thermalization. We have observed non-ideal effects in large absorbers that must be controlled and minimized before the fabrication of low noise, larger area microcalorimeters can be accomplished. C1 UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. RP KELLEY, RL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012; OI Juda, Michael/0000-0002-4375-9688 NR 7 TC 16 Z9 16 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 225 EP 230 DI 10.1007/BF00693424 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200007 ER PT J AU AUDLEY, MD KELLEY, RL RAWLEY, GL AF AUDLEY, MD KELLEY, RL RAWLEY, GL TI A PROTOTYPE KINETIC INDUCTANCE THERMOMETER FOR X-RAY CALORIMETRY SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB We have measured the parameters of a prototype kinetic inductance thermometer for X-ray calorimetry which was fabricated at GSFC. This device consists of an aluminum meander strip and ground plane and operates at about 1.2 K. For thermal isolation, the device was suspended on Kevlar threads along with a heater and a germanium resistance thermometer. The meander strip was included in the tank circuit of a 10 MHz tunnel diode oscillator operating at about 1 K. The kinetic inductance was measured by monitoring the oscillator frequency. The temperature dependence of the kinetic inductance was found to be in reasonable agreement with the behavior predicted from the device parameters. Having characterized this proof-of-concept device, we intend to investigate the suitability of kinetic inductors operating at lower temperatures for X-ray calorimetry. C1 APPL RES CORP,LANDOVER,MD 20785. UNIV MARYLAND,COLL PK,MD 20742. RP AUDLEY, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Kelley, Richard/K-4474-2012 NR 10 TC 14 Z9 14 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 245 EP 250 DI 10.1007/BF00693427 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200010 ER PT J AU OSTERMAN, DP PATT, R AUDLEY, D KELLEY, R AF OSTERMAN, DP PATT, R AUDLEY, D KELLEY, R TI AN X-RAY MICROCALORIMETER WITH KINETIC INDUCTANCE THERMOMETER AND DC SQUID READ-OUT SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB This article reports on the development of a microcalorimeter for X-ray spectroscopy Which uses a superconducting kinetic inductance thermometer. The monolithic construction combines the thermometer and all other components on a single substrate. These include a dc SQUID for measuring the thermometer output, and a micromachined ''leg and panel'' structure for low thermal conductance and capacitance. An all-niobium prototype has been fabricated, and its operation verified qualitatively above 4 K C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP OSTERMAN, DP (reprint author), HYPRES INC,ELMSFORD,NY 10591, USA. RI Kelley, Richard/K-4474-2012 NR 9 TC 7 Z9 7 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 251 EP 256 DI 10.1007/BF00693428 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200011 ER PT J AU STAHLE, CK KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE JUDA, M MCCAMMON, D ZHANG, J AF STAHLE, CK KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE JUDA, M MCCAMMON, D ZHANG, J TI THERMALIZATION OF X-RAYS IN EVAPORATED TIN AND BISMUTH-FILMS USED AS THE ABSORBING MATERIALS IN X-RAY CALORIMETERS SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB We have investigated the use of evaporated tin and bismuth films as the absorbing materials in X-ray calorimeters. When the films were deposited directly on monolithic silicon calorimeters, the output signal from both Sn and Bi devices was strongly dependent on the location of the absorption event relative to the ion-implanted thermistors, presumably indicating thermistor sensitivity to a non-thermal spectrum of phonons. With Sn films we also observed that a component of the thermalization proceeded slowly, relative to a complete thermalization reference. The thermalization function could be modified by trapping magnetic flux within the film. In order to distinguish thermalization effects in the films from the thermistor sensitivity to energetic phonons, we deposited Sn and Bi films on thin Si substrates which we then affixed to calorimeters using epoxy. With glued Sn films, we were able to attain as good as 13.6 eV resolution of 6 keV X-rays with no excess broadening of the line beyond the width of the baseline, while similarly made Bi devices showed excess broadening. C1 UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. RP STAHLE, CK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012; OI Juda, Michael/0000-0002-4375-9688 NR 2 TC 8 Z9 8 U1 0 U2 3 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 257 EP 262 DI 10.1007/BF00693429 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200012 ER PT J AU SZYMKOWIAK, AE KELLEY, RL MOSELEY, SH STAHLE, CK AF SZYMKOWIAK, AE KELLEY, RL MOSELEY, SH STAHLE, CK TI SIGNAL-PROCESSING FOR MICROCALORIMETERS SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB Most of the power in the signals from microcalorimeters occurs al relatively low frequencies. At these frequencies, typical amplifiers will have significant amounts of l/f noise. Our laboratory systems can also suffer from pickup at several harmonics of the AC power line, and from microphonic pickup at frequencies that vary with the configuration of the apparatus. We have developed some optimal signal processing techniques in order to construct the best possible estimates of our pulse heights in the presence of these non-ideal effects. In addition to a discussion of our laboratory systems, we present our plans for providing this kind of signal processing in flight experiments. RP SZYMKOWIAK, AE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012 NR 0 TC 75 Z9 75 U1 0 U2 5 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 281 EP 285 DI 10.1007/BF00693433 PG 5 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200016 ER PT J AU MCCAMMON, D CUI, W JUDA, M ZHANG, JH KELLEY, R MOSELEY, H STAHLE, C SZYMKOWIAK, A AF MCCAMMON, D CUI, W JUDA, M ZHANG, JH KELLEY, R MOSELEY, H STAHLE, C SZYMKOWIAK, A TI OPTIMIZATION OF DOPED SILICON AND GERMANIUM THERMISTORS SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY C1 NASA,GODDARD SPACE FLIGHT CTR,CODE 666,GREENBELT,MD 20771. RP MCCAMMON, D (reprint author), UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706, USA. RI Kelley, Richard/K-4474-2012 NR 0 TC 2 Z9 2 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 287 EP 287 DI 10.1007/BF00693434 PG 1 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200017 ER PT J AU STAHLE, CK WOUTERS, J KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE AF STAHLE, CK WOUTERS, J KELLEY, RL MOSELEY, SH SZYMKOWIAK, AE TI A SILICON COMPOSITE THERMAL AND IONIZATION X-RAY-DETECTOR SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB We have made a combination calorimetric and ionization X-ray detector by attaching a silicon p-i-n diode to a monolithic silicon microcalorimeter. Applying a bias to the diode enhanced the thermal signal, and with a reverse bias of 25 V we achieved a detection threshold of 8 eV, based upon energy scaling of the standard deviation of the baseline noise. We were able to measure a charge signal in the absence of applied bias on the diode, demonstrating that the junction potential is sufficient to drift the ionized charges to the contacts. A fraction of the electron-hole pairs created became trapped, manifested by excess broadening in the measured thermal signal and by using the variation of the thermal signal magnitude with reverse bias to fit for the fraction of charge that is trapped. The ability to collect charge without an applied bias is necessary to produce high resolution combination thermal and ionization detectors. C1 KATHOLIEKE UNIV LEUVEN,INST KERN STRALINGSFYS,B-3001 LOUVAIN,BELGIUM. RP STAHLE, CK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012; Wouters, Jan/D-1800-2015 OI Wouters, Jan/0000-0002-0093-698X NR 4 TC 1 Z9 1 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 411 EP 416 DI 10.1007/BF00693453 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200036 ER PT J AU GAIDIS, MC FRIEDRICH, S PROBER, DE SZYMKOWIAK, AE MOSELEY, SH AF GAIDIS, MC FRIEDRICH, S PROBER, DE SZYMKOWIAK, AE MOSELEY, SH TI SUPERCONDUCTING NB-TA-AL-ALOX-AL TUNNEL-JUNCTIONS FOR X-RAY-DETECTION SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY ID QUASIPARTICLE AB We report progress on the microlithographic fabrication of Nb-Ta-Al-AlOx-Al structures designed for x-ray detection. These structures use bandgap engineering both for quasiparticle trapping to increase the collection efficiency and to prevent quasiparticle diffusion out through the leads. Non-standard tunnel junction geometries are used to reduce the magnetic field needed to suppress the Josephson current for stable biasing. The performance of these devices as alpha particle detectors is presented. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GAIDIS, MC (reprint author), YALE UNIV,DEPT APPL PHYS,NEW HAVEN,CT 06520, USA. RI Moseley, Harvey/D-5069-2012; Gaidis, Michael/D-3327-2013 NR 11 TC 14 Z9 14 U1 0 U2 2 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 605 EP 610 DI 10.1007/BF00693483 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200066 ER PT J AU SAULNIER, GG ZACHER, RA FRITZ, GG HUNT, B LEDUC, HG JUDAS, A AF SAULNIER, GG ZACHER, RA FRITZ, GG HUNT, B LEDUC, HG JUDAS, A TI NBN/MGO/NBN SUPERCONDUCTING TUNNEL-JUNCTIONS AS X-RAY-DETECTORS SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY ID QUASIPARTICLE; RESOLUTION; ENERGY AB We report on our work using NbN/MgO/NbN junctions for the detection of x-rays. Detectors based on superconducting tunneling junctions offer the prospect of energy resolution over an order of magnitude higher than is obtainable with the current generation of semiconductor-based detectors NbN is interesting due to the possibility of its use in trapping layer devices. The junctions were fabricated at the NASA Jet Propulsion Laboratory (JPL) with an area of 4 mum by 4 mum. They were tested at the Naval Research Laboratory (NRL) in an applied magnetic field of approximately 250 gauss, a current bias of several hundred nanoamps and an operating temperature of 1.7 K. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. NASA,JET PROP LAB,PASADENA,CA 91109. RP SAULNIER, GG (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375, USA. NR 9 TC 1 Z9 1 U1 1 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 653 EP 658 DI 10.1007/BF00693491 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200074 ER PT J AU NAHUM, M MARTINIS, JM CASTLES, S AF NAHUM, M MARTINIS, JM CASTLES, S TI HOT-ELECTRON MICROCALORIMETERS FOR X-RAY AND PHONON DETECTION SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL WORKSHOP ON LOW TEMPERATURE DETECTORS ( LTD-5 ) CY JUL 29-AUG 03, 1993 CL UNIV CALIF BERKELEY, BERKELEY, CA HO UNIV CALIF BERKELEY AB We propose a novel hot-electron microcalorimeter for measurements of x-rays or phonons produced by the interaction of a high energy particle with the underlying substrate. This type of detector uses a normal metal film to absorb the incoming excitation which subsequently heats the electrons above the lattice temperature. The temperature of the electrons is measured from the current - voltage characteristics of a superconductor-insulator-normal metal tunnel junction, where part of the absorber forms the normal electrode. We present simple calculations of the energy sensitivity of the junction and of the ultimate performance of x-ray and phonon detectors. We also present preliminary measurements of prototype devices which were used to test the basic detector physics. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP NAHUM, M (reprint author), NATL INST STAND & TECHNOL,BOULDER,CO 80303, USA. NR 10 TC 24 Z9 24 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD NOV PY 1993 VL 93 IS 3-4 BP 733 EP 738 DI 10.1007/BF00693504 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA MK002 UT WOS:A1993MK00200087 ER PT J AU TOTH, RA AF TOTH, RA TI (HDO)-O-16, (HDO)-O-18, AND (HDO)-O-17 TRANSITION FREQUENCIES AND STRENGTHS STRENGTHS IN THE NU(2)-BANDS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID LINE POSITIONS; HDO; SUBMILLIMETER; SPECTROSCOPY; (H2O)-O-16; SPECTRA; REGION; BANDS; WATER RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 55 Z9 57 U1 0 U2 6 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD NOV PY 1993 VL 162 IS 1 BP 20 EP 40 DI 10.1006/jmsp.1993.1266 PG 21 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA MC296 UT WOS:A1993MC29600003 ER PT J AU TOTH, RA AF TOTH, RA TI (D2O)-O-16 AND (D2O)-O-18 TRANSITION FREQUENCIES AND STRENGTHS IN THE NU(2)-BANDS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID LINE POSITIONS; V2 BAND; HDO; REGION RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 44 Z9 44 U1 0 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD NOV PY 1993 VL 162 IS 1 BP 41 EP 54 DI 10.1006/jmsp.1993.1267 PG 14 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA MC296 UT WOS:A1993MC29600004 ER PT J AU OLSHAUSEN, BA ANDERSON, CH VANESSEN, DC AF OLSHAUSEN, BA ANDERSON, CH VANESSEN, DC TI A NEUROBIOLOGICAL MODEL OF VISUAL-ATTENTION AND INVARIANT PATTERN-RECOGNITION BASED ON DYNAMIC ROUTING OF INFORMATION SO JOURNAL OF NEUROSCIENCE LA English DT Article DE VISUAL ATTENTION; RECOGNITION; MODEL; GATING; VISUAL CORTEX; PULVINAR; CONTROL ID LATERAL GENICULATE-NUCLEUS; POSTERIOR PARIETAL CORTEX; NEURAL NETWORK MODEL; SELECTIVE ATTENTION; MACAQUE MONKEY; STRIATE CORTEX; INFEROTEMPORAL CORTEX; SUPERIOR COLLICULUS; INFERIOR PULVINAR; SPATIAL ATTENTION AB We present a biologically plausible model of an attentional mechanism for forming position- and scale-invariant representations of objects in the visual world. The model relies on a set of control neurons to dynamically modify the synaptic strengths of intracortical connections so that information from a windowed region of primary visual cortex (V1) is selectively routed to higher cortical areas. Local spatial relationships (i.e., topography) within the attentional window are preserved as information is routed through the cortex. This enables attended objects to be represented in higher cortical areas within an object-centered reference frame that is position and scale invariant. We hypothesize that the pulvinar may provide the control signals for routing information through the cortex. The dynamics of the control neurons are governed by simple differential equations that could be realized by neurobiologically plausible circuits. In preattentive mode, the control neurons receive their input from a low-level ''saliency map'' representing potentially interesting regions of a scene. During the pattern recognition phase, control neurons are driven by the interaction between top-down (memory) and bottom-up (retinal input) sources. The model respects key neurophysiological, neuroanatomical, and psychophysical data relating to attention, and it makes a variety of experimentally testable predictions. C1 CALTECH,COMPUTAT & NEURAL SYST PROGRAM,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. FU NIMH NIH HHS [MH19138-02 T32] NR 122 TC 471 Z9 480 U1 3 U2 28 PU SOC NEUROSCIENCE PI WASHINGTON PA 11 DUPONT CIRCLE, NW, STE 500, WASHINGTON, DC 20036 SN 0270-6474 J9 J NEUROSCI JI J. Neurosci. PD NOV PY 1993 VL 13 IS 11 BP 4700 EP 4719 PG 20 WC Neurosciences SC Neurosciences & Neurology GA MF297 UT WOS:A1993MF29700012 PM 8229193 ER PT J AU HARGENS, AR BOTTE, MJ SWENSON, MR GELBERMAN, RH RHOADES, CE AKESON, WH AF HARGENS, AR BOTTE, MJ SWENSON, MR GELBERMAN, RH RHOADES, CE AKESON, WH TI EFFECTS OF LOCAL COMPRESSION ON PERONEAL NERVE FUNCTION IN HUMANS SO JOURNAL OF ORTHOPAEDIC RESEARCH LA English DT Article ID LOWER-EXTREMITY TRAUMA; COMPARTMENT SYNDROME; PRESSURE; CATHETER AB A new apparatus was developed to compress the anterior compartment selectively and reproducibly in humans. Thirty-five normal volunteers were studied to determine short-term thresholds of local tissue pressure that produce significant neuromuscular dysfunction. Local tissue fluid pressure adjacent to the deep peroneal nerve was elevated by the compression apparatus and continuously monitored for 2-3 h by the slit catheter technique. Elevation of tissue fluid pressure to within 35-40 mm Hg of diastolic blood pressure (approximately 40 mm Hg of in situ pressure in our subjects) elicited a consistent progression of neuromuscular deterioration including, in order, (a) gradual loss of sensation, as assessed by Semmes-Weinstein monofilaments, (b) subjective complaints, (c) reduced nerve conduction velocity, (d) decreased action potential amplitude of the extensor digitorum brevis muscle, and (e) motor weakness of muscles within the anterior compartment. Generally, higher intracompartmental pressures caused more rapid deterioration of neuromuscular function. In two subjects, when in situ compression levels were 0 and 30 mm Hg, normal neuromuscular function was maintained for 3 h. Threshold pressures for significant dysfunction were not always the same for each functional parameter studied, and the magnitudes of each functional deficit did not always correlate with compression level. This variable tolerance to elevated pressure emphasizes the need to monitor clinical signs and symptoms carefully in the diagnosis of compartment syndromes. The nature of the present studies was short term; longer term compression of myoneural tissues may result in dysfunction at lower pressure thresholds. C1 VET AFFAIRS MED CTR,DEPT ORTHOPAED,SAN DIEGO,CA. VET AFFAIRS MED CTR,DIV NEUROL,SAN DIEGO,CA. UNIV CALIF SAN DIEGO,MED CTR,LA JOLLA,CA 92093. HARVARD UNIV,MASSACHUSETTS GEN HOSP,SCH MED,DEPT ORTHOPAED SURG,BOSTON,MA 02114. RP HARGENS, AR (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035, USA. NR 22 TC 29 Z9 29 U1 1 U2 2 PU JOURNAL BONE JOINT SURGERY INC PI NEEDHAM PA 20 PICKERING ST, NEEDHAM, MA 02192 SN 0736-0266 J9 J ORTHOPAED RES JI J. Orthop. Res. PD NOV PY 1993 VL 11 IS 6 BP 818 EP 827 DI 10.1002/jor.1100110607 PG 10 WC Orthopedics SC Orthopedics GA MR350 UT WOS:A1993MR35000006 PM 8283326 ER PT J AU ANICICH, VG AF ANICICH, VG TI EVALUATED BIMOLECULAR ION-MOLECULE GAS-PHASE KINETICS OF POSITIVE-IONS FOR USE IN MODELING PLANETARY-ATMOSPHERES, COMETARY COMAE, AND INTERSTELLAR CLOUDS SO JOURNAL OF PHYSICAL AND CHEMICAL REFERENCE DATA LA English DT Review DE EVALUATED RESULTS; ION-MOLECULE REACTIONS; POSITIVE IONS; PRODUCT DISTRIBUTIONS; REACTION RATE COEFFICIENTS AB Recommendations of reaction rate coefficients and product distributions for bimolecular positive ion-molecule reactions of importance in planetary atmospheres, cometary comae, and interstellar clouds are presented. Two publications Anicich and Huntress, Astrophys. J. Suppl. Ser. 62, 553 (1986) and Anicich, Astrophys. J. Suppl. Ser. 84, 215 (1993) served as the basis for this evaluation, which covers the literature from 1965 through 1991 with some additional citations missed in the original surveys. RP ANICICH, VG (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 343 Z9 343 U1 3 U2 27 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0047-2689 J9 J PHYS CHEM REF DATA JI J. Phys. Chem. Ref. Data PD NOV-DEC PY 1993 VL 22 IS 6 BP 1469 EP 1569 PG 101 WC Chemistry, Multidisciplinary; Chemistry, Physical; Physics, Multidisciplinary SC Chemistry; Physics GA MM124 UT WOS:A1993MM12400004 ER PT J AU HAIDVOGEL, DB BECKMANN, A CHAPMAN, DC LIN, RQ AF HAIDVOGEL, DB BECKMANN, A CHAPMAN, DC LIN, RQ TI NUMERICAL-SIMULATION OF FLOW AROUND A TALL ISOLATED SEAMOUNT .2. RESONANT GENERATION OF TRAPPED WAVES SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID TIDE-TOPOGRAPHY INTERACTIONS; STRATIFIED SHELF SEA; INTERNAL TIDES; CURRENTS; OCEAN; RECTIFICATION; SIGMA; BANK AB A sigma-coordinate, primitive equation ocean circulation model is used to explore the problem of the resonant generation of trapped waves about a tall, circular, isolated seamount by an incident oscillatory barotropic current. The numerical solutions are used to extend prior studies into the fully nonlinear regime, and in particular to quantify and interpret the occurrence of residual circulation. Specific attention is also devoted to the dependence of the resonance and rectification mechanisms on stratification, forcing frequency, and choice of subgrid-scale viscous closure. Resonantly generated trapped waves of significant amplitude are found to occur broadly in parameter space; a precise match between the frequency of the imposed incident current and the frequency of the trapped free wave is not necessary to produce substantial excitation of the trapped wave. The maximum amplification factors produced in these numerical solutions, O(100) times the strength of the incident current, are consistent with previous studies. In the presence of nonlinear advection, strong residual currents are produced. The time-mean circulation about the seamount is dominated by a strong bottom-intensified, anticyclonic circulation closely trapped to the seamount. Maximum local time-mean current amplitudes are found to be as large as 37% of the magnitude of the propagating waves. In addition to the strong anticyclonic residual flow, there is a weaker secondary circulation in the vertical-radial plane characterized by downwelling over the top of the seamount at all depths. Maximum vertical downwelling rates of several tens of meters per day occur at the summit of the seamount. The vertical mass flux implied by this systematic downwelling is balanced by a slow radial flux of mass directed outward along the flanks of the seamount. Time-mean budgets for the radial and azimuthal components of momentum show that horizontal eddy fluxes of momentum are responsible for transporting net radial and azimuthal momentum from the far field to the upper flanks of the seamount. There, Coriolis and pressure gradient forces provide the dominant balances in the radial direction. However, the Coriolis force and viscous effects provide the primary balance for the azimuthal component. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEAN ICE BRANCH,GREENBELT,MD 20771. WOODS HOLE OCEANOG INST,WOODS HOLE,MA 02543. INST MEERESKUNDE,THEORET OZEANOG ABT,KIEL,GERMANY. RP HAIDVOGEL, DB (reprint author), RUTGERS UNIV,INST MARINE & COASTAL SCI,POB 231,NEW BRUNSWICK,NJ 08903, USA. NR 18 TC 43 Z9 43 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD NOV PY 1993 VL 23 IS 11 BP 2373 EP 2391 DI 10.1175/1520-0485(1993)023<2373:NSOFAA>2.0.CO;2 PG 19 WC Oceanography SC Oceanography GA MF846 UT WOS:A1993MF84600005 ER PT J AU COLEMAN, CC EPSTEIN, AB EBERT, RJ AF COLEMAN, CC EPSTEIN, AB EBERT, RJ TI PHOTOIMAGING IN MERCURIC IODIDE POLYCRYSTALLINE FILMS SO JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS LA English DT Article DE PHOTOIMAGING; HGI2; PBI2; THIN FILMS; SUBLIMATION AB We have demonstrated a photoimaging process in thin polycrystalline films of the low temperature phase of semiconducting mercuric iodide for the first time. This process is shown to be due to a thermally activated photon enhanced sublimation which occurs above 50-degrees-C. C1 SLOAN TECHNOL,SANTA BARBARA,CA 93103. CALTECH,JET PROP LAB,PASADENA,CA 91125. RP COLEMAN, CC (reprint author), CALIF STATE UNIV LOS ANGELES,DEPT PHYS & ASTRON,5151 UNIV DR,LOS ANGELES,CA 90032, USA. NR 9 TC 5 Z9 5 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-3697 J9 J PHYS CHEM SOLIDS JI J. Phys. Chem. Solids PD NOV PY 1993 VL 54 IS 11 BP 1497 EP 1500 DI 10.1016/0022-3697(93)90342-O PG 4 WC Chemistry, Multidisciplinary; Physics, Condensed Matter SC Chemistry; Physics GA MW488 UT WOS:A1993MW48800007 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI SYNTHESIS AND PROPERTIES OF POLY[ARYLENE ETHER (N-ARYLENEBENZIMIDAZOLE)]S SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article DE POLY(ARYLENE ETHER)S; POLY(N-ARYLENE BENZIMIDAZOLE)S; HIGH-TEMPERATURE POLYMERS; HIGH-PERFORMANCE POLYMERS ID POLY(ARYLENE; POLYMERIZATION; CHEMISTRY AB Poly (arylene ether) s containing N-arylenebenzimidazole groups were prepared by the aromatic nucleophilic displacement reaction of two new bis(hydroxyphenyl-N-arylenebenzimidazole)s with activated aromatic difluorides in sulfolane at 200-degrees-C in the presence of anhydrous potassium carbonate. The bis (hydroxyphenyl-N-arylenebenzimidazole)s were prepared from bis (o-aminoanilino)arylenes and phenyl-4-hydroxybenzoate. The polymers were soluble in N-methyl-2-pyrrolidinone and m-cresol and exhibited inherent viscosities from 0.37-0.86 dL/g and glass transition temperatures from 219-289-degrees-C. Thermogravimetric analyses showed 5% weight losses from 463-506-degrees-C in air and 467-522-degrees-C in nitrogen. Unoriented thin films exhibited tensile strengths, moduli, and break elongations at 23-degrees-C of 10.2-12.5 ksi, 318-365 ksi, and 4-7%, respectively, and at 177-degrees-C of 5.1-6.9 ksi, 256-296 ksi, and 1-5%, respectively. A 50: 50 random copolymer prepared from 1,3-bis(4-fluorobenzoyl)benzene, 1,1'-(4,4'-biphenylene)-bis[2-(4-hydroxyphenyl)benzimidazole], and 5,5'-bis[2-(4-hydroxyphenyl)benzimidazole] exhibited higher moisture absorption and lower tensile properties than those predicted by a rule of mixtures relationship. The chemical, physical, and mechanical properties of these polymers are discussed. (C) 1993 John Wiley & Sons, Inc. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 38 TC 18 Z9 18 U1 2 U2 6 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD NOV PY 1993 VL 31 IS 12 BP 3099 EP 3108 DI 10.1002/pola.1993.080311226 PG 10 WC Polymer Science SC Polymer Science GA MC588 UT WOS:A1993MC58800026 ER PT J AU CARLSON, JR PAO, SP ABDOLHAMID, KS AF CARLSON, JR PAO, SP ABDOLHAMID, KS TI COMPUTATIONAL ANALYSIS OF VENTED SUPERSONIC EXHAUST NOZZLES USING A MULTIBLOCK MULTIZONE STRATEGY SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A high-expansion ratio axisymmetric nozzle with and without longitudinal trailing-edge slots has been examined. Solutions were determined using a three-dimensional Navier-Stokes computer code. These results were compared with experimental data to determine the accuracy of the code for nozzle applications. Additionally, off-body flow physics were examined to understand the changes in nozzle performance with differing operating conditions. Highly overexpanded and near-design jet exhaust flows were simulated exhausting into subsonic and supersonic freestream Mach numbers. Pressure and velocity vector flowfields are shown and the predicted internal nozzle performance is compared with experimental data. Solutions were developed using laminar viscous stresses and thin-layer approximations. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23681. RP CARLSON, JR (reprint author), NASA,LANGLEY RES CTR,DIV APPL AERODYNAM,PROP AERODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 10 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1993 VL 9 IS 6 BP 834 EP 839 DI 10.2514/3.23697 PG 6 WC Engineering, Aerospace SC Engineering GA MG559 UT WOS:A1993MG55900006 ER PT J AU BAUER, A GODON, M CARLIER, J MA, Q TIPPING, RH AF BAUER, A GODON, M CARLIER, J MA, Q TIPPING, RH TI ABSORPTION BY H2O AND H2O-N-2 MIXTURES AT 153 GHZ SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID ATMOSPHERIC WATER-VAPOR; LINE-SHAPE THEORY; TEMPERATURE-DEPENDENCE; PERTURBER DEPENDENCES; CONTINUUM ABSORPTION; INFRARED-ABSORPTION; FAR WINGS; 183 GHZ; ATTENUATION; MM AB New experimental data on and a theoretical analysis of the absorption coefficient at 153 GHz are presented for pure water vapor and water vapor-nitrogen mixtures. This frequency is 30 GHz lower than the resonant frequency of the nearest strong water line (183 GHz) and complements our previous measurements at 213 GHz. The pressure dependence is observed to be quadratic in the case of pure water vapor, while in the case of mixtures there are both linear and quadratic density components. By fitting our experimental data taken at several temperatures we have obtained the temperature dependence of the absorption. Our experimental data are compared to several theoretical models with and without a continuum contribution, and we find that none of the models is in very good agreement with the data; in the case of pure water vapor, the continuum contribution calculated using the recent theoretical absorption gives the best results. In general, the agreement between the data and the various models is less satisfactory than found previously in the high-frequency wing. The anisotropy in the observed absorption differs from that currently used in atmospheric models. C1 UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. UNIV LILLE 1,SPECT HERTZIENNE LAB,CNRS,F-59655 VILLENEUVE DASCQ,FRANCE. COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10025. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. NR 76 TC 19 Z9 19 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV PY 1993 VL 50 IS 5 BP 463 EP 475 DI 10.1016/0022-4073(93)90039-K PG 13 WC Optics; Spectroscopy SC Optics; Spectroscopy GA MK109 UT WOS:A1993MK10900003 ER PT J AU REUTER, DC SIROTA, JM AF REUTER, DC SIROTA, JM TI ABSOLUTE INTENSITIES AND FOREIGN GAS BROADENING COEFFICIENTS OF THE 11(1,10)[-11(2,10) AND 18(0,18)[-18(1,18) LINES IN THE NU-7 BAND OF C2H4 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID INFRARED OBSERVATIONS; TITANS ATMOSPHERE; SATURNIAN SYSTEM; ETHYLENE AB Absolute intensities and foreign gas broadening coefficients of the 18(0,18)<--18(1,18) and 11(1,10)<--11(2,10) transitions in the nu(7) band of C2H4 near 948 cm(-1) have been measured at a spectral resolution of similar to 5 x 10(-4) cm(-1) using tunable diode laser spectrometry. Ar, He, N-2, and O-2 were used as the broadening gases. In order to determine the temperature dependence of the broadening coefficient, data were obtained at temperatures ranging from 150 to 296 K. The absolute intensity of the 5(0,5)<--5(1,5) transition was also found at 296 K. A band strength of 339+/-10 cm(-2)atm(-1) was obtained from weighted averages of the individual line intensities and a rigid asymmetric top calculation. RP NASA, GODDARD SPACE FLIGHT CTR, PLANETARY SYST BRANCH, CODE 693, GREENBELT, MD 20771 USA. NR 18 TC 15 Z9 15 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 EI 1879-1352 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV PY 1993 VL 50 IS 5 BP 477 EP 482 DI 10.1016/0022-4073(93)90040-O PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA MK109 UT WOS:A1993MK10900004 ER PT J AU QUINN, RD KERSLAKE, TW AF QUINN, RD KERSLAKE, TW TI SOLAR DYNAMIC MODULES FOR SPACE STATION FREEDOM - THE RELATIONSHIP BETWEEN FINE-POINTING CONTROL AND THERMAL LOADING OF THE APERTURE PLATE .1. ANALYSIS SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB The dynamic equations for the simulation of Space Station Freedom configured with solar dynamic (SD) power modules are developed. The formulation permits the structure to be subjected to shuttle docking disturbances while being controlled with a ''natural'' vibration and tracking control approach. Multiple control cases can be performed for the purpose of investigating the relationship between actuator effort, SD pointing, and thermal loading on the receiver aperture plate. Transient, one-dimensional heat transfer equations are formulated to conservatively predict temperatures of the multilayered receiver aperture plate assembly and thermal stresses in its shield layer Numerical results from these analyses are presented in a companion paper (Part II). C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP QUINN, RD (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106, USA. NR 15 TC 0 Z9 0 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD NOV PY 1993 VL 115 IS 4 BP 189 EP 194 DI 10.1115/1.2930048 PG 6 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA MH940 UT WOS:A1993MH94000001 ER PT J AU KERSLAKE, TW QUINN, RD AF KERSLAKE, TW QUINN, RD TI SOLAR DYNAMIC MODULES FOR SPACE STATION FREEDOM - THE RELATIONSHIP BETWEEN FINE-POINTING CONTROL AND THERMAL LOADING OF THE APERTURE PLATE .2. RESULTS SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB The analytical approaches developed in a companion paper (Part I) were used to quantify the relationship between fine-pointing control and thermal loading of the aperture plate. Dynamic simulations of Space Station Freedom configured with solar dynamic (SD) power modules were performed. The structure was subjected to shuttle docking disturbances, while being controlled with a ''natural'' vibration and tracking control approach. Three control cases were investigated for the purpose of investigating the relationship between actuator effort, SD pointing, and thermal loading on the receiver aperture plate. Transient one-dimensional heat transfer analyses were performed to conservatively predict temperatures of the multilayered receiver aperture plate assembly and thermal stresses in its shield layer Results indicate that the proposed aperture plate is tolerant of concentrated flux impingement during short-lived structural disturbances. Pointing requirements may be loosened and the required control torques lessened from that previously specified. Downsizing and simplifying the joint drive system should result in a considerable savings in mass. C1 CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106. RP KERSLAKE, TW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD NOV PY 1993 VL 115 IS 4 BP 195 EP 199 DI 10.1115/1.2930049 PG 5 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA MH940 UT WOS:A1993MH94000002 ER PT J AU LEPSCH, RA NAFTEL, JC AF LEPSCH, RA NAFTEL, JC TI WINGED BOOSTER PERFORMANCE WITH COMBINED ROCKET AND AIRBREATHING PROPULSION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A conceptual level analysis was performed on a horizontal-takeoff, two-stage-to-orbit system consisting of a rocket and turboramjet powered hypersonic booster and a rocket-powered orbiter. The analysis includes estimates of vehicle aerodynamics, performance, and weights. Rocket and airbreathing systems on the booster are operated in parallel and at full thrust for ascent to a Mach 6 staging point, whereas cruise back is accomplished using airbreathing propulsion alone. Rocket engines on the orbiter are ignited at staging to propel the orbiter. Booster weights were determined for various combinations of rocket and airbreathing propulsion. The combinations that resulted in the lowest vehicle gross and empty weights were determined. Results show that the lowest gross weight occurs when only airbreathing engines are used. The empty weight of the all airbreathing booster, however, is quite high. Significant reductions in booster empty weight is accomplished with the addition of rocket engines. Also, the use of rockets on the booster greatly decreases the time to staging and the cruise-back distance. RP LEPSCH, RA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 25 TC 2 Z9 2 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 641 EP 646 DI 10.2514/3.26368 PG 6 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800001 ER PT J AU TAUBER, M CHARGIN, M HENLINE, W CHIU, A YANG, L HAMM, KR MIURA, H AF TAUBER, M CHARGIN, M HENLINE, W CHIU, A YANG, L HAMM, KR MIURA, H TI AEROBRAKE DESIGN STUDIES FOR MANNED MARS MISSIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The vehicle's mass tractions that must be devoted to the aerobrakes, including the heatshields, have been computed for a high-speed manned Mars entry of 8.6 km/s and with a 5 Earth g deceleration limit. Blunt, low lift-to-drag (L/D) ratio configurations with ballistic coefficients (m/C(D)A) of 100 and 200 kg/m2 have been studied. In addition, a delta-winged vehicle, with a medium L/D and a ballistic coefficient of 375 kg/m2, has been studied. Both insulative, radiatively cooled heatshields and ablators have been considered. After adding heatshielding and optimizing the structure, the aerobrakes' total mass fractions (heatshield plus aerobrake mass divided by the vehicle's total mass) varied from about 15 to 13% for ballistic coefficients of 100 and 200 kg/m2, respectively, for the blunt shapes and was slightly under 17% for the winged vehicle. The winged vehicle's aerobrake mass fraction was somewhat greater because the former's much higher ballistic coefficient resulted in more intense heating, thus requiring more thermal protection. The aerobrakes' mass fractions range from less than to slightly over the 15% value that is considered to make aerobraking indisputably superior to propulsive braking. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP TAUBER, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 20 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 656 EP 664 DI 10.2514/3.26370 PG 9 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800003 ER PT J AU ROKEY, MJ AF ROKEY, MJ TI MAGELLAN RADAR SPECIAL FLIGHT EXPERIMENTS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Special radar experiments were conducted by the Magellan spacecraft to explore resolution enhancement, stereo imaging, and effects of radar polarization. These are described herein, along with an overview of the Magellan mission to Venus and a summary of the spacecraft systems and capabilities. Unusual commanding constraints are discussed, and a summary of experiment results is given. RP ROKEY, MJ (reprint author), JET PROP LAB,MAGELLAN PROJECT,MAIL STOP 264-214,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 715 EP 723 DI 10.2514/3.26377 PG 9 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800010 ER PT J AU HILLARD, GB AF HILLARD, GB TI PLASMA CURRENT COLLECTION OF Z-93 THERMAL PAINT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note RP HILLARD, GB (reprint author), NASA,LEWIS RES CTR,SPACE ENVIRONM EFFECTS BRANCH,CLEVELAND,OH 44135, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 767 EP 769 DI 10.2514/3.26385 PG 3 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800018 ER PT J AU ZOBY, EV GUPTA, RN LEE, KP AF ZOBY, EV GUPTA, RN LEE, KP TI HYPERVELOCITY STAGNATION-POINT HEATING RATE DISCREPANCIES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 VIGYAN INC,HAMPTON,VA 23665. RP ZOBY, EV (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 773 EP 774 DI 10.2514/3.55659 PG 2 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800021 ER PT J AU THROCKMORTON, DA AF THROCKMORTON, DA TI LEESIDE SHOCK-LAYER TRANSITION AND THE SPACE-SHUTTLE ORBITER SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note ID HEAT-TRANSFER DATA RP THROCKMORTON, DA (reprint author), NASA,LANGLEY RES CTR,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1993 VL 30 IS 6 BP 774 EP 776 DI 10.2514/3.26389 PG 3 WC Engineering, Aerospace SC Engineering GA MK988 UT WOS:A1993MK98800022 ER PT J AU STARK, M AF STARK, M TI IMPACTS OF OBJECT-ORIENTED TECHNOLOGIES - 7 YEARS OF SOFTWARE ENGINEERING SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article AB This article examines the premise that object-oriented technology (OOT) is the most significant technology ever examined by the Software Engineering Laboratory (SEL). The evolution of the use of OOT in the SEL ''Experience Factory'' is described in terms of the SEL's original expectations, focusing on how successive generations of projects have used OOT. General conclusions are drawn on how the usage of the technology has evolved in this environment. C1 NASA,GODDARD SPACE FLIGHT CTR,SOFTWARE ENGN BRANCH,GREENBELT,MD 20771. NR 4 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD NOV PY 1993 VL 23 IS 2 BP 163 EP 169 DI 10.1016/0164-1212(93)90081-8 PG 7 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA ME484 UT WOS:A1993ME48400008 ER PT J AU SCHOLTZ, J CHIDAMBER, S GLASS, R GOERNER, A ROSSON, MB STARK, M VESSEY, I AF SCHOLTZ, J CHIDAMBER, S GLASS, R GOERNER, A ROSSON, MB STARK, M VESSEY, I TI OBJECT-ORIENTED PROGRAMMING - THE PROMISE AND THE REALITY SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article ID SOFTWARE AB This article summarizes a workshop organized and conducted by the authors on April 1 and 2, 1993, under the auspices of Portland State University and the Oregon Center for Advanced Technology Education. This workshop provided a uniquely comprehensive and realistic look at the state of the art and practice of object-oriented programming. Issues discussed at the workshop and summarized here include the naturalness of object-oriented technology, reuse potential, programming support and evaluation tools, and the cost of converting to an object-oriented design technology. The findings should be of interest to researchers, organizations, and individuals who are exploring and /or using the object-oriented approach to software development. The article concludes by offering some recommendations for the use of object-oriented technology. C1 PORTLAND STATE UNIV,DEPT COMP SCI,PORTLAND,OR 97207. MIT,CAMBRIDGE,MA 02139. COMP TRENDS,STATE COLL,PA. UNIV MISSOURI,KANSAS CITY,MO 64110. IBM CORP,THOMAS J WATSON RES CTR,YORKTOWN HTS,NY 10598. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. PENN STATE UNIV,UNIV PK,PA 16802. NR 8 TC 9 Z9 9 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD NOV PY 1993 VL 23 IS 2 BP 199 EP 204 DI 10.1016/0164-1212(93)90084-B PG 6 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA ME484 UT WOS:A1993ME48400011 ER PT J AU HOU, AY AF HOU, AY TI THE INFLUENCE OF TROPICAL HEATING DISPLACEMENTS ON THE EXTRATROPICAL CLIMATE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID GENERAL-CIRCULATION MODEL; BAROCLINIC INSTABILITY; PLANETARY-WAVES; VERTICAL SHEAR; EDDY FLUXES; BASIC STATE; ATMOSPHERE; FLOW; TELECONNECTIONS; DIAGNOSTICS AB The hypothesis is advanced that a latitudinal shift in the tropical convective heating pattern can significantly alter temperatures in the extratropics. Results of a simplified GCM show that the shift of a prescribed tropical heating toward the summer pole, on time scales longer than a few weeks, leads to a more intense cross-equatorial ''winter'' Hadley circulation, enhanced upper-level tropical easterlies, and a slightly stronger subtropical winter jet, accompanied by warming at the winter middle and high latitudes as a result of increased dynamical heating. The indications are that there is a robust connection between the net dynamic heating in the extratropics and the implied changes in the subtropical wind shear resulting from adjustments in the Hadley circulation associated with convective heating displacements in the tropics. The implications are that (i) the low-frequency temporal variability in the Hadley circulation may play an important role in modulating wave transport in the winter extratropics, (ii) the global climate may be sensitive to those processes that control deep cumulus convection in the tropics, and (iii) systematic temperature biases in GCMs may be reduced by improving the tropical rainfall simulation. RP HOU, AY (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. RI Hou, Arthur/D-8578-2012 NR 43 TC 24 Z9 26 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD NOV 1 PY 1993 VL 50 IS 21 BP 3553 EP 3570 DI 10.1175/1520-0469(1993)050<3553:TIOTHD>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MF553 UT WOS:A1993MF55300005 ER PT J AU POPOV, BN ZHANG, W DARCY, EC WHITE, RE AF POPOV, BN ZHANG, W DARCY, EC WHITE, RE TI IMPEDANCE SPECTROSCOPY AS A NONDESTRUCTIVE HEALTH INTERROGATION TOOL FOR LITHIUM-BCX CELLS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID THIONYL-CHLORIDE; SOCL2; ELECTRODES; FILM; ELECTROLYTES; BATTERIES; LI/SOCL2; SYSTEMS; MODEL; LI AB The objective of this investigation was to study the growth of thick passivating layers on the Li anode in Li/BCX (Li/SOCl2 + BrCl) cells which were stored for a period of 3 years. Impedance spectroscopy and equivalent circuit models were used to determine characterizing parameters for these cells. The equivalent circuit used for virgin cells includes a faradic contribution and diffusion of the electroactive species. The equivalent circuit for batteries stored 1 or 2 years includes the impedance of a metal/passive film interface, the resistance of the film, and the impedance of the passivating film/electrolyte interface. The equivalent circuit used for batteries stored for 3 years accounts for cathodic contributions in the overall impedance spectrum. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP POPOV, BN (reprint author), UNIV S CAROLINA,DEPT CHEM ENGN,COLUMBIA,SC 29208, USA. NR 42 TC 6 Z9 7 U1 1 U2 5 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD NOV PY 1993 VL 140 IS 11 BP 3097 EP 3103 DI 10.1149/1.2220992 PG 7 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA MG873 UT WOS:A1993MG87300013 ER PT J AU FLATTE, SM WANG, GY MARTIN, J AF FLATTE, SM WANG, GY MARTIN, J TI IRRADIANCE VARIANCE OF OPTICAL WAVES THROUGH ATMOSPHERIC-TURBULENCE BY NUMERICAL-SIMULATION AND COMPARISON WITH EXPERIMENT SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID RANDOM-MEDIA; INNER-SCALE; SCINTILLATION; FLUCTUATIONS; PROPAGATION; STATISTICS; SCATTERING; SPECTRUM; LIGHT; INDEX AB Irradiance variance for optical propagation through atmospheric turbulence is calculated by numerical simulation. Let l0 be the inner scale, R(f) be the Fresnel scale, and beta0(2) be the weak-fluctuation irradiance variance at zero inner scale. Then results in the strong-focusing regime just past the peak can be summarized by sigma(I)2 = 1.74 - 0.092beta0 + 0.60(l0/R(f)) for a plane wave and sigma(I)2 = 3.02 - 0.35beta0 + 5.56(l0/R(f)) for a point source. These numerical results are in excellent agreement with experimental results. C1 JET PROP LAB,PASADENA,CA 91109. RP FLATTE, SM (reprint author), UNIV CALIF SANTA CRUZ,DEPT PHYS,SANTA CRUZ,CA 95064, USA. NR 22 TC 72 Z9 76 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD NOV PY 1993 VL 10 IS 11 BP 2363 EP 2370 DI 10.1364/JOSAA.10.002363 PG 8 WC Optics SC Optics GA MD726 UT WOS:A1993MD72600012 ER PT J AU TOTH, RA AF TOTH, RA TI NU(1)-NU(2), NU(3)-NU(2), NU(1), AND NU(3) BANDS OF (H2O)-O-16 - LINE POSITIONS AND STRENGTHS SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID TRANSITION FREQUENCIES; CM-1; SPECTRUM; WATER; STATES; H2O-16; REGION AB High-resolution spectra of (H2O)-O-16 were recorded with a Fourier-transform spectrometer covering transitions in the (100)-(010), (001)-(010)), (100)-(000), and (001)-(000) bands. The measured line frequencies were used to determine high-accuracy values of rotational energy levels in the (100) and (001) vibrational states. Measurements of the line strengths were fitted to a model in which 19 transition moment parameters were determined for the B-type bands and 8 parameters for the A-type bands. The fitting technique did not consider interactions between the (020), (100), and (001) vibrational states. The experimental results provide a more accurate representation of the line positions and strengths than those available at present for these bands. RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 20 TC 96 Z9 96 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD NOV PY 1993 VL 10 IS 11 BP 2006 EP 2030 PG 25 WC Optics SC Optics GA MF959 UT WOS:A1993MF95900005 ER PT J AU HOGE, FE VODACEK, A BLOUGH, NV AF HOGE, FE VODACEK, A BLOUGH, NV TI INHERENT OPTICAL-PROPERTIES OF THE OCEAN - RETRIEVAL OF THE ABSORPTION-COEFFICIENT OF CHROMOPHORIC DISSOLVED ORGANIC-MATTER FROM FLUORESCENCE MEASUREMENTS SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Article ID YELLOW SUBSTANCE; CHLOROPHYLL-A; SPECTROSCOPY; WATER; ATTENUATION; REFLECTANCE; SEA AB The quantitative relationship between the absorption and fluorescence emission of chromophoric (colored) dissolved organic matter (CDOM) has been determined along five cruise tracks in the western North Atlantic Ocean, the Gulf of Mexico, and Monterey Bay, and includes Gulf Stream, Loop Current, slope, shelf, and coastal waters. We present a protocol for the determination of CDOM fluorescence that will allow both interlaboratory comparisons and the calibration of airborne fluorescence measurements. This protocol is based on the use of the water Raman signal as an internal radiometric standard and quinine sulfate as an external standard. This study demonstrates that when an appropriate and consistent procedure is used to standardize fluorescence measurements, the fluorescence per unit absorption exhibits surprisingly little variation for diverse waters. The maximum variability observed between all sites was 36% and within the western North Atlantic the variability was only 12%. Algorithms are presented for retrieval of the absorption coefficient of CDOM at 355 and 337 nm from shipboard or airborne measurements of the water-Raman-normalized fluorescence emission resulting from 355- and 337-nm excitation. C1 WOODS HOLE OCEANOG INST,DEPT CHEM & MARINE GEOCHEM,WOODS HOLE,MA 02543. RP HOGE, FE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. RI Blough, Neil/B-7727-2009; Vodacek, Anthony/F-1585-2011 OI Vodacek, Anthony/0000-0001-9196-0928 NR 20 TC 112 Z9 138 U1 0 U2 18 PU AMER SOC LIMNOLOGY OCEANOGRAPH PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044-8897 SN 0024-3590 J9 LIMNOL OCEANOGR JI Limnol. Oceanogr. PD NOV PY 1993 VL 38 IS 7 BP 1394 EP 1402 PG 9 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA MR975 UT WOS:A1993MR97500005 ER PT J AU MINELLO, TJ AF MINELLO, TJ TI CHRONOGRAPHIC TETHERING - A TECHNIQUE FOR MEASURING PREY SURVIVAL-TIME AND TESTING PREDATION PRESSURE IN AQUATIC HABITATS SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article ID JUVENILE BLUE CRABS; PENAEUS-AZTECUS IVES; BROWN SHRIMP; CALLINECTES-SAPIDUS; NURSERY HABITATS; FISH PREDATION; RATES; REFUGE; FOOD AB A chronographic system was developed to measure survival time of tethered prey and quantify predation pressure in aquatic habitats. The system incorporates a small digital clock with a pressure-sensitive triggering mechanism. Survival time is a continuous variable that can be analyzed with parametric statistical tests, and in comparison with presence/absence data normally obtained in tethering studies, this variable provides more information per tethered prey. The technique was tested using tethered brown shrimp Penaeus aztecus. The sensitivity of the triggering mechanism was set to ensure that shrimp escape behavior would not trigger the clock. In laboratory trials with pinfish Lagodon rhomboides as predators, triggering efficiency for predation events was measured at 65%. A field experiment was also conducted in 3 estuarine habitats located in the Galveston Bay system of Texas, USA. On unstructured sand bottom the efficiency of the triggering mechanism was similar to that measured in the laboratory. Structure in seagrass and salt marsh habitats, however, appeared to affect triggering efficiency and reduced the number of usable observations in these habitats. Despite this complication, significant differences in survival time were detected. Predation pressure appeared to be lower in the seagrass and salt marsh habitats examined compared with nonvegetated sand bottom. RP MINELLO, TJ (reprint author), NATL MARINE FISHERIES SERV, SE FISHERIES CTR, GALVESTON LAB, 4700 AVE U, GALVESTON, TX 77551 USA. NR 20 TC 45 Z9 45 U1 1 U2 7 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0171-8630 J9 MAR ECOL PROG SER JI Mar. Ecol.-Prog. Ser. PD NOV PY 1993 VL 101 IS 1-2 BP 99 EP 104 DI 10.3354/meps101099 PG 6 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA ME437 UT WOS:A1993ME43700010 ER PT J AU BARCOHEN, Y MAL, AK LIH, SS AF BARCOHEN, Y MAL, AK LIH, SS TI NDE OF COMPOSITE-MATERIALS USING ULTRASONIC OBLIQUE INSONIFICATION SO MATERIALS EVALUATION LA English DT Article DE COMPOSITE MATERIAL; FIBER-REINFORCED COMPOSITES; NONDESTRUCTIVE EVALUATION; ULTRASONIC TESTING ID LEAKY LAMB WAVES; NONDESTRUCTIVE EVALUATION; ANISOTROPIC PLATE AB The analysis of reflected ultrasonic waves induced by oblique insonification of composite materials is increasingly recognized as a powerful tool in providing information about defects and material properties. The theoretical modeling of the wave behavior for tone-burst and pulses has been very successful in accurately corroborating the experimental results. The data repeatability and accuracy make oblique insonification methods easy to standardize for practical applications. Recent theoretical and experimental results and the progress in using frequency- and time-domain data are discussed with an emphasis on the application to graphite/epoxy composites. C1 UNIV CALIF LOS ANGELES,DEPT MECH AEROSP & NUCL ENGN,LOS ANGELES,CA 90024. RP BARCOHEN, Y (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 26 TC 22 Z9 22 U1 1 U2 2 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD NOV PY 1993 VL 51 IS 11 BP 1285 EP 1296 PG 12 WC Materials Science, Characterization & Testing SC Materials Science GA MG745 UT WOS:A1993MG74500010 ER PT J AU CHOI, SR TIKARE, V AF CHOI, SR TIKARE, V TI CRACK HEALING OF ALUMINA WITH A RESIDUAL GLASSY PHASE - STRENGTH, FRACTURE-TOUGHNESS AND FATIGUE SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID SILICON-NITRIDE; OXIDATION AB The crack-healing behavior of identation cracks and large precracks in 96 wt.% alumina was studied as a function of annealing temperature in air and inert environments. Crack healing occurred at annealing temperatures of 800-degrees-C and above in both air and inert (argon) environments, indicating its cause as transport of existing material to the crack plane, and resulted in increased strength and fracture toughness. However, the resulting phase assemblage in the crack plane was susceptible to fatigue at room temperature in distilled water, as evidenced by a somewhat low fatigue parameter of N = 68. Furthermore, polished-and-annealed samples were more susceptible to fatigue at room temperature in air than as-polished samples. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHOI, SR (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 22 TC 18 Z9 18 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD NOV 1 PY 1993 VL 171 IS 1-2 BP 77 EP 83 DI 10.1016/0921-5093(93)90394-T PG 7 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA ME439 UT WOS:A1993ME43900008 ER PT J AU LAI, SHY AF LAI, SHY TI THE INFLUENCE OF SHAPE CHANGES ON STRUCTURAL DYNAMICS OF A ROUND-CORNERED THIN-WALLED BEAM WITH WARPING SO MECHANICS RESEARCH COMMUNICATIONS LA English DT Article AB The objective of this study is to investigate the influence of shape changes on the natural frequencies of a channel beam. To achieve this objective, the solutions of differential equations of motion for a beam experiencing coupled bending and torsion are derived using the Ritz approach. The functional of the corresponding system frequency equation is formulated. A set of polynomial that satisfies the fixed-free boundary condition is generated. The Ritz method leads the formulation to an eigen value problem for frequency calculations. A numerical examples is presented to validate the approach and to study the influence of shape changes on the dynamics of the beam structure. RP LAI, SHY (reprint author), N CAROLINA AGR & TECH STATE UNIV,NASA,CTR AEROSP RES,GREENSBORO,NC 27411, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0093-6413 J9 MECH RES COMMUN JI Mech. Res. Commun. PD NOV-DEC PY 1993 VL 20 IS 6 BP 487 EP 492 DI 10.1016/0093-6413(93)90008-C PG 6 WC Mechanics SC Mechanics GA MH439 UT WOS:A1993MH43900007 ER PT J AU SHEN, JY SHARPE, L TAYLOR, LW AF SHEN, JY SHARPE, L TAYLOR, LW TI A STRAIN-ENERGY CRITERION FOR RECOGNITION OF IDENTIFIED MODES OF CONTINUOUS STRUCTURAL MODELS SO MECHANICS RESEARCH COMMUNICATIONS LA English DT Article AB In structural modal analysis and modal testing, an important but difficult task is to match the identified natural frequencies and the corresponding modal deflections. This process is called the modal recognition in this paper. There were some treatments towards this problem for the lumped parameter structural models. For the distributed parameter models, however, little research has been reported on the modal recognition problem. In this paper, a strain-energy-criterion for modal recognition has been developed. As an example, a distributed parameter model for a two-beam structural system has been formulated, which is expected to simulate the dynamics of a two-arm manipulating system fixed on a shuttle. Transfer matrix method has been used to set up the dynamic equation of the system. The natural frequencies are obtained from the solution of the characteristic equation. Consequently, the mode shape functions are found out analytically. Strain energy can be viewed as a measure of the structural deformation. When performing modal analysis, we always assume that the structural system is vibrating at a particular natural frequency. The strain energy is, therefore, stored in the deflection caused by such a harmonic motion. The vibration at a particular natural frequency will not produce any strain energy in the other modal components. On the other hand, if a particular mode shape is contributed mostly by the deformation of a specific component of the global structural system, then the great percentage of the total strain energy will be stored in the deformation of that component. Based upon the calculation of the strain energy in the structural components we can find out which component is deformed most and in what motion it is deformed, thereby, the mode shape can be detected. The computer simulation demonstrated that the strain energy indicated an essentially perfect recognition of the identified natural frequencies with the corresponding mode shapes. The creation of the strain-energy criterion consummates the procedure of the distributed parameter modeling, modal identification and parameter estimation. C1 NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,HAMPTON,VA 23665. RP SHEN, JY (reprint author), N CAROLINA AGR & TECH STATE UNIV,SCH ENGN,CTR AEROSP RES,GREENSBORO,NC 27411, USA. NR 8 TC 0 Z9 0 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0093-6413 J9 MECH RES COMMUN JI Mech. Res. Commun. PD NOV-DEC PY 1993 VL 20 IS 6 BP 507 EP 518 DI 10.1016/0093-6413(93)90011-C PG 12 WC Mechanics SC Mechanics GA MH439 UT WOS:A1993MH43900010 ER PT J AU SUD, VK SRINIVASAN, R CHARLES, JB BUNGO, MW AF SUD, VK SRINIVASAN, R CHARLES, JB BUNGO, MW TI EFFECTS OF LOWER-BODY NEGATIVE-PRESSURE ON BLOOD-FLOW WITH APPLICATIONS TO THE HUMAN CARDIOVASCULAR-SYSTEM SO MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING LA English DT Article DE CARDIOVASCULAR SYSTEM; FLOW RATE; LOWER-BODY NEGATIVE PRESSURE; MODELING; SIMULATION ID ORTHOSTATIC TOLERANCE; INDIVIDUAL RESPONSE; ASSAY TECHNIQUE; LBNP AB The paper reports a theoretical investigation into the effects of lower-body negative pressure on blood flow through the human cardiovascular system. The human cardiovascular system is modelled as a closed network of arteries, arterioles, capillaries, venules and veins of different lengths and cross-sections. The pumping action is provided by the contraction of the ventricles. The model has been analysed using the finite-element method. The pertinent equations incorporating the effects of lower-body negative pressure for the pressures and flow velocities have been derived, and the quantitative results have been computed. Percentage changes in flow velocities, pressure drops and conductances under the application of lower-body negative pressure in the various segments and organs of the entire cardiovascular system are obtained. The lower-body negative pressure has no effect on the flow rates in carotid, ulnar and coronary arteries, nor on the supply of blood to the upper extremities, kidneys, spleen and liver. The major effects are found in the lower extremities. C1 KRUG INT,HOUSTON,TX 77058. NASA,JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SUD, VK (reprint author), ALL INDIA INST MED SCI,DEPT BIOPHYS,NEW DELHI 110029,INDIA. NR 35 TC 4 Z9 5 U1 1 U2 5 PU PETER PEREGRINUS LTD PI HERTS PA SOUTHGATE HOUSE STEVENAGE PO BOX 8, HERTS, ENGLAND SG1 1HQ SN 0140-0118 J9 MED BIOL ENG COMPUT JI Med. Biol. Eng. Comput. PD NOV PY 1993 VL 31 IS 6 BP 569 EP 575 DI 10.1007/BF02441803 PG 7 WC Computer Science, Interdisciplinary Applications; Engineering, Biomedical; Mathematical & Computational Biology; Medical Informatics SC Computer Science; Engineering; Mathematical & Computational Biology; Medical Informatics GA PN058 UT WOS:A1993PN05800004 PM 8145581 ER PT J AU AIKIN, BJM COURTNEY, TH AF AIKIN, BJM COURTNEY, TH TI MODELING OF PARTICLE-SIZE EVOLUTION DURING MECHANICAL MILLING SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID AMORPHIZATION; ALLOY AB The process of mechanical alloying (MA) involves the repeated deformation, welding, and fracture of powder materials during grinding in high-energy mills. During MA, the size and size distribution of the particles change as a result of the particles' different fracture and welding rates. The evolution of particle volume distributions during such a combined ''fission-fusion'' process can be described via a differential-integral equation. While analytical solutions are known for systems in which only fusion takes place, there is apparently no such solution for the fission-fusion problem. In this article, we describe a discretized form of the fission-fusion equation and apply it to modeling of particle size distributions during milling of elemental powders using previously determined fracture and welding rates appropriate to the global system of particles. Predicted particle size distributions mimic well those determined experimentally. C1 UNIV VIRGINIA,DEPT MAT SCI & ENGN,CHARLOTTESVILLE,VA 22903. MICHIGAN TECHNOL UNIV,DEPT MET & MAT ENGN,HOUGHTON,MI 49931. RP AIKIN, BJM (reprint author), CASE WESTERN RESERVE UNIV,NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 35 TC 20 Z9 20 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD NOV PY 1993 VL 24 IS 11 BP 2465 EP 2471 DI 10.1007/BF02646525 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA MF556 UT WOS:A1993MF55600010 ER PT J AU BREIT, GA WATENPAUGH, DE BALLARD, RE HARGENS, AR AF BREIT, GA WATENPAUGH, DE BALLARD, RE HARGENS, AR TI ACUTE CUTANEOUS MICROVASCULAR FLOW RESPONSES TO WHOLE-BODY TILTING IN HUMANS SO MICROVASCULAR RESEARCH LA English DT Article ID MICROCIRCULATION; MECHANISM; HEAD; FOOT RP BREIT, GA (reprint author), NASA,AMES RES CTR,DIV LIFE SCI 23911,MOFFETT FIELD,CA 94035, USA. NR 23 TC 14 Z9 15 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0026-2862 J9 MICROVASC RES JI Microvasc. Res. PD NOV PY 1993 VL 46 IS 3 BP 351 EP 358 DI 10.1006/mvre.1993.1058 PG 8 WC Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA MJ730 UT WOS:A1993MJ73000008 PM 8121318 ER PT J AU WU, KW WICKRAMASINGHE, DT AF WU, KW WICKRAMASINGHE, DT TI MAGNETIC-MOMENT DISTRIBUTION OF MAGNETIC CATACLYSMIC VARIABLES .2. EFFECTS DUE TO PERIOD DISTRIBUTION SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; STARS, EVOLUTION; STARS, MAGNETIC FIELDS; NOVAE, CATACLYSMIC VARIABLES; WHITE DWARFS ID INTERMEDIATE POLARS; EVOLUTION; BINARIES; BRAKING; STARS AB The effects of evolution and birth-rate on the distribution of magnetic cataclysmic variables into various subclasses are investigated using Monte Carlo simulations. Our simulations indicate the possibility that AM Herculis systems and intermediate polars might follow different evolutionary scenarios. C1 UNIV SYDNEY,SCH PHYS,THEORET ASTROPHYS RES CTR,SYDNEY,NSW 2006,AUSTRALIA. AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 2601,AUSTRALIA. RP WU, KW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 27 TC 11 Z9 11 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 1 PY 1993 VL 265 IS 1 BP 115 EP 125 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MC843 UT WOS:A1993MC84300015 ER PT J AU SUD, YC WALKER, GK AF SUD, YC WALKER, GK TI A RAIN EVAPORATION AND DOWNDRAFT PARAMETERIZATION TO COMPLEMENT A CUMULUS UPDRAFT SCHEME AND ITS EVALUATION USING GATE DATA SO MONTHLY WEATHER REVIEW LA English DT Article ID GENERAL-CIRCULATION MODELS; TROPICAL CLOUD CLUSTERS; LARGE-SCALE ENVIRONMENT; ARAKAWA-SCHUBERT; MOISTURE BUDGETS; BIOSPHERE MODEL; CONVECTION; ENSEMBLE; CLIMATE; ABSORPTION AB A rain evaporation and downdraft parameterization is designed to complement the cumulus convection scheme of the Goddard Laboratory for Atmospheres General Circulation Model (GLA GCM). The scheme invokes (i) a diagnostic determination of the commencement level of rain-evaporation-induced downdrafts, (ii) a method for calculating downdraft mass fluxes emanating from different levels of the atmosphere, and (iii) an explicitly prescribed overall fraction of rain evaporation within the downdraft. The parameterization was tested with the GATE [GARP (Global Atmospheric Research Program) Atlantic Tropical Experiment] phase III data in a fully prognostic mode and with the entire atmospheric and surface forcings prescribed with data. It was found that the near-surface downdraft cooling largely mitigates the observed surface sensible heating. In the absence of this cooling, the boundary layer must get rid of the surface heat flux by spurious turbulent transport, which becomes significant in simulations that ignore both the rain evaporation and downdrafts. The time mean as well as root-mean-square errors in the vertical temperature profiles are somewhat larger for simulations without downdrafts and are much larger for simulations without both downdrafts and rain evaporation. The downdrafts are found to produce a useful correction in the simulated near-surface temperature and humidity in GCM simulations, and in that way, the parameterization improves the simulation of tropospheric temperature and humidity. In a one-year comparison of GLA GCM simulations with and without downdrafts, the former produced better precipitation climatology and surface temperatures. C1 GEN SCI CORP, LAUREL, MD USA. RP SUD, YC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 913, GREENBELT, MD 20771 USA. NR 68 TC 35 Z9 35 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1993 VL 121 IS 11 BP 3019 EP 3039 DI 10.1175/1520-0493(1993)121<3019:AREADP>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD412 UT WOS:A1993MD41200005 ER PT J AU COHN, SE AF COHN, SE TI DYNAMICS OF SHORT-TERM UNIVARIATE FORECAST ERROR COVARIANCES SO MONTHLY WEATHER REVIEW LA English DT Article ID ATMOSPHERIC DATA ASSIMILATION; ADJOINT VORTICITY EQUATION; METEOROLOGICAL OBSERVATIONS; KALMAN FILTER; VARIATIONAL ASSIMILATION; ANALYSIS SYSTEM; MODEL-ERROR; PREDICTION; INTERPOLATION; CONSTRAINTS AB The covariance equation based on second-order closure for dynamics governed by a general scalar (univariate) nonlinear partial differential equation (PDE) is studied. If the governing dynamics involve n space dimensions, then the covariance equation is a PDE in 2n space dimensions. Solving this equation for n = 3 is therefore computationally infeasible. This is a hindrance to stochastic-dynamic prediction as well as to novel methods of data assimilation based on the Kalman filter. It is shown that the covariance equation can be solved approximately, to any desired accuracy, by solving instead an auxiliary system of PDEs in just n dimensions. The first of these is a dynamical equation for the variance field. Successive equations describe, to increasingly high order, the dynamics of the shape of either the covariance function or the correlation function for points separated by small distances. The second-order equation, for instance, describes the evolution of the correlation length (turbulent microscale) field. Each auxiliary equation is coupled only to the preceding, lower-order equations if the governing dynamics are hyperbolic, but is weakly coupled to the following equation in the presence of diffusion. Analysis of these equations reveals some of the qualitative behavior of their solutions. It is shown that the variance equation, through nonlinear coupling with the mean equation, describes the nonlinear effect of saturation of variance as well as the internal and external growth of variance. Further, it is shown that, in the presence of model error, the initial correlation field is transient, being damped as the influence of the model error correlation grows, while in the absence of model error the initial correlation is simply advected. There is also a critical correlation length, depending on the internal dynamics and on the model error, toward which the forecast error correlation length generally tends. C1 NYU,COURANT INST MATH SCI,NEW YORK,NY 10012. RP COHN, SE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. RI Cohn, Stephen/K-1954-2012 OI Cohn, Stephen/0000-0001-8506-9354 NR 92 TC 61 Z9 61 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1993 VL 121 IS 11 BP 3123 EP 3149 DI 10.1175/1520-0493(1993)121<3123:DOSTUF>2.0.CO;2 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD412 UT WOS:A1993MD41200010 ER PT J AU ZENG, Z GOODMAN, RM SMYTH, P AF ZENG, Z GOODMAN, RM SMYTH, P TI LEARNING FINITE-STATE MACHINES WITH SELF-CLUSTERING RECURRENT NETWORKS SO NEURAL COMPUTATION LA English DT Article ID IDENTIFICATION; COMPLEXITY; INFERENCE AB Recent work has shown that recurrent neural networks have the ability to learn finite state automata from examples. In particular, networks using second-order units have been successful at this task. In studying the performance and learning behavior of such networks we have found that the second-order network model attempts to form clusters in activation space as its internal representation of states. However, these learned states become unstable as longer and longer test input strings are presented to the network. In essence, the network ''forgets'' where the individual states are in activation space. In this paper we propose a new method to force such a network to learn stable states by introducing discretization into the network and using a pseudo-gradient learning rule to perform training. The essence of the learning rule is that in doing gradient descent, it makes use of the gradient of a sigmoid function as a heuristic hint in place of that of the hard-limiting function, while still using the discretized value in the feedback update path. The new structure uses isolated points in activation space instead of vague clusters as its internal representation of states. It is shown to have similar capabilities in learning finite state automata as the original network, but without the instability problem. The proposed pseudo-gradient learning rule may also be used as a basis for training other types of networks that have hard-limiting threshold activation functions. C1 JET PROP LAB,PASADENA,CA 91109. RP ZENG, Z (reprint author), CALTECH,DEPT ELECT ENGN,116-81,PASADENA,CA 91125, USA. NR 22 TC 55 Z9 56 U1 1 U2 2 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0899-7667 J9 NEURAL COMPUT JI Neural Comput. PD NOV PY 1993 VL 5 IS 6 BP 976 EP 990 DI 10.1162/neco.1993.5.6.976 PG 15 WC Computer Science, Artificial Intelligence SC Computer Science GA MC084 UT WOS:A1993MC08400011 ER PT J AU ZHOU, HY ZHAO, F YU, FTS CHAO, TH AF ZHOU, HY ZHAO, F YU, FTS CHAO, TH TI IMPROVED INTERCLASS MULTIOBJECT DISCRIMINATION WITH PHASE-DIFFERENCE PREWHITENING TECHNIQUE SO OPTICAL ENGINEERING LA English DT Article DE ACQUISITION TRACKING AND POINTING; WHITENING TECHNIQUES; INTERCLASS DISCRIMINATION CAPABILITIES; OPTICAL PATTERN RECOGNITION; COMPOSITE FILTERS ID CORRELATION-ENERGY FILTERS; PATTERN-RECOGNITION; ONLY FILTER AB We describe a phase-difference prewhitening technique to improve the interclass discrimination capability for the case of one filter per multiobject. Conceptually, this is an extension of the magnitude-whitening operation in Yaroslavsky's optimal filter for the case of one filter per object. By introducing this technique into the filter synthesis procedure, the discrimination ability is increased significantly compared with previous methods. Computer simulation results by means of this technique are given. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ZHOU, HY (reprint author), PENN STATE UNIV,DEPT ELECT & COMP ENGN,UNIV PK,PA 16802, USA. NR 16 TC 7 Z9 7 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD NOV PY 1993 VL 32 IS 11 BP 2720 EP 2725 DI 10.1117/12.150681 PG 6 WC Optics SC Optics GA MG773 UT WOS:A1993MG77300012 ER PT J AU ZHOU, S CAMPBELL, S WU, WS YEH, PC LIU, HK AF ZHOU, S CAMPBELL, S WU, WS YEH, PC LIU, HK TI POLARIZATION-ENCODED AND SPACE-ENCODED PARALLEL OPTICAL FUZZY-LOGIC PROCESSOR SO OPTICS LETTERS LA English DT Article AB A novel polarization- and space-encoded parallel optical fuzzy logic processor is proposed and demonstrated by use of optical fan-out elements and polarization multiplexing. Sixteen fuzzy logic operations between two inputs are achieved with a simple data-encoding scheme. Our system exhibits a high operation speed, a high signal-to-noise ratio, C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. ROCKWELL INT SCI CTR,THOUSAND OAKS,CA. RP ZHOU, S (reprint author), UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106, USA. RI Yeh, Pochi/A-2109-2010 NR 14 TC 4 Z9 6 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD NOV 1 PY 1993 VL 18 IS 21 BP 1831 EP 1833 DI 10.1364/OL.18.001831 PG 3 WC Optics SC Optics GA MC897 UT WOS:A1993MC89700021 PM 19829419 ER PT J AU ROSEN, J SEGEV, M YARIV, A BARHEN, J AF ROSEN, J SEGEV, M YARIV, A BARHEN, J TI REDUCTION IN THE RECONSTRUCTION ERROR COMPUTER-GENERATED HOLOGRAMS BY PHOTOREFRACTIVE VOLUME HOLOGRAPHY SO OPTICS LETTERS LA English DT Article AB We suggest a method for coding high-resolution computer-generated volume holograms. It involves splitting the computer-generated hologram into multiple holograms, their individual recording as volume holograms by use of the maximal resolution available from the spatial light modulator, and subsequent simultaneous reconstruction. We demonstrate the recording and the reconstruction of a computer-generated volume hologram with a space-bandwidth product much higher than the limitation imposed by the interfacing spatial light modulator. Finally, we analyze the scheduling procedure of the multiple holographic recording process in photorefractive medium in this specific application. C1 CALTECH,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ROSEN, J (reprint author), ROME LAB,OPT SIGNAL PROC BRANCH,BEDFORD,MA 01731, USA. RI Rosen, Joseph/F-1889-2012 OI Rosen, Joseph/0000-0002-9739-2180 NR 9 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD NOV 1 PY 1993 VL 18 IS 21 BP 1858 EP 1860 DI 10.1364/OL.18.001858 PG 3 WC Optics SC Optics GA MC897 UT WOS:A1993MC89700030 PM 19829428 ER PT J AU NOEVER, DA AF NOEVER, DA TI GIBBS OVERSHOOT ON A FRACTAL SO PHYSICA A LA English DT Article ID CLUSTERS AB Gibbs' overshoot refers to the persistent discrepancy between a Fourier series' approximation and actual values near a functional discontinuity. Here this phenomenon is generalized to a fractal discontinuity on a trial function. Analytic results support the conclusion that fractal dimension can parameterize the Gibbs' overshoot on an example sawtooth with a fractal distribution of discontinuous depths. Simulations confirm this finding on a fractal Brownian walk and the devil's staircase. Results indicate that the overshoot arises on a fractal not as much from any general ruggedness, but more from the fractal discontinuity directly. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES76,HUNTSVILLE,AL 35812, USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-4371 J9 PHYSICA A JI Physica A PD NOV 1 PY 1993 VL 199 IS 3-4 BP 341 EP 349 DI 10.1016/0378-4371(92)00211-J PG 9 WC Physics, Multidisciplinary SC Physics GA ME993 UT WOS:A1993ME99300001 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI DOUBLY-EXCITED SHAPE RESONANCES IN H- SO PHYSICAL REVIEW A LA English DT Article ID ELECTRIC-FIELDS; STATES; PHOTODETACHMENT; AUTOIONIZATION; HYDROGEN; ATOMS; 1PO AB The method of complex-coordinate rotation is used to investigate doubly excited shape resonances in H-. We calculate resonance parameters for the P-1(o) shape resonance lying above the n = 2 hydrogen threshold using Hylleraas-type wave functions. Comparisons are made with experimental measurements and with other theoretical calculations. In addition, we also report a calculation for P-3(o) and 1D(e) shape resonances lying above the n = 3 hydrogen threshold. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HO, YK (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. RI Ho, Yew Kam/F-7912-2012 NR 29 TC 29 Z9 29 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD NOV PY 1993 VL 48 IS 5 BP 3720 EP 3724 DI 10.1103/PhysRevA.48.3720 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA MF743 UT WOS:A1993MF74300047 ER PT J AU CHASNOV, JR AF CHASNOV, JR TI COMPUTATION OF THE LOITSIANSKI INTEGRAL IN DECAYING ISOTROPIC TURBULENCE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Letter AB The time evolution of the Loitsianski integral at high-Reynolds numbers is determined by computing an ensemble average of a large number of independent large-eddy simulations of decaying isotropic turbulence. It is found that the Loitsianski integral becomes proportional to t(gamma) at large times and that gamma almost-equal-to 0.25. The present simulations illustrate the efficient use of massively parallel computers for simulating large ensembles of turbulent flows. RP CHASNOV, JR (reprint author), NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035, USA. NR 13 TC 19 Z9 19 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD NOV PY 1993 VL 5 IS 11 BP 2579 EP 2581 DI 10.1063/1.858773 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MD642 UT WOS:A1993MD64200001 ER PT J AU GOTOH, T ROGALLO, RS HERRING, JR KRAICHNAN, RH AF GOTOH, T ROGALLO, RS HERRING, JR KRAICHNAN, RH TI LAGRANGIAN VELOCITY CORRELATIONS IN HOMOGENEOUS ISOTROPIC TURBULENCE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID NON-GAUSSIAN STATISTICS; DIRECT NUMERICAL SIMULATIONS; RENORMALIZED APPROXIMATION; TIME CORRELATIONS; PHYSICAL MODEL; INTERMITTENCY; AUTOCORRELATION; DIFFUSION AB The Lagrangian velocity autocorrelation and the time correlations for individual wave-number bands are computed by direct numerical simulation (DNS) using the passive vector method (PVM), and the accuracy of the method is studied. It is found that the PVM is accurate when K(max)/k(d) greater-than-or-equal-to 2 where K(max) is the maximum wave number carried in the simulation and k(d) is the Kolmogorov wave number. The Eulerian and Lagrangian time correlations for various wave-number bands are compared. At moderate to high wave number the Eulerian time correlation decays faster than the Lagrangian, and the effect of sweep on the former is observed. The time scale of the Eulerian correlation is found to be (kU0)-1 while that of the Lagrangian is [integral-k/0p2E(p)dp]-1/2. The Lagrangian velocity autocorrelation in a frozen turbulent field is computed using the DIA, ALHDIA, and LRA theories and is compared with DNS measurements. The Markovianized Lagrangian renormalized approximation (MLRA) is compared with the DNS, and good agreement is found for one-time quantities in decaying turbulence at low Reynolds numbers and for the Lagrangian velocity autocorrelation in stationary turbulence at moderate Reynolds number. The effect of non-Gaussianity on the Lagrangian correlation predicted by the theories is also discussed. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NAGOYA INST TECHNOL,DEPT SYST ENGN,NAGOYA,AICHI 466,JAPAN. RP GOTOH, T (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. NR 45 TC 26 Z9 27 U1 1 U2 8 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD NOV PY 1993 VL 5 IS 11 BP 2846 EP 2864 DI 10.1063/1.858748 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MD642 UT WOS:A1993MD64200029 ER PT J AU WENZEL, KP SMITH, EJ AF WENZEL, KP SMITH, EJ TI THE ULYSSES ENCOUNTER WITH JUPITER - AN INTRODUCTION SO PLANETARY AND SPACE SCIENCE LA English DT Article C1 JET PROP LAB,PASADENA,CA 91109. RP WENZEL, KP (reprint author), ESA,DEPT SPACE SCI,NOORDWIJK,NETHERLANDS. NR 3 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 797 EP 798 DI 10.1016/0032-0633(93)90086-H PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200001 ER PT J AU TSURUTANI, BT ARBALLO, JK SMITH, EJ SOUTHWOOD, D BALOGH, A AF TSURUTANI, BT ARBALLO, JK SMITH, EJ SOUTHWOOD, D BALOGH, A TI LARGE-AMPLITUDE MAGNETIC PULSES DOWNSTREAM OF THE JOVIAN BOW SHOCK - ULYSSES OBSERVATIONS SO PLANETARY AND SPACE SCIENCE LA English DT Article ID QUASI-PARALLEL SHOCK; PULSATIONS; JUPITER; FLYBY AB We report the first finding of large-amplitude magnetic pulses in the Jovian magnetosheath. The pulses are highly compressional with DELTA\B\/\B\ ranging from 0.5 to 2.0. Each pulse contains a full 360-degrees phase rotation. These solitary waves are propagating at an angle nearly orthogonal to the ambient magnetic field (theta(kB) > 83-degrees). A determination of the sense of rotation about B0 therefore cannot be made. The waves are elliptically polarized. The scale size of the pulses is approximately 8-17 proton gyroradii ii the plasma frame. We compare these Jovian pulses with similar phenomena occurring at Earth (short large-amplitude magnetic structures: SLAMS) and at comet Giacobini-Zinner. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP TSURUTANI, BT (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 8 Z9 8 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 851 EP 856 DI 10.1016/0032-0633(93)90092-G PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200007 ER PT J AU HAMMOND, CM PHILLIPS, JL BAME, SJ SMITH, EJ MACLENNAN, CG AF HAMMOND, CM PHILLIPS, JL BAME, SJ SMITH, EJ MACLENNAN, CG TI ULYSSES OBSERVATIONS OF THE PLANETARY DEPLETION LAYER AT JUPITER SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SOLAR-WIND PLASMA; SUBSOLAR MAGNETOSHEATH; MAGNETOPAUSE; ENVIRONMENT; FLYBY AB The repeated samplings of the Jovian magnetosheath during the Ulysses encounter with Jupiter provided an opportunity to probe the planetary depletion layer. Of the 10 complete crossings of the Jovian magnetopause, only three contained clear signatures of an overlying depletion layer. All of these occurred on the flanks of the magnetosphere near the dusk terminator; crossings on the dayside were ambiguous or clearly lacked a depletion layer signature. In this paper we present a detailed analysis of the observations by the Ulysses solar wind plasma and magnetometer experiments and discuss conditions favorable and unfavorable for depletion layer observation. C1 JET PROP LAB,PASADENA,CA 91109. AT&T BELL LABS,MURRAY HILL,NJ 07974. RP HAMMOND, CM (reprint author), LOS ALAMOS NATL LAB,MS D466,LOS ALAMOS,NM 87545, USA. NR 16 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 857 EP 868 DI 10.1016/0032-0633(93)90093-H PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200008 ER PT J AU KAISER, ML DESCH, MD FARRELL, WM HESS, RA MACDOWALL, RJ AF KAISER, ML DESCH, MD FARRELL, WM HESS, RA MACDOWALL, RJ TI ORDINARY AND Z-MODE EMISSIONS FROM THE JOVIAN POLAR-REGION SO PLANETARY AND SPACE SCIENCE LA English DT Article ID KILOMETRIC RADIATION; JUPITER; MAGNETOSPHERE; URANUS; RADIO AB The Ulysses Unified Radio and Plasma (URAP) experiment has detected a new component of Jupiter's radio spectrum in the frequency range from about 10 to 30 kHz. This component is emitted in the magnetoionic ordinary mode from a localized corotating source in the northern polar region. The source is centered at system III longitude 208-degrees, near the meridian containing the North magnetic dipole axis, at a distance of nearly 4R(J) from the planet and near the last closed field line. The emission frequency is somewhat above the electron plasma frequency in the source region, but well below the electron gyrofrequency. Accompanying this 0-mode emission at lower frequencies is intense Z-mode emission, which is likely to play a significant role in the generation of the 0-mode. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. RP KAISER, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI MacDowall, Robert/D-2773-2012; Farrell, William/I-4865-2013 NR 27 TC 9 Z9 9 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 977 EP 985 DI 10.1016/0032-0633(93)90102-8 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200017 ER PT J AU MACDOWALL, RJ KAISER, ML DESCH, MD FARRELL, WM HESS, RA STONE, RG AF MACDOWALL, RJ KAISER, ML DESCH, MD FARRELL, WM HESS, RA STONE, RG TI QUASI-PERIODIC JOVIAN RADIO-BURSTS - OBSERVATIONS FROM THE ULYSSES RADIO AND PLASMA-WAVE EXPERIMENT SO PLANETARY AND SPACE SCIENCE LA English DT Article ID COHERENT SYNCHROTRON RADIATION; SOLAR-WIND; PLANETARY MAGNETOSPHERES; NIGHTSIDE MAGNETOSPHERE; KILOMETRIC RADIATION; JUPITER; EMISSIONS; URANUS; VOYAGER; PROPAGATION AB The Ulysses flyby of Jupiter has permitted the detection of a variety of quasiperiodic magnetospheric phenomena. In this paper, Unified Radio and Plasma Wave Experiment (URAP) observations of quasiperiodic radio bursts are presented. There appear to be two preferred periods of short-term variability in the Jovian magnetosphere, as indicated by two classes of bursts, one with approximately 40 min periodicity, the other with approximately 15 min periodicity. The URAP radio direction determination capability provides clear evidence that the 40 min bursts originate near the southern Jovian magnetic pole, whereas the source location of the 15 min bursts remains uncertain. These bursts may be the signatures of quasiperiodic electron acceleration in the Jovian magnetosphere; however, only the 40 min bursts occur in association with observed electron bursts of similar periodicity. Both classes of bursts show some evidence of solar wind control. In particular, the onset of enhanced 40 min burst activity is well correlated with the arrival of high-velocity solar wind streams at Jupiter, thereby providing a remote monitor of solar wind conditions at Jupiter. C1 HUGHES STX CORP,LANHAM,MD 20706. RP MACDOWALL, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 695,GREENBELT,MD 20771, USA. RI MacDowall, Robert/D-2773-2012; Farrell, William/I-4865-2013 NR 41 TC 60 Z9 60 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 1059 EP 1072 DI 10.1016/0032-0633(93)90109-F PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200024 ER PT J AU KAISER, ML DESCH, MD FARRELL, WM AF KAISER, ML DESCH, MD FARRELL, WM TI CLOCK-LIKE BEHAVIOR OF JOVIAN CONTINUUM RADIATION SO PLANETARY AND SPACE SCIENCE LA English DT Article ID KILOMETRIC RADIATION; POLARIZATION; EMISSIONS; JUPITER AB Ulysses URAP observations of escaping Jovian continuum radiation show a persistent 10 h variation in amplitude which can best be explained by a clock-like model. The continuum shows a moderately strong preference to reach maximum intensity when the 0-degrees-90-degrees System III longitude sector faces the Sun. RP KAISER, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 10 TC 16 Z9 16 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 1073 EP 1077 DI 10.1016/0032-0633(93)90110-N PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200025 ER PT J AU STAUBACH, P DIVINE, N GRUN, E AF STAUBACH, P DIVINE, N GRUN, E TI TEMPERATURES OF ZODIACAL DUST SO PLANETARY AND SPACE SCIENCE LA English DT Article ID INTERPLANETARY DUST; EMISSION; LIGHT; PIONEER-10 AB Temperatures of interplanetary dust particles have been determined by calculating the thermal emission from dust concentrations according to the ''Five Populations of Interplanetary Meteoroids'' model by Divine (J. geophys. Res., in press, 1993) and matching it with the observed zodiacal thermal emission. Properties of the meteoroid populations are described by comparing them with the meteoroid mass distribution measured at 1 a.u., and with zodiacal light observations ranging from 0.3 to 4 a.u. Particle temperatures are assumed as a function of heliocentric distance and particle size. An IR emissivity of 1 has been assumed for particles bigger than one-tenth of the considered wavelength and zero for smaller particles. The intensity contributions of the five meteoroid populations are evaluated. The resulting total IR intensity is compared with the intensity of the zodiacal emission as determined either by the Infrared Astronomical Satellite IRAS or by the Zodiacal Infrared Project ZIP. At 1 a.u., temperatures have been obtained which range from 130 to 190 K and from 380 to 390 K for particles of diameters 10(-4) and 10(-6) m, respectively. Compared with Mie calculations the particle temperatures are between those of a dielectric (obsidian) and a strongly absorbing material (graphite). C1 JET PROP LAB,PASADENA,CA 91109. RP STAUBACH, P (reprint author), MAX PLANCK INST KERNPHYS,POB 103980,D-69029 HEIDELBERG,GERMANY. NR 28 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV-DEC PY 1993 VL 41 IS 11-12 BP 1099 EP 1108 DI 10.1016/0032-0633(93)90113-G PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX892 UT WOS:A1993NX89200028 ER PT J AU MIDDLETON, EM TERAMURA, AH AF MIDDLETON, EM TERAMURA, AH TI THE ROLE OF FLAVONOL GLYCOSIDES AND CAROTENOIDS IN PROTECTING SOYBEAN FROM ULTRAVIOLET-B DAMAGE SO PLANT PHYSIOLOGY LA English DT Article ID PHENYLALANINE AMMONIA-LYASE; PHOTON FLUX-DENSITY; ARABIDOPSIS-THALIANA; ELEVATIONAL GRADIENT; STOMATAL RESPONSE; BLUE-LIGHT; UV-LIGHT; RADIATION; PHOTOSYNTHESIS; PLANTS AB The increase in ultraviolet-B (UV-B; 0.290-0.320 mu m) radiation received by plants due to stratospheric ozone depletion heightens the importance of understanding UV-B tolerance. Photosynthetic tissue is believed to be protected from UV-B radiation by UV-B-absorbing compounds (e.g. flavonoids). Although synthesis of flavonoids is induced by UV-B radiation, its protective role on photosynthetic pigments has not been clearly demonstrated. This results in part from the design of UV-B experiments in which experimental UV-A irradiance has not been carefully controlled, since blue/UV-A radiation is involved in the biosynthesis of the photosynthetic pigments. The relationship of flavonoids to photosynthetic performance, photosynthetic pigments, and growth measures was examined in an experiment where UV-A control groups were included at two biologically effective daily UV-B irradiances, 14.1 and 10.7 kJ m(-2). Normal, chlorophyll-deficient, and flavonoid-deficient pigment isolines of two soybean (Glycine max) cultivars that produced different flavonol glycosides (Harosoy produced kaempferol, Clark produced quercetin and kaempferol) were examined. Plants with higher levels of total flavonoids, not specific flavonol glycosides, were more UV-B tolerant as determined by growth, pigment, and gas-exchange variables. Regression analyses indicated no direct relationship between photosynthesis and leaf levels of UV-B-absorbing compounds. UV-B radiation increased photosynthetic pigment content, along with UV-B-absorbing compounds, but only the former (especially carotenoids) was related to total biomass (r(2) = 0.61, linear) and to photosynthetic efficiency (negative, exponential relationship, r(2) = 0.82). A reduction in photosynthesis was associated primarily with a stomatal limitation rather than photosystem II damage. This study suggests that both carotenoids and flavonoids may be involved in plant UV-B photoprotection, but only carotenoids are directly linked to photoprotection of photosynthetic function. These results additionally show the importance of UV-A control in UV-B experiments conducted using artificial lamps and filters. C1 UNIV MARYLAND,DEPT BOT,COLL PK,MD 20744. RP MIDDLETON, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 44 TC 246 Z9 282 U1 4 U2 16 PU AMER SOC PLANT PHYSIOLOGISTS PI ROCKVILLE PA 15501 MONONA DRIVE, ROCKVILLE, MD 20855 SN 0032-0889 J9 PLANT PHYSIOL JI Plant Physiol. PD NOV PY 1993 VL 103 IS 3 BP 741 EP 752 PG 12 WC Plant Sciences SC Plant Sciences GA MG605 UT WOS:A1993MG60500009 ER PT J AU Darrach, M Wang, S Woolsey, JM McConkey, JW AF Darrach, M. Wang, S. Woolsey, J. M. McConkey, J. W. TI Spectroscopic diagnosis of vibrationally-hot N(2) SO PLASMA SOURCES SCIENCE & TECHNOLOGY LA English DT Article AB Electron-impact induced vuv emission measurements of the c(4)'(1)Sigma(+)(u)-X(1)Sigma(+)(g) and a(1)Pi(g)-X(1)Sigma(+)(g), systems of N(2) allow significant information about the vibrational character of an RF excited N(2) beam to be obtained, The former system provides a rather accurate direct monitor of the v = 0 population of the ground state whereas the latter allows conclusions to be drawn about the population in other states as well. The, measurements is also established. C1 [Darrach, M.; Wang, S.; Woolsey, J. M.; McConkey, J. W.] Univ Windsor, Dept Phys, Windsor, ON N9B 3P4, Canada. [Woolsey, J. M.] Univ Stirling, Stirling FK9 4LA, Scotland. RP Darrach, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. FU Natural Sciences and Engineering Research Council of Canada; Scientific Affairs Division of NATO [CRG 890801] FX The authors are pleased to acknowledge financial assistance From the Natural Sciences and Engineering Research Council of Canada and from the Scientific Affairs Division of NATO through research grant CRG 890801. They are grateful for helpful input from S Trajmar and G K James. NR 11 TC 0 Z9 0 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0963-0252 J9 PLASMA SOURCES SCI T JI Plasma Sources Sci. Technol. PD NOV PY 1993 VL 2 IS 4 BP 258 EP 260 DI 10.1088/0963-0252/2/4/005 PG 3 WC Physics, Fluids & Plasmas SC Physics GA V10QA UT WOS:000207477300005 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI IS PSR-1509-58 THE REMNANT OF SUPERNOVA AD-185 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB Thorsett has recently advanced the proposal that the counterpart of the supernova recorded by Chinese astronomers in AD 185 is the pulsar PSR 1509-58 in the supernova remnant MSH 15-52. This proposal is attractive since it was claimed to better fit the visibility constraints that plagued earlier identifications and since the spin-down age of the pulsar is 1690 years. I have examined in detail the question of the visibility of a supernova at the proposed position and find that the reported dates of visibility can be matched only if the supernova appeared substantially brighter than Venus at its peak. For the distance and extinction to the pulsar, this implies M(V)(max) was brighter than -21.4 mag, whereas the brightest known absolute magnitude of a Type II supernova is -19.65 (H-0 = 75 km s-1 Mpc-1). Thus, the high required luminosity can be used as good evidence against the identification of SN 185 with PSR 1509-58. However, if the identification is retained, then Hubble's Constant would have to have a small value and/or the supernova had to have been a type IIP event with exceptional brilliance. The earlier identification of SN 185 with MSH 14-63 by Clark and Stephenson can also be reconciled with the visibility data. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 12 TC 4 Z9 4 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD NOV PY 1993 VL 105 IS 693 BP 1238 EP 1239 DI 10.1086/133301 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MJ754 UT WOS:A1993MJ75400004 ER PT J AU HYUNG, S ALLER, LH FEIBELMAN, WA AF HYUNG, S ALLER, LH FEIBELMAN, WA TI THE SPECTRUM OF THE PLANETARY-NEBULA NGC-6567 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB Because of the similarity of its spectrum to that of NGC 6572 particularly in the UV we have made a detailed study of NGC 6567 using both the IUE for the UV region and the Hamilton Echelle at Lick Observatory for the optical region. Plasma diagnostics suggest an electron temperature of about 11,500 K and an electron density near 9000 cm-3. The chemical composition of this Population Type II, high-velocity planetary nebula is found from ionic concentrations and a theoretical model. The ''metal''/H ratio is lower than in the sun, except for C whose abundance is enhanced to about 30% over the solar value and for He which may be slightly enhanced. There is no evidence of any spectral variability. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HYUNG, S (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. NR 18 TC 22 Z9 22 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD NOV PY 1993 VL 105 IS 693 BP 1279 EP 1286 DI 10.1086/133308 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MJ754 UT WOS:A1993MJ75400011 ER PT J AU NEELY, AW JANESICK, JR AF NEELY, AW JANESICK, JR TI A CCD ANTIBLOOMING TECHNIQUE FOR USE IN PHOTOMETRY SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB A new antiblooming technique was used to collect images for a BL Lac monitoring project. The antiblooming was accomplished by clocking two of the collection phases (in a three-phase chip) back and forth during the integration of an image. Calibrations were done using VRI standard stars to insure that the technique did not affect normal photon collection and photometric data. New sources of noise were identified which must be subtracted from the processed image. In contrast, the technique reduced dark current noise, which is of benefit with a thermoelectric-cooled camera. The technique eliminated blooming across the stars of interest, while preserving photon-collection efficiency. It also reduced the total noise of the exposures. C1 JET PROP LAB,PASADENA,CA 91109. RP NEELY, AW (reprint author), NF OBSERV LTD,ROUTE 15,BOX 760,SAN LORENZO,NM 88041, USA. NR 8 TC 6 Z9 6 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD NOV PY 1993 VL 105 IS 693 BP 1330 EP 1333 DI 10.1086/133314 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MJ754 UT WOS:A1993MJ75400017 ER PT J AU RAMPINO, MR SELF, S AF RAMPINO, MR SELF, S TI CLIMATE VOLCANISM FEEDBACK AND THE TOBA ERUPTION OF SIMILAR-TO 74,000 YEARS AGO SO QUATERNARY RESEARCH LA English DT Article ID VOSTOK ICE-CORE; LONG-TERM VARIATIONS; NORTH-ATLANTIC; GLACIER VARIATIONS; SHEET GROWTH; 75 KA; RECORD; ATMOSPHERE; TEPHRA; MODEL C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,DEPT GEOL & GEOPHYS,HONOLULU,HI 96822. RP RAMPINO, MR (reprint author), NYU,DEPT APPL SCI,EARTH SYST GRP,NEW YORK,NY 10003, USA. NR 94 TC 89 Z9 91 U1 14 U2 48 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0033-5894 J9 QUATERNARY RES JI Quat. Res. PD NOV PY 1993 VL 40 IS 3 BP 269 EP 280 DI 10.1006/qres.1993.1081 PG 12 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA MJ015 UT WOS:A1993MJ01500001 ER PT J AU DAVIS, JL ELGERED, G NIELL, AE KUEHN, CE AF DAVIS, JL ELGERED, G NIELL, AE KUEHN, CE TI GROUND-BASED MEASUREMENT OF GRADIENTS IN THE WET RADIO REFRACTIVITY OF AIR SO RADIO SCIENCE LA English DT Article ID MILLIMETER-WAVE-PROPAGATION; INTERFEROMETRY; GEODESY; MODEL; FREQUENCIES; LENGTH; WATER AB We have used a ground-based microwave radiometer, known as a water vapor radiometer, to investigate the local spatial and temporal variation of the wet propagation delay for a site on the west coast of Sweden. The data were obtained from a wide range of azimuths and from elevation angles greater than 23.6-degrees (air mass 2.5). Visual inspection of the data suggested a simple ''cosine azimuth'' variation, implying that a first-order gradient model was required. This model was adequate for short time spans up to approximately 15 min, but significant temporal variations in the gradient suggested to us that we include gradient rate terms. The resulting six-parameter model has proven adequate (rms delay residual approximately 1 mm) for up to 30 min of data. Assuming a simple exponential profile for the wet refractivity gradient, the estimated gradient parameters imply average surface wet-refractivity horizontal gradients of order of 0.1-1 N km-1. These gradients are larger, by 1-2 orders of magnitude, than gradients determined by others by averaging over long (approximately 100-km) distances. This result implies that for applications that are sensitive to local gradients, such as wet propagation-delay models for radio-interferometric geodetic studies, the use of meteorological data from widely spread stations may be inadequate. The gradient model presented here is inadequate for times longer than about 30 min. even if no gradients are present, because of the complicated stochastic like temporal behavior of the wet atmosphere. When gradients are present, they can change magnitude by approximately 50% over 10-15 min. Nevertheless, our ability to fit the radiometer data implies that on timescales <30 min and for elevation angles >23.6-degrees, the local structure of the wet atmosphere can be described with a simple model. (The model is not limited to this range of elevation angles in principle.) The estimated gradient and gradient rate vectors have preferred directions, which indicates a prevailing structure in the three-dimensional temperature and humidity fields, possibly related to systematic behavior in large-scale weather systems and/or the local air-land-sea interaction at this site. C1 CHALMERS UNIV TECHNOL,ONSALA SPACE OBSERV,S-43900 ONSALA,SWEDEN. NASA,GODDARD SPACE FLIGHT CTR,INTERFEROMETR INC,GREENBELT,MD 20771. HAYSTACK OBSERV,NEROC,WESTFORD,MA 01886. RP DAVIS, JL (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,MAIL STOP 42,CAMBRIDGE,MA 02138, USA. RI Davis, James/D-8766-2013; Elgered, Gunnar/B-7052-2016 OI Davis, James/0000-0003-3057-477X; Elgered, Gunnar/0000-0001-5711-0073 NR 30 TC 86 Z9 90 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 1993 VL 28 IS 6 BP 1003 EP 1018 DI 10.1029/93RS01917 PG 16 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA ML354 UT WOS:A1993ML35400006 ER PT J AU DURDEN, SL KLEIN, JD ZEBKER, HA AF DURDEN, SL KLEIN, JD ZEBKER, HA TI MEASUREMENT AND SIMULATION OF SIGNAL FLUCTUATIONS CAUSED BY PROPAGATION THROUGH TREES SO RADIO SCIENCE LA English DT Article ID L-BAND; RADAR AB We present measured magnitude and phase fluctuations of UHF, L band, and C band signals that were transmitted from the ground through a forest canopy to an airborne radar. We find that the measured fluctuations are similar to those calculated by a simple Monte Carlo simulation. Both observed and calculated RMS fluctuations are typically several decibels in magnitude and tens of degrees in phase at all three frequencies. RP DURDEN, SL (reprint author), JET PROP LAB,MS 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 2 Z9 2 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 1993 VL 28 IS 6 BP 1049 EP 1051 DI 10.1029/93RS02122 PG 3 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA ML354 UT WOS:A1993ML35400010 ER PT J AU NGHIEM, SV YUEH, SH KWOK, R NGUYEN, DT AF NGHIEM, SV YUEH, SH KWOK, R NGUYEN, DT TI POLARIMETRIC REMOTE-SENSING OF GEOPHYSICAL MEDIUM STRUCTURES SO RADIO SCIENCE LA English DT Article AB Polarimetric remote sensing of structures in geophysical media is studied in this paper based on their symmetry properties. Orientations of spheroidal scatterers described by spherical, uniform, planophile, plagiothile, erectophile, and extremophile distributions are considered to derive their polarimetric backscattering characteristics. These distributions can be identified from the observed scattering coefficients by comparison with theoretical symmetry calculations. A new parameter is defined to study scattering structures in geophysical media. Experimental observations from polarimetric data acquired by the Jet Propulsion Laboratory airborne synthetic aperture radar over forests, sea ice, and sea surface are presented to illustrate the use of symmetry properties. For forests, the coniferous forest in Mount Shasta area and mixed forests near Presque Isle show evidence of the centrical symmetry at C band. In sea ice from the Beaufort Sea, multiyear sea ice has a cross-polarized ratio e close to e0, calculated from symmetry, due to the randomness in the scattering structure. For first-year sea ice, e is much smaller than e0 as a result of preferential alignment of the columnar structure of the ice. From polarimetric data of a sea surface in the Bering sea, it is observed that e and e0 are increasing with incident angle and e is greater than e0 at L band because of the directional feature of sea surface waves. Use of symmetry properties of geophysical media for polarimetric radar calibration is also suggested. RP NGHIEM, SV (reprint author), JET PROP LAB,MAIL STOP 300-235,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 13 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 1993 VL 28 IS 6 BP 1111 EP 1130 DI 10.1029/93RS01376 PG 20 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA ML354 UT WOS:A1993ML35400016 ER PT J AU NICHOLS, WE CUENCA, RH SCHMUGGE, TJ WANG, JR AF NICHOLS, WE CUENCA, RH SCHMUGGE, TJ WANG, JR TI PUSHBROOM MICROWAVE RADIOMETER RESULTS FROM HAPEX-MOBILHY SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID TIME DOMAIN REFLECTOMETRY; SURFACE SOIL-MOISTURE AB The NASA C-130 remote sensing aircraft was in Toulouse, France from 25 May through 4 July 1986, for participation in the HAPEX-MOBILHY program. Spectral and radiometric data were collected by C-130-borne sensors in the visible, infrared, and microwave wavelengths. These data provided information on the spatial and temporal variations Of surface parameters such as vegetation indices, surface temperature, and surface soil moisture. The Pushbroom Microwave Radiometer (PBMR) was used to collect passive microwave brightness temperature data. This four-beam sensor operates at the 21 -cm wavelength, providing cross-track coverage approximately 1.2 times the aircraft altitude, Observed brightness temperatures for the period were high, ranging from above 240 K to about 290 K. Brightness temperature images appeared to correspond well to spatial and temporal soil moisture variation. Previous research has demonstrated that an approximately linear relationship exists between the surface emissivity and surface soil moisture. For these data, however, regression analysis did not indicate a strong linear relationship (r2 = 0. 32 and r2 = 0. 42, respectively) because of the limited range of soil moisture conditions encountered and the small number of ground measurements. When results from wetter soil conditions encountered in another experiment were included, the regression improved dramatically. Based on similar research with the PBMR and an understanding of the ground data collection program, this result was examined to produce recommendations for improvements to future passive microwave research and data collection programs. Examples Of surface soil moisture maps generated with PBMR data are presented which appear to be representative of the actual soil moisture conditions. C1 OREGON STATE UNIV, CORVALLIS, OR 97331 USA. USDA ARS, BELTSVILLE AGR RES CTR, BELTSVILLE, MD 20705 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP NICHOLS, WE (reprint author), PACIFIC NW LAB, DEPT GEOSCI, POB 999,MSIN K6-77, RICHLAND, WA 99352 USA. NR 16 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD NOV PY 1993 VL 46 IS 2 BP 119 EP 128 DI 10.1016/0034-4257(93)90089-G PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA MD665 UT WOS:A1993MD66500002 ER PT J AU PUSEY, ML AF PUSEY, ML TI A COMPUTER-CONTROLLED MICROSCOPY SYSTEM FOR FOLLOWING PROTEIN CRYSTAL-FACE GROWTH-RATES SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID LYSOZYME AB A computer-controlled microscopy system for following the face growth of multiple small (approximately 10 to 50 mum) crystals during one experimental run is described. The major system components are a controlling PC with a digital oscilloscope board, PC-controlled translation stages for X, Y, and Z axes of motion, a video microscopy system, and a circuit to trigger digitization of preselected video lines. Crystal locations in the growth chamber are stored in an array, and sequentially accessed during each measurement cycle. Operator-selected horizontal video scan lines are digitized and these data are used to calculate the distance between parallel faces of the crystals. The system was assembled from readily available components, and can be easily modified for other microscopy-based tracking and measuring functions. RP PUSEY, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS ES 76,HUNTSVILLE,AL 35812, USA. NR 4 TC 16 Z9 16 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 1993 VL 64 IS 11 BP 3121 EP 3125 DI 10.1063/1.1144318 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MG624 UT WOS:A1993MG62400014 ER PT J AU FRALICK, GC FORNEY, LJ AF FRALICK, GC FORNEY, LJ TI FREQUENCY-RESPONSE OF A SUPPORTED THERMOCOUPLE WIRE - EFFECTS OF AXIAL CONDUCTION SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Theoretical expressions are derived for the steady-state frequency response of a supported thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a supported one material wire and a two material wire with unequal material properties across the junction. For the case of a one material supported wire, an exact solution is derived which compares favorably with an approximate expression that only matches temperatures at the support junction. Moreover, for the case of a two material supported wire, an analytical expression is derived that closely correlates numerical results. C1 GEORGIA INST TECHNOL,SCH CHEM ENGN,ATLANTA,GA 30332. RP FRALICK, GC (reprint author), NASA,LEWIS RES CTR,RES SENSOR TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 1993 VL 64 IS 11 BP 3236 EP 3244 DI 10.1063/1.1144334 PG 9 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MG624 UT WOS:A1993MG62400030 ER PT J AU GAFFNEY, N LESTER, D TELESCO, C AF GAFFNEY, N LESTER, D TELESCO, C TI KINEMATICS OF THE STARS IN THE STARBURST NUCLEUS OF M82 - JUST ANOTHER NORMAL STELLAR BULGE SO REVISTA MEXICANA DE ASTRONOMIA Y ASTROFISICA LA English DT Article; Proceedings Paper CT 4th Texas Mexico Conference on Astrophysics CY MAR 01-02, 1993 CL AUSTIN, TX DE GALAXIES, INDIVIDUAL (M82); GALAXIES, KINEMATICS AND DYNAMICS; GALAXIES, NUCLEI; GALAXIES, STARBURST; GALAXIES, STELLAR CONTENT; TECHNIQUES, SPECTROSCOPIC ID GIANT STARS AB Using the sharp edge of the (2-0)(CO)-C-12 stellar absorption bandhead, we have measured the velocity dispersion from the central 5'' of the starburst galaxy M82. Using both minimum least squares fitting and maximum entropy deconvolution we have derived a velocity dispersion for the central r < 7.5 pc of 100 km/s. The mass-to-light ratio this implies is more than 10 times higher than in the surrounding regions of the galaxy, and is comparable to the same spatial region in our own galaxy. This implies that the starlight from the near-infrared-bright nucleus is dominated by an older population of giants and not by supergiants formed in the starburst. C1 MCDONALD OBSERV,AUSTIN,TX 78712. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP GAFFNEY, N (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU UNIV NACIONAL AUTONOMA MEXICO, INST DE ASTRONOMIA PI MEXICO CITY PA APDO POSTAL 70-264, MEXICO CITY 04510, MEXICO SN 0185-1101 J9 REV MEX ASTRON ASTR JI Rev. Mex. Astron. Astrofis. PD NOV PY 1993 VL 27 SI SI BP 137 EP 140 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MQ642 UT WOS:A1993MQ64200027 ER PT J AU SANKARAN, SN HERRMANN, RK CLARK, RK OUTLAW, RA AF SANKARAN, SN HERRMANN, RK CLARK, RK OUTLAW, RA TI HYDROGEN TRANSPORT BEHAVIOR OF TIMETAL-21S ALLOY SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID TEMPERATURE C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP SANKARAN, SN (reprint author), ANALYT SERV & MAT INC,107 RES DR,HAMPTON,VA 23666, USA. NR 12 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD NOV 1 PY 1993 VL 29 IS 9 BP 1247 EP 1252 DI 10.1016/0956-716X(93)90117-B PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA LX096 UT WOS:A1993LX09600018 ER PT J AU ELLENBERGER, R LING, R BUSCHER, D UHDELACOVARA, J SHULER, R AF ELLENBERGER, R LING, R BUSCHER, D UHDELACOVARA, J SHULER, R TI AUTOMATIC-GENERATION OF REAL-TIME ADA SIMULATIONS FOR SPACE STATION FREEDOM SO SIMULATION LA English DT Article DE SPACE STATION FREEDOM; INTEGRATION, TEST AND VERIFICATION ENVIRONMENT; REAL-TIME; AUTOMATIC CODE GENERATOR; ADA AB This paper describes a method to automatically generate real-time simulations in Ada for use in Space Station Freedom (SSF) Integration, Test, and Verification Environment (ITVE). The interface requirements of the ITVE could not be fully met by commercial-off-the-shelf (COTS) tools; therefore, modifications to the COTS tool were necessary and a tool was developed in-house to meet the required interface. This process is illustrated by generating a Space Station Guidance, Navigation and Control (GN&C) simulation from an engineering block diagram. Moreover, this method can be readily applied to other environments with different types of schedulers or real-time databases. RP ELLENBERGER, R (reprint author), NASA,JOHNSON SPACE CTR,DIV FLIGHT DATE SYST,EK74,HOUSTON,TX 77058, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU SIMULATION COUNCILS INC PI SAN DIEGO PA PO BOX 17900, SAN DIEGO, CA 92117 SN 0037-5497 J9 SIMULATION JI Simulation PD NOV PY 1993 VL 61 IS 5 BP 337 EP 345 DI 10.1177/003754979306100509 PG 9 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering SC Computer Science GA MX106 UT WOS:A1993MX10600005 ER PT J AU SCHIER, M WAY, J HOLT, B AF SCHIER, M WAY, J HOLT, B TI APPLICATIONS OF THE EOS SAR TO MONITORING GLOBAL CHANGE SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB The Earth Observing System (EOS) Synthetic Aperture Radar (SAR) is a critical component of the overall EOS mission and NASA's Mission to Planet Earth. The EOS SAR is a multi-frequency, multi-polarization radar capable of the global monitoring of key quantitative measurements of geophysical and biophysical parameters. The role of the SAR in global monitoring will be discussed, emphasizing the geophysical product variables which will be generated and used in global hydrologic, biogeochemical, and energy cycle models. RP SCHIER, M (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD NOV PY 1993 VL 13 IS 6 BP 569 EP 575 PG 7 WC Engineering, Aerospace SC Engineering GA MK259 UT WOS:A1993MK25900005 ER PT J AU CRUISE, JF MILLER, RL AF CRUISE, JF MILLER, RL TI HYDROLOGIC MODELING WITH REMOTELY-SENSED DATABASES SO WATER RESOURCES BULLETIN LA English DT Article DE MODELING; REMOTE SENSING; IMAGE PROCESSING; GLEAMS MODEL ID GLEAMS AB An integrated remotely sensed database was used as the basis for a hydrologic and sediment transport modeling effort for an agricultural area of western Puerto Rico. Classified spectral images of airborne radiance data provided ground cover information and were used in conjunction with topographic and soils data to guide model construction and provide input to the water balance and sediment yield simulations. Runoff and sediment discharge from hydrologically homogeneous regions were routed through the drainage network and combined at the basin outlet. The model was used to simulate four years of observed sediment discharge from the basin. Relative contributions to the total sediment yield of forested and agricultural areas were determined and compared. RP CRUISE, JF (reprint author), NASA,JOHN C STENNIS SPACE CTR,SCI & TECHNOL LAB,BAY ST LOUIS,MS 39529, USA. NR 13 TC 7 Z9 7 U1 0 U2 0 PU AMER WATER RESOURCES ASSOC PI HERNDON PA 950 HERNDON PARKWAY SUITE 300, HERNDON, VA 20170-5531 SN 0043-1370 J9 WATER RESOUR BULL JI Water Resour. Bull. PD NOV-DEC PY 1993 VL 29 IS 6 BP 997 EP 1002 PG 6 WC Engineering, Civil; Geosciences, Multidisciplinary; Water Resources SC Engineering; Geology; Water Resources GA MW603 UT WOS:A1993MW60300016 ER PT J AU WANG, S TRAJMAR, S KHAKOO, MA AF WANG, S TRAJMAR, S KHAKOO, MA TI LOW-ENERGY ELECTRON-IMPACT SPECTROSCOPY OF C-60 BUCKMINSTERFULLERENE MOLECULE SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID EXCITED-STATE PROPERTIES; ABSORPTION-SPECTRA; TRIPLET-STATE; PHOTOPHYSICAL PROPERTIES; INVERSE PHOTOEMISSION; TRANSIENT ABSORPTION; CROSS-SECTIONS; FULLERENES C60; THIN-FILMS; SOLID C60 AB The methods of electron-impact spectroscopy were utilized to obtain the first low-energy, high-resolution energy-loss spectra of gas phase pure C-60 and C-60 + C-70 mixture buckminsterfullerene molecules over a range of scattering angles. The impact energies and scattering angles ranged from 8 to 100 eV and 0 degrees to 90 degrees, respectively. Broad spectral features in the energy-loss spectra have been assigned to overlapping electronic transitions based on the identification of features in the photoabsorption spectrum of C-60 molecules in n-hexane solution by Leach et al. Pure vibrational excitation features were also observed. The relative scattering intensities of these spectral features represent the corresponding relative cross sections. C1 CALIF STATE UNIV FULLERTON,DEPT PHYS,FULLERTON,CA 92633. RP WANG, S (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 53 TC 0 Z9 0 U1 1 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD OCT 28 PY 1993 VL 26 IS 20 BP 3639 EP 3651 DI 10.1088/0953-4075/26/20/022 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA MF205 UT WOS:A1993MF20500022 ER PT J AU CHENG, BL SCHRAMM, DN TRURAN, JW AF CHENG, BL SCHRAMM, DN TRURAN, JW TI INTERACTION RATES AT HIGH MAGNETIC-FIELD STRENGTHS AND HIGH DEGENERACY SO PHYSICS LETTERS B LA English DT Article AB In this paper, we have derived the the effects of strong magnetic fields B on nucleon and particle reaction rates of astrophysical significance. We have explored the sensitivity to the presence of arbitrary degeneracy and polarization. The possible astrophysical applications-of our results are discussed. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,NASA,CTR ASTROPHYS,BATAVIA,IL 60510. RP CHENG, BL (reprint author), UNIV ILLINOIS,DEPT ASTRON,1002 W GREEN ST,URBANA,IL 61801, USA. NR 28 TC 27 Z9 27 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD OCT 28 PY 1993 VL 316 IS 4 BP 521 EP 527 DI 10.1016/0370-2693(93)91038-O PG 7 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA MD457 UT WOS:A1993MD45700011 ER PT J AU HICKEY, GS SHARMA, PK AF HICKEY, GS SHARMA, PK TI SELECTIVE MOLECULAR SORPTION BY HIGH-SURFACE-AREA CATALYST SUPPORTS SO THERMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT 21st North-American-Thermal-Analysis-Society Conference CY SEP 13-16, 1992 CL ATLANTA, GA SP N AMER THERMAL ANAL SOC AB Three high surface area catalyst supports were studied for the selective molecular sorption of organic compounds. The first was a carbon molecular sieve with a well-defined pore structure. The other two were silica gel and high surface area alumina. Both have a random pore structure. A mixture of phenol and acetic acid was used to qualitatively characterize the intermolecular force potentials and pore selectivity. Thermal gravimetric analysis and mass spectroscopy were used to characterize the desorption kinetics and differential scanning calorimetry was used to study the heats of desorption. The analyses illustrate an approach for characterizing adsorption-desorption processes in catalysts and high surface area materials. RP HICKEY, GS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD OCT 26 PY 1993 VL 226 BP 333 EP 342 DI 10.1016/0040-6031(93)80235-3 PG 10 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA ML659 UT WOS:A1993ML65900037 ER PT J AU CONNERNEY, JEP AF CONNERNEY, JEP TI MAGNETIC-FIELDS OF THE OUTER PLANETS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SATURNIAN KILOMETRIC RADIATION; ZONAL HARMONIC MODEL; HIGH-FREQUENCY LIMIT; GEOMAGNETIC-FIELD; MAGNETOMETER OBSERVATIONS; EFFECTIVE TEMPERATURE; ROTATION PERIOD; ENERGY-BALANCE; URANUS; NEPTUNE AB It is difficult to imagine a group of planetary dynamos more diverse than those visited by the Pioneer and Voyager spacecraft. The magnetic field of Jupiter is large in magnitude and has a dipole axis within 10-degrees of its rotation axis, comfortably consistent with the paleomagnetic history of the geodynamo. Saturn's remarkable (zonal harmonic) magnetic field has an axis of symmetry that is indistinguishable from its rotation axis (<< 1-degrees angular separation); it is also highly antisymmetric with respect to the equator plane, According to one hypothesis, the spin symmetry may arise from the differential rotation of an electrically conducting and stably stratified layer above the dynamo. The magnetic fields of Uranus and Neptune are very much alike, and equally unlike those of the other known magnetized planets. These two planets are characterized by a large dipole tilts (59-degrees and 47-degrees, respectively) and quadrupole moments (Schmidt-normalized quadrupole/dipole ratio almost-equal-to 1.0). These properties may be characteristic of dynamo generation in the relatively poorly conducting ''ice'' interiors of Uranus and Neptune. Characteristics of these planetary magnetic fields are illustrated using contour maps of the field on the planet's surface and discussed in the context of planetary interiors and dynamo generation. RP CONNERNEY, JEP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013; OI connerney, jack/0000-0001-7478-6462 NR 105 TC 156 Z9 156 U1 0 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18659 EP 18679 DI 10.1029/93JE00980 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600001 ER PT J AU BOUSKA, V BELL, JF AF BOUSKA, V BELL, JF TI ASSUMPTIONS ABOUT THE PRESENCE OF NATURAL GLASSES ON MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CHEMICAL-COMPOSITION; PARENT BODY; IMPACT; METEORITES; VOLCANISM; MINERALS; PRODUCTS; SURFACE; CRATER; SOIL AB Natural glasses occur not only on Earth but also in lunar rocks and in some meteorites. On geological grounds, natural glasses could be expected on the surface of Mars and their presence would have important implications for the weathering and alteration of the near-surface layer. Ultramafic and mafic magmatism rich in iron and some volatiles appears to have been important on Mars as has been impact cratering, volcanism, and possibly hydrothermal alteration. Available data indicate that we can presume the past or present existence of volcanic basaltic glasses, impact glasses formed by thermal fusion of meteorite-impact targets, and diaplectic (mainly maskelynite) glasses. Conditions appear unsuitable for the formation of tektites on the Martian surface, and the production of measurable amounts of fulgurite or combustion glass seems improbable. Prospects for the remote and in situ identification of Martian glasses and their subsequent weathering products are discussed and include orbital reflectance and thermal emission spectroscopic measurements and Mossbauer spectroscopy from a surface lander. C1 NATL RES COUNCIL NASA AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP BOUSKA, V (reprint author), CHARLES UNIV,FAC SCI,DEPT GEOCHEM MINERAL & CRYSTALLOG,ALBERTOV 6,CS-12843 PRAGUE 2,CZECHOSLOVAKIA. NR 84 TC 13 Z9 13 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18719 EP 18725 DI 10.1029/93JE01959 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600005 ER PT J AU KOSTIUK, T MCGRATH, M BERGSTRALH, J AF KOSTIUK, T MCGRATH, M BERGSTRALH, J TI VARIABLE PHENOMENA IN JOVIAN PLANETARY SYSTEMS - INTRODUCTION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material C1 NASA HEADQUARTERS,DIV SOLAR SYST EXPLORAT,WASHINGTON,DC 20546. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP KOSTIUK, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 693,GREENBELT,MD 20771, USA. RI Kostiuk, Theodor/A-3077-2014 NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18727 EP 18728 DI 10.1029/93JE02466 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600006 ER PT J AU OSHEROVICH, VA BENSON, RF FAINBERG, J STONE, RG MACDOWALL, RJ AF OSHEROVICH, VA BENSON, RF FAINBERG, J STONE, RG MACDOWALL, RJ TI SOUNDER STIMULATED D(N) RESONANCES IN JUPITER IO PLASMA TORUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID FREE ELECTROMAGNETIC-FIELDS; CYLINDRICAL OSCILLATIONS; PHYSICAL NATURE; IONOSPHERE; RADIO; MAGNETOSPHERE; EMISSIONS; VOYAGER-1; WAVES AB On February 8, 1992, the Ulysses spacecraft passed through Jupiter's Io plasma torus, where rich spectra of narrow-band resonances were stimulated by the relaxation sounder of the Ulysses unified radio and plasma wave (URAP) instrument. Since the gyrofrequency f(g) is comparable to the plasma frequency f(p) in the Io torus, it was predicted that the general classification of stimulated ionospheric D(n) resonances, developed for 1 less-than-or-equal-to f(p)/f(g) less-than-or-equal-to 8 in the Earth's topside ionosphere, should apply in the Io torus as well as the Earth's magnetosphere (Osherovich, 1989). The URAP plasmagrams (sounder spectra) in the portions of the Io torus satisfying these plasma conditions are dominated by the D(n) resonances for frequencies below f(p). On most of these plasmagrams the f(p) resonance is also present, but it is seldom the dominant resonance. Neither upper hybrid nor f(p) resonances have been found on these plasmagrams. The identification of D(n) resonances has allowed both the electron density and the magnetic field amplitude to be calculated. The derived densities on the outbound pass agree well with a Voyager model of Bagenal (1992). The derived magnetic field values are close to the Goddard Space Flight Center O6 magnetic field model. C1 HUGHES STX CORP,LANHAM,MD. RP OSHEROVICH, VA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI MacDowall, Robert/D-2773-2012 NR 30 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18751 EP 18756 DI 10.1029/93JE01481 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600009 ER PT J AU KAISER, ML AF KAISER, ML TI TIME-VARIABLE MAGNETOSPHERIC RADIO EMISSIONS FROM JUPITER SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SOLAR-WIND CONTROL; PLASMA-WAVE OBSERVATIONS; RADIATION; PLANETS AB Jupiter is the source of a large number of independent nonthermal radio sources, all of which vary with time. The known causes of the variations include planetary rotation modulation, modulation by Io and/or its torus, and influence by the solar wind which can reach surprisingly deep into the Jovian magnetosphere. However, a significant number of radio variations, both short-term and long-term, are not currently explained by any known mechanism. RP KAISER, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 28 TC 24 Z9 24 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18757 EP 18765 DI 10.1029/93JE01279 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600010 ER PT J AU REINER, MJ FAINBERG, J STONE, RG AF REINER, MJ FAINBERG, J STONE, RG TI SOURCE CHARACTERISTICS OF JOVIAN HECTOMETRIC RADIO EMISSIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SOURCE LOCATION; RADIATION; VOYAGER; JUPITER AB Direct confirmation that low-frequency Jovian hectometric (HOM) radio emissions centered near 0-degrees central meridian longitude consist of distinct, oppositely polarized northern and southern beams has been achieved using data from the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft during the Ulysses-Jupiter encounter in early February 1992. Distinct northern and southern beams were observed in the frequency range from approximately 300 kHz to 1 MHz for at least eight Jovian rotations during the Ulysses inbound pass at distances from 100 to 40 R(J). The radiation from the two magnetic hemispheres was measured from different Jovigraphic longitudes and magnetic (or centrifugal) latitudes. Observed temporal variations in the radio intensities, with time scales on the order of 30 min, may result either from longitudinal variations of the HOM sources or from longitudinal density variations in the lo plasma torus. Using the URAP direction-finding capabilities and assuming a tilted dipole planetary magnetic field model, the three-dimensional HOM source locations, the L shell through these source locations, and the beam opening angles were independently deduced. The HOM sources were found to originate at approximately 3 R(J) and on low L shells (L is similar to 4 to 6), with beam opening angles ranging from 10-degrees to 50-degrees. C1 HUGHES STX CORP,LANHAM,MD. RP REINER, MJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 28 TC 29 Z9 29 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18767 EP 18777 DI 10.1029/93JE01779 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600011 ER PT J AU PRANGE, R ZARKA, P BALLESTER, GE LIVENGOOD, TA DENIS, L CARR, T REYES, F BAME, SJ MOOS, HW AF PRANGE, R ZARKA, P BALLESTER, GE LIVENGOOD, TA DENIS, L CARR, T REYES, F BAME, SJ MOOS, HW TI CORRELATED VARIATIONS OF UV AND RADIO EMISSIONS DURING AN OUTSTANDING JOVIAN AURORAL EVENT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID KILOMETRIC RADIATION; SOLAR-WIND; GEOMAGNETIC-ACTIVITY; SOURCE LOCATION; ENERGY-SOURCE; MU-M; JUPITER; GENERATION; MODEL; IO AB An exceptional Jovian aurora was detected in the FUV on December 21, 1990, by means of Vilspa and Goddard Space Flight Center (GFSC) International Ultraviolet Explorer (IUE) observations. This event included intensification by a factor of three between December 20 and 21, leading to the brightest aurora identified in the IUE data analyzed, and, in the north, to a shift of the emission peak towards larger longitudes (these variations are even more dramatic once the actual source brightness distribution is retrieved from the raw data). The Jovian radio emission simultaneously recorded at decameter wavelengths in Nancay also exhibits significant changes, from a weak and short-duration emission on December 20 to a very intense one, lasting several hours, on December 21. Confirmation of this intense radio event is also found in the observations at the University of Florida on December 21. The emissions are identified as right-handed Io-independent ''A'' (or ''non Io-A'') components from the northern hemisphere. The radio source region deduced from the Nancay observations lies, for both days, close to the UV peak emission, exhibiting in particular a similar shift of the source region toward larger longitudes from one day to the next. A significant broadening of the radio source was also observed and it is shown that on both days, the extent of the radio source closely followed the longitude range for which the UV brightness exceeds a given threshold (approximately 3 kW m-1). The correlated variations, both in intensity and longitude, strongly suggest that a common cause triggered the variation of the UV and radio emissions during this exceptional event. On one hand, the variation of the UV aurora could possibly be interpreted according to the Prange and Elkhamsi (1991) model of diffuse multicomponent auroral precipitation (electron and ion): it would arise from an increase in the precipitation rate of ions together with an inward shift of their precipitation locus from L almost-equal-to 10 to L almost-equal-to 6. On the other hand, the analysis of Ulysses observations in the upstream solar wind suggests that a significant disturbance in the solar wind, involving the generation of an interplanetary shock and the presence of a CME have interacted with the Jovian magnetosphere at about the time of the auroral event. Both arguments suggest that we may have observed for the first time a magnetic storm-type interaction in an outer planet magnetosphere, affecting simultaneously several auroral processes. Conversely, the observed relationship between the level of UV auroral activity and the detection of decameter emission (DAM), if it were a typical feature, might argue in favour of a more direct and permanent association between the auroral processes leading to UV and radio aurorae. possibly related to ''discrete-arc''-like activity and electron precipitation. C1 STN RADIOASTRON NANCAY,RADIOASTRON DECAMETR GRP,F-18330 NEUVY BARANGEON,FRANCE. JOHNS HOPKINS UNIV,CTR ASTROPHYS SCI,BALTIMORE,MD 21218. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. OBSERV PARIS,ARPEGES,F-92195 MEUDON,FRANCE. INST ASTROPHYS,F-75014 PARIS,FRANCE. UNIV OXFORD,DEPT EARTH SCI,OXFORD,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV FLORIDA,DEPT ASTRON,GAINESVILLE,FL 32611. RP PRANGE, R (reprint author), UNIV PARIS 11,INST ASTROPHYS SPATIALE,F-91405 ORSAY,FRANCE. RI Livengood, Timothy/C-8512-2012 NR 55 TC 37 Z9 37 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18779 EP 18791 DI 10.1029/93JE01802 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600012 ER PT J AU LIVENGOOD, TA KOSTIUK, T ESPENAK, F GOLDSTEIN, JJ AF LIVENGOOD, TA KOSTIUK, T ESPENAK, F GOLDSTEIN, JJ TI TEMPERATURE AND ABUNDANCES IN THE JOVIAN AURORAL STRATOSPHERE .1. ETHANE AS A PROBE OF THE MILLIBAR REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID JUPITER; SPECTROMETRY; ENCOUNTER; EMISSION; BAND AB We report infrared heterodyne spectroscopy (lambda/DELTAlambda is similar to 10(6)) of C2H6 emission at 11.9 mum from the northern Jovian auroral region, in observations conducted over December 2-7, 1989. Accurately measured line shapes provide information on C2H6 abundance as well as temperature and permit retrieval of the source pressure region. Enhanced emission was observed in the longitude range approximately 150-degrees-180-degrees at approximately 60-degrees north latitude, approximately corresponding to the CH4 7.8-mum hot spot and the region of brightest UV aurora. Significant brightness variations were observed in the hot spot emissions on a time scale of approximately 20 hours. Analysis of the brightest hot spot spectra indicates C2H6 mole fractions of approximately (6.3-6.8) X 10(-6) at temperatures of approximately 182-184 K at 1 mbar, compared to mole fractions of (3.8 +/- 1.4) x 10(-6) averaged over spectra outside the hot spot at a temperature of approximately 172 K at the same pressure. Fixing the mole fraction to the lower limit retrieved in the quiescent (non-hot spot) region allows the temperature at 1 mbar to be as high as approximately 200 K within the hot spot. These results provide upper limits to the temperature increase near the source of the C2H6 thermal infrared emission. Combined with results from similar measurements of ethylene emission probing the approximately 10-mubar region (Kostiuk et al., this issue), altitude information on the thermal structure of the Jovian auroral stratosphere can be obtained for the first time. C1 NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560. UNIV HAWAII,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. RP LIVENGOOD, TA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,MAIL STOP 693,GREENBELT,MD 20771, USA. RI Livengood, Timothy/C-8512-2012; Kostiuk, Theodor/A-3077-2014 NR 24 TC 29 Z9 29 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18813 EP 18822 DI 10.1029/93JE01043 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600015 ER PT J AU KOSTIUK, T ROMANI, P ESPENAK, F LIVENGOOD, TA GOLDSTEIN, JJ AF KOSTIUK, T ROMANI, P ESPENAK, F LIVENGOOD, TA GOLDSTEIN, JJ TI TEMPERATURE AND ABUNDANCES IN THE JOVIAN AURORAL STRATOSPHERE .2. ETHYLENE AS A PROBE OF THE MICROBAR REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HETERODYNE SPECTROSCOPY; MU-M; JUPITER; H-3+; EMISSION; ETHANE; BAND; SPECTROMETRY; ENCOUNTER; LINE AB Individual emission lines of ethylene (C2H4) near 10.5 mum were measured from the equatorial and north polar regions of Jupiter. Observations were made at a spectral resolution of 0.00083 cm-1 using infrared heterodyne spectroscopy at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The line shape information possible with this resolving power permitted the retrieval of quiescent ethylene abundances and the investigation of abundance and thermal structure variability in the polar auroral region. A rough distribution of the north polar emission as a function of longitude was obtained with an instantaneous field of view (full width at half maximum) of approximately 1 arc sec on the planet. The greatest C2H4 emission was observed near the nominal north polar methane hot spot (60-degrees-N, 180-degrees longitude, System III, 1965). It was found to be confined to <10-degrees longitude on the planet. Using a Voyager-derived thermal profile, retrieved ethylene mole fractions for equatorial and north polar quiescent (non-hot spot) regions were consistent with results from existing photochemical models. At the hot spot an 18-fold increase in abundance was required near the 10-mubar level to reproduce the data. Alternatively varying the stratospheric thermal profile, a 67-137 K increase in temperature was required at the approximately 10-mubar level to satisfy the observed emission, if the C2H4 mole fraction is fixed to the quiescent value. These results provide the first direct probe of the upper stratosphere of Jupiter and give upper limits to the temperature increase near the source of the north polar thermal infrared aurora. Combined with results from similar measurements of auroral ethane emission (Livengood et al., this issue) probing the 1-mbar region, altitude information on the thermal structure can be obtained for the first time. The ethylene line emission region extends to the few microbar pressure level and may overlap the region where the H-2 ultraviolet aurora is formed; thus it can be used as a probe of the coupling between the ultraviolet and thermal infrared phenomena. C1 NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560. UNIV HAWAII,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. RP KOSTIUK, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 693,GREENBELT,MD 20771, USA. RI Livengood, Timothy/C-8512-2012; Romani, Paul/D-2729-2012; Kostiuk, Theodor/A-3077-2014 NR 29 TC 65 Z9 65 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 1993 VL 98 IS E10 BP 18823 EP 18830 DI 10.1029/93JE01332 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA ME266 UT WOS:A1993ME26600016 ER PT J AU CARSEY, FD GARWOOD, RW AF CARSEY, FD GARWOOD, RW TI IDENTIFICATION OF MODELED OCEAN PLUMES IN GREENLAND GYRE ERS-1 SAR DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA ICE; WATER; CIRCULATION; LAYER AB Oceanic convective plumes modeled with a thermobaric large-eddy simulation and driven by conditions similar to those of the Greenland Sea are compared to observations from ERS-1 Synthetic Aperture Radar (SAR) data from the Greenland Sea for the winter of 1992. In both form and size the two representations are seen to compare favorably. The plume-filled area of the SAR image occupies a region about 20 km by 90 km at the ice edge of the open water in ''Nordbukta'', the large seasonal ice retreat, in the ''Odden' ice protuberance in the southern Greenland gyre. In the SAR data the plumes appear to be ice covered while the convective-return areas are open. C1 USN,POSTGRAD SCH,MONTEREY,CA 93943. RP CARSEY, FD (reprint author), JET PROP LAB,JPL MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 12 Z9 12 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2207 EP 2210 DI 10.1029/93GL01954 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200014 ER PT J AU KOSTER, RD DEVALPINE, DP JOUZEL, J AF KOSTER, RD DEVALPINE, DP JOUZEL, J TI CONTINENTAL WATER RECYCLING AND (H2O)-O-18 CONCENTRATIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GENERAL-CIRCULATION MODEL; AMAZON BASIN; PRECIPITATION; SIMULATIONS; CYCLE; HDO AB Using a GCM fitted with tracer diagnostics, we examine how continental moisture recycling affects the stable water isotope content of precipitation, focusing on its contribution to the ''noise'' in the well-established relationship between temperature and deltaO-18. On a global basis, for temperatures between -30-degrees and 15-degrees-C, continental recycling explains more than a third of the variability in annual deltaO-18 that is not explained by temperature. Recycling appears almost as important as temperature in defining deltaO-18 distributions during northern hemisphere summer. C1 CENS,MODELISAT CLIMAT & ENVIRONNEMENT LAB,F-91191 GIF SUR YVETTE,FRANCE. CNRS,GLACIOL & GEOPHYS ENVIRONNEMENT LAB,F-38042 GRENOBLE,FRANCE. YALE UNIV,NEW HAVEN,CT 06520. RP KOSTER, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 974,GREENBELT,MD 20771, USA. RI Koster, Randal/F-5881-2012 OI Koster, Randal/0000-0001-6418-6383 NR 20 TC 36 Z9 38 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2215 EP 2218 DI 10.1029/93GL01781 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200016 ER PT J AU FARRELL, WM MACDOWALL, RJ DESCH, MD KAISER, ML STONE, RG KELLOGG, PJ LIN, N CORNILLEAUWEHRLIN, N CANU, P BAME, SJ PHILLIPS, JL AF FARRELL, WM MACDOWALL, RJ DESCH, MD KAISER, ML STONE, RG KELLOGG, PJ LIN, N CORNILLEAUWEHRLIN, N CANU, P BAME, SJ PHILLIPS, JL TI ULYSSES OBSERVATIONS OF AURORAL HISS AT HIGH JOVIAN LATITUDES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPACELAB-2 ELECTRON-BEAM; WHISTLER-MODE RADIATION; POLAR MAGNETOSPHERE; RADIO-EMISSION; JUPITER; INJECTION; WAVES; CUSP AB During the Ulysses flyby of Jupiter, a whistler-mode emission was periodically detected by the Unified Radio and Plasma wave (URAP) experiment during intervals when the spacecraft extended to high magnetic latitudes. The signal was detected between the local electron plasma frequency and lower hybrid resonance and appears as a funnel-shaped structure on frequency-versus-time spectrograms; these characteristics are very reminiscent of whistler-mode auroral hiss observed at high latitudes at Earth. Ray tracing of the emission occurrences suggests the emission source is on magnetic field lines extending out to at least 65 R(J). This location associates the emission with the boundary between open and closed field lines - not the Io torus. The emission radiates about 10(7) W of power. Consequently, the auroral input power derived from the solar wind to drive the emission is believed to be 10(10-12) W (or about 1% of the energy associated with lo torus electrical processes). C1 CTR RECH PHYS ENVIRONNEMENT TERR & PLANETAIRE,F-92131 ISSY MOULINEAUX,FRANCE. UNIV MINNESOTA,SCH ASTRON & ASTROPHYS,MINNEAPOLIS,MN 55455. LOS ALAMOS NATL LAB,SPACE PLASMA PHYS GRP,LOS ALAMOS,NM 87545. RP FARRELL, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI MacDowall, Robert/D-2773-2012; Farrell, William/I-4865-2013 NR 23 TC 11 Z9 11 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2259 EP 2262 DI 10.1029/93GL01120 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200027 ER PT J AU MEWALDT, RA CUMMINGS, AC CUMMINGS, JR STONE, EC KLECKER, B HOVESTADT, D SCHOLER, M MASON, GM MAZUR, JE HAMILTON, DC VONROSENVINGE, TT BLAKE, JB AF MEWALDT, RA CUMMINGS, AC CUMMINGS, JR STONE, EC KLECKER, B HOVESTADT, D SCHOLER, M MASON, GM MAZUR, JE HAMILTON, DC VONROSENVINGE, TT BLAKE, JB TI THE RETURN OF THE ANOMALOUS COSMIC-RAYS TO 1-AU IN 1992 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODULATION; COMPONENT; SPECTRA; DRIFT AB New observations of low energy (approximately 1 to 200 MeV/nuc) cosmic rays measured by three newly launched experiments on SAMPEX during 1992 and 1993 show the strong presence of anomalous, cosmic ray (ACR) nitrogen and oxygen, well before the approaching solar minimum. When compared with ACR temporal variations over the past two solar cycles we find that the 1992-1993 fluxes are approximately 5 to 10 times their level at corresponding neutron monitor counting rates-in 1969-1970 and 1985. C1 MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. AEROSP CORP,EL SEGUNDO,CA 90009. UNIV MARYLAND,COLL PK,MD 20742. RP MEWALDT, RA (reprint author), CALTECH,220-47,PASADENA,CA 91125, USA. NR 24 TC 41 Z9 41 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2263 EP 2266 DI 10.1029/93GL02493 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200028 ER PT J AU SCHATTEN, KH PESNELL, WD AF SCHATTEN, KH PESNELL, WD TI AN EARLY SOLAR DYNAMO PREDICTION - CYCLE-23-SIMILAR-TO-CYCLE-22 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CYCLE AB In this paper, we briefly review the ''dynamo'' and ''geomagnetic precursor'' methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the magnification of preexisting magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, through the development of the ''Solar Dynamo Amplitude' (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. Using the present value of the SODA index, we estimate that die next cycle's smoothed peak activity will be about 210 +/- 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 170 +/- 25. This suggests that solar cycle #23 will be large, comparable to cycle #22. The estimated peak is expected to occur near 1999.7 +/- 1 year. Since the current approach is novel (using data prior to solar minimum), these estimates may improve when the upcoming solar minimum is reached. RP SCHATTEN, KH (reprint author), NASA, GODDARD SPACE FLIGHT CTR, PLANETARY ATMOSPHERES BRANCH, CODE 914, GREENBELT, MD 20771 USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 19 TC 62 Z9 62 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2275 EP 2278 DI 10.1029/93GL02431 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200031 ER PT J AU GOLDBERG, RA KOPP, E WITT, G SWARTZ, WE AF GOLDBERG, RA KOPP, E WITT, G SWARTZ, WE TI AN OVERVIEW OF NLC-91 - A ROCKET RADAR STUDY OF THE POLAR SUMMER MESOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; CHARGED AEROSOLS; MESOPAUSE; ECHOES; CLOUDS AB In late July and early August of 1991, a major suborbital scientific campaign (NLC-91) involving scientists from eight countries was conducted at ESRANGE, Kiruna, Sweden and at Heiss Island, Russia. The purpose of the program was to investigate the chemical, dynamical, and electrodynamical properties of the polar summer mesosphere. Thirty one rocket flights were coordinated with two coherent radar facilities, EISCAT and CUPRI, and with other ground-based observatories and facilities. This permitted direct comparison between the in situ measurements and those obtained by remote sensing of the mesosphere via continuous ground-based monitoring. The primary objectives of the campaign were to study noctilucent clouds (NLCs) and polar mesospheric summer echoes (PMSEs), including their possible relationship to local aerosols and/or small scale turbulence. This overview describes the scientific program, discusses the geophysical conditions during launch activities, and reviews some of the preliminary results. More detailed results can be found in the papers which follow. C1 UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. UNIV STOCKHOLM,ARRHENIUS LAB,S-10691 STOCKHOLM,SWEDEN. CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853. RP GOLDBERG, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 690,GREENBELT,MD 20771, USA. NR 18 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 22 PY 1993 VL 20 IS 20 BP 2283 EP 2286 DI 10.1029/93GL01704 PG 4 WC Geosciences, Multidisciplinary SC Geology GA ME862 UT WOS:A1993ME86200034 ER PT J AU SAGAN, C THOMPSON, WR CARLSON, R GURNETT, D HORD, C AF SAGAN, C THOMPSON, WR CARLSON, R GURNETT, D HORD, C TI A SEARCH FOR LIFE ON EARTH FROM THE GALILEO SPACECRAFT SO NATURE LA English DT Article ID SPECTROMETER EXPERIMENT AB In its December 1990 fly-by of Earth, the Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; together, these are strongly suggestive of life on Earth. Moreover, the presence of narrow-band, pulsed, amplitude-modulated radio transmission seems uniquely attributable to intelligence. These observations constitute a control experiment for the search for extraterrestrial life by modern interplanetary spacecraft. C1 JET PROP LAB,ATMOSPHER & COMETARY SCI SECT,PASADENA,CA 91109. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. RP SAGAN, C (reprint author), CORNELL UNIV,PLANETARY STUDIES LAB,ITHACA,NY 14853, USA. NR 34 TC 148 Z9 148 U1 2 U2 31 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 21 PY 1993 VL 365 IS 6448 BP 715 EP 721 DI 10.1038/365715a0 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MC812 UT WOS:A1993MC81200051 PM 11536539 ER PT J AU BERTSCH, DL DAME, TM FICHTEL, CE HUNTER, SD SREEKUMAR, P STACY, JG THADDEUS, P AF BERTSCH, DL DAME, TM FICHTEL, CE HUNTER, SD SREEKUMAR, P STACY, JG THADDEUS, P TI DIFFUSE GAMMA-RAY EMISSION IN THE GALACTIC PLANE FROM COSMIC-RAY, MATTER, AND PHOTON INTERACTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; DIFFUSE RADIATION; GALAXY, STRUCTURE; GAMMA RAYS, OBSERVATIONS ID INTERSTELLAR RADIATION-FIELD; MOLECULAR CLOUD COMPLEXES; LARGE-SCALE DISTRIBUTION; SOUTHERN MILKY-WAY; CO SURVEY; SOLAR CIRCLE; NEUTRAL HYDROGEN; CARBON-MONOXIDE; ATOMIC-HYDROGEN; ROTATION CURVE AB On the basis of the spatial distribution, intensity, and energy spectrum, the diffuse Galactic high-energy gamma radiation is believed to be the result of cosmic-rav interactions with matter, and to a lesser extent photons. This paper describes a model calculation of diffuse gamma-ray emission based on these interactions. Recent radio observations of the main interstellar components of matter on a scale of 0.5-degrees are used for the entire region within 10-degrees of the Galactic plane. A three-dimensional spatial model of the Galaxy is used to compute the emission from each volume element based on the matter, cosmic ray, and photon densities using well know interaction processes. Provisions are incorporated to account for the near-far ambiguity in determining the distance of matter in the inner Galaxy that results from Galactic rotation velocity-distance relationship. Cosmic-rav densities are modeled from the matter distribution using dynamical balance arguments, and they are expressed as a coupling scale length. This length, together with the normalization factor used to convert the observed CO line intensity to the molecular hydrogen density, are the only two adjustable parameters in the model. This approach provides a framework for calculating the observed intensity without invoking symmetries in longitude which can dilute spatial differences related to interesting spiral arm features, and it provides for a wide range of assumptions regarding the cosmic-ray distribution to be readily tested. The calculations are compared with existing data, and the values of the parameters are given. It is expected that new results from the EGRET instrument, when used with this model, will contribute to a better understanding of the cosmic ray distribution and the relation between CO and atomic hydrogen. Both of these issues are significant for studies of the dynamics and structure of the Galaxy. C1 UNIV NEW HAMPSHIRE,DURHAM,NH 03824. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV SPACE RES ASSOC,COLUMBIA,MD. RP BERTSCH, DL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Hunter, Stanley/D-2942-2012 NR 87 TC 171 Z9 172 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP 587 EP 600 DI 10.1086/173261 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA826 UT WOS:A1993MA82600017 ER PT J AU THEJAPPA, G LENGYELFREY, D STONE, RG GOLDSTEIN, ML AF THEJAPPA, G LENGYELFREY, D STONE, RG GOLDSTEIN, ML TI EVALUATION OF EMISSION MECHANISMS AT OMEGA-PE USING ULYSSES OBSERVATIONS OF TYPE-III BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERPLANETARY MEDIUM; RADIATION MECHANISMS, MISCELLANEOUS; SOLAR WIND; SUN, RADIO RADIATION ID SOLAR RADIO-BURSTS; LANGMUIR-WAVES; INTERPLANETARY SPACE; ELECTRON-BEAM; COLLAPSE; PLASMA; PROPAGATION; SCATTERING; TURBULENCE; RADIATION AB We present the first observational tests of existing theories for the generation of type III radio bursts emitting at the fundamental plasma frequency, omega(pe). This study is based on local radio emission and in situ wave phenomena associated with four interplanetary type III radio bursts observed by the unified radio and plasma wave experiment on the Ulysses spacecraft. Intense Langmuir wave peaks with energy densities and rapid time variations indicative of Langmuir solitons are observed for some events. Low-frequency waves below 500 Hz are not observed. For each event, brightness temperatures derived from radio observations are compared with those predicted by various mechanisms for the conversion of Langmuir waves to electromagnetic radiation. The theories tested here are: (1) scattering of Langmuir waves by thermal ions; (2) wave-wave interactions, i.e., merging and decay processes involving Langmuir and low-frequency waves, (3) strong turbulence phenomena involving Langmuir solitons; and (4) direct coupling between Langmuir and electromagnetic waves due to density gradients. The mechanism of scattering on thermal ions may be ruled out as a major source of electromagnetic radiation since it yields brightness temperatures well below observed type III values. Wave-wave interactions yield brightness temperatures four to six orders of magnitude greater than observed values. The strong turbulence mechanism and the direct coupling mechanism predict brightness temperatures less than two orders of magnitude too large. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP THEJAPPA, G (reprint author), UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742, USA. RI Goldstein, Melvyn/B-1724-2008 NR 45 TC 41 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP 831 EP 844 DI 10.1086/173281 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA826 UT WOS:A1993MA82600037 ER PT J AU ASCHWANDEN, MJ BENZ, AO DENNIS, BR GAIZAUSKAS, V AF ASCHWANDEN, MJ BENZ, AO DENNIS, BR GAIZAUSKAS, V TI QUASI-PERIODIC PARTICLE INJECTION INTO CORONAL LOOPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, FLARES; SUN, PARTICLE EMISSION; SUN, RADIO RADIATION; SUN, X-RAYS, GAMMA-RAYS ID FLARE ENERGY-RELEASE; SOLAR RADIO-BURSTS; X-RAY-EMISSION; 1980 JUNE 7; MILLISECOND SPIKES; IMPULSIVE PHASE; MAGNETIC-FIELDS; PULSATIONS; STARS; FRAGMENTATION AB We present observations of the flare of 1989 June 22, 1445 UT (in active region NOAA 5555), obtained with the Hard X-Ray Burst Spectrometer (HXRBS) on SMM at energies > 52 keV, and with the broad-band radio spectrometer PHOENIX at ETH/Zurich in the frequency range of 100-2800 MHz. The radio emission is dominated by a less than or similar to 100% polarized decimetric continuum at 400-1400 MHz, peaking at 750 MHz. The decimetric radio flux is highly correlated with the 50-150 keV hard X-ray flux but is delayed by 3.5-5.4 s with respect to the hard X-rays. The HXR emission shows an excess of greater than or similar to 10 fast (less than or similar to 100 ms) spikes (according to Poisson statistics). The radio emission exhibits weak fine structure, consisting of almost-equal-to 45 quasi-periodic pulses with a mean period of 1.6 s. The frequency-time drift pattern of this fine structure is found to be consistent with segments of inverted-U type bursts, suggesting quasi-periodic injection of electron beams into a loop system. The loop system has an average height of 68,000 km and expands with a velocity of 200 km s-1 due to flare heating. Chromospheric evaporation enhances the electron density near the footpoints. The type III-exciting electrons have a mean velocity of v/c = 0.30 +/- 0.10 (22 keV) and propagate along inverted-U burst trajectories with a mean duration of 2.5 s. For those electrons which reach the mirror point near the opposite footpoint of the loop system, we calculate (from the density and loop length) a low energy cutoff of greater-than-or-equal-to 8 keV due to collisional deflection, yielding a propagation velocity of v/c = 0.18 and a propagation delay of 5.1 +/- 1.0 s, which agrees well with the observed delay of 5.16 s between the cross-correlated HXR and radio flux. The greater-than-or-equal-to 8 keV electrons provide free energy for a loss cone instability near the secondary footpoint, which is observed as decimetric continuum polarized in the same sense of circular polarization as the type III bursts. The constraints from the Halpha flare position and the magnetic potential field extrapolation indicate that the loss cone emission is produced in the diverging field region above the umbra of the leading sunspot, which has a photospheric field strength of - 1600 G. This flare allows us to deconvolve quasi-periodic particle injection and subsequently triggered coherent radio emission from trapped particles in flare-associated loops. It demonstrates that quasi-periodic modes of particle acceleration, particle dynamics in mirror loops, and the resulting plasma instabilities can be efficiently diagnosed from correlated hard X-ray and radio signatures. C1 NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,OTTAWA K1A 0R6,ONTARIO,CANADA. SWISS FED INST TECHNOL,INST ASTRON,CH-8092 ZURICH,SWITZERLAND. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP ASCHWANDEN, MJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 682,GREENBELT,MD 20771, USA. RI Dennis, Brian/C-9511-2012 NR 61 TC 31 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP 857 EP 874 DI 10.1086/173283 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA826 UT WOS:A1993MA82600039 ER PT J AU CRENSHAW, DM BOGGESS, A WU, CC AF CRENSHAW, DM BOGGESS, A WU, CC TI FAINT OBJECT SPECTROGRAPH SPECTRA OF THE UV EMISSION-LINES IN NGC-5548 - DETECTION OF STRONG NARROW COMPONENTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-5548); GALAXIES, SEYFERT ID ACTIVE GALACTIC NUCLEI; SEYFERT-1 GALAXIES; NGC 5548; REGION; ULTRAVIOLET; GAS; MARKARIAN-3; VARIABILITY; CONTINUUM AB Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Lyalpha, C IV lambda1549, and C III] lambda1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV lambda1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II lambda2798 is very weak or absent. C1 COMP SCI CORP,SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,GODDARD HIGH RESOLUT SPECTROGRAPH INVEST DEFINIT TEAM,GREENBELT,MD 20771. RP CRENSHAW, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INT ULTRAVIOLET EXPLORER OBSERV,GREENBELT,MD 20771, USA. NR 23 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP L67 EP L70 DI 10.1086/187072 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA827 UT WOS:A1993MA82700006 ER PT J AU LIN, YC BERTSCH, DL DINGUS, BL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF LIN, YC BERTSCH, DL DINGUS, BL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI EGRET LIMITS ON HIGH-ENERGY GAMMA-RAY EMISSION FROM X-RAY-SELECTED AND LOW-ENERGY GAMMA-RAY-SELECTED SEYFERT-GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, SEYFERT; GAMMA-RAYS, OBSERVATIONS ID ACTIVE GALACTIC NUCLEI; NGC-4151; RADIATION; TELESCOPE; ASTRONOMY AB A sample of 22 Seyfert galaxies, 11 type 1 and two type 2 galaxies selected according to their X-ray fluxes in the AGN survey catalogs of EXOSAT and Ginga, two additional type 1 galaxies for which detections in low-energy gamma rays have been reported in the past, plus six more type 1 galaxies and one unclassified Seyfert that have been studied by the OSSE collaboration, have been examined for high-energy gamma ray emission in observations by the EGRET telescope on the Compton Observatory. No high-energy gamma-ray emission has been detected from any of them. The 2 sigma upper limits of the gamma-ray fluxes above 100 MeV for these 22 Seyfert galaxies are given here. The significance of these negative results is discussed. Implications of the EGRET result for NGC 4151 are discussed in more detail. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. COMP SCI CORP,GRO SCI SUPPORT CTR,ASTRON PROGRAMS,GREENBELT,MD 20771. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP LIN, YC (reprint author), STANFORD UNIV,W W HANSEN EXPTL PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 43 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP L53 EP L56 DI 10.1086/187069 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA827 UT WOS:A1993MA82700003 ER PT J AU SCHOMBERT, JM BARSONY, M HANLON, PC AF SCHOMBERT, JM BARSONY, M HANLON, PC TI LOW-MASS STAR-FORMATION IN COOLING FLOW GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COOLING FLOWS; GALAXIES, PHOTOMETRY ID ELLIPTICAL GALAXIES; STANDARD STARS; H-I; CLUSTERS; PHOTOMETRY; SAMPLE; MATTER; VIRGO AB Observations are presented based on optical and near-IR imaging to support the idea that isolated and cluster cooling flow galaxies are enriched in low-mass stars, the result of recent, truncated IMF star formation from accreting gas. Galaxies with low accretion rates (M < 5 M. yr-1) have normal optical colors and gradients, but red V - K colors signaling an IMF enhanced in low-mass main-sequence stars. Cluster cooling flow ellipticals (M > 50 M. yr-1) selected to have blue optical colors indicative of recent star formation also show redder V-K colors with respect to expected values for a weak starburst. The strength of the starburst in the U - V, V - K diagram indicates an efficiency which places only 5% of the accreting matter into an IMF similar to that found in the Galactic disk and the remaining mass is again sited in low-mass stars. C1 CALTECH,JET PROPULS LAB,CTR INFRARED PROC & ANAL,MS100-22,PASADENA,CA 91125. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. RP SCHOMBERT, JM (reprint author), KITT PEAK NATL OBSERV,TUCSON,AZ 85726, USA. NR 32 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1993 VL 416 IS 2 BP L61 EP L65 DI 10.1086/187071 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA827 UT WOS:A1993MA82700005 ER PT J AU HERBER, A THOMASON, LW RADIONOV, VF LEITERER, U AF HERBER, A THOMASON, LW RADIONOV, VF LEITERER, U TI COMPARISON OF TRENDS IN THE TROPOSPHERIC AND STRATOSPHERIC AEROSOL OPTICAL DEPTHS IN THE ANTARCTIC SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PINATUBO AEROSOLS; ERUPTION AB Temporal variations of the aerosol optical depth of the Antarctic troposphere and stratosphere are considered on the basis of long-term Sun photometer and actinometer measurements which have been made at Mirny and Georg Forster stations since 1956 and 1988, respectively. This data is supplemented by measurements of the stratospheric aerosol optical depth by the satellite-borne stratospheric aerosol measurement II instrument. These observations indicate that under undisturbed conditions, the stratospheric aerosol optical depth represents approximately 25% of the total atmospheric aerosol optical depth. The aerosol optical depth in the Antarctic is most notably affected by volcanic eruptions, such as El Chichon in 1982 and Mount Pinatubo and Cerro Hudson in 1991, and by the occurrence of polar stratospheric clouds during Antarctic winter and spring. Apart from these episodic events, no long-term trend an the aerosol optical depth can he discerned from the nearly 40-year record. C1 DWD,LINDENBERG METEOROL OBSERV,D-15864 LINDENBERG,GERMANY. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. ARTIC & ANTARTIC RES INST,ST PETERSBURG 199266,RUSSIA. RP HERBER, A (reprint author), ALFRED WEGENER INST POLAR & MARINE RES,RES DEPT,POSTFACH 600149,D-14401 POTSDAM,GERMANY. OI Thomason, Larry/0000-0002-1902-0840 NR 31 TC 29 Z9 31 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18441 EP 18447 DI 10.1029/93JD01666 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200012 ER PT J AU ROOD, RB DOUGLASS, AR KAYE, JA CONSIDINE, DB AF ROOD, RB DOUGLASS, AR KAYE, JA CONSIDINE, DB TI CHARACTERISTICS OF WINTERTIME AND AUTUMN NITRIC-ACID CHEMISTRY AS DEFINED BY LIMB INFRARED MONITOR OF THE STRATOSPHERE (LIMS) DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HETEROGENEOUS CHEMISTRY; PLANETARY-WAVES; POLAR VORTEX; MODEL; OZONE; TRANSPORT; NIMBUS-7; N2O5; HNO3; VARIABILITY AB Earlier two-dimensional (2-D) and three-dimensional (3 -D) model experiments have shown that the Limb Infrared Monitor of the Stratosphere (LIMS) nitric acid data do not behave as expected from conventional gas phase chemical reactions. As contrasted to two-dimensional (2-D) model results, the 3-D model suggests that the discrepancies are at middle latitudes outside of the polar vortex, rather than at polar latitudes. Using only the data record, the characteristics of the nitric acid behavior are further examined. The data inside the Aleutian anticyclone are examined during the January wave 1 warming. The anticyclone provides a large isolated region of air that moves from about 40-degrees-N to 60-degrees-N during the warming. Ozone remains approximately constant during this transit, while nitric acid increases more than 1 parts per billion by volume (ppbv). Both ozone and water vapor fields develop a wave 1 structure during the warming, as expected. Nitric acid, which is also expected to develop a wave 1 signal, develops a prominent wave 2 structure. This structure is observed between 50 and 5 mbar. A prominent feature of the nitric acid field is the persistent ''bending'' of contours due to strong meridional flow. Since these contours persist, instead of aligning with the flow, there must be chemical processes maintaining the nitric acid with timescales shorter than the advective timescale. The time constant for this chemical process ranges from approximately 1 day at 70-degrees-N to about 4 days at 30-degrees-N. When the time constant is used in the 3-D model, all of the basic characteristics of the observations are simulated. It is not clear what chemical mechanisms are responsible for this behavior. There is a strong relationship between the insolation and the shortcomings of the nitric acid simulations. Heterogeneous reactions on background aerosols are considered, but their spatial, temporal, and chemical characteristics are not clearly consistent with the needed changes in the chemistry. If heterogeneous processes are the mechanism, then they are much more complex than currently included in stratospheric models. C1 APPL RES CORP,LANDOVER,MD 20785. NASA HEADQUARTERS,WASHINGTON,DC 20546. RP ROOD, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 9103,GREENBELT,MD 20771, USA. RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 35 TC 12 Z9 12 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18533 EP 18545 DI 10.1029/93JD01419 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200020 ER PT J AU BHARTIA, PK HERMAN, J MCPETERS, RD TORRES, O AF BHARTIA, PK HERMAN, J MCPETERS, RD TORRES, O TI EFFECT OF MOUNT-PINATUBO AEROSOLS ON TOTAL OZONE MEASUREMENTS FROM BACKSCATTER ULTRAVIOLET (BUV) EXPERIMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SULFURIC-ACID; CLOUDS AB Error introduced by Mount Pinatubo aerosols in total ozone derived by the backscatter ultraviolet (BUV) technique is described. BUV instruments include the total ozone mapping spectrometer (TOMS) instrument flying on Nimbus 7 and Meteor 3 satellites and solar backscattered ultraviolet (SBUV 2) instruments on NOAA weather satellites. Radiative transfer calculations show that except at very high solar zenith angle,. errors in total ozone derived from the aerosol-contaminated radiances are less than 2% and vary both in magnitude and in sign with angles of observation. At solar zenith angles greater than 75-degrees. total ozone values may be underestimated by as much as 10% if a large concentration of aerosols is present near the ozone density peak. In subsolar latitudes, error in total ozone derived from TOMS as a function of scan angle is very sensitive to the aerosol size distribution parameters. Aerosol parameters derived from these data agree well with in situ measurements. RP BHARTIA, PK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MAIL CODE 916,GREENBELT,MD 20771, USA. RI McPeters, Richard/G-4955-2013; Torres, Omar/G-4929-2013; Bhartia, Pawan/A-4209-2016 OI McPeters, Richard/0000-0002-8926-8462; Bhartia, Pawan/0000-0001-8307-9137 NR 15 TC 45 Z9 45 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18547 EP 18554 DI 10.1029/93JD01739 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200021 ER PT J AU TREPTE, CR VEIGA, RE MCCORMICK, MP AF TREPTE, CR VEIGA, RE MCCORMICK, MP TI THE POLEWARD DISPERSAL OF MOUNT-PINATUBO VOLCANIC AEROSOL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BREAKING PLANETARY-WAVES; STRATOSPHERIC AEROSOL; II MEASUREMENTS; SAM-II; SAGE; CIRCULATION; SATELLITE; MODEL; LAYER; ERUPTIONS AB Using the SAGE II 1-mum stratospheric aerosol extinction ratio observations. the dispersal of Mount Pinatubo aerosol within two transport regimes during the first 10 months after the eruption is displayed in meridional cross sections. Maximum aerosol extinction ratio values were contained in a tropical reservoir bounded by strong gradients in the subtropics. The detainment of aerosol from the equatorial reservoir occurred in episodic synoptic scale events and two examples are presented: (1) transport into the boreal summer hemisphere in a lower regime just above the tropopause associated with upwardly decaying tropospheric disturbances and (2) dispersal into the austral winter hemisphere in an upper transport regime near 30 hPa associated with planetary wave activity in the southern subtropics. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. UNIV WISCONSIN,DEPT ATMOSPHER & OCEAN SCI,MADISON,WI 53706. NR 37 TC 184 Z9 186 U1 2 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18563 EP 18573 DI 10.1029/93JD01362 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200023 ER PT J AU PIERCE, RB FAIRLIE, TDA AF PIERCE, RB FAIRLIE, TDA TI CHAOTIC ADVECTION IN THE STRATOSPHERE - IMPLICATIONS FOR THE DISPERSAL OF CHEMICALLY PERTURBED AIR FROM THE POLAR VORTEX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE; DYNAMICS; BREAKING; WAVES; MODEL AB The Lagrangian evolution of material lines within the northern hemisphere winter stratospheric vortex is determined using isentropic winds and diabatic heating rates obtained from the NASA Langley Research Center (LaRC) atmospheric circulation model. Transient, subtropical anticyclones lead to deformation of the material lines near the edge of the polar vortex which then rapidly evolve into elongated filaments as material is drawn around the anticyclones. The rate of stretching of the material lines is shown to be exponential, with typical e-folding times of the order of 4 to 8 days. These results provide evidence for ''chaotic advection'' near the edge of the stratospheric polar vortex which leads to rapid mixing of vortex air with tropical and midlatitude air. The characteristic timescales of these mixing processes and the extent to which the mixing penetrates the polar vortex have important implications for the dispersal of chemically perturbed air from the polar vortex throughout the northern hemisphere and attendant ozone depletion, C1 SCI & TECHNOL CORP,HAMPTON,VA 23666. RP PIERCE, RB (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. RI Pierce, Robert Bradley/F-5609-2010 OI Pierce, Robert Bradley/0000-0002-2767-1643 NR 20 TC 95 Z9 96 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18589 EP 18595 DI 10.1029/93JD01619 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200025 ER PT J AU MLYNCZAK, MG SOLOMON, S ZARAS, DS AF MLYNCZAK, MG SOLOMON, S ZARAS, DS TI AN UPDATED MODEL FOR O2(A1-DELTA-G) CONCENTRATIONS IN THE MESOSPHERE AND LOWER THERMOSPHERE AND IMPLICATIONS FOR REMOTE-SENSING OF OZONE AT 1.27 MU-M SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MOLECULAR-OXYGEN; ENERGY-TRANSFER; EXCITATION; RATES AB An updated kinetic model for the calculation of daytime steady state O2(a1DELTA(g)) concentrations in the mesosphere and lower thermosphere is presented. In addition to the usual source from ozone photolysis in the Hartley band, energy transfer from O(1D) produced by photolysis of molecular oxygen in the Lyman alpha and Schumann-Runge continuum spectral intervals is shown be a significant source Of O2(a1DELTA(g)) as well. Numerous changes and additions to the basic O2(a1DELTA(g)) kinetic model have been included. These new sources and kinetic parameters imply that lower mesospheric ozone concentrations as inferred by near-infrared emission techniques are to be decreased by as much as 10% while lower thermospheric ozone concentrations are to be increased by as much as 20%. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23666. NOAA,AERON LAB,BOULDER,CO 80303. RP MLYNCZAK, MG (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401B,HAMPTON,VA 23681, USA. RI Mlynczak, Martin/K-3396-2012 NR 17 TC 35 Z9 37 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18639 EP 18648 DI 10.1029/93JD01478 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200030 ER PT J AU LOUIS, G BESS, TD CHARLOCK, TP ROSE, FG AF LOUIS, G BESS, TD CHARLOCK, TP ROSE, FG TI ANNUAL AND INTERANNUAL VARIATIONS OF EARTH-EMITTED RADIATION BASED ON A 10-YEAR DATA SET - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Note C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP LOUIS, G (reprint author), NASA,LANGLEY RES CTR,DEPT ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1993 VL 98 IS D10 BP 18655 EP 18655 DI 10.1029/93JD01359 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA MD722 UT WOS:A1993MD72200032 ER PT J AU GHOSH, MK BREWE, DE AF GHOSH, MK BREWE, DE TI THERMOMECHANICAL ANALYSIS OF A DRY SHAFT MULTILAYERED BUSH TRIBOSYSTEM USING THE FINITE-ELEMENT METHOD SO COMPUTERS & STRUCTURES LA English DT Article ID SLIDING SYSTEMS; TEMPERATURES; CRACKING; MEDIA AB The thermomechanical analysis of a dry shaft-multilayered bush with a coating on the inner surface, has been accomplished by using the finite element method. Temperatures generated due to frictional heating at the shaft-bush interface and the resulting thermal stresses and deformations have been calculated in the tribosystem. A solid model of the tribosystem was generated using an eight-node three-dimensional first-order isoparametric heat transfer element for temperature analysis and an eight-node three-dimensional isoparametric brick element for stresses/deformation. The solid model was generated using Patran solid modeller software. Finite element analysis of the tribosystem for temperature, stresses and deformation was performed using Marc finite element software on a Cray X-MP supercomputer. The analysis was performed for various coating materials, coating thicknesses and thermal cooling boundary conditions. Higher temperatures are obtained at the shaft-bush interface when the coating material is of low thermal conductivity, e.g. Al2O3 and ZrO2. Results indicate that stresses can be lower in the coating if the coating thickness is lower for coating materials with thermal conductivity lower than the substrate. However, for coating materials with higher thermal conductivity, stresses are not altered appreciably. Thermal stresses and deformation are dependent on the elastic properties and thermal expansion coefficient of the coating material for a given geometry. C1 NASA,LEWIS RES CTR,PROPULS DIRECTORATE,CLEVELAND,OH 44135. RP GHOSH, MK (reprint author), BANARAS HINDU UNIV,INST TECHNOL,DEPT MECH ENGN,VARANASI 221005,UTTAR PRADESH,INDIA. NR 15 TC 2 Z9 2 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD OCT 17 PY 1993 VL 49 IS 2 BP 207 EP 218 DI 10.1016/0045-7949(93)90102-J PG 12 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA MK168 UT WOS:A1993MK16800001 ER PT J AU SOCKOL, PM AF SOCKOL, PM TI MULTIGRID SOLUTION OF THE NAVIER-STOKES EQUATIONS ON HIGHLY STRETCHED GRIDS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE MULTIGRID METHOD; NAVIER-STOKES EQUATIONS; INCOMPRESSIBLE FLOW ID GEOMETRIES; FLOWS AB Relaxation-based multigrid solvers for the steady incompressible Navier-Stokes equations are examined to determine their computational speed and robustness. Four relaxation methods were used as smoothers in a common tailored multigrid procedure. The resulting solvers were applied to three two-dimensional flow problems, over a range of Reynolds numbers, on both uniform and highly stretched grids. In all cases the L2 norm of the velocity changes is reduced to 10(-6) in a few 10's of fine-grid sweeps. The results of the study are used to draw conclusions on the strengths and weaknesses of the individual relaxation methods as well as those of the overall multigrid procedure when used as a solver on highly stretched grids. RP SOCKOL, PM (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135, USA. NR 16 TC 11 Z9 11 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD OCT 15 PY 1993 VL 17 IS 7 BP 543 EP 566 DI 10.1002/fld.1650170702 PG 24 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA LY823 UT WOS:A1993LY82300001 ER PT J AU WU, D OUTLAW, RA ASH, RL AF WU, D OUTLAW, RA ASH, RL TI GLOW-DISCHARGE ENHANCED PERMEATION OF OXYGEN THROUGH SILVER SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID TRANSPORT; AG AB The permeation of oxygen through Ag0.05Zr over the temperature range of 300-650-degrees-C under glow-discharge conditions has been studied and compared to the permeation of thermally dissociated molecular oxygen. A low-energy dc glow-discharge in O2 has been employed which produced approximately 10% atoms. The permeation rate during the glow discharge was found to be much higher (a factor of approximately 10) than without the glow discharge. The small fraction of oxygen atoms generated appears to dominate the permeation because of much higher solution probabilities. Below 500-degrees-C, the activation energy for the permeation with glow discharge was found to be 15.5 kcal/mol compared to 22.0 kcal/mol without glow discharge (molecular oxygen). Above 500-degrees-C, the enhanced permeation with glow discharge gradually diminishes with increasing temperature and approaches that observed without the glow discharge at high temperature; the reason for this is primarily because of the thermal instability of the supersaturated high-pressure interface where atoms recombine and desorb back into the gas phase. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP WU, D (reprint author), OLD DOMINION UNIV,NORFOLK,VA 23508, USA. NR 11 TC 14 Z9 14 U1 1 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 15 PY 1993 VL 74 IS 8 BP 4990 EP 4994 DI 10.1063/1.354304 PG 5 WC Physics, Applied SC Physics GA MC030 UT WOS:A1993MC03000028 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW STALLCOP, JR LEVIN, E AF PARTRIDGE, H BAUSCHLICHER, CW STALLCOP, JR LEVIN, E TI AB-INITIO POTENTIAL-ENERGY SURFACE FOR H-H2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID DIFFERENTIAL CROSS-SECTIONS; STATE REACTION DYNAMICS; REACTION D+H2->HD+H; DISPERSION COEFFICIENTS; TRAJECTORY CALCULATIONS; INELASTIC-SCATTERING; ANGULAR-MOMENTUM; QUANTUM DYNAMICS; BARRIER HEIGHT; BASIS-SETS AB Ab initio calculations employing large basis sets are performed to determine an accurate potential energy surface for H-H-2 interactions for a broad range of separation distances. At large distances, the spherically averaged potential determined from the calculated energies agrees well with the corresponding results determined from dispersion coefficients; the van der Waals well depth is predicted to be 75+/-3muE(h). Large basis sets have also been applied to reexamine the accuracy of theoretical repulsive potential energy surfaces (25-70 kcal/mol above the H-H-2 asymptote) at small interatomic separations; the Boothroyd, Keogh, Martin, and Peterson (BKMP) potential energy surface is found to agree with results of the present calculations to within the expected uncertainty (+/- 1 kcal/mol) of the fit. Multipolar expansions of the computed H-H-2 potential energy surface are reported for four internuclear separation distances (1.2, 1.401, 1.449, and 1.7a0) of the hydrogen molecule. The differential elastic scattering cross section calculated from the present results is compared with the measurements from a crossed beam experiment. C1 ELORET INST,PALO ALTO,CA 94303. RP PARTRIDGE, H (reprint author), NASA,AMES RES CTR,DIV THERMOSCI,COMPUTAT CHEM,MOFFETT FIELD,CA 94035, USA. NR 51 TC 50 Z9 50 U1 1 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 15 PY 1993 VL 99 IS 8 BP 5951 EP 5960 DI 10.1063/1.465894 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA MB564 UT WOS:A1993MB56400038 ER PT J AU FRANCISCO, JS SANDER, SP AF FRANCISCO, JS SANDER, SP TI STRUCTURE AND THERMOCHEMISTRY OF HYDROCHLOROUS ACID, HOCL SO JOURNAL OF CHEMICAL PHYSICS LA English DT Note ID QUADRATIC CONFIGURATION-INTERACTION; EQUILIBRIUM-CONSTANT; ULTRAVIOLET-SPECTRUM; HEATS RP FRANCISCO, JS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 13 Z9 13 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 15 PY 1993 VL 99 IS 8 BP 6219 EP 6226 DI 10.1063/1.465885 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA MB564 UT WOS:A1993MB56400065 ER PT J AU TURNER, MS AF TURNER, MS TI PRODUCTION OF SCALAR AND TENSOR PERTURBATIONS IN INFLATIONARY MODELS SO PHYSICAL REVIEW D LA English DT Article ID ISOTHERMAL DENSITY PERTURBATIONS; MICROWAVE BACKGROUND ANISOTROPY; GRAVITATIONAL-WAVES; EXTENDED INFLATION; FLUCTUATION SPECTRA; UNIVERSE SCENARIO; GRAND UNIFICATION; DARK MATTER; COSMOLOGY; COBE AB Scalar (density) and tensor (gravity-wave) perturbations provide the basis for the fundamental observable consequences of inflation, including CBR anisotropy and the formation of structure in the Universe. These perturbations are nearly scale invariant (Harrison-Zel'dovich spectrum), though a slight deviation from scale invariance (''tilt'') can have significant consequences for both CBR anisotropy and structure formation. In particular, a slightly tilted spectrum of scalar perturbations may improve the agreement of the cold dark matter scenario with the observational data. The amplitude and spectrum of the scalar and tensor perturbations depend upon the shape of the inflationary potential in the small interval where the scalar field responsible for inflation was between about 46 and 54 e-folds before the end of inflation. By expanding the inflationary potential in a Taylor series over this interval we show that the amplitudes of the perturbations and the power-law slopes of their spectra can be expressed in terms of the value of the potential 50 e-folds before the end of inflation, V50, its steepness x 50 = m(pl)V'50/V50, and the rate of change of its steepness, x'50 (a prime denotes a derivative with respect to the scalar field). In addition, the power-law index of the cosmic-scale factor at this time is q50 = [dlnR/dlnt]50 cogruent-to 16pi/X(50)2. (Formally, our results for the perturbation amplitudes and spectral indices are accurate to lowest order in the deviation from scale invariance.) In general, the deviation from scale invariance is such to enhance fluctuations on large scales, and is only significant for steep potentials, large x50, or potentials with rapidly changing steepness, large x'50. In the latter case, only the spectrum of scalar perturbations is significantly tilted. Steep potentials are characterized by a large tensor-mode contribution to the quadrupole CBR temperature anisotropy, a similar tilt in both scalar and tensor perturbations, and a slower expansion rate, i.e., smaller q50. Measurements of the amplitude and tilt of the scalar and tensor perturbations overdetermine V50, x50, and x'50, and r-an in principle be used to infer these quantities as well as for testing the inflationary hypothesis. Our formalism has its limitations; it is not applicable to potentials with unusual features in the region that affects astrophysical scales. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP TURNER, MS (reprint author), UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637, USA. NR 62 TC 62 Z9 62 U1 0 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1993 VL 48 IS 8 BP 3502 EP 3512 DI 10.1103/PhysRevD.48.3502 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA MG847 UT WOS:A1993MG84700012 ER PT J AU GRASSO, D KOLB, EW AF GRASSO, D KOLB, EW TI PLASMON DECAY TO V(V)OVER-BAR IN A RELATIVISTIC PLASMA SO PHYSICAL REVIEW D LA English DT Article ID NEUTRINO MAGNETIC-MOMENTS; NUCLEOSYNTHESIS; CONSTRAINTS AB The plasmon decay rate to neutrino-antineutrino pairs is calculated assuming a nonvanishing magnetic moment for the neutrino. Since we are interested in the ultrarelativistic regime (T > m(e)c2), an appropriate covariant formalism is introduced to treat collective plasma excitations. We show that this process could result in an important contribution to the production of wrong-helicity neutrinos in the early Universe. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. IST NAZL FIS NUCL,SEZIONE ROMA,ROME,ITALY. RP GRASSO, D (reprint author), UNIV ROMA LA SAPIENZA,SCUOLA DOTTORATO RICERCA,DIPARTIMENTO FIS,I-00185 ROME,ITALY. RI Grasso, Dario/I-2440-2012 OI Grasso, Dario/0000-0001-7761-7242 NR 23 TC 6 Z9 6 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1993 VL 48 IS 8 BP 3522 EP 3526 DI 10.1103/PhysRevD.48.3522 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA MG847 UT WOS:A1993MG84700015 ER PT J AU ALBRECHT, A AF ALBRECHT, A TI FOLLOWING A COLLAPSING WAVE-FUNCTION SO PHYSICAL REVIEW D LA English DT Article ID QUANTUM BROWNIAN-MOTION; LOGICAL REFORMULATION; MECHANICS; ENVIRONMENT; DECOHERENCE; PACKET AB I study the quantum mechanics of a spin interacting with an ''apparatus.'' Although the evolution of the whole system is unitary, the spin evolution is not. The system is chosen so that the spin exhibits loss of quantum coherence, or ''wave function collapse,'' of the sort usually associated with a quantum measurement. The system is analyzed from the point of view of the spin density matrix (or ''Schmidt paths''), and also using the consistent histories approach. These two points of view are contrasted with each other. Connections between the results and the form of the Hamiltonian discussed in detail. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP ALBRECHT, A (reprint author), NASA,FERMILAB,CTR ASTROPHYS,POB 500,BATAVIA,IL 60510, USA. NR 35 TC 29 Z9 29 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1993 VL 48 IS 8 BP 3768 EP 3778 DI 10.1103/PhysRevD.48.3768 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA MG847 UT WOS:A1993MG84700043 ER PT J AU SEKANINA, Z AF SEKANINA, Z TI DISINTEGRATION PHENOMENA EXPECTED DURING COLLISION OF COMET SHOEMAKER-LEVY-9 WITH JUPITER SO SCIENCE LA English DT Article ID PRECESSION; METEOROIDS; METEORITE; FIREBALL; NUCLEUS AB In July 1994, periodic comet Shoemaker-Levy 9 is expected to collide with Jupiter. The largest fragments of the comet's original nucleus will be tidally disrupted shortly before they enter the Jovian atmosphere, and all fragments, from large rocks to small grains, will suffer ablation and disintegration as a result of interaction with the atmosphere. Even if atmospheric entry takes place on the planet's far side, secondary phenomena triggered by the terminal explosions of kilometer-sized fragments are likely to be observable from the Earth. RP SEKANINA, Z (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 51 TC 56 Z9 57 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 15 PY 1993 VL 262 IS 5132 BP 382 EP 387 DI 10.1126/science.262.5132.382 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MB859 UT WOS:A1993MB85900047 PM 17789945 ER PT J AU SANDFORD, SA ALLAMANDOLA, LJ GEBALLE, TR AF SANDFORD, SA ALLAMANDOLA, LJ GEBALLE, TR TI SPECTROSCOPIC DETECTION OF MOLECULAR-HYDROGEN FROZEN IN INTERSTELLAR ICES (RETRACTED ARTICLE. SEE VOL 287, PG 976, 2000) SO SCIENCE LA English DT Article; Retracted Publication ID DENSE CLOUDS; FEATURES; GAS AB A weak infrared absorption feature near 4141 wavenumbers (2.415 micrometers) in the spectrum of WL5, an infrared source in the rho Ophiuchus cloud complex, has been detected. It is attributed to molecular hydrogen created by irradiation and frozen in situ into water-rich ices. A second, broader absorption at 4125 wavenumbers centimeters (2.424 micrometers) is probably due to methanol in the ices. The column densities of frozen molecular hydrogen and methanol are inferred to be about 2.5 x 10(18) and 3.0 x 10(19), respectively. There is about three times more frozen molecular hydrogen than frozen carbon monoxide along this line of sight. C1 JOINT ASTRON CTR, HILO, HI 96720 USA. RP SANDFORD, SA (reprint author), NASA, AMES RES CTR, MAIL STOP 245-6, MOFFETT FIELD, CA 94035 USA. NR 29 TC 59 Z9 59 U1 2 U2 7 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 15 PY 1993 VL 262 IS 5132 BP 400 EP 404 DI 10.1126/science.11542874 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MB859 UT WOS:A1993MB85900050 PM 11542874 ER PT J AU WEAVER, ML KAUFMAN, MJ NOEBE, RD AF WEAVER, ML KAUFMAN, MJ NOEBE, RD TI THE EFFECTS OF ALLOY PURITY ON THE MECHANICAL-BEHAVIOR OF SOFT ORIENTED NIAL SINGLE-CRYSTALS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID DEFORMATION; TENSILE; TEMPERATURE; FRACTURE; BRITTLE; METALS C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WEAVER, ML (reprint author), UNIV FLORIDA,DEPT MAT SCI & ENGN,GAINESVILLE,FL 32611, USA. NR 28 TC 20 Z9 20 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD OCT 15 PY 1993 VL 29 IS 8 BP 1113 EP 1118 DI 10.1016/0956-716X(93)90187-W PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA LV343 UT WOS:A1993LV34300020 ER PT J AU MADEJSKI, GM DONE, C TURNER, TJ MUSHOTZKY, RF SERLEMITSOS, P FIORE, F SIKORA, M BEGELMAN, MC AF MADEJSKI, GM DONE, C TURNER, TJ MUSHOTZKY, RF SERLEMITSOS, P FIORE, F SIKORA, M BEGELMAN, MC TI SOLVING THE MYSTERY OF THE X-RAY PERIODICITY IN THE SEYFERT-GALAXY NGC6814 SO NATURE LA English DT Article ID VARIABILITY; NGC-6814; LINE AB ACTIVE galaxies, of which Seyfert galaxies are a subgroup, are thought to be powered by the accretion of gas onto a massive black hole at the galaxy centre; the X-rays emitted by active galactic nuclei arise from the heated, infalling gas. The observed rapid variability of this X-ray emission requires a compact source, providing additional support for the black-hole hypothesis. The Seyfert galaxy NGC6814 has been thought to be unique among active galaxies, in exhibiting not simply variability but a periodicity of approximately 12,100 s in its X-ray luminosity1-4. Many exotic theories have been proposed to explain this periodicity, including, gravitational lensing of hotspots on the accretion disk by the central black hole5-7 or the effects of a captured star orbiting the black hole4,8-10. Here we show, using data from the Rosat X-ray telescope, that although the 12,100 s period is indeed real and stable, it is not associated with NGC6814. Instead, the periodic emission arises from another source, 37 arcmin away from NGC6814, which is probably an object in our Galaxy-for example, a white dwarf accreting gas (from a giant companion) onto its poles. C1 UNIV SPACE RES ASSOC,GREENBELT,MD 20771. CTR ASTROPHYS,CAMBRIDGE,MA 02138. COPERNICUS ASTRON CTR,PL-00716 WARSAW,POLAND. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,BOULDER,CO 80309. RP MADEJSKI, GM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. RI done, chris/D-4605-2016; OI done, chris/0000-0002-1065-7239; Fiore, Fabrizio/0000-0002-4031-4157 NR 25 TC 53 Z9 53 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 14 PY 1993 VL 365 IS 6447 BP 626 EP 628 DI 10.1038/365626a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MB846 UT WOS:A1993MB84600051 ER PT J AU SUMMERS, DP CHANG, S AF SUMMERS, DP CHANG, S TI PREBIOTIC AMMONIA FROM REDUCTION OF NITRITE BY IRON(II) ON THE EARLY EARTH SO NATURE LA English DT Article ID AQUEOUS-SOLUTION; CARBON-DIOXIDE; ATMOSPHERE; EVOLUTION; NITROGEN; FIXATION; SEAWATER; IMPACTS; OXYGEN; SULFUR AB THEORIES for the origin of life require the availability of reduced (or 'fixed') nitrogen-containing compounds, in particular ammonia. In reducing atmospheres, such compounds are readily formed by electrical discharges1-2, but geochemical evidence suggests that the early Earth had a non-reducing atmosphere1,3-6, in which discharges would have instead produced NO (refs 7-10). This would have been converted into nitric and nitrous acids and delivered to the early oceans as acid rain11. It is known12-15, however, that Fe(II) was present in the early oceans at much higher concentrations than are found today, and thus the oxidation of Fe(II) to Fe(III) provides a possible means for reducing nitrites and nitrates to ammonia. Here we explore this possibility in a series of experiments which mimic a broad range of prebiotic seawater conditions (the actual conditions on the early Earth remain poorly constrained). We find that the reduction by Fe(II) of nitrites and nitrates to ammonia could have been a significant source of reduced nitrogen on the early Earth, provided that the ocean pH exceeded 7.3 and is favoured for temperatures greater than about 25-degrees-C. RP SUMMERS, DP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 31 TC 91 Z9 93 U1 4 U2 39 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 14 PY 1993 VL 365 IS 6447 BP 630 EP 632 DI 10.1038/365630a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MB846 UT WOS:A1993MB84600053 PM 11540245 ER PT J AU BONAVITO, NL DORBAND, JE BUSSE, T AF BONAVITO, NL DORBAND, JE BUSSE, T TI MAXIMUM-ENTROPY RESTORATION OF BLURRED AND OVERSATURATED HUBBLE-SPACE-TELESCOPE IMAGERY SO APPLIED OPTICS LA English DT Article AB A brief introduction to image reconstruction is made and the basic concepts of the maximum entropy method are outlined. A statistical inference algorithm based on this method is presented. The algorithm is tested on simulated data and applied to real data. The latter is from a 1024 x 1024 Hubble Space Telescope image of the binary stellar system R Aquarii, which suffers from both spherical aberration and detector saturation. Under these constraints the maximum entropy method produces an image that agrees closely with observed results. The calculations were performed on the MasPar MP-1 single-instruction/multiple-data computer. C1 MASPAR COMP CORP, BETHESDA, MD 20817 USA. RP BONAVITO, NL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, DIV SPACE DATA & COMP, GREENBELT, MD 20771 USA. NR 29 TC 10 Z9 13 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 10 PY 1993 VL 32 IS 29 BP 5768 EP 5774 PG 7 WC Optics SC Optics GA LZ639 UT WOS:A1993LZ63900007 PM 20856397 ER PT J AU CHRISTODOULOU, DM TOHLINE, JE STEIMANCAMERON, TY AF CHRISTODOULOU, DM TOHLINE, JE STEIMANCAMERON, TY TI KINEMATICAL MODELING OF WARPS IN THE H-I DISKS OF GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, KINEMATICS AND DYNAMICS; GALAXIES, STRUCTURE; RADIO LINES, GALAXIES ID APERTURE-SYNTHESIS OBSERVATIONS; PREFERRED ORBIT PLANES; NEUTRAL HYDROGEN; NEWTONIAN DYNAMICS; TRIAXIAL GALAXIES; ROTATIONAL PROPERTIES; SPIRAL GALAXIES; GALACTIC WARPS; MASS PROBLEM; HIDDEN MASS AB In order to gain an appreciation for the general structure of warped gas layers in galaxies, we have con-structed kinematical, tilted-ring models of 21 galaxies for which detailed H I observations already exist in the literature. In this paper we present results for the 15 normal spiral galaxies of this sample that are not viewed edge-on. A comparison between our models and tilted-ring models of the same galaxies previously constructed by other authors shows that there is generally good agreement. We make an attempt to unify the notation of different authors who have published radio observations and/or kinematical models of individual galaxies in this sample. We also suggest how, in future work of this nature, model parameters should be presented and referenced in order to maintain a reasonable degree of consistency in the liteature. When viewed in the perspective of dynamical models, a twisted warped gas layer can be understood as arising from orbiting gas which is in the process of settling to a preferred orientation in the nonspherical, gravitational potential well of the galaxy. Hence, detailed kinematical modeling of a specific galaxy disk can provide not only information regarding the orientation and structure of its warp but also information about the shape (whether oblate or prolate) of the dark halo in which the disk is embedded. By examining a large number of galaxies in a consistent manner, we have deduced some general characteristics of warped disks that have heretofore gone unnoticed. We have also identified uniqueness problems that can arise in this type of modeling procedure which can considerably cloud one's ability to completely decipher an individual disk's structure. For 14 out of 15 spiral galaxies modeled here, we have been able to determine the local kinematical structure of the warp. Gas layers do not appear to warp more than approximately 40-degrees out of the plane defined by the central disk of the galaxy, but they can twist through angles as large as 170-degrees. The overall position of the warp and the gross geometric shape of the halo have been determined unambiguously only in cases where the twisting of the warp is relatively strong. (Examples of galaxies whose disks sit in an oblate halo are M33, M83, NGC 2805, NGC 2841, and NGC 3718; prolate halos appear to surround NGC 5033 and NGC 5055; and ambiguous cases, at present permitting equally good oblate and prolate halo models, are M31, NGC 300, NGC 3079, NGC 3198, NGC 6946, NGC 7331, and IC 342.) There appears to be a high degree of correlation between the twisting angles of kinematical models and precession angles derived from dynamical arguments. This correlation gives us considerable confidence that the kinematically identified twists in warped H I layers are real and that the general dynamical picture that has been put forward to explain their existence is correct. Adopting a scale-free, logarithmic halo potential having a quadrupole distortion eta, we conclude specifically that in each of these twisted warped disk systems the product etatau8 is approximately equal to 1, where tau8 is the age of the warped layer in 10(8) yr. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. RP CHRISTODOULOU, DM (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 76 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 74 EP 103 DI 10.1086/173216 PN 1 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800007 ER PT J AU RYDER, S STAVELEYSMITH, L DOPITA, M PETRE, R COLBERT, E MALIN, D SCHLEGEL, E AF RYDER, S STAVELEYSMITH, L DOPITA, M PETRE, R COLBERT, E MALIN, D SCHLEGEL, E TI SN 1978K - AN EXTRAORDINARY SUPERNOVA IN THE NEARBY GALAXY NGC 1313 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 1313); STARS, INDIVIDUAL (SN 1978K); SUPERNOVAE, INDIVIDUAL (SN 1978K) ID X-RAY OBSERVATIONS; H-II REGIONS; MAGELLANIC CLOUD; RADIO-EMISSION; SOUTHERN GALAXIES; SPIRAL GALAXIES; ETA-CARINAE; SN-1986J; SN-1961V; NGC-1313 AB We have identified an extremely luminous radio and X-ray source with an optically variable emission-line object in the outskirts of the nearby barred spiral galaxy NGC 1313. Archival data show that the object (officially designated SN 1978K) had a major optical outburst (M(B) < - 12.3) in mid-1978 and that a radio and X-ray outburst followed this event. The light curve, optical spectra, radio data, and the X-ray data all indicate that the event was a very unusual Type II supernova, with many similar properties to the so-called Type V supernovae SN 1961V in NGC 1058 and SN 1986J in NGC 891. The currently bright Doppler-broadened Balmer lines, the forbidden lines and the extremely high radio and X-ray luminosities (among the brightest of known supernovae in both regimes) are believed to be powered by the shock driving through a dense circumstellar medium created by extreme mass-loss (approximately 4 x 10(-4) M. yr-1) from a massive progenitor. Some of the optical properties may be explained by the super outburst of an eta Carinae-type object, but such an event would fail to explain the radio and X-ray luminosity. The closeness, low extinction and low confusion toward SN 1978K will allow for a detailed study of a class of peculiar supernovae which is possibly much more common than previously supposed. C1 AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,X-RAY ASTROPHYS BRANCH,GREENBELT,MD 20771. UNIV MARYLAND,ASTRON PROGRAM,COLL PK,MD 20742. ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP RYDER, S (reprint author), UNIV ALABAMA,DEPT PHYS & ASTRON,BOX 870324,TUSCALOOSA,AL 35487, USA. RI Staveley-Smith, Lister/A-1683-2011; Dopita, Michael/P-5413-2014; OI Staveley-Smith, Lister/0000-0002-8057-0294; Dopita, Michael/0000-0003-0922-4986; Ryder, Stuart/0000-0003-4501-8100 NR 72 TC 100 Z9 100 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 167 EP & DI 10.1086/173223 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800014 ER PT J AU WU, CC CRENSHAW, DM FESEN, RA HAMILTON, AJS SARAZIN, CL AF WU, CC CRENSHAW, DM FESEN, RA HAMILTON, AJS SARAZIN, CL TI FAINT OBJECT SPECTROGRAPH SPECTRA OF THE BROAD FE-II ABSORPTION-LINES IN THE REMNANT OF SN-1006 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, ABUNDANCES; ISM, INDIVIDUAL (SN 1006); SUPERNOVA REMNANTS AB Ultraviolet spectra of a hot subdwarf star located behind the remnant of SN 1006 have been obtained with the Faint Object Spectrograph on the Hubble Space Telescope. The FOS UV spectra show strong and extremely broad Fe II lambda2343, lambda2374, lambda2382, lambda2586, and lambda2599 lines in absorption from the supernova remnant, confirming an earlier detection with the International Ultraviolet Explorer. The better resolution and signal-to-noise of the FOS spectra allow for the removal of narrow interstellar and stellar lines and the deblending of the broad Fe II lines, resulting in an intrinsic Fe II profile suitable for detailed comparison with model predictions. The velocity profile of the ejecta is approximately symmetric around 0 km s 1 and extends up to +/-8300 km s-1 at the continuum. The absorption-line width and angular size of the remnant yield a lower limit of 1.9 kpc to the distance of the remnant. The remnant contains approximately 0.014 M . of Fe+. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. DARTMOUTH COLL,DEPT PHYS & ASTRON,HANOVER,NH 03755. UNIV COLORADO,JILA,BOULDER,CO 80309. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. RP WU, CC (reprint author), SPACE TELESCOPE SCI INST,COMP SCI CORP,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 10 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 247 EP 250 DI 10.1086/173230 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800021 ER PT J AU ELITZUR, M AF ELITZUR, M TI POLARIZATION OF ASTRONOMICAL MASER RADIATION .2. POLARIZATION MODES AND UNSATURATED GROWTH SO ASTROPHYSICAL JOURNAL LA English DT Article DE MASERS; MOLECULAR PROCESSES; POLARIZATION; RADIATIVE TRANSFER ID ASTROPHYSICAL MASERS; MAGNETIC-FIELDS AB Maser polarization is analyzed in the limit of overlapping Zeeman components (gv(B) much less than DELTAv(D), where gv(B) is the Zeeman splitting and DELTAnu(D) is the Doppler width). All the discrepancies among the conflicting conclusions of previous studies that identified maser polarizations in this limit are fully resolved. In the case of m-independent pumping, proper application of the eigenvalue technique of Goldreich, Keeley, & Kwan shows that the polarization eigenvectors are the same for saturated and unsaturated masers and are independent of spin for pure spin states, in agreement with the results of the first paper in this series. Stable eigenvectors correspond to the peak of the polarization mode distribution of self-amplified radiation at any degree of saturation. But the distribution average, the actually measured polarization, does not necessarily coincide with its peak. The mode distribution starts with a rectangular shape, because the seed radiation generated in spontaneous decays is unpolarized. and evolves toward a sharply peaked profile whose average, and not just its peak, coincides with the eigenvector solution because of the following two effects. First, interaction with the maser molecules induces rotation of the polarization vectors of individual modes, similar to Faraday rotation. The rotation rate is different for different modes, and the polarization eigenvectors correspond to stationary modes that do not rotate. Starting from unpolarized radiation generated by the source terms and containing an equal mix of all modes, all individual polarization vectors rotate into the stationary stable modes, resulting in a radiation field polarized according to the solution of the eigenvalue problem. As a result of this rotation the ensemble-averaged Stokes parameters reach the eigenvector solution when J greater than or similar to J(s), where J(s) is the angle-averaged intensity and J. is the saturation intensity, i.e., only after the maser saturates. This explains the results of numerical studies of the maser polarization problem presented in the literature. Second, and more important, maser growth is highly unstable during the unsaturated phase for any polarization configuration except for that of the eigenvector solution. The Stokes parameters of all other polarization structures include terms proportional to exp \aI\, where I is the intensity and a not-equal 0, and thus are highly unstable against arbitrarily small intensity perturbations. Such perturbations induce runaway divergence of the ensemble-averaged Stokes parameters away from their initial values, a divergence that stops only when the polarization settles into the appropriate eigenvector solution. The e-folding growth rate of the instabilities increases with J and reaches unity when J approximately J(s)/tau(s), where tau(s) is the optical depth of the maser when it saturates; pumping schemes of astronomical masers typically produce tau(s) approximately 12-17. Instabilities impose an upper bound on the intensity of radiation whose polarization differs from that of the eigenvector solution and are the dominant factor in narrowing the polarization mode distribution around its peak. Only radiation whose ensemble-averaged polarization corresponds to the eigenvector solution can grow to saturation and beyond. Furthermore, all polarization configurations are unstable for propagation at 0 < theta < theta0, where theta is measured from the magnetic axis and sin2 theta0 = 1/3. One eigenvector solution, corresponding to fully polarized radiation, is stable in this region during the unsaturated growth phase against perturbations that rotate the polarization at a fixed intensity, but not against intensity perturbations. As a result, stable buildup of maser radiation in a magnetic field with gv(B) much less than DELTAv(D) is possible only for theta greater-than-or-equal-to 0,; propagation directions too close to the field axis, corresponding to a fractional volume of approximately 0.09, are excluded. Propagation along the axis, theta = 0, is allowed, but the corresponding radiation is unpolarized. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ELITZUR, M (reprint author), UNIV KENTUCKY,DEPT PHYS & ASTRON,LEXINGTON,KY 40506, USA. NR 12 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 256 EP 266 DI 10.1086/173232 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800023 ER PT J AU CANUTO, VM AF CANUTO, VM TI TURBULENT CONVECTION WITH OVERSHOOTING - REYNOLDS STRESS APPROACH .2. SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; STARS, INTERIORS; TURBULENCE ID STABLY STRATIFIED FLUID; COMPRESSIBLE CONVECTION; STELLAR EVOLUTION; BOUNDARY-LAYER; MASSIVE STARS; HEAT-FLUX; SPECTRA; MODELS; CORES; ZONE AB We derive a new nonlocal model for turbulent convection which incorporates recent advances from laboratory, planetary, and numerical simulation of turbulence, and we show how previous prototypic models can be recovered. The new model is given by five coupled differential equations, equations (81)-(84) and (100), that yield: convective flux, temperature variance, turbulent kinetic energy in the z-direction, total turbulent kinetic energy, and (rate of) dissipation of kinetic energy. The solution of these five equations yields all the turbulent quantities as a function of the temperature gradient. The latter is then obtained by solving the flux conservation law, equation (96), which we derive anew to account for the kinetic energy flux. The main features of the new model are as follows. 1. Nonlocality.-This basic feature is represented by the third-order moments that enter the governing equations (81)-(84) and (100). In all nonlocal models thus far, these moments were treated with the diffusion approximation. Since the latter yields incorrect results in the case of the convective boundary layer, we avoid it. We derive the dynamic equations for all the third-order moments and solve them analytically. 2. Gravity waves, stable stratification.--The fundamental feature of the overshooting (OV) region is that the flow is stably stratified, del - del(ad) < 0. Under such circumstances, the Kolmogorov spectrum is no longer valid since eddies, working against gravity, lose a fraction of their kinetic energy which goes to generate ''gravity waves.'' To fully account for the appearance of a '' buoyancy subrange'' E(k) approximately k-3 in lieu of the Kolmogorov spectrum approximately k-5/3, we adopt a recent model for stably stratified turbulence which has been successfully tested against convective boundary layer data. 3. Dissipation epsilon.-The process of dissipation of turbulent kinetic energy has been neglected for many years, but is now viewed as crucial for a proper quantification of OV. The assumption epsilon = 0 not only violates the energy conservation law, but overestimates the extent of the OV region. When epsilon is included, it is generally computed locally with a mixing length 1. If the description of l is difficult in the main convective region, it is all the more so in the OV region where the concept of a mixing length loses its physical content. We avoid the use of a mixing length in both the convective and the OV region by introducing a differential equation for the dissipation epsilon, equation (100), which, being nonlocal, accounts for the fact that turbulent kinetic energy created at one point in the flow may be dissipated somewhere else, in accordance with the nonlocal nature of turbulent convection. 4. Pressure forces, anisotropy.-The stably stratified turbulence found in the OV region is experimentally known to be highly anisotropic since negative buoyancy suppresses the eddy vertical motion. Thus, pressure-velocity and pressure-temperature correlations, which help restore isotropy, play a crucial role. 5. The Boussinesq Approximation is avoided. 6. The turbulent kinetic energy flux.-A new flux conservation law, equation (96), is derived which includes the turbulent kinetic energy flux recently found to be up to 50% of the total flux for Sun-like stars. 7. A new hydrostatic equilibrium equation, equation (103), is derived which, in addition to a turbulent pressure, also includes buoyancy effects. The next step is to couple the new model to a stellar structure code. RP CANUTO, VM (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 84 TC 68 Z9 69 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 331 EP 354 DI 10.1086/173238 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800029 ER PT J AU SHORE, SN AUFDENBERG, JP AF SHORE, SN AUFDENBERG, JP TI ON THE INTERPRETATION OF THE ULTRAVIOLET-SPECTRA OF SYMBIOTIC STARS AND RECURRENT NOVAE .1. SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; LINE, PROFILES; NOVAE, CATACLYSMIC VARIABLES; STARS, EMISSION-LINE, BE; ULTRAVIOLET, STARS AB We present an analysis of high-resolution spectra of several symbiotics and symbiotic novae. We show that the emission lines are severely affected by differential extinction caused by absorption lines in the wind of the red giant companion. The major source of the absorbing spectrum is the forest of lines produced by neutral and singly ionized iron peak elements. We present models for the effects of this ''iron curtain,'' and we show that some of the outstanding anomalies in the emission-line fluxes results from the differential absorption by the environment as the path length along the line-of-sight changes; (2) observed ultraviolet continuum temperatures should, in general, be considerably lower than that inferred from the Zanstra method or related measures of the ionization temperature; (3) disappearance of the emission lines need not imply any changes at all in the intrinsic properties of the ionizing source but may simply reflect the orbital modulation of its intensity by the circumstellar environment- (4) circumstellar absorption also affects the interpretation of broad emission line profiles; and (5) the absence of emission lines is not a strong argument against the existence of an accretion disk around the hot component. C1 DEMIRM,OBSERV MEUDON,F-92195 MEUDON,FRANCE. UNIV TOLEDO,DEPT PHYS & ASTRON,TOLEDO,OH 43606. RP SHORE, SN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GHRS SCI TEAM COMP SCI CORP,CODE 681,GREENBELT,MD 20771, USA. NR 31 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 355 EP 367 DI 10.1086/173239 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800030 ER PT J AU ROUMELIOTIS, G MOORE, RL AF ROUMELIOTIS, G MOORE, RL TI A LINEAR SOLUTION FOR MAGNETIC RECONNECTION DRIVEN BY CONVERGING OR DIVERGING FOOTPOINT MOTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CORONA; SUN, FLARES; SUN, MAGNETIC FIELDS ID CURRENT SHEETS; FIELDS AB In this paper, we develop a linear, analytic model for magnetic reconnection and current sheet formation at an X-type neutral line in the solar atmosphere. The reconnection process is assumed to be driven by converging or diverging footpoint motions at the photosphere. In particular, we examine how the stressed magnetic configuration around the neutral line is influenced by the magnitude of the photospheric driving velocities and the properties of the plasma between the photosphere and the neutral line. From application of the model to the solar atmosphere in active regions, we suggest that flux cancellation in the photosphere may be accomplished through gradual, linear reconnection with little noticeable heating of the atmosphere around the reconnection site and that the classical coronal neutral line current sheet will likely undergo continual rapid dissipation that prevents the build-up of enough stored magnetic energy to power a flare. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP ROUMELIOTIS, G (reprint author), STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305, USA. NR 14 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP 386 EP 391 DI 10.1086/173243 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA328 UT WOS:A1993MA32800034 ER PT J AU KUIPER, TBH WHITEOAK, JB PENG, RS PETERS, WL REYNOLDS, JE AF KUIPER, TBH WHITEOAK, JB PENG, RS PETERS, WL REYNOLDS, JE TI REFRIGERATION OF THE 18.3 GHZ C3H2 TRANSITION IN DARK CLOUD G1.6-0.25 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (G1.6-0.025); ISM, MOLECULES; LINE, FORMATION; MOLECULAR PROCESSES; RADIO LINES, ISM ID CYCLOPROPENYLIDENE AB We have observed 1(10)-1(01) (18.3 GHz) transition of ortho-cyclopropenylidene, C3H2, at 24 positions in the unusual dense cloud G1.6-0.025. Except for one position, the transition is refrigerated, a phenomenon which has not been seen in this transition before and was not predicted to occur. In general, the absorption correlates with the absorption seen in the 2(0)-3(-1) (12.2 GHz) transition of methanol, but there are significant differences. We suspect that collisional excitation at relatively high kinetic temperature (50 K) enhanced by photon trapping is responsible for the refrigeration. C1 CSIRO,AUSTRALIA TELESCOPE NATL FAC,EPPING,NSW 2121,AUSTRALIA. UNIV NEW S WALES,SCH PHYS,KENSINGTON,NSW 2033,AUSTRALIA. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP KUIPER, TBH (reprint author), JET PROP LAB,169-506,PASADENA,CA 91109, USA. NR 19 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1993 VL 416 IS 1 BP L33 EP L36 DI 10.1086/187064 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA331 UT WOS:A1993MA33100009 ER PT J AU FARRELL, WM AF FARRELL, WM TI THE HELIOSPHERIC CAVITY RADIO-EMISSION - GENERATION OF DISCRETE TONES BY FERMI ACCELERATION VIA OSCILLATING BOUNDARY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OUTER HELIOSPHERE; SURFACE-WAVES; MAGNETOPAUSE; CONSTRAINTS AB A theory is presented that describes the formation of the discrete radio tones that could apply to the radio emission observed in the outer heliosphere by the Voyager spacecraft. Specifically, a broadband emission is assumed to be trapped within the heliospheric cavity. If the heliospheric outer boundary, the heliopause, has a large-scale, monochromatic oscillation, the trapped emission will form intense, discrete tones at wave frequencies where the photon travel time is an integer ratio of the boundary oscillation period. A new set of nonlinear coupled difference equations am presented that describe the interaction of the trapped photon with the boundary, the set appearing similar to that used to model Fermi acceleration of particles via oscillatory boundaries. Results indicate that heliopause oscillation periods on the order of 1000s of seconds could generate tones at frequencies near those observed by Voyager. The tones can also drift in association with the changing cavity size or oscillation period. RP FARRELL, WM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 695, GREENBELT, MD 20771 USA. RI Farrell, William/I-4865-2013 NR 16 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 8 PY 1993 VL 20 IS 19 BP 2011 EP 2014 DI 10.1029/93GL01114 PG 4 WC Geosciences, Multidisciplinary SC Geology GA MB580 UT WOS:A1993MB58000001 ER PT J AU SISKIND, DE SUMMERS, ME MLYNCZAK, MG AF SISKIND, DE SUMMERS, ME MLYNCZAK, MG TI AN EVALUATION OF O-2(B(1)SIGMA(G)) AS A POSSIBLE SOURCE OF OH AND ODD-NITROGEN IN THE STRATOSPHERE AND MESOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OZONE AB A one dimensional photochemical model has been used to evaluate the hypothesis that the oxidation of H-2 and N2O by O2(b1SIGMA(g)) could lead to significant production of OH and odd-nitrogen in the middle atmosphere. For the reaction with H-2, even if all the quenchings lead to oxidation, the change in the OH column is only 13%. This is still too small to resolve the discrepancy between the model and ground based measurements and furthermore could not account for the apparent change in the ground based column with time. For the reaction with N2O, it is possible to produce significant odd-nitrogen in the lower stratosphere only if the oxidation yield is at least 5-10%. However, one then gets a surplus of odd-nitrogen in the upper stratosphere unless one makes the additional assumption that the production of O2(b1SIGMA(g)) from O(1D) quenching is small. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP SISKIND, DE (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,CODE 7641,WASHINGTON,DC 20375, USA. RI Mlynczak, Martin/K-3396-2012 NR 13 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 8 PY 1993 VL 20 IS 19 BP 2047 EP 2050 DI 10.1029/93GL02471 PG 4 WC Geosciences, Multidisciplinary SC Geology GA MB580 UT WOS:A1993MB58000010 ER PT J AU COHEN, SC AF COHEN, SC TI DOES RAPID CHANGE IN ICE LOADING MODULATE STRAIN ACCUMULATION AND RELEASE IN GLACIATED, TECTONICALLY ACTIVE REGIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHQUAKES AB There are major glaciated regions of the world that are also seismologically active. Changes in the thickness of ice due to glacier surges, advances, or retreats produce stress changes that may be a significant fraction of the tectonic stress accumulated during an earthquake cycle. The changes in ice loading can affect both the normal and shear stress on a fault with stresses being enhanced or reduced depending on glacier and fault geometry. The stress change has a nearly instantaneous elastic component and a longer time-scale viscoelastic component. Thus I propose that glacier motion can produce geodetically significant horizontal and vertical crustal displacements and can affect strain, strain rate, and the time of occurrence of earthquakes. In regions that are not tectonically active, rapid ice motion can also produce locally significant and geodetically detectable crustal deformations. RP COHEN, SC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,CODE 921,GREENBELT,MD 20771, USA. NR 23 TC 9 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 8 PY 1993 VL 20 IS 19 BP 2123 EP 2126 DI 10.1029/93GL01655 PG 4 WC Geosciences, Multidisciplinary SC Geology GA MB580 UT WOS:A1993MB58000029 ER PT J AU ALLEVATO, CE VINING, CB AF ALLEVATO, CE VINING, CB TI PHASE-DIAGRAM AND ELECTRICAL BEHAVIOR OF SILICON-RICH IRIDIUM SILICIDE COMPOUNDS SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article ID METAL SILICIDES AB The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis (DTA), metallography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only five distinct compositions: IrSi, Ir4Si5, Ir3Si4, Ir3Si5 and IrSi(almost-equal-to 3). The existence of Ir2Si3, IrSi7, and IrSi2 could not be confirmed in this study. DTA in conjunction with X-ray powder diffraction confirm polymorphism in IrSi(almost-equal-to 3), determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 80.5 +/- 1 at.% Si was observed between IrSi(almost-equal-to 3) and silicon. Both IrSi5 and Ir3Si4 exhibit distinct metallic behavior while Ir3Si5 is semiconducting. IrSi and IrSi(almost-equal-to 3) exhibit nearly temperature-independent electrical resistivities on the order of (5-10) X 10(-6) OMEGA m. RP ALLEVATO, CE (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 22 TC 25 Z9 25 U1 0 U2 8 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD OCT 8 PY 1993 VL 200 BP 99 EP 105 DI 10.1016/0925-8388(93)90478-6 PG 7 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA MC272 UT WOS:A1993MC27200019 ER PT J AU GURNETT, DA KURTH, WS ALLENDORF, SC POYNTER, RL AF GURNETT, DA KURTH, WS ALLENDORF, SC POYNTER, RL TI RADIO-EMISSION FROM THE HELIOPAUSE TRIGGERED BY AN INTERPLANETARY SHOCK SO SCIENCE LA English DT Article ID COSMIC-RAY INTENSITY; OUTER HELIOSPHERE; MASS EJECTIONS; RADIATION AB A strong heliospheric radio emission event has been detected by Voyagers 1 and 2 in the frequency range of 2 to 3 kilohertz. This event started in July 1992 and is believed to have been generated at or near the heliopause by an interplanetary shock that originated during a period of intense solar activity in late May and early June 1991. This shock produced large plasma disturbances and decreases in cosmic ray intensity at Earth, Pioneers 10 and 11, and Voyagers 1 and 2. The average propagation speed estimated from these effects is 600 to 800 kilometers per second. After correction for the expected decrease in the shock speed in the outer heliosphere, the distance to the heliopause is estimated to be between 116 and 177 astronomical units. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP GURNETT, DA (reprint author), UNIV IOWA, DEPT PHYS & ASTRON, IOWA CITY, IA 52242 USA. OI Kurth, William/0000-0002-5471-6202 NR 37 TC 160 Z9 160 U1 1 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD OCT 8 PY 1993 VL 262 IS 5131 BP 199 EP 203 DI 10.1126/science.262.5131.199 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MA665 UT WOS:A1993MA66500023 PM 17841865 ER PT J AU ACKERMAN, AS TOON, OB HOBBS, PV AF ACKERMAN, AS TOON, OB HOBBS, PV TI DISSIPATION OF MARINE STRATIFORM CLOUDS AND COLLAPSE OF THE MARINE BOUNDARY-LAYER DUE TO THE DEPLETION OF CLOUD CONDENSATION NUCLEI BY CLOUDS SO SCIENCE LA English DT Article ID MODEL; STRATOCUMULUS; ATMOSPHERES; INSTABILITY; SCATTERING; AEROSOLS AB When the production of cloud condensation nuclei in the stratocumulus-topped marine boundary layer is low enough, droplet collisions can reduce concentrations of cloud droplet numbers to extremely low values. At low droplet concentrations a cloud layer can become so optically thin that cloud-top radiative cooling cannot drive vertical mixing. Under these conditions, model simulations indicate that the stratocumulus-topped marine boundary layer collapses to a shallow fog layer. Through this mechanism, marine stratiform clouds may limit their own lifetimes. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ACKERMAN, AS (reprint author), UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195, USA. RI Ackerman, Andrew/D-4433-2012 OI Ackerman, Andrew/0000-0003-0254-6253 NR 28 TC 85 Z9 85 U1 0 U2 11 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 8 PY 1993 VL 262 IS 5131 BP 226 EP 229 DI 10.1126/science.262.5131.226 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MA665 UT WOS:A1993MA66500030 PM 17841869 ER PT J AU RANDEL, WJ GILLE, JC ROCHE, AE KUMER, JB MERGENTHALER, JL WATERS, JW FISHBEIN, EF LAHOZ, WA AF RANDEL, WJ GILLE, JC ROCHE, AE KUMER, JB MERGENTHALER, JL WATERS, JW FISHBEIN, EF LAHOZ, WA TI STRATOSPHERIC TRANSPORT FROM THE TROPICS TO MIDDLE LATITUDES BY PLANETARY-WAVE MIXING SO NATURE LA English DT Article ID POTENTIAL VORTICITY; NUMERICAL-MODEL; BREAKING; N2O AB TRANSPORT of air from the troposphere to the stratosphere takes place mainly in the tropics1. By studying satellite records of the dispersal of volcanic aerosols from tropical eruptions, Trepte and Hitchman2 concluded that there is a barrier inhibiting the transport of stratospheric air from the tropics to middle latitude, raising the question of how stratospheric material that has been transported from the troposphere is subsequently conveyed to higher latitudes. Here we present global maps of nitrous oxide and water mixing ratios obtained by the Upper Atmosphere Research Satellite. We see strong latitudinal gradients in these trace species, confirming the existence of a barrier to transport. But superimposed on this background structure we also see planetary-scale 'tongues' of tropical stratospheric air extending out into middle latitudes, and time sequences show irreversible mixing from the tropics into middle latitudes. Such episodes could be responsible for transporting significant quantities of stratospheric air across the tropical barrier. C1 LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. JET PROP LAB,PASADENA,CA 91109. UNIV EDINBURGH,DEPT METEOROL,EDINBURGH EH9 3JZ,MIDLOTHIAN,SCOTLAND. RP RANDEL, WJ (reprint author), NATL CTR ATMOSPHER RES,BOULDER,CO 80307, USA. RI Randel, William/K-3267-2016 OI Randel, William/0000-0002-5999-7162 NR 23 TC 129 Z9 129 U1 1 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 7 PY 1993 VL 365 IS 6446 BP 533 EP 535 DI 10.1038/365533a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA MA661 UT WOS:A1993MA66100048 ER PT J AU WARGO, MJ AF WARGO, MJ TI IMPROVED OPPORTUNITIES FOR THE INVESTIGATION OF CRYSTAL-GROWTH PHENOMENA ON SPACE STATION FREEDOM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43rd International-Astronautical-Federation Congress CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC SP INT ASTRONAUT FEDERAT AB Investigation of gravity as an experimental variable during crystal growth of electronic and photonic materials is expected to be significantly enhanced by the extended availability of the microgravity environment aboard Space Station Freedom. Experiments studying liquid/solid and vapor/solid phase transformations using the Crystal Growth Furnace were conducted during the first of the U.S. Microgravity Laboratory series of Space Shuttle flights. The increased time available for experiments on Space Station coupled with the quiescent environment expected during the ground-tended phase will permit scientists to conduct experiments which are not possible at present. These include studies which are both comprehensive and require processing times which are in excess of that available on today's carriers. RP WARGO, MJ (reprint author), NASA HEADQUARTERS,OFF SPACE SCI & APPLICAT,DIV MICROGRAV SCI & APPLICAT,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT-NOV PY 1993 VL 29 IS 10-11 BP 833 EP 839 DI 10.1016/0094-5765(93)90165-S PG 7 WC Engineering, Aerospace SC Engineering GA ML135 UT WOS:A1993ML13500014 ER PT J AU KENNEFICK, CM AF KENNEFICK, CM TI OFF-AXIS LOADING OF SILICON-CARBIDE FIBERS IN A TITANIUM ALUMINIDE MATRIX SO ACTA METALLURGICA ET MATERIALIA LA English DT Article ID EXPLORE INTERFACIAL MECHANICS; MONOFILAMENT-REINFORCED TI; INDENTATION METHOD; CERAMIC COMPOSITES; RESIDUAL-STRESSES; FRACTURE ENERGY; STRENGTH; GLASS AB Silicon carbide SCS-6 fibers in a Ti24Al + 11Nb matrix were subjected to off axis loading in a ''thin-slice'' pushout test, resulting in various combinations of shear, radial compression, and tension along the fibers as a function of orientation angle. The load necessary for debonding decreased as the orientation angle increased, whereas the average frictional sliding stress after 60 s of sliding remained relatively constant for orientation angles less than 30 deg. Analyses of the specimen bending stresses and of the contact stresses by finite element modelling and thin plate theory are presented. RP KENNEFICK, CM (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 30 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-7151 J9 ACTA METALL MATER JI Acta Metall. Mater. PD OCT PY 1993 VL 41 IS 10 BP 3055 EP 3063 DI 10.1016/0956-7151(93)90118-C PG 9 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA LV724 UT WOS:A1993LV72400025 ER PT J AU HUBA, JD BERNHARDT, PA FEDDER, JA LYON, JG MITCHELL, HG AF HUBA, JD BERNHARDT, PA FEDDER, JA LYON, JG MITCHELL, HG TI MODELING THE PLASMA DYNAMICS OF THE CRRES G-9 AND G-10 BARIUM RELEASES SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID ION CLOUDS; MAGNETOSPHERE; IONOSPHERE; MOTION; MODES AB The CRRES mission involved a number of chemical releases in the ionosphere and magnetosphere to study a multitude of scientific phenomena. In this paper two releases are discussed: the G-9 release and the G-10 release. One of the primary purposes of the G-9 release was to study the transverse motion (i.e., 'skidding') of plasma across magnetic field lines. Analysis of optical images indicates that the barium cloud 'skidded' approximately 9 - 15 km. The simulation study is based upon a 2D electrostatic code which incorporates a time-dependent model of coupling to the background ionosphere. The simulation results indicate the densest portion of the barium cloud 'skids' approximately 15 km within the first 3 sec following the release, consistent with observations. The G-10 release was designed to study, in part, the formation and evolution of a diamagnetic cavity, as well as the stability of the barium plasma. The simulation results are obtained from a 2D Hall MHD code and show that (1) the plasma and field structure at time t less-than-or-equal-to 22 sec, and develop scale sizes approximately 10 - 15 km, and (2) the structuring of the plasma allows 'blobs' of plasma to drift across the magnetic field. These results are consistent with optical and in situ magnetometer measurements. C1 UNIV IOWA, IOWA CITY, IA 52242 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP USN, RES LAB, DIV PLASMA PHYS, WASHINGTON, DC 20375 USA. NR 27 TC 1 Z9 1 U1 1 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES JI Adv. Space Res. PD OCT PY 1993 VL 13 IS 10 BP 45 EP 54 PG 10 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA ML874 UT WOS:A1993ML87400006 ER PT J AU MOUNT, FE AF MOUNT, FE TI THE HUMAN FACTOR IN AEROSPACE MAINTENANCE SO AEROSPACE AMERICA LA English DT Article RP MOUNT, FE (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV FLIGHT CREW SUPPORT,CREW INTERFACE ANAL SECT,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD OCT PY 1993 VL 31 IS 10 BP 26 EP & PG 0 WC Engineering, Aerospace SC Engineering GA MA616 UT WOS:A1993MA61600008 ER PT J AU OLSEN, ME SEEGMILLER, HL AF OLSEN, ME SEEGMILLER, HL TI LOW-ASPECT-RATIO WING CODE VALIDATION EXPERIMENT SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 30TH AEROSPACE SCIENCES MEETING CY JAN 06-09, 1992 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB A code validation experiment for transonic flow is described. The experimental geometry is a low aspect ratio wing, tested in a solid wall wind tunnel. Inflow conditions were measured far enough upstream of the model to allow simple specification. Experimental uncertainties are given for pressure, temperature, velocity, and position measurements, as well as bounds on model deflections and transition location. Cursory comparison with simple computational models provides a baseline of flow conditions that should be readily modeled as well as denotes those cases that will be more challenging. The data include a wide range of alpha, M(infinity), and two Re(c)r. The Reynolds numbers reached in this experiment reproduce those experienced by an aircraft with a 5-m root chord, flying at 14-16 km, from Mach 0.6 to 0.8. The angle-of-attack range of the experiment extends into the regime of leading-edge separation (0 deg less-than-or-equal-to alpha less-than-or-equal-to 8 deg). RP OLSEN, ME (reprint author), NASA,AMES RES CTR,MODELLING & VALIDAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 11 TC 3 Z9 3 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1744 EP 1752 DI 10.2514/3.49105 PG 9 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300002 ER PT J AU PALMER, G VENKATAPATHY, E AF PALMER, G VENKATAPATHY, E TI EFFECTIVE TREATMENT OF THE SINGULAR LINE BOUNDARY-PROBLEM FOR 3-DIMENSIONAL GRIDS SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 30TH AEROSPACE SCIENCES MEETING CY JAN 06-09, 1992 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB THREE-DIMENSIONAL grids of rotation contain a singular line where the radial grid planes meet. When the flow equations are transformed into generalized coordinates, a mathematical singularity is introduced into the governing equations. Specifically, the grid Jacobian J becomes infinite along the singular line. This can introduce nonphysical perturbations in the flow solution, particularly if a finite-difference solution algorithm is used. A number of recent publications1-5 have discussed problems associated with the singular line. This paper presents a method for eliminating the axis singularity. The governing equations are reformulated using a redefined grid Jacobian that can be evaluated at the singular line. This allows a finite-difference algorithm to compute a smooth, continuous solution in the region of the singular line. C1 ELORET INST,MT VIEW,CA 94043. RP PALMER, G (reprint author), NASA,AMES RES CTR,AEROTHERMODYNAM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1757 EP 1758 DI 10.2514/3.11845 PG 2 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300004 ER PT J AU ROSENFELD, M KWAK, D AF ROSENFELD, M KWAK, D TI MULTIGRID ACCELERATION OF A FRACTIONAL-STEP SOLVER IN GENERALIZED CURVILINEAR COORDINATE SYSTEMS SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT 30TH AEROSPACE SCIENCES MEETING CY JAN 06-09, 1992 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB A fractional-step (FS) solver of the three-dimensional time-dependent incompressible Navier-Stokes equations in generalized curvilinear coordinate systems, previously developed by the present authors, has been significantly enhanced by accelerating the Poisson solver with multigrid (MG) procedures. The most CPU time-consuming part of fractional-step methods is the solution of a discrete Poisson-like equation with Neumann-type boundary conditions formulated to satisfy the continuity equation. Usually, more than 80% of the total computational time of FS methods is consumed by the iterative solution of the Poisson equation. In the present study, multigrid techniques have been employed for accelerating the convergence rate of the Poisson solver in nonorthogonal coordinate systems. Various MG strategies have been tested in numerous numerical experiments. The total computational time required for solving the Poisson equation was reduced by an order of magnitude, whereas the overall computational time of the flow solver was reduced by a factor of 3-4. The MG Poisson solver consumes less than 25% of the total CPU time. The computational work has been found to be of order O(N), where N is the total number of mesh points, whereas the CPU time on a vector computer (CRAY Y-MP) is of O(N0.75). Consequently, the present method is a viable alternative for solving complex flowfields with a very large number of mesh points. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ROSENFELD, M (reprint author), TEL AVIV UNIV,FAC ENGN,DEPT FLUID DYNAM,IL-69978 TEL AVIV,ISRAEL. NR 12 TC 13 Z9 13 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1792 EP 1800 DI 10.2514/3.11851 PG 9 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300010 ER PT J AU HARVEY, AD ACHARYA, S LAWRENCE, SL AF HARVEY, AD ACHARYA, S LAWRENCE, SL TI SPACE-MARCHING CALCULATIONS ABOUT HYPERSONIC CONFIGURATIONS USING A SOLUTION-ADAPTIVE MESH ALGORITHM SO AIAA JOURNAL LA English DT Article ID NAVIER-STOKES EQUATIONS; GRID PROCEDURE AB A solution-adaptive marching algorithm is developed and applied to a three-dimensional parabolized Navier-Stokes equation solver. The resulting algorithm obtains accurate solutions by using a spatial-marching/adaptive-grid procedure. The adaptation step redistributes grid points line by line in both crossflow directions, with grid point motion controlled by forces analogous to tensional and torsional spring forces with the tensional force proportional to the error measure or weighting functions. The solution-adaptive marching procedure is applied to the hypersonic flow about two generic aircraft configurations. The first of these is an all-body-type geometry with elliptical cross sections and is studied at angles of attack of 0, 5, and 15 deg. The second geometry is a generic blended-wing-body design. Results are presented that demonstrate the improvements in flowfield resolution obtainable with the solution-adaptive marching procedure over conventional fixed grid techniques. Computed pitot pressure profiles obtained using the solution-adaptive algorithm show improved agreement with experimental data compared to predictions obtained using a fixed grid. C1 LOUISIANA STATE UNIV,DEPT MECH ENGN,BATON ROUGE,LA 70803. NASA,AMES RES CTR,APPL COMPUTAT FLUIDS BRANCH,MOFFETT FIELD,CA 94035. NR 27 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1809 EP 1818 DI 10.2514/3.11853 PG 10 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300012 ER PT J AU SHIH, TIP RIMLINGER, MJ CHYU, WJ AF SHIH, TIP RIMLINGER, MJ CHYU, WJ TI 3-DIMENSIONAL SHOCK-WAVE BOUNDARY-LAYER INTERACTIONS WITH BLEED SO AIAA JOURNAL LA English DT Article ID DIFFERENCE AB Computations were performed to investigate the physics of three-dimensional, shock-wave/boundary-layer interactions on a flat plate in which fluid in the boundary layer was bled through a circular hole into a plenum to control shock-wave induced flow separation. This study revealed two underlying mechanisms by which bleed holes can control shock-wave/boundary-layer interactions. It also showed how bleed-hole placement relative to where the incident shock wave impinges affects upstream, spanwise, and downstream influence lengths. This study is based on the ensemble-averaged, full compressible Navier-Stokes equations closed by the Baldwin-Lomax turbulence model. Solutions to these equations were obtained by an implicit, partially split, two-factored method with flux-vector splitting on a chimera overlapping grid. C1 NASA,AMES RES CTR,APPL COMPUTAT FLUIDS BRANCH,MOFFETT FIELD,CA 94035. RP SHIH, TIP (reprint author), CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213, USA. NR 11 TC 18 Z9 18 U1 1 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1819 EP 1826 DI 10.2514/3.11854 PG 8 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300013 ER PT J AU RIBNER, HS AF RIBNER, HS TI THRUST IMPARTED TO AN AIRFOIL BY PASSAGE THROUGH A SINUSOIDAL UPWASH FIELD SO AIAA JOURNAL LA English DT Article AB The passage of an airfoil through a sinusoidal upwash field (Sears, 1941) is analyzed further to yield the wavelength-dependent thrust: the ''Katzmayr effect.'' The shed vorticity is shown to induce an opposed flow that reduces the kinetic energy: the decrement is found to match exactly the work done by the thrust. The ''Sears function for thrust'' is then applied to passage through turbulence described by a one-dimensional power spectrum. Finally, some acoustical implications of relaxing the postulated incompressibility are briefly discussed. It is argued that the radiated dipole noise, like the thrust, draws its energy from the flowfield. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP RIBNER, HS (reprint author), UNIV TORONTO,INST AEROSP STUDIES,4925 DUFFERIN ST,DOWNSVIEW M3H 5T6,ON,CANADA. NR 25 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1863 EP 1868 DI 10.2514/3.11860 PG 6 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300019 ER PT J AU LEVINEWEST, MB SALAMA, MA AF LEVINEWEST, MB SALAMA, MA TI MODE LOCALIZATION EXPERIMENTS ON A RIBBED ANTENNA SO AIAA JOURNAL LA English DT Article AB In this paper, the mode localization (ML) phenomenon is investigated experimentally and analytically to determine the influence of its parameters. For this purpose, a full-scale 12-rib loosely coupled antenna testbed with small imperfections is dynamically tested for various levels of inter-rib coupling stiffness and excitation force. The experimental results are described herein. Using a simplified numerical model of the structure, a sensitivity analysis of the modal behavior is also performed. The numerical and experimental results are shown to agree remarkably well, thereby providing conclusive validation of the ML phenomenon on a testbed having the dynamic characteristics of space structures. RP LEVINEWEST, MB (reprint author), CALTECH,JET PROPULS LAB,4800 OAK GROVE DR,MS 157316,PASADENA,CA 91125, USA. NR 12 TC 10 Z9 13 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1929 EP 1937 DI 10.2514/3.49111 PG 9 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300028 ER PT J AU NOOR, AK KIM, YH PETERS, JM AF NOOR, AK KIM, YH PETERS, JM TI STRAIN-ENERGY OF THERMALLY STRESSED MULTILAYER PANELS AND ITS SENSITIVITY COEFFICIENTS SO AIAA JOURNAL LA English DT Article AB A study is made of the effect of lamination and material parameters of thermally stressed multilayer composite panels on the strain energy and its sensitivity coefficients obtained by the three-dimensional thermoelasticity model. The sensitivity coefficients measure the sensitivity of the strain energy to variations in the different lamination and material parameters of the panel. The strain energy and sensitivity coefficients obtained by the three-dimensional model are used as the basis for assessing the accuracy of the corresponding quantities obtained by two-dimensional first-order shear deformation theory. Numerical results are presented for antisymmetrically laminated angle-ply panels subjected to linear temperature variation through the thickness. The numerical results demonstrate the accuracy of the strain energy and its sensitivity coefficients obtained by the first-order shear deformation theory, for the range of parameters considered, and the importance of the particular terms in the strain energy, which vanish for single-layer panels. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP NOOR, AK (reprint author), UNIV VIRGINIA,CTR COMPUTAT STRUCT TECHNOL,CHARLOTTESVILLE,VA 22903, USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1993 VL 31 IS 10 BP 1946 EP 1952 DI 10.2514/3.11871 PG 7 WC Engineering, Aerospace SC Engineering GA MA623 UT WOS:A1993MA62300030 ER PT J AU KASSEMI, M GOKOGLU, SA PANZARELLA, CH VEITCH, LC AF KASSEMI, M GOKOGLU, SA PANZARELLA, CH VEITCH, LC TI A COMBINED HEAT-TRANSFER ANALYSIS OF A SINGLE-FIBER CVD REACTOR SO AICHE JOURNAL LA English DT Article AB A combined-conjugated heat-transfer and fluid-flow analysis is presented for coating fibers by CVD in a vertical cylindrical quartz reactor. The numerical model focuses on radiation and natural con vection. Three case studies are performed, and the wall temperature predictions are compared to experimental measurements. In the first case, the flowing gas is hydrogen, and conduction is more important than both radiation and convection, in which case measured and predicted wall temperatures agree excellently. In the second, hydrogen is replaced by argon, thus making radiation heat transfer more important than the previous situation. Three radiation models with increasing degrees of sophistication are compared: an approximate nongray model (no wavelength dependence of emissivity), an approximate semigray model, and a rigorous semigray model with view factor calculations. Comparison with experiments suggest that a semigray radiative analysis is needed for correct determination of wall temperatures. The third involves argon at a lower flow rate, where natural convection effects are more pronounced. Checking the validity of the Boussinesq approximation by incorporating the explicit dependence of density on temperature in the model shows a slight difference between the velocity fields predicted using the Boussinesq approximation and those obtained using the explicit dependence of density on temperature. However, there is negligible difference between the temperature fields predicted in the two cases. RP KASSEMI, M (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 3 Z9 3 U1 0 U2 1 PU AMER INST CHEMICAL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0001-1541 J9 AICHE J JI AICHE J. PD OCT PY 1993 VL 39 IS 10 BP 1687 EP 1696 DI 10.1002/aic.690391012 PG 10 WC Engineering, Chemical SC Engineering GA MA180 UT WOS:A1993MA18000011 ER PT J AU SEYMOUR, RS HARGENS, AR PEDLEY, TJ AF SEYMOUR, RS HARGENS, AR PEDLEY, TJ TI THE HEART WORKS AGAINST GRAVITY SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Review DE CIRCULATION; BLOOD FLOW; SIPHON; COLLAPSIBLE VESSELS; BLOOD PRESSURE; TISSUE PRESSURE ID BLOOD-FLOW; GIRAFFE; CIRCULATION; HEMODYNAMICS AB The circulatory systems of vertebrate animals are closed, and blood leaves and returns to the heart at the same level. It is often concluded, therefore, that the heart works only against the viscous resistance of the system, not against gravity, even in vascular loops above the heart in which the siphon principle operates. However, we argue that the siphon principle does not assist blood flow in superior vascular loops if any of the descending vasculature is collapsible. If central arterial blood pressure is insufficient to support a blood column between the heart and the head, blood flow ceases because of vascular collapse. Furthermore, the siphon principle does not assist the heart even when a continuous stream of blood is flowing in a superior loop. The potential energy gained by blood as it is pumped to the head is lost to friction in partially collapsed descending vessels and thus is not regained. Application of the Poiseuille equation to flow in collapsible vessels is limited; resistance depends on flow rate in partially collapsed vessels with no transmural pressure difference, but flow rate is independent of resistance. Thus the pressure developed by the heart to establish a given flow rate is independent of the resistance occurring in the partially collapsed vessels. The pressure depends only on the height of the blood column and the resistance in the noncollapsed parts of the system. Simple laboratory models, involving water flow in collapsible tubing, dispel the idea that the siphon principle facilitates blood flow and suggest that previously published results may have been affected by experimental artifact. C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV LEEDS,DEPT APPL MATH STUDIES,LEEDS LS2 9JT,W YORKSHIRE,ENGLAND. RP SEYMOUR, RS (reprint author), UNIV ADELAIDE,DEPT ZOOL,ADELAIDE,SA 5005,AUSTRALIA. RI Seymour, Roger/C-3469-2009 NR 28 TC 39 Z9 39 U1 1 U2 12 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD OCT PY 1993 VL 265 IS 4 BP R715 EP R720 PN 2 PG 6 WC Physiology SC Physiology GA ME481 UT WOS:A1993ME48100060 PM 8238437 ER PT J AU PEREZ, JD LIU, C LAWSON, L MOORE, TE CHAPPELL, CR AF PEREZ, JD LIU, C LAWSON, L MOORE, TE CHAPPELL, CR TI A NEW TECHNIQUE FOR DECONVOLUTION OF DATA FROM INSTRUMENTS THAT MAKE INTEGRAL MEASUREMENTS, EG RIMS ON DE-1 SO ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES LA English DT Article AB A general method for deconvolving an unknown function from integral measurements is described and applied to data from the instrument RIMS aboard the spacecraft DE-1. The principal features of the method are: 1. it uses objective criteria based upon fundamental statistical principles, i.e. Bayesian statistics; 2. it provides for insertion of prior knowledge in a non-prejudicial, explicit manner through the choice of breakpoints that determine the bicubic spline expansion functions; 3. it prevents random fluctuations from controlling the fit to the data through the use of singular value decomposition and the elimination of small singular values; 4. it guards against the introduction of spurious features into the result by including a penalty function and using the principle of generalized cross validation. Illustrative examples from RIMS data for H+ and O+ show that the method provides enhanced accuracy and detail in deconvolving the ion phase space density. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP PEREZ, JD (reprint author), AUBURN UNIV,DEPT PHYS,AUBURN,AL 36849, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 15 TC 3 Z9 3 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys.-Atmos. Hydrospheres Space Sci. PD OCT PY 1993 VL 11 IS 10 BP 889 EP 896 PG 8 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA MC072 UT WOS:A1993MC07200002 ER PT J AU DEGANI, A ASFOUR, SS WALY, SM KOSHY, JG AF DEGANI, A ASFOUR, SS WALY, SM KOSHY, JG TI A COMPARATIVE-STUDY OF 2 SHOVEL DESIGNS SO APPLIED ERGONOMICS LA English DT Article DE SHOVELS; HAND TOOLS; MUSCULOSKELETAL DISORDERS; FIELD STUDY; SURFACE ELECTROMYOGRAPHY ID ERGONOMICS AB In the present study a modified shovel design with two perpendicular shafts is presented. This modified, two-shaft shovel was compared with a regular shovel. The modified shovel was evaluated and tested in a controlled laboratory environment using surface electromyography recorded from the lumbar paraspinal muscles. The new shovel design was also tested in a field study using ratings of perceived exertion. The results indicate that there was a significant reduction in EMG values of the lumbar paraspinal muscles and a consistent reduction in perceived exertion ratings while the modified shovel was being used for removing dirt in digging trenches up to 90 cm in depth. C1 UNIV MIAMI,DEPT IND ENGN,CORAL GABLES,FL 33124. RP DEGANI, A (reprint author), NASA,AMES RES CTR,RES CTR,MS 262-4,MOFFETT FIELD,CA 94035, USA. NR 16 TC 6 Z9 6 U1 2 U2 4 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0003-6870 J9 APPL ERGON JI Appl. Ergon. PD OCT PY 1993 VL 24 IS 5 BP 306 EP 312 DI 10.1016/0003-6870(93)90069-L PG 7 WC Engineering, Industrial; Ergonomics; Psychology, Applied SC Engineering; Psychology GA MD233 UT WOS:A1993MD23300001 PM 15676927 ER PT J AU BAYARD, DS AF BAYARD, DS TI STATISTICAL PLANT SET ESTIMATION USING SCHROEDER-PHASED MULTISINUSOIDAL INPUT-DESIGN SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article ID FREQUENCY-DOMAIN IDENTIFICATION AB In this paper, a frequency domain method is developed for plant set estimation. The estimation of a plant ''set'' rather than a point estimate is required to support many methods of modem robust control design. The approach here is based on using a Schroeder-phased multisinusoid input design which has the special property of placing input energy only at the discrete frequency points used in the computation. A detailed analysis of the statistical properties of the frequency domain estimator is given, leading to exact expressions for the probability distribution of the estimation error and many important properties. it is shown that for any nominal parametric plant estimate, one can use these results to construct an overbound on the additive uncertainty to any prescribed statistical confidence. The ''soft'' bound thus obtained can be used to replace ''hard'' bounds presently used in many robust control analysis and synthesis methods. RP BAYARD, DS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 23 Z9 23 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD OCT PY 1993 VL 58 IS 2-3 BP 169 EP 198 DI 10.1016/0096-3003(93)90135-2 PG 30 WC Mathematics, Applied SC Mathematics GA MA044 UT WOS:A1993MA04400003 ER PT J AU EDLOU, SM SMAJKIEWICZ, A ALJUMAILY, GA AF EDLOU, SM SMAJKIEWICZ, A ALJUMAILY, GA TI OPTICAL-PROPERTIES AND ENVIRONMENTAL STABILITY OF OXIDE COATINGS DEPOSITED BY REACTIVE SPUTTERING SO APPLIED OPTICS LA English DT Article DE THIN FILMS; SPUTTERING; INTERFERENCE; OPTICAL COATINGS; OPTICAL FILTERS; MATERIALS; METAL OXIDES; OPTICAL PROPERTIES ID THIN-FILMS AB Refractory metal-oxide coatings are deposited by reactive dc magnetron sputtering in an oxygen environment. The optical constants and the environmental stability of silicon oxide, aluminium oxide, hafnium oxide, zirconium oxide, tantalum oxide, titanium oxide, and a blend of hafnium oxide with silicon oxide are investigated. Properties of both single-layer and multilayer interference filters are examined. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP EDLOU, SM (reprint author), BARR ASSOCIATES INC, 2 LYBERTY WAY, WESTFORD, MA 01886 USA. NR 13 TC 91 Z9 92 U1 3 U2 19 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 1 PY 1993 VL 32 IS 28 BP 5601 EP 5605 PG 5 WC Optics SC Optics GA LZ497 UT WOS:A1993LZ49700026 PM 20856375 ER PT J AU SUBRAMANYAM, G KAPOOR, VJ CHOREY, CM BHASIN, KB AF SUBRAMANYAM, G KAPOOR, VJ CHOREY, CM BHASIN, KB TI TICABACUO HIGH-TC SUPERCONDUCTING MICROSTRIP RING RESONATORS DESIGNED FOR 12 GHZ SO APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT WORLD CONGRESS ON SUPERCONDUCTIVITY CY SEP 15-18, 1992 CL MUNICH, GERMANY ID THIN-FILMS AB Microwave properties of sputtered Tl-Ca-Ba-Cu-O thin films were investigated by designing, fabricating and testing microstrip ring resonators. Ring resonators designed for 12 GHz fundamental resonance frequency, were fabricated and tested. From the unloaded Q values for the resonators, the surface resistance was calculated by separating the conductor losses from the total losses. The penetration depth was obtained from the temperature dependence of resonance frequency, assuming that the shift in resonance frequency is mainly due to the temperature dependence of penetration depth. The effective surface resistance at 12 GHz and 77 K was determined to be between 1.5 and 2.75 mOMEGA, almost an order lower than Cu at the same temperature and frequency. The effective penetration depth at 0-degrees-K is approximately 7000 angstrom. C1 SVERDRUP TECHNOL INC,CLEVELAND,OH 43435. NASA,LEWIS RES CTR,CLEVELAND,OH 43435. RP SUBRAMANYAM, G (reprint author), UNIV CINCINNATI,DEPT ELECT & COMP ENGN,MICROWAVE ELECTR LAB,CINCINNATI,OH 45221, USA. NR 17 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD OCT-DEC PY 1993 VL 1 IS 10-12 BP 1605 EP 1614 DI 10.1016/0964-1807(93)90308-O PG 10 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA LR723 UT WOS:A1993LR72300012 ER PT J AU PARKER, JW GARMANY, CD AF PARKER, JW GARMANY, CD TI THE OB ASSOCIATIONS OF 30-DORADUS IN THE LARGE MAGELLANIC CLOUD .2. STELLAR CONTENT AND INITIAL MASS FUNCTION SO ASTRONOMICAL JOURNAL LA English DT Article ID WOLF-RAYET STARS; 30 DORADUS; SPECTRAL CLASSIFICATION; NEARBY GALAXIES; EVOLUTION; ULTRAVIOLET; CLUSTERS; EXTINCTION; COLORS; REGION AB From photometric and spectroscopic observations of the stars in 30 Doradus we determine the effective stellar temperatures and bolometric magnitudes. We construct the theoretical H-R diagram, and using stellar evolution models we then bin the stars by mass to obtain the initial mass function (IMF). The IMF shows marked curvature; it flattens out at lower masses, even for those masses above which the photometry is complete. Best estimates of the IMF slope yield values of GAMMA - 1.5 +/- 0.2 for M greater-than-or-similar-to 12 M., where the Salpeter slope is GAMMA = -1.35. However, there are indications that different regions of 30 Doradus have different IMF slopes, perhaps as the result of sequential star formation effects. C1 UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. RP PARKER, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,MAIL CODE 681,GREENBELT,MD 20771, USA. NR 62 TC 81 Z9 81 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1993 VL 106 IS 4 BP 1471 EP 1483 DI 10.1086/116740 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LZ183 UT WOS:A1993LZ18300017 ER PT J AU KENYON, SJ MIKOLAJEWSKA, J MIKOLAJEWSKI, M POLIDAN, RS SLOVAK, MH AF KENYON, SJ MIKOLAJEWSKA, J MIKOLAJEWSKI, M POLIDAN, RS SLOVAK, MH TI EVOLUTION OF THE SYMBIOTIC BINARY-SYSTEM AG PEGASI - THE SLOWEST CLASSICAL NOVA ERUPTION EVER RECORDED SO ASTRONOMICAL JOURNAL LA English DT Review ID ACCRETING WHITE-DWARFS; EMISSION-LINE SPECTRUM; HYDROGEN SHELL FLASHES; MAIN-SEQUENCE STARS; WOLF-RAYET STARS; MASS-LOSS; INFRARED-SPECTROSCOPY; COOL COMPONENTS; INHOMOGENEOUS-MEDIUM; STELLAR EVOLUTION AB We present an analysis of new and existing photometric and spectroscopic observations of the ongoing eruption in the symbiotic star AG Pegasi. These observations show that this binary has evolved considerably since the turn of the century. In particular, recent dramatic changes in both the UV continuum and the wind from the hot component allow a more detailed analysis than in previous papers. AG Peg is composed of a normal M3 giant (M(g) approximately 2.5M. and a hot, compact star (M(h) approximately 0.6M.) embedded in a dense, ionized nebula. The hot component powers the activity observed in this system, including a dense wind (v(r) approximately 1000 km s-1; M approximately 10(-6) M. yr-1) and a photoionized region within the outer atmosphere of the red giant. The hot component contracted in radius at roughly constant luminosity from 1850 to 1985. Its bolometric luminosity declined by a factor of approximately 4 during the past 5 yr, and it may now be evolving along the constant radius portion of the white dwarf cooling curve. Both the mass loss rate from the hot component and the emission activity decreased in step with the hot component's total luminosity, while photospheric radiation from the red giant companion remained essentially constant. C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. NICOLAUS COPERNICUS ASTRON CTR,PL-00716 WARSAW,POLAND. NICOLAUS COPERNICUS UNIV,INST ASTRON,PL-87100 TORUN,POLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. OI Kenyon, Scott/0000-0003-0214-609X NR 177 TC 72 Z9 72 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1993 VL 106 IS 4 BP 1573 EP 1598 DI 10.1086/116749 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LZ183 UT WOS:A1993LZ18300026 ER PT J AU SIMON, T DRAKE, SA AF SIMON, T DRAKE, SA TI THE CORONAE OF MAIN-SEQUENCE A-STARS SO ASTRONOMICAL JOURNAL LA English DT Article ID CHROMOSPHERIC ACTIVITY; CONVECTION ZONES; EVOLUTION; ROTATION; ONSET AB We have undertaken a deep x-ray imaging survey of single, normal, mid-to-late-A- and early-F-type main-sequence stars using the ROSAT PSPC. Eight of the nine such stars in our fields went undetected at very weak emission levels, with upper limits on the normalized x-ray flux in each case of better than log R(x) < - 6.3. The only A-F star we detected was 83 Tau, a member of the Hyades that we now belatedly recognize as a possible binary star, whose emission may come from an unidentified companion. Our observations reveal a systematic decline in coronal x-ray brightness with increasing effective temperature, which we attribute to the presence of strong coronal winds. These new results add further weight to earlier suggestions that single A and early-F stars in the field and in nearby older open clusters generally have intrinsically faint coronae. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS SCI ARCHIVE RES CTR,GREENBELT,MD 20771. RP SIMON, T (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. NR 22 TC 13 Z9 13 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1993 VL 106 IS 4 BP 1660 EP 1663 DI 10.1086/116755 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LZ183 UT WOS:A1993LZ18300032 ER PT J AU GOEBEL, JH AF GOEBEL, JH TI SIS2 IN CIRCUMSTELLAR SHELLS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, INDIVIDUAL, ALPHA-SI-X HYA-SAO-197549 CIRCUMSTELLAR MATTER; ISM, DUST, EXTINCTION ID PROTO-PLANETARY NEBULAE; CARBON-RICH STARS; INFRARED-SPECTRUM; EMISSION FEATURE; CHEMISTRY; GLASSES; SULFUR AB Solid state SiS2 is proposed as the material responsible for the recently discovered 21 mum emission feature that is observed in the carbon-rich circumstellar shells of certain protoplanetary nebulae. Sulfurized SiC, or SiS2 mantles on grains of either SiC or a:C-H are discussed as possible forms for which no spectroscopic laboratory observations yet exist. The identification with a relatively minor species and required special abundance ratios are consistent with the low incidence rate that the 21 mum feature presents in the population of carbon rich objects. It is also consistent with the lack of a good correlation between the 21 mum feature and the other solid-state spectroscopic features that have been observed in protoplanetaries that would be expected if the feature arose from molecules composed of H, C, N, and O. SiS2 condensate is consistent with the circumstellar shell temperature range, T(CS) less than or similar to 150 K, at which the feature appears, and the available mass of SiS2, M(SiS2) congruent-to 5 10(-6)M., that is possible in the circumstellar shell. RP GOEBEL, JH (reprint author), NASA, AMES RES CTR, MAIL STOP 244-10, MOFFETT FIELD, CA 94035 USA. NR 34 TC 29 Z9 30 U1 0 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 1993 VL 278 IS 1 BP 226 EP 230 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD361 UT WOS:A1993MD36100028 ER PT J AU BOER, M PIZZICHINI, G HARTMANN, D HURLEY, K KOUVELIOTOU, C MOTCH, C AF BOER, M PIZZICHINI, G HARTMANN, D HURLEY, K KOUVELIOTOU, C MOTCH, C TI ROSAT-POINTED OBSERVATIONS OF 2 GAMMA-RAY BURST ERROR BOXES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GAMMA-RAYS, BURSTS; X-RAYS, GENERAL; STARS, NEUTRON ID NEUTRON-STAR MODELS; OPTICAL COUNTERPARTS; ABSORPTION FEATURES; CONSTRAINTS; SPECTRA; ORIGIN AB We present ROSAT observations of two gamma-ray burst error boxes and of one possible optical transient source. No point sources were detected and a comparison is made with previous observations of the same objects (Boer et al. 1988, 1991). We interpret the data in the context of gamma-ray burst models that invoke galactic neutron stars. Although recent BATSE observations (Meegan et al. 1992) effectively rule out a galactic disk origin for the majority of gamma-ray bursts, it cannot be excluded at present that a fraction of them originates from nearby neutron stars. It is these sources that are constrained by the ROSAT data presented here. C1 MAX PLANCK INST EXTRATERR PHYS, GARCHING, GERMANY. CNR, IST TESRE, I-40126 BOLOGNA, ITALY. CLEMSON UNIV, DEPT PHYS & ASTRON, CLEMSON, SC 29634 USA. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. UNIV STRASBOURG, OBSERV STRASBOURG, F-67000 STRASBOURG, FRANCE. RP BOER, M (reprint author), CTR ETUD SPATIALE RAYONNEMENTS, CNRS, UPS, BP 4346, F-31029 TOULOUSE, FRANCE. NR 42 TC 10 Z9 10 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 1993 VL 277 IS 2 BP 503 EP 509 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA601 UT WOS:A1993MA60100020 ER PT J AU DOMINIK, C SEDLMAYR, E GAIL, HP AF DOMINIK, C SEDLMAYR, E GAIL, HP TI DUST FORMATION IN STELLAR WINDS .6. MOMENT EQUATIONS FOR THE FORMATION OF HETEROGENEOUS AND CORE-MANTLE GRAINS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE DUST; INTERPLANETARY MEDIUM; STARS, CIRCUMSTELLAR MATTER; STARS, LATE TYPE ID DRIVEN WINDS; C-STARS; CONDENSATION; GROWTH; NUCLEATION AB The grains found in interstellar and interplanetary space are well known to often be of amorphous heterogeneous structure. Nevertheless a quantitative theory for the description of the growth of these particles is still missing. We show that the well known moment method for the calculation of dust grain formation can be generalized in order to account also for the formation of heterogeneous dust grains. These include both grains consisting of a mixture of different molecules and the so-called core-mantle grains where different materials condense in layers on the grains. Furthermore we construct a special equilibrium state that allows for the calculation of equilibrium densities of various molecules above composite grain materials. The new equations are applied to dust condensation in the wind of an M giant star. C1 TECH UNIV BERLIN, INST ASTRON & ASTROPHYS, D-10623 BERLIN, GERMANY. UNIV HEIDELBERG, INST THEORET ASTROPHYS, D-69120 HEIDELBERG, GERMANY. RP DOMINIK, C (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 24 TC 47 Z9 47 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 1993 VL 277 IS 2 BP 578 EP 594 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA601 UT WOS:A1993MA60100028 ER PT J AU KIRSHNER, RP JEFFERY, DJ LEIBUNDGUT, B CHALLIS, PM SONNEBORN, G PHILLIPS, MM SUNTZEFF, NB SMITH, RC WINKLER, PF WINGE, C HAMUY, M HUNTER, DA ROTH, KC BLADES, JC BRANCH, D CHEVALIER, RA FRANSSON, C PANAGIA, N WAGONER, RV WHEELER, JC HARKNESS, RP AF KIRSHNER, RP JEFFERY, DJ LEIBUNDGUT, B CHALLIS, PM SONNEBORN, G PHILLIPS, MM SUNTZEFF, NB SMITH, RC WINKLER, PF WINGE, C HAMUY, M HUNTER, DA ROTH, KC BLADES, JC BRANCH, D CHEVALIER, RA FRANSSON, C PANAGIA, N WAGONER, RV WHEELER, JC HARKNESS, RP TI SN-1992A - ULTRAVIOLET AND OPTICAL STUDIES BASED ON HST, IUE, AND CTIO OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-1380); SUPERNOVAE, INDIVIDUAL (SN-1992A); ULTRAVIOLET, STARS ID WHITE-DWARF MODELS; I SUPER-NOVA; SN-1987A POLARIMETRY; INTERSTELLAR LINES; SPECTRAL-LINES; MAXIMUM LIGHT; SPECTROPOLARIMETRY; POLARIZATION; NUCLEOSYNTHESIS; SPECTROSCOPY AB The Type Ia supernova SN 1992A in the S0 galaxy NGC 1380 was observed as a target of opportunity by the International Ultraviolet Explorer (IUE) and with great alacrity by the Hubble Space Telescope (HST). Here we present the HST and IUE spectra and photometry that we obtained, as well as optical spectra obtained at the Cerro Tololo Inter-American Observatory (CTIO). The HST Faint Object Spectrograph (FOS) spectra, from 5 and 45 days past maximum light, are the best UV spectra of a Type Ia supernova and reveal for the first time with good signal-to-noise ratio the Type Ia spectral region blueward of approximately 2650 angstrom. The UV photometry taken in the F175W, F275W, and F342W bands defined by the HST filters shows light curves that resemble the Type Ia template U light curve. Using data from SN 1992A and SN 1990N, we have constructed a Type Ia template light curve for the flux region near 2750 angstrom that is quite detailed from 14 days before maximum light to 22 days after maximum light and that extends to 77 days after maximum light. This light curve also resembles the template U light curve. A high-resolution HST Goddard High Resolution Spectrograph (GHRS) spectrum of SN 1992A shows no evidence for any interstellar lines attributable to NGC 1380 or to Galactic high-velocity clouds; low-velocity Galactic gas gives rise to relatively weak Mg II UV resonance absorption lines. These results are consistent with low extinction along the line of sight to SN 1992A. We have done a parameterized LTE analysis of the SN 1992A spectra using a slightly modified version of Woosley's delayed-detonation model DD4. We find that the features in the region blueward of approximately 2650 angstrom in the HST spectra are P Cygni absorptions due to blends of iron peak element multiplets and the Mg II resonance multiplet. Newly synthesized magnesium, sulfur, and silicon probably extend to velocities at least as high as approximately 19,000 km s-1. Newly synthesized Ni-Co may dominate the iron peak element abundances out to approximately 13,000 km s-1 in the ejecta of SN 1992A as in model DD4. However, further investigation of the extent of Ni-Co material in SN 1992A and other Type Ia supernovae is needed; this investigation could greatly help constrain Type Ia models. An analysis of the O I lambda7773 line in SN 1992A and other Type Ia supernovae implies that the oxygen-rich layer in typical Type Ia's extends over a velocity range of at least approximately 11,000-19,000 km s-1. None of the explosion models we considered, including model DD4, has an oxygen-rich layer that completely extends over this range. Model DD4, however, is promising, and further investigation of delayed-detonation models of its kind is merited. Spectropolarimetric observations taken by Spyromilio & Bailey of SN 1992A are consistent with the SN 1992A being spherically symmetric. We discuss these observations and the importance of taking spectropolarimetry of other Type Ia supernovae. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NATL OPT ASTRON OBSERV, CERRO TOLOLO INTER AMER OBSERV, CASILLA 603, CHILE. MIDDLEBURY COLL, DEPT PHYS, MIDDLEBURY, VT 05753 USA. UNIV FED RIO GRANDE SUL, DEPT ASTRON, BR-91501-970 PORTO ALEGRE, RS, BRAZIL. LOWELL OBSERV, FLAGSTAFF, AZ 86001 USA. NORTHWESTERN UNIV, DEPT PHYS & ASTRON, EVANSTON, IL 60208 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. UNIV OKLAHOMA, DEPT PHYS & ASTRON, NORMAN, OK 73019 USA. UNIV VIRGINIA, DEPT ASTRON, CHARLOTTESVILLE, VA 22903 USA. STANFORD UNIV, DEPT PHYS, STANFORD, CA 94305 USA. STOCKHOLM OBSERV, S-13336 SALTSJOBADEN, SWEDEN. STANFORD UNIV, CTR SPACE SCI & ASTROPHYS, STANFORD, CA 94305 USA. UNIV TEXAS, DEPT ASTRON, AUSTIN, TX 78712 USA. RP HARVARD SMITHSONIAN CTR ASTROPHYS, MS-19, 60 GARDEN ST, CAMBRIDGE, MA 02138 USA. RI Hamuy, Mario/G-7541-2016 NR 110 TC 172 Z9 172 U1 1 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1993 VL 415 IS 2 BP 589 EP 615 DI 10.1086/173188 PN 1 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY327 UT WOS:A1993LY32700014 ER PT J AU STECKER, FW DEJAGER, OC AF STECKER, FW DEJAGER, OC TI NEW UPPER LIMITS ON INTERGALACTIC INFRARED RADIATION FROM HIGH-ENERGY ASTROPHYSICS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, THEORY; INFRARED, GENERAL; QUASARS, GENERAL; QUASARS, INDIVIDUAL (MARKARIAN-421) ID MARKARIAN-421 AB Following our previously proposed technique, we have used the recent gamma-ray observations of Mrk 421 obtained by the Whipple Observatory team and the EGRET experiment on Compton Gamma-Ray Observatory as a probe to place significant constraints on the intergalactic infrared energy density. Our 2 sigma upper limits are approximately 10(-8) W m-2 sr-1 for the 1-5 mum range. These constraints are much better than those obtained by direct measurements. They rule out more exotic mechanisms for producing a large intergalactic IR flux and are consistent with radiation produced by stars in normal galaxies. C1 POTCHEFSTROOM UNIV CHRISTIAN HIGHER EDUC,DEPT PHYS,POTCHEFSTROOM 2520,SOUTH AFRICA. RP STECKER, FW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Stecker, Floyd/D-3169-2012 NR 22 TC 106 Z9 106 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1993 VL 415 IS 2 BP L71 EP L73 DI 10.1086/187035 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY329 UT WOS:A1993LY32900003 ER PT J AU WOODEN, DH RANK, DM BREGMAN, JD WITTEBORN, FC TIELENS, AGGM COHEN, M PINTO, PA AXELROD, TS AF WOODEN, DH RANK, DM BREGMAN, JD WITTEBORN, FC TIELENS, AGGM COHEN, M PINTO, PA AXELROD, TS TI AIRBORNE SPECTROPHOTOMETRY OF SN-1987A FROM 1.7 TO 12.6 MICRONS - TIME HISTORY OF THE DUST CONTINUUM AND LINE EMISSION SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Review DE DUST, EXTINCTION; INFRARED, STARS; SUPERNOVAE, INDIVIDUAL (SN-1987A) ID SPECTRAL IRRADIANCE CALIBRATION; BOLOMETRIC LIGHT-CURVE; LARGE MAGELLANIC CLOUD; SUPERNOVA 1987A; SN 1987A; INFRARED SPECTROPHOTOMETRY; PHOTOMETRIC-OBSERVATIONS; ABSOLUTE FLUXES; HYDROGENIC IONS; CARBON-MONOXIDE AB Spectrophotometric observations (1.7-12.6 mum) of SN 1987A from the Kuiper Airborne Observatory are presented for five epochs at 60, 260, 415, 615, and 775 days after the explosion. A variety of emission lines is seen, including members of the hydrogen Humphreys, Pfund, Brackett, and Paschen series, fine-structure lines of metals (including [Ni II] 6.634 mum, [Ni I] 7.507 mum, [Ar II] 6.985 mum, and [Co II] 10.521 mum), and CO and SiO molecular bands. The temporal evolution of the seven strongest H lines follows case C recombination theory and yields large values Of tau(Halpha) at 260 and 415 days. A mass of approximately 2 x 10(-3) M. is derived for stable nickel, and the ratio of the [Ni I] 7.507 mum and [Ni II] 6.634 mum line intensities yields a high ionization fraction of 0.9 in the nickel zone. Dust condensation is clearly detected at 615 days for the first time in a Type II supernova. At no time is there a 9.7 mum emission feature characteristic of interstellar astronomical silicates in the spectra of SN 1987A, nor are the 6.2 or 7.7 mum emission features attributed to polycyclic aromatic hydrocarbons seen. These airbome data are combined with other airbome and ground-based measurements taken at (or near) the same time to form five composite spectra of SN 1987A with wavelength coverage from approximately 3200 angstrom to 100 mum. The IR continuum emission between approximately 2 and 100 mum is compared with a three-component model-(1) hot photospheric continuum, (2) free-free and free-bound H emission, and (3) dust continuum-with the best fit determined using a nonlinear chi2 method. The dust continuum component is well characterized by a single-temperature graybody emission spectrum, i.e., by the radiation from gray grains or dust in optically thick clumps. At early times (less than 400 days after core collapse), the dust emission tracks the bolometric luminosity at about the 2% level. By 615 days, the fraction of the total luminosity contributed by the IR dust continuum increases dramatically to 0.45, and then to 0.83 at 775 days. We suggest that this dichotomy in the temporal evolution of the dust emission arises from dust with different origins. Circumstellar dust present before the supernova and then heated by it may account for the early emission. Newly condensed dust in the ejecta accounts for the later emission. A lower limit to the dust mass at 775 days is approximately 10(-4) M., but much more dust could be present. Since the emission is well fitted by a graybody, no information on the dust composition can be directly discerned from our data. C1 UNIV CALIF SANTA CRUZ OBSERV,LICK OBSERV,SANTA CRUZ,CA 95064. UNIV CALIF BERKELEY,RADIO ASTRON LAB,BERKELEY,CA 94720. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. RP WOODEN, DH (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MOFFETT FIELD,CA 94035, USA. NR 109 TC 153 Z9 154 U1 0 U2 8 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD OCT PY 1993 VL 88 IS 2 BP 477 EP 507 DI 10.1086/191830 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY026 UT WOS:A1993LY02600006 ER PT J AU DLUGOKENCKY, EJ HARRIS, JM CHUNG, YS TANS, PP FUNG, I AF DLUGOKENCKY, EJ HARRIS, JM CHUNG, YS TANS, PP FUNG, I TI THE RELATIONSHIP BETWEEN THE METHANE SEASONAL CYCLE AND REGIONAL SOURCES AND SINKS AT TAE-AHN PENINSULA, KOREA SO ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS LA English DT Article DE ATMOSPHERIC METHANE; REGIONAL CH4 SOURCES AND SINKS; CH4 OBSERVATIONS IN KOREA ID ATMOSPHERIC METHANE AB Methane measurements from weekly air samples collected at Tae-ahn Peninsula, Korea (TAP) present new constraints on the regional methane source strength of eastern Asia. Analysis of atmospheric trajectories shows that the lowest methane values observed at Tae-ahn are associated with southeasterly flow off the tropical Pacific Ocean and are similar to those observed at Cape Kumukahi, Hawaii. During June to August, northwesterly flow from the peat-rich wetlands located in the maritime provinces of the Far East former Soviet Union elevates methane at TAP by approximately 80 ppb above the annual mean. Analysis of the Tae-ahn observations using a 3-D atmospheric methane model suggests that methane emission rates from the Far East Soviet wetlands may be approximately 2 times those of Alaskan wetlands. Also, the relative maximum in May/June at Tae-ahn constrains global CH4 emissions from rice cultivation to approximately 100 Tg yr-1. C1 UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. KOREA NATL UNIV EDUC,INST ENVIRONM SCI,CHONGBOOK 363791,SOUTH KOREA. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771. RP DLUGOKENCKY, EJ (reprint author), NOAA,CLIMATE & DIAGNOST LAB,325 BROADWAY,BOULDER,CO 80303, USA. NR 16 TC 14 Z9 15 U1 3 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0004-6981 J9 ATMOS ENVIRON A-GEN PD OCT PY 1993 VL 27 IS 14 BP 2115 EP 2120 DI 10.1016/0960-1686(93)90041-V PG 6 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA MD968 UT WOS:A1993MD96800003 ER PT J AU KOHL, RL AF KOHL, RL TI AUTONOMIC FUNCTION AND PLASMA-CATECHOLAMINES FOLLOWING STRESSFUL SENSORY STIMULI SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SPACE MOTION SICKNESS AB This experimentation defined a limited role for epinephrine in the autonomic nervous system function and the nausea that occurred following motion sickness testing. Individual responses to stressful sensory stimuli and nausea, as reflected by rising peripheral levels of epinephrine, were not significantly diminished upon repeated exposure and adaptation to the stressor. However, subjects who demonstrated more robust elevations of epinephrine in response to nausea displayed higher resistances to stressful motion stimuli. Modulation of peripheral catecholaminergic function with dexamethasone, or scopolamine plus amphetamine, suggested that altered autonomic nervous system function and nausea following motion sickness testing were not mediated by peripheral catecholamine receptor stimulation. Marked differences were noted in individual responses to drug and systemic responses of epinephrine and norepinephrine. It is possible that responses in epinephrine to motion sickness testing may predict resistance to stressful motion, and represent a peripheral manifestation of some as yet unknown central event of etiologic relevance. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. UNIV TEXAS,MED BRANCH,DEPT PHARMACOL & TOXICOL,GALVESTON,TX 77550. NR 14 TC 6 Z9 7 U1 0 U2 3 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 1993 VL 64 IS 10 BP 921 EP 927 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA MA049 UT WOS:A1993MA04900006 PM 8240196 ER PT J AU Boyd, PT McMillan, SLW AF Boyd, Patricia T. McMillan, Stephen L. W. TI Chaotic scattering in the gravitational three-body problem SO CHAOS LA English DT Article AB We summarize some results of an ongoing study of the chaotic scattering interaction between a bound pair of stars (a binary) and an incoming field star. The stars are modeled as point masses and their equations of motion are numerically integrated for a large number of initial conditions. The global features of the resulting initial-value space maps are presented, and their evolution as a function of system parameters is discussed. We find that the maps contain regular regions separated by rivers of chaotic behavior. The probability of escape within the chaotic regions is discussed, and a straightforward explanation of the scaling present in these regions is reviewed. We investigate a statistical quantity of interest, namely the cross section for temporarily bound interactions, as a function of the third star's incoming velocity and mass. Finally, a new way of considering long-lived trajectories is presented, allowing long data sets to be qualitatively analyzed at a glance. C1 [Boyd, Patricia T.; McMillan, Stephen L. W.] Drexel Univ, Dept Phys & Atmospher Sci, Philadelphia, PA 19104 USA. [Boyd, Patricia T.] NASA, Univ Space Res Assoc, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Boyd, PT (reprint author), Drexel Univ, Dept Phys & Atmospher Sci, Philadelphia, PA 19104 USA. FU NSF [AST-9010876]; Pittsburgh Supercomputer Center [PHY 910009P, AST 900005P]; NASA [NAS5-32484] FX We thank Robert Gilmore, Patricia Carter, Jian-Min Yuan, and James Heagy for helpful discussions during the preparation of this work. We are grateful to T. Tel for a careful reading of the manuscript, and for pointing out an error in an earlier version of this work. This work was supported by NSF Grant No. AST-9010876 and Pittsburgh Supercomputer Center Connection Machine Grant Nos. PHY 910009P and AST 900005P. PTB acknowledges support from NASA Contract No. NAS5-32484 to USRA. NR 34 TC 35 Z9 35 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1054-1500 J9 CHAOS JI Chaos PD OCT PY 1993 VL 3 IS 4 BP 507 EP 523 DI 10.1063/1.165956 PG 17 WC Mathematics, Applied; Physics, Mathematical SC Mathematics; Physics GA V22XU UT WOS:000208308700009 ER PT J AU MIELKE, SL LYNCH, GC TRUHLAR, DG SCHWENKE, DW AF MIELKE, SL LYNCH, GC TRUHLAR, DG SCHWENKE, DW TI A MORE ACCURATE POTENTIAL-ENERGY SURFACE AND QUANTUM-MECHANICAL CROSS-SECTION CALCULATIONS FOR THE F+H2 REACTION SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MANY-BODY EXPANSION; QUANTIZED TRANSITION-STATES; CHEMICAL-REACTIONS; PHOTODETACHMENT SPECTRUM; REACTION PROBABILITIES; ANGULAR-DISTRIBUTIONS; HYPERSPHERICAL METHOD; REACTION F+H2->HF+H; MOLECULAR-BEAM; SCATTERING AB A new potential energy surface (called 6SEC) obtained by iterative refinement of the previously published 5SEC surface is presented. The new surface was obtained using accurate three-dimensional quantum mechanical scattering calculations to test the effects of various modifications of the 5SEC surface. We also calculated well converged quantum mechanical vibrational branching ratios and differential cross sections for the 6SEC surface for four sets of initial conditions; these results show good agreement with experiment for low initial rotational quantum number; increasing the rotational quantum number diminishes the forward scattering, but not as much as has been inferred from experiment. C1 UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP UNIV MINNESOTA, DEPT CHEM, CHEM PHYS PROGRAM, MINNEAPOLIS, MN 55455 USA. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 65 TC 76 Z9 76 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 EI 1873-4448 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD OCT 1 PY 1993 VL 213 IS 1-2 BP 10 EP 16 DI 10.1016/0009-2614(93)85411-G PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LZ692 UT WOS:A1993LZ69200003 ER PT J AU HANSEN, J WILSON, H AF HANSEN, J WILSON, H TI COMMENTARY ON THE SIGNIFICANCE OF GLOBAL TEMPERATURE RECORDS SO CLIMATIC CHANGE LA English DT Note ID SURFACE AIR-TEMPERATURE; CLIMATE RP HANSEN, J (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 26 TC 11 Z9 11 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD OCT PY 1993 VL 25 IS 2 BP 185 EP 191 DI 10.1007/BF01661206 PG 7 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA MK683 UT WOS:A1993MK68300008 ER PT J AU NOOR, AK VENNERI, SL AF NOOR, AK VENNERI, SL TI A PERSPECTIVE ON COMPUTATIONAL STRUCTURES TECHNOLOGY SO COMPUTER LA English DT Article C1 UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. NASA HEADQUARTERS,DIV SPACE RES,WASHINGTON,DC. NR 9 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9162 J9 COMPUTER JI Computer PD OCT PY 1993 VL 26 IS 10 BP 38 EP 46 DI 10.1109/2.237442 PG 9 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA MA718 UT WOS:A1993MA71800015 ER PT J AU BEARD, JS ABITZ, RJ LOFGREN, GE AF BEARD, JS ABITZ, RJ LOFGREN, GE TI EXPERIMENTAL MELTING OF CRUSTAL XENOLITHS FROM KILBOURNE HOLE, NEW-MEXICO AND IMPLICATIONS FOR THE CONTAMINATION AND GENESIS OF MAGMAS SO CONTRIBUTIONS TO MINERALOGY AND PETROLOGY LA English DT Article ID MIDTERTIARY FELSIC VOLCANICS; SR ISOTOPIC COMPOSITIONS; ORIGIN; ND; ELEMENT; CONSTRAINTS; GRANITE; SYSTEM; WATER AB Experiments (P = 6.9 kb; T = 900-1000-degrees-C) on four crustal xenoliths from Kilbourne Hole demonstrate the varying melting behavior of relatively dry crustal lithologies in the region. Granodioritic gneisses (samples KH-8 and KH-11) yield little melt (< 5-25%) by 925-degrees-C, but undergo extensive (30-50%) melting between 950 and 1000-degrees-C. A dioritic charnockite (KH-9) begins to melt, with the consumption of all modal K-feldspar, by 900-degrees-C. It is as fertile a melt source as the granodiorites at lower temperatures, but is outstripped in melt production by the granodiorite gneisses at high temperature, yielding only 26% melt by 1000-degrees-C. A pelitic granulite (KH-12) proved to be refractory (confirming earlier predictions based on geochemistry) and did not yield significant melt even at 1000-degrees-C. All melts have the composition of metaluminous to slightly peraluminous granites and are unlikely to be individually recognizable as magma contaminants on the basis of major element chemistry. However, the relative stability of K-feldspar during partial melting will produce recognizable signatures in Ba. Eu, K/Ba. and Ba/Rb. Melts of KH-11, which retains substantial K-feldspar throughout the melting interval, are generally low in Ba (< 500 800 ppm), have high K/Ba and low Ba/Rb (est.) (62-124 and 1-3, respectively). Melts of KH-9, in which all K-feldspar disappears with the onset of melting. are Ba-rich [2000-2600 ppm, K/Ba = 16-22, Ba/Rb (est.) = 25-47]. Melts of KH-8 have variable Ba contents; < 500 ppm Ba at low temperature but > 900 ppm Ba in high-temperature melts coexisting with a K-feldspar-free restite. Although REE were not measured in either feldspar or melt, the high Kspar/melt Kds for Eu suggests that the melts coexisting with K-feldspar will have strong negative Eu anomalies. Isotopic and trace element models for magma contamination need to take into account the melting behavior of isotopic reservoirs. For example, the most radiogenic (and incompatible element-rich) sample examined here (the pelitic granulite, Sr-87/Sr-86 = 0.757) is refractory, while samples with far less radiogenic Sr (Sr-87/Sr-86 = 0.708-0.732) produced substantial melt. This suggests that, in this area, the isotopic signature of contamination may be more subtle than expected. The experimental results can be used to model the petrogenesis of Oligocene volcanic rocks exposed 150 km to the NW of Kilbourne Hole, in the Black Range in the Mogollon-Datil volcanic field. The experimental results suggest that a crustal melting origin for the Kneeling Nun and Caballo Blanco Tuffs is unlikely, even though such an interpretation is permitted by Sr isotopes. Crustal contamination of a mantle-derived magma best explains the chemical and isotopic characteristics of these tuffs. Both experimental and geochemical data suggest that the rhyolites of Moccasin John Canyon and Diamond Creek could represent direct melts of granodiorite basement similar, but not identical, to the Kilbourne Hole granodiorites, perhaps slightly modified by crystal fractionation. The absence of volcanic rocks having Sr-87/Sr-86 > 0.74 in the region is consistent with the refractory character of the pelitic granulite. C1 IT CORP, ALBUQUERQUE, NM 87108 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP BEARD, JS (reprint author), VIRGINIA MUSEUM NAT HIST, MARTINSVILLE, VA 24112 USA. NR 35 TC 40 Z9 40 U1 3 U2 7 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0010-7999 EI 1432-0967 J9 CONTRIB MINERAL PETR JI Contrib. Mineral. Petrol. PD OCT PY 1993 VL 115 IS 1 BP 88 EP 102 DI 10.1007/BF00712981 PG 15 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA MD394 UT WOS:A1993MD39400008 ER PT J AU PHILLIPS, RS SHAHSHAHANI, MM AF PHILLIPS, RS SHAHSHAHANI, MM TI SCATTERING-THEORY FOR SYMMETRICAL SPACES OF NONCOMPACT TYPE SO DUKE MATHEMATICAL JOURNAL LA English DT Article ID GROUP REPRESENTATIONS; DUALITY C1 JET PROP LAB,PASADENA,CA 91109. RP PHILLIPS, RS (reprint author), STANFORD UNIV,DEPT MATH,STANFORD,CA 94305, USA. NR 18 TC 2 Z9 2 U1 0 U2 0 PU DUKE UNIV PRESS PI DURHAM PA BOX 90660, DURHAM, NC 27708-0660 SN 0012-7094 J9 DUKE MATH J JI Duke Math. J. PD OCT PY 1993 VL 72 IS 1 BP 1 EP 29 DI 10.1215/S0012-7094-93-07201-8 PG 29 WC Mathematics SC Mathematics GA MF152 UT WOS:A1993MF15200001 ER PT J AU REID, MA AF REID, MA TI CHANGES IN IMPEDANCES OF NI/CD CELLS WITH VOLTAGE AND CYCLE LIFE SO ELECTROCHIMICA ACTA LA English DT Article DE BATTERIES; IMPEDANCE AB Impedances of aerospace design Super Ni/Cd cells are being measured as functions of voltage and number of cycles. The cells have been cycled over 4400 cycles to date. Analysis of the impedance data has been made using a number of equivalent circuits. The model giving the best fit over the whole range of voltage has a parallel circuit of a kinetic resistance and a constant phase element in series with the ohmic resistance. The values for the circuit elements have been treated as empirical parameters, and no attempt has been made as yet to correlate them with physical and chemical changes in the electrode. No significant changes have been seen as yet with the exception of a decrease in kinetic resistance at low states of charge in the first 500 cycles. RP REID, MA (reprint author), NASA,LEWIS RES CTR,ELECTROCHEM TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 7 TC 5 Z9 5 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-4686 J9 ELECTROCHIM ACTA JI Electrochim. Acta PD OCT PY 1993 VL 38 IS 14 BP 2037 EP 2041 DI 10.1016/0013-4686(93)80337-Y PG 5 WC Electrochemistry SC Electrochemistry GA LX860 UT WOS:A1993LX86000038 ER PT J AU MORRIS, RV GOLDEN, DC BELL, JF LAUER, HV ADAMS, JB AF MORRIS, RV GOLDEN, DC BELL, JF LAUER, HV ADAMS, JB TI PIGMENTING AGENTS IN MARTIAN SOILS - INFERENCES FROM SPECTRAL, MOSSBAUER, AND MAGNETIC-PROPERTIES OF NANOPHASE AND OTHER IRON-OXIDES IN HAWAIIAN PALAGONITIC SOIL PN-9 SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT WORKSHOP ON CHEMICAL WEATHERING ON MARS CY SEP 10-12, 1992 CL COCOA BEACH, FL SP MARTIAN SURFACE & ATMOSPHERE THROUGH TIME PROGRAM ID BASALTIC GLASSES; IMPACT MELT; MARS; MINERALOGY; HEMATITE; CHEMISTRY; EARTH; CRUST AB We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars. C1 LOCKHEED ESC,HOUSTON,TX 77058. UNIV WASHINGTON,DEPT GEOL SCI,SEATTLE,WA 98195. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP MORRIS, RV (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH SN4,HOUSTON,TX 77058, USA. NR 62 TC 94 Z9 94 U1 2 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1993 VL 57 IS 19 BP 4597 EP 4609 DI 10.1016/0016-7037(93)90185-Y PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MD265 UT WOS:A1993MD26500005 PM 11539577 ER PT J AU LERNER, NR PETERSON, E CHANG, S AF LERNER, NR PETERSON, E CHANG, S TI THE STRECKER SYNTHESIS AS A SOURCE OF AMINO-ACIDS IN CARBONACEOUS CHONDRITES - DEUTERIUM RETENTION DURING SYNTHESIS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID MURCHISON METEORITE; MASS-SPECTRA; BUTYL ESTERS; HYDROGEN AB Deuterium-enriched amino acids occur in the Murchison carbonaceous chondrite. Synthesis from D-enriched interstellar precursors by Strecker reactions during aqueous alteration of the parent body has been proposed. To test this hypothesis, we have measured the retention of deuterium in amino acids produced from HCN, NH3, and formaldehyde-D2, acetaldehyde-D4, and acetone-D6 in H2O. The isotopic label is 50% to 98% retained, with variations in retentivity depending on the amino acid and the reaction conditions. If amino acids, once formed on the parent body by the Strecker synthesis, lose no deuterium by subsequent exchange with water or H-bearing minerals, then the observed deuterium isotopic composition of Murchison amino acids represents as much as 50% or more of the enrichments inherited from their interstellar precursors. Imino diacids are prominent side products of the Strecker synthesis which have not been reported in carbonaceous chondrites. Under the conditions of the Strecker reaction using deuterium labeled aldehydes and ketones, unlabeled amino acids are also formed by an HCN polymerization route indicating multiple pathways for the synthesis of amino acids in meteorites. RP LERNER, NR (reprint author), NASA,AMES RES CTR,PLANETARY BIOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 40 TC 37 Z9 37 U1 5 U2 29 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1993 VL 57 IS 19 BP 4713 EP 4723 DI 10.1016/0016-7037(93)90195-3 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MD265 UT WOS:A1993MD26500015 PM 11539581 ER PT J AU TREIMAN, AH AF TREIMAN, AH TI THE PARENT MAGMA OF THE NAKHLA (SNC) METEORITE, INFERRED FROM MAGMATIC INCLUSIONS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID PETROGENESIS; ZAGAMI; CRYSTALLIZATION; METASOMATISM; PHENOCRYSTS; EVOLUTION; COMPLEX; BASALTS; ORIGIN; CLUES AB The Nakhla meteorite, one of the SNC group of putative Martian origin, is an igneous rock, a cumulate of augite and olivine, that does not represent a magma composition. Samples of its parent magma were trapped as magmatic inclusions in its cumulus olivine crystals. The inclusions range from 10-350 mum in diameter and consist of augite rich in Ti and Al, silica-rich glass, iron oxides, ilmenite, apatite, and rare amphibole. Each inclusion has a find of augite and chromite against its host olivine, and a core of radiating sprays of augite set in glass and feldspar. These textures are consistent with an origin as trapped silicate liquid. Twenty four inclusions were analyzed by electron microprobe, by averaging series of rastered beam analyses. On average, the analyses are independent of the size of the inclusion, most clearly for inclusions larger than 70 mum diameter, and variations among analyses are consistent with small differences in th; proportions of augite, glass, and iron oxides exposed on thin section surfaces. The average inclusion analysis is calculated to represent 28% host olivine and 72% inclusion composition. The inclusion rinds are calculated to be 13% of the inclusion composition, for which a small correction is made. The inclusion composition is then corrected for Mg/Fe exchange with the host olivine (to chemical equilibrium with the cumulus augite cores) and crystallization of 13% olivine onto the host crystal to yield a magma composition with the proper MgO/FeO ratio and with olivine and augite on its liquidus. This composition, NK93, is an estimate of Nakhla's parent magma originally trapped in the inclusions. NK93 is basaltic, rich in iron, and poor in aluminum compared to terrestrial basalts. Its abundances of Al, Ti, and Na are consistent with the geochemistry of the SNC meteorites as a whole. NK93 is similar to the parent magmas proposed in an independent study of magmatic inclusions in Nakhla, but unlike other proposed compositions. One proposed parent magma, based on mass balance and the assumption that Nakhla was a closed-system after crystal accumulation, is inconsistent with the magmatic inclusion studies and Nakhla's petrography. This suggests that Nakhla was not a closed-system, but was infiltrated by post-cumulus basaltic magmas. Another suggested parent magma was derived from element distribution between augite and basaltic magma, but that calculation relied on an incorrect augite composition. Using a correct augite composition in that calculation yields a parent magma much closer in composition to NK93. Thus, three independent approaches converge in requiring that Nakhla originally formed from a low-Al, low MgO/FeO basalt like NK93. C1 NASA,LYNDON B JOHNSON SPACE CTR,SN-2,HOUSTON,TX 77058. NR 32 TC 78 Z9 78 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1993 VL 57 IS 19 BP 4753 EP 4767 DI 10.1016/0016-7037(93)90198-6 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MD265 UT WOS:A1993MD26500018 ER PT J AU KOROTEV, RL MORRIS, RV AF KOROTEV, RL MORRIS, RV TI COMPOSITION AND MATURITY OF APOLLO 16 REGOLITH CORE 60013/14 SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID LUNAR AB Samples from every half-centimeter dissection interval of double drive tube 60013/14 (sections 60013 and 60014) were analyzed by magnetic techniques for Fe-degrees concentration and surface maturity parameter I(s)/FeO, and by neutron activation for concentrations of 25 lithophile and siderophile elements. Core 60013/14 is one of three regolith cores taken in a triangular array 40-50 m apart on the Cayley plains during Apollo 16 mission to the Moon. The core can be divided into three zones based both on I(s)/FeO and composition. Unit A (0-44 cm depth) is compositionally similar to other soils from the surface of the central region of the site and is mature throughout, although maturity decreases with depth. Unit B (44-59 cm) is submature and compositionally more feldspathic than Unit A. Regions of lowest maturity in Unit B are characterized by lower Sm/Sc ratios than any soil obtained from the Cayley plains as a result of some unidentified lithologic component with low surface maturity. The component is probably some type of mafic anorthosite that does not occur in such high abundance in any of the other returned soils. Unit C (59-62 cm) is more mature than Unit B and compositionally equivalent to an 87: 13 mixture of soil such as that from Unit A and plagioclase such as found in ferroan anorthosite. Similar soils, but containing greater abundances of anorthosite (plagioclase), are found at depth in the other two cores of the array. These units of immature to submature soil enriched to varying degrees (compared to the mature surface soil) in ferroan anorthosite consisting of approximately 99% plagioclase are the only compositionally distinct subsurface similarities among the three cores. Each of the cores contains other units that are compositionally dissimilar to any soil unit in the other two cores. These compositionally distinct units probably derive from local subsurface blocks deposited by the event(s) that formed the Cayley plains. The ferroan anorthosite with approximately 99% plagioclase, however, must represent some subsurface lithology that is significant on the scale of tens of meters. The compositional uniformity of the surface soil (0-10 cm depth) over distances of kilometers reflects the large-scale uniformity of the plains deposits; the fine-structure reflects small-scale nonuniformity and the inefficiency of the impact-mixing process at depths as shallow as even one meter. C1 NASA,LYNDON B JOHNSON SPACE CTR,CODE SN4,HOUSTON,TX 77058. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. RP KOROTEV, RL (reprint author), WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130, USA. NR 54 TC 11 Z9 11 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1993 VL 57 IS 19 BP 4813 EP 4826 DI 10.1016/0016-7037(93)90201-7 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MD265 UT WOS:A1993MD26500021 ER PT J AU SHIH, CY NYQUIST, LE WIESMANN, H AF SHIH, CY NYQUIST, LE WIESMANN, H TI K-CA CHRONOLOGY OF LUNAR GRANITES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID KREEP BASALT; RB-SR; AGE; CLAST; GEOCHRONOLOGY; PETROGENESIS; ISOTOPES; EUCRITE; ORIGIN; SAMPLE AB K-Ca age determinations were undertaken for three lunar granitic samples (14321,1062, 14303,206, and 12013,141 ). K-Ca isotopic analyses of bulk samples of seven pristine lunar igneous rocks including four mare basalts ( 100 1 7, 15555, 14321,1394, and 14305,304,371), one norite (15445,17), one anorthosite (60025), one KREEP basalt (72275,543), and seven meteorites (Juvinas, Pasamonte, Moore County, Stannern, Y75011,84B, Zagami, and Shergotty) were also performed. The K-Ca mineral isochron for lunar granitic clast 14321,1062 yields an age of 4.06 +/- 0.07 Ga for lambda(K-40) = 0.5543 Ga-1 and an initial Ca-40/Ca-44 of 47.141 -/+ 0.010 (normalized to Ca-42/Ca-44 = 0.31221). The K-Ca age is in excellent agreement with the Rb-Sr and Sm-Nd ages and is slightly older than the average Ar-39-Ar-40 and U-Pb zircon ages. Low precision K-Ca ages of 4.04 +/- 0.64 Ga and 3.76 +/- 0.72 Ga were obtained for lunar granites 14303,206 and 12013,141, respectively, due to their lower K/Ca ratios. Initial Ca-40/Ca-44 values for seven lunar and seven meteoritic bulk samples are similar and yield an average initial Ca-40/Ca-44 of 47.136 +/- 0.002 (2sigma(m)) and +/- 0.006 (2sigma(p)). Assuming this value as the lunar initial Ca-40/Ca-44, a ten- to twenty-fold fractionation for K/Ca during the formation of granite 14321 is calculated for a two-stage model. The large K/Ca enrichment is consistent with a granite genesis model involving a silicate-liquid immiscibility process. Literature data for lunar granites studied so far exhibit a wide range of ages from 3.9 to 4.4 Ga. Thus, lunar granites probably represent samples from about eight different intrusive bodies. The positive K and K/Ca correlations of lunar rocks strongly supports an early global lunar differentiation. However, most granites were probably not directly produced from this early differentiation event. C1 NASA,LYNDON B JOHNSON SPACE CTR,SN2,HOUSTON,TX 77058. RP SHIH, CY (reprint author), LOCKHEED ENGN & SCI CO,2400 NASA RD 1,HOUSTON,TX 77058, USA. NR 76 TC 23 Z9 26 U1 0 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1993 VL 57 IS 19 BP 4827 EP 4841 DI 10.1016/0016-7037(93)90202-8 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MD265 UT WOS:A1993MD26500022 ER PT J AU MILLER, MM WEBB, FH TOWNSEND, D GOLOMBEK, MP DOKKA, RK AF MILLER, MM WEBB, FH TOWNSEND, D GOLOMBEK, MP DOKKA, RK TI REGIONAL COSEISMIC DEFORMATION FROM THE JUNE 28, 1992, LANDERS, CALIFORNIA, EARTHQUAKE - RESULTS FROM THE MOJAVE GPS NETWORK SO GEOLOGY LA English DT Article ID SAN-ANDREAS FAULT; SOUTHERN-CALIFORNIA; DESERT; SLIP; STRESS; VALLEY; SHEAR AB The 1992 Landers, California, earthquake sequence and its aftershocks defineate an a part of the Eastern California shear zone. The surface rupture lies within the Mojave Desert, providing a unique opportunity to characterize far-field deformation with a regional Global Positioning System (GPS) network that was installed and occupied in May 1991, with uncertainties of less than 1 cm on interstation baseline vectors. Changes in absolute displacement vectors on the decimetre and centimetre level were determined for individual sites, providing more samples of the sparsely sampled Landers displacement field. Measured displacements result from secular strain across the Mojave Desert, coseismic elastic recovery, and postseismic deformation during the six weeks between the earthquake and the GPS experiment. Secular strain and postseismic displacement are relatively small. Thus, first-order modeling of these fields allows calculation and subtraction of their signals, leaving a coseismic residual field. The GPS-determined far-field coseismic displacements differ significantly from elastic half-space models, offering new insight on the role of regional-scale heterogeneity in crustal structure. C1 JET PROP LAB,PASADENA,CA 91109. LOUISIANA STATE UNIV,DEPT GEOL,BATON ROUGE,LA 70803. RP MILLER, MM (reprint author), CENT WASHINGTON UNIV,DEPT GEOL,ELLENSBURG,WA 98926, USA. OI Miller, M Meghan/0000-0002-7296-0639 NR 28 TC 10 Z9 10 U1 0 U2 2 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD OCT PY 1993 VL 21 IS 10 BP 868 EP 872 DI 10.1130/0091-7613(1993)021<0868:RCDFTJ>2.3.CO;2 PG 5 WC Geology SC Geology GA MB299 UT WOS:A1993MB29900001 ER PT J AU RICHARDS, DW JANESICK, JR ELLIOT, ST DINGIZIAN, A VELTHUIZEN, R WEI, Q CLARKE, LP AF RICHARDS, DW JANESICK, JR ELLIOT, ST DINGIZIAN, A VELTHUIZEN, R WEI, Q CLARKE, LP TI ENHANCED DETECTION OF NORMAL RETINAL NERVE-FIBER STRIATIONS USING A CHARGE-COUPLED-DEVICE AND DIGITAL FILTERING SO GRAEFES ARCHIVE FOR CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY LA English DT Article ID IMAGE-ANALYSIS; LAYER; GLAUCOMA AB We used a 1024 x 1024 pixel, 15-mum, 16-bit-encoding, multi-pin-phase charge-coupled device (CCD) to obtain images of the normal human retinal nerve fiber layer. This device, which operates at room temperature, offers significantly better signal-to-noise ratio, linearity, and dynamic range than do photographic film, video imaging techniques, or commercially available CCDs. We demonstrate the use of a nonlinear digital filter, together with filter windows, that enhances fine detail of NFL striations, while suppressing noise, in limited areas of the CCD images. High-sensitivity imaging of this type, together with appropriate digital processing, may prove useful in diagnosing and following nerve-fiber-layer damage due to glaucoma. C1 UNIV S FLORIDA,COLL MED,DEPT OPHTHALMOL,TAMPA,FL 33612. UNIV S FLORIDA,H LEE MOFFITT HOSP,TAMPA,FL 33620. UNIV S FLORIDA,DEPT RADIOL,CTR ENGN & MED IMAGE ANAL,TAMPA,FL 33620. JET PROP LAB,PASADENA,CA 91109. UNIV S FLORIDA,CANC RES INST,TAMPA,FL 33620. NR 31 TC 4 Z9 4 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0721-832X J9 GRAEF ARCH CLIN EXP JI Graefes Arch. Clin. Exp. Ophthalmol. PD OCT PY 1993 VL 231 IS 10 BP 595 EP 599 DI 10.1007/BF00936525 PG 5 WC Ophthalmology SC Ophthalmology GA LY709 UT WOS:A1993LY70900008 PM 8224936 ER PT J AU FRICK, J MITCHELL, CA AF FRICK, J MITCHELL, CA TI STABILIZATION OF PH IN SOLID-MATRIX HYDROPONIC SYSTEMS SO HORTSCIENCE LA English DT Article DE BRASSICA-NAPUS; AMBERLITE; BIOREGENERATIVE LIFE SUPPORT; CATION EXCHANGE; CONTROLLED ENVIRONMENT; MES; SUBSTRATE; YIELD RATE ID NUTRIENT SOLUTION; BUFFERS; CULTURE AB 2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mm) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite: 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g.m-2.day-1) were about double that of the control (8.2 g.m-2.day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g.m-2.day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mm MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents. RP FRICK, J (reprint author), PURDUE UNIV,NASA,SPECIALIZED CTR RES & TRAINING BIOREGENERAT LIFE SUPPORT,W LAFAYETTE,IN 47907, USA. NR 15 TC 5 Z9 6 U1 0 U2 1 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 SN 0018-5345 J9 HORTSCIENCE JI Hortscience PD OCT PY 1993 VL 28 IS 10 BP 981 EP 984 PG 4 WC Horticulture SC Agriculture GA MJ963 UT WOS:A1993MJ96300003 PM 11537992 ER PT J AU DOBROVOLSKIS, AR AF DOBROVOLSKIS, AR TI THE LAPLACE PLANES OF URANUS AND PLUTO SO ICARUS LA English DT Article ID COMETARY ORBITS; POLAR RINGS; NEPTUNE C1 UNIV CALIF SANTA CRUZ,SANTA CRUZ,CA 95060. RP DOBROVOLSKIS, AR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1993 VL 105 IS 2 BP 400 EP 407 DI 10.1006/icar.1993.1136 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ML417 UT WOS:A1993ML41700013 ER PT J AU GRIFFIN, MJ ORTON, GS AF GRIFFIN, MJ ORTON, GS TI THE NEAR-MILLIMETER BRIGHTNESS TEMPERATURE SPECTRA OF URANUS AND NEPTUNE SO ICARUS LA English DT Article ID ROTOTRANSLATIONAL ABSORPTION-SPECTRA; THERMAL STRUCTURE; VLA OBSERVATIONS; SUBMILLIMETER; ATMOSPHERE; PAIRS; WAVELENGTH; VOYAGER-2; DYNAMICS; PLANETS C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP GRIFFIN, MJ (reprint author), QUEEN MARY & WESTFIELD COLL,DEPT PHYS,MILE END RD,LONDON E1 4NS,ENGLAND. NR 30 TC 135 Z9 135 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1993 VL 105 IS 2 BP 537 EP 547 DI 10.1006/icar.1993.1147 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ML417 UT WOS:A1993ML41700024 ER PT J AU HOBAN, S REUTER, DC DISANTI, MA MUMMA, MJ ELSTON, R AF HOBAN, S REUTER, DC DISANTI, MA MUMMA, MJ ELSTON, R TI INFRARED OBSERVATIONS OF METHANOL IN COMET P/SWIFT-TUTTLE SO ICARUS LA English DT Article ID OORT CLOUD; EMISSION FEATURE; FORMALDEHYDE; HALLEY; IDENTIFICATION; SPECTRA C1 CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. RP HOBAN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,CODE 693,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013 NR 33 TC 15 Z9 15 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1993 VL 105 IS 2 BP 548 EP 556 DI 10.1006/icar.1993.1148 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA ML417 UT WOS:A1993ML41700025 ER PT J AU SIMONS, RN LEE, RQ AF SIMONS, RN LEE, RQ TI EFFECT OF PARASITIC DIELECTRIC RESONATORS ON CPW APERTURE-COUPLED DIELECTRIC RESONATOR ANTENNAS SO IEE PROCEEDINGS-H MICROWAVES ANTENNAS AND PROPAGATION LA English DT Article DE WAVE-GUIDES AND WAVE-GUIDE COMPONENTS; DIELECTRIC RESONATOR; APERTURE COUPLING AB The effects of parasitic dielectric resonators on the HE(11 delta) and HE(13 delta) modes of a cylindrical dielectric resonator antenna (DRA) have been studied. The DRA was excited electromagnetically with a grounded coplanar waveguide through an aperture in the common ground plane. Strong couplings were observed for the HE(11 delta) mode with the parasitic element superimposed on the driven DRA, and for the HE(13 delta) mode with parasitic elements placed on both sides of the driven DRA. Results indicate significant enhancement in bandwidth for both modes, and good radiation patterns for the HE(11 delta) mode. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 7 TC 43 Z9 43 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0950-107X J9 IEE PROC-H PD OCT PY 1993 VL 140 IS 5 BP 336 EP 338 PG 3 WC Optics SC Optics GA MM499 UT WOS:A1993MM49900002 ER PT J AU REDDY, CJ ITTIPIBOON, A CUHACI, M AF REDDY, CJ ITTIPIBOON, A CUHACI, M TI ADMITTANCE CHARACTERISTICS OF NARROW RADIATING SLOTS IN NONRADIATING DIELECTRIC WAVE-GUIDE SO IEE PROCEEDINGS-H MICROWAVES ANTENNAS AND PROPAGATION LA English DT Article DE MILLIMETER-WAVE CIRCUITS; SLOT ARRAY ANTENNAS; WAVE-GUIDES ID MODAL EXPANSION METHOD; WAVE-GUIDE; DESIGN; ARRAY AB A study of an inclined slot cut in the metal wall of nonradiative dielectric (NRD) waveguide is presented. The modal expansion method is applied to the development of an equivalent network of a slot discontinuity in NRD waveguide, using the reciprocity and Poynting theorems. The effect of the metal wall thickness is taken into consideration by applying microwave network analysis. Numerical data for the normalised slot admittance is obtained and compared with experimental results. Good agreement is observed. Numerical data for the slot admittance for various dielectric materials is also presented and the radiation patterns of a single slot are included. C1 COMMUN RES CTR,OTTAWA K2H 8S2,ON,CANADA. RP REDDY, CJ (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 490,HAMPTON,VA 23681, USA. NR 21 TC 7 Z9 7 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0950-107X J9 IEE PROC-H PD OCT PY 1993 VL 140 IS 5 BP 407 EP 413 PG 7 WC Optics SC Optics GA MM499 UT WOS:A1993MM49900016 ER PT J AU BARNES, NP BARNES, JC AF BARNES, NP BARNES, JC TI INJECTION SEEDING-I - THEORY SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID AXIAL-MODE-OPERATION; ND-YAG OSCILLATOR; DYE-LASER; HIGH-POWER; OPTICAL RESONATORS; NARROW LINEWIDTH; EXCIMER LASERS; TEA-CO2 LASER; LOCKING; SELECTION AB Injection seeding has proven to be a practical method of controlling the spectral output of a laser in an efficient and reliable manner. To achieve satisfactory injection seeding performance, a sufficiently large seed must be employed. To characterize the required seed, an injection seeding theory is developed here which establishes two interrelated concepts, threshold for injection seeding and spectral purity of the laser output. Rather than utilizing numerical techniques to solve the differential equations, closed-form expressions for the threshold are developed for not only common continuous wave injection seeding but pulsed injection seeding as well. In addition, effects of alignment of the seed to the resonator, both in position and angle, and effects of frequency mismatch, or difference between the seed and the resonant frequencies of the resonator, are taken into account. Expressions for the threshold utilize readily measurable experimental parameters. Spectral purity of the laser output and its consequences on the required seed power or energy are also explored. RP BARNES, NP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 37 TC 37 Z9 44 U1 3 U2 20 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD OCT PY 1993 VL 29 IS 10 BP 2670 EP 2683 DI 10.1109/3.250390 PG 14 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA MN495 UT WOS:A1993MN49500012 ER PT J AU BARNES, JC BARNES, NP WANG, LG EDWARDS, W AF BARNES, JC BARNES, NP WANG, LG EDWARDS, W TI INJECTION SEEDING-II - TI-AL2O3 EXPERIMENTS SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID LASER CHARACTERISTICS; SAPPHIRE LASER; SENSITIVITY AB Experiments have been designed and performed to determine the effects on the seeding efficiency of injection seed energy and power, alignment, and spatial mode matching between single longitudinal mode seed lasers and a power oscillator. The absorption features of H2O have allowed the characterization of the seeding efficiency by selectively absorbing the laser output energy corresponding to the seed wavelength. This enabled the accurate measurement of the residual unseeded laser output energy. Both a pulsed and a continuous wave seed source were used for these experiments. This work compares the results of the experiments with a theory for injection seeding developed in the previous paper. C1 COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185. RP BARNES, JC (reprint author), NASA,LANGLEY RES CTR,MS474,HAMPTON,VA 23681, USA. NR 24 TC 29 Z9 30 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD OCT PY 1993 VL 29 IS 10 BP 2684 EP 2692 DI 10.1109/3.250391 PG 9 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA MN495 UT WOS:A1993MN49500013 ER PT J AU BOUSSALIS, D BAYARD, DS IH, C WANG, SJ AHMED, A AF BOUSSALIS, D BAYARD, DS IH, C WANG, SJ AHMED, A TI EXPERIMENTAL-STUDY IN ADAPTIVE TRACKING CONTROL SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID SYSTEMS AB This paper describes an experimental study of adaptive pointing and tracking control for flexible spacecraft conducted on a complex ground experiment facility. The algorithm used in this study is based on a multivariable direct model reference adaptive control law. Several experimental validation studies were performed earlier using this algorithm for vibration damping and robust regulation, with excellent results. The current work extends previous studies by addressing the pointing and tracking problem. As is consistent with an adaptive control framework, the plant is assumed to be poorly known to the extent that only system level knowledge of its dynamics is availabe. Explicit bounds on the steady-state pointing error are derived as functions of the adaptive controller design parameters. It is shown that good tracking performance can be achieved in an experimental setting by adjusting adaptive controller design weightings according to the guidelines indicated by the analytical expressions for the error. C1 JET PROP LAB,GALILEO FLIGHT PROJECT,PASADENA,CA 91109. RP BOUSSALIS, D (reprint author), JET PROP LAB,GUIDANCE & CONTROL SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 1993 VL 29 IS 4 BP 1204 EP 1215 DI 10.1109/7.259523 PG 12 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA MD777 UT WOS:A1993MD77700012 ER PT J AU LIU, KF BALANIS, CA BIRTCHER, CR BARBER, GC AF LIU, KF BALANIS, CA BIRTCHER, CR BARBER, GC TI ANALYSIS OF PYRAMIDAL HORN ANTENNAS USING MOMENT METHODS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID RADIATION; WAVEGUIDE; APERTURE; PLANE; HALF AB A hybrid numerical technique is developed for electrically large pyramidal horn antennas radiating in free space. A stepped-waveguide method is used to analyze the interior surfaces of the horn transition. The electric field integral equation (EFIE) is employed on the outer surfaces of the pyramidal horn including the radiating aperture. Meanwhile, the magnetic field integral equation (MFIE) is used on the aperture to relate the aperture fields and those in the horn transition. The resultant hybrid field integral equation (HFIE) is solved numerically by the method of moments. This formulation is both accurate and numerically stable so that high-gain microwave pyramidal horns can be analyzed rigorously. Far-field radiation patterns, both computed and measured, are presented for three electrically-large X-band horn antennas. The comparisons demonstrate that this method is accurate enough to predict the fine pattern structure at wide angles and in the back region. Computed far-field patterns and aperture field distributions of two smaller X-band horns are also presented along with a discussion on the validity of the approximate aperture field distributions routinely used in the analysis and design of pyramidal horns. C1 NASA,LANGLEY RES CTR,CECOM,JOINT PROGRAMS OFF,HAMPTON,VA 23681. RP LIU, KF (reprint author), ARIZONA STATE UNIV,TELECOMMUN RES CTR,TEMPE,AZ 85287, USA. NR 26 TC 33 Z9 35 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD OCT PY 1993 VL 41 IS 10 BP 1379 EP 1389 DI 10.1109/8.247778 PG 11 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA MM290 UT WOS:A1993MM29000004 ER PT J AU BACH, R PAIELLI, R AF BACH, R PAIELLI, R TI LINEARIZATION OF ATTITUDE-CONTROL ERROR DYNAMICS SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note AB Direction cosines and quaternions are useful for representing rigid-body attitude because they exhibit no kinematic singularities. Each utilizes more variables than the minimum three degrees of freedom required to specify attitude. Therefore, application of a nonlinear inversion procedure to either formulation introduces singularities. Furthermore, in designing an attitude-control system, it is not appropriate to express attitude error as a difference of direction cosines (or quaternions). One should employ a measure of attitude error that not only is minimal but preserves orthogonal rotation properties as well. This note applies an inversion procedure to an appropriate measure of attitude error, so that the singularity occurs when the error reaches +/- 180-degrees. This approach leads to the realization of a new model-follower attitude-control system that exhibits exact linear attitude-error dynamics. RP BACH, R (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 11 TC 15 Z9 16 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD OCT PY 1993 VL 38 IS 10 BP 1521 EP 1525 DI 10.1109/9.241567 PG 5 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA MF088 UT WOS:A1993MF08800008 ER PT J AU JAIN, RK AF JAIN, RK TI CALCULATED PERFORMANCE OF INDIUM-PHOSPHIDE SOLAR-CELLS UNDER MONOCHROMATIC ILLUMINATION SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Note AB The performance of a high-efficiency indium phosphide n+p solar cell under monochromatic illumination has been modeled. The cell modeling of this experimental device gives the peak efficiency in excess of 44% at 0.87 mum and 25-degrees-C. The effect of cell series resistance on its performance has also been studied. The effect of cell series resistance on its performance has also been studied. Calculated efficiencies for an optimized InP cell are in excess of 50% in the wavelength band of 0.75-0.925 mum. Our calculations of conversion efficiency versus source wavelength for InP solar cells are compared to other solar cell materials at a source illumination of 1 W/cm 2. RP JAIN, RK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 12 TC 6 Z9 10 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD OCT PY 1993 VL 40 IS 10 BP 1893 EP 1895 DI 10.1109/16.277355 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA MA766 UT WOS:A1993MA76600032 ER PT J AU ACHARYA, PR EKSTROM, H GEARHART, SS JACOBSSON, S JOHANSSON, JF KOLLBERG, EL REBEIZ, GM AF ACHARYA, PR EKSTROM, H GEARHART, SS JACOBSSON, S JOHANSSON, JF KOLLBERG, EL REBEIZ, GM TI TAPERED SLOTLINE ANTENNAS AT 802 GHZ SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Tapered endfire slotline antennas, of the BLTSA type, have been fabricated on 1.7 muM thin SiO2/Si3N4 dielectric membranes. Antenna patterns of the E-, H-, and D-planes have been measured at 802 GHz. The -10 dB beamwidths were found to be approximately 40-degrees in all planes, with side lobe levels below -11 dB (-19 dB in the E-plane). The cross-polarized peaks in the D-plane are 8 dB below the co-polarized peak. A theoretical model for calculating the E- and H- plane patterns of tapered slotline antenna has been extended to include the co- and cross-polarized D-planes. Measured and calculated patterns show good agreement. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109. RP ACHARYA, PR (reprint author), CHALMERS UNIV TECHNOL,DEPT RADIOL & SPACE SCI,S-41296 GOTHENBURG,SWEDEN. NR 16 TC 29 Z9 29 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD OCT PY 1993 VL 41 IS 10 BP 1715 EP 1719 DI 10.1109/22.247916 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA ML422 UT WOS:A1993ML42200008 ER PT J AU KORMANYOS, BK OSTDIEK, PH BISHOP, WL CROWE, TW REBEIZ, GM AF KORMANYOS, BK OSTDIEK, PH BISHOP, WL CROWE, TW REBEIZ, GM TI A PLANAR WIDE-BAND 80-200 GHZ SUBHARMONIC RECEIVER SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID MILLIMETER AB A wideband planar subharmonic mixer has been designed for millimeter-wave operation. The receiver consists of a novel back-to-back Schottky-diode pair integrated at the base of a wideband log-periodic antenna and placed on a silicon lens. The wideband planar receiver results in state-of-the art-performance at 90 GHz (and 182 GHz) with a double-sideband conversion loss and noise-temperature of 6.7 dB (and 8.5 dB) and 1080 K (and 1820 K), respectively. These results are about 3 dB higher than the best tuned waveguide subharmonic mixers using planar diodes. The design is well suited for higher frequencies (up to 1 THz) and for the inclusion of biased back-to-back planar diodes to ease the LO power requirements. The planar subharmonic approach results in an inexpensive wideband receiver and the design can be easily extended to receiver arrays. C1 USAF,INST TECHNOL,DEPT ENGN PHYS,WRIGHT PATTERSON AFB,OH 45433. UNIV VIRGINIA,DEPT ELECT ENGN,SEMICOND DEVICE LAB,CHARLOTTESVILLE,VA 22903. RP KORMANYOS, BK (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 23 TC 45 Z9 45 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD OCT PY 1993 VL 41 IS 10 BP 1730 EP 1737 DI 10.1109/22.247918 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA ML422 UT WOS:A1993ML42200010 ER PT J AU FILIPOVIC, DF GEARHART, SS REBEIZ, GM AF FILIPOVIC, DF GEARHART, SS REBEIZ, GM TI DOUBLE-SLOT ANTENNAS ON EXTENDED HEMISPHERICAL AND ELLIPTIC SILICON DIELECTRIC LENSES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID MILLIMETER-WAVE; DIPOLE; ARRAYS AB In this paper, the far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on hemispherical lenses with varying extension lengths. The radiation patterns of a double-slot antenna on a silicon dielectric lens are computed using ray-tracing inside the dielectric lens and electric and magnetic field integration on the spherical dielectric surface. The measured radiation patterns at 246 GHz and Gaussian-beam coupling efficiencies show good agreement with theory. The theoretical results are presented in extension length/radius and radius/lambda and therefore result in universal design curves for silicon lenses of different diameters and at different frequencies. The theoretical and experimental results indicate that for single units, there exists a wide range of extension lengths (ext. length/radius = 0.32 to 0.35) which result in high Gaussian-coupling efficiencies (50-60%) to moderately high f#'s. These Gaussian-coupling efficiencies can be increased to 80-90% with the use of a lambda(m)/4 matching-cap layer. For imaging array applications with high packing densities, an extension length/radius = 0.38 to 0.39 (depending on frequency) will result in peak directivity and a corresponding Gaussian-coupling efficiency 15-20% lower than for single units. RP FILIPOVIC, DF (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 28 TC 351 Z9 353 U1 1 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD OCT PY 1993 VL 41 IS 10 BP 1738 EP 1749 DI 10.1109/22.247919 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA ML422 UT WOS:A1993ML42200011 ER PT J AU BEJCZY, AK VENKATARAMAN, ST AKIN, D AF BEJCZY, AK VENKATARAMAN, ST AKIN, D TI INTRODUCTION TO THE SPECIAL ISSUE ON SPACE ROBOTICS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Editorial Material C1 UNIV MARYLAND,INST SYST RES,COLL PK,MD 20742. UNIV MARYLAND,SPACE SYST LAB,COLL PK,MD 20742. RP BEJCZY, AK (reprint author), JET PROP LAB,TELEROBOT RES PROGRAM,PASADENA,CA 91109, USA. NR 0 TC 5 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 521 EP 523 PG 3 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500001 ER PT J AU LEE, SK LEE, HS AF LEE, SK LEE, HS TI MODELING, DESIGN, AND EVALUATION OF ADVANCED TELEOPERATOR CONTROL-SYSTEMS WITH SHORT-TIME DELAY SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB A novel real-time teleoperator control system is designed and evaluated to achieve desired performance and robustness under shared compliance control and short time delays of up to a few seconds. For the design, the following are emphasized: 1) Telemonitoring force feedback is introduced as a new form of kinesthetic coupling. 2) Dynamic characteristics of the master and slave arms are actively modified based on generalized impedance control according to local design criteria. 3) The human dynamics involved in generating a control command based on visual and force stimuli are incorporated into the controller design. 4) To balance the robustness/performance trade-off, system performance is optimized subject to a known maximum time delay. The proposed teleoperator control system is simulated with modeled human dynamics in the control loop and compared with a number of conventional methods for evaluation. Simulation results suggest that the proposed control system is superior to conventional systems in terms of performance and robustness under short time delays and human control errors. Finally, experimental evidence is presented that supports the advantages of the proposed telemonitoring force feedback, and describe an experimental method for further validating the human dynamic model of teleoperation. C1 HYOSUNG IND CO LTD,SEOUL,SOUTH KOREA. UNIV SO CALIF,DEPT EE SYST & COMP SCI,LOS ANGELES,CA 90089. RP LEE, SK (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 41 TC 33 Z9 38 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 607 EP 623 DI 10.1109/70.258053 PG 17 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500010 ER PT J AU ANDARY, JF SPIDALIERE, PD AF ANDARY, JF SPIDALIERE, PD TI THE DEVELOPMENT TEST FLIGHT OF THE FLIGHT TELEROBOTIC SERVICER - DESIGN DESCRIPTION AND LESSONS LEARNED SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB The Development Test Flight (DTF-1) system design is described and the technical, operational and safety considerations that affected the design are discussed. Also discussed are the ''lessons'' that were learned during the design and early development stages in an effort to capture some of the knowledge from the program. RP ANDARY, JF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 7 TC 6 Z9 6 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 664 EP 674 DI 10.1109/70.258057 PG 11 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500014 ER PT J AU WU, EC HWANG, JC CHLADEK, JT AF WU, EC HWANG, JC CHLADEK, JT TI FAULT-TOLERANT JOINT DEVELOPMENT FOR THE SPACE-SHUTTLE REMOTE MANIPULATOR SYSTEM - ANALYSIS AND EXPERIMENT SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB The feasibility of space-based fault-tolerant robot joint design with a dual-motor, single-output differential-based mechanical drive system is investigated. The mathematical model of the differential system was developed and the inherent nonlinear dynamic characteristics for the differential were first reduced to linear state equations through variable substitutions. Nonlinear phenomena such as gearbox forward/backdrive efficiency, motor friction/stiction, and torque limiting were also included. Simulations were performed for various joint failure conditions. A scaled-down differential test-bed was subsequently designed and built to validate the analytical results. Simulation and test results demonstrated that the design is capable of sustaining a single failure and absorbing the failure disturbance, and continuing to be operational with the remaining single drive mode. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP WU, EC (reprint author), LOCKHEED ELECTR CO INC,HOUSTON,TX 77058, USA. NR 10 TC 46 Z9 50 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 675 EP 684 DI 10.1109/70.258058 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500015 ER PT J AU VENKATARAMAN, ST GULATI, S BARHEN, J TOOMARIAN, N AF VENKATARAMAN, ST GULATI, S BARHEN, J TOOMARIAN, N TI A NEURAL-NETWORK-BASED IDENTIFICATION OF ENVIRONMENTS MODELS FOR COMPLAINT CONTROL OF SPACE ROBOTS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article ID SYSTEM-IDENTIFICATION; AERIAL MOVEMENT; HUMAN-BODY; SIMULATION AB Many space robotic systems would be required to operate in uncertain or even unknown environments. In the paper, the problem of identifying such environments for compliance control is considered. In particular, neural networks are used for identifying environments that a robot establishes contact with. Both function approximation and parameter identification (with fixed nonlinear structure and unknown parameters) results are presented. The environment model structure considered is relevant to two space applications: cooperative execution of tasks by robots and astronauts, and sample acquisition during planetary exploration. Compliant motion experiments have been performed with a robotic arm, placed in contact with a single degree-of-freedom electromechanical environment. In the experiments, desired contact forces are computed using a neural network, given a desired motion trajectory. Results of the control experiments performed on robot hardware are described, along with relevant discussions. RP VENKATARAMAN, ST (reprint author), JET PROP LAB,ROBOT SYST & ADV COMP SECT,NONLINEAR SCI & INFORMAT PROC GRP,PASADENA,CA 91109, USA. NR 37 TC 15 Z9 17 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 685 EP 697 DI 10.1109/70.258059 PG 13 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500016 ER PT J AU KONDRASKE, GV VOLZ, RA JOHNSON, DH TESAR, D TRINKLE, JC PRICE, CR AF KONDRASKE, GV VOLZ, RA JOHNSON, DH TESAR, D TRINKLE, JC PRICE, CR TI NETWORK-BASED INFRASTRUCTURE FOR DISTRIBUTED REMOTE OPERATIONS AND ROBOTICS RESEARCH SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Letter AB The establishment of a unique infrastructure for distributed robotics and remote operations research within an educational environment is reported. Using a new object-oriented protocol (TelRIP) and Internet, this distributed laboratory consists of sites at four universities (Universities Space Automation and Robotics Consortium) and NASA's Johnson Space Center. The distributed laboratory configuration provides the opportunity to quantitatively study the effects of various system components and technologies on overall telerobotic task performance. We have successfully implemented and demonstrated (first in February 1991) the ability to execute representative inspection and manipulation tasks with multiple control, robot, and performance/workload monitoring sites simultaneously connected. Operations are carried out on a routine basis. During the process, needs for hardware and software standards development have been identified. The current implementation provides the basis to link government, industrial, and university facilities to a truly collaborative research and development environment, enabling graduate students to experience rich educational opportunities that would otherwise not be possible. C1 TEXAS A&M UNIV,DEPT COMP SCI,COLL STN,TX 77843. RICE UNIV,DEPT ELECT & COMP ENGN,HOUSTON,TX 77251. BRC MERB ROBOTICS,AUSTIN,TX 78712. NASA,LYNDON B JOHNSON SPACE CTR,DIV AUTOMAT & ROBOTICS,HOUSTON,TX 77058. RP KONDRASKE, GV (reprint author), UNIV TEXAS,INST HUMAN PERFORMANCE,POB 19180,ARLINGTON,TX 76019, USA. NR 8 TC 19 Z9 19 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1993 VL 9 IS 5 BP 702 EP 704 DI 10.1109/70.258062 PG 3 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA MU755 UT WOS:A1993MU75500018 ER PT J AU FILIPOVIC, DF REBEIZ, GM AF FILIPOVIC, DF REBEIZ, GM TI DOUBLE-SLOT ANTENNAS ON EXTENDED HEMISPHERICAL AND ELLIPTIC QUARTZ DIELECTRIC LENSES SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article AB In this paper, the theoretical far-field patterns and Gaussian-beam coupling efficiencies are investigated for a double-slot antenna placed on quartz hemispherical lenses with varying extension lengths. The radiation patterns of the double-slot antenna are computed using ray-tracing inside the lens and electric and magnetic field integration on the spherical dielectric surface. The theoretical results are equally valid for double-dipole, log-periodic, and spiral antennas, and are presented in extension length/radius and radius/lambda. Therefore, the results yield universal design curves for quartz lenses of different diameters and at different frequencies and using different antennas. The results indicate that for single units, there exists a wide range of extension lengths (ext. length/radius=0.61 to 0.76) which result in high Gaussian-coupling efficiencies to moderately high f/# systems. For imaging array applications with high packing densities, an extension length/radius=0.82 to 0.93 (depending on frequency) will result in peak directivity and highest packing density but lower Gaussian-coupling efficiencies. RP FILIPOVIC, DF (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 13 TC 14 Z9 14 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD OCT PY 1993 VL 14 IS 10 BP 1905 EP 1924 DI 10.1007/BF02096363 PG 20 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA MC217 UT WOS:A1993MC21700003 ER PT J AU ELEFTHERIADES, GV REBEIZ, GM AF ELEFTHERIADES, GV REBEIZ, GM TI SELF AND MUTUAL ADMITTANCE OF SLOT ANTENNAS ON A DIELECTRIC HALF-SPACE SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article ID ARRAYS; ELEMENTS; DIPOLE AB In this paper, an efficient implementation of the spectral domain moment technique is presented for computing the self and mutual coupling between slot antennas on a dielectric half-space. It is demonstrated that by the proper selection of the weighting functions in the method of moments, the analytic evaluation or simplification of the transverse moment integrals is enabled. This results into a significant reduction of the required computational labor. The method is then utilized in order to provide design data for the self and mutual admittances between two slot antennas on a dielectric substrate lens in the case of fused quartz (epsilon(r) = 3.80), crystal quartz (epsilon(r) = 4.53), silicon (epsilon(r) = 11.9) and GaAs (epsilon(r) = 12.8). The presented technique and associated results are useful when designing twin slot quasi-optical receivers, imaging arrays, phased arrays or power-combining arrays of slot elements at millimeter-wave frequencies. RP ELEFTHERIADES, GV (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 18 TC 30 Z9 31 U1 0 U2 3 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD OCT PY 1993 VL 14 IS 10 BP 1925 EP 1946 DI 10.1007/BF02096364 PG 22 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA MC217 UT WOS:A1993MC21700004 ER PT J AU CHEN, W LEE, KF DAHELE, JS LEE, RQ AF CHEN, W LEE, KF DAHELE, JS LEE, RQ TI CAD FORMULAS FOR RESONANT FREQUENCIES OF TM01 AND TM10 MODES OF RECTANGULAR PATCH ANTENNA WITH SUPERSTRATE SO INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE COMPUTER-AIDED ENGINEERING LA English DT Article ID MICROSTRIP ANTENNAS; DIELECTRIC COVER; INPUT IMPEDANCE AB Curve-fitting formulas based on moment method results are presented for the normalized resonant frequencies of the TM01 and TM10 modes of a rectangular patch antenna covered with a superstrate. The formulas can be used for a wide range of substrate and superstrate thicknesses and permittivities. Although they are obtained by fitting data points with aspect ratio a/b = 1.5, the formulas are found to be useful for a/b between 1.3 and 1.8. Comparison with measured data is given. (C) 1993 John Wiley & Sons, Inc. C1 ROYAL MIL COLL SCI,DEPT ELECT ENGN & SCI,SWINDON SN6 8LA,WILTS,ENGLAND. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHEN, W (reprint author), UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606, USA. NR 8 TC 0 Z9 0 U1 1 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 1050-1827 J9 INT J MICROWAVE MILL JI Int. J. Microw. Millimeter-Wave Comput.-Aided Eng. PD OCT PY 1993 VL 3 IS 4 BP 340 EP 349 DI 10.1002/mmce.4570030406 PG 10 WC Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA LY049 UT WOS:A1993LY04900005 ER PT J AU DIB, N PONCHAK, G KATEHI, L AF DIB, N PONCHAK, G KATEHI, L TI COMMENTS ON APPROXIMATING RADIATION - RESPONSE SO INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE COMPUTER-AIDED ENGINEERING LA English DT Letter C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DIB, N (reprint author), UNIV MICHIGAN,DEPT EECS,ANN ARBOR,MI 48109, USA. OI Dib, Nihad/0000-0002-2263-5512 NR 3 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 1050-1827 J9 INT J MICROWAVE MILL JI Int. J. Microw. Millimeter-Wave Comput.-Aided Eng. PD OCT PY 1993 VL 3 IS 4 BP 458 EP 458 DI 10.1002/mmce.4570030419 PG 1 WC Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA LY049 UT WOS:A1993LY04900018 ER PT J AU LULLA, K HOLLAND, SD AF LULLA, K HOLLAND, SD TI NASA ELECTRONIC STILL CAMERA (ESC) SYSTEM USED TO IMAGE THE KAMCHATKA VOLCANOS FROM THE SPACE-SHUTTLE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article RP LULLA, K (reprint author), NASA,JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD OCT PY 1993 VL 14 IS 15 BP 2745 EP 2746 PG 2 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA MF907 UT WOS:A1993MF90700001 ER PT J AU WANG, Y IMHOFF, ML AF WANG, Y IMHOFF, ML TI SIMULATED AND OBSERVED L-HH RADAR BACKSCATTER FROM TROPICAL MANGROVE FORESTS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID L-BAND; VEGETATION; SCATTERING; STANDS; MODEL AB We applied the Santa Barbara canopy backscatter model to model radar backscatter from mangrove forest stands in the Ganges delta of southern Bangladesh, and assessed the feasibility of delineating flooding boundaries within the stands. Modelled L-band (0.235 m wavelength) HH backscatter showed that canopy volume scattering dominated for stands under nonflooded ground surface. Double bounce trunk-ground term were enhanced by the presence of water under trees. For flooded mangrove forest, the trunk-ground term was dominant at small radar incidence angles; the trunk-ground term dominancy reduced as the incidence angle increased. Shuttle Imaging Radar (SIR-B) data and model results showed that for the mangrove forest, radar data with small incidence angles should be used to delineate the flooding boundaries. C1 NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. UNIV CALIF SANTA BARBARA,CTR REMOTE SENSING & ENVIRONM OPT,SANTA BARBARA,CA 93106. RI wang, yong/I-2004-2013 NR 20 TC 16 Z9 22 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD OCT PY 1993 VL 14 IS 15 BP 2819 EP 2828 PG 10 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA MF907 UT WOS:A1993MF90700007 ER PT J AU JOHNSTON, JC THOMPSON, DA AF JOHNSTON, JC THOMPSON, DA TI VISUALIZATION AND ANIMATION IN MANUFACTURING AND MATERIALS SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article C1 UNIV AKRON,AKRON,OH 44325. RP JOHNSTON, JC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD OCT PY 1993 VL 45 IS 10 BP 14 EP 19 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA MB381 UT WOS:A1993MB38100002 ER PT J AU POTTER, BD YUAN, FG PATER, RH AF POTTER, BD YUAN, FG PATER, RH TI THE EFFECT OF MOLECULAR-WEIGHT ON TRANSVERSE MICROCRACKING IN HIGH-TEMPERATURE LARC-RP46T POLYIMIDE COMPOSITES SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB This experimental study examines the role of molecular weight as well as crosslink density on the microcrack resistance in high-temperature LaRC-RP46T composites. LaRC-RP46T polyimides are prepared by in-situ polymerization of three monomer reactants: monoisopropyl ester of 5-norbornene-2, 3-dicarboxylic acid (NE); 3,4'-oxydianiline (3,4'-ODA); and diisopropyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid (BTDE). Five formulations were prepared, in which formulated molecular weight between crosslink sites varies from 1,500 to 21,000 g/mole. By varying the molecular weight betr,een the crosslink sires, a series of five resin systems with different crosslink densities was produced. Cross-ply composite laminates were compression molded from each formulation and IM-7 graphite fibers and were cut into a series of triangular test specimens. These test specimens were then subjected to 1,500 thermal cycles in order to investigate the damage associated with thermal cycling. The extent of the microcrack damage was determined by measuring the number of transverse microcracks and by noting changes in the density and moisture absorption of each specimen. C1 NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665. RP POTTER, BD (reprint author), N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695, USA. NR 7 TC 6 Z9 6 U1 2 U2 2 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 1993 VL 25 IS 1 BP 30 EP 34 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA MW920 UT WOS:A1993MW92000004 ER PT J AU SAWKO, PM TRAN, D AF SAWKO, PM TRAN, D TI EFFECTS OF WEAVE ARCHITECTURE ON AEROACOUSTIC PERFORMANCE OF CERAMIC INSULATION BLANKETS SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB A comparison of sewn, quilted Advanced Flexible Reusable Surface Insulation (AFRSI) blankets and integrally woven core Tailorable Advanced Blanket Insulation (TABI) systems was conducted in a 170 decibel aeroacoustic environment under oscillating air loads. Preconditioning in a radiant heat source was done at both 2,000 degrees F and 2,500 degrees F before testing. It was shown. that a multilayer weave construction based on an angle interlock weave architecture was superior to other systems investigated and did not require a surface coating to enhance survivability. Single-ply TABI fabric surfaces using an insulated integrally woven core structure can survive up to 2,000 degrees F without the use of a ceramic coating to toughen the surface to the aeroacoustic noise level. AFRSI blankets required a ceramic coating in order to demonstrate comparable performance after exposure to a 2,000 degrees F radiant heat temperature. C1 SAN JOSE STATE UNIV,DEPT AEROSPACE ENGN,SAN JOSE,CA. RP SAWKO, PM (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 1993 VL 25 IS 1 BP 51 EP 57 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA MW920 UT WOS:A1993MW92000007 ER PT J AU MIYOSHI, K WU, RLC GARSCADDEN, A BARNES, PN JACKSON, HE AF MIYOSHI, K WU, RLC GARSCADDEN, A BARNES, PN JACKSON, HE TI FRICTION AND WEAR OF PLASMA-DEPOSITED DIAMOND FILMS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CHEMICAL-VAPOR-DEPOSITION; GROWTH AB Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus, the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02-0.04 in humid air and in dry nitrogen, but 1.5-1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen. C1 UNIVERSAL ENERGY SYST INC, DAYTON, OH 45432 USA. WRIGHT LAB, WRIGHT PATTERSON AFB, DAYTON, OH 45433 USA. UNIV CINCINNATI, DEPT PHYS, CINCINNATI, OH 45221 USA. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RI Jackson, Howard/K-4881-2012 NR 20 TC 64 Z9 64 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-8979 EI 1089-7550 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 1 PY 1993 VL 74 IS 7 BP 4446 EP 4454 DI 10.1063/1.354386 PG 9 WC Physics, Applied SC Physics GA MB177 UT WOS:A1993MB17700024 ER PT J AU HERMES, LG WITT, A SMITH, SD KLINGLEWILSON, D MORRIS, D STUMPF, GJ EILTS, MD AF HERMES, LG WITT, A SMITH, SD KLINGLEWILSON, D MORRIS, D STUMPF, GJ EILTS, MD TI THE GUST-FRONT DETECTION AND WIND-SHIFT ALGORITHMS FOR THE TERMINAL DOPPLER WEATHER RADAR SYSTEM SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB The Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR) system was primarily designed to address the operational needs of pilots in the avoidance of low-altitude wind shears upon takeoff and landing at airports. One of the primary methods of wind-shear detection for the TDWR system is the gust-front detection algorithm. The algorithm is designed to detect gust fronts that produce a wind-shear hazard and/or sustained wind shifts. It serves the hazard warning function by providing an estimate of the wind-speed gain for aircraft penetrating the gust front. The gust-front detection and wind-shift algorithms together serve a planning function by providing forecasted gust-front locations and estimates of the horizontal wind vector behind the front, respectively. This information is used by air traffic managers to determine arrival and departure runway configurations and aircraft movements to minimize the impact of wind shifts on airport capacity. This paper describes the gust-front detection and wind-shift algorithms to be fielded in the initial TDWR systems. Results of a quantitative performance evaluation using Doppler radar data collected during TDWR operational demonstrations at the Denver, Kansas City, and Orlando airports are presented. The algorithms were found to be operationally useful by the FAA airport controllers and supervisors. RP HERMES, LG (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,NOAA,SPACEFLIGHT METEOROL GRP ZS8,BLDG 30,ROOM 2104,HOUSTON,TX 77058, USA. NR 0 TC 6 Z9 10 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD OCT PY 1993 VL 10 IS 5 BP 693 EP 709 DI 10.1175/1520-0426(1993)010<0693:TGFDAW>2.0.CO;2 PG 17 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA LY374 UT WOS:A1993LY37400005 ER PT J AU CARPENTER, MH GOTTLIEB, D ABARBANEL, S AF CARPENTER, MH GOTTLIEB, D ABARBANEL, S TI THE STABILITY OF NUMERICAL BOUNDARY TREATMENTS FOR COMPACT HIGH-ORDER FINITE-DIFFERENCE SCHEMES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID APPROXIMATIONS RP CARPENTER, MH (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23681, USA. NR 16 TC 200 Z9 209 U1 2 U2 13 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT PY 1993 VL 108 IS 2 BP 272 EP 295 DI 10.1006/jcph.1993.1182 PG 24 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA MC593 UT WOS:A1993MC59300008 ER PT J AU ZINGG, DW LOMAX, H AF ZINGG, DW LOMAX, H TI FINITE-DIFFERENCE SCHEMES ON REGULAR TRIANGULAR GRIDS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ZINGG, DW (reprint author), UNIV TORONTO,INST AEROSPACE STUDIES,TORONTO M3H 5T6,ON,CANADA. NR 7 TC 13 Z9 13 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT PY 1993 VL 108 IS 2 BP 306 EP 313 DI 10.1006/jcph.1993.1184 PG 8 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA MC593 UT WOS:A1993MC59300010 ER PT J AU BAKUCKAS, JG JOHNSON, WS BIGELOW, CA AF BAKUCKAS, JG JOHNSON, WS BIGELOW, CA TI FATIGUE DAMAGE IN CROSS-PLY TITANIUM METAL-MATRIX COMPOSITES CONTAINING CENTER HOLES SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB The development of fatigue damage in four [0/90]s SCS-6/Ti-15-3 laminates containing center holes was investigated. A methodology to predict damage initiation based on an effective strain parameter was used to determine the stress levels and the number of cycles required for matrix crack initiation. Damage progression was monitored at various stages of fatigue loading. In general, a saturated state of damage consisting of matrix cracks and fiber-matrix debonding was obtained which reduced the composite modulus. Matrix cracks were bridged by the 0-degrees fibers. The fatigue limit (stress causing catastrophic fracture of the laminates) was also determined. The static and post-fatigue residual strengths were accurately predicted using a three dimensional elastic-plastic finite element analysis. The matrix damage that occurred during fatigue loading significantly reduced the notched strength. C1 NASA,LANGLEY RES CTR,DIV MAT,MECH MAT BRANCH,HAMPTON,VA 23681. RP BAKUCKAS, JG (reprint author), NASA,LANGLEY RES CTR,NATL RES COUNCIL,HAMPTON,VA 23681, USA. NR 19 TC 10 Z9 10 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD OCT PY 1993 VL 115 IS 4 BP 404 EP 410 DI 10.1115/1.2904238 PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA ME172 UT WOS:A1993ME17200013 ER PT J AU KAISER, MK MOWAFY, L AF KAISER, MK MOWAFY, L TI OPTICAL SPECIFICATION OF TIME-TO-PASSAGE - OBSERVERS SENSITIVITY TO GLOBAL TAU SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID DEPTH-PERCEPTION; INFORMATION; COLLISION; FLOW; NEURONS; CONTACT AB Despite its general mathematical formulation, most empirical work on the visual perception of tau (defined as a quantity divided by its temporal derivative) has focused on the case of direct approach, with tau defined as image angle/rate of expansion. Empirical investigators tend to generalize image size analyses to off-axis approaches. However, this generalization is inappropriate for all but a few classes of objects. After mathematically reestablishing the appropriate optical cues specifying time to passage for noncollision cases, we report a series of studies in which we examined observers' sensitivities to this information in both relative- and absolute-judgment paradigms. In general, we found observers' judgments to be accurate and robust. C1 UNIV DAYTON,FLIGHT TRAINING RES SUPPORT GRP,DAYTON,OH 45469. RP KAISER, MK (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MAIL STOP 262-3,MOFFETT FIELD,CA 94035, USA. NR 26 TC 95 Z9 95 U1 1 U2 4 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD OCT PY 1993 VL 19 IS 5 BP 1028 EP 1040 DI 10.1037//0096-1523.19.5.1028 PG 13 WC Psychology; Psychology, Experimental SC Psychology GA MB176 UT WOS:A1993MB17600007 PM 8228837 ER PT J AU JIMENEZ, J WRAY, AA SAFFMAN, PG ROGALLO, RS AF JIMENEZ, J WRAY, AA SAFFMAN, PG ROGALLO, RS TI THE STRUCTURE OF INTENSE VORTICITY IN ISOTROPIC TURBULENCE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID INTERMITTENCY; DISSIPATION AB The structure of the intense-vorticity regions is studied in numerically simulated homogeneous, isotropic, equilibrium turbulent flow fields at four different Reynolds numbers, in the range Re(lambda) = 35-170. In accordance with previous investigators this vorticity is found to be organized in coherent, cylindrical or ribbon-like. vortices ('worms'). A statistical study suggests that they are simply especially intense features of the background, O(omega'), vorticity. Their radii scale with the Kolmogorov microscale and their lengths with the integral scale of the flow. An interesting observation is that the Reynolds number gamma/nu, based on the circulation of the intense vortices, increases monotonically with Re(lambda), raising the question of the stability of the structures in the limit of Re(lambda) --> infinity. Conversely, the average rate of stretching of these vortices increases only slowly with their peak vorticity, suggesting that self-stretching is not important in their evolution. One- and two-dimensional statistics of vorticity and strain are presented; they are non-Gaussian and the behaviour of their tails depends strongly on the Reynolds number. There is no evidence of convergence to a limiting distribution in this range of Re(lambda), even though the energy spectra and the energy dissipation rate show good asymptotic properties in the higher-Reynolds-number cases. Evidence is presented to show that worms are natural features of the flow and that they do not depend on the particular forcing scheme. C1 CALTECH,PASADENA,CA 91125. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SCH AERONAUT,E-28040 MADRID,SPAIN. RP JIMENEZ, J (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI jimenez, javier/A-6691-2008 OI jimenez, javier/0000-0003-0755-843X NR 25 TC 572 Z9 575 U1 6 U2 38 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD OCT PY 1993 VL 255 BP 65 EP 90 DI 10.1017/S0022112093002393 PG 26 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MF298 UT WOS:A1993MF29800004 ER PT J AU CHOI, H MOIN, P KIM, J AF CHOI, H MOIN, P KIM, J TI DIRECT NUMERICAL-SIMULATION OF TURBULENT-FLOW OVER RIBLETS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID DRAG REDUCTION; BOUNDARY-LAYER; SKIN FRICTION; WALL; CHANNEL; SURFACES AB Direct numerical simulations of turbulent flows over riblet-mounted surfaces are performed to educe the mechanism of drag reduction by riblets. The computed drag on the riblet surfaces is in good agreement with the existing experimental data. The mean-velocity profiles show upward and downward shifts in the log-law for drag-decreasing and drag-increasing cases, respectively. Turbulence statistics above the riblets are computed and compared with those above a flat plate. Differences in the mean-velocity profile and turbulence quantities are found to be limited to the inner region of the boundary layer. Velocity and vorticity fluctuations as well as the Reynolds shear stresses above the riblets are reduced in drag-reducing configurations. Quadrant analysis indicates that riblets mitigate the positive Reynolds-shear-stress-producing events in drag-reducing configurations. From examination of the instantaneous flow fields, a drag reduction mechanism by riblets is proposed: riblets with small spacings reduce viscous drag by restricting the location of the streamwise vortices above the wetted surface such that only a limited area of the riblets is exposed to the downwash of high-speed fluid that the vortices induce. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CHOI, H (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI Choi, Haecheon/D-1016-2011; OI Choi, Haecheon/0000-0003-0696-847X; Kim, John/0000-0002-6369-9264 NR 47 TC 260 Z9 277 U1 6 U2 56 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD OCT PY 1993 VL 255 BP 503 EP 539 DI 10.1017/S0022112093002575 PG 37 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA MF298 UT WOS:A1993MF29800022 ER PT J AU CHAO, JK LYU, LH WU, BH LAZARUS, AJ CHANG, TS LEPPING, RP AF CHAO, JK LYU, LH WU, BH LAZARUS, AJ CHANG, TS LEPPING, RP TI OBSERVATIONS OF AN INTERMEDIATE SHOCK IN INTERPLANETARY SPACE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DISCONTINUITIES; EVOLUTION AB An interplanetary intermediate shock is identified from the bulk velocity, number density, and temperature of the solar wind protons and the three components of the interplanetary magnetic field observed by Voyager 1 on May 1 (day 122), 1980, when the spacecraft was at a distance of about 9 AU from the Sun. It is shown by a best fit procedure that the measured plasma and magnetic field on both sides of the discontinuity satisfy the Rankine-Hugoniot relations for a magnetohydrodynamic (MHD) intermediate shock. This shock satisfies the following conditions. (1) The normal Alfven-Mach number (M(A) = V(B)*/V(A) is greater than unity in the preshock state and less than unity in the postshock state. (2) Both the fast-mode Mach number (M(f) = V(n)*/V(f)) in the preshock state and the slow-mode Mach number (M(sl) = V(n)*/V(sl)) in the postshock state are less than unity, but the slow-mode Mach number is greater than unity in the preshock state. (3) The projected components of the magnetic fields in the shock front for the pre- and postshock states have opposite signs. (4) The magnitudes of the magnetic fields decrease from the preshock to the postshock states. In the above expression, V(A) is the Alfven speed based on the magnetic field component normal to the shock front, V(n)* is the component of the bulk velocity normal to the shock front and measured in the shock frame of reference, and V(f) and V(sl) are the speeds of the fast- and slow- mode magnetosonic waves in the direction of the shock normal, respectively. The discontinuity event in our discussion cannot be a rotational discontinuity because the Walen's relation is not satisfied. The identified intermediate, shock has M(A) = 1.04, theta(Bn) =37-degrees, and beta =0.56, where theta(Bn) is the angle between the preshock magnetic field and the shock normal direction and beta is the ratio of thermal to magnetic energy densities. Using these parameters, a numerical solution of the MHD equations for the shock is obtained. The simulated profiles of the bulk velocity, number density, temperature, and magnetic fields of the pre-and postshock states agree with those of the observed values. The same parameters are used to simulate an intermediate shock using a hybrid numerical code in which full ion dynamics is retained while electron inertial force is neglected. The results of this simulation are compared with high-resolution magnetic field data with a time resolution of 1.92-s averages. The shock thickness of about 70 c/omega(pi) predicted from the hybrid code agrees with the observations. The general behavior of the magnetic field in the shock transition region is also very similar for the simulated and observed results. The macro- and microstructures of the intermediate shock obtained from the MHD and hybrid models resemble the observed structures. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20770. RP CHAO, JK (reprint author), NATL CENT UNIV,INST SPACE SCI,CHUNGLI 32054,TAIWAN. NR 25 TC 28 Z9 33 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1993 VL 98 IS A10 BP 17443 EP 17450 DI 10.1029/93JA01609 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA457 UT WOS:A1993MA45700018 ER PT J AU BURLAGA, LF NESS, NF AF BURLAGA, LF NESS, NF TI LARGE-SCALE DISTANT HELIOSPHERIC MAGNETIC-FIELD - VOYAGER-1 AND VOYAGER-2 OBSERVATIONS FROM 1986 THROUGH 1989 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SECTOR STRUCTURE AB We analyze the magnetic field observed by Voyagers 1 and 2 (V1 and V2) as solar activity increased from near minimum in 1986 to near maximum at the end of 1989. The radial distance of V1 and V2 increased from 25.4 to 39.9 AU and from 18.9 to 30.2 AU, respectively. The elevation angle of the magnetic field observed by both V1 and V2 for each of the years was delta = 0-degrees +/- 4.5-degrees. The azimuthal angle A was consistent with Parker's spiral angle when the solar activity was low but not during 1988 and 1989 when there were many transient ejecta. V1 observed predominantly a single negative polarity from 1986 through 1988, when its latitude was in the range 27.8-degrees-30.8-degrees-N, because the heliospheric current sheet (HCS) was below V1. V1 observed both polarities during 1989, when the maximum latitude of the HCS was far above V1. During 1988 and 1989, V2 observed sectors but no sector pattern, even though an extrapolation of the neutral line near the Sun would imply a two-sector pattern. This indicates a significant radial evolution of the sector structure and the HCS. We suggest that the numerous transient ejecta perturb the HCS and the radial positions of the sector boundaries randomly when the Sun is active. There was no relation among the sector boundaries, sectors, and interaction regions at either V1 or V2. This implies a considerable evolution of the relation between interaction regions and sector boundaries with increasing distance from the Sun. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 28 TC 24 Z9 24 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1993 VL 98 IS A10 BP 17451 EP 17460 DI 10.1029/93JA01475 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA457 UT WOS:A1993MA45700019 ER PT J AU BURLAGA, LF AF BURLAGA, LF TI INTERMITTENT TURBULENCE IN LARGE-SCALE VELOCITY FLUCTUATIONS AT 1 AU NEAR SOLAR MAXIMUM SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FULLY-DEVELOPED TURBULENCE; MULTIFRACTAL STRUCTURE; SPECTRAL SIGNATURES; RECURRENT STREAMS; FLUID TURBULENCE; MAGNETIC-FIELD; WIND; 1-AU; FRACTALS; FLOWS AB The large-scale fluctuations of the bulk speed at 1 AU near solar maximum, from day 1 through day 365, 1979 exhibit multifractal scaling over the range from 8 hours to 2.7 days. The observations are consistent with the binomial cascade model of intermittent turbulence proposed by Meneveau and Sreenivasan (1987a). The intermittency exponent computed from these observations is mu = 0.19 +/- 0.02, which is consistent with the best estimate mu = 0.025 +/- 0.05 obtained from earth-based measurements of intermittent turbulence (Sreenivasan and Kailasnath, 1993). Thus the complicated speed fluctuations observed over this range of periods at 1 AU near solar maximum are described by a simple relation for the inertial range of intermittent turbulence. The multifractal structure of these fluctuations differs from that associated with the large-scale fluctuations observed during 1974 when corotating streams were dominant. In both cases the distribution of speed differences was exponential. There appears to be a solar cycle variation in the spectral exponent describing the large-scale speed fluctuations. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 42 TC 44 Z9 44 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1993 VL 98 IS A10 BP 17467 EP 17473 DI 10.1029/93JA01630 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA457 UT WOS:A1993MA45700021 ER PT J AU WHITTEN, RC BARNES, A MCCORMICK, PT AF WHITTEN, RC BARNES, A MCCORMICK, PT TI PLASMA MOTION IN THE VENUS IONOSPHERE - TRANSITION TO SUPERSONIC-FLOW - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article C1 SANTA CLARA UNIV,DEPT PHYS,SANTA CLARA,CA 95053. RP WHITTEN, RC (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 4 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1993 VL 98 IS A10 BP 17489 EP 17489 DI 10.1029/93JA00722 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA457 UT WOS:A1993MA45700024 ER PT J AU AIKIN, AC HEDIN, AE KENDIG, DJ DRAKE, S AF AIKIN, AC HEDIN, AE KENDIG, DJ DRAKE, S TI THERMOSPHERIC MOLECULAR-OXYGEN MEASUREMENTS USING THE ULTRAVIOLET SPECTROMETER ON THE SOLAR MAXIMUM MISSION SPACECRAFT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ATMOSPHERE EXPLORER; TEMPERATURE AB The technique of solar occultation has been utilized to measure molecular oxygen densities in the 140- to 220- km altitude region. The ultraviolet spectrometer/polarimeter on the Solar Maximum Mission (SMM) spacecraft was operated in the occultation mode between 1985 and the end of 1989, at wavelengths of 137.46 and 139.06 nm. This covered the period from the solar sunspot minimum in 1986 to December 1989 when solar activity was near the sunspot maximum. The observed solar area was 10x10 arc s2, which yields O2 concentrations with an altitude resolution of 0.17 km. These molecular oxygen data are compared with O2 data obtained under similar conditions of local time, location, and solar activity using other techniques. SMM data are also compared with the mass spectrometer/incoherent scatter (MSIS) - 86 model. Good agreement is found near 150 km for several O2 temporal variations including the annual cycle, local time, solar activity, and magnetic activity. Unlike the model, the measured density profiles exhibit no significant increase with increasing solar activity. The disagreement of the SMM O2 data with the MSIS-86 model increases with increasing altitude. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOCIATES,GREENBELT,MD 20771. HUGHES STX CORP,LANHAM,MD. RP AIKIN, AC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 916,GREENBELT,MD 20771, USA. NR 32 TC 13 Z9 13 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1993 VL 98 IS A10 BP 17607 EP 17613 DI 10.1029/93JA01468 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MA457 UT WOS:A1993MA45700035 ER PT J AU WHITTENBERGER, JD AF WHITTENBERGER, JD TI EFFECT OF LONG-TERM 1093-K EXPOSURE TO AIR OR VACUUM ON THE STRUCTURE OF SEVERAL WROUGHT SUPERALLOYS SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article; Proceedings Paper CT INTERNATIONAL AEROMAT 93 CONF : PROCESSING/SYNTHESIS OF MATERIALS CY JUN 06-09, 1993 CL ANAHEIM, CA SP AMER SOC MET INT DE HEAT TREATMENT; OXIDATION; SUPERALLOYS; VACUUM EXPOSURE ID LIF-22CAF2 AB Long-term 1093 K heat treatments of three commercial superalloy sheet materials were undertaken in air and vacuum. With either exposure, significant precipitation of second phases occurred in the Co-base Haynes(R) Alloy 188 (HA 188) and the Ni-base Haynes(R) Alloy 230 (HA 230); however, much less precipitation was found in the exposed Ni-base alloy Inconel(R) 617 (IN 617). Although some grain growth occurred in HA 188, no changes in the grain size of either RA 230 or IN 617 were observed after 22,500 h at temperature. Oxidation during air heat treatments led to weight gain due to the formation of chromia + spinel scales and surface-connected grain boundary pits/oxides in all three superalloys. Both the weight gain and depth of intergranular attack were dependent on the square root of time, which is indicative of diffusion-controlled phenomena. Because many alloy samples had neighbors in close proximity, most vacuum heat treated specimens did not suffer significant loss of volatile elements. However, some exposed samples were subjected to unrestricted vacuum heat treatments, allowing estimates of volatilization to be made. Based on the data for HA 188, the weight loss during 1093 K vacuum exposure was diffusion controlled once the inhibiting effects of surface films on the as-received alloys were broken down. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 11 Z9 11 U1 1 U2 5 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD OCT PY 1993 VL 2 IS 5 BP 745 EP 758 DI 10.1007/BF02650066 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA MH538 UT WOS:A1993MH53800016 ER PT J AU PHAN, M HORTA, LG JUANG, JN LONGMAN, RW AF PHAN, M HORTA, LG JUANG, JN LONGMAN, RW TI LINEAR-SYSTEM IDENTIFICATION VIA AN ASYMPTOTICALLY STABLE OBSERVER SO JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS LA English DT Article DE SYSTEM IDENTIFICATION; OBSERVER IDENTIFICATION; POLE PLACEMENT; STATE SPACE REALIZATION; MARKOV PARAMETERS; OBSERVER MARKOV PARAMETERS AB This paper presents a formulation for identification of linear multivariable systems from single or multiple sets of input-output data. The system input-output relationship is expressed in terms of an observer, which is made asymptotically stable by an embedded eigenvalue assignment procedure. The prescribed eigenvalues for the observer may be real, complex, mixed real and complex, or zero corresponding to a deadbeat observer. In this formulation, the Markov parameters of the observer are first identified from input-output data. The Markov parameters of the actual system are then recovered from those of the observer and used to realize a state space model of the system. The basic mathematical formulation is derived, and numerical examples are presented to illustrate the proposed method. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. COLUMBIA UNIV,NEW YORK,NY. RP PHAN, M (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA, USA. NR 12 TC 43 Z9 46 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-3239 J9 J OPTIMIZ THEORY APP JI J. Optim. Theory Appl. PD OCT PY 1993 VL 79 IS 1 BP 59 EP 86 DI 10.1007/BF00941887 PG 28 WC Operations Research & Management Science; Mathematics, Applied SC Operations Research & Management Science; Mathematics GA MJ997 UT WOS:A1993MJ99700004 ER PT J AU FU, LL FUKUMORI, I MILLER, RN AF FU, LL FUKUMORI, I MILLER, RN TI FITTING DYNAMIC-MODELS TO THE GEOSAT SEA-LEVEL OBSERVATIONS IN THE TROPICAL PACIFIC-OCEAN .2. A LINEAR, WIND-DRIVEN MODEL SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID DATA ASSIMILATION; EQUATORIAL OCEAN; ROSSBY WAVES; KALMAN FILTER; EL-NINO; STRESS; TIME AB The Geosat altimeter sea level observations in the tropical Pacific Ocean are used to evaluate the performance of a linear wind-driven equatorial wave model. The question posed is the extent to which such a model can describe the observed sea level variations. The Kalman filter and optimal smoother are used to obtain a solution that is an optimal fit to the observation in a weighted least-squares sense. The total mean variance of the Geosat sea level observation is 98.1 cm2, of which 36.6 cm2 is due to measurement errors, leaving 61.5 cm2 for the oceanographic signal to be explained. The model is found to account for about 68% of this signal variance, and the remainder is ascribed to the effects of physical mechanisms missing from the model. This result suggests that the Geosat data contains sufficient information for testing yet more sophisticated models. Utility of an approximate filter and smoother based on the asymptotic time limit of the estimation error covariance is also examined and compared with the estimates of the full time-evolving filter. The results are found to be statistically indistinguishable from each other, but the computational requirements are more than an order of magnitude less for the approximate filter/smoother. Corrections to the wind field that drives the model are also obtained by the smoother, but they are found only to be marginally improved when compared with in situ wind measurements. The substantial errors in the Geosat data and the simplicity of the present model prevents a reliable wind estimate from being made. C1 OREGON STATE UNIV,COLL OCEANOG,CORVALLIS,OR 97331. RP FU, LL (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 35 TC 56 Z9 57 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1993 VL 23 IS 10 BP 2162 EP 2181 DI 10.1175/1520-0485(1993)023<2162:FDMTTG>2.0.CO;2 PG 20 WC Oceanography SC Oceanography GA MC027 UT WOS:A1993MC02700002 ER PT J AU PHILLIPS, OM GU, DF WALSH, EJ AF PHILLIPS, OM GU, DF WALSH, EJ TI ON THE EXPECTED STRUCTURE OF EXTREME WAVES IN A GAUSSIAN SEA .2. SWADE SCANNING RADAR ALTIMETER MEASUREMENTS SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Note ID SURFACE CONTOUR RADAR; SPECTRA AB In a previous paper (Phillips et al.) an approximate theory was developed that predicted that the expected configuration of extreme waves in a random sea (or the average configuration of an ensemble of extreme waves) is proportional to the space-time autocorrelation function of the surface displacement of the wave field as a whole. This result is tested by examination of scanning radar altimeter measurements made during SWADE in four different sea states, including a unimodal mature wave field, a short fetch, a wind-generated sea crossing swell, a very broad directional spectrum, and a fetch-limited wind sea with opposing swell. In each of these, the spatial autocorrelation function was found directly from the SRA data. The highest waves in each dataset were selected and their configurations averaged with respect to the crest. These averaged configurations were in each case found to be consistent with the autocorrelation function. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP PHILLIPS, OM (reprint author), JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,OLIN HALL,3400 N CHARLES ST,BALTIMORE,MD 21218, USA. NR 12 TC 37 Z9 37 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1993 VL 23 IS 10 BP 2297 EP 2309 DI 10.1175/1520-0485(1993)023<2297:OTESOE>2.0.CO;2 PG 13 WC Oceanography SC Oceanography GA MC027 UT WOS:A1993MC02700009 ER PT J AU MARGOLIS, JS AF MARGOLIS, JS TI MEASUREMENT OF HYDROGEN-BROADENED METHANE LINES IN THE NU(4) BAND AT 296-K AND 200-K SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB Hydrogen-broadening of a large number of methane lines in the nu4 band has been measured at room temperature and 200 K (determined from the rotational temperature). The measurements were obtained using the KPNO McMath FTS with spectral resolution of 0.005 cm-1 and a signal-to-noise ratio of 100 or more. Hydrogen pressures between 250 and 600 torr and methane pressures up to 2 torr were utilised. The spectra were analyzed using a parametrised least-squares fitting procedure. RP MARGOLIS, JS (reprint author), JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 183-301,PASADENA,CA 91109, USA. NR 10 TC 21 Z9 21 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT PY 1993 VL 50 IS 4 BP 431 EP 441 DI 10.1016/0022-4073(93)90073-Q PG 11 WC Optics; Spectroscopy SC Optics; Spectroscopy GA LY895 UT WOS:A1993LY89500005 ER PT J AU HERRINGTON, DM SIEBES, M SOKOL, DK SIU, CO WALFORD, GD AF HERRINGTON, DM SIEBES, M SOKOL, DK SIU, CO WALFORD, GD TI VARIABILITY IN MEASURES OF CORONARY LUMEN DIMENSIONS USING QUANTITATIVE CORONARY ANGIOGRAPHY SO JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY LA English DT Article ID ARTERY DISEASE; CINE FILM; CINEANGIOGRAMS; ARTERIOGRAPHY; STENOSES; QUANTIFICATION; DIAMETER AB Objectives: The purpose of this study was to determine the true total variability of quantitative coronary angiographic measures and their components in the clinical setting. Background: Many studies describe quantitative coronary angiographic variability on the basis of repeated quantitative coronary angiographic measures from the same cineangiogram. Although these studies characterize well the performance of quantitative coronary angiographic analysis methods, they do not include other potentially important sources of variability in results of this procedure, such as day to day variations in patients and equipment or variability in selection of frames for analysis. Methods: Coronary angiograms from 20 patients who underwent diagnostic angiography followed by percutaneous transluminal coronary angioplasty an average of 2.9 days later were reviewed. A total of 30 lesions well visualized in both films were analyzed multiple times using an automated first-derivative edge-detection quantitative coronary angiographic technique. Results: The coefficient of variation for quantitative coronary angiographic measures of the same lesions from separate angiograms ranged from 8.11% to 14.01%. Average diameter was the least variable and percent diameter stenosis the most variable. Day to day variations in the patient, procedure and equipment accounted for an average of 30% of the total variability. Of the remaining variability, only 13.26% was due to variability in frame selection. Conclusions: These results provide useful information for planning clinical studies using quantitative coronary angiography, identify areas where additional improvements in this technology are needed and define more clearly the applicability of quantitative coronary angiography in the setting of routine clinical practice. C1 JOHNS HOPKINS UNIV,DEPT MED,DIV CARDIOL,BALTIMORE,MD 21218. JET PROP LAB,PASADENA,CA 91109. RP HERRINGTON, DM (reprint author), BOWMAN GRAY SCH MED,DIV CARDIOL,MED CTR BLVD,WINSTON SALEM,NC 27157, USA. RI Siebes, Maria/A-9870-2008 OI Siebes, Maria/0000-0002-7034-5843 FU NCRR NIH HHS [RR00722]; NHLBI NIH HHS [HL-23619, HL07642] NR 29 TC 36 Z9 37 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0735-1097 J9 J AM COLL CARDIOL JI J. Am. Coll. Cardiol. PD OCT PY 1993 VL 22 IS 4 BP 1068 EP 1074 PG 7 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA MQ362 UT WOS:A1993MQ36200015 PM 8409042 ER PT J AU KIM, FD CELI, R TISCHLER, MB AF KIM, FD CELI, R TISCHLER, MB TI HIGH-ORDER STATE-SPACE SIMULATION-MODELS OF HELICOPTER FLIGHT MECHANICS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB This paper describes the formulation and validation of a high-order linearized mathematical model of helicopter flight mechanics, which includes rotor flap and lag degrees of freedom as well as inflow dynamics. The model is extracted numerically from an existing nonlinear, blade element, real-time simulation model. Extensive modifications in the formulation and solution process of the nonlinear model, required for a theoretically rigorous linearization, are described in detail. The validation results show that the linearized model successfully captures the coupled rotor-fuselage dynamics in the frequency band most critical for the design of advanced flight control systems. Additional results quantify the extent to which the order of the model can be reduced without loss of fidelity. C1 UNIV MARYLAND,DEPT AEROSP ENGN,CTR ROTORCRAFT EDUC & RES,COLL PK,MD 20742. USA,AEROFLIGHTDYNAM DIRECTORATE,AMES RES CTR,MOFFETT FIELD,CA. RP KIM, FD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 14 Z9 15 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1993 VL 38 IS 4 BP 16 EP 27 PG 12 WC Engineering, Aerospace SC Engineering GA MV901 UT WOS:A1993MV90100002 ER PT J AU NIXON, MW AF NIXON, MW TI PARAMETRIC STUDIES FOR TILTROTOR AEROELASTIC STABILITY IN HIGH-SPEED FLIGHT SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB The influence of several system design parameters on tiltrotor aeroelastic stability is examined for the highspeed (axial) flight mode. The results are based on a math model in which the wing is assumed to be cantilevered and is represented by beam finite elements having vertical bending, chordwise bending and torsional degrees of freedom. A quasi-steady aerodynamic model is used for both the wing and rotor system. Coupling of the rotor flapping modes with the wing elastic modes produces a whirl motion, typical of tiltrotors, that can become unstable at high speeds. The sensitivity of this instability with respect to rotor frequencies, wing stiffnesses and forward wing sweep is examined. Some important new trends are identified regarding the role of blade lag dynamics and forward wing sweep in tiltrotor aeroelastic stability. Two important conclusions based on these trend studies are that the blade lag frequency may be tuned to improve tiltrotor stability, and forward wing sweep is destabilizing because of changes in rotor force components associated with the sweep. RP NIXON, MW (reprint author), NASA,LANGLEY RES CTR,USA,VEHICLE STRUCT DIRECTORATE,HAMPTON,VA 23665, USA. NR 19 TC 8 Z9 9 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1993 VL 38 IS 4 BP 71 EP 79 PG 9 WC Engineering, Aerospace SC Engineering GA MV901 UT WOS:A1993MV90100007 ER PT J AU MARKLEY, FL AF MARKLEY, FL TI NEW DYNAMIC VARIABLES FOR MOMENTUM-BIAS SPACECRAFT SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This paper introduces two new seven-parameter representations for spacecraft attitude dynamics modeling. The seven parameters are the three components of the total system angular momentum in the spacecraft body frame, the three components of the angular momentum in the inertial reference frame, and an angle variable. These obey a single constraint as do parameterizations that include a quaternion; in this case, the constraint is the equality of the sum of the squares of the angular momentum components in the two frames. The two representations are nonsingular if the system angular momentum is nonzero and obeys certain orientation constraints. The new parameterizations of the attitude matrix, the equations of motion, and the relation of the solution of these equations to Euler angles for torque-free motion are developed and analyzed. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,CODE 712,GREENBELT,MD 20771, USA. NR 5 TC 5 Z9 5 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1993 VL 41 IS 4 BP 557 EP 567 PG 11 WC Engineering, Aerospace SC Engineering GA NB179 UT WOS:A1993NB17900006 ER PT J AU VINING, CB WILLIAMS, RM UNDERWOOD, ML RYAN, MA SUITOR, JW AF VINING, CB WILLIAMS, RM UNDERWOOD, ML RYAN, MA SUITOR, JW TI REVERSIBLE THERMODYNAMIC CYCLE FOR AMTEC POWER CONVERSION SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID INTERFACIAL IMPEDANCE; ELECTRODES; TRANSPORT; KINETICS; ALUMINA AB The thermodynamic cycle appropriate to an alkali metal thermal-to-electric converter (AMTEC) cell is discussed for both liquid- and vapor-fed modes of operation, under the assumption that all processes can be performed reversibly. In the liquid-fed mode, the reversible efficiency is greater than 89.6% of Carnot efficiency for heat input and rejection temperatures (900-1300 and 400-800 K, respectively) typical of practical devices. Vapor-fed cells can approach the efficiency of liquid-fed cells. Quantitative estimates confirm that the efficiency is insensitive to either the work required to pressurize the sodium liquid or the details of the state changes associated with cooling the low pressure sodium gas to the heat rejection temperature. RP VINING, CB (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 10 TC 7 Z9 7 U1 1 U2 2 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD OCT PY 1993 VL 140 IS 10 BP 2760 EP 2763 DI 10.1149/1.2220907 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA MD880 UT WOS:A1993MD88000011 ER PT J AU DEGROH, HC KASSEMI, M AF DEGROH, HC KASSEMI, M TI EFFECT OF RADIATION ON CONVECTION IN A TOP-HEATED ENCLOSURE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID NATURAL-CONVECTION; CHANNEL AB The top-heated enclosure is of considerable importance in many engineering situations, especially in crystal growth from vapor where it is used to minimize convection. In this work we present a combined numerical and experimental investigation of radiation induced convection to show that the convective stability of the top-heated enclosure is disrupted by heat transfer conditions at the wall. When the enclosure is not insulated. the thermal stratification of the fluid is modified by convective and radiative losses to the surrounding environment. This results in a double annular cell now, which when cut by the laser sheet, shows a four-vortex pattern with a weak annular cell at the bottom and a large counter-rotating annular cell at the top. When the enclosure is insulated, the convective stability of the fluid is again disrupted; this time as a result of radiative heat transfer between the enclosing surfaces which drives two annular flow cells of relatively equal size. Excellent agreement was found between the numerical predictions and the experiment. Comparison between model and experiments show that radiation effects are important even at temperature levels as low as 300-degrees, and if these effects are not included, numerical predictions can be far removed from reality. RP DEGROH, HC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 561 EP 568 DI 10.2514/3.461 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900004 ER PT J AU SIEGEL, R SPUCKLER, CM AF SIEGEL, R SPUCKLER, CM TI VARIABLE REFRACTIVE-INDEX EFFECTS ON RADIATION IN SEMITRANSPARENT SCATTERING MULTILAYERED REGIONS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID HEAT-TRANSFER; ABSORBERS AB A simple set of equations is derived for predicting the temperature distribution and radiative energy flow in a semitransparent layer consisting of an arbitrary number of laminated sublayers that absorb, emit, and scatter radiation. Each sublayer can have a different refractive index and optical thickness. The plane composite region is heated on each exterior side by a different amount of incident radiation. The results are for the limiting case where heat conduction within the layers is very small relative to radiative transfer, and is neglected. The interfaces are assumed diffuse, and all interface reflections are included in the analysis. The thermal behavior is readily calculated from the analytical expressions that are obtained. By using many sublayers, the analytical expressions provide the temperature distribution and heat flow for a diffusing medium with a continuously varying refractive index, including internal reflection effects caused by refractive index gradients. Temperature and heat flux results are given to show the effect of variations in refractive index and optical thickness through the multilayer laminate. RP SIEGEL, R (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 17 TC 73 Z9 73 U1 0 U2 6 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 EI 1533-6808 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 624 EP 630 DI 10.2514/3.470 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900013 ER PT J AU GARIMELLA, SV SHOLLENBERGER, KA EIBECK, PA WHITE, S AF GARIMELLA, SV SHOLLENBERGER, KA EIBECK, PA WHITE, S TI FLOW AND HEAT-TRANSFER IN SIMULATED REENTRY VEHICLE TILE GAPS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID DRIVEN CAVITY FLOW AB Experiments were performed to investigate the flow patterns and convective heat transfer characteristics in intersecting tile gaps on space vehicles. The flow in a water channel simulates the external flow, and gaps with a depth to width ratio of 20 are mounted as recesses in the bottom wall. A ''parallel'' gap is installed at 18 deg to the flow direction and ends in a perpendicular gap normal to the flow direction. Gap flow patterns and temperature distributions are obtained as functions of the gap-width-based Reynolds number, the relative height between tiles at the T intersection, and the temperature difference between gap and external flows, using dye entrainment, liquid crystals. and a grid of surface thermocouples. External flow penetration into the perpendicular gap was limited to roughly two gap widths while greater entrainment occurred in the parallel gap. The 18-deg angle of the parallel gap led to asymmetries about the centerline in the perpendicular gap now patterns and convection coefficients. Natural convection was the predominant mode of heat transfer in the bulk of the perpendicular gap. The Reynolds number and relative tile-height differences had the strongest influence on heat transfer and affected both the magnitude and the asymmetry of the temperature and flowfields. C1 UNIV CALIF BERKELEY,DEPT MECH ENGN,BERKELEY,CA 94720. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP GARIMELLA, SV (reprint author), UNIV WISCONSIN,DEPT MECH ENGN,MILWAUKEE,WI 53201, USA. RI Garimella, Suresh/A-1286-2013 OI Garimella, Suresh/0000-0003-1421-2912 NR 11 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 644 EP 650 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900016 ER PT J AU WADAWADIGI, G TANNEHILL, JC BUELOW, PE LAWRENCE, SL AF WADAWADIGI, G TANNEHILL, JC BUELOW, PE LAWRENCE, SL TI 3-DIMENSIONAL UPWIND PARABOLIZED NAVIER-STOKES CODE FOR SUPERSONIC COMBUSTION FLOWFIELDS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID FLOWS; NONEQUILIBRIUM AB A new upwind, parabolized Navier-Stokes (PNS) code has been developed to compute the three-dimensional chemically reacting flow in scramjet (supersonic combustion ramjet) engines. The code is a modification of the three-dimensional upwind PNS (UPS) airflow code which has been extended in the present study to permit internal flow calculations with hydrogen-air chemistry. With these additions, the new code has the capability of computing both aerodynamic and propulsive flowfields. The algorithm solves the PNS equations using a finite-volume, upwind TVD method based on Roe's approximate Riemann solver that has been modified to account for nonequilibrium effects. The fluid medium is assumed to be a chemically reacting mixture of thermally perfect (but calorically imperfect) gases in thermal equilibrium. The new code has been applied to two test cases. These include the Burrows-Kurkov supersonic combustion experiment and a three-dimensional shock-induced combustion flowfield. The computed results compare favorably with the available experimental data. C1 NASA,AMES RES CTR,APPL COMPUTAT FLUID DYNAM BRANCH,MOFFETT FIELD,CA 94035. RP WADAWADIGI, G (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT AEROSP ENGN & ENGN MECH,AMES,IA 50011, USA. NR 42 TC 8 Z9 11 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 661 EP 667 DI 10.2514/3.475 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900018 ER PT J AU SHARMA, SP RUFFIN, SM GILLESPIE, WD MEYER, SA AF SHARMA, SP RUFFIN, SM GILLESPIE, WD MEYER, SA TI VIBRATIONAL-RELAXATION MEASUREMENTS IN AN EXPANDING FLOW USING SPONTANEOUS RAMAN-SCATTERING SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Vibrational relaxation of nitrogen in a two-dimensional nozzle now is studied with spontaneous Raman scattering. An electric arc-driven shock tube operating as a reflected shock tunnel produces stagnation conditions of 5600 K and 100 atm. A 248-nm KrF laser pulse is focused into the nozzle to produce spatially resolved spontaneous Raman spectra. Vibrational population distributions are derived from the spectra for the states upsilon = 0 to upsilon = 8. The experimental results are compared with two theoretical models: 1) the Landau-Teller relaxation model and 2) a numerical solution of the master equations using transition rates derived from Schwartz, Slawsky, and Herzfeld (SSH) theory. We have measured a value for the Landau-Teller correction factor (phi) to be 1.0-1.5. C1 STANFORD UNIV,STANFORD,CA 94305. RP SHARMA, SP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 20 Z9 20 U1 2 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 697 EP 703 DI 10.2514/3.479 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900022 ER PT J AU PARK, C YOON, S AF PARK, C YOON, S TI CALCULATION OF REAL-GAS EFFECTS ON AIRFOIL AERODYNAMIC CHARACTERISTICS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 MCAT INST,MOFFETT FIELD,CA 94035. RP PARK, C (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 4 TC 1 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 727 EP 729 DI 10.2514/3.56282 PG 3 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900027 ER PT J AU CHUNG, CH DEWITT, KJ JENG, DR PENKO, PF AF CHUNG, CH DEWITT, KJ JENG, DR PENKO, PF TI INTERNAL STRUCTURE OF SHOCK-WAVES IN DISPARATE MASS MIXTURES SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 UNIV TOLEDO,DEPT CHEM ENGN,TOLEDO,OH 43606. UNIV TOLEDO,DEPT MECH ENGN,TOLEDO,OH 43606. RP CHUNG, CH (reprint author), NASA,LEWIS RES CTR,LOW TRUST POPULAT BRANCH,CLEVELAND,OH 44135, USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1993 VL 7 IS 4 BP 742 EP 744 DI 10.2514/3.490 PG 3 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA MD879 UT WOS:A1993MD87900033 ER PT J AU GILMARTIN, WG JOHANOS, TC EBERHARDT, LL AF GILMARTIN, WG JOHANOS, TC EBERHARDT, LL TI SURVIVAL RATES FOR THE HAWAIIAN MONK SEAL (MONACHUS-SCHAUINSLANDI) SO MARINE MAMMAL SCIENCE LA English DT Article DE HAWAIIAN MONK SEAL; MONACHUS-SCHAUINSLANDI; SURVIVAL; TAG RESIGHTING; JOLLY-SEBER AB Endangered Hawaiian monk seal (Monachus schauinslandi) pups at all the major breeding islands in the Northwestern Hawaiian Islands have been tagged since the early 1980s. Pups were double flipper tagged as soon as possible post-weaning. With few exceptions, an extensive tag resighting effort was conducted annually at the same islands. These resighting data were used to estimate seal survival rates from the time of tagging to age one at all locations using the ratio of seals alive in eae second year to number of pups tagged. These survival fates among the islands, from weaning to age one, averaged over the years of the study, ranged from 0.80 to 0.90. For young seals over age one, capture-recapture methods were used to calculate survival pooled through several years, and these rates ranged from 0.85 to 0.98. At French Frigate Shoals and Laysan Island, the higher numbers of tagged pups allowed separate estimates of male and female survival to be calculated. These rates suggested that survival of immature females was better than males. Beginning in 1989, survival of immature seals at French Frigate Shoals decined sharply. RP GILMARTIN, WG (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822, USA. NR 15 TC 27 Z9 29 U1 1 U2 5 PU SOC MARINE MAMMALOGY PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 SN 0824-0469 J9 MAR MAMMAL SCI JI Mar. Mamm. Sci. PD OCT PY 1993 VL 9 IS 4 BP 407 EP 420 DI 10.1111/j.1748-7692.1993.tb00473.x PG 14 WC Marine & Freshwater Biology; Zoology SC Marine & Freshwater Biology; Zoology GA MH887 UT WOS:A1993MH88700006 ER PT J AU DEGROH, HC WEIDMAN, PD ZAKHEM, R AHUJA, S BECKERMANN, C AF DEGROH, HC WEIDMAN, PD ZAKHEM, R AHUJA, S BECKERMANN, C TI CALCULATION OF DENDRITE SETTLING VELOCITIES USING A POROUS ENVELOPE SO METALLURGICAL TRANSACTIONS B-PROCESS METALLURGY LA English DT Article ID NH4CL-H2O ANALOG CASTINGS; MODEL ASPECTS; DRAG AB The convective transport and gravitational settling of unattached equiaxed grains and dendrite fragments can cause macrosegregation and influence the structure of the equiaxed zone in a variety of solidification arrangements. An understanding of how the highly nonspherical geometry of the dendrite influences its settling and transport characteristics is needed to determine the motion of unattached dendrites and predict structure and segregation in castings. The empirical results of previous works have been used to develop a FORTRAN 77 computer program to calculate the settling velocity of various dendritic shapes and a number of other parameters of interest, such as the volume and surface area of the dendrite. Required inputs to the code are the physical properties of the system and some simple geometric parameters of the dendrite being considered, such as the average radius of the primary arm. The predicted settling velocities were on average within +/-5 pct of those measured for model dendrites and were consistent and in good agreement with three other experimental investigations. Future development of the code will attempt to overcome many of its present limitations by including particle-particle interactions and the effects of tertiary arms, for example. C1 UNIV COLORADO,DEPT MECH ENGN,BOULDER,CO 80309. UNIV IOWA,DEPT MECH ENGN,IOWA CITY,IA 52242. RP DEGROH, HC (reprint author), NASA,LEWIS RES CTR,DEPT MECH ENGN,CLEVELAND,OH 44135, USA. RI Beckermann, Christoph/F-7158-2010 OI Beckermann, Christoph/0000-0002-9976-0995 NR 22 TC 25 Z9 25 U1 0 U2 10 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2141 J9 METALL TRANS B PD OCT PY 1993 VL 24 IS 5 BP 749 EP 753 PG 5 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA LY902 UT WOS:A1993LY90200004 ER PT J AU GUENTHER, B AF GUENTHER, B TI NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY IV - FOREWORD SO METROLOGIA LA English DT Editorial Material RP GUENTHER, B (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 205 EP 205 DI 10.1088/0026-1394/30/4/E01 PG 1 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600001 ER PT J AU NITHIANANDAM, J GUENTHER, BW ALLISON, LJ AF NITHIANANDAM, J GUENTHER, BW ALLISON, LJ TI AN ANECDOTAL REVIEW OF NASA EARTH OBSERVING SATELLITE REMOTE SENSORS AND RADIOMETRIC CALIBRATION METHODS SO METROLOGIA LA English DT Article ID OZONE AB An anecdotal history of the evolution of satellite remote sensors for making Earth observations in the infrared, visible and ultraviolet spectral regions during the past three decades at the National Aeronautics and Space Administration (NASA) is presented together with an intercomparison of the earlier scanning remote sensors and the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Earth Observing System (EOS) project. Developments in the pre-launch and in-flight radiometric calibration systems and techniques for these satellite remote scanners, sounders and television imagers are highlighted. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP NITHIANANDAM, J (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 20 TC 7 Z9 7 U1 0 U2 1 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 207 EP 212 DI 10.1088/0026-1394/30/4/001 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600002 ER PT J AU BRUEGGE, CJ DUVAL, VG CHRIEN, NL DINER, DJ AF BRUEGGE, CJ DUVAL, VG CHRIEN, NL DINER, DJ TI CALIBRATION PLANS FOR THE MULTI-ANGLE IMAGING SPECTRORADIOMETER (MISR) SO METROLOGIA LA English DT Article AB The EOS Multi-angle Imaging SpectroRadiometer (MISR) will study the ecology and climate of the Earth through acquisition of global multi-angle imagery. The MISR employs nine discrete cameras, each a push-broom imager. Of these, four point forward, four point aft and one views the nadir. Absolute radiometric calibration will be obtained pre-flight using high quantum efficiency (HQE) detectors and an integrating sphere source. After launch, instrument calibration will be provided using HQE detectors in conjunction with deployable diffuse calibration panels. The panels will be deployed at time intervals of one month and used to direct sunlight into the cameras, filling their fields-of-view and providing through-the-optics calibration. Additional techniques will be utilized to reduce systematic errors, and provide continuity as the methodology changes with time. For example, radiation-resistant photodiodes will also be used to monitor panel radiant exitance. These data will be acquired throughout the five-year mission, to maintain calibration in the latter years when it is expected that the HQE diodes will have degraded. During the mission, it is planned that the MISR will conduct semi-annual ground calibration campaigns, utilizing field measurements and higher resolution sensors (aboard aircraft or in-orbit platforms) to provide a check of the on-board hardware. These ground calibration campaigns are limited in number, but are believed to be the key to the long-term-maintenance of MISR radiometric calibration. RP BRUEGGE, CJ (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 12 Z9 12 U1 1 U2 3 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 213 EP 221 DI 10.1088/0026-1394/30/4/002 PG 9 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600003 ER PT J AU HILSENRATH, E WILLIAMS, DE CAFFREY, RT CEBULA, RP HYNES, SJ AF HILSENRATH, E WILLIAMS, DE CAFFREY, RT CEBULA, RP HYNES, SJ TI CALIBRATION AND RADIOMETRIC STABILITY OF THE SHUTTLE SOLAR BACKSCATTER ULTRAVIOLET (SSBUV) EXPERIMENT SO METROLOGIA LA English DT Article ID INSTRUMENTS; IRRADIANCE; OZONE AB The SSBUV is part of the National Plan for monitoring the stratosphere, Ozone monitoring from space employs backscatter ultraviolet-type instruments on NOAA operational, NASA research and foreign environmental satellites. The SSBUV provides calibration data for these instruments using nearly coincident observations of the Earth's ultraviolet albedo from a series of Space Shuttle flights. The SSBUV also measures the middle ultraviolet solar irradiance as part of the ozone measurement. A major requirement for the SSBUV is that its calibration be known to about 1 % from one flight to the next. To achieve this, the SSBUV conducts a rigorous calibration program involving multiple standard sources and detectors. The SSBUV has now flown four times, over a thirty-month period beginning in October 1989. This paper deals with the calibration and radiometric stability before and after each of four Shuttle flights and is an update to the results reported after the first SSBUV flight. For the more recent flights, laboratory calibration precision continues to be better than 1 %. Instrument sensitivity continued to degrade by 1 % to 3 % after each flight, and is wavelength dependent. Measurements of the solar irradiance in the wavelength region 200 nm to 400 nm have a precision of 1 % to 2 % from one flight to the next. Comparison of the SSBUV and the NOAA-11 SBUV-2 solar irradiance measurements indicates that the SBUV-2 instrument is degrading less than 1 % per year at wavelengths longer than 300 nm and by as much as 6 % per year at wavelengths shorter than 250 nm. C1 HUGHES STX CORP,LANHAM,MD 20706. IDEA,BELTSVILLE,MD 20705. RP HILSENRATH, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 17 TC 16 Z9 16 U1 1 U2 2 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 243 EP 248 DI 10.1088/0026-1394/30/4/005 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600006 ER PT J AU MECHERIKUNNEL, A AF MECHERIKUNNEL, A TI A COMPARATIVE-STUDY OF SOLAR TOTAL IRRADIANCE MEASURED BY ACTIVE-CAVITY RADIOMETERS SO METROLOGIA LA English DT Article AB This paper presents the results from a comparative study of solar total irradiance data from the Earth Radiation Budget Experiment (ERBE) on board the Earth Radiation Budget Satellite (ERBS), and the Solar Maximum Mission Active Cavity Radiometer Irradiance Monitor-1 (SMM/ACRIM), for the overlap period 25 October 1984 to 5 July 1989. Both measurements used active-cavity radiometers (ACR). For days when measurements are available from both satellites, the mean difference in the irradiance values is 2,18 W.m-2. The data show good agreement both in the details of the day-to-day variations and in the long-term trends. The irradiance variations observed in the measurements track the solar activity cycle quite well. The amplitude of the solar cycle related irradiance variation is 0,1 %. For the period October 1984 to July 1989, a correlation coefficient of 0,781 is obtained for the two data sets. The correlation becomes stronger with the increase in solar activity, but breaks down for low solar activity periods. Independent studies of ERBS/ERBE and Nimbus-7/ERB; SMM/ACRIM and Nimbus-7/ERB also show high correlation between the data sets during high solar activity periods. RP MECHERIKUNNEL, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERRESTRIAL PHYS LAB,GREENBELT,MD 20771, USA. NR 7 TC 2 Z9 4 U1 0 U2 2 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 271 EP 273 DI 10.1088/0026-1394/30/4/010 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600011 ER PT J AU SMITH, PL LEAN, JL CHRISTENSEN, AB HARVEY, KL JUDGE, DL MOORE, RL TORR, MR WOODS, TN AF SMITH, PL LEAN, JL CHRISTENSEN, AB HARVEY, KL JUDGE, DL MOORE, RL TORR, MR WOODS, TN TI SOURCE - THE SOLAR ULTRAVIOLET-RADIATION AND CORRELATIVE EMISSIONS MISSION SO METROLOGIA LA English DT Article ID IRRADIANCE VARIATIONS; FLUX; MODEL AB The Solar Ultraviolet Radiation and Correlative Emissions (SOURCE) mission is intended to advance our ability to specify the spectral irradiance of the Sun in the extreme ultraviolet (EUV) wavelength range through simultaneous, radiometrically accurate measurements of the solar EUV spectral irradiance and measurements, including EUV and visible images, of solar parameters that are correlated with the EUV flux. The data will be used in combination with empirical modelling to develop and validate a more accurate system of proxy, or surrogate, indices for the solar EUV flux. C1 AEROSP CORP,LOS ANGELES,CA 90009. SOLAR PHYS RES CORP,TUCSON,AZ 85718. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV SO CALIF,CTR SPACE SCI,LOS ANGELES,CA 90089. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. HIGH ALTITUDE OBSERV,BOULDER,CO 80307. RP SMITH, PL (reprint author), USN,RES LAB,DIV SPACE SCI,WASHINGTON,DC 20375, USA. OI Lean, Judith/0000-0002-0087-9639 NR 24 TC 0 Z9 0 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 275 EP 277 DI 10.1088/0026-1394/30/4/011 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600012 ER PT J AU LEE, RB AVIS, LM GIBSON, MA THOMAS, S WILSON, R AF LEE, RB AVIS, LM GIBSON, MA THOMAS, S WILSON, R TI IN-FLIGHT EVALUATIONS OF TUNGSTEN CALIBRATION LAMPS USING SHORTWAVE THERMISTOR BOLOMETERS AND ACTIVE-CAVITY RADIOMETERS SO METROLOGIA LA English DT Article ID RADIATION; INSTRUMENT; MAXIMUM AB The stabilities of type 715, T-1, tungsten calibration lamps were evaluated aboard three spacecraft platforms during the period 1984 to 1989. In the 0,2 mum to <5,0 mum broadband spectral region, the emitted radiant power from each lamp was measured using shortwave thermistor bolometers and active-cavity radiometers. The radiant power was found to be constant to +/- 1 %. The responses of filter and silicon photodiode monitoring systems used to evaluate the lamps were found to degrade as much as 6 % during the first two years in orbit. C1 SCI APPLICAT INT CORP,HAMPTON,VA 23666. RP LEE, RB (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 22 TC 14 Z9 14 U1 0 U2 1 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD OCT PY 1993 VL 30 IS 4 BP 389 EP 395 DI 10.1088/0026-1394/30/4/034 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MN836 UT WOS:A1993MN83600035 ER PT J AU BHASIN, KB AF BHASIN, KB TI SPECIAL ISSUE ON SUPERCONDUCTIVE MICROWAVE DEVICES AND CIRCUITS - FOREWORD SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Editorial Material RP BHASIN, KB (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 2 U2 2 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD OCT PY 1993 VL 6 IS 13 BP 725 EP 725 PG 1 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA LY906 UT WOS:A1993LY90600001 ER PT J AU MIRANDA, FA TONCICH, SS BHASIN, KB AF MIRANDA, FA TONCICH, SS BHASIN, KB TI PERFORMANCE OF 2-POLE BANDPASS-FILTERS PHOTODEFINED ON DOUBLE-SIDED Y-BA-CU-O AND TL-BA-CA-CU-O THIN-FILMS SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE 2-POLE BANDPASS FILTERS; DOUBLE-SIDED HTS THIN FILMS; INSERTION LOSS MEASUREMENTS AB The performance of 7.3-GHz two-pole bandpass filters (5% bandwidth) fabricated on double-sided Y-Ba-Cu-0 and Tl-Ba-Ca-Cu-0 thin films deposited on LaAlO3 is discussed. At 77 K, the Tl-Ba-Ca-Cu-O and Y-Ba-Cu-0 superconducting filters exhibited minimum passband insertion losses of 0.3 and 1.2 dB, respectively. An insertion loss of 3.4 dB was measured for an all-gold filter at 77 K. (C) 1993 John Wiley & Sons. Inc. RP MIRANDA, FA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD OCT PY 1993 VL 6 IS 13 BP 752 EP 756 DI 10.1002/mop.4650061309 PG 5 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA LY906 UT WOS:A1993LY90600008 ER PT J AU HEARN, CP BARTLEY, PG BRADSHAW, ES AF HEARN, CP BARTLEY, PG BRADSHAW, ES TI A MODIFIED Q-CIRCLE MEASUREMENT PROCEDURE FOR GREATER ACCURACY SO MICROWAVE JOURNAL LA English DT Note C1 INNOVAT MEASUREMENT SOLUT INC,ATLANTA,GA. LOCKHEED ENGN & SCI CO,HAMPTON,VA. RP HEARN, CP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 5 TC 1 Z9 1 U1 0 U2 0 PU HORIZON HOUSE-MICROWAVE PI NORWOOD PA 685 CANTON ST, NORWOOD, MA 02062 SN 0192-6225 J9 MICROWAVE J JI Microw. J. PD OCT PY 1993 VL 36 IS 10 BP 108 EP & PG 0 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA ME533 UT WOS:A1993ME53300007 ER PT J AU YAO, MW CHAIT, A AF YAO, MW CHAIT, A TI AN ALTERNATIVE FORMULATION OF THE APPARENT HEAT-CAPACITY METHOD FOR PHASE-CHANGE PROBLEMS SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article ID SOLIDIFICATION PROBLEMS AB In the apparent heat capacity method (AHCM) for heat transfer problems with phase change, the conventional time discretization is subject to severe restrictions an time steps in spite of the various approximation techniques that have been developed so far. To improve the conventional AHCM we propose an alternative formulation. By introducing a nominal heat capacity, the new time discretization can better approximate the time derivative of enthalpy while maintaining the same form as the conventional AHCM. The new formulation also establishes an equivalent relation between the full enthalpy formulation and the AHCM. A one-dimensional (I-D) Stefan problem is used as a test problem, and comparison is made between the solutions of the conventional and the new AHCM formulations. It is found that for implicit schemes with large time steps, the new formulation performs much better than the conventional AHCM. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP YAO, MW (reprint author), OHIO AEROSP INST,BROOKPARK,OH 44142, USA. NR 28 TC 15 Z9 15 U1 0 U2 5 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD OCT-NOV PY 1993 VL 24 IS 3 BP 279 EP 300 DI 10.1080/10407799308955894 PG 22 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA MD931 UT WOS:A1993MD93100003 ER PT J AU JANI, MG BARNES, NP MURRAY, KE LOCKARD, GE AF JANI, MG BARNES, NP MURRAY, KE LOCKARD, GE TI LONG-PULSE-LENGTH 2-MU-M DIODE-PUMPED YLIF4 LASER SO OPTICS LETTERS LA English DT Article ID TM; OPERATION; YAG; HO AB A diode-pumped Ho:Tm:YLiF4 laser at room temperature has achieved an optical efficiency of 5.9% under normal-mode operation. Long pulse lengths, of the order of 1 mus, have been obtained by use of 4-m ring resonator, with laser energy output of 15 mJ in single Q-switched pulses for an input energy of 2.078 J. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP JANI, MG (reprint author), SCI & TECHNOL CORP,101 RES DR,HAMPTON,VA 23666, USA. NR 12 TC 14 Z9 15 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD OCT 1 PY 1993 VL 18 IS 19 BP 1636 EP 1638 DI 10.1364/OL.18.001636 PG 3 WC Optics SC Optics GA LY623 UT WOS:A1993LY62300019 PM 19823470 ER PT J AU YEH, NC KRIPLANI, U JIANG, W REED, DS STRAYER, DM BARNER, JB HUNT, BD FOOTE, MC VASQUEZ, RP GUPTA, A KUSSMAUL, A AF YEH, NC KRIPLANI, U JIANG, W REED, DS STRAYER, DM BARNER, JB HUNT, BD FOOTE, MC VASQUEZ, RP GUPTA, A KUSSMAUL, A TI MICROWAVE VORTEX DISSIPATION OF SUPERCONDUCTING ND-CE-CU-O EPITAXIAL-FILMS IN HIGH MAGNETIC-FIELDS SO PHYSICAL REVIEW B LA English DT Note ID HIGH-TEMPERATURE SUPERCONDUCTORS; II SUPERCONDUCTORS; THIN-FILMS; YBA2CU3OY CRYSTALS; SURFACE IMPEDANCE; SCALING BEHAVIOR; DEPENDENCE; PENETRATION; FORCES AB The microwave vortex dissipation of superconducting Nd1.85Ce0.15CuOx epitaxial films is investigated by use of a sapphire dielectric-ring resonator in the whispering gallery modes, and in dc magnetic fields ranging from 0 to 25 kG. By extending the Coffey-Clem model to the thin-film and finite-grain-size limit, we infer important material parameters, including the irreversibility line, vortex pinning potential, pinning force constant and viscosity, through a direct least-squares fit to the microwave-absorption data. C1 JET PROP LAB,PASADENA,CA 91109. IBM CORP,THOMAS J WATSON RES CTR,DIV RES,YORKTOWN HTS,NY 10598. MIT,FRANCIS BITTER NATL MAGNET LAB,CAMBRIDGE,MA 02139. RP YEH, NC (reprint author), CALTECH,DEPT PHYS,PASADENA,CA 91125, USA. NR 31 TC 17 Z9 17 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD OCT 1 PY 1993 VL 48 IS 13 BP 9861 EP 9864 DI 10.1103/PhysRevB.48.9861 PG 4 WC Physics, Condensed Matter SC Physics GA MC116 UT WOS:A1993MC11600093 ER PT J AU CAI, D STOREY, LRO ITOH, T AF CAI, D STOREY, LRO ITOH, T TI PARTICLE SIMULATION OF THE KINETIC KELVIN-HELMHOLTZ INSTABILITY IN A MAGNETOPLASMA SO PHYSICS OF FLUIDS B-PLASMA PHYSICS LA English DT Article ID EXTERNAL MAGNETIC-FIELD; ELECTRIC-FIELD; SPACE-SHUTTLE; POLARIZATION; BOUNDARY; BEAM AB The kinetic Kelvin-Helmholtz instability in a collisionless magnetoplasma is simulated numerically in cases where the ion gyroradius is comparable with or larger than the spatial scale of the cross-field shear. The approach consists of starting the simulation from a state close to equilibrium, then observing the linear growth of instabilities and their ultimate saturation. The initial quasiequilibrium state is set up by a newly developed particle loading method; the instabilities are excited by numerical noise. The simulation is performed in two dimensions, in the plane perpendicular to the magnetic field, using an electrostatic particle code. The results for the kinetic Kelvin-Helmholtz instability are similar to those predicted by a hydromagnetic model, except that they depend slightly on the sign of the shear. Other instabilities are observed also: when the ion gyroradius is small on the scale of the shear, there is an unidentified short-wavelength instability characterized by k DELTAx greater-than-or-equal-to 1, where k is the wave number in the flow direction and DELTAx is the spatial scale of the shear; when the ion gyroradius is Large, Bernstein waves, both ionic and electronic, are excited in the flow discretion. C1 NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,GREENBELT,MD 20771. KOBE UNIV,NADA KU,KOBE 657,JAPAN. RP CAI, D (reprint author), UNIV TSUKUBA,INST INFORMAT SCI & ELECTR,TSUKUBA 305,JAPAN. NR 24 TC 7 Z9 7 U1 1 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8221 J9 PHYS FLUIDS B-PLASMA PD OCT PY 1993 VL 5 IS 10 BP 3507 EP 3523 DI 10.1063/1.860826 PG 17 WC Physics, Fluids & Plasmas SC Physics GA MC104 UT WOS:A1993MC10400006 ER PT J AU GAUSTAD, JE VANBUREN, D AF GAUSTAD, JE VANBUREN, D TI THE DISTRIBUTION OF INTERSTELLAR DUST IN THE SOLAR NEIGHBORHOOD SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID INFRARED CIRRUS; FILLING FACTOR; GALAXY; IRAS AB We surveyed the IRAS data base at the positions of the 1808 O6-B9.5 stars in The Bright Star Catalog for extended objects with excess emission at 60 mum, indicating the presence of interstellar dust at the location of the star. Within 400 pc the filling factor of the interstellar medium for dust clouds with a density >0.5 cm-3 is 14.6 +/- 2.4%. Above a density of 1.0 cm-3, the density distribution function appears to follow a power law of index -1.25. When the dust clouds are mapped onto the galactic plane, the sun appears to be located in a low-density region of the interstellar medium of width about 60 pc extending at least 500 pc in the direction of longitudes 80-degrees-260-degrees, a feature we call the ''local trough.'' C1 CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. RP GAUSTAD, JE (reprint author), SWARTHMORE COLL,DEPT PHYS & ASTRON,SWARTHMORE,PA 19081, USA. NR 20 TC 47 Z9 47 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 1993 VL 105 IS 692 BP 1127 EP 1140 DI 10.1086/133291 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD190 UT WOS:A1993MD19000006 ER PT J AU SHAVERS, MR FRANKEL, K MILLER, J SCHIMMERLING, W TOWNSEND, LW WILSON, JW AF SHAVERS, MR FRANKEL, K MILLER, J SCHIMMERLING, W TOWNSEND, LW WILSON, JW TI THE FRAGMENTATION OF 670A MEV NE-20 AS A FUNCTION OF DEPTH IN WATER .3. ANALYTICAL MULTIGENERATION TRANSPORT-THEORY SO RADIATION RESEARCH LA English DT Article ID CROSS-SECTIONS; MEV NE-20; PROPAGATION; IONS C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. FU NCI NIH HHS [CA23247] NR 16 TC 16 Z9 16 U1 0 U2 1 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD OCT PY 1993 VL 136 IS 1 BP 1 EP 14 DI 10.2307/3578633 PG 14 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA MD360 UT WOS:A1993MD36000001 PM 8210324 ER PT J AU CHOUDHURY, BJ AF CHOUDHURY, BJ TI REFLECTIVITIES OF SELECTED LAND-SURFACE TYPES AT 19 AND 37 GHZ FROM SSM/I OBSERVATIONS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID MICROWAVE BRIGHTNESS TEMPERATURES; WATER-CONTENT; EMISSION; VEGETATION; RADIATION; MODEL; COVER; CLASSIFICATION; MOISTURE; IMAGER AB Surface reflectivities for horizontally and vertically polarized emission at 19 GHz and 37 GHz are calculated for two locations over sand deserts, one location each over a rainforest, and a savanna from daytime observations by the Special Sensor Microwave Imager (SSM/I) on board the DMSP-F8 satellite for the period january 1988 to December 1989. The calculated reflectivities over the deserts are compared against predictions from the Fresnel equations, while the reflectivities over the rainforest are compared against predictions from a radiative transfer model and with field observations. The temporal variation of the reflectivities over the savanna is discussed in relation to those over deserts and rainforest, and in terms of biomass growth and decay. These SSM/I observations can be used to study seasonal and interannual changes of vegetation cover. RP CHOUDHURY, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. NR 39 TC 35 Z9 41 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1993 VL 46 IS 1 BP 1 EP 17 DI 10.1016/0034-4257(93)90028-V PG 17 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA LX456 UT WOS:A1993LX45600001 ER PT J AU DOWNING, HG CARTER, GA HOLLADAY, KW CIBULA, WG AF DOWNING, HG CARTER, GA HOLLADAY, KW CIBULA, WG TI THE RADIATIVE-EQUIVALENT WATER THICKNESS OF LEAVES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID OPTICAL-PROPERTIES; LEAF; REFLECTANCE; LIGHT AB The spectral transmittance of pure liquid water was measured using reflectance spectroscopy to provide a physical standard of comparison for the spectral reflectance of leaves. The spectral reflectance of a white reference measured through a 356 mum ray pathlength of water compared favorably with values predicted for the same pathlength by the known absorption coefficients of water. Differences between predicted and measured reflectances were significant only near wavelengths of 1400 nm and in the 1965-2200 nm range. The maximum difference of 7% occurred at 1401 nm. Predicted reflectances indicated notable reflectance minima at wavelengths near 1450 nm, 1940 nm, and 2500 nm, even for a 5-mum ray pathlength. Predicted reflectances at wavelengths less than 900 nm remained approximately 100% for a 3160 mum pathlength. A method is provided by which leaf reflectance in the 1500-2500 nm range can be used to easily compute the radiative-equivalent water thickness (REWT) of leaves. The REWT is defined as the thickness (absorption pathlength) of pure liquid water that would be required to yield the same radiative properties as the leaf in the 1500-2500 nm range, and is a physical standard that may be used in the study of leaf infrared reflectance. C1 NASA,SCI & TECHNOL LAB,BAY ST LOUIS,MS 39529. LOCKHEED ENGN & SCI CO,BAY ST LOUIS,MS. UNIV NEW ORLEANS,DEPT MATH,NEW ORLEANS,LA 70148. NR 14 TC 14 Z9 15 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1993 VL 46 IS 1 BP 103 EP 107 PG 5 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA LX456 UT WOS:A1993LX45600008 ER PT J AU SITTLER, EC AF SITTLER, EC TI REAL-TIME SPECTRAL-ANALYSIS ALGORITHM FOR SPACE PLASMA 3-DIMENSIONAL ION MASS SPECTROMETERS SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID SATURN AB We have developed a fast real-time spectral analysis algorithm for space plasma three-dimensional (3D) ion mass spectrometers that deconvolves contributions to time-of-flight ion mass spectra for various ion species abundances. The algorithm is composed of a set of coupled linear equations with constant coefficients. The algorithm is implemented so that in-flight computers need only apply a predetermined number of multiplies and adds to the spectral data. The algorithm allows run times to be short and highly predictable, can accommodate the presence of background in the ion mass spectra, and can be updated to adjust to calibration changes and unexpected instrument anomalies or failures. Space plasma 3D ion mass spectrometers have the capability of generating large volumes of data and if not compressed would produce data rates that far exceed the telemetry rate usually allocated to space plasma instruments. The real-time application of this algorithm allows one to achieve compression ratios greater than 100 for the spectral data without introducing systematic errors to the computed ion abundances. It also allows the application of other higher level data compression techniques to provide additional compression of the telemetry data. Finally, the algorithm can be thought of as a way to increase the mass resolution of the ion spectrometer. RP SITTLER, EC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 21 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1993 VL 64 IS 10 BP 2771 EP 2781 DI 10.1063/1.1144416 PG 11 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MC137 UT WOS:A1993MC13700008 ER PT J AU RHIM, WK CHUNG, SK BARBER, D MAN, KF GUTT, G RULISON, A SPJUT, RE AF RHIM, WK CHUNG, SK BARBER, D MAN, KF GUTT, G RULISON, A SPJUT, RE TI AN ELECTROSTATIC LEVITATOR FOR HIGH-TEMPERATURE CONTAINERLESS MATERIALS PROCESSING IN 1-G SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID PARTICLES AB This article discusses recent developments in high-temperature electrostatic levitation technology for containerless processing of metals and alloys. Presented is the first demonstration of an electrostatic levitation technology which can levitate metals and alloys (2-4 mm diam spheres) in vacuum and of superheating-undercooling-recalescence cycles which can be repeated while maintaining good positioning stability. The electrostatic levitator (ESL) has several important advantages over the electromagnetic levitator. Most important is the wide range of sample temperature which can be achieved without affecting levitation. This article also describes the general architecture of the levitator, electrode design, position control hardware and software, sample heating, charging, and preparation methods, and operational procedures. Particular emphasis is given to sample charging by photoelectric and thermionic emission. While this ESL is more oriented toward ground-based operation, an extension to microgravity applications is also addressed briefly. The system performance was demonstrated by showing multiple superheating-undercooling-recalescence cycles in a zirconium sample (T(m)=2128 K). This levitator, when fully matured, will be a valuable tool both in Earth-based and space-based laboratories for the study of thermophysical properties of undercooled liquids, nucleation kinetics, the creation of metastable phases, and access to a wide range of materials with novel properties. RP RHIM, WK (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 231 Z9 238 U1 5 U2 32 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1993 VL 64 IS 10 BP 2961 EP 2970 DI 10.1063/1.1144475 PG 10 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA MC137 UT WOS:A1993MC13700039 ER PT J AU OSTRO, SJ AF OSTRO, SJ TI PLANETARY RADAR ASTRONOMY SO REVIEWS OF MODERN PHYSICS LA English DT Review ID ARAKI-ALCOCK 1983D; COHERENT-BACKSCATTER; MAGELLAN OBSERVATIONS; WEAK LOCALIZATION; INITIAL ANALYSIS; GENERAL-RELATIVITY; BINARY ASTEROIDS; VENUS VOLCANISM; POLARIZED-LIGHT; IMPACT CRATERS AB Radar is a powerful technique that has furnished otherwise unavailable information about solar system bodies for three decades. The advantages of radar in planetary astronomy result from (1) the observer's control of all the attributes of the coherent signal used to illuminate the target, especially the wave form's time/frequency modulation and polarization; (2) the ability of radar to resolve objects spatially via measurements of the distribution of echo power in time delay and Doppler frequency; (3) the pronounced degree to which delay-Doppler measurements constrain orbits and spin vectors; and (4) centimeter-to-meter wavelengths, which easily penetrate optically opaque planetary clouds and cometary comae, permit investigation of near-surface macrostructure and bulk density, and are sensitive to high concentrations of metal or, in certain situations, ice. Planetary radar astronomy has primarily involved observations with Earth-based radar telescopes, but also includes some experiments with a spaceborne transmitter or receiver. In addition to providing a wealth of information about the geological and dynamical properties of asteroids, comets, the inner planets, and natural satellites, radar experiments have established the scale of the solar system, have contributed significantly to the accuracy of planetary ephemerides, and have helped to constrain theories of gravitation. This review outlines radar astronomical techniques and describes principal observational results. RP OSTRO, SJ (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 293 TC 121 Z9 123 U1 1 U2 8 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0034-6861 EI 1539-0756 J9 REV MOD PHYS JI Rev. Mod. Phys. PD OCT PY 1993 VL 65 IS 4 BP 1235 EP 1279 DI 10.1103/RevModPhys.65.1235 PG 45 WC Physics, Multidisciplinary SC Physics GA MM657 UT WOS:A1993MM65700004 ER PT J AU TIELENS, AGGM MEIXNER, MM VANDERWERF, PP BREGMAN, J TAUBER, JA STUTZKI, J RANK, D AF TIELENS, AGGM MEIXNER, MM VANDERWERF, PP BREGMAN, J TAUBER, JA STUTZKI, J RANK, D TI ANATOMY OF THE PHOTODISSOCIATION REGION IN THE ORION BAR SO SCIENCE LA English DT Article ID MOLECULAR-HYDROGEN EMISSION; INFRARED LINE OBSERVATIONS; CLUMPY STRUCTURE; MICRON EMISSION; BRIGHT BAR; M17 SW; NEBULA; MODEL; CARBON; CLOUDS AB Much of the interstellar gas resides in photodissociation regions whose chemistry and energy balance is controlled by the flux of far-ultraviolet radiation upon them. These photons can ionize and dissociate molecules and heat the gas through the photoelectric effect working on dust grains. These regions have been extensively modeled theoretically, but detailed observational studies are few. Mapping of the prominent Orion Bar photodissociation region at wavelengths corresponding to the carbon-hydrogen stretching mode of polycyclic aromatic hydrocarbons, the 1-0 S(1) line of molecular hydrogen, and the J = 1-0 rotational line of carbon monoxide allows the penetration of the far-ultraviolet radiation into the cloud to be traced. The results strongly support the theoretical models and show conclusively that the incident far-ultraviolet radiation field, not shocks as has sometimes been proposed, is responsible for the emission in the Orion Bar. C1 UNIV CALIF BERKELEY,RADIOASTRON LAB,BERKELEY,CA 94720. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. ESTEC,ESA,DIV ASTROPHYS,2200 AG NOORDWIJK,NETHERLANDS. UNIV CALIF SANTA CRUZ,LICK OBSERV,SANTA CRUZ,CA 95060. UNIV COLOGNE,INST PHYS 1,W-5000 COLOGNE 41,GERMANY. RP TIELENS, AGGM (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 40 TC 102 Z9 102 U1 3 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 1 PY 1993 VL 262 IS 5130 BP 86 EP 89 DI 10.1126/science.262.5130.86 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LZ635 UT WOS:A1993LZ63500026 PM 17742963 ER PT J AU SEIDEWITZ, E BALFOUR, B ADAMS, SS WADE, DM COX, B AF SEIDEWITZ, E BALFOUR, B ADAMS, SS WADE, DM COX, B TI DEVELOPING SOFTWARE FOR LARGE-SCALE REUSE SO SIGPLAN NOTICES LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. GEORGE MASON UNIV,FAIRFAX,VA 22030. NR 2 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0362-1340 J9 SIGPLAN NOTICES JI Sigplan Not. PD OCT PY 1993 VL 28 IS 10 BP 137 EP 143 PG 7 WC Computer Science, Software Engineering SC Computer Science GA MD098 UT WOS:A1993MD09800011 ER PT J AU STARK, M AF STARK, M TI IMPACTS OF OBJECT-ORIENTED TECHNOLOGIES - 7 YEARS OF SEL STUDIES SO SIGPLAN NOTICES LA English DT Article AB This paper examines the premise that object-oriented technology (OOT) is the most significant technology ever examined by the Software Engineering Laboratory. The evolution of the use of OOT in the Software Engineering Laboratory (SEL) ''Experience Factory'' is described in terms of the SEL's original expectations, focusing on how successive generations of projects have used OOT. General conclusions are drawn on how the usage of the technology has evolved in this environment. C1 NASA,GODDARD SPACE FLIGHT CTR,SOFTWARE ENGN BRANCH,GREENBELT,MD 20771. NR 4 TC 1 Z9 1 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0362-1340 J9 SIGPLAN NOTICES JI Sigplan Not. PD OCT PY 1993 VL 28 IS 10 BP 365 EP 373 PG 9 WC Computer Science, Software Engineering SC Computer Science GA MD098 UT WOS:A1993MD09800034 ER PT J AU LITVINTCHOUK, SD STARK, M BALFOUR, B FAYAD, M ROSENFELD, B AF LITVINTCHOUK, SD STARK, M BALFOUR, B FAYAD, M ROSENFELD, B TI EVOLVING TOWARD OBJECT-ORIENTED TECHNOLOGY IN LARGE ORGANIZATIONS SO SIGPLAN NOTICES LA English DT Article AB The Software Engineering Laboratory (SEL), sponsored by the NASA Goddard Space Flight Center, was created to investigate the effectiveness of software engineering technologies. At SEL, the initial experience with object-oriented technology has been positive. However, the successes achieved thus far took seven years to achieve. In this panel, we will explore how typical the SEL's experience is of large organizations doing large software developments. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0362-1340 J9 SIGPLAN NOTICES JI Sigplan Not. PD OCT PY 1993 VL 28 IS 10 BP 374 EP 375 PG 2 WC Computer Science, Software Engineering SC Computer Science GA MD098 UT WOS:A1993MD09800035 ER PT J AU WEBER, M BLASS, WE NADLER, S HALSEY, GW MAGUIRE, WC HILLMAN, JJ AF WEBER, M BLASS, WE NADLER, S HALSEY, GW MAGUIRE, WC HILLMAN, JJ TI L-RESONANCE EFFECTS IN C2H-2 NEAR 13.7 MU-M .2. THE 2 QUANTUM HOTBANDS SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Article ID LINEAR-MOLECULES; ACETYLENE; BANDS; REGION AB This article is the second part on l-resonance effects on the rotation-vibration bands of acetylene observed in the nu5 fundamental region. While the first part concentrated on the energy level analysis of the fundamental and the seven strongest hotbands originating in the nu4 and nu5 excited states for both major isotopes [Spectrochim. Acta 48A, 1203 (1992)], this article summarizes the results of the analysis of the hotbands 2nu4 + nu5 <-- 2nu4, nu4 + 2nu5 <-- nu4 + nu5, and 3nu5 <-- 2nu5 from which improved molecular constants for the 2nu4 and three quantum energy levels were derived for the major isotope (C2H2)-C-12. The mixing levels within the excited vibrational states due to vibrational and rotational l-resonance effects are discussed which lead to the identification of the strong ''forbidden'' DELTAl = 3 band, 2nu4 + nu5(3) <-- 2nu4(0e) as a result of l-resonance intensity perturbation. C1 UNIV TENNESSEE,DEPT PHYS,KNOXVILLE,TN 37996. RP WEBER, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 690,GREENBELT,MD 20771, USA. RI Blass, William/A-2792-2008; Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 21 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD OCT PY 1993 VL 49 IS 11 BP 1659 EP 1681 DI 10.1016/0584-8539(93)80124-S PG 23 WC Spectroscopy SC Spectroscopy GA LZ016 UT WOS:A1993LZ01600013 ER PT J AU NIKORA, VI SAPOZHNIKOV, VB NOEVER, DA AF NIKORA, VI SAPOZHNIKOV, VB NOEVER, DA TI FRACTAL GEOMETRY OF INDIVIDUAL RIVER CHANNELS AND ITS COMPUTER-SIMULATION SO WATER RESOURCES RESEARCH LA English DT Article ID MAINSTREAM LENGTH; CATCHMENT-AREA; NETWORKS AB A new method for analyzing the self-similarity and self-affinity of single-thread channels is proposed. It permits the determination of the fractal scaling exponents, of the characteristic scales, and the evaluation of the degree of anisotropy for self-similar fractal lines. Based upon the application of this method to the Dniester and Pruth rivers we established the self-similarity of the river pattern on small scales and the self-affinity on large scales. For these rivers we obtained the fractal scaling exponents, the characteristic scales, and the anisotropy parameters. A computer model has been developed which simulates river patterns whose fractal properties are close to the properties of natural objects. A generalized model of fractal behavior of natural rivers is proposed. On the basis of self-affinity of natural and simulated rivers on large scales, a hypothesis has been formulated which explains the violation of the dimension principle in the well-known relation between the river length and the catchment area, C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP NIKORA, VI (reprint author), ACAD SCI REPUBL MOLDOVA,INST GEOPHYS & GEOL,ACAD STR 3,KISHINEV 277028,MOLDOVA. NR 14 TC 24 Z9 31 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD OCT PY 1993 VL 29 IS 10 BP 3561 EP 3568 DI 10.1029/93WR00978 PG 8 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA MA368 UT WOS:A1993MA36800023 ER PT J AU GRESHO, PM GARTLING, DK TORCZYNSKI, JR CLIFFE, KA WINTERS, KH GARRATT, TJ SPENCE, A GOODRICH, JW AF GRESHO, PM GARTLING, DK TORCZYNSKI, JR CLIFFE, KA WINTERS, KH GARRATT, TJ SPENCE, A GOODRICH, JW TI IS THE STEADY VISCOUS INCOMPRESSIBLE 2-DIMENSIONAL FLOW OVER A BACKWARD-FACING STEP AT RE=800 STABLE SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE BACKWARD-FACING STEP; FLOW STABILITY; INCOMPRESSIBLE FLOW ID NAVIER-STOKES EQUATIONS; FINITE-ELEMENT METHOD; FLUID-DYNAMICS AB A detailed case study is made of one particular solution of the 2D incompressible Navier-Stokes equations. Careful mesh refinement studies were made using four different methods (and computer codes): (1) a high-order finite-element method solving the unsteady equations by time-marching; (2) a high-order finite-element method solving both the steady equations and the associated linear-stability problem; (3) a second-order finite difference method solving the unsteady equations in streamfunction form by time-marching; and (4) a spectral-element method solving the unsteady equations by time-marching. The unanimous conclusion is that the correct solution for flow over the backward-facing step at Re = 800 is steady-and it is stable, to both small and large perturbations. C1 SANDIA NATL LABS,ALBUQUERQUE,NM 87185. ASPENTEC UK LTD,CAMBRIDGE,ENGLAND. UNIV BATH,SCH MATH SCI,BATH BA2 7AY,AVON,ENGLAND. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP GRESHO, PM (reprint author), LAWRENCE LIVERMORE NATL LAB,POB 808,LIVERMORE,CA 94551, USA. NR 44 TC 102 Z9 103 U1 0 U2 11 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD SEP 30 PY 1993 VL 17 IS 6 BP 501 EP 541 DI 10.1002/fld.1650170605 PG 41 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA LW726 UT WOS:A1993LW72600004 ER PT J AU WEITZ, CM BASILEVSKY, AT AF WEITZ, CM BASILEVSKY, AT TI MAGELLAN OBSERVATIONS OF THE VENERA AND VEGA LANDING SITE REGIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID RADAR REFLECTIVITY; VENUS; SURFACE; GEOLOGY; ARECIBO; PLAINS AB Geologic maps have been produced for each of the seven Venera/Vega landing sites on Venus. The dominant terrain identified at all the sites is plains. The sites contain minor amounts of complex ridge terrain (CRT). complex terrain (CT), and an older plains (P(o)) that are all embayed by younger plains (P(y)). Some of the sites (Venera 9 and Vega 1 and 2) are made up of vast regional plains units while the other sites (Venera 8, 10, 13, and 14) contain more localized plains. The Venera 8 and 13 sites have unusual volcanic features associated with them and a nontholeiitic composition was measured by the landers at these sites. At the other five sites where a tholeiitic composition was measured, lava flows with morphologies that suggest an apparent low viscosity have been identified. This indicates a good correspondence between the geochemistry measured by the landers and the Magellan imagery. A good correlation also exists between the TV panoramas taken by four of the landers and the Magellan imagery. At the Venera 9, 10, 14 and Vega 1, 2 sites, the most likely material sampled are plains composed of tholeiitic lavas. A steep-sided dome, lamprophyre-like lavas, or ash beds are the most likely material sampled by the Venera 8 lander. The Venera 13 lander may have sampled lava flows from a corona-like feature or from a steep-sided dome in the southeast of the landing circle. Radiophysical properties of the landing sites show a good correspondence with the local geology, with most variations in backscatter, emissivity, and rms slopes reflecting differences in surface roughness. The Venera/Vega sites are good examples of typical venusian plains, indicating that geochemical measurements and TV observations provide representative characteristics of this most abundant terrain type on Venus. C1 BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. RUSSIAN ACAD SCI,VERNADSKY INST,MOSCOW,RUSSIA. RP WEITZ, CM (reprint author), JET PROP LAB,4800 OAK GROVE DR,M-S 300-233,PASADENA,CA 91109, USA. NR 32 TC 20 Z9 20 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1993 VL 98 IS E9 BP 17069 EP 17097 DI 10.1029/93JE01776 PG 29 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MA452 UT WOS:A1993MA45200005 ER PT J AU MONKS, PS ROMANI, PN NESBITT, FL SCANLON, M STIEF, LJ AF MONKS, PS ROMANI, PN NESBITT, FL SCANLON, M STIEF, LJ TI THE KINETICS OF THE FORMATION OF NITRILE COMPOUNDS IN THE ATMOSPHERES OF TITAN AND NEPTUNE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CN RADICAL REACTIONS; TEMPERATURE-DEPENDENCE; ORGANIC-CHEMISTRY; RATE CONSTANTS; PHOTOCHEMISTRY; ATOMS; HCN; SPECTRA; RANGE; C2H4 AB The nitrile compounds HCN and C2HCN (cyanoacetylene) were detected on Titan by Voyager 1. The ethylene-analog nitrile to cyanoacetylene C2H3CN (acrylonitrile) remains undetected. More recently, ground-based observers have detected HCN on Neptune and placed an upper limit on C2HCN. Kinetic aspects of the formation of acrylonitrile have been studied in a discharge-flow mass spectrometric system at T = 298 K. The fractional yield for the formation of acrylonitrile from the fast gas phase reaction CN + C2H4 --> C2H3CN + H has been determined to be (0.2 +/- 0.1). The other possible gas phase reaction leading to the formation of acrylonitrile, HCN + C2H3 --> C2H3CN + H, has been determined to be slow under planetary conditions at k(T = 298 K) = 2-7 x 10(-14) cm3 molecule-1 s-1, but remains an important chemical sink for HCN. The planetary implications of the results are discussed in terms of the ratio of acrylonitrile to cyanoacetylene on Titan and Neptune. C1 COPPIN STATE COLL,DEPT NATL SCI,BALTIMORE,MD 21216. FAIRMONT STATE COLL,DEPT CHEM,FAIRMONT,WV 26554. RP MONKS, PS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Romani, Paul/D-2729-2012; Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 44 TC 36 Z9 36 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1993 VL 98 IS E9 BP 17115 EP 17122 DI 10.1029/93JE01789 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA MA452 UT WOS:A1993MA45200007 ER PT J AU SODUPE, M BAUSCHLICHER, CW AF SODUPE, M BAUSCHLICHER, CW TI A THEORETICAL-STUDY OF THE SPECTROSCOPY OF SRH2O+ AND SRNH3+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID PHOTODISSOCIATION SPECTROSCOPY; BASIS SETS; SPECTRA; ATOMS; IONS AB The structure, binding energies, and vibrational frequencies are determined for the excited states of SrH2O+ and SrNH3+ to supplement our previous results for the ground state and vertical excitation energies. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 14 TC 11 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD SEP 24 PY 1993 VL 212 IS 6 BP 624 EP 630 DI 10.1016/0009-2614(93)85495-A PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LX798 UT WOS:A1993LX79800011 ER PT J AU RIGNOT, EJ OSTRO, SJ VANZYL, JJ JEZEK, KC AF RIGNOT, EJ OSTRO, SJ VANZYL, JJ JEZEK, KC TI UNUSUAL RADAR ECHOES FROM THE GREENLAND ICE-SHEET SO SCIENCE LA English DT Article ID COHERENT-BACKSCATTER; POLARIZATION AB Airborne radar images of part of the Greenland ice sheet reveal icy terrain whose radar properties are unique among radar-studied terrestrial surfaces but resemble those of Jupiter's icy Galilean satellites. The 5.6- and 24-centimeter-wavelength echoes from the Greenland percolation zone, like the 3.5- and 13-centimeter-wavelength echoes from the icy satellites, are extremely intense and have anomalous circular and linear polarization ratios. However, the detailed subsurface configurations of the Galilean satellite regoliths, where heterogeneities are the product of prolonged meteoroid bombardment, are unlikely to resemble that within the Greenland percolation zone, where heterogeneities are the product of seasonal melting and refreezing. C1 OHIO STATE UNIV,BYRD POLAR RES CTR,COLUMBUS,OH 43210. RP RIGNOT, EJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 20 TC 28 Z9 28 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 24 PY 1993 VL 261 IS 5129 BP 1710 EP 1713 DI 10.1126/science.261.5129.1710 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LY584 UT WOS:A1993LY58400019 PM 17794875 ER PT J AU PODOLSKE, J LOEWENSTEIN, M AF PODOLSKE, J LOEWENSTEIN, M TI AIRBORNE TUNABLE DIODE-LASER SPECTROMETER FOR TRACE-GAS MEASUREMENT IN THE LOWER STRATOSPHERE SO APPLIED OPTICS LA English DT Article DE TUNABLE DIODE LASER; ATMOSPHERIC SPECTROSCOPY; NITROUS OXIDE ID ANTARCTIC OZONE EXPERIMENT; NITROUS-OXIDE; ABSORPTION SPECTROMETER; AIRCRAFT MEASUREMENTS; CARBON-MONOXIDE; SEPTEMBER 1987; POLAR VORTEX; WINTER; NO2; HCL AB This paper describes the airborne tunable laser absorption spectrometer, a tunable diode laser instrument designed for in situ trace-gas measurement in the lower stratosphere from an ER-2 high-altitude research aircraft. Laser-wavelength modulation and second-harmonic detection are employed to achieve the required constituent detection sensitivity. The airborne tunable laser absorption spectrometer was used in two polar ozone campaigns, the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition, and measured nitrous oxide with a response time of ls and an accuracy less-than-or-equal-to 10%. RP PODOLSKE, J (reprint author), NASA, AMES RES CTR, DIV EARTH SYST SCI, MOFFETT FIELD, CA 94035 USA. NR 37 TC 70 Z9 70 U1 1 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 1993 VL 32 IS 27 BP 5324 EP 5333 PG 10 WC Optics SC Optics GA LX590 UT WOS:A1993LX59000017 PM 20856342 ER PT J AU WOLFIRE, MG KONIGL, A AF WOLFIRE, MG KONIGL, A TI MOLECULAR LINE EMISSION MODELS OF HERBIG-HARO OBJECTS .2. HCO+ EMISSION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, JETS AND OUTFLOWS; MOLECULAR PROCESSES; STARS, PRE-MAIN-SEQUENCE ID PHOTODISSOCIATION REGIONS; INFRARED-EMISSION; DISSOCIATIVE RECOMBINATION; ROTATIONAL-EXCITATION; INTERSTELLAR CLOUDS; SUPERNOVA REMNANT; PROPER MOTIONS; BOW SHOCK; HH-1; H-2 AB We present time-dependent models of the chemistry and temperature of interstellar molecular gas clumps that are exposed to the radiation from propagating stellar-jet shocks. The X-ray, EUV, and FUV radiation from the shock initiates ion chemistry and also heats the gas in the clumps. Using representative parameters, we show that, on the shock transit time between the clumps, the abundances of the ionized molecular species that are produced in the clumps can exceed the values determined from steady state models by several orders of magnitude. Collisional excitation by the heated gas can lead to measurable line emission from several ionized species; as in previous investigations of X-ray-irradiated molecular gas, we find that electron impacts contribute significantly to this process. We apply these results to the interpretation of the HCO+ line emission that has already been detected in several Herbig-Haro objects (including HH 1-2, HH 34S, and HH 7-11). We demonstrate that this picture provides a natural explanation of the fact that the line intensity typically peaks ahead of the associated shock, as well as of the reported low line-center velocities and narrow line widths. We tabulate several diagnostic line intensities of HCO+ and other molecular species that may be used to infer the physical conditions in the emitting gas. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. RP WOLFIRE, MG (reprint author), NASA,AMES RES CTR,MS 2453,MOFFETT FIELD,CA 94035, USA. NR 54 TC 37 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP 204 EP 217 DI 10.1086/173156 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW899 UT WOS:A1993LW89900020 ER PT J AU STEINACKER, J JAEKEL, U SCHLICKEISER, R AF STEINACKER, J JAEKEL, U SCHLICKEISER, R TI ION-ACCELERATION IN IMPULSIVE SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; MHD; SUN, FLARES; SUN, PARTICLE EMISSIONS ID GYRORESONANT ELECTRON ACCELERATION; COSMIC-RAY TRANSPORT; LOW-BETA PLASMA; PARTICLE-ACCELERATION; SHOCK-WAVE; TURBULENCE; DIFFUSION; SPECTRA; EVENTS; FIELDS AB Nonrelativistic spectra of protons and ions accelerated in impulsive solar flares are derived using more realistic turbulence power spectra. The calculation is based on a particle transport equation extracted from a second step acceleration model containing stochastic acceleration. The turbulence model is generalized to waves with a small angle to the magnetic field vector and to turbulence power spectra with spectral indices s smaller than 2. Due to the occurrence of impulsive flares at low coronal heights Coulomb losses at the dense coronal plasma and diffusive particle escape are taken into account. The ion spectra show deviations from long-duration spectra near the Coulomb barrier, where the losses become maximal. The Z2/A-dependence of the Coulomb losses leads to spectral variations for different ions. We present a method to estimate the turbulence parameter s and injection conditions of the flare particles using ion ratios like Fe/O of impulsive flares. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. MAX PLANCK INST RADIOASTRON,D-53121 BONN,GERMANY. NR 43 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP 342 EP 353 DI 10.1086/173168 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW899 UT WOS:A1993LW89900032 ER PT J AU STEINOLFSON, RS DAVILA, JM AF STEINOLFSON, RS DAVILA, JM TI CORONAL HEATING BY THE RESONANT ABSORPTION OF ALFVEN WAVES - IMPORTANCE OF THE GLOBAL MODE AND SCALING LAWS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CORONA ID NON-UNIFORM PLASMA; SURFACE-WAVES; SOLAR CORONA; RESISTIVE MAGNETOHYDRODYNAMICS; TEARING MODE; LOOPS; SIMULATION; DYNAMICS; DECAY; IDEAL AB Numerical simulations of the MHD equations for a fully compressible, low-beta, resistive plasma are used to study the resonance absorption process for the heating of coronal active region loops. Comparisons with more approximate analytic models show that the major predictions of the analytic theories are, to a large extent, confirmed by the numerical computations. The simulations demonstrate that the dissipation occurs primarily in a thin resonance layer. Some of the analytically predicted features verified by the simulations are (a) the position of the resonance layer within the initial inhomogeneity; (b) the importance of the global mode for a large range of loop densities; (c) the dependence of the resonance layer thickness and the steady-state heating rate on the dissipation coefficient; and (d) the time required for the resonance layer to form. In contrast with some previous analytic and simulation results, the time for the loop to reach a steady state is found to be the phase-mixing time rather than a dissipation time. This disagreement is shown to result from neglect of the existence of the global mode in some of the earlier analyses. The resonant absorption process is also shown to behave similar to a classical driven harmonic oscillator. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP SW RES INST, DEPT SPACE SCI, SAN ANTONIO, TX 78228 USA. NR 34 TC 91 Z9 91 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP 354 EP 363 DI 10.1086/173169 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW899 UT WOS:A1993LW89900033 ER PT J AU SCHUTTE, WA TIELENS, AGGM ALLAMANDOLA, LJ AF SCHUTTE, WA TIELENS, AGGM ALLAMANDOLA, LJ TI THEORETICAL MODELING OF THE INFRARED FLUORESCENCE FROM INTERSTELLAR POLYCYCLIC AROMATIC-HYDROCARBONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, LINES; ISM, MOLECULES; LINE, IDENTIFICATIONS; MOLECULAR PROCESSES ID MICRON EMISSION FEATURES; IRAS SOURCES; AMORPHOUS-CARBON; TEMPERATURE-FLUCTUATIONS; OPTICAL-PROPERTIES; IONIZATION FRONT; SILICATE GRAINS; HIGH-RESOLUTION; NGC 7027; SPECTRUM AB We have modeled the family of interstellar IR emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 mum by calculating the fluorescence from a size distribution of interstellar polycyclic aromatic hydrocarbons (PAHs) embedded in the radiation field of a hot star. It is found that the various emission bands are dominated by distinctly different PAHs, from molecules with much less than approximately 80 C atoms for the 3.3 mum feature, to molecules with 10(2)-10(5) C atoms for the emission in the IRAS 12 and 25 mum bands. We quantitatively describe the influence on the emergent spectrum of various PAH properties such as the molecular structure, the amount of dehydrogenation, the intrinsic strength of the IR active modes, and the size distribution. Comparing our model results to the emission spectrum from the Orion Bar region, we conclude that interstellar PAHs are likely fully, or almost fully, hydrogenated. Moreover, it is found that the intrinsic strengths of the 6.2 and 7.7 mum C-C stretching modes, and the 8.6 mum C-H in-plane bending mode are 2-6 times larger than measured for neutral PAHs in the laboratory. This difference is tentatively ascribed to interstellar PAHs being ionized, or, alternatively, to their being highly asymmetric. It is furthermore concluded that the earlier assignment of the 3.4 mum subfeature to the hot band of the aromatic C-H stretching mode is only marginally consistent with the available observational data. In some cases an additional component appears to be required to account for its intensity. The hot band may be responsible for a weaker shoulder in some cases. An assignment to the C-H stretching feature from ''superhydrogenated'' PAHs, i.e., PAHs with extra H atoms attached to the peripheral carbon atoms, is considered as the additional contributor. Finally, it is pointed out how future high-quality observations of the emission from interstellar PAHs covering a large wavelength range, together with modeling of the type presented in the paper, could be used to study a number of important questions, such the preferred molecular structures of interstellar PAHs and their evolution in the interstellar medium. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. NR 78 TC 235 Z9 235 U1 0 U2 14 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP 397 EP 414 DI 10.1086/173173 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW899 UT WOS:A1993LW89900037 ER PT J AU GRADY, CA BJORKMAN, KS SHEPHERD, D SCHULTELADBECK, RE PEREZ, MR DEWINTER, D THE, PS AF GRADY, CA BJORKMAN, KS SHEPHERD, D SCHULTELADBECK, RE PEREZ, MR DEWINTER, D THE, PS TI DETECTION OF ACCRETING GAS TOWARD HD-45677 - A NEWLY RECOGNIZED, HERBIG BE PROTO PLANETARY SYSTEM SO ASTROPHYSICAL JOURNAL LA English DT Article DE HD-45677; STARS, PRE-MAIN-SEQUENCE; ULTRAVIOLET, STARS ID STAR HD-45677; EMISSION-LINE; CANIS MAJORIS; AE/BE STARS; PECULIAR; OBJECTS; ORIONIS; DISKS AB We report detection of high-velocity, accreting gas toward the B[e] star with IR excess and bipolar nebula, HD 45677. High-velocity (+200 to +400 km s-1), variable column density gas is visible in all IUE spectra from 1979 to 1992 in transitions of Si II, C II, Al III, Fe III, Si IV, and C IV. Low-velocity absorption profiles from low oscillator strength transitions of Si II, Fe II, and Zn II exhibit double-peaked absorption profiles similar to those previously reported in optical spectra of FU Orionis objects. The UV absorption data, together with previously reported analyses of the IR excess and polarization of this object, suggest that HD 45677 is a massive, Herbig Be star with an actively accreting circumstellar, proto-planetary disk. C1 UNIV WISCONSIN,SPACE ASTRON LAB,MADISON,WI 53706. UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. NASA,GODDARD SPACE FLIGHT CTR,GSFC,IUE OBSERV,CSC,ASTRON PROGRAMS,GREENBELT,MD 20771. UNIV AMSTERDAM,ASTRON INST ANTON PANNEKOEK,1098 SJ AMSTERDAM,NETHERLANDS. RP GRADY, CA (reprint author), APPL RES CORP,8201 CORP DR,SUITE 1120,LANDOVER,MD 20785, USA. NR 38 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP L39 EP & DI 10.1086/187027 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW901 UT WOS:A1993LW90100010 ER PT J AU STEIGMAN, G FIELDS, BD OLIVE, KA SCHRAMM, DN WALKER, TP AF STEIGMAN, G FIELDS, BD OLIVE, KA SCHRAMM, DN WALKER, TP TI POPULATION-II LI-6 AS A PROBE OF NUCLEOSYNTHESIS AND STELLAR STRUCTURE AND EVOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ABUNDANCES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; STARS, ABUNDANCES ID HALO-STARS; PRIMORDIAL LITHIUM; DISK-STARS; ABUNDANCE; DWARFS; METALLICITY; BERYLLIUM; OXYGEN; GALAXY; BE-9 AB We discuss the importance of Population II Li-6 as a diagnostic for models of primordial nucleosynthesis, cosmic-ray nucleosyntheses in the early Galaxy, and the structure and evolution of metal-poor solar-type stars. The observation of Li-6 in the subdwarf HD 84937 is shown to be consistent with the existing Population II LiBeB data within the context of a simple three-component model: (1) standard big bang nucleosynthesis, (2) Population II cosmic-ray nucleosynthesis, (3) standard (nonrotating) stellar LiBeB depletion. If this interpretation is correct, we predict a potentially detectable boron abundance for this star: B/H approximately 2 x 10(-12). Subsequent Population II LiBeB observations, and in particular further observations of Population II Li-6, are shown to be crucial to our understanding of the primordial and early galactic creation and destruction mechanisms for light elements. C1 FNAL,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. UNIV CHICAGO,CHICAGO,IL 60637. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. RP STEIGMAN, G (reprint author), OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210, USA. NR 36 TC 59 Z9 59 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP L35 EP L38 DI 10.1086/187026 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW901 UT WOS:A1993LW90100009 ER PT J AU THOMPSON, DJ BERTSCH, DL DINGUS, BL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, EJ SREEKUMAR, P AF THOMPSON, DJ BERTSCH, DL DINGUS, BL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL SCHNEID, EJ SREEKUMAR, P TI EGRET OBSERVATIONS OF ACTIVE GALACTIC NUCLEI - 0836+710, 0454-234, 0804+499, 0906+430, 1510-089, AND 2356+196 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, OBSERVATIONS; QUASARS, GENERAL ID COMPLETE SAMPLE; RADIO-SOURCES; TELESCOPE; JET; POLARIZATION; QUASARS; SPECTRA; 3C-279; GHZ AB The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory observed high-energy gamma rays (50 MeV less-than-or-equal-to E less-than-or-equal-to 2000 MeV) from quasar 0836+710 (z = 2.16) during observations in 1992 January, near the time of an optical flare (von Linde et al. 1993). The gamma-ray spectrum can be fitted with a power law with photon number index 2.4 +/- 0.2. EGRET identifies quasars 0454-234, 0804+499, 0906+430, 1510-089, and 2356+196 at a statistical significance of between 4 and 5 standard deviations. C1 MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. COMP SCI CORP,ASTRON PROGRAMS,COMPTON OBSERV SCI SUPPORT CTR,GREENBELT,MD 20770. HAMPDEN SYDNEY COLL,DEPT PHYS,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP THOMPSON, DJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 662,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 42 TC 62 Z9 64 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1993 VL 415 IS 1 BP L13 EP L16 DI 10.1086/187021 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW901 UT WOS:A1993LW90100004 ER PT J AU JOHNSON, JE KOROPALOV, VM PICKERING, KE THOMPSON, AM BOND, N ELKINS, JW AF JOHNSON, JE KOROPALOV, VM PICKERING, KE THOMPSON, AM BOND, N ELKINS, JW TI 3RD SOVIET-AMERICAN GASES AND AEROSOLS (SAGA-3) EXPERIMENT - OVERVIEW AND METEOROLOGICAL AND OCEANOGRAPHIC CONDITIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PACIFIC; OCEAN; EXCHANGE; SULFUR; OXIDE; FLUX AB The primary goal of the third joint Soviet-American Gases and Aerosols (SAGA 3) experiment was to study trace gases and aerosols in the remote marine boundary layer. SAGA 3/leg 1 took place from February 13 to March 13, 1990, aboard the former Soviet R/V Akademik Korolev and consisted of five equatorial transects (designated transects 1 through 5) between 15-degrees-N and 10-degrees-S on a cruise track from Hilo, Hawaii, to Pago-Pago, American Samoa. Specific objectives were to study (1) the oceanic distribution and air-sea exchange of biogenic trace gases; (2) photochemical cycles of C-, S-, and N-containing gases in the marine boundary layer; (3) the distribution of aerosol particles in the marine boundary layer and their physical and chemical properties; (4) interhemispheric gradients and latitudinal mixing of trace gases and aerosols; and (5) stratospheric aerosol layers. SAGA 3/leg 2 continued from March 17 to April 7, 1990, with one more equatorial transect between American Samoa and the northern coast of the Philippines (transect 6) followed by a final transect to Singapore (transect 7). During leg 2, most former Soviet measurements continued, but with the exception of measurements of nitrous oxide (N2O) and selected halocarbons in the air and surface waters all American measurements ceased. This paper briefly summarizes the chemical measurements made by SAGA 3 investigators and presents in some detail the meteorological and hydrological characteristics encountered during SAGA 3. The meteorological analysis is based on atmospheric soundings of temperature, humidity, winds, sea surface temperature, postcruise back trajectories of winds, and satellite imagery. In general, the meteorology during SAGA 3 was typical of the location and time of year. Exceptions to this include an incipient E1 Nino that never developed fully, a poorly defined ITCZ on 4 of 6 equator crossings, wind speeds that were 20% greater than the decadal mean, a convective event that brought midtropospheric air to the surface (on Julian day 59), and transport of northern hemispheric air to 18-degrees-S during a synoptic scale tropical disturbance C1 UNIV WASHINGTON,JOINT INST STUDY ATMOSPHERE & OCEAN,SEATTLE,WA 98195. INST APPL GEOPHYS,MOSCOW,RUSSIA. UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. RP JOHNSON, JE (reprint author), NOAA,PACIFIC MARINE ENVIRONM LAB,7600 SAND POINT WAY NE,SEATTLE,WA 98115, USA. RI Pickering, Kenneth/E-6274-2012; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 31 TC 18 Z9 18 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1993 VL 98 IS D9 BP 16893 EP 16908 DI 10.1029/93JD00566 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY330 UT WOS:A1993LY33000029 ER PT J AU ATLAS, E POLLOCK, W GREENBERG, J HEIDT, L THOMPSON, AM AF ATLAS, E POLLOCK, W GREENBERG, J HEIDT, L THOMPSON, AM TI ALKYL NITRATES, NONMETHANE HYDROCARBONS, AND HALOCARBON GASES OVER THE EQUATORIAL PACIFIC-OCEAN DURING SAGA-3 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ORGANIC NITRATES; ANTARCTIC TROPOSPHERE; MAUNA-LOA; ATMOSPHERE; CHEMISTRY; AIR; PHOTOOXIDATIONS; BROMOFORM; ALKANES; OZONE AB The third joint Soviet-American Gases and Aerosols (SAGA 3) experiment was a research cruise conducted aboard the Akademik Korolev in February and March 1990. The cruise covered a region of the equatorial Pacific Ocean from 15-degrees-N to 10-degrees-S latitude and 144-degrees to 165-degrees W longitude. On this cruise we collected samples for the measurement of alkyl nitrates (RONO2), nonmethane hydrocarbons (NMHC) and several halocarbon gases. Though there are few data available for comparison in this region of the marine boundary layer, the mixing ratios of the trace gases we measured are within the range of prior measurements in the remote atmosphere. Latitudinal gradients were found for trace gases with predominantly anthropogenic sources, e.g., methylene chloride, tetrachloroethylene, and acetylene; higher concentrations in the North Pacific atmosphere decreased slowly across the Equator to the South Pacific. More stable gases, e.g. methyl chloride and methyl bromide, had no pronounced variation across the equator. A biogenic source of two organobromine compounds, bromoform and dibromochloromethane, was indicated by maximum mixing ratios of these species over the equator where indicators of biological productivity (e.g., chlorophyll) in the surface ocean water also maximized. Alkyl nitrates were found at levels higher than predicted from steady state calculations based on measured mixing ratios of hydrocarbons and NO. The measured levels of RONO2 suggest long-range transport as one mechanism contributing to elevated concentrations of alkyl nitrates in the remote troposphere. However, the distributions of C2 and C3 alkyl nitrates over the equator were similar to the organobromine gases. This distribution suggests a possible oceanic source for alkyl nitrates to the atmosphere. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ATLAS, E (reprint author), NATL CTR ATMOSPHER RES,DIV ATMOSPHER CHEM,POB 3000,BOULDER,CO 80307, USA. RI Atlas, Elliot/J-8171-2015; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 45 TC 130 Z9 130 U1 0 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1993 VL 98 IS D9 BP 16933 EP 16947 DI 10.1029/93JD01005 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY330 UT WOS:A1993LY33000032 ER PT J AU TORRES, AL THOMPSON, AM AF TORRES, AL THOMPSON, AM TI NITRIC-OXIDE IN THE EQUATORIAL PACIFIC BOUNDARY-LAYER - SAGA-3 MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID UNITED-STATES SITE; ORGANIC NITRATES; TROPOSPHERIC OZONE; PHOTOLYSIS; CHEMISTRY; KINETICS; BUDGETS; ORIGIN; CLOUDS; MODEL AB As part of the Soviet-American Gases and Aerosols (SAGA) experiment, mixing ratios of atmospheric nitric oxide were measured at the surface of the equatorial Pacific Ocean between Hawaii and American Samoa during February and March 1990. Overall, NO mixing ratios for measurements made between 0800 and 1600 LT averaged 2.9 +/- 0.1 parts per trillion by volume (pptv), where the uncertainties represent 95% confidence limits in the mean. Concentrations were generally highest near the equator: NO mixing ratios obtained between 0800 and 1600 LT averaged 4.0 +/- 0.2 pptv in the 5-degrees-S-5-degrees-N latitude band and 2.1 +/- 0.2 pptv in the 5-degrees-15-degrees bands north and south of the equator. In the equatorial band the average diurnal behavior was a steady rise in NO from early morning until local noon, reaching a peak of about 4.5 pptv that remained until late afternoon before beginning a rapid decline. In the 5-degrees-15-degrees bands north and south of the equator the average diurnal curve for NO was flat (within experimental uncertainties) at about 2 pptv from 0800 to 1600. These findings are consistent with previous measurements of NO in both boundary layer and free tropospheric remote Pacific environments. They confirm a picture of the remote equatorial Pacific boundary layer as a region of low NO and net photochemical destruction Of O3. The NO and O3 measured on SAGA 3 correspond to a loss rate of ozone of approximately 1 parts per billion by volume (ppbv) O3/day in a region where mean surface O3 is 10 ppbv. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP TORRES, AL (reprint author), NASA,GSFC,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 34 TC 43 Z9 43 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1993 VL 98 IS D9 BP 16949 EP 16954 DI 10.1029/92JD01906 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY330 UT WOS:A1993LY33000033 ER PT J AU THOMPSON, AM JOHNSON, JE TORRES, AL BATES, TS KELLY, KC ATLAS, E GREENBERG, JP DONAHUE, NM YVON, SA SALTZMAN, ES HEIKES, BG MOSHER, BW SHASHKOV, AA YEGOROV, VI AF THOMPSON, AM JOHNSON, JE TORRES, AL BATES, TS KELLY, KC ATLAS, E GREENBERG, JP DONAHUE, NM YVON, SA SALTZMAN, ES HEIKES, BG MOSHER, BW SHASHKOV, AA YEGOROV, VI TI OZONE OBSERVATIONS AND A MODEL OF MARINE BOUNDARY-LAYER PHOTOCHEMISTRY DURING SAGA-3 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EQUATORIAL PACIFIC; ORGANIC NITRATES; ATMOSPHERIC MEASUREMENTS; DIMETHYL SULFIDE; UNITED-STATES; NITRIC-OXIDE; OCEAN; TROPOSPHERE; TRANSPORT; CHEMISTRY AB A major purpose of the third joint Soviet-American Gases and Aerosols (SAGA 3) oceanographic cruise was to examine remote tropical marine O3 and photochemical cycles in detail. On leg 1, which took place between Hilo, Hawaii, and Pago-Pago, American Samoa, in February and March 1990, shipboard measurements were made Of O3, CO, CH4, nonmethane hydrocarbons (NMHC), NO, dimethyl sulfide (DMS), H2S, H2O2, organic peroxides, and total column O3. Postcruise analysis was performed for alkyl nitrates and a second set of nonmethane hydrocarbons. A latitudinal gradient in O3 was observed on SAGA 3, with O3 north of the intertropical convergence zone (ITCZ) at 15-20 parts per billion by volume (ppbv) and less than 12 ppbv south of the ITCZ but never less-than-or-equal-to 3 ppbv as observed on some previous equatorial Pacific cruises (Piotrowicz et al., 1986; Johnson et al., 1990). Total column O3 (230-250 Dobson units (DU)) measured from the Akademik Korolev was within 8% of the corresponding total ozone mapping spectrometer (TOMS) satellite observations and confirmed the equatorial Pacific as a low O3 region. In terms of number of constituents measured, SAGA 3 may be the most photochemically complete at-sea experiment to date. A one-dimensional photochemical model gives a self-consistent picture of O3-NO-CO-hydrocarbon interactions taking place during SAGA 3. At typical equatorial conditions, mean O3 is 10 ppbv with a 10-15% diurnal variation and maximum near sunrise. Measurements of O3, CO, CH4, NMHC, and H2O constrain model-calculated OH to 9 x 10(5) cm-3 for 10 ppbv O3 at the equator. For DMS (300-400 parts per trillion by volume (pptv)) this OH abundance requires a sea-to-air flux of 6-8 x 10(9) cm-2 s-1, which is within the uncertainty range of the flux deduced from SAGA 3 measurements of DMS in seawater (Bates et al., this issue). The concentrations of alkyl nitrates on SAGA 3 (5-15 pptv total alkyl nitrates) were up to 6 times higher than expected from currently accepted kinetics, suggesting a largely continental source for these species. However, maxima in isopropyl nitrate and bromoform near the equator (Atlas et al., this issue) as well as for nitric oxide (Torres and Thompson, this issue) may signify photochemical and biological sources of these species. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NOAA,PACIFIC MARINE ENVIRONM LAB,SEATTLE,WA 98115. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV RHODE ISL,GRAD SCH OCEANOG,KINGSTON,RI 02882. UNIV NEW HAMPSHIRE,DURHAM,NH 03824. UNIV MIAMI,ROSENSTIEL SCH MARINE & ATMOSPHER SCI,MIAMI,FL 33149. MAIN GEOPHYS OBSERV,ST PETERSBURG,RUSSIA. NASA,GODDARDS SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. INST APPL PHYS,ATMOSPHER MONITORING LAB,MOSCOW,RUSSIA. RP THOMPSON, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 916,GREENBELT,MD 20771, USA. RI Donahue, Neil/A-2329-2008; Yvon-Lewis, Shari/E-4108-2012; Mason, Robert/A-6829-2011; Atlas, Elliot/J-8171-2015; Bates, Timothy/L-6080-2016; Thompson, Anne /C-3649-2014 OI Donahue, Neil/0000-0003-3054-2364; Yvon-Lewis, Shari/0000-0003-1378-8434; Thompson, Anne /0000-0002-7829-0920 NR 41 TC 103 Z9 103 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1993 VL 98 IS D9 BP 16955 EP 16968 DI 10.1029/93JD00258 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LY330 UT WOS:A1993LY33000034 ER PT J AU ROSENFELD, D ALTEROVITZ, SA AF ROSENFELD, D ALTEROVITZ, SA TI THE EFFECTS OF STRAIN ON THE MICROWAVE PERFORMANCE OF SIGE HBTS SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE STRAIN; CUTOFF FREQUENCY; MAXIMUM FREQUENCY; HETEROJUNCTION BIPOLAR TRANSISTOR; SILICON-GERMANIUM AB The results of a theoretical study of the effects of the strain on the cutoff frequencies of SiGe HBTs are presented. The influence of the strain on the base resistance and transit time, and through them on high-frequency performance, was taken into account. The positive role played by the strain is demonstrated. (C) 1993 John Wiley & Sons, Inc. RP ROSENFELD, D (reprint author), NASA,LEWIS RES CTR,M-S 54-5,2100 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD SEP 20 PY 1993 VL 6 IS 12 BP 689 EP 692 DI 10.1002/mop.4650061207 PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA LR842 UT WOS:A1993LR84200006 ER PT J AU BLUTH, GJS AF BLUTH, GJS TI HOT PAPERS - GEOPHYSICS - GLOBAL TRACKING OF THE SO2 CLOUDS FROM THE JUNE, 1991 MOUNT-PINATUBO ERUPTIONS BY BLUTH,G.J.S., DOIRON,S.D., SCHNETZLER,C.C., ET-AL SO SCIENTIST LA English DT Article AB A geophysicist discusses the climatological effects of the eruption of the Mount Pinatubo volcano. RP BLUTH, GJS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771, USA. NR 2 TC 0 Z9 0 U1 0 U2 2 PU SCIENTIST INC PI PHILADELPHIA PA 3600 MARKET ST SUITE 450, PHILADELPHIA, PA 19104 SN 0890-3670 J9 SCIENTIST JI Scientist PD SEP 20 PY 1993 VL 7 IS 18 BP 16 EP 16 PG 1 WC Information Science & Library Science; Multidisciplinary Sciences SC Information Science & Library Science; Science & Technology - Other Topics GA LX107 UT WOS:A1993LX10700012 ER PT J AU BERKE, L PATNAIK, SN MURTHY, PLN AF BERKE, L PATNAIK, SN MURTHY, PLN TI OPTIMUM DESIGN OF AEROSPACE STRUCTURAL COMPONENTS USING NEURAL NETWORKS SO COMPUTERS & STRUCTURES LA English DT Article AB The application of artificial neural networks to capture structural design expertise is demonstrated. The principal advantage of a trained neural network is that it requires a trivial computational effort to produce an acceptable new design. For the class of problems addressed, the development of a conventional expert system would be extremely difficult. In the present effort, a structural optimization code with multiple nonlinear programming algorithms and an artificial neural network code NETS were used. A set of optimum designs for a ring and two aircraft wings for static and dynamic constraints were generated using the optimization codes. The optimum design data were processed to obtain input and output pairs, which were used to develop a trained artificial neural network using the code NETS. Optimum designs for new design conditions were predicted using the trained network. Neural net prediction of optimum designs was found to be satisfactory for the majority of the output design parameters. However, results from the present study indicate that caution must be exercised to ensure that all design variables are within selected error-bounds. C1 OHIO AEROSP INST,CLEVELAND,OH 44135. RP BERKE, L (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 24 Z9 30 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD SEP 17 PY 1993 VL 48 IS 6 BP 1001 EP 1010 DI 10.1016/0045-7949(93)90435-G PG 10 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA MG377 UT WOS:A1993MG37700005 ER PT J AU SWARTZ, DA CLOCCHIATTI, A BENJAMIN, R LESTER, DF WHEELER, JC AF SWARTZ, DA CLOCCHIATTI, A BENJAMIN, R LESTER, DF WHEELER, JC TI SUPERNOVA-1993J AS A SPECTROSCOPIC LINK BETWEEN TYPE-II AND TYPE-IB SUPERNOVAE SO NATURE LA English DT Article ID STANDARD STARS; HELIUM; SPECTROPHOTOMETRY; PHASE AB SUPERNOVA 1993J in the nearby galaxy M81 is one of the closest-and hence brightest-supernovae to be witnessed this century. The early spectrum of SN1993J showed1-3 the characteristic hydrogen signature of type II supernovae, but its subsequent evolution is atypical for this class of supernova. Here we present optical and infrared spectra of SN1993J up to 43 days after outburst, which reveal the onset of the helium absorption and emission features more commonly associated with hydrogen-free type Ib supernovae. Corresponding model spectra show that the progenitor star must have possessed an unusually thin (for type II supernovae) hydrogen-rich envelope overlying a helium-rich mantle. Moreover, the supernova ejecta must have remained compositionally stratified, with little transport of the hydrogen-rich material down into the underlying helium layer, or mixing of heavier elements (such as radioactive Ni-56) outwards. SN1993J therefore represents a transition object between hydrogen-dominated type II supernovae, and hydrogen-free, helium-dominated type Ib supernovae. C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RP SWARTZ, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 24 TC 58 Z9 58 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD SEP 16 PY 1993 VL 365 IS 6443 BP 232 EP 234 DI 10.1038/365232a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LX471 UT WOS:A1993LX47100046 ER PT J AU MCPETERS, RD AF MCPETERS, RD TI THE ATMOSPHERIC SO(2) BUDGET FOR PINATUBO DERIVED FROM NOAA-11 SBUV/2 SPECTRAL DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SO2 COLUMN MEASUREMENTS; MAUNA-LOA; CLOUDS; PLUME; OZONE; JUNE AB Spectral scan data from the NOAA-11 SBUV/2 instrument were used to derive SO2 for three days following the eruption of Mt. Pinatubo - June 19, July 1, and July 17, 1991. Band structure between 300 and 310 nm observed in the backscattered albedo uniquely identifies the presence of SO2. Band ratios are used to infer SO2 amounts to better accuracy (approximately 10% to 20%) and sensitivity (about 0.5 milli-atm-cm of SO2) than the TOMS retrieval, but with relatively poor spatial coverage because the measurement is nadir only. Only 7 scans showed detectable SO2 on June 19 when the cloud was still very localized. On July 1 there were 29 scans between 35-degrees-N and 12-degrees-S with SO2, with the highest concentration detected over the Atlantic, and on July 17 SO2 was detected in 30 scans around the world, but in decreased concentration. Estimates of the total SO2 budget made after the cloud had spread sufficiently for the sparse SBUV/2 sampling to be adequate indicated that there were 8.4 million metric tons (MMT) of SO2 in the stratosphere on July 1, 1991, and 4.1 MMT remaining on July 17. This corresponds to an e-folding time of about 24 days for the conversion of SO2 to aerosol, and is consistent with an initial injection into the stratosphere of 12-15 MMT of SO2. RP MCPETERS, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 916,GREENBELT,MD 20771, USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 12 TC 44 Z9 44 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1993 VL 20 IS 18 BP 1971 EP 1974 DI 10.1029/93GL02360 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LX651 UT WOS:A1993LX65100021 ER PT J AU CUMMINGS, JR CUMMINGS, AC MEWALDT, RA SELESNICK, RS STONE, EC VONROSENVINGE, TT AF CUMMINGS, JR CUMMINGS, AC MEWALDT, RA SELESNICK, RS STONE, EC VONROSENVINGE, TT TI NEW EVIDENCE FOR GEOMAGNETICALLY TRAPPED ANOMALOUS COSMIC-RAYS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID COMPONENT; OXYGEN AB We report new observations of greater-than-or-equal-to 15 MeV/nuc trapped heavy ions with Z greater-than-or-equal-to 2, made on the polar-orbiting SAMPEX spacecraft in late 1992 and early 1993. A trapped population that includes He, N, O, and Ne is found to be located at L almost-equal-to 2. We conclude that the observed N, O, and Ne ions are ''anomalous'' cosmic rays, trapped by the mechanism proposed by Blake and Friesen. While it is not expected that this mechanism would also trap anomalous He, the characteristics of the trapped He population are generally consistent with those of N, O, and Ne. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CUMMINGS, JR (reprint author), CALTECH,220-47,PASADENA,CA 91125, USA. NR 20 TC 43 Z9 43 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1993 VL 20 IS 18 BP 2003 EP 2006 DI 10.1029/93GL01961 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LX651 UT WOS:A1993LX65100029 ER PT J AU ANDRAS, MT HEPP, AF DURAJ, SA CLARK, EB SCHEIMAN, DA HEHEMANN, DG FANWICK, PE AF ANDRAS, MT HEPP, AF DURAJ, SA CLARK, EB SCHEIMAN, DA HEHEMANN, DG FANWICK, PE TI SYNTHESIS, CHARACTERIZATION, AND DECOMPOSITION OF THE 1ST MONONUCLEAR 8TH-COORDINATE INDIUM(III) BENZOATE, IN (ETA-2-O2CC6H5)3(4-MEPY)2 SO INORGANIC CHEMISTRY LA English DT Note C1 NASA,LEWIS RES CTR,PHOTOVOLTA BRANCH,CLEVELAND,OH 44135. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. SVERDRUP TECHNOL INC,BROOKPARK,OH 44142. NR 16 TC 13 Z9 13 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0020-1669 J9 INORG CHEM JI Inorg. Chem. PD SEP 15 PY 1993 VL 32 IS 19 BP 4150 EP 4152 DI 10.1021/ic00071a030 PG 3 WC Chemistry, Inorganic & Nuclear SC Chemistry GA LY531 UT WOS:A1993LY53100030 ER PT J AU MENA, RA SCHACHAM, SE YOUNG, PG HAUGLAND, EJ ALTEROVITZ, SA AF MENA, RA SCHACHAM, SE YOUNG, PG HAUGLAND, EJ ALTEROVITZ, SA TI TRANSPORT-PROPERTIES OF EPITAXIAL LIFT-OFF FILMS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID GAAS; HETEROJUNCTIONS; SYSTEMS AB Transport properties of epitaxially lifted-off (ELO) films were characterized using conductivity, Hall, and Shubnikov-de Haas measurements. A 10%-15% increase in the two-dimensional electron gas concentration was observed in these films as compared with adjacent conventional samples. We believe this result to be caused by a backgating effect produced by a charge buildup at the interface of the ELO film and the quartz substrate. This increase results in a significant decrease in the quantum lifetime in the ELO samples, by 17%-30%, but without a degradation in carrier mobility. Under persistent photoconductivity, only one subband was populated in the conventional structure, while in the ELO films the population of the second subband was clearly visible. However, the increase of the second subband concentration with increasing excitation is substantially smaller than anticipated due to screening of the backgating effect. C1 TECHNION ISRAEL INST TECHNOL,IL-32000 HAIFA,ISRAEL. UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. RP MENA, RA (reprint author), NASA,LEWIS RES CTR,SOLID STATE TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 16 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 1993 VL 74 IS 6 BP 3970 EP 3976 DI 10.1063/1.354466 PG 7 WC Physics, Applied SC Physics GA LY328 UT WOS:A1993LY32800051 ER PT J AU WATSON, DM GUPTILL, MT HUFFMAN, JE KRABACH, TN RAINES, SN SATYAPAL, S AF WATSON, DM GUPTILL, MT HUFFMAN, JE KRABACH, TN RAINES, SN SATYAPAL, S TI GERMANIUM BLOCKED-IMPURITY-BAND DETECTOR ARRAYS - UNPASSIVATED DEVICES WITH BULK SUBSTRATES SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ASTRONOMY AB We have fabricated and characterized six-element monolithic arrays of Ge:Ga blocked-impurity-band detectors, with threshold wavelength 220 mum, peak quantum efficiency 14%, detective quantum efficiency 9%, dark current 300 e- s-1, and response uniformity better than 4%. The devices are described very well by the standard model of blocked-impurity-band detectors, and appear to satisfy many of the requirements of low-background astronomical instruments. C1 ROCKWELL INT SCI CTR,ANAHEIM,CA 92803. JET PROP LAB,PASADENA,CA 91109. RP WATSON, DM (reprint author), UNIV ROCHESTER,DEPT PHYS & ASTRON,ROCHESTER,NY 14627, USA. NR 17 TC 45 Z9 46 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 1993 VL 74 IS 6 BP 4199 EP 4206 DI 10.1063/1.354424 PG 8 WC Physics, Applied SC Physics GA LY328 UT WOS:A1993LY32800086 ER PT J AU GREEN, S AF GREEN, S TI RAMAN LINEWIDTHS AND ROTATIONALLY INELASTIC-COLLISION RATES IN NITROGEN (VOL 98, PG 257, 1993) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Correction, Addition RP GREEN, S (reprint author), NASA,GODDARD SPACE FIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 1 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 15 PY 1993 VL 99 IS 6 BP 4875 EP 4875 DI 10.1063/1.466237 PG 1 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA LX143 UT WOS:A1993LX14300065 ER PT J AU HAKKINEN, S AF HAKKINEN, S TI AN ARCTIC SOURCE FOR THE GREAT SALINITY ANOMALY - A SIMULATION OF THE ARCTIC ICE-OCEAN SYSTEM FOR 1955-1975 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID NORTHERN NORTH-ATLANTIC; SEA-ICE; MODEL; CIRCULATION; VARIABILITY; CLIMATE; GREENLAND; COVER; CYCLE; BASIN AB A fully prognostic Arctic ice-ocean model is used to study the interannual variability of the sea ice during the period 1955-1975 and to explain the large variability of the ice extent in the Greenland and Iceland seas during the late 1960's. In particular, the model is used to test the conjecture of Aagaard and Carmack (1989) that the Great Salinity Anomaly (GSA) was a consequence of the anomalously large ice export in 1968. The objective here is to explore the high-latitude ice-ocean circulation changes due to wind field changes. In the simulations the ice extent in the Greenland Sea increased during the 1960's, reaching a maximum in 1968, as observed, and maxima in ice extent were always preceded by large pulses of ice export through the Fram Strait. The ice export event of 1968 was the largest in the simulation, being about twice as large as the average and corresponding to 1600 km3 of excess fresh water. The simulated upper water column in the Greenland Sea has a salinity minimum in the fall of 1968, followed by very low winter salinities. The simulations suggest that, besides the above average ice export to the Greenland Sea, there was also fresh water export to support the larger than average ice cover. Three low-salinity anomalies, which are created by the variability in ice production/melt, exited through the Fram Strait in 1963-1965, 1966, and 1967-1969, the later two events being associated with a net freshwater export of about 900 km3. The total simulated freshwater input of 2500 km3 to the Greenland Sea compares well with the estimated total freshwater excess of the GSA of about 2200 km3 as it passed through the Labrador Sea (Dickson et al., 1988). Considering the uncertainties in the model, it is possible that the ice export could account for even larger portion of the freshwater excess. However, the main conclusion is that these model results show the origin of the GSA to be in the Arctic, as suggested by Aagaard and Carmack (1989) and support the view that the Arctic may play an active role in climate change. RP HAKKINEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER SCI LAB,CODE 971,GREENBELT,MD 20771, USA. RI Hakkinen, Sirpa/E-1461-2012 NR 34 TC 143 Z9 145 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1993 VL 98 IS C9 BP 16397 EP 16410 DI 10.1029/93JC01504 PG 14 WC Oceanography SC Oceanography GA LX764 UT WOS:A1993LX76400009 ER PT J AU VACHON, PW OLSEN, RB KROGSTAD, HE LIU, AK AF VACHON, PW OLSEN, RB KROGSTAD, HE LIU, AK TI AIRBORNE SYNTHETIC-APERTURE RADAR OBSERVATIONS AND SIMULATIONS FOR WAVES IN ICE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEAN SURFACE-WAVES; SAR IMAGERY; SPECTRA; PROPAGATION; EVOLUTION; ZONE AB The Canada Centre for Remote Sensing CV-580 aircraft collected C-band synthetic aperture radar (SAR) data over the marginal ice zone off the east coast of Newfoundland during the Labrador Ice Margin Experiment (LIMEX) in March 1989. One component of the LIMEX'89 program was the study of ocean waves penetrating the marginal ice zone. In this paper, we consider nearly coincidental observations of waves in ice by airborne SAR and wave-induced ice motion measurements. We explain the wave patterns observed in the SAR imagery, and the corresponding SAR image spectra, in terms of SAR wave imaging models. These include the well-known tilt cross-section modulation, linear, quasi-linear, and nonlinear velocity bunching forward mapping models (FMMs), and the assertion that the concept of coherence time limitation applies differently to the cases of waves in ice and open water. We modify the concept of the scene coherence time to include two parts: first, a decorrelation time deduced from the inherent azimuth cutoff in the nonlinear velocity bunching FMM; and second, the intrinsic scene coherence time which is a measure of the time scale over which an open water Bragg scattering patch retains its phase structure. Either of these coherence time scales could dominate the SAR image formation process, depending upon the environmental conditions (the wave spectrum and the wind speed, for example). These two coherence time scales are independently estimated based upon a quasi-linear velocity bunching FMM applied to some of the LIMEX'89 observations. Observed SAR image spectra and forward mapped ice motion package spectra are favorably compared. C1 SATLANTIC INC,HALIFAX B3K 5X8,NS,CANADA. NORWEGIAN INST TECHNOL,FDN SCI & IND RES,TRONDHEIM,NORWAY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP VACHON, PW (reprint author), CANADA CTR REMOTE SENSING,588 BOOTH ST,OTTAWA K1A 0Y7,ON,CANADA. NR 41 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1993 VL 98 IS C9 BP 16411 EP 16425 DI 10.1029/93JC00914 PG 15 WC Oceanography SC Oceanography GA LX764 UT WOS:A1993LX76400010 ER PT J AU KIM, CM CONLISK, AT AF KIM, CM CONLISK, AT TI THE FLOW AND ACOUSTIC FIELD DUE TO AN INCLINED PLATE WITH A DOWNSTREAM SPLITTER SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID BLUFF-BODY; WAKE; SOUND; NOISE; CYLINDER; TANDEM; MOTION; DUCT C1 OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210. RP KIM, CM (reprint author), NASA,LEWIS RES CTR,PROPELLER & ACOUST TECHNOL BRANCH,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 35 TC 0 Z9 0 U1 1 U2 2 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD SEP 15 PY 1993 VL 166 IS 2 BP 209 EP 235 DI 10.1006/jsvi.1993.1293 PG 27 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA LZ914 UT WOS:A1993LZ91400002 ER PT J AU ANDERSON, KR GROZA, JR DRESHFIELD, RL ELLIS, D AF ANDERSON, KR GROZA, JR DRESHFIELD, RL ELLIS, D TI MICROSTRUCTURAL EVOLUTION AND THERMAL-STABILITY OF PRECIPITATION-STRENGTHENED CU-8CR-4NB ALLOY SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article AB The microstructural changes that occur during age hardening of a precipitation-strengthened copper alloy with 8 at.% Cr and 4 at.% Nb (Cu-8Cr-4Nb) alloy were studied by TEM technique and correlated to the corresponding mechanical properties at room and elevated temperatures. The thermal stability of Cu-8Cr-4Nb alloy was attributed to the fine distribution of secondary precipitates and their slow-coarsening rate upon aging. These secondary precipitates provide strengthening by the Orowan mechanism and restrict grain growth upon aging. The experimental values of mechanical properties are compared to the results anticipated from Orowan and Hall-Petch strengthening models to account for the main strengthening mechanisms of the present alloy. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP ANDERSON, KR (reprint author), UNIV CALIF DAVIS,DEPT MECH AERONAUT & MAT ENGN,DAVIS,CA 95616, USA. NR 14 TC 21 Z9 21 U1 1 U2 4 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD SEP 15 PY 1993 VL 169 IS 1-2 BP 167 EP 175 DI 10.1016/0921-5093(93)90611-H PG 9 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA LZ088 UT WOS:A1993LZ08800020 ER PT J AU MURPHY, DW BROWNE, IWA PERLEY, RA AF MURPHY, DW BROWNE, IWA PERLEY, RA TI VLA OBSERVATIONS OF A COMPLETE SAMPLE OF CORE-DOMINATED RADIO-SOURCES SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE METHODS DATA ANALYSIS; BL LACERTAE OBJECTS GENERAL; QUASARS GENERAL; RADIO CONTINUUM GALAXIES ID QUASARS; EMISSION AB Maps with high dynamic range are presented of a well-defined sample of powerful core-dominated radio sources, all of which have 5-GHz core flux densities > 1 Jy. The maps were made at a frequency of 1.64 GHz from combined VLA A and B configuration data. A novel technique for producing high dynamic range maps of variable sources from data taken at different epochs is described. It is found that, on average, BL Lac objects are not more core-dominated than the quasars in the sample. This provides no support for the view that BL Lacs are those quasars seen at such small angles to the line of sight that their relativistically beamed core emission swamps that from other components. The results are consistent with most BL Lac objects being the beamed cores of low-luminosity (FRI) radio galaxies. Nevertheless, a substantial fraction of BL Lac objects, especially those with redshifts > 0.5, have extended radio emission whose luminosity is equivalent to that of high-luminosity (FRII) radio galaxies. The existence of these objects has serious implications for 'unified schemes'. Amongst the broad-line objects we find no evidence that those classified as highly polarized or optically violently variable are any more core-dominated than the rest. C1 UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. RP MURPHY, DW (reprint author), JET PROP LAB,MS 238-600,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 199 Z9 203 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 15 PY 1993 VL 264 IS 2 BP 298 EP 318 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LX326 UT WOS:A1993LX32600005 ER PT J AU KARIMI, M VIDALI, G DALINS, I AF KARIMI, M VIDALI, G DALINS, I TI ENERGETICS OF THE FORMATION AND MIGRATION OF DEFECTS IN PB(110) SO PHYSICAL REVIEW B LA English DT Article ID EMBEDDED-ATOM-METHOD; MULTICOMPONENT ORDER PARAMETER; SURFACE MISCIBILITY GAPS; SELF-DIFFUSION; FCC METALS; TRANSITION-METALS; EXCHANGE MECHANISM; SINGLE ADATOMS; HCP METALS; MODEL AB As part of our investigations on the disordering of metal surfaces, we report the results of our calculations of the energetics of formation and migration of defects in Pb(110) using molecular-dynamics and molecular-statics simulations. We used the embedded-atom method to describe the interatomic interactions. Defect formation and migration energies have been calculated at the surface as well as in the near-surface region. Vacancy, divacancy, and interstitial formation and migration energies converge to bulk values already at a few layers below the surface. Our results are compared with recent simulations of Cu and Ni and with experimental data. We also calculated the surface Debye temperature and surface energy. We find that the surface Debye temperature, surface single-vacancy formation energy, and surface divacancy formation energy are all lower than their bulk values. Our result for the surface energy is lower than the experimental values. C1 SYRACUSE UNIV,DEPT PHYS,SYRACUSE,NY 13244. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP KARIMI, M (reprint author), INDIANA UNIV PENN,DEPT PHYS,INDIANA,PA 15705, USA. NR 59 TC 12 Z9 12 U1 3 U2 5 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD SEP 15 PY 1993 VL 48 IS 12 BP 8986 EP 8992 DI 10.1103/PhysRevB.48.8986 PG 7 WC Physics, Condensed Matter SC Physics GA LY959 UT WOS:A1993LY95900054 ER PT J AU JU, NJ BULGAC, A KELLER, JW AF JU, NJ BULGAC, A KELLER, JW TI EXCITATION OF COLLECTIVE PLASMON STATES IN FULLERENES SO PHYSICAL REVIEW B LA English DT Article ID ENERGY-LOSS SPECTROSCOPY; C-60; CLUSTERS; GRAPHITE; C-70; C60 AB We present theoretical and experimental electron-energy-loss spectroscopy results concerning the excitation of collective plasmon states in isolated fullerenes (gas targets). The large number of active electrons in a carbon cluster and the strong Coulomb interaction among them lead to a rich spectrum of collective states. States with total angular momentum up to L = 8HBAR have a strong collective character. The equivalents of both pi and sigma plasmons in graphite are predicted for a whole range of carbon clusters C20, C60, C70, and C100. The theoretical results compare very well with experimental photoexcitation results in C60 and C70 and EELS data on gas targets C60 and C70. C1 MICHIGAN STATE UNIV,NATL SUPERCONDUCTING CYCLOTRON LAB,E LANSING,MI 48824. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP JU, NJ (reprint author), MICHIGAN STATE UNIV,DEPT PHYS & ASTRON,E LANSING,MI 48824, USA. RI Keller, John/I-5097-2013; OI Bulgac, Aurel/0000-0003-0556-4107 NR 26 TC 32 Z9 32 U1 1 U2 6 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD SEP 15 PY 1993 VL 48 IS 12 BP 9071 EP 9079 DI 10.1103/PhysRevB.48.9071 PG 9 WC Physics, Condensed Matter SC Physics GA LY959 UT WOS:A1993LY95900064 ER PT J AU STEBBINS, A VEERARAGHAVAN, S AF STEBBINS, A VEERARAGHAVAN, S TI MICROWAVE BACKGROUND-RADIATION ANISOTROPY FROM SCALAR FIELD GRADIENTS SO PHYSICAL REVIEW D LA English DT Article ID COLD DARK MATTER; COSMIC STRINGS; TEXTURE; PERTURBATIONS; COSMOGONY; COSMOLOGY; PHYSICS; MODELS AB Analytic calculations of the cosmological density fluctuations and microwave background radiation anisotropies induced by gradients in a topologically trivial scalar field are presented. This anlaytic solution should provide a good test for numerical simulations of microwave anisotropy from scalar fields. To the extent that these results generalize to other scalar field models and configurations, they imply that (1) MBR measurements limit large-scale primordial variations greater than about 5 x 10(16) GeV within our horizon, (2) the total scalar field variation is a fair predictor of the magnitude of the MBR anisotropy, but is only accurate to within a factor of about three, (3) scalar fields as well as other models of seeded perturbations produce a few times more anisotropy DELTAT/T for a given density fluctuation deltarho/rho (on the same scale) than do primordial adiabatic perturbations, (4) models of scalar field seeds which produce a scale-invariant spectrum of perturbations seem to require galaxies to be more clustered than the mass on small scales, and (5) scalar fields do not ''tilt'' the Universe. C1 UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,AMHERST,MA 01003. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP STEBBINS, A (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMILAB MS209,BOX 500,BATAVIA,IL 60510, USA. NR 27 TC 6 Z9 6 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1993 VL 48 IS 6 BP 2421 EP 2430 DI 10.1103/PhysRevD.48.2421 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LY666 UT WOS:A1993LY66600008 ER PT J AU COPELAND, EJ KOLB, EW LIDDLE, AR LIDSEY, JE AF COPELAND, EJ KOLB, EW LIDDLE, AR LIDSEY, JE TI RECONSTRUCTING THE INFLATION POTENTIAL - IN PRINCIPLE AND IN PRACTICE SO PHYSICAL REVIEW D LA English DT Article ID MICROWAVE BACKGROUND-RADIATION; REDSHIFT-DISTANCE SAMPLES; LARGE-SCALE STRUCTURE; GRAVITATIONAL-WAVES; EXTENDED INFLATION; DENSITY FIELDS; IRAS GALAXIES; ANISOTROPY; COBE; PERTURBATIONS AB Generalizing the original work by Hodges and Blumenthal, we outline a formalism which allows one, in principle, to reconstruct the potential of the inflaton field from knowledge of the tensor gravitational wave spectrum or the scalar density fluctuation spectrum, with special emphasis on the importance of the tensor spectrum. We provide some illustrative examples of such reconstruction. We then discuss in some detail the question of whether one can use real observations to carry out this procedure. We conclude that, in practice, a full reconstruction of the functional form of the potential will not be possible within the foreseeable future. However, with a knowledge of the dark matter components, it should soon be possible to combine intermediate-scale data with measurements of large-scale cosmic microwave background anisotropies to yield useful information regarding the potential. C1 NASA, FERMILAB ASTROPHYS CTR, FERMI NATL ACCELERATOR LAB, BATAVIA, IL 60510 USA. UNIV CHICAGO, ENRICO FERMI INST, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. UNIV SUSSEX, SCH MATH & PHYS SCI, CTR ASTRON, BRIGHTON BN1 9QH, E SUSSEX, ENGLAND. QUEEN MARY & WESTFIELD COLL, SCH MATH SCI, ASTRON UNIT, LONDON E1 4NS, ENGLAND. RP UNIV SUSSEX, SCH MATH & PHYS SCI, BRIGHTON BN1 9QH, E SUSSEX, ENGLAND. NR 73 TC 143 Z9 143 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1993 VL 48 IS 6 BP 2529 EP 2547 DI 10.1103/PhysRevD.48.2529 PG 19 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LY666 UT WOS:A1993LY66600018 ER PT J AU SHI, X SCHRAMM, DN FIELDS, BD AF SHI, X SCHRAMM, DN FIELDS, BD TI CONSTRAINTS ON NEUTRINO OSCILLATIONS FROM BIG-BANG NUCLEOSYNTHESIS SO PHYSICAL REVIEW D LA English DT Article ID EARLY UNIVERSE; PRIMORDIAL NUCLEOSYNTHESIS; SOLAR; MATTER; MASS; COSMOLOGY; MODEL; SCALE AB We discuss in detail the effect of neutrino oscillations in big bang nucleosynthesis between active and sterile neutrinos as well as between active and active neutrinos. We calculate the constraints on mixing between active and sterile neutrinos from the present observation of the primordial helium abundance and discuss the potential implications on various astrophysical and cosmological problems of such oscillations. In particular, we show that large-angle sterile neutrino mixing seems to be excluded as a MSW solution to the solar neutrino situation or a solution to the atmospheric neutrino mixing hinted at in some underground experiments. We show bow, with this constraint, the next generation of solar neutrino experiments should be able to determine the resolution of the solar neutrino problem. It is also shown how sterile neutrinos remain a viable dark matter candidate. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP SHI, X (reprint author), UNIV CHICAGO,CHICAGO,IL 60637, USA. OI Fields, Brian/0000-0002-4188-7141 NR 44 TC 131 Z9 131 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1993 VL 48 IS 6 BP 2563 EP 2572 DI 10.1103/PhysRevD.48.2563 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LY666 UT WOS:A1993LY66600020 ER PT J AU CALDWELL, RR GATES, E AF CALDWELL, RR GATES, E TI CONSTRAINTS ON COSMIC STRINGS DUE TO BLACK-HOLES FORMED FROM COLLAPSED COSMIC-STRING LOOPS SO PHYSICAL REVIEW D LA English DT Article ID SMALL-SCALE STRUCTURE; GRAVITATIONAL-RADIATION; EVOLUTION; NETWORK; PARTICLES; RELICS; RAYS AB The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict f, the fraction of cosmic string loops which collapse to form black holes, and mu, the cosmic string mass per unit length. Using a realistic model of cosmic strings, we find that the energy density in 100 MeV photons radiated by the black holes serves as the strongest restriction on the parameters, such that f less-than-or-equal-to 10(-17) for Gmu = 10(-6). We also find that inert black hole remnants left by black holes formed from collapsed cosmic string loops cannot serve as the dark matter. If earlier, crude estimates that f approximately 10(-12) are reliable, our results severely restrict mu, and therefore limit the viability of the cosmic string large-scale structure C1 UNIV CHICAGO, CHICAGO, IL 60637 USA. RP NASA, FERMILAB ASTROPHYS CTR, FERMI NATL ACCELERATOR LAB, POB 500, BATAVIA, IL 60510 USA. OI Caldwell, Robert/0000-0001-7490-7463 NR 31 TC 7 Z9 7 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1993 VL 48 IS 6 BP 2581 EP 2586 DI 10.1103/PhysRevD.48.2581 PG 6 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA LY666 UT WOS:A1993LY66600022 ER PT J AU OHSAKA, K TRINH, EH AF OHSAKA, K TRINH, EH TI AN APPROXIMATE FORMULA FOR RECALESCENCE IN BINARY EUTECTIC ALLOYS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID CONTAINERLESS RP OHSAKA, K (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD SEP 15 PY 1993 VL 29 IS 6 BP 845 EP 850 DI 10.1016/0956-716X(93)90239-O PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA LP598 UT WOS:A1993LP59800025 ER PT J AU SMITH, GD YOON, DY JAFFE, RL AF SMITH, GD YOON, DY JAFFE, RL TI A 3RD-ORDER ROTATIONAL ISOMERIC STATE MODEL FOR POLY(OXYETHYLENE) BASED UPON AB-INITIO ELECTRONIC-STRUCTURE ANALYSES OF MODEL MOLECULES SO MACROMOLECULES LA English DT Article ID AQUEOUS SALT-SOLUTIONS; CONFORMATIONAL ENERGIES; POLY(ETHYLENE OXIDE); GAS-PHASE; 1,2-DIMETHOXYETHANE; VISCOSITY AB A new three-state rotational isomeric state (RIS) model has been derived for poly(oxyethylene) (POE), based upon ab initio electronic structure analyses of the model molecules 1,2-dimethoxyethane (DME) and diethyl ether (DEE). It is demonstrated that the low energy of the tg+/-g-/+ conformation of DME, resulting from strong O ... H attractions, as indicated by the ab initio studies, necessitates the inclusion of third-order interactions (depending on three consecutive torsional angles) in the RIS model. This is realized by adopting 9 x 9 statistical weight matrices. This third-order RIS model, with all the parameters derived from the conformational geometries and energies of DME and DEE, predicts the chain dimensions, the dipole moments, and their temperature coefficients for POE in good agreement with experiments. It was also found from analysis of the energies of the O-C-C-O, O-C-C-CH2-(O), and O-C-C-CH2-(CH2) gauche conformations (relative to trans) in DME, 1,3-dimethoxypropane, and methyl butyl ether, respectively, that the strength of the oxygen gauche effect for the C-C bond, i.e., the stabilization of the O-C-C-X gauche conformation relative to the trans conformation, correlates well with the degree of Coulombic repulsion or attraction between the oxygen and the ''X'' moiety. This explains the slightly higher energy (0.1 kcal/mol) found for the O-C-C-O gauche conformation (relative to trans) in DME from ab initio calculations while similar calculations for 1,3-dimethoxypropane and methyl butyl ether indicate that the O-C-C-CH2 gauche conformations are significantly lower in energy than their respective trans conformations. C1 IBM CORP,ALMADEN RES CTR,650 HARRY RD,SAN JOSE,CA 95120. ELORET INST,SUNNYVALE,CA 94087. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 23 TC 60 Z9 60 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD SEP 13 PY 1993 VL 26 IS 19 BP 5213 EP 5218 DI 10.1021/ma00071a037 PG 6 WC Polymer Science SC Polymer Science GA LX932 UT WOS:A1993LX93200037 ER PT J AU JUDAY, RD AF JUDAY, RD TI OPTIMAL REALIZABLE FILTERS AND THE MINIMUM EUCLIDEAN DISTANCE PRINCIPLE SO APPLIED OPTICS LA English DT Article ID SPATIAL LIGHT-MODULATOR; TERNARY MATCHED-FILTERS; PHASE-ONLY FILTERS; TO-NOISE RATIOS; PATTERN-RECOGNITION; SIGNAL; DISCRIMINATION AB Minimizing a Euclidean distance in the complex plane optimizes a wide class of correlation metrics for filters implemented on realistic devices. The algorithm searches over no more than two real scalars (gain and phase). It unifies a variety of previous solutions for special cases (e.g., a maximum signal-to-noise ratio with colored noise and a real filter and a maximum correlation intensity with no noise and a coupled filter). It extends optimal partial information filter theory to arbitrary spatial light modulators (fully complex, coupled, discrete, finite contrast ratio, and so forth), additive input noise (white or colored), spatially nonuniform filter modulators, and additive correlation detection noise (including signal-dependent noise). An appendix summarizes the algorithm as it is implemented in available computer code. RP JUDAY, RD (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. NR 26 TC 105 Z9 111 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 10 PY 1993 VL 32 IS 26 BP 5100 EP 5111 PG 12 WC Optics SC Optics GA LW372 UT WOS:A1993LW37200021 PM 20856317 ER PT J AU TEREBEY, S CHANDLER, CJ ANDRE, P AF TEREBEY, S CHANDLER, CJ ANDRE, P TI THE CONTRIBUTION OF DISKS AND ENVELOPES TO THE MILLIMETER CONTINUUM EMISSION FROM VERY YOUNG LOW-MASS STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; CIRCUMSTELLAR MATTER; INFRARED, STARS; RADIO CONTINUUM, STARS; STARS, LOW-MASS, BROWN DWARFS; STARS, PRE-MAIN-SEQUENCE ID FAR-INFRARED OBSERVATIONS; DENSE CORES; DARK CLOUDS; CIRCUMSTELLAR DISKS; MOLECULAR OUTFLOWS; STELLAR OBJECTS; IRAS 16293-2422; EXCITING SOURCE; HIGH-RESOLUTION; BINARY-SYSTEM AB We investigate the question of disk formation during the protostar phase. We build on the results of Keene & Masson (1990) whose analysis of L1551 IRS 5 showed the millimeter continuum emission comes from both an unresolved circumstellar component, i.e., disk, and a more extended envelope/dense core. We model the dust continuum emission from the dense cloud core using the cloud-collapse models of Terebey, Shu, & Cassen (1984) and show that dust emission from the dense core is important when measured with large single-dish telescopes at 1.3 mm, but nearly negligible with interferometers at 2.7 mm. Combining new 2.7 mm Owens Valley Interferometer data of IRAS-Dense cores with data from the literature, we conclude that massive disks are also seen toward a number of other sources including L1448 IRS 3 (IRAS 03225+3034), whose disk mass is estimated to be 0.5 M., (assuming T(D) = 40 K, beta = 1.5, and optically thin emission). However 1.3 mm data from the IRAM 30 m telescope for a larger sample shows that massive disks are relatively rare, occurring around perhaps 5% of young embedded stars. This implies that either massive disks occur briefly during the embedded phase or that relatively few young stars form massive disks. The median 1.3 mm flux density of IRAS-Dense cores in our sample is nearly the same as T Tauri stars in the sample of Beckwith et al. (1990). We conclude that the typical disk mass is not significantly higher during the embedded phase than during the later T Tauri phase. C1 CALTECH,OWENS VALEY RADIO OBSERV 10524,PASADENA,CA 91125. CTR ETUD SACLAY,SERV ASTROPHYS,F-91191 GIF SUR YVETTE,FRANCE. RP TEREBEY, S (reprint author), JET PROP LAB,CTR INFRARED PROC & ANAL,IPAC 100-22,PASADENA,CA 91109, USA. NR 56 TC 101 Z9 101 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP 759 EP 772 DI 10.1086/173121 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU946 UT WOS:A1993LU94600035 ER PT J AU ROBINSON, RD CARPENTER, KG WOODGATE, BE MARAN, SP AF ROBINSON, RD CARPENTER, KG WOODGATE, BE MARAN, SP TI A SEARCH FOR PROTON-BEAMS DURING FLARES ON AU MICROSCOPII SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACTIVITY; STARS, FLARE; STARS, INDIVIDUAL (AU MICROSCOPII); ULTRAVIOLET, STARS ID SOLAR-FLARES; ALPHA EMISSION; PHASE AB We report the results of a coordinated observing campaign on the active M dwarf star AU Mic. The purpose of the campaign was to search for evidence of proton beams during the impulsive phase of stellar flares and to determine whether the energy contained in these beams represented a significant fraction of the energy budget of the flare. During a total of 3.5 hr of monitoring a small flare was observed simultaneously by the HST, IUE, and the AAT. This event, which had a total optical + UV emission of 1.3 x 10(32) ergs, occurred during the decay phase of a much larger event and showed no evidence for a proton beam with an energy greater than a few times 10(29) ergs s-1. This is comparable to the maximum energy flux released by the flare, though this energy release rate must occur over a time interval much shorter than that of the impulsive phase itself. We conclude that the proton beams may be capable of transporting some energy during the impulsive phase of a flare, but that they are unlikely to be the major contributor, at least for this particular event. More observations are required to establish whether this is a general characteristic of stellar flares. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP ROBINSON, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAMS,CODE 681,GREENBELT,MD 20771, USA. RI Woodgate, Bruce/D-2970-2012; Carpenter, Kenneth/D-4740-2012 NR 14 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP 872 EP 876 DI 10.1086/173129 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU946 UT WOS:A1993LU94600043 ER PT J AU WOLFF, CL AF WOLFF, CL TI EQUIDISTRIBUTION OF ENERGY AND OTHER QUANTITIES IN OSCILLATING-SYSTEMS SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; METHODS, ANALYTICAL; STARS, OSCILLATIONS; SUN, OSCILLATIONS ID R-MODES; SOLAR AB Energy of a high harmonic standing wave tends to be distributed equally over the whole wave even in a stratified medium where the wave's peak amplitude can be much larger near the upper boundary than the lower one. This fact is generalized to the many diverse physical problems which solve second-order differential equations of Sturm-Liouville type. For any such solution y(z) whose sign fluctuates along the z-axis, quantities are found which have the same value between any two neighboring zeros of y. One of the equidistributed quantities for an oscillating fluid sphere is similar to kinetic energy but is identical only in limiting cases. The acoustic midpoint of a cavity can be a unique place where some nonlinear perturbations have extra strength. This may apply to the puzzling solar phenomenon called supergranulation. RP WOLFF, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 914,GREENBELT,MD 20771, USA. NR 14 TC 2 Z9 2 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP 892 EP 897 DI 10.1086/173132 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU946 UT WOS:A1993LU94600046 ER PT J AU LAU, YT NORTHROP, TG FINN, JM AF LAU, YT NORTHROP, TG FINN, JM TI LONG-TERM CONTAINMENT OF ENERGETIC PARTICLES IN CORONAL LOOPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CORONA; SUN, FLARES; SUN, X-RAYS, GAMMA-RAYS ID GAMMA-RAY EMISSION; SOLAR-FLARES; PION DECAY AB Recent observation from the Compton Gamma-Ray Observatory shows that gamma-ray emission after a solar flare can last for as long as 8 hours. There is also evidence that electrons and protons are accelerated only during the impulsive phase of the flare and are subsequently mirror trapped in coronal magnetic loops. This poses the following dilemma: if the magnetic field lines in the loop are simple plane arches, the protons will drift across the cross section of the loop in seconds to minutes, rather than hours. To solve the dilemma, we use guiding center theory to show that long-term containment of energetic protons in a coronal loop is possible if magnetic field lines have enough twist. We also find that in the trapped region of the loop, the twist angle of field lines between the mirror points of a bounce orbit is approximately 2pi. C1 NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,GREENBELT,MD 20771. RP LAU, YT (reprint author), UNIV MARYLAND,PLASMA RES LAB,COLL PK,MD 20742, USA. NR 12 TC 15 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP 908 EP 915 DI 10.1086/173134 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU946 UT WOS:A1993LU94600048 ER PT J AU BENNETT, CL HINSHAW, G BANDAY, A KOGUT, A WRIGHT, EL LOEWENSTEIN, K CHENG, ES AF BENNETT, CL HINSHAW, G BANDAY, A KOGUT, A WRIGHT, EL LOEWENSTEIN, K CHENG, ES TI NONCOSMOLOGICAL SIGNAL CONTRIBUTIONS TO THE COBE1 DMR ANISOTROPY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; DIFFUSE RADIATION; INTERGALACTIC MEDIUM ID DIFFERENTIAL MICROWAVE RADIOMETER; BACKGROUND-RADIATION; EMISSION; GALAXIES AB We examine the COBE Differential Microwave Radiometer (DMR) data for evidence of noncosmological source contributions. The DMR maps are cross-correlated with maps of rich clusters, extragalactic IRAS sources, HEAO 1 A-2 X-ray emission, and 5 GHz radio sources. We limit the rms contributions from these sources on a 7-degrees angular scale to less than 10 muK (95% confidence level) in the DMR maps, although the Large Magellanic Cloud probably contributes approximately 50 muK to a limited region of the sky. Thus, our previous interpretation that the fluctuations in the COBE DMR data are most likely due to cosmic fluctuations at the surface of last scattering remains intact. The Comptonization parameter for hot electrons traced by rich clusters is limited to deltay < 2 x 10(-6) (95% confidence level) averaged over the 7-degrees DMR beam. C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. RP BENNETT, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 20 TC 35 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP L77 EP L80 DI 10.1086/187000 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU947 UT WOS:A1993LU94700008 ER PT J AU GUHATHAKURTA, M FISHER, RR ALTROCK, RC AF GUHATHAKURTA, M FISHER, RR ALTROCK, RC TI LARGE-SCALE CORONAL TEMPERATURE AND DENSITY DISTRIBUTIONS, 1984-1992 SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA ID SOLAR AB In this Letter we characterize the temperature and the density structure of the corona utilizing spectrophotometric observations at different heights but at the same latitude during the descending phase of cycle 21 through the ascending phase of cycle 22. The data include ground-based intensity observations of the green (Fe XIV lambda5303) and red (Fe x lambda6374) coronal forbidden lines, photospheric magnetographs from the National Solar Observatory, Kitt Peak, and synoptic maps of white-light K-coronal polarized brightness, pB, from the High Altitude Observatory. A determination of plasma temperature T can be estimated from the intensity ratio Fe x/Fe xiv (where T is inversely proportional to the ratio), since both emission lines come from ionized states of Fe, and the ratio is only weakly dependent on density. Distributions of the electron temperature from the line ratio and the polarized brightness which yields electron density of the corona during the descending and the ascending phases of solar cycles 21 and 22 are presented. These data refer to structures of the corona which are relatively large scale, having a temporal coherence of at least two or more synoptic rotation periods, such as the streamer belts, the individual helmet streamers, and the larger coronal holes. We observe that there is a large-scale organization of the inferred coronal temperature distribution that is associated with the large-scale structures in the solar magnetic fields; this organization tends to persist through most of the magnetic activity cycle. This distribution differs in spatial and temporal characterization from the traditional picture of sunspot and active region evolution over the range of sunspot cycles, which are manifestations of the small-scale, strong magnetic field regions. For example, during 1987-1990 the active region latitudes drift equatorward, whereas bright coronal features in white light and the inferred temperature structures drift poleward. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NATL SOLAR OBSERV,GEOPHYS DIRECTORATE,PHILLIPS LAB AFSC,SUNSPOT,NM 88349. RP GUHATHAKURTA, M (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80303, USA. NR 14 TC 48 Z9 51 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP L145 EP & DI 10.1086/187017 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU947 UT WOS:A1993LU94700025 ER PT J AU WARREN, JK VALLERGA, JV MAUCHE, CW MUKAI, K SIEGMUND, OHW AF WARREN, JK VALLERGA, JV MAUCHE, CW MUKAI, K SIEGMUND, OHW TI EXTREME-ULTRAVIOLET EXPLORER OBSERVATIONS OF THE MAGNETIC CATACLYSMIC VARIABLE RE 1938-461 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (RE 1938-461); STARS, MAGNETIC FIELDS; X-RAYS, STARS ID AM HERCULIS; RADIO-EMISSION AB The magnetic cataclysmic variable RE 1938-461 was observed by the Extreme Ultraviolet Explorer (EUVE) Deep Survey instrument on 1992 July 8-9 during in-orbit calibration. It was detected in the Lexan/boron (65-190 angstrom) band, with a quiescent count rate of 0.0062 +/- 0.0017 s-1, and was not detected in the aluminum/carbon (160-360 angstrom) band. The Lexan/boron count rate is lower than the corresponding ROSAT wide-field camera Lexan/boron count rate. This is consistent with the fact that the source was in a low state during an optical observation performed just after the EUVE observation, whereas it was in an optical high state during the ROSAT observation. The quiescent count rates are consistent with a virtual cessation of accretion. Two transient events lasting approximately 1 hr occurred during the Lexan/boron pointing, the second at a count rate of 0.050 +/- 0.006 s-1. This appears to be the first detection of an EUV transient during the low state of a magnetic cataclysmic variable. We propose two possible explanations for the transient events. (1) They may have been caused by intermittent accretion of dense filaments of matter, formed by an instability at the second star surface, which impact and heat the white dwarf photosphere, causing it to emit EUV radiation. For an assumed blackbody temperature of 20-50 eV and an interstellar column density of 10(20) cm-2, the luminosity of the second transient is approximately 10(32) (d/300 pc)2 ergs s-1, and the fractional emitting area of the white dwarf is approximately 6 x 10(-5) (d/300 pc)2 for a 0.7 M. white dwarf. (2) Given the high rotation rate of the secondary and the possibility that the secondary is magnetically active, it is possible that these transients are the EUV component of magnetic flares. For an assumed thermal plasma with a temperature of 10(6)-10(8) K and an interstellar column density of 10(20) cm-2, the luminosity of the second transient is approximately 10(33) (d/300 pc)2 ergs s-1 and the emission measure is approximately 10(55)-10(56) (d/300 pc)2 cm-3. We note that a magnetic flare or a coronal mass ejection may be the source of the intermittent accretion enhancements of the first scenario. C1 UNIV CALIF BERKELEY,CTR EUV ASTROPHYS,BERKELEY,CA 94720. LAWRENCE LIVERMORE NATL LAB,EXPTL ASTROPHYS LAB,LIVERMORE,CA 94550. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WARREN, JK (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,EXPTL ASTROPHYS GRP,BERKELEY,CA 94720, USA. NR 21 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1993 VL 414 IS 2 BP L69 EP L72 DI 10.1086/186998 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU947 UT WOS:A1993LU94700006 ER PT J AU TENG, WL WANG, JR DORAISWAMY, PC AF TENG, WL WANG, JR DORAISWAMY, PC TI RELATIONSHIP BETWEEN SATELLITE MICROWAVE RADIOMETRIC DATA, ANTECEDENT PRECIPITATION INDEX, AND REGIONAL SOIL-MOISTURE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID 37 GHZ DATA; POLARIZATION DIFFERENCE; BRIGHTNESS TEMPERATURES; VEGETATION; SMMR AB Satellite microwave brightness temperatures (T(B)'s) have been shown, in previous studies for semi-arid environments, to correlate well with the antecedent precipitation index (API), a soil moisture indicator. The current study, using the Special Sensor Microwave/imager (SSM/I), continued this work for parts of the U.S. Corn and Wheat Belts, which included areas with a more humid climate, a denser natural vegetation cover, and a different mix of agricultural crop types. Four years (1987-1990) of SSM/I data at 19 and 37 GHz, daily precipitation and temperature data from weather stations, and API calculated from the weather data were processed, geo-referenced, and averaged to 3/4-degrees latitude-longitude grid quadrants. Correlation results between T(B) at 19 GHz and API were highly dependent on geographical location. Correlation coefficients (r values) ranged from -0.6 to -0.85 for the semi-arid parts of the study area and from -0-3 to -0.7 for the more humid and more densely vegetated parts. R values were also higher for the very dry and very wet years (-O.5 to -0.85) than for the 'normal' year (-0.3 to -0.65). Similar to previous results, the Microwave Polarization Difference Index (MPDI), based on the 37 GHz data, was found to correspond to variations in vegetation cover. The MPDI was used to develop a linear regression model to estimate API from T(B). Correlation between estimated and calculated APIs was also geographically and time dependent. Comparison of API with some field soil moisture measurements showed a similar trend, which provided some degree of confidence in using API as an indicator of soil moisture. C1 NASA,GODDARD SPACE FLIGHT CTR,MICROWAVE SENSORS & DATA COMMUN BRANCH,GREENBELT,MD 20771. USDA ARS,BELTSVILLE AGR RES CTR,BELTSVILLE,MD 20705. RP TENG, WL (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 24 TC 44 Z9 54 U1 4 U2 14 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD SEP 10 PY 1993 VL 14 IS 13 BP 2483 EP 2500 PG 18 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA MA934 UT WOS:A1993MA93400004 ER PT J AU CAILLAT, T BORSHCHEVSKY, A FLEURIAL, JP AF CAILLAT, T BORSHCHEVSKY, A FLEURIAL, JP TI PHASE-DIAGRAM OF THE IR-SB SYSTEM ON THE ANTIMONY-RICH PART SO JOURNAL OF ALLOYS AND COMPOUNDS LA English DT Article ID BINARY AB The antimony-rich iridium antimony phase diagram was investigated by means of differential thermal analysis, microprobe analysis, metallography and X-ray powder diffraction. The existence of three compounds was confirmed in the range 50-100 at.% Sb: IrSb3 which forms by peritectic reaction at 1141-degrees-C, IrSb2 which also forms peritectically at 1475+/-30-degrees-C and IrSb which melts congruently at 1645+/-25-degrees-C. IrSb3 forms a degenerate eutectic with antimony at 621-degrees-C. The shape of the liquidus line was also investigated. RP CAILLAT, T (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 2 Z9 2 U1 3 U2 12 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0925-8388 J9 J ALLOY COMPD JI J. Alloy. Compd. PD SEP 10 PY 1993 VL 199 IS 1-2 BP 207 EP 210 DI 10.1016/0925-8388(93)90452-S PG 4 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA LV152 UT WOS:A1993LV15200034 ER PT J AU WANG, PKC HADAEGH, FY AF WANG, PKC HADAEGH, FY TI FORCED VIBRATIONS OF PRELOADED ELASTIC BEAMS WITH JOINTS IN THE MICRODYNAMIC REGIME SO JOURNAL OF SOUND AND VIBRATION LA English DT Article C1 JET PROP LAB,PASADENA,CA 91109. RP WANG, PKC (reprint author), UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024, USA. NR 15 TC 2 Z9 5 U1 1 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD SEP 8 PY 1993 VL 166 IS 1 BP 1 EP 19 DI 10.1006/jsvi.1993.1279 PG 19 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA LZ904 UT WOS:A1993LZ90400001 ER PT J AU CLEM, JM GUZIK, TG LIJOWSKI, M WEFEL, JP BEATTY, JJ FICENEC, DJ TOBIAS, S MITCHELL, JW MCKEE, S NUTTER, S TARLE, G TOMASCH, A BOWER, CR HEINZ, RM MUFSON, SL MUSSER, J PITTS, J SPICZAK, GM AHLEN, SP ZHOU, B AF CLEM, JM GUZIK, TG LIJOWSKI, M WEFEL, JP BEATTY, JJ FICENEC, DJ TOBIAS, S MITCHELL, JW MCKEE, S NUTTER, S TARLE, G TOMASCH, A BOWER, CR HEINZ, RM MUFSON, SL MUSSER, J PITTS, J SPICZAK, GM AHLEN, SP ZHOU, B TI BALLOON OBSERVATIONS OF GALACTIC COSMIC-RAY HELIUM BEFORE AND DURING A FORBUSH DECREASE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPECTRA AB The energy spectrum of galactic cosmic ray Helium was measured in two different balloon experiments launched four days apart from Canada: SMILI-I on 1-Sept-1989 and MASS on 5-Sept-1989. A slow Forbush decrease began on 4-Sept-1989 and had not reached its maximum at the time of the MASS flight. Comparison of the balloon measurements shows a fractional decrease of 0.37 to 0.15 in the Helium flux between 200 and 450 MeV/nucleon (1.2-2.0 GV). The rigidity dependence is analyzed in two models and found to be steeper than previous observations. Interplanetary particle data and ground-based Neutron Monitor results are consistent with the balloon observations. Probable sources for this Forbush decrease are discussed. C1 WASHINGTON UNIV,DEPT PHYS,ST LOUIS,MO 63130. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MICHIGAN,DEPT PHYS,ANN ARBOR,MI 48109. INDIANA UNIV,DEPT PHYS,BLOOMINGTON,IN 47405. BOSTON UNIV,DEPT PHYS,BOSTON,MA 02215. RP CLEM, JM (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. RI Beatty, James/D-9310-2011 OI Beatty, James/0000-0003-0481-4952 NR 12 TC 1 Z9 1 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 3 PY 1993 VL 20 IS 17 BP 1743 EP 1746 DI 10.1029/93GL01972 PG 4 WC Geosciences, Multidisciplinary SC Geology GA LW834 UT WOS:A1993LW83400001 ER PT J AU KELLER, LP MCKAY, DS AF KELLER, LP MCKAY, DS TI DISCOVERY OF VAPOR DEPOSITS IN THE LUNAR REGOLITH SO SCIENCE LA English DT Article AB Lunar soils contain micrometer-sized mineral grains surrounded by thin amorphous rims. Similar features have been produced by exposure of pristine grains to a simulated solar wind, leading to the widespread belief that the amorphous rims result from radiation damage. Electron microscopy studies show, however, that the amorphous rims are compositionally distinct from their hosts and consist largely of vapor-deposited material generated by micrometeorite impacts into the lunar regolith. Vapor deposits slow the lunar erosion rate by solar wind sputtering, influence the optical properties of the lunar regolith, and may account for the presence of sodium and potassium in the lunar atmosphere. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058. NR 21 TC 129 Z9 135 U1 1 U2 13 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 3 PY 1993 VL 261 IS 5126 BP 1305 EP 1307 DI 10.1126/science.261.5126.1305 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LV656 UT WOS:A1993LV65600022 PM 17731858 ER PT J AU LEE, TJ DATEO, CE GAZDY, B BOWMAN, JM AF LEE, TJ DATEO, CE GAZDY, B BOWMAN, JM TI ACCURATE QUARTIC FORCE-FIELDS AND VIBRATIONAL FREQUENCIES FOR HCN AND HNC SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID EQUILIBRIUM STRUCTURE; OVERTONE TRANSITIONS; CM-1; CONSTANTS; MOLECULES; SPECTRUM; CATION AB The quartic force fields of HCN and HNC are determined using atomic natural orbital one-particle basis sets of spdf/spd and spdfg/spdf quality in conjunction with the CCSD(T) electron correlation method (singles and doubles coupled-cluster theory plus a perturbational estimate of the effects of connected triple excitations). The HCN force field is in good agreement with a recent experimentally derived force field and also with the force field recently computed by Wong and Bacskay. On the basis of the good agreement obtained for HCN, it is argued that the ab initio quartic force field for HNC is superior to a prior force field derived from experiment. The harmonic frequencies of HNC are predicted to be 3822 +/- 10, 472 +/- 5, and 2051 +/- 10 cm-1 for omega1, omega2, and omega3, respectively; the experimentally derived values are above these values and fall outside the estimated uncertainties. Using the quartic force field, spectroscopic constants are predicted for HNC based on a vibrational second-order perturbation theory analysis. It is also asserted that the gas-phase fundamental nu3 for HNC is slightly lower than the matrix isolation value. The range of validity of the quartic force fields is investigated by comparison of variational vibrational energies computed with the quartic force fields to those obtained from our recently reported global HCN/HNC potential energy surface and also to experimental data. C1 ELORET INST, PALO ALTO, CA 94303 USA. EMORY UNIV, DEPT CHEM, ATLANTA, GA 30322 USA. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 36 TC 35 Z9 35 U1 2 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 2 PY 1993 VL 97 IS 35 BP 8937 EP 8943 DI 10.1021/j100137a018 PG 7 WC Chemistry, Physical SC Chemistry GA LX921 UT WOS:A1993LX92100018 ER PT J AU BAILEY, DH AF BAILEY, DH TI ALGORITHM 719 - MULTIPRECISION TRANSLATION AND EXECUTION OF FORTRAN PROGRAMS SO ACM TRANSACTIONS ON MATHEMATICAL SOFTWARE LA English DT Article DE ALGORITHMS; PERFORMANCE; MULTIPLE-PRECISION COMPUTATION; MULTIPRECISION ARITHMETIC ID ELEMENTARY-FUNCTIONS; CRYPTOSYSTEMS; COMPUTATION; CONSTANTS; PI AB This paper describes two Fortran utilities for multiprecision computation. The first is a package of Fortran subroutines that perform a variety of arithmetic operations and transcendental functions on floating point numbers of arbitrarily high precision. This package is in some cases over 200 times faster than that of certain other packages that have been developed for this purpose. The second utility is a translator program, which facilitates the conversion of ordinary Fortran programs to use this package. By means of source directives (special comments) in the original Fortran program, the user declares the precision level and specifies which variables in each subprogram are to be treated as multiprecision. The translator program reads this source program and outputs a program with the appropriate multiprecision subroutine calls. This translator supports multiprecision integer, real, and complex datatypes. The required array space for multiprecision data types is automatically allocated. In the evaluation of computational expressions, all of the usual conventions for operator precedence and mixed mode operations are upheld. Furthermore, most of the Fortran-77 intrinsics, such as ABS, MOD, NINT, COS, EXP are supported and produce true multiprecision values. RP BAILEY, DH (reprint author), NASA,AMES RES CTR,NAS APPL RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 32 TC 102 Z9 102 U1 0 U2 1 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0098-3500 J9 ACM T MATH SOFTWARE JI ACM Trans. Math. Softw. PD SEP PY 1993 VL 19 IS 3 BP 288 EP 319 DI 10.1145/155743.155767 PG 32 WC Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA MA500 UT WOS:A1993MA50000002 ER PT J AU DUFFY, DG AF DUFFY, DG TI ON THE NUMERICAL INVERSION OF LAPLACE TRANSFORMS - COMPARISON OF 3 NEW METHODS ON CHARACTERISTIC PROBLEMS FROM APPLICATIONS SO ACM TRANSACTIONS ON MATHEMATICAL SOFTWARE LA English DT Article DE ALGORITHMS; MEASUREMENT ID CONVERGENCE; SOFTWARE AB Three frequently used methods for numerically inverting Laplace transforms are tested on complicated transforms taken from the literature. The first method is a straightforward application of the trapezoidal rule to Bromwich's integral. The second method, developed by Weeks [22], integrates Bromwich's integral by using Laguerre polynomials. The third method, devised by Talbot [18], deforms Bromwich's contour so that the integrand of Bromwich's integral is small at the beginning and end of the contour. These methods are also applied to joint Laplace-Fourier transform problems. All three methods give satisfactory results; Talbot's, however, has an accurate method for choosing required parameters. RP DUFFY, DG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 24 TC 57 Z9 57 U1 0 U2 2 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0098-3500 J9 ACM T MATH SOFTWARE JI ACM Trans. Math. Softw. PD SEP PY 1993 VL 19 IS 3 BP 333 EP 359 DI 10.1145/155743.155788 PG 27 WC Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA MA500 UT WOS:A1993MA50000004 ER PT J AU WEBER, WJ GRAY, VW JACKSON, B STEELE, LC AF WEBER, WJ GRAY, VW JACKSON, B STEELE, LC TI A SYSTEMS-APPROACH TO THE COMMERCIALIZATION OF SPACE COMMUNICATIONS TECHNOLOGY - THE NASA JPL MOBILE SATELLITE PROGRAM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB This paper discusses the systems approach taken by NASA and the Jet Propulsion Laboratory in the commercialization of land-mobile satellite services (LMSS) in the United States. As the lead center for NASA's Mobile Satellite Program, JPL was involved in identifying and addressing many of the key barriers to commercialization of mobile satellite communications, including technical, economic, regulatory and institutional risks, or uncertainties. The systems engineering approach described here was used to mitigate these risks. The result was the development and implementation of the JPL Mobile Satellite Experiment Project. This Project included not only technology development, but also studies to support NASA in the definition of the regulatory, market, and investment environments within which LMSS would evolve and eventually operate, as well as initiatives to mitigate their associated commercialization risks. The end result of these government-led endeavors was the acceleration of the introduction of commercial mobile satellite services, both nationally and internationally. RP WEBER, WJ (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD SEP PY 1993 VL 29 IS 9 BP 667 EP 675 DI 10.1016/0094-5765(93)90085-B PG 9 WC Engineering, Aerospace SC Engineering GA LR483 UT WOS:A1993LR48300002 ER PT J AU BOURKE, RD DIAS, WC GOLOMBEK, MP PIVIROTTO, DL STURMS, FM HUBBARD, GS AF BOURKE, RD DIAS, WC GOLOMBEK, MP PIVIROTTO, DL STURMS, FM HUBBARD, GS TI STATUS OF ROBOTIC MISSION STUDIES FOR THE SPACE EXPLORATION INITIATIVE - 1991 SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 42ND CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 07-11, 1991 CL MONTREAL, CANADA SP INT ASTRONAUT FEDERAT AB The paper describes the 1990/1991 robotic mission study efforts for Moon and Mars exploration associated with human missions of the Space Exploration Initiative. RP BOURKE, RD (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD SEP PY 1993 VL 29 IS 9 BP 691 EP 699 DI 10.1016/0094-5765(93)90088-E PG 9 WC Engineering, Aerospace SC Engineering GA LR483 UT WOS:A1993LR48300005 ER PT J AU SCHMIEDER, B DEMOULIN, P HAGYARD, M MACHADO, ME AI, GX ZHANG, HQ FU, QJ LI, ZK LUAN, T KALMAN, B GYORI, L AF SCHMIEDER, B DEMOULIN, P HAGYARD, M MACHADO, ME AI, GX ZHANG, HQ FU, QJ LI, ZK LUAN, T KALMAN, B GYORI, L TI RELATIONSHIP BETWEEN MAGNETIC-FIELD EVOLUTION AND FLARING SITES IN AR-6659 ON JUNE 1991 SO ADVANCES IN SPACE RESEARCH LA English DT Article ID FLARES AB During the international campaign of June 1991, the active region AR 6659 produced 6 very large long duration flares at the same location during its passage across the solar disk. Vector magnetograms were obtained at Marshall (Huntsville) and Huairou Station (Beijing) with a time difference of 10 to 12 hours, thus giving a good survey of the magnetic field evolution with time. The flare of June 6/01:08 UT (X12 plus/4B) was observed in Shahe Station (Beijing) in white light, in Halpha and in radio centimetric wavelengths. The evolution of the flare of June 9/01:43 UT (X10/3B) has been followed in Halpha at the Yunnan Observatory (Kunming). An other one was well observed on June 15 at 08:20 UT in Wroclaw and in Debrecen. Some subflares were observed at Sac Peak on June 4, 5, 7 at Meudon on June 10, 14 and Debrecen on June 12 and 13. In this short communication we concentrate on the relationship between magnetic field shear and flare sites. C1 NASA,MSFC,HUNTSVILLE,AL 35812. UAH,HUNTSVILLE,AL 35812. BEIJING OBSERV,BEIJING 100080,PEOPLES R CHINA. YUNNAN OBSERV,KUNMING,PEOPLES R CHINA. DEBRECEN OBSERV,DEBRECEN,HUNGARY. RP SCHMIEDER, B (reprint author), OBSERV PARIS,F-92195 MEUDON,FRANCE. OI Demoulin, Pascal/0000-0001-8215-6532 NR 4 TC 1 Z9 1 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 123 EP 126 DI 10.1016/0273-1177(93)90467-P PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400018 ER PT J AU MACHADO, ME ONG, KK EMSLIE, AG FISHMAN, GJ MEEGAN, C WILSON, R PACIESAS, WS AF MACHADO, ME ONG, KK EMSLIE, AG FISHMAN, GJ MEEGAN, C WILSON, R PACIESAS, WS TI THE FINE-SCALE TEMPORAL STRUCTURE OF HARD X-RAY-BURSTS SO ADVANCES IN SPACE RESEARCH LA English DT Article AB We report on the preliminary analysis of fast temporal fluctuations observed in hard X-ray bursts, as recorded by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP MACHADO, ME (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. NR 10 TC 32 Z9 33 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 175 EP 178 DI 10.1016/0273-1177(93)90473-O PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400024 ER PT J AU CROSBY, N ASCHWANDEN, M DENNIS, B AF CROSBY, N ASCHWANDEN, M DENNIS, B TI FREQUENCY-DISTRIBUTIONS OF SOLAR-X-RAY FLARE PARAMETERS SO ADVANCES IN SPACE RESEARCH LA English DT Article ID MICROFLARES AB We have determined frequency distributions of flare parameters from the over 12,000 solar flares that were recorded with the Hard X-ray Burst Spectrometer (HXRBS) on SMM. These parameters include the total flare duration, peak counting rate, the peak hard X-ray flux, the total energy in electrons, and the peak hard X-ray flux in electrons (the latter two computed assuming a thick-target model). The energies were computed above a threshold energy between 25 and 50 keV. All the distributions can be represented by power-laws over a range of several orders of magnitude, above the HXRBS sensitivity threshold. Power-laws can be taken as evidence for self-organized criticality in solar flares. Correlations among these parameters are determined from linear regression fits as well as from the slopes from the frequency distributions. Variations of the frequency distributions were also investigated with respect to the solar cycle. C1 CATHOLIC UNIV AMER,WASHINGTON,DC 20064. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP CROSBY, N (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 14 TC 6 Z9 6 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 179 EP 182 DI 10.1016/0273-1177(93)90474-P PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400025 ER PT J AU SAWANT, HS CECATTO, JR DENNIS, BR GARY, DE HURFORD, GJ AF SAWANT, HS CECATTO, JR DENNIS, BR GARY, DE HURFORD, GJ TI HIGH-SPECTRAL-RESOLUTION, HIGH-SENSITIVITY MICROWAVE AND ASSOCIATED HARD X-RAY-BURSTS SO ADVANCES IN SPACE RESEARCH LA English DT Article ID SOLAR AB We have carried out mm-wavelength (18 - 23) GHz observations of solar bursts in June 1989, in Brazil. Nine of the bursts were observed simultaneously with the Hard X-ray Burst Spectrometer (HXRBS) on the Solar Maximum Mission (SMM). The Owens Valley Radio Observatory (OVRO) observed five of these events from 1 to 18 GHz. To date, we have analyzed six of these events and the preliminary results are: (i) The turnover frequency of all of these bursts were in the frequency range of 7 - 11 GHz and the radio spectral index ranged from -0.3 to -5.3; (ii) In three bursts, dominant features of high energy (greater-than-or-equal-to 200 keV) X-rays coincided in time with mm-wavelength peaks, suggesting that the high energy electrons are responsible for the mm-wavelength emission. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CALTECH,PASADENA,CA 91125. RP SAWANT, HS (reprint author), INST NACL PESQUISAS ESPACIAIS,DIV ASTROFIS,CP 515,BR-12201 S JOSE CAMPO,SP,BRAZIL. RI Dennis, Brian/C-9511-2012; OI Gary, Dale/0000-0003-2520-8396 NR 6 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 191 EP 194 DI 10.1016/0273-1177(93)90477-S PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400028 ER PT J AU SCHWARTZ, RA FISHMAN, G MEEGAN, C WILSON, R PACIESAS, W AF SCHWARTZ, RA FISHMAN, G MEEGAN, C WILSON, R PACIESAS, W TI STUDYING FLARE ACCELERATED ELECTRONS WITH BATSE SO ADVANCES IN SPACE RESEARCH LA English DT Article ID SOLAR-FLARES AB The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory has opened a hard X-ray window of unprecedented sensitivity from 10 to several hundreds of keV which allows a fresh examination of the details of the accelerated electron spectrum during solar flares. Using the BATSE Spectroscopy detectors we have examined the low energy hard X-ray spectrum for thermal components and evidence of cutoffs in the accelerated electron spectrum. C1 NASA,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP SCHWARTZ, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,HUGHES STX,CTR SOLAR DATA ANAL,CODE 682,GREENBELT,MD 20771, USA. NR 6 TC 12 Z9 12 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 233 EP 236 DI 10.1016/0273-1177(93)90482-Q PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400033 ER PT J AU SCHMELZ, JT FLUDRA, A AF SCHMELZ, JT FLUDRA, A TI UNIQUE SMM OBSERVATIONS OF AN IMPULSIVE DOUBLE SOLAR-FLARE - ENHANCED NEON ABUNDANCE SO ADVANCES IN SPACE RESEARCH LA English DT Article ID EMISSION; LINES AB The Solar Maximum Mission Flat Crystal Spectrometer observed a GOES M5 double impulsive flare on 05 November 1980. Simultaneous spectra of seven bright soft X-ray resonance lines provide information over a broad temperature range (2-35 x 10(6) K) and are available throughout the event. A differential emission measure analysis reveals that the flux of the Ne IX resonance line is larger than expected. Various sources of contamination, non-equilibrium and multi-thermal effects, and possible errors in the atomic physics calculations are investigated and eliminated as the source of the unexpected flux, and it is suggested, rather, that the neon abundance is enhanced in this flare. C1 UNIV LONDON UNIV COLL,MULLARD SPACE SCI LAB,LONDON WC1E 6BT,ENGLAND. RP SCHMELZ, JT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 14 TC 12 Z9 12 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 325 EP 328 DI 10.1016/0273-1177(93)90500-B PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400051 ER PT J AU REAMES, DV AF REAMES, DV TI NONTHERMAL PARTICLES IN THE INTERPLANETARY MEDIUM SO ADVANCES IN SPACE RESEARCH LA English DT Article ID SOLAR ENERGETIC PARTICLES; CORONAL MASS EJECTIONS; HE-3-RICH EVENTS; IMPULSIVE ACCELERATION; SHOCK ACCELERATION; ELECTRON EVENTS; FLARES; ABUNDANCES; SPECTRA; WAVES AB During the past few years we have found that the MeV ion populations from a variety different of solar and interplanetary sources have quite distinct abundances and spectra. Particles from impulsive flares are electron rich, have He-3/He-4 enhancements of up to 10(4), and enhancements in heavy elements like Fe/C by factors of 10, relative to coronal abundances. The high ionization state of Fe, +20, indicates heating of the material to temperatures up to approximately 20 MK (1 MK = 10(6) K). The enhancements are probably produced by selective absorption of plasma waves in these events. In contrast, particles from gradual solar events have strong proton enhancements at high energies, but element abundances and ionization states are more typical of ambient coronal material. The abundances, time profiles, and extended longitude distribution of gradual events indicate that particles are accelerated from the ambient corona and solar wind by a shock wave that is driven by a coronal mass ejection. RP REAMES, DV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 37 TC 55 Z9 56 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 331 EP 339 DI 10.1016/0273-1177(93)90501-2 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400052 ER PT J AU ADAMS, JH BEAUJEAN, R BOBERG, PR GRIGOROV, NL KONDRATYEVA, MA MASON, GM MCGUIRE, RE MEWALDT, RA PANASYUK, MI TRETYAKOVA, CA TYLKA, AJ ZHURAVLEV, DA AF ADAMS, JH BEAUJEAN, R BOBERG, PR GRIGOROV, NL KONDRATYEVA, MA MASON, GM MCGUIRE, RE MEWALDT, RA PANASYUK, MI TRETYAKOVA, CA TYLKA, AJ ZHURAVLEV, DA TI DETERMINING THE CHARGE STATES OF SOLAR ENERGETIC IONS DURING LARGE GEOMAGNETIC STORMS SO ADVANCES IN SPACE RESEARCH LA English DT Article ID PARTICLES; RAYS AB We give a progress report on a new method of measuring the mean ionic charge states of solar energetic particles (SEPs) and apply this method to oxygen ions at energies of approximately 10 MeV/nucleon. We compare simultaneous flux measurements inside and outside the magnetosphere to determine the geomagnetic transmission and use this result to find the corresponding mean ionic charge state. The key to this method is to determine the dependence of the geomagnetic transmission function on the mean ionic charge state of the ions. We report here the results of a new technique to calculate the geomagnetic transmission function, which attempts to account for the cutoff suppression caused by the geomagnetic activity which often accompanies SEP events. C1 CHRISTIAN ALBRECHTS UNIV KIEL,INST REINE & ANGEW KERNPHYS,W-2300 KIEL 1,GERMANY. MOSCOW MV LOMONOSOV STATE UNIV,NUCL PHYS RES INST,MOSCOW 119899,RUSSIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CALTECH,DOWNS LAB 22047,PASADENA,CA 91125. UNIV MARYLAND,DEPT PHYS,COLL PK,MD 20742. UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLL PK,MD 20742. RP ADAMS, JH (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,CODE 7654,WASHINGTON,DC 20375, USA. RI Panasyuk, Mikhail/E-2005-2012; Tylka, Allan/G-9592-2014 NR 17 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 367 EP 370 DI 10.1016/0273-1177(93)90507-8 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400058 ER PT J AU SABA, JLR STRONG, KT AF SABA, JLR STRONG, KT TI CORONAL ABUNDANCES OF O, NE, MG, AND FE IN SOLAR ACTIVE REGIONS SO ADVANCES IN SPACE RESEARCH LA English DT Article ID ENERGETIC PARTICLES; OXYGEN; FLARE AB High resolution soft X-ray spectra acquired with the Flat Crystal Spectrometer on Solar Maximum Mission provide an excellent data base for studying abundances in solar active regions, and testing current ideas on elemental selection by first ionization potential (FIP). The temperature-diagnostic line ratio Fe XVIII/Fe XVII allows removal of the weak temperature dependence of line ratios involving 0 VIII, Ne IX, Mg XI, and Fe XVII, to determine the relative abundances among the 'high-FIP'' elements 0 and Ne, and the 'low-FIP'' elements Mg and Fe. Significant variability is found for all combinations of relative abundance. The low-FIP/high-FIP Fe:Ne, Mg:Ne, and Mg:O vary by at least a factor of 5; the low-FIP/high-FIP Fe:O, the low-FIP/low-FIP Mg:Fe and the high-FIP/high-FIP Ne:O vary by a factor of 3. The extreme values of the relative abundances depend on the line emissivity calculations used, but the magnitude of variation is about the same for any simple curve through the data. No single set of atomic parameters and ion fractions can account for the observed variations. C1 NASA,GODDARD SPACE FLIGHT CTR,GSFC,CTR SOLAR DATA ANAL,GREENBELT,MD 20771. RP SABA, JLR (reprint author), LOCKHEED SOLAR & ASTROPHYS LAB,DEPT 9130,BLDG 252,3251 HANOVER ST,PALO ALTO,CA 94304, USA. NR 19 TC 12 Z9 12 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 391 EP 394 DI 10.1016/0273-1177(93)90510-I PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400061 ER PT J AU LIN, RP DENNIS, BR EMSLIE, AG RAMATY, R CANFIELD, R DOSCHEK, G AF LIN, RP DENNIS, BR EMSLIE, AG RAMATY, R CANFIELD, R DOSCHEK, G TI THE NASA HIGH-ENERGY SOLAR PHYSICS (HESP) MISSION FOR THE NEXT SOLAR MAXIMUM SO ADVANCES IN SPACE RESEARCH LA English DT Article ID X-RAY-BURSTS; COLLISIONLESS CONDUCTION FRONT; FLARES; PARTICLES; SPECTRA AB The NASA High Energy Solar Physics (HESP) mission offers the opportunity for major breakthroughs in our understanding of the fundamental energy release and particle acceleration processes at the core of the solar flare problem. HESP's primary strawman instrument, the High Energy Imaging Spectrometer (HEISPEC). will provide X-ray and gamma-ray imaging spectroscopy, i.e., high-resolution spectroscopy at each spatial point in the image. It has the following unique capabilities: (1) high-resolution (approximately keV) spectroscopy from 2 keV - 20 MeV to resolve flare gamma-ray lines and sharp features in the continuum; (2) hard X-ray imaging with 2'' angular resolution and tens of millisecond temporal resolution, commensurate with the travel and stopping distances and times for the accelerated electrons; (3) gamma-ray imaging with 4''-8'' resolution with the capability of imaging in specific lines or continuum regions; (4) moderate resolution imaging of energetic (20 MeV to approximately 1 GeV) gamma-rays and neutrons. Additional strawman instruments include a Bragg crystal spectrometer for diagnostic information and a soft X-ray/XUV/UV imager to map the flare coronal magnetic field and plasma structure. The HESP mission also includes extensive ground-based observational and supporting theory programs. Presently BESP is planned for a FY 1995 new start and late 1999 launch. in time for the next solar activity maximum. C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV ALABAMA,HUNTSVILLE,AL 35899. UNIV HAWAII,HONOLULU,HI 96822. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USN,RES LAB,WASHINGTON,DC 20375. RP LIN, RP (reprint author), UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720, USA. RI Dennis, Brian/C-9511-2012 NR 32 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0273-1177 J9 ADV SPACE RES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 401 EP 410 DI 10.1016/0273-1177(93)90512-A PG 10 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400063 ER PT J AU SUESS, ST AF SUESS, ST TI THE RELATIONSHIP BETWEEN CORONAL AND INTERPLANETARY MAGNETIC-FIELDS SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID HELIOSPHERIC CURRENT SHEET; HEAT-FLUX DROPOUTS; SOLAR-WIND; TURBULENCE; EVOLUTION; SUN; ORIGIN; STORMS; CLOUDS; MODEL AB The morphology of the interplanetary magnetic field (IMF) is being used increasingly often to diagnose the state and solar origin of interplanetary plasma. For example, the heliospheric current sheet has been used to locate the magnetic equator and relate it to the coronal streamer belt. More often, recently, has been use of variance analysis of the IMF to infer the topology of apparent magnetic loops, magnetic draping, and relationships between the IMF and photospheric fields. These time-dependent IMF variations open new horizons for relating the IMF to the coronal field. Here, I review applications of coronal magnetic field models to predicting the quasi-stead IMF morphology and review recent applications of IMF variance analysis to diagnose origins and history of solar wind plasma. RP SUESS, ST (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB ES52, HUNTSVILLE, AL 35812 USA. NR 72 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 31 EP 42 PG 12 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400005 ER PT J AU WEBB, D JACKSON, B HICK, P SCHWENN, R BOTHMER, V REAMES, D AF WEBB, D JACKSON, B HICK, P SCHWENN, R BOTHMER, V REAMES, D TI COMPARISON OF CMES, MAGNETIC CLOUDS, AND BIDIRECTIONALLY STREAMING PROTON EVENTS IN THE HELIOSPHERE USING HELIOS DATA SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article AB Coronal Mass Ejections (CMEs) are large, energetic expulsions of mass and magnetic fields from the Sun; they can significantly affect large volumes of the heliosphere and appear to be a key cause of geomagnetic storms. We have compiled a list of all significant CMEs detected by the HELIOS white light photometers from 1975-1982. We are studying the characteristics of these CMEs, and present preliminary results of their associations with in-situ features, especially magnetic ''clouds'' and periods of bidirectionally streaming ions, two classes of structures considered indicative of interplanetary loops. Advantages of this data set include reliable association in the interplanetary medium of the white light CME plasma with the in-situ features, and observations of a large number of events over a long time base. C1 UNIV CALIF SAN DIEGO, CASS, LA JOLLA, CA 92093 USA. MAX PLANCK INST AERON, W-3411 KATLENBURG DUHM, GERMANY. GSFC, HIGH ENERGY ASTROPHYS, GREENBELT, MD 20771 USA. RP WEBB, D (reprint author), BOSTON COLL, INST SPACE RES, NEWTON, MA 02159 USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 71 EP 74 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400010 ER PT J AU RAMATY, R MANDZHAVIDZE, N KOZLOVSKY, B SKIBO, JG AF RAMATY, R MANDZHAVIDZE, N KOZLOVSKY, B SKIBO, JG TI ACCELERATION IN SOLAR-FLARES - INTERACTING PARTICLES VERSUS INTERPLANETARY PARTICLES SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID GAMMA-RAY EMISSION; ENERGETIC PARTICLES; PION DECAY; EVENTS; RADIATION; SPECTRA AB We study the properties of flare accelerated particles using gamma ray observations. We derive ion and electron energy spectra, electron to proton ratios, and numbers of interacting particles. We investigate the effects of the abundance variations implied by the gamma ray data on these parameters. We compare the results with interplanetary observations of solar flare particles. C1 UNIV MARYLAND, COLL PK, MD 20742 USA. TEL AVIV UNIV, IL-69978 TEL AVIV, ISRAEL. INST GEOPHYS, TBILISI, GA USA. RP RAMATY, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GSFC, GREENBELT, MD 20771 USA. NR 44 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 275 EP 284 PG 10 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400041 ER PT J AU MEYER, JP AF MEYER, JP TI ELEMENTAL ABUNDANCES IN ACTIVE REGIONS, FLARES AND INTERPLANETARY MEDIUM SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Review ID SOLAR ENERGETIC PARTICLES; CORONAL MASS EJECTIONS; CALCIUM ABUNDANCE; PHOTOSPHERIC ABUNDANCES; STELLAR CHROMOSPHERES; TRANSITION REGION; MAGNETIC-FIELDS; POLAR PLUME; WIND SPEED; GAMMA-RAY C1 CTR ETUDES SACLAY, SERV ASTROPHYS, F-91191 GIF SUR YVETTE, FRANCE. RP NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 107 TC 43 Z9 43 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0273-1177 J9 ADV SPACE RES-SERIES JI Adv. Space Res. PD SEP PY 1993 VL 13 IS 9 BP 377 EP 390 DI 10.1016/0273-1177(93)90509-A PG 14 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA LX184 UT WOS:A1993LX18400060 ER PT J AU PIVIROTTO, DS AF PIVIROTTO, DS TI FINDING THE PATH TO A BETTER MARS ROVER SO AEROSPACE AMERICA LA English DT Article RP PIVIROTTO, DS (reprint author), JET PROP LAB,MESUR PATHFINDER ROVER TEAM,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 1993 VL 31 IS 9 BP 12 EP & PG 0 WC Engineering, Aerospace SC Engineering GA LW164 UT WOS:A1993LW16400004 ER PT J AU KIM, S DARTNALL, T SUDWEEKS, F CRAWFORD, J HIRSH, H ANICK, P SIMOUDIS, E LANSKY, A KAMBHAMPATI, S PEDNAULT, E YANG, Q GELLER, J HORTY, J SHOHAM, Y CORNUEJOLS, A GOLDMAN, S SCHLIMMER, J FISHER, D SAITTA, L AF KIM, S DARTNALL, T SUDWEEKS, F CRAWFORD, J HIRSH, H ANICK, P SIMOUDIS, E LANSKY, A KAMBHAMPATI, S PEDNAULT, E YANG, Q GELLER, J HORTY, J SHOHAM, Y CORNUEJOLS, A GOLDMAN, S SCHLIMMER, J FISHER, D SAITTA, L TI AAAI 1993 SPRING SYMPOSIUM SERIES REPORTS SO AI MAGAZINE LA English DT Article C1 NEW JERSEY INST TECHNOL,NEWARK,NJ 07102. UNIV MARYLAND,COLL PK,MD 20742. UNIV PARIS,ORSAY,FRANCE. WASHINGTON UNIV,ST LOUIS,MO 63130. VANDERBILT UNIV,NASHVILLE,TN 37240. LOCKHEED MISSILES & SPACE CO INC,SUNNYVALE,CA 94086. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV TURIN,I-10124 TURIN,ITALY. ARIZONA STATE UNIV,TEMPE,AZ 85287. UNIV WATERLOO,WATERLOO N2L 3G1,ONTARIO,CANADA. UNIV SYDNEY,SYDNEY,NSW 2006,AUSTRALIA. AT&T BELL LABS,MURRAY HILL,NJ 07974. RUTGERS UNIV,NEW BRUNSWICK,NJ 08903. DIGITAL EQUIPMENT CORP,HUDSON,MA 01749. RP KIM, S (reprint author), GRIFFITH UNIV,NATHAN,QLD 4111,AUSTRALIA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 1993 VL 14 IS 3 BP 32 EP 37 PG 6 WC Computer Science, Artificial Intelligence SC Computer Science GA LZ499 UT WOS:A1993LZ49900004 ER PT J AU COLONIUS, T LELE, SK MOIN, P AF COLONIUS, T LELE, SK MOIN, P TI BOUNDARY-CONDITIONS FOR DIRECT COMPUTATION OF AERODYNAMIC SOUND GENERATION SO AIAA JOURNAL LA English DT Article ID HYPERBOLIC SYSTEMS; WAVE-EQUATION AB Accurate computation of the far-field sound along with the near-field source terms associated with a free shear flow requires that the Navier-Stokes equations be solved using accurate numerical differentiation and time-marching schemes, with nonreflecting boundary conditions. Nonreflecting boundary conditions have been developed for two-dimensional linearized Euler equations by Giles. These conditions are modified for use with nonlinear Navier-Stokes computations of open flow problems. At an outflow, vortical structures are found to produce large reflections due to nonlinear effects; these reflection errors cannot be improved by increasing the accuracy of the linear boundary conditions. An exit zone just upstream of an outflow where disturbances are significantly attenuated through grid stretching and filtering is developed for use with the nonreflecting boundary conditions; reflections from vortical structures are decreased by 3 orders of magnitude. The accuracy and stability of the boundary conditions are investigated in several model flows that include sound radiation by an energy source in a uniformly sheared viscous flow, the propagation of vortices in a uniform flow, and the spatial evolution of a compressible mixing layer. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, DEPT AERONAUT & ASTRONAUT, STANFORD, CA 94305 USA. RP STANFORD UNIV, DEPT MECH ENGN, STANFORD, CA 94305 USA. NR 25 TC 130 Z9 131 U1 0 U2 11 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0001-1452 EI 1533-385X J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1574 EP 1582 DI 10.2514/3.11817 PG 9 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500005 ER PT J AU HUANG, PG BRADSHAW, P COAKLEY, TJ AF HUANG, PG BRADSHAW, P COAKLEY, TJ TI SKIN FRICTION AND VELOCITY PROFILE FAMILY FOR COMPRESSIBLE TURBULENT BOUNDARY-LAYERS SO AIAA JOURNAL LA English DT Article AB The paper presents a general approach to constructing mean velocity profiles for compressible turbulent boundary layers with isothermal or adiabatic walls. The theory is based on a density-weighted transformation that allows the extension of the incompressible similarity laws of the wall to the compressible regions. The velocity profile family is compared to a range of experimental data, and excellent agreement is obtained. A self-consistent skin friction law, which satisfies the proposed velocity profile family, is derived and compared with the well-known Van Driest II theory for boundary layers in zero pressure gradient. The results are found to be at least as good as those obtained by using the Van Driest II transformation. C1 ELORET INST,PALO ALTO,CA 94303. STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. RP HUANG, PG (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 49 Z9 54 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1600 EP 1604 DI 10.2514/3.11820 PG 5 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500008 ER PT J AU NG, LL ZANG, TA AF NG, LL ZANG, TA TI SECONDARY INSTABILITY MECHANISMS IN COMPRESSIBLE AXISYMMETRICAL BOUNDARY-LAYERS SO AIAA JOURNAL LA English DT Article ID STABILITY AB Secondary instability mechanisms in compressible, axisymmetric boundary layers are analyzed using spectrally accurate mean-flow and stability codes. Results show that subharmonic disturbances are the most dangerous secondary disturbances in an environment with a low to moderate intensity of the primary disturbance. The relation between spatial and temporal analyses of the secondary disturbance is explored at Mach 1.6 along a flat plate and Mach 6.8 along a cone. Spatial direct numerical simulations are utilized to confirm the quantitative predictions from spatial secondary instability theory. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665. NR 16 TC 1 Z9 1 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1605 EP 1610 DI 10.2514/3.11821 PG 6 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500009 ER PT J AU RAUSCH, RD BATINA, JT YANG, HTY AF RAUSCH, RD BATINA, JT YANG, HTY TI 3-DIMENSIONAL TIME-MARCHING AEROELASTIC ANALYSES USING AN UNSTRUCTURED-GRID EULER METHOD SO AIAA JOURNAL LA English DT Article ID VORTICAL FLOW COMPUTATIONS; FLUTTER ANALYSIS; EQUATIONS; MESHES; WINGS AB Modifications to a three-dimensional, implicit, upwind, unstructured-grid Euler code for seroelastic analysis of complete aircraft configurations are described. The modifications involve the addition of the structural equations of motion for their simultaneous time integration with the governing flow equations. The paper presents a detailed description of the time-marching seroelastic procedures and presents comparisons with experimental data to provide an assessment of the capability. Flutter results are shown for an isolated 45-deg swept-back wing and a supersonic transport configuration with a fuselage, clipped delta wing, and two identical rearward-mounted engine nacelles. Comparisons are made between computed and experimental flutter characteristics to assess the accuracy of the aeroelastic results. C1 NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,UNSTEADY AERODYNAM BRANCH,HAMPTON,VA 23681. PURDUE UNIV,SCH ENGN,W LAFAYETTE,IN 47907. RP RAUSCH, RD (reprint author), PURDUE UNIV,SCH AERONAUT & ASTRONAUT,W LAFAYETTE,IN 47907, USA. NR 40 TC 32 Z9 32 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1626 EP 1633 DI 10.2514/3.11824 PG 8 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500012 ER PT J AU SRINIVASAN, GR MCCROSKEY, WJ AF SRINIVASAN, GR MCCROSKEY, WJ TI EULER CALCULATIONS OF UNSTEADY INTERACTION OF ADVANCING ROTOR WITH A LINE VORTEX SO AIAA JOURNAL LA English DT Article ID EQUATIONS; SIMULATIONS AB The unsteady, three-dimensional flowfield of a helicopter rotor blade in forward night encountering a concentrated line vortex is calculated using an implicit, finite difference numerical procedure for the solution of Euler equations. A prescribed vortex method is adopted to preserve the structure of the interacting vortex. The test cases considered for computation correspond to the two-bladed model rotor experimental conditions of Caradonna et al. and consist of parallel and oblique interactions. Comparison of numerical results with the test data show good agreement for the surface pressures for both parallel and oblique interactions at subsonic and transonic flow conditions. The results indicate that the subsonic parallel blade-vortex interaction is nearly two-dimensional-like and the unsteady time-lag effects appear to be negligible. However, both the three-dimensional and unsteady time-lag effects are found to be important under supercritical now conditions and these effects are accentuated in the presence of transonic shocks. In contrast, the oblique blade-vortex interaction is unsteady and three dimensional at both the subsonic and transonic now conditions. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 26 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1659 EP 1666 DI 10.2514/3.49095 PG 8 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500016 ER PT J AU MCGOWAN, DM BOSTIC, SW AF MCGOWAN, DM BOSTIC, SW TI COMPARISON OF ADVANCED REDUCED-BASIS METHODS FOR TRANSIENT STRUCTURAL-ANALYSIS SO AIAA JOURNAL LA English DT Article ID DYNAMIC ANALYSIS; RITZ VECTORS AB Two advanced reduced-basis methods, the force-derivative method and the Lanczos method, are compared with two widely used modal methods, the mode-displacement method and the mode-acceleration method. Three example structural problems are studied: an undamped and a discretely damped multispan beam subject to a uniformly distributed load that varies as a quintic function of time, and a high-speed civil transport subject to a normal wing-tip load that varies as a sinusoidal function of time. The comparison criteria include the number of basis vectors required to obtain a desired level of accuracy and the associated computational times. It is shown that, in general, the force-derivative method obtains converged solutions using the fewest number of basis vectors and the smallest amount of CPU time. However, for structures where only a small number of modes participate in the response, all of the methods require very few basis vectors for convergence, and the relative advantages of the higher order modal methods are not as significant. Although the Lanczos method was shown to be effective in solving the two undamped example problems, it was not effective in solving the discretely damped multispan beam example. C1 NASA,LANGLEY RES CTR,COMPUTAT MECH BRANCH,HAMPTON,VA 23681. RP MCGOWAN, DM (reprint author), NASA,LANGLEY RES CTR,AIRCRAFT STRUCT BRANCH,HAMPTON,VA 23681, USA. NR 17 TC 3 Z9 4 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1712 EP 1719 DI 10.2514/3.11834 PG 8 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500022 ER PT J AU KANDULA, M BUNING, PG AF KANDULA, M BUNING, PG TI EVALUATION OF BALDWIN-BARTH TURBULENCE MODEL WITH AN AXISYMMETRICAL AFTERBODY-EXHAUST JET FLOWFIELD SO AIAA JOURNAL LA English DT Note ID PREDICTIONS; FLOW C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP KANDULA, M (reprint author), LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058, USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1993 VL 31 IS 9 BP 1723 EP 1725 DI 10.2514/3.49099 PG 3 WC Engineering, Aerospace SC Engineering GA LU625 UT WOS:A1993LU62500024 ER PT J AU CONTENT, D NAMIOKA, T AF CONTENT, D NAMIOKA, T TI DEFORMED ELLIPSOIDAL GRATINGS FOR FAR-ULTRAVIOLET SPECTROGRAPHS - ANALYTIC OPTIMIZATION SO APPLIED OPTICS LA English DT Article DE DIFFRACTION GRATING; VACUUM-ULTRAVIOLET SPECTROGRAPH; ANALYTIC DESIGN METHODS; FAR-ULTRAVIOLET SPECTROSCOPIC EXPLORER ID HIGH-RESOLUTION SPECTROGRAPH; CORRECTED ASPHERIC GRATINGS; DESIGN AB Analytic formulas are developed for the semiaxes and for the deformation coefficients of a deformed ellipsoidal grating that minimize aberrations over a given spectral range. These include the Rowland circle mount and quasi-Rowland circle mounts, as required for systems that combine spectra from multiple gratings on a common detector. It is also shown that the necessary condition for a holographic grating to give a better performance over a conventional grating is the use of a convergent beam and a divergent beam for the recording. Examples applicable to the Far-Ultraviolet Spectroscopic Explorer are given. The light-path function for a deformed ellipsoidal holographic grating is also presented. C1 NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RP CONTENT, D (reprint author), NASA, GODDARD SPACE FLIGHT CTR, OPT RES SECT, MAIL CODE 717-1, GREENBELT, MD 20771 USA. NR 17 TC 6 Z9 6 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 1 PY 1993 VL 32 IS 25 BP 4881 EP 4889 PG 9 WC Optics SC Optics GA LU727 UT WOS:A1993LU72700032 PM 20830163 ER PT J AU CHANTON, JP WHITING, GJ HAPPELL, JD GERARD, G AF CHANTON, JP WHITING, GJ HAPPELL, JD GERARD, G TI CONTRASTING RATES AND DIURNAL PATTERNS OF METHANE EMISSION FROM EMERGENT AQUATIC MACROPHYTES SO AQUATIC BOTANY LA English DT Article ID GAS-TRANSPORT SYSTEM; RICE PADDIES; PHRAGMITES-AUSTRALIS; PRESSURIZED VENTILATION; FLORIDA EVERGLADES; WETLAND PLANTS; CO2 EXCHANGE; ROOTS; SOIL; ATMOSPHERE AB Rates of methane emission associated with Florida Typha domingensis Pers. and Typha latifolia L. peaked in the early daylight hours and were two to four times higher than the relatively constant rates observed in the afternoon and night. Factors associated with methane emission peaks were increasing solar illumination which drives pressurized bulk flow ventilation in T. domingensis and T. latifolia, opening of stomata, and decreasing concentrations of methane within plant stems, Cladium jamaicense Crantz, which employs diffusive gas exchange, did not exhibit diurnal variations in methane emission rates although stomatal conductance varied diurnally. Within the Florida Everglades methane emission rates were higher in T domingensis areas (143 +/- 19 mg CH4 m-2 day-1) than in C. jamaicense areas (45 +/- 15 mg CH4 m-2 day-1). These elevated rates were related to the higher above ground biomass and production in T domingensis areas relative to C jamaicense, which suggests that quantitative differences in plant biomass and production rather than qualitative differences between these plant species may control methane emissions. Methane emission was 2.7 +/- 1.4% of net daily ecosystem production (NEP) in a T. domingensis area and 14 +/- 5.8% and 3.4 +/- 4.2% of NEP in two C. jamaicense areas. C1 NASA,LANGLEY RES CTR,HUGHES STX CORP,HAMPTON,VA 23665. RP CHANTON, JP (reprint author), FLORIDA STATE UNIV,DEPT OCEANOG,TALLAHASSEE,FL 32306, USA. NR 59 TC 119 Z9 126 U1 3 U2 22 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3770 J9 AQUAT BOT JI Aquat. Bot. PD SEP PY 1993 VL 46 IS 2 BP 111 EP 128 DI 10.1016/0304-3770(93)90040-4 PG 18 WC Plant Sciences; Marine & Freshwater Biology SC Plant Sciences; Marine & Freshwater Biology GA MA504 UT WOS:A1993MA50400002 ER PT J AU HILL, JM OEGERLE, WR AF HILL, JM OEGERLE, WR TI DYNAMICS OF CD CLUSTERS OF GALAXIES .1. REDSHIFT DATA FOR 7 CLUSTERS SO ASTRONOMICAL JOURNAL LA English DT Article ID CENTRAL DOMINANT GALAXIES; EMISSION-LINE GALAXIES; RICH CLUSTERS; ABELL CLUSTERS; VELOCITY DISPERSIONS; MULTIPLE NUCLEI; BRIGHT GALAXIES; RADIO SURVEY; EVOLUTION; CANNIBALISM AB We present the initial results of a spectroscopic study of a sample of cD galaxy clusters. The goal of this program is to study the dynamics of the clusters, with emphasis on determining the nature and frequency of peculiar velocity cD galaxies. In this paper we present redshifts for 611 galaxies in the fields of the rich Abell clusters A193, A399, A401, A1795, A1809, A2063, and A2124. We discuss our data reduction techniques, and compare our derived velocities with previously published values. We find a frequency of emission line galaxies of approximately 6% in clusters, a factor of 2-3 less than the field. C1 GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HILL, JM (reprint author), UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721, USA. RI Oegerle, William/C-9070-2012 NR 53 TC 63 Z9 63 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1993 VL 106 IS 3 BP 831 EP 847 DI 10.1086/116688 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU943 UT WOS:A1993LU94300001 ER PT J AU SCHOMBERT, JM HANLAN, PC BARSONY, M RAKOS, KD AF SCHOMBERT, JM HANLAN, PC BARSONY, M RAKOS, KD TI METALLICITY GRADIENTS IN EARLY-TYPE GALAXIES SO ASTRONOMICAL JOURNAL LA English DT Article ID CCD SURFACE PHOTOMETRY; ABSOLUTE MAGNITUDE RELATION; COMPOSITE STELLAR-SYSTEMS; BRIGHT ELLIPTIC GALAXIES; GLOBULAR-CLUSTERS; SPECTRAL EVOLUTION; JHK OBSERVATIONS; COLOR GRADIENTS; STANDARD STARS; SPECTROSCOPY AB Narrow-band optical and near-IR images are used to study color gradients in elliptical and S0 galaxies. Over 90% of the 23 sample galaxies display gradients in the optical of DELTA(v-y)/DELTA log r=-0.15+/-0.08 (which corresponds to DELTA(B-R)/DELTA log r=-0.09, in agreement with previous broadband studies) and in the near-IR of DELTA(V-K)/DELTA log r=-0.27+/-0.14 and DELTA(J-K)/DELTA log r=-0.15+/-0.12. Using an empirical calibration from the optical colors v-y to Mg2 produces a mean Mg gradient for the sample equivalent to DELTAMg2/DELTA log r=-0.036+/-0.016 or DELTAMg2/DELTAmu(V)=-0.013+/-0.007. Near-IR colors imply DELTA[Fe/H]/DELTA log r=-0.48 and core [Fe/H] values between -0.5 and +0.1 versus halo values near -1.3. A discrepancy exists between optical colors, influenced by light element abundances (particularly CN), and J-K, which is dominated by the true metallicity as reflected in the mean giant branch temperature, supporting the hypothesis that the [Mg/Fe] ratio in early-type galaxies differs from other galaxies due to an enhanced Type II SN component at the initial phase of star formation [Worthey et al., ApJ, 393, 611 (1992) ]. Gradients in our continuum color, b-y, signals a blue horizontal branch population contribution in the integrated light and warns that finer knowledge of the color evolutionary history of early-type galaxies will require substantial improvements in our Spectroenergy distribution models in order to predict behavior from the far-UV to the near-IR. C1 UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV VIENNA,INST ASTRON,A-1180 VIENNA,AUSTRIA. RP SCHOMBERT, JM (reprint author), CALTECH,JET PROPULS LAB,CTR INFRARED PROC & ANAL,MS100-22,PASADENA,CA 91125, USA. NR 65 TC 25 Z9 25 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1993 VL 106 IS 3 BP 923 EP 938 DI 10.1086/116694 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU943 UT WOS:A1993LU94300007 ER PT J AU LEE, MG FREEDMAN, WL MADORE, BF AF LEE, MG FREEDMAN, WL MADORE, BF TI STELLAR POPULATIONS IN THE DWARF ELLIPTIC GALAXY NGC 185 SO ASTRONOMICAL JOURNAL LA English DT Article ID LOCAL GROUP GALAXIES; SURFACE PHOTOMETRY; GLOBULAR-CLUSTERS; NEARBY GALAXIES; GIANT BRANCH; NGC-185; STARS; DYNAMICS; SYSTEMS; M31 AB BVRI CCD photometry of approximately 5300 stars in the central (2.'2 X 3.'5) area of the dwarf elliptical galaxy NGC 185 in the Local Group is presented. The color-magnitude diagrams of NGC 185 show three distinct stellar populations: (1) a strong red giant branch (RGB) population, the tip of which found to be at I(TRGB) = 20.3 +/- 0.2 mag, and (V-1)TRGB = 1.95 +/- 0.05, (2) an asymptotic giant branch (AGB) located above the tip of the RGB, and (3) a small number of young stars having blue to yellow colors. The reddening of the bright foreground stars has been determined using the (B-V) - (V-I) diagram to be E(B-V) =0.19 +/- 0.03 mag. The distance has been estimated from the I magnitude of the tip of the RGB, giving (m-M)0 = 23.96 +/- 0.21 mag for A(I) = 0.38 mag, corresponding to 620 +/- 60 kpc. The mean metallicity of the RGB stars has been determined using the median color of the RGB stars at M(I) = -3.5 mag, (V-I)-3.5,0 = 1.727 mag: giving a mean metallicity of [Fe/H] = -1.23 +/- 0.16 dex. The dispersion in color at M(I) = -3.5 mag is DELTA(V-I)-3.5 = 0.12 mag, implying a metallicity dispersion of -1.6 < [Fe/H] < -0.9 dex. Surface photometry of the area within R = 50'' is also presented, showing that colors get rapidly bluer inside R almost-equal-to 10''. A V luminosity function for the blue stars has been derived, the slope of which is very similar to that for other nearby galaxies. The AGB stars extend to M(bol) almost-equal-to -5.0 mag, and most of the AGB stars above the tip of the RGB are likely to belong to an intermediate-age population. The bolometric luminosity function of the red giant stars in NGC 185 is found to be very similar to that of M32. C1 CALTECH,JET PROPULS LAB,CTR EXTRAGALACT DATABASE INFRARED PROC & ANAL,IPAC,NASA,PASADENA,CA 91101. RP LEE, MG (reprint author), CARNEGIE OBSERV,813 SANTA BARBARA ST,PASADENA,CA 91101, USA. NR 53 TC 68 Z9 69 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1993 VL 106 IS 3 BP 964 EP 985 DI 10.1086/116697 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU943 UT WOS:A1993LU94300010 ER PT J AU FEKEL, FC TOMKIN, J AF FEKEL, FC TOMKIN, J TI THE SPECTROSCOPIC ORBIT OF GAMMA-GEMINORUM AND A SEARCH FOR ITS SECONDARY SO ASTRONOMICAL JOURNAL LA English DT Article ID MAIN-SEQUENCE; ROTATIONAL VELOCITY; STARS; ABUNDANCES; SYSTEM; BINARIES AB New spectroscopic observations of gamma Geminorum, a bright, ''normal'' A1 IV star have resulted in an improved spectroscopic orbit. The orbital period is 12.632 +/- 0.002 yr, the eccentricity is 0.893 +/- 0.002, and the orbital parallax is 0.0291'' +/- 0.0024'' or a distance of 34 pc. We determine a v sin i of 8 +/- 1 km s-1 for the A star, which confirms that it is a slow rotator. Near-infrared spectroscopic observations at 8806 angstrom, obtained through the brief nodal passage, have resulted in the probable detection of the secondary. The masses are 2.8 and 1.07 M. and the DELTA V of the components is 6.0 mag. This DELTA V supports the value of 5.6 mag obtained by Sato et al. [AJ, 105,1553 (1993)] from observations of the asteroid occultation of gamma Gem in 1991. The magnitude difference and mass of the secondary are consistent with a G dwarf spectral type. The detection of such a faint secondary does not compromise the use in most contexts of gamma Gem as a standard star. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RP FEKEL, FC (reprint author), VANDERBILT UNIV,DYER OBSERV,DEPT PHYS & ASTRON,NASHVILLE,TN 37235, USA. NR 36 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1993 VL 106 IS 3 BP 1156 EP 1166 DI 10.1086/116714 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU943 UT WOS:A1993LU94300027 ER PT J AU SEKANINA, Z AF SEKANINA, Z TI NONGRAVITATIONAL MOTIONS OF COMETS - COMPONENT OF THE RECOIL FORCE NORMAL TO ORBITAL PLANE SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMETS; ORBITAL MOTION; NONGRAVITATIONAL PERTURBATIONS; NORMAL COMPONENT OF THE NONGRAVITATIONAL FORCE; P/CLARK ID MODEL; ENCKE AB The significance and detectability of a normal component of the nongravitational acceleration that perturbs the motions of periodic comets are examined by comparing the total perturbation effect, calculated from the component's empirical term in the equations of motion integrated over the orbital period, with the cumulative perturbations of the longitude of the ascending node and the orbital inclination brought about by the momentum that is transferred to the nucleus due to water outgassing from discrete active regions. It is shown that the approximation of temporal variations in the recoil acceleration computed using the well-known g(r) law, which is symmetrical with respect to perihelion, implies that the cumulative nongravitational perturbations of the two orbital elements are accounted for in a fashion that is inconsistent with the perturbation theory. The net result is that, in general, the expected value of the Style II nongravitational parameter that is consistent with the cumulative effect on the inclination, (i)A3, differs from the parameter's expected value that describes the cumulative effect on the nodal line, (OMEGA)A3. The parameter's distributions as functions of the spin vector and the direction of the ejecta's vector (described by the thrust angle) are represented graphically for several heliocentric orbits. Symmetries with respect to particular values of the argument of perihelion, the rotation constants, and the thrust angle that apply in the case of a baseline model (which involves assumptions of a single source and the absence of sublimation lags) are identified. The magnitudes of the parameter A3 derived from orbit-determination runs are found to be generally compatible with the presented interpretation in that they are not excessive, thus supporting the evidence presented in an earlier paper (Sekanina 1993) and based upon information on the transverse and radial components of the recoil force. The values of (i)A3 and (OMEGA)A3 are shown to coincide for certain spin-axis orientations and it is only then that the parameter A3 should reliably be determined from an orbital solution that employs the standard g(r) law. One such scenario appears to be closely approximated by Periodic Comet Clark, for which the data available are shown to provide meaningful constraints on the bulk properties of its nucleus. A potential need for a revision of the nongravitational terms in the equations of motion is suggested. RP SEKANINA, Z (reprint author), JET PROP LAB, MAIL STOP 169-237, PASADENA, CA 91109 USA. NR 55 TC 4 Z9 4 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1993 VL 277 IS 1 BP 265 EP 282 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY306 UT WOS:A1993LY30600030 ER PT J AU ALBERDI, A LARA, L MARCAIDE, JM ELOSEGUI, P SHAPIRO, II COTTON, WD DIAMOND, PJ ROMNEY, JD PRESTON, RA AF ALBERDI, A LARA, L MARCAIDE, JM ELOSEGUI, P SHAPIRO, II COTTON, WD DIAMOND, PJ ROMNEY, JD PRESTON, RA TI VLBA IMAGE OF SGR-A-ASTERISK AT LAMBDA=1.35-CM SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE RADIO SOURCES, SGR-A-ASTERISK; THE GALACTIC CENTER; INTERFEROMETRY, VLBI ID COMPACT RADIO-SOURCE; GALACTIC-CENTER; SIZE AB The compact non-thermal radio source at the Galactic Center, Sgr A*, has been imaged, at lambda=1.35 cm, for the first time with VLBI techniques. We observed Sgr A*, on 1991 June 23, with an array formed by 5 of the VLBA telescopes and the phased-VLA. The maximum angular resolution corresponded to a fringe spacing of 6.0x2.8 milliarcseconds in position angle 3-degrees (measured east from north). The observed surface brightness distribution of Sgr A* is best modelled by an elliptically shaped gaussian component with parameter values: flux density 1.07 +/- 0.15 Jy, major axis of FWHM = 2.58 0.08 milliarcseconds in position angle = 79-degrees +/- 6-degrees, and axial ratio = 0.5 +/- 0.2. The angular size of this model agrees well with the expected scattering size of Sgr A*. There is no clear evidence of any change in the source structure between our two sets of lambda=1.35 cm VLBI observations on Sgr A* which were separated by 6 years. C1 UNIV VALENCIA, E-46100 BURJASSOT, SPAIN. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. NATL RADIO ASTRON OBSERV, CHARLOTTESVILLE, VA 22901 USA. NATL RADIO ASTRON OBSERV, SOCORRO, NM 87801 USA. JET PROP LAB, PASADENA, CA 91109 USA. RP ALBERDI, A (reprint author), CSIC, INST ASTROFIS ANDALUCIA, APDO 3004, E-18080 GRANADA, SPAIN. NR 22 TC 17 Z9 17 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1993 VL 277 IS 1 BP L1 EP L4 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LY306 UT WOS:A1993LY30600001 ER PT J AU SHRADER, CR GONZALEZRIESTRA, R AF SHRADER, CR GONZALEZRIESTRA, R TI IUE OBSERVATIONS OF X-RAY NOVA MUSCAE 1991 DURING OUTBURST SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, INDIVIDUAL, NOVA MUSCAE 1991; ULTRAVIOLET, STARS; STARS, NOVAE, CATACLYSMIC VARIABLES; X-RAYS, STARS AB We report on a series of ultraviolet spectroscopic observations made with the IUE satellite, which sampled critical outburst stages of the soft X-ray transient Nova Muscae 1991. Continuum light curves, and multi-epoch line analysis are presented. The lambdalambda1500-3300 continuum fits approximately the ''canonical'' f(v) is-proportional-to nu1/3 power law expected for thermal emission from steady state accretion disk, while such a fit over the entire IUE band is less satisfactory. The emission line spectrum contains prominent high ionization lines of C IV (lambda1549) and N V (lambda1240) at each epoch; He II (lambda1640) is detected at most epochs, but is marginally detected or undetected in several cases. Weaker lines are seen at intermittent epochs, including possible detection of some lower ionization species of carbon and nitrogen. The latter occur most frequently about 6 weeks post-outburst and thereafter, and may be indicative of the increasing prominence of a cooler, outer disk region or related to the onset of a transition to an optically thin state in the disk. There was a softening of the continuum occurring about 6 weeks post-outburst as well. Several galactic absorption lines are detected, in addition to complex, bands of blended absorption lines or a pseudocontinuum of unresolved emission lines which evolve significantly over the course of the event. Broad Ly-alpha absorption is seen at each epoch. Derivation of the interstellar extinction towards the source, and its implications on distance estimates is discussed. Comparisons between the UV spectra of Nova Muscae 1991 and those of several previous soft X-ray transient events and steady low mass X-ray binary systems are made. C1 ESA, IUE OBSERV, VILSPA, E-28080 MADRID, SPAIN. NASA, GODDARD SPACE FLIGHT CTR, IUE OBSERV, GREENBELT, MD 20771 USA. ESTEC, DEPT SPACE SCI, DIV ASTROPHYS, NOORDWIJK, NETHERLANDS. RP SHRADER, CR (reprint author), NASA, GODDARD SPACE FLIGHT CTR,COMP SCI CORP, HIGH ENERGY ASTROPHYS LAB,CODE 668-1,BLDG 7, RM 258, GREENBELT, MD 20771 USA. NR 24 TC 11 Z9 11 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1993 VL 276 IS 2 BP 373 EP 381 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LW895 UT WOS:A1993LW89500008 ER PT J AU NEMIROFF, RJ NORRIS, JP WICKRAMASINGHE, WADT HORACK, JM KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS AF NEMIROFF, RJ NORRIS, JP WICKRAMASINGHE, WADT HORACK, JM KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS TI SEARCHING GAMMA-RAY BURSTS FOR GRAVITATIONAL LENSING ECHOES - IMPLICATIONS FOR COMPACT DARK-MATTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GAMMA-RAYS; BURSTS; GRAVITATIONAL LENSING ID COSMOLOGICAL DENSITY; OBJECTS AB The first available 44 gamma-ray bursts (GRBs) detected by the Burst and Transient Source Experiment on board the Compton Gamma-Ray Observatory have been inspected for echo signals following shortly after the main signal. No significant echoes have been found. Echoes would have been expected were the GRBs distant enough and the universe populated with a sufficient density of compact objects composing the dark matter. Constraints on dark matter abundance and GRB redshifts from the present data are presented and discussed. Based on these preliminary results, a universe filled to critical density of compact objects between 10(6.5) M. and 10(8.1) M. are now marginally excluded, or the most likely cosmological distance paradigm for GRBs is not correct. We expect future constraints to be able either to test currently popular cosmological dark matter paradigms or to indicate that GRBs do not lie at cosmological distances. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. UNIV PENN,PHILADELPHIA,PA 19104. RP NEMIROFF, RJ (reprint author), UNIV SPACE RES ASSOC,WASHINGTON,DC, USA. RI Horack, John/J-6670-2016 NR 30 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 36 EP 40 DI 10.1086/173054 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400004 ER PT J AU MALONEY, P AF MALONEY, P TI SHARP EDGES TO NEUTRAL HYDROGEN DISKS IN GALAXIES AND THE EXTRAGALACTIC RADIATION-FIELD SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; DIFFUSE RADIATION; GALAXIES, INDIVIDUAL (NGC-3198); GALAXIES, ISM; GALAXIES, KINEMATICS AND DYNAMICS ID ON SPIRAL GALAXIES; H-ALPHA EMISSION; DARK MATTER; PHOTOIONIZATION MODELS; VELOCITY DISPERSION; MASS-DISTRIBUTION; CLOUDS; GAS; REDSHIFT; LINE AB Recent observations of the late-type spiral galaxy NGC 3198 show that the extended atomic hydrogen distribution in this galaxy is sharply truncated at a neutral hydrogen column density of N(H I) almost-equal-to 5 x 10(19) cm-2 (van Gorkom et al. 1993). In this paper I show that this cutoff can be reasonably explained as the result of photoionization of the gas by the extragalactic radiation field. I treat the gaseous disk in plane-parallel geometry, with the vertical equilibrium explicitly calculated for a composite disk/halo model; the gas is assumed to be smoothly distributed and isothermal, with T is similar to 10(4) K. The extragalactic radiation field is taken to be a power law between the Lyman limit and the observed value at 1.5 keV; the actual intensity at the Lyman limit is a free parameter. Models calculated for a range of velocity dispersions and ionizing photon fluxes show similar behavior, with a characteristic column density N(cr) is similar to a few times 10(19) cm-2 at which the ionization fraction sharply increases. This result is not significantly affected by halo eccentricity, but does depend on the clumpiness of the gas. Specific application to NGC 3198 shows that the total hydrogen distribution may be nearly axisymmetric, and that the atomic hydrogen at large radii is not significantly clumped into clouds. The column density at which this transition occurs is not very sensitive to galaxy mass or halo parameters, changing by only a factor of approximately 3 as the halo surface density SIGMA(h) is varied by a factor of approximately 30. The numerical results are in good agreement with an analytic estimate of the critical column density; the analytic result shows that N(cr) is-proportional-to [phi(i,ex)sigma(zz) V(A)/SIGMA(h)]1/2, here V(A) is the halo asymptotic velocity, sigma(zz) is the gas vertical velocity dispersion, and phi(i,ex) is the extragalactic ionizing photon flux. Because of the insensitivity to galaxy parameters, this model predicts that all disk galaxies will show sharp edges to their neutral hydrogen distributions at similar column densities, as first discussed by Bochkarev & Sunyaev (1977). It also predicts that objects with atomic hydrogen surface densities below this critical value will be mostly ionized and hence undetectable in the 21 cm line. If the observed H I cutoffs are due to photoionization, the extragalactic ionizing photon flux in the energy range hv = 13.6 approximately 200 eV must be 5 x 10(3) less than or similar to phi(i,ex) less than or similar to 5 x 10(4) photons cm-2 s-1. The emission measure EM of ionized gas at large radii is generally too small to be detectable by emission in Halpha at present. Strict limits on or eventual measurement of EM(R) and determination of the neutral gas velocity dispersion will allow a more precise determination of phi(i,ex). C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STERREWACHT LEIDEN,LEIDEN,NETHERLANDS. NR 49 TC 161 Z9 161 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 41 EP 56 DI 10.1086/173055 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400005 ER PT J AU NOLAN, PL BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF NOLAN, PL BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI OBSERVATION OF HIGH-ENERGY GAMMA-RAYS FROM THE QUASI-STELLAR OBJECT CTA-102 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL, CTA-102 ID ACTIVE GALACTIC NUCLEI; X-RAY; RADIO-SOURCES; TELESCOPE; RADIATION; SPECTRUM; 3C-279; JETS AB The quasar CTA 102 (QSO 2230+114) was observed 4 times in 1991-1992 by the EGRET high-energy gamma-ray telescope on the Compton Gamma-Ray Observatory satellite. In the 1992 January 23-February 6 observation, emission was detected at the level (2.4 +/- 0.5) x 10(-7) photons cm-2 s-1 (E > 100 MeV). The other observations produced upper limits or detections with lower significance which are consistent with the same flux. The photon spectrum can be represented by a power law with a number index of 2.6 +/- 0.2, the softest so far observed by EGRET. The emitted gamma-ray luminosity, if isotropic, is 5 x 10(47) ergs s-1 (H0 = 75 km s-1 Mpc-1, q0 = 0.5), although there are good reasons to believe that the gamma emission is strongly beamed. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. COMP SCI CORP,COMPTON OBSERV,CTR SCI SUPPORT,GREENBELT,MD 20771. UNIV SPACE RES ASSOC,WASHINGTON,DC. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP NOLAN, PL (reprint author), STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 50 TC 33 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 82 EP 85 DI 10.1086/173058 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400008 ER PT J AU RUSSELL, WS ROBERTS, WW AF RUSSELL, WS ROBERTS, WW TI ANALYSIS OF THE DISTRIBUTION OF PITCH ANGLES IN MODEL GALACTIC DISKS - NUMERICAL-METHODS AND ALGORITHMS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ISM; GALAXIES, KINEMATICS AND DYNAMICS; GALAXIES, SPIRAL ID SPIRAL GALAXIES; STAR FORMATION; MODAL APPROACH; SIMULATIONS; MORPHOLOGY; MECHANISMS; DYNAMICS AB Numerical methods and algorithms are developed for analyzing the morphology of global and local structure in prototype and observed disk-shaped galaxies. One prototype spiral galaxy, taken from the 1992 theoretical-computational studies of Roberts et al., serves as the representative candidate to be analyzed in this paper. From the computed distribution of the gaseous component, ''partitioning'' methods based on nearest-neighbor and Voronoi polyhedra calculations are applied to capture regions of high-population gas density associated with local arm segments, spurs, feathers, and secondary features. The pitch angle and length of each of these features are determined using least-squares procedures minimizing perpendicular distances from data points to the regression curve in adapted logarithmic spiral coordinates. The resulting least-squares approximations are further checked for goodness of fit using the Kolmogorov-Smirnov test. Despite the fact that the representative prototype model galaxy is driven by an underlying global two-armed density wave of 10-degrees-15-degrees pitch angle, the gas response is found to exhibit many local and mesoscale spiral features of much greater pitch angle. These features are attributed to the self-gravitational effects of the gas itself on local scales. Prominent peaks are found in the computed pitch angle distribution between 20-degrees and 40-degrees; these are attributed to spurs and local arm segments that branch off the underlying 10-degrees-15-degrees modal density-wave-driven global spiral pattern. Prominent highly inclined spurs and feathers in the outer half of the prototype galaxy are found to give rise to a peak pitch angle distribution between 50-degrees and 55-degrees. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. UNIV VIRGINIA, VIRGINIA INST THEORET ASTRON, CHARLOTTESVILLE, VA 22903 USA. UNIV VIRGINIA, DEPT APPL MATH, CHARLOTTESVILLE, VA 22903 USA. RP COLUMBIA UNIV, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 42 TC 3 Z9 3 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 86 EP 97 DI 10.1086/173059 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400009 ER PT J AU WALL, WF JAFFE, DT BASH, FN ISRAEL, FP MALONEY, PR BAAS, F AF WALL, WF JAFFE, DT BASH, FN ISRAEL, FP MALONEY, PR BAAS, F TI KILOPARSEC-SCALE MOLECULAR GAS EXCITATION IN SPIRAL GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ISM; GALAXIES, SPIRAL; ISM, MOLECULES ID H-II REGIONS; APERTURE-SYNTHESIS OBSERVATIONS; STAR-FORMATION; CARBON-MONOXIDE; GALACTIC-CENTER; IC 342; INFRARED-EMISSION; NEARBY GALAXIES; CO OBSERVATIONS; 158 MICRON AB We combine beam-matched (CO)-C-13, (CO)-C-12 J = 3 --> 2 and J = 2 --> 1 line data to infer the molecular gas excitation conditions in the central 500 to 1600 pc diameters of a small sample of infrared-bright external galaxies: NGC 253, IC 342, M83, Maffei 2, and NGC 6946. We find that the central 170 to 530 pc diameter regions have typical molecular gas densities ranging from less than or similar to 10(4) cm-3 (in M83) to greater than or similar to 10(5) cm-3 (in NGC 253) and that, outside of these regions, the densities are likely to be less than or similar to 10(4) cm-3. The molecular clouds outside the inner 170-530 pc are at least as warm as the molecular clouds in our Galaxy. Column densities derived from integrated (CO)-C-13 line strengths and Halpha surface brightnesses suggest that the star formation rate is enhanced in the central 170-530 pc diameters by an order of magnitude over that inferred for the outer star-forming disks in spiral galaxies. The total luminosity of each sample galaxy over all CO rotational lines is approximately 10(5)-10(6) L., which is within an order of magnitude of that of the important cooling line of [C II] at 158 mum. Additional observations of the J = 1 --> 0 lines of (CO)-O-18 and (CO)-C-13 Suggest that emission from the central kiloparsec of spiral galaxies may be optically thick in the (CO)-C-13 J = 1 --> 0 line. If so, estimates of molecular gas mass using (CO)-C-13 integrated line strengths could be too low. The sum of the molecular line observations imply the existence of two molecular gas components: a low-density [n(H-2) less than or similar to 10(3)-10(4) cm-3] component and a warm (T(K) greater than or similar to 50 K), high-density [n(H-2) greater than or similar to 10(4)-10(5) cm-3] component. The warm, dense component is probably associated with star formation. C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. STERREWACHT LEIDEN,2300 RA LEIDEN,NETHERLANDS. UNIV COLORADO,JILA,BOULDER,CO 80309. JOINT ASTRON CTR,HILO,HI 96720. RP WALL, WF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 90 TC 42 Z9 42 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 98 EP 111 DI 10.1086/173060 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400010 ER PT J AU TELESCO, CM DRESSEL, LL WOLSTENCROFT, RD AF TELESCO, CM DRESSEL, LL WOLSTENCROFT, RD TI THE GENESIS OF STARBURSTS AND INFRARED-EMISSION IN THE CENTERS OF GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, NUCLEI; GALAXIES, STARBURST; GALAXIES, STRUCTURE; INFRARED, GALAXIES ID STAR-FORMATION REGIONS; MOLECULAR GAS BAR; H-II REGIONS; ACTIVE GALACTIC NUCLEI; SPIRAL GALAXIES; X-RAY; BRIGHT GALAXIES; IRAS OBSERVATIONS; IONIZED-GAS; INTERSTELLAR MATTER AB We present 10.8 mum maps of the central regions of 21 infrared-luminous galaxies. Each map, obtained using the NASA MSFC bolometer array at the IRTF, has a resolution of approximately 4'' and spans typically 25'' x 20''. Some of the galaxies have also been mapped at 12.5, 19.2, and 30 mum. The sample consists primarily of starburst galaxies but includes several Seyferts and LINERs. On average, the flux detected in each map is approximately 58% of that detected at 12 mum by IRAS. We see a variety of morphologies, including compact and elongated sources and more complex distributions exhibiting such features as kiloparsec-size rings and double lobes. The midinfrared radiation is emitted by dust particles, and for two of the galaxies we see spatial color variations attributable to the presence of very small grains and consistent with their depletion in the starbursts. The mid-infrared emission traces the dust heated by the youngest stars. Comparison of the distributions of intense star formation and the dense neutral interstellar medium for eight of these galaxies demonstrates that the two are intimately linked. For several of the galaxies, infrared and CO peaks coincide, although for most of the galaxies the dense gas is much more extended than the star formation. Our sample contains a preponderance of barred galaxies. We show for a subset of the sample that the most intense star formation tends to occur in the circumnuclear regions at the inner Lindblad resonances (ILRs) when ILRs exist or at the nuclei when ILRs do not exist. We interpret these findings by considering how bars and dynamical resonances effect the distribution and properties of gas in galaxies. C1 APPL RES CORP,LANDOVER,MD 20785. ROYAL OBSERV,EDINBURGH EH9 3HJ,MIDLOTHIAN,SCOTLAND. RP TELESCO, CM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES63,HUNTSVILLE,AL 35812, USA. NR 205 TC 130 Z9 130 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 120 EP 143 DI 10.1086/173062 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400012 ER PT J AU MULCHAEY, JS COLBERT, E WILSON, AS MUSHOTZKY, RF WEAVER, KA AF MULCHAEY, JS COLBERT, E WILSON, AS MUSHOTZKY, RF WEAVER, KA TI SOFT-X-RAY SPECTRA OF SEYFERT-2 GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-5506, MCG-5-23-16, MARKARIAN-348); GALAXIES, SEYFERT; X-RAYS, GALAXIES ID UNIFIED MODEL; LINE EMISSION; IONIZED-GAS; NGC 1068; NGC-1068; NGC-4151; SPECTROPOLARIMETRY; POLARIZATION; MCG-5-23-16; FEATURES AB Soft X-ray spectra of three Seyfert 2 galaxies obtained with the ROSAT PSPC are presented. These spectra have the following properties: (1) For two of these objects, NGC 5506 and MCG -5-23-16, most of the flux occurs at energies greater than 1 keV and probably represents a low-energy extension of the source seen at higher (> 2 keV) energies. Both sources suffer photoelectric absorption at approximately 1 keV, implying hydrogen column densities of several times 10(22) cm-2. The third source, Mrk 348, has very little flux in the ROSAT band, suggesting a photoelectric cutoff at energies above the ROSAT band, in agreement with Ginga observations. (2) In all three galaxies, X-rays are detected at energies below these photoelectric cutoffs with flux above that expected from a model in which the source has the same spectral index as at higher energies (2-10 keV) and is covered by a uniform, cold, photoelectric absorber. This result indicates the presence of an additional component at soft energies, which we refer to as a ''soft excess.'' (3) The monochromatic flux of the soft excess measured at 1 keV is approximately 1%-2% of the directly viewed hard X-ray continuum in all three galaxies. (4) In MCG -5-23-16 and Mrk 348, the soft component is well-described by a power law with a steep spectrum (photon index, GAMMA = 4.8 and 2.4, respectively, with N approximately E(-GAMMA)) or a relatively cool (kT < 1 keV) thermal bremsstrahlung or blackbody. The third object, NGC 5506, shows no strong evidence for spectral steepening at low energies, but additional absorption from gas in the disk of the edge-on host galaxy may make the detection of such a component difficult. A steeper continuum at low energies (GAMMA approximately 2.1-3.9) than at high energies (GAMMA approximately 1.4-1.9) has also been found in some Seyfert 1 galaxies. This fact, combined with the ratio of flux in the soft to hard continuum, argues that the soft excess may be dominated by electron-scattered nuclear radiation. The ratio of soft to hard continuum flux implies the optical depth to electron scattering in the scattering zone is in the range 0.02-0.1 for these three galaxies. Alternative explanations for the soft X-ray excesses, such as blended line emission, partial covering of the nuclear source and spatially extended X-ray emission, are, however, also viable. The PSPC data allow an accurate measurement of the gas column density responsible for absorbing the hard X-ray continuum in NGC 5506 and MCG -5-23-16. In both cases, the PSPC value is in excellent agreement with previous measurements. The lack of variation of these columns over the last 14 yr is most easily understood if a molecular torus, rather than a few broad-line region clouds, is responsible for this absorption. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP MULCHAEY, JS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 45 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 144 EP 153 DI 10.1086/173063 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400013 ER PT J AU REYNOLDS, AP PARMAR, AN WHITE, NE AF REYNOLDS, AP PARMAR, AN WHITE, NE TI THE LUMINOSITY DEPENDENCE OF THE X-RAY-SPECTRUM OF THE TRANSIENT 42 2ND PULSAR EXO-2030+375 SO ASTROPHYSICAL JOURNAL LA English DT Article DE PULSARS, INDIVIDUAL (EXO-2030+375); STARS, NEUTRON; X-RAYS, STARS ID CYCLOTRON ABSORPTION FEATURE; ACCRETION TORQUES; EXO 2030+375; DISCOVERY; HERCULES-X-1; SPECTROSCOPY; X0331+53; V0332+53; FLARES; LINE AB We report on the evolution in the X-ray spectrum of the transient X-ray pulsar EXO 2030+375 during part of an outburst in 1985 May-August. The overall continuum spectral shape is similar to that of other accreting pulsars and can be represented by a power-law.spectrum modified at low energies by significant absorption and at high energies either by an exponential cutoff or by the effects of cyclotron scattering. As the luminosity decreased by a factor of approximately 100, the X-ray spectrum became harder with the photon index decreasing from 1.83 +/- 0.01 to 1.29 +/- 0.01. In addition, the high-energy cutoff energy decreased from 20 to 10 keV during the same interval. If the cutoff is interpreted in terms of cyclotron resonance scattering, then this variation implies a magnetic field strength that decreased from 2.6 x 10(12) G to 1.3 x 10(12) G. This variation implies that the cutoff energy does not provide a reliable measure of the surface magnetic field strength in this system. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REYNOLDS, AP (reprint author), ESTEC,ESA,DEPT SPACE SCI,DIV ASTROPHYS,KEPLERLAAN 1,POSTBUS 299,2200 AG NOORDWIJK,NETHERLANDS. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 29 TC 35 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 302 EP 309 DI 10.1086/173076 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400026 ER PT J AU JORDAN, SD AF JORDAN, SD TI CHROMOSPHERIC HEATING BY ACOUSTIC SHOCK-WAVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE SHOCK WAVES; SUN, CHROMOSPHERE ID TRANSFORM SPECTROMETER OBSERVATIONS; SOLAR CARBON-MONOXIDE; ATMOSPHERE; SPECTROSCOPY; BIFURCATION; MODEL AB Recent work by Anderson & Athay suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wave-fronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay. RP JORDAN, SD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 42 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP 337 EP 344 DI 10.1086/173080 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU114 UT WOS:A1993LU11400030 ER PT J AU HILL, JK ISENSEE, JE BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP AF HILL, JK ISENSEE, JE BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET PHOTOMETRY OF OB ASSOCIATIONS IN M31 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, GENERAL; GALAXIES, INDIVIDUAL (M31); ULTRAVIOLET, GALAXIES ID IMAGING TELESCOPE; ROCKET ULTRAVIOLET; MASSIVE STARS; EXTINCTION; IMAGES; CLUSTERS AB Near-UV (2490 angstrom) and far-UV (1520 angstrom) magnitudes are obtained for 76 massive stars in 24 OB associations in the central and southern portions of M31 from images obtained by the Ultraviolet Imaging Telescope during the Astro 1 spacelab mission. UV photometry is important because the most massive stars are brightest in the UV, the sensitivity to interstellar extinction is largest there, and because stars detected in the far-UV are unlikely to be foreground Galactic stars. A comparison is made with the previous UIT photometry of 30 stars in the giant association NGC 206 (A78). The brightest stars in the far-UV band in NGC 206 are approximately 1 mag brighter than the brightest stars in any of the other associations. The most likely explanation for the brighter stars in NGC 206 is the lower extinction, together with more recent formation of at least some massive stars. Extinctions are estimated from the relation between E(B-V) and the distance from the center of M31 derived by Hodge and Lee from optical CCD stellar photometry, although the extinction of NGC 206 is assumed to follow the reddening model of Hutchings, Bianchi, and Massey. From evolutionary models we estimate lower limits to the maximum stellar mass at approximately 60-100 M. in NGC 206, A29, A61, A63, A130, and A132. For other associations, the limits are in the range approximately 20-55 M.. The association with the most measured stars other than NGC 206 is A21, with 15. The brightest star in A21 is 2 mag fainter than the brightest star in NGC 206 with mass approximately 40 M., if it is a supergiant at the age of maximum far-UV luminosity. The faintness of the stars in A21 is only partially accounted for by increased extinction, according to the relation of Hodge and Lee. Ages are estimated at 3-11 Myr for the most recent star formation in each association, if the star with the brightest m152 magnitude is a blue supergiant. A mass range is computed for the brightest star in the far-UV band by assuming that it is either on the zero-age main sequence (maximum mass) or a supergiant with maximum far-UV luminosity (minimum mass). C1 NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,GSFC,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP HILL, JK (reprint author), HUGHES STX,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 24 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1993 VL 414 IS 1 BP L9 EP & DI 10.1086/186983 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU108 UT WOS:A1993LU10800003 ER PT J AU GREENHOUSE, MA FELDMAN, U SMITH, HA KLAPISCH, M BHATIA, AK BARSHALOM, A AF GREENHOUSE, MA FELDMAN, U SMITH, HA KLAPISCH, M BHATIA, AK BARSHALOM, A TI INFRARED CORONAL EMISSION-LINES AND THE POSSIBILITY OF THEIR LASER-EMISSION IN SEYFERT NUCLEI SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ATOMIC PROCESSES; GALAXIES, NUCLEI; GALAXIES, SEYFERT; INFRARED, GALAXIES; LINE, FORMATION; MASERS ID ACTIVE GALACTIC NUCLEI; X-RAY-SPECTRUM; CLASSICAL NOVAE; FORBIDDEN LINES; IONIZATION; GALAXIES; PROFILES; ELEMENTS; NGC-1068; PROGRAM AB Infrared coronal emission lines are providing a new window for observation and analysis of highly ionized gas in such Galactic and extragalactic sources as Seyfert nuclei and classical novae shells. These lines are expected to be primary coolants in colliding galaxies, galaxy cluster cooling flows, cometary-compact H II regions, and supernova remnants. In this paper, we compile a complete list of infrared (lambda > 1 mum) lines due to transitions within the ground configurations 2s(2)2p(k) and 3s(2)3p(k) (k = 1-5) or the first excited configurations 2s2p and 3s3p of highly ionized (chi greater-than-or-equal-to 100 eV) astrophysically abundant [n(X)/n(H) greater-than-or-equal-to 10(-6)]elements. Included are approximately 74 lines in ions of O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, and Ni spanning a wavelength range of approximately 1-280 mum. We present results from detailed balance calculations, critical densities for collisional deexcitation, intrinsic photon rates, branching ratios, and excitation temperatures for the majority of the compiled transitions. The temperature and density parameter space for dominant cooling via infrared coronal lines is presented, and the relationship of infrared and optical coronal lines is discussed. We find that under physical conditions found in Seyfert nuclei, 14 of 70 transitions examined have significant population inversions in levels that give rise to infrared coronal lines. Laser gain lengths and corresponding column densities are calculated for dense [10(6) less-than-or-equal-to n(e) (cm-3) less-than-or-equal-to 10(9)] collisionally ionized plasmas. Application of these results to cooler plasmas photoionized by power-law continuum radiation fields is also discussed. We find that several infrared coronal line transitions have laser gain lengths that correspond to column densities of 10(24-25) cm-2 which are modeled to exist in Seyfert nuclei. Observations that can reveal inverted level populations and laser gain in infrared coronal lines are also suggested. C1 NUCL RES CTR NEGEV,BEER SHEVA,ISRAEL. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USN,RES LAB,SOLAR TERR RELAT BRANCH,WASHINGTON,DC 20375. USN,RES LAB,ARTEP INC,WASHINGTON,DC 20375. RP GREENHOUSE, MA (reprint author), SMITHSONIAN INST,NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560, USA. NR 63 TC 35 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1993 VL 88 IS 1 BP 23 EP 48 DI 10.1086/191813 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU110 UT WOS:A1993LU11000002 ER PT J AU KEENAN, FP CONLON, ES BOWDEN, DA FEIBELMAN, WA PRADHAN, AK AF KEENAN, FP CONLON, ES BOWDEN, DA FEIBELMAN, WA PRADHAN, AK TI ELECTRON-DENSITY DIAGNOSTICS FOR GASEOUS NEBULAE INVOLVING THE O-IV INTERCOMBINATION LINES NEAR 1400-ANGSTROM SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ATOMIC DATA; PLANETARY NEBULAE, GENERAL; ULTRAVIOLET, INTERSTELLAR ID PLANETARY-NEBULAE; OPACITY CALCULATIONS; ATOMIC DATA; EMISSION; RATIOS; TEMPERATURES; EXCITATION; PROGRAM; HBV-475; IONS AB Theoretical O iv electron density sensitive emission-line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R1 = I(1407.4 angstrom)/I(1401.2 angstrom), R2 = I(1404.8 angstrom)/I(1401.2 angstrom), R3 = I(1399.8 angstrom)/I(1401.2 angstrom), and R4 = I(1397.2 angstrom)/I(1401.2 angstrom). The observed values of R1-R4, measured from high-resolution spectra obtained with the International Ultraviolet Explorer (IUE) satellite, lead to electron densities that are compatible, and which are also in good agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS,GREENBELT,MD 20771. OHIO STATE UNIV,COLUMBUS,OH 43210. RP KEENAN, FP (reprint author), QUEENS UNIV BELFAST,DEPT BIOL,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NR 21 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1993 VL 88 IS 1 BP 169 EP 172 DI 10.1086/191819 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LU110 UT WOS:A1993LU11000008 ER PT J AU ROACH, AT AAGAARD, K CARSEY, F AF ROACH, AT AAGAARD, K CARSEY, F TI COUPLED ICE-OCEAN VARIABILITY IN THE GREENLAND SEA SO ATMOSPHERE-OCEAN LA English DT Article ID MICROWAVE; CONVECTION; WATER; WINTER AB A major surface feature of the Greenland Sea during winter is the frequent eastward extension of sea ice south of 75-degrees-N and an associated embayment to the north. These features are nominally connected with the East Greenland Current, and both the promontory and the embayment are readily apparent on climatic ice charts. However, there are significant changes in these features on time-scales as short as a few days. Using a combination of satellite microwave images (SSM/I) of ice cover, meteorological data and in situ velocity, temperature and salinity records, we relate the ice distribution and its changes to the developing structure and circulation of the upper ocean during winter 1988-1989. Our measurements illustrate the preconditioning that leads to convective overturn, which in tum brings warmer water to the surface and results in the rapid disappearance of ice. In particular, the surface was cooled to the freezing point by early December and the salinity then increased through ice formation (about 0.016 m d-1) and brine rejection. Once the vertical density gradient was sufficiently eroded, a period of high heat flux (>300 W m-2) in late January provided enough buoyancy loss to convectively mix the upper water column to at least 200 m. We estimate vertical velocities at about 3 cm s-1 downward during the initial sinking. The deepening of the thermocline raised surface temperatures by over 1-degrees-C resulting in nearly 1.5 x 10(5) km2 of ice-melt within two days. Average rates of ice retreat are about 11 km d-1 southwestward, generally consistent with a wind-driven flow. Comparison of hydrographic surveys from before and after the overturning indicate the fresh water was advected out of the area, possibly to the south and east of our moorings. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP ROACH, AT (reprint author), UNIV WASHINGTON, APPL PHYS LAB, 1013 NE 40TH, SEATTLE, WA 98105 USA. NR 29 TC 30 Z9 30 U1 1 U2 4 PU CMOS-SCMO PI OTTAWA PA BOX 3211, STATION D, OTTAWA, ON K1P 6H7, CANADA SN 0705-5900 J9 ATMOS OCEAN JI Atmos.-Ocean PD SEP PY 1993 VL 31 IS 3 BP 319 EP 337 DI 10.1080/07055900.1993.9649474 PG 19 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA MC816 UT WOS:A1993MC81600002 ER PT J AU ROSE, RM HELMREICH, RL FOGG, L MCFADDEN, TJ AF ROSE, RM HELMREICH, RL FOGG, L MCFADDEN, TJ TI ASSESSMENTS OF ASTRONAUT EFFECTIVENESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB This study examined the reliability and convergent validity of three methods of peer and supervisory ratings of the effectiveness of individual NASA astronauts and their relationships with flight assignments. These two techniques were found to be reliable and relatively convergent. Seniority and a peer-rated Performance and Competence factor proved to be most closely associated with flight assignments, while supervisor ratings and a peer-rated Group Living and Personality factor were found to be unrelated. Results have implications for the selection and training of astronauts. C1 UNIV TEXAS,NASA,FAA,AEROSP CREW RES PROJECT,AUSTIN,TX 78712. RUSH UNIV,SCH MED,CHICAGO,IL 60612. RP ROSE, RM (reprint author), JOHN D & CATHERINE T MACARTHUR FDN,SUITE 1100,140 S DEARBORN ST,CHICAGO,IL 60612, USA. NR 11 TC 12 Z9 12 U1 17 U2 17 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1993 VL 64 IS 9 BP 789 EP 794 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA LW050 UT WOS:A1993LW05000001 PM 8216138 ER PT J AU MILLER, JC SHARKEY, TJ GRAHAM, GA MCCAULEY, ME AF MILLER, JC SHARKEY, TJ GRAHAM, GA MCCAULEY, ME TI AUTONOMIC PHYSIOLOGICAL DATA ASSOCIATED WITH SIMULATOR DISCOMFORT SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID MOTION SICKNESS; SPECTRAL-ANALYSIS; SINUS ARRHYTHMIA AB A physiological monitoring capability was developed for the Army's Crew Station Research and Development Facility (CSRDF), a research simulator for advanced rotorcraft. Preliminary physiological data are reported from studies of simulator-induced sickness. Our objective was to demonstrate sensitivity of physiological measures relative to self-reports of simulator sickness severity. The data suggested that heart period, tachygastria, and skin conductance level were more sensitive to simulator sickness than were vagal tone and normal myoelectrical gastric activity. C1 MONTERY TECHNOL INC, 1143 G EXECUT CIRCLE, CARY, NC 27511 USA. USA, NASA, AMES RES CTR, R & D BRANCH, CREW STN, MOFFETT FIELD, CA USA. NR 23 TC 13 Z9 13 U1 1 U2 1 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 EI 1943-4448 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1993 VL 64 IS 9 BP 813 EP 819 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA LW050 UT WOS:A1993LW05000005 PM 8216142 ER PT J AU HARM, DL ZOGRAFOS, LM SKINNER, NC PARKER, DE AF HARM, DL ZOGRAFOS, LM SKINNER, NC PARKER, DE TI CHANGES IN COMPENSATORY EYE-MOVEMENTS ASSOCIATED WITH SIMULATED STIMULUS CONDITIONS OF SPACEFLIGHT SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID WEIGHTLESSNESS; TRANSLATION; ADAPTATION; VECTION AB Compensatory vertical eye movement gain (CVEMG) was recorded during pitch oscillation in darkness before, during and immediately after exposures to the stimulus rearrangement produced by the Preflight Adaptation Trainer (PAT) Tilt-Translation Device (TTD). The TTD is designed to elicit adaptive responses that are similar to those observed in microgravity-adapted astronauts. The data from Experiment 1 yielded a statistically significant CVEMG decrease following 15 min of exposure to a stimulus rearrangement condition where the phase angle between subject pitch tilt and visual scene translation was 270-degrees, statistically significant gain decreases were not observed following exposures either to a condition where the phase angle between subject pitch and scene translation was 90-degrees or to a no-stimulus-rearrangement condition. Experiment 2 replicated the 270-degrees-phase condition from Experiment 1 and extended the exposure duration from 30 to 45 min. Statistically significant additional changes in CVEMG associated with the increased exposure duration were not observed. The adaptation time constant estimated from the combined data from Experiments 1 and 2 was 29 min. C1 MIAMI UNIV,DEPT PSYCHOL,SPATIAL ORIENTAT RES LAB,OXFORD,OH 45056. RP HARM, DL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED RES INST,MAIL CODE SDS,HOUSTON,TX 77058, USA. NR 16 TC 4 Z9 4 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1993 VL 64 IS 9 BP 820 EP 826 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA LW050 UT WOS:A1993LW05000006 PM 8216143 ER PT J AU BOEHLERT, GW MUNDY, BC AF BOEHLERT, GW MUNDY, BC TI ICHTHYOPLANKTON ASSEMBLAGES AT SEAMOUNTS AND OCEANIC ISLANDS SO BULLETIN OF MARINE SCIENCE LA English DT Review ID GREAT-BARRIER-REEF; HADDOCK MELANOGRAMMUS-AEGLEFINUS; FINE-SCALE DISTRIBUTION; EARLY LIFE-HISTORY; FISH LARVAE; CORAL REEFS; LIZARD-ISLAND; CONTINENTAL-SHELF; TROPICAL PACIFIC; HAWAIIAN-ISLANDS AB Seamounts and oceanic islands support demersal or neritic fish populations and are localized sources of eggs and larvae added to a background of oceanic ichthyoplankton. Associated larval fish assemblages, however, have been identified in few studies, and most have been based on subjective classifications of species by reproductive characteristics. At seamounts, little evidence exists that ichthyoplankton assemblages differ from the background field despite physical mechanisms proposed to maintain planktonic forms. Larvae of bottom-associated species are notably rare in samples taken in these regions. In contrast, characteristic ichthyoplankton assemblages have been described at oceanic islands. Unique assemblages may exist in embayments and lagoons, but they are not well described. Nearshore assemblages (0 to 0.5 km offshore) are dominated by larvae of small species with demersal eggs; neritic assemblages (0.5 to 5 km offshore) include inshore species with demersal and planktonic eggs mixed with larvae of certain species that are usually oceanic as adults. Although larvae of some inshore species with pelagic eggs are found offshore in oceanic assemblages (beyond 3 to 5 km), assemblages there are poorly described. Spatial and seasonal spawning behavior of adults plays the key role in formation of ichthyoplankton assemblages. Mechanisms that may maintain ichthyoplankton assemblages at islands include boundary layers, smalt scale frontal dynamics, tidal currents, topographically produced eddies, seasonally reduced or variable currents, and regions of no, or returning flow. Behavior of larvae, particularly that affecting vertical distribution, can modify the influences of these mechanisms. The integrity of assemblages can be disrupted by both biotic and abiotic factors. C1 NOAA, NATL MARINE FISHERIES SERV, SW FISHERIES SCI CTR, HONOLULU LAB, HONOLULU, HI 96822 USA. NR 118 TC 61 Z9 65 U1 0 U2 3 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 USA SN 0007-4977 EI 1553-6955 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1993 VL 53 IS 2 BP 336 EP 361 PG 26 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA MN606 UT WOS:A1993MN60600003 ER PT J AU COWEN, RK HARE, JA FAHAY, MP AF COWEN, RK HARE, JA FAHAY, MP TI BEYOND HYDROGRAPHY - CAN PHYSICAL PROCESSES EXPLAIN LARVAL FISH ASSEMBLAGES WITHIN THE MIDDLE ATLANTIC BIGHT SO BULLETIN OF MARINE SCIENCE LA English DT Article ID CAPE FEAR RIVER; WARM-CORE RING; GULF-STREAM; NORTH-CAROLINA; SLOPE WATER; VERTICAL-DISTRIBUTION; SHELFBREAK EDDIES; SURFACE SLICKS; UNITED-STATES; BAY ANCHOVY AB The summer ichthyoplankton within the New York Bight can be separated into five distinct assemblages (Coastal A and B, Shelf, Outer-shelf, and Slope). Attempts to explain the distribution of species within these assemblages based on simple hydrographic parameters such as temperature and salinity explain, on average, less than 15% of the variability. A better explanation of these groupings can be obtained by incorporating a more detailed understanding of the complex physical processes that operate within the Bight. We provide a detailed analysis of one of the larval fsh assemblages, the Slope assemblage, to demonstrate how assemblage membership may be dynamic and to elucidate which factors may be most important in maintaining assemblage boundaries and membership. While spawning location may be important in determining the presence of certain species, a clear understanding of transport routes may be needed to explain the presence of other species. Maintenance of assemblage boundaries is due to a combination of the physical features of the environment (e.g., fronts, currents) and larval behavior. Studying larvae that cross assemblage boundaries over time suggests how some larvae may actively utilize different cross-front exchange processes, and conversely, how other larvae avoid such transport. C1 NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732. RP COWEN, RK (reprint author), SUNY STONY BROOK,MARINE SCI RES CTR,STONY BROOK,NY 11794, USA. NR 72 TC 128 Z9 131 U1 0 U2 10 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1993 VL 53 IS 2 BP 567 EP 587 PG 21 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA MN606 UT WOS:A1993MN60600010 ER PT J AU DOYLE, MJ MORSE, WW KENDALL, AW AF DOYLE, MJ MORSE, WW KENDALL, AW TI A COMPARISON OF LARVAL FISH ASSEMBLAGES IN THE TEMPERATE ZONE OF THE NORTHEAST PACIFIC AND NORTHWEST ATLANTIC OCEANS SO BULLETIN OF MARINE SCIENCE LA English DT Article ID CONTINENTAL-SHELF; SPATIAL-DISTRIBUTION; GEORGES BANK; ICHTHYOPLANKTON; ASSOCIATIONS; CIRCULATION; PERSISTENCE; OREGON; EGGS AB Numerical classification is used to examine broad scale spatial patterns in the larval component of the ichthyoplankton off the west and east coasts of the United States, based on data collected during extensive surveys over several years. The multispecies spatial patterns that emerged imply the existence of persistent and geographically distinct larval fish assemblages off both coasts. Four assemblages were identified off the west coast. They include a coastal assemblage that was restricted to coastal and continental shelf waters mainly off Washington and Oregon; a slope/transitional assemblage that occurred largely along the shelf edge and slope; a Columbia River plume assemblage that was associated with the Columbia River plume during summer; and an oceanic assemblage that prevailed in deep water beyond the shelf edge and for which northern and southern components were apparent during winter and spring. The east coast assemblages include a Gulf of Maine and Georges Bank assemblage; an oceanic assemblage that was associated with the continental shelf edge and slope; and a Middle Atlantic Bight assemblage that occurred along the shelf from Cape Cod, Massachusetts, to Cape Hatteras, North Carolina, Northern, southern, inshore, and offshore components of the Middle Atlantic Bight assemblage were apparent at certain times of the year. In general, the boundaries to the assemblages are fluid, and seasonal variation in occurrence and abundance of species within assemblages is strong. The distribution of the larval fish assemblages reflects spatial structure in the oceanographic environment and, in some instances, can be related to specific hydrographic features. Among the fish taxa in both regions, adaptation of the spawning patterns to the prevailing oceanographic conditions is apparent. Co-evolution among the fishes' spawning strategies within the complex and variable marine ecosystems may have given rise to the high degree of structure observed in the ichthyoplankton spatial patterns and to the larval fish assemblages themselves. It is not possible to conclude from this limited study that the multispecies larval fish assemblages are independent ecological entities that enhance survival of the constituent species. Further investigations of finer scale spatial patterns within the larval fish assemblages and among different ontogenetic categories, as well as consideration of the zooplankton, of which fish larvae form only a small part, are necessary to understand fully the multispecies spatial patterns that prevail. C1 OREGON STATE UNIV,DEPT FISHERIES & WILDLIFE,CORVALLIS,OR 97331. NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732. RP DOYLE, MJ (reprint author), NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,7600 SAND POINT WAY NE,SEATTLE,WA 98115, USA. NR 66 TC 69 Z9 72 U1 2 U2 6 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1993 VL 53 IS 2 BP 588 EP 644 PG 57 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA MN606 UT WOS:A1993MN60600011 ER PT J AU SOMERTON, DA KOBAYASHI, DR LANDGRAF, KC AF SOMERTON, DA KOBAYASHI, DR LANDGRAF, KC TI STOCK ASSESSMENT OF NEHU, ENCRASICHOLINA-PURPUREA, USING THE EGG-PRODUCTION METHOD SO BULLETIN OF MARINE SCIENCE LA English DT Article ID HAWAIIAN ANCHOVY AB Nehu, Encrasicholina purpurea, are short lived, tropical anchovies used as baitfish for the Hawaiian pole-and-line tuna fishery. The spawning biomass of nehu within Pearl Harbor, Hawaii, was estimated weekly using the Daily Egg Production Method (DEPM). Over the 2-year study period, spawning biomass varied between 0.5 and 5.0 metric tons in response to the intensive fishery and a seasonal cyclicity in reproductive effort. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. NR 22 TC 3 Z9 3 U1 0 U2 1 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1993 VL 53 IS 2 BP 768 EP 777 PG 10 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA MN606 UT WOS:A1993MN60600017 ER PT J AU ESTABROOK, FB WAHLQUIST, HD AF ESTABROOK, FB WAHLQUIST, HD TI IMMERSION IDEALS AND THE CAUSAL-STRUCTURE OF RICCI-FLAT GEOMETRIES SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article ID FRAME BUNDLES AB A moving-frame analysis is given for the immersion of four-dimensional (pseudo-) Riemannian geometries in ten-dimensional (pseudo-) Euclidean space. The resulting Darboux bundles incorporate auxiliary connection forms that give concise quadratic expressions for the Riemann and Ricci tensors. Using Cartan-Kahler theory we calculate Cartan characters for the Ricci-flat case, which directly show how the three-dimensional foliation, constraints and causal evolution of dynamic geometry arise. Cartan character analyses are also reported for three-dimensional flat Riemannian geometry immersed in six-dimensional Euclidean space, for five-dimensional Ricci-flat geometry immersed in 15, and for some coupled and specialized fields. In all cases (m - 1)-dimensional causal foliation naturally emerges from use of the auxiliary variables describing the immersions, and the physical degrees of freedom are immediately discovered. RP ESTABROOK, FB (reprint author), JET PROP LAB,169-327,PASADENA,CA 91109, USA. NR 7 TC 6 Z9 7 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD SEP PY 1993 VL 10 IS 9 BP 1851 EP 1858 DI 10.1088/0264-9381/10/9/024 PG 8 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA MD604 UT WOS:A1993MD60400024 ER PT J AU LAI, SHY AF LAI, SHY TI FUZZY-LOGIC CONTROLLER-DESIGN FOR SPACECRAFT PROXIMITY OPERATIONS SO COMPUTERS & INDUSTRIAL ENGINEERING LA English DT Article AB A Genetic Algorithms (GAs) based method is presented in this paper for concurrent design of rule sets and membership functions for a fuzzy logic controllers to be used in spacecraft proximity operations. The heuristic nature of fuzzy logic makes GAs a natural candidate for logic design in which both rule sets and membership functions are optimized simultaneously. The employment of GAs natural genetic operations provides a means to search in a complex system space that is difficult to described mathematically. A one-dimensional controller for spacecraft proximity operations is implemented for examination in detail. The expension of the algorithm for a 6 DOF controller is discussed. RP LAI, SHY (reprint author), N CAROLINA AGR & TECH STATE UNIV,NASA,CTR RES EXCELLENCE,CONTROLS & GUIDANCE GRP,GREENSBORO,NC 27411, USA. NR 10 TC 28 Z9 29 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0360-8352 J9 COMPUT IND ENG JI Comput. Ind. Eng. PD SEP PY 1993 VL 25 IS 1-4 BP 13 EP 16 DI 10.1016/0360-8352(93)90209-G PG 4 WC Computer Science, Interdisciplinary Applications; Engineering, Industrial SC Computer Science; Engineering GA LZ695 UT WOS:A1993LZ69500004 ER PT J AU UTKU, S UTKU, B WADA, BK AF UTKU, S UTKU, B WADA, BK TI A READILY AVAILABLE ENERGY-SOURCE FOR ACTIVE VIBRATION CONTROL IN BUILDINGS SO EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS LA English DT Note ID SPACE CRANE; GEOMETRY; TRUSS AB By equipping structures with appropriate actuators, sensors and microprocessors, it is possible to suppress actively the undesirable vibrations of the structures. Due to small energy requirements, the vibration suppression in large space trusses orbiting the Earth by controlling the elongations and contractions of length-adjustable bars of the truss has been shown to be feasible both theoretically and experimentally. This method of vibration suppression is part of the 'adaptive structures technology'. It can be used for suppressing the vibrations of a building subjected to earthquake or wind excitations, provided that the much higher energy and power requirements are met. In this work the use of gravitational energy of the mass of the building is proposed for active vibration control. C1 CIT,JET PROP LAB,PASADENA,CA 91109. RP UTKU, S (reprint author), DUKE UNIV,DEPT CIVIL & ENVIRONM ENGN,DURHAM,NC 27708, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0098-8847 J9 EARTHQUAKE ENG STRUC JI Earthq. Eng. Struct. Dyn. PD SEP PY 1993 VL 22 IS 9 BP 823 EP 827 DI 10.1002/eqe.4290220907 PG 5 WC Engineering, Civil; Engineering, Geological SC Engineering GA LW525 UT WOS:A1993LW52500006 ER PT J AU NEWMAN, JC BIGELOW, CA SHIVAKUMAR, KN AF NEWMAN, JC BIGELOW, CA SHIVAKUMAR, KN TI 3-DIMENSIONAL ELASTIC-PLASTIC FINITE-ELEMENT ANALYSES OF CONSTRAINT VARIATIONS IN CRACKED BODIES SO ENGINEERING FRACTURE MECHANICS LA English DT Article AB Three-dimensional elastic-plastic (small-strain) finite-element analyses were used to study the stresses, deformations, and constraint variations around a straight-through crack in finite-thickness plates for an elastic-perfectly plastic material under monotonic and cyclic loading. Middle-crack tension specimens were analyzed for thicknesses ranging from 1.25 to 20 mm with various crack lengths. Three local constraint parameters, related to the normal, tangential, and hydrostatic stresses, showed similar variations along the crack front for a given thickness and applied stress level. Numerical analyses indicated that cyclic stress history and crack growth reduced the local constraint parameters in the interior of a plate, especially at high applied stress levels. A global constraint factor alpha(g) was defined to simulate three-dimensional effects in two-dimensional crack analyses. The global constraint factor was calculated as an average through-the-thickness value over the crack-front plastic region. Values of alpha(g) were found to be nearly independent of crack length and were related to the stress-intensity factor for a given thickness. Using the global constraint factors, crack-tip-opening displacements calculated from a modified Dugdale model compared well with the finite-element results from small- to large-scale yielding conditions for both thin and thick bodies. An application of the global constraint factor concept to model fatigue-crack growth under aircraft spectrum loading is presented. C1 N CAROLINA AGR & TECH STATE UNIV,GREENSBORO,NC 27410. RP NEWMAN, JC (reprint author), NASA,LANGLEY RES CTR,MECH MAT BRANCH,HAMPTON,VA 23681, USA. NR 33 TC 68 Z9 70 U1 1 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD SEP PY 1993 VL 46 IS 1 BP 1 EP 13 DI 10.1016/0013-7944(93)90299-8 PG 13 WC Mechanics SC Mechanics GA LX539 UT WOS:A1993LX53900001 ER PT J AU HAN, B IFJU, P POST, D AF HAN, B IFJU, P POST, D TI GEOMETRIC MOIRE METHODS WITH ENHANCED SENSITIVITY BY OPTICAL DIGITAL FRINGE MULTIPLICATION SO EXPERIMENTAL MECHANICS LA English DT Article ID DIFFRACTION AB A robust fringe-shifting and image processing scheme is applied to geometric moire experiments. High quality contour maps of U, V and W displacement fields are obtained with sensitivity enhanced by a factor of ten. The method is compatible with complicated intensity distributions, variable bar-to-space ratios of gratings, and optical noise. It is applicable to large fields for both in-plane moire and shadow moire measurements. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061. RP HAN, B (reprint author), IBM CORP,ENDICOTT ELECTR PACKAGING,1701 NORTH ST,ENDICOTT,NY 13760, USA. RI Han, Bongtae/K-7167-2013 OI Han, Bongtae/0000-0003-3721-9738 NR 10 TC 7 Z9 7 U1 0 U2 1 PU SOC EXPERIMENTAL MECHANICS PI BETHEL PA 7 SCHOOL STREET, BETHEL, CT 06801 SN 0014-4851 J9 EXP MECH JI Exp. Mech. PD SEP PY 1993 VL 33 IS 3 BP 195 EP 200 DI 10.1007/BF02322572 PG 6 WC Materials Science, Multidisciplinary; Mechanics; Materials Science, Characterization & Testing SC Materials Science; Mechanics GA LX310 UT WOS:A1993LX31000005 ER PT J AU Glazman, RE AF Glazman, Roman E. TI A CASCADE MODEL OF WAVE TURBULENCE WITH APPLICATIONS TO SURFACE GRAVITY AND CAPILLARY WAVES SO FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY LA English DT Article AB A heuristic approach to the derivation of power spectra of wave motion is described and applied to capillary waves. The case of gravity waves studied earlier is briefly reviewed. In contrast to the previous studies, the nonlinearity of the wave motion is not required to be small, and the mean number of resonantly interacting wave harmonics is not limited to a smallest possible number (which is 4 for gravity waves on a deep fluid and 3 for capillary waves). The main external parameter of the problem is the input flux Q of the wave energy related to the mean wind velocity as Q proportional to U(3). Depending on its value, wave spectra S(w) proportional to w(-q) and F(k) proportional to k(-p) take various forms - from that corresponding to the weak-turbulence limit and to that corresponding to the saturated (Phillips') wave spectra. Fractal dimensions of the sea surface are related to external factors, specifically to the mean wind speed. The theoretically predicted spectra are in qualitative agreement with the observations on capillary waves conducted in a large wave tank. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Glazman, RE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM reg@pacific.jpl.nasa.gov FU National Aeronautics and Space Administration; Office of Naval Research [N0001492J1343] FX This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Financial support was provided by the Office of Naval Research, Grant No. N0001492J1343. NR 15 TC 2 Z9 2 U1 0 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0218-348X J9 FRACTALS JI Fractals-Complex Geom. Patterns Scaling Nat. Soc. PD SEP PY 1993 VL 1 IS 3 BP 513 EP 520 DI 10.1142/S0218348X93000538 PG 8 WC Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences SC Mathematics; Science & Technology - Other Topics GA V18WZ UT WOS:000208036200024 ER PT J AU Davis, AB Marshak, AL Wiscombe, WJ AF Davis, A. B. Marshak, A. L. Wiscombe, W. J. TI BI-MULTIFRACTAL ANALYSIS AND MULTI-AFFINE MODELING OF NON-STATIONARY GEOPHYSICAL PROCESSES, APPLICATION TO TURBULENCE AND CLOUDS SO FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY LA English DT Article ID GENERALIZED DIMENSIONS; STRANGE ATTRACTORS AB In recent years, considerable progress has been achieved in the description of natural variability, largely due to the widespread use of scale-invariant concepts such as fractals and multifractals. In particular, this last concept has been used to clarify the fuzzy notion of "inhomogeneity" by introducing and quantifying the effects of intermittency. In this paper, we present a more comprehensive approach to multifractal data analysis and simulation that includes and combines the currently popular singularity analysis techniques with the more traditional approach based on structure functions. Being related to the new idea of "multi-affinity", these last statistics are regaining favor and constitute the proper framework to address the problem of quantifying and qualifying yet another outstanding fuzzy notion, that of "non-stationarity". This is an important step because non-stationary behavior is ubiquitous in Nature. Using turbulence as an example, we also show how a unified multifractal formalism can help in extracting, from data alone, the "effective constitutive laws" that describe phenomenologically the nonlinearities of the macroscopic transport processes that shape the geophysical field represented by the dataset. Finally, we argue that the essential multifractality of any natural system can be captured on the "q = 1 multifractal plane" and describe ways in which it can be used in practical geophysical problems. C1 [Davis, A. B.; Wiscombe, W. J.] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. [Marshak, A. L.] SSAI, Lanham, MD 20706 USA. RP Davis, AB (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Wiscombe, Warren/D-4665-2012; Marshak, Alexander/D-5671-2012 OI Wiscombe, Warren/0000-0001-6844-9849; FU DoE [DE-A105-90ER61069] FX This work was supported by DoE's ARM project, grant DE-A105-90ER61069 to NASA Goddard Space Flight Center. We thank A. Arneodo, R. Cahalan, D. Lavallee, S. Lovejoy, C. Meneveau, W. Ridgway, D. Schertzer, Y. Tessier and T. Warn for fruitful discussions. NR 20 TC 7 Z9 7 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0218-348X J9 FRACTALS JI Fractals-Complex Geom. Patterns Scaling Nat. Soc. PD SEP PY 1993 VL 1 IS 3 BP 560 EP 567 DI 10.1142/S0218348X93000587 PG 8 WC Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences SC Mathematics; Science & Technology - Other Topics GA V18WZ UT WOS:000208036200029 ER PT J AU Marshak, A Davis, A Cahalan, R Wiscombe, W AF Marshak, A. Davis, A. Cahalan, R. Wiscombe, W. TI MULTI-SINGULAR AND MULTI-AFFINE PROPERTIES OF BOUNDED CASCADE MODELS SO FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY LA English DT Article ID FULLY-DEVELOPED TURBULENCE; GENERALIZED DIMENSIONS; STRANGE ATTRACTORS; FORMALISM AB We investigate a class of one-dimensional bounded random cascade models which are multiplicative and stationary by construction but additive and non-stationary with respect to some, but not all, of their statistical properties. In essence, a new parameter H > 0 is introduced to "smooth" standard (p-model) cascades, these well-studied processes being retrieved at H = 0. The resulting ambivalent statistical behavior of the new model leads to a 1st order multifractal phase transition in the structure function exponents, i.e., there is a discontinuity in the derivative of zeta(q) = min{qH, 1}. We interpret this bifurcation as a separation of the stationary and non-stationary "ingredients" of the model by lowering the multifractal "temperature" (1/q) below the critical value H. We also see exactly how the generalized dimensions D-q converge to one in the small scale limit for all q. We discuss this last finding in terms of "residual" multifractality, a singularity spectrum that is entirely traceable to finite size effects (to which we are never immune in data analysis situations). Finally, we locate the bounded and unbounded versions of the model in the "q = 1 multifractal plane" where the coordinates are C-1 = 1 - D-1 (a direct measure of "intermittency") and H-1 = zeta(1) (a direct measure of "smoothness"), both of which are normally in the interval [0,1]. This provides us with a simple way of comparing the multiplicative models with their additive counterparts, as well as with different types of geophysical data. C1 [Marshak, A.] SSAI, Lanham, MD 20706 USA. [Davis, A.; Cahalan, R.; Wiscombe, W.] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Marshak, A (reprint author), SSAI, 5900 Princess Garden Pkwy, Lanham, MD 20706 USA. RI Cahalan, Robert/E-3462-2012; Wiscombe, Warren/D-4665-2012; Marshak, Alexander/D-5671-2012 OI Cahalan, Robert/0000-0001-9724-1270; Wiscombe, Warren/0000-0001-6844-9849; FU DoE [DE-A105-90ER61069] FX This work was supported by DoE's ARM project, grant DE-A105-90ER61069 to NASA Goddard Space Flight Center. We thank A. Arneodo, T. Bell, D. Lavallee, S. Lovejoy, C. Meneveau, W. Ridgway and T. Warn for fruitful discussions. NR 21 TC 0 Z9 0 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0218-348X J9 FRACTALS JI Fractals-Complex Geom. Patterns Scaling Nat. Soc. PD SEP PY 1993 VL 1 IS 3 BP 702 EP 710 DI 10.1142/S0218348X93000733 PG 9 WC Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences SC Mathematics; Science & Technology - Other Topics GA V18WZ UT WOS:000208036200044 ER PT J AU OBERBECK, VR AF OBERBECK, VR TI IMPACTS AND GLOBAL CHANGE SO GEOTIMES LA English DT Article RP OBERBECK, VR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94025, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOLOGICAL INST PI ALEXANDRIA PA 4220 KING ST, ALEXANDRIA, VA 22302-1507 SN 0016-8556 J9 GEOTIMES JI Geotimes PD SEP PY 1993 VL 38 IS 9 BP 16 EP & PG 0 WC Geosciences, Multidisciplinary SC Geology GA LV830 UT WOS:A1993LV83000008 ER PT J AU BOUWMAN, AF FUNG, I MATTHEWS, E JOHN, J AF BOUWMAN, AF FUNG, I MATTHEWS, E JOHN, J TI GLOBAL ANALYSIS OF THE POTENTIAL FOR N2O PRODUCTION IN NATURAL SOILS SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Review ID NITROUS-OXIDE PRODUCTION; TEMPERATE FOREST SOILS; GASEOUS NITROGEN; TROPICAL FOREST; TERRESTRIAL ECOSYSTEMS; FIELD MEASUREMENT; VEGETATION INDEX; GRASSLAND SOIL; AEROBIC SOILS; DRYING CYCLES AB A simple global model of the production potential of nitrous oxide (N2O) in natural soils is developed to analyze the relative importance, both geographically and seasonally, of the different controls on N2O production at the global scale. Five major controls on N2O production are included: (1) input of organic matter, (2) soil fertility, (3) soil moisture status, (4) temperature, and (5) soil oxygen status. Indices for the controls are derived form global gridded (1-degrees x 1-degrees resolution) data bases of soil type, soil texture, NDVI and climate. The model explains close to 60% of the variability found in measurements reported at about 30 sites in six different ecosystems throughout the world. Although this result is reasonable for global analyses, the correlation is considered insufficient to make global estimates of nitrous oxide emission with confidence. The model confirms conclusions from earlier studies that the major source regions of nitrous oxide are in the tropics. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10027 USA. RP BOUWMAN, AF (reprint author), NATL INST PUBL HLTH & ENVIRONM PROTECT, POB 1, 3720 BA BILTHOVEN, NETHERLANDS. RI Bouwman, Lex/B-7053-2012; John, Jasmin/F-8194-2012; Bouwman, Lex/F-1444-2015 OI John, Jasmin/0000-0003-2696-277X; Bouwman, Lex/0000-0002-2045-1859 NR 130 TC 139 Z9 148 U1 8 U2 36 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD SEP PY 1993 VL 7 IS 3 BP 557 EP 597 DI 10.1029/93GB01186 PG 41 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA LX222 UT WOS:A1993LX22200006 ER PT J AU DAI, A FUNG, IY AF DAI, A FUNG, IY TI CAN CLIMATE VARIABILITY CONTRIBUTE TO THE MISSING CO2 SINK SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID ATMOSPHERIC CO2; AIR TEMPERATURES; CARBON-DIOXIDE; PRECIPITATION; MODEL; VEGETATION; BIOSPHERE; BUDGET; RESPONSES; FORESTS AB The contemporary carbon budget for the atmosphere requires a large ''missing'' carbon sink to balance anthropogenic carbon inputs. We investigated climatic effects on carbon exchanges between the atmosphere and the undisturbed biosphere and assessed the possible contribution of climate variability to the carbon sink. Empirical models and global temperature and precipitation data sets were used in the study. It was found that climate perturbations during 1940-1988 caused considerable variations in plant productivity and soil respiration. The different sensitivities of the fluxes to climate perturbations led to a significant carbon accumulation in the biosphere. The cumulative carbon sink for the period 1950-1984 (approximately 20+/-5 GtC or 10(12) kg C) was predominantly located in mid-latitudes in the northern hemisphere (30-degrees-60-degrees-N) and could amount to half of the missing CO2 sink as derived from deconvolution analyses. Our results indicate that climate variations have unequal impacts on biospheric carbon fluxes from different ecosystems and imply that caution must be exercised in generalizing in situ observations to the globe. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP DAI, A (reprint author), COLUMBIA UNIV, DEPT GEOL SCI, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Dai, Aiguo/D-3487-2009 NR 43 TC 141 Z9 153 U1 1 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD SEP PY 1993 VL 7 IS 3 BP 599 EP 609 DI 10.1029/93GB01165 PG 11 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA LX222 UT WOS:A1993LX22200007 ER PT J AU VILAS, F LARSON, SM HATCH, EC JARVIS, KS AF VILAS, F LARSON, SM HATCH, EC JARVIS, KS TI CCD REFLECTANCE SPECTRA OF SELECTED ASTEROIDS .2. LOW-ALBEDO ASTEROID SPECTRA AND DATA EXTRACTION TECHNIQUES SO ICARUS LA English DT Article ID OUTER-BELT; SPECTROPHOTOMETRY C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. CENTENARY COLL LOUISIANA,DEPT PHYS,SHREVEPORT,LA 71104. WRIGHT STATE UNIV,DEPT GEOL,DAYTON,OH 45435. RP VILAS, F (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 31 TC 48 Z9 48 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1993 VL 105 IS 1 BP 67 EP 78 DI 10.1006/icar.1993.1111 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD454 UT WOS:A1993MD45400004 ER PT J AU HINSON, DP MAGALHAES, JA AF HINSON, DP MAGALHAES, JA TI INERTIO-GRAVITY WAVES IN THE ATMOSPHERE OF NEPTUNE SO ICARUS LA English DT Article ID RADIO OCCULTATION MEASUREMENTS; VOYAGER MEASUREMENTS; THERMAL STRUCTURE; STRATOSPHERE; TURBULENCE; FLUXES; URANUS; SYSTEM; VENUS; HEAT C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HINSON, DP (reprint author), STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305, USA. NR 49 TC 19 Z9 19 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1993 VL 105 IS 1 BP 142 EP 161 DI 10.1006/icar.1993.1115 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD454 UT WOS:A1993MD45400008 ER PT J AU HUTZELL, WT MCKAY, CP TOON, OB AF HUTZELL, WT MCKAY, CP TOON, OB TI EFFECTS OF TIME-VARYING HAZE PRODUCTION ON TITANS GEOMETRIC ALBEDO SO ICARUS LA English DT Article ID ATMOSPHERE; PHOTOCHEMISTRY; MODEL; OCCULTATION; AEROSOLS; NEPTUNE; URANUS C1 GEORGIA INST TECHNOL,SCH EARTH & ATMOSPHER SCI,ATLANTA,GA 30332. RP HUTZELL, WT (reprint author), NASA,AMES RES CTR,MAIL STOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 30 TC 22 Z9 22 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1993 VL 105 IS 1 BP 162 EP 174 DI 10.1006/icar.1993.1116 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD454 UT WOS:A1993MD45400009 ER PT J AU DONES, L CUZZI, JN SHOWALTER, MR AF DONES, L CUZZI, JN SHOWALTER, MR TI VOYAGER PHOTOMETRY OF SATURNS A RING SO ICARUS LA English DT Article ID PARTICLE-SIZE DISTRIBUTIONS; RADIO OCCULTATION; PLANETARY RINGS; BENDING WAVES; RESONANCE STRUCTURES; MULTIPLE-SCATTERING; INTERPLANETARY DUST; URANIAN SATELLITES; VERTICAL STRUCTURE; OPTICAL-PROPERTIES RP DONES, L (reprint author), NASA,AMES RES CTR,MAIL STOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 149 TC 101 Z9 101 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1993 VL 105 IS 1 BP 184 EP 215 DI 10.1006/icar.1993.1118 PG 32 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD454 UT WOS:A1993MD45400011 ER PT J AU LOVE, SG HORZ, F BROWNLEE, DE AF LOVE, SG HORZ, F BROWNLEE, DE TI TARGET POROSITY EFFECTS IN IMPACT CRATERING AND COLLISIONAL DISRUPTION SO ICARUS LA English DT Article ID SHOCK METAMORPHISM C1 NASA,LYNDON B JOHNSON SPACE CTR,GEOL & GEOPHYS BRANCH,HOUSTON,TX 77058. RP LOVE, SG (reprint author), UNIV WASHINGTON,DEPT ASTRON,FM-20,SEATTLE,WA 98195, USA. NR 24 TC 108 Z9 110 U1 2 U2 9 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1993 VL 105 IS 1 BP 216 EP 224 DI 10.1006/icar.1993.1119 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA MD454 UT WOS:A1993MD45400012 ER PT J AU LEE, AY AF LEE, AY TI NEIGHBORING OPTIMAL FEEDBACK LAW FOR LINEAR TIME-DELAYED DYNAMICAL-SYSTEMS SO IEE PROCEEDINGS-D CONTROL THEORY AND APPLICATIONS LA English DT Article DE BACKWARD SWEEP SYSTEMS; TIME-DELAYED OPTIMAL CONTROL AB One way to obtain a neighbouring feedback law for a time-delayed optimal control problem is to first transform it into a 'standard' optimisation problem. That is one without terms having a time-delayed argument. To this end, I use a Pade approximation to determine a differential relation for y(t), an augmented state that represents x(t - tau). The time-delayed optimisation problem can then be rewritten in terms of an augmented state vector consisting of both the physical state x(t) and the delayed state y(t). Once reformulated, one may use to advantage existing well-developed techniques such as the backward sweep method to obtain the neighbouring feedback law. Results obtained from two examples show good agreement between the exact results and those predicted by the feedback law for small variations in both the initial condition and a system parameter. RP LEE, AY (reprint author), JET PROP LAB,MS 198-326,PASADENA,CA 91109, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0143-7054 J9 IEE PROC-D PD SEP PY 1993 VL 140 IS 5 BP 339 EP 344 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA MG210 UT WOS:A1993MG21000008 ER PT J AU ZUCKERWAR, AJ PRETLOW, RA STOUGHTON, JW BAKER, DA AF ZUCKERWAR, AJ PRETLOW, RA STOUGHTON, JW BAKER, DA TI DEVELOPMENT OF A PIEZOPOLYMER PRESSURE SENSOR FOR A PORTABLE FETAL HEART-RATE MONITOR SO IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING LA English DT Article AB A piezopolymer pressure sensor has been developed for service in a portable fetal heart rate monitor, which will permit an expectant mother to perform the fetal nonstress test, a standard predelivery test, in her home. Several sensors are mounted in an array on a belt worn by the mother. The sensor design conforms to the distinctive features of the fetal heart tone, namely, the acoustic signature, frequency, spectrum, signal amplitude, and localization. The components of a sensor serve to fulfill five functions: signal detection, acceleration cancellation, acoustical isolation, electrical shielding, and electrical isolation of the mother. A theoretical analysis of the sensor response yields a numerical value for the sensor sensitivity, which is compared to experiment in an in vitro sensor calibration. Finally, an in vivo test on patients within the last six weeks of term reveals that nonstress test recordings from the acoustic monitor compare well with those obtained from conventional ultrasound. C1 OLD DOMINION UNIV,DEPT ELECT & COMP ENGN,NORFOLK,VA 23508. BAKER GUARDIAN MED LABS,SPOKANE,WA 99207. RP ZUCKERWAR, AJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 9 TC 36 Z9 37 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9294 J9 IEEE T BIO-MED ENG JI IEEE Trans. Biomed. Eng. PD SEP PY 1993 VL 40 IS 9 BP 963 EP 969 DI 10.1109/10.245618 PG 7 WC Engineering, Biomedical SC Engineering GA MH972 UT WOS:A1993MH97200014 PM 8288288 ER PT J AU VIVEKANANDAN, J RAGHAVAN, R BRINGI, VN AF VIVEKANANDAN, J RAGHAVAN, R BRINGI, VN TI POLARIMETRIC RADAR MODELING OF MIXTURES OF PRECIPITATION PARTICLES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID DIFFERENTIAL PHASE-SHIFT; POLARIZATION; HAIL; REFLECTIVITY AB With the recent advances of dual-polarized radar techniques in meteorology it is now possible to deduce precipitation microphysical characteristics in far more detail than possible with reflectivity measurements alone. Radar parameters such as differential reflectivity and differential phase between horizontal and vertical polarizations have been studied in detail as well as linear depolarization ratio, copolar correlation coefficient, and backscatter differential phase. While these parameters can be linked to certain microphysical properties of specific classes of precipitation such as raindrops or hail, very little study has been directed at the practically important cases of mixtures of different types of precipitation particles such as rain, hail, graupel, ice crystals, and snow. Each type can have different size, shape, orientation, and dielectric constant distributions. The treatment here is rigorous and is based on the Mueller matrix formulation. Radar parameters are derived from the averaged Mueller matrix computations. Careful consideration is given to the orientation and size distributions of the different particle types. After calculating single particle scattering characteristics, some simple two-component mixtures such as rain/hail and ice crystals/snow are considered. Finally, a 2D numerical cloud model is used to simulate the rain, hail/graupel, and snow fields of an evolving convective storm from which the radar parameters are derived for the initial, peak, and dissipating stages of the storm. Model computations are performed at C and S-band frequencies. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ES42,HUNTSVILLE,AL 35812. COLORADO STATE UNIV,DEPT ELECT ENGN,FT COLLINS,CO 80523. RP VIVEKANANDAN, J (reprint author), NATL CTR ATMOSPHER RES,BOULDER,CO 80307, USA. RI Swain , Bibhu /A-7037-2016 OI Swain , Bibhu /0000-0002-6190-7453 NR 29 TC 24 Z9 26 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1993 VL 31 IS 5 BP 1017 EP 1030 DI 10.1109/36.263772 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MP174 UT WOS:A1993MP17400009 ER PT J AU VANZYL, JJ CHAPMAN, BD DUBOIS, P SHI, JC AF VANZYL, JJ CHAPMAN, BD DUBOIS, P SHI, JC TI THE EFFECT OF TOPOGRAPHY ON SAR CALIBRATION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID POLARIMETRIC RADAR IMAGES; RADIOMETRIC CORRECTION; PHASE CALIBRATION AB During normal synthetic aperture radar (SAR) processing, a Rat earth is assumed when performing radiometric corrections such as antenna pattern and scattering area removal. Here we examine the effects of topographic variations on these corrections. Local slopes will cause the actual scattering area to be different from that calculated using the flat earth assumption. It is shown that this effect, which is present for both airborne and spaceborne SAR data, may easily cause calibration errors larger than a decibel. Ignoring the topography during antenna pattern removal mag also introduce errors of several decibels in the case of airborne systems. The effect of topography on antenna pattern removal is expected to be negligible for spaceborne SAR's. In this paper we show how these effects can be taken into account if a digital elevation model is available for the imaged area. The errors are quantified for two different types of terrain, a moderate relief area near Tombstone, AZ, and a high relief area near Oetztal in the Austrian Alps. We show errors for two well-known radar systems, the C-band ERS-1 spaceborne radar system and the three frequency NASA/JPL airborne SAR system (AIRSAR). For the moderate relief area, it is shown that the scattering area removal leads to errors that are smaller than 1 dB in most of the image, although the errors for the spaceborne case are larger than those of the airborne case, mainly because of the smaller incidence angle. In the case of the high relief area, most of the leading slopes show errors on the order of 5 dB or larger, even in the airborne case. In the spaceborne example of the Oetztal area, most of the image shows errors exceeding 1 dB, with large areas showing errors exceeding 5 dB in magnitude. Using the AIRSAR C-band antenna pattern, it is shown that extremely large errors, some well larger than 10 dB can be expected in the near range of the Oetztal image. It is also shown that not taking the topography into account during antenna pattern removal introduces polarimetric calibration errors. C1 UNIV CALIF SANTA BARBARA,SANTA BARBARA,CA 93106. CALTECH,JET PROP LAB,AIRBORNE ACT MICROWAVE SENSORS PROGRAM,PASADENA,CA. RP VANZYL, JJ (reprint author), CALTECH,JET PROP LAB,RADAR SCI & ENGN SECT,AIRCRAFT SAR GRP,PASADENA,CA 91109, USA. NR 21 TC 75 Z9 76 U1 1 U2 12 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1993 VL 31 IS 5 BP 1036 EP 1043 DI 10.1109/36.263774 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MP174 UT WOS:A1993MP17400011 ER PT J AU RAO, KS RAJU, S WANG, JR AF RAO, KS RAJU, S WANG, JR TI ESTIMATION OF SOIL-MOISTURE AND SURFACE-ROUGHNESS PARAMETERS FROM BACKSCATTERING COEFFICIENT SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note ID MICROWAVE; DEPENDENCE; MODELS AB A statistical inversion technique was implemented to estimate soil moisture and surface roughness parameters from the remotely sensed multifrequency backscattering coefficients. Both two- and three-frequency approaches were examined and tested in detail for the inversion technique. Initially the technique was tested with a simulated data set generated from various scattering models. Later it was applied to an experimental data set that pro ided, for a w ide range of surface roughness and soil moisture, backscattering coefficients at many incidence angles and frequencies. It was found that, in general, the three-frequency approach produce more accurate results. However, under a favorable combination of frequencies and incidence angles, both approaches give results with a comparable accuracy. There is a potential that soil moisture could be estimated to an accuracy of about 2%. In the mean time the surface roughness parameters could be estimated to an accuracy of better than 10%. C1 INDIAN INST TECHNOL,CSRE,BOMBAY 400076,MAHARASHTRA,INDIA. RP RAO, KS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 17 TC 19 Z9 25 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1993 VL 31 IS 5 BP 1094 EP 1099 DI 10.1109/36.263781 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MP174 UT WOS:A1993MP17400018 ER PT J AU SMITH, JA AF SMITH, JA TI LAI INVERSION USING A BACKPROPAGATION NEURAL-NETWORK TRAINED WITH A MULTIPLE-SCATTERING MODEL SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note ID VEGETATION; INDEX; PARAMETERS AB Standard regression methods applied to canopies within a single homogeneous soil type yield good results for estimating leaf area index (LAI) but perform unacceptably when applied across soil boundaries. In contrast, the neural network reported here generally yielded absolute percentage errors of < 30%. The network was applied, without retraining, to a Landsat TM. RP SMITH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 18 TC 59 Z9 68 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1993 VL 31 IS 5 BP 1102 EP 1106 DI 10.1109/36.263783 PG 5 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA MP174 UT WOS:A1993MP17400020 ER PT J AU DIB, NI GUPTA, M PONCHAK, GE KATEHI, LPB AF DIB, NI GUPTA, M PONCHAK, GE KATEHI, LPB TI CHARACTERIZATION OF ASYMMETRIC COPLANAR WAVE-GUIDE DISCONTINUITIES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID WAVE-GUIDE DISCONTINUITIES AB A general technique to characterize asymmetric coplanar waveguide (CPW) discontinuities with air bridges where both the fundamental coplanar and slotline modes may be excited together is presented. First, the CPW discontinuity without air bridges is analyzed using the space-domain integral equation (SDIE) approach. Second, the parameters (phase, amplitude, and wavelength) of the coplanar and slotline modes are extracted from an amplitude modulated-like standing wave existing in the CPW feeding lines. Then a 2n x 2n generalized scattering matrix of the n-port discontinuity without air bridges is derived which includes the occurring mode conversion. Finally, this generalized scattering matrix is reduced to an n x n matrix by enforcing suitable conditions at the ports which correspond to the excited slotline mode. For the purpose of illustration, the method is applied to a shielded asymmetric short-end CPW shunt stub, the scattering parameters of which are compared with those of a symmetric one. Experiments are performed on both discontinuities and the results are in good agreement with theoretical data. The advantages of using air bridges in CPW circuits as opposed to bond wires are also discussed. C1 TEXAS INSTRUMENTS INC,DALLAS,TX. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DIB, NI (reprint author), UNIV MICHIGAN,RADIAT LAB,ANN ARBOR,MI 48109, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 20 TC 43 Z9 43 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD SEP PY 1993 VL 41 IS 9 BP 1549 EP 1558 DI 10.1109/22.245676 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA MK214 UT WOS:A1993MK21400013 ER PT J AU GABB, TP GAYDA, J BARTOLOTTA, PA CASTELLI, MG AF GABB, TP GAYDA, J BARTOLOTTA, PA CASTELLI, MG TI A REVIEW OF THERMOMECHANICAL FATIGUE DAMAGE MECHANISMS IN 2 TITANIUM AND TITANIUM ALUMINIDE MATRIX COMPOSITES SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article DE THERMOMECHANICAL FATIGUE; COMPOSITES; DAMAGE MECHANISMS; TITANIUM MATRIX COMPOSITES AB Combined load and temperature cycling could limit the durability of continuous fibre reinforced titanium matrix composites. The fatigue life and damage induced by combining load and temperature cycling in several different ways were examined in two representative 0-degrees unidirectional titanium and titanium aluminide matrix composites. Load and temperature were sequentially cycled and simultaneously cycled in thermomechanical fatigue tests. Sequential and simultaneous thermomechanical fatigue tests in which maximum tensile loads occurred at minimum temperature had comparable lives and damage, associated with environment-assisted surface cracking. Sequential and simultaneous thermomechanical fatigue tests in which maximum loads occurred at maximum temperature each had different lives and damage, primarily because of differences in the extent of matrix-relaxation-induced load shedding from the matrix to the fibres. These general results applied to both titanium matrix composite systems. RP GABB, TP (reprint author), NASA,LEWIS RES CTR,MAIL STOP 49-3,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 15 TC 14 Z9 14 U1 1 U2 2 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD SEP PY 1993 VL 15 IS 5 BP 413 EP 422 DI 10.1016/0142-1123(93)90488-C PG 10 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA LX730 UT WOS:A1993LX73000008 ER PT J AU DUNCAN, D GENEROUS, C HUNTER, JF AF DUNCAN, D GENEROUS, C HUNTER, JF TI SUPPORT OF RESEARCH-AND-DEVELOPMENT ACTIVITIES VIA THE INTERNET - NASA ACCESS MECHANISM SO INTERNET RESEARCH-ELECTRONIC NETWORKING APPLICATIONS AND POLICY LA English DT Article AB The growing availability of computer networks and the resources resident on them is changing the environment in which research and development (R&D) activities are performed. The information infrastructure supporting research and engineering activities must adapt, so that they complement and enhance the new networked R&D environment. The National Aeronautics and Space Administration (NASA) has tested a prototype system, the NASA Access Mechanism (NAM), that helps its users exploit Internet-available resources to conduct NASA research and engineering activities. C1 LOGIST MANAGEMENT INST,BETHESDA,MD 20817. UUCOM INC,ALEXANDRIA,VA 22309. NASA,STI PROGRAM,WASHINGTON,DC 20546. NR 8 TC 1 Z9 1 U1 0 U2 0 PU MCB UNIV PRESS LTD PI BRADFORD PA 60/62 TOLLER LANE, BRADFORD, W YORKSHIRE, ENGLAND BD8 9BY SN 1066-2243 J9 INTERNET RES JI Internet Res.-Electron. Netw. Appl. Policy PD FAL PY 1993 VL 3 IS 3 BP 37 EP 46 PG 10 WC Business; Computer Science, Information Systems; Telecommunications SC Business & Economics; Computer Science; Telecommunications GA MF923 UT WOS:A1993MF92300004 ER PT J AU KHMELEVTSEV, SS MAKKORMIK, MP KAUFMAN, YG CHAIKOVSKY, AP SHCHERBAKOV, VN AF KHMELEVTSEV, SS MAKKORMIK, MP KAUFMAN, YG CHAIKOVSKY, AP SHCHERBAKOV, VN TI MEASUREMENTS OF STRATOSPHERIC CLOUD PARAMETERS AT MIDDLE LATITUDES SO IZVESTIYA AKADEMII NAUK FIZIKA ATMOSFERY I OKEANA LA Russian DT Note ID LIDAR C1 NASA,CTR ATMOSPHER RES,WASHINGTON,DC 20546. RP KHMELEVTSEV, SS (reprint author), TAIFUN IND RES ASSOC,MOSCOW,RUSSIA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU MEZHDUNARODNAYA KNIGA PI MOSCOW PA 39 DIMITROVA UL., 113095 MOSCOW, RUSSIA SN 0002-3515 J9 IZV AN FIZ ATMOS OK+ JI Izv. Akad. Nauk. Fiz. Atmos. Okean. Biol. PD SEP-OCT PY 1993 VL 29 IS 5 BP 695 EP 696 PG 2 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA MH065 UT WOS:A1993MH06500019 ER PT J AU OVERFELT, T GLASGOW, T AF OVERFELT, T GLASGOW, T TI THE THERMOPHYSICAL PROPERTIES OF MOLTEN MATERIALS SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Editorial Material C1 NASA,PROC SCI & TECHNOL BRANCH,WASHINGTON,DC 20546. RP OVERFELT, T (reprint author), AUBURN UNIV,AUBURN,AL 36849, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD SEP PY 1993 VL 45 IS 9 BP 13 EP 15 PG 3 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA LW185 UT WOS:A1993LW18500002 ER EF