FN Thomson Reuters Web of Science™ VR 1.0 PT J AU GEHRELS, N TUELLER, J AF GEHRELS, N TUELLER, J TI GAMMA-RAY OBSERVATIONS OF THE GALACTIC-CENTER - REMOVING THE GALACTIC RIDGE CONTRIBUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, CENTER; GAMMA RAYS, OBSERVATIONS ID 6.7-KEV IRON LINE; CENTER REGION; CENTER DIRECTION; ANNIHILATION RADIATION; COS-B; EMISSION; SPECTRUM; COMPONENT; CONTINUUM; ENERGIES AB We combine, for the first time, spectral measurements of the emission from the disk of our Galaxy from keV to GeV energies. This emission is found to have a similar spatial distribution at all energies: a longitude extent of about +/-40-degrees and a latitude extent of less than or similar to 5-degrees. Hence the name ''Galactic ridge'' is appropriate. The energy flux from the ridge is about 10(-7) ergs cm-2 s-1 which gives a luminosity of about 10(38) ergs s-1 assuming an effective distance to the emitting region of 3 kpc. The emission over most of the energy range is dominated by cosmic-ray electrons and protons interacting with interstellar matter. Observations by HEAO A-4 from 1977 to 1979 and by the GRIS balloon instrument in 1988 October give estimates of the ridge spectrum near 100 keV. We subtract this diffuse component from Galactic center observations made by wide-field (approximately 20-degrees) gamma-ray instruments over the past 20 years to determine the emission from point sources in the region. For most of the measurements, the Galactic ridge accounts for between one-third and one-half of the observed flux. This solves the long-standing puzzle of why the wide-field flux is higher than that from the known point sources. Most of the measurements (approximately 80%) have a flux at 100 keV, which, after substraction of our estimate of the diffuse component, is less than or equal to the sum of the normal-state fluxes from the two brightest gamma-ray sources in the region, 1E 1740.7-2942 and GRS 1758-258. These have probably been the dominant gamma-ray point sources in the region since the late 1960s. Subtracting the diffuse emission and the GRS 1758-258 emission from the HEXAGONE observations on 1989 May 22 gives a spectrum that is dominated by lines from positron annihilation. RP GEHRELS, N (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012 NR 61 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 APR 20 PY 1993 VL 407 IS 2 BP 597 EP 605 DI 10.1086/172541 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX399 UT WOS:A1993KX39900015 ER PT J AU SCHLEGEL, EM SERLEMITSOS, PJ JAHODA, K MARSHALL, F PETRE, R BOLDT, E MUSHOTZKY, R SWANK, J SZYMKOWIAK, A SMALE, A WEAVER, K AF SCHLEGEL, EM SERLEMITSOS, PJ JAHODA, K MARSHALL, F PETRE, R BOLDT, E MUSHOTZKY, R SWANK, J SZYMKOWIAK, A SMALE, A WEAVER, K TI A BROAD-BAND X-RAY TELESCOPE SPECTRUM OF THE MASSIVE X-RAY BINARY X-PERSEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EMISSION-LINE, BE; STARS, INDIVIDUAL (X-PERSEI); STARS, NEUTRON; X-RAYS, STARS ID ABSORPTION; PULSARS AB The Broad Band X-Ray Telescope, covering the 0.3-12 keV bandpass with moderate spectral resolution, observed the Be/X-ray binary X Per in 1990 December during the Astro-1 mission on the space shuttle Columbia. The data obtained are the best to date to search for lines and edges. The data are well fitted by a power-law spectrum with a high-energy cutoff. A low value for the high-energy cutoff is found, implying a slightly weaker magnetic field strength for the X-ray pulsar. No iron line is present at approximately 6.5 keV with an equivalent width > 30-40 eV. The BBXRT observation corresponded to the ''off'' state of X Per's recent ''phase change.'' RP SCHLEGEL, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 668,GREENBELT,MD 20771, USA. RI Jahoda, Keith/D-5616-2012; Swank, Jean/F-2693-2012 NR 30 TC 22 Z9 22 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 APR 20 PY 1993 VL 407 IS 2 BP 744 EP 751 DI 10.1086/172556 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX399 UT WOS:A1993KX39900030 ER PT J AU CHOKSHI, A TIELENS, AGGM HOLLENBACH, D AF CHOKSHI, A TIELENS, AGGM HOLLENBACH, D TI DUST COAGULATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; INTERSTELLAR, GRAINS; INTERSTELLAR, MATTER; PLANETS, FORMATION ID CONTACT DEFORMATIONS; SURFACE-ENERGY; SOLAR NEBULA; PARTICLES; GRAINS; ADHESION; SOLIDS; FORCES; EXTINCTION; WAVELENGTH AB Two colliding dust particles can stick, bounce, fragment, melt, or vaporize upon collision, depending on the relative velocity and material parameters. We have theoretically modeled the microphysics of the coagulation process in the collision of two, smooth, elastic, spherical grains. It is shown that sticking will occur when the relative collision velocity is less than a critical velocity, v(cr), which depends on the grain size and the elastic properties and surface energy of the material. Critical relative velocities for coagulation have been evaluated as a function of grain sizes for silicate, icy, and carbonaceous grains. We find that v(cr) varies as R-5/6 where R is the radius of curvature of the colliding particles. Micron-sized quartz particles are able to coagulate at collision velocities of less than congruent-to 10(2) cm s-1, while centimeter-sized grains require velocities below 10(-2) cm s-1. Critical velocities also depend on the material properties (interface energy and elasticity) of the particles; thus small icy grains stick better than small quartz grains (v(cr) is congruent-to 2 x 10(3) cm s-1 vs. 10(2) cm s-1 for 1000 angstrom grains). Realistic interstellar grains may be nonspherical and have core mantle structure and rough surfaces. In addition, plastic flow may also be of importance. The role of these effects in the coagulation process is examined. It is concluded that nonsphericity has only a minor effect. Surface irregularities can limit coagulation considerably. For submicron-sized ice grains this may reduce the critical velocity by a factor congruent-to 3. For silicate and graphite grains this reduction may be much larger. While plastic deformation is very important in the collision of centimeter-sized metal spheres, micron-sized grains have a much higher yield strength, and their sticking will not be affected much. Finally, we briefly examine sticking in the collision of fluffy agglomerates. Coagulation of interstellar grains in dense clouds is briefly discussed. We conclude that efficient coagulation requires coverage of grain cores by an icy grain mantle. Even then, coagulation will lead to only a doubling of the mass of a large (a > 1000 angstrom) grain within a dense core lifetime. Smaller grains can, however, be efficiently removed from the cloud by coagulation. Thus, coagulation can have a dramatic effect on the visible and, particularly, the UV portion of the extinction curve in dense clouds and on their IR spectrum. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CHOKSHI, A (reprint author), CALTECH,IPAC,PASADENA,CA 91125, USA. NR 61 TC 232 Z9 232 U1 1 U2 15 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1993 VL 407 IS 2 BP 806 EP 819 DI 10.1086/172562 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX399 UT WOS:A1993KX39900036 ER PT J AU AJELLO, JM SHEMANSKY, DE AF AJELLO, JM SHEMANSKY, DE TI ELECTRON-EXCITATION OF THE H-2(A (3)SIGMA(G)(+)-]B(3)SIGMA(U)(+)) CONTINUUM IN THE VACUUM ULTRAVIOLET SO ASTROPHYSICAL JOURNAL LA English DT Article DE MOLECULAR PROCESSES ID EMISSION CROSS-SECTION; IMPACT EXCITATION; EXTREME-ULTRAVIOLET; MOLECULAR-HYDROGEN; MEDIUM-RESOLUTION; RYDBERG SERIES; STATE; N-2; DISSOCIATION; TRANSITION AB The electron excitation function for the H-2(a 3SIGMA(g)+ --> b 3SIGMA(u)+) continuum emission has been measured from 11 to 30 eV at 195.0 nm. The emission cross section data have been combined with electron energy loss cross section measurements (Khakoo & Trajmar 1986) to extend the experimental data to 60 eV. The excitation cross section has been estimated by normalizing the data to the electron energy loss cross section at 20 eV and using a model to account for emission from the entire band system (120-500 nm). The spin forbidden excitation of the a 3SIGMA(g)+ state is a major dissociative channel of H-2 at low energy with a peak cross section of 1.7 +/- 0.85 x 10(-17) cm2 at 15.5 eV. The full width at half-maximum (FWHM) of the cross section is 7 eV. The high energy dependence of the cross section has a rapid 1/E3 fall off with electron energy, E, above 50 eV. A modified Born approximation analysis was applied to the data to provide an analytic model. C1 UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089. RP AJELLO, JM (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 32 TC 18 Z9 18 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 APR 20 PY 1993 VL 407 IS 2 BP 820 EP 825 DI 10.1086/172563 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX399 UT WOS:A1993KX39900037 ER PT J AU GAFFNEY, NI LESTER, DF TELESCO, CM AF GAFFNEY, NI LESTER, DF TELESCO, CM TI THE STELLAR VELOCITY DISPERSION IN THE NUCLEUS OF M82 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M82); GALAXIES, KINEMATICS AND DYNAMICS; GALAXIES, NUCLEI; GALAXIES, STARBURST; GALAXIES, STELLAR CONTENT; TECHNIQUES, RADIAL VELOCITIES ID GALACTIC-CENTER; GIANT STARS; STARBURST AB We observed the 2-0 (CO)-C-12 absorption bandhead from integrated starlight from the nuclear bulge of the starburst galaxy M82. The velocity dispersion of the stellar component in the central arcsecond is significantly larger than that of the ionized gas in the same region, implying that the stars and gas represent different kinematic systems. The M/L(K) in this nuclear region is essentially identical to that in our own nuclear bulge, but is much higher than in the starburst disk of M82 at larger radii. This implies that the near-infrared continuum from the central r < 7.5 pc of M82 is dominated by a nuclear bulge population that predates the enveloping starburst. This work is a first step in separating these two distinct populations in the central region of this well-observed starburst galaxy. C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. NR 21 TC 23 Z9 23 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 APR 20 PY 1993 VL 407 IS 2 BP L57 EP L60 DI 10.1086/186805 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX400 UT WOS:A1993KX40000005 ER PT J AU HARTMAN, RC BERTSCH, DL DINGUS, BL FICHTEL, CE HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINER, BG SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF HARTMAN, RC BERTSCH, DL DINGUS, BL FICHTEL, CE HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINER, BG SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI EGRET DETECTION OF HIGH-ENERGY GAMMA-RADIATION FROM THE OVV QUASAR 3C-454.3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL, 3C-454.3 ID EXTRAGALACTIC RADIO-SOURCES; MILLIMETER CONTINUUM; FLUX DENSITIES; COS-B; BLAZARS; SPECTRA; DISTRIBUTIONS; EMISSION; OBJECTS; 3C-279 AB High-energy gamma radiation has been observed from the optically violent variable (OVV) quasar 3C 454.3 (PKS 2251 + 158) by the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Observatory. During the 1992 January-February observation, the emission showed a power-law photon spectrum with an exponent of - 2.18 +/- 0.08. The flux density (E > 100 MeV) was observed to vary within the range (0.4-1.4) x 10(-6) photon cm-2 s-1 on a time scale of less than a week. Lower sensitivity observations during 1992 April and May also detected emission within that range, but with lower statistical significance. An earlier low-sensitivity exposure during 1991 August gave a 95% confidence upper limit of 0.26 x 10(-6) photon cm-2 s-1. The similarity of the gamma-ray emission of 3C 454.3 to that of 3C 279 parallels the similarity of these two objects at lower frequencies. C1 HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,MANSEN EXPTL PHYS LAB,STANFORD,CA 94305. COMP SCI CORP,COMPTON OBSERV,CTR SCI SUPPORT,GREENBELT,MD. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20740. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. RP HARTMAN, RC (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 71 TC 49 Z9 50 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 APR 20 PY 1993 VL 407 IS 2 BP L41 EP L44 DI 10.1086/186801 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX400 UT WOS:A1993KX40000001 ER PT J AU GRYMES, RA SAWYER, C AF GRYMES, RA SAWYER, C TI STUDIES OF SENESCENT CELL BEHAVIOR IN RESPONSE TO PDGF UNDER CONDITIONS OF VARYING STRESS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD APR 20 PY 1993 VL 7 IS 7 BP A1225 EP A1225 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KY848 UT WOS:A1993KY84801083 ER PT J AU LOWE, LL GRYMES, RA AF LOWE, LL GRYMES, RA TI EFFECTS OF HINDLIMB SUSPENSION AND RECOVERY ON MYOGENIC HELIX/LOOP/HELIX GENE-EXPRESSION IN SPECIALIZED ADULT MUSCLE SO FASEB JOURNAL LA English DT Meeting Abstract C1 BENEDICT COLL,COLUMBIA,SC 29204. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD APR 20 PY 1993 VL 7 IS 7 BP A1078 EP A1078 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KY848 UT WOS:A1993KY84800228 ER PT J AU MOORE, KE FITZJARRALD, DR AF MOORE, KE FITZJARRALD, DR TI HOW WELL CAN REGIONAL FLUXES BE DERIVED FROM SMALLER-SCALE ESTIMATES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONVECTIVE BOUNDARY-LAYER; AIRCRAFT MEASUREMENTS; EDDY FLUX; PARAMETERIZATION; BUDGET; LENGTH; MODEL AB Regional surface fluxes are essential lower boundary conditions for large-scale numerical weather and climate models and are the elements of global budgets of important trace gases (Stewart et al., 1989). Surface properties affecting the exchange of heat, moisture, momentum and trace gases vary with length scales from 1 m to hundreds of kilometers. A classical difficulty is that fluxes have been measured directly only at points (towers) or along lines (from aircraft). The process of ''scaling up'' observations limited in space and/or time to represent larger areas has been done by assigning properties to surface types and combining estimated or calculated fluxes using an area-weighted average. Because of nonlinear influences, such as the effect of internal boundary layers, it is not clear that a simple area-weighted average is sufficient to produce the large scale from the small scale, nor is it known how important the uncertainty is to large-scale model outcomes. Simultaneous aircraft and tower data obtained in the relatively simple terrain of the western Alaskan tundra were used to determine the extent to which surface type variation can be related to regional-scale fluxes of heat, moisture, and other properties. Surface type was classified as lake or land with an aircraft-borne infrared thermometer, and flight-level heat and moisture fluxes were related to surface type. The magnitude and variety of sampling errors inherent in eddy correlation flux estimation place limits on how well any flux can be known even in simple geometries. Because of the presence of intrinsic and site-specific uncertainties, regional-scale flux of heat and moisture using aircraft observations in our study area can be reasonably verified to be estimated correctly from linear combinations of smaller-scale estimates only to within a factor of 1.5. Flights at lower levels or in a more comprehensive or systematic pattern might be able to resolve the contributions from individual surface types better, but an experiment to test any scaling-up hypothesis is difficult to devise. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP MOORE, KE (reprint author), SUNY ALBANY,ATMOSPHER SCI RES CTR,ALBANY,NY 12205, USA. NR 30 TC 12 Z9 13 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 APR 20 PY 1993 VL 98 IS D4 BP 7187 EP 7198 DI 10.1029/93JD00029 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KZ339 UT WOS:A1993KZ33900007 ER PT J AU DEMENOCAL, PB RIND, D AF DEMENOCAL, PB RIND, D TI SENSITIVITY OF ASIAN AND AFRICAN CLIMATE TO VARIATIONS IN SEASONAL INSOLATION, GLACIAL ICE COVER, SEA-SURFACE TEMPERATURE, AND ASIAN OROGRAPHY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LATE CENOZOIC UPLIFT; INDIAN-OCEAN; ARABIAN SEA; GENERAL-CIRCULATION; TROPICAL ATLANTIC; NORTH-ATLANTIC; SOUTHERN ASIA; AMERICAN WEST; NUMERICAL EXPERIMENTS; LEVEL FLUCTUATIONS AB The sensitivity of Asian and African climate to prescribed changes in specific high-latitude boundary conditions is examined using the GISS general circulation model (GCM) (8-degrees x 10-degrees). In agreement with previous GCM simulations, summer Asian monsoon winds and rainfall were considerably enhanced by the approximately 8% increase in 11 kyr B.P. insolation; the African monsoon was less responsive to insolation forcing in this model. Increased high-latitude glacial ice cover strengthened winter Asian trade winds and imposed cooler and drier conditions over Arabia and northeastern Africa; summer monsoon winds and associated precipitation were diminished over parts of south Asia. Increased high-latitude ice cover alone had little effect on African climate. Cooler North Atlantic sea surface temperatures (SSTs) enhanced winter trade wind circulation over North Africa, promoted cooler and drier conditions, and reduced the summer monsoon circulation; southern Asian climate was relatively unaffected. Reducing Himalayan and Tibetan elevation to 500 m produced dramatic increases in winter Asian trade wind circulation; the summer monsoon circulation persisted but was weakened considerably. African climate was relatively insensitive to the reduced Asian orography. Many of the model results agree qualitatively with available paleoclimate data. These model results suggest that African and southern Asian climate respond to separate elements of high-latitude climate variability. Specifically, Arabian and northeastern African climate is most sensitive to changes in Fennoscandian ice elevation and albedo, whereas northwestern African climate is most sensitive to changes in the North Atlantic SST field. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP DEMENOCAL, PB (reprint author), COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964, USA. RI demenocal, peter/B-1386-2013 OI demenocal, peter/0000-0002-7191-717X NR 89 TC 94 Z9 99 U1 2 U2 16 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 APR 20 PY 1993 VL 98 IS D4 BP 7265 EP 7287 DI 10.1029/92JD02924 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KZ339 UT WOS:A1993KZ33900014 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H AF BAUSCHLICHER, CW PARTRIDGE, H TI A MRCI PS AND CASSCF STUDY OF THE GROUND-STATE MGO DISSOCIATION-ENERGY - COMMENT SO CHEMICAL PHYSICS LETTERS LA English DT Note ID CORE VALENCE CORRELATION; ELECTRON CORRELATION AB We demonstrate that the ''systematic'' procedure used by Garcia Cuesta, Sanchez de Meras, and Nebot Gil to select a CASSCF active space for MgO is flawed by local minima in the optimization. We show that their correlation treatment underestimates D(e) by 0.2 eV. In addition, the small basis set employed resulted in at least another 0.6 eV underestimation of the D(e). Thus their computed D(e) value is in error by at least 0.8 eV. Our calculations demonstrate that D(e) (to Mg 1S and O 3P) is larger than 2.70 eV and strongly support our previous estimate of 2.80 +/- 0.1 eV. Hence, this value is not in error by 1 eV as asserted by Nebot Gil and co-workers. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 20 TC 13 Z9 13 U1 2 U2 4 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 APR 16 PY 1993 VL 205 IS 4-5 BP 479 EP 483 DI 10.1016/0009-2614(93)87154-U PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KW799 UT WOS:A1993KW79900023 ER PT J AU SMITH, JH AF SMITH, JH TI MODELING MUDDLES - VALIDATION BEYOND THE NUMBERS SO EUROPEAN JOURNAL OF OPERATIONAL RESEARCH LA English DT Article DE MODELING; PHILOSOPHY; MANAGEMENT; DECISION THEORY; SOCIAL ID DECISION; POLICY AB A nonnumerical methodology for estimating the validity of complex models is presented. The validity of such models was estimated qualitatively by identifying the arguments used by the interested parties associated with the model. The patterns of reasoning about the foundations of the model were identified through an analysis of the arguments defending and denying the validity of the model. The approach is illustrated by using the expected utility (EU) model as an example. The analysis revealed contrasting sets of pro-EU and con-EU model arguments. A fundamental difference in the forms of arguments was observed: The pro-EU model used broad arguments covering a variety of issues (top-down) and the con-EU model used specific empirical results to question the fundamental grounding of EU model theory (bottom-up). The approach holds promise for large complex models that are difficult, if not impossible, to validate quantitatively. RP SMITH, JH (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 4 Z9 4 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-2217 J9 EUR J OPER RES JI Eur. J. Oper. Res. PD APR 16 PY 1993 VL 66 IS 2 BP 235 EP 249 DI 10.1016/0377-2217(93)90315-E PG 15 WC Management; Operations Research & Management Science SC Business & Economics; Operations Research & Management Science GA KU061 UT WOS:A1993KU06100006 ER PT J AU YU, AW KRAINAK, MA UNGER, GL AF YU, AW KRAINAK, MA UNGER, GL TI 1047-NM LASER-DIODE MASTER OSCILLATOR ND-YLF POWER-AMPLIFIER LASER SYSTEM SO ELECTRONICS LETTERS LA English DT Article DE OSCILLATORS; SEMICONDUCTOR LASERS AB A master oscillator power amplifier (MOPA) laser transmitter system at 1047 nm wavelength using a semiconductor laser diode and a diode pumped solid state (Nd:YLF) laser (DPSSL) amplifier is described. A small signal gain of 23 dB, a near diffraction limited beam, 1 Gbit/s modulation rates and >0.6 W average power are achieved. This MOPA laser has the advantage of amplifying the modulation signal from the laser diode master oscillator (MO) with no signal degradation. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP YU, AW (reprint author), HUGHES STX CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. NR 5 TC 5 Z9 5 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD APR 15 PY 1993 VL 29 IS 8 BP 678 EP 679 DI 10.1049/el:19930454 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA LB771 UT WOS:A1993LB77100023 ER PT J AU CHAO, Y HALPERN, D PERIGAUD, C AF CHAO, Y HALPERN, D PERIGAUD, C TI SEA-SURFACE HEIGHT VARIABILITY DURING 1986-1988 IN THE TROPICAL PACIFIC-OCEAN SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GEOSAT CROSSOVER ANALYSIS; EL-NINO; ROSSBY WAVES; LEVEL; ALTIMETRY; PARAMETERIZATION; TIDES AB Sea surface height variabilities during 1986-1988 in the tropical Pacific Ocean are described, based upon the Geosat altimeter data and a tropical Pacific Ocean general circulation model (OGCM) simulation forced with observed winds from Florida State University. Both data sets are validated against in situ sea level measurements at 12 selected sea level stations in the equatorial Pacific and were found to be in good agreement with these measurements with correlation coefficients (averaged over the 12 sea level stations in the equatorial Pacific) of 0.69 for Geosat and 0.71 for OGCM. Both the Geosat data and OGCM simulation capture significant amounts of variance of in situ measurements with standard deviations (averaged over the 12 sea level stations) of 7.7 cm for Geosat and 7.1 cm for OGCM as compared with that of 9.8 cm for in situ measurements. The Geosat altimeter data, given their uncertainties, are capable of describing sea surface height variabilities during 1986-1988 in the tropical Pacific Ocean, in particular the seasonal cycle, the 1987 El Nino and 1988 La Nina episodes, and the December 1986 equatorial Kelvin wave event. The OGCM-simulated surface dynamic height is found sensitive to different surface wind products: The standard deviation of the surface dynamic height simulated by the European Center for Medium-Range Weather Forecasting (ECMWF) 10-m wind product is only 5.5 cm. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP UNIV CALIF LOS ANGELES, DEPT ATMOSPHER SCI, 405 HILGARD AVE, LOS ANGELES, CA 90024 USA. NR 55 TC 19 Z9 19 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD APR 15 PY 1993 VL 98 IS C4 BP 6947 EP 6959 DI 10.1029/92JC02984 PG 13 WC Oceanography SC Oceanography GA KY384 UT WOS:A1993KY38400008 ER PT J AU BUSALACCHI, AJ ATLAS, RM HACKERT, EC AF BUSALACCHI, AJ ATLAS, RM HACKERT, EC TI COMPARISON OF SPECIAL SENSOR MICROWAVE IMAGER VECTOR WIND STRESS WITH MODEL-DERIVED AND SUBJECTIVE PRODUCTS FOR THE TROPICAL PACIFIC SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID DIRECT MINIMIZATION; AMBIGUITY REMOVAL; VARIABILITY; OCEAN; ASSIMILATION; SEASAT; SYSTEM; SPACE; TIME AB A new source of vector wind stress data is assessed relative to existing analyses of the surface wind field. The large-scale variability of vector wind stress generated by Atlas et al. (1991) and based on the special sensor microwave imager (SSM/I) remotely sensed observations of surface wind speed is compared with five operational and subjectively analyzed wind products across the tropical Pacific basin for the first year of SSM/I, July 1987 through June 1988. The conventional wind stress data considered are the operational wind products from European Centre for Medium Range Weather Forecasts (ECMWF), National Meteorological Center (NMC), and Fleet Numerical Oceanography Center (FNOC), and the subjective analyses from Florida State University and the University of Hawaii. The spatial and temporal variability of the zonal component, meridional component, and curl of the wind stress are examined relative to their future use in wind-driven ocean model studies of tropical Pacific Ocean circulation. The basin-scale structure of the SSM/I data fall within a range bracketed by ECMWF, the University of Hawaii, NMC, and the Florida State products. The SSM/I data are shown to be most similar to the ECMWF analysis and the subjective analysis of satellite-derived cloud motion wind vectors (SAWIN) performed at the University of Hawaii. The basin-wide mean rms difference between the SSM/I data and these two products is 0.18 dyn cm-2 for tau(x) and 0.10-0.12 dyn cm-2 for tau(y). In order to place these differences within context, the basin-wide mean standard deviation for the temporal variability is found to be 0.23-0.26 dyn cm-2 for tau(x) and 0.15-0.16 dyn cm-2 for tau(y). On regional scales, some of the differences among these products are greater than 0.3 dyn cm-2. The ECMWF and SAWIN analyses are the most similar (basin-wide mean rms difference tau(x) = 0.16 dyn cm-2, tau(y) = 0.11 dyn cm-2) of the 15 possible product versus product comparisons. This may indicate a high weight given to cloud motion wind vectors in the ECMWF analysis for data sparse regions of the tropical Pacific. The wind data from the FNOC analysis forecast system in use in 1987-1988 (and since upgraded) was the most dissimilar wind product. The relatively dense space-time coverage of the SSM/I satellite data (order of 27 observations per 2-degrees x 2.5-degrees grid square every 1.5 days), together with the large-scale similarity with conventional wind products, suggests that the SSM/I-based analysis represents a new source of surface wind information suitable for ocean modeling studies. As a result of the potential demonstrated here, strong consideration should be given to the use of these wind data in forcing ocean circulation modeling studies. Furthermore, the prospects of processing the surface wind speed retrievals from spaceborne passive and active microwave sensors dating back for more than 10 years should be examined. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. HUGHES STX CORP,OCEANS & ICE BRANCH,LANHAM,MD. RP BUSALACCHI, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771, USA. RI Hackert, Eric/A-9915-2011; Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 31 TC 23 Z9 23 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-OCEANS JI J. Geophys. Res.-Oceans PD APR 15 PY 1993 VL 98 IS C4 BP 6961 EP 6977 DI 10.1029/92JC02827 PG 17 WC Oceanography SC Oceanography GA KY384 UT WOS:A1993KY38400009 ER PT J AU BAUSCHLICHER, CW AF BAUSCHLICHER, CW TI ABINITIO STUDY OF FE+-BENZYNE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAS-PHASE; MOLECULAR CALCULATIONS; BASIS SETS; ROW ATOMS; ORBITALS; ENERGIES; IONS AB The interaction of Fe+ with benzyne is studied using the self-consistent-field (SCF), complete active space SCF, and modified-coupled-pair functional levels of theory. The most stable structure is planar, where the Fe+ has inserted into the in-plane pi bond, although the C-C bond distance suggests that some in-plane pi bonding remains. This system is compared with Sc+ bonding to benzyne and other ligands. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 26 TC 12 Z9 12 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD APR 15 PY 1993 VL 97 IS 15 BP 3709 EP 3711 DI 10.1021/j100117a013 PG 3 WC Chemistry, Physical SC Chemistry GA KX596 UT WOS:A1993KX59600013 ER PT J AU PFISTER, L SCOTT, S LOEWENSTEIN, M BOWEN, S LEGG, M AF PFISTER, L SCOTT, S LOEWENSTEIN, M BOWEN, S LEGG, M TI MESOSCALE DISTURBANCES IN THE TROPICAL STRATOSPHERE EXCITED BY CONVECTION - OBSERVATIONS AND EFFECTS ON THE STRATOSPHERIC MOMENTUM BUDGET SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID GENERAL-CIRCULATION MODEL; GRAVITY-WAVES; SEMIANNUAL OSCILLATION; ATMOSPHERE; ARECIBO; ANVILS; LINES AB The importance of the momentum flux of topographically generated mesoscale gravity waves to the extratropical middle atmosphere circulation has been well established for over a decade. Estimates of the zonal forcing due to tropical mesoscale gravity waves, however, are hampered by lack of data on their primarily convective sources. The advent of aircraft measurements over tropical convective systems now makes such estimates possible without the use of ad hoc assumptions about amplitudes and phase speeds. Aircraft measurements from NASA's 1980 Panama and 1987 STEP/Australia Missions show that convectively generated disturbances observed just above the tropopause have horizontal scales comparable to those of the underlying anvils (about 50-100 km) with peak-to-peak isentropic surface variations of about 300-400 m. Satellite imagery of tropical anvil evolution indicates a typical lifetime of about five hours. Assuming that each convective system's impact on the stratosphere can be modeled as a time-dependent ''mountain'' with the preceding spatial and time scales, the excited spectrum of gravity waves can be calculated. A suitable quasilinear wave-mean flow interaction parameterization and satellite-derived cloud area statistics can then be used to evaluate the zonal acceleration as a function of altitude induced by gravity waves from mesoscale convective systems. The results indicate maximum westerly accelerations due to breaking mesoscale gravity waves of almost 0.4 m s-1/day in the upper stratosphere (in the region of the semiannual oscillation) during September, comparable to but probably smaller than the accelerations induced by planetary-scale Kelvin waves. Calculated easterly accelerations due to breaking mesoscale gravity waves in the QBO region below 35 km are smaller, accounting for about 10% of the required zonal acceleration. C1 SAN JOSE STATE UNIV,SAN JOSE,CA 95192. SYNERNET,FREMONT,CA. RP PFISTER, L (reprint author), NASA,AMES RES CTR,SGG 245-3,MOFFETT FIELD,CA 94035, USA. NR 35 TC 78 Z9 80 U1 0 U2 2 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 APR 15 PY 1993 VL 50 IS 8 BP 1058 EP 1075 DI 10.1175/1520-0469(1993)050<1058:MDITTS>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KZ474 UT WOS:A1993KZ47400003 ER PT J AU DEMARIA, M BAIK, JJ KAPLAN, J AF DEMARIA, M BAIK, JJ KAPLAN, J TI UPPER-LEVEL EDDY ANGULAR-MOMENTUM FLUXES AND TROPICAL CYCLONE INTENSITY CHANGE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID HURRICANE INTENSITY; EXTERNAL INFLUENCES AB The eddy flux convergence of relative angular momentum (EFC) at 200 mb was calculated for the named tropical cyclones during the 1989-1991 Atlantic hurricane seasons (371 synoptic times). A period of enhanced EFC within 1500 km of the storm center occurred about every 5 days due to the interaction with upper-level troughs in the midlatitude westerlies or upper-level, cold lows in low latitudes. Twenty-six of the 32 storms had at least one period of enhanced EFC. In about one-third of the cases, the storm intensified just after the period of enhanced EFC. In most of the cases in which the storm did not intensify the vertical shear increased, the storm moved over cold water, or the storm became extratropical just after the period of enhanced EFC. A statistically significant relationship (at the 95% level) was found between the EFC within 600 km of the storm center and the intensity change during the next 48 h. However, this relationship could only be determined using a multiple regression technique that also accounted for the effects of vertical shear and sea surface temperature variations. The EFC was also examined for the ten storms from the 1989-1991 sample that had the largest intensification rates. Six of the ten periods of rapid intensification were associated with enhanced EFC. In the remaining four cases the storms were intensifying rapidly in a low shear environment without any obvious interaction with upper-level troughs. C1 NASA,GODDARD SPACE FLIGHT CTR,SEVERE STORMS BRANCH,GREENBELT,MD 20771. RP DEMARIA, M (reprint author), US DEPT COMMERCE,NOAA,AOML,DIV HURRICANE RES,4301 RICKENBACKER CAUSEWAY,MIAMI,FL 33149, USA. RI DeMaria, Mark/F-5583-2010; Kaplan, John/A-8709-2014 OI Kaplan, John/0000-0002-7253-3039 NR 28 TC 77 Z9 80 U1 0 U2 2 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 APR 15 PY 1993 VL 50 IS 8 BP 1133 EP 1147 DI 10.1175/1520-0469(1993)050<1133:ULEAMF>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KZ474 UT WOS:A1993KZ47400009 ER PT J AU WATERS, JW FROIDEVAUX, L READ, WG MANNEY, GL ELSON, LS FLOWER, DA JARNOT, RF HARWOOD, RS AF WATERS, JW FROIDEVAUX, L READ, WG MANNEY, GL ELSON, LS FLOWER, DA JARNOT, RF HARWOOD, RS TI STRATOSPHERIC CIO AND OZONE FROM THE MICROWAVE LIMB SOUNDER ON THE UPPER-ATMOSPHERE RESEARCH SATELLITE SO NATURE LA English DT Article ID HIGH-ALTITUDE AIRCRAFT; INSITU ER-2 DATA; ANTARCTIC OZONE; POLAR VORTEX; ARCTIC STRATOSPHERE; POTENTIAL VORTICITY; HYDROGEN-CHLORIDE; NITRIC-ACID; DESTRUCTION; DENITRIFICATION AB Concentrations of atmospheric ozone and of CIO (the predominant form of reactive chlorine responsible for stratospheric ozone depletion) are reported for both the Arctic and Antarctic winters of the past 18 months. Chlorine in the lower stratosphere was almost completely converted to chemically reactive forms in both the northern and southern polar winter vortices. This occurred in the south long before the development of the Antarctic ozone hole, suggesting that ozone loss can be masked by influx of ozone-rich air. C1 UNIV EDINBURGH,DEPT METEOROL,EDINBURGH EH9 3JZ,MIDLOTHIAN,SCOTLAND. RP WATERS, JW (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 52 TC 233 Z9 234 U1 0 U2 6 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD APR 15 PY 1993 VL 362 IS 6421 BP 597 EP 602 DI 10.1038/362597a0 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KX438 UT WOS:A1993KX43800036 ER PT J AU SCHUSTER, GL ANDREWS, JR AF SCHUSTER, GL ANDREWS, JR TI COHERENT SUMMATION OF SATURATED ALGAAS AMPLIFIERS SO OPTICS LETTERS LA English DT Article ID POWER-AMPLIFIER; DIODE-LASERS; ARRAYS; BATIO3 AB Coherent summation of the output of two saturated traveling-wave amplifiers, each injected from a common semiconductor laser and all operated cw, has resulted in a single diffraction-limited beam containing 93% of the power originally contained in the two individual amplified beams. The 372 mW of power in a single diffraction-limited lobe is a 1.5-fold enhancement over the power available from a single amplifier. C1 XEROX WEBSTER RES CTR,WEBSTER,NY 14580. RP SCHUSTER, GL (reprint author), NASA,LANGLEY RES CTR,MS-493,HAMPTON,VA 23665, USA. NR 19 TC 8 Z9 8 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 APR 15 PY 1993 VL 18 IS 8 BP 619 EP 621 DI 10.1364/OL.18.000619 PG 3 WC Optics SC Optics GA KX231 UT WOS:A1993KX23100019 PM 19802219 ER PT J AU MASSAROTTI, A QUASHNOCK, JM AF MASSAROTTI, A QUASHNOCK, JM TI DOMAIN-WALLS, WAKES, AND STRUCTURE FORMATION SO PHYSICAL REVIEW D LA English DT Article ID DARK MATTER; EVOLUTION; UNIVERSE; STRINGS AB We consider a cosmological domain wall model where the dark matter interacts nongravitationally with the walls. We find that the dark matter is quickly (as early as z congruent-to 100) swept up in wakes and voids, with the wakes growing with time in a self-similar manner. The dark matter wakes, of order 5h-1 Mpc thick today, tug on the baryons, which also trail behind in wakes of similar thickness. We find that the peculiar motions induced are of the order of a few hundred km/s, coherent on a scale of order 20h-1 Mpc. The baryon overdensities generated by the domain walls are distributed in a geometry similar to that of galaxy superclusters found in recent survey. C1 NASA,CTR FERMILAB ASTROPHYS,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP MASSAROTTI, A (reprint author), UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637, USA. NR 21 TC 4 Z9 4 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 APR 15 PY 1993 VL 47 IS 8 BP 3177 EP 3183 DI 10.1103/PhysRevD.47.3177 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA KY674 UT WOS:A1993KY67400011 ER PT J AU BIRT, MJ HAFLEY, RA WAGNER, JA LISAGOR, WB AF BIRT, MJ HAFLEY, RA WAGNER, JA LISAGOR, WB TI THE FRACTURE-RESISTANCE OF 1420 AND 1421 AL-MG-LI ALLOYS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 NASA,LANGLEY RES CTR,MET MAT BRANCH,HAMPTON,VA 23665. RP BIRT, MJ (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23681, USA. NR 10 TC 3 Z9 8 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 APR 15 PY 1993 VL 28 IS 8 BP 919 EP 923 DI 10.1016/0956-716X(93)90056-X PG 5 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA KR717 UT WOS:A1993KR71700006 ER PT J AU RAVAT, DN HINZE, WJ TAYLOR, PT AF RAVAT, DN HINZE, WJ TAYLOR, PT TI EUROPEAN TECTONIC FEATURES OBSERVED BY MAGSAT SO TECTONOPHYSICS LA English DT Article ID MAGNETIC ANOMALY DATA; EARTHS CRUST; CONTINENTAL-CRUST; HEAT-FLOW; MODEL; FIELD; LITHOSPHERE; MAP; SUSCEPTIBILITY; MINERALOGY AB Regional three-dimensional magnetic models have been developed to characterize the principal European long-wave-length magnetic anomalies represented on the improved MAGSAT magnetic anomaly map of Europe. The magnetic models were constrained by regional variations in geology and geophysical parameters (e.g., geologic boundaries, crustal thickness, heat flow). Because only limited measurements of magnetization are available on lower crustal and uppermost mantle rock samples, our results are useful in constraining and understanding the overall magnetization of these regions. Illustrations of these include: (1) geologic provinces across the Tornquist-Teisseyre tectonic zone; (2) regions of thin crust and high mantle heat flow in south-central Europe; (3) the Kursk-Voronezh magnetic anomaly; and (4) the Ladoga-Gulf of Bothnia zone. The region of the Tornquist-Teisseyre tectonic zone, that marks the boundary between the Fennoscandian-Baltic Shield and metastable Europe, is a major magnetic discontinuity. In south-central Europe, the regional magnetic variations appear to be directly related to variations in the lower crustal thickness and possibly also to heat flow. In addition, the famous Kursk (Ukraine) iron-ore deposit produces a prominent bullseye anomaly at satellite altitude. The Kiruna MAGSAT anomaly is modelled as having a large, deep body as its source. The high P-wave velocity, basal crustal layers encountered in rift (e.g., the Tornquist-Teisseyre tectonic zone itself) and continental arc (e.g., the Ladoga-Gulf of Bothnia zone) settings of Europe appear to be nearly non-magnetic. C1 PURDUE UNIV,DEPT EARTH & ATMOSPHER SCI,W LAFAYETTE,IN 47907. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP RAVAT, DN (reprint author), SO ILLINOIS UNIV,DEPT GEOL,CARBONDALE,IL 62901, USA. RI Taylor, Patrick/D-4707-2012; OI Taylor, Patrick/0000-0002-1212-9384; Ravat, Dhananjay/0000-0003-1962-4422 NR 75 TC 15 Z9 16 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD APR 15 PY 1993 VL 220 IS 1-4 BP 157 EP 173 DI 10.1016/0040-1951(93)90229-D PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KZ831 UT WOS:A1993KZ83100011 ER PT J AU FATHAUER, RW DEJEWSKI, SM GEORGE, T JONES, EW KRABACH, TN KSENDZOV, A AF FATHAUER, RW DEJEWSKI, SM GEORGE, T JONES, EW KRABACH, TN KSENDZOV, A TI INFRARED PHOTODETECTORS WITH TAILORABLE RESPONSE DUE TO RESONANT PLASMON ABSORPTION IN EPITAXIAL SILICIDE PARTICLES EMBEDDED IN SILICON SO APPLIED PHYSICS LETTERS LA English DT Article ID PHOTOEMISSION; SI AB Photodiodes with epitaxial CoSi2 particles embedded in a single-crystal silicon matrix show response in the 1-2 mum range with structure which correlates with absorption peaks due to the surface plasmon resonance of the particles. Aspect ratios (height:diameter) of the particles are accurately controlled by molecular beam epitaxy over a range from 1.4:1 to 1:7, allowing the absorption peaks to be tailored from 1.2 to 2.6 mum, respectively. The particle surface plasmon excitation modifies the photoresponse of the devices and allows this response to be tailored through control of the dimensions of the particles. The photodiodes were tested at 77 K, and 4 of 8 devices tested with an absorption peak at 1.7 mum show dark currents less than 2 nA/cm2 at a reverse bias of 1 V. Detectivities for the same devices at 77 K range from 4 X 10(9) to 8 X 10(9) cm square-root Hz/W. RP FATHAUER, RW (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 9 TC 7 Z9 7 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 12 PY 1993 VL 62 IS 15 BP 1774 EP 1776 DI 10.1063/1.109571 PG 3 WC Physics, Applied SC Physics GA KW464 UT WOS:A1993KW46400023 ER PT J AU KRISHER, TP MORABITO, DD ANDERSON, JD AF KRISHER, TP MORABITO, DD ANDERSON, JD TI THE GALILEO SOLAR REDSHIFT EXPERIMENT SO PHYSICAL REVIEW LETTERS LA English DT Article ID GRAVITATIONAL REDSHIFT; EQUIVALENCE PRINCIPLE AB From the October 1989 launch to the first December 1990 Earth gravity assist, we regularly obtained frequency measurements of the spacecraft clock-an ultrastable crystal oscillator (USO) supplied by Frequency Electronics, Inc. The solar gravitational redshift in frequency was readily detectable, and because of the unique variations in heliocentric distance we could separate the general relativistic effects from the USO's intrinsic frequency variations. We have verified the total frequency shift predicted by general relativity to 0.5% accuracy, and the solar gravitational redshift to 1% accuracy. This is the first test of the solar redshift with an interplanetary spacecraft. RP KRISHER, TP (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 30 Z9 31 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD APR 12 PY 1993 VL 70 IS 15 BP 2213 EP 2216 DI 10.1103/PhysRevLett.70.2213 PG 4 WC Physics, Multidisciplinary SC Physics GA KW756 UT WOS:A1993KW75600004 ER PT J AU WANNIER, PG ANDERSSON, BG FEDERMAN, SR LEWIS, BM VIALA, YP SHAYA, E AF WANNIER, PG ANDERSSON, BG FEDERMAN, SR LEWIS, BM VIALA, YP SHAYA, E TI WARM NEUTRAL HALOS AROUND MOLECULAR CLOUDS .5. OH (1665 AND 1667 MHZ) OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, CLOUDS; ISM, MOLECULES; MOLECULAR PROCESSES ID DENSE INTERSTELLAR CLOUDS; INTER-STELLAR CLOUDS; DISSOCIATIVE RECOMBINATION; LAMBDA-ORIONIS; H-I; DARK CLOUDS; DIFFUSE; RESOLUTION; CO; EQUILIBRIUM AB We have made 10 strip maps of 1665 and 1667 MHz OH emission, traversing the outer boundaries of five molecular clouds. The OH emission is found to be significantly extended relative to CO, implying that OH is to be found in abundance in the partly atomic, partly molecular gas surrounding dense neutral clouds. The fractional OH abundance is calculated using existing H I and CO observations, and detailed source models which include a complete chemistry network and a radiative transfer code. The largest OH abundances are found outside of the CO clouds, especially in those regions thought to be suffused by intense UV radiation. We conclude that the extended OH is formed, not by the exothermic reaction of O with H-3+, but by the endothermic reaction, H+ + O --> H + O+. The increased importance of the endothermic channel, relative to that assumed in earlier work, results from: (1) larger temperatures and (2) a lower efficiency of H-2 production, resulting in a larger H I column density. This is consistent with, and is in fact predicted by, earlier models based on H I and CO observations alone. C1 ARECIBO OBSERV, ARECIBO, PR 00613 USA. OBSERV PARIS, SECT MEUDON, DEMIRM, F-92195 MEUDON, FRANCE. UNIV TOLEDO, DEPT PHYS, TOLEDO, OH 43606 USA. UNIV MARYLAND, DEPT PHYS & ASTRON, COLL PK, MD 20742 USA. RP JET PROP LAB, PASADENA, CA 91109 USA. NR 57 TC 22 Z9 22 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 APR 10 PY 1993 VL 407 IS 1 BP 163 EP 174 DI 10.1086/172502 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KV285 UT WOS:A1993KV28500017 ER PT J AU MacLow, MM NORMAN, ML AF MacLow, MM NORMAN, ML TI NONLINEAR GROWTH OF DYNAMIC OVERSTABILITIES IN BLAST WAVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; SUPERNOVA REMNANTS; SHOCK WAVES; INSTABILITIES ID RAYLEIGH-TAYLOR INSTABILITY; SHOCK-WAVES AB Blast waves have been shown by Vishniac to be subject to an oscillating instability, with growth occurring when the blast wave is thin enough. The nonlinear development of this overstability has not yet been determined. We directly model the overstability using the numerical gas dynamics code ZEUS-2D. We confirm the linear analysis by perturbing a blast wave with a low-amplitude eigenfunction of the overstability. We then increase the amplitude of the perturbations to determine the nonlinear behavior of the overstability. We find that the overstability saturates due to weak transverse shocks in the shell. Transverse velocities in the dense shell reach the postshock sound speed, and high-density regions with sizes of order the shell thickness form. Transverse oscillations continue even after saturation. This confirms and explains the damping of the overstability experimentally discovered by Grun et al. Our results support the short time scale for gravitational instability of the shell proposed by Vishniac. Observations of thin, radiatively cooled shells in supernova remnants may directly show the effects of the overstability. C1 UNIV ILLINOIS, DEPT ASTRON, URBANA, IL 61801 USA. NASA, AMES RES CTR, DIV SPACE SCI, MOFFETT FIELD, CA 94035 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. NATL CTR SUPERCOMP APPLICAT, URBANA, IL 61801 USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 29 TC 88 Z9 88 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 APR 10 PY 1993 VL 407 IS 1 BP 207 EP 218 DI 10.1086/172506 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KV285 UT WOS:A1993KV28500021 ER PT J AU PRAVDO, SH ANGELINI, L AF PRAVDO, SH ANGELINI, L TI X-RAYS FROM EMISSION-LINE STARS IN THE HERBIG-HARO-1 REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EMISSION-LINE, BE; STARS, PRE-MAIN-SEQUENCE; X-RAYS, STARS ID HERBIG-HARO OBJECTS; T-TAURI STARS; INFRARED OBSERVATIONS; HIGH-RESOLUTION; NEBULA; HH-1; SPECTROSCOPY; ABSORPTION; ORION; DUST AB We have observed the region in Orion containing Herbig-Haro 1 as well as a number of young, active stars. This observation shows a similar X-ray morphology to that in the first X-ray imaging observation about 10 years ago. The ROSAT High Resolution Instrument with its approximately arcsecond spatial resolution allows us in most cases to make definite optical identifications of the 0.1-2.4 keV X-ray sources. New identifications with emission-line stars are made, and prior identifications using lower resolution observations are confirmed or corrected. The X-ray emission previously detected from the vicinity of HH-1 is not associated with HH-1 but with a known T Tauri star. The observed relationships among X-ray, optical line, and infrared excess emission do not simply fall into the suggested classifications for T Tauri or T Tauri-like stars. This could be an indication of another X-ray emission region such as accretion disks that add to the emission from the stellar atmospheres. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP PRAVDO, SH (reprint author), JET PROP LAB,MAIL STOP 168-222,PASADENA,CA 91109, USA. NR 41 TC 8 Z9 8 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 APR 10 PY 1993 VL 407 IS 1 BP 232 EP & DI 10.1086/172508 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KV285 UT WOS:A1993KV28500023 ER PT J AU PERCIVAL, JW BIGGS, JD DOLAN, JF ROBINSON, EL TAYLOR, MJ BLESS, RC ELLIOT, JL NELSON, MJ RAMSEYER, TF VANCITTERS, GW ZHANG, E AF PERCIVAL, JW BIGGS, JD DOLAN, JF ROBINSON, EL TAYLOR, MJ BLESS, RC ELLIOT, JL NELSON, MJ RAMSEYER, TF VANCITTERS, GW ZHANG, E TI THE CRAB PULSAR IN THE VISIBLE AND ULTRAVIOLET WITH 20 MICROSECOND EFFECTIVE TIME RESOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE PULSARS, INDIVIDUAL (CRAB PULSAR); TECHNIQUES, PHOTOMETRIC; ULTRAVIOLET, STARS ID EMISSION; STARS; VELA AB The Crab pulsar (PSR 0531 + 21) was observed with the High Speed Photometer on the Hubble Space Telescope in the visible in 1991 October and in the UV in 1992 January. The time resolution of the instrument was 10.74 mus; the effective time resolution of the light curves folded modulo the pulsar period was 21.5 mus. Contemporaneous UVBR observations were obtained from McDonald Observatory in January. The visible and UV light curves observed from HST are similar, but the main pulse is slightly narrower in the UV. The separation in phase between the main pulse and the interpulse is also 0.7% smaller in the UV than in the visible. The main pulse arrival time is the same in the UV as in the visible and radio to within the accuracy of the establishment of the spacecraft clock, +/- 1.05 ms (+/- 0.031 in pulsar phase). The peak of the main pulse is resolved in time. Corrected for reddening, the intensity spectral index of the Crab pulsar from 1680 to 7400 angstrom is alpha = 0.11 +/- 0.13. The pulsed flux has an intensity less than 0.9% of the peak flux (2 sigma upper limit) just before the onset of the main pulse. The variations in intensity of individual main and secondary pulses are uncorrelated, even within the same rotational period. These results are consistent with the predictions of the standard model of pulsar emission. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. MIT,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02139. NATL SCI FDN,DIV ASTRON SCI,WASHINGTON,DC 20550. USN ACAD,DEPT AEROSP ENGN,ANNAPOLIS,MD 21402. RP PERCIVAL, JW (reprint author), UNIV WISCONSIN,SPACE ASTRON LAB,MADISON,WI 53706, USA. NR 24 TC 83 Z9 83 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 APR 10 PY 1993 VL 407 IS 1 BP 276 EP & DI 10.1086/172512 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KV285 UT WOS:A1993KV28500027 ER PT J AU BURLAGA, LF PERKO, J PIRRAGLIA, J AF BURLAGA, LF PERKO, J PIRRAGLIA, J TI COSMIC-RAY MODULATION, MERGED INTERACTION REGIONS, AND MULTIFRACTALS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; COSMIC RAYS; MAGNETIC FIELDS ID HELIOSPHERIC CURRENT SHEET; OUTER HELIOSPHERE; SOLAR MODULATION; MAGNETIC-FIELD; RADIAL GRADIENTS; PARTICLE DRIFT; TRANSPORT; CYCLE; FLUCTUATIONS; PROPAGATION AB We have analyzed observations of the cosmic rays > 70 MeV per nucleon and the magnetic field strength made by instruments on Voyager 2 near the ecliptic from 1983.0 to 1989.6 with the aim of better understanding the relation between the cosmic-ray intensity variations and the magnetic field strength variations with time. Using the model of Perko & Burlaga with the observed magnetic field strengths as input, we show the following. The basic large-scale structure of the cosmic-ray intensity profile from 1983.0 to 1989.6 is determined by the relatively small number of large merged interaction regions (MIRs) with B/B(P) > 3.5, rather than by the cumulative effect of many small MIRs. MIRs of intermediate strength 2.0 < B/B(P) < 3.5 produce some large perturbations corresponding to certain events that have been noted in the literature and other fluctuations on short and intermediate time scales. Small MIRs, viz. regions with 1 < B/B(P) < 2, produce minor perturbations in the cosmic-ray intensity profile on short time scales. The distributions of the hour averages of the magnetic field intensity have exponential tails, with e-folding parameters that vary with the phase of the solar cycle. The large-scale magnetic field strength fluctuations from 1983.0 to 1989.6 have a multifractal structure over the range of scales from 16 hr to 256 hr. The large-scale magnetic field strength fluctuations have multifractal structure with different parameters during each of the following intervals: (1) 1983.0-1985.0, when solar activity was declining; (2) 1985.0-1987.5, when the solar activity was low; and (3) 1987.5-1989.6, when the solar activity was increasing. We have determined the multifractal spectra from each of the three intervals, and we reconstructed realistic magnetic field strength profiles for each of these intervals from the multifractal spectra using a variation of the two-scale binomial model described by Pirraglia. These results point to a way to construct realistic global statistical models of the large-scale magnetic field strength fluctuations in the outer heliosphere, and their effects on cosmic ray propagation. C1 UNIV DELAWARE, BARTOL RES INST, NEWARK, DE 19716 USA. RP NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, CODE 692, GREENBELT, MD 20771 USA. NR 66 TC 49 Z9 49 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 APR 10 PY 1993 VL 407 IS 1 BP 347 EP 358 DI 10.1086/172517 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KV285 UT WOS:A1993KV28500032 ER PT J AU HWANG, SM RABINOWITZ, MJ GARDINER, WC AF HWANG, SM RABINOWITZ, MJ GARDINER, WC TI RECOMBINATION OF METHYL RADICALS AT HIGH-TEMPERATURES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID RATE-CONSTANT; REACTION CH3+CH3->C2H6; CHEMICAL-KINETICS; SHOCK-TUBE; PRESSURE; COMBUSTION; DEPENDENCE; CH3 AB The recombination of methyl radicals generated by pyrolysis of azomethane-Ar mixtures and detected by coincidence absorption of the zinc 213.9 nm atomic line was studied in incident shock waves at temperatures from 1300 to 1700 K and densities from 2 x 10(-6) to 9 x 10(-6) mol/cm3. A simultaneous regression analysis based upon large factorial design computer simulations was used to solve the inverse problem of parameter identification and to determine optimal values of rate coefficient and other parameters. The rate coefficient found for the recombination channel is in agreement with a previously published nine-parameter weak collision model. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. UNIV TEXAS,DEPT CHEM,AUSTIN,TX 78712. RP HWANG, SM (reprint author), UNIV TOLEDO,DEPT CHEM ENGN,TOLEDO,OH 43606, USA. NR 34 TC 42 Z9 42 U1 0 U2 6 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 APR 9 PY 1993 VL 205 IS 2-3 BP 157 EP 162 DI 10.1016/0009-2614(93)89221-3 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KV519 UT WOS:A1993KV51900006 ER PT J AU NEREM, RS CHAO, BF AU, AY CHAN, JC KLOSKO, SM PAVLIS, NK WILLIAMSON, RG AF NEREM, RS CHAO, BF AU, AY CHAN, JC KLOSKO, SM PAVLIS, NK WILLIAMSON, RG TI TEMPORAL VARIATIONS OF THE EARTHS GRAVITATIONAL-FIELD FROM SATELLITE LASER RANGING TO LAGEOS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ROTATION; DEFORMATION; HARMONICS; MOTION AB We have estimated monthly values of the J2 and J3 Earth gravitational coefficients using LAGEOS satellite laser ranging (SLR) data collected between 1980 and 1989. For the same time period, we have also computed corresponding estimates of the variations in these coefficients caused by atmospheric mass redistribution using surface atmospheric pressure estimates from the European Center for Medium Range Weather Forecasts (ECMWF). These data were processed both with and without a correction for the ''inverted barometer effect,'' the ocean's isostatic response to atmospheric loading. While the estimated zonal harmonics in the orbit analysis accommodate gravitational changes at a reduced level arising from all other higher degree zonal effects, the LAGEOS and atmospheric time series for J2 compare quite well and it appears that the non-secular variation in J2 can be largely attributed to the redistribution of the atmospheric mass. While the observed changes in the 'effective'' J3 parameters are not well predicted by the third degree zonal harmonic changes in the atmosphere, both odd zonal time series display strong seasonality. The LAGEOS J3 estimates are very sensitive to as yet unmodeled forces acting on the satellite and these effects must be better understood before determining the dominant geophysical signals contributing to the estimate of this time series. RP NEREM, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 18 TC 49 Z9 56 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 APR 9 PY 1993 VL 20 IS 7 BP 595 EP 598 DI 10.1029/93GL00169 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KY310 UT WOS:A1993KY31000014 ER PT J AU NEREM, RS BILLS, BG MCNAMEE, JB AF NEREM, RS BILLS, BG MCNAMEE, JB TI A HIGH-RESOLUTION GRAVITY MODEL FOR VENUS - GVM-1 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HARMONIC-ANALYSIS; TOPOGRAPHY AB A spherical harmonic model of the gravitational field of Venus complete to degree and order 50 has been developed using the S-band Doppler tracking data of the Pioneer Venus Orbiter (PVO) collected between 1979 and 1982. The short wavelengths of this model could only be resolved near the PVO periapse location (approximately 14-degrees-N latitude), therefore a priori constraints were applied to the model to bias poorly observed coefficients towards zero. The resulting model has a half-wavelength resolution of 400 km near the PVO periapse location, but the resolution degrades to greater than 1000 km near the poles. This gravity model correlates well with a degree 50 spherical harmonic expansion of the Venus topography derived from a combination of Magellan and PVO data. New tracking data from Magellan's gravity mission should provide some improvement to this model, although a complete model of the Venusian gravity field will depend on tracking of Magellan after the circularization of it's orbit using aerobraking. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. JET PROP LAB,PASADENA,CA 91109. RP NEREM, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,CODE 921,GREENBELT,MD 20771, USA. RI Bills, Bruce/C-1156-2008 NR 19 TC 23 Z9 24 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 APR 9 PY 1993 VL 20 IS 7 BP 599 EP 602 DI 10.1029/92GL02851 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KY310 UT WOS:A1993KY31000015 ER PT J AU ARGUS, DF LYZENGA, GA AF ARGUS, DF LYZENGA, GA TI CONSTRAINTS ON INTERSEISMIC DEFORMATION AT JAPAN TRENCH FROM VLBI DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DISPLACEMENT; SEISMICITY; RELEASE; FAULTS; ZONE; ARC AB We use space geodetic data from very long baseline interferometry to estimate the velocity relative to the plates of two sites near Tokyo. We use these results and elastic models of interseismic deformation to put constraints on the slip rate along the main thrust at the Japan subduction zone. The sites at Kashima and Tsukuba lie 150 and 200 km, respectively, west of the axis of the Japan trench, where the Pacific plate subducts at approximately 97 mm/yr. The two sites also lie 160 km from the Sagami trough, where the Philippine plate subducts obliquely at approximately 32 mm/yr. Relative to the North American plate Kashima moves at 13+/-2 mm/yr toward N46+/-4-degrees-W and Tsukuba moves at 9+/-3 mm/yr toward N42+/-19-degrees-W. These observed velocities are intermediate between the velocities of the Pacific and Eurasian plates, consistent with the overriding plate being the Eurasian plate. In this case the observed velocities reflect the sum of (a) permanent west-northwest shortening in northern Honshu and (b) elastic deformation due to locking the main thrust fault at Japan trench. But the observed velocities are also part way between the velocities of the Philippine and North American plates, and they may result from Philippine-North American deformation. Nevertheless, the observed velocities limit the locked segment of the main thrust at Japan trench to no more than 27 km vertically or 100 km along dip. Thus, the main Pacific plate thrust fault is not strongly coupled, part of it must creep, and it probably does not generate great earthquakes. C1 HARVEY MUDD COLL,DEPT PHYS,CLAREMONT,CA 91711. RP ARGUS, DF (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Argus, Donald/F-7704-2011 NR 17 TC 7 Z9 7 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 APR 9 PY 1993 VL 20 IS 7 BP 611 EP 614 DI 10.1029/93GL00427 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KY310 UT WOS:A1993KY31000018 ER PT J AU MARDER Sr GORMAN, CB TIEMANN, BG CHENG, LT AF MARDER, SR GORMAN, CB TIEMANN, BG CHENG, LT TI STRONGER ACCEPTORS CAN DIMINISH NONLINEAR OPTICAL-RESPONSE IN SIMPLE DONOR-ACCEPTOR POLYENES SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Note ID CONJUGATED ORGANIC-MOLECULES; SEMIEMPIRICAL METHODS; CRYSTAL-STRUCTURE; HYPERPOLARIZABILITIES; LENGTH; OPTIMIZATION; PARAMETERS; STATE C1 CALTECH, BECKMAN INST, CTR MOLEC MAT RESOURCE, PASADENA, CA 91125 USA. DUPONT CO, DEPT CENT RES & DEV, EXPTL STN, WILMINGTON, DE 19880 USA. RP MARDER Sr (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Gorman, Christopher/A-3463-2008 OI Gorman, Christopher/0000-0001-7367-2965 NR 31 TC 190 Z9 192 U1 3 U2 12 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD APR 7 PY 1993 VL 115 IS 7 BP 3006 EP 3007 DI 10.1021/ja00060a071 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA KW980 UT WOS:A1993KW98000071 ER PT J AU SIEG, RM ALTEROVITZ, SA CROKE, ET HARRELL, MJ AF SIEG, RM ALTEROVITZ, SA CROKE, ET HARRELL, MJ TI ELLIPSOMETRIC STUDY OF SI0.5GE0.5/SI STRAINED-LAYER SUPERLATTICES SO APPLIED PHYSICS LETTERS LA English DT Article AB We present an ellipsometric study of two Si0.5Ge0.5/Si strained-layer superlattices grown by MBE at low temperature (500-degrees-C), and compare our results with x-ray diffraction (XRD) estimates. Excellent agreement is obtained between target values, XRD, and ellipsometry when one of two available SixGe1-x databases is used. We show that ellipsometry can be used to nondestructively determine the number of superlattice periods, layer thickness, SixGe1-x composition, and oxide thickness without resorting to additional sources of information. We also note that we do not observe any strain effect on the E1 critical point. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. HUGHES RES LABS,MALIBU,CA 90265. RP SIEG, RM (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 17 TC 10 Z9 10 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 5 PY 1993 VL 62 IS 14 BP 1626 EP 1628 DI 10.1063/1.108607 PG 3 WC Physics, Applied SC Physics GA KV995 UT WOS:A1993KV99500017 ER PT J AU ALLAMANDOLA, LJ SANDFORD, SA TIELENS, AGGM HERBST, TM AF ALLAMANDOLA, LJ SANDFORD, SA TIELENS, AGGM HERBST, TM TI DIAMONDS IN DENSE MOLECULAR CLOUDS - A CHALLENGE TO THE STANDARD INTERSTELLAR-MEDIUM PARADIGM SO SCIENCE LA English DT Article ID METEORITES; EVOLUTION; ORIGIN; DUST AB Observations of a newly discovered infrared C-H stretching band indicate that interstellar diamond-like material appears to be characteristic of dense clouds. In sharp contrast. the spectral signature of dust in the diffuse interstellar medium is dominated by -CH2- and -CH3 groups. This dichotomy in the aliphatic organic component between the dense and diffuse media challenges standard assumptions about the processes occurring in, and interactions between, these two media. The ubiquity of this interstellar diamond-like material rules out models for meteoritic diamond formation in unusual circumstellar environments and implies that the formation of the diamond-like material is associated with common interstellar processes or stellar types. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP ALLAMANDOLA, LJ (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MT VIEW,CA 94035, USA. NR 29 TC 73 Z9 73 U1 0 U2 3 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 2 PY 1993 VL 260 IS 5104 BP 64 EP 66 DI 10.1126/science.11538059 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KV423 UT WOS:A1993KV42300025 PM 11538059 ER PT J AU BRAND, VD LOUNGE, JM WALKER, DM AF BRAND, VD LOUNGE, JM WALKER, DM TI ASSEMBLING A SPACE STATION IN ORBIT SO ACTA ASTRONAUTICA LA English DT Article AB A detailed description is given for the future Space Station Freedom as well as the problems, and presently planned procedures for assembling it in orbit. New technologies to be applied are briefly mentioned. RP BRAND, VD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, 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 APR PY 1993 VL 29 IS 4 BP 317 EP 323 DI 10.1016/0094-5765(93)90145-M PG 7 WC Engineering, Aerospace SC Engineering GA KZ255 UT WOS:A1993KZ25500009 ER PT J AU BAKER, DN KLIMAS, AJ PULKKINEN, TI MCPHERRON, RL AF BAKER, DN KLIMAS, AJ PULKKINEN, TI MCPHERRON, RL TI REEXAMINATION OF DRIVEN AND UNLOADING ASPECTS OF MAGNETOSPHERIC SUBSTORMS SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID GEOMAGNETIC-ACTIVITY AB Magnetospheric substorms represent a global interaction between the solar wind, the magnetosphere, and the ionosphere. Energy extracted from the solar wind is episodically stored in the magnetosphere, with a large fraction of the energy often being in the form of excess magnetic flux in the magnetotail lobes. This stored energy is then explosively dissipated in the near-Earth, nightside region at substorm onset. It is generally accepted, therefore, that substorms consist of both directly driven and loading-unloading processes. However, a recent study has presented results in which nearly 90% of the auroral electrojet (AE) variation was directly predictable from the solar wind variations alone. This would suggest that only a small residual in the AE variability is due to internal magnetospheric dynamics. We consider nonlinear dynamical models of the global solar wind-magnetosphere interaction. In the present work we use the observed, highly variable solar wind electric field (VB(S)) to drive the Faraday loop analogue model. We find that it is critically important to include magnetotail unloading in the model in order to replicate the main features of geomagnetic activity: With just the driven response in the model, we do not obtain realistic time behavior of the model AL index. C1 FINNISH METEOROL INST, HELSINKI, FINLAND. UNIV CALIF LOS ANGELES, IGPP, LOS ANGELES, CA 90024 USA. RP BAKER, DN (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Pulkkinen, Tuija/D-8403-2012 OI Pulkkinen, Tuija/0000-0002-6317-381X NR 10 TC 3 Z9 3 U1 0 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 APR PY 1993 VL 13 IS 4 BP 75 EP 83 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200013 ER PT J AU PULKKINEN, TI BAKER, DN MITCHELL, DG MCPHERRON, RL HUANG, CY FRANK, LA AF PULKKINEN, TI BAKER, DN MITCHELL, DG MCPHERRON, RL HUANG, CY FRANK, LA TI GLOBAL AND LOCAL ESTIMATES OF THE CURRENT SHEET THICKNESS - CDAW-6 SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID SUBSTORM GROWTH-PHASE; TAIL CURRENT SHEET; PLASMA SHEET; MAGNETOTAIL; MODEL; RECONNECTION; EXPANSION; ONSET; EVENT AB The growth phase development of the near-Earth magnetotail configuration during the CDAW-6 substorm (22 March 1979,1054 UT) is studied using two complementary methods. The global magnetic field configuration is modeled using data from two suitably located spacecraft and temporally evolving variations of the Tsyganenko magnetic field model. These results are compared with a local calculation of the current sheet location and thickness previously carried out by McPherron et al. /1/. The good agreement between the two methods provides a positive test for the accuracy of the global model. Both models indicate the formation of an extremely thin current sheet during the substorm growth phase. The plasma electron data together with the rate of pitch-angle scattering estimated from the global field model suggest that the onset may be initiated by the chaotization of electrons and consequent growth of the tearing instability. C1 NASA, GODDARD SPACE FLIGHT CTR, GSFC, GREENBELT, MD 20771 USA. JHU, APL, LAUREL, MD 20723 USA. UNIV CALIF LOS ANGELES, IGPP, LOS ANGELES, CA 90024 USA. UNIV IOWA, IOWA CITY, IA 52242 USA. RP PULKKINEN, TI (reprint author), FINNISH METEOROL INST, BOX 503, SF-00101 HELSINKI, FINLAND. RI Pulkkinen, Tuija/D-8403-2012 OI Pulkkinen, Tuija/0000-0002-6317-381X NR 21 TC 0 Z9 0 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 APR PY 1993 VL 13 IS 4 BP 85 EP 91 PG 7 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200014 ER PT J AU MORELLI, JP BUNTING, RJ COWLEY, SWH FARRUGIA, CJ FREEMAN, MP FRIISCHRISTENSEN, E JONES, GOL LESTER, M LEWIS, RV LUHR, H ORR, D PINNOCK, M REEVES, GD WILLIAMS, PJS YEOMAN, TK AF MORELLI, JP BUNTING, RJ COWLEY, SWH FARRUGIA, CJ FREEMAN, MP FRIISCHRISTENSEN, E JONES, GOL LESTER, M LEWIS, RV LUHR, H ORR, D PINNOCK, M REEVES, GD WILLIAMS, PJS YEOMAN, TK TI PLASMA-FLOW BURSTS IN THE NIGHTSIDE AURORAL-ZONE IONOSPHERE AND THEIR RELATION TO GEOMAGNETIC-ACTIVITY SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID EISCAT AB We examine the nature of flows in the nightside auroral zone ionosphere and their relationship with concurrent geomagnetic activity by studying a three-hour interval of ground-based radar, magnetometer array and spacecraft data. We find that the flows are bursty in nature, a characteristic previously reported, and that the bursts are related to a series of substorm electrojet intensifications initiated in the pre-midnight sector. C1 NASA, GODDARD SPACE FLIGHT CTR, GODDARD SFC CODE 692, GREENBELT, MD 20771 USA. UNIV LEICESTER, DEPT PHYS, LEICESTER LE1 7RH, ENGLAND. DANISH METEOROL INST, DK-2100 COPENHAGEN, DENMARK. UCW, DEPT PHYS, ABERYSTWYTH SY23 3BZ, DYFED, WALES. LANL, LOS ALAMOS, NM 87545 USA. TECH UNIV BRAUNSCHWEIG, W-3300 BRAUNSCHWEIG, GERMANY. UNIV YORK, DEPT PHYS, YORK YO1 5DD, N YORKSHIRE, ENGLAND. BRITISH ANTARCTIC SURVEY, CAMBRIDGE CB3 0ET, ENGLAND. RP MORELLI, JP (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. RI Yeoman, Timothy/L-9105-2014 OI Yeoman, Timothy/0000-0002-8434-4825 NR 7 TC 3 Z9 3 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 APR PY 1993 VL 13 IS 4 BP 135 EP 138 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200022 ER PT J AU ARNOLDY, R LYNCH, K KINTNER, P VAGO, J POLLOCK, CJ MOORE, TE AF ARNOLDY, R LYNCH, K KINTNER, P VAGO, J POLLOCK, CJ MOORE, TE TI TRANSVERSE ION-ACCELERATION AND AURORAL ELECTRON-PRECIPITATION SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID NOISE; BEAM AB High time resolution electron and ion measurements aboard a sounding rocket reaching an altitude of 1100 km have revealed hundreds of localized regions of intense lower hybrid waves and transversely accelerated H+ and O+ ions (TAI). From the nature of the correlations between the TAI and the waves it is concluded that the waves are accelerating the ions within localized regions of transverse scale length of 50 to 100 m and that these acceleration regions are thin filaments with lengths the order of a few hundred kilometers. The TAI fluxes are adequate to explain ISIS satellite observations of TAI. The TAI occur during periods of field-aligned electron precipitation. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. CORNELL UNIV, ITHACA, NY 14853 USA. RP ARNOLDY, R (reprint author), UNIV NEW HAMPSHIRE, CTR SPACE SCI, DURHAM, NH 03824 USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 16 TC 0 Z9 0 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 APR PY 1993 VL 13 IS 4 BP 143 EP 148 PG 6 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200024 ER PT J AU MCPHERRON, RL ANGELOPOULOS, V BAKER, DN HONES, EW AF MCPHERRON, RL ANGELOPOULOS, V BAKER, DN HONES, EW TI IS THERE A NEAR-EARTH NEUTRAL LINE SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID SUBSTORM EXPANSION PHASE; SOLAR-WIND PARAMETERS; SHEET BOUNDARY-LAYER; LOBE MAGNETIC-FIELD; PLASMA SHEET; MAGNETOSPHERIC SUBSTORMS; GEOMAGNETIC-ACTIVITY; MULTIPLE-SATELLITE; MAGNETOTAIL; DISRUPTION AB High correlations between southward turnings of the IMF, increases of open flux in the tail lobes, and magnetic activity confirm dayside magnetic reconnection plays a fundamental role in magnetospheric substorms. The absence of a time delay between expansion phase onset and the decrease in tail lobe flux suggest that nightside reconnection is involved in the expansion. At 20-30 R(e), the disappearance of the center of the plasma sheet and the appearance of tailward flows threaded with southward fields strongly suggest reconnection occurs earthward of this distance. Recent AMPTE/CCE and DMSP observations suggest that current disruption begins near synchronous orbit on closed field lines and expands tailward. Auroral images from the VIKING spacecraft support this. Reports of a lack of correlation between plasma and field changes at the ISEE spacecraft and onsets has led some researchers to reject the hypothesis that reconnection is the cause of the expansion. To counter these reports we present magnetic field and plasma data from substorms observed on an outbound pass by ISEE-2. We show that the tail field responds in the manner predicted by the near-earth neutral line (NENL) model, growing in strength and tilting earthward in the growth phase, and decreasing and tilting upward in the expansion phase. Near the earth the plasma sheet gradually thins in the growth phase while further away it suddenly thins at expansion onset. In the expansion phase the plasma sheet rapidly recovers close to the earth, but its recovery is delayed until the substorm recovery phase further from the earth. We explain many of the recent reports of disagreement between the NENL model and observations by a combination of factors. These include: Large changes in the location of a spacecraft relative to the neutral sheet as the size of the magnetosphere changes with dynamic pressure, or as the central meridian and latitude of substorm onset change due to inherent variability, Differences between the outbound and inbound portions of the ISEE orbit; Change in shape of successive orbits in GSM coordinates. Most important is multiple substorm onsets. Successive intensifications cause quite different effects at a spacecraft as the disturbance moves relative to the spacecraft. We conclude that rather than one x-line, there are probably multiple, localized pairs of x- and o-type lines formed in the near-earth plasma sheet during the substorm expansion. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. RP MCPHERRON, RL (reprint author), UNIV CALIF LOS ANGELES, INST GEOPHYS & PLANETARY PHYS, LOS ANGELES, CA 90024 USA. NR 43 TC 3 Z9 3 U1 0 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 APR PY 1993 VL 13 IS 4 BP 173 EP 186 PG 14 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200028 ER PT J AU NAKAMURA, R BAKER, DN FAIRFIELD, DH MITCHELL, DG MCPHERRON, RL AF NAKAMURA, R BAKER, DN FAIRFIELD, DH MITCHELL, DG MCPHERRON, RL TI PLASMA-FLOW AND MAGNETIC-FIELD CHARACTERISTICS IN THE MIDTAIL REGION SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID EQUATORIAL MAGNETOTAIL; RECONNECTION; SUBSTORM; SHEET AB Statistical occurrence properties of bulk plasma flow and magnetic field orientation near the mid-tail neutral sheet are determined using IMP 6, 7, and 8 magnetic field and particle data. Bulk flow and magnetic field characteristics significantly change according to the radial distance down the tail. The predominant direction of the flow is duskward in the region Earthward of X = -25 R(E), but is sunward in the region beyond X = -25 R(E). High speed flow events (V > 300 km/s) near the neutral sheet are essentially restricted to the region tailward of X = -25 R(E) and are predominantly Earthward or tailward. The relationship between Bz polarity and plasma flow direction of high speed flow events is consistent with that expected due to magnetic reconnection processes. C1 JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD 20707 USA. UNIV CALIF LOS ANGELES, INST GEOPHYS & PLANETARY PHYS, LOS ANGELES, CA 90024 USA. RP NAKAMURA, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GSFC, CODE 690, GREENBELT, MD 20771 USA. RI Nakamura, Rumi/I-7712-2013 OI Nakamura, Rumi/0000-0002-2620-9211 NR 15 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 APR PY 1993 VL 13 IS 4 BP 223 EP 228 PG 6 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200034 ER PT J AU BIRN, J HESSE, M AF BIRN, J HESSE, M TI PARTICLE-ACCELERATION IN A MHD SIMULATION OF MAGNETOTAIL DYNAMICS SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID RECONNECTION AB The acceleration of protons in a dynamically evolving magnetotail is investigated on the basis of a three-dimensional resistive MHD simulation and the tracing of particles in the fields obtained from that simulation. The MHD simulation, representing plasmoid formation and ejection through a near-Earth reconnection process, generates cross-tail electric fields of up to about 4-mV/m, which lead to integrated potential differences across the tail of up to 200-kV. The large spatial extent of the increased electric field, which is largely associated with the plasma motion, together with the finite cross-tail extent suggest that acceleration might take place over a wide range of locations in x. This is confirmed by the particle tracing. An investigation of energized particles in the near-Earth region shows that these particles occupy a significant portion of the closed field line region inside of, but for moderate energies of tens of keV, not directly adjacent to, the separatrix. C1 NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, GREENBELT, MD 20771 USA. RP BIRN, J (reprint author), LOS ALAMOS NATL LAB, MS D438, LOS ALAMOS, NM 87545 USA. RI Hesse, Michael/D-2031-2012 NR 7 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 APR PY 1993 VL 13 IS 4 BP 245 EP 248 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200037 ER PT J AU HESSE, M BIRN, J AF HESSE, M BIRN, J TI PARALLEL ELECTRIC-FIELDS AS ACCELERATION MECHANISMS IN 3-DIMENSIONAL MAGNETIC RECONNECTION SO ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article ID LINE AB An extension to the theory of General Magnetic Reconnection (GMR) is presented. In particular, a new analytical relation between the rate of change of newly connected magnetic flux and the maximum possible value of the parallel component of the electric field integrated along the magnetic field will be derived. Estimates of the maximum value based on three-dimensional MHD simulations will be presented also. C1 LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87544 USA. RP NASA, GODDARD SPACE FLIGHT CTR, CODE 696, GREENBELT, MD 20771 USA. RI Hesse, Michael/D-2031-2012 NR 12 TC 2 Z9 2 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 APR PY 1993 VL 13 IS 4 BP 249 EP 252 PG 4 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA KV092 UT WOS:A1993KV09200038 ER PT J AU SAMIMY, M ZAMAN, KBMQ REEDER, MF AF SAMIMY, M ZAMAN, KBMQ REEDER, MF TI EFFECT OF TABS ON THE FLOW AND NOISE FIELD OF AN AXISYMMETRICAL JET SO AIAA JOURNAL LA English DT Article ID SHEAR-LAYER; SUPERSONIC JETS; SUBSONIC JET AB The effect of vortex generators, in the form of small tabs projecting normally into the flow at the nozzle exit, on the characteristics of an axisymmetric jet is investigated experimentally over the jet Mach number range of 0.3-1.81. The tabs eliminate screech noise from supersonic jets and alter the shock structure drastically. They distort the jet cross section and increase the jet spread mte significantly. The distortion produced is essentially the same at subsonic and underexpanded supersonic conditions. Thus, the underlying mechanism must be independent of compressibility effects. A tab with a height as small as 2% of the jet diameter, but larger than the efflux boundary-layer thickness, is found to produce a significant effect. Flow visualization reveals that each tab introduces an ''indentation'' into the high speed side of the shear layer via the action of streamwise vortices. These vortices are inferred to be of the ''trailing vortex'' type rather than of the ''necklace vortex'' type. It is apparent that a substantial pressure differential must exist between the upstream and the downstream sides of the tab to effectively produce these trailing vortices. This explains why the tabs are ineffective in the overexpanded now, as in that case an adverse pressure gradient exists near the nozzle exit which reduces the pressure differential produced by the tab. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP SAMIMY, M (reprint author), OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210, USA. NR 32 TC 130 Z9 136 U1 1 U2 8 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 APR PY 1993 VL 31 IS 4 BP 609 EP 619 DI 10.2514/3.11594 PG 11 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000001 ER PT J AU YOUNG, TW WARREN, ES HARRIS, JE HASSAN, HA AF YOUNG, TW WARREN, ES HARRIS, JE HASSAN, HA TI NEW APPROACH FOR THE CALCULATION OF TRANSITIONAL FLOWS SO AIAA JOURNAL LA English DT Article AB In spite of many attempts at modeling natural transition, it has not been possible to predict the streamwise intensities. A procedure is developed that incorporates some results of linear stability theory into one-equation and stress model formulations. The stresses resulting from fluctuations in the transitional region have turbulent, laminar (nonturbulent), and large eddy components. Comparison with Schubauer and Klebanoff's experiments have shown that the nonturbulent and large eddy components have a large influence on the streamwise intensities and little influence on the skin friction. Finally, predictions of the one-equation model were as good as those obtained by the stress model. C1 NASA,LANGLEY RES CTR,DIV FLUID DYNAM,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23681. RP YOUNG, TW (reprint author), N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695, USA. NR 14 TC 6 Z9 7 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 APR PY 1993 VL 31 IS 4 BP 629 EP 636 DI 10.2514/3.11596 PG 8 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000003 ER PT J AU SHIH, TH LUMLEY, JL AF SHIH, TH LUMLEY, JL TI CRITICAL COMPARISON OF 2ND-ORDER CLOSURES WITH DIRECT NUMERICAL SIMULATIONS OF HOMOGENEOUS TURBULENCE SO AIAA JOURNAL LA English DT Article ID MODELS; FLOWS AB Recently, several models have been proposed for closing the second-moment equations, in which the velocity-pressure gradient tensor and the dissipation rate tensor are two of the most important terms. In the literature, these correlation tensors are usually decomposed into a so-called rapid term and a return-to-isotropy term. Models of these terms have been used in global now calculations together with other modeled terms. However, their individual behaviors in different flows have not been fully examined because they are unmeasurable in the laboratory. Recently, the development of direct numerical simulation (DNS) of turbulence has given us the possibility to do this kind of study. With direct numerical simulation, we may use the solution to calculate exactly the values of these correlation terms and then directly compare them with the values from their modeled formulations. In this paper, we make direct comparisons of five representative rapid models and eight return-to-isotropy models using the DNS data of 45 homogeneous flows, which were done by Rogers et al. (1986) and Lee and Reynolds (1985). The purpose of these direct comparisons is to explore the performance of these models in different flows and identify the ones that give the best performance. The paper also describes the modeling procedure, model constraints, and the various evaluated models. The detailed results of the direct comparisons are discussed, and a few concluding remarks on turbulence models are given. C1 CORNELL UNIV,DEPT MECH & AEROSP ENGN,ITHACA,NY 14853. RP SHIH, TH (reprint author), NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135, USA. NR 23 TC 20 Z9 20 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 APR PY 1993 VL 31 IS 4 BP 663 EP 670 DI 10.2514/3.11601 PG 8 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000008 ER PT J AU FRENDI, A MAESTRELLO, L BAYLISS, A AF FRENDI, A MAESTRELLO, L BAYLISS, A TI COUPLING BETWEEN A SUPERSONIC BOUNDARY-LAYER AND A FLEXIBLE SURFACE SO AIAA JOURNAL LA English DT Article AB The coupling between a two-dimensional, supersonic, laminar boundary layer and a flexible surface is studied using direct numerical computations of the Navier-Stokes equations coupled with the plate equation. The flexible surface is forced to vibrate by plane acoustic waves at normal incidence emanated by a sound source located on the side of the flexible surface opposite to the boundary layer. The effect of the source excitation frequency on the surface vibration and boundary-layer stability is analyzed. We find that, for frequencies near the fifth natural frequency of the surface or lower, large disturbances are introduced in the boundary layer that may alter its stability characteristics. The interaction between a stable two-dimensional disturbance of Tollmien-Schlichting (TS) type with the vibrating surface is also studied. We find that the disturbance level is higher over the vibrating flexible surface than that obtained when the surface is rigid, which indicates a strong coupling between now and structure. However, in the absence of the sound source, the disturbance levels over the rigid and flexible surfaces are identical. This result is due to the high frequency of the TS disturbance that does not couple with the flexible surface. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NORTHWESTERN UNIV,CHICAGO,IL 60611. RP FRENDI, A (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23665, USA. RI Bayliss, Alvin/B-7337-2009 NR 14 TC 8 Z9 8 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 APR PY 1993 VL 31 IS 4 BP 708 EP 713 DI 10.2514/3.49017 PG 6 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000014 ER PT J AU DAVILA, CG JOHNSON, ER AF DAVILA, CG JOHNSON, ER TI ANALYSIS OF DELAMINATION INITIATION IN POSTBUCKLED DROPPED-PLY LAMINATES SO AIAA JOURNAL LA English DT Article AB The compression strength of dropped-ply, graphite-epoxy laminated plates for the delamination mode of failure is studied by a finite element analysis and corroborated with experiments. The compression strength of the 2.54-cm-wide specimens, which exhibited a linear response to delamination initiation, is greater than the compression strength of the 7.62-cm-wide specimens with the same layup, which exhibited a nonlinear response to delamination. Analyses confirm that the influence of the geometric nonlinearity on the response of the 2.54-cm-wide dropped-ply laminate is insignificant, but this nonlinearity is very significant in the response of its 7.62-cm-wide counterpart. For the 7.62-cm-wide dropped-ply laminate, the decrease in compression strength is associated with the redistribution and intensification of the severe interlaminar stress gradients occurring at the dropoff to a location closer to the knife-edge support. C1 VIRGINIA POLYTECH INST & STATE UNIV,DEPT AEROSP & OCEAN ENGN,BLACKSBURG,VA 24061. RP DAVILA, CG (reprint author), NASA,HAMPTON,VA 23665, USA. RI Davila, Carlos/D-8559-2011 NR 17 TC 38 Z9 39 U1 1 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 APR PY 1993 VL 31 IS 4 BP 721 EP 727 DI 10.2514/3.49019 PG 7 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000016 ER PT J AU WEILAND, KJ AF WEILAND, KJ TI INTENSIFIED ARRAY CAMERA IMAGING OF SOLID-SURFACE COMBUSTION ABOARD THE NASA LEARJET SO AIAA JOURNAL LA English DT Note RP WEILAND, KJ (reprint author), NASA,LEWIS RES CTR,DIV SPACE EXPT,2100 BROOKPARK RD,MS 110-3,CLEVELAND,OH 44135, USA. NR 8 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 APR PY 1993 VL 31 IS 4 BP 786 EP 788 DI 10.2514/3.49023 PG 3 WC Engineering, Aerospace SC Engineering GA KY250 UT WOS:A1993KY25000026 ER PT J AU LIN, TA NAVIDI, M JAMES, W LIN, TN SUN, GY AF LIN, TA NAVIDI, M JAMES, W LIN, TN SUN, GY TI EFFECTS OF ACUTE ETHANOL ADMINISTRATION ON POLYPHOSPHOINOSITIDE TURNOVER AND LEVELS OF INOSITOL 1,4,5-TRISPHOSPHATE IN MOUSE CEREBRUM AND CEREBELLUM SO ALCOHOLISM-CLINICAL AND EXPERIMENTAL RESEARCH LA English DT Article DE POLY-PL TURNOVER; ACUTE ETHANOL; ATROPINE; CEREBRUM; CEREBELLUM ID RAT-BRAIN; MEMBRANE PHOSPHOINOSITIDES; MYOINOSITOL 1-PHOSPHATE; HYDROLYSIS; METABOLISM; PHOSPHATES; BREAKDOWN; LITHIUM; CORTEX AB Although ethanol is known for its central depressant action, its effect on the polyphosphoinositide (poly-PI) signal transduction activity in brain has not been examined in detail. In this study, C57BI/6J mice were injected intracerebrally with [H-3]inositol, and poly-PI turnover in brain was assessed by determining the levels of labeled inositol monophosphates (IP1) accumulated after intraperitoneal injection of LiCl (6 meq/kg body weight) 4 hr before killing. Using this experimental protocol, acute ethanol administration (by gavage) resulted in time- and dose-dependent decreases in the levels of labeled IP1 in both cerebrum and cerebellum as compared with controls. The ethanol-induced decrease in labeled IP1 correlated well with the decrease in levels of inositol 1,4,5-triphosphate (as measured by the radioreceptor assay) and the increase in blood ethanol concentration. Despite a 4-fold higher accumulation of labeled IP1 in the cerebrum compared with the cerebellum, there were no major differences in the steady-state levels of inositol 1,4,5-triphosphate (based on tissue weight) in either brain region. Intraperitoneal injection of atropine (50 mg/kg) (a muscarinic cholinergic receptor antagonist) to the lithium-treated mice resulted in a 34% decrease in labeled IP, as compared with controls. This result suggests that a substantial proportion of the signals transduced were due to activation of the muscarinic cholinergic receptor. Administration of ethanol (5 g/kg) to the atropine-treated mice resulted in a further decrease in labeled IP, and longer sleep time as compared with those given ethanol alone. Taken together, these results indicate a relationship between the acute effect of ethanol and the poly-PI signaling activity in brain and modulation of the ethanol effect by compounds affecting the poly-PI signaling pathway. C1 UNIV MISSOURI,SCH MED,DEPT BIOCHEM,M121 MED SCI BLDG,COLUMBIA,MO 65212. NASA,AMES RES CTR,BIONET INC,MOFFETT FIELD,CA 94035. BAYLOR COLL MED,DIV RESTORATORY NEUROL,HOUSTON,TX 77030. FU NIAAA NIH HHS [AA06661, AA07458] NR 19 TC 9 Z9 9 U1 0 U2 0 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0145-6008 J9 ALCOHOL CLIN EXP RES JI Alcoholism (NY) PD APR PY 1993 VL 17 IS 2 BP 401 EP 405 DI 10.1111/j.1530-0277.1993.tb00783.x PG 5 WC Substance Abuse SC Substance Abuse GA KZ662 UT WOS:A1993KZ66200035 PM 8387729 ER PT J AU EDWARDS, ML UTHMAN, M SPALDING, G GOODWIN, T HOLIAN, A AF EDWARDS, ML UTHMAN, M SPALDING, G GOODWIN, T HOLIAN, A TI TYPE-II PNEUMOCYTES RETAIN DIFFERENTIATED MORPHOLOGY IN A LOW SHEAR SUSPENSION-CULTURE SO AMERICAN REVIEW OF RESPIRATORY DISEASE LA English DT Meeting Abstract C1 UNIV TEXAS,SCH MED,DIV PULM & CRIT CARE,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER LUNG ASSOC PI NEW YORK PA 1740 BROADWAY, NEW YORK, NY 10019 SN 0003-0805 J9 AM REV RESPIR DIS JI Am. Rev. Respir. Dis. PD APR PY 1993 VL 147 IS 4 SU S BP A160 EP A160 PG 1 WC Respiratory System SC Respiratory System GA LB149 UT WOS:A1993LB14900585 ER PT J AU BRECKINRIDGE, JB WOOD, HJ AF BRECKINRIDGE, JB WOOD, HJ TI SPACE OPTICS - INTRODUCTION SO APPLIED OPTICS LA English DT Editorial Material AB This feature of Applied Optics consists of papers on the Hubble Space Telescope and its instruments as well as other new instruments and other new optics technology for space science. Many of the papers are an outgrowth of the papers presented at the Second Space Optics Topical Meeting, October 1991, in Williamsburg, Va. This introduction provides an overview for the papers related to the Hubble Space Telescope: measurement of the error and approaches to correct for the error. C1 NASA, GODDARD SPACE FLIGHT CTR, HUBBLE SPACE TELESCOPE PROJECT OFF, GREENBELT, MD 20771 USA. RP BRECKINRIDGE, JB (reprint author), JET PROP LAB, OPT SECT, CODE 442, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 1 TC 2 Z9 2 U1 0 U2 1 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 APR 1 PY 1993 VL 32 IS 10 BP 1677 EP 1680 PG 4 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500001 PM 20820299 ER PT J AU MEINEL, AB MEINEL, MP SCHULTE, DH AF MEINEL, AB MEINEL, MP SCHULTE, DH TI DETERMINATION OF THE HUBBLE SPACE TELESCOPE EFFECTIVE CONIC-CONSTANT ERROR FROM DIRECT IMAGE MEASUREMENTS SO APPLIED OPTICS LA English DT Article DE WIDE-FIELD AND PLANETARY-CAMERA IMAGERY; HUBBLE SPACE TELESCOPE; CONIC-CONSTANT DETERMINATION; DIRECT IMAGE MEASUREMENT AB Direct measurement of discernible features in the Hubble Space Telescope (HST) imagery has enabled a self-consistent determination to be made of the effective conic constant of HST images taken with planetary camera 6 (PC-6) of the wide field and planetary camera. Before being corrected for the contribution from PC-6, the conic constant is -1.01429 +/- 0.0002. The correction for PC-6 is less accurately determined but probably lies between -0.0002 and 0.0004. As a result the HST optics are characterized best by a conic constant of -1.0140 +/- 0.0003 as obtained from direct image measurements. C1 LOCKHEED MISSILES & SPACE CO INC, PALO ALTO, CA 94304 USA. RP MEINEL, AB (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 0 TC 2 Z9 2 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 APR 1 PY 1993 VL 32 IS 10 BP 1715 EP 1719 PG 5 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500006 PM 20820304 ER PT J AU REDDING, D DUMONT, P YU, J AF REDDING, D DUMONT, P YU, J TI HUBBLE SPACE TELESCOPE PRESCRIPTION RETRIEVAL SO APPLIED OPTICS LA English DT Article AB Prescription retrieval is a technique for directly estimating optical prescription parameters from images. We apply it to estimate the value of the Hubble Space Telescope primary mirror conic constant. Our results agree with other studies that examined primary-mirror test fixtures and results. In addition they show that small aberrations exist on the planetary-camera repeater optics. C1 CHARLES STARK DRAPER LAB INC, CAMBRIDGE, MA 02139 USA. RP REDDING, D (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 8 TC 12 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 APR 1 PY 1993 VL 32 IS 10 BP 1728 EP 1736 PG 9 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500008 PM 20820306 ER PT J AU DAVILA, P WOOD, HJ ATCHESON, PD SAUNDERS, R SULLIVAN, J VAUGHAN, AH SAISSE, M AF DAVILA, P WOOD, HJ ATCHESON, PD SAUNDERS, R SULLIVAN, J VAUGHAN, AH SAISSE, M TI TELESCOPE SIMULATORS FOR HUBBLE - AN OVERVIEW OF OPTICAL DESIGNS SO APPLIED OPTICS LA English DT Article AB Various optical configurations for Hubble Space Telescope simulators have been proposed, and some are being built for use as verification tools to characterize the performance of second-generation instruments during ground testing. We describe the Hubble Space Telescope, present an overview of three optical designs for simulators, and discuss the relative advantages and disadvantages of each configuration. C1 BALL AEROSP SYST GRP, BOULDER, CO 80306 USA. JET PROP LAB, PASADENA, CA 91109 USA. CNRS, ASTRON SPATIALE LAB, F-13376 MARSEILLE 12, FRANCE. RP DAVILA, P (reprint author), NASA, GODDARD SPACE FLIGHT CTR, OPT BRANCH, GREENBELT, MD 20771 USA. NR 8 TC 2 Z9 2 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 APR 1 PY 1993 VL 32 IS 10 BP 1775 EP 1781 PG 7 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500012 PM 20820310 ER PT J AU HANNAN, PG DAVILA, P WOOD, HJ AF HANNAN, PG DAVILA, P WOOD, HJ TI OPTICAL DESIGN OF ZERO-POWER HUBBLE SPACE TELESCOPE WAVE-FRONT CORRECTORS FOR NULL TESTING SO APPLIED OPTICS LA English DT Article DE OPTICAL TESTING; LENS DESIGN; OPTICAL DESIGN AB The optical design of the second-generation wide-field/planetary-camera instrument for the Hubble Space Telescope has been modified to compensate for the spherical aberration of the optical telescope assembly (OTA) by introduction of undercorrected spherical aberration into the wave front. This instrument can be tested in a simple manner to ensure that its aberration contribution has the proper sign and magnitude. We present designs for a near-zero power doublet lens that can be used to generate a spherically aberrated wave front that is similar to the OTA wave front. When this lens is used in combination with the instrument, a near-perfect or nulled wave front should be produced, resulting in a high-quality point image on axis. We also present lens designs for a similar test that can be performed on the OTA simulators now being built to verify the other second-generation instruments. RP HANNAN, PG (reprint author), NASA, GODDARD SPACE FLIGHT CTR, OPT BRANCH, GREENBELT, MD 20771 USA. NR 1 TC 0 Z9 0 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 APR 1 PY 1993 VL 32 IS 10 BP 1782 EP 1785 PG 4 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500013 PM 20820311 ER PT J AU FEINBERG, L WILSON, M AF FEINBERG, L WILSON, M TI HUBBLE SPACE TELESCOPE COSTAR ASPHERE VERIFICATION WITH A MODIFIED COMPUTER-GENERATED HOLOGRAM INTERFEROMETER SO APPLIED OPTICS LA English DT Article AB To correct for the spherical aberration in the Hubble Space Telescope primary mirror, five anamorphic aspheric mirrors representing correction for three scientific instruments have been fabricated as part of the development of the corrective-optics space telescope axial-replacement instrument (COSTAR). During the acceptance tests of these mirrors at the vendor, a quick and simple method for verifying the asphere surface figure was developed. The technique has been used on three of the aspheres relating to the three instrument prescriptions. Results indicate that the three aspheres are correct to the limited accuracy expected of this test. RP FEINBERG, L (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 4 TC 2 Z9 2 U1 1 U2 1 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 APR 1 PY 1993 VL 32 IS 10 BP 1786 EP 1788 PG 3 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500014 PM 20820312 ER PT J AU COLAVITA, MM SHAO, M RAYMAN, MD AF COLAVITA, MM SHAO, M RAYMAN, MD TI ORBITING STELLAR INTERFEROMETER FOR ASTROMETRY AND IMAGING SO APPLIED OPTICS LA English DT Article DE STELLAR INTERFEROMETRY; OPTICAL INTERFEROMETRY; ASTROMETRY; ASTRONOMICAL IMAGING; SPACE OPTICS; LASER METROLOGY ID LIGHT AB The orbiting stellar interferometer (OSI) is a concept for a first-generation space interferometer with astrometric and imaging goals and is responsive to the recommendations of the Astronomy and Astrophysics Survey Committee for an astrometric interferometer mission. The OSI, as developed at the Jet Propulsion Laboratory over the past several years, is a triple Michelson interferometer with articulating siderostats and optical delay lines. Two point designs for the instrument are described. The 18-m design uses an 18-m maximum baseline and aperture diameters of 40 cm; the targeted astrometric performance is a wide-field accuracy of 10 muarsec for 16-mag objects in 100 s of integration time and for 20-mag objects in 1 h. The instrument would also be capable of synthesis imaging with a resolution of 5 marcsec, which corresponds to the diffraction limit of the 18-m base line. The design uses a deployed structure, which would fold to fit into an Atlas IIAS shroud, for insertion into a 900-km sun-synchronous orbit. In addition to the 18-m point design a 7-m point design that uses a shorter base line in order to simplify deployment is also discussed. OSI's high performance is made possible by utilizing laser metrology and controlled-optics technology. RP COLAVITA, MM (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 16 TC 9 Z9 9 U1 0 U2 1 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 APR 1 PY 1993 VL 32 IS 10 BP 1789 EP 1797 PG 9 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500015 PM 20820313 ER PT J AU HERZIG, H TOFT, AR FLEETWOOD, CM AF HERZIG, H TOFT, AR FLEETWOOD, CM TI LONG-DURATION ORBITAL EFFECTS ON OPTICAL COATING MATERIALS SO APPLIED OPTICS LA English DT Article DE MIRRORS; REFLECTANCE; SPACE OPTICS AB We flew specimens of eight different optical coating materials in low earth orbit as part of the Long Duration Exposure Facility manifest to determine their ability to withstand exposure to the residual atomic O and other environmental effects at those altitudes. We included samples of Al, Au, Ir, Os, Pt, Al + MgF2, Al + SiO(x), and chemical-vapor-deposited SiC, representing reflective optical applications from the vacuum ultraviolet through the visible portions of the spectrum. We found that the majority of the materials suffered sufficient reflectance degradation to warrant careful consideration in the design of future space-flight instrumentation. RP HERZIG, H (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 11 TC 14 Z9 14 U1 4 U2 7 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 APR 1 PY 1993 VL 32 IS 10 BP 1798 EP 1804 PG 7 WC Optics SC Optics GA KW465 UT WOS:A1993KW46500016 PM 20820314 ER PT J AU BISWAS, A AF BISWAS, A TI THERMAL-PROCESSING OF O-TERPHENYL - A RAMAN-STUDY SO APPLIED SPECTROSCOPY LA English DT Article DE RAMAN SPECTROSCOPY; MATERIALS PROCESSING; GLASS TRANSITION, O-TERPHENYL ID SCATTERING AB Raman spectra from o-terphenyl sealed in glass capillary tubes were acquired over temperatures ranging from 233 K to 343 K. Over this temperature range, o-terphenyl can exist in the solid-crystalline, molten, supercooled-liquid, and amorphous-glassy states. Representative structure-sensitive spectra are presented along with a qualitative description. The lattice spectral feature occurring at a Raman shift of 123 cm-1 displays abrupt changes in profile and intensity as melting and glass transition occur. The intensity ratio of the C-C stretching 996-cm-1 line and C-H stretching line at 1008 cm-1 displays a change related to the transformation of the ordered-crystalline phase to the disordered-liquid or glassy state. At a Raman shift of 1162 cm-1 the solid-crystalline state shows a splitting due to the effect of the crystal field. The possibility of using these structure-sensitive Raman characteristics for in situ diagnostics during materials processing is discussed. RP BISWAS, A (reprint author), JET PROP LAB,MS 183-401,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 5 Z9 5 U1 1 U2 2 PU SOC APPLIED SPECTROSCOPY PI FREDERICK PA PO BOX 1438, FREDERICK, MD 21701 SN 0003-7028 J9 APPL SPECTROSC JI Appl. Spectrosc. PD APR PY 1993 VL 47 IS 4 BP 458 EP 462 DI 10.1366/0003702934334921 PG 5 WC Instruments & Instrumentation; Spectroscopy SC Instruments & Instrumentation; Spectroscopy GA KZ612 UT WOS:A1993KZ61200013 ER PT J AU LONSDALE, CJ CHOKSHI, A AF LONSDALE, CJ CHOKSHI, A TI EVOLUTION OF THE BLUE AND FAR-INFRARED GALAXY LUMINOSITY FUNCTIONS SO ASTRONOMICAL JOURNAL LA English DT Article ID HIGH-REDSHIFT GALAXIES; NUMBER COUNTS; CONSTRAINTS; UNIVERSE; FIELD; MAG AB We construct a blue band luminosity function from published spectroscopic surveys of faint field galaxies (b(j)> 20) and compare it to three recent determinations of the blue-selected field galaxy luminosity function in the local universe. We find evidence for density evolution for moderate luminosity galaxies ( - 17.5 > M(b) > - 21.5; h = 0. 5) at a rate of (1 + z)delta, with a best fit of delta = 4 +/- 2, between the current epoch and z greater than or similar to 0. 1. At M(b) < - 22 we find evidence for about 0.5-1.5 mag of luminosity evolution in addition to the density evolution, corresponding to an evolutionary rate of L approximately (1+z)gamma, gamma = 0.5-2.5, by a redshift of about 0.4, when the data are compared to the local luminosity function of de Lapparent et al [ApJ, 343, 1 (1989)]. However, in the presence of the above mentioned density evolution, no additional luminosity evolution is required to fit the M(b) < - 22 data if the local luminosity functions of either Efstathiou et al. [MNRAS, 232, 431, (1988)] or Loveday et al. [ApJ, 390, 338 (1992)] are used instead. Assuming a steeper faint end slope of alpha = -1.3, similar to that observed in the Virgo cluster, could explain the data with a luminosity evolution rate gamma = 1-2, without need for any density evolution. We compare the best-fitting composite density and luminosity evolution models to faint IRAS 60 mum source counts. The fits are quite acceptable, implying that the blue and far-infrared evolutionary rates may be similar. C1 JET PROP LAB,PASADENA,CA 91109. RP LONSDALE, CJ (reprint author), CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125, USA. NR 40 TC 23 Z9 23 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 APR PY 1993 VL 105 IS 4 BP 1333 EP 1343 DI 10.1086/116513 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU572 UT WOS:A1993KU57200008 ER PT J AU BRUHWEILER, FC FEIBELMAN, WA AF BRUHWEILER, FC FEIBELMAN, WA TI INTERNATIONAL ULTRAVIOLET EXPLORER OBSERVATIONS OF THE WHITE-DWARF NUCLEUS OF THE VERY OLD, DIFFUSE PLANETARY-NEBULA, IW-2 SO ASTRONOMICAL JOURNAL LA English DT Article ID HIGH-GRAVITY STARS; ATMOSPHERES; SPECTRA; HOT; OXYGEN; MODELS AB Ultraviolet low-dispersion spectra of the central star of the faint planetary nebula, IW-2, were obtained with the International Ultraviolet Explorer (IUE). The apparent large diameter of the very diffuse nebula, about half that of the moon, as seen on the Palomar Sky Survey plates by Ishida and Weinberger, indicates this object to be potentially quite evolved and nearby. The IUE spectra clearly reveal a hot stellar continuum extending over the entire wavelength range of the short-wavelength prime camera (1200-2000 angstrom). This object with V = 17.7 +/- 0.4 is definitely one of the faintest stars ever successfully observed with the IUE. Comparisons of the IUE observed fluxes with those from white dwarf model atmospheres suggest extinction near E(B- V) =0.45 for a white dwarf of T(eff) almost-equal-to 100 000 K. This, together with constraints from estimates of the nebular emission measure and observed visual magnitude also argue for a white dwarf of T(eff) almost-equal-to 100 000 K at a distance of 300 to 350 pc. The distance and luminosity of the central star is greater than that deduced by Ishida and Weinberger. It further shows that the nucleus of IW-2 to be one of the most evolved stars to be identified with a planetary nebula. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BRUHWEILER, FC (reprint author), CATHOLIC UNIV AMER,DEPT PHYS,ASTROPHYS PROGRAM,WASHINGTON,DC 20064, USA. NR 18 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 0004-6256 J9 ASTRON J JI Astron. J. PD APR PY 1993 VL 105 IS 4 BP 1477 EP 1480 DI 10.1086/116525 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU572 UT WOS:A1993KU57200020 ER PT J AU MORRIS, CS HANNER, MS AF MORRIS, CS HANNER, MS TI THE INFRARED LIGHT-CURVE OF PERIODIC COMET HALLEY 1986-III AND ITS RELATIONSHIP TO THE VISUAL LIGHT-CURVE, C2, AND WATER PRODUCTION-RATES SO ASTRONOMICAL JOURNAL LA English DT Article ID MONITORING PROGRAM; IUE OBSERVATIONS; P/HALLEY; PHOTOMETRY; COLOR; PERIHELION; SCATTERING; DUST AB The near-infrared light curve of Periodic Comet Halley 1986 III is analyzed and compared with C2 production, water production, and the visual light curve. This is the most complete infrared light curve compiled, to date, for any comet. The scattering phase function at small Sun-comet-Earth angles is shown to affect the slope of near-infrared light curve significantly. P/Halley's dust production, as inferred from the infrared light curve, did not vary as a simple power-law with respect to heliocentric distance, but showed an increased production rate near perihelion which appears to be correlated with the onset of significant jet activity. The near-infrared light curve, visual light curve, C2, and water production rates displayed different heliocentric variations suggesting that one parameter cannot be accurately estimated from another. This is particularly true of the early preperihelion visual light curve which reflects the accumulation of material in the growing coma and, thus, does not mimic the heliocentric variation of any of the other parameters. During short-term periods of enhanced activity, on the time scale of hours, the small aperture (near-nucleus) observations peaked within hours of the onset of activity. A peak of 0.3-0.5 magnitude in the visual magnitude, representing the integrated brightness of the comet's visible coma, lagged the other parameters by about a day. The near-infrared color, J-H, was less red during periods of strong dust activity. RP MORRIS, CS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 38 TC 8 Z9 8 U1 0 U2 1 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 APR PY 1993 VL 105 IS 4 BP 1537 EP 1546 DI 10.1086/116533 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU572 UT WOS:A1993KU57200028 ER PT J AU YEOMANS, DK CHODAS, PW KEESEY, MS OWEN, WM WIMBERLY, RN AF YEOMANS, DK CHODAS, PW KEESEY, MS OWEN, WM WIMBERLY, RN TI TARGETING AN ASTEROID - THE GALILEO SPACECRAFTS ENCOUNTER WITH 951 GASPRA SO ASTRONOMICAL JOURNAL LA English DT Article AB On 1991 October 29, the Galileo spacecraft provided the first in situ observations of an asteroid. To a significant degree, the successful encounter with asteroid 951 Gaspra was made possible by the high accuracy of the ground-based Gaspra ephemeris and the refinement to this initial ephemeris provided by the use of optical navigation images taken on board the spacecraft itself. The success of these celestial navigation efforts was dramatically demonstrated when Gaspra appeared in the central frame of the large mosaic of CCD images-less than one asteroid diameter from Gaspra's expected location in the camera's field of view. The corrections to Gaspra's ground-based ephemeris, based upon the optical on-board navigation images, were less than 80 km. The ground-based observation program that went into this ephemeris development is discussed and the accuracy of the ephemeris is used to validate the assumptions that went into the error analysis studies. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP YEOMANS, DK (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 8 TC 12 Z9 13 U1 0 U2 1 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 APR PY 1993 VL 105 IS 4 BP 1547 EP 1552 DI 10.1086/116534 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU572 UT WOS:A1993KU57200029 ER PT J AU DEMOULIN, P VANDRIELGESZTELYI, L SCHMIEDER, B HENOUX, JC CSEPURA, G HAGYARD, MJ AF DEMOULIN, P VANDRIELGESZTELYI, L SCHMIEDER, B HENOUX, JC CSEPURA, G HAGYARD, MJ TI EVIDENCE FOR MAGNETIC RECONNECTION IN SOLAR-FLARES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS (MHD); THE SUN, FLARES; THE SUN, MAGNETIC FIELDS; THE SUN, ACTIVITY ID ACTIVE REGIONS; ELECTRIC CURRENTS; ENERGY-RELEASE; LINE AB From a study of the magnetic field topology in an active region, evidence is derived that solar flares are produced by magnetic reconnection. We study a complex group with two active regions (AR 2511 and AR 2512) for three consecutive days, June 13-15 1980. The observed longitudinal magnetic field is used to model the coronal magnetic field by the potential field created by a series of magnetic charges. This computed field matches satisfactorily the Halpha fibrils and the observed transverse field direction. A set of flares occurs principally in the northern group (AR 2511). During these three days, two different magnetic configurations in succession are responsible for the occurrence of these flares: first the intrusion of a new opposite flux in the following polarity, secondly the emergence of new flux between the main polarities. In this last case flares occurred, although the emerging bipole is almost parallel to the main bipole. We show that even in this bipolar configuration a separator is present and that observed Halpha flare ribbons are located near the intersection of the computed separatrices with the photosphere. This provides strong support to a model where reconnection releases the stored magnetic energy. The induced evolution of the magnetic field forces reconnection along others separators. They are connected by magnetic field lines to fainter kernels. C1 STERREKUNDIG INST, 3508 TA UTRECHT, NETHERLANDS. HELIOPHYS OBSERV, H-4010 DEBRECEN, HUNGARY. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RP DEMOULIN, P (reprint author), OBSERV PARIS, DASOP, UA 326, F-92195 MEUDON, FRANCE. NR 26 TC 94 Z9 95 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 APR PY 1993 VL 271 IS 1 BP 292 EP 307 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU738 UT WOS:A1993KU73800033 ER PT J AU SEKANINA, Z AF SEKANINA, Z TI ORBITAL ANOMALIES OF THE PERIODIC COMETS BRORSEN, FINLAY, AND SCHWASSMANN-WACHMANN-2 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMETS; ORBITAL ANOMALIES; LIGHT CURVE; P/BRORSEN; P/FINLAY; P/SCHWASSMANN; WACHMANN-2 ID NUCLEUS PRECESSION; MOTION AB Activation of new discrete sources appears to be a common phenomenon on the nuclei of periodic comets. Some of these sources have life spans as short as 1-2 revolutions about the Sun or less, while others are much more persistent (enduring for dozens of revolutions or longer). One line of evidence for an episode of this kind is an orbital anomaly, a sudden redistribution of the momentum that is transferred to the nucleus by the sublimating mass. Such discontinuities in the orbital motion have been reported for a number of periodic comets, of which Brorsen, Finlay, and Schwassmann-Wachmann 2 are investigated in some detail in this paper. Since the ''ignition'' and/or deactivation of a discrete source also entail parallel changes in the comet's water production and light curves, the latter provide constraints on the activation/deactivation scenarios. Although no unique solution can be offered in any particular case, the best conditions for detecting such events generally occur when the nucleus rotation vector is near the orbital plane and normal to the Sun's direction at perihelion and when the activated/deactivated source is near one of the rotation poles. Especially for highly irregular nuclei, forced precession is a likely byproduct of such episodes and it may assist in activating additional sources by altering the insolation distribution over the nucleus surface. RP JET PROP LAB, MAIL STOP 169-237, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 39 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 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD APR PY 1993 VL 271 IS 2 BP 630 EP 644 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KY482 UT WOS:A1993KY48200034 ER PT J AU HAMABATA, H AF HAMABATA, H TI PARAMETRIC-INSTABILITIES OF CIRCULARLY POLARIZED ALFVEN WAVES IN HIGH-BETA PLASMAS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INSTABILITIES; MHD; POLARIZATION ID FINITE-AMPLITUDE; SCATTERING AB A class of parametric instabilities of finitc-amplitude, circularly polarized Alfven waves in high-beta (plasma pressure/magnctic pressure) plasmas is considered by using the CGL equations including the effect of finite ion Larmor radius. Thc dispersion relation govcrning the instabilities is a sixth-order polynomial which is solved numerically. There are two types of instabilities: a modulational instability at k < k0 and a relatively weak and narrow bandwidth instability at k greater than or similar to k0, where k and ko are the wavenumbers of the unstable density fluctuation and the ''pump'' wave, respectively. It is shown that these instabilities can occur for left-hand pump waves and that the modulational instability is unstable over a very broad band in k with a maximum growth rate at finite k not-equal 0. It is also shown that the growth rate of the modulational instability peaks at particular values of the pump strength and beta, indicating that the instability can be suppressed if the amplitude of the pump wave and the plasma pressure are too large. Relevance of our investigation to the cosmic rays in the interstcllar medium is discussed. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. NR 17 TC 3 Z9 3 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 APR 1 PY 1993 VL 406 IS 2 BP 563 EP 568 DI 10.1086/172468 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU607 UT WOS:A1993KU60700022 ER PT J AU THOMAS, D SCHRAMM, DN OLIVE, KA FIELDS, BD AF THOMAS, D SCHRAMM, DN OLIVE, KA FIELDS, BD TI PRIMORDIAL NUCLEOSYNTHESIS AND THE ABUNDANCES OF BERYLLIUM AND BORON SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUCLEAR REACTIONS; NUCLEOSYNTHESIS; ABUNDANCES ID ENERGY-LEVELS; LIGHT-NUCLEI; HEAVY-ELEMENTS; REACTION-RATES; HALO-STARS; BE-9; LITHIUM; NUMBER AB The recently attained ability to make measurements of Be and B as well as to put constraints on Li-6 abundances in metal-poor stars has led to a detailed reexamination of big bang nucleosynthesis in the A greater than or similar to 6 regime. The nuclear reaction network has been significantly expanded, with many new rates added. It is demonstrated that although a number of A > 7 reaction rates are poorly determined, even with extreme values chosen, the standard homogeneous model is unable to produce significant yields (Be/H and B/H < 10(-17) when A less-than-or-equal-to 7 abundances fit) above A = 7, and the 7 Li-7/Li-6 ratio always exceeds 500. We also preliminarily explore inhomogeneous models, such as those inspired by a first-order quark-hadron phase transition, where regions with high neutron/proton ratios can allow some leakage up to A > 7. However, models that fit the A less-than-or-equal-to 7 abundances still seem to have difficulty in obtaining significant A > 7 yields. C1 NASA,FERMILAB ASTROPHYS CTR,FNAL,BATAVIA,IL 60510. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. RP THOMAS, D (reprint author), UNIV CHICAGO,CHICAGO,IL 60637, USA. NR 51 TC 83 Z9 83 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 APR 1 PY 1993 VL 406 IS 2 BP 569 EP 579 DI 10.1086/172469 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU607 UT WOS:A1993KU60700023 ER PT J AU NATTA, A PALLA, F BUTNER, HM EVANS, NJ HARVEY, PM AF NATTA, A PALLA, F BUTNER, HM EVANS, NJ HARVEY, PM TI INFRARED STUDIES OF CIRCUMSTELLAR MATTER AROUND HERBIG AE/BE AND RELATED STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, PRE-MAIN-SEQUENCE ID CARBON-MONOXIDE OBSERVATIONS; YOUNG STELLAR OBJECTS; R-CORONAE AUSTRINAE; EMISSION-LINE STARS; Z-CANIS MAJORIS; T-TAURI STARS; AE-TYPE STARS; HARO OBJECTS; MOLECULAR CLOUDS; RADIO-CONTINUUM AB High spatial resolution data at 50 and 100 mum are presented for seven young, intermediate-mass stars with flat or rising spectral energy distributions. Five objects have been resolved in at least one direction at 100 mum, and two were resolved at 50 mum. The far-infrared emission from resolved sources comes from extended envelopes whose size varies between 5 x 10(3) and 8 x 10(4) AU. In most cases, the intensity profiles do not show large departures from spherical symmetry. For the five resolved stars, we model the observations as emission from dust in an envelope, heated by a central source. The combination of the size information and the spectral energy distributions demonstrates that the central source spectra must be considerably redder than those of the stars. While several possible explanations exist, we adopt a model for the central source composed of a star and a circumstellar disk. By comparing the predictions of radiation transfer models to the observations (the far-infrared scans and the spectral energy distribution from visual to millimeter wavelengths), it is possible to separate the contribution of the star, the disk, and the envelope, and to investigate their physical properties. The derived density profiles of the envelopes show that in two cases the dust has a steep density profile (n approximately r(-alpha), alpha approximately 2), while in three other objects the dust must be distributed with rather shallow gradients (alpha approximately 0.5). Thus, our sample of five Herbig Ae/Be stars, all surrounded by a significant amount of matter, includes objects that are probably still in an accretion phase, and objects that are not. It is at present unclear if this results from the action of the star/disk system on the environment, or if it reflects a difference in the pristine physical conditions before the star formed. Circumstellar disks with temperatures given by T is-proportional-to r-0.5 provide a good explanation for the spectral energy distributions in the mid-infrared. However, the excess luminosity at near-infrared wavelengths, if interpreted as due to viscous dissipation, implies implausibly high mass accretion rates. A resolution to the problem of the origin of the excess luminosity and the role of accretion in pre-main-sequence evolution awaits more accurate determinations of the stellar luminosities. Alternative explanations, such as several independent dust structures near the star or of a component of small grains and PAHs, are in principle possible. C1 NASA, AMES RES CTR, DIV SPACE SCI, MOFFETT FIELD, CA 94035 USA. UNIV TEXAS, DEPT ASTRON, AUSTIN, TX 78712 USA. RP NATTA, A (reprint author), OSSERV ASTROFIS ARCETRI, LARGO E FERMI 5, I-50125 FLORENCE, ITALY. OI palla, francesco/0000-0002-3321-0456; Butner, Harold/0000-0003-4899-2064 NR 87 TC 83 Z9 83 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1993 VL 406 IS 2 BP 674 EP 691 DI 10.1086/172478 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU607 UT WOS:A1993KU60700032 ER PT J AU KASTNER, SO BHATIA, AK AF KASTNER, SO BHATIA, AK TI C-III SPECTRA IN WC WOLF-RAYET STARS - DOES COLLISIONAL EXCITATION DOMINATE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; STARS, WOLF-RAYET ID ABUNDANCES AB A direct comparison of the spectra emitted by an improved collisionally excited C III atomic model, with observations of C III spectra in Wolf-Rayet WC stars, shows agreement for UV, visible, and near-infrared lines including lines usually considered to be recombination lines. The agreement implies high-density and temperature source conditions corresponding to log (N(e) T(e)) > 16 as a lower limit, whereas most current modeling assumes log (N(e) T(e)) < 15.5. This raises questions concerning the photoionization/recombination assumptions on which most WR modeling is based. Recent models are discussed from this point of view. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP KASTNER, SO (reprint author), MATH SCI CONSULTANTS INC,1-A RIDGE RD,GREENBELT,MD 20770, USA. NR 32 TC 0 Z9 0 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 APR 1 PY 1993 VL 406 IS 2 BP 708 EP 713 DI 10.1086/172481 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU607 UT WOS:A1993KU60700035 ER PT J AU RHODES, EJ CACCIANI, A KORZENNIK, SG ULRICH, RK AF RHODES, EJ CACCIANI, A KORZENNIK, SG ULRICH, RK TI CONFIRMATION OF SOLAR-CYCLE DEPENDENT INTERMEDIATE-DEGREE P-MODE FREQUENCY-SHIFTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, OSCILLATIONS ID OSCILLATION FREQUENCIES; IRRADIANCE; SUN AB Recently, Libbrecht & Woodard (1990a, b) presented clear evidence that the frequencies of a set of intermediate-degree (5 less-than-or-equal-to l less-than-or-equal-to 60) solar p-mode oscillations increased systematically between mid-1986 and mid-1988. Independently, Elsworth et al. (1990) presented evidence for similar shifts in the frequencies of a set of low-degree (0 less-than-or-equal-to l less-than-or-equal-to 2) p-modes over an 11 yr interval between 1977 and 1988. Elsworth et al. (1990) also demonstrated that these low-degree frequency shifts were correlated with changes in the smoothed sunspot number over the entire 11 yr interval. Here we present the results of intercomparisons of seven different sets of frequencies of intermediate-degree (5 less-than-or-equal-to l less-than-or-equal-to 120) p-modes obtained at several different locations between 1981 and 1989. We will show that the frequency shifts exhibited by all of these intermediate-degree p-modes are consistent with the intermediate-degree frequency shifts presented by Libbrecht & Woodard (1990a, b) and also with the low-degree frequency shifts presented by Elsworth et al. (1990). We will also show that these frequency shifts correlate with solar cycle-dependent changes in sunspot number, area, and irradiance. We will also demonstrate that more extensive sets of p-mode observations will haye to be analyzed before it will be possible to determine which of these solar cycle parameters is best correlated with the observed frequency shifts. C1 JET PROP LAB,SPACE PHYS & ASTROPHYS SECT,PASADENA,CA 91109. UNIV SO CALIF,DEPT ASTRON,LOS ANGELES,CA 90089. UNIV ROMA LA SAPIENZA,DEPT PHYS,I-00185 ROME,ITALY. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP RHODES, EJ (reprint author), UNIV CALIF SANTA BARBARA,INST THEORET PHYS,SANTA BARBARA,CA 93106, USA. NR 24 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 APR 1 PY 1993 VL 406 IS 2 BP 714 EP 722 DI 10.1086/172482 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU607 UT WOS:A1993KU60700036 ER PT J AU RICHARDSON, IG REAMES, DV AF RICHARDSON, IG REAMES, DV TI BIDIRECTIONAL SIMILAR-TO-1 MEV AMU(-1) ION INTERVALS IN 1973-1991 OBSERVED BY THE GODDARD-SPACE-FLIGHT-CENTER INSTRUMENTS ON IMP-8 AND ISEE-3/ICE SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE INTERPLANETARY MEDIUM; SOLAR WIND; SUN, PARTICLE EMISSION ID SOLAR ENERGETIC PARTICLES; MAGNETIC-FIELD STRUCTURE; INTERPLANETARY SHOCK; LOOP STRUCTURE; CLOUDS; EVENTS; PROTONS; 1-AU; WIND; DISTURBANCES AB A search has been made for bidirectional energetic ion flows (BIFs) in the solar wind at 1 AU during 1973-1991 using approximately 1 MeV amu-1 ion data from the Goddard Space Flight Center instruments on ISEE3/ICE and IMP8. Some 4000 intervals have been identified. These range in duration from approximately 15 minutes to over 60 hr (mean = 3 hr), corresponding to scale sizes from approximately 0.003 to >0.7 AU. The occurrence rate falls off exponentially with an e-folding duration of approximately 4 hr (approximately 0.05 AU). BIFs are observed more frequently around solar maximum, when they are observed approximately 12% of the time compared with approximately 5% at solar minimum. Intervals with durations greater than 4 hr are observed on average approximately every 3-4 days at solar maximum and every 2 weeks at solar minimum, with approximately 33% of these intervals following within 2 days of an interplanetary shock. Around 80% of previously reported bidirectional >35 keV ion flows, bidirectional solar wind electron heat fluxes, magnetic clouds and He enhancements, signatures attributed to the passage of coronal mass ejections (CMEs), show evidence of bidirectional >1 MeV amu-1 BIFs. Of the other 20%, around half are associated with low energetic ion fluxes, and the remainder with solar particle events and shock-accelerated ions which do not show bidirectional streaming. These various CME signatures and the >1 MeV amu-1 BIFs usually do not coincide exactly, however, and additional bidirectional ion events are identified. A one-to-one association between individual BIFs and CMEs does not occur. In particular, intermittent episodes of ion bidirectionality may occur during the passage of clear magnetic cloud signatures. Hence CME boundaries and durations may not be identified unambiguously from BIF observations. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP RICHARDSON, IG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 44 TC 34 Z9 34 U1 0 U2 1 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 APR PY 1993 VL 85 IS 2 BP 411 EP 432 DI 10.1086/191769 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU132 UT WOS:A1993KU13200007 ER PT J AU NAZAR, K GREENLEAF, JE PHILPOTT, D POHOSKA, E OLSZEWSKA, K KACIUBAUSCILKO, H AF NAZAR, K GREENLEAF, JE PHILPOTT, D POHOSKA, E OLSZEWSKA, K KACIUBAUSCILKO, H TI MUSCLE MITOCHONDRIAL DENSITY AFTER EXHAUSTIVE EXERCISE IN DOGS - PROLONGED RESTRICTED ACTIVITY AND RETRAINING SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID RAT SOLEUS MUSCLE; SKELETAL-MUSCLE; ULTRASTRUCTURAL-CHANGES; HINDLIMB SUSPENSION; TIME COURSE; ATROPHY; IMMOBILIZATION; ADAPTATIONS; HYPOKINESIA; MORPHOLOGY AB The effect of exhaustive treadmill exercise on mitochondrial density (MD) and ultrastructural changes in quadriceps femoris muscle was studied in 7 normal, healthy, male mongrel dogs (2-4 years, 15-20 kg) before and after restricted activity (RA) (2 months for 5 dogs, 5 months for 2 dogs), and following a subsequent 2-month exercise retraining period (2-months group). Mean (+/- S.E.) time to exhaustion in the 2-month group decreased from 177 +/- 11 min before to 90 +/- 16 min (DELTA = -49%, p < 0.05) after RA; retraining increased tolerance to 219 +/- 36 min (DELTA = + 24%, p < 0.05) above the pre-RA and 143% (p < 0.05) above the post-RA time. Post-RA exhaustion time in the 5-months group was 25 and 45 min (35 +/- 10 min). Muscle samples taken after RA showed abnormalities indicative of degeneration, which were reversed by retraining. Resting MD decreased (p < 0.05) from a control level of 27.8% to 14.7% (2 months) and 16.3% (5 months), and was restored to 27.1% (NS) after retraining. Exhaustive exercise caused an increase in MD under control conditions and after RA, but not following retraining. Disruption of mitochondria after exercise was evident after 5-months confinement. Factors causing mitochondrial changes and eventually their disruption during exercise after restricted activity are not related as much to the state of fatigue as to the pre-exercise quality of the muscle modified by disease or training. C1 NASA,AMES RES CTR,DIV LIFE SCI,HUMAN GRAVITAT PHYSIOL LAB 23911,MOFFETT FIELD,CA 94035. POLISH ACAD SCI,MED RES CTR,DEPT APPL PHYSIOL,PL-00730 WARSAW,POLAND. NR 29 TC 4 Z9 4 U1 1 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 APR PY 1993 VL 64 IS 4 BP 306 EP 313 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA KW246 UT WOS:A1993KW24600006 PM 8476371 ER PT J AU FERRANDO, AA GREEN, NR BARNES, KW WOODWARD, B AF FERRANDO, AA GREEN, NR BARNES, KW WOODWARD, B TI MICROWAVE DIGESTION PREPARATION AND ICP DETERMINATION OF BORON IN HUMAN PLASMA SO BIOLOGICAL TRACE ELEMENT RESEARCH LA English DT Article DE BORON; MICROWAVE DIGESTION; PLASMA BORON ID SPECTROSCOPY; LITHIUM AB A microwave digestion procedure, followed by Inductively Coupled Argon Plasma Spectroscopy, is described for the determination of boron (B) in human plasma. The National Institute of Standards and Technology (NIST) currently does not certify the concentration of B in any substance. The NIST citrus leaves 1572 (CL) Standard Reference Material (SRM) and wheat flour 1567a (WF) were chosen to determine the efficacy of digestion. CL and WF values compare favorably to those obtained from an open-vessel, wet digestion followed by ICP, and by neutron activation and mass spectrometric measurements. Plasma samples were oxidized by doubled-distilled ultrapure HNO3 in 120 mL PFA Teflon(TM) vessels. An MDS-81D microwave digestion procedure allows for rapid and relatively precise determination of B in human plasma, while limiting handling hazards and sources of contamination. C1 AUBURN UNIV,DEPT NUTR & FOOD SCI,AUBURN,AL 36849. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. FLORIDA DEPT AGR & CONSUMER SERV,BUR FOOD LAB,TALLAHASSEE,FL 32399. NR 11 TC 21 Z9 21 U1 0 U2 3 PU HUMANA PRESS INC PI TOTOWA PA 999 RIVERVIEW DRIVE SUITE 208, TOTOWA, NJ 07512 SN 0163-4984 J9 BIOL TRACE ELEM RES JI Biol. Trace Elem. Res. PD APR PY 1993 VL 37 IS 1 BP 17 EP 25 DI 10.1007/BF02789398 PG 9 WC Biochemistry & Molecular Biology; Endocrinology & Metabolism SC Biochemistry & Molecular Biology; Endocrinology & Metabolism GA KV745 UT WOS:A1993KV74500002 PM 7682826 ER PT J AU BAUM, BA BARKSTROM, BR AF BAUM, BA BARKSTROM, BR TI DESIGN AND IMPLEMENTATION OF A PROTOTYPE DATA SYSTEM FOR EARTH RADIATION BUDGET, CLOUD, AEROSOL, AND CHEMISTRY DATA SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID EXPERIMENT ERBE; CLIMATE AB The Earth Observing System (EOS) will collect data from a large number of satellite-borne instruments, beginning later in this decade. To make data accessible to the scientific community, NASA will build an EOS Data and Information System (EOSDIS). As an initial effort to accelerate the development of EOSDIS and to gain experience with such an information system, NASA and other agencies are working on a prototype system called Version 0 (V0). This effort will provide improved access to pre-EOS earth science data throughout the early EOSDIS period. Based on recommendations from the EOSDIS Science Advisory Panel, EOSDIS will have several distributed active archive centers (DAACs). Each DAAC will specialize in particular datasets. This paper describes work at the NASA Langley Research Center's (LaRC) DAAC. The Version 0 Langley DAAC began archiving and distributing existing datasets pertaining to the earth's radiation budget, clouds, aerosols, and tropospheric chemistry in late 1992. The primary goals of the LaRC VO effort are the following: 1. Enhance scientific use of existing data; 2. Develop institutional expertise in maintaining and distributing data; 3. Use institutional capability for processing data from previous missions such as the Earth Radiation Budget Experiment and the Stratospheric Aerosol and Gas Experiment to prepare for processing future EOS satellite data; 4. Encourage cooperative interagency and international involvement with datasets and research; 5. Incorporate technological hardware and software advances quickly. RP BAUM, BA (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. RI Baum, Bryan/B-7670-2011 OI Baum, Bryan/0000-0002-7193-2767 NR 17 TC 6 Z9 6 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD APR PY 1993 VL 74 IS 4 BP 591 EP 598 DI 10.1175/1520-0477(1993)074<0591:DAIOAP>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KY078 UT WOS:A1993KY07800004 ER PT J AU WEBSTER, L CHEN, JG FLORES, L TAN, S AF WEBSTER, L CHEN, JG FLORES, L TAN, S TI EXERCISE COUNTERMEASURE PROTOCOL MANAGEMENT EXPERT-SYSTEM SO COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE LA English DT Article DE EXPERT SYSTEM; EXERCISE COUNTERMEASURE PROTOCOL AB Exercise will be used primarily to countermeasure against deconditioning on extended space flight. In this paper we describe the development and evaluation of an expert system for exercise countermeasure protocol management. Currently, the system includes two major subsystems: baseline prescription and prescription adjustment. The baseline prescription subsystem is designed to provide initial exercise prescriptions while prescription adjustment subsystem is designed to modify the initial prescription based on the exercised progress. The system runs under three different environments: PC, SUN workstation, and Symbolic machine. The inference engine, baseline prescription module, prescription adjustment module and explanation module are developed under the Symbolic environment by using the ART (Automated Reasoning Tool) software. The Sun environment handles database management features and interfaces with PC environment to obtain physical and physiological data from exercise units on-board during the flight. Eight subjects' data have been used to evaluate the system performance by comparing the prescription of nine experienced exercise physiologists and the one prescribed by the expert system. The results of the validation test indicated that the performance of the expert system was acceptable. C1 UNIV HOUSTON,DEPT IND ENGN,HOUSTON,TX 77204. NASA,LYNDON B JOHNSON SPACE CTR,DIV AUTOMAT & ROBOT,HOUSTON,TX 77058. LOCKHEED ENGN SCI CO,HOUSTON,TX. NR 3 TC 2 Z9 3 U1 0 U2 0 PU ELSEVIER SCI IRELAND LTD PI CLARE PA CUSTOMER RELATIONS MANAGER, BAY 15, SHANNON INDUSTRIAL ESTATE CO, CLARE, IRELAND SN 0169-2607 J9 COMPUT METH PROG BIO JI Comput. Meth. Programs Biomed. PD APR PY 1993 VL 39 IS 3-4 BP 217 EP 223 DI 10.1016/0169-2607(93)90024-F PG 7 WC Computer Science, Interdisciplinary Applications; Computer Science, Theory & Methods; Engineering, Biomedical; Medical Informatics SC Computer Science; Engineering; Medical Informatics GA LF237 UT WOS:A1993LF23700008 PM 8334874 ER PT J AU BOZACK, MJ BESHEARS, RD AF BOZACK, MJ BESHEARS, RD TI THE EFFECTS OF EXPOSURE TEMPERATURE ON 2219-AL-CU ALLOY SURFACES IMMERSED IN NATURAL SEAWATER SO CORROSION SCIENCE LA English DT Article ID ALUMINUM-ALLOYS; SEA-WATER; ATMOSPHERIC CORROSION; CHEMICAL NATURE; PIT GROWTH; DISSOLUTION; METALS; FOILS; MEDIA AB Deposits which form on 2219 Al-Cu alloy surfaces during exposure to natural seawater as a function of temperature have been investigated by surface and thin film techniques. Formation of aluminum oxide is favoured at T = 30-degrees-C; salt at T = 60-degrees-C; magnesium oxide at T = 100-degrees-C. Smaller concentrations of other chlorides and sulfates are also observed. Effects due to X-ray sampling depth and electron-stimulated desorption complicate the identification of surface compounds. C1 NASA,MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL. RP BOZACK, MJ (reprint author), AUBURN UNIV,DEPT PHYS,SPACE SCI LAB,AUBURN,AL 36849, USA. NR 50 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 0010-938X J9 CORROS SCI JI Corrosion Sci. PD APR PY 1993 VL 34 IS 4 BP 631 EP 653 DI 10.1016/0010-938X(93)90277-N PG 23 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA KV230 UT WOS:A1993KV23000008 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI HOTSPOTS AND SUNSPOTS - SURFACE TRACERS OF DEEP MANTLE CONVECTION IN THE EARTH AND SUN SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID POLAR WANDER; FLOOD-BASALT; HOT SPOTS; VOLCANISM; PLUMES; MODELS; SUBDUCTION AB The pattern of new appearances of hotspots on the Earth is investigated using available age data. The worldwide total of Cenozoic and Mesozoic hotspots, predicted by extrapolation from the observed number of continental flood basalts, is approximately 40, in agreement with Crough's counts. There are found to be no true antipodal pairs. In one interpretation of the data, new appearances of hotspots occur first at high latitudes in both hemispheres and then migrate toward the equator; shortly before the migration cycle is finished, the next cycle begins. A relative deficiency of hotspots, however, is observed in very low equatorial and very high polar regions. In addition, hotspots occupy two large hemispherical groups in longitude that slowly drift in the same direction as the axial body rotation. An observed magnetic superchron seems to end when a new hotspot migration cycle in latitude begins; but consecutive superchrons show opposite polarity. Although the hotspot data are rather sparse, their suggested patterns resemble the well-known patterns of complexes of active regions on the Sun, as exemplified by proxy data, such as sunspots. Both the Earth and the Sun possess large convecting, rotating and magnetized mantles, in which the characteristic surface tracers are believed to reflect the patterns of convective phenomena very deep in the mantle (even though the tracers themselves-hotspots and sunspots-are certainly not analogs of each other). The present study supports existing theoretical ideas that the large-scale patterns of deep mantle convection in the Earth and Sun may fundamentally resemble each other, despite the enormous difference in their molecular viscosities. Magnetic polarity reversal histories also show close similarities in the two bodies, suggesting the operation of basically similar convective dynamos. However, the Sun has displayed no known analog of the Earth's magnetically disturbed intervals. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 48 TC 7 Z9 9 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD APR PY 1993 VL 116 IS 1-4 BP 1 EP 8 DI 10.1016/0012-821X(93)90041-7 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LA737 UT WOS:A1993LA73700001 ER PT J AU FOROUHAR, S KEO, S LARSSON, A KSENDZOV, A TEMKIN, H AF FOROUHAR, S KEO, S LARSSON, A KSENDZOV, A TEMKIN, H TI LOW-THRESHOLD CONTINUOUS OPERATION OF INGAAS/INGAASP QUANTUM-WELL LASERS AT SIMILAR-TO-2.0-MU-M SO ELECTRONICS LETTERS LA English DT Article DE SEMICONDUCTOR LASERS; LASERS ID MICRO-M AB The first low threshold continuous operation of InGaAs strained layer quantum well lasers at approximately 2.0 mum is reported. The threshold current density or 5 mum wide and 1.5 mm long ridge waveguide lasers was less than 380 A/cm2. The external differential quantum efficiency of 1 mm long lasers was as high as 15% and laser operation was observed at temperatures as high as 50-degrees-C The lasers are characterised by T0 = 54-degrees-C which is the highest characteristic temperature ever achieved at this wavelength in any material system. C1 CHALMERS UNIV TECHNOL,DEPT OPTOELECTR,S-41296 GOTHENBURG,SWEDEN. COLORADO STATE UNIV,DEPT ELECT ENGN,FT COLLINS,CO 80523. RP FOROUHAR, S (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 6 TC 25 Z9 25 U1 1 U2 2 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD APR 1 PY 1993 VL 29 IS 7 BP 574 EP 576 DI 10.1049/el:19930386 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA LB770 UT WOS:A1993LB77000002 ER PT J AU ELDERING, A LARSON, SM HALL, JR HUSSEY, KJ CASS, GR AF ELDERING, A LARSON, SM HALL, JR HUSSEY, KJ CASS, GR TI DEVELOPMENT OF AN IMPROVED IMAGE-PROCESSING BASED VISIBILITY MODEL SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID RADIATIVE-TRANSFER; PLANETARY-ATMOSPHERES; 2-STREAM AB An image processing based visibility model is presented in which model calculations are displayed as synthetic color photographs that have the appearance of a smog event. A theoretically based model for light scattering and absorption in a plane parallel atmosphere is used to determine sky color and to provide accurate prediction of skylight addition to the line of sight between the observer and objects in the field of view. Data for testing the visibility model are collected experimentally, including standard photographs of chosen vistas and measurements of the chemical composition and size distributions of the atmospheric aerosol. The model is verified by comparison against radiometer measurements as well as point by point comparison of actual photographs and synthetic images. It is shown that the image processing based visibility model performs well, producing representations of the sky color and objects in the field of view that are close to those seen in actual photographs. C1 CALTECH,DEPT ENVIRONM ENGN SCI,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. CALTECH,ENVIRONM QUAL LAB,PASADENA,CA 91125. NR 29 TC 25 Z9 25 U1 1 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD APR PY 1993 VL 27 IS 4 BP 626 EP 635 DI 10.1021/es00041a006 PG 10 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA KU952 UT WOS:A1993KU95200016 ER PT J AU CUTLER, AD BRADSHAW, P AF CUTLER, AD BRADSHAW, P TI STRONG VORTEX BOUNDARY-LAYER INTERACTIONS .1. VORTICES HIGH SO EXPERIMENTS IN FLUIDS LA English DT Article ID FREE-STREAM TURBULENCE; FLOW; DIVERGENCE; SYMMETRY; PLANES AB Detailed measurements with hot-wires and pressure probes are presented for the interaction between a turbulent longitudinal vortex pair with ''common flow'' down, and a turbulent boundary layer. The interaction has a larger value of the vortex circulation parameter, and therefore better represents many aircraft/vortex interactions, than those studied previously. The vortices move down towards the boundary layer, but only the outer parts of the vortices actually enter the it. Beneath the vortices the boundary layer is thinned by lateral divergence to the extent that it almost ceases to grow. Outboard of the vortices the boundary layer is thickened by lateral convergence. The changes in turbulence structure parameters in the boundary layer appear to be due to the effects of 'extra-rate-of-strain'' produced by lateral divergence (or convergence) and by free-stream turbulence. The effect of the interaction on the vortices (other than the inviscid effect of the image vortices below the surface) is small. The flow constitutes a searching test case for prediction methods for three-dimensional turbulent flows. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. RP CUTLER, AD (reprint author), GEORGE WASHINGTON UNIV,JIAFS,NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 27 TC 9 Z9 9 U1 1 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD APR PY 1993 VL 14 IS 5 BP 321 EP 332 PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA LB094 UT WOS:A1993LB09400005 ER PT J AU SMITH, WG MORSE, WW AF SMITH, WG MORSE, WW TI LARVAL DISTRIBUTION PATTERNS - EARLY SIGNALS FOR THE COLLAPSE RECOVERY OF ATLANTIC HERRING CLUPEA-HARENGUS IN THE GEORGES BANK AREA SO FISHERY BULLETIN LA English DT Article ID STOCK DISCRETENESS; MAINE; GROWTH; GULF; ABUNDANCE; FISHES AB Changing temporal and spatial distribution patterns of Atlantic herring Clupea harengus larvae collected off southern New England over two decades provided early signals of large-scale changes in adult spawning biomass that are now a matter of record. Four contrasting spawning patterns were evident during the 20 yr period. Each pattern covered successive multi-year intervals and reflected the corresponding status of the adult population. In 1971, spawning occurred throughout the Georges Bank/Nantucket Shoals/Massachusetts Bay study area. The principal spawning grounds of herring in the Gulf of Maine region were located on the Northeast Peak of Georges Bank. With the collapse of the Georges Bank fishery in 1976, spawning receded westward to Nantucket Shoals. By 1979, larvae occurred only in the Stellwagen Banks area of Massachusetts Bay, the smallest of the three subareas. After a 6yr hiatus, spawning beds on Nantucket Shoals were reoccupied in 1985. By 1988 spawning had advanced eastward to Cultivator Shoals on Georges Bank, but through 1990 we found no evidence of renewed spawning activity on the historically-prominent spawning beds on Northeast Peak. The rebuilding process was attributed to recolonization rather than resurgence. RP SMITH, WG (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 35 TC 19 Z9 22 U1 0 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 APR PY 1993 VL 91 IS 2 BP 338 EP 347 PG 10 WC Fisheries SC Fisheries GA LV380 UT WOS:A1993LV38000014 ER PT J AU HAYNES, EB AF HAYNES, EB TI STAGE-I ZOEAE OF LABORATORY-HATCHED LOPHOLITHODES-MANDTII (DECAPODA, ANOMURA, LITHODIDAE) SO FISHERY BULLETIN LA English DT Note RP HAYNES, EB (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 4 TC 7 Z9 7 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 APR PY 1993 VL 91 IS 2 BP 379 EP 381 PG 3 WC Fisheries SC Fisheries GA LV380 UT WOS:A1993LV38000018 ER PT J AU THOMAS, KL BLANFORD, GE KELLER, LP KLOCK, W MCKAY, DS AF THOMAS, KL BLANFORD, GE KELLER, LP KLOCK, W MCKAY, DS TI CARBON ABUNDANCE AND SILICATE MINERALOGY OF ANHYDROUS INTERPLANETARY DUST PARTICLES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID UNEQUILIBRATED ORDINARY CHONDRITES; MAJOR ELEMENT COMPOSITION; COMET; NUCLEUS; MICROPROBE; ALBEDO; HALLEY; COLOR AB We have studied nineteen anhydrous chondritic interplanetary dust particles (IDPs) using analytical electron microscopy. We have determined a method for quantitative light element EDX analysis of small particles and have applied these techniques to a group of IDPs. Our results show that some IDPs have significantly higher bulk carbon abundances than do carbonaceous chondrites. We have also identified a relationship between carbon abundance and silicate mineralogy in our set of anhydrous IDPs. In general, these particles are dominated by pyroxene, olivine, or a subequal mixture of olivine and pyroxene. The pyroxene-dominated IDPs have a higher carbon abundance than those dominated by olivines. Members of the mixed mineralogy IDPs can be grouped with either the pyroxene- or olivine-dominated particles based on their carbon abundance. The high carbon, pyroxene-dominated particles have primitive mineralogies and bulk compositions which show strong similarities to cometary dust particles. We believe that the lower carbon, olivine-dominated IDPs are probably derived from asteroids. Based on carbon abundances, the mixed-mineralogy group represents particles derived from either comets or asteroids. We believe that the high carbon, pyroxene-rich anhydrous IDPs are the best candidates for cometary dust. C1 UNIV HOUSTON CLEAR LAKE, HOUSTON, TX 77058 USA. INST PLANETOL, W-4400 MUNSTER, GERMANY. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP THOMAS, KL (reprint author), LOCKHEED ENGN & SCI CO, 2400 NASA RD, HOUSTON, TX 77058 USA. NR 35 TC 103 Z9 103 U1 1 U2 11 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD APR PY 1993 VL 57 IS 7 BP 1551 EP 1566 DI 10.1016/0016-7037(93)90012-L PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KY313 UT WOS:A1993KY31300012 PM 11539451 ER PT J AU BEATTIE, P DRAKE, M JONES, J LEEMAN, W LONGHI, J MCKAY, G NIELSEN, R PALME, H SHAW, D TAKAHASHI, E WATSON, B AF BEATTIE, P DRAKE, M JONES, J LEEMAN, W LONGHI, J MCKAY, G NIELSEN, R PALME, H SHAW, D TAKAHASHI, E WATSON, B TI TERMINOLOGY FOR TRACE-ELEMENT PARTITIONING SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Note ID COEFFICIENTS AB A self-consistent terminology for partitioning data is presented. Ratios of the concentration of a component in two phases are termed partition coefficients and given the symbol D. Ratios of partition coefficients are termed exchange coefficients and given the symbol K(D). The prefix ''bulk'' implies that these coefficients are weighted according to the proportions of coexisting phases. Bulk partition and bulk exchange coefficients are denoted by DBAR and K(D)BAR, respectively. C1 LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV HAWAII MANOA,DIV PLANETARY SCI,HONOLULU,HI 96822. RICE UNIV,DEPT GEOL & GEOPHYS,HOUSTON,TX 77251. RENSSELAER POLYTECH INST,DEPT EARTH & ENVIRONM SCI,TROY,NY 12180. MCMASTER UNIV,DEPT GEOL,HAMILTON L8S 4M1,ONTARIO,CANADA. TOKYO INST TECHNOL,MEGURO KU,TOKYO 152,JAPAN. MAX PLANCK INST CHEM,W-6500 MAINZ,GERMANY. COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. OREGON STATE UNIV,COLL OCEANOG,CORVALLIS,OR 97331. RP BEATTIE, P (reprint author), UNIV CAMBRIDGE,DEPT EARTH SCI,CAMBRIDGE CB2 3EQ,ENGLAND. NR 9 TC 90 Z9 93 U1 1 U2 12 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 APR PY 1993 VL 57 IS 7 BP 1605 EP 1606 DI 10.1016/0016-7037(93)90015-O PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KY313 UT WOS:A1993KY31300015 ER PT J AU CHAO, BF LIU, HS AF CHAO, BF LIU, HS TI THE EARTHS EQUATORIAL PRINCIPAL AXES AND MOMENTS OF INERTIA - REPLY SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Note RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 6 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD APR PY 1993 VL 113 IS 1 BP 270 EP 270 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KV466 UT WOS:A1993KV46600024 ER PT J AU ENGMAN, T AF ENGMAN, T TI REMOTE-SENSING - A DEVELOPING TECHNOLOGY FOR HYDROLOGY - PREFACE SO HYDROLOGICAL PROCESSES LA English DT Editorial Material RP ENGMAN, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0885-6087 J9 HYDROL PROCESS JI Hydrol. Process. PD APR-JUN PY 1993 VL 7 IS 2 BP 119 EP 119 DI 10.1002/hyp.3360070203 PG 1 WC Water Resources SC Water Resources GA KZ958 UT WOS:A1993KZ95800002 ER PT J AU VILAS, F HATCH, EC LARSON, SM SAWYER, SR GAFFEY, MJ AF VILAS, F HATCH, EC LARSON, SM SAWYER, SR GAFFEY, MJ TI FERRIC IRON IN PRIMITIVE ASTEROIDS - A 0.43-MU-M ABSORPTION FEATURE SO ICARUS LA English DT Article ID SPECTRA; SULFATES; EARTH; BELT C1 CENTENARY COLL LOUISIANA,DEPT PHYS,SHREVEPORT,LA 71104. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RENSSELAER POLYTECH INST,DEPT EARTH & ENVIRONM SCI,TROY,NY 12181. RP VILAS, F (reprint author), NASA,JOHNSON SPACE CTR SN3,HOUSTON,TX 77058, USA. NR 27 TC 47 Z9 47 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 APR PY 1993 VL 102 IS 2 BP 225 EP 231 DI 10.1006/icar.1993.1045 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LA761 UT WOS:A1993LA76100004 ER PT J AU COUSTENIS, A ENCRENAZ, T BEZARD, B BJORAKER, G GRANER, G DANGNHU, M ARIE, E AF COUSTENIS, A ENCRENAZ, T BEZARD, B BJORAKER, G GRANER, G DANGNHU, M ARIE, E TI MODELING TITANS THERMAL INFRARED-SPECTRUM FOR HIGH-RESOLUTION SPACE OBSERVATIONS SO ICARUS LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; CARBON-MONOXIDE; ATMOSPHERE; PROPYNE; INTENSITIES; ABUNDANCE; SYSTEM; ALLENE; REGION; BAND C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LAB PHYS MOLEC & APPLICAT,F-91405 ORSAY,FRANCE. RP COUSTENIS, A (reprint author), OBSERV PARIS,DEPT RECH SPATIALE,SECT MEUDON,F-92195 MEUDON,FRANCE. RI Bjoraker, Gordon/D-5032-2012 NR 45 TC 75 Z9 75 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 0019-1035 J9 ICARUS JI Icarus PD APR PY 1993 VL 102 IS 2 BP 240 EP 260 DI 10.1006/icar.1993.1047 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LA761 UT WOS:A1993LA76100006 ER PT J AU MICHELANGELI, DV TOON, OB HABERLE, RM POLLACK, JB AF MICHELANGELI, DV TOON, OB HABERLE, RM POLLACK, JB TI NUMERICAL SIMULATIONS OF THE FORMATION AND EVOLUTION OF WATER ICE CLOUDS IN THE MARTIAN ATMOSPHERE SO ICARUS LA English DT Article ID SOLAR OCCULTATION MEASUREMENTS; VERTICAL DISTRIBUTION; GENERAL-CIRCULATION; MARS; DUST; CYCLE; PARTICLES; AEROSOLS; NUCLEATION; PROFILES C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 49 TC 29 Z9 29 U1 3 U2 6 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 APR PY 1993 VL 102 IS 2 BP 261 EP 285 DI 10.1006/icar.1993.1048 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LA761 UT WOS:A1993LA76100007 ER PT J AU WAFF, CB AF WAFF, CB TI THE ROAD TO THE DEEP SPACE NETWORK SO IEEE SPECTRUM LA English DT Article RP WAFF, CB (reprint author), JET PROP LAB,TDA DSN,DOCUMENTAT GRP,PASADENA,CA 91109, USA. NR 10 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 0018-9235 J9 IEEE SPECTRUM JI IEEE Spectr. PD APR PY 1993 VL 30 IS 4 BP 50 EP 57 DI 10.1109/6.206623 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA KV185 UT WOS:A1993KV18500006 ER PT J AU MAGHAMI, PG JOSHI, SM AF MAGHAMI, PG JOSHI, SM TI SENSOR ACTUATOR PLACEMENT FOR FLEXIBLE SPACE STRUCTURES SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID LINEAR-MULTIVARIABLE SYSTEMS; ROOT LOCI; ZEROS AB A new approach for the placement of sensors and actuators in the active control of flexible space structures is developed. The approach converts the discrete nature of sensor and actuator positioning problem to a nonlinear programming optimization through approximation of the control forces and output measurements by spatially continuous functions. The locations of the sensors and actuators are optimized in order to move the transmission zeros of the system farther to the left of the imaginary axis. This criterion for sensor/actuator placement can be quite useful for optimal regulation and tracking problems, as well as for low authority controller designs. Two performance metrics are considered for the optimization and are applied to the sensor/actuator positioning of a large-order flexible space structure. RP MAGHAMI, PG (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 230,HAMPTON,VA 23665, USA. NR 17 TC 21 Z9 22 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD APR PY 1993 VL 29 IS 2 BP 345 EP 351 DI 10.1109/7.210073 PG 7 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KY174 UT WOS:A1993KY17400007 ER PT J AU KANTAK, AV AF KANTAK, AV TI A METHOD OF OBTAINING SIGNAL COMPONENTS OF RESIDUAL CARRIER SIGNAL WITH THEIR POWER CONTENT AND COMPUTER-SIMULATION SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Letter AB This paper presents a new algorithm to obtain all signal components of a residual carrier signal with any number of channels. The phase modulation type may be NRZ-L or split phase (Manchester). The algorithm also provides an easy way of obtaining the power contents of the signal components. Steps to recognize the signal components that influence the carrier tracking loop and the data tracking loop at the receiver are given. Finally, a computer program for numerical computation is also given. RP KANTAK, AV (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 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 APR PY 1993 VL 29 IS 2 BP 532 EP 540 DI 10.1109/7.210090 PG 9 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KY174 UT WOS:A1993KY17400024 ER PT J AU RAHMATSAMII, Y TULINTSEFF, AN AF RAHMATSAMII, Y TULINTSEFF, AN TI DIFFRACTION ANALYSIS OF FREQUENCY-SELECTIVE REFLECTOR ANTENNAS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB Frequency selective surface (FSS) reflector antennas are used in many dual-reflector antenna systems in order to provide multifrequency capabilities. In the past, the diffraction analysis of reflectors was based primarily on the assumption of a solid subreflector configuration and only the gain loss caused by the presence of the FSS subreflector was accounted for. In this paper, a unified computational technique is presented which allows the incorporation of the curved FSS geometry in the computation of the antenna radiation pattern. The scattered fields from an illuminated FSS reflector are formalized using Huygens' principle in such a way that the ''reflecting'' and the ''transparent'' FSS subreflector cases are treated identically and the thickness of the FSS subreflector remains arbitrary. The analysis utilizes local surface coordinates to describe the reflection/transmission matrices of the FSS subreflector where it is assumed that these matrices are available. In most cases one may use the local tangent plane for approximating the plane of the FSS in the local coordinate surface of the reflector. The paper demonstrates how the local curved coordinate system can be introduced in the diffraction modeling of FSS reflectors and its importance in accurately predicting the side-lobe and cross-polarization levels. Results of numerical simulations are presented for several FSS subreflector configurations. C1 JET PROP LAB,PASADENA,CA 91109. RP RAHMATSAMII, Y (reprint author), UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024, USA. NR 12 TC 37 Z9 38 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 APR PY 1993 VL 41 IS 4 BP 476 EP 487 DI 10.1109/8.220980 PG 12 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LJ350 UT WOS:A1993LJ35000010 ER PT J AU PRESTAGE, JD TJOELKER, RL WANG, RT DICK, GJ MALEKI, L AF PRESTAGE, JD TJOELKER, RL WANG, RT DICK, GJ MALEKI, L TI HG+ TRAPPED ION STANDARD WITH THE SUPERCONDUCTING CAVITY MASER OSCILLATOR SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article ID FREQUENCY STANDARDS; CLOCK AB The frequency stability of an atomic standard based on Hg-199+ ions confined in a hybrid RF/dc linear trap is described. The 40.5 GHz clock transition has been measured to be 17 mHz wide, representing a quality factor greater than 2 X 10(12). A 160 mHz line is used to steer the output of a 5 MHz crystal oscillator to obtain a stability of 2 x 10(-15) for 24 000 s averaging times. In a separate measurement, a 37 mHz line is used to steer the output of the superconducting cavity maser oscillator to reach 1 x 10(-15) stability at 10 000 s. RP PRESTAGE, JD (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 5 Z9 5 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 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD APR PY 1993 VL 42 IS 2 BP 200 EP 205 DI 10.1109/19.278549 PG 6 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LP755 UT WOS:A1993LP75500021 ER PT J AU CHOUDHURY, D FRERKING, MA BATELAAN, PD AF CHOUDHURY, D FRERKING, MA BATELAAN, PD TI A 200 GHZ TRIPLER USING A SINGLE BARRIER VARACTOR SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID WAVE MULTIPLIERS; MILLIMETER-WAVE; DIODES AB In this paper, we present results for a tripler to 200 GHz using a single barrier varactor (SBV). The performance of the tripler, over an output frequency range from 186 to 207 GHz, has been measured in a crossed waveguide mount. The theoretical performance of the device and the tripler mount have been calculated using large signal analysis. An overall efficiency of 2% was achieved with efficiency at the device of above 5%. A comparison of theoretical and measured results and a discussion of various losses in the mount and the varactor are presented. C1 JET PROP LAB,MICROWAVE OBSERV SYST SECT,PASADENA,CA 91109. RP CHOUDHURY, D (reprint author), JET PROP LAB,ADV DEVICES GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 24 Z9 25 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 1993 VL 41 IS 4 BP 595 EP 599 DI 10.1109/22.231651 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA LR942 UT WOS:A1993LR94200007 ER PT J AU STIMSON, PA DENGLER, RJ LEDUC, HG CYPHER, SR SIEGEL, PH AF STIMSON, PA DENGLER, RJ LEDUC, HG CYPHER, SR SIEGEL, PH TI A PLANAR QUASI-OPTICAL SIS RECEIVER SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID GHZ HETERODYNE RECEIVER; MILLIMETER WAVELENGTHS; MIXERS; NOISE; JUNCTIONS AB A novel planar, quasi-optical SIS receiver operating at 230 GHz is described. The receiver consists of a 2 x 5 array of half wave dipole antennas with niobium-aluminum oxide-niobium SIS junctions on a quartz dielectric-filled parabola. The 1.4 GHz intermediate frequency is coupled from the mixer via coplanar strip transmission lines and 4:1 balun transformers. The receiver is operated at 4.2 K in a liquid helium immersion cryostat. We report here accurate measurements of the performance of single untuned array receiver elements. A mixer noise temperature of 89 K DSB, receiver noise temperature of 156 K DSB and conversion loss of 8 dB into a matched load have been obtained. This mixer noise temperature is approximately a factor of two larger than that of current state of the art waveguide mixers using untuned single junctions at the same frequency. RP STIMSON, PA (reprint author), JET PROP LAB,SENSOR TECHNOL GRP,PASADENA,CA 91109, USA. NR 20 TC 4 Z9 4 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 1993 VL 41 IS 4 BP 609 EP 615 DI 10.1109/22.231654 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA LR942 UT WOS:A1993LR94200010 ER PT J AU FREDERICKSON, AR MULLEN, EG KERNS, KJ ROBINSON, PA HOLEMAN, EG AF FREDERICKSON, AR MULLEN, EG KERNS, KJ ROBINSON, PA HOLEMAN, EG TI THE CRRES-IDM SPACECRAFT EXPERIMENT FOR INSULATOR DISCHARGE PULSES SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID SURFACES; SCATHA AB The Internal Discharge Monitor (IDM) is designed to observe electrical pulses from common electrical insulators in space service. The characteristics of the instrument are described. The IDM was flown on the Combined Release and Radiation Effects Satellite (CRRES). The sixteen insulator samples included G10 circuit boards, FR4 and PTFE fiberglass circuit boards, FEP Teflon, alumina, and wires with common insulations. The samples are fully enclosed, mutually isolated, and space radiation penetrates 0.02 cm of aluminum before striking the samples. Published data in the literature provides a simple method for determining the flux of penetrating electrons. The pulse rate is compared to the penetrating flux of electrons. C1 BOSTON COLL,CHESTNUT HILL,MA 02167. CALTECH,JET PROPULS LAB,PASADENA,CA 91103. RP FREDERICKSON, AR (reprint author), USAF,PHILLIPS LAB GEOPHYS DIRECTORATE,BEDFORD,MA 01731, USA. NR 24 TC 15 Z9 16 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1993 VL 40 IS 2 BP 233 EP 241 DI 10.1109/23.212347 PG 9 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA LA062 UT WOS:A1993LA06200029 ER PT J AU SERAJI, H LONG, MK LEE, TS AF SERAJI, H LONG, MK LEE, TS TI MOTION CONTROL OF 7-DOF ARMS - THE CONFIGURATION CONTROL APPROACH SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article ID KINEMATICALLY REDUNDANT MANIPULATORS; OBSTACLE AVOIDANCE; IMPLEMENTATION; ROBOTS AB Graphics simulation and real-time implementation of configuration control schemes for a redundant 7-DOF Robotics Research arm are described. The arm kinematics and motion control schemes are described briefly. This is then followed by a description of a graphics simulation environment for 7-DOF arm control on the Silicon Graphics IRIS Workstation. Computer simulation results are presented to demonstrate elbow control, collision avoidance, and optimal joint movement as redundancy resolution goals for the 7-DOF arm. The laboratory setup for experimental validation of motion control of the 7-DOF Robotics Research arm is then described. The configuration control approach is implemented on a Motorola 68020/VME bus-based real-time controller, with elbow positioning for redundancy resolution. Experimental results demonstrate the efficacy of configuration control for real-time control of the 7-DOF arm. C1 JET PROP LAB,ROBOT SYST & ADV COMP TECHNOL SECT,PASADENA,CA 91109. RP SERAJI, H (reprint author), JET PROP LAB,ROBOT SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 42 Z9 43 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 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD APR PY 1993 VL 9 IS 2 BP 125 EP 139 DI 10.1109/70.238277 PG 15 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA LZ622 UT WOS:A1993LZ62200001 ER PT J AU GHOSN, LJ CALOMINO, AM BREWER, DN AF GHOSN, LJ CALOMINO, AM BREWER, DN TI ANALYTICAL STRESS INTENSITY SOLUTION FOR THE STABLE POISSON LOADED SPECIMEN SO INTERNATIONAL JOURNAL OF FRACTURE LA English DT Article AB An analytical calibration of the Stable Poisson Loaded (SPL) specimen is presented. The specimen configuration is similar to the ASTM E-561 compact-tension specimen with displacement controlled wedge loading used for R-curve determination. The crack mouth opening displacements (CMOD's) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and specimen. In this report, stress intensity factors, CMOD's, and crack displacement profiles, are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length thus making the SPL specimen configuration attractive for fracture testing of brittle, high modulus materials. C1 USA,LEWIS RES CTR,RES LAB,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP GHOSN, LJ (reprint author), SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOKPARK,OH 44142, USA. NR 12 TC 1 Z9 1 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0376-9429 J9 INT J FRACTURE JI Int. J. Fract. PD APR 1 PY 1993 VL 60 IS 3 BP 209 EP 220 DI 10.1007/BF00012509 PG 12 WC Materials Science, Multidisciplinary; Mechanics SC Materials Science; Mechanics GA LF651 UT WOS:A1993LF65100002 ER PT J AU ALIAHMAD, WY BISHOP, WL CROWE, TW REBEIZ, GM AF ALIAHMAD, WY BISHOP, WL CROWE, TW REBEIZ, GM TI A 250 GHZ PLANAR LOW-NOISE SCHOTTKY RECEIVER SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article ID MILLIMETER-WAVE MATERIALS AB A planar quasi-optical Schottky receiver based on the quasi-integrated horn antenna has been developed and tested over the 230-280 GHz bandwidth. The receiver consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended on a thin dielectric membrane in an etched-pyramidal horn cavity. The diode has a 1.2 mum anode diameter and a low parasitic capacitance due to the use of an etched surface channel. The antenna-mixer results in a measured DSB conversion loss and noise temperature at 258 GHz of 7.2dB +/- 0.5dB and 1310K +/- 70K, respectively, at room temperature. The design is compatible with SIS mixers, and the low cost of fabrication and simplicity makes it ideal for submillimeter-wave imaging arrays requiring a 10-20% bandwidth. C1 UNIV VIRGINIA,DEPT ELECT ENGN,SEMICOND DEVICE LAB,CHARLOTTESVILLE,VA 22901. RP ALIAHMAD, WY (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 11 TC 1 Z9 1 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 APR PY 1993 VL 14 IS 4 BP 737 EP 748 DI 10.1007/BF02084284 PG 12 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA KX639 UT WOS:A1993KX63900001 ER PT J AU GUGERTY, L AF GUGERTY, L TI THE USE OF ANALYTICAL MODELS IN HUMAN COMPUTER-INTERFACE DESIGN SO INTERNATIONAL JOURNAL OF MAN-MACHINE STUDIES LA English DT Article ID SUPERVISORY CONTROL-SYSTEMS; ARCHITECTURE; ACQUISITION; KNOWLEDGE; TASK C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. US NATL AERONAUT & SPACE ADM,JOHNSON SPACE CTR,HUMAN COMP INTERACT LAB,HOUSTON,TX 77058. NR 81 TC 2 Z9 2 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0020-7373 J9 INT J MAN MACH STUD PD APR PY 1993 VL 38 IS 4 BP 625 EP 660 DI 10.1006/imms.1993.1030 PG 36 WC Computer Science, Cybernetics; Ergonomics; Psychology SC Computer Science; Engineering; Psychology GA LB120 UT WOS:A1993LB12000005 ER PT J AU YAMAMOTO, Y INOUE, S RICHARDSON, W MACHIDA, S AF YAMAMOTO, Y INOUE, S RICHARDSON, W MACHIDA, S TI QUANTUM STATE CONTROL IN SEMICONDUCTOR-P-N JUNCTIONS .1. SQUEEZED STATE GENERATION IN SEMICONDUCTOR-LASERS SO INTERNATIONAL JOURNAL OF MODERN PHYSICS B LA English DT Article ID EXTERNAL-FIELD FLUCTUATIONS; NOISE SUPPRESSION; OSCILLATOR; LIGHT; UNCERTAINTY; INJECTION AB Quantum statistical properties of laser light have been extensively studied for the last thirty years by using an operator Langevin equation, a density operator master equation, and a quantum mechanical Fokker-Planck equation. It has been generally accepted among physicists and quantum electronics engineers that an ideal laser operating at far above the threshold generates a coherent state of light. Various experimental facts such as the Poissonian photoelectron statistics, the shot noise limited photocurrent fluctuations, and the Gaussian distributions of optical homodyne detector output seem to support this. However, recent careful studies on a semiconductor laser have revealed that a semiconductor laser does not necessarily produce a coherent state of light, but generates a number-phase squeezed state, in which the photon-number noise is smaller than the standard quantum limit (shot noise limit or Poisson limit). This paper reviews the theoretical and experimental aspects of number-phase squeezed state generation by a semiconductor laser. C1 WASEDA UNIV, TOKYO 160, JAPAN. JET PROP LAB, PASADENA, CA 91109 USA. RP YAMAMOTO, Y (reprint author), NIPPON TELEGRAPH & TEL PUBL CORP, BASIC RES LABS, 3-9-11 MIDORI CHO, MUSASHINO, TOKYO 180, JAPAN. RI Yamamoto, Yoshihisa/A-2811-2012 NR 62 TC 5 Z9 5 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0217-9792 EI 1793-6578 J9 INT J MOD PHYS B JI Int. J. Mod. Phys. B PD APR 1 PY 1993 VL 7 IS 8 BP 1577 EP 1652 DI 10.1142/S021797929300250X PG 76 WC Physics, Applied; Physics, Condensed Matter; Physics, Mathematical SC Physics GA LE728 UT WOS:A1993LE72800001 ER PT J AU VANDEGRIEND, AA OWE, M AF VANDEGRIEND, AA OWE, M TI ON THE RELATIONSHIP BETWEEN THERMAL EMISSIVITY AND THE NORMALIZED DIFFERENCE VEGETATION INDEX FOR NATURAL SURFACES SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID DAILY EVAPOTRANSPIRATION; MONITORING VEGETATION; SOIL-MOISTURE; IR DATA; WATER; EVAPORATION; REFLECTANCE; TEMPERATURE AB The spatial variation of both the thermal emissivity (8-14 mum) and Normalized Difference Vegetation Index (NDVI) was measured for a series of natural surfaces within a savanna environment in Botswana. The measurements were performed with an emissivity-box and with a combined red and near-infrared radiometer, with spectral bands corresponding to NOAA/AVHRR. It was found that thermal emissivity was highly correlated with NDVI after logarithmic transformation, with a correlation coefficient of R=0.94. This empirical relationship is of potential use for energy balance studies using thermal infrared remote sensing. The relationship was used in combination with AVHRR (GAC), AVHRR (LAC), and Landsat (TM) data to demonstrate and compare the spatial variability of various spatial scales. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP VANDEGRIEND, AA (reprint author), FREE UNIV AMSTERDAM,INST EARTH SCI,DEBOELELAAN 1085,1081 HV AMSTERDAM,NETHERLANDS. NR 43 TC 254 Z9 258 U1 11 U2 58 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 APR PY 1993 VL 14 IS 6 BP 1119 EP 1131 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LG220 UT WOS:A1993LG22000008 ER PT J AU KAUFMAN, YJ NAKAJIMA, T AF KAUFMAN, YJ NAKAJIMA, T TI EFFECT OF AMAZON SMOKE ON CLOUD MICROPHYSICS AND ALBEDO - ANALYSIS FROM SATELLITE IMAGERY SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SOLAR-RADIATION MEASUREMENTS; EFFECTIVE PARTICLE RADIUS; OPTICAL-THICKNESS; CLIMATE CHANGE; FOSSIL-FUEL; EMISSIONS; AEROSOLS; POLLUTION; BRAZIL; ATMOSPHERE AB NOAA Advanced Very High Resolution Radiometer images taken over the Brazilian Amazon Basin during the biomass burning season of 1987 are used to study the effect of smoke aerosol Particles on the properties of low cumulus and stratocumulus clouds. The reflectance at a wavelength of 0.64 mum and the drop size, derived from the cloud reflectance at 3.75 mum, are studied for tens of thousands of clouds. The opacity of the smoke layer adjacent to each cloud is also monitored simultaneously. Though from satellite data it is impossible to derive all the parameters that influence cloud properties and smoke-cloud interaction (e.g., detailed aerosol particles size distribution and chemistry, liquid water content. etc.); satellite data can be used to generate large-scale statistics of the properties of clouds and surrounding aerosol (e.g., smoke optical thickness, cloud-drop size, and cloud reflection of solar radiation) from which the interaction of aerosol with clouds can be surmised. In order to minimize the effect of variations in the precipitable water vapor and in other smoke and cloud properties, biomass burning in the tropics is chosen as the study topic. and the results are averaged for numerous clouds with the same ambient smoke optical thickness. It is shown in this study that the presence of dense smoke (an increase in the optical thickness from 0.1 to 2.0) can reduce the remotely sensed drop size of continental cloud drops from 15 to 9 mum. Due to both the high initial reflectance of clouds in the visible part of the spectrum and the presence of graphitic carbon, the average cloud reflectance at 0.64 mum is reduced from 0.71 to 0.68 for an increase in smoke optical thickness from 0.1 to 2.0. The measurements are compared to results from other years, and it is found that, as predicted, high concentration of aerosol particles causes a decrease in the cloud-drop size and that smoke darkens the bright Amazonian clouds. Comparison with theoretical computations based on Twomey's model show that by using the measured reduction in the cloud-drop size due to the presence of smoke it is possible to explain the reduction in the cloud reflectance at 0.64 mum for smoke imagery index of -0.02 to -0.03. Smoke particles are hygroscopic and have a similar size distribution to maritime and anthropogenic sulfuric aerosol particles. Therefore, these results may also be representative of the interaction of sulfuric particles with clouds. C1 UNIV TOKYO,CTR CLIMATE SYST RES,BUNYO KU,TOKYO 113,JAPAN. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 913,GREENBELT,MD 20771, USA. RI Nakajima, Teruyuki/H-2370-2013 OI Nakajima, Teruyuki/0000-0002-9042-504X NR 65 TC 178 Z9 188 U1 5 U2 12 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD APR PY 1993 VL 32 IS 4 BP 729 EP 744 DI 10.1175/1520-0450(1993)032<0729:EOASOC>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KW381 UT WOS:A1993KW38100013 ER PT J AU CHOI, YH MERKLE, CL AF CHOI, YH MERKLE, CL TI THE APPLICATION OF PRECONDITIONING IN VISCOUS FLOWS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID INCOMPRESSIBLE-FLOW; EQUATIONS; SCHEMES; LAYER C1 PENN STATE UNIV,DEPT MECH ENGN,UNIV PK,PA 16802. RP CHOI, YH (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 26 TC 291 Z9 317 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD APR PY 1993 VL 105 IS 2 BP 207 EP 223 DI 10.1006/jcph.1993.1069 PG 17 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA KU501 UT WOS:A1993KU50100003 ER PT J AU RUMSEY, CL VAN LEER, B ROE, PL AF RUMSEY, CL VAN LEER, B ROE, PL TI A MULTIDIMENSIONAL FLUX FUNCTION WITH APPLICATIONS TO THE EULER AND NAVIER-STOKES EQUATIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID DIFFERENCE C1 UNIV MICHIGAN, ANN ARBOR, MI 48109 USA. RP NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 16 TC 28 Z9 28 U1 0 U2 3 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 EI 1090-2716 J9 J COMPUT PHYS JI J. Comput. Phys. PD APR PY 1993 VL 105 IS 2 BP 306 EP 323 DI 10.1006/jcph.1993.1077 PG 18 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA KU501 UT WOS:A1993KU50100011 ER PT J AU FLOWERS, GT RYAN, SG AF FLOWERS, GT RYAN, SG TI DEVELOPMENT OF A SET OF EQUATIONS FOR INCORPORATING DISK FLEXIBILITY EFFECTS IN ROTORDYNAMIC ANALYSES SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL ID BEAM AB Rotordynamic equations that account for disk flexibility are developed. These equations employ free-free rotor modes to model the rotor system. Only transverse vibrations of the disks are considered, with the shaft/disk system considered to be torsionally rigid. Second-order elastic foreshortening effects that couple with the rotor speed to produce first-order terms in the equations of motion are included. The approach developed in this study is readily adaptable for usage in many of the codes that are currently used in rotordynamic simulations. The equations are similar to those used in standard rigid disk analyses but with additional terms that include the effects of disk flexibility. An example case is presented to demonstrate the use of the equations and to show the influence of disk flexibility on the rotor dynamic behavior of a sample system. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP FLOWERS, GT (reprint author), AUBURN UNIV,DEPT MECH ENGN,AUBURN,AL 36849, USA. NR 26 TC 16 Z9 16 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 227 EP 233 DI 10.1115/1.2906698 PG 7 WC Engineering, Mechanical SC Engineering GA KZ489 UT WOS:A1993KZ48900003 ER PT J AU CHAMIS, CC SINGHAL, SN AF CHAMIS, CC SINGHAL, SN TI COUPLED MULTIDISCIPLINARY SIMULATION OF COMPOSITE ENGINE STRUCTURES IN PROPULSION ENVIRONMENT SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL AB A computational simulation procedure is described for the coupled response of multilayered multimaterial composite engine structural components that are subjected to simultaneous multidisciplinary thermal, structural, vibration, and acoustic loading including the effect of hostile environments. The simulation is based on a three-dimensional finite element analysis technique in conjunction with structural mechanics codes and with the acoustic analysis methods. The composite material behavior is assessed at the various composite scales, i. e., the laminate/ply/fiber and matrix constituents, via a nonlinear material characterization model. Sample cases exhibiting nonlinear geometric, material, loading, and environmental behavior of aircraft engine fan blades are presented. Results for deformed shape, vibration frequencies, mode shapes, and acoustic noise emitted from the fan blade are discussed for their coupled effect in hot and humid environments. Results such as acoustic noise for coupled composite-mechanics/heat transfer/structural/vibration/acoustic analyses demonstrate the effectiveness of coupled multidisciplinary computational simulation and the various advantages of composite materials compared to metals. C1 SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP CHAMIS, CC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 9 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 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 300 EP 306 DI 10.1115/1.2906709 PG 7 WC Engineering, Mechanical SC Engineering GA KZ489 UT WOS:A1993KZ48900014 ER PT J AU LIN, RR PALAZZOLO, AB KASCAK, AF MONTAGUE, GT AF LIN, RR PALAZZOLO, AB KASCAK, AF MONTAGUE, GT TI ELECTROMECHANICAL SIMULATION AND TESTING OF ACTIVELY CONTROLLED ROTORDYNAMIC SYSTEMS WITH PIEZOELECTRIC ACTUATORS SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL AB Past research on this subject has treated Piezoelectric actuators as ideal devices that have tip displacements proportional to their input voltages, at any instant in time. This assumption neglected phase lag and amplitude change at high frequencies. This characteristic of any actuator may lead to coupled control system-structural system instability that limits the amount of active stiffness or active damping that can be obtained. The paper presents a method for simulating the coupled ''electromechanical'' system to predict rotordynamic stability and unbalance response along with control system stability. The piezoelectric actuators and their amplifiers are represented as equivalent linear electrical circuits. The electromechanical system modeling approach is utilized to correlate test results from a double overhung rotor rig at NASA Lewis. The test results also show the effectiveness of the control system for suppressing the unbalance response of two modes using active stiffness and active damping. C1 TEXAS A&M UNIV SYST,COLL STN,TX 77843. USA,NASA LEWIS,CLEVELAND,OH 44135. SVERDRUP,NASA LEWIS,CLEVELAND,OH 44135. NR 20 TC 9 Z9 9 U1 1 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 324 EP 335 DI 10.1115/1.2906712 PG 12 WC Engineering, Mechanical SC Engineering GA KZ489 UT WOS:A1993KZ48900017 ER PT J AU RASHIDI, M DIRUSSO, E AF RASHIDI, M DIRUSSO, E TI DESIGN OF A HYDRAULIC ACTUATOR FOR ACTIVE CONTROL OF ROTATING MACHINERY SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL AB A hydraulic actuator was designed and is described herein. This actuator consists of: a pump, which generates the nominal pressure, a hydraulic servovalve, and a thin elastic plate, which transduces the generated pressure variations into forces acting on a mass, which simulates the bearing of a rotor system. An actuator characteristic number is defined to provide a base for an optimum design of force actuators with combined weight, frequency, and force considerations. This characteristic number may also be used to compare hydraulic and electromagnetic force actuators. In tests this actuator generated 182.3 N force at a frequency of 100. Hz. and a displacement amplitude of 5.8 x 10(-5) m. C1 NASA,LEWIS RES CTR,STRUCT DYNAM BRANCH,CLEVELAND,OH 44135. RP RASHIDI, M (reprint author), CLEVELAND STATE UNIV,DEPT MECH ENGN,CLEVELAND,OH 44135, USA. NR 4 TC 4 Z9 4 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 336 EP 340 DI 10.1115/1.2906713 PG 5 WC Engineering, Mechanical SC Engineering GA KZ489 UT WOS:A1993KZ48900018 ER PT J AU CARLILE, JA HENDRICKS, RC YODER, DA AF CARLILE, JA HENDRICKS, RC YODER, DA TI BRUSH SEAL LEAKAGE PERFORMANCE WITH GASEOUS WORKING FLUIDS AT STATIC AND LOW ROTOR SPEED CONDITIONS SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 36TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 03-06, 1991 CL ORLANDO, FL AB The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was investigated. This report includes the leakage results for air, helium, and carbon dioxide at several bristle/rotor interferences. In addition, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were investigated. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3. 792 cm ( 1. 4930 in. ), a fence height of 0. 0635 cm (0. 025 in. ), and 1800 bristles/cm-circumference (4500 bristles/in. -circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison with the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times when compared to a nonlubricated brush seal. The air and carbon dioxide data were successfully correlated using the corresponding state theory. However, the helium data followed a different curve from the air and carbon dioxide data. RP CARLILE, JA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 19 TC 11 Z9 12 U1 0 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 397 EP 403 DI 10.1115/1.2906722 PG 7 WC Engineering, Mechanical SC Engineering GA KZ489 UT WOS:A1993KZ48900027 ER PT J AU NOOR, AK HADIAN, MJ ANDERSEN, CM AF NOOR, AK HADIAN, MJ ANDERSEN, CM TI HYBRID ANALYTICAL TECHNIQUE FOR NONLINEAR VIBRATION ANALYSIS OF THIN-WALLED-BEAMS SO JOURNAL OF ENGINEERING MECHANICS-ASCE LA English DT Article ID FINITE-ELEMENT APPROACH; RITZ METHOD; FORMULATION AB A two-step hybrid analytical technique is presented for the nonlinear vibration analysis of thin-walled beams. The first step involves the generation of various-order perturbation functions using the Linstedt-Poincare perturbation technique. The second step consists of using the perturbation functions as coordinate (or approximation) functions and then computing both the amplitudes of these functions and the nonlinear frequency of vibration via a direct variational procedure. The analytical formulation is based on a form of the geometrically nonlinear beam theory with the effects of in-plane inertia, rotatory inertia, and transverse shear deformation included. The effectiveness of the proposed technique is demonstrated by means of a numerical example of thin-walled beam with a doubly symmetric I-section. The solutions obtained using a single-spatial mode were compared with those obtained using multiple-spatial modes. The standard of comparison was taken to be the frequencies obtained by the direct integration/fast Fourier transform (FFT) technique. The nonlinear frequencies obtained by the hybrid technique were shown to converge to the corresponding ones obtained by the direct integration/fast Fourier transform (FFT) technique well beyond the range of applicability of the perturbation technique. The frequencies and total strain energy of the beam were overestimated by using a single-spatial mode. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMP STRUCT TECH,HAMPTON,VA 23681, USA. NR 32 TC 1 Z9 1 U1 0 U2 1 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9399 J9 J ENG MECH-ASCE JI J. Eng. Mech.-ASCE PD APR PY 1993 VL 119 IS 4 BP 786 EP 800 DI 10.1061/(ASCE)0733-9399(1993)119:4(786) PG 15 WC Engineering, Mechanical SC Engineering GA KT971 UT WOS:A1993KT97100009 ER PT J AU SPALART, PR WATMUFF, JH AF SPALART, PR WATMUFF, JH TI EXPERIMENTAL AND NUMERICAL STUDY OF A TURBULENT BOUNDARY-LAYER WITH PRESSURE-GRADIENTS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NAVIER-STOKES EQUATIONS; MODEL; WALL; FLOW; SIMULATION AB The boundary layer develops along a flat plate with a Reynolds number high enough to sustain turbulence and allow accurate experimental measurements, but low enough to allow a direct numerical simulation. A favourable pressure gradient just downstream of the trip (experiment) or inflow boundary (simulation) helps the turbulence to mature without unduly increasing the Reynolds number. The pressure gradient then reverses, and the beta-parameter rises from -0.3 to +2. The wall-pressure distribution and Reynolds number of the simulation are matched to those of the experiment, as are the gross characteristics of the boundary layer at the inflow. This information would be sufficient to calculate the flow by another method. Extensive automation of the experiment allows a large measurement grid with long samples and frequent calibration of the hot wires. The simulation relies on the recent 'fringe method' with its numerical advantages and good inflow quality. After an inflow transient good agreement is observed: the differences. of up to 13%, are discussed. Moderate deviations from the law of the wall are found in the velocity profiles of the simulation. They are fully correlated with the pressure gradient, are in fair quantitative agreement with experimental results of Nagano, Tagawa & Tsuji, and are roughly the opposite of uncorrected mixing-length-model predictions. Large deviations from wall scaling are observed for other quantities. notably for the turbulence dissipation rate. The a1 structure parameter drops mildly in the upper layer with adverse pressure gradient. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NASA, STANFORD CTR TURBULENCE RES, STANFORD, CA 94305 USA. NR 48 TC 168 Z9 171 U1 1 U2 35 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 APR PY 1993 VL 249 BP 337 EP 371 DI 10.1017/S002211209300120X PG 35 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KZ447 UT WOS:A1993KZ44700016 ER PT J AU BASSOM, AP OTTO, SR AF BASSOM, AP OTTO, SR TI WEAKLY NONLINEAR STABILITY OF VISCOUS VORTICES IN 3-DIMENSIONAL BOUNDARY-LAYERS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID GORTLER VORTICES AB Recently it has been demonstrated that three-dimensionality can play an important role in dictating the stability of any Gortler vortices which a particular boundary layer may support. According to a linearized theory, vortices within a high Gortler number flow can take one of two possible forms within a two-dimensional flow supplemented by a small crossflow of size O(Re-1/2G3/5), where Re is the Reynolds number of the flow and G the Gortler number. Bassom & Hall (1991) showed that these forms are characterized by O(1)-wavenumber inviscid disturbances and larger O(G1/5)-wave-number modes which are trapped within a thin layer adjacent to the bounding surface. Here we concentrate on the latter, essentially viscous, vortices. These modes are unstable in the absence of crossflow but the imposition of small crossflow has a stabilizing effect. Bassom & Hall (1991) demonstrated the existence of neutrally stable vortices for certain crossflow/wavenumber combinations and here we describe the weakly nonlinear stability properties of these disturbances. It is shown conclusively that the effect of crossflow is to stabilize the nonlinear modes and the calculations herein allow stable finite-amplitude vortices to be found. Predictions are made concerning the likelihood of observing some of these viscous modes within a practical setting and asymptotic work permits discussion of the stability properties of modes with wavenumbers that are small relative to the implied O(G1/5) scaling. C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665. RP BASSOM, AP (reprint author), UNIV EXETER,DEPT MATH,N PK RD,EXETER EX4 4QE,DEVON,ENGLAND. RI Bassom, Andrew/F-6691-2014 NR 16 TC 5 Z9 5 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 APR PY 1993 VL 249 BP 597 EP 618 DI 10.1017/S0022112093001302 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KZ447 UT WOS:A1993KZ44700026 ER PT J AU LUHMANN, JG ZHANG, TL PETRINEC, SM RUSSELL, CT GAZIS, P BARNES, A AF LUHMANN, JG ZHANG, TL PETRINEC, SM RUSSELL, CT GAZIS, P BARNES, A TI SOLAR CYCLE-21 EFFECTS ON THE INTERPLANETARY MAGNETIC-FIELD AND RELATED PARAMETERS AT 0.7 AND 1.0 AU SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LARGE-SCALE; WIND; IMF; EVOLUTION; 1-AU AB Magnetometer data obtained over the course of the previous solar cycle by the Pioneer Venus orbiter (PVO) at approximately 0.7 AU and IMP 8 at 1.0 AU are used to compare the long-term behavior of the interplanetary magnetic field (IMF) at these two heliocentric distances. Similarities include an enhancement in the typical or median field magnitude during the declining phase of the solar cycle as compared to solar maximum or minimum, slight decreases in the Parker spiral angle from the declining phase through solar minimum, similar trends in the Alfvenic and magnetosonic Mach numbers, and the remarkably consistent sector structure noted previously. Differences include the temporal behavior of the high-field tail of the field distribution, showing that high fields are most frequently observed during solar maximum at the Earth but during the declining phase of activity at Venus. This latter feature suggests that the perceived occurrence history of large fields from transient disturbances such as coronal mass ejections is a sensitive function of position within the heliosphere. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP LUHMANN, JG (reprint author), UNIV CALIF LOS ANGELES, INST GEOPHYS & PLANETARY PHYS, LOS ANGELES, CA 90024 USA. OI Russell, Christopher/0000-0003-1639-8298 NR 39 TC 45 Z9 46 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD APR 1 PY 1993 VL 98 IS A4 BP 5559 EP 5572 DI 10.1029/92JA02235 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300002 ER PT J AU VERMA, MK ROBERTS, DA AF VERMA, MK ROBERTS, DA TI THE RADIAL EVOLUTION OF THE AMPLITUDES OF DISSIPATIONLESS TURBULENT SOLAR-WIND FLUCTUATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HELIOSPHERE AB We examine the evolution with heliocentric distance of the amplitude of fluctuations in the interplanetary magnetic and velocity fields assuming a model of homogeneous, steady state turbulence. Based on observations and recent results, both the Alfven ratio and the normalized cross helicity are taken to be constant compared to other variations, and the turbulence is assumed to be nearly incompressive. The fluctuation amplitudes are found by taking the heating of the plasma by the fluctuations to be negligible; quasi-steady state turbulence with damping balanced by large-scale energy input will lead to the same conclusions for inertial range fluctuations. While the assumptions of this model contrast sharply with those for purely Alfvenic fluctuations, we find that the radial dependence of the amplitude of the fluctuations for reasonable parameters is very nearly that found from both WKB analysis and recent turbulence modeling. The robustness of this result suggests why some predictions of WKB theory are apparently correct in solar wind conditions where the theory is not expected to be valid. C1 UNIV MARYLAND, DEPT PHYS, COLL PK, MD 20742 USA. RP VERMA, MK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, CODE 692, GREENBELT, MD 20771 USA. RI Roberts, Dana/D-4625-2012; verma, mahendra/G-4041-2013 OI verma, mahendra/0000-0002-3380-4561 NR 21 TC 18 Z9 18 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 APR 1 PY 1993 VL 98 IS A4 BP 5625 EP 5630 DI 10.1029/92JA02398 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300007 ER PT J AU GURNETT, DA HOSPODARSKY, GB KURTH, WS WILLIAMS, DJ BOLTON, SJ AF GURNETT, DA HOSPODARSKY, GB KURTH, WS WILLIAMS, DJ BOLTON, SJ TI FINE-STRUCTURE OF LANGMUIR-WAVES PRODUCED BY A SOLAR ELECTRON EVENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID III RADIO-BURSTS; SPATIAL COLLAPSE; PLASMA-WAVES; WIND; EMISSIONS AB Highly structured bursts of Langmuir waves produced by energetic electrons ejected from a solar flare have been observed using wideband plasma wave measurements on the Galileo spacecraft. The wideband sampling system on Galileo provides digital electric field waveforms at sampling rates up to 201,600 samples s-1, much higher than any previous instrument of this type. The solar flare of interest occurred on December 10, 1990, while the spacecraft was at a radial distance of 0.98 AU from the Sun. This flare emitted a stream of energetic electrons and an associated type III radio event, both of which were detected by Galileo. Starting about 1 hour after the onset of the flare, a large number of intense Langmuir wave bursts were detected near the local electron plasma frequency, which was about 25 kHz. The Langmuir wave bursts. which lasted about 1.5 hours, coincided with the arrival of the solar electrons. The bursts are highly structured and consist mainly of isolated wave packets with durations as short as 1 ms and beat-type waveforms with beat frequencies ranging from 200 to 500 Hz. The peak electric field strengths are about 1.7 mV m-1. The highly structured envelopes of these waves are strongly suggestive of nonlinear parametric decay processes such as those predicted by various theories dealing with the saturation of beam-driven electrostatic instabilities. However, the intensities are too low for strong turbulence effects to be important. C1 JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. JET PROP LAB,PASADENA,CA 91109. RP GURNETT, DA (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. NR 41 TC 77 Z9 77 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 APR 1 PY 1993 VL 98 IS A4 BP 5631 EP 5637 DI 10.1029/92JA02838 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300008 ER PT J AU TSYGANENKO, NA AF TSYGANENKO, NA TI A GLOBAL ANALYTICAL REPRESENTATION OF THE MAGNETIC-FIELD PRODUCED BY THE REGION-2 BIRKELAND CURRENTS AND THE PARTIAL RING CURRENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID QUANTITATIVE MODELS AB A quantitative model is developed of the magnetic field produced by the electric current system of region 2 Birkeland currents, closed via the partial ring current. The distribution of j(perpendicular-to) is computed from a given axially asymmetric spatial distribution of hot isotropic magnetospheric plasma over an infinitely thin L shell in an axisymmetric purely dipolar geomagnetic field, while the field-aligned current density is found from the continuity of the net electric current. The magnetic field distribution is derived by a Biot-Savart integral over the electric current system. An assumed cosine dependence of the plasma pressure on local time makes it possible to reduce the problem of analytical representation of the B field to two dimensions, The obtained numerical fits for the partial ring current/region 2 Birkeland current magnetic field are relatively simple, continuous, and valid throughout the whole extraterrestrial space from ionospheric heights up to tens of R(E). To our knowledge, this is a first global analytical representation for the magnetic field of the partial ring current system which can be incorporated in future advanced models of the external geomagnetic field. C1 UNIV ST PETERSBURG,INST PHYS,STARY PETERGOF,ST PETERSBURG 198904,RUSSIA. RP TSYGANENKO, NA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 14 TC 25 Z9 25 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 JI J. Geophys. Res-Space Phys. PD APR 1 PY 1993 VL 98 IS A4 BP 5677 EP 5690 DI 10.1029/92JA02002 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300012 ER PT J AU STERN, DP AF STERN, DP TI A SIMPLE-MODEL OF BIRKELAND CURRENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; LARGE-SCALE CHARACTERISTICS; GEOMAGNETIC-FIELD; MAGNETIC-FIELDS; GROWTH-PHASE; MAGNETOSPHERE; TRIAD; SHEET AB A simple representation of the global circuit of Birkeland currents is developed, based on a representation of the current density j in terms of Euler potentials (alpha,chi). The underlying magnetic field, which shares with j the potential alpha, is assumed to be dipolar, making the model applicable mainly to region 2 Birkeland currents, although a similar approach could also be used for region 1. A form of j is chosen that gives a current sheet with peak outflow at dawn and peak inflow at dusk (or vice versa), connected across a flat polar cap sheet. The current is further assumed to flow in a thin layer enclosing the dipole fieldline surface L=10, and to close symmetrically across noon and midnight. To produce the asymmetry expected of the partial ring current, a (full) ring current j(RC) is added to the configuration, and a suitable function G(gamma) defining the currents was selected. The field of the current sheet is then numerically derived by Biot-Savart integration and the magnetic scalar potential PSI, which consists of a cosphi component and an axisymmetrical one, is approximated in three regions of space. It is found that the superposition of harmonics of the same type, centered at different ''foci,'' provided a flexible and powerful representation of harmonic functions, accurate here within less than 1%. Appendix A discusses the Euler potentials of the magnetic field B and Appendix B develops an interpolation formula by which current sheets of finite width could be consistently represented. Future plans are described for deforming configurations of this type to represent region 1 currents and for bypassing the tedious Biot-Savart integration. RP STERN, DP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. NR 29 TC 13 Z9 13 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 JI J. Geophys. Res-Space Phys. PD APR 1 PY 1993 VL 98 IS A4 BP 5691 EP 5706 DI 10.1029/92JA02003 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300013 ER PT J AU NAKAMURA, R OGUTI, T YAMAMOTO, T KOKUBUN, S AF NAKAMURA, R OGUTI, T YAMAMOTO, T KOKUBUN, S TI EQUATORWARD AND POLEWARD EXPANSION OF THE AURORAS DURING AURORAL SUBSTORMS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TWO-DIMENSIONAL OBSERVATIONS; WESTWARD TRAVELING SURGE; ELECTRIC-FIELDS; MAGNETOSPHERIC SUBSTORMS; ZONE CURRENTS; CURRENT FLOW; ONSET; SIGNATURES; PHASE; MAGNETOTAIL AB Using all-sky TV auroral data with high spatial and temporal resolution, the formation of the auroral bulge is investigated. We show how the discrete auroral structures within the poleward expanding bulge develop systematically toward the west, the east, and also equatorward from a localized breakup region. Auroral structure at the western end of the bulge (a surge) develops with clockwise rotation as viewed along the magnetic field direction. At the eastern part of the bulge, thin auroral features propagate eastward from the breakup region. Around the central meridian of the bulge, auroral features expand equatorward and become north-south aligned (the N-S aurora). The N-S aurora and the eastward propagating aurora develop into diffuse and pulsating aurora after the expansion. We suggest that these discrete auroral structures in the bulge develop along the plasma streamlines in a localized distorted two-cell equipotential distribution; the negative potential peak is concentrated at the western part of the bulge and the positive potential region is spread poleward of the eastward propagating aurora. Equatorward expansion of auroral structures would be attributed in this scenario to the subsequent earthward transport of plasma from the onset region. Energetic particles would also be injected at the N-S auroral region as well as to the east of the region and would trigger the pulsating auroral activity. Poleward expansion, on the other hand, would be produced by the tailward motion of the onset region in accordance with the tailward moving current disruption region. C1 NATL INST POLAR RES,TOKYO,TOKYO,JAPAN. NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA,AICHI 442,JAPAN. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. UNIV TOKYO,DEPT EARTH & PLANETARY PHYS,BUNKYO KU,TOKYO 113,JAPAN. RP NAKAMURA, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Nakamura, Rumi/I-7712-2013 OI Nakamura, Rumi/0000-0002-2620-9211 NR 45 TC 71 Z9 72 U1 0 U2 5 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 APR 1 PY 1993 VL 98 IS A4 BP 5743 EP 5759 DI 10.1029/92JA02230 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300016 ER PT J AU KOSKINEN, HEJ LOPEZ, RE PELLINEN, RJ PULKKINEN, TI BAKER, DN BOSINGER, T AF KOSKINEN, HEJ LOPEZ, RE PELLINEN, RJ PULKKINEN, TI BAKER, DN BOSINGER, T TI PSEUDOBREAKUP AND SUBSTORM GROWTH-PHASE IN THE IONOSPHERE AND MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HARANG DISCONTINUITY; ELECTRIC-FIELDS; MAGNETIC-FIELD; PLASMA SHEET; AURORAL-ZONE; SOLAR-WIND; MAGNETOTAIL; INSTABILITY; CURRENTS; ORBIT AB We present observations made in space and on the ground during the growth phase and the onset of a substorm on August 31, 1986. About 20 min after the epsilon parameter at the magnetopause had exceeded 10(11) W, magnetic field dipolarization with an increase of energetic particle fluxes was observed by the AMPTE Charge Composition Explorer (CCE) spacecraft at the geocentric distance of 8.7 R(E) close to magnetic midnight. The event exhibited local signatures of a substorm onset at AMPTE CCE and a weak wedgelike current system in the midnight sector ionosphere. However, it did not lead to a full-scale substorm expansion, as determined by several ground-based instruments, nor did it produce large particle injections at geostationary orbit. Only after another 20 min of continued growth phase the entire magnetosphere-ionosphere system could apparently allow the onset of a regular substorm expansion. The initial activation is interpreted in the present paper as a ''pseudobreakup.'' We examine the physical conditions in the near-Earth plasma sheet using spacecraft observations and analyze the development in the ionosphere using ground-based magnetometers and electric field observations from the STARE radar. We find that the main observable differences between pseudobreakups and ordinary breakups are the strength and consequences. Furthermore, it is shown that ionospheric activity at the time of a pseudobreakup is not necessarily as localized in longitude as generally believed. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. APPL RES CORP,LANDOVER,MD. UNIV OULU,DEPT PHYS,SF-90570 OULU,FINLAND. RP KOSKINEN, HEJ (reprint author), FINNISH METEROL INST,DEPT GEOPHYS,BOX 503,SF-00101 HELSINKI,FINLAND. RI Pulkkinen, Tuija/D-8403-2012; Koskinen, Hannu/B-4971-2017; OI Pulkkinen, Tuija/0000-0002-6317-381X; Koskinen, Hannu/0000-0003-3839-6461; Lopez, Ramon/0000-0001-5881-1365 NR 36 TC 117 Z9 117 U1 0 U2 5 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 APR 1 PY 1993 VL 98 IS A4 BP 5801 EP 5813 DI 10.1029/92JA02482 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300020 ER PT J AU MELENDEZALVIRA, DJ BURNSIDE, RG WALKER, JCG AF MELENDEZALVIRA, DJ BURNSIDE, RG WALKER, JCG TI MODELING THE ARECIBO NIGHTTIME F2 LAYER .1. OVERHEAD PROPERTIES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID OPTICAL OBSERVATIONS; EQUINOX TRANSITION; TOPSIDE IONOSPHERE; ELECTRIC-FIELDS; MID-LATITUDES; NEUTRAL WINDS; REGION; ION; THERMOSPHERE; DYNAMICS AB The servo model of Rishbeth et ai. (1978) is extended and applied to fit the height and plasma density of the nighttime F2 layer, as measured from the Arecibo Observatory in Puerto Rico during solar maximum by Burnside (1984). The model equations am integrated numerically to fit the observed peak height and density. specifically, the fitting is made by applying a theoretical zonal current (or drift), as needed so as to match the observed F2 peak. Morever, the applied current/drift employs the measured ion velocity. whereas the component due to the neutral wind is freely adjusted. An improvement over previous servo-model fits is made by considering the time variations in all the model neutral and plasma densities and temperatures. All the background neutral densities are obtained from the MSIS model (Hedin, 1987). The following results are obtained: (1) the model adequately reproduces the observed behavior of the F2 layer (2) the additional terms in the extended servo-height equation affect the peak height computation by no more than 10% on average; (3) the applied current is generally eastward though it becomes westward during the postmidnight collapse or descent of the layer (4) differences between model and optically measured meridional wind speeds appear to be related to the presence of large vertical shears in the wind; (5) the observed peak density can be reproduced to within 20% to 40% accuracy; and (6) variable plasmaspheric fluxes of the order of 10(13) (m-2 s-1) contribute to the maintenance and variability of the nighttime peak density. Also, horizontally divergent plasma fluxes remove plasma away from the local F2 peak; however, this is relatively minor. The overall model fit to the data is improved with the ion-neutral collision frequency increased by 70% (Burnside et al., 1987). C1 ARECIBO OBSERV,ARECIBO,PR 00612. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP MELENDEZALVIRA, DJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,CODE ES55,HUNTSVILLE,AL 35812, USA. NR 60 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 APR 1 PY 1993 VL 98 IS A4 BP 5993 EP 6011 DI 10.1029/92JA02790 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300037 ER PT J AU ANDERSON, PC HANSON, WB HEELIS, RA CRAVEN, JD BAKER, DN FRANK, LA AF ANDERSON, PC HANSON, WB HEELIS, RA CRAVEN, JD BAKER, DN FRANK, LA TI A PROPOSED PRODUCTION-MODEL OF RAPID SUBAURORAL ION DRIFTS AND THEIR RELATIONSHIP TO SUBSTORM EVOLUTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; DIRECTED ELECTRIC-FIELDS; SUB-AURORAL LATITUDES; PRECIPITATION; IONOSPHERE; CONVECTION; BOUNDARY; REGION AB Multisatellite data are used to examine the temporal relationship between Subauroral Ion Drifts (SAID) and the phases of an auroral substorm. Utilizing images of auroral luminosities taken by the Dynamics Explorer 1 (DE 1) spacecraft and observations of particle injection at geosynchronous chronous orbit, we identify the time of expansive phase onset and estimate the time at which recovery begins. Noting the times at which SAID are observed simultaneously by the DE 2 spacecraft, we find that SAID typically occur well after substorm onset (more than 30 min), during the substorm recovery phase. Substantial westward ion drifts and field-aligned currents are observed well equatorward of the auroral oval during the expansion phase of a substorm, but the drifts lack the narrow spike signature associated with SAID. Prior to substorm onset and after substorm recovery, field-aligned currents are absent equatorward of the auroral oval and the ionosphere is very nearly corotating. A phenomenological model of SAID production is proposed that qualitatively agrees with the observed ionospheric signatures and substorm temporal relationship. In this model, substorm-generated, subauroral field-aligned currents close via Pedersen currents with the outward flowing, region 1 currents at higher latitudes. These Pedersen currents flow in the region of low conductivity equatorward of the auroral oval and are associated with relatively large, poleward directed electric fields. The frictional heating of the ions caused by collisions with the corotating neutral atmosphere substantially increases the rate of ion-atom interchange between O+ and N2. Subsequent fast recombination of NO+ with electrons further reduces the subauroral F region conductivities with a corresponding increase in the electric field and the frictional heating. This heating leads to thermal expansion, substantial field-aligned plasma flow, and very large depletions in the F peak concentration, thus additionally reducing the height-integrated Pedersen conductivity. C1 UNIV TEXAS,CTR SPACE SCI,RICHARDSON,TX 75083. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775. UNIV ALASKA,DEPT PHYS,FAIRBANKS,AK 99775. RP ANDERSON, PC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 34 TC 124 Z9 125 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 JI J. Geophys. Res-Space Phys. PD APR 1 PY 1993 VL 98 IS A4 BP 6069 EP 6078 DI 10.1029/92JA01975 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KW003 UT WOS:A1993KW00300043 ER PT J AU CETIN, BC BARHEN, J BURDICK, JW AF CETIN, BC BARHEN, J BURDICK, JW TI TERMINAL REPELLER UNCONSTRAINED SUBENERGY TUNNELING (TRUST) FOR FASTGLOBAL OPTIMIZATION SO JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS LA English DT Article DE GLOBAL OPTIMIZATION; DYNAMICAL SYSTEMS; TERMINAL REPELLERS; SUBENERGY TUNNELING FUNCTION; ARTIFICIAL NEURAL NETWORKS ID GLOBAL OPTIMIZATION; NEURAL NETWORKS; ALGORITHM AB A new method for unconstrained global function optimization, acronymed TRUST, is introduced. This method formulates optimization as the solution of a deterministic dynamical system incorporating terminal repellers and a novel subenergy tunneling function. Benchmark tests comparing this method to other global optimization procedures are presented, and the TRUST algorithm is shown to be substantially faster. The TRUST formulation leads to a simple stopping criterion. In addition, the structure of the equations enables an implementation of the algorithm in analog VLSI hardware, in the vein of artificial neural networks, for further substantial speed enhancement. C1 JET PROP LAB, NONLINEAR SCI & INFORMAT PROC GRP, PASADENA, CA 91109 USA. CALTECH, DEPT MECH ENGN, PASADENA, CA 91125 USA. RP CETIN, BC (reprint author), CALTECH, DEPT ELECT ENGN, PASADENA, CA 91125 USA. NR 20 TC 81 Z9 91 U1 0 U2 1 PU SPRINGER/PLENUM PUBLISHERS PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-3239 J9 J OPTIMIZ THEORY APP JI J. Optim. Theory Appl. PD APR PY 1993 VL 77 IS 1 BP 97 EP 126 DI 10.1007/BF00940781 PG 30 WC Operations Research & Management Science; Mathematics, Applied SC Operations Research & Management Science; Mathematics GA LH844 UT WOS:A1993LH84400005 ER PT J AU MAY, RD WEBSTER, CR AF MAY, RD WEBSTER, CR TI DATA-PROCESSING AND CALIBRATION FOR TUNABLE DIODE-LASER HARMONIC ABSORPTION SPECTROMETERS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID OPTICAL HETERODYNE SPECTROSCOPY; FM SPECTROSCOPY; STRATOSPHERE; SPECTRA; HNO3; NO2 AB Data processing and calibration methods are described for tunable diode laser absorption spectrometers which produce harmonic absorption spectra as raw data for measuring gas mixing ratios down to parts-per-trillion levels at a variety of pressures. The methods, which take advantage of modem computer speed, memory, and data storage capabilities, are applicable to the detection of weakly absorbing gases in quantitative industrial monitoring, in addition to aircraft and balloon atmospheric measurements for which they were designed. Algorithms for calibration and data analysis, including rejection of erroneous spectra, variation of effective integration time, spectral alignment prior to averaging, and plotting and archiving of results, have been tested on actual stratospheric laser spectra recorded by the Aircraft Laser Infrared Absorption Spectrometer (ALIAS) spectrometer in numerous flights of NASA's ER-2 aircraft. RP MAY, RD (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 30 TC 25 Z9 26 U1 1 U2 6 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 APR PY 1993 VL 49 IS 4 BP 335 EP 347 DI 10.1016/0022-4073(93)90098-3 PG 13 WC Optics; Spectroscopy SC Optics; Spectroscopy GA KV501 UT WOS:A1993KV50100002 ER PT J AU LIGHT, JS AF LIGHT, JS TI TIP VORTEX GEOMETRY OF A HOVERING HELICOPTER ROTOR IN GROUND EFFECT SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB The wide-field shadowgraph method has been used to photograph the tip vortices of a hovering helicopter rotor in ground effect. The shadowgraphs were used to obtain quantitative measurements of the rotor tip vortex geometry both in and out of ground effect. Many important phenomena are visible in the rotor wake using this method. These include the variation in descent and contraction rates of the tip vortices in ground effect, and the interaction between tip vortices in the far wake. The tip vortex geometry from the shadowgraphs is compared with the tip vortex geometry predicted using a free wake hover performance analysis. The free wake analysis accurately predicts the tip vortex geometry both in and out of ground effect. Performance data from the test is compared with the performance predicted using several methods, including the free wake analysis. All methods provided reasonable predictions of the helicopter performance in ground effect. RP LIGHT, JS (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 16 TC 7 Z9 14 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 APR PY 1993 VL 38 IS 2 BP 34 EP 42 PG 9 WC Engineering, Aerospace SC Engineering GA LC580 UT WOS:A1993LC58000004 ER PT J AU BLISS, DB MILLER, WO AF BLISS, DB MILLER, WO TI EFFICIENT FREE WAKE CALCULATIONS USING ANALYTICAL NUMERICAL MATCHING SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A hybrid analytical and numerical method called Analytical/Numerical Matching is used to calculate the velocity field of rotor wake vortex filaments. A simple discretization of the Biot-Savart law is used to obtain an efficient but low order numerical calculation of the velocity field. An artificially large vortex core is introduced and the discretized velocity field is calculated accurately for a smooth large core filament. At points close to the filament, a local analytical correction is applied to correct for the near-field velocity associated with the physical vortex core size. Because this correction is infrequently applied, the overall approach is both efficient and accurate. Closed analytical expressions for the Analytical/Numerical Matching velocity derivatives were obtained, resulting in a linearized form of the method. The accuracy of the Analytical/Numerical Matching method is studied in detail for vortex rings. Several tip vortex rotor free wake solutions are obtained using the linear and fully nonlinear Analytical/Numerical Matching methods, and are compared to another method having comparably high accuracy. C1 NASA,NATL RES COUNCIL,MOFFETT FIELD,CA 94035. RP BLISS, DB (reprint author), DUKE UNIV,DURHAM,NC 27706, USA. NR 16 TC 3 Z9 4 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 APR PY 1993 VL 38 IS 2 BP 43 EP 52 PG 10 WC Engineering, Aerospace SC Engineering GA LC580 UT WOS:A1993LC58000005 ER PT J AU MILLER, WO BLISS, DB AF MILLER, WO BLISS, DB TI DIRECT PERIODIC-SOLUTIONS OF ROTOR FREE WAKE CALCULATIONS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Periodic Inversion is a new approach for the calculation of rotor free wakes which solves directly for periodically steady-state solutions, at all advance ratios including low speed and hover. This is a unique capability as traditional time marching solutions can fail to converge at low advance ratios. The method is based on enforcing a periodic boundary condition on the wake over one rotor revolution. The resulting system of nonlinear equations is linearized, then iteratively solved for perturbative corrections to the wake geometry. The method is used to examine the low speed wake structure, which exhibits three distinct forms depending on advance ratio: a helical structure from hover to some lower bound advance ratio, a roll-up structure above some higher bound advance ratio, and a rapid transition region between the two. Performance curves are generated by varying trim parameters between iterations. C1 DUKE UNIV,DURHAM,NC 27706. RP MILLER, WO (reprint author), NASA,NATL RES COUNCIL,MOFFETT FIELD,CA 94035, USA. NR 9 TC 20 Z9 23 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 APR PY 1993 VL 38 IS 2 BP 53 EP 60 PG 8 WC Engineering, Aerospace SC Engineering GA LC580 UT WOS:A1993LC58000006 ER PT J AU STRAWN, RC BARTH, TJ AF STRAWN, RC BARTH, TJ TI A FINITE-VOLUME EULER SOLVER FOR COMPUTING ROTARY-WING AERODYNAMICS ON UNSTRUCTURED MESHES SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB An unstructured-grid solver for the unsteady Euler equations has been developed for predicting the aerodynamics of helicopter rotor blades. This now solver is a finite-volume scheme that computes flow quantities at the vertices of the mesh. Special treatments are used for the nux differencing and boundary conditions in order to compute rotary-wing flowfields, and these are detailed in the paper. The unstructured-grid solver permits adaptive-grid refinement in order to improve the resolution of flow features such as shocks, rotor wakes and acoustic waves. These capabilities are demonstrated in the paper. Example calculations are presented for two hovering rotors. In both cases, adaptive-grid refinement is used to resolve high gradients near the rotor surface and also to capture the vortical regions in the rotor wake. The computed results show good agreement with experimental results for surface airloads and wake geometry. C1 NASA,CFD BRANCH,MOFFETT FIELD,CA 94035. RP STRAWN, RC (reprint author), NASA,US ARMY AEROFLIGHTDYNAM,MOFFETT FIELD,CA 94035, USA. NR 12 TC 22 Z9 27 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 APR PY 1993 VL 38 IS 2 BP 61 EP 67 PG 7 WC Engineering, Aerospace SC Engineering GA LC580 UT WOS:A1993LC58000007 ER PT J AU CHENG, VHL SRIDHAR, B AF CHENG, VHL SRIDHAR, B TI TECHNOLOGIES FOR AUTOMATING ROTORCRAFT NAP-OF-THE-EARTH FLIGHT SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB This paper reviews the technologies required for automating rotorcraft nap-of-the-earth flight, where the use of natural obstacles for masking from the enemy is intentional and the danger of undesirable obstacles such as enemy traps is real. Specifically, the automatic guidance structure is modeled by three decision-making levels: the far-field mission planning and the mid-field terrain-masking trajectory shaping are both driven by stored terrain data, whereas the near-field obstacle detection/avoidance is driven by real-time, on-board sensor data. This paper summarizes the far-field and mid-field accomplishments, and reports on the status of recent efforts in obstacle detection and avoidance development. Obstacle detection is based primarily on passive imaging sensors for the desirable properties of covertness and wide field of view, although active sensors are included in the structure to provide the needed high resolution for thin-wire detection. An extensive list of references, though not exhaustive, is provided. RP CHENG, VHL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 65 TC 5 Z9 5 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 APR PY 1993 VL 38 IS 2 BP 78 EP 87 PG 10 WC Engineering, Aerospace SC Engineering GA LC580 UT WOS:A1993LC58000009 ER PT J AU ALFANO, S NEGRON, D AF ALFANO, S NEGRON, D TI DETERMINING SATELLITE CLOSE APPROACHES SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This paper presents a numerical method to evaluate close approaches of two satellites. The algorithm is based on a space curve modeling technique originally developed by Overhauser, presented here as an independent derivation. The method to determine minimum spacing between two space objects is based on creating a relative distance waveform, delta(t), versus time. The waveform is produced from either uniform or arbitrarily spaced data points, from which intervals of close approach are obtained by extracting the real roots of a localized cubic polynomial. This method is free of both transcendental equations and the computation of acceleration terms of the two objects of interest. For this study a close approach truth table is constructed using a 0.1 second sequential step along the orbits, then differencing the two position vectors. The close approach entrance and exit times for an ellipsoidal quadric surface are then located using a piecewise linear interpolator, and serve as a benchmark for comparison. The simulation results show this algorithm produces encounter times almost identical to those in the truth table, with a 99.84% reduction in computer runtime. The results, created from real orbital data, include solution sets for three operational uses of close-approach logic. For this study, satellite orbital motion is modeled using first-order secular perturbations caused by mass anomalies. C1 US SPACE COMMAND,DIV SPACE OPERAT CONTROL,CHEYENNE MT AFB,CO 80914. RP ALFANO, S (reprint author), PHILLIPS LAB,DIV SPACE & MISSILES DYNAM,PL VTA,KIRTLAND AFB,NM 87117, USA. NR 6 TC 19 Z9 22 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 APR-JUN PY 1993 VL 41 IS 2 BP 217 EP 225 PG 9 WC Engineering, Aerospace SC Engineering GA LQ595 UT WOS:A1993LQ59500005 ER PT J AU MARKLEY, FL AF MARKLEY, FL TI ATTITUDE DETERMINATION USING VECTOR OBSERVATIONS - A FAST OPTIMAL MATRIX ALGORITHM SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The attitude matrix minimizing Wahba's loss function is computed directly by a method that is either faster or more robust than any previously known algorithm for finding this optimal estimate. Analysis of the special case of two vector observations identifies those cases for which the TRIAD or algebraic method minimizes Wahba's loss function. The new method also provides an estimate of the attitude error covariance matrix, including an especially convenient representation of the two-observation covariance matrix. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,CODE 712,GREENBELT,MD 20771, USA. NR 21 TC 107 Z9 122 U1 2 U2 8 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 APR-JUN PY 1993 VL 41 IS 2 BP 261 EP 280 PG 20 WC Engineering, Aerospace SC Engineering GA LQ595 UT WOS:A1993LQ59500008 ER PT J AU BIANCO, R RAPP, RA SMIALEK, JL AF BIANCO, R RAPP, RA SMIALEK, JL TI CHROMIUM AND REACTIVE ELEMENT MODIFIED ALUMINIDE DIFFUSION COATINGS ON SUPERALLOYS - ENVIRONMENTAL TESTING SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID HOT CORROSION; OXIDATION BEHAVIOR; SODIUM-SULFATE; BASE ALLOYS; DEGRADATION; DISSOLUTION; RESISTANCE; MECHANISMS; YTTRIUM; GROWTH AB The isothermal oxidation of reactive element (RE)-doped aluminide coatings on IN 713LC alloy substrates at 1100-degrees-C in air formed a continuous slow-growing alpha-Al2O3 scale after 44 h of exposure. RE-free (reactive element-free) aluminide coatings were characterized by a cracked oxide scale which exposed an underlying voided coating surface. The cyclic oxidation behavior of Cr/RE-modified aluminide diffusion coatings on Rene 80 and IN 713LC alloy substrates, and of RE-doped aluminide coatings on IN 713LC alloy substrates, at 1100-degrees-C in static air was determined. Coatings deposited by the above pack (AP) arrangement, as opposed to the powder contacting (PC) arrangement, showed improved resistance to cyclic oxidation attack. RE-doped and Cr/RE-modified aluminide coatings exhibited considerably more adherent protective Al2O3 scales compared to undoped aluminide coatings. The hot corrosion behavior of Cr/RE-modified aluminide coatings on Rene 80 and Mar-M247 alloy substrates at 900-degrees-C in a 0.1% SO2/O2 gas mixture also was determined. The Cr/RE-modified aluminide coatings provided better resistance to hot corrosion attack (i.e., thin film studies) than a commercial low activity aluminide coating. Coating lifetimes were strongly dependent on the chromium surface composition, since a mixed (Al, Cr)2O3 scale better resists attack by the molten salt. C1 NATL AERONAUT & SPACE ADM,LEWIS RES CTR,CLEVELAND,OH 44135. RP BIANCO, R (reprint author), OHIO STATE UNIV,DEPT MAT SCI & ENGN,COLUMBUS,OH 43210, USA. NR 49 TC 32 Z9 33 U1 1 U2 15 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 APR PY 1993 VL 140 IS 4 BP 1191 EP 1203 DI 10.1149/1.2056220 PG 13 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA KY388 UT WOS:A1993KY38800066 ER PT J AU RIGNOT, E CHELLAPPA, R AF RIGNOT, E CHELLAPPA, R TI MAXIMUM A POSTERIORI CLASSIFICATION OF MULTIFREQUENCY, MULTILOOK, SYNTHETIC APERTURE RADAR INTENSITY DATA SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID K-DISTRIBUTION; SAR IMAGES; CLUTTER; SEGMENTATION; MODEL AB We present a maximum a posteriori (MAP) classifier for classifying multifrequency, multilook, single polarization, synthetic aperture radar (SAR) intensity data into regions or ensembles of pixels of homogeneous and similar radar backscatter characteristics. A model for the prior joint distribution of the multifrequency SAR intensity data is combined with a Markov random field for representing the interactions between region labels to obtain an expression for the posterior distribution of the region labels given the multifrequency SAR observations. The maximization of the posterior distribution yields Bayes's optimum region labeling or classification of the SAR data or its MAP estimate. The performance of the MAP classifier is evaluated by using computer-simulated multilook SAR intensity data as a function of the parameters in the classification process. Multilook SAR intensity data are shown to yield higher classification accuracies than one-look SAR complex amplitude data. Examples using actual two-frequency, four-look, SAR intensity data acquired by the NASA/Jet Propulsion Laboratory airborne polarimetric SAR are presented. The MAP classifier is extended to the case in which the radar backscatter from the remotely sensed surface varies within the SAR image because of incidence angle effects. The results obtained illustrate the practicality of the method for combining SAR intensity observations acquired at two different frequencies and for improving classification accuracy of SAR data. C1 UNIV MARYLAND,CTR AUTOMAT RES,DEPT ELECT ENGN,COLL PK,MD 20742. RP RIGNOT, E (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 26 TC 13 Z9 15 U1 0 U2 0 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 APR PY 1993 VL 10 IS 4 BP 573 EP 582 DI 10.1364/JOSAA.10.000573 PG 10 WC Optics SC Optics GA KU219 UT WOS:A1993KU21900005 ER PT J AU JENDOUBI, S LEE, HS KIM, TK AF JENDOUBI, S LEE, HS KIM, TK TI DISCRETE ORDINATES SOLUTIONS FOR RADIATIVELY PARTICIPATING MEDIA IN A CYLINDRICAL ENCLOSURE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID ANISOTROPIC SCATTERING MEDIA; HEAT-TRANSFER AB The radiative transfer equation is solved by the S-N discrete ordinates method in the two-dimensional r-z coordinates system. The walls of the enclosure are diffuse, and the participating medium absorbs, emits, and anisotropically scatters the radiative energy. Diffuse wall incidence, isothermal medium emission, and collimated incidence problems are considered. Effects of the scattering phase functions on average incident radiation and net radiative heat fluxes are studied. In addition, the effects of scattering albedo, optical thickness, and the wall emissivity are briefly discussed. C1 NASA, LEWIS RES CTR, DIV PROPULS SYST, CLEVELAND, OH 44135 USA. CHUNG ANG UNIV, DEPT MECH ENGN, SEOUL 156756, SOUTH KOREA. RP UNIV MINNESOTA, DEPT MECH ENGN, MINNEAPOLIS, MN 55455 USA. NR 21 TC 57 Z9 57 U1 1 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 APR-JUN PY 1993 VL 7 IS 2 BP 213 EP 219 DI 10.2514/3.409 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600002 ER PT J AU HARTUNG, LC HASSAN, HA AF HARTUNG, LC HASSAN, HA TI RADIATION TRANSPORT AROUND AXISYMMETRICAL BLUNT BODY VEHICLES USING A MODIFIED DIFFERENTIAL APPROXIMATION SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A moment method for computing three-dimensional radiative transport is applied to axisymmetric flows in thermochemical nonequilibrium. Such flows are representative of proposed aerobrake missions. The method uses the P-1 approximation to reduce the governing system of integro-differential equations to a coupled set of partial differential equations. A numerical solution method for these equations given actual variations of the radiation properties in thermochemical nonequilibrium blunt body flows is developed. Initial results from the method are shown and compared to tangent slab calculations. The agreement between the transport methods is found to be about 10% in the stagnation region with the difference increasing along the flank of the vehicle. C1 N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP HARTUNG, LC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 27 TC 16 Z9 16 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 APR-JUN PY 1993 VL 7 IS 2 BP 220 EP 227 DI 10.2514/3.410 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600003 ER PT J AU DURGAPAL, P AF DURGAPAL, P TI CURRENT DISTRIBUTION IN THE CATHODE AREA OF AN ARCJET SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A theoretical model of the electrode phenomena, leading to the computation of the current density distributions, arc spot temperature, spot size, sheath voltage, ablation velocity, and ablation rates, is put forward. Computations for an atmospheric arc, at load currents ranging from 800 to 3000 A, in 1) one segment, and 2) four segment electrode configurations, are conducted. Spot size seems to vary linearly with load current, ranging from 1.82 to 3.22 mm for a rotating arcfoot, as the load current is varied from 800 to 3000 A. Even with arcfoot rotation, spot temperatures are high enough to cause ablation of the electrode material. Computations for P = 50 atm and I = 6000 A reveal that arc rotation is even more essential in order to save the excessive material ablation. In order to achieve an acceptable level of material ablation at P = 50 atm and I = 6000 A. a rotational frequency of 300-400 Hz needs to be achieved. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94034. NR 10 TC 6 Z9 6 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 APR-JUN PY 1993 VL 7 IS 2 BP 241 EP 250 DI 10.2514/3.413 PG 10 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600006 ER PT J AU SHARMA, SP RUFFIN, SM MEYER, SA GILLESPIE, WD YATES, LA AF SHARMA, SP RUFFIN, SM MEYER, SA GILLESPIE, WD YATES, LA TI DENSITY-MEASUREMENTS IN AN EXPANDING FLOW USING HOLOGRAPHIC-INTERFEROMETRY SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A nonequilibrium expansion of nitrogen through a two-dimensional nozzle of a reflected shock tunnel is investigated with laser holography, time-resolved pressure measurements, and emission spectroscopy to characterize the flowfield for future vibrational relaxation measurements. A two-dimensional computation is used to simulate the nozzle flowfield. Synthetic holograms are generated using the computed density profiles and are compared with the experimental holograms. Also, using a quasi-one-dimensional approximation, populations for each vibrational level are computed by 1) solving the master equations, and 2) using the Landau-Teller formulation. Computational accuracy of both models is assessed against the experimental data. C1 STANFORD UNIV,STANFORD,CA 94305. ELORET INST,PALO ALTO,CA 94303. RP SHARMA, SP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 3 Z9 3 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 APR-JUN PY 1993 VL 7 IS 2 BP 261 EP 268 DI 10.2514/3.415 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600008 ER PT J AU LEVIN, DA LODA, RT CANDLER, GV PARK, C AF LEVIN, DA LODA, RT CANDLER, GV PARK, C TI THEORY OF RADIATION FROM LOW-VELOCITY SHOCK HEATED AIR SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Application of hypersonic computational fluid dynamics models to low velocity vehicles is examined. Important modeling aspects such as chemical kinetics, electronic excitation/de-excitation mechanisms, and existence of equilibrium vs nonequilibrium conditions in the flow were examined. Flowfield properties and in-band radiances in the wavelength region of 0.25 mu in the vicinity of the stagnation streamline are given for a hemisphere with a radius of 0.0762 m. Comparison with recent shock tube data is also shown. C1 N CAROLINA STATE UNIV,DEPT MECH AEROSP ENGN,RALEIGH,NC 27695. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LEVIN, DA (reprint author), INST DEF ANAL,DIV SCI & TECHNOL,1801 N BEAUREGARD ST,ALEXANDRIA,VA 22311, USA. NR 22 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 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 1993 VL 7 IS 2 BP 269 EP 276 DI 10.2514/3.416 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600009 ER PT J AU PALMER, G AF PALMER, G TI MAGNETIC-FIELD EFFECTS ON THE COMPUTED FLOW OVER A MARS RETURN AEROBRAKE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A numerical algorithm is developed to calculate the electromagnetic phenomena simultaneously with the fluid flow in the shock layer over an axisymmetric blunt body in a thermal equilibrium, chemical nonequilibrium environment. The flowfield is solved using an explicit time-marching, first-order spatially accurate scheme. The electromagnetic phenomena are coupled to the real-gas flow solver through an iterative procedure. The electromagnetic terms introduce a strong stiffness, which was overcome by using significantly smaller time steps for the electromagnetic conservation equation. The technique is applied in calculating the flow over a Mars return aerobrake vehicle entering the Earth's atmosphere. For the case where no external field is applied, the electromagnetic effects have little impact on the flowfield. With the application of an external magnetic field of 0.05 to 0.1 T, the solution indicates an increase in stagnation line shock standoff distance, wall pressure, and radiative heat transfer and a decrease in convective heat transfer. RP PALMER, G (reprint author), NASA,AMES RES CTR,AEROTHERMODYNAM BRACH,MOFFETT FIELD,CA 94035, USA. NR 30 TC 10 Z9 10 U1 1 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 APR-JUN PY 1993 VL 7 IS 2 BP 294 EP 301 DI 10.2514/3.419 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600012 ER PT J AU SPUCKLER, CM SIEGEL, R AF SPUCKLER, CM SIEGEL, R TI REFRACTIVE-INDEX AND SCATTERING EFFECTS ON RADIATIVE BEHAVIOR OF A SEMITRANSPARENT LAYER SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Heat transfer characteristics are analyzed for a plane layer of semitransparent material with refractive index greater-than-or-equal-to 1. Energy transfer in the material is by conduction, emission, absorption, and isotropic scattering. The layer surfaces are diffuse intending to model a ceramic layer in high temperature applications. Each side of the layer is heated by radiation and convection. Internal reflections at the boundary surfaces are included. For a refractive index larger than unity, there is internal reflection of some of the energy within the layer. This, coupled with scattering, has a substantial effect on distributing energy across the layer and altering the temperature distribution from when the refractive index is unity. The effect of scattering is examined by comparisons with results from an earlier paper for an absorbing layer. Results are given for a gray medium with a scattering albedo up to 0.999, and for a two-band spectral variation of the albedo with one band having low absorption. Radiant energy leaving the surface as a result of emission and scattering was examined to determine if it could be used to accurately indicate the surface temperature. RP NASA, LEWIS RES CTR, LEWIS RES ACAD, CLEVELAND, OH 44135 USA. NR 15 TC 21 Z9 21 U1 0 U2 4 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 APR-JUN PY 1993 VL 7 IS 2 BP 302 EP 310 DI 10.2514/3.420 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600013 ER PT J AU RAMACHANDRAN, N AF RAMACHANDRAN, N TI THERMAL BUOYANCY AND MARANGONI CONVECTION IN A 2 FLUID LAYERED SYSTEM SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID NATURAL-CONVECTION AB Thermal buoyancy and surface tension driven convection is numerically investigated in a system with two immiscible fluids. The geometry investigated has an open cavity configuration with the lighter fluid situated on top of the heavier fluid, forming a stable layered system. The upper fluid meniscus and the interface are assumed to be flat and undeformable in the calculations. The governing equations and boundary/interface conditions are solved by a control volume-based finite difference scheme for two pairs of immiscible fluids; the water-hexadecane system and a so-called generic system. The steady-state calculations predict dramatically different flows when interfacial tension effects are included or excluded from the system model. These differences are particularly appreciable in surface tension-dominated flows, that are typical of microgravity situations. Complex flow patterns, with induced secondary flows, are noticed in both the fluids. In general, the overall system heat transfer is found to increase with increases in the thermal buoyancy and surface tension effects, but the behavior of the system flow and thermal fields is not easy to characterize when different combinations of these forces are considered. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NR 14 TC 7 Z9 7 U1 1 U2 3 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 APR-JUN PY 1993 VL 7 IS 2 BP 352 EP 360 DI 10.2514/3.427 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA LC656 UT WOS:A1993LC65600020 ER PT J AU COPENHAVER, WW HAH, C PUTERBAUGH, SL CUMPSTY, NA AF COPENHAVER, WW HAH, C PUTERBAUGH, SL CUMPSTY, NA TI 3-DIMENSIONAL FLOW PHENOMENA IN A TRANSONIC, HIGH-THROUGHFLOW, AXIAL-FLOW COMPRESSOR STAGE SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 37TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 01-04, 1992 CL COLOGNE, GERMANY AB A detailed aerodynamic study of a transonic, high-throughflow, single-stage compressor is presented. The compressor stage was comprised of a low-aspect-ratio rotor combined alternately with two different stator designs. Both experimental and numerical studies are conducted to understand the details of the complex flow field present in this stage. Aerodynamic measurements using high-frequency, Kulite pressure transducers and conventional probes are compared with results from a three-dimensional viscous flow analysis. A steady multiple blade row approach is used in the numerical technique to examine the detailed flow structure inside the rotor and the stator passages. The comparisons indicate that many flow field features are correctly captured by viscous flow analysis, and therefore unmeasured phenomena can be studied with some level of confidence. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV CAMBRIDGE,WHITTLE LAB,CAMBRIDGE,ENGLAND. RP COPENHAVER, WW (reprint author), USAF,WRIGHT AERONAUT LABS,WRIGHT PATTERSON AFB,OH 45433, USA. NR 17 TC 29 Z9 30 U1 0 U2 6 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 240 EP 248 DI 10.1115/1.2929228 PG 9 WC Engineering, Mechanical SC Engineering GA KZ266 UT WOS:A1993KZ26600004 ER PT J AU ARNONE, A SWANSON, RC AF ARNONE, A SWANSON, RC TI A NAVIER-STOKES SOLVER FOR TURBOMACHINERY APPLICATIONS SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article ID MULTIPLE-GRID ALGORITHM; VISCOUS FLOWS; EULER AB A computer code for solving the Reynolds-averaged full Navier-Stokes equations has been developed and applied using H- and C-type grids. The Baldwin-Lomax eddy-viscosity model is used for turbulence closure. The integration in time is based on an explicit four-stage Runge-Kutta scheme. Local time stepping, variable coefficient implicit residual smoothing, and a full multigrid method have been implemented to accelerate steady-state calculations. A grid independence analysis is presented for a transonic rotor blade. Comparisons with experimental data show that the code is an accurate viscous solver and can give very good blade-to-blade predictions for engineering applications. RP ARNONE, A (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. OI Arnone, Andrea/0000-0001-7471-4442 NR 19 TC 19 Z9 19 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 1993 VL 115 IS 2 BP 305 EP 313 DI 10.1115/1.2929236 PG 9 WC Engineering, Mechanical SC Engineering GA KZ266 UT WOS:A1993KZ26600010 ER PT J AU ZIMMER, JP LEWIS, SM MOYER, JL AF ZIMMER, JP LEWIS, SM MOYER, JL TI COMPARISON OF GAVAGE, WATER BOTTLE, AND A HIGH-MOISTURE DIET BOLUS AS DOSING METHODS FOR QUANTITATIVE D-XYLOSE ADMINISTRATION TO B6D2F1 (MUS-MUSCULUS) MICE SO LABORATORY ANIMALS LA English DT Article DE DOSING METHODS; HIGH-MOISTURE DIET; MEAL; GAVAGE; WATER BOTTLE; D-XYLOSE; XYLOSE TOLERANCE TEST ID ABSORPTION AB Gavage, water bottle, and diet incorporation are 3 dosing methods used orally to administer test compounds to rodents. These 3 methods were compared in mice to determine which represented the most quantitative delivery system. For dietary incorporation, a high-moisture bolus form of NIH-31 rodent meal was developed using hydroxypropyl methylcellulose as an autoclave-stable binding agent. A high-moisture bolus was selected to increase the acceptability of the dosed diet and to promote quantitative consumption through reduced wastage. The test compound used was D-xylose, a pentose sugar that may be quantitatively detected, colorimetrically, in urine following oral dosing. Six male and 6 female B6D2F1 mice were placed in metabolism cages and dosed with a known quantity of D-xylose by each of the 3 methods. Urine was collected before and after each method of administration and analysed for total D-xylose; the per cent recovery was based upon the amount of D-xylose consumed. Quantitative consumption was apparently greatest for water bottle dosing with an average recovery of 56.0% of the original D-xylose dose. High-moisture bolus incorporation ranked second with 50.0% D-xylose recovery, and gavage was third with 41.0% D-xylose recovery. C1 BIONET CORP,NATL CTR TOXICOL RES,JEFFERSON,AR 72079. CORNELL UNIV,DIV NUTR SCI,ITHACA,NY 14850. BIONET CORP,NASA,KENNEDY SPACE CTR,FL 32899. NR 19 TC 5 Z9 5 U1 0 U2 0 PU ROYAL SOC MEDICINE SERVICES LTD PI LONDON PA 1 WIMPOLE STREET, LONDON, ENGLAND W1M 8AE SN 0023-6772 J9 LAB ANIM JI Lab. Anim. PD APR PY 1993 VL 27 IS 2 BP 164 EP 170 DI 10.1258/002367793780810423 PG 7 WC Veterinary Sciences; Zoology SC Veterinary Sciences; Zoology GA KV919 UT WOS:A1993KV91900011 PM 8501899 ER PT J AU CHASE, TJ AF CHASE, TJ TI WEAR MODES ACTIVE IN ANGULAR CONTACT BALL-BEARINGS OPERATING IN LIQUID-OXYGEN ENVIRONMENT OF THE SPACE-SHUTTLE TURBOPUMPS SO LUBRICATION ENGINEERING LA English DT Article DE WEAR MODES; CRYOGENIC BEARINGS; ANGULAR CONTACT; LOX TURBOPUMPS AB Extensive experimental investigation has been carried out on used flight bearings of the high pressure oxidizer turbopumps (HPOTP) of the space shuttle main engine (SSME) in order to determine the dominant wear modes, their extent, and causes. The paper presents the methodology, various surface analysis techniques used, results, and discussion. The mode largely responsible for premature bearing wear has been identified as adhesive/shear peeling of the upper layers of bearing balls and rings. This mode relies upon the mechanism of scale formation, breakdown, and removal, all of which are greatly enhanced by the heavy oxidation environment of the HPOTP. Major causes of the high wear rates appear to be lubrication and cooling, both inadequate for the imposed conditions of operation. Numerous illustrations and evidence are provided. RP CHASE, TJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,NATL RES COUNCIL,HUNTSVILLE,AL 35812, USA. NR 22 TC 10 Z9 13 U1 1 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD APR PY 1993 VL 49 IS 4 BP 313 EP 322 PG 10 WC Engineering, Mechanical SC Engineering GA KV143 UT WOS:A1993KV14300008 ER PT J AU WILSON, CD BOEHLERT, GW AF WILSON, CD BOEHLERT, GW TI POPULATION BIOLOGY OF GNATHOPHAUSIA-LONGISPINA (MYSIDACEA, LOPHOGASTRIDA) FROM A CENTRAL NORTH PACIFIC SEAMOUNT SO MARINE BIOLOGY LA English DT Article ID INGENS MYSIDACEA; GROWTH-RATE; CRUSTACEA; COMMUNITY AB Large numbers of the lophogastrid mysid Gnathophausia longispina were discovered in 1984 over Southeast Hancock Seamount on the northern Hawaiian Ridge. Additional specimens were collected from the same area during subsequent surveys in 1985, 1987, and 1988 to obtain new information on the life history of this species. Estimates of growth suggest that G. longispina reaches sexual maturity by its second year. Young are brooded by the female for nearly a year and released in late winter-early spring. It is doubtful if G. longispina live longer than 2 yr or produce more than one brood. Most G. longispina are found within 100 m above the seamount summit. The modal progression of size classes over time indicates that this species is dependent on local processes rather than recruitment from other areas to maintain its populations at the seamount. C1 UNIV HAWAII,DEPT OCEANOG,HONOLULU,HI 96822. NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. NR 24 TC 7 Z9 8 U1 1 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0025-3162 J9 MAR BIOL JI Mar. Biol. PD APR PY 1993 VL 115 IS 4 BP 537 EP 543 DI 10.1007/BF00349360 PG 7 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA LC691 UT WOS:A1993LC69100003 ER PT J AU BROWN, SA KUMAR, KS WHITTENBERGER, JD AF BROWN, SA KUMAR, KS WHITTENBERGER, JD TI MECHANICAL-BEHAVIOR OF TIB2-PARTICULATE-REINFORCED AL66TI25MN9 PRODUCED BY INGOT METALLURGY SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID GAMMA TITANIUM ALUMINIDES AB A cast and isothermally forged particulate composite of Al66Ti25Mn9 + 3 vol.% TiB2 was evaluated in compression, three-point bending and uniaxial tension. Compared with previous results on a monolithic material of the same composition, the composite was stronger in compression at all temperatures and strain rates examined. A similar trend was noted in tension in the temperature range 923 K-1073 K. Three-point bend tests (300 K-873 K), however, revealed a smaller degree of plastic deformation in the composite compared to its monolithic counterpart. Serrated flow was observed between 623 K and 923 K in compression, bending and tension for the monolithic material, whereas in the composite it was noted at 573 K in compression. In tension, the composite exhibits brittle failure at 923 K. Above 923 K, the ductility is roughly one half of the monolithic alloy. Transgranular cleavage fracture in the composite changes to an intergranular mode at a higher temperature relative to the monolithic material. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BROWN, SA (reprint author), MARTIN MARIETTA CORP LABS,BALTIMORE,MD 21227, USA. NR 11 TC 3 Z9 3 U1 0 U2 0 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 APR 1 PY 1993 VL 161 IS 2 BP 187 EP 194 DI 10.1016/0921-5093(93)90512-D PG 8 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA LB329 UT WOS:A1993LB32900003 ER PT J AU SPANOS, G AYERS, JD VOLD, CL LOCCI, IE AF SPANOS, G AYERS, JD VOLD, CL LOCCI, IE TI THE MICROSTRUCTURAL EVOLUTION, CRYSTALLOGRAPHY, AND THERMAL-PROCESSING OF ULTRAHIGH CARBON FE-1.85 PCT-C MELT-SPUN RIBBON SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID STEEL AB The microstructural evolution, mechanisms of grain refinement, crystallography, and thermal processing of a rapidly solidified Fe-1.85 pct C alloy have been studied by transmission electron microscopy (TEM). Melt-spun ribbons quenched in liquid nitrogen consist of carbide-free highly twinned martensite plates between 0.5- and 2.0-mum long and 0.1- and 0.5-mum thick, with approximately 40 pct retained austenite also present. Ribbons tempered at 600-degrees-C for 10 seconds consist of ferrite of approximately the same grain size and both intragranular and intergranular cementite precipitates. The intragranular cementite particles are about 0.1 mum or less in size and exhibit a single variant of the Bagaryatskii orientation relationship with respect to a given ferrite grain; the intergranular particles are about 0.1 mum in thickness and can be as long as 0.5 mum due to growth and/or coalescence along ferrite grain boundaries. A heat-treatment cycle investigated with a view toward generating structures suited for superplastic consolidation of the rapidly solidified ribbons consists of quenching the ribbon in liquid nitrogen, tempering at 600-degrees-C for 10 seconds, ''upquenching'' to 750-degrees-C (austenitizing) for 10 seconds, and subsequently quenching again in liquid nitrogen. This treatment results in martensite grains highly misoriented with respect to one another and typically 0.5 mum or less in both length and thickness and cementite particles 0.4 mum or less in size. (Occasionally, longer martensite plates were observed; but they never exceeded 1 mum in length.) The microstructures produced here offer the potential for producing fine-grained ultrahigh carbon steels of very high strength without the brittleness associated with the formation of coarse carbide particles or the loss of strength due to graphite formation. This investigation has thus provided the basis for follow-on studies currently underway in ultrahigh carbon Fe-C-Cr and Fe-C-Cr-Si steels, with the intent of producing similar microstructures which will also exhibit enhanced high-temperature stability. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SPANOS, G (reprint author), USN,RES LAB,PHYS MET BRANCH,WASHINGTON,DC 20385, USA. NR 23 TC 2 Z9 2 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD APR PY 1993 VL 24 IS 4 BP 809 EP 818 DI 10.1007/BF02656502 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA KU568 UT WOS:A1993KU56800004 ER PT J AU SIRCAR, S WILSON, DB STOLTZFUS, J AF SIRCAR, S WILSON, DB STOLTZFUS, J TI A REAL-TIME GRAVIMETRIC INSTRUMENT FOR COMBUSTION STUDIES OF METALLIC MATERIALS SO METALLURGICAL TRANSACTIONS B-PROCESS METALLURGY LA English DT Note RP SIRCAR, S (reprint author), NASA,WHITE SANDS TEST FACIL,PO DRAWER MM,LAS CRUCES,NM 88004, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2141 J9 METALL TRANS B PD APR PY 1993 VL 24 IS 2 BP 395 EP 397 DI 10.1007/BF02659141 PG 3 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA KV762 UT WOS:A1993KV76200017 ER PT J AU HEARN, CP AF HEARN, CP TI LUMPED ELEMENTS CHARACTERIZE-Q IN DIELECTRIC RESONATORS SO MICROWAVES & RF LA English DT Article RP HEARN, CP (reprint author), NASA,LANGLEY RES CTR,MS 490,HAMPTON,VA 23681, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0745-2993 J9 MICROWAVES RF JI Microw. RF PD APR PY 1993 VL 32 IS 4 BP 89 EP 92 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA KZ554 UT WOS:A1993KZ55400010 ER PT J AU GRUN, E ZOOK, HA BAGUHL, M BALOGH, A BAME, SJ FECHTIG, H FORSYTH, R HANNER, MS HORANYI, M KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, I MCDONNELL, JAM MORFILL, GE PHILLIPS, JL POLANSKEY, C SCHWEHM, G SIDDIQUE, N STAUBACH, P SVESTKA, J TAYLOR, A AF GRUN, E ZOOK, HA BAGUHL, M BALOGH, A BAME, SJ FECHTIG, H FORSYTH, R HANNER, MS HORANYI, M KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, I MCDONNELL, JAM MORFILL, GE PHILLIPS, JL POLANSKEY, C SCHWEHM, G SIDDIQUE, N STAUBACH, P SVESTKA, J TAYLOR, A TI DISCOVERY OF JOVIAN DUST STREAMS AND INTERSTELLAR GRAINS BY THE ULYSSES SPACECRAFT SO NATURE LA English DT Article ID INTER-STELLAR GRAINS; RING; ORIGIN AB ON 8 February 1992, the Ulysses spacecraft flew by Jupiter at a distance of 5.4 AU from the Sun. During the encounter, the spacecraft was deflected into a new orbit, inclined at about 80-degrees to the ecliptic plane, which will ultimately lead Ulysses over the polar regions of the Sun1. Within 1 AU from Jupiter, the onboard dust detector2 recorded periodic bursts of submicrometre dust particles, with durations ranging from several hours to two days, and occurring at approximately monthly intervals (28 +/- 3 days). These particles arrived at Ulysses in collimated streams radiating from close to the line-of-sight direction to Jupiter, suggesting a jovian origin for the periodic bursts. Ulysses also detected a flux of micrometre-sized dust particles moving in high-velocity (greater-than-or-equal-to 26 km s-1) retrograde orbits (opposite to the motion of the planets); we identify these grains as being of interstellar origin. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. JET PROP LAB,PASADENA,CA 91109. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. LUND OBSERV,S-221 LUND,SWEDEN. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV KENT,CANTERBURY CT2 7NR,ENGLAND. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. EUROPEAN SPACE TECHNOL CTR,2200 AG NOORDWIJK,NETHERLANDS. PRAGUE OBSERV,CS-11846 PRAGUE 1,CZECHOSLOVAKIA. RP GRUN, E (reprint author), MAX PLANCK INST NUCL PHYS,W-6900 HEIDELBERG 1,GERMANY. OI Horanyi, Mihaly/0000-0002-5920-9226 NR 23 TC 248 Z9 248 U1 1 U2 6 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD APR 1 PY 1993 VL 362 IS 6419 BP 428 EP 430 DI 10.1038/362428a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KV424 UT WOS:A1993KV42400075 ER PT J AU DUVALL, TL JEFFERIES, SM HARVEY, JW POMERANTZ, MA AF DUVALL, TL JEFFERIES, SM HARVEY, JW POMERANTZ, MA TI TIME DISTANCE HELIOSEISMOLOGY SO NATURE LA English DT Article ID ACOUSTIC MODES; SOLAR; OSCILLATIONS AB THE application of seismology to the study of the solar interior1,2 (helioseismology) has advanced almost solely by the prediction and measurement of the Sun's frequencies of free oscillation, or normal modes. Direct measurement of the travel times and distances of individual acoustic waves-the predominant approach in terrestrial seismology3-would appear to be more difficult in view of the number and stochastic nature of solar seismic sources. Here, however, we show that it is possible to extract time-distance information from temporal cross-correlations of the intensity fluctuations on the solar surface. This approach opens the way for seismic studies of local solar phenomena, such as subsurface inhomogeneities near sunspots, and should help to refine global models of the internal velocity stratification in the Sun. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. RP DUVALL, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Duvall, Thomas/C-9998-2012 NR 17 TC 518 Z9 519 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD APR 1 PY 1993 VL 362 IS 6419 BP 430 EP 432 DI 10.1038/362430a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KV424 UT WOS:A1993KV42400076 ER PT J AU STIEGMAN, AE BRUEGGE, CJ SPRINGSTEEN, AW AF STIEGMAN, AE BRUEGGE, CJ SPRINGSTEEN, AW TI ULTRAVIOLET STABILITY AND CONTAMINATION ANALYSIS OF SPECTRALON DIFFUSE REFLECTANCE MATERIAL SO OPTICAL ENGINEERING LA English DT Article DE SPECTRALON; POLYTETRAFLUOROETHYLENE; DIFFUSE REFLECTANCE STANDARDS; CALIBRATION; FLIGHT QUALIFICATION; SPACE EXPOSURE ENVIRONMENTAL TESTING; MULTIANGLE IMAGING SPECTRORADIOMETER (MISR); EARTH OBSERVING SYSTEM AB A detailed chemical analysis was carried out on Spectralon, a highly Lambertian, diffuse reflectance material. Results of this investigation unambiguously identified the presence of an organic (hydrocarbon) impurity intrinsic to the commercial material. This impurity could be removed by a vacuum bake-out procedure and was identified as the cause of optical changes (degradation) that occur in the material when exposed to UV light. It was found that when this impurity was removed, the Spectralon material was photochemically stable and maintained its reflectance properties even after extensive solar UV exposure. C1 LABSPHERE INC,N SUTTON,NH 03264. RP STIEGMAN, AE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 TC 41 Z9 42 U1 0 U2 5 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 APR PY 1993 VL 32 IS 4 BP 799 EP 804 DI 10.1117/12.132374 PG 6 WC Optics SC Optics GA KW554 UT WOS:A1993KW55400025 ER PT J AU BRUEGGE, CJ STIEGMAN, AE RAINEN, RA SPRINGSTEEN, AW AF BRUEGGE, CJ STIEGMAN, AE RAINEN, RA SPRINGSTEEN, AW TI USE OF SPECTRALON AS A DIFFUSE REFLECTANCE STANDARD FOR IN-FLIGHT CALIBRATION OF EARTH-ORBITING SENSORS SO OPTICAL ENGINEERING LA English DT Article DE SPECTRALON; POLYTETRAFLUOROETHYLENE; DIFFUSE REFLECTANCE STANDARDS; CALIBRATION; FLIGHT QUALIFICATION; SPACE ENVIRONMENT EXPOSURE TESTING; MULTIANGLE IMAGING SPECTRORADIOMETER; EARTH OBSERVING SYSTEM AB For the Multiangle Imaging SpectroRadiometer (MISR), currently under development for the Earth Observing System, we plan to use deployable diffuse reflectance panels to provide a flight calibration of its nine cameras. Near-lambertian reflectance characteristics are desirable to facilitate flat-field camera intercomparisons and to allow each camera to be calibrated under the same illumination levels. Panel spatial and spectral uniformity and stability with time are also required. Spectralon(TM), a commercially available diffuse reflectance material made from polytetrafluoroethylene (PTFE), has been baselined in the MISR design. To assess the suitability of this material, a series of environmental exposure tests were performed. No degradation of the optical properties was apparent following proton bombardment, and stability through UV illumination was satisfactory, provided simple cleaning and handling procedures were implemented. One surprise during the testing, however, was a buildup of several thousand volts of static charge, which developed while simulating a rare pass through an auroral storm. Such a potential for charge buildup is not unique to PTFE, but exists for many thermal control paints used to cover spacecraft exteriors. Further testing of the charged Spectralon failed to produce arcing to the metallic housing frame, and models indicate that charge neutralization will occur after passage through the storm. For these reasons we intend to fly Spectralon as per our original plan. C1 LAPSPHERE INC,N SUTTON,NH 03264. RP BRUEGGE, CJ (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 58 Z9 59 U1 0 U2 6 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 APR PY 1993 VL 32 IS 4 BP 805 EP 814 DI 10.1117/12.132373 PG 10 WC Optics SC Optics GA KW554 UT WOS:A1993KW55400026 ER PT J AU SCHEPS, R MYERS, JF GLESNE, TR SERREZE, HB AF SCHEPS, R MYERS, JF GLESNE, TR SERREZE, HB TI MONOCHROMATIC END-PUMPED OPERATION OF AN ALEXANDRITE LASER SO OPTICS COMMUNICATIONS LA English DT Article ID DIODES; CW AB Operation of an alexandrite laser pumped by short wavelength visible laser diodes is described. Two polarization-combined 640 nm diodes produced 25 mW output at 753 nm. Characterization measurements were performed with a dye laser. The best slope efficiency measured was 63.8%, close to the calculated intrinsic efficiency and the highest reported for a Cr3+-doped laser. The threshold power was 5.5 mW and the measured passive resonator loss was 0.06% cm. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MCDONNELL DOUGLAS ELECTR SYST CO,CTR OPTOELECTR,ELMSFORD,NY 10523. RP SCHEPS, R (reprint author), USN COMMAND,CTR CONTROL & OCEAN SURVEILLANCE,DIV RDT&E,CODE 754,SAN DIEGO,CA 92152, USA. NR 14 TC 16 Z9 16 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 J9 OPT COMMUN JI Opt. Commun. PD APR 1 PY 1993 VL 97 IS 5-6 BP 363 EP 366 DI 10.1016/0030-4018(93)90504-X PG 4 WC Optics SC Optics GA KR756 UT WOS:A1993KR75600015 ER PT J AU JOSEPH, RM GOORJIAN, PM TAFLOVE, A AF JOSEPH, RM GOORJIAN, PM TAFLOVE, A TI DIRECT TIME INTEGRATION OF MAXWELL EQUATIONS IN 2-DIMENSIONAL DIELECTRIC WAVE-GUIDES FOR PROPAGATION AND SCATTERING OF FEMTOSECOND ELECTROMAGNETIC SOLITONS SO OPTICS LETTERS LA English DT Article AB We present what are to our knowledge first-time calculations from vector nonlinear Maxwell's equations of femtosecond soliton propagation and scattering, including carrier waves, in two-dimensional dielectric waveguides. The time integration efficiently implements linear and nonlinear convolutions for the electric polarization, and the nonlinear convolution accounts for two quantum effects, the Kerr and Raman interactions. By retaining the optical carrier, the new method solves for fundamental quantities-optical electric and magnetic fields in space and time-rather than a nonphysical envelope function. It has the potential to provide an unprecedented two- and three-dimensional modeling capability for millimeter-scale integrated-optical circuits with submicrometer engineered inhomogeneities. C1 NORTHWESTERN UNIV, MCCORMICK SCH ENGN, DEPT ELECT ENGN & COMP SCI, EVANSTON, IL 60208 USA. RP NASA, AMES RES CTR, MAIL STOP 202A-2, MOFFETT FIELD, CA 94035 USA. RI Taflove, Allen/B-7275-2009 NR 5 TC 54 Z9 54 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 EI 1539-4794 J9 OPT LETT JI Opt. Lett. PD APR 1 PY 1993 VL 18 IS 7 BP 491 EP 493 DI 10.1364/OL.18.000491 PG 3 WC Optics SC Optics GA KU378 UT WOS:A1993KU37800007 PM 19802177 ER PT J AU MIDDLETON, EM TERAMURA, AH AF MIDDLETON, EM TERAMURA, AH TI POTENTIAL ERRORS IN THE USE OF CELLULOSE DIACETATE AND MYLAR FILTERS IN UV-B RADIATION STUDIES SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Note ID PHOTON FLUX-DENSITY; ULTRAVIOLET-B; NET PHOTOSYNTHESIS; IRRADIANCES; IRRADIATION; PLANTS AB The increase in UV-B radiation (290-320 nm) penetrating to the earth's surface as a result of the chemical depletion of the stratospheric ozone layer is an important environmental concern. In most studies using UV-B sources, the determination of enhanced UV-B radiation effects on plants relies on equivalent UV-A radiation (320-400 nm) from the experimental UV-B fluorescent lamp source, filtered with either cellulose diacetate (CA) to create UV-B treatments, or with type S Mylar or polyester (PE) to create controls (no UV-B). The spectral in the UV-A was measured in the dark below lamps at two daily UV-B irradiance levels (14.1 and 10.7 kJ m-2) with CA and PE at two ages. Highly significant differences in UV-A radiation (P less-than-or-equal-to 0.01) were measured below the treatment/control pairs at both fluence rates and filter ages. Filter aging was observed, which reduced the UV-A irradiance, especially for PE. The total daily ambient UV-A irradiance was also determined in the glasshouse at three seasons: the fall equinox, summer and winter, from which the total daily UV-A (lamp + ambient) irradiances were calculated. The addition of low to moderate ambient irradiance removed the treatment/control differences in the longwave UV-A (350-400 nm); however, the treatment/control differences remained in the shortwave UV-A (320-350 nm), which was restricted by the glass, and in the total UV-A. The treatment/control differences persisted in the shortwave UV-A for the higher irradiance level, even under high summer ambient light. Also, spectral ratios (UV-B:UV-A and shortwave:longwave UV-A) for all treatment groups decreased as the ambient UV-A radiation increased. Therefore, a range of experimental conditions exist where PE-covered lamps do not provide adequate control for UV-A irradiance, relative to the CA treatment, for glasshouse/growth chamber experiments. Potential complications in the interpretation of plant response exist for UV-B experiments conducted under low ambient light conditions (e.g. growth chambers; glasshouse in winter) or high daily UV-B irradiances (eg. greater-than-or-equal-to 14 kJ m-2) for those plant responses that are sensitive to UV-A radiation. C1 UNIV MARYLAND,DEPT BOT,COLL PK,MD 20744. RP MIDDLETON, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERRESTRIAL PHYS LAB,GREENBELT,MD 20771, USA. NR 29 TC 39 Z9 40 U1 0 U2 1 PU AMER SOC PHOTOBIOLOGY PI AUGUSTA PA BIOTECH PARK, 1021 15TH ST, SUITE 9, AUGUSTA, GA 30901-3158 SN 0031-8655 J9 PHOTOCHEM PHOTOBIOL JI Photochem. Photobiol. PD APR PY 1993 VL 57 IS 4 BP 744 EP 751 DI 10.1111/j.1751-1097.1993.tb02948.x PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA LB366 UT WOS:A1993LB36600028 ER PT J AU ARTONI, M ZANG, J BIRMAN, JL AF ARTONI, M ZANG, J BIRMAN, JL TI ANHARMONIC AND NONCLASSICAL EFFECTS OF THE QUANTUM-DEFORMED HARMONIC-OSCILLATOR SO PHYSICAL REVIEW A LA English DT Article ID CONFORMAL FIELD-THEORIES; YANG-BAXTER EQUATION; SQUEEZED STATES; Q-ANALOGS AB An isomorphism is realized between the (q)-deformed harmonic oscillator and a particular anharmonic oscillator model: it permits insight into the problem of the physics behind the deformation parameter q. In our model, the anharmonic coupling strength is shown to be proportional to q. The isomorphism permits us also to analyze and to interpret the appearance of various nonclassical features induced by a q deformation during the time evoluton of an su(2) coherent state. C1 CUNY CITY COLL,DEPT PHYS,NEW YORK,NY 10031. RP ARTONI, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PHOTON CODE 715,GREENBELT,MD 20771, USA. NR 41 TC 12 Z9 12 U1 0 U2 0 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 APR PY 1993 VL 47 IS 4 BP 2555 EP 2561 DI 10.1103/PhysRevA.47.2555 PN A PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA KW308 UT WOS:A1993KW30800027 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI DOUBLY EXCITED (1,3)P(E) STATES IN HELIUM-LIKE SYSTEMS SO PHYSICAL REVIEW A LA English DT Article ID COLLISION AB Doubly excited or Feshbach-type resonant states in heliumlike systems, Z = 2-10, have been calculated using the complex-rotation method. Using Hylleraas-type wave functions having up to 825 terms, we predict resonance parameters (both resonance positions and widths) below the N = 3, 4, and 5 thresholds of the hydrogenic systems. The present results for Z = 7 and 8 are compared with those of the close-coupling calculations and experimental results where available. 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 8 TC 27 Z9 28 U1 0 U2 2 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 APR PY 1993 VL 47 IS 4 BP 2628 EP 2633 DI 10.1103/PhysRevA.47.2628 PN A PG 6 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA KW308 UT WOS:A1993KW30800036 ER PT J AU LASSEIGNE, DG HUSSAINI, MY AF LASSEIGNE, DG HUSSAINI, MY TI INTERACTION OF DISTURBANCES WITH AN OBLIQUE DETONATION-WAVE ATTACHED TO A WEDGE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID VORTICITY AB The linear response of an oblique overdriven detonation to imposed free-stream disturbances or to periodic movements of the wedge is examined. The free-stream disturbances are assumed to be steady vorticity waves and the wedge motions are considered to be time periodic oscillations either about a fixed pivot point or along the plane of symmetry of the wedge aligned with the incoming stream. All disturbances are assumed to have wavelengths large compared to the thickness of the detonation so that the detonation is considered to be a region of infinitesimal thickness in which a finite amount of heat is released. The response to the imposed disturbances is a function of the Mach number of the incoming flow, the wedge angle, and the exothermicity of the reaction within the detonation. It is shown that, as the degree of overdrive increases, the amplitude of the response increases significantly; furthermore, a fundamental difference in the dependence of the response on the parameters of the problem is found between the response to a free-stream disturbance and to a disturbance emanating from the wedge surface. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP LASSEIGNE, DG (reprint author), OLD DOMINION UNIV,DEPT MATH & STAT,NORFOLK,VA 23529, USA. NR 14 TC 3 Z9 3 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 APR PY 1993 VL 5 IS 4 BP 1047 EP 1058 DI 10.1063/1.858669 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KU148 UT WOS:A1993KU14800025 ER PT J AU DOUGHERTY, MK SOUTHWOOD, DJ BALOGH, A SMITH, EJ AF DOUGHERTY, MK SOUTHWOOD, DJ BALOGH, A SMITH, EJ TI FIELD-ALIGNED CURRENTS IN THE JOVIAN MAGNETOSPHERE DURING THE ULYSSES FLYBY SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SHEET; IO AB The data recorded by the dual vector helium/fluxgate magnetometer flown onboard the Ulysses spacecraft during the flyby of Jupiter in February 1992 are analysed with the aim of identifying the presence of field-aligned current signatures. Field-aligned current flow is expected wherever stress is being transmitted electromagnetically along the magnetic field direction. Sources of such currents at Jupiter are departures within the magnetosphere from corotation, momentum transfer from the solar wind, or centrifugally driven magnetospheric outflow. It is pointed out that the azimuthal field component provides a simple first-order means of monitoring the presence of currents, the currents occurring in regions where the azimuthal component changes significantly. The data from both inbound and outbound passes show evidence of ''leading'' and ''lagging'' azimuthal field signatures where the field bends out of the meridian, and which are signatures symptomatic of current systems associated with departures from corotation. On the outbound pass, the most intense signatures are found where the field switches from a configuration symptomatic of the field lagging corotation to a configuration representing the field leading. The latter configuration also corresponds to a tail-like displacement of the field and, indeed, the magnetometer data alone cannot distinguish the source of the current system, which could be due to solar wind magnetosphere coupling or which may arise from internal stress imbalance. C1 JET PROP LAB,PASADENA,CA 91109. RP DOUGHERTY, MK (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,LONDON SW7 2BZ,ENGLAND. NR 26 TC 33 Z9 33 U1 0 U2 4 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 APR PY 1993 VL 41 IS 4 BP 291 EP 300 DI 10.1016/0032-0633(93)90024-V PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA LK637 UT WOS:A1993LK63700004 ER PT J AU ADELMAN, SJ ROBINSON, RD WAHLGREN, GM AF ADELMAN, SJ ROBINSON, RD WAHLGREN, GM TI ELEMENTAL ABUNDANCES OF THE B6 IV-STAR XI OCTANTIS SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID OSCILLATOR-STRENGTHS; SI-II; SOLAR; IRON AB An elemental abundance study utilized AAT echelle spectrograms of the ultrasharp-lined superficially normal B6 IV star xi Octantis. The derived abundances fall within the trends of values derived for normal B main-sequence band stars. On average they are 0.28 dex less than solar. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. RP ADELMAN, SJ (reprint author), CITADEL,DEPT PHYS,CHARLESTON,SC 29409, USA. NR 20 TC 12 Z9 12 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 APR PY 1993 VL 105 IS 686 BP 327 EP 331 DI 10.1086/133158 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KY948 UT WOS:A1993KY94800001 ER PT J AU BADHWAR, GD CUCINOTTA, FA ONEILL, PM AF BADHWAR, GD CUCINOTTA, FA ONEILL, PM TI DEPTH DOSE EQUIVALENT RELATIONSHIP FOR COSMIC-RAYS AT VARIOUS SOLAR MINIMA SO RADIATION RESEARCH LA English DT Article C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP BADHWAR, GD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 28 TC 17 Z9 17 U1 0 U2 4 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 APR PY 1993 VL 134 IS 1 BP 9 EP 15 DI 10.2307/3578496 PG 7 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA KY744 UT WOS:A1993KY74400002 PM 8475259 ER PT J AU VERMA, SB SELLERS, PJ WALTHALL, CL HALL, FG KIM, J GOETZ, SJ AF VERMA, SB SELLERS, PJ WALTHALL, CL HALL, FG KIM, J GOETZ, SJ TI PHOTOSYNTHESIS AND STOMATAL CONDUCTANCE RELATED TO REFLECTANCE ON THE CANOPY SCALE SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID TEMPERATE GRASSLAND ECOSYSTEM; TALLGRASS PRAIRIE; SURFACE; HEAT; TRANSPIRATION; VEGETATION; RADIATION; MOMENTUM; EXCHANGE; DIOXIDE AB Field measurements Of carbon dioxide and water vapor fluxes were analyzed in conjunction with reflectances obtained from a helicopter-mounted Modular Multiband Radiometer (MMR) at a grassland study site during the First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE). These measurements are representative of the canopy scale and were made over a range of meteorological and soil moisture conditions during different stages in the annual life cycle of the prairie vegetation, and thus provide a good basis for investigating hypotheses/relationships potentially useful in remote sensing applications. We tested the hypothesis (Sellers, 1987) that the simple ratio vegetation index (SR) should be near-linearly related to the derivatives of the unstressed canopy stomatal conductance (g*c) and the unstressed canopy photosynthesis (P*c) with respect to photosynthetically active radiation (PAR). Even though there is some scatter in our data, the results seem to support this hypothesis. Further investigation, however, is needed before such relationships can be employed in satellite remote sensing applications C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,DEPT GEOG,GLOBAL REMOTE SENSING STUDIES LAB,COLL PK,MD 20742. RP VERMA, SB (reprint author), UNIV NEBRASKA,DEPT AGR METEOROL,POB 830728,LINCOLN,NE 68583, USA. RI Goetz, Scott/A-3393-2015 OI Goetz, Scott/0000-0002-6326-4308 NR 41 TC 39 Z9 41 U1 0 U2 4 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 APR PY 1993 VL 44 IS 1 BP 103 EP 116 DI 10.1016/0034-4257(93)90106-8 PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA KU006 UT WOS:A1993KU00600008 ER PT J AU CAMP, JB WITTEBORN, FC AF CAMP, JB WITTEBORN, FC TI EFFECT OF COULOMB INTERACTION ON TIME-OF-FLIGHT OF COLD ANTIPROTONS LAUNCHED FROM AN ION TRAP SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Time-of-flight spectra for Maxwell-Boltzman (MB) distributions of antiprotons initially held in an ion trap and detected after being launched through a 50-cm-long shielding drift tube have been calculated. The distributions used are of temperature 0.4-40 K, cubic length 0.003-3.0 cm, and number 10-100 particles. The mutual Coulomb repulsion of the particles causes a reduction in the number of late arrival particles expected from the MB velocity distribution. The Coulomb energy is not equally divided among the particles during the expansion. The energy is transferred preferentially to the outer particles so that the reduction in the number of slow particles is not necessarily large. The reduction factor is found to be greater than unity when the potential energy of the trapped ions is greater than approximately 5 % of the ions' kinetic energy and is approximately 2 for the launch parameters of the Los Alamos antiproton gravity experiment. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CAMP, JB (reprint author), LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545, USA. NR 4 TC 0 Z9 0 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 APR PY 1993 VL 64 IS 4 BP 854 EP 857 DI 10.1063/1.1144132 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA KX401 UT WOS:A1993KX40100002 ER PT J AU RICCITIELLO, SR HSU, MS CHEN, TS AF RICCITIELLO, SR HSU, MS CHEN, TS TI CERAMIC FIBERS FROM SI-B-C POLYMER PRECURSORS SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article ID PYROLYSIS AB Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. Silicon carbide fiber (Nicalon), for example, has been successfully produced by the polymer-pyrolysis route, and is presently available from Nippon Carbon. More recently, other fibers have been made available, such as the silicon nitride fiber from Dow Corning Co. and Tyranno fiber from Textron Specialty Materials. The above mentioned fibers, when tested over a temperature range from 25-degrees-C to 1400-degrees-C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied. C1 HC CHEM RES & SERV CORP,SAN JOSE,CA. RP RICCITIELLO, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 0 Z9 0 U1 1 U2 2 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD APR PY 1993 VL 24 IS 3 BP 9 EP 14 PG 6 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA LB615 UT WOS:A1993LB61500002 ER PT J AU JACOBSON, NS AF JACOBSON, NS TI THERMOCHEMICAL LIMITATIONS OF CERAMIC MATERIALS SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article ID SILICON-CARBIDE; MATRIX COMPOSITES; OXIDATION; VAPOR; TOUGHNESS; NITRIDE AB Nonoxide and oxide ceramics and composites are classes of potentially useful high-temperature materials. The ultimate temperature capabilities of these materials have both thermomechanical and thermochemical limitations. In this paper, the major thermochemical limitations are explored. For nonoxides such as SiC, Si3N4, and A1N, these limitations are oxidation and volatility (external reactions) and phase changes and interfacial reactions (internal reactions). For oxides such as Al2O3 and stabilized ZrO2, these limitations are volatility, phase changes, and interfacial reactions. Where possible, specific upper temperature limits are set. RP JACOBSON, NS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009 NR 40 TC 2 Z9 2 U1 0 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD APR PY 1993 VL 24 IS 3 BP 51 EP 58 PG 8 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA LB615 UT WOS:A1993LB61500009 ER PT J AU KRAEMER, SK AF KRAEMER, SK TI BLUEPRINT FOR SPACE - SCIENCE-FICTION TO SCIENCE FACT - ORDWAY,FI, LIEBERMANN,R SO TECHNOLOGY AND CULTURE LA English DT Book Review RP KRAEMER, SK (reprint author), NASA,OFF SPECIAL STUDIES,WASHINGTON,DC 20546, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0040-165X J9 TECHNOL CULT JI Technol. Cult. PD APR PY 1993 VL 34 IS 2 BP 461 EP 462 DI 10.2307/3106575 PG 2 WC History & Philosophy Of Science SC History & Philosophy of Science GA LH981 UT WOS:A1993LH98100044 ER PT J AU WESSEL, VW AF WESSEL, VW TI TECHNOLOGY-TRANSFER AND INTELLECTUAL PROPERTY - AN ANALYSIS OF THE NASA APPROACH SO TECHNOVATION LA English DT Article AB The decade of the 1980s saw significant developments in the promulgation of regulations and legislation governing intellectual property (patents and licenses) at US Government research and development (R&D) laboratories. These actions were part of a deliberate effort on the part of the US to (1) increase the quantity and quality of technological innovations at government R&D laboratories; (2) encourage their timely transfer into the private sector; and (3) stimulate a sagging US economy. New-technology inventions were viewed as a valued but essentially dormant national resource, one which, if cultivated, could furnish the catalyst for an improved economy both at home and abroad. A brief review of the Intellectual Property Program developed by the National Aeronautics and Space Administration (NASA) and the legislation governing it is provided in this report. While the productivity of the program at all NASA centers is evaluated over the decade of the 1980s, particular focus is given to the three NASA R&D centers. Conclusions regarding the program at each of the centers are drawn, and some options are proposed for future consideration. RP WESSEL, VW (reprint author), NASA,LANGLEY RES CTR,DIV SYST SAFETY QUAL & RELIABIL,RISK MANAGEMENT BRANCH,MAIL STOP 429,HAMPTON,VA 23681, USA. NR 0 TC 2 Z9 2 U1 0 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0166-4972 J9 TECHNOVATION JI Technovation PD APR PY 1993 VL 13 IS 3 BP 133 EP 146 DI 10.1016/0166-4972(93)90036-U PG 14 WC Engineering, Industrial; Management; Operations Research & Management Science SC Engineering; Business & Economics; Operations Research & Management Science GA LG993 UT WOS:A1993LG99300002 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H AF BAUSCHLICHER, CW PARTRIDGE, H TI ON THE INVARIANCE OF THE CONFIGURATION-INTERACTION ENERGY WITH RESPECT TO ORBITAL ROTATIONS SO THEORETICA CHIMICA ACTA LA English DT Article DE CONFIGURATION INTERACTION ENERGY; CI; INVARIANCE; ORBITAL ROTATIONS ID SPACES AB The invariance of the configuration interaction (CI) energy with respect to orbital rotation is considered. The inclusion of all spin couplings versus only those from the first-order interacting space is considered. A definition for the analog of a second-order CI calculation when inactive electrons are present is proposed. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 7 TC 7 Z9 7 U1 0 U2 3 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD APR PY 1993 VL 85 IS 4 BP 255 EP 259 DI 10.1007/BF01129115 PG 5 WC Chemistry, Physical SC Chemistry GA LA222 UT WOS:A1993LA22200002 ER PT J AU ARMSTRONG, JW AF ARMSTRONG, JW TI BISPECTRAL ANALYSIS OF SPACECRAFT RADIO SCINTILLATION SO WAVES IN RANDOM MEDIA LA English DT Article AB Strong intensity scintillations are characterized by a positively skewed probability density function. For such non-Gaussian processes, the power spectrum is not a complete statistical description. In this paper I present the simplest of the higher-order spectra, the bispectrum, of interplanetary intensity scintillation (IPS) data taken in the transition between weak and strong scattering. The bispectrum is the Fourier transform of the third-order lagged product, . As the spectrum gives the contribution to the variance from two Fourier components having frequencies that add to zero, the bispectrum gives the contribution to the third moment from the product of three Fourier components having frequencies that add to zero. The bispectra computed here are of the monochromatic S-band beacon onboard the Pioneer Venus spacecraft. This use of a monochromatic point source eliminates complications in the interpretation caused by filtering. of the third moment by finite bandwidth and finite angular source size. The spectrum, probability density function (PDF), and bispectrum are related and thus the measurement of all these quantities can be used to check for internal consistency. In this paper this internal consistency check is done by analysing these three statistics of IPS intensity data for moderate strength scintillation. RP ARMSTRONG, JW (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0959-7174 J9 WAVE RANDOM MEDIA JI Waves Random Media PD APR PY 1993 VL 3 IS 2 BP 63 EP 70 DI 10.1088/0959-7174/3/2/001 PG 8 WC Physics, Multidisciplinary SC Physics GA LQ056 UT WOS:A1993LQ05600001 ER PT J AU PATNAIK, SN GUPTILL, JD BERKE, L AF PATNAIK, SN GUPTILL, JD BERKE, L TI SINGULARITY IN STRUCTURAL OPTIMIZATION SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID INTEGRATED FORCE METHOD; FINITE-ELEMENT ANALYSIS; CONSTRAINTS; BEHAVIOR AB Singularity conditions that arise during structural optimization can seriously degrade the performance of the optimizer. The singularities are intrinsic to the formulation of the structural optimization problem and are not associated with the method of analysis. Certain conditions that give rise to singularities in linear elastic structures have been identified in earlier papers, along with a proposition to alleviate the consequences of their presence.1-3 These singularities were global in nature, encompassing the entire structure. Further examination revealed more complex sets of conditions in which singularities occur. Some of these singularities are local in nature, being associated with only a segment of the structure. Moreover, the likelihood that one of these local singularities may arise during an optimization procedure can be much greater than that of the global singularity identified earlier. This paper provides examples of these additional forms of singularities. It gives a framework in which these singularities can be recognized. In particular, the singularities can be identified by examination of the stress-displacement relations along with the compatibility conditions and/or the displacement-stress relations derived in the integrated force method of structural analysis. Methods for the elimination of the effects of these singularities are suggested and numerical illustrations are given. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PATNAIK, SN (reprint author), OHIO AEROSP INST,BROOK PK,OH 44142, USA. NR 15 TC 17 Z9 17 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD MAR 30 PY 1993 VL 36 IS 6 BP 931 EP 944 DI 10.1002/nme.1620360604 PG 14 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA KU310 UT WOS:A1993KU31000003 ER PT J AU KIM, SS YAVROUIAN, AH LIANG, RH AF KIM, SS YAVROUIAN, AH LIANG, RH TI SEGMENTAL MOBILITY AND FREE-VOLUME DECAY OF POLY(PHENYL METHACRYLATE) - AN EPR STUDY SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Note DE SEGMENTAL MOBILITY; FREE-VOLUME; POLY(PHENYL METHACRYLATE); EPR ID RESONANCE RP KIM, SS (reprint author), JET PROP LAB,SPACE MAT SCI & TECHNOL SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 10 Z9 10 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-6266 J9 J POLYM SCI POL PHYS JI J. Polym. Sci. Pt. B-Polym. Phys. PD MAR 30 PY 1993 VL 31 IS 4 BP 495 EP 499 DI 10.1002/polb.1993.090310417 PG 5 WC Polymer Science SC Polymer Science GA KM701 UT WOS:A1993KM70100017 ER PT J AU BHATIA, AK SCHNEIDER, BI TEMKIN, A AF BHATIA, AK SCHNEIDER, BI TEMKIN, A TI ABINITIO METHOD FOR CALCULATING TOTAL CROSS-SECTIONS SO PHYSICAL REVIEW LETTERS LA English DT Article ID ELECTRON-HYDROGEN SCATTERING; INTERMEDIATE ENERGIES; SIMPLIFIED MODEL AB A method for calculating total cross sections without formally including nonelastic channels is presented. The idea is to use a one channel T-matrix variational principle with a complex correlation function. The derived T matrix is therefore not unitary: Elastic scattering is calculated from \T\2, but total scattering is derived from the imaginary part of T using the optical theorem. The method is applied to the spherically symmetric model of electron-hydrogen scattering. No spurious structure arises; results for sigma(el) and sigma(total) are in excellent agreement with calculations of Callaway and Oza. The method has wide potential applicability. C1 NATL SCI FDN,DIV PHYS,WASHINGTON,DC 20550. RP BHATIA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 680,GREENBELT,MD 20771, USA. NR 21 TC 16 Z9 16 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD MAR 29 PY 1993 VL 70 IS 13 BP 1936 EP 1939 DI 10.1103/PhysRevLett.70.1936 PG 4 WC Physics, Multidisciplinary SC Physics GA KU171 UT WOS:A1993KU17100011 ER PT J AU KRAUS, WB GLASGOW, MB KIM, MY OLMEIJER, DL KIEFER, RL ORWOLL, RA AF KRAUS, WB GLASGOW, MB KIM, MY OLMEIJER, DL KIEFER, RL ORWOLL, RA TI BORON CONTAINING POLYMERS FOR RADIATION SHIELDING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. COLL WILLIAM & MARY,DEPT CHEM,WILLIAMSBURG,VA 23187. COLL WILLIAM & MARY,PROGRAM APPL SCI,WILLIAMSBURG,VA 23187. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 23 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300873 ER PT J AU OGLESBY, DM UPCHURCH, BT LEIGHTY, BD COLLMAN, JP ZHANG, XM HERRMANN, PC AF OGLESBY, DM UPCHURCH, BT LEIGHTY, BD COLLMAN, JP ZHANG, XM HERRMANN, PC TI SURFACE ACOUSTIC-WAVE OXYGEN SENSOR SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 OLD DOMINION UNIV,DEPT CHEM & BIOCHEM,NORFOLK,VA 23508. NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,HAMPTON,VA 23665. STANFORD UNIV,DEPT CHEM,STANFORD,CA 94305. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 23 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ981 UT WOS:A1993KQ98100249 ER PT J AU KOJIRO, DR HUMPHRY, DE TAKEUCHI, N COHEN, MJ STIMAC, RM WERNLUND, RF AF KOJIRO, DR HUMPHRY, DE TAKEUCHI, N COHEN, MJ STIMAC, RM WERNLUND, RF TI ENHANCEMENT OF IMS SAMPLE IONIZATION IN AN ALL HELIUM ENVIRONMENT SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SETI INST,MT VIEW,CA 94043. IMA NORCAL,RICHMOND,CA 94804. PCP INC,W PALM BEACH,FL 33409. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 32 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ981 UT WOS:A1993KQ98100258 ER PT J AU SHEN, TC KOJIRO, DR AF SHEN, TC KOJIRO, DR TI PYROSENSORS FOR ANALYZING OXIDANTS IN MARTIAN SOIL SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 48 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ981 UT WOS:A1993KQ98100273 ER PT J AU JENSEN, BJ AF JENSEN, BJ TI PHOSPHINE OXIDE CONTAINING IMIDE ARYLENE ETHER COPOLYMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 51 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300901 ER PT J AU JENSEN, BJ HERGENROTHER, PM NWOKOGU, G AF JENSEN, BJ HERGENROTHER, PM NWOKOGU, G TI POLY(ARYLENE ETHER)S WITH PENDENT ETHYNYL GROUPS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. HAMPTON UNIV,HAMPTON,VA 23668. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 52 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300902 ER PT J AU UPCHURCH, BT SCHRYER, DR WOOD, GM KIELIN, EJ BROWN, KG AF UPCHURCH, BT SCHRYER, DR WOOD, GM KIELIN, EJ BROWN, KG TI LOW-TEMPERATURE OXIDATION CATALYSTS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,HAMPTON,VA 23681. OLD DOMINION UNIV,DEPT CHEM & BIOCHEM,NORFOLK,VA 23529. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 66 EP CATL PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98301672 ER PT J AU CONNELL, JW SMITH, JG HERGENROTHER, PM AF CONNELL, JW SMITH, JG HERGENROTHER, PM TI OXYGEN PLASMA RESISTANT POLYIMIDES AND POLY(ARYLENE ETHER HETEROCYCLE)S CONTAINING PHENYL PHOSPHINE OXIDE GROUPS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 1 Z9 1 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 84 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300934 ER PT J AU SOUCEK, MD PATER, RH RITENOUR, SL AF SOUCEK, MD PATER, RH RITENOUR, SL TI THE FORMATION OF CYCLOADDITION ADDUCTS IN THE REACTION OF AN ACETYLENE-TERMINATED MATERIAL WITH A BISMALEIMIDE - A MODEL-COMPOUND STUDY FOR ADDITION-TYPE THERMOPLASTICS (ATTS) USING METAL-CATALYSTS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 86 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300936 ER PT J AU BRYANT, RG JENSEN, BJ HERGENROTHER, PM AF BRYANT, RG JENSEN, BJ HERGENROTHER, PM TI SYNTHESIS AND PROPERTIES OF PHENYLETHYNYL-TERMINATED POLYIMIDES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 104 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300954 ER PT J AU KUNDU, KP DEUR, JM AF KUNDU, KP DEUR, JM TI REMOVAL OF NITROGEN-OXIDES FROM EXHAUST EMISSIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 118 EP ENVR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ981 UT WOS:A1993KQ98101831 ER PT J AU STOAKLEY, DM STCLAIR, AK CROALL, CI AF STOAKLEY, DM STCLAIR, AK CROALL, CI TI LOW DIELECTRIC, FLUORINATED POLYIMIDE COPOLYMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 170 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98301020 ER PT J AU STCLAIR, AK STCLAIR, TL AF STCLAIR, AK STCLAIR, TL TI POLYIMIDES CONTAINING PENTAFLUOROSULFANYLBENZENE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV ALABAMA,DEPT CHEM,TUSCALOOSA,AL 35487. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 172 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98301022 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI CONTROLLED MOLECULAR-WEIGHT POLY(ARYLENE ETHER BENZIMIDAZOLE)S ENDCAPPED WITH BENZIMIDAZOLE AND ACETYLENE GROUPS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 182 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98301032 ER PT J AU DATEO, CE AF DATEO, CE TI A NEW GLOBAL POTENTIAL-ENERGY SURFACE FOR THE HYDROPEROXYL RADICAL, HO2 SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,ELORET INST,MOFFETT FIELD,CA 94035. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 183 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300789 ER PT J AU LEE, TJ JAYATILAKA, D AF LEE, TJ JAYATILAKA, D TI EFFICIENT OPEN-SHELL COUPLED-CLUSTER AND PERTURBATION THEORIES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Jayatilaka, Dylan/B-3498-2012 OI Jayatilaka, Dylan/0000-0002-3349-5834 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 210 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98300816 ER PT J AU MACINNES, AN POWER, MB HEPP, AF BARRON, AR AF MACINNES, AN POWER, MB HEPP, AF BARRON, AR TI INDIUM TERT-BUTYLTHIOLATES AS SINGLE SOURCE PRECURSORS FOR INDIUM SULFIDE THIN-FILMS - IS MOLECULAR DESIGN ENOUGH SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 233 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ981 UT WOS:A1993KQ98102585 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI CONTROLLED MOLECULAR-WEIGHT POLY(ARYLENE ETHER BENZIMIDAZOLE)S ENDCAPPED WITH BENZIMIDAZOLE AND ACETYLENE GROUPS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD MAR 28 PY 1993 VL 205 BP 341 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA KQ983 UT WOS:A1993KQ98301191 ER PT J AU CARLSON, BE LACIS, AA ROSSOW, WB AF CARLSON, BE LACIS, AA ROSSOW, WB TI TROPOSPHERIC GAS-COMPOSITION AND CLOUD STRUCTURE OF THE JOVIAN NORTH EQUATORIAL BELT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID VOYAGER IRIS SPECTRA; GIANT PLANETS; INFRARED-ABSORPTION; PARA-HYDROGEN; JUPITERS ATMOSPHERE; OPTICAL-CONSTANTS; LIGHT-SCATTERING; CARBON-MONOXIDE; SOLAR-SYSTEM; NH3 ICE AB High spatial resolution Voyager infrared interferometer spectrometer spectra of the North Equatorial Belt (NEB) reveal longitudinal variability of 5-mum brightness temperatures of order 100-degrees-C. These observations are used to investigate spatial variations in the gas composition and cloud structure of the NEB. We use an anisotropic multiple scattering radiative transfer model to calculate synthetic spectra for comparison with the IRIS observations. The spectral dependence of cloud extinction from 180 to 2300 cm-1 is modeled using Mie theory. The entire spectral range of the IRIS observations (180-2300 cm-1) is used to constrain the cloud properties and vertical structure of the NEB. Within the model, cloud base locations vary with assumed gas abundances according to thermochemical equilibrium. We find that spatial variations in the abundance profiles of the condensible species, para hydrogen profiles and cloud optical depths can be used as tracers of the local and large-scale dynamics. Based on the spectral dependence of NH3 cloud extinction that is required to fit the IRIS observations, we conclude that the bulk of the NH3 cloud extinction is provided by large particles, effective radii almost-equal-to 100 mum; however, a small particle mode may also be present. We find that the observed 5-mum brightness temperature structure can be reproduced by spatial variations in cloud opacity and water relative humidity. NEB hot spots, due to their low cloud opacity, provide a unique opportunity to study the deep cloud structure in the Jovian atmosphere. Cloud opacity is required at P > 4 bars (coincident with the location of the thermochemically predicted H2O cloud) to reproduce the observed continuum level near 2130 cm-1, as well as to model the overall shape of the continuum between 2100 and 2300 cm-1. Water relative humidity is found to vary spatially above the base of the water cloud increasing from almost-equal-to 15% in hot spots to 100% in colder spectral ensembles. The variation of relative humidity is strongly correlated with the variation of cloud opacity, suggesting dynamic depletion of water vapor above the cloud forming level as the most plausible model to explain the spatial variation in the water profile within the NEB. RP NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, NEW YORK, NY USA. RI Lacis, Andrew/D-4658-2012; Carlson, Barbara/D-8319-2012; Rossow, William/F-3138-2015 NR 97 TC 66 Z9 66 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1993 VL 98 IS E3 BP 5251 EP 5290 DI 10.1029/92JE02737 PG 40 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400001 ER PT J AU MIYAMOTO, M FURUTA, T FUJII, N MCKAY, DS LOFGREN, GE DUKE, MB AF MIYAMOTO, M FURUTA, T FUJII, N MCKAY, DS LOFGREN, GE DUKE, MB TI THE MN-FE NEGATIVE CORRELATION IN OLIVINES IN ALHA-77257 UREILITE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ANTARCTIC UREILITES; SILICATE LIQUID; PARENT BODY; ORIGIN; EVOLUTION; CONSTRAINTS; MINERALOGY; PETROLOGY; PYROXENES; GENESIS AB Mn, Fe, and oxygen zoning profiles of olivines in the ALHA 77257 ureilite were measured by an electron probe microanalyzer to study the effects of reduction on the Mn-Fe value, because ureilite olivines exhibit thin reduced rims. The Mn content gradually increases toward the rim of ureilite olivines as the Fa (= 100 x Fe/(Mg + Fe), mol %) component decreases, which suggests that the Mn-Fe content of olivine is related to redox conditions. A calculated diffusional cooling rate of 1-2-degrees-C/h gives the best fit to both the observed MnO and Fa chemical zoning profiles of ALHA 77257. The results of melting experiments suggest that the negative correlation of Mn-Fe in olivine and low-Ca pyroxene is related to reduction and that the Mn-Fe positive correlation is related to temperature. The Fe/Mn-Fe/Mg trend of olivine cores in ureilites may be established by the reduction process at about 1275-degrees-C. C1 UNIV TOKYO,OCEAN RES INST,TOKYO 113,JAPAN. KOBE UNIV,DEPT EARTH SCI,NADA KU,KOBE 657,JAPAN. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MIYAMOTO, M (reprint author), UNIV TOKYO,FAC SCI,INST MINERAL,BUNKYO KU,TOKYO 113,JAPAN. NR 42 TC 10 Z9 12 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 MAR 25 PY 1993 VL 98 IS E3 BP 5301 EP 5307 DI 10.1029/92JE02943 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400003 ER PT J AU CAPOBIANCO, CJ JONES, JH DRAKE, MJ AF CAPOBIANCO, CJ JONES, JH DRAKE, MJ TI METAL-SILICATE THERMOCHEMISTRY AT HIGH-TEMPERATURE - MAGMA OCEANS AND THE EXCESS SIDEROPHILE ELEMENT PROBLEM OF THE EARTHS UPPER MANTLE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CORE FORMATION; PARTITIONING BEHAVIOR; ORIGIN; MOON; OXYGEN; NI; CONSTRAINTS; LIQUID; IRON; MELT AB Recent theoretical considerations indicate that Earth should have been at least partly molten at the end of accretion and perhaps sufficiently to produce a magma ocean. Metal-silicate partition coefficients applicable to a magma ocean (3000 K-4000 K and up to 130 GPa) would be valuable to test such models against well-known mantle siderophile element abundances, but they have not been measured. However, an extrapolation of existing low temperature data to these extreme conditions has recently been attempted [Murthy, 1991]. Murthy's results seem to account for many apparent excesses of siderophile elements in the mantle. We examined his extrapolation method and found it to be inconsistent with published temperature dependencies for metal-silicate partition coefficients. We also attempted an extrapolation to magma ocean temperatures, based on known chemical behavior for several elements, and using published metal-silicate partition coefficients. If the chemistry quantified by the low-temperature data is applicable at high temperature, an important assumption, then our results indicate that high temperature alone will not help ameliorate the excess siderophile element problem of the upper mantle, in contrast to the conclusions of Murthy [1991]. For most elements, a modest increase in siderophile behavior is predicted with rising temperature if an iron-wustite redox buffer is paralleled. But long-range extrapolation of experimental data containing even modest experimental errors is hazardous. Extrapolated high-temperature partition coefficients can differ by orders of magnitude for a given element, even though the input from independent studies is consistent within quoted errors. Direct experimental measurements for at least some of the siderophile elements will be necessary to accurately assess siderophile element behavior in a magma ocean. The excess siderophile element problem of the Earth's upper mantle remains unsolved. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP CAPOBIANCO, CJ (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. NR 26 TC 40 Z9 40 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 MAR 25 PY 1993 VL 98 IS E3 BP 5433 EP 5443 DI 10.1029/92JE02742 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400015 ER PT J AU GIERASCH, PJ CONRATH, BJ AF GIERASCH, PJ CONRATH, BJ TI DYNAMICS OF THE ATMOSPHERES OF THE OUTER PLANETS - POST-VOYAGER MEASUREMENT OBJECTIVES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID RADIO OCCULTATION MEASUREMENTS; GREAT RED SPOT; INFRARED OBSERVATIONS; JUPITERS ATMOSPHERE; UPPER TROPOSPHERE; ENERGY-BALANCE; WAVES; STRATOSPHERE; VORTICES; SYSTEM AB Current knowledge about dynamics and thermal structure on the outer planets is reviewed with the aim of identifying important measurements which should be made in the post-Voyager era. The existence of jets and cloud bands is the puzzle that underlies all others. Discussion focuses on the particular case of Jupiter because documentation is most complete. Recent dynamical work has successfully reproduced much of the behavior of jets and spots with simple models that contain few parameters. It is argued that the gross dynamical parameters, such as density stratification and rotation rate, are the keys to their behaviors, rather than the particular specifics of radiative forcing, cloud distributions, thermodynamic transformations. Voyager data have shown that the jet systems decay with height in the region above the visible clouds. Therefore the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds. These require determination of the deep structure of the jets, of the density stratification, and of the horizontal density contrasts. The deep regions are not easily accessible, and these measurements present challenging opportunities. Indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere, and some of these issues are also discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP GIERASCH, PJ (reprint author), CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853, USA. NR 43 TC 26 Z9 27 U1 1 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 MAR 25 PY 1993 VL 98 IS E3 BP 5459 EP 5469 DI 10.1029/92JE01897 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400018 ER PT J AU SMITH, SJ CHUTJIAN, A MAWHORTER, RJ WILLIAMS, ID SHEMANSKY, DE AF SMITH, SJ CHUTJIAN, A MAWHORTER, RJ WILLIAMS, ID SHEMANSKY, DE TI EXCITATION OF POSITIVE-IONS BY LOW-ENERGY ELECTRONS - RELEVANCE TO THE IO TORUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID IMPACT EXCITATION; OSCILLATOR-STRENGTHS; COLLISION STRENGTHS; PLASMA TORUS; CROSS-SECTIONS; O-III; TRANSITION; OXYGEN; ULTRAVIOLET; SULFUR AB The importance of measuring electron-ion excitation cross sections in singly and multiply charged positive ions is outlined, and recent results for Mg II and O II ions are given using the Jet Propulsion Laboratory's electron energy-loss merged-beams apparatus. For Mg II, collision strengths are presented for the 3s 2S --> 3p 2P(h, k) resonance transition at electron energies from threshold to approximately 9 x threshold (40 eV). Theoretical comparisons are also given with two five-state close-coupling calculations. The energy variation of the collision strength is fitted with a semiempirical analytic function which includes approximations to polarization, resonance, and exchange contributions. In O II, first spectra anywhere of electron excitation of the optically allowed 2s(2)2p3 4S(o) --> 2s2p4 4p(14.88 eV) and --> 2p(2)3s 4p (22.98 eV) transitions are presented. In addition, excitations of the two low lying, optically forbidden transitions 4S(o) --> 2P(3)2D(o) (3.33 eV) and --> 2p(3)2p(o) (5.02 eV) are detected for the first time. C1 POMONA COLL,DEPT PHYS & ASTRON,CLAREMONT,CA 91711. QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089. RP SMITH, SJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 34 TC 4 Z9 4 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 MAR 25 PY 1993 VL 98 IS E3 BP 5499 EP 5504 DI 10.1029/92JE02807 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400021 ER PT J AU DELLORUSSO, N KHANNA, RK MOORE, MH AF DELLORUSSO, N KHANNA, RK MOORE, MH TI IDENTIFICATION AND YIELD OF CARBONIC-ACID AND FORMALDEHYDE IN IRRADIATED ICES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID H2O+CO2 AB Carbonic acid ((OH)2CO) was tentatively identified in the infrared spectrum of a proton irradiated CO2 + H2O ice mixture [Moore and Khanna, 1991]. In this report we present additional evidence for a more definitive identification of (OH)2CO with (1) the infrared spectrum of a residue obtained by proton irradiation Of CO2 + D2O ice mixture, and (2) the infrared spectra of solid phases of formaldehyde (H2CO), acetone [(CH3)2CO], and dimethyl carbonate [(OCH3)2CO], which are structurally similar to (OH)2CO. Infrared characteristics (peak frequencies and complex refractive indices of the compounds in point 2) are also reported. In particular, the integrated absorption coefficients for the C=O band for the compounds in point 2 do not vary by more than 20%. Based on these values, we estimate the yields of H2CO and (OH)2CO by proton irradiation of ice mixtures. Both H2CO and (OH)2CO are possible irradiation products of cometary and planetary ices. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP DELLORUSSO, N (reprint author), UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLL PK,MD 20742, USA. NR 18 TC 50 Z9 50 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-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1993 VL 98 IS E3 BP 5505 EP 5510 DI 10.1029/92JE02325 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400022 ER PT J AU BAINES, KH WEST, RA GIVER, LP MORENO, F AF BAINES, KH WEST, RA GIVER, LP MORENO, F TI QUASI-RANDOM NARROW-BAND MODEL FITS TO NEAR-INFRARED LOW-TEMPERATURE LABORATORY METHANE SPECTRA AND DERIVED EXPONENTIAL SUM ABSORPTION-COEFFICIENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID ATMOSPHERES AB Near-infrared 10-cm-1 resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112 K, 188 K, and 295 K), and 20 pressures from 0.000 1 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 mum. Root-mean-square deviations between the laboratory and the exponential-sum synthetic transmissions are reported for the best fitting 50 wavelengths. Deviations relevant to broadband, 1% spectral resolution observations such as planned to be acquired by Galileo/Near Infrared Mapping Spectrometer (NIMS) and Cassini/Visual and Infrared Mapping Spectrometer are also presented. The validity of exponential-sum coefficients derived from broadband (10 cm - 1) transmission data is demonstrated via direct comparison with line-by-line calculations. The complete atlas of coefficients is available from the Planetary Data System-Planetary Atmospheres Discipline Node. C1 NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. INST ASTROFIS ANDALUCIA,GRANADA,SPAIN. RP BAINES, KH (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 31 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-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1993 VL 98 IS E3 BP 5517 EP 5529 DI 10.1029/92JE02808 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400024 ER PT J AU NAVA, DF PAYNE, WA MARSTON, G STIEF, LJ AF NAVA, DF PAYNE, WA MARSTON, G STIEF, LJ TI THE REACTION OF ATOMIC-HYDROGEN WITH GERMANE - TEMPERATURE-DEPENDENCE OF THE RATE-CONSTANT AND IMPLICATIONS FOR GERMANE PHOTOCHEMISTRY IN THE ATMOSPHERES OF JUPITER AND SATURN SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID ABSOLUTE RATE-CONSTANT; VACUUM ULTRAVIOLET; CROSS-SECTIONS; GEH4; PH3; PHOTOABSORPTION; PARAMETERS; SILANES; CH3D AB Germane (GeH4) has been suggested to be a chemical tracer of atmospheric dynamics on Jupiter and Saturn. The observed abundance of germanium as GeH4 in the atmosphere of Saturn is dramatically low compared to the predicted GeH4 abundance. In order to provide data to help determine the major chemical form in which germanium exists in these planetary atmospheres, studies of the formation and loss processes for GeH4 are required. One of the important reactions to consider is that of hydrogen atom reaction with germane; H + GeH4. Two previous measurements of the rate constant for this reaction, made only at 298 K, yielded values differing by a factor of 200. We have under-taken a study to determine the absolute rate constant for this reaction for the first time as a function of temperature and pressure. The method employed to measure the rate of this reaction is that of flash photolysis of dilute mixtures of GeH4 in argon, combined with time-resolved detection of H atoms via Lyman a resonance fluorescence. Results of this study show the reaction to be moderately rapid, independent of total pressure, but possessing a positive temperature dependence. Rate constant data over the temperature range 2 1 0 less-than-or-equal-to T less-than-or-equal-to 450 K yield the Arrhenius expression k1 = (1.94 +/- 0.39) x 10(-10) exp [(- 11 30 +/- 50)/T] cm 3 s - 1. Implications for modeling the germane photochemistry in the atmospheres of Jupiter and Saturn derived from the present temperature dependent kinetic study are (1) low-temperature reaction rate data relevant for these atmospheric conditions are provided, and (2) limits may be placed on the role of GeH4 production and loss processes in the modeler's efforts to elucidate the respective chemical forms and abundances in which the total germanium exists in the atmospheric systems of Jupiter and Saturn. RP NAVA, DF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,ASTROCHEM BRANCH,GREENBELT,MD 20771, USA. RI Marston, George/J-9223-2012; Nava, David/E-4372-2012; Marston, George/B-3116-2015 OI Marston, George/0000-0002-0050-5928; Marston, George/0000-0002-0050-5928 NR 30 TC 11 Z9 11 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 MAR 25 PY 1993 VL 98 IS E3 BP 5531 EP 5537 DI 10.1029/92JE02806 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400025 ER PT J AU SPILKER, TR AF SPILKER, TR TI NEW LABORATORY MEASUREMENTS ON AMMONIAS INVERSION SPECTRUM, WITH IMPLICATIONS FOR PLANETARY-ATMOSPHERES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 3RD INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 3RD ICLRPA ) CY NOV 03, 1991 CL PALO ALTO, CA SP NASA, AMES RES CTR, NASA, GODDARD SPACE FLIGHT CTR, NASA, HEADQUARTERS, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA ID RADIO OCCULTATION MEASUREMENTS; NEPTUNE; NH3; ABSORPTION; VOYAGER-2; JUPITER; OPACITY; URANUS AB Microwave spectral measurements have been performed on pure room-temperature gaseous ammonia at frequencies from 1.75 to 18 GHz (1.7-17 cm), at 50-, 100-, and 300-torr pressures. These measurements are part of a laboratory program to measure the microwave absorption spectrum of ammonia, under conditions applicable to giant planet atmospheres, now in progress at the Jet Propulsion Laboratory. The pure ammonia data reported here agree well with previous data by Bleaney and Loubser (1950) at 100 and 300 torrs, and with predictions of the absorptivity formalism published by Berge and Gulkis. Success with pure ammonia but failure with mixtures of ammonia in hydrogen and helium (Spilker, 1990) indicates that the Berge and Gulkis formalism does not correctly handle foreign-gas effects on ammonia inversion lines. This may require modifying conclusions of radio astronomical and radio occultation studies that used this formalism. Notably, a suggested depletion of ammonia and superabundance of hydrogen sulfide may have been exaggerated as a result of inaccuracies in the Berge and Gulkis formalism. RP SPILKER, TR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 9 Z9 9 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 MAR 25 PY 1993 VL 98 IS E3 BP 5539 EP 5548 DI 10.1029/92JE02354 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW894 UT WOS:A1993KW89400026 ER PT J AU MARDER, SR PERRY, JW TIEMANN, BG GORMAN, CB GILMOUR, S BIDDLE, SL BOURHILL, G AF MARDER, SR PERRY, JW TIEMANN, BG GORMAN, CB GILMOUR, S BIDDLE, SL BOURHILL, G TI DIRECT OBSERVATION OF REDUCED BOND LENGTH ALTERNATION IN DONOR-ACCEPTOR POLYENES SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Note ID CRYSTAL-STRUCTURE; RAMAN-SCATTERING; DYES; POLYACETYLENE; MODEL C1 CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. RP MARDER, SR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Gorman, Christopher/A-3463-2008; Perry, Joseph/B-7191-2011 OI Gorman, Christopher/0000-0001-7367-2965; Perry, Joseph/0000-0003-1101-7337 NR 27 TC 182 Z9 182 U1 1 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD MAR 24 PY 1993 VL 115 IS 6 BP 2524 EP 2526 DI 10.1021/ja00059a067 PG 3 WC Chemistry, Multidisciplinary SC Chemistry GA KU902 UT WOS:A1993KU90200067 ER PT J AU ALTEROVITZ, SA SIEG, RM PAMULAPATI, J BHATTACHARYA, PK AF ALTEROVITZ, SA SIEG, RM PAMULAPATI, J BHATTACHARYA, PK TI ELLIPSOMETRIC CHARACTERIZATION OF IN0.52AL0.48AS AND OF MODULATION DOPED FIELD-EFFECT TRANSISTOR STRUCTURES ON INP SUBSTRATES SO APPLIED PHYSICS LETTERS LA English DT Article ID OPTICAL-PROPERTIES; SPECTROSCOPIC ELLIPSOMETRY; VARIABLE ANGLE AB The dielectric function of a thick layer of In0.52Al0.48As lattice matched to InP was measured by variable angle spectroscopic ellipsometry in the range 1.9-4.1 eV. The In0.52Al0.48As was protected from oxidation using a thin In0.53Ga0.47As cap that was mathematically removed for the dielectric function estimate. The In0.52Al0.48As dielectric function was then verified by ellipsometric measurements of other In0.53Ga0.47As/In0.52Al0.48As structures, including modulation doped field effect transistors (MODFET), and is shown to provide accurate structure layer thicknesses. C1 CLEVELAND STATE UNIV,DEPT EE,CLEVELAND,OH 44115. UNIV MICHIGAN,ANN ARBOR,MI 48109. RP ALTEROVITZ, SA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 22 PY 1993 VL 62 IS 12 BP 1411 EP 1413 DI 10.1063/1.108695 PG 3 WC Physics, Applied SC Physics GA KT419 UT WOS:A1993KT41900035 ER PT J AU DRAKE, SA SIMON, T BROWN, A AF DRAKE, SA SIMON, T BROWN, A TI DETECTION OF RADIO-CONTINUUM EMISSION FROM PROCYON SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIATION MECHANISMS, MISCELLANEOUS; RADIO CONTINUUM, STARS; STARS, INDIVIDUAL (ALPHA CANIS MINORIS) ID MASS-LOSS; MICROWAVE EMISSION; DWARF STARS; CORONAE; FLARE; SPECTRUM AB We have detected the F5 IV-V star Procyon as a weak and variable 3.6 cm radio continuum source using the Very Large Array.2 The inferred radio luminosity is 11.7 less-than-or-equal-to log L(nu) less-than-or-equal-to 12.2 which is similar to, though somewhat higher than, the X-band luminosity of the active and flaring Sun. The 33 muJy flux density level at which we detected Procyon on four of five occasions is close to the 36 muJy radio flux density expected from a model in which the radio emission consists of two components: optically thick '' stellar disk '' emission with a 3.6 cm brightness temperature of 2 x 10(4) K that is 50% larger than the solar value, and optically thin coronal emission with an emission measure the same as that indicated by Einstein and EXOSAT X-ray flux measurements in 1981 and 1983. The maximum mass-loss rate of a warm (T(e) approximately 10(4)-10(5) K) stellar wind is constrained by our radio observations to be less than 2 x 10(-11) M. yr-1. An elevated flux density of 115 muJy observed on a single occasion may have been associated with a radio outburst or flare, or, alternatively, been caused by the rotation onto the visible hemisphere of a large, intense active region. In either case, this observation provides circumstantial evidence for the existence of highly localized magnetic fields on the surface of Procyon. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. NATL INST STAND & TECHNOL,BOULDER,CO 80309. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. RP DRAKE, SA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS SCI ARCHIVE RES CTR,CODE 668,GREENBELT,MD 20771, USA. NR 31 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 MAR 20 PY 1993 VL 406 IS 1 BP 247 EP 251 DI 10.1086/172436 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KT453 UT WOS:A1993KT45300025 ER PT J AU JORDAN, SD THOMPSON, WT THOMAS, RJ NEUPERT, WM AF JORDAN, SD THOMPSON, WT THOMAS, RJ NEUPERT, WM TI SOLAR CORONAL OBSERVATIONS AND FORMATION OF THE HE-II 304-ANGSTROM LINE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; SUN, CORONA; SUN, UV RADIATION ID RADIATION AB Although a large body of recent work supports the formation of the He II 304 angstrom resonance line (IS S-2(1/2)-2p P-2(1/2,3/2))0 by collisional excitation in the quiet Sun, the formation mechanism is less clear in strong coronal active regions and flares. The 1989 May 5 flight of the Goddard Solar Extreme Ultraviolet Rocket Telescope and Spectrograph (SERTS-3) provided a data set that is well suited to addressing this question. This paper develops a method of assessment of the line formation mechanism that is based on simple non-LTE theory and is applied to these data. The results support the conclusion of other authors that the 304 angstrom line is formed by collisional excitation in the quiet Sun, but that photoionization-recombination (p-r) may play a significant role in coronal active regions, and that p-r is important, and may even be predominant, in many flares. C1 APPL RES CORP,LANDOVER,MD 20784. RP JORDAN, SD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 680,GREENBELT,MD 20771, USA. RI Thompson, William/D-7376-2012 NR 19 TC 25 Z9 25 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 MAR 20 PY 1993 VL 406 IS 1 BP 346 EP 349 DI 10.1086/172444 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KT453 UT WOS:A1993KT45300033 ER PT J AU KASHLINSKY, A AF KASHLINSKY, A TI HIGH-Z OBJECTS AND COLD DARK MATTER COSMOGONIES - CONSTRAINTS ON THE PRIMORDIAL POWER SPECTRUM ON SMALL SCALES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, THEORY; GALAXIES, FORMATION; LARGE-SCALE STRUCTURE OF UNIVERSE ID RADIO GALAXY; REDSHIFT; UNIVERSE; QUASARS; FIELDS AB Modified cold dark matter (CDM) models were recently suggested to account for large-scale optical data, which fix the power spectrum on large scales, and the COBE results, which would then fix the bias parameter, b. We point out that all such models have deficit of small-scale power where density fluctuations are presently nonlinear, and should then lead to late epochs of collapse of scales 10(9)-10(10) M. < M < (1-5) x 10(14) M.. We compute the probabilities and comoving space densities of various scale objects at high redshifts according to the CDM models and compare these with observations of high-z QSOs, high-z galaxies and the protocluster-size object found recently by Uson et al. at z = 3.4. We show that the modified CDM models are inconsistent with the observational data on these objects. We thus suggest that in order to account for the high-z objects, as well as the large-scale and COBE data, one needs a power spectrum with more power on small scales than CDM models allow and an open universe. RP KASHLINSKY, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. NR 38 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 MAR 20 PY 1993 VL 406 IS 1 BP L1 EP & DI 10.1086/186772 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KT454 UT WOS:A1993KT45400001 ER PT J AU BLIVEN, LF GIOVANANGELI, JP AF BLIVEN, LF GIOVANANGELI, JP TI AN EXPERIMENTAL-STUDY OF MICROWAVE-SCATTERING FROM RAIN-ROUGHENED AND WIND-ROUGHENED SEAS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID WATER-WAVES; SURFACE; OCEAN; STRESS; MODEL AB This paper investigates radar cross-section (RCS) characteristics of rain- and wind-roughened sea-surfaces. We conducted experiments in laboratory wind-wave tanks using artificial rain. The study includes light rain rates, light wind speeds, and combinations of these. A 36 Ghz scatterometer was operated at 30-degrees incidence angle and with vertical polarization. RCS data were obtained not only with the scatterometer pointing up-wind but also as a function of azimuthal angle. We use a scatterometer rain and wind model SRWM-1, which relates the total average RCS in storms to the sum of the average RCS due to rain plus the average RCS due to wind. Implications of the study for operational monitoring of wind in rainy oceanic areas by satellite-borne instruments is discussed. C1 INST MECAN STAT TURBULENCE, F-13003 MARSEILLE, FRANCE. RP NASA, GODDARD SPACE FLIGHT CTR, WALLOPS ISL, VA 23337 USA. RI bliven, francis/E-1450-2012 NR 42 TC 29 Z9 29 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND SN 0143-1161 EI 1366-5901 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAR 20 PY 1993 VL 14 IS 5 BP 855 EP 869 PG 15 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LA885 UT WOS:A1993LA88500004 ER PT J AU RIND, D CHIOU, EW CHU, W OLTMANS, S LERNER, J LARSEN, J MCCORMICK, MP MCMASTER, L AF RIND, D CHIOU, EW CHU, W OLTMANS, S LERNER, J LARSEN, J MCCORMICK, MP MCMASTER, L TI OVERVIEW OF THE STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II WATER-VAPOR OBSERVATIONS - METHOD, VALIDATION, AND DATA CHARACTERISTICS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SATELLITE DATA; H2O; O-3; CH4; DEHYDRATION; NIMBUS-7; CLIMATE; MODELS; OZONE; LIMS AB Water vapor observations obtained from the Stratospheric Aerosol and Gas Experiment II (SAGE II) solar occultation instrument for the troposphere and stratosphere are presented and compared with correlative in situ measurement techniques and other satellite data. The SAGE II instrument produces water vapor values from cloud top to approximately 1 mbar, except in regions of high aerosol content such as occurs in the low to middle stratosphere after volcanic eruptions. Details of the analysis procedure, instrumental errors, and data characteristics are discussed. Various features of the data set for the first 5 years after launch (1985-1989) are identified. These include an increase in middle and upper tropospheric water vapor during northern hemisphere summer and autumn, thus at times of warmest sea surface temperature; minimum water vapor values of 2.5-3 ppmv in the tropical lower stratosphere, with lower values during northern hemisphere winter and spring; slowly increasing water vapor values with altitude in the stratosphere, reaching 5-6 ppmv or greater near the stratopause; extratropical values with minimum profile amounts occurring above the conventionally defined tropopause; and higher extratropical than tropical water vapor values throughout the stratosphere except in locations of possible polar stratospheric clouds. SAGE II data will be useful for studying individual water vapor profiles, tropospheric response to climate perturbations, tropospheric-stratospheric exchange (due to its inherent high vertical resolution), and stratospheric transports. It should also aid in the preparation, for the first time on a global scale, of climatologies of the stratosphere and the upper level cloud-free troposphere, for use in radiative, dynamical, and chemical studies. C1 STX CORP,NEW YORK,NY 10025. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. STX CORP,HAMPTON,VA. NOAA,CLIMATE MODELLING & DIAGNOST LAB,BOULDER,CO 80303. RP RIND, D (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 55 TC 78 Z9 79 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 MAR 20 PY 1993 VL 98 IS D3 BP 4835 EP 4856 DI 10.1029/92JD01174 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900001 ER PT J AU CHU, WP CHIOU, EW LARSEN, JC THOMASON, LW RIND, D BUGLIA, JJ OLTMANS, S MCCORMICK, MP MCMASTER, LM AF CHU, WP CHIOU, EW LARSEN, JC THOMASON, LW RIND, D BUGLIA, JJ OLTMANS, S MCCORMICK, MP MCMASTER, LM TI ALGORITHMS AND SENSITIVITY ANALYSES FOR STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II WATER-VAPOR RETRIEVAL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION; PARAMETERS; INVERSION; NIMBUS-7; OZONE AB This paper provides a detailed description of the current operational inversion algorithm for the retrieval of water vapor vertical profiles from the Stratospheric Aerosol and Gas Experiment II (SAGE II) occultation data at the 0.94-mum wavelength channel. This algorithm is different from the algorithm used for the retrieval of the other species such as aerosol, ozone, and nitrogen dioxide because of the nonlinear relationship between the concentration versus the broad band absorption characteristics of water vapor. Included in the discussion of the retrieval algorithm are problems related to the accuracy of the computational scheme, accuracy of the removal of other interfering species, and the expected uncertainty of the retrieved profile. A comparative analysis on the computational schemes used for the calculation of the water vapor transmission at the 0.94-mum wavelength region is presented. Analyses are also presented on the sensitivity of the retrievals to interferences from the other species which contribute to the total signature as observed at the 0.94-mum wavelength channel on SAGE II instrument. Error analyses of the SAGE II water vapor retrieval will be shown, indicating that good quality water vapor data are being produced by the SAGE II measurements. C1 STX CORP,HAMPTON,VA. GODDARD SPACE FLIGHT CTR,GODDARD INST SPACE SCI,NEW YORK,NY 10025. NASA,LANGLEY RES CTR,DIV FLIGHT ELECTR,HAMPTON,VA 23665. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. RP CHU, WP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. OI Thomason, Larry/0000-0002-1902-0840 NR 27 TC 47 Z9 47 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 MAR 20 PY 1993 VL 98 IS D3 BP 4857 EP 4866 DI 10.1029/92JD01628 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900002 ER PT J AU MCCORMICK, MP CHIOU, EW MCMASTER, LR CHU, WP LARSEN, JC RIND, D OLTMANS, S AF MCCORMICK, MP CHIOU, EW MCMASTER, LR CHU, WP LARSEN, JC RIND, D OLTMANS, S TI ANNUAL VARIATIONS OF WATER-VAPOR IN THE STRATOSPHERE AND UPPER TROPOSPHERE OBSERVED BY THE STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID H2O; DISTRIBUTIONS; LIMS; O-3; CH4; HDO AB This paper presents a description of the annual variations of water vapor in the stratosphere and the upper troposphere derived from observations of the Stratospheric Aerosol and Gas Experiment II (SAGE II). The altitude-time cross sections exhibit annually repeatable patterns in both hemispheres. The appearance of a yearly minimum in water vapor in both hemispheres at approximately the same time supports the idea of a common source(s) for stratospheric dry air. Annual patterns observed at northern mid-latitudes, like the appearance of a hygropause in winter and the weakening and upward shifting of the hygropause from January to May, agree with in situ balloon observations previously obtained over Boulder and Washington, D. C. An increase in water vapor with altitude in the tropics is consistent with methane oxidation in the upper stratosphere to lower mesosphere as a source for water vapor. A poleward gradient is also shown as expected based on a Lagrangian mean circulation. A linear regression analysis using SAGE II data from January 1986 to December 1988 shows that little annual variation occurs in the middle and upper stratosphere with the region of large annual variability near the tropopause. The semi-annual variability is relatively marked at altitudes of 24 and 40 km in the tropics. C1 HUGHES STX CORP,HAMPTON,VA. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. NASA,LANGLEY RES CTR,DIV FLIGHT ELECTR,HAMPTON,VA 23665. RP MCCORMICK, MP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 30 TC 58 Z9 58 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 MAR 20 PY 1993 VL 98 IS D3 BP 4867 EP 4874 DI 10.1029/92JD02218 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900003 ER PT J AU CHIOU, EW MCCORMICK, MP MCMASTER, LR CHU, WP LARSEN, JC RIND, D OLTMANS, S AF CHIOU, EW MCCORMICK, MP MCMASTER, LR CHU, WP LARSEN, JC RIND, D OLTMANS, S TI INTERCOMPARISON OF STRATOSPHERIC WATER-VAPOR OBSERVED BY SATELLITE EXPERIMENTS - STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II VERSUS LIMB INFRARED MONITOR OF THE STRATOSPHERE AND ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; MESOSPHERE; NIMBUS-7; MODEL AB This paper presents a comparison of the stratospheric water vapor measurements made by the satellite-borne sensors the Stratospheric Aerosol and Gas Experiment II (SAGE II), the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS), and the Spacelab 3 Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. LIMS obtained data for 7 months between November 1978 and May 1979; ATMOS was carried on Shuttle and observed eight profiles from April 30 to May 6, 1985 at approximately 30-degrees-N and 50-degrees-S; and, SAGE II continues to make measurements since its launch in October 1984. For both 30-degrees-N and 50-degrees-S in May, the comparisons between SAGE II and ATMOS show agreement within the estimated combined uncertainty of the two experiments. Several important features identified by LIMS observations have been confirmed by SAGE II: a well-developed hygropause in the lower stratosphere at low- to mid-latitudes, a poleward latitudinal gradient, increasing water vapor mixing ratios with altitude in the tropics, and the transport of dry lower stratospheric water vapor upward and southward in May, and upward and northward in November. A detailed comparative study also indicates that the two previously suggested corrections for LIMS, a correction in tropical lower stratosphere due to a positive temperature bias and the correction above 28 km based on improved emissivities will bring LIMS measurements much closer to those of SAGE II. The only significant difference occurs at high southern latitudes in May below 18 km, where LIMS measurements are 2-3 ppmv greater. It should be noted that LIMS observations are from 16 to 50 km, ATMOS from 14 to 86 km, and SAGE II from mid-troposphere to 40 km. With multiyear coverage, SAGE II observations should be useful for studying tropospheric-stratospheric exchange, for stratospheric transport, and for preparing water vapor climatologies for the stratosphere and the upper troposphere. C1 HUGHES STX CORP,HAMPTON,VA. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,DIV FLIGHT ELECTR,HAMPTON,VA 23665. NR 32 TC 19 Z9 19 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 MAR 20 PY 1993 VL 98 IS D3 BP 4875 EP 4887 DI 10.1029/92JD01629 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900004 ER PT J AU PRUVOST, P OVARLEZ, J LENOBLE, J CHU, WP AF PRUVOST, P OVARLEZ, J LENOBLE, J CHU, WP TI COMPARISON OF STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II AND BALLOON-BORNE STRATOSPHERIC WATER-VAPOR MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NIMBUS-7 AB The Stratospheric Aerosol and Gas Experiment II has one channel at 940 nm related to water vapor. Two inversion procedures were developed independently in order to obtain the water vapor profile: the Chahine method by the Langley Research Center, and the Mill method by the Laboratoire d'Optique Atmospherique. Comparisons were made between these two algorithms and some results are presented at mid-latitudes (approximately 45-degrees-N) and tropical latitudes (12-degrees-S-25-degrees-S). They are compared with in situ frost point hygrometer data provided by balloon experiments from the Laboratoire de Meteorologie Dynamique. At +/-0.5 ppmv, agreement between the inversion results and the experimental results was obtained in the altitude range from 18-19 to 26-27 km. Below 18-19 km and above 26-27 km the error is larger (sometimes 1 ppmv and more). C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. ECOLE POLYTECH,CNRS,METEOROL DYNAM LAB,F-91128 PALAISEAU,FRANCE. RP PRUVOST, P (reprint author), UNIV LILLE 1,OPT ATMOSPHER LAB,CNRS,UA 713,F-59655 VILLENEUVE DASCQ,FRANCE. NR 17 TC 8 Z9 8 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 MAR 20 PY 1993 VL 98 IS D3 BP 4889 EP 4896 DI 10.1029/92JD02337 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900005 ER PT J AU LARSEN, JC CHIOU, EW CHU, WP MCCORMICK, MP MCMASTER, LR OLTMANS, S RIND, D AF LARSEN, JC CHIOU, EW CHU, WP MCCORMICK, MP MCMASTER, LR OLTMANS, S RIND, D TI A COMPARISON OF THE STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II TROPOSPHERIC WATER-VAPOR TO RADIOSONDE MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID VALIDATION; SATELLITE; CO AB Upper tropospheric Stratospheric Aerosol and Gas Experiment II (SAGE II) water vapor observations are compared to correlative radiosonde observations and radiosonde based climatologies. The SAGE II 1987 monthly zonal mean water vapor climatology is compared to both the Global Atmospheric Circulation Statistics (1963-1973) climatology and to the 1987 radiosonde climatology. The clear sky SAGE II climatology is found to be approximately half the level of both the clear/cloudy sky radiosonde climatologies. To determine whether this is realistic for these two different climatologies or includes additional observational and instrumental biases, we took the 1987 radiosonde data set and identified approximately 800 correlative profile pairs. The observational biases inherent to SAGE II and the radiosondes produce a set of profile pairs characteristic of clear sky, land conditions. A critical review of the radiosonde measurement capability was carried out to establish the operating range and accuracy in the upper troposphere. We show that even with tight coincidence criterion, the quality of the profile pair comparisons varies considerably because of strong water vapor variability occurring on small time and space scales. Annual zonal means calculated from the set of profile pairs again finds SAGE II significantly drier in many latitude bands. Resolving the radiosonde data base by hygrometer type shows this to be true for all hygrometers except for the thin film capacitive type (Vaisala Humicap). For this hygrometer, between 4.5 and 6.5 km SAGE II is drier by approximately 25.%, and from 8.5 to 11.5 km they are nearly equivalent when global annual means are compared. The good agreement with the Vaisala Humicap, currently the most accurate and responsive hygrometer in operational use, suggests existing radiosonde climatologies contain a significant moist bias in the upper troposphere. C1 HUGHES STX CORP,HAMPTON,VA. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NASA,CLIMATE MODELING & DIAGNOST LAB,NEW YORK,NY 10025. NOAA,CLIMATE MODELING & DIAGNOST LAB,BOULDER,CO 80303. NR 31 TC 22 Z9 22 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 MAR 20 PY 1993 VL 98 IS D3 BP 4897 EP 4917 DI 10.1029/92JD01630 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900006 ER PT J AU CROSSON, WL SMITH, EA COOPER, HJ AF CROSSON, WL SMITH, EA COOPER, HJ TI ESTIMATION OF SURFACE HEAT AND MOISTURE FLUXES OVER A PRAIRIE GRASSLAND .4. IMPACT OF SATELLITE REMOTE-SENSING OF SLOW CANOPY VARIABLES ON PERFORMANCE OF A HYBRID BIOSPHERE MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; SOIL-MOISTURE; MESOSCALE CIRCULATIONS; VEGETATION; EVAPOTRANSPIRATION; SIMULATION; ANOMALIES; RAINFALL; CLIMATE AB Herein, we present the results of a series of numerical experiments using the Ex-BATS biosphere model, which is an adaptation of Dickinson's biosphere-atmosphere transfer scheme (BATS). These simulations are used to assess how the model performs when remotely sensed data are used to estimate three key canopy variables. These canopy variables, which effectively represent the slowly changing boundary conditions of a vegetated surface, consist of the total surface albedo, leaf area index, and the nondiurnally varying component of stomatal resistance, referred to as stressed stomatal resistance. The surface albedo is retrieved from NOAA-AVHRR (advanced very high resolution radiometer) channel 1 spectral reflectance information in conjunction with a directional reflectance model which accounts for the strong diurnal variations in surface reflectance. A 4-channel vegetation index also retrieved from AVHRR measurements is used to estimate the leaf area index. A similar index derived from high-resolution SPOT visible and near-infrared information has been used to describe the spatial variations in such indices which impact the retrieval of the leaf area index. Satellite retrieval of stomatal resistance is based on split-window skin temperatures from AVHRR channels 4 and 5 from the afternoon overpass (approximately 1630 LT). Variables derived from the hourly skin temperature observations of GOES-VISSR have also been examined with respect to retrieval of stomatal resistance. It was found that although stomatal resistance has little correlation with the diurnal amplitude of skin temperature, it is closely related to the daily maximum of skin temperature. Numerical experiments have been conducted to examine model sensitivity to each of these canopy variables. Results indicate that Ex-BATS is not sensitive to small variations of surface albedo or leaf area index within the range of estimation uncertainty. The rms measurement-model flux differences in every numerical trial were within 6 W m-2 of the rms differences obtained for the simulations performed using measured albedo and leaf area index. Measured stomatal resistance values were obtained using an inversion form of the model. The resulting stomatal resistances were used to perform a control experiment simulating an ideal satellite retrieval scenario involving one observation per day. The control experiment resulted in improvements of approximately 20 W m-2 in the rms flux differences over the model using a purely hypothetical formulation for stomatal resistance. Simulations using the remotely retrieved stomatal resistances produced significantly reduced rms differences for latent and sensible heat fluxes over the model using the hypothetical formulation. Based on a 55-day composite involving all days from the four FIFE intensive field campaigns, the sensible and latent heat flux improvements are approximately 25 and 20%, respectively (11 and 8 W m -2) . The satellite retrievals are only 20 and 30% less accurate (7 and 10 W m-2) than the idealized results of the control experiment. C1 FLORIDA STATE UNIV,SUPERCOMP COMPUTAT RES INST,TALLAHASSEE,FL 32306. FLORIDA STATE UNIV,DEPT METEOROL,TALLAHASSEE,FL 32306. RP CROSSON, WL (reprint author), UNIV SPACE RES ASSOC,MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 35 TC 15 Z9 15 U1 1 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 MAR 20 PY 1993 VL 98 IS D3 BP 4979 EP 4999 DI 10.1029/92JD01917 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KU069 UT WOS:A1993KU06900010 ER PT J AU SIMONS, RN LEE, RQ PERL, TD SILVESTRO, J AF SIMONS, RN LEE, RQ PERL, TD SILVESTRO, J TI EFFECT OF A DIELECTRIC OVERLAY ON A LINEARLY TAPERED SLOT ANTENNA EXCITED BY A COPLANAR WAVE-GUIDE SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE SLOT ANTENNA; COPLANAR WAVE-GUIDE; ANTENNA FEED AB A linearly tapered slot antenna (LTSA) with a dielectric overlay was experimentally investigated. The presence of dielectric overlay alters the guide wavelength of the LTSA, and thus the radiation characteristics of the antenna. Results indicate that dielectric overlay could be used to reduce the physical length and to improve the radiation characteristics of the LTSA. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 0 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 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD MAR 20 PY 1993 VL 6 IS 4 BP 225 EP 228 DI 10.1002/mop.4650060404 PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA KM993 UT WOS:A1993KM99300003 ER PT J AU OLIVER, B AF OLIVER, B TI OPTICS AND ALIENS SO NEW SCIENTIST LA English DT Letter RP OLIVER, B (reprint author), NASA,AMES RES CTR,SETI OFF,MOFFETT FIELD,CA 94035, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU NEW SCIENTIST PUBL EXPEDITING INC PI ELMONT PA 200 MEACHAM AVE, ELMONT, NY 11003 SN 0262-4079 J9 NEW SCI JI New Sci. PD MAR 20 PY 1993 VL 137 IS 1865 BP 50 EP 50 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KU228 UT WOS:A1993KU22800040 ER PT J AU JACKMAN, CH NIELSEN, JE ALLEN, DJ CERNIGLIA, MC MCPETERS, RD DOUGLASS, AR ROOD, RB AF JACKMAN, CH NIELSEN, JE ALLEN, DJ CERNIGLIA, MC MCPETERS, RD DOUGLASS, AR ROOD, RB TI THE EFFECTS OF THE OCTOBER 1989 SOLAR PROTON EVENTS ON THE STRATOSPHERE AS COMPUTED USING A 3-DIMENSIONAL MODEL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; OZONE DEPLETION; NITROGEN AB Very large solar proton events (SPEs) occurred from October 19-27, 1989. These SPEs are predicted to produce short-lived increases in HO(x) and long-lived increases in NO(x) species, which both can lead to ozone destruction. December 1989 SBUV/2 measurements of upper stratospheric ozone show substantially more ozone depletion in the Northern than in the Southem Hemisphere even though the amount of HO(x) and NO(x) produce a in both hemispheres should be similar from these SPEs. Our two-dimensional (2D) model simulations predict only a modest interhemispheric difference in the ozone depletion in December caused by the October 1989 SPEs. In an attempt to better understand the interhemispheric difference in the observed ozone depletion, we have used the GSFC three-dimensional (3D) chemistry and transport model to simulate the distribution of NO(x) and ozone after the SPEs. Our 3D model computations of ozone and NO(x) behavior for two months after the October 1989 SPEs indicate differences in the constituent behavior in the two hemispheres during the October-November-December 1989 time period which are qualitatively consistent with SBUV/2 ozone observations. These differences are caused by: 1) Substantial mixing of perturbed air in the Southem Hemisphere from the polar region with unperturbed lower latitude air during the November final warning; and 2) Significant confinement of the photochemically perturbed air in the Northern Hemisphere in the winter-time polar vortex. C1 APPL RES CORP,LANDOVER,MD 20785. RP JACKMAN, CH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 916,GREENBELT,MD 20771, USA. RI Allen, Dale/F-7168-2010; Douglass, Anne/D-4655-2012; Jackman, Charles/D-4699-2012; McPeters, Richard/G-4955-2013; Rood, Richard/C-5611-2008 OI Allen, Dale/0000-0003-3305-9669; McPeters, Richard/0000-0002-8926-8462; Rood, Richard/0000-0002-2310-4262 NR 23 TC 27 Z9 27 U1 1 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 MAR 19 PY 1993 VL 20 IS 6 BP 459 EP 462 DI 10.1029/93GL00205 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800012 ER PT J AU PRICE, C RIND, D AF PRICE, C RIND, D TI WHAT DETERMINES THE CLOUD-TO-GROUND LIGHTNING FRACTION IN THUNDERSTORMS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID THUNDERCLOUDS; RATIO AB The ratio of intracloud lightning (IC) to cloud-to-ground lightning (CG) in thunderstorms is observed to vary with latitude. The reason frequently given for this behaviour is that the height of die freezing level, and hence the negative charge center in thunderstorms, varies with latitude, resulting in higher ratios in the tropics compared with those in midlatitudes. This study shows that this hypothesis could well be incorrect. Analysis of cloud and lightning data indicates that the IC/CG ratio is linked to the thickness of the cold cloud region in thunderstorms (0-degrees-C to cloud top), rather than to the freezing level height. C1 COLUMBIA UNIV,NEW YORK,NY 10027. RP PRICE, C (reprint author), NASA,GISS,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 17 TC 103 Z9 104 U1 0 U2 5 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 MAR 19 PY 1993 VL 20 IS 6 BP 463 EP 466 DI 10.1029/93GL00226 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800013 ER PT J AU TORR, MR AF TORR, MR TI THE SCIENTIFIC OBJECTIVES OF THE ATLAS-1 SHUTTLE MISSION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB During the 9-day ATLAS-1 mission (March 24 - April 2, 1992), a significant database was acquired on the temperature, pressure, and composition of the atmospheric regions between approximately 15 km and 300 km, together with measurements of the total solar irradiance and the solar spectral irradiance between 1200 angstrom and 3.2 mum. Six remote sensing atmospheric instruments covered a scope in altitude and species that has not been addressed before from a single mission. The atmospheric composition dataset should serve as an important reference for the determination of future global change in these regions. Both the solar and atmospheric instruments made observations that were coordinated with those made from other spacecraft, such as the UARS, the NOAA, and the ERB satellites. The objective of these correlative measurements was both to complement the measurements made by the other payloads and also to update the calibration of the instruments on the long-duration orbiting vehicles with recent, highly accurate calibrations. Experiments were conducted in space plasma physics. Most important of these was the generation of artificial auroras by firing a beam of energetic electrons into the atmosphere. The induced auroras were observed with a photometric imaging camera. In addition, measurements were made of the precipitation of energetic neutrals from the ring current. ATLAS-1 also carried an UV instrument to gather wide field observations of astronomical sources. A subset of these instruments is planned to fly once a year for the duration of a solar cycle. Both the ATLAS-1 mission and the ongoing series represent an important element of the Mission to Planet Earth and the Global Change Program. The papers in this special issue give a summary of the results obtained in the first 4 months following the mission. RP TORR, MR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES 51,HUNTSVILLE,AL 35812, USA. NR 1 TC 10 Z9 10 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 MAR 19 PY 1993 VL 20 IS 6 BP 487 EP 490 DI 10.1029/93GL00592 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800019 ER PT J AU BURCH, JL MENDE, SB KAWASHIMA, N ROBERTS, WT TAYLOR, WWL NEUBERT, T GIBSON, WC MARSHALL, JA SWENSON, GR AF BURCH, JL MENDE, SB KAWASHIMA, N ROBERTS, WT TAYLOR, WWL NEUBERT, T GIBSON, WC MARSHALL, JA SWENSON, GR TI ARTIFICIAL AURORAS IN THE UPPER-ATMOSPHERE .1. ELECTRON-BEAM INJECTIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Artificial electron beams from the Space Experiments with Particle Accelerators (SEPAC) on the ATLAS 1 Spacelab payload were used to stimulate auroral emissions at southem auroral latitudes. The emitted electron beams were monoenergetic at 6.25 keV and were fired in one-second pulses every fifteen seconds with currents of 1.21 A. Optical measurements of the beam were made in the vicinity of the Shuttle Orbiter by its on-board television camera and in the upper atmosphere by the Atmospheric Emissions Photometric Imager (AEPI). AEPI imaged auroral emissions in both white light and at the 427.8 nm N2+ emission line. Energy deposition calculations and the results of previous sounding-rocket experiments had suggested that emissions with scale sizes of about 130 meters would result from the artificial electron beams with the visible emissions extending from about 110 to 130 km altitudes. In the ATLAS 1 experiments the auroral imaging was performed from the Shuttle, providing a new perspective on the artificial auroras and allowing the emissions to be traced from altitudes near the 295 km Shuttle altitude down to the 110 km level along the curved magnetic field lines. C1 LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. INST SPACE & ASTRONAUT SCI,KANAGAWA 172,JAPAN. NICHOLS RES CORP,ARLINGTON,VA 22209. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP BURCH, JL (reprint author), SW RES INST,PO DRAWER 28510,SAN ANTONIO,TX 78228, USA. NR 11 TC 10 Z9 10 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 MAR 19 PY 1993 VL 20 IS 6 BP 491 EP 494 DI 10.1029/93GL00595 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800020 ER PT J AU MENDE, SB BURCH, JL SWENSON, GR AAMODT, EK GELLER, SP RAIRDEN, RL HASSLER, PL AF MENDE, SB BURCH, JL SWENSON, GR AAMODT, EK GELLER, SP RAIRDEN, RL HASSLER, PL TI ARTIFICIAL AURORAS IN THE UPPER-ATMOSPHERE .2. IMAGING RESULTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ELECTRON-BEAMS; CONJUGATE ECHOES AB On the ATLAS 1 mission (STS-45, launched March 24, 1992) two experiments, AEPI (Atmospheric Emissions Photometric Imaging) and SEPAC (Space Experiments with Particle Accelerators) performed the first experiment in a series of active experiments intended to probe the atmosphere, ionosphere and magnetosphere with electron beams. The luminous artificial aurora generated by the electron beam interaction was detected and measured by AEPI both in white light and in a narrow wavelength band at 427.8 nm (peak intensity 5 kR). Modelling calculation showed that there was a significant contribution from emissions originating near the spacecraft. The spatial intensity distribution of the observed auroral patch is consistent with emission contribution from both high and low altitude regions. An extended tail in the direction of the shuttle wake was observed in the 427.8 nm channel, consistent with a decay time associated with the dissipation of the hot electron plasma. C1 SW RES INST,SAN ANTONIO,TX 78228. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP MENDE, SB (reprint author), LOCKHEED PALO ALTO RES LABS,D91-20,B255,3251 HANOVER ST,PALO ALTO,CA 94304, USA. NR 19 TC 7 Z9 7 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 MAR 19 PY 1993 VL 20 IS 6 BP 495 EP 498 DI 10.1029/93GL00594 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800021 ER PT J AU MORGAN, MF TORR, DG TORR, MR AF MORGAN, MF TORR, DG TORR, MR TI PRELIMINARY MEASUREMENTS OF MESOSPHERIC OH X2-PI BY ISO ON ATLAS-1 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSITU MEASUREMENTS; STRATOSPHERE; OZONE; MODEL; HO2 AB Resonance fluorescence of the OH radical was observed in the mesosphere by the Imaging Spectrometric Observatory (ISO) on ATLAS 1 . A preliminary determination of the OH density profile from 70 to 80 km has been made from these observations. This marks the first measurement of ground state OH in the mesosphere since Anderson's [1971a,b] sounding rocket measurements, and the first from space. ISO imaged resonance scattered sunlight in the OH A2SIGMA - X2PI (0, 0) band during limb scans at tangent heights between 60 and 85 km, at 1.6 km spatial resolution, using an f/3.5 diffraction grating spectrometer with spectral resolution of 0.5 angstrom. OH observations were conducted throughout most of the dayside passes during the mission, covering much of the northern hemisphere to 57-degrees-N latitude. Here we report results from an observation at 39-degrees-N, local solar time 13:15, on March 30, 1992; we find OH densities on the order of 8 x 10(6) cm-3 from 70 to 80 km, decreasing rapidly above 80 km. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP MORGAN, MF (reprint author), UNIV ALABAMA,DEPT PHYS,OPT AERON LAB,OB 300,HUNTSVILLE,AL 35899, USA. RI Morgan, Frank/C-5246-2016 OI Morgan, Frank/0000-0003-3166-7732 NR 18 TC 15 Z9 15 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 MAR 19 PY 1993 VL 20 IS 6 BP 511 EP 514 DI 10.1029/92GL02628 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800025 ER PT J AU OWENS, JK TORR, DG TORR, MR CHANG, T FENNELLY, JA RICHARDS, PG MORGAN, MF BALDRIDGE, TW FELLOWS, CW DOUGANI, H SWIFT, W TEJADA, A ORME, T GERMANY, GA YUNG, S AF OWENS, JK TORR, DG TORR, MR CHANG, T FENNELLY, JA RICHARDS, PG MORGAN, MF BALDRIDGE, TW FELLOWS, CW DOUGANI, H SWIFT, W TEJADA, A ORME, T GERMANY, GA YUNG, S TI MESOSPHERIC NIGHTGLOW SPECTRAL SURVEY TAKEN BY THE ISO SPECTRAL SPATIAL IMAGER ON ATLAS-1 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HERZBERG-I SYSTEM; TERRESTRIAL NIGHTGLOW; ALTITUDE DEPENDENCE; EMISSION AB This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v' = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of +/-10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v' = 5 level is not observed although there is a suggestion of depletion in v' = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen. C1 SCI APPLICAT SUPPORT SERV INC,BOEING COMP SUPPORT SERV,HUNTSVILLE,AL 35824. UNIV ALABAMA,DEPT PHYS,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. UNIV ALABAMA,DEPT COMP SCI,HUNTSVILLE,AL 35899. SCI & ENGN ASSOCIATES INC,HUNTSVILLE,AL 35816. RP OWENS, JK (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 9 TC 10 Z9 10 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 MAR 19 PY 1993 VL 20 IS 6 BP 515 EP 518 DI 10.1029/93GL00616 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800026 ER PT J AU TORR, DG TORR, MR RICHARDS, PG AF TORR, DG TORR, MR RICHARDS, PG TI THERMOSPHERIC AIRGLOW EMISSIONS - A COMPARISON OF MEASUREMENTS FROM ATLAS-1 AND THEORY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL AB The Imaging Spectrometric Observatory flown on the ATLAS-1 shuttle mission was designed to measure the dayglow and nightglow emissions of the thermosphere and mesosphere. During this mission the ISO obtained the first detailed spectral atlas of the dayglow over a broad wavelength range (600 angstrom to 8400 angstrom). Spectral emissions over this wavelength range were obtained as a function of altitude, allowing comparisons to be made with current thermospheric photochemistry models. Much of the present understanding of thermospheric photochemistry is based on the work done using die multi-instrument complement onboard the Atmosphere Explorer satellites flown in the 1970's. It is therefore of considerable interest to answer the question of how well that basic photochemistry predicts a large number of different airglow emissions measured almost 20 years later. In this paper we run our comprehensive thermospheric model for conditions appropriate to the time of the ATLAS-1 mission and compare the slant path intensities thus computed (as a function of altitude, latitude, longitude, and local time) with a dozen major emissions measured in the course of a particular observing sequence. Bearing in mind that the model has been run in a predictive mode, and that no attempt has yet been made to iterate the fit to the data, it is found that the agreement is reasonably good, indicating that the major processes controlling the thermospheric airglow are relatively well understood. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP TORR, DG (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 5 TC 18 Z9 18 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 MAR 19 PY 1993 VL 20 IS 6 BP 519 EP 522 DI 10.1029/93GL00614 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800027 ER PT J AU TORR, MR TORR, DG CHANG, T RICHARDS, PG BALDRIDGE, TW OWENS, JK DOUGANI, H FELLOWS, C SWIFT, W YUNG, S HLADKY, J AF TORR, MR TORR, DG CHANG, T RICHARDS, PG BALDRIDGE, TW OWENS, JK DOUGANI, H FELLOWS, C SWIFT, W YUNG, S HLADKY, J TI THE 1ST NEGATIVE BANDS OF N2+ IN THE DAYGLOW FROM THE ATLAS-1 SHUTTLE MISSION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODEL AB During November-December 1983 the first spectral images of the N2+ first negative bands in the dayglow were measured by the Imaging Spectrometric Observatory on the Spacelab 1 shuttle mission. These data contained two unexpected characteristics: the intensities were considerably higher than current photochemistry predicts (by factors of 3-5), and the bands showed larger than expected populations in the higher vibrational levels. Both of these characteristics persisted throughout the mission and were independent of vehicle attitude. The spectra were imaged for the second time in the dayglow by the same instrument from the ATLAS-1 shuttle mission in March 1992, providing an opportunity to re-examine these issues. The vibrational distributions measured from ATLAS-1 are found to be rather similar to those measured from Spacelab 1, but with somewhat lower populations in levels, nu' = 2 and 3. The Spacelab 1 and the ATLAS-1 missions were the first opportunities to image the DELTAnu = +1 progression at 3584 angstrom, allowing the first determinations of the populations in levels higher than 2, which earlier studies were not able to address. The integrated column intensities of the 0-0 band emission at 3914 angstrom as measured from ATLAS-1 are found to be in good agreement with model values, while the Spacelab 1 intensities appear to have been significantly affected by vehicle-induced effects. It would appear that the Spacelab 1 mission was highly anomalous in this regard, and the emission spectra from that mission are contaminated by non-ambient features, many of which are from the same species as are found in the thermosphere. The ion environment, in particular, appears to have been very perturbed on that mission. By contrast, the ATLAS-1 mission spectra appear to be very clean and do not show obvious evidence of vehicle effects. It appears that the absence of the large pressurized double-Spacelab module that occupied much of the payload bay for Spacelab 1, and the revised payload and orbiter processing procedures, have resulted in an environment that is substantially improved for remote sensing purposes. Studies of natural emissions, such as this one of the N2+ bands, are feasible and provide good data for modeling of the region. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. SCI & ENGN ASSOCIATES INC,HUNTSVILLE,AL 35816. BOEING COMP SUPPORT SERV INC,HUNTSVILLE,AL 35824. RP TORR, MR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 5 TC 4 Z9 4 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 MAR 19 PY 1993 VL 20 IS 6 BP 523 EP 526 DI 10.1029/93GL00244 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800028 ER PT J AU FENNELLY, JA TORR, DG TORR, MR RICHARDS, PG YUNG, S AF FENNELLY, JA TORR, DG TORR, MR RICHARDS, PG YUNG, S TI RETRIEVAL OF THERMOSPHERIC ATOMIC OXYGEN, NITROGEN AND TEMPERATURE FROM THE 732 NM EMISSION MEASURED BY THE ISO ON ATLAS-1 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR AB The Imaging Spectrometric Observatory (ISO) was a part of the ATLAS 1 Mission flown on the shuttle Atlantis from March 24 to April 2, 1992. During limb scanning operations, the ISO measured the O+(2P) ion emission at 732 nm. We have used a numerical inversion technique to retrieve thermospheric atomic oxygen, molecular nitrogen and temperature profiles. These preliminary results indicate a lower thermospheric temperature cooler than that predicted by MSIS for the solar conditions during the mission. Although the densities agree at low altitudes, the reduced scale height produces O and N2 densities 25% lower than the MSIS at 300 km. C1 UNIV ALABAMA,DEPT COMP SCI,HUNTSVILLE,AL 35899. SCI APPLICAT SUPPORT SERV INC,BOEING COMP SUPPORT SERV,HUNTSVILLE,AL 35824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP FENNELLY, JA (reprint author), UNIV ALABAMA,DEPT PHYS,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 10 TC 5 Z9 5 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 MAR 19 PY 1993 VL 20 IS 6 BP 527 EP 530 DI 10.1029/93GL00615 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800029 ER PT J AU TORR, MR TORR, DG RICHARDS, PG AF TORR, MR TORR, DG RICHARDS, PG TI N(2P) IN THE DAYGLOW - MEASUREMENT AND THEORY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATOMIC NITROGEN; AURORA; DISSOCIATION; EXCITATION; MODEL AB During the ATLAS-1 mission, the first dayglow altitude profiles were obtained of the N(2P) emission at 3466 angstrom. These observations were made in the sunlit thermosphere using the Imaging Spectrometric Observatory. As all previous work on this emission has been done under auroral conditions, this study represents the first examination of the photochemical sources and sinks of N(2P) in the normal daytime thermosphere, with comparison with measurements. We find that the observations are explained by a model in which the major source is photodissociation of N2, and quenching by O is the principal low-altitude loss process, with radiative decay to N(2D) dominating above 200 km. As the dominant loss processes are likely to result in the production of N(2D), N(2P) could be a moderate source of N(2D) and may be a factor to be taken into consideration in modeling NO. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP TORR, MR (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 21 TC 7 Z9 7 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 MAR 19 PY 1993 VL 20 IS 6 BP 531 EP 534 DI 10.1029/92GL02180 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KU908 UT WOS:A1993KU90800030 ER PT J AU POHORILLE, A BENJAMIN, I AF POHORILLE, A BENJAMIN, I TI STRUCTURE AND ENERGETICS OF MODEL AMPHIPHILIC MOLECULES AT THE WATER LIQUID VAPOR INTERFACE - A MOLECULAR-DYNAMICS STUDY SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID 2ND HARMONIC-GENERATION; LONG-CHAIN MOLECULES; MONTE-CARLO SIMULATION; CHARGED MOLECULES; SOLVATION; MONOLAYER; ADSORPTION; BEHAVIOR; MEMBRANE; PROTEINS AB A molecular dynamics study of adsorption of p-n-pentylphenol at infinite dilution at the water liquid-vapor interface is reported. The calculated free energy of adsorption is -8.8 +/- 0.7 kcal/mol, in good agreement with the experimental value of -7.3 kcal/mol. The transition between the interfacial region and the bulk solution is sharp and well-defined by energetic, conformational, and orientational criteria. At the water surface, the phenol head group is mostly immersed in aqueous solvent. The most frequent orientation of the hydrocarbon tail is parallel to the interface, due to dispersion interactions with the water surface. This arrangement of the phenol ring and the alkyl chain requires that the chain exhibits a kink. As the polar head group is being moved into the solvent, the chain length increases and the tail becomes increasingly aligned toward the surface normal, such that the nonpolar part of the molecule exposed to water is minimized. The same effect was achieved when phenol was replaced by a more polar head group, phenolate. This result underscores the difference between hydrophobic hydration at the surface and in the bulk solvent, when nonpolar molecular fragments adopt compact conformations. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF SANTA CRUZ,DEPT CHEM,SANTA CRUZ,CA 95064. RP POHORILLE, A (reprint author), UNIV CALIF SAN FRANCISCO,DEPT PHARMACEUT CHEM,SAN FRANCISCO,CA 94143, USA. FU NCI NIH HHS [NCA-2 315] NR 41 TC 46 Z9 46 U1 1 U2 11 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 18 PY 1993 VL 97 IS 11 BP 2664 EP 2670 DI 10.1021/j100113a030 PG 7 WC Chemistry, Physical SC Chemistry GA KT613 UT WOS:A1993KT61300030 PM 11539476 ER PT J AU KEYSER, LF LEU, MT MOORE, SB AF KEYSER, LF LEU, MT MOORE, SB TI COMMENT ON POROSITIES OF ICE FILMS USED TO SIMULATE STRATOSPHERIC CLOUD SURFACES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Note RP KEYSER, LF (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 5 TC 68 Z9 68 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 18 PY 1993 VL 97 IS 11 BP 2800 EP 2801 DI 10.1021/j100113a053 PG 2 WC Chemistry, Physical SC Chemistry GA KT613 UT WOS:A1993KT61300053 ER PT J AU JEDRZEJAS, MJ MARTUCH, RA TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF AF JEDRZEJAS, MJ MARTUCH, RA TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF TI STRUCTURE OF BIS(4-METHYLPYRIDINE-N)COPPER(I) BROMIDE SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article AB Bromobis(4-methylpyridine)copper(I), [CuBr(C6H7N)2], M(r) = 329.71, triclinic, P1BAR, a = 9.254 (7), b = 9.736 (3), c = 7.955 (3) angstrom, alpha = 102.34 (3), beta = 112.33 (3), gamma = 95.09 (4)-degrees, V = 636.2 (6) angstrom3 , Z = 2, D(m) = 1.8, D(x) = 1.721 g cm-3, lambda(Mo Kalpha) = 0.710326 angstrom, mu = 50.84 cm-1, F(000) = 328, T = 293 K, R = 0.057, wR = 0.088, for 1517 independent observed [I > 3sigma(I)] reflections. An interesting structural feature of this compound is a distance between Cu atoms of 3.101 (2) angstrom within the same unit cell compared to a distance of 6.124 (2) angstrom between Cu atoms of different unit cells. C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,CLEVELAND,OH 44135. NR 5 TC 4 Z9 4 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD MAR 15 PY 1993 VL 49 BP 536 EP 538 DI 10.1107/S0108270192006279 PN 3 PG 3 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA KU863 UT WOS:A1993KU86300042 ER PT J AU JEDRZEJAS, MJ TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF AF JEDRZEJAS, MJ TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF TI STRUCTURE OF BIS(BENZENESULFONATO-O)TETRAKIS(PYRIDINE-N)COPPER(II) SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article AB [Cu(C6H5O3S)2(C5H5N)4], M(r) = 694.29, monoclinic, C2/c, a = 15.180 (6), b = 14.431 (5), c = 15.269 (6) angstrom, beta = 96.38 (4)-degrees, V = 3324 (2) angstrom3, Z = 4 D(x) = 1.388 g cm-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 8.54 cm-1, F(000) = 1436, T = 295 K, R = 0.067, wR = 0.087 for 1141 independent reflections with I greater-than-or-equal-to 3sigma(I) and 207 variables. The [Cu(O3SC6H5)2(C5H5N)4] complex has a distorted trans octahedral stereochemistry. The bond angles about the Cu atom are consistent with this structure type. The important bond distances and angles are: Cu-O1 2.471 (8), S-Cl 1.785 (10) angstrom, Cu-O1-S 154.1 (6), O1-S-O2 112.3 (5), 01-S-O3 111.5 (5)-degrees. C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,CLEVELAND,OH 44135. NR 8 TC 6 Z9 6 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD MAR 15 PY 1993 VL 49 BP 538 EP 540 DI 10.1107/S0108270192006280 PN 3 PG 3 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA KU863 UT WOS:A1993KU86300043 ER PT J AU ANDRAS, MT HEPP, AF FANWICK, PE MARTUCH, RA DURAJ, SA AF ANDRAS, MT HEPP, AF FANWICK, PE MARTUCH, RA DURAJ, SA TI STRUCTURE OF 4-METHYLPYRIDINIUM BROMIDE SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article AB Gamma-Picolinium bromide, [C6H7NH]Br, M(r) = 174.05, monoclinic, Cm, a = 8.785 (4), b = 8.318 (3), c = 4.920 (1) angstrom, beta = 103.62 (3)-degrees, V = 349.4 (4) angstrom3, Z = 2, D(x) = 1.654 g cm 3, lambda(Mo Kalpha) = 0.71673 angstrom, mu = 57.23 cm-1, F(000) = 172, T = 293 K, R = 0.033 for 415 reflections with F(o)2 > 3sigma(F(o)2 and 41 variables. The compound consists of C6H7NH+ cations and Br- anions. Both species reside on crystallographic mirror planes defined by the Br, N(1), C(4), C(7) and H(71) atoms. The Br-N distance is 3.12 (1) angstrom. C1 NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,MS 302-1,CLEVELAND,OH 44135. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NR 8 TC 4 Z9 4 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD MAR 15 PY 1993 VL 49 BP 548 EP 550 DI 10.1107/S0108270192006826 PN 3 PG 3 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA KU863 UT WOS:A1993KU86300048 ER PT J AU MADER, TH GIBSON, CR CAPUTO, M HUNTER, N TAYLOR, G CHARLES, J MEEHAN, RT AF MADER, TH GIBSON, CR CAPUTO, M HUNTER, N TAYLOR, G CHARLES, J MEEHAN, RT TI INTRAOCULAR-PRESSURE AND RETINAL VASCULAR CHANGES DURING TRANSIENT EXPOSURE TO MICROGRAVITY SO AMERICAN JOURNAL OF OPHTHALMOLOGY LA English DT Article AB We measured intraocular pressures and retinal vascular diameters from 11 subjects during 20 seconds of microgravity produced by parabolic flight on board a KC-135 aircraft. Intraocular pressures increased 58% during parabolic flight compared to baseline values (19 +/- 1 mm Hg vs 12 +/- 1 mm Hg, respectively; P < .001). A 4% reduction in the caliber of retinal arteries was also noted during microgravity, but this change did not achieve statistical significance (7.8 +/- 0.3 pixels at zerogravity vs 8.1 +/- 0.3 pixels at 1g; P = .07). The increase in intraocular pressure and trend of arteries to constrict are thought to result from cephalad shifts in intravascular and extravascular body fluids as a result of the absence of the 1g hydrostatic gradient. The results of our study confirm that this fluid shift and its effects on the eye occur rapidly, within 20 seconds of exposure to microgravity. C1 ST JOHN EYE ASSOCIAT,HOUSTON,TX. KRUG LIFE SCI INC,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV COLORADO,HLTH SCI CTR,DENVER,CO 80262. RP MADER, TH (reprint author), MADIGAN ARMY MED CTR,OPHTHALMOL SERV,TACOMA,WA 98431, USA. NR 15 TC 25 Z9 29 U1 0 U2 3 PU OPHTHALMIC PUBL CO PI CHICAGO PA 77 WEST WACKER DR, STE 660, CHICAGO, IL 60601 SN 0002-9394 J9 AM J OPHTHALMOL JI Am. J. Ophthalmol. PD MAR 15 PY 1993 VL 115 IS 3 BP 347 EP 350 PG 4 WC Ophthalmology SC Ophthalmology GA KQ126 UT WOS:A1993KQ12600010 PM 8442494 ER PT J AU SCHACHAM, SE MENA, RA HAUGLAND, EJ ALTEROVITZ, SA AF SCHACHAM, SE MENA, RA HAUGLAND, EJ ALTEROVITZ, SA TI ROOM-TEMPERATURE DETERMINATION OF 2-DIMENSIONAL ELECTRON-GAS CONCENTRATION AND MOBILITY IN HETEROSTRUCTURES SO APPLIED PHYSICS LETTERS LA English DT Article AB A technique for determination of room-temperature two-dimensional electron gas (2DEG) concentration and mobility in heterostructures is presented. Using simultaneous fits of the longitudinal and transverse voltages as a function of applied magnetic field, we were able to separate the parameters associated with the 2DEG from those of the parallel layer. Comparison with the Shubnikov-de Haas data derived from measurements at liquid helium temperatures proves that the analysis of the room-temperature data provides an excellent estimate of the 2DEG concentration. In addition we were able to obtain for the first time the room-temperature mobility of the 2DEG, an important parameter to device application. Both results are significantly different from those derived from conventional Hall analysis. RP SCHACHAM, SE (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 5 TC 14 Z9 14 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 15 PY 1993 VL 62 IS 11 BP 1283 EP 1285 DI 10.1063/1.108708 PG 3 WC Physics, Applied SC Physics GA KR574 UT WOS:A1993KR57400038 ER PT J AU AHUMADA, AJ TABERNERO, A AF AHUMADA, AJ TABERNERO, A TI DEVELOPING A TRANSLATION-INVARIANT CORTEX TRANSFORMATION FROM AN IRREGULAR RETINA SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. INST OPT,MADRID,SPAIN. NR 0 TC 1 Z9 1 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1993 VL 34 IS 4 BP 707 EP 707 PG 1 WC Ophthalmology SC Ophthalmology GA KT893 UT WOS:A1993KT89300022 ER PT J AU PAVEL, M AF PAVEL, M TI STATIC APERTURE PROBLEM AND INFORMATION FUSION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NYU,NEW YORK,NY 10003. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1993 VL 34 IS 4 BP 707 EP 707 PG 1 WC Ophthalmology SC Ophthalmology GA KT893 UT WOS:A1993KT89300020 ER PT J AU MULLIGAN, JB AF MULLIGAN, JB TI CLASSIFICATION OF COLOR X-JUNCTIONS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1993 VL 34 IS 4 BP 766 EP 766 PG 1 WC Ophthalmology SC Ophthalmology GA KT893 UT WOS:A1993KT89300322 ER PT J AU WATSON, AB TURANO, K ECKERT, MP AF WATSON, AB TURANO, K ECKERT, MP TI THE OPTIMAL MOTION STIMULUS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. JOHNS HOPKINS UNIV,BALTIMORE,MD 21205. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1993 VL 34 IS 4 BP 975 EP 975 PG 1 WC Ophthalmology SC Ophthalmology GA KT893 UT WOS:A1993KT89301341 ER PT J AU STONE, LS PERRONE, JA AF STONE, LS PERRONE, JA TI HUMAN HEADING PERCEPTION CANNOT BE EXPLAINED USING A LOCAL DIFFERENTIAL MOTION ALGORITHM SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV WAIKATO,HAMILTON,NEW ZEALAND. NR 4 TC 5 Z9 5 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1993 VL 34 IS 4 BP 1229 EP 1229 PG 1 WC Ophthalmology SC Ophthalmology GA KT893 UT WOS:A1993KT89302576 ER PT J AU SINGH, J VELLAIKAL, M AF SINGH, J VELLAIKAL, M TI NUCLEATION OF DIAMOND DURING HOT FILAMENT CHEMICAL VAPOR-DEPOSITION SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID METHANE; GROWTH AB We have investigated the mechanism of nucleation of diamond during hot filament chemical vapor deposition process by high resolution transmission electron microscopy. Diamond was deposited on copper grids which were directly mounted on a high resolution transmission electron microscopy holder in order to study nucleation and growth characteristics of crystalline diamond. We have found direct evidence for the formation of a diamond-like amorphous carbon layer 8-14 nm thick in which small diamond microcrystallites about 2-5 nm across were embedded. These diamond microcrystallites were formed as a result of direct transformation of diamond-like carbon into diamond. Large diamond crystallites were observed to grow from these microcrystallites. It is envisaged that the diamond microcrystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth on which the large diamond crystallites grew. C1 N CAROLINA STATE UNIV,DEPT MAT SCI & ENGN,RALEIGH,NC 27695. RP SINGH, J (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAIL STOP EH 23,HUNTSVILLE,AL 35812, USA. NR 12 TC 36 Z9 37 U1 2 U2 4 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 MAR 15 PY 1993 VL 73 IS 6 BP 2831 EP 2834 DI 10.1063/1.353034 PG 4 WC Physics, Applied SC Physics GA KT869 UT WOS:A1993KT86900033 ER PT J AU HWANG, IH MEADOR, WE AF HWANG, IH MEADOR, WE TI AN ANALYTICAL MODEL FOR LONGITUDINALLY PUMPED CONTINUOUS-WAVE LASER (VOL 72, PG 2556, 1992) SO JOURNAL OF APPLIED PHYSICS LA English DT Correction, Addition C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HWANG, IH (reprint author), HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668, USA. NR 1 TC 0 Z9 0 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 MAR 15 PY 1993 VL 73 IS 6 BP 3117 EP 3117 DI 10.1063/1.354100 PG 1 WC Physics, Applied SC Physics GA KT869 UT WOS:A1993KT86900083 ER PT J AU MORALEJO, C CODY, RJ ALLEN, JE AF MORALEJO, C CODY, RJ ALLEN, JE TI NONLOCAL THERMODYNAMIC-EQUILIBRIUM EFFECTS OF VIBRATIONALLY EXCITED NO SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID INTERNAL STATE DISTRIBUTION; INDUCED FLUORESCENCE DETERMINATION; UPPER-ATMOSPHERE; NITRIC-OXIDE; H+NO2->OH+NO AB The vibrational distribution of NO(X 2pi) from the reaction O(3P) +NO2(X 2A1) --> NO(X 2pi,nu'')+O2 was studied at room temperature in a fast-flow system. Oxygen atoms were produced via the microwave-discharge dissociation of molecular oxygen with argon as the carrier gas. The reaction time between the NO2 molecules and the oxygen atoms was kept at approximately 3 ms to minimize vibrational energy quenching. NO(X) radicals were detected via laser-induced fluorescence of the A 2SIGMA+ <-- X 2pi electronic transition. The relative vibrational population ratio of NO in the ground electronic state was determined to be 87.4 +/-2.6% and 12.6+/-2.7% in the v''=0 and v''=1 levels, respectively. No higher vibrational states were observed. The NO vibrational population ratio measured in this study correlates well with the earlier observation of high vibrational excitation in O2. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,GREENBELT,MD 20771. RI Cody, Regina/D-5996-2013 NR 23 TC 0 Z9 0 U1 0 U2 1 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 MAR 15 PY 1993 VL 98 IS 6 BP 4707 EP 4710 DI 10.1063/1.464974 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KU222 UT WOS:A1993KU22200039 ER PT J AU SCHWENKE, DW WALCH, SP TAYLOR, PR AF SCHWENKE, DW WALCH, SP TAYLOR, PR TI A GLOBAL POTENTIAL-ENERGY SURFACE FOR ARH2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID VANDERWAALS POTENTIALS; CROSS-SECTIONS; RECOMBINATION; SCATTERING; KR; XE AB We describe an analytic representation of the ArH2 potential energy surface which well reproduces the results of extensive ab initio electronic structure calculations. We also give an empirical modification of the function designed to improve agreement with experimental estimates of the van der Waals minimum. The analytic representation smoothly interpolates between the H + H and strong bonding H-2 limits. In the fitting process, an accurate reproduction of regions of the potential expected to be important for high temperature (approximately 3000 K) collision processes is emphasized. Overall, the analytic representation well reproduces the anisotropy and H-2 bond length dependence of the input data. C1 ELORET INST,PALO ALTO,CA 94303. RP SCHWENKE, DW (reprint author), NASA,AMES RES CTR,MS 230-3,MOFFETT FIELD,CA 94035, USA. RI schwenke, david/I-3564-2013 NR 18 TC 20 Z9 20 U1 1 U2 2 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 MAR 15 PY 1993 VL 98 IS 6 BP 4738 EP 4744 DI 10.1063/1.464977 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KU222 UT WOS:A1993KU22200043 ER PT J AU SURAMPUDI, S SHEN, DH HUANG, CK NARAYANAN, SR ATTIA, A HALPERT, G PELED, E AF SURAMPUDI, S SHEN, DH HUANG, CK NARAYANAN, SR ATTIA, A HALPERT, G PELED, E TI EFFECT OF CYCLING ON THE LITHIUM ELECTROLYTE INTERFACE IN ORGANIC ELECTROLYTES SO JOURNAL OF POWER SOURCES LA English DT Article; Proceedings Paper CT 6TH INTERNATIONAL MEETING ON LITHIUM BATTERIES ( 6-IMLB ) CY MAY 10-15, 1992 CL MUNSTER, GERMANY SP DEUT AKAD AUSTAUSCHDIENST, DEUT FORSCHUNGSGEMEINSCH, MINIST FORSCH & WISSENSCH LANDES NORDRHEINWESTFALEN, UNIV MUNSTER, GRACE, PRIVATBRAUEREI A ROLINCK, RENATA BATTERIES, SONNENSCHEIN LITHIUM, VARTA BATTERIE AB The successful operation of ambient temperature secondary lithium cells is primarily dependent on the lithium/electrolyte interface properties. In this study, an attempt has been made to study the effect of cell cycling on the lithium/electrolyte interface by nondestructive methods such as a.c. impedance spectroscopy and microcalorimetry. Experimental Li-TiS2 cells were constructed and activated with different electrolytes. The cells delivered 30 to 300 cycles at 100% depth-of-discharge depending on the electrolyte. The reactivity of both uncycled and cycled lithium towards various electrolytes was studied by measuring the heat evolved from the cells under open-circuit condition at 25-degrees-C by microcalorimetry. Cycled cells at the end of charge/discharge showed considerably higher heat output compared with the uncycled cells. After thirty days of storage, the heat output of the cycled cells is similar to that of the uncycled cells. A.c. impedance analysis results indicate that the cell internal resistance increases with cycling, and this is attributed to the degradation of the electrolyte with cycling. The value R(f) was found to decrease with cycling. The observed decrease in R(f) is probably due to the increase in the surface area of the lithium anode due to cycling. The peak frequency was found to be in the range, 400 to 1000 Hz for both uncycled and cycled cells suggesting that the passivating film composition does not change significantly with cycling. C1 TEL AVIV UNIV,DEPT CHEM,IL-69978 TEL AVIV,ISRAEL. RP SURAMPUDI, S (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 5 TC 8 Z9 8 U1 0 U2 7 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD MAR 15 PY 1993 VL 43 IS 1-3 BP 21 EP 26 DI 10.1016/0378-7753(93)80098-A PG 6 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA LH762 UT WOS:A1993LH76200004 ER PT J AU SHEN, DH HALPERT, G AF SHEN, DH HALPERT, G TI DESIGN CONCEPTS OF HIGH-POWER BIPOLAR RECHARGEABLE LITHIUM BATTERY SO JOURNAL OF POWER SOURCES LA English DT Article; Proceedings Paper CT 6TH INTERNATIONAL MEETING ON LITHIUM BATTERIES ( 6-IMLB ) CY MAY 10-15, 1992 CL MUNSTER, GERMANY SP DEUT AKAD AUSTAUSCHDIENST, DEUT FORSCHUNGSGEMEINSCH, MINIST FORSCH & WISSENSCH LANDES NORDRHEINWESTFALEN, UNIV MUNSTER, GRACE, PRIVATBRAUEREI A ROLINCK, RENATA BATTERIES, SONNENSCHEIN LITHIUM, VARTA BATTERIE AB The present study shows that current bipolar Li/TiS2 batteries using a 0.38 mm thick TiS2 bipolar plate, can yield moderate specific power and also high specific energy battery. The computer design studies project that a 100 V, 10 A h bipolar Li/TiS2 battery can achieve 150 W h/kg, 210 W h/l, and 150 W/kg. The unoptimized experimental bipolar Li/TiS2 batteries (3 cells, 90 mA h) exhibited 47 W h/kg, 90 W h/l, and 140 W/kg. Preliminary results on the cycleability of the bipolar batteries were demonstrated. The results also show that enhanced rate capability can be achieved by using pulse discharge and longer rest period between pulses. RP SHEN, DH (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 3 Z9 3 U1 0 U2 5 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD MAR 15 PY 1993 VL 43 IS 1-3 BP 327 EP 338 DI 10.1016/0378-7753(93)80130-H PG 12 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA LH762 UT WOS:A1993LH76200036 ER PT J AU FRITTS, DC WANG, DY BLANCHARD, RC AF FRITTS, DC WANG, DY BLANCHARD, RC TI GRAVITY-WAVE AND TIDAL STRUCTURES BETWEEN 60-KM AND 140-KM INFERRED FROM SPACE-SHUTTLE REENTRY DATA SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MIDDLE ATMOSPHERE; POKER FLAT; THERMOSPHERIC TIDES; COUPLED COMPOSITION; LOWER STRATOSPHERE; AURORAL FORCINGS; SUMMER MESOPAUSE; MOMENTUM FLUXES; POLAR MESOPAUSE; SATURATION AB This study presents an analysis of density measurements made using high-resolution accelerometers aboard several space shuttles at altitudes from 60 to 140 km during reentry into the earth's atmosphere. The observed density fluctuations are interpreted in terms of gravity waves and tides and provide evidence of the importance of such motions well into the thermosphere. Height profiles of fractional density variance reveal that wave amplitudes increase at a rate consistent with observations at lower levels up to approximately 90 km. The rate of amplitude growth decreases at greater heights, however, and appears to cease above approximately 110 km. Wave amplitudes are nevertheless large at these heights and suggest that gravity waves may play an important role in forcing of the lower thermosphere. C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. INST SPACE & TERRESTRIAL SCI,N YORK,ON,CANADA. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP FRITTS, DC (reprint author), UNIV COLORADO,DEPT ELECT & COMP ENGN,CAMPUS BOX 425,BOULDER,CO 80309, USA. NR 38 TC 8 Z9 8 U1 0 U2 0 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 MAR 15 PY 1993 VL 50 IS 6 BP 837 EP 849 DI 10.1175/1520-0469(1993)050<0837:GWATSB>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KV365 UT WOS:A1993KV36500004 ER PT J AU SCHOLL, MS AF SCHOLL, MS TI STAR-FIELD IDENTIFICATION ALGORITHM SO OPTICS LETTERS LA English DT Article AB A six-feature, all-sky star-field identification algorithm has been developed. The minimum identifiable star pattern element consists of an oriented star triplet defined by three stars, their celestial coordinates, and their visual magnitudes. C1 JET PROP LAB,PASADENA,CA 91109. RP SCHOLL, MS (reprint author), ALENKA ASSOCIATES,POB 27408,TEMPE,AZ 85285, USA. NR 11 TC 8 Z9 8 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAR 15 PY 1993 VL 18 IS 6 BP 399 EP 401 DI 10.1364/OL.18.000399 PG 3 WC Optics SC Optics GA KP967 UT WOS:A1993KP96700001 PM 19802148 ER PT J AU SCHOLL, MS AF SCHOLL, MS TI EXPERIMENTAL DEMONSTRATION OF A STAR-FIELD IDENTIFICATION ALGORITHM SO OPTICS LETTERS LA English DT Article AB A fault-tolerant, six-feature, all-sky star-field identification algorithm has been integrated with a CCD-based imaging camera. This autonomous intelligent camera identifies in real time any star field without a priori knowledge and requires a reference catalog incorporating fewer than 1000 stars. Observatory tests on star fields with this intelligent camera are described. C1 JET PROP LAB,PASADENA,CA 91109. RP SCHOLL, MS (reprint author), ALENKA ASSOCIATES,POB 27408,TEMPE,AZ 85285, USA. NR 6 TC 12 Z9 12 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAR 15 PY 1993 VL 18 IS 6 BP 402 EP 404 DI 10.1364/OL.18.000402 PG 3 WC Optics SC Optics GA KP967 UT WOS:A1993KP96700002 PM 19802149 ER PT J AU VASQUEZ, RP FOOTE, MC HUNT, BD BARNER, JB AF VASQUEZ, RP FOOTE, MC HUNT, BD BARNER, JB TI GROWTH OF YBA2CU3O7-DELTA ON ALKALINE-EARTH FLUORIDE SUBSTRATES AND THIN-FILMS SO PHYSICA C LA English DT Article ID RAY PHOTOELECTRON-SPECTROSCOPY; BUFFER LAYERS; SURFACES; SILICON; CAF2 AB The growth and characterization of YBa2Cu3O7-delta (YBCO) thin films grown by laser ablation on MgF2 (100), CaF2 (100), SrF2 (100), and BaF2 (100) substrates, and on CaF2 and BaF2 thin films on LaAlO3 (100) substrates, are described. High quality superconducting YBCO films could be grown directly only on the BaF2 substrates and thin films. YBCO films grown directly on MgF2 or CaF2 substrates were insulating and showed clear signs of interdiffusion and reaction, as measured by X-ray photoelectron spectroscopy. Superconducting YBCO films could be grown on SrF2 and CaF2 substrates and thin films only with an yttria-stabilized zirconia buffer layer and/or with a low YBCO growth temperature, while YBCO grown on MgF2 yielded insulating films for all growth conditions investigated. The highest quality YBCO films were obtained on BaF2 substrates (T(c) = 87.6 K, DELTAT(c) = 0.3 K). These results are discussed in terms of the thermodynamic stability of possible reaction products and the temperature dependence of the ionic mobilities. RP VASQUEZ, RP (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 25 TC 7 Z9 7 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD MAR 15 PY 1993 VL 207 IS 3-4 BP 266 EP 272 DI 10.1016/0921-4534(93)90309-E PG 7 WC Physics, Applied SC Physics GA KT694 UT WOS:A1993KT69400010 ER PT J AU BARNER, JB HUNT, BD FOOTE, MC PIKE, WT VASQUEZ, RP AF BARNER, JB HUNT, BD FOOTE, MC PIKE, WT VASQUEZ, RP TI YBA2CU3O7-DELTA-BASED, EDGE-GEOMETRY SNS JOSEPHSON-JUNCTIONS WITH LOW-RESISTIVITY PRBA2CU3O7-DELTA BARRIERS SO PHYSICA C LA English DT Article ID BOUNDARY CRITICAL CURRENTS; ORIENTATION DEPENDENCE; YBA2CU3O7 FILMS; WEAK LINKS; DC SQUIDS; FABRICATION; BICRYSTALS AB We investigated the properties of all-high-T(c) edge-geometry Josephson weak links using superconducting YBa2Cu3O7-delta (YBCO) electrodes and PrBa2Cu3O7-delta (PBCO) normal-metal layers. The fabrication of the weak links involved first ion-milling the base YBCO film using a MgO mask to form the edge and then depositing PBCO and YBCO layers in situ by pulsed-laser deposition. The optimum PBCO films had resistivities of 2 to 4 mOMEGA cm at room temperature and approximately 30 mOMEGA cm at 4.2 K. Current-versus-voltage (I-V) characteristics were qualitatively consistent with the resistively-shunted-junction (RSJ) model. Strong Shapiro steps were present in the I-V characteristics of junctions under microwave irradiation and the critical current of the devices modulated with a Fraunhofer-like dependence asa function of magnetic field. The device parameters exhibited good scaling with area and PBCO thickness. The critical-current density varied exponentially with PBCO thickness, yielding a normal-metal coherence length of 9 nm for the PBCO. RP BARNER, JB (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 40 TC 33 Z9 34 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD MAR 15 PY 1993 VL 207 IS 3-4 BP 381 EP 390 DI 10.1016/0921-4534(93)90320-P PG 10 WC Physics, Applied SC Physics GA KT694 UT WOS:A1993KT69400021 ER PT J AU MACGIBBON, JH BRANDENBERGER, RH AF MACGIBBON, JH BRANDENBERGER, RH TI GAMMA-RAY SIGNATURES FROM ORDINARY COSMIC STRINGS SO PHYSICAL REVIEW D LA English DT Article ID SUPERCONDUCTING STRINGS; DOMAIN-WALLS; EVOLUTION; FLUX; RADIATION; SPECTRUM; ANNIHILATION; SIMULATION; PARTICLES; LIMITS AB We calculate the flux of ultrahigh-energy photons from individual ordinary (i.e., nonsuperconducting) cosmic strings and compare the results with the sensitivity of current and proposed TeV and EeV telescopes. Our calculations give only upper limits for the gamma-ray flux, since the source of the photons, jets from particle production at cusps, may be weakened by back-reaction effects. For the usual cosmic distribution of strings, the predicted bursts from strings with the value of mass per unit length associated with galaxy formation or light strings may just be detectable. A diffuse gamma-ray background from light strings may also be seen by the Fly's Eye detector at above 7 X 10(10) GeV. C1 BROWN UNIV, DEPT PHYS, PROVIDENCE, RI 02912 USA. RP MACGIBBON, JH (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 665, GREENBELT, MD 20771 USA. NR 70 TC 18 Z9 18 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1550-7998 EI 1550-2368 J9 PHYS REV D JI Phys. Rev. D PD MAR 15 PY 1993 VL 47 IS 6 BP 2283 EP 2296 DI 10.1103/PhysRevD.47.2283 PG 14 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA KT972 UT WOS:A1993KT97200012 ER PT J AU PRICE, RH PULLIN, J KUNDU, PK AF PRICE, RH PULLIN, J KUNDU, PK TI ESCAPE OF GRAVITATIONAL-RADIATION FROM THE FIELD OF MASSIVE BODIES SO PHYSICAL REVIEW LETTERS LA English DT Article AB We consider a compact source of gravitational waves of frequency omega, in or near a massive spherically symmetric distribution of matter or a black hole. Recent calculations have led to apparently contradictory results for the influence of the massive body on the propagation of the waves. We show here that the results are in fact consistent and in agreement with the ''standard'' viewpoint in which the high-frequency compact source produces the, radiation as if in a flat background, and the background curvature affects the propagation of these waves. C1 APPL RES CORP,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHER LAB,GREENBELT,MD 20771. RP PRICE, RH (reprint author), UNIV UTAH,DEPT PHYS,SALT LAKE CITY,UT 84112, USA. RI Kundu, Prasun/C-7212-2013 OI Kundu, Prasun/0000-0002-2284-9852 NR 8 TC 7 Z9 7 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD MAR 15 PY 1993 VL 70 IS 11 BP 1572 EP 1575 DI 10.1103/PhysRevLett.70.1572 PG 4 WC Physics, Multidisciplinary SC Physics GA KT366 UT WOS:A1993KT36600002 ER PT J AU GRYMES, RA SAWYER, C BROWN, MV AF GRYMES, RA SAWYER, C BROWN, MV TI STUDIES OF SENESCENT CELL BEHAVIOR IN RESPONSE TO PDGF UNDER CONDITIONS OF VARYING STRESS SO JOURNAL OF CELLULAR BIOCHEMISTRY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. MORRIS BROWN COLL,DEPT BIOL SCI,ATLANTA,GA 30314. NR 0 TC 0 Z9 0 U1 0 U2 0 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0730-2312 J9 J CELL BIOCHEM JI J. Cell. Biochem. PD MAR 13 PY 1993 SU 17D BP 154 EP 154 PG 1 WC Biochemistry & Molecular Biology; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA KV880 UT WOS:A1993KV88000531 ER PT J AU MARAIS, DJD STRAUSS, H SUMMONS, RE HAYES, JM AF MARAIS, DJD STRAUSS, H SUMMONS, RE HAYES, JM TI PROTEROZOIC CARBON-CYCLE - REPLY SO NATURE LA English DT Letter C1 RUHR UNIV BOCHUM,INST GEOL,W-4630 BOCHUM 1,GERMANY. AUSTRALIAN GEOL SURVEY ORG,CANBERRA,ACT 2605,AUSTRALIA. INDIANA UNIV,DEPT GEOL SCI,BIOGEOCHEM LABS,BLOOMINGTON,IN 47405. INDIANA UNIV,DEPT CHEM,BLOOMINGTON,IN 47405. RP MARAIS, DJD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 6 TC 0 Z9 0 U1 1 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD MAR 11 PY 1993 VL 362 IS 6416 BP 118 EP 118 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KR028 UT WOS:A1993KR02800036 ER PT J AU CHAO, TH STONER, WW AF CHAO, TH STONER, WW TI OPTICAL IMPLEMENTATION OF A FEATURE-BASED NEURAL NETWORK WITH APPLICATION TO AUTOMATIC TARGET RECOGNITION SO APPLIED OPTICS LA English DT Article ID MODEL; MEMORY; FEEDBACK AB An optical neural network based on the neocognitron paradigm [IEEE Trans. Syst. Man Cybern. SMC-13, 826-834 (1983)] is introduced. A novel aspect of the architectural design is shift-invariant multichannel Fourier optical correlation within each processing layer. Multilayer processing is achieved by feeding back the output of the feature correlator iteratively to the input spatial light modulator and by updating the Fourier filters. By training the neural net with characteristic features extracted from the target images, successful pattern recognition with intraclass fault tolerance and interclass discrimination is achieved. A detailed system description is provided. Experimental demonstrations of a two-layer neural network for space-object discrimination is also presented. C1 SCI APPLICAT INT CORP, BILLERICA, MA 01821 USA. RP CHAO, TH (reprint author), JET PROP LAB, CTR SPACE MICROELECTR TECHNOL, PASADENA, CA 91109 USA. NR 29 TC 10 Z9 11 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 MAR 10 PY 1993 VL 32 IS 8 BP 1359 EP 1369 PG 11 WC Optics SC Optics GA KT614 UT WOS:A1993KT61400013 PM 20820271 ER PT J AU FIELDS, BD SCHRAMM, DN TRURAN, JW AF FIELDS, BD SCHRAMM, DN TRURAN, JW TI BERYLLIUM AND BORON CONSTRAINTS ON AN EARLY GALACTIC BRIGHT PHASE SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; ELEMENTARY PARTICLES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; STARS, EVOLUTION ID COSMIC-RAY SPECTRUM; STARS; ABUNDANCES; NUCLEOSYNTHESIS; LITHIUM; DWARFS; RATIO; MODEL; LI AB The recent observations of Be and B in metal-deficient halo dwarfs are used to constrain a '' bright phase '' of enhanced cosmic-ray flux in the early Galaxy. Assuming that this Be and B arises from cosmic-ray spallation in the early Galaxy, limits are placed on the intensity of the early (Population II) cosmic-ray flux relative to the present (Population I) flux. A simple estimate of bounds on the flux ratio is 1 less than or similar PHI(Pop II)/PHI(Pop I) less than or similar 40. This upper bound would restrict galaxies like our own from producing neutrino fluxes that would be detectable in any currently proposed detectors. It is found that the relative enhancement of the early flux varies inversely with the relative time of enhancement. It is noted that associated gamma-ray production via pp --> pi0pp may be a significant contribution to the gamma-ray background above 100 MeV. C1 NASA,FERMILAB ASTROPHYS GRP,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. NR 51 TC 7 Z9 7 U1 1 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 MAR 10 PY 1993 VL 405 IS 2 BP 559 EP 566 DI 10.1086/172387 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP612 UT WOS:A1993KP61200016 ER PT J AU PETUCHOWSKI, SJ BENNETT, CL AF PETUCHOWSKI, SJ BENNETT, CL TI GALACTIC FINE-STRUCTURE LINES - MORPHOLOGIES OF THE WARM IONIZED INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; ISM, GENERAL ID H-II REGIONS; MOLECULAR CLOUDS; C-II; STAR FORMATION; MASSIVE STARS; EMISSION; DIFFUSE; GALAXY; MODEL; GAS AB Far-infrared ionic fine-structure emission lines associated with the large-scale structure of the Galactic ionized medium are interpreted in terms of a heuristic model in which three distinct source morphologies are considered: ionization-bounded H II regions; an extended, low-density medium; and externally ionized surfaces of neutral clouds. The model reveals that the overall luminosity of the Galaxy in the fine-structure lines of both C II and N II is due, in comparable proportions, to diffuse medium and the boundaries between ionized and neutral regions. Limits are set on the luminosity of the diffuse component in the plane of the Galaxy. Some individual lines of sight of the COBE FIRAS instrument are dominated, in these spectral lines, by H II regions, even with its 7-degrees field of view. Average densities of both H II regions and photodissociation regions are estimated on a Galactic scale. RP PETUCHOWSKI, SJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,MC 685,GREENBELT,MD 20771, USA. NR 33 TC 55 Z9 55 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 MAR 10 PY 1993 VL 405 IS 2 BP 591 EP 598 DI 10.1086/172390 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP612 UT WOS:A1993KP61200019 ER PT J AU CHAN, K LINGENFELTER, RE AF CHAN, K LINGENFELTER, RE TI POSITRONS FROM SUPERNOVAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ELEMENTARY PARTICLES; GAMMA RAYS, THEORY; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; SUPERNOVAE, GENERAL ID GALACTIC-CENTER DIRECTION; SHAPLEY-AMES GALAXIES; RAY LINE EMISSION; ANNIHILATION RADIATION; INTERSTELLAR-MEDIUM; I SUPERNOVAE; CENTER REGION; AL-26; EXPLOSIONS; MODELS AB Positrons are produced in the ejecta of supernovae by the decay of nucleosynthetic Co-56, Ti-44, and Al-26. We calculate the probability that these positrons can survive without annihilating in the supemova ejecta, and we show that enough of these positrons should escape into the interstellar medium to account for the observed diffuse Galactic annihilation radiation. We assume current supernova models with possible mixing and consider the limiting conditions of positron propagation, where they are either trapped locally in the ejecta or allowed to stream through the ejecta. The surviving positrons are carried by the expanding ejecta into the interstellar medium where their annihilation lifetime of approximately 10(5)-10(6) yr is much longer than the average supernovae occurrence time of approximately 10(2) yr. Thus, annihilating positrons from thousands of supernovae throughout the Galaxy produce a steady diffuse flux of annihilation radiation. We further show that combining the calculated positron survival fractions and nucleosynthetic yields for current supernova models with the estimated supernova rates and the observed flux of diffuse Galactic annihilation radiation suggests that the present Galactic rate of Fe-56 nucleosynthesis is approximately (0.8 +/- 0.6) M. per 100 yr. C1 UNIV CALIF SAN DIEGO, CTR ASTROPHYS & SPACE SCI, LA JOLLA, CA 92093 USA. RP CHAN, K (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 92 TC 68 Z9 68 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 MAR 10 PY 1993 VL 405 IS 2 BP 614 EP 636 DI 10.1086/172393 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP612 UT WOS:A1993KP61200022 ER PT J AU FONTENLA, JM RABIN, D HATHAWAY, DH MOORE, RL AF FONTENLA, JM RABIN, D HATHAWAY, DH MOORE, RL TI MEASUREMENT OF P-MODE ENERGY PROPAGATION IN THE QUIET SOLAR PHOTOSPHERE SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, ATMOSPHERE; SUN, OSCILLATIONS ID MECHANICAL FLUX; VERTICAL PROPAGATION; PHASE DELAYS; CHROMOSPHERE; WAVES; ATMOSPHERE AB We have measured and analyzed the p-mode oscillations in the profile of the Mg I 4571 angstrom line in a quiet region near disk center. The oscillations are found to be mostly standing waves, in agreement with previous work. However, a small propagating component is measured, and we determine the direction, magnitude, and vertical variation of the energy propagation. The work integral indicates an upward energy flow of approximately 2 x 10(7) ergs cm-2 s-1 at a height of 50 km above the base of the photosphere for waves with frequencies of 2-16 mHz. This energy flow decreases exponentially with height and drops below 10(5) ergs cm-2 s-1 in the uppermost photosphere (above approximately 300 km). The energy flow leaving the upper photosphere is at least an order of magnitude too small to constitute a significant source of heating for the chromosphere. However, the p-mode damping in the lower photosphere approaches levels large enough to account for the measured p-mode line widths. The relative amplitudes and phases of the thermodynamic quantities indicate that the p-mode are neither adiabatic nor isothermal in the photosphere. C1 ASSOC UNIV RES ASTRON INC,NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP FONTENLA, JM (reprint author), UNIV ALABAMA,CSPAR,HUNTSVILLE,AL 35899, USA. NR 20 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 MAR 10 PY 1993 VL 405 IS 2 BP 787 EP 797 DI 10.1086/172408 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP612 UT WOS:A1993KP61200037 ER PT J AU MILLER, RL AF MILLER, RL TI HIGH-RESOLUTION IMAGE-PROCESSING ON LOW-COST MICROCOMPUTERS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SURFACE AB Recent advances in microcomputer technology have resulted in systems that rival the speed, storage, and display capabilities of traditionally larger machines. Low-cost microcomputers can provide a powerful environment for image processing. A new software program which offers sophisticated image display and analysis on IBM-based systems is presented. Designed specifically for a microcomputer, this program provides a wide-range of functions normally found only on dedicated graphics systems, and therefore can provide most students, universities and research groups with an affordable computer platform for processing digital images. The processing of AVHRR images within this environment is presented as an example. RP MILLER, RL (reprint author), NASA,SCI & TECHNOL LAB,BAY ST LOUIS,MS 39529, USA. NR 9 TC 11 Z9 11 U1 0 U2 1 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 MAR 10 PY 1993 VL 14 IS 4 BP 655 EP 667 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA LB283 UT WOS:A1993LB28300003 ER PT J AU OPPENHEIMER, C FRANCIS, PW ROTHERY, DA CARLTON, RWT GLAZE, LS AF OPPENHEIMER, C FRANCIS, PW ROTHERY, DA CARLTON, RWT GLAZE, LS TI INFRARED IMAGE-ANALYSIS OF VOLCANIC THERMAL FEATURES - LASCAR VOLCANO, CHILE, 1984-1992 SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID MOUNT-ST-HELENS; ACTIVE VOLCANOS; THEMATIC MAPPER; ERUPTION; DOME AB Fifteen Landsat Thematic Mapper (TM) images of Lascar volcano (Chile), recorded between December 1984 and April 1992, document the evolution of a lava dome within the summit crater. Four of the scenes were acquired at night. In every image, the two short-wavelength infrared bands, 5 and 7, have detected thermal radiation from the volcano. As a consequence of the Planck distribution function, the relative response of these two channels depends on the proportions of very hot (> 600-degrees-C) surfaces occupying tiny pixel areas and broader regions at moderate temperatures (< 280-degrees-C). Intercomparison of bands 5 and 7 thereby provides a means for interpreting TM thermal anomalies even in the absence of ground observations. Pronounced changes in the configuration and intensity of the Lascar anomaly suggest that the volcano has experienced at least two cycles of lava dome activity since 1984. The first of these progressed through a ''cooling'' period, possibly reflecting a reduced flux of magmatic volatiles at the surface, and culminated in an explosive eruption on September 16, 1986, which appears to have completely destroyed the inferred lava dome. The TM data indicate that a new dome had been emplaced by November 1987, more than 15 months before it was first discovered by local observers. Lascar's style of cyclical effusive and explosive activity is typical of many volcanoes, and die remote sensing techniques presented herein could be applied elsewhere. C1 JET PROP LAB,PASADENA,CA 91109. RP OPPENHEIMER, C (reprint author), OPEN UNIV,DEPT EARTH SCI,MILTON KEYNES MK7 6AA,BUCKS,ENGLAND. RI Glaze, Lori/D-1314-2012; Oppenheimer, Clive/G-9881-2013 OI Oppenheimer, Clive/0000-0003-4506-7260 NR 40 TC 119 Z9 119 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-SOL EA JI J. Geophys. Res.-Solid Earth PD MAR 10 PY 1993 VL 98 IS B3 BP 4269 EP 4286 DI 10.1029/92JB02134 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KQ873 UT WOS:A1993KQ87300014 ER PT J AU IVINS, ER SAMMIS, CG YODER, CF AF IVINS, ER SAMMIS, CG YODER, CF TI DEEP MANTLE VISCOUS STRUCTURE WITH PRIOR ESTIMATE AND SATELLITE CONSTRAINT SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GLACIAL-ISOSTATIC-ADJUSTMENT; ACTIVATION VOLUME; VARIABLE VISCOSITY; GRAVITY-FIELD; CONVECTION; OLIVINE; CREEP; RHEOLOGY; LAGEOS; STATE AB Radial viscosity profiles are constructed for the mantle using plausible temperature profiles and high-temperature creep models in olivine. While it is possible to specifically design mantle thermal profiles that produce relatively constant viscosity, temperatures deduced from parametric and/or full numerical simulation of convection predict steep increases of viscosity with depth. The most ubiquitous trend is an increase in viscosity from about 800 to 900 km depth to the top of the D'' layer. Predicted increase of viscosity in this portion of the lower mantle ranges from a factor of 10(2) to 10(4). Precise estimates are impossible due uncertainty in determining activation volume V* and activation energy E*. Zeroth-order extrapolation of a creep law to lower mantle conditions requires the assumption that diffusion of a single ionic species controls dislocation mobility. The extrapolation is useful in spite of its great uncertainty. Our rationale consists of two essential elements: (1) Creep laws with depth-dependent prefactor A(r) and depth-dependent activation volume V*(r), energy E*(r), and enthalpy S*(r) can be parameterized using estimates of diffusion constants based on elasticity. (2) Secular changes in Earth's gravity field, particularly the zonal coefficients J(l) are now detected in the orbits of artificial satellites such as LAGEOS and Starlette. These secular changes are believed to be dominated by postglacial rebound, although there is some contribution from present-day glacial melting. These gravity field measurements, when combined with constraints on glacial melting, provide a sensitive set of constraints on lower mantle viscous response to the Last glacial epoch and, hence, provide a test of a priori estimates. A radially stratified and incompressible Earth model is used to test sensitivity of data to viscosity increases with depth and convective boundary layer structure. Prior estimates and observed nontidal J2(-C20) are consistent with a layered lower mantle viscosity. Details of this layering are examined by comparing predicted and observed J3, J4. Speculation that a high-viscosity layer exists above D'' is considered. With a 650-km-thick deep high-viscosity layer (eta almost-equal-to 6.0 x 10(23) Pa s) the remaining lower mantle is in one of two ranges: 1.5 to 3.5 x 10(20) or 3.5 to about 10 x 10(22) Pa s. Observational bounds on secular gravity coefficients C30, C40, C50, and C70 using LAGEOS, Starlette, or Etalon satellite data could eliminate the ambiguity between these two viscosity ranges. C1 UNIV SO CALIF, DEPT GEOL SCI, LOS ANGELES, CA 90089 USA. RP IVINS, ER (reprint author), JET PROP LAB, DIV EARTH & SPACE SCI, MS 183-501, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 95 TC 59 Z9 59 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD MAR 10 PY 1993 VL 98 IS B3 BP 4579 EP 4609 DI 10.1029/92JB02728 PG 31 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KQ873 UT WOS:A1993KQ87300038 ER PT J AU MALLA, RP WU, SC LICHTEN, SM AF MALLA, RP WU, SC LICHTEN, SM TI GEOCENTER LOCATION AND VARIATIONS IN EARTH ORIENTATION USING GLOBAL POSITIONING SYSTEM MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GRAVITY MODEL AB We have studied the use of Global Positioning System (GPS) ground and flight tracking data to measure short-period Earth orientation variations and changes in Earth's center of mass location (the geocenter). Ground-based GPS estimates of daily and subdaily changes in Earth orientation presently show centimeter-level precision. Comparisons between GPS-estimated Earth rotation variations (UTI-UTC) and those calculated from ocean tide models suggest that observed subdaily variations in Earth rotation are dominated by oceanic tidal effects. Our preliminary GPS estimates for geocenter location (from a 3-week experiment) agree with an independent satellite laser ranging estimates to 10-15 cm. Covariance analysis predicts that temporal resolution of GPS estimates for Earth orientation and geocenter improves significantly when data collected from low Earth-orbiting satellites as well as from ground sites are combined. The low-Earth GPS tracking data enhance the accuracy and resolution for measuring high-frequency global geodynamical signals over time scales less than 1 day. Low-Earth orbiters such as Topex/Poseidon carrying GPS flight receivers will provide opportunities to demonstrate these enhancements. RP MALLA, RP (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 4 Z9 4 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-SOL EA JI J. Geophys. Res.-Solid Earth PD MAR 10 PY 1993 VL 98 IS B3 BP 4611 EP 4617 DI 10.1029/92JB02588 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KQ873 UT WOS:A1993KQ87300039 ER PT J AU GILMOUR, S MARDER, SR TIEMANN, BG CHENG, LT AF GILMOUR, S MARDER, SR TIEMANN, BG CHENG, LT TI SYNTHESIS AND 1ST HYPERPOLARIZABILITIES OF ACCEPTOR-SUBSTITUTED BETA-APO-8'-CAROTENAL DERIVED COMPOUNDS SO JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS LA English DT Article ID SEMIEMPIRICAL METHODS; OPTIMIZATION; PARAMETERS; MOLECULES AB The synthesis and second-order nonlinear optical properties of acceptor-substituted biologically derived beta-apo-8'-carotenal compounds are reported; electric field-induced second harmonic generation (EFISH) measurements give values of beta(0) which are 2-6 times greater than for 4-NN-dimethylamino-4'-nitrostilbene (DANS). C1 DUPONT CO,DEPT CENT RES & DEV,EXPTL STN,WILMINGTON,DE 19880. CALTECH,BECKMAN INST,MOLEC MAT RESOURCE CTR,PASADENA,CA 91125. RP GILMOUR, S (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 TC 11 Z9 11 U1 0 U2 0 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0022-4936 J9 J CHEM SOC CHEM COMM JI J. Chem. Soc.-Chem. Commun. PD MAR 7 PY 1993 IS 5 BP 432 EP 433 DI 10.1039/c39930000432 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA KT299 UT WOS:A1993KT29900003 ER PT J AU SCHWENKE, DW MIELKE, SL TAWA, GJ FRIEDMAN, RS HALVICK, P TRUHLAR, DG AF SCHWENKE, DW MIELKE, SL TAWA, GJ FRIEDMAN, RS HALVICK, P TRUHLAR, DG TI CONVERGED QUANTUM-MECHANICAL CALCULATIONS OF ELECTRONIC-TO-VIBRATIONAL, ROTATIONAL ENERGY-TRANSFER PROBABILITIES IN A SYSTEM WITH A CONICAL INTERSECTION SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ALGEBRAIC VARIATIONAL CALCULATIONS; REACTIVE SCATTERING; COLLISIONS; EQUATIONS; EXCITATION; DYNAMICS; HE AB We present quantum-mechanical transition probabilities for the process Na(3p2P) +H2(nu0 = 0,j0 = 0, 2) --> Na(3s2S) + H-2(nu',j') with zero total angular momentum where nu0, j0, nu', and j' are initial and final vibrational and rotational quantum numbers. These calculations involve two coupled potential energy surfaces at a total energy of 2.431 eV, and the excited state has energetically accessible geometric configurations with H-H internuclear distances 2.7 times larger than the H-2 equilibrium internuclear distance - which makes converged quantum-mechanical calculations very difficult. Convergence is demonstrated by obtaining the same results using two entirely different methods - R matrix propagation and the outgoing wave variational principle. C1 UNIV MINNESOTA, INST SUPERCOMP, DEPT CHEM, CHEM PHYS PROGRAM, MINNEAPOLIS, MN 55455 USA. UNIV MINNESOTA, ARMY HIGH PERFORMANCE COMPUT RES CTR, MINNEAPOLIS, MN 55455 USA. RP SCHWENKE, DW (reprint author), NASA, AMES RES CTR, MAIL STOP 230-3, MOFFETT FIELD, CA 94035 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 43 TC 33 Z9 33 U1 0 U2 5 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 MAR 5 PY 1993 VL 203 IS 5-6 BP 565 EP 572 DI 10.1016/0009-2614(93)85311-B PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KP246 UT WOS:A1993KP24600022 ER PT J AU CHANDRA, S JACKMAN, CH DOUGLASS, AR FLEMING, EL CONSIDINE, DB AF CHANDRA, S JACKMAN, CH DOUGLASS, AR FLEMING, EL CONSIDINE, DB TI CHLORINE CATALYZED DESTRUCTION OF OZONE - IMPLICATIONS FOR OZONE VARIABILITY IN THE UPPER-STRATOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PHOTOCHEMISTRY; MODEL AB The annual mean and the annual amplitude of ozone have been derived from ozone measurements from the SBUV and SBUV/2 spectrometers on board the Nimbus-7 and NOAA-11 satellites. These values differ significantly from values calculated using a two-dimensional model of stratospheric photochemistry and dynamics with standard chemistry. We have found that the differences between the calculated and data-derived values are considerably improved by changing the partitioning in the Cl(y) family to create a larger reservoir of HCl and reducing ClO. This is accomplished by including a channel for the products HCl+O2 from the reaction ClO+OH in addition to the products Cl+HO2. This partitioning also improves the agreement between the calculated and measured values of ClO/HCl ratio. C1 APPL RES CORP,LANDOVER,MD 20785. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Douglass, Anne/D-4655-2012; Jackman, Charles/D-4699-2012 NR 18 TC 35 Z9 35 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 MAR 5 PY 1993 VL 20 IS 5 BP 351 EP 354 DI 10.1029/93GL00212 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KR866 UT WOS:A1993KR86600005 ER PT J AU LUNDGREN, PR WOLF, SK PROTTI, M HURST, KJ AF LUNDGREN, PR WOLF, SK PROTTI, M HURST, KJ TI GPS MEASUREMENTS OF CRUSTAL DEFORMATION ASSOCIATED WITH THE 22 APRIL 1991, VALLE-DE-LA-ESTRELLA, COSTA-RICA EARTHQUAKE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PANAMA AB We present analysis results for Global Positioning System (GPS) measurements made at sites in Costa Rica during two campaigns in February and July 1991. GPS solutions for 5 sites (Limon, Liberia, Bratsi, ETCG, and Vueltas) reveal significant horizontal and vertical displacements relative to their February positions. Horizontal displacements relative to Liberia, measured 244.7 +/- 0.8, 89.2 +/- 0.9, 12.4 +/- 1.3, and 1.9 +/- 0.9 cm at Limon, Bratsi, Vueltas, and ETCG respectively. Vertical displacements relative to Liberia measured 16.3 +/- 2.1, 15.3 +/- 3.0, -10.5 +/- 4.4, and -0.6 +/- 2.1 cm at Limon, Bratsi, Vueltas, and ETCG respectively. We find differences in the GPS derived vertical and horizontal displacements compared to other types of geodetic measurements of uplift in the coastal region and their associated models. To address these differences we compute a dislocation model which fits the GPS measured displacements. A simple uniform planar slip model can not reconcile the differences between the coastal uplift data or the seismic moment, suggesting considerable complexity of the earthquake source. C1 UNIV NACL HEREDIA,OBSERV VULCANOL & SISMOL COSTA RICA,HEREDIA,COSTA RICA. UNIV CALIF SANTA CRUZ,INST TECTON,CF RICHTER SEISMOL LAB,SANTA CRUZ,CA 95064. RP LUNDGREN, PR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Protti, Marino/0000-0001-9818-0051 NR 17 TC 11 Z9 11 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 MAR 5 PY 1993 VL 20 IS 5 BP 407 EP 410 DI 10.1029/93GL00294 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KR866 UT WOS:A1993KR86600019 ER PT J AU WU, TK LEE, SW ZIMMERMAN, ML AF WU, TK LEE, SW ZIMMERMAN, ML TI EVALUATION OF FREQUENCY-SELECTIVE REFLECTOR ANTENNA SYSTEMS SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE FREQUENCY-SELECTIVE SURFACE; REFLECTOR ANTENNA; GEOMETRIC OPTICS AB The performance of a four-frequency-band (S/X/Ku/Ka) frequency-selective surface (FSS) with double-ring elements is evaluated both for a flat panel development and for a curved subreflector in a dual reflector antenna. Good agreement is observed between the measured and computed data for the flat panel FSS. To accurately predict the FSS effects on a dual reflector antenna's radiation pattern, we take into account the FSS subreflector's transmitted/reflected field variation as functions of the polarization and incident angles with respect to the local coordinates. An FSS transmission/reflection coefficient table is computed for TE and TM polarizations at various incident angles based on the planar FSS model. Next, the hybrid geometric optics (GO) and physical optics (PO) technique is implemented with linear interpolation of the FSS table to efficiencly determine the FSS effects in a dual reflector antenna. RP WU, TK (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 6 Z9 7 U1 0 U2 1 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 MAR 5 PY 1993 VL 6 IS 3 BP 175 EP 179 DI 10.1002/mop.4650060307 PG 5 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA KL796 UT WOS:A1993KL79600006 ER PT J AU MINNIS, P HARRISON, EF STOWE, LL GIBSON, GG DENN, FM DOELLING, DR SMITH, WL AF MINNIS, P HARRISON, EF STOWE, LL GIBSON, GG DENN, FM DOELLING, DR SMITH, WL TI RADIATIVE CLIMATE FORCING BY THE MOUNT-PINATUBO ERUPTION SO SCIENCE LA English DT Article ID EL-CHICHON; BUDGET EXPERIMENT; VOLCANIC-ERUPTIONS; ATMOSPHERE; CLOUD AB Radiative flux anomalies derived from the National Aeronautics and Space Administration (NASA) spaceborne Earth Radiation Budget Experiment were used to determine the volcanic radiative forcing that followed the eruption of Mount Pinatubo in June 1991. They are the first unambiguous, direct measurements of large-scale volcanic forcing. The volcanic aerosols caused a strong cooling effect immediately; the amount of cooling increased through September 1991 as shortwave forcing increased relative to the longwave forcing. The primary effects of the aerosols were a direct increase in albedo over mostly clear areas and both direct and indirect increases in the albedo of cloudy areas. C1 NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,CAMP SPRINGS,MD 20233. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP MINNIS, P (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHERE SCI,HAMPTON,VA 23681, USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 43 TC 208 Z9 213 U1 2 U2 26 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 5 PY 1993 VL 259 IS 5100 BP 1411 EP 1415 DI 10.1126/science.259.5100.1411 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KP978 UT WOS:A1993KP97800024 PM 17801273 ER PT J AU BILITZA, D RAWER, K BOSSY, L GULYAEVA, T AF BILITZA, D RAWER, K BOSSY, L GULYAEVA, T TI INTERNATIONAL REFERENCE IONOSPHERE - PAST, PRESENT, AND FUTURE .1. ELECTRON-DENSITY SO ADVANCES IN SPACE RESEARCH LA English DT Article ID MODEL; FOF2; HEIGHT; MAPS; LATITUDE; VALUES; F0F2 AB In December 1990 a new IRI handbook was published b NASA's National Space Science Data Center (NSSDC) describing in detail the International Reference Ionosphere 1990. Shortly thereafter, the IRI-90 software was released on tape, diskette, and computer networks. This paper is intended as an inventory of the most important IRI activities up to 1990 and as a starting point for the next improvement cycle. It summarizes the work and studies that led to IRI-90 and provides an overview over this latest version of the model. Shortcomings and limitations are pointed out, and ways of overcoming them are discussed. Priorities are suggested for the list of work items that the IRI group has to tackle in the future. High on the wishlist are major improvements at high latitudes and inclusion of magnetic storm effects. This first paper deals with the electron density; a follow-on paper discusses plasma temperatures, ion composition, and ion drift. C1 NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,GREENBELT,MD 20771. UNIV FREIBURG,W-7800 FREIBURG,GERMANY. INST AERON SPATIALE BELGIQUE,B-1180 BRUSSELS,BELGIUM. INST TERR MAGNETISM IONOSPHERE & RADIO WAVE PROPAGAT,TROICK 142092,USSR. NR 91 TC 154 Z9 155 U1 1 U2 4 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 MAR PY 1993 VL 13 IS 3 BP 3 EP 13 DI 10.1016/0273-1177(93)90240-C PG 11 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA JY022 UT WOS:A1993JY02200001 ER PT J AU BILITZA, D RAWER, K BOSSY, L GULYAEVA, T AF BILITZA, D RAWER, K BOSSY, L GULYAEVA, T TI INTERNATIONAL REFERENCE IONOSPHERE - PAST, PRESENT, AND FUTURE .2. PLASMA TEMPERATURES, ION COMPOSITION AND ION DRIFT SO ADVANCES IN SPACE RESEARCH LA English DT Article ID ELECTRON-DENSITY; F-REGION; TERRESTRIAL IONOSPHERE; EMPIRICAL-MODEL; DISTRIBUTIONS; LATITUDES; EISCAT; MIDDLE; FIELD AB In December 1990 a new IRI handbook was published by NASA's National Space Science Data Center (NSSDC) describing in detail the International Reference Ionosphere 1990. Shortly thereafter, the IRI-90 software was released on tape, diskette, and computer networks. This paper is intended as an inventory of the most important IRI activities up to 1990 and as a starting point for the next improvement cycle. It summarizes the work and studies that led to IRI-90 and provides an overview over this latest version of the model. Shortcomings and limitations are pointed out and ways of overcoming them are discussed. Priorities are suggested for the list of work items that the IRI group has to tackle in the future. High on the wish-list are (i) major improvements at high latitudes and (ii) inclusion of magnetic storm effects. This paper deals with plasma temperatures, ion composition, and ion drift; the preceding companion paper discusses the electron density. C1 NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,GREENBELT,MD 20771. UNIV FREIBURG,W-7800 FREIBURG,GERMANY. INST TERR MAGNETISM IONOSPHERE & RADIO WAVE PROPAGAT,TROICK 142092,USSR. INST AERON SPATIALE BELGIQUE,B-1180 BRUSSELS,BELGIUM. NR 64 TC 12 Z9 12 U1 2 U2 6 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 MAR PY 1993 VL 13 IS 3 BP 15 EP 23 DI 10.1016/0273-1177(93)90241-3 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA JY022 UT WOS:A1993JY02200002 ER PT J AU GAT, E SLACK, M KAK, A CHIEN, S AF GAT, E SLACK, M KAK, A CHIEN, S TI APPLICATIONS OF AI TO REAL-WORLD AUTONOMOUS MOBILE ROBOTS SO AI MAGAZINE LA English DT Editorial Material C1 MITRE CORP,MCLEAN,VA 22101. PURDUE UNIV,W LAFAYETTE,IN 47907. RP GAT, E (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 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 SPR PY 1993 VL 14 IS 1 BP 10 EP 11 PG 2 WC Computer Science, Artificial Intelligence SC Computer Science GA KT084 UT WOS:A1993KT08400002 ER PT J AU KANT, E KELLER, R STEINBERG, S AF KANT, E KELLER, R STEINBERG, S TI INTELLIGENT SCIENTIFIC COMPUTATION SO AI MAGAZINE LA English DT Editorial Material C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV NEW MEXICO,ALBUQUERQUE,NM 87131. NR 0 TC 0 Z9 0 U1 0 U2 0 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 SPR PY 1993 VL 14 IS 1 BP 11 EP 12 PG 2 WC Computer Science, Artificial Intelligence SC Computer Science GA KT084 UT WOS:A1993KT08400004 ER PT J AU GAT, E AF GAT, E TI ON THE ROLE OF STORED INTERNAL STATE IN THE CONTROL OF AUTONOMOUS MOBILE ROBOTS SO AI MAGAZINE LA English DT Article AB This article informally examines the role of stored internal state (that is, memory) in the control of autonomous mobile robots. The difficulties associated with using stored internal state are reviewed. It is argued that the underlying cause of these problems is the implicit predictions contained within the state, and, therefore, many of the problems can be solved by taking care that the internal state contains information only about predictable aspects of the environment. One way of accomplishing this is to maintain internal state only at a high level of abstraction. The resulting information can be used to guide the actions of a robot but should not be used to control these actions directly; local sensor information is still necessary for immediate control. A mechanism to detect and recover from failures is also required. A control architecture embodying these design principles is briefly described. This architecture was successfully used to control real-world and simulated real-world autonomous mobile robots performing complex navigation tasks. The architecture is able to incorporate standard Al planning and world-modeling algorithms into a real-time situated framework. RP GAT, E (reprint author), JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 12 TC 7 Z9 7 U1 0 U2 0 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 SPR PY 1993 VL 14 IS 1 BP 64 EP 73 PG 10 WC Computer Science, Artificial Intelligence SC Computer Science GA KT084 UT WOS:A1993KT08400012 ER PT J AU MCKENZIE, RL AF MCKENZIE, RL TI PROGRESS IN LASER SPECTROSCOPIC TECHNIQUES FOR AERODYNAMIC MEASUREMENTS - AN OVERVIEW SO AIAA JOURNAL LA English DT Article ID TURBULENT NONPREMIXED FLAME; INDUCED IODINE FLUORESCENCE; INDUCED O-2 FLUORESCENCE; UV RAYLEIGH-SCATTERING; RAMAN-SCATTERING; GAS-FLOWS; DOPPLER VELOCIMETRY; SUPERSONIC FLOWS; AIR-FLOWS; VELOCITY RP MCKENZIE, RL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 113 TC 16 Z9 21 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 MAR PY 1993 VL 31 IS 3 BP 465 EP 477 DI 10.2514/3.11353 PG 13 WC Engineering, Aerospace SC Engineering GA KU606 UT WOS:A1993KU60600009 ER PT J AU CAVOLOWSKY, JA NEWFIELD, ME LOOMIS, MP AF CAVOLOWSKY, JA NEWFIELD, ME LOOMIS, MP TI LASER-ABSORPTION MEASUREMENTS OF OH CONCENTRATION AND TEMPERATURE IN PULSED FACILITIES SO AIAA JOURNAL LA English DT Article ID BAND AB A laser absorption flow diagnostic application has been developed at the NASA Ames 16-in. shock tunnel for purposes of measuring the thermochemical state of OH in flow environments of interest. Research objectives include the investigation of high-temperature, low-pressure chemistry pertinent to scramjet combustors and high altitude flight. The system can be operated in either the fixed frequency mode or in the rapid wavelength scanning mode to measure species mole fraction and temperature. Emission diagnostics have been employed to determine shock tunnel flow quality and assist in the proper application of the diagnostic and its data interpretation. Rotational lines in the OH A2SIGMA <-- X2PI (0,0) system were probed in the expanding facility nozzle flow and time-resolved measurements of temperature and mole fraction are provided. Facility test time was also measured using this technique. Discussion of diagnostic and operational uncertainties is included. C1 MCAT INST,SAN JOSE,CA 95127. RP CAVOLOWSKY, JA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 22 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 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 1993 VL 31 IS 3 BP 491 EP 498 DI 10.2514/3.11356 PG 8 WC Engineering, Aerospace SC Engineering GA KU606 UT WOS:A1993KU60600012 ER PT J AU CARTER, GA AF CARTER, GA TI RESPONSES OF LEAF SPECTRAL REFLECTANCE TO PLANT STRESS SO AMERICAN JOURNAL OF BOTANY LA English DT Article ID RED EDGE; PINE AB Leaf spectral reflectances were measured to determine whether leaf reflectance responses to plant stress may differ according to the agent of stress and species. As a result of decreased absorption by pigments, reflectance at visible wavelengths increased consistently in stressed leaves for eight stress agents and among six vascular plant species. Visible reflectance was most sensitive to stress in the 535-640-nm and 685-700-nm wavelength ranges. A sensitivity minimum occurred consistently near 670 nm. Infrared reflectance was comparatively unresponsive to stress, but increased at 1,400-2,500 nm with severe leaf dehydration and the accompanying decreased absorption by water. Thus visible rather than infrared reflectance was the most reliable indicator of plant stress. Visible reflectance responses to stress were spectrally similar among agents of stress and species. RP CARTER, GA (reprint author), NATL AERONAUT & SPACE ADM,SCI & TECHNOL LAB,BAY ST LOUIS,MS 39529, USA. NR 15 TC 266 Z9 292 U1 4 U2 46 PU BOTANICAL SOC AMER INC PI COLUMBUS PA OHIO STATE UNIV-DEPT BOTANY 1735 NEIL AVE, COLUMBUS, OH 43210 SN 0002-9122 J9 AM J BOT JI Am. J. Bot. PD MAR PY 1993 VL 80 IS 3 BP 239 EP 243 DI 10.2307/2445346 PG 5 WC Plant Sciences SC Plant Sciences GA KT073 UT WOS:A1993KT07300001 ER PT J AU OVRYN, B HAACKE, EM AF OVRYN, B HAACKE, EM TI TEMPORAL AVERAGING OF PHASE MEASUREMENTS IN THE PRESENCE OF SPURIOUS PHASE DRIFT - APPLICATION TO PHASE-STEPPED REAL-TIME HOLOGRAPHIC-INTERFEROMETRY SO APPLIED OPTICS LA English DT Article DE TEMPORAL AVERAGING; COMPENSATION; PHASE STEPPING; PHASE DRIFT; HOLOGRAPHIC INTERFEROMETRY ID SHIFTING INTERFEROMETRY; FIBER; ACCURACY; SYSTEM; AIR AB A technique that compensates for low spatial frequency spurious phase changes during an interference experiment is developed; it permits temporal averaging of multiple phase measurements, made before and after object displacement. The method is tested with phase-stepped real-time holographic interferometry applied to cantilever bending of a piezoelectric bimorph ceramic. Results indicate that temporal averaging of the corrected data significantly reduces the white noise in a phase measurement without incurring systematic errors or sacrificing spatial resolution. White noise is reduced from 3-degrees to less than 1-degrees (lambda/360) using these methods. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. CASE WESTERN RESERVE UNIV, DEPT BIOMED ENGN, CLEVELAND, OH 44106 USA. CASE WESTERN RESERVE UNIV, DEPT RADIOL, CLEVELAND, OH 44106 USA. CASE WESTERN RESERVE UNIV, DEPT PHYS & BIOMED ENGN, CLEVELAND, OH 44106 USA. NR 18 TC 1 Z9 1 U1 0 U2 1 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 MAR 1 PY 1993 VL 32 IS 7 BP 1087 EP 1094 PG 8 WC Optics SC Optics GA KP924 UT WOS:A1993KP92400008 PM 20820236 ER PT J AU BRANDT, JC HEAP, SR BEAVER, EA BOGGESS, A CARPENTER, KG EBBETS, DC HUTCHINGS, JB JURA, M LECKRONE, DS LINSKY, JL MARAN, SP SAVAGE, BD SMITH, AM TRAFTON, LM WALTER, FM WEYMANN, RJ SNOW, M RANDALL, CE LINDLER, DJ SHORE, SN MORRIS, SL GILLILAND, RL LU, L ROBINSON, RD AF BRANDT, JC HEAP, SR BEAVER, EA BOGGESS, A CARPENTER, KG EBBETS, DC HUTCHINGS, JB JURA, M LECKRONE, DS LINSKY, JL MARAN, SP SAVAGE, BD SMITH, AM TRAFTON, LM WALTER, FM WEYMANN, RJ SNOW, M RANDALL, CE LINDLER, DJ SHORE, SN MORRIS, SL GILLILAND, RL LU, L ROBINSON, RD TI OBSERVATIONS OF 3C-273 WITH THE GODDARD HIGH-RESOLUTION SPECTROGRAPH ON THE HUBBLE SPACE TELESCOPE SO ASTRONOMICAL JOURNAL LA English DT Article ID HALO AB The observations of the quasar 3C 273 taken with the Goddard High Resolution Spectrograph in 1991 February are presented here. We have included both the reduced raw data, and smoothed and deconvolved spectra. Also, a list of observed absorption lines is presented. The data comprise 11 spectra, including 1 low resolution observation and 10 medium resolution observations. The wavelength region covered ranged from about 1150 to 2820 angstrom, but was not all inclusive. The procedures used to obtain and reduce the data, including corrections for fixed pattern noise, compensation for the effects of spherical aberration in the HST primary mirror, and objective detection of weak absorption lines, are described. We also have included a short discussion on the detection of galactic Ni II and Virgo cluster metal lines. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,C-011,LA JOLLA,CA 92093. NASA,GODDARD SPACE FLIGHT CTR,CODE 440,GREENBELT,MD 20771. BALL AEROSP SYST GRP,BOULDER,CO 80306. DOMINION ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. NATL INST STAND & TECHNOL,DIV QUANTUM PHYS,BOULDER,CO 80309. UNIV COLORADO & NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 680,GREENBELT,MD 20771. UNIV WISCONSIN,DEPT AUGEN,MADISON,WI 53706. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. SUNY STONY BROOK,STONY BROOK,NY 11794. CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,CODE 681,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. RP BRANDT, JC (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. RI Morris, Simon/G-7981-2011; heap, sara/E-2237-2012; Carpenter, Kenneth/D-4740-2012; OI Morris, Simon/0000-0003-4866-110X; SNOW, MARTIN/0000-0001-9106-1332; RANDALL, CORA/0000-0002-4313-4397 NR 21 TC 21 Z9 21 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 MAR PY 1993 VL 105 IS 3 BP 831 EP 846 DI 10.1086/116475 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KQ553 UT WOS:A1993KQ55300006 ER PT J AU SURACE, JA MAZZARELLA, J SOIFER, BT WEHRLE, AE AF SURACE, JA MAZZARELLA, J SOIFER, BT WEHRLE, AE TI HIGH-RESOLUTION IRAS OBSERVATIONS OF INTERACTING SYSTEMS IN THE IRAS BRIGHT GALAXY SAMPLE SO ASTRONOMICAL JOURNAL LA English DT Article ID ULTRALUMINOUS INFRARED GALAXIES; MARKARIAN GALAXIES; GLOBAL PROPERTIES; SEYFERT-GALAXIES; MERGING GALAXIES; SPIRAL GALAXIES; STAR FORMATION; EMISSION; STARBURSTS; RADIO AB A sample of morphologically selected interacting galaxies has been chosen from the 60 mum flux density limited IRAS Bright Galaxy Sample [Soifer et al., ApJ, 320, 238 (1987)]. Using the HIRES algorithm [Aumann et al., AJ, 99, 1674 (1990)] and one-dimensional coaddition, the IRAS survey data for these galaxies were analyzed and the infrared fluxes at 12, 25, 60, and 100 mum for the resolved components have been determined where possible. Of the 56 potentially resolvable interacting groups, 22 systems have been resolved yielding fluxes for a total of 51 galaxies. In about 2/3 of the resolved pairs, both galaxies are bright in the infrared. A set of isolated noninteracting galaxies with a similar distribution of blue luminosities was chosen from the IRAS Bright Galaxy Sample for comparison with the interacting galaxies. For the current sample of interacting systems resolved by IRAS the primary conclusions are as follows: (a) It is not possible to distinguish individual interacting galaxies from isolated galaxies of similar blue luminosity on the basis of infrared properties alone. Interactions of the type sampled here do not, therefore, produce any unique IR signatures in individual galaxies. The relatively large intrinsic dispersion of normal galaxy properties is likely responsible for this fact. (b) No direct correlation was found between measures of interaction strength and indicators of enhanced star formation within the resolved systems. (c) Comparison of the interacting and isolated samples indicates substantial differences between their distributions of far-infrared color ratios, luminosities, and surface brightnesses. These differences can be attributed to the expected heating of the gas rich interstellar medium due to the triggering of starbursts in the interacting galaxies. Even during the early stages of interaction spanned by these systems, tidal perturbations appear to substantially boost far-infrared indicators of star formation compared to noninteracting systems. C1 CALTECH, JET PROPULS LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91125 USA. RP SURACE, JA (reprint author), CALTECH, DIV MATH PHYS & ASTRON, PASADENA, CA 91125 USA. NR 52 TC 43 Z9 43 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD MAR PY 1993 VL 105 IS 3 BP 864 EP 876 DI 10.1086/116478 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KQ553 UT WOS:A1993KQ55300009 ER PT J AU RUDY, RJ ROSSANO, GS ERWIN, P PUETTER, RC FEIBELMAN, WA AF RUDY, RJ ROSSANO, GS ERWIN, P PUETTER, RC FEIBELMAN, WA TI NEAR-INFRARED AND ULTRAVIOLET SPECTROPHOTOMETRY OF THE YOUNG PLANETARY-NEBULA HUBBLE-12 SO ASTRONOMICAL JOURNAL LA English DT Article ID MOLECULAR-HYDROGEN EMISSION; ORION NEBULA; LINE; SPECTROSCOPY; EXCITATION; SPECTRUM; OBJECTS; IC-4997; STARS AB In this paper we present spectrophotometry from 0.84-1.32 mum of the young planetary nebula Hubble 12. Archival IUE observations are rereduced and presented as well. Features of the infrared spectrum are catalogued and compared with those of other planetary nebula. Of these features the most peculiar is the brightness of the O I lines. O I lambda13164 is stronger in Hubble 12 than in any other planetary nebula yet measured. The presence of lambda13164 indicates that fluorescent excitation by the stellar continuum is the principal mechanism generating the O I lines. Their unusual strength probably results from the abundance of neutral material in the system. Fluorescently excited H-2 features, detected by Dinerstein et al [ApJ, 327, L27 (1988)] in measurements of the circumnebular neutral gas, are not apparent in our observations of the more central, ionized regions. The IR measurements are combined with the UV data and published optical observations to provide several independent determinations of the extinction, the electron density, and the electron temperature. Our best value for the extinction is E(B - V) =0.85, about 0.45 of which is probably interstellar in origin. The different emission lines indicate densities which range from a few thousand up to 10(6) cm-3 for the ionized regions, with values Up to 10(7) cm-3 being possible for the neutral zones. The [O III] lines indicate an electron temperature of less-than-or-equal-to 10 000 K, somewhat lower than the value suggested by the continuum emission from the ionized gas. The range in extinction, density, and temperature suggests that within the ionized region, pockets of emission with distinctly different conditions exist. The logarithmic abundances for helium, oxygen, and sulfur are found to be 11.11, 8.34, and 6.61, respectively. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP RUDY, RJ (reprint author), AEROSP CORP,CTR SPACE & ENVIRONM TECHNOL,M2-266,POB 92957,LOS ANGELES,CA 90009, USA. NR 38 TC 12 Z9 12 U1 0 U2 1 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 MAR PY 1993 VL 105 IS 3 BP 1002 EP 1009 DI 10.1086/116488 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KQ553 UT WOS:A1993KQ55300019 ER PT J AU DUTREY, A DUVERT, G CASTETS, A LANGER, WD BALLY, J WILSON, RW AF DUTREY, A DUVERT, G CASTETS, A LANGER, WD BALLY, J WILSON, RW TI A MULTITRANSITION STUDY OF CARBON-MONOXIDE IN THE ORION A MOLECULAR CLOUD .2. (CO)-O-18 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERSTELLAR MEDIUM, CLOUDS; HII REGION; MOLECULES; MILLIMETER LINES; RADIATION TRANSFER; SURVEYS ID INTER-STELLAR CLOUDS; FRAGMENTATION AB We present an analysis of density, temperature and excitation conditions in one half square degree region around BN/KL in Orion A using new (CO)-O-18 J = 1 --> 0 and J = 2 --> 1 data. This paper extends our previous study of Orion A, based on a multi-transition analysis of (CO)-C-13, to the optically thinner (CO)-O-18 species that traces better the dense inner regions of Giant molecular clouds. From the (CO)-O-18 maps we identify several condensations and are able to derive their size, linewidth, average density, mass and virial mass. C1 IRAM, F-38406 ST MARTIN DHERES, FRANCE. AT&T BELL LABS, HOLMDEL, NJ 07733 USA. JET PROP LAB, PASADENA, CA 91109 USA. RP DUTREY, A (reprint author), OBSERV GRENOBLE, BP 53X, F-38041 GRENOBLE, FRANCE. NR 20 TC 29 Z9 29 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 MAR PY 1993 VL 270 IS 1-2 BP 468 EP 476 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KU567 UT WOS:A1993KU56700051 ER PT J AU KONTIZAS, M KONTIZAS, E MICHALITSIANOS, AG AF KONTIZAS, M KONTIZAS, E MICHALITSIANOS, AG TI RADIAL-DISTRIBUTION OF METALLICITY IN THE LMC CLUSTER SYSTEMS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GALAXIES, STRUCTURE; STAR CLUSTERS, ABUNDANCES ID LARGE MAGELLANIC CLOUD; GLOBULAR-CLUSTERS; AGES; DISK AB New determinations of the deprojected distances to the galaxy centre for 94 star clusters and their metal abundances are used to investigate the variation of metallicity across the two LMC star cluster systems (Kontizas et al. 1990). A systematic radial trend of metallicity is observed in the extended outer cluster system, the outermost clusters being significantly metal poorer than the more central ones, with the exception of six clusters (which might lie out of the plane of the cluster system) out of 77. A radial metallicity gradient has been found, qualitatively comparable to that of the Milky Way for its system of the old disk clusters. If the six clusters are taken into consideration then the outer cluster system is well mixed up to 8 kpc. The spatial distribution of metallicities for the inner LMC cluster system, consisting of very young globulars does not show a systematic radial trend; they are all metal rich. C1 NATL OBSERV, INST ASTRON, GR-11810 ATHENS, GREECE. UNIV ATHENS, DEPT PHYS, ASTROPHYS ASTRON & MECH SECT, GR-15783 ZOGRAFOS, GREECE. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RI Kontizas, Evangelos/A-1969-2014 NR 33 TC 22 Z9 22 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 MAR PY 1993 VL 269 IS 1-2 BP 107 EP 110 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KR442 UT WOS:A1993KR44200015 ER PT J AU THE, PS PEREZ, MR DEWINTER, D VANDENANCKER, ME AF THE, PS PEREZ, MR DEWINTER, D VANDENANCKER, ME TI THE NEW BE-TYPE STAR-HD-147196 IN THE RHO-OPHIUCHI DARK CLOUD REGION SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS; ATMOSPHERES, STARS; EMISSION-LINE, BESTARS; EVOLUTION, STARS; PREMAIN SEQUENCE ID ANOMALOUS EXTINCTION LAW; STARS AB The newly discovered Halpha-emission line star, HD 147196, by Irvine (1990) was observed spectroscopically and photometrically at the ESO. Furthermore, high and low resolution IUE spectra were obtained at the NASA, Goddard Space Flight Center. From the examination of the data of this star, which is located in the direction of the rho Oph dark cloud, we report: 1) The finding of Irvine (1990) that this relatively bright star show its Halpha-line in emission has been confirmed, 2) Previous Halpha-surveys of the rho Oph star-forming region (Haro 1949, Hidajat 196 1) did not detect HD 147196 as an Halpha-emission star, meaning that it must recently be very active, and has perhaps transformed itself from a B-type star at shell phase to a Be-phase, 3) The Mg II h + k resonance lines are in absorption and they appear to be interstellar in nature, which means that either the abundance of Mg in the extended atmosphere of the star is low or that the shell is not extended enough to produce emission lines of Mg II, 4) Photometric observations of this B8 V type star do not show: a) any variations during at least the times (years) covered by our monitoring ([V] = 7.04m), b) excess of near-IR radiation in its spectral energy distribution (SED), up to the M-passband at 4.8 mum; this is a well known fact for late type Be stars. C1 NASA, GODDARD SPACE FLIGHT CTR, IUE OBSERV, GREENBELT, MD 20771 USA. RP THE, PS (reprint author), UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, KRUISLAAN 403, 1098 SJ AMSTERDAM, NETHERLANDS. NR 30 TC 1 Z9 1 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 MAR PY 1993 VL 269 IS 1-2 BP 181 EP 186 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KR442 UT WOS:A1993KR44200024 ER PT J AU HUBBARD, WB SICARDY, B MILES, R HOLLIS, AJ FORREST, RW NICOLSON, IKM APPLEBY, G BEISKER, W BITTNER, C BODE, HJ BRUNS, M DENZAU, H NEZEL, M RIEDEL, E STRUCKMANN, H ARLOT, JE ROQUES, F SEVRE, F THUILLOT, W HOFFMANN, M GEYER, EH BUIL, C COLAS, F LECACHEUX, J KLOTZ, A THOUVENOT, E VIDAL, JL CARREIRA, E ROSSI, F BLANCO, C CRISTALDI, S NEVO, Y REITSEMA, HJ BROSCH, N CERNIS, K ZDANAVICIUS, K WASSERMAN, LH HUNTEN, DM GAUTIER, D LELLOUCH, E YELLE, RV RIZK, B FLASAR, FM PORCO, CC TOUBLANC, D CORUGEDO, G AF HUBBARD, WB SICARDY, B MILES, R HOLLIS, AJ FORREST, RW NICOLSON, IKM APPLEBY, G BEISKER, W BITTNER, C BODE, HJ BRUNS, M DENZAU, H NEZEL, M RIEDEL, E STRUCKMANN, H ARLOT, JE ROQUES, F SEVRE, F THUILLOT, W HOFFMANN, M GEYER, EH BUIL, C COLAS, F LECACHEUX, J KLOTZ, A THOUVENOT, E VIDAL, JL CARREIRA, E ROSSI, F BLANCO, C CRISTALDI, S NEVO, Y REITSEMA, HJ BROSCH, N CERNIS, K ZDANAVICIUS, K WASSERMAN, LH HUNTEN, DM GAUTIER, D LELLOUCH, E YELLE, RV RIZK, B FLASAR, FM PORCO, CC TOUBLANC, D CORUGEDO, G TI THE OCCULTATION OF 28-SGR BY TITAN SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE TITAN; ATMOSPHERE; OCCULTATION ID UPPER-ATMOSPHERE; PLUTO ATMOSPHERE; MODELS; TEMPERATURE; SCATTERING AB We present a comprehensive analysis of data obtained during the 1989 July 3 occultation of 28 Sgr by Titan. The data set includes 23 lightcurves from 15 separate stations, spanning wavelengths from 0.36 mum to 0.89 mum. A detailed model of the structure of Titan's atmosphere in the altitude range 250 to 450 km is developed, giving the distribution of temperature, pressure, haze optical depth, and zonal wind velocity as a function of altitude and latitude. Haze layers detected in Titan's stratosphere are about one scale height higher than inferred from Voyager data, and show a wavelength dependence indicative of particle sizes on the order of 0.1 mum. A marked north-south dichotomy in haze density is observed, with a transition to lower density south of about -20-degrees latitude. Zonal wind speeds are inferred from global distortions from spherical symmetry, and are of the order of 100 m/s, with significant increase toward higher latitudes. Titan's high atmosphere shows substantial axial symmetry; the position angle of the symmetry axis is equal to the position angle of Saturn's spin axis to within approximately 1-degrees. C1 UNIV PARIS 06, OBSERV PARIS, F-92195 MEUDON, FRANCE. MANLEY OBSERV, MANLEY WA6 9DZ, CHESHIRE, ENGLAND. BRITISH ASTRON ASSOC, LONDON WIV 9AG, ENGLAND. UNIV HERTFORDSHIRE OBSERV, HERTFORD SG13 8LD, ENGLAND. ROYAL GREENWICH OBSERV, CAMBRIDGE CB3 0EZ, ENGLAND. IOTA, W-3000 HANNOVER 91, GERMANY. BUR LONGITUDES, F-75014 PARIS, FRANCE. INST ASTROPHYS PARIS, F-75014 PARIS, FRANCE. UNIV STERNWARTE BONN, OBSERV HOHER LIST, BONN, GERMANY. ASSOC TELESCOPE 60 CM, TOULOUSE, FRANCE. OBSERV PIC MIDI & TOULOUSE, F-65200 BAGNERES DE BIGORRE, FRANCE. SPECOLA VATICANA, VATICAN OBSERV RES GRP, I-00120 CITTA VATICANO, ITALY. KIBBUTZ EIN HAROD, IL-18965 MEUCHAD, ISRAEL. UNIV CATANIA, IST ASTRON, I-95125 CATANIA, ITALY. BALL AEROSP SYST DIV, BOULDER, CO 80306 USA. TEL AVIV UNIV, WISE OBSERV, IL-69978 TEL AVIV, ISRAEL. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. LOWELL OBSERV, FLAGSTAFF, AZ 86001 USA. OBSERV BORDEAUX, F-33270 FLOIRAC, FRANCE. UNIV ARIZONA, APPL MATH PROGRAM, TUCSON, AZ 85721 USA. VILNIUS THEORET PHYS & ASTRON, VILNIUS 2600, LITHUANIA. RP HUBBARD, WB (reprint author), UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. RI Brosch, Noah/C-7889-2009; Flasar, F Michael/C-8509-2012 NR 31 TC 109 Z9 110 U1 0 U2 3 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 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 1993 VL 269 IS 1-2 BP 541 EP 563 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KR442 UT WOS:A1993KR44200062 ER PT J AU ZDZIARSKI, AA ZYCKI, PT SVENSSON, R BOLDT, E AF ZDZIARSKI, AA ZYCKI, PT SVENSSON, R BOLDT, E TI ON COMPTON REFLECTION IN THE SOURCES OF THE COSMIC X-RAY-BACKGROUND SO ASTROPHYSICAL JOURNAL LA English DT Article DE DIFFUSE RADIATION; GALAXIES, ACTIVE; RADIATION MECHANISMS, MISCELLANEOUS; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; COLD MATTER; SPECTRUM AB The cosmic X-ray background exhibits a rather narrow peak at approximately 30 keV when plotted in intensity per logarithmic photon interval, EI(E). The position and the width of the peak are observationally well established. We reconsider recent models for the background that assume that it originates from unresolved AGNs emitting spectra due to enhanced Compton reflection of a power-law photon spectrum incident on cold matter. We emphasize the use of EI(E) when fitting the observed background as then the important features are clearly visible. Doing so, we find that previously published models do not fit the data, and, in particular, the position and the width of the X-ray peak are not correctly reproduced. To explain the origin of the discrepancies, we study the parameter space of the Compton reflection model and find that the allowed parameter space is severely constrained by physical and cosmological effects. In particular, for an incident power-law energy index alpha greater than or similar to 1, the X-ray peak in the observed spectrum from a population of AGNs is necessarily at an energy less than that of the observed peak. Thus, reflection models using alpha greater than or similar to 1 can be ruled out. We show two examples of improved fits to the X-ray background. In one, an as yet unobserved AGN population at high redshifts is responsible for the background, and in the other, the major contribution to the background comes from observed foreground AGNs. We find neither model can be made fully compatible with the X-ray background spectrum, and that the model spectra of the required foreground AGNs are different from the observed ones. We conclude that the Compton reflection models proposed so far do not provide a straightforward explanation of the X-ray background spectrum. We do not exclude, however, that more complex models with Compton reflection may still prove correct. C1 MIT,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,BALTIMORE,MD 21218. STOCKHOLM OBSERV,S-13336 SALTSJOBADEN,SWEDEN. RP ZDZIARSKI, AA (reprint author), NICHOLAS COPERNICUS ASTRON CTR,BARTYCKA 18,PL-00716 WARSAW,POLAND. NR 25 TC 18 Z9 18 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 MAR 1 PY 1993 VL 405 IS 1 BP 125 EP 129 DI 10.1086/172345 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP297 UT WOS:A1993KP29700009 ER PT J AU MARSHALL, FE NETZER, H ARNAUD, KA BOLDT, EA HOLT, SS JAHODA, KM KELLEY, R MUSHOTZKY, RF PETRE, R SERLEMITSOS, PJ SMALE, AP SWANK, JH SZYMKOWIAK, AE WEAVER, KA AF MARSHALL, FE NETZER, H ARNAUD, KA BOLDT, EA HOLT, SS JAHODA, KM KELLEY, R MUSHOTZKY, RF PETRE, R SERLEMITSOS, PJ SMALE, AP SWANK, JH SZYMKOWIAK, AE WEAVER, KA TI A NEW X-RAY SPECTRAL OBSERVATION OF NGC-1068 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-1068); GALAXIES, SEYFERT; RADIATION MECHANISMS, MISCELLANEOUS; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; THIN ACCRETION DISKS; NGC 1068; SEYFERT-2 GALAXIES; LINE REGIONS; COLD MATTER; EMISSION; REFLECTION AB The first moderate-resolution (FWHM approximately 100 eV) X-ray spectrum of a Seyfert 2 galaxy was obtained with the BBXRT experiment aboard Astro-1, The observed X-ray continuum of NGC 1068 from 0.3 to 10 keV is well fitted as the sum of two power-law spectra with no evidence for absorption intrinsic to the source. Strong Fe K emission lines with a total equivalent width of 2700 eV were detected due to iron less ionized than Fe xx and to iron more ionized than Fe XXIII. Unresolved Fe L lines with a total equivalent width of 340 eV were also seen. No evidence was seen for lines due to the recombination of highly ionized oxygen with an upper limit for the O Lyalpha emission line of 40 eV. The discovery of multiple Fe K and Fe L emission lines clearly indicates a broad range of ionization states for this gas. The X-ray emission from NGC 1068 is thought to be due to radiation from the obscured nucleus of the galaxy that is Compton-scattered by warm (T approximately 2 x 10(5) K) electrons above the obscuring material. We associate the cooler, less ionized Fe with the warm electrons producing the polarized optical light, and the hotter (T approximately 4 x 10(6) K), highly ionized Fe with a previously unseen component. The two components may share the same volume, or the hot component may be located closer to the nucleus. The X-ray emission from the two components is modeled for various geometries using a photoionization code that calculates the temperature and ionization state of the gas. We present models consistent with the X-ray, UV, and optical observations. Typical model parameters are a total Compton depth of a few percent, an inner boundary of the hot component of about 1 pc, and an inner boundary of the warm component of about 20 pc. All the successful models require that oxygen be underabundant compared with solar by a factor of at least 5, while Fe is most likely overabundant. We show that the observed optical and UV line strengths from the NLR are consistent with these abundances. C1 UNIV MARYLAND,BALTIMORE,MD 21201. RP MARSHALL, FE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Swank, Jean/F-2693-2012; Kelley, Richard/K-4474-2012 NR 43 TC 103 Z9 103 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 MAR 1 PY 1993 VL 405 IS 1 BP 168 EP 178 DI 10.1086/172350 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP297 UT WOS:A1993KP29700014 ER PT J AU MEIXNER, M TIELENS, AGGM AF MEIXNER, M TIELENS, AGGM TI MODELS OF CLUMPY PHOTODISSOCIATION REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, INTERSTELLAR, CONTINUUM; ISM, STRUCTURE; RADIATIVE TRANSFER ID FAR-INFRARED SPECTROSCOPY; ULTRAVIOLET-RADIATION; MOLECULAR CLOUDS; M17 SW; LINE; GAS; SUBMILLIMETER; ABUNDANCE; EMISSION; SILICON AB We investigate far-infrared (FIR) fine structure line and submillimeter line emissions important in the cooling of photodissociation regions (PDRs) as they would arise in clumpy regions. We have developed a simple model for clumpy PDRs consisting of two components, dense clumps (5 x 10(5), 10(6), or 10(7) cm-3) embedded in a less dense interclump medium (300 or 3000 cm-3). Both the clump and interclump gas is presumed to be heated, ionized, and dissociated by penetrating far-ultraviolet (FUV) (6 < hv < 13.6 eV) photons. Employing the two-component medium radiative transfer formalism of Boisse, we calculate the UV penetration into each model clumpy region. As previously noted by Boisse, the UV radiation penetrates further into the clumpy region (an order of magnitude or more in our cases) than a cloud in which the material is homogeneously distributed. Hence, PDR cooling line emission can be excited on these larger scales. With clump to interclump density contrasts of more than 100, the penetration depends primarily on the density of the interclump medium and less on the clump filling factor. The homogeneous PDR models of Tielens and Hollenbach are used to calculate the line intensities arising in the clumps and in the interclump medium which are assumed to be independent in velocity space. The line intensities are presented for two geometries: face-on and edge-on. In reality, molecular regions have a range of densities and density gradients. Our model incorporates only some of this complexity as a first attempt to study the effects of clumpiness on the resulting line emission and hence the reader should view the results in the paper as investigative. In light of this study, we review observational evidence for clumpy PDRs. In particular, the dense clumps present in this model are capable of reproducing the very high excitation lines (e.g., CO 14-13) and the lower density interclump gas produces the very extended (1-6 pc) [C I] and [C II] emission. In addition, the model suggests an explanation for the unusually high [Si II] (35 mum) intensity with respect to the [O I] (63 mum) intensity found in some PDRs. Most important, the model infers that some lines arise mostly from the interclump material ([C I], [C II], and lower CO transitions) while others are exclusively excited in the clumps ([O I], [Si II], and high CO transitions). This result differentiates our model from previous clumpy models of PDRs which assume that all emission arises from the clumps. C1 NASA,AMES RES CTR,DIV SPACE SCI MS 245-3,MOFFETT FIELD,CA 94035. RP MEIXNER, M (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720, USA. NR 27 TC 86 Z9 86 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1993 VL 405 IS 1 BP 216 EP 228 DI 10.1086/172355 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP297 UT WOS:A1993KP29700019 ER PT J AU LONG, KS BLAIR, WP BOWERS, CW DAVIDSEN, AF KRISS, GA SION, EM HUBENY, I AF LONG, KS BLAIR, WP BOWERS, CW DAVIDSEN, AF KRISS, GA SION, EM HUBENY, I TI OBSERVATIONS OF THE WHITE-DWARF IN THE U-GEMINORUM SYSTEM WITH THE HOPKINS ULTRAVIOLET TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (U-GEMINORUM); ULTRAVIOLET, STARS; WHITE DWARFS ID CATACLYSMIC VARIABLE-STARS; INTER-STELLAR EXTINCTION; NOVA VW-HYDRI; ACCRETION DISKS; BOUNDARY-LAYER; IUE OBSERVATIONS; URSAE-MAJORIS; HEII LINES; EVOLUTION; ATMOSPHERES AB We have used the Hopkins Ultraviolet Telescope to obtain a far-ultraviolet (830-1860 angstrom) spectrum of the dwarf nova U Geminorum. The spectrum, which was obtained 10 days after U Gem had returned to the low state following a normal outburst, shows prominent absorption features due to the Lyman series of hydrogen and the Balmer lines of He II, as well as weaker absorption lines due to metals, including C III lambda977, C III lambda1176, N v lambdalambda1239, 1243, Si IV lambdalambda1394, 1403, C IV lambdalambda1548, 1551, and possibly O VI lambdalambda1032, 1038. The continuum, which extends to the Lyman limit but not beyond, is dominated by emission from the white dwarf. The average surface temperature appears to have been approximately 38,000 K if all the UV light comes from the white dwarf This temperature is higher than the temperature derived from previous measurements with IUE obtained further from outburst. There is evidence for a hot (approximately 57,000 K) component in the continuum which may be due to the boundary-layer region of the white dwarf photosphere. There is no obvious evidence of UV emission from the accretion disk. A preliminary analysis of the strength of the absorption lines suggests that most of the lines, but not those from ions with the highest ionization potential, arise in the photosphere of the white dwarf, which has nearly solar surface composition due to accretion from the secondary companion. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CTR ASTROPHYS SCI,BALTIMORE,MD 21218. VILLANOVA UNIV,DEPT ASTRON & ASTROPHYS,VILLANOVA,PA 19085. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LONG, KS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 54 TC 46 Z9 46 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 MAR 1 PY 1993 VL 405 IS 1 BP 327 EP 336 DI 10.1086/172365 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP297 UT WOS:A1993KP29700029 ER PT J AU 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 PINKAU, K SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF 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 PINKAU, K SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI DETECTION OF GAMMA-RAY EMISSION FROM THE QUASAR PKS 0208-512 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GAMMA-RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL (PKS 0208; 512) ID RADIO-SOURCES; TELESCOPE AB High-energy gamma-ray emission has been detected from the quasar PKS 0208 - 512 in the energy range above 30 MeV by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory. This region of sky was observed in five different viewing periods, and evidence of time variability in the gamma-ray emission by more than a factor of 3 was found. At the maximum intensity between 1991 September 19 and October 3, the flux density above 100 MeV was (9.1 +/- 0.4) x 10(-7)gamma cm-2 s-1. The photon spectrum during this period may be expressed as a power law with an exponent of -1.69 +/- 0.05 between 30 MeV and 4 GeV. This is the hardest quasar spectrum observed by EGRET up to the present time. C1 MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. COMP SCI CORP,ASTRON PROGRAM,COMPTON OBSERV SCI SUPPORT CTR,LOS ANGELES,CA 90045. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP BERTSCH, DL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,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 30 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 MAR 1 PY 1993 VL 405 IS 1 BP L21 EP L24 DI 10.1086/186756 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP298 UT WOS:A1993KP29800006 ER PT J AU LEVENTHAL, M BARTHELMY, SD GEHRELS, N TEEGARDEN, BJ TUELLER, J BARTLETT, LM AF LEVENTHAL, M BARTHELMY, SD GEHRELS, N TEEGARDEN, BJ TUELLER, J BARTLETT, LM TI GRIS DETECTIONS OF THE 511 KEV LINE FROM THE GALACTIC-CENTER REGION IN 1992 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, CENTER; GAMMA-RAYS, OBSERVATIONS; LINE, PROFILES ID ANNIHILATION RADIATION; SOURCE 1E1740.7-2942; CENTER DIRECTION; SPECTRUM AB The Gamma Ray Imaging Spectrometer (GRIS) was flown on balloons over Alice Springs, Australia on 1992 April 26 and May 7. A full Galactic center transit (approximately 12 hr) was achieved on both flights with the instrument working normally. The electron/positron annihilation line was detected on both flights. The line fluxes and line widths were found to be (7.7 +/- 1.2) x 10(-4) and (8.9 +/- 1.1) x 10(-4) photons cm-2 s-1 and 1.3 +/- 0.7 and 3.6 +/- 1.0 keV, respectively. These results are compared to each other and earlier (1988) GRIS results to produce suggestive evidence for source variability. Near-contemporaneous OSSE/CGRO Galactic center observations indicate that the GRIS results cannot be due solely to a single point source like 1E 1740.7-2942 within a few degrees of the Galactic center. The GRIS 1992 results represent the first time that successive high-resolution balloon measurements have been achieved on a time scale of days. C1 UNIV MARYLAND,COLL PK,MD 20742. RP LEVENTHAL, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012; Barthelmy, Scott/D-2943-2012 NR 26 TC 33 Z9 33 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 MAR 1 PY 1993 VL 405 IS 1 BP L25 EP L28 DI 10.1086/186757 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP298 UT WOS:A1993KP29800007 ER PT J AU LONSDALE, CJ SMITH, HE LONSDALE, CJ AF LONSDALE, CJ SMITH, HE LONSDALE, CJ TI THE STARBURST-AGN CONNECTION - A SENSITIVE VLBI SURVEY OF LUMINOUS IRAS GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; INFRARED, GALAXIES; RADIO CONTINUUM, GALAXIES ID ULTRALUMINOUS INFRARED GALAXIES; ACTIVE GALACTIC NUCLEI; RADIO; EMISSION; SAMPLE AB Results of an 18 cm VLBI survey of 31 luminous (L(fir) > 1-(11.25) L.), radio-compact (theta less-than-or-similar-to 0.''25) infrared galaxies are presented. Over half the sample galaxies show high-brightness temperature emission, with T(b) > 10(5) K and structure on scales of 5-150 mas. The median VLBI core power for detected sources is log P(core) = 22.0 (W Hz-1), and the ratio of core to total 1.6 GHz flux density = 0.12. The limits for nondetected sources are similar, consistent with a picture in which most of these galaxies have compact cores at a level of a few percent of the total radio flux density. Characteristics of the extended radio structure, infrared properties, and optical excitation are not good indicators of the detectability of VLBI-scale emission. Structural information and energetic considerations rule out a single supernova interpretation of the compact emission in these galaxies, although we cannot exclude the possibility of several simultaneous extraordinarily luminous radio supernovae within the central few hundred pc3. Our results instead favor the presence of an AGN obscured by starburst-related dust. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. RP LONSDALE, CJ (reprint author), MIT,HAYSTACK OBSERV,ROUTE 40,WESTFORD,MA 01886, USA. NR 18 TC 73 Z9 73 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 MAR 1 PY 1993 VL 405 IS 1 BP L9 EP L12 DI 10.1086/186753 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP298 UT WOS:A1993KP29800003 ER PT J AU MAZZARELLA, JM BOROSON, TA AF MAZZARELLA, JM BOROSON, TA TI OPTICAL IMAGING AND LONG-SLIT SPECTROSCOPY OF MARKARIAN GALAXIES WITH MULTIPLE NUCLEI .1. BASIC DATA SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GALAXIES, INTERACTIONS; GALAXIES, NUCLEI; GALAXIES, PHOTOMETRY; GALAXIES, STARBURST ID INTERACTING GALAXIES; SEYFERT-GALAXIES; STAR-FORMATION; COMPANIONS; CATALOG AB Optical CCD images and long-slit spectroscopic data are presented for over 100 Markarian (UV-excess)galaxies reported in early studies to possess multiple optical nuclei or extreme morphological peculiarities suggestive of galaxy collisions and mergers. Stacked broad-band (BVR) images are presented with histogram equalization in order to show simultaneously the nuclei and features at very low surface-brightness levels. Morphological properties, luminosities and colors of the integral systems are given. Photometric and image properties of over 200 individual nuclei and giant H II regions have been measured with respect to the local backgrounds in the galaxies using an objective image finding algorithm. Labeled contour plots identify the measured subcomponents. Two-dimensional spectral data are presented, in addition to intensity profiles along the slit in the light of Halpha + [N II] emission lines and adjacent continuum. Nuclear emission-line measurements (4500-7500 angstrom, almost-equal-to 10 angstrom FWHM resolution), reddening estimates, monochromatic continuum magnitudes, and colors are given. Interpretation of these data with emphasis on the confirmed interacting and merging galaxies is presented in a subsequent paper. C1 CALTECH,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. NATL OPT ASTRON OBSERV,KITT PEAK NATL OBSERV,TUCSON,AZ 85726. RP MAZZARELLA, JM (reprint author), JET PROP LAB,CTR INFRARED PROC & ANAL,100-22,PASADENA,CA 91109, USA. NR 68 TC 148 Z9 148 U1 0 U2 1 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 MAR PY 1993 VL 85 IS 1 BP 27 EP 109 DI 10.1086/191754 PG 83 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KM956 UT WOS:A1993KM95600002 ER PT J AU GREEN, S MALUENDES, S MCLEAN, AD AF GREEN, S MALUENDES, S MCLEAN, AD TI IMPROVED COLLISIONAL EXCITATION RATES FOR INTERSTELLAR WATER SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE MOLECULAR DATA; MOLECULAR PROCESSES ID H2O; SCATTERING; TRANSITION; MOLECULES; CLOUDS AB Theoretical rate constants among the lowest 45 para and 45 ortho rotational levels of water in collisions with He atoms have been calculated for temperatures between 20 and 2000 K using a recently improved theoretical interaction potential. These values are about 30%-40% larger than those reported previously (Palma et al. 1988b) but relative sizes of different state-to-state rates have not changed significantly. Successive improvements to the theoretical description of this system now appear to have converged. C1 MOLEC RES INST,PALO ALTO,CA 94304. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 16 TC 129 Z9 129 U1 0 U2 5 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 MAR PY 1993 VL 85 IS 1 BP 181 EP 185 DI 10.1086/191760 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KM956 UT WOS:A1993KM95600008 PM 11537853 ER PT J AU KO, MKW SZE, ND MOLNAR, G PRATHER, MJ AF KO, MKW SZE, ND MOLNAR, G PRATHER, MJ TI GLOBAL WARMING FROM CHLOROFLUOROCARBONS AND THEIR ALTERNATIVES - TIME SCALES OF CHEMISTRY AND CLIMATE SO ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS LA English DT Article DE GREENHOUSE WARMING; GLOBAL WARMING POTENTIAL; HALOCARBONS; CFC SUBSTITUTES ID TRACE GASES; GREENHOUSE; CO2; ATMOSPHERE AB The halocarbons (chlorofluorocarbons, CFCs, and their replacement chemicals: the hydrochlorofluorocarbons, HCFCs, and the hydrofluorocarbons, HFCs) are greenhouse gases. The atmospheric accumulation of these gases is expected to add to the global warming predicted for expected increases of CO2, CH4, N2O, tropospheric ozone and H2O. Over the next decades, production of CFCs is scheduled to be phased out, while emissions of their alternatives are expected to increase. A simple model is used to illustrate the methodology for determining the time variations of the radiative forcing and temperature changes attributable to the direct greenhouse effect from potential emissions of the halocarbons. Although there are uncertainties associated with the lifetimes of the greenhouse gases, CFCs and their substitutes, the future growth rates of these gases, and the parameters used to simulate the response of the Earth-climate system, the method serves to illustrate an important aspect of the greenhouse warming issue beyond what is provided by the various greenhouse warming indices. Our results show that for likely substitution scenarios, the warming due to halocarbons will correspond to 4-10% of the total expected greenhouse warming at the year 2100. However, uncontrolled growth of the substitutes could result in an eight-fold increase in halocarbon production and a doubling of the halocarbon contribution by 2100. C1 NASA HEADQUARTERS,WASHINGTON,DC 20546. RP KO, MKW (reprint author), ATMOSPHER & ENVIRONM RES INC,840 MEM DR,CAMBRIDGE,MA 01730, USA. NR 33 TC 12 Z9 12 U1 5 U2 15 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 MAR PY 1993 VL 27 IS 4 BP 581 EP 587 DI 10.1016/0960-1686(93)90215-K PG 7 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA KU201 UT WOS:A1993KU20100012 ER PT J AU BHATIA, AK DOSCHEK, GA AF BHATIA, AK DOSCHEK, GA TI ATOMIC DATA AND SPECTRAL-LINE INTENSITIES FOR C-LIKE CA(XV) SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID CROSS-SECTIONS 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 8 TC 24 Z9 24 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 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD MAR PY 1993 VL 53 IS 2 BP 195 EP 232 DI 10.1006/adnd.1993.1005 PG 38 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA KZ271 UT WOS:A1993KZ27100002 ER PT J AU KYRIAKOPOULOS, KJ SARIDIS, GN AF KYRIAKOPOULOS, KJ SARIDIS, GN TI AN INTEGRATED COLLISION PREDICTION AND AVOIDANCE SCHEME FOR MOBILE ROBOTS IN NONSTATIONARY ENVIRONMENTS SO AUTOMATICA LA English DT Article DE MOBILE ROBOTS; MOTION PLANNING; COLLISION PREDICTION; COLLISION AVOIDANCE; POTENTIAL FUNCTIONS; LYAPUNOV STABILITY AB A formulation that makes possible the integration of collision prediction and avoidance stages for mobile robots moving in general terrains containing moving obstacles is presented. A dynamic model of the mobile robot and the dynamic constraints are derived. Collision avoidance is guaranteed if the distance between the robot and a moving obstacle is nonzero. A nominal trajectory is assumed to be known from off-line planning. The main idea is to change the velocity along the nominal trajectory so that collisions are avoided. A feedback control is developed and local asymptotic stability is proved if the velocity of the moving obstacle is bounded. Furthermore, a solution to the problem of inverse dynamics for the mobile robot is given. Simulation results verify the value of the proposed strategy. C1 RENSSELAER POLYTECH INST,NASA,CTR INTELLIGENT ROBOT SYST SPACE EXPLORAT,TROY,NY 12180. RP KYRIAKOPOULOS, KJ (reprint author), RENSSELAER POLYTECH INST,NEW YORK STATE CTR ADV TECHNOL AUTOMAT & ROBOT,TROY,NY 12180, USA. NR 23 TC 18 Z9 18 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0005-1098 J9 AUTOMATICA JI Automatica PD MAR PY 1993 VL 29 IS 2 BP 309 EP 322 DI 10.1016/0005-1098(93)90125-D PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA KU192 UT WOS:A1993KU19200004 ER PT J AU GANDER, PH NGUYEN, D ROSEKIND, MR CONNELL, LJ AF GANDER, PH NGUYEN, D ROSEKIND, MR CONNELL, LJ TI AGE, CIRCADIAN-RHYTHMS, AND SLEEP LOSS IN FLIGHT CREWS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID TEMPERATURE; CHRONOBIOLOGY; WORK AB Age-related changes in trip-induced sleep loss, personality (n = 205), and the pre-duty temperature rhythm (n = 91) were analyzed in crews from various flight operations. Eveningness decreased with age (subjects aged 20-30 were more evening-type than subjects over 40). The minimum of the baseline temperature rhythm occurred earlier with age (earlier in subjects aged 30-50 than in subjects aged 20-30). The amplitude of the baseline temperature rhythm declined with age (greater in subjects aged 20-30 than in subjects over 40). Average daily percentage sleep loss during trips increased with age. Among crewmembers flying longhaul flight operations, subjects aged 50-60 averaged 3.5 times more sleep loss per day than subjects aged 20-30. These studies support previous findings that evening types and subjects with later peaking temperature rhythms adapt better to shift work and time zone changes. Age and circadian type may be important considerations for duty schedules and fatigue countermeasures. RP GANDER, PH (reprint author), NASA,AMES RES CTR,SAN JOSE STATE UNIV FDN,FLIGHT HUMAN FACTORS BRANCH,MS 262-4,MOFFETT FIELD,CA 94035, USA. NR 35 TC 40 Z9 40 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 MAR PY 1993 VL 64 IS 3 BP 189 EP 195 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA KQ755 UT WOS:A1993KQ75500001 PM 8447798 ER PT J AU SANTY, PA HOLLAND, AW LOOPER, L MARCONDESNORTH, R AF SANTY, PA HOLLAND, AW LOOPER, L MARCONDESNORTH, R TI MULTICULTURAL FACTORS IN THE SPACE ENVIRONMENT - RESULTS OF AN INTERNATIONAL SHUTTLE CREW DEBRIEF SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB There is increasing interest and concern about the multicultural and multinational factors which might negatively affect adjustment and performance of Space Station Freedom (SSF) crews, living and working for long periods of time in the space environment. To begin identifying potential problem areas, a crew debrief questionnaire (called an ''International Crew Debrief'') was mailed to U.S. astronauts who flew on Shuttle missions between 1981-1990 with one or more crewmembers from other countries. There were 20 U.S. astronauts who flew on international space missions; 9 of these responded to the questionnaire, for a return rate of 45%. There were 42 incidents reported: 9 in the preflight period; 26 inflight; and 7 in the postflight period. Most of these incidents were rated as having a low or medium impact, but five of the inflight incidents were rated to have a ''high'' mission impact. A number of causes for the problems were listed, and are discussed. Debrief respondents provided useful and timely recommendations on preflight training which may help facilitate the integration of multinational crews, and prevent multicultural or multinational factors from interfering with mission operations. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX. UNIV SPACE RES ASSOC,HOUSTON,TX. RP SANTY, PA (reprint author), UNIV TEXAS,MED BRANCH,DEPT PSYCHIAT & BEHAV SCI,GALVESTON,TX 77550, USA. NR 11 TC 28 Z9 28 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 MAR PY 1993 VL 64 IS 3 BP 196 EP 200 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA KQ755 UT WOS:A1993KQ75500002 PM 8447799 ER PT J AU DAVIS, JR JENNINGS, RT BECK, BG BAGIAN, JP AF DAVIS, JR JENNINGS, RT BECK, BG BAGIAN, JP TI TREATMENT EFFICACY OF INTRAMUSCULAR PROMETHAZINE FOR SPACE MOTION SICKNESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID PERFORMANCE; FLIGHTS AB Intramuscular promethazine and its efficacy in the treatment of Space Motion Sickness (SMS) were evaluated using standardized questions administered during postflight debriefings to crewmembers immediately after their first Shuttle flight. Space Motion Sickness was graded as none, mild, moderate, or severe, based on published criteria. Immediate symptom relief (within 1-2 h) was evaluated by subjective reports; medication efficacy was based on scores derived from the four most frequently reported symptoms of SMS: nausea, vomiting, loss of appetite, and stomach awareness. Scores were given for each symptom, mild = 1, moderate = 2, and severe = 3, and added for a total score for each flight day. Following intramuscular (IM) promethazine on flight day 1, the scores were used to determine if the crewmembers were ''sick'' or ''not sick'' on flight day 2. On the basis of the scoring criteria, any subject with a score adding to greater than three, with any severe symptom, or with vomiting was defined as ''sick.'' The comparison showed that 25% of crewmembers treated with IM promethazine were ''sick'' on flight day 2, compared to 50% of crewmembers who did not receive promethazine (p = 0.046). Of crewmembers treated with IM promethazine, 90% reported immediate symptom relief as well. Untreated crewmembers typically have slow symptom resolution over 72-96 h, and those treated with oral scopolamine/dextroamphetamine show delayed symptom development. This study suggests that intramuscular promethazine is an effective treatment for SMS and merits continued use and further controlled investigations. C1 NASA,LYNDON B JOHNSON SPACE CTR,MED OPERAT BRANCH,MAIL CODE SD2,HOUSTON,TX 77058. NR 19 TC 25 Z9 26 U1 0 U2 1 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 MAR PY 1993 VL 64 IS 3 BP 230 EP 233 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA KQ755 UT WOS:A1993KQ75500008 PM 8447805 ER PT J AU BISHOP, PA GREENISEN, M AF BISHOP, PA GREENISEN, M TI LIMITATIONS TO THE STUDY OF MAN IN SPACE IN THE UNITED-STATES SPACE PROGRAM SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note AB Research on humans conducted during spaceflight is fraught both with great opportunities and great obstacles. The purpose of this paper is to review some of the limitations to research in space in the United States with hope that an informed scientific community may lead to more rapid and efficient solution of these problems. Limitations arise because opportunities to study the some astronauts in well-controlled situations on repeated spaceflights are practically non-existent. Human research opportunities are further limited by the necessity of avoiding simultaneous mutually-interfering experiments. Environmental factors, including diet and other physiological perturbations concomitant with spaceflight, also complicate research design and interpretation. Technical limitations to research methods and opportunities further restrict the development of the knowledge base. Finally, Earth analogues of space travel all suffer from inadequacies. Though all of these obstacles will eventually be overcome, creativity, diligence, and persistence are required to further our knowledge of humans in space. C1 NASA,LYNDON B JOHNSON SPACE CTR,EXERCISE COUNTERMEASURES PROJECT,HOUSTON,TX 77058. UNIV ALABAMA,TUSCALOOSA,AL 35401. NR 15 TC 4 Z9 4 U1 0 U2 1 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 MAR PY 1993 VL 64 IS 3 BP 238 EP 242 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA KQ755 UT WOS:A1993KQ75500011 PM 8447808 ER PT J AU CHOU, SH AF CHOU, SH TI A COMPARISON OF AIRBORNE EDDY-CORRELATION AND BULK AERODYNAMIC METHODS FOR OCEAN-AIR TURBULENT FLUXES DURING COLD-AIR OUTBREAKS SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID ATMOSPHERIC SURFACE-LAYER; BOUNDARY-LAYER; GRADIENT RELATIONSHIPS; AIRCRAFT MEASUREMENTS; DRAG COEFFICIENTS; MOMENTUM FLUX; WIND-STRESS; HEAT-FLUX; INTERFACE; PARAMETERIZATION AB Four bulk schemes (LKB, FG, D and DB), with the flux-profile relationships of Liu et al. (1979). Francey and Garratt (1981), Dyer (1974), and Dyer and Bradley (1982), are derived from the viscous interfacial-sublayer model of Liu et al. These schemes, with stability-dependent transfer coefficients. are then tested against the eddy-correlation fluxes measured at the 50 m flight level above the western Atlantic Ocean during cold-air outbreaks. The bulk fluxes of momentum (tau), sensible heat (H). and latent heat (E) are found to increase with various von Karman constants (k(M) for tau, k(H) for H. and k(E) for E). Except that the LKB scheme overestimates by 28% (46 W m-2), on the average, the fluxes estimated by the four bulk schemes appear to be in fairly good agreement with those of the eddy correlation method (magnitudes of biases within 10% for tau, 17% for H, and 13% for E). The results suggest that the overall fluxes and surface-layer scaling parameters are best estimated by FG and that k(H) < k(E). On the average, the FG scheme underestimates tau by 10% (0.032 N m-2) and E by 4% (12 W m-2), and overestimates H by 0.3% (0.5 W m-2). The equivalent neutral transfer coefficients at 10 m height of the FG scheme compare well with some schemes of those tested by Blanc (1985). The relative importance of various von Karman constants, dimensionless gradients and roughness lengths to the oceanic transfer coefficients is assessed. The dependence of transfer coefficients on wind speeds and roughness lengths is discussed. The transfer coefficients for tau and E agree excellently between LKB and FG. However, the ratio of the coefficient for H of LKB to that of FG, increasing with decreasing stability, is very sensitive to stability at low winds, but approaches the neutral value of 1.25 at high winds. RP NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 912, GREENBELT, MD 20771 USA. NR 45 TC 34 Z9 38 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0006-8314 EI 1573-1472 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD MAR PY 1993 VL 64 IS 1-2 BP 75 EP 100 DI 10.1007/BF00705663 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KW913 UT WOS:A1993KW91300004 ER PT J AU HIRUKI, LM GILMARTIN, WG BECKER, BL STIRLING, I AF HIRUKI, LM GILMARTIN, WG BECKER, BL STIRLING, I TI WOUNDING IN HAWAIIAN MONK SEALS (MONACHUS-SCHAUINSLANDI) SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID NORTHERN ELEPHANT SEALS; REPRODUCTIVE-BEHAVIOR; SHARK PREDATION; MATING-BEHAVIOR; TAIL AUTOTOMY; ENCOUNTERS; FREQUENCY; SUCCESS AB Injuries observed on endangered Hawaiian monk seals (Monachus schauinslandi) at Laysan Island and French Frigate Shoals in the northwestern Hawaiian Islands in 1988 and 1989 were classified into six major types, based on the source of the wounds: mating attempts by adult male monk seals; nonmating aggressive interactions with other seals; attacks by large sharks; attacks by cookiecutter sharks (Isistius brasiliensis); contact with coral reef or debris; and entanglement in netting or marine debris. At both locations, injuries inflicted by adult male seals during mobbing incidents, in which many males attempt to mate with one seal, were seen more frequently than other types of injuries in 1988 and 1989. Injury data from 1982 - 1987 at Laysan Island and from 1985 - 1989 at French Frigate Shoals were used to compare the distribution of mating injuries inflicted by adult males and injuries inflicted by large sharks over size and sex classes of seals. Mating injuries caused by adult male seals were seen primarily on adult females but were also seen on seals in other size classes. Mating injuries inflicted by adult males occurred earlier in the year and with greater frequency at Laysan Island than at French Frigate Shoals. Injuries inflicted by large sharks were observed more often on adult male seals than on seals in other size classes at Laysan Island; however, no such difference was seen among size classes at French Frigate Shoals. C1 UNIV ALBERTA,DEPT ZOOL,EDMONTON T6G 2E9,ALBERTA,CANADA. CANADIAN WILDLIFE SERV,EDMONTON T6H 3S5,AB,CANADA. RP HIRUKI, LM (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 61 TC 30 Z9 32 U1 2 U2 14 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD MAR PY 1993 VL 71 IS 3 BP 458 EP 468 DI 10.1139/z93-066 PG 11 WC Zoology SC Zoology GA KX258 UT WOS:A1993KX25800003 ER PT J AU HIRUKI, LM STIRLING, I GILMARTIN, WG JOHANOS, TC BECKER, BL AF HIRUKI, LM STIRLING, I GILMARTIN, WG JOHANOS, TC BECKER, BL TI SIGNIFICANCE OF WOUNDING TO FEMALE REPRODUCTIVE SUCCESS IN HAWAIIAN MONK SEALS (MONACHUS-SCHAUINSLANDI) AT LAYSAN ISLAND SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID NORTHERN ELEPHANT SEAL; HALICHOERUS-GRYPUS; GREY SEAL; MASS-LOSS; ENERGETICS; HARP; PUPS; LACTATION; DYNAMICS AB We studied reproductive rate, length of lactation period, pup survival, and mortality of injured and uninjured female Hawaiian monk seals (Monachus schauinslandi) on Laysan Island, northwestern Hawaiian Islands, in 1983-1989. The severity and timing of nonfatal injuries were influential in determining their effect on female reproductive success. There was a tendency towards a shorter mean lactation period and lower survival rate of pups for females with major injuries than for uninjured females. Females with minor injuries were similar to uninjured females in terms of reproductive rate, length of lactation, and pup survival. For females injured shortly before the birth of their pup or during lactation, pup survival was lower than for uninjured females, whereas for females injured during the year prior to pupping, measures of reproductive success were not significantly different from those for uninjured females. Immature (aged 4-8 years) females entering the reproductive population were injured by adult male seals significantly more often than females aged 0-3 years, but at a similar rate to adult females. The major effect of injuries on female reproductive success is an increase in female mortality: 87.5% of the adult females (n = 16) that died on Laysan Island in 1983-1989 sustained injuries from adult male seals. C1 UNIV ALBERTA,DEPT ZOOL,EDMONTON T6G 2E9,ALBERTA,CANADA. RP HIRUKI, LM (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 35 TC 30 Z9 34 U1 1 U2 4 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD MAR PY 1993 VL 71 IS 3 BP 469 EP 474 DI 10.1139/z93-067 PG 6 WC Zoology SC Zoology GA KX258 UT WOS:A1993KX25800004 ER PT J AU MARENGO, JA DRUYAN, LM HASTENRATH, S AF MARENGO, JA DRUYAN, LM HASTENRATH, S TI OBSERVATIONAL AND MODELING STUDIES OF AMAZONIA INTERANNUAL CLIMATE VARIABILITY SO CLIMATIC CHANGE LA English DT Article ID TROPICAL ATLANTIC; SOUTHERN OSCILLATION; NORTHEAST BRAZIL; CIRCULATION; ANOMALIES; RAINFALL; OCEAN; DEFORESTATION; IMPACT AB The interannual variability of climate in the Amazon basin is studied using precipitation and river level anomalies observed near the March/April rainy season peak for the period 1980-86, supported by satellite imagery of tropical convection. Evaluation of this data in conjunction with the corresponding circulation and sea-surface temperature (SST) anomaly patterns indicates that abundant rainy seasons in Northern Amazonia are characterized by anomalously cold surface waters in the tropical eastern Pacific, and negative/positive SST anomalies in the tropical North/South Atlantic, accelerated Northeast trades and a southward displaced Intertropical Convergence Zone (ITCZ) over the Atlantic sector. Years with deficient rainfall show broadly opposite patterns. General circulation model (GCM) experiments using observed SSF in three case studies were aimed at testing the teleconnections between SST and Amazon climate implied by the empirical analysis. The GCM-generated surface fields resemble the corresponding observers fields most closely over the tropical Pacific and, with one exception, over the tropical Atlantic as well. The modeled precipitation features, along the Northwest coast of South America, anomalies of opposite sign to the North and South of the equator, in agreement with observations and results from a different GCM. Similarities in simulations run from different initial conditions, but using the same global SST, indicate broad consistency in response to common boundary forcing. C1 COLUMBIA UNIV,NEW YORK,NY 10027. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP MARENGO, JA (reprint author), NASA,NATL RES COUNCIL,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI Marengo, Jose /J-9382-2012 OI Marengo, Jose /0000-0002-8154-2762 NR 38 TC 33 Z9 35 U1 0 U2 3 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 MAR PY 1993 VL 23 IS 3 BP 267 EP 286 DI 10.1007/BF01091619 PG 20 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA KT756 UT WOS:A1993KT75600005 ER PT J AU NOOR, AK ANDERSEN, CM PETERS, JM AF NOOR, AK ANDERSEN, CM PETERS, JM TI REDUCED BASIS TECHNIQUE FOR NONLINEAR VIBRATION ANALYSIS OF COMPOSITE PANELS SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID FLEXURAL VIBRATIONS; RECTANGULAR-PLATES; ORTHOTROPIC PLATES; SHEAR DEFORMATION; REDUCTION METHODS; ROTATORY INERTIA; LARGE-DEFLECTION; IMPERFECT AB A reduced basis technique and a computational procedure are presented for the nonlinear free vibrations of composite panels. The computational procedure can be conveniently divided into two distinct steps. The first step involves the generation of various-order perturbation vectors using Linstedt-Poincare perturbation technique. The second step consists of using the perturbation vectors as basis vectors, computing the amplitudes of these vectors, and the nonlinear frequency of vibration, via a direct variational procedure. The analytical formulation is based on a form of the geometrically nonlinear shallow shell theory with the effects of transverse shear deformation, rotatory inertia and anisotropic material behavior included. The panel is discretized by using mixed finite element models with the fundamental unknowns consisting of both the nodal displacements and the stress-resultant parameters of the panel. The potential of the proposed technique is discussed and its effectiveness is demonstrated by means of numerical examples. C1 COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMP STRUCT TECHNOL,HAMPTON,VA 23681, USA. NR 39 TC 11 Z9 11 U1 0 U2 2 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0045-7825 J9 COMPUT METHOD APPL M JI Comput. Meth. Appl. Mech. Eng. PD MAR PY 1993 VL 103 IS 1-2 BP 175 EP 186 DI 10.1016/0045-7825(93)90045-Y PG 12 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA KV169 UT WOS:A1993KV16900008 ER PT J AU KENNEDY, AK LOFGREN, GE WASSERBURG, GJ AF KENNEDY, AK LOFGREN, GE WASSERBURG, GJ TI AN EXPERIMENTAL-STUDY OF TRACE-ELEMENT PARTITIONING BETWEEN OLIVINE, ORTHO-PYROXENE AND MELT IN CHONDRULES - EQUILIBRIUM VALUES AND KINETIC EFFECTS SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID DYNAMIC CRYSTALLIZATION; ION-MICROPROBE; FRACTIONATION; PHENOCRYSTS; REE; CHONDRITES; TEXTURES; PROBE; MAGMA AB The concentrations of 32 elements (major, minor, REE, Ba, Hf, Sc, V, Co, Ni, Sr, Y, Zr, Nb, Ge, Th and U) were measured using an ion microprobe in olivine and orthopyroxene, and in coexisting glass in the run products produced in isothermal and dynamic crystallization experiments on chemical compositions that produce porphyritic olivine, radial pyroxene and barred olivine textures. Cooling rates in the dynamic crystallization experiments ranged from 1-degrees-C/h to 2191-degrees-C/h. The mineral/melt partition coefficients (D) calculated from the measured concentrations for both olivine and orthopyroxene showed very little change between equilibrium experiments and dynamic experiments with cooling rates of up to 100-degrees-C/h. The data appear to define reliable equilibrium D values. Olivine D's range from 2 x 10(-5) for U to approximately 10 for Ni, and orthopyroxene D's range from 2 x 10(-5) for U to approximately 8 for Mg. There are regular relationships between the ionic radius, the valence of the trace element and the partition coefficients in olivine and orthopyroxene in all experiments. While there are some differences in the D values between olivine and orthopyroxene, they follow very similar trends. For experiments at high cooling rates there is an increase in the measured concentrations for incompatible trace elements in the crystals which yields apparent partition coefficients greater by up to 3 orders of magnitude from the equilibrium values obtained for isothermal equilibrium and slow cooling experiments. In contrast, compatible trace element D values are only slightly sensitive to cooling rate, typically varying by less than a factor of 2. SEM studies showed that melt inclusions were common in orthopyroxenes. It is shown that the increase in apparent D values for pyroxene observed with high cooling rates can be quantitatively explained by trapping of melt inclusions in crystals with equilibrium D values. Incorporation of melt inclusions may also quantitatively explain the increases in apparent D values in olivine at high cooling rates. However, no inclusions of melt were identified in olivine, even at the fastest cooling rate. If the high apparent D values obtained for olivine at high cooling rates were due to incorporation of trace elements in the lattice and not due to entrapment of melt, it would require incorporation of elements independent of valence and ionic radius. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP KENNEDY, AK (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,CHARLES ARMS LAB,LUNAT ASYLUM,PASADENA,CA 91125, USA. RI WASSERBURG, GERALD /F-6247-2011; Kennedy, Allen/B-2425-2013 OI Kennedy, Allen/0000-0002-2132-7825 NR 41 TC 228 Z9 231 U1 2 U2 19 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD MAR PY 1993 VL 115 IS 1-4 BP 177 EP 195 DI 10.1016/0012-821X(93)90221-T PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KW193 UT WOS:A1993KW19300014 ER PT J AU RABIN, R GORDON, SL LYMN, RW TODD, PW FREY, MAB SULZMAN, FM AF RABIN, R GORDON, SL LYMN, RW TODD, PW FREY, MAB SULZMAN, FM TI EFFECTS OF SPACEFLIGHT ON THE MUSCULOSKELETAL SYSTEM - NIH AND NASA FUTURE-DIRECTIONS SO FASEB JOURNAL LA English DT Article ID MYOSIN HEAVY-CHAIN; MYOTENDINOUS JUNCTION; MUSCLE; EXPRESSION; DYSTROPHIN; ATROPHY; BONE AB ''The Effects of Space Travel on the Musculoskeletal System,'' a workshop held at the National Institutes of Health on October 3 and 4, 1990, was sponsored jointly by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the National Aeronautics and Space Administration (NASA) Attended by 80 invitees, it was chaired by Michael F. Holick, Boston University School of Medicine, and Kenneth M. Baldwin, University of California at Irvine. Participants reviewed the normal function and structure of bone and muscle, as well as independent and interactive responses of these tissues to activity and disuse on Earth and in the microgravity environment of space. They then focused on those future directions of research, summarized in this report, that are relevant to the missions and interests of both agencies. A comprehensive review of the presentations is available from NIAMS.2 C1 NIAMSD,BETHESDA,MD 20892. LOCKHEED ENGN & SCI CO,DEPT LIFE SUPPORT,WASHINGTON,DC 20024. NASA,DIV LIFE SCI,WASHINGTON,DC 20546. UNIV COLORADO,DEPT CHEM ENGN,BOULDER,CO 80309. RP RABIN, R (reprint author), CTR SPACE & ADV TECHNOL,9302 LEE HWY,STE 400,FAIRFAX,VA 22031, USA. NR 26 TC 15 Z9 15 U1 0 U2 2 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR PY 1993 VL 7 IS 5 BP 396 EP 398 PG 3 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KV351 UT WOS:A1993KV35100002 PM 8462780 ER PT J AU GRAEDEL, TE BATES, TS BOUWMAN, AF CUNNOLD, D DIGNON, J FUNG, I JACOB, DJ LAMB, BK LOGAN, JA MARLAND, G MIDDLETON, P PACYNA, JM PLACET, M VELDT, C AF GRAEDEL, TE BATES, TS BOUWMAN, AF CUNNOLD, D DIGNON, J FUNG, I JACOB, DJ LAMB, BK LOGAN, JA MARLAND, G MIDDLETON, P PACYNA, JM PLACET, M VELDT, C TI A COMPILATION OF INVENTORIES OF EMISSIONS TO THE ATMOSPHERE SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Review ID GENERAL-CIRCULATION MODEL; SURFACE AIR-TEMPERATURE; ZONE COLOR SCANNER; NITROUS-OXIDE; HYDROCARBON EMISSIONS; ANTHROPOGENIC SOURCES; GLOBAL DISTRIBUTION; METHANE EMISSIONS; DIOXIDE EMISSIONS; EARTHS ATMOSPHERE AB Detailed and accurate emissions inventories are essential for reliable computer dispersion model simulation of the behavior of chemically and radiatively important atmospheric species. Currently, model simulations of the atmosphere are limited by the paucity of quality emissions data for input. As a first step in providing internationally recognized emissions inventories, we list here the inventories that are extant, together with their spatial and temporal characteristics and a few interpretive comments. The only global emissions inventory we regard as good is that for chlorofluorocarbons. Those for CO2, CH4, NO(x), SO2, reduced sulfur, and radon we regard as fair. In selected regions, the spatial resolution of emissions is well determined for CO2, CO, NO(x), and SO2. The temporal resolution of existing inventories is almost uniformly poor. Much remains to be done to generate emissions inventories adequate to fully support computer models of regional and global chemistry and climate. C1 PACIFIC NW LAB, WASHINGTON, DC 20024 USA. NOAA, PACIFIC MARINE ENVIRONM LAB, SEATTLE, WA 98115 USA. NATL INST PUBL HLTH & ENVIRONM PROTECT, 3720 BA BILTHOVEN, NETHERLANDS. GEORGIA INST TECHNOL, SCH GEOPHYS SCI, ATLANTA, GA 30332 USA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. WASHINGTON STATE UNIV, DEPT CIVIL ENGN, ATMOSPHER RES LAB, PULLMAN, WA 99164 USA. OAK RIDGE NATL LAB, DIV ENVIRONM SCI, OAK RIDGE, TN 37831 USA. SUNY ALBANY, ALBANY, NY 12222 USA. NORWEGIAN INST AIR RES, N-2001 LILLESTROM, NORWAY. NETHERLANDS ORG APPL SCI RES, APELDOOM, NETHERLANDS. RP AT&T BELL LABS, ROOM 1D-349, MURRAY HILL, NJ 07974 USA. RI Bouwman, Lex/B-7053-2012; Bouwman, Lex/F-1444-2015; Bates, Timothy/L-6080-2016 OI Bouwman, Lex/0000-0002-2045-1859; NR 198 TC 67 Z9 68 U1 1 U2 19 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 EI 1944-9224 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD MAR PY 1993 VL 7 IS 1 BP 1 EP 26 DI 10.1029/92GB02793 PG 26 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA KW450 UT WOS:A1993KW45000001 ER PT J AU WEBB, RS ROSENZWEIG, CE LEVINE, ER AF WEBB, RS ROSENZWEIG, CE LEVINE, ER TI SPECIFYING LAND SURFACE CHARACTERISTICS IN GENERAL-CIRCULATION MODELS - SOIL-PROFILE DATA SET AND DERIVED WATER-HOLDING CAPACITIES SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article AB A standardized global data set of soil horizon thicknesses and textures (particle size distributions) has been compiled from the Food and Agriculture Organization of the United Nations/United Nations Educational, Scientific, and Cultural Organization (FAO/UNESCO) Soil Map of the World, Vols. 2-10 [1971-1981]. This data set was developed for use by the improved land-surface hydrology parameterization designed by Abramopoulos et al. [1988] for the Goddard Institute for Space Studies General Circulation Model II (GISS GCM). The data set specifies the top and bottom depths and the percent abundance of sand, silt, and clay of individual soil horizons in each of the 106 soil types cataloged for nine continental divisions. When combined with the World Soil Data File [Zobler, 1986], the result is a 1-degrees x 1-degrees global data set of variations in physical properties throughout the soil profile. These properties are important in the determination of water storage in individual soil horizons and exchange of water with the lower atmosphere within global climate models. We have used these data sets, in conjunction with the Matthews [1983] global vegetation data set and texture-based estimates of available soil moisture, to calculate the global distributions of soil profile thickness, potential storage of water in the soil profile, potential storage of water in the root zone, and potential storage of water derived from soil texture. Comparisons with the water-holding capacities used in the GISS Model II show that our derived values for potential storage of water are consistently larger than those previously used in the GISS GCM. Preliminary analyses suggest that incorporation of this data set into the GISS GCM has improved the model's performance by including more realistic variability in land surface properties. C1 COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10027. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY. NR 42 TC 105 Z9 110 U1 5 U2 24 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 MAR PY 1993 VL 7 IS 1 BP 97 EP 108 DI 10.1029/92GB01822 PG 12 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA KW450 UT WOS:A1993KW45000006 ER PT J AU YODER, JA MCCLAIN, CR FELDMAN, GC ESAIAS, WE AF YODER, JA MCCLAIN, CR FELDMAN, GC ESAIAS, WE TI ANNUAL CYCLES OF PHYTOPLANKTON CHLOROPHYLL CONCENTRATIONS IN THE GLOBAL OCEAN - A SATELLITE VIEW SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID NORTH-ATLANTIC; PACIFIC; VARIABILITY; BIGHT; IRON; SEA AB Conceptual and mathematical models show that annual cycles of phytoplankton biomass are different within different regions of the ocean. The purpose of this manuscript is to use coastal zone color scanner chlorophyll imagery (CZCS-Chl) to determine annual cycles in phytoplankton chlorophyll (biomass) averaged over very large areas of the global ocean. A possible result is that large-scale averaging of CZCS-Chl will yield no interpretable signals because of spatial variability in annual cycles at scales much smaller than our averaging scale. Alternatively, if our analyses show regular and persistent global patterns, then our results will provide a basin-scale overview of phytoplankton biomass seasonality for comparison with model results or with other large-scale oceanographic measurements. Our results show that monthly mean CZCS-Chl imagery (and using in situ concentrations for winter at latitudes poleward of 40 deg) resolves important differences in annual phytoplankton chlorophyll cycles for different ocean basins and latitude belts. As predicted by simple models of plankton dynamics, our results show: (1) global subtropical waters have circa 2X higher CZCS-Chl concentrations in winter than in summer and (2) subpolar waters in the northern hemisphere (NH) have mean monthly CZCS-Chl concentrations during May and June that are manyfold higher than in winter, particularly in the North Atlantic. Our results also show: (1) Northern Indian Ocean is the major subtropical anomaly, (2) subpolar waters in the SH do not show differences between spring maxima and winter minima as large as those in the subpolar NH and (3) larger ocean area in the SH is compensated by higher mean annual CZCS-Chl concentrations in the NH, so that annual hemispherical integrals (mean annual concentrations multiplied by ocean areas) are very similar. The simple patterns we report imply that mean annual cycles in phytoplankton biomass averaged over very large areas of the global ocean are largely explainable by very simple mathematical models such as those presented several decades ago by Cushing, Riley, Steele, and others. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP UNIV RHODE ISL, GRAD SCH OCEANOG, S FERRY RD, NARRAGANSETT, RI 02882 USA. OI yoder, james/0000-0002-2700-8681 NR 39 TC 153 Z9 154 U1 1 U2 13 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 EI 1944-9224 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD MAR PY 1993 VL 7 IS 1 BP 181 EP 193 DI 10.1029/93GB02358 PG 13 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA KW450 UT WOS:A1993KW45000011 ER PT J AU KOMATSU, G BAKER, VR GULICK, VC PARKER, TJ AF KOMATSU, G BAKER, VR GULICK, VC PARKER, TJ TI VENUSIAN CHANNELS AND VALLEYS - DISTRIBUTION AND VOLCANOLOGICAL IMPLICATIONS SO ICARUS LA English DT Article ID WESTERN-AUSTRALIA; FLOOD BASALTS; MANTLE; PLUME; KOMATIITES; HEADS; TAILS C1 JET PROP LAB,PASADENA,CA 91109. RP KOMATSU, G (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. RI Komatsu, Goro/I-7822-2012 OI Komatsu, Goro/0000-0003-4155-108X NR 51 TC 47 Z9 47 U1 1 U2 4 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 MAR PY 1993 VL 102 IS 1 BP 1 EP 25 DI 10.1006/icar.1993.1029 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500001 ER PT J AU MCKAY, CP POLLACK, JB LUNINE, JI COURTIN, R AF MCKAY, CP POLLACK, JB LUNINE, JI COURTIN, R TI COUPLED ATMOSPHERE OCEAN MODELS OF TITANS PAST SO ICARUS LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; HYPOTHESIZED OCEAN; GREENHOUSE; CONDENSATION; EQUILIBRIUM; EVOLUTION; CLIMATE; METHANE; MARS C1 UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721. OBSERV PARIS,DEPT RECH SPATIALE,F-92195 MEUDON,FRANCE. RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 26 TC 53 Z9 53 U1 0 U2 3 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 MAR PY 1993 VL 102 IS 1 BP 88 EP 98 DI 10.1006/icar.1993.1034 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500006 PM 11536938 ER PT J AU KIM, SJ GLENAR, DA JOYCE, RR KOSTIUK, T AF KIM, SJ GLENAR, DA JOYCE, RR KOSTIUK, T TI SPATIAL AND SPECTRAL CHARACTERISTICS OF THE NEAR-INFRARED AURORAE OF JUPITER SO ICARUS LA English DT Article ID FUNDAMENTAL-BAND; MU-M; H-3+; EMISSION; H-3(+) C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. KITT PEAK NATL OBSERV,TUCSON,AZ 85726. RP KIM, SJ (reprint author), UNIV MARYLAND,DEPT CHEM ENGN,COLL PK,MD 20742, USA. RI Kim, Sang Joon/E-2383-2013; Kostiuk, Theodor/A-3077-2014 NR 18 TC 15 Z9 15 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 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1993 VL 102 IS 1 BP 99 EP 106 DI 10.1006/icar.1993.1035 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500007 ER PT J AU HIROI, T BELL, JF TAKEDA, H PIETERS, CM AF HIROI, T BELL, JF TAKEDA, H PIETERS, CM TI MODELING OF S-TYPE ASTEROID SPECTRA USING PRIMITIVE ACHONDRITES AND IRON-METEORITES SO ICARUS LA English DT Article ID SURFACE MATERIALS; MINERALOGY C1 UNIV HAWAII,SOEST,DEPT GEOL & GEOPHYS,HONOLULU,HI 96822. UNIV TOKYO,FAC SCI,INST MINERAL,TOKYO 113,JAPAN. BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. RP HIROI, T (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 30 TC 39 Z9 39 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 MAR PY 1993 VL 102 IS 1 BP 107 EP 116 DI 10.1006/icar.1993.1036 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500008 ER PT J AU KORYCANSKY, DG POLLACK, JB AF KORYCANSKY, DG POLLACK, JB TI NUMERICAL-CALCULATIONS OF THE LINEAR RESPONSE OF A GASEOUS DISK TO A PROTOPLANET SO ICARUS LA English DT Article ID SOLAR NEBULA; TIDAL INTERACTION; DENSITY WAVES; MIGRATION; LINDBLAD RP KORYCANSKY, DG (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 18 TC 63 Z9 63 U1 2 U2 3 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 MAR PY 1993 VL 102 IS 1 BP 150 EP 165 DI 10.1006/icar.1993.1039 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500011 ER PT J AU DAVIES, JK SYKES, MV CRUIKSHANK, DP AF DAVIES, JK SYKES, MV CRUIKSHANK, DP TI NEAR-INFRARED PHOTOMETRY AND SPECTROSCOPY OF THE UNUSUAL MINOR PLANET 5145-PHOLUS (1992AD) SO ICARUS LA English DT Note ID CHEMISTRY C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85724. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP DAVIES, JK (reprint author), ROYAL OBSERV,BLACKFORD HILL,EDINBURGH EH9 3HJ,MIDLOTHIAN,SCOTLAND. NR 20 TC 48 Z9 48 U1 1 U2 2 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 MAR PY 1993 VL 102 IS 1 BP 166 EP 169 DI 10.1006/icar.1993.1040 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KX515 UT WOS:A1993KX51500012 ER PT J AU SHIEH, LS WANG, YJ SUNKEL, JW AF SHIEH, LS WANG, YJ SUNKEL, JW TI HYBRID STATE-SPACE SELF-TUNING CONTROL OF UNCERTAIN LINEAR-SYSTEMS SO IEE PROCEEDINGS-D CONTROL THEORY AND APPLICATIONS LA English DT Article DE DIGITAL REDESIGN; OPTIMAL CONTROL ID REGULATORS; TIME AB The paper presents a hybrid state-space self-tuner using a new dual-rate sampling scheme for digital adaptive control of continuous-time uncertain linear systems. A state-space-based recursive least-squares algorithm, together with a variable forgetting factor, is used for direct estimations of both the equivalent discrete-time uncertain linear system parameters and the associated discrete-time state of a continuous-time uncertain linear system from the sampled input and Output data. An analogue optimal regional pole-placement design method is used for designing an optimal observer-based analogue controller. A suboptimal observer-based digital controller is then designed from the designed analogue controller using digital redesign technique. To enhance the robustness of parameter identification and state estimation algorithms, a dynamic bound for a class of uncertain bilinear parameters and a fast-rate digital controller are developed at each fast-sampling period. Also, to accommodate computation loads and computation delay for developing the advanced hybrid self-tuner, the designed analogue controller and observer gains are both updated at each slow-sampling period. This control technique has been successfully applied to benchmark control problems. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SHIEH, LS (reprint author), UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204, USA. NR 18 TC 11 Z9 11 U1 1 U2 2 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 MAR PY 1993 VL 140 IS 2 BP 99 EP 110 PG 12 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA LE249 UT WOS:A1993LE24900006 ER PT J AU TRUONG, TK REED, IS SHIH, MT AF TRUONG, TK REED, IS SHIH, MT TI EFFICIENT MULTIPLICATION ALGORITHM OVER THE FINITE-FIELDS GF(Q(M)) WHERE Q = 3, 5 SO IEE PROCEEDINGS-E COMPUTERS AND DIGITAL TECHNIQUES LA English DT Article DE CODING THEORY; MULTIPLICATION ALGORITHM; CALOIS FIELD MULTIPLICATION AB Galois field multiplication is central to coding theory. In many applications of finite fields, there is need for a multiplication algorithm which can be realised easily on VLSI chips. In the paper, what is called the Babylonian multiplication algorithm for using tables of squares is applied to the Galois fields GF(q(m)). It is shown that this multiplication method for certain Galois fields eliminates the need for the division operation of dividing by four in the original Babylonian algorithm. Also, it is found that this multiplier can be used to compute complex multiplications defined on the direct sum of two identical copies of these Galois fields. C1 UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089. RP TRUONG, TK (reprint author), JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109, USA. NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0143-7062 J9 IEE PROC-E PD MAR PY 1993 VL 140 IS 2 BP 92 EP 94 PG 3 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA LE247 UT WOS:A1993LE24700002 ER PT J AU NEUDECK, PG LARKIN, DJ STARR, JE POWELL, JA SALUPO, CS MATUS, LG AF NEUDECK, PG LARKIN, DJ STARR, JE POWELL, JA SALUPO, CS MATUS, LG TI GREATLY IMPROVED 3C-SIC P-N-JUNCTION DIODES GROWN BY CHEMICAL VAPOR-DEPOSITION SO IEEE ELECTRON DEVICE LETTERS LA English DT Article ID SIC THIN-FILMS; FIELD-EFFECT TRANSISTORS; BETA-SILICON-CARBIDE; EPITAXIAL-GROWTH; ALPHA AB In this paper we report on the fabrication and initial electrical characterization of greatly improved 3C-SiC (beta-SiC) p-n junction diodes. These diodes, which were grown on commercially available 6H-SiC substrates by chemical vapor deposition, demonstrate rectification to -200 V at room temperature, representing a fourfold improvement in reported 3C-SiC diode blocking voltage. The reverse leakage currents and saturation current densities measured on these diodes also show significant improvement compared to previously reported 3C-SiC p-n junction diodes. When placed under sufficient forward bias, the diodes emit significantly bright green-yellow light. These results should lead to substantial advancements in 3C-SiC transistor performance. C1 OHIO AEROSP INST,BROOK PK,OH 44142. CALSPAN CORP,MIDDLEBURG HTS,OH 44130. RP NEUDECK, PG (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 38 TC 21 Z9 21 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 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD MAR PY 1993 VL 14 IS 3 BP 136 EP 139 DI 10.1109/55.215136 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA KN764 UT WOS:A1993KN76400014 ER PT J AU SHIVELY, D AF SHIVELY, D TI SURFACE-WAVES ON A GROUNDED DIELECTRIC SLAB COVERED BY A RESISTIVE SHEET SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note ID THIN AB This paper examines surface wave propagation in a grounded dielectric slab covered with a resistive sheet. Transcendental equations are derived for each polarization and are solved using iterative techniques. Attention and phase velocity are shown for a representative geometry. The results are applicable to both a grounded slab covered with a resistive sheet and an ungrounded slab covered on each side with a resistive sheet. RP SHIVELY, D (reprint author), NASA,LANGLEY RES CTR,JOINT RES PROGRAMS OFF,MAIL STOP 490,HAMPTON,VA 23681, USA. NR 4 TC 3 Z9 3 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD MAR PY 1993 VL 41 IS 3 BP 348 EP 350 DI 10.1109/8.233127 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LH043 UT WOS:A1993LH04300013 ER PT J AU Rohrer, NJ Richard, MA Valco, GJ Bhasin, KB AF Rohrer, Norman J. Richard, M. A. Valco, George J. Bhasin, Kul B. TI A 10 GHz Y-Ba-Cu-O/GaAs Hybrid Oscillator Proximity Coupled to a Circular Microstrip Patch Antenna SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB A 10 GHz hybrid Y-Ba-Cu-O / GaAs microwave oscillator proximity coupled to a circular microstrip antenna has been designed, fabricated and characterized. The oscillator was a reflection mode type using a GaAs MESFET as the active element. The feedline, transmission lines, rf chokes, and bias lines were all fabricated from YBa2Cu3O7-x superconducting thin films on a 1 cm X 1 cm lanthanum aluminate substrate. The output feedline of the oscillator was wire bonded to a superconducting feedline on a second 1 cm X 1 cm lanthanum aluminate substrate, which was in turn proximity coupled to a circular microstrip patch antenna. Antenna patterns from this active patch antenna and the performance of the oscillator measured at 77 K are reported. The oscillator had a maximum output power of 11.5 dBm at 77 K, which corresponded to an efficiency of 10%. In addition, the efficiency of the microstrip patch antenna together with its high temperature superconducting feedline was measured from 85 K to 30 K and was found to be 71% at 77 K, increasing to a maximum of 87.4% at 30 K. C1 [Rohrer, Norman J.; Valco, George J.] Ohio State Univ, Dept Elect Engn, Columbus, OH 43210 USA. [Richard, M. A.] Case Western Reserve Univ, Dept Elect Engn, Cleveland, OH 44106 USA. [Bhasin, Kul B.] NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Rohrer, NJ (reprint author), Ohio State Univ, Dept Elect Engn, Columbus, OH 43210 USA. FU National Aeronautics and Space Administration [NCC-3-197]; Ohio Aerospace Institute FX This work was supported by the National Aeronautics and Space Administration under award no. NCC-3-197. M. A. Richard was supported through the Ohio Aerospace Institute Doctoral Fellowship. NR 13 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 23 EP 27 DI 10.1109/77.233412 PN 1 PG 5 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TF UT WOS:000209703000004 ER PT J AU Hooker, MW Taylor, TD Leigh, HD Wise, SA Buckley, JD Vasquez, P Buck, GM Hicks, LP AF Hooker, M. W. Taylor, T. D. Leigh, H. D. Wise, S. A. Buckley, J. D. Vasquez, P. Buck, G. M. Hicks, L. P. TI EFFECTS OF PROCESS VARIABLES ON THE PROPERTIES OF YBa2Cu3O7-x CERAMICS FORMED BY INVESTMENT CASTING SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics. C1 [Hooker, M. W.; Taylor, T. D.; Leigh, H. D.] Clemson Univ, Dept Ceram Engn, Clemson, SC 29634 USA. [Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.] NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hooker, MW (reprint author), Clemson Univ, Dept Ceram Engn, Clemson, SC 29634 USA. FU NASA-Langley Research Center, Hampton, VA [NGT-50548] FX Research performed at NASA-Langley Research Center, Hampton, VA through grant number NGT-50548. NR 10 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 1154 EP 1156 DI 10.1109/77.233349 PN 3 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TH UT WOS:000209703200061 ER PT J AU Subramanyam, G Kapoor, VJ Chorey, CM Bhasin, KB AF Subramanyam, G. Kapoor, V. J. Chorey, C. M. Bhasin, K. B. TI PROCESSING, ELECTRICAL AND MICROWAVE PROPERTIES OF SPUTTERED TI-Ca-Ba-Cu-O SUPERCONDUCTING THIN FILMS SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB A reproducible fabrication process has been established for TICaBaCuO thin films on LaAlO3 substrates by rf magnetron sputtering and post -deposition processing methods. Electrical transport properties of the thin films were measured on patterned four -probe test devices. Microwave properties of the films were obtained from unloaded Q measurements of all -superconducting ring resonators. This paper describes the processing, electrical and microwave properties of Tl2Ca1Ba2Cu2Ox (2122) phase thin films. C1 [Subramanyam, G.; Kapoor, V. J.] Univ Cincinnati, Dept Elect & Comp Engn, Cincinnati, OH 45221 USA. [Chorey, C. M.] NASA Lewis Grp, Sverdrup Technol Inc, Cleveland, OH 44135 USA. [Bhasin, K. B.] NASA Lewis Res Ctr, Cleveland, OH 44135 USA. RP Subramanyam, G (reprint author), Univ Cincinnati, Dept Elect & Comp Engn, Cincinnati, OH 45221 USA. FU NASA Lewis Research Center FX This research was supported by NASA Lewis Research Center. NR 11 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 1749 EP 1752 DI 10.1109/77.233596 PN 3 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TH UT WOS:000209703200217 ER PT J AU Gaidis, MC Friedrich, S Prober, DE Moseley, SH Szymkowiak, AE AF Gaidis, M. C. Friedrich, S. Prober, D. E. Moseley, S. H. Szymkowiak, A. E. TI SUPERCONDUCTING AL-TRILAYER TUNNEL JUNCTIONS FOR USE AS X-RAY DETECTORS SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB We have developed photolithographic techniques to fabricate high quality Al-Al Oxide-Al superconducting tunnel junctions for use in x-ray detectors. These devices are designed to incorporate approximate to 1 mu m thick superconducting x-ray absorbers for the detection of <10 keV single photons. In an effort to increase energy resolution, superconductor "bandgap engineering" with lateral and vertical trapping has been used to shorten quasiparticle tunneling times and diffusion lengths and to prevent quasiparticle diffusion away from the tunnel junction. Methods have been developed for overcoming materials incompatibility and device degradation upon thermal cycling; these are reported. We also report on the use of a non-rectangular tunnel junction geometry which reduces the magnetic field needed to suppress the Josephson current for stable biasing. Work in progress to measure the energy resolution of these x-ray detectors at 0.35 K is also discussed.* C1 [Gaidis, M. C.; Friedrich, S.; Prober, D. E.] Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. [Moseley, S. H.; Szymkowiak, A. E.] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gaidis, MC (reprint author), Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Gaidis, Michael/D-3327-2013 FU NASA [NAG 5-1244]; CT High Technology FX Research supported by NASA grant NAG 5-1244, and CT High Technology and NASA fellowships to one of us (MG). Manuscript received August 24. 1992. NR 13 TC 14 Z9 14 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 2088 EP 2091 DI 10.1109/77.233445 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TI UT WOS:000209703300070 ER PT J AU Shirron, PJ DiPirro, MJ AF Shirron, P. J. DiPirro, M. J. TI CONCEPT FOR A HIGH-RESOLUTION THERMOMETER UTILIZING THE TEMPERATURE DEPENDENCE OF THE MAGNETIC PENETRATION DEPTH SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB A thermometer utilizing the temperature dependence of the magnetic penetration depth in superconductors is described which has the potential for temperature resolution, when using a dc SQUID readout, on the order of 1 picoKelvin. One such device has been fabricated and characterized to demonstrate proof of concept. It consists of primary and secondary coils of NbTi wire wound on a copper toroidal core on which a thin (similar to 15 nm) layer of In (T-C=3.4K) has been deposited. The temperature dependence of the mutual inductance, M(T), or self-inductance, L(T), is used to detect changes in temperature. Measurements of M(T) have been made with an ac excitation of the primary for various frequencies and peak magnetic field strengths. Estimates of ultimate temperature resolution are given. C1 [Shirron, P. J.; DiPirro, M. J.] NASA, Goddard Space Flight Ctr, Code 713, Greenbelt, MD USA. RP Shirron, PJ (reprint author), NASA, Goddard Space Flight Ctr, Code 713, Greenbelt, MD USA. FU NASN/Goddard Space Flight Center Director's Discretionary Fund FX This work was supported by NASN/Goddard Space Flight Center Director's Discretionary Fund. NR 8 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 2140 EP 2143 DI 10.1109/77.233925 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TI UT WOS:000209703300083 ER PT J AU Stern, JA LeDuc, HG Zmuidzinas, J AF Stern, J. A. LeDuc, H. G. Zmuidzinas, J. TI QUASI-OPTICAL JOSEPHSON-JUNCTION OSCILLATOR ARRYAS SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB Josephson junctions are natural voltage-controlled oscillators capable of generating submillimeter-wavelength radiation, but a single junction usually can produce only 100 nW of power and often has a broad spectral linewidth. We are investigating twodimensional quasi-optical power combining arrays of 10(3) and 10(4) NbN/MgO/NbN and Nb/Al-AlOx/Nb junction to overcome these limitations. The junctions are DC biased in parallel and are distributed along interdigitated lines. The arrays couple to a resonant mode of a Fabry-Perot cavity to achieve mutual phase-locking. Devices have been produced, and the I-V characteristics of these arrays have been measured, but not as of now in the Fabry-Perot cavity. In this paper, the important features of the design and the critical device properties are discussed. C1 [Stern, J. A.; LeDuc, H. G.] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. [Zmuidzinas, J.] CALTECH, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RP Stern, JA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. FU Caltech President's Fund FX This work was supported by a Caltech President's Fund. We would also like to thank Rich Muller and Paul Maker for writing the e-beam lithography patterns. NR 9 TC 10 Z9 10 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 2485 EP 2488 DI 10.1109/77.233960 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TI UT WOS:000209703300168 ER PT J AU Lewis, LL Koepf, G Bhasin, KB Richard, MA AF Lewis, L. L. Koepf, G. Bhasin, K. B. Richard, M. A. TI PERFORMANCE OF TICaBaCuO 30 GHZ 64 ELEMENT ANTENNA ARRAY SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article AB A 64 element, 30 GHz, microstrip antenna array with corporate feed network was designed and built on a.254 mm (10 mil) thick lanthanum aluminate substrate. One antenna pattern was fabricated from gold film, and a second pattern used TICaBaCuO high temperature superconductor. Both antennas used gold ground planes deposited on the reverse side of the substrate. Gain and radiation patterns were measured for both antennas at room temperature and at cryogenic temperatures. Observations agree well with simple models for loss and microwave beam width, with a gain on boresight of 20.3 dB and beam width of 15 degrees for the superconducting antenna. C1 [Lewis, L. L.; Koepf, G.] Ball Commun Syst Div, Broomfield, CO 80038 USA. [Bhasin, K. B.] NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. [Richard, M. A.] Case Western Reserve Univ, Cleveland, OH 44106 USA. RP Lewis, LL (reprint author), Ball Commun Syst Div, Broomfield, CO 80038 USA. FU NASA Headquarters, Satellite Communications Applications Research (SCAR) Program FX Research supported in part by NASA Headquarters, Satellite Communications Applications Research (SCAR) Program. NR 8 TC 11 Z9 11 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1051-8223 EI 1558-2515 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 1993 VL 3 IS 1 BP 2844 EP 2847 DI 10.1109/77.233994 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA V43TI UT WOS:000209703300253 ER PT J AU LUNDY, GM MILLER, RE AF LUNDY, GM MILLER, RE TI ANALYZING A CSMA CD PROTOCOL THROUGH A SYSTEMS OF COMMUNICATING MACHINES SPECIFICATION SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article AB A model for the specification and analysis of communication protocols called Systems of Communicating Machines is used to specify a CSMA/CD protocol, and to analyze it for safety and certain restricted liveness properties. The model uses a combination of finite state machines and variables in the specification of each machine, and the communication between machines is accomplished through shared variables. The ethernet bus is modeled as a single variable shared by all communicating processes. Collisions are modeled by simultaneous writes to this variable. C1 UNIV MARYLAND,DEPT COMP SCI,COLL PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,CTR EXCELLENCE SPACE DATA & INFORMAT SCI,GREENBELT,MD 20771. RP LUNDY, GM (reprint author), USN,SCH POSTGRAD,DEPT COMP SCI,MONTEREY,CA 93943, USA. NR 5 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 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD MAR PY 1993 VL 41 IS 3 BP 447 EP 449 DI 10.1109/26.221072 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LL458 UT WOS:A1993LL45800006 ER PT J AU SATORIUS, EH TRUONG, TK SHIH, MT REED, IS AF SATORIUS, EH TRUONG, TK SHIH, MT REED, IS TI A VLSI DESIGN FOR A TRACEBACK VITERBI DECODER (VOL 40, PG 616, 1992) SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Correction, Addition C1 UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089. RP SATORIUS, EH (reprint author), JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109, USA. NR 3 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 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD MAR PY 1993 VL 41 IS 3 BP 508 EP 508 PG 1 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA LL458 UT WOS:A1993LL45800015 ER PT J AU SINGER, S APPELBAUM, J AF SINGER, S APPELBAUM, J TI STARTING CHARACTERISTICS OF DIRECT-CURRENT MOTORS POWERED BY SOLAR-CELLS SO IEEE TRANSACTIONS ON ENERGY CONVERSION LA English DT Article; Proceedings Paper CT 1992 WINTER MEETING OF THE POWER ENGINEERING SOC OF THE IEEE CY JAN 26-30, 1992 CL NEW YORK, NY SP IEEE, POWER ENGN SOC, ENERGY DEV & POWER GENERAT COMM DE DC MOTORS; STARTING CURRENT AND TORQUE; SOLAR CELLS ID COMMON SOURCE; OPERATION AB Direct current motors are used in photovoltaic systems. Important characteristics of electric motors are the starting to rated current and the torque ratios. These ratios are dictated by the size of the solar cell array and are different for the various dc motor types. The paper deals with the calculation of the starting to rated current ratio and starting to rated torque ratio of the permanent magnet, separately, series and shunt excited motors when powered by solar cells for the two cases: where (1) the system includes a maximum-power-point-tracker (MPPT) and (2) without an MPPT. Comparing these two cases, one gets a torque magnification of about 3 for the permanent magnet motor and about 7 for other motor types at rated design insolation. The calculation of the torques may assist the PV system designer to determine the advantage of including an MPPT in the system as far as the starting characteristics of the dc motors are concerned. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SINGER, S (reprint author), UNIV COLORADO,COLORADO SPRINGS,CO 80933, USA. NR 15 TC 25 Z9 25 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 0885-8969 J9 IEEE T ENERGY CONVER JI IEEE Trans. Energy Convers. PD MAR PY 1993 VL 8 IS 1 BP 47 EP 53 DI 10.1109/60.207405 PG 7 WC Energy & Fuels; Engineering, Electrical & Electronic SC Energy & Fuels; Engineering GA KW213 UT WOS:A1993KW21300008 ER PT J AU MARTH, PC JENSEN, JR KILGUS, CC PERSCHY, JA MACARTHUR, JL HANCOCK, DW HAYNE, GS PURDY, CL ROSSI, LC KOBLINSKY, CJ AF MARTH, PC JENSEN, JR KILGUS, CC PERSCHY, JA MACARTHUR, JL HANCOCK, DW HAYNE, GS PURDY, CL ROSSI, LC KOBLINSKY, CJ TI PRELAUNCH PERFORMANCE OF THE NASA ALTIMETER FOR THE TOPEX POSEIDON PROJECT SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID GULF-STREAM; GEOSAT ALTIMETER; MESOSCALE VARIABILITY; DATA ASSIMILATION; SURFACE; OCEAN; CIRCULATION; TOPOGRAPHY; ATLANTIC; PROFILES AB Validation of in-orbit performance has demonstrated the ability of satellite radar altimetry to measure mesoscale absolute dynamic sea surface topography and to measure the variation in the general circulation on the largest spatial scales. Measurements of basin scale mean circulation, however, have been corrupted by system inaccuracies. The TOPEX/POSEIDON radar altimeter satellite applies recent advances in remote sensing instrumentation to reduce long wavelength measurement errors to dramatically lower levels. The TOPEX altimeter measures the range to the ocean surface with 2-cm precision and accuracy through the use of both Ku- and C-band radars, a high pulse repetition frequency, an agile tracker, and absolute internal height calibration. Dual pulse bandwidths for both frequencies make it possible to quickly acquire the surface and begin tracking after crossing the land/ocean boundary. This paper presents the altimeter requirements and the elements of the altimeter design that have resulted in meeting these requirements. Prelaunch test data, based on the use of a Radar Altimeter System Evaluator to simulate the backscatter from the ocean surface, are presented to demonstrate that the TOPEX altimeter will meet these requirements and provide the data necessary to the understanding of basin scale mean circulation. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA. SIGMA XI,RES TRIANGLE PK,NC. RP MARTH, PC (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707, USA. NR 49 TC 38 Z9 41 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1993 VL 31 IS 2 BP 315 EP 332 DI 10.1109/36.214909 PG 18 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA LD280 UT WOS:A1993LD28000001 ER PT J AU NEREM, RS PUTNEY, BH MARSHALL, JA LERCH, FJ PAVLIS, EC KLOSKO, SM LUTHCKE, SB PATEL, GB WILLIAMSON, RG ZELENSKY, NP AF NEREM, RS PUTNEY, BH MARSHALL, JA LERCH, FJ PAVLIS, EC KLOSKO, SM LUTHCKE, SB PATEL, GB WILLIAMSON, RG ZELENSKY, NP TI EXPECTED ORBIT DETERMINATION PERFORMANCE FOR THE TOPEX POSEIDON MISSION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID GRAVITATIONAL MODEL; OCEANLESS EARTH; SATELLITE; ALTIMETRY; LAGEOS; GEM-T1 AB The TOPEX/Poseidon (T/P) mission, launched during the summer of 1992, has the requirement that the radial component of its orbit must be computed to an accuracy of 13 cm root-mean-square (rms) or better, allowing measurements of the sea surface height to be computed to similar accuracy when the satellite height is differenced with the altimeter measurements. This will be done by combining precise satellite tracking measurements with precise models of the forces acting on the satellite. The Space Geodesy Branch at Goddard Space Flight Center (GSFC), as part of the T/P precision orbit determination (POD) Team, has the responsibility within NASA for the T/P precise orbit computations. The prelaunch activities of the T/P POD Team have been mainly directed towards developing improved models of the static and time-varying gravitational forces acting on T/P and precise models for the non-conservative forces perturbing the orbit of T/P such as atmospheric drag, solar and Earth radiation pressure, and thermal imbalances. The radial orbit error budget for T/P allows 10 cm rms error due to gravity field mismodeling, 3 cm due to solid Earth and ocean tides, 6 cm due to radiative forces, and 3 cm due to atmospheric drag. A prelaunch assessment of the current modeling accuracies for these forces indicates that the radial orbit error requirements can be achieved with the current models, and can probably be surpassed once T/P tracking data are used to fine tune the models. Provided that the performance of the T/P spacecraft is nominal, the precise orbits computed by the T/P POD Team should be accurate to 13 cm or better radially. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. RP NEREM, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,HUGHES STX CORP,GREENBELT,MD 20771, USA. RI Luthcke, Scott/D-6283-2012 NR 49 TC 14 Z9 14 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 MAR PY 1993 VL 31 IS 2 BP 333 EP 354 DI 10.1109/36.214910 PG 22 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA LD280 UT WOS:A1993LD28000002 ER PT J AU RAY, RD AF RAY, RD TI GLOBAL OCEAN TIDE MODELS ON THE EVE OF TOPEX/POSEIDON SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID GEOSAT ALTIMETRY; EARTH; PREDICTIONS; ATLANTIC; ROTATION; GRAVITY; SEASAT; M2 AB Some existing global ocean tide models that can provide tide corrections to Topex/Poseidon altimeter data are described. Emphasis is given to the Schwiderski and Cartwright-Ray models, as these are the most comprehensive, highest resolution models, but other models that will soon appear are mentioned. Differences between models for M2 often exceed 10 cm over vast stretches of the ocean. Comparisons to 80 selected pelagic and island gauge measurements indicate the Schwiderski model is more accurate for the major solar tides, Cartwright-Ray for the major lunar tides. The adequacy of available tide models for studying basin-scale motions is probably marginal at best. The subject, however, is in a state of flux, and we may expect rapid advancement over the next several years. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012 NR 69 TC 32 Z9 32 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 MAR PY 1993 VL 31 IS 2 BP 355 EP 364 DI 10.1109/36.214911 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 LD280 UT WOS:A1993LD28000003 ER PT J AU HEVIZI, LG WALSH, EJ MCINTOSH, RE VANDEMARK, D HINES, DE SWIFT, RN SCOTT, JF AF HEVIZI, LG WALSH, EJ MCINTOSH, RE VANDEMARK, D HINES, DE SWIFT, RN SCOTT, JF TI ELECTROMAGNETIC BIAS IN SEA-SURFACE RANGE MEASUREMENTS AT FREQUENCIES OF THE TOPEX POSEIDON SATELLITE SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID RADAR ALTIMETER; GEOSAT ALTIMETER; STATE BIAS; DEPENDENCE AB Range measurements made by satellite radar altimeters experience an electromagnetic (EM) bias toward the troughs of ocean waves. This EM bias was measured at the 13.6 GHz and 5.3 GHz operating frequencies of the NASA altimeter on the TOPEX/POSEIDON satellite in a series of 11 aircraft flights from January 17, 1991, through March 4, 1991, during the Surface WAve Dynamics Experiment (SWADE). The data are consistent with an earlier set of airborne measurements and indicate that EM bias is slightly higher at 5.3 GHz than at 13.6 GHz, and that the magnitudes of both biases increase with increasing wind speed, as does their difference. With some exceptions, EM bias shows little variation over a mesoscale region on a given day or within 1 or 2 h, but it can change significantly over a 6-h period. An examination of recent tower, airborne, and satellite measurements shows a consistency in the characteristics of the wind speed dependence but suggests that there may be a height dependence in the determinations, with the bias decreasing with increasing altitude. The airborne measurements appear to be the most reasonable basis for correcting the NASA altimeter range data from the TOPEX/POSEIDON satellite. In addition, a preliminary analysis of a very limited amount of the data acquired at 20.3 m s-1 in Southern Ocean Waves Experiment (SOWEX) has given confidence that the quadratic models for the prelaunch EM bias corrections are more appropriate for wind speed dependence than are the linear models initially considered. C1 NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,EG&G WASHINGTON ANALYT SERV CTR INC,WALLOPS ISL,VA 23337. RP HEVIZI, LG (reprint author), UNIV MASSACHUSETTS,DEPT ELECT & COMP ENGN,AMHERST,MA 01003, USA. NR 17 TC 17 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1993 VL 31 IS 2 BP 376 EP 388 DI 10.1109/36.214914 PG 13 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA LD280 UT WOS:A1993LD28000006 ER PT J AU ENGLAND, MN SCHMIDLIN, FJ JOHANSSON, JM AF ENGLAND, MN SCHMIDLIN, FJ JOHANSSON, JM TI ATMOSPHERIC MOISTURE MEASUREMENTS - A MICROWAVE RADIOMETER - RADIOSONDE COMPARISON SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID WATER-VAPOR; PATH-DELAY; LIQUID AB The NASA/Goddard Space Flight Center Crustal Dynamics Project microwave Water Vapor Radiometer (WVR-J03) is used to measure the thermal emission of the sky at three frequencies (20.7, 22.2, and 31.4 GHz). Measurements were taken during the Atmospheric Moisture Intercomparison Study (ATMIS) held at Wallops Island, VA during April 1989. These measurements were compared with brightness temperatures inferred from measurements from VAISALA radiosonde packages launched every 3 hours during the experiment period. An error analysis for the radiosonde-inferred brightness temperatures was performed assuming reasonable random uncertainties for the pressure, temperature, and humidity measurements and propagating these uncertainties through the analysis algorithm. For the assumed uncertainties (sigma(P) = sigma(T) = 0.84 K, and sigma(RH) = 5% RH) the dominant contribution to the total uncertainty comes from the temperature measurement (66% - 88%) whereas the relative humidity measurement contributes only 2% - 8%, except in the vicinity of the water vapor line, where the contribution is 10% - 20%. Sky brightness temperature random errors range from 0.03 K to 0.6 K, with systematic errors between 0.4 K and 1.8 K. Two different water vapor emission models were used for the derivation of the brightness temperatures from the radiosonde measurements. The Liebe model and VAISALA radiosonde data give better agreement with the WVR for the 20.7 and 22.2 GHz frequencies (mean differences [WVR - VAI] of -0.32 +/- 0.56 K and -0.22 +/- 0.77 K, respectively) than does the Waters model and VAISALA radiosonde data. Agreement is best at 31.4 GHz using the Waters model (mean difference [WVR - VAI] -0.28 +/- 0.5 K), although in all cases the differences are less than the estimated uncertainties on the radiosonde inferred brightness temperatures. Differences between the two models increase as the moisture content increases and vary as a function of frequency. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC,WALLOPS ISL,VA 23337. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP ENGLAND, MN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OBSERV COMP SCI CORP,GREENBELT,MD 20771, USA. NR 30 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1993 VL 31 IS 2 BP 389 EP 398 DI 10.1109/36.214915 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 LD280 UT WOS:A1993LD28000007 ER PT J AU KALSHOVEN, JE DABNEY, PW AF KALSHOVEN, JE DABNEY, PW TI REMOTE-SENSING OF THE EARTHS SURFACE WITH AN AIRBORNE POLARIZED LASER SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB A new remote sensing instrument, the Airborne Laser Polarization Sensor (ALPS), makes the first multispectral radiometric and polarization measurements of the Earth's surface using a polarized laser light source. Results from data flights taken over boreal forests in Maine at two wavelengths (using a Nd:YAG laser source: 1060 nm and 532 nm) show distinct depolarization signatures for three broadleaf and five coniferous tree species. A statistically significant increase in depolarization is found to correlate with increasing leaf surface roughness for the broadleaf species in the near-infrared. With the exception of spruce, the dominant species in the boreal forest, conifers had no clear depolarization variations between species at that wavelength. The mean depolarization by conifers was distinctively lower, however, than that measured for the broadleaf species. The conifers did exhibit distinct depolarization signatures at 532 nm, while the broadleaf species had no apparent species dependent depolarization variations at that wavelength. Measurements made over nonforest ground cover had a large dynamic range in depolarization values at both wavelengths. The ALPS system employees twelve photo-multiplier tube detectors configurable to measure desired parameters such as the total backscatter and the polarization state, including the azimuthal angle and ellipticity, at different ultraviolet to near-infrared wavelengths simultaneously. Measurements of the azimuth and ellipticity of the backscatter polarization were variable and no specific conclusions have yet been drawn. RP KALSHOVEN, JE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. RI Dabney, Philip/C-9976-2013 NR 28 TC 20 Z9 20 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 MAR PY 1993 VL 31 IS 2 BP 438 EP 446 DI 10.1109/36.214920 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 LD280 UT WOS:A1993LD28000012 ER PT J AU PARKER, JW FERRARO, RD LIEWER, PC AF PARKER, JW FERRARO, RD LIEWER, PC TI COMPARING 3D FINITE-ELEMENT FORMULATIONS MODELING SCATTERING FROM A CONDUCTING SPHERE SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 5TH BIENNIAL IEEE CONF ON ELECTROMAGNETIC FIELD COMPUTATION ( IEEE-CEFC ) CY AUG 03-05, 1992 CL HARVEY MUDD COLL, CLAREMONT, CA SP IEEE, MAGNET SOC, HARVEY MUDD COLL HO HARVEY MUDD COLL AB Six tetrahedral finite element varieties are used to model the frequency-domain open-region scattering problem of a ka = 2 conducting sphere. A wave-absorbing boundary condition is imposed at kr = 3. Linear and quadratic node-based elements display vector parasites, which are less significant in the quadratic element case. Whitney edge elements improve with increasing mesh density, but accuracy is costly due to approximately linear h-convergence. Whitney elements also result in acceptably fast convergence of a bi-conjugate gradient iterative solver, alone among the elements examined here. Novel weighted Whitney elements show some effectiveness and appear free of vector parasites, but are not cost effective as compared with Whitney elements. Higher-order tangential elements appear cost-effective, in that accurate solutions may be obtained at low mesh density. RP PARKER, JW (reprint author), CALTECH,JET PROPULS LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 3 TC 5 Z9 5 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 MAR PY 1993 VL 29 IS 2 BP 1646 EP 1649 DI 10.1109/20.250721 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA KV879 UT WOS:A1993KV87900090 ER PT J AU LEE, JC SHEU, BJ FANG, WC CHELLAPPA, R AF LEE, JC SHEU, BJ FANG, WC CHELLAPPA, R TI VLSI NEUROPROCESSORS FOR VIDEO MOTION DETECTION SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article ID OPTICAL-FLOW; DEPTH; CIRCUITS; MAP AB The system design of a locally connected competitive neural network for video motion detection is presented. The motion information from a sequence of image data can be determined through a two-dimensional multiprocessor array in which each processing element consists of an analog neuroprocessor. Massively parallel neurocomputing is done by compact and efficient neuroprocessors. Local data transfer between the neuroprocessors is performed by using an analog point-to-point interconnection scheme. To maintain strong signal strength over the whole system, global data communication between the host computer and neuroprocessors is carried out in a digital common bus. A mixed-signal very large scale integration (VLSI) neural chip that includes multiple neuroprocessors for fast video motion detection has been developed. Measured results of the programmable synapse, and winner-take-all circuitry are presented. Based on the measurement data, system-level analysis on a sequence of real-world images was conducted. A 1.5 x 2.8-cm2 chip in a 1.2-mum CMOS technology can accommodate 64 velocity-selective neuroprocessors. Each chip can achieve 83.2 giga connections per second. The intrinsic speed-up factor over a Sun-4/75 workstation is around 180. C1 NATL CHIAO TUNG UNIV,HSINCHU,TAIWAN. JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,INST SIGNAL & IMAGE PROC,DEPT ELECT ENGN ELECTROPHYS & SYST,LOS ANGELES,CA 90089. NR 54 TC 8 Z9 8 U1 12 U2 15 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD MAR PY 1993 VL 4 IS 2 BP 178 EP 191 DI 10.1109/72.207607 PG 14 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA KW592 UT WOS:A1993KW59200001 PM 18267719 ER PT J AU SPIRKOVSKA, L REID, MB AF SPIRKOVSKA, L REID, MB TI COARSE-CODED HIGHER-ORDER NEURAL NETWORKS FOR PSRI OBJECT RECOGNITION SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article AB A higher-order neural network (HONN) can be designed to be invariant to changes in scale, translation, and in-plane rotation. Invariances are built directly into the architecture of a HONN and do not need to be learned. Consequently, fewer training passes and a smaller training set are required to learn to distinguish between objects. The size of the input field is limited, however, because of the memory required for the large number of interconnections in a fully connected HONN. By coarse coding the input image, the input field size can be increased to allow the larger input scenes required for practical object recognition problems. We describe a coarse coding technique and present simulation results illustrating its usefulness and its limitations. Our simulations show that a third-order neural network can be trained to distinguish between two objects in a 4096 x 4096 pixel input field independent of transformations in translation, in-plane rotation, and scale in less than ten passes through the training set. Furthermore, we empirically determine the limits of the coarse coding technique in the object recognition domain. RP SPIRKOVSKA, L (reprint author), NASA,AMES RES CTR,MT VIEW,CA, USA. NR 12 TC 29 Z9 29 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 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD MAR PY 1993 VL 4 IS 2 BP 276 EP 283 DI 10.1109/72.207615 PG 8 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA KW592 UT WOS:A1993KW59200009 PM 18267727 ER PT J AU DAY, WB MCCREARY, CL WALLS, B AF DAY, WB MCCREARY, CL WALLS, B TI AN ALLOCATION ALGORITHM FOR DISTRIBUTING DATALOG PROGRAMS SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS LA English DT Letter AB An O(N3) algorithm for partitioning and allocating N DataLog procedural bundles among K distributed or dedicated processors is presented. The algorithm determines a static distribution of the bundles to all K processors. The independent variables of the objective function include both processing and communication costs, and the goal is to balance the processing requirements of the K processors while allocating bundles in such a way as to reduce the communication costs. The algorithm can be used with heterogeneous systems of processors, and it can accommodate a two-tier communication model where both local area networks and more expensive wide area networks are used. Furthermore, the algorithm can be used interactively with a programmer or system designer. Example results from its implementation are given, and a comparison with another technique is shown. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP DAY, WB (reprint author), AUBURN UNIV,DEPT COMP SCI & ENGN,AUBURN,AL 36849, USA. NR 20 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 0018-9472 J9 IEEE T SYST MAN CYB JI IEEE Trans. Syst. Man Cybern. PD MAR-APR PY 1993 VL 23 IS 2 BP 570 EP 576 DI 10.1109/21.229470 PG 7 WC Computer Science, Cybernetics; Engineering, Electrical & Electronic SC Computer Science; Engineering GA LR798 UT WOS:A1993LR79800024 ER PT J AU PATRICK, V GAVALAS, GR SHARMA, PK AF PATRICK, V GAVALAS, GR SHARMA, PK TI REDUCTION, SULFIDATION, AND REGENERATION OF MIXED IRON ALUMINUM-OXIDE SORBENTS SO INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH LA English DT Article ID H2S; DESULFURIZATION; PYRRHOTITE; PRECURSORS; GASES AB The reduction and sulfidation of Fe2O3 and Fe2O3-Al2O3 sorbents were investigated by thermogravimetric analysis (TGA). Mixed iron-aluminum oxides were reduced more slowly and by a more complex mechanism than pure iron oxide. Several phases that were responsible for this difference were identified by temperature-programmed reduction (TPR), X-ray diffraction (XRD), BET surface area (BET), and scanning electron microscopy (SEM). Sulfidation of reduced sorbents in the TGA at 600-degrees-C produced two crystalline phases: high-temperature, hexagonal pyrrhotite (Fe1-xS), and unreacted FeAl2O4. The reaction of the pure and mixed oxide with a mixture of H2S-H2-H2O-N2 was studied in a tubular microreactor to evaluate the performance of these materials as high-temperature H2S sorbents. At 650-degrees-C the mixed oxide yielded considerably lower prebreakthrough outlet H2S levels than the pure iron oxide. Regeneration in pure SO2 and SO2-air mixtures of sulfided samples resulted in complete conversion of iron sulfide to iron oxide and quantitative recovery of elemental sulfur. C1 CALTECH,DIV CHEM & CHEM ENGN,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 35 TC 25 Z9 25 U1 1 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0888-5885 J9 IND ENG CHEM RES JI Ind. Eng. Chem. Res. PD MAR PY 1993 VL 32 IS 3 BP 519 EP 532 DI 10.1021/ie00015a015 PG 14 WC Engineering, Chemical SC Engineering GA KQ965 UT WOS:A1993KQ96500015 ER PT J AU CHAMBERLAIN, RG FOX, M POLLOCK, SM SHAW, SH NUNEZ, EJ FORD, JR MAGEE, JF MACHOL, RE AF CHAMBERLAIN, RG FOX, M POLLOCK, SM SHAW, SH NUNEZ, EJ FORD, JR MAGEE, JF MACHOL, RE TI 20 30 HINDSIGHT - HOW MUCH MATHEMATICS DO YOU USE SO INTERFACES LA English DT Article DE MATHEMATICS PROFESSIONAL; MS OR EDUCATION C1 UNIV MICHIGAN,ANN ARBOR,MI 48109. SHELL DEV CO,HOUSTON,TX 77001. ROHM & HAAS CO,PHILADELPHIA,PA 19105. ARTHUR D LITTLE INC,CAMBRIDGE,MA 02140. RP CHAMBERLAIN, RG (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST OPERATIONS RESEARCH MANAGEMENT SCIENCES PI LINTHICUM HTS PA 901 ELKRIDGE LANDING RD, STE 400, LINTHICUM HTS, MD 21090-2909 SN 0092-2102 J9 INTERFACES JI Interfaces PD MAR-APR PY 1993 VL 23 IS 2 BP 93 EP 101 DI 10.1287/inte.23.2.93 PG 9 WC Management; Operations Research & Management Science SC Business & Economics; Operations Research & Management Science GA KY422 UT WOS:A1993KY42200012 ER PT J AU MATTHEWS, E AF MATTHEWS, E TI GLOBAL GEOGRAPHICAL DATABASES FOR MODELING TRACE GAS FLUXES SO INTERNATIONAL JOURNAL OF GEOGRAPHICAL INFORMATION SYSTEMS LA English DT Article ID AMAZON RIVER FLOODPLAIN; METHANE FLUX; RICE PADDY; ATMOSPHERIC METHANE; EMISSIONS; TROPOSPHERE; WATER; TEMPERATURE; VEGETATION; WETLANDS AB The design and development of global digital databases and their integrated use in studies of terrestrial sources and sinks of trace gases are discussed. Generic design characteristics that expand the utility of these databases are outlined including: hierarchical classification systems that provide for encoding and accessing data at several levels of detail, and fine spatial and thematic resolution which accommodate adaptations to a broad base of applications. The discussion follows the sequence of (1) developing primary databases on major surface characteristics, (2) selectively integrating combinations of data bases to produce secondary data sets of source categories, and (3) combining information on source categories with fluxes to produce tertiary data sets of emissions. These procedures are demonstrated with the example of estimating and evaluating alternative global methane emissions from natural wetlands. RP MATTHEWS, E (reprint author), HUGHES STX CORP,NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 61 TC 1 Z9 1 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0269-3798 J9 INT J GEOGR INF SYST JI Int. J. Geogr. Inf. Syst. PD MAR-APR PY 1993 VL 7 IS 2 BP 125 EP 142 DI 10.1080/02693799308901946 PG 18 WC Geography; Information Science & Library Science SC Geography; Information Science & Library Science GA LH919 UT WOS:A1993LH91900004 ER PT J AU EAGLES, DM AF EAGLES, DM TI ANALYSIS OF RESISTANCE DATA ON A GOOD CERAMIC SAMPLE OF YBA2CU3O7-X SO JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS LA English DT Article DE ELECTRICAL RESISTIVITY; FLUCTUATION EFFECTS; NORMAL-STATE PROPERTIES; 2-BAND MODEL; HALL COEFFICIENT ID HIGH-TC SUPERCONDUCTORS; SINGLE-CRYSTAL YBA2CU3O7-X; TRANSPORT-PROPERTIES; FLUCTUATION CONDUCTIVITY; ELECTRICAL-CONDUCTIVITY; ANISOTROPIC RESISTIVITY; THERMOELECTRIC-POWER; HALL DATA; TEMPERATURE; OXIDE AB Resistance data between 91.4 and 200 K on a ceramic sample of YBa2Cu3O7-x are analysed using a two-band model for normal-state conductance plus the Lawrence-Doniach theory for effects of superconducting fluctuations. The data is fitted to a root-mean-square accuracy of 0.16% of the resistance in the middle of the temperature range. The steepest slope of the resistance of the sample occurs at 91.13 K, and the analysis shows that the critical region extends to less than 0.3 K above T(c). Values of parameters found indicate that defect or impurity scattering within grains is unusually small in this sample. Some difficulties in understanding Hall data using either simple two-band models or more sophisticated one-band models are discussed briefly. C1 NORWEGIAN INST TECHNOL,DIV PHYS,N-7034 TRONDHEIM,NORWAY. FDN RES & TECHNOL HELLAS,INST ELECTR STRUCT & LASER,GR-71110 IRAKLION,GREECE. RP EAGLES, DM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,CODE ES 74,HUNTSVILLE,AL 35812, USA. NR 56 TC 1 Z9 1 U1 1 U2 2 PU JAPAN J APPLIED PHYSICS PI MINATO-KU TOKYO PA DAINI TOYOKAIJI BLDG 24-8 SHINBASHI 4-CHOME, MINATO-KU TOKYO 105, JAPAN SN 0021-4922 J9 JPN J APPL PHYS 1 JI Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap. PD MAR PY 1993 VL 32 IS 3A BP 1077 EP 1081 DI 10.1143/JJAP.32.1077 PG 5 WC Physics, Applied SC Physics GA KV994 UT WOS:A1993KV99400010 ER PT J AU DITTMAR, JH HALL, DG AF DITTMAR, JH HALL, DG TI CRUISE NOISE OF AN ADVANCED PROPELLER WITH SWIRL RECOVERY VANES SO JOURNAL OF AIRCRAFT LA English DT Article AB A model SR-7A propeller was acoustically tested with and without downstream swirl recovery vanes to determine if any extra noise was caused by the interaction of the propeller wakes and vortices with these vanes. No additional noise was observed at the cruise condition over the angular range 46-130 deg. The presence of the swirl recovery vanes unloaded the propeller and resulted in small peak noise reductions. The propeller test without vanes was also used to investigate the variation of the peak propeller noise with helical tip Mach number. As observed before on other propellers, the peak noise initially increased with helical tip Mach number and remained constant or decreased at higher helical tip Mach numbers. Detailed pressure-time histories indicate that a portion of the primary pressure pulse is progressively cancelled by a secondary pulse as the helical tip Mach number is increased. RP DITTMAR, JH (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 1993 VL 30 IS 2 BP 221 EP 226 DI 10.2514/3.56885 PG 6 WC Engineering, Aerospace SC Engineering GA KV465 UT WOS:A1993KV46500009 ER PT J AU WEIZER, VG FATEMI, NS AF WEIZER, VG FATEMI, NS TI LOW RESISTANCE SILVER CONTACTS TO INDIUM-PHOSPHIDE - ELECTRICAL AND METALLURGICAL CONSIDERATIONS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID AU-INP INTERACTION; GOLD; GAAS AB The electrical and metallurgical behavior of the Ag-InP contact system has been investigated. Specific contact resistivity (R(c)) values in the low 10(-6) OMEGA cm2 range are readily achieved on n-InP (Si: 1.7 X 10(18) cm-3) after sintering at 400-degrees-C for several minutes. The low R(c) values, however, are shown to be accompanied by dissolution of InP into the metallization, resulting in device degradation. An analysis of the sinter-induced metallurgical interactions indicates that this system is quite similar to the well-characterized Au-InP system, although there are some fundamental differences. The similarities include the dissociative diffusion of In, the reaction-suppressing effect of SiO2 capping, and, most importantly, the formation of a phosphide layer at the metal-InP interface. It is suggested that the low post-sinter R(c) values in the Ag-InP system are due to the presence of a AgP2 layer at the metal-InP interface. We show that it is possible to achieve low values of R(c) without incurring device degrading metallurgical interactions by introducing a thin AgP2 layer between the InP and the current carrying metallization. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP WEIZER, VG (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 17 TC 10 Z9 10 U1 0 U2 1 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 MAR 1 PY 1993 VL 73 IS 5 BP 2353 EP 2359 DI 10.1063/1.353113 PG 7 WC Physics, Applied SC Physics GA KT868 UT WOS:A1993KT86800043 ER PT J AU SPAULDING, GF JESSUP, JM GOODWIN, TJ AF SPAULDING, GF JESSUP, JM GOODWIN, TJ TI ADVANCES IN CELLULAR CONSTRUCTION SO JOURNAL OF CELLULAR BIOCHEMISTRY LA English DT Editorial Material ID CULTURE; CELLS C1 NEW ENGLAND DEACONESS HOSP,BOSTON,MA 02215. NASA,LYNDON B JOHNSON SPACE CTR,KRUG LIFE SCI,HOUSTON,TX 77058. RP SPAULDING, GF (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOTECHNOL PROGRAM,HOUSTON,TX 77058, USA. NR 14 TC 30 Z9 31 U1 0 U2 1 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0730-2312 J9 J CELL BIOCHEM JI J. Cell. Biochem. PD MAR PY 1993 VL 51 IS 3 BP 249 EP 251 DI 10.1002/jcb.240510302 PG 3 WC Biochemistry & Molecular Biology; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA KR850 UT WOS:A1993KR85000001 PM 8501125 ER PT J AU BECKER, JL PREWETT, TL SPAULDING, GF GOODWIN, TJ AF BECKER, JL PREWETT, TL SPAULDING, GF GOODWIN, TJ TI 3-DIMENSIONAL GROWTH AND DIFFERENTIATION OF OVARIAN TUMOR-CELL LINE IN HIGH ASPECT ROTATING-WALL VESSEL - MORPHOLOGIC AND EMBRYOLOGIC CONSIDERATIONS SO JOURNAL OF CELLULAR BIOCHEMISTRY LA English DT Article DE HETEROLOGOUS MIXED MULLERIAN TUMOR; OVARIAN TUMOR MODEL; PLURIPOTENT CELL ID MIXED MESODERMAL TUMOR AB Cancer of the ovary is the leading cause of death from gynecologic malignancy. To understand better these aggressive tumors, the development of in vitro models to study human ovarian cancer is critical. However, the establishment of long-term cell lines has been difficult, due to the generalized poor survival of patient tumor cells grown in primary culture. Satisfactory culture systems for ovarian tumor cells have therefore been limited. To study cellular interactions involved in the growth and differentiation of these tumors, a cell line was established from a mixed mullerian tumor of the ovary. This cell line, designated LN1, was cultured on microcarrier beads in the high aspect rotating-wall vessel. The tumor cells grown in this vessel readily proliferated without a requirement for cocultivation with a supportive cell layer. Evaluation of cellular morphology by phase contrast light microscopy and scanning electron microscopy revealed the presence of three-dimensional multicellular aggregates consisting of multiple cell-coated beads bridged together, as well as scattered aggregates of LN1 cells proliferating as spheroids free in suspension. In contrast to conventional culture systems, culture in the high aspect rotating-wall vessel facilitated the generation of multiple cell types that could be recovered. These results illustrate the ability of this culture system to provide the biological conditions necessary for pluripotent cell growth. C1 KRUG LIFE SCI,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP BECKER, JL (reprint author), UNIV S FLORIDA,DEPT OBSTET & GYNECOL,4 COLUMBIA DR,TAMPA,FL 33606, USA. NR 25 TC 69 Z9 70 U1 1 U2 7 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0730-2312 J9 J CELL BIOCHEM JI J. Cell. Biochem. PD MAR PY 1993 VL 51 IS 3 BP 283 EP 289 DI 10.1002/jcb.240510307 PG 7 WC Biochemistry & Molecular Biology; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA KR850 UT WOS:A1993KR85000006 PM 8501130 ER PT J AU JESSUP, JM GOODWIN, TJ SPAULDING, G AF JESSUP, JM GOODWIN, TJ SPAULDING, G TI PROSPECTS FOR USE OF MICROGRAVITY-BASED BIOREACTORS TO STUDY 3-DIMENSIONAL HOST TUMOR INTERACTIONS IN HUMAN NEOPLASIA SO JOURNAL OF CELLULAR BIOCHEMISTRY LA English DT Article DE MICROGRAVITY-BASED BIOREACTORS; 3-DIMENSIONAL HOST TUMOR INTERACTIONS; BATCH CULTURE; EPITHELIAL CELLS; NEOPLASTIC TRANSFORMATION ID FLUIDIZED-BED BIOREACTORS; COLON CANCER-CELLS; CULTURE; LINE; DIFFERENTIATION AB Microgravity offers unique advantages for the cultivation of mammalian tissues because the lack of gravity-induced sedimentation supports three-dimensional growth in batch culture in aqueous medium. Bioreactors that simulate microgravity but operate in unit gravity provide conditions that permit human epithelial cells to grow to densities approaching 10(7) cells/ml on microcarriers in suspension, in masses up to 1 cm in diameter, and under conditions of low shear stress. While useful for many different applications in tissue culture, this culture system is especially useful for the analysis of the microenvironment in which host matrix and cells interact with infiltrating tumor cells. Growth in the microgravity-based bioreactor has supported morphological differentiation of human colon carcinoma cells when cultured with normal human stromal cells. Furthermore, these co-cultures produced factors that stimulated goblet cell production in normal colon cells in an in vivo bioassay. Early experiments also suggest that the microgravity environment will not alter the ability of epithelial cells to recognize and associate with each other and with constituents of basement membrane and extracellular matrix. These findings suggest that cells grown in bioreactors that simulate aspects of microgravity or under actual microgravity conditions will produce tissues and substances in sufficient quantity and at high enough concentration to promote characterization of molecules that control differentiation and neoplastic transformation. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOTECHNOL PROGRAM,HOUSTON,TX 77058. RP JESSUP, JM (reprint author), NEW ENGLAND DEACONESS HOSP,DEPT SURG,CANC BIOL LAB,185 PILGRIM RD,BOSTON,MA 02215, USA. FU NCI NIH HHS [CA42587] NR 25 TC 79 Z9 83 U1 2 U2 8 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0730-2312 J9 J CELL BIOCHEM JI J. Cell. Biochem. PD MAR PY 1993 VL 51 IS 3 BP 290 EP 300 DI 10.1002/jcb.240510308 PG 11 WC Biochemistry & Molecular Biology; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA KR850 UT WOS:A1993KR85000007 PM 8501131 ER PT J AU GOODWIN, TJ PREWETT, TL WOLF, DA SPAULDING, GF AF GOODWIN, TJ PREWETT, TL WOLF, DA SPAULDING, GF TI REDUCED SHEAR-STRESS - A MAJOR COMPONENT IN THE ABILITY OF MAMMALIAN-TISSUES TO FORM 3-DIMENSIONAL ASSEMBLIES IN SIMULATED MICROGRAVITY SO JOURNAL OF CELLULAR BIOCHEMISTRY LA English DT Article DE INTEGRATED ROTATING-WALL VESSEL; SHEAR STRESS; SIMULATED MICROGRAVITY; 3-DIMENSIONAL TISSUES; MICROCARRIERS ID CELL-CULTURE; DAMAGE; GROWTH AB BHK-21 cells were cultured under various shear stress conditions in an Integrated Rotating-Wall Vessel (IRWV). Shear ranged from 0.5 dyn/cm2 (simulated microgravity) to 0.92 dyn/cm2. Under simulated microgravity conditions, BHK-21 cells complexed into three-dimensional cellular aggregates attaining 6 x 10(6) cells/ml as compared to growth under 0.92 dyn/cm2 conditions. Glucose utilization in simulated microgravity was reduced significantly, and cellular damage at the microcarrier surface was kept to a minimum. Thus, the integrated rotating wall vessel provides a quiescent environment for the culture of mammalian cells. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GOODWIN, TJ (reprint author), KRUG LIFE SCI,1290 HERCULES DR,SUITE 120,HOUSTON,TX 77058, USA. NR 33 TC 153 Z9 164 U1 4 U2 17 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0730-2312 J9 J CELL BIOCHEM JI J. Cell. Biochem. PD MAR PY 1993 VL 51 IS 3 BP 301 EP 311 DI 10.1002/jcb.240510309 PG 11 WC Biochemistry & Molecular Biology; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA KR850 UT WOS:A1993KR85000008 PM 8501132 ER PT J AU CHERTOCK, B SUD, YC AF CHERTOCK, B SUD, YC TI COMPARISON OF OCEAN SURFACE SOLAR IRRADIANCE IN THE GLA GENERAL-CIRCULATION MODEL AND SATELLITE-BASED CALCULATIONS SO JOURNAL OF CLIMATE LA English DT Note ID RADIATION; BIOSPHERE; SIB AB A global, 7-year satellite-based record of ocean surface solar irradiance (SSI) is used to assess the realism of ocean SSI simulated by the nine-layer Goddard Laboratory for Atmospheres (GLA) General Circulation Model (GCM). January and July climatologies of net SSI produced by the model are compared with corresponding satellite climatologies for the world oceans between 54-degrees-N and 54-degrees-S. This comparison of climatologies indicates areas of strengths and weaknesses in the GCM treatment of cloud-radiation interactions, the major source of model uncertainty. Realism of ocean SSI is also important for applications such as incorporating the GLA GCM into a coupled ocean-atmosphere GCM. The results show that the GLA GCM simulates too much SSI in the extratropics and too little in the tropics, especially in the summer hemisphere. These discrepancies reach magnitudes of 60 W m-2 and more. The discrepancies are particularly large in the July case off the western coast of North America. In this region of persistent marine stratus, the GCM climatological values exceed the satellite climatological values by as much as 131 W m-2. Positive and negative discrepancies in SSI are shown to be consistent with discrepancies in planetary albedo. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP CHERTOCK, B (reprint author), NOAA,ENVIRONM RES INST,WAVE PROPAGAT LAB,BOULDER,CO 80303, USA. NR 29 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAR PY 1993 VL 6 IS 3 BP 560 EP 567 DI 10.1175/1520-0442(1993)006<0560:COOSSI>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KY833 UT WOS:A1993KY83300010 ER PT J AU HO, HJ TSAI, MY MORTON, J FARLEY, GL AF HO, HJ TSAI, MY MORTON, J FARLEY, GL TI AN EXPERIMENTAL PROCEDURE FOR THE IOSIPESCU COMPOSITE SPECIMEN TESTED IN THE MODIFIED WYOMING FIXTURE SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Note DE IOSIPESCU COMPOSITE SPECIMENS; IOSIPESCU SHEAR TEST; MODIFIED WYOMING FIXTURE; SHEAR PROPERTIES ID SHEAR TEST; UNIDIRECTIONAL COMPOSITES AB A detailed description of the experimental procedure for testing composite Iosipescu specimens in the modified Wyoming fixture is presented. Specimen preparation and strain gage instrumentation are addressed. Interpretation of the experimental results is discussed. With the proper experimental setup and procedure, consistent and repeatable shear properties are obtained. C1 NASA,LANGLEY RES CTR,USA AEROSTRUCT DIRECTORATE,HAMPTON,VA 23665. RP HO, HJ (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061, USA. NR 21 TC 5 Z9 5 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD SPR PY 1993 VL 15 IS 1 BP 52 EP 58 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA KW116 UT WOS:A1993KW11600007 ER PT J AU VENKATAKRISHNAN, V MAVRIPLIS, DJ AF VENKATAKRISHNAN, V MAVRIPLIS, DJ TI IMPLICIT SOLVERS FOR UNSTRUCTURED MESHES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID EQUATIONS; SYSTEMS C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP VENKATAKRISHNAN, V (reprint author), NASA,AMES RES CTR,APPL RES BRANCH,COMP SCI CORP,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 18 TC 55 Z9 57 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR PY 1993 VL 105 IS 1 BP 83 EP 91 DI 10.1006/jcph.1993.1055 PG 9 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA KT822 UT WOS:A1993KT82200008 ER PT J AU JIANG, BN AF JIANG, BN TI NONOSCILLATORY AND NONDIFFUSIVE SOLUTION OF CONVECTION PROBLEMS BY THE ITERATIVELY REWEIGHTED LEAST-SQUARES FINITE-ELEMENT METHOD SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID COMPRESSIBLE EULER; CONSERVATION-LAWS; EQUATIONS; SCHEMES RP JIANG, BN (reprint author), NASA,LEWIS RES CTR,ICOMP,CLEVELAND,OH 44135, USA. NR 35 TC 8 Z9 8 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR PY 1993 VL 105 IS 1 BP 108 EP 121 DI 10.1006/jcph.1993.1057 PG 14 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA KT822 UT WOS:A1993KT82200010 ER PT J AU PULLIAM, TH VASTANO, JA AF PULLIAM, TH VASTANO, JA TI TRANSITION TO CHAOS IN AN OPEN UNFORCED 2D FLOW SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID COMPUTATIONAL INSTABILITY; TURBULENCE; PRELUDE RP PULLIAM, TH (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 20 Z9 20 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR PY 1993 VL 105 IS 1 BP 133 EP 149 DI 10.1006/jcph.1993.1059 PG 17 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA KT822 UT WOS:A1993KT82200012 ER PT J AU PINES, V ZLATKOWSKI, M CHAIT, A AF PINES, V ZLATKOWSKI, M CHAIT, A TI SURFACE-TENSION ANISOTROPY AND CELL-LIKE STRUCTURE FORMATION IN FREE SOLIDIFICATION SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10TH INTERNATIONAL CONF ON CRYSTAL GROWTH ( ICCG-10 ) CY AUG 16-21, 1992 CL SAN DIEGO, CA SP INT UNION CRYSTAL GROWTH, AIRTRON, AKZO, ALLIED SIGNAL, BERTRAM LABS, CERES, CLEVELAND CRYSTALS, CRYSTAL ASSOC, CRYSTAL SYST, CRYSTAL TECHNOL ID PERTURBED-SPHERICAL NUCLEUS; PURE SUPERCOOLED LIQUID; TIME DEVELOPMENT; GROWTH; INSTABILITIES AB This work addresses the role of a surface tension anisotropy during solidification of a pure Material from a supercooled melt. We study the formation of a pre-dendritic cell-like structure using fully time-dependent nonlinear numerical solutions of the thermodiffusion model avoiding simplifications of mathematical nature. The introduction of surface tension anisotropy to the model results in changes of cell tip radii as well as in some variations in the morphology of the solid-liquid interface. Time dependent mechanisms lead to the establishment of near constancy of cell tip radii and the restoration of cell tip radii following induced tip perturbations; both phenomenon are found for zero and nonzero surface tension anisotropy parameter values. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 9 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1993 VL 128 IS 1-4 BP 247 EP 250 DI 10.1016/0022-0248(93)90327-S PN 1 PG 4 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KU915 UT WOS:A1993KU91500042 ER PT J AU BORSHCHEVSKY, A FLEURIAL, JP AF BORSHCHEVSKY, A FLEURIAL, JP TI GROWTH OF HEAVILY-DOPED SIGE FROM METALLIC SOLUTIONS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10TH INTERNATIONAL CONF ON CRYSTAL GROWTH ( ICCG-10 ) CY AUG 16-21, 1992 CL SAN DIEGO, CA SP INT UNION CRYSTAL GROWTH, AIRTRON, AKZO, ALLIED SIGNAL, BERTRAM LABS, CERES, CLEVELAND CRYSTALS, CRYSTAL ASSOC, CRYSTAL SYST, CRYSTAL TECHNOL ID LIQUID-PHASE EPITAXY; PERTURBED ANGULAR-CORRELATION; SILICON; GERMANIUM; DIFFUSION; ANTIMONY; ENERGY AB Liquid phase epitaxy (LPE) and traveling solvent method (TSM) have been used to grow heavily doped Si-Ge. LPE has been found suitable for near-equilibrium single-crystalline layer growth of Si-rich alloys on Si substrates at temperatures substantially lower than for stoichiometric melts. Higher dopant(s) solid solubilities at these lower temperatures allowed the introduction into the growing layer of much more Ga and P simultaneously. Direct compositional measurements proved a great enhancement of P solubility in Si80Ge20 when Ga is present. Necessary ternary and quaternary phase diagrams, previously calculated, were used extensively. Noticeable contribution of III-V interaction during crystallization of the alloys is discussed. Growth of bulk homogeneous SiGe solid solution ingots by TSM using solvents such as Sn or Ga were also investigated. The TSM recrystallization of Si80Ge20 source was performed in an 800-900-degrees-C temperature range, in a sealed quartz ampoule moving at 0.4-0.6 mm/day. The growth resulted in dense polycrystalline ingots with cross-sections of the grains of about 5-7 mm. Electrical and thermal properties of the samples were measured from room temperature to 1000-degrees-C. RP BORSHCHEVSKY, A (reprint author), JET PROP LAB,4800 OAK GROVE DR,M-S 277-212,PASADENA,CA 91109, USA. NR 21 TC 4 Z9 4 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1993 VL 128 IS 1-4 BP 331 EP 337 DI 10.1016/0022-0248(93)90343-U PN 1 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KU915 UT WOS:A1993KU91500058 ER PT J AU SU, CH VOLZ, MP GILLIES, DC SZOFRAN, FR LEHOCZKY, SL DUDLEY, M YAO, GD ZHOU, WY AF SU, CH VOLZ, MP GILLIES, DC SZOFRAN, FR LEHOCZKY, SL DUDLEY, M YAO, GD ZHOU, WY TI GROWTH OF ZNTE BY PHYSICAL VAPOR TRANSPORT AND TRAVELING HEATER METHOD SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10TH INTERNATIONAL CONF ON CRYSTAL GROWTH ( ICGG-10 ) CY AUG 16-21, 1992 CL SAN DIEGO, CA AB ZnTe crystals were grown by horizontal physical vapor transport (PVT) and a Te-solution vertical traveling heater method (THM). The grown crystals were examined by X-ray Laue diffraction technique and Hall measurements to determine the growth orientation and the electrical properties of the crystals. They were also characterized by low temperature infrared (IR) absorption measurements. Several sets of distinct peaks were observed in the IR absorption spectra for the THM samples and were identified as resulting from Cu2+ impurities. Similar measurements on vapor grown ZnTe showed featureless absorption spectra. Chemical analyses were carried out to measure the impurity content in various ZnTe samples and synchrotron radiation topography was used to study crystalline microstructure of the (111) ZnTe single crystals grown by PVT. C1 SUNY STONY BROOK,DEPT MAT SCI & ENGN,STONY BROOK,NY 11794. RP SU, CH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 14 TC 20 Z9 20 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1993 VL 128 IS 1-4 BP 627 EP 632 DI 10.1016/S0022-0248(07)80013-3 PN 2 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KV697 UT WOS:A1993KV69700012 ER PT J AU SINGH, NB GOTTLIEB, M MAZELSKY, R DUVAL, WMB AF SINGH, NB GOTTLIEB, M MAZELSKY, R DUVAL, WMB TI THE OPTICAL-QUALITY OF MERCUROUS HALIDE CRYSTALS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10TH INTERNATIONAL CONF ON CRYSTAL GROWTH ( ICGG-10 ) CY AUG 16-21, 1992 CL SAN DIEGO, CA ID CHLORIDE CRYSTALS; DEVICES; GROWTH AB The improvement in the optical quality of mercurous halide crystals is described. Optical quality was evaluated by studying optical distortion, birefringence interferograms, and laser scattering characteristics; the parameters which are crucial for practical devices. Mercurous chloride and mercurous bromide crystals showed acoustic attenuation constants of 8 and 11.8 dB mus-1 GHz-2 for cm size crystals. The acoustic attenuation of mercurous iodide was very large and varied significantly because of inhomogeneities in the matrices of cm size crystals. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SINGH, NB (reprint author), WESTINGHOUSE ELECT CORP,CTR SCI & TECHNOL,1310 BEULAH RD,PITTSBURGH,PA 15235, USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1993 VL 128 IS 1-4 BP 1053 EP 1058 DI 10.1016/S0022-0248(07)80096-0 PN 2 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KV697 UT WOS:A1993KV69700095 ER PT J AU ROSCH, W JESSER, W DEBNAM, W FRIPP, A WOODELL, G PENDERGRASS, TK AF ROSCH, W JESSER, W DEBNAM, W FRIPP, A WOODELL, G PENDERGRASS, TK TI A TECHNIQUE FOR MEASURING THE HEAT-TRANSFER COEFFICIENT INSIDE A BRIDGMAN FURNACE SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10TH INTERNATIONAL CONF ON CRYSTAL GROWTH ( ICGG-10 ) CY AUG 16-21, 1992 CL SAN DIEGO, CA AB Knowledge of the amount of heat that is conducted, advected and radiated between an ampoule and the furnace is important for understanding vertical Bridgman crystal growth. This heat transfer depends on the temperature, emissivities and geometries of both the furnace and ampoule, as well as the choice of ambient gas inside the furnace. This paper presents a method which directly measures this heat transfer without the need to know any physical properties of the furnace, the ampoule, or the gaseous environment. Data are given for one specific furnace in which this method was used. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NASA,MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35899. RP ROSCH, W (reprint author), UNIV VIRGINIA,CHARLOTTESVILLE,VA 22901, USA. NR 4 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1993 VL 128 IS 1-4 BP 1187 EP 1192 DI 10.1016/S0022-0248(07)80121-7 PN 2 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA KV697 UT WOS:A1993KV69700120 ER PT J AU RAVE, DP CORDES, CL AF RAVE, DP CORDES, CL TI TIME-ACTIVITY BUDGET OF NORTHERN PINTAILS USING NONHUNTED RICE FIELDS IN SOUTHWEST LOUISIANA SO JOURNAL OF FIELD ORNITHOLOGY LA English DT Article ID SACRAMENTO-VALLEY; FEEDING ECOLOGY; CALIFORNIA; WATERFOWL; TEXAS AB Monthly behavioral observations of Northern Pintails (Anas acuta) were conducted on five leased tracts of nonhunted private land, each including 60 ha of flooded rice fields, in southwest Louisiana during November-February 1988-1989. Pintails spent 52% of diurnal time resting, 21% feeding, 16% in comfort activities, 6% in locomotion, 4% courting and 1% in other behaviors. Activities differed among months and periods of the day. Pintails used nonhunted rice fields only during the day, departing after sunset. Pintail time budgets in Louisiana approximated those reported in California. Pintails using rice fields during the day, however, fed more than did those roosting on open water pools at Lacassine National Wildlife Refuge (NWR), Louisiana. Small (60 ha), nonhunted rice fields provided wintering Northern Pintails security plus food during the day. C1 LOUISIANA STATE UNIV,CTR WETLANDS RESOURCES,US FISH & WILDLIFE SERV,BATON ROUGE,LA 70803. NASA,US FISH & WILDLIFE SERV,NATL WETLANDS RES CTR,SLIDELL,LA 70458. NR 19 TC 23 Z9 24 U1 1 U2 9 PU ASSOC FIELD ORNITHOLOGISTS PI BELOIT PA BELOIT COLLEGE, DEPT BIOLOGY, 700 COLLEGE ST, BELOIT, WI 53511 SN 0273-8570 J9 J FIELD ORNITHOL JI J. Field Ornithol. PD SPR PY 1993 VL 64 IS 2 BP 211 EP 218 PG 8 WC Ornithology SC Zoology GA KZ075 UT WOS:A1993KZ07500012 ER PT J AU CONNELL, JW SMITH, JG HERGENROTHER, PM AF CONNELL, JW SMITH, JG HERGENROTHER, PM TI THE EFFECT OF OXYGEN PLASMA ON SOME EXPERIMENTAL POLYMERS CONTAINING SILICON AND PHOSPHORUS SO JOURNAL OF FIRE SCIENCES LA English DT Article; Proceedings Paper CT 39TH SAGAMORE ARMY MATERIALS RESEARCH CONF CY SEP 16-17, 1992 CL PLYMOUTH, MA ID SPACE STATION; FILMS AB As part of a NASA program on high performance polymers for space applications, polymers containing silicon and phosphorus were prepared, characterized and exposed to an oxygen plasma under vacuum. Thin films of polyimides containing pendent siloxane groups, thermosetting resins containing silicon and poly(arylene ether)s containing phenylphosphine oxide were exposed to a radio frequency generated oxygen plasma to assess their stability. The weight loss of the films was monitored as a function of exposure time and compared with that of Ultem(R) and Kapton(R) polyimide films of the same thickness exposed under identical conditions. All of the experimental materials exhibited better weight retention than either of the commercial polyimides. The thermosetting resins containing silicon and poly(arylene ether)s containing phosphine oxide exhibited only minor weight loss (0-5%) compared to that exhibited by Ultem(R) (75-100%) and Kapton(R) (35-82%). Organic polymers containing silicon are known to form silicates and silicon dioxide when exposed to atomic oxygen providing an in situ protective coating. Likewise, polymers containing phosphorus have been shown to form an inorganic phosphate surface layer which subsequently provides protection from further oxidation. The same inherent characteristics that provide the polymers with atomic oxygen resistance (i.e., high oxidation state or inorganic oxide formation) may also impart fire resistance. Materials containing phosphorus are known to exhibit good flame resistance. The chemistry, properties, limiting oxygen index and oxygen plasma resistance of these materials will be discussed. RP CONNELL, JW (reprint author), NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23681, USA. NR 25 TC 19 Z9 19 U1 1 U2 5 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0734-9041 J9 J FIRE SCI JI J. Fire Sci. PD MAR-APR PY 1993 VL 11 IS 2 BP 137 EP 146 DI 10.1177/073490419301100203 PG 10 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA KV027 UT WOS:A1993KV02700003 ER PT J AU JIMENEZ, J ORLANDI, P AF JIMENEZ, J ORLANDI, P TI THE ROLLUP OF A VORTEX LAYER NEAR A WALL SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TURBULENT BOUNDARY-LAYER; VORTICITY; FLOW; DYNAMICS; WAVES; FILAMENTATION AB The behaviour of an inviscid vortex layer of non-zero thickness near a wall is studied, both through direct numerical simulation of the two-dimensional vorticity equation at high Reynolds numbers, and using an approximate ordinary nonlinear integro-differential equation which is satisfied in the limit of a thin layer under long-wavelength perturbations. For appropriate initial conditions the layer rolls up and breaks into compact vortices which move along the wall at constant speed. Because of the effect of the wall, they correspond to equilibrium counter-rotating vortex dipoles. This breakup can be related to the disintegration of the initial conditions of the approximate nonlinear dispersive equation into solitary waves. The study is motivated by the formation of longitudinal vortices from vortex sheets in the wall region of a turbulent channel. C1 UNIV ROMA LA SAPIENZA,DIPARTIMENTO MECCAN & AERONAUT,I-00184 ROME,ITALY. STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JIMENEZ, J (reprint author), U POLITECN,SCH AERONAUT,PL CARDENAL CISNEROS 3,E-28040 MADRID,SPAIN. RI jimenez, javier/A-6691-2008 OI jimenez, javier/0000-0003-0755-843X NR 31 TC 24 Z9 24 U1 0 U2 3 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 MAR PY 1993 VL 248 BP 297 EP 313 DI 10.1017/S0022112093000783 PG 17 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KU924 UT WOS:A1993KU92400013 ER PT J AU GOLDSTEIN, ME LEIB, SJ AF GOLDSTEIN, ME LEIB, SJ TI A NOTE ON THE DISTORTION OF A FLAT-PLATE BOUNDARY-LAYER BY FREE-STREAM VORTICITY NORMAL TO THE PLATE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID COLLISION AB The purpose of this note is to construct a local solution that eliminates a residual velocity discontinuity in the inviscid portion of a solution obtained in a recent paper by Goldstein, Leib & Cowley (1992). This result is of importance because it shows that the solution obtained in that paper is entirely non-singular outside the viscous wall boundary layer and that any singularity in the problem will have to arise in the usual way through a breakdown in the viscous boundary layer. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP GOLDSTEIN, ME (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 6 TC 4 Z9 4 U1 0 U2 0 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 MAR PY 1993 VL 248 BP 531 EP 541 DI 10.1017/S0022112093000898 PG 11 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KU924 UT WOS:A1993KU92400024 ER PT J AU DEMUREN, AO SARKAR, S AF DEMUREN, AO SARKAR, S TI PERSPECTIVE - SYSTEMATIC STUDY OF REYNOLDS STRESS CLOSURE MODELS IN THE COMPUTATIONS OF PLANE CHANNEL FLOWS SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID TURBULENT SHEAR-FLOW AB This paper investigates the roles of pressure-strain and turbulent diffusion models in the numerical calculation of turbulent plane channel flows with second-moment closure models. Only high Reynolds number models are considered. Three turbulent diffusion and five pressure-strain models are utilized in the computations. The main characteristics of the mean flow and the turbulent fields are compared against experimental data. All the features of the mean flow are correctly predicted by all but one of the Reynolds stress closure models. The Reynolds stress anisotropies in the log layer are predicted to varying degrees of accuracy (good to fair) by the models. It is found that, contrary to previous assertions, wall-reflection terms are not necessary to obtain the correct Reynolds stress anisotropy in the log-layer. The pressure-strain models determine the level of anisotropy in the log-layer, while the diffusion models strongly influence the rate of relaxation towards isotropy in the outer-layer. None of the models could predict correctly the extent of relaxation towards isotropy of the streamwise and lateral components of the Reynolds stresses in the wake region near the center of the channel. Results from direct numerical simulation are used to further clarify this behavior of the models. C1 NASA, LANGLEY RES CTR, ICASE, HAMPTON, VA 23665 USA. RP OLD DOMINION UNIV, DEPT MECH ENGN & MECH, NORFOLK, VA 23529 USA. NR 24 TC 12 Z9 12 U1 0 U2 1 PU ASME PI NEW YORK PA TWO PARK AVE, NEW YORK, NY 10016-5990 USA SN 0098-2202 EI 1528-901X J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD MAR PY 1993 VL 115 IS 1 BP 5 EP 12 DI 10.1115/1.2910114 PG 8 WC Engineering, Mechanical SC Engineering GA KV017 UT WOS:A1993KV01700003 ER PT J AU DEPASCALE, MP MORSELLI, A PICOZZA, P GOLDEN, RL GRIMANI, C KIMBELL, BL STEPHENS, SA STOCHAJ, SJ WEBBER, WR BASINI, G BONGIORNO, F BRANCACCIO, FM RICCI, M ORMES, JF SEO, ES STREITMATTER, RE PAPINI, P SPILLANTINI, P BRUNETTI, MT CODINO, A MENICHELLI, M SALVATORI, I AF DEPASCALE, MP MORSELLI, A PICOZZA, P GOLDEN, RL GRIMANI, C KIMBELL, BL STEPHENS, SA STOCHAJ, SJ WEBBER, WR BASINI, G BONGIORNO, F BRANCACCIO, FM RICCI, M ORMES, JF SEO, ES STREITMATTER, RE PAPINI, P SPILLANTINI, P BRUNETTI, MT CODINO, A MENICHELLI, M SALVATORI, I TI ABSOLUTE SPECTRUM AND CHARGE RATIO OF COSMIC-RAY MUONS IN THE ENERGY REGION FROM 0.2 GEV TO 100 GEV AT 600-M ABOVE SEA-LEVEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB We have determined the momentum spectrum and charge ratio of muons in the region from 250 MeV/c to 100 GeV/c using a superconducting magnetic spectrometer. The absolute differential spectrum of muons obtained in this experiment at 600 m above sea level is in good agreement with the previous measurements at sea level. The differential spectrum can be represented by a power law with a varying index, which is consistent with zero below 450 MeV/c and steepens to a value of -2.7 +/- 0.1 between 20 and 100 GeV/c. The integral flux of muons measured in this experiment span a very large range of momentum and is in excellent agreement with the earlier results. The positive to negative muon ratio appears to be constant in the entire momentum range covered in this experiment within the errors and the mean value is 1.220 +/- 0.044. The absolute momentum spectrum and the charge ratio measured in this experiment are also consistent with the theoretical expectations. This is the only experiment which covers a wide range of nearly 3 decades in momentum from a very low momentum. C1 UNIV FIRENZE,DIPARTIMENTO FIS,FLORENCE,ITALY. INFN,LAB NAZL FRASCATI,I-00044 ROME,ITALY. NEW MEXICO STATE UNIV,PARTICLE ASTROPHYS LAB,LAS CRUCES,NM 88003. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV PERUGIA,DIPARTIMENTO FIS,I-06100 PERUGIA,ITALY. INFN,PERUGIA,ITALY. RP DEPASCALE, MP (reprint author), UNIV ROMA TOR VERGATA,DIPARTIMENTO FIS,VIA EMANUELE CARNEVALE 15,I-00173 ROME,ITALY. RI Morselli, Aldo/G-6769-2011 OI Morselli, Aldo/0000-0002-7704-9553 NR 19 TC 49 Z9 50 U1 1 U2 5 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 MAR 1 PY 1993 VL 98 IS A3 BP 3501 EP 3507 DI 10.1029/92JA02672 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900003 ER PT J AU CANE, HV AF CANE, HV TI COSMIC-RAY DECREASES AND MAGNETIC CLOUDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FORBUSH DECREASES; DISTURBANCES; VOYAGER; SHOCK AB A study has been made of energetic particle data, obtained from IMP 8, in conjunction with solar wind field and plasma data at the times of reported magnetic clouds. It is shown that magnetic clouds can cause a depression of the cosmic ray flux but high fields are required. A depression of 3% in a neutron monitor requires a field of about 25 nT. Such high fields are found only in a subset of coronal ejecta. The principal cause for Forbush decreases associated with energetic shocks is probably turbulence in the postshock region, although some shocks will be followed by an ejecta with a high field. Each event is different. The lower-energy particles can help in identifying the dominant processes in individual events. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NR 19 TC 48 Z9 48 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 MAR 1 PY 1993 VL 98 IS A3 BP 3509 EP 3512 DI 10.1029/92JA02479 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900004 ER PT J AU BURLAGA, LF NESS, NF AF BURLAGA, LF NESS, NF TI RADIAL AND LATITUDINAL VARIATIONS OF THE MAGNETIC-FIELD STRENGTH IN THE OUTER HELIOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LARGE HELIOCENTRIC DISTANCES; SOLAR-WIND; PIONEER OBSERVATIONS; GRADIENTS; VOYAGER; DEFECTS; 1-AU AB This paper analyzes the radial, latitudinal, and temporal variations of the magnetic field in the outer heliosphere, using the observations from Voyagers 1 and 2 and Pioneers 10 and 11. The radial variation of the magnetic field strength measured during 1973-1989 from 1 to 19 AU is compared with that predicted by Parker's spiral field model. The speed deficit (V - V1)/V1 between 1 and 19 AU is (+0.0027 +/- 0.0026)/AU for the Voyager data and (0.0099 +/- 0.0024)/AU for the Pioneer 11 data. Thus the Voyager data are consistent with no radial variation of the speed, as assumed in deriving Parker's equations for the spiral field, but the Pioneer data are not. The magnetic flux deficit in the outer heliosphere relative to 1 AU is measured by the quantity D = (A - A1)/A1 versus R. For the Voyager data the 1 AU intercept of the best fit line to these data is (0.029 +/- 0.031), which is consistent with zero, as required by the definition of D. For the Pioneer 11 data the corresponding 1 AU intercept is (-0.068 +/- 0.044), which implies a flux deficit of (7% +/- 4%) at 1 AU, suggesting either a systematic error in the data or statistical uncertainties greater than we estimated. The magnetic flux deficit is given by the slope the best fit line to D versus R. The Voyager data give a slope -(0.0027 +/- 0.0036)/AU, which is consistent with zero, indicating no flux deficit in the Voyager data. The Pioneer data give a slope (0.0040 +/- 0.0042)/AU, which is also consistent with zero. Since the best fit line to the Voyager observations of D versus R gives a value of D at 1 AU consistent with zero, we may set D(1) = 0 and obtain D(R) = [(0.0001 +/- 0.0021)/AU] x (R - 1)(AU), consistent with no flux deficit between 1 and 19 AU from 1977 through 1985. For the years 1986 and 1987 the Voyager data give a nonzero flux deficit equal to (-0.264 +/- 0.075)/AU and (-0.171 +/- 0.070)/AU, respectively. The Pioneer 11 data show no significant flux deficit during 1986 (+0.19 +/- 0.22)/AU. The flux deficit observed by Voyager 2 during these 2 years near solar minimum might be related to the presence of a heliospheric vortex street at this time. The magnetic field strength measured by Voyager 1 at high latitudes is smaller than the magnetic field strength measured by Voyager 2 near the heliographic equator beyond 21 AU. During 1986, when the heliospheric vortex street wrapped field lines in spirals around the axes of the vortices, the source magnetic field strength at 27-degrees-N was greater than the source field strength at approximately 1-degrees-N. During 1988 and 1989, when the vortex street was no longer present, the source field strength at approximately 30-degrees-N was less than that at approximately 3-degrees-N to 4-degrees-N. The topology of the spiral interplanetary magnetic field is determined by a defect in the heliosphere, the rotating Sun. The language of group theory can describe this and other more complex defects and vector fields in the heliosphere. C1 UNIV DELAWARE, BARTOL RES INST, NEWARK, DE 19718 USA. RP NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, CODE 692, GREENBELT, MD 20771 USA. NR 27 TC 17 Z9 17 U1 1 U2 1 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 MAR 1 PY 1993 VL 98 IS A3 BP 3539 EP 3549 DI 10.1029/92JA02555 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900007 ER PT J AU OGILVIE, KW GEISS, J GLOECKLER, G BERDICHEVSKY, D WILKEN, B AF OGILVIE, KW GEISS, J GLOECKLER, G BERDICHEVSKY, D WILKEN, B TI HIGH-VELOCITY TAILS ON THE VELOCITY DISTRIBUTION OF SOLAR-WIND IONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SHOCKS AB Recent observations of the solar wind using the SWICS instrument on the Ulysses spacecraft have shown the presence of high-velocity ''tails'' on the velocity distribution of protons. Similar features have also been observed on the velocity distributions of helium and oxygen ions. Of the order of 1% of the solar wind density is involved in these tails, which are approximately exponential in shape and persist to V = V(B) + 10V(th) or beyond, where V(B) is the bulk velocity and V(th) the thermal velocity of the solar wind. This paper contains a preliminary description of the phenomenon. It is clear that it is ultimately connected with the passage of interplanetary shocks past the spacecraft and that particle acceleration at oblique shocks is involved. C1 HUGHES STX,LANHAM,MD 20740. UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV MARYLAND,DEPT PHYS & ASTRON,COLL PK,MD 20742. RP OGILVIE, KW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 692,GREENBELT RD,GREENBELT,MD 20771, USA. NR 21 TC 22 Z9 22 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 MAR 1 PY 1993 VL 98 IS A3 BP 3605 EP 3611 DI 10.1029/92JA02902 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900011 ER PT J AU TAN, LC MASON, GM RICHARDSON, IG IPAVICH, FM AF TAN, LC MASON, GM RICHARDSON, IG IPAVICH, FM TI DIFFUSION-COEFFICIENTS OF ENERGETIC WATER GROUP IONS NEAR COMET GIACOBINI-ZINNER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ISEE-C; PICKUP IONS; HEAVY-IONS; STOCHASTIC ACCELERATION; SOLAR-WIND; PARTICLES; UPSTREAM; MODEL; WAVES; H+ AB When the ICE spacecraft flew past the comet Giacobini-Zinner on September 11, 1985, the ultra low-energy charge analyzer and energetic particle anisotropy spectrometer sensors observed an intensity gradient in the flux of fast (800-1400 km s-1) water group ions in the so-called transition region downstream of the cometary bow wave. We have combined the data from the two sensors and applied a single, self-consistent analysis technique to derive a single-particle spectrum from approximately 200-1600 km s-1. Using this information, along with the deduced bulk flow speed of the ions, we calculate a parallel diffusion coefficient in the transition region downstream of the cometary bow wave of (2.3 +/- 0.5) x 10(17) cm2 s-1; the corresponding scattering mean free path lambda is (6 +/- 1) x 10(4) km. We also find that the parallel diffusion coefficient depends on the collision frequency nu+ (nu-) of water group ions with Alfven waves, which we assume are propagating parallel (antiparallel) to the magnetic field. Our observations are consistent with nu+ = (1.6 +/- 0.4) x 10(-2) s-1 and nu-/nu+ = 0.3 +/- 0.2; i.e., most of the waves are propagating in the antisunward direction. C1 UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLL PK,MD 20742. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP TAN, LC (reprint author), UNIV MARYLAND,DEPT PHYS,COLL PK,MD 20742, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 30 TC 1 Z9 1 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 MAR 1 PY 1993 VL 98 IS A3 BP 3613 EP 3621 DI 10.1029/92JA02551 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900012 ER PT J AU TSURUTANI, BT THORNE, RM AF TSURUTANI, BT THORNE, RM TI COMPARISON OF OBSERVED AND CALCULATED IMPLANTED ION DISTRIBUTIONS OUTSIDE COMET-HALLEYS BOW SHOCK - COMMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GIACOBINI-ZINNER; PICKUP IONS; WAVES C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. RP TSURUTANI, BT (reprint author), JET PROP LAB,SPACE PHYS & ASTROPHYS SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 1 Z9 1 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 MAR 1 PY 1993 VL 98 IS A3 BP 3623 EP 3625 DI 10.1029/92JA01659 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900013 ER PT J AU FARRELL, WM LEPPING, RP SMITH, CW AF FARRELL, WM LEPPING, RP SMITH, CW TI ULF TURBULENCE IN THE NEPTUNIAN POLAR CUSP SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA; MAGNETOSPHERE; MAGNETOPAUSE; MAGNETOMETER; RECONNECTION; VOYAGER-2; HAWKEYE-1; UPSTREAM; WAVES; LAYER AB One of the most fortuitous events occurring during the Voyager 2 Neptune encounter was the passage of the spacecraft through the southern magnetic cusp region prior to entry into the magnetosphere. This region was previously identified by a slow, steady change in the magnetic field direction to a dipolar configuration and a slow, steady decrease in electron and ion fluxes. Such observations are similar to those of the terrestrial cusp. Besides these characteristics, the region also possesses enhanced ULF magnetic turbulence at frequencies less than 0.5 Hz as measured by the Voyager 2 magnetometer (MAG) experiment. The activity is particularly strong at the frontside magnetopause boundary and at the backside cusp/magnetosphere boundary. Specifically, in these regions the fluctuation level. DELTAB/B, is as large as 6%. The enhanced ULF turbulence extends from 0.01 Hz continuously up to nearly 0.5 Hz, and is consistent with the whistler mode. Calculations indicate that such turbulence should resonate with electrons having energies in the tens of kiloelectron volts. Observations indicate a very strong correlation of the ULF turbulence with the energetic electrons between 22 and 35 keV measured by Voyager's low-energy charged particle (LECP) experiment. This result suggests a Vigorous interaction between the two. Based on an assumed cusp geometry and measured wave levels, the ULF turbulence could generate as much as 10(7) W of power that would be absorbed by the surrounding magnetosphere. This power input represents about 1% of the total auroral power required to drive the UV aurora and radio emissions. Thus the ULF wave turbulence in the cusp may represent a significant but not complete power source for the magnetosphere. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19718. RP FARRELL, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 695,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 28 TC 1 Z9 1 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 JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1993 VL 98 IS A3 BP 3631 EP 3643 DI 10.1029/92JA02204 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900015 ER PT J AU COLE, KD AF COLE, KD TI COMPARISON OF DAYSIDE CURRENT LAYERS IN VENUS IONOSPHERE AND EARTHS EQUATORIAL ELECTROJET SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLANETARY IONOSPHERES; MAGNETIC-FIELDS; MODEL AB The major physical aspects of the equatorial electrojet of Earth and the dayside ionospheric current layers of Venus are compared, viz., the electric current intensity and total current, roles of electric field, pressure and gravity, diffusion time scales, and the Bernouille effect. The largest potential differences, of the order of 10 volts, horizontally across the dayside ionosphere of Venus, have important implications for possible dynamo action in the Venus ionosphere and the application of an electric field from the lower atmosphere or from the solar wind. An upper limit to the horizontal scale of vertical magnetic fields in the Venus ionosphere is estimated thereby for the first time. New upper limits on the velocity in, and thickness of, a possible S layer at Venus (Cloutier et al., 1987) am presented. If an S layer exists, it is only for extreme conditions of the solar wind. A mechanism for formation of magnetic Topes in the Venus ionosphere is also proposed. C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERE BRANCH,GREENBELT,MD 20771. NR 22 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 MAR 1 PY 1993 VL 98 IS A3 BP 3659 EP 3667 DI 10.1029/92JA00444 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900017 ER PT J AU BAKER, DN PULKKINEN, TI MCPHERRON, RL CRAVEN, JD FRANK, LA ELPHINSTONE, RD MURPHREE, JS FENNELL, JF LOPEZ, RE NAGAI, T AF BAKER, DN PULKKINEN, TI MCPHERRON, RL CRAVEN, JD FRANK, LA ELPHINSTONE, RD MURPHREE, JS FENNELL, JF LOPEZ, RE NAGAI, T TI CDAW-9 ANALYSIS OF MAGNETOSPHERIC EVENTS ON MAY 3, 1986 - EVENT-C SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SUBSTORM GROWTH-PHASE; HOT TENUOUS PLASMAS; TAIL CURRENT SHEET; ELECTRON ANISOTROPIES; ENERGETIC PARTICLES; EARTHS MAGNETOTAIL; BOUNDARY-LAYERS; AURORAL IMAGER; CURRENT WEDGE; FIELD MODEL AB The ninth Coordinated Data Analysis Workshop (CDAW 9) focused upon, several intervals within the PROMIS period (March-June 1986). Event interval C comprised the period 0000-1200 UT on May 3, 1986, which was a highly disturbed time near the end of a geomagnetic storm interval. A very large substorm early in the period commenced at 0111 UT and had a peak AE index value of approximately 1500 nT. Subsequent activity was lower, but at least three other substorms occurred at 2-3 hour intervals. The substorms on May 3 were well observed by a variety of satellites including ISEE 1, 2, and IMP 8 in the magnetotail plus SCATHA, GOES, GMS, and LANL spacecraft at or near geostationary orbit. A particularly important feature of the 0111 UT substorm was the simultaneous imaging of the southern auroral oval by DE 1 and of the northern auroral oval by Viking. The excellent constellation of spacecraft near local midnight in the radial range 5-9 R(E) made it possible to study the strong cross-tail current development during the substorm growth phase and the current disruption and current wedge development during the expansion phase. We use a time-evolving magnetic field model to map observed auroral features out into the magnetospheric equatorial plane. There was both a dominant eastward and a weaker westward progression of activity following the expansion phase. A clear latitudinal separation (greater than or similar to 10-degrees) of the initial region of auroral brightening and the region of intense westward electrojet current was identified. The combined ground, near-tail, and imaging data for this event provided an unprecedented opportunity to investigate tail current development, field line mapping, and substorm onset mechanisms. We find evidence for strong current diversion within the near-tail plasma sheet during the late growth phase and strong current disruption and field-aligned current formation from deeper in the tail at substorm onset. We conclude that these results are consistent with a model of magnetic neutral line formation in the late growth phase which causes plasma sheet current diversion before the substorm onset. The expansion phase onset occurs considerably later due to reconnection of lobelike magnetic field lines and roughly concurrent cross-tail disruption in the inner plasma sheet region. C1 FINNISH METEOROL INST,HELSINKI,FINLAND. METEOROL RES INST,IBARAKI,JAPAN. AEROSP CORP,EL SEGUNDO,CA 90245. UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. UNIV CALGARY,CALGARY T2N 1N4,ALBERTA,CANADA. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99701. UNIV ALASKA,DEPT PHYS,FAIRBANKS,AK 99701. UNIV IOWA,IOWA CITY,IA 52242. RP BAKER, DN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Pulkkinen, Tuija/D-8403-2012; OI Pulkkinen, Tuija/0000-0002-6317-381X; Lopez, Ramon/0000-0001-5881-1365 NR 52 TC 72 Z9 72 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 JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1993 VL 98 IS A3 BP 3815 EP 3834 DI 10.1029/92JA02475 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900031 ER PT J AU HESSE, M BIRN, J AF HESSE, M BIRN, J TI 3-DIMENSIONAL MAGNETOTAIL EQUILIBRIA BY NUMERICAL RELAXATION TECHNIQUES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOSPHERIC MAGNETIC-FIELD; DIFFERENT DISTURBANCE LEVELS; GLOBAL QUANTITATIVE MODELS; SUBSTORM CURRENT WEDGE; GEOMAGNETIC-FIELD; CISLUNAR MAGNETOSPHERE; ALIGNED CURRENTS; CURRENT SYSTEM; TAIL; RECONNECTION AB A numerical method to iteratively approach three-dimensional magnetostatic force equilibria is presented. The emphasis of the modeling is on the development of a suitable model of the Earth's magnetotail, including a portion of the inner magnetosphere, i.e., on models which violate the ''tail approximation'' commonly employed in analytical models. The numerical approach will be discussed and compared to methods developed for laboratory plasma physics. The method is then applied, as a first example, to the magnetotail outside of 10 R(E) using Tsyganenko's (1987) model for the quiet magnetosphere as an initial condition. We discuss the changes of the magnetic field necessary to yield an equilibrium configuration and the resulting distribution of the self-consistently derived pressure. At last we will show that a self-consistent magnetotail equilibrium based on a close approximation to Tsyganenko's model requires a region 1 type current system which is not present in the initial configuration. RP NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, CODE 696, GREENBELT, MD 20771 USA. RI Hesse, Michael/D-2031-2012 NR 36 TC 51 Z9 52 U1 0 U2 3 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 MAR 1 PY 1993 VL 98 IS A3 BP 3973 EP 3982 DI 10.1029/92JA02905 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP929 UT WOS:A1993KP92900043 ER PT J AU SCOTT, MA GILBERT, MG DEMEO, ME AF SCOTT, MA GILBERT, MG DEMEO, ME TI ACTIVE VIBRATION DAMPING OF THE SPACE-SHUTTLE REMOTE MANIPULATOR SYSTEM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA GUIDANCE, NAVIGATION, AND CONTROL CONF CY AUG 12-14, 1991 CL NEW ORLEANS, LA SP AMER INST AERONAUT & ASTRONAUT ID FREQUENCY AB Controls-structures interaction is a technology currently under development for application to large flexible space vehicles. The goal of this technology is the improvement of spacecraft performance through active control of the structural dynamic response of the vehicle. This goal is particularly important for modern spacecraft designs where large size and reduced stiffness make structural response a significant contributor to vehicle dynamics. Analysis and design methods have been developed to analyze and predict flexible spacecraft performance, but the technology remains largely unvalidated by hardware experiments, demonstrations, or applications, particularly in-space flight applications. One potential application considered is to provide active damping augmentation of the Space Shuttle remote manipulator system. The objective of actively damping the manipulator is to demonstrate improved structural dynamic response following payload maneuvers and Shuttle reaction control system thruster firings. This paper describes an initial analysis effort to determine the feasibility of controlling the flexible dynamic response of the arm. The approach to the study is summarized and results from both linear and nonlinear performance analyses of candidate control laws are presented. Results indicate that significant improvement in dynamic response can be achieved through active control if measured arm tip acceleration was made available for feedback. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. CHARLES STARK DRAPER LAB INC,DIV DYNAM & CONTROL,CAMBRIDGE,MA 02139. RP SCOTT, MA (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT CONTROLS BRANCH,HAMPTON,VA 23665, USA. NR 14 TC 14 Z9 15 U1 1 U2 3 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 MAR-APR PY 1993 VL 16 IS 2 BP 275 EP 280 DI 10.2514/3.56598 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA KR254 UT WOS:A1993KR25400008 ER PT J AU MAGHAMI, PG JOSHI, SM AF MAGHAMI, PG JOSHI, SM TI SENSOR-ACTUATOR PLACEMENT FOR FLEXIBLE STRUCTURES WITH ACTUATOR DYNAMICS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA GUIDANCE, NAVIGATION, AND CONTROL CONF CY AUG 12-14, 1991 CL NEW ORLEANS, LA SP AMER INST AERONAUT & ASTRONAUT ID LINEAR-MULTIVARIABLE SYSTEMS; LARGE SPACE STRUCTURES; ROOT LOCI; ZEROS AB A novel approach for placement of sensors and actuators in control of flexible space structures is developed. Using an approximation of the control forces and output measurements by spatially continuous functions, the approach follows a nonlinear programming technique to determine optimal locations for sensors and actuators. Two different criteria are considered for the placement of sensors and actuators. The first criterion optimizes the location of the sensors and actuators in order to move the transmission zeros of the system farther to the left of the imaginary axis. The second criterion, however, places the sensors and actuators to optimize a function of the singular values of the Hankel matrix, which includes both measures of controllability and observability. Moreover, the effect of actuator dynamics in the placement of sensors and actuators is investigated. RP MAGHAMI, PG (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 230,HAMPTON,VA 23681, USA. NR 20 TC 11 Z9 12 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 MAR-APR PY 1993 VL 16 IS 2 BP 301 EP 307 DI 10.2514/3.56599 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA KR254 UT WOS:A1993KR25400012 ER PT J AU JUANG, JN PHAN, M HORTA, LG LONGMAN, RW AF JUANG, JN PHAN, M HORTA, LG LONGMAN, RW TI IDENTIFICATION OF OBSERVER KALMAN FILTER MARKOV PARAMETERS - THEORY AND EXPERIMENTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA GUIDANCE, NAVIGATION, AND CONTROL CONF CY AUG 12-14, 1991 CL NEW ORLEANS, LA SP AMER INST AERONAUT & ASTRONAUT AB This paper discusses an algorithm to compute the Markov parameters of an observer or Kalman filter from experimental input and output data. The Markov parameters can then be used for identification of a state-space representation, with associated Kalman or observer gain, for the purpose of controller design. The algorithm is a nonrecursive matrix version of two recursive algorithms developed in previous works for different purposes, and the relationship between these other algorithms is developed. The new matrix formulation here gives insight into the existence and uniqueness of solutions of certain equations and offers bounds on the proper choice of observer order. It is shown that if one uses data containing noise and seeks the fastest possible deterministic observer, the deadbeat observer, one instead obtains the Kalman filter, which is the fastest possible observer in the stochastic environment. The results of the paper are demonstrated in numerical studies and experiments on the Hubble space telescope. C1 COLUMBIA UNIV,NEW YORK,NY 10027. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,SPACE DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 15 TC 154 Z9 165 U1 1 U2 5 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 MAR-APR PY 1993 VL 16 IS 2 BP 320 EP 329 DI 10.2514/3.21006 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA KR254 UT WOS:A1993KR25400014 ER PT J AU HORTA, LG PHAN, M JUANG, JN LONGMAN, RW SULLA, JL AF HORTA, LG PHAN, M JUANG, JN LONGMAN, RW SULLA, JL TI FREQUENCY-WEIGHTED SYSTEM-IDENTIFICATION AND LINEAR QUADRATIC CONTROLLER-DESIGN SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA GUIDANCE, NAVIGATION, AND CONTROL CONF CY AUG 12-14, 1991 CL NEW ORLEANS, LA SP AMER INST AERONAUT & ASTRONAUT AB Application of filters for the frequency weighting of Markov parameters (pulse response functions) is described in relation to system/observer identification. The time domain identification approach recovers a model that has a pulse response weighted according to frequency. The identified model is composed of the original system and filters. The augmented system occurs in a form that can be used directly for frequency-weighted linear quadratic controller design. Data from either single or multiple experiments can be used to recover the Markov parameters. Measured acceleration signals from a truss structure are used for system identification and the model obtained is for frequency-weighted controller design. The procedure makes the identification and controller design complementary problems. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP HORTA, LG (reprint author), NASA,LANGLEY RES CTR,NATL RES COUNCIL,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 13 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1993 VL 16 IS 2 BP 330 EP 336 DI 10.2514/3.21007 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA KR254 UT WOS:A1993KR25400015 ER PT J AU FARMER, SC DELLACORTE, C BOOK, PO AF FARMER, SC DELLACORTE, C BOOK, PO TI SLIDING WEAR OF SELF-MATED AL2O3-SIC WHISKER-REINFORCED COMPOSITES AT 23-1200-DEGREES-C SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SILICON-CARBIDE WHISKERS; SIC WHISKERS; ALUMINA; MICROSTRUCTURE AB Microstructural changes occurring during sliding wear of self-mated Al2O3-SiC whisker-reinforced composites were studied using optical, scanning electron Microscopy and transmission electron microscopy. Pin-on-disc specimens were slid in air at 2.7 m s-1 sliding velocity under a 26.5 N load for 1 h. Wear tests were conducted at 23, 600, 800 and 1200-degrees-C. Mild wear with a wear factor of 2.4 x 10(-7) - 1.5 x 10(-6) mm3 N-1 m-1 was experienced at all test temperatures. The composite showed evidence of wear by fatigue mechanisms at 800-degrees-C and below. Tribochemical reaction (SiC oxidation and reaction Of SiO2 and Al2O3) leads to intergranular failure at 1200-degrees-C. Distinct microstructural differences existing at each test temperature are reported. C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP FARMER, SC (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 17 TC 8 Z9 8 U1 2 U2 2 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD MAR 1 PY 1993 VL 28 IS 5 BP 1147 EP 1154 DI 10.1007/BF01191945 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA KR346 UT WOS:A1993KR34600003 ER PT J AU SMITH, MW JARRETT, O ANTCLIFF, RR NORTHAM, GB CUTLER, AD TAYLOR, DJ AF SMITH, MW JARRETT, O ANTCLIFF, RR NORTHAM, GB CUTLER, AD TAYLOR, DJ TI COHERENT ANTI-STOKES-RAMAN SPECTROSCOPY TEMPERATURE-MEASUREMENTS IN A HYDROGEN-FUELED SUPERSONIC COMBUSTOR SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Coherent anti-Stokes Raman spectroscopy (CARS) thermometry has been used to obtain static temperature cross sections in a three-dimensional supersonic combustor flowfield. Data were obtained in three spanwise planes downstream of a single normal fuel injector which was located downstream of a rearward-facing step. The freestream flow was nominally Mach 2 and was combustion heated to a total temperature of 1440 K (yielding a static temperature of about 800 K in the freestream) to simulate the inflow to a combustor operating at a flight Mach number of about 5.4. Since a broadband probe laser was used an instantaneous temperature sample was obtained with each laser shot at a repetition rate of 10 Hz. Thus root-mean-square (rms) temperatures and temperature probability density functions (pdf's) were obtained in addition to mean temperatures. C1 NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,OPT SPECT SECT,HAMPTON,VA 23681. GEORGE WASHINGTON UNIV,HAMPTON,VA 23681. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP SMITH, MW (reprint author), NASA,LANGLEY RES CTR,EXPTL METHODS BRANCH,COMBUST FUNDAMENTALS GRP,HAMPTON,VA 23681, USA. NR 6 TC 10 Z9 10 U1 0 U2 2 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 MAR-APR PY 1993 VL 9 IS 2 BP 163 EP 168 DI 10.2514/3.23604 PG 6 WC Engineering, Aerospace SC Engineering GA KR542 UT WOS:A1993KR54200002 ER PT J AU ZELEZNIK, FJ AF ZELEZNIK, FJ TI EVALUATION OF THE MUNICH METHOD FOR MODELING ROCKET ENGINE PERFORMANCE SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A new procedure, dubbed the Munich Method, has been proposed recently for the modeling of rocket engine performance. The author of the Munich Method claims it to be an extension and improvement of the thermodynamic procedures used to model rocket engines in the NASA-Lewis chemical equilibrium program. An examination of the Munich Method shows that it contains several flaws. If these defects are corrected then the Munich Method will produce results identical to those generated by the NASA-Lewis Code. RP ZELEZNIK, FJ (reprint author), NASA,LEWIS RES CTR,AEROTHERMOCHEM BRANCH,MAIL STOP 5-11,CLEVELAND,OH 44135, USA. NR 9 TC 2 Z9 2 U1 1 U2 3 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 MAR-APR PY 1993 VL 9 IS 2 BP 191 EP 196 DI 10.2514/3.23608 PG 6 WC Engineering, Aerospace SC Engineering GA KR542 UT WOS:A1993KR54200006 ER PT J AU CHOY, FK RUAN, YF ZAKRAJSEK, JJ OSWALD, FB AF CHOY, FK RUAN, YF ZAKRAJSEK, JJ OSWALD, FB TI MODAL SIMULATION OF GEAR BOX VIBRATION WITH EXPERIMENTAL CORRELATION SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID TRANSMISSION; DYNAMICS; SYSTEM AB A newly developed global dynamic model was used to simulate the dynamics of a gear noise rig at the NASA Lewis Research Center. Experimental results from the test rig were used to verify the analytical model. In this model, the number of degrees of freedom (DOF) of the system are reduced by transforming the system equations of motion into modal coordinates. The vibration of the individual gear-shaft systems is coupled through the gear-mesh forces. A three-dimensional bearing model was used to couple the casing structural vibration to the gear rotor dynamics. The system of modal equations is solved to predict the resulting vibration at several locations on the test rig. Experimental vibrational data were measured at several running speeds and were compared to the predictions of the global dynamic model. There was excellent agreement between the analytical and experimental vibration results. C1 NASA,LEWIS RES CTR,MECH SYST TECHNOL BRANCH,CLEVELAND,OH 44135. RP CHOY, FK (reprint author), UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325, USA. NR 16 TC 11 Z9 13 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 MAR-APR PY 1993 VL 9 IS 2 BP 301 EP 306 DI 10.2514/3.23622 PG 6 WC Engineering, Aerospace SC Engineering GA KR542 UT WOS:A1993KR54200020 ER PT J AU DELLACORTE, C STEINETZ, BM AF DELLACORTE, C STEINETZ, BM TI RELATIVE SLIDING DURABILITY OF 2 CANDIDATE HIGH-TEMPERATURE OXIDE FIBER SEAL MATERIALS SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID WEAR AB A test program to determine the relative sliding durability of two candidate ceramic fibers for high-temperature sliding seal applications is described. Pin-on-disk tests were used to evaluate potential seal materials. Friction was measured during the tests, and fiber wear (indicated by the extent of fibers broken in a test bundle or yarn) was measured at the end of a test. In general, friction and wear increase with increased test temperature. The relative fiber durability correlates with tensile strength, indicating that tensile data, which is more readily available than sliding durability data, may be useful in predicting fiber wear behavior under various conditions. A dimensional analysis of the wear data shows that the fiber durability is related to a dimensionless parameter which represents the ratio of the fiber strength to the fiber stresses imposed by sliding. C1 NASA,LEWIS RES CTR,DIV STRUCT,CLEVELAND,OH 44135. RP DELLACORTE, C (reprint author), NASA,LEWIS RES CTR,DIV MAT,CLEVELAND,OH 44135, USA. NR 13 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1993 VL 9 IS 2 BP 307 EP 312 DI 10.2514/3.23623 PG 6 WC Engineering, Aerospace SC Engineering GA KR542 UT WOS:A1993KR54200021 ER PT J AU COLBAUGH, R SERAJI, H GLASS, K AF COLBAUGH, R SERAJI, H GLASS, K TI DIRECT ADAPTIVE IMPEDANCE CONTROL OF ROBOT MANIPULATORS SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID CONFIGURATION CONTROL; REDUNDANT ROBOTS; COMPLIANT MOTION; ADAPTATION AB This article presents an adaptive scheme for controlling the end-effector impedance of robot manipulators. The proposed control system consists of three subsystems: a simple ''filter'' that characterizes the desired dynamic relationship between the end-effector position error and the end-effector/environment contact force, an adaptive controller that produces the Cartesian-space control input required to provide this desired dynamic relationship, and an algorithm for mapping the Cartesian-space control input to a physically realizable joint-space control torque. The controller does not require knowledge of either the structure or the parameter values of the robot dynamics and is implemented without calculation of the robot inverse kinematic transformation. As a result, the scheme represents a general and computationally efficient approach to controlling the impedance of both nonredundant and redundant manipulators. Furthermore, the method can be applied directly to trajectory tracking in free-space motion by removing the impedance filter. Computer simulation results are given for a planar four degree-of-freedom redundant robot under adaptive impedance control. These results demonstrate that accurate end-effector impedance control and effective redundancy utilization can be achieved simultaneously by using the proposed controller. C1 JET PROP LAB,PASADENA,CA 91109. NEW MEXICO STATE UNIV,DEPT IND ENGN,LAS CRUCES,NM 88001. RP COLBAUGH, R (reprint author), NEW MEXICO STATE UNIV,DEPT MECH ENGN,LAS CRUCES,NM 88001, USA. NR 33 TC 42 Z9 42 U1 3 U2 7 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD MAR PY 1993 VL 10 IS 2 BP 217 EP 248 DI 10.1002/rob.4620100205 PG 32 WC Robotics SC Robotics GA KL396 UT WOS:A1993KL39600004 ER PT J AU PAPADOPOULOS, P TAUBER, ME CHANG, ID AF PAPADOPOULOS, P TAUBER, ME CHANG, ID TI HEATSHIELD EROSION IN A DUSTY MARTIAN ATMOSPHERE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID STORMS; MARS AB The effects of dust particle impacts on the erosion of the forebody heatshield were calculated for a 26 m diameter aerobraking vehicle entering a dusty Martian atmosphere at 8600 m/s. An explicit, thin-layer, Navier-Stokes code was used to compute the dustless flowfield about the vehicle for the actual Martian atmospheric composition. The deceleration and melting of 1-19 mum diameter dust particles within the forebody shock layer were computed. All particles began vaporizing shortly after entering the shock layer, but most survived to hit the heatshield surface. The two different hestshield materials considered were Shuttle ceramic tiles and the ablator used on the Apollo capsule. For a vehicle with a ballistic coefficient of 200 kg/m2, the heatshield surfaces experienced an average of about 7 mm of surface erosion. For the ablator, the increase in the forebody thermal protection mass was 29%, or about 1.3% of the vehicle's mass. This modest mass penalty does not compromise the use of aerobraking at Mars. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP PAPADOPOULOS, P (reprint author), STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305, USA. NR 37 TC 10 Z9 10 U1 0 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 MAR-APR PY 1993 VL 30 IS 2 BP 140 EP 151 DI 10.2514/3.11522 PG 12 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600002 ER PT J AU TAUBER, ME YANG, L PATERSON, J AF TAUBER, ME YANG, L PATERSON, J TI FLAT SURFACE HEAT-TRANSFER CORRELATIONS FOR MARTIAN ENTRY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Analytic expressions have been derived for estimating the nonablating laminar and turbulent boundary-layer convective heating rates on inclined flat surfaces for the Martian atmosphere in thermochemical equilibrium. The equations are valid in the speed and altitude regime where aerobraking would occur at Mars. Comparisons with limited experimental measurements and calculations for CO2 (the Martian atmosphere is 95.6% CO2) yielded reasonably good agreement, especially for the ratios of heating rates in CO2 to those in air at the same conditions. In the aerobraking speed regime, the laminar flat surface boundary layer heating rates are 15-25% greater at Mars than in air. The differences between the turbulent heating rates are even more pronounced. The turbulent heating rates can be over 50% greater at Mars than in air at the same flight conditions. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP TAUBER, ME (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 29 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 MAR-APR PY 1993 VL 30 IS 2 BP 164 EP 169 DI 10.2514/3.11524 PG 6 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600004 ER PT J AU CHEN, FJ WILKINSON, SP BECKWITH, IE AF CHEN, FJ WILKINSON, SP BECKWITH, IE TI GORTLER INSTABILITY AND HYPERSONIC QUIET NOZZLE DESIGN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A new concept for nozzle design incorporating slow expansion rates and a radial flow region has been implemented for a hypersonic (Mach 6) nozzle. Data indicate that these modifications have the potential for providing a large increase in the length of the quiet test core by postponing the initiation and decreasing the growth of Gortler vortices on the concave region of the nozzle walls. The concept was verified previously by experimental data from the advanced Mach 3.5 axisymmetric quiet nozzle. To verify the concept for hypersonic flow, the new advanced Mach 6 axisymmetric quiet nozzle was built and tested at NASA Langley. Preliminary experimental results on the extent of laminar wall boundary-layer flow are compared with data from the Mach 5 axisymmetric, rapid expansion, pilot quiet nozzle and with theoretical predictions based on linear stability theory. The Reynolds numbers based on the measured length of the quiet test core for the new nozzle are in agreement with the trend of theoretical predictions in the low unit Reynolds number range. With further improvement of the nozzle finish, especially in the critical throat region, the nozzle performance can be expected to approach the design conditions. C1 GEORGE WASHINGTON UNIV,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,JOINT INST ADV FLIGHT SCI,HAMPTON,VA 23681. RP CHEN, FJ (reprint author), NASA,LANGLEY RES CTR,EXPTL METHODS BRANCH,DIV FLUID MECH,HAMPTON,VA 23681, USA. NR 33 TC 12 Z9 12 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 MAR-APR PY 1993 VL 30 IS 2 BP 170 EP 175 DI 10.2514/3.11525 PG 6 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600005 ER PT J AU SCIALDONE, JJ AF SCIALDONE, JJ TI SPACECRAFT THERMAL BLANKET CLEANING - VACUUM BAKING OR GASEOUS FLOW PURGING SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The mass losses and the outgassing rates per unit area of three thermal blankets consisting of various combinations of Mylar and Kapton, with interposed Dacron nets, have been measured with an analytical balance using two methods. The blankets at 25-degrees-C were either outgassed in vacuum for 20 h, or were purged with a dry nitrogen flow of 8.5 X 10(-2) m3/h at 25-degrees-C for 20 h. The two methods have been compared for their effectiveness in cleaning the blankets for their use in space applications. The measurements were carried out using blanket strips and rolled-up blanket samples fitting the balance's cylindrical plenum. Also, temperature scanning tests were carried out to indicate the optimum temperatures for purging and for vacuum cleaning. The data indicate that the purging for 20 h with the N2 flow can accomplish the same level of cleaning provided by the vacuum with the blankets at 25-degrees-C for 20 h. In both cases, the rate of outgassing after 20 h is reduced by three orders of magnitude, and the weight losses are in the range of 10E-4 g/cm2. Equivalent mass loss time constants, regained mass in air as a function of time, and other parameters were obtained for these blankets. RP SCIALDONE, JJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,POLYMERS SECT,GREENBELT,MD 20771, USA. NR 5 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 MAR-APR PY 1993 VL 30 IS 2 BP 208 EP 215 DI 10.2514/3.11529 PG 8 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600009 ER PT J AU SIMPSON, JP WITTEBORN, FC GRAPS, A FAZIO, GG KOCH, DG AF SIMPSON, JP WITTEBORN, FC GRAPS, A FAZIO, GG KOCH, DG TI PARTICLE SIGHTINGS BY THE INFRARED TELESCOPE ON SPACELAB-2 SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID OPTICAL-CONSTANTS AB Part of the objective of the cooled infrared telescope on Spacelab 2 was to determine the particle environment around the Space Shuttle. The telescope scanned the sky in six wavelength bands ranging from 2 to 100 mum with high time resolution. Dust particles could be identified from their particular signature in the data stream. Particle data from about 4 h early in the mission were analyzed in terms of size, color temperature, velocity, and time. The 1100 particles that were seen were slow moving and ranged in color temperature from 190 to 350 K with a few much hotter. The minimum detectable diameter is between 5 and 15 mum, depending on temperature. The size distribution resembles sample distributions collected at a Shuttle preparation facility. Although particle detection rates varied widely with time, no specific events were identified to be associated with particle production. It was not possible to determine the particle composition, although it was probably not ice. C1 STERLING SOFTWARE,PALO ALTO,CA. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP SIMPSON, JP (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 12 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 MAR-APR PY 1993 VL 30 IS 2 BP 216 EP 221 DI 10.2514/3.11530 PG 6 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600010 ER PT J AU VERDERAIME, V AF VERDERAIME, V TI AEROSTRUCTURAL SAFETY FACTOR CRITERIA USING DETERMINISTIC RELIABILITY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The primary function of most metallic structures is to sustain operational loads with no detrimental deformation. The current practice of specifying a universal ultimate safety factor, or reliability, biases the operation margin by the selection of material. By expressing the deterministic safety factor in probabilistic tolerance limits, the included three safety design factors are specified independently by loads, materials, and stress criteria. The minimum limit of the stress safety design factor was determined to be the ultimate-to-yield stress ratio. This ratio was combined with estimated modeling and complexity uncertainty factors to redefine the conventional safety factor. The metallic structural safety with the modified conventional safety factor and the loads and material safety design factors was expressed by a safety index and reliability. Although the resulting reliability varies with material selection, the suggested criteria provide a uniformly efficient and safe operational structure. RP VERDERAIME, V (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB,HUNTSVILLE,AL 35812, USA. NR 5 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1993 VL 30 IS 2 BP 244 EP 247 DI 10.2514/3.11533 PG 4 WC Engineering, Aerospace SC Engineering GA KW276 UT WOS:A1993KW27600014 ER PT J AU TAO, WK SIMPSON, J SUI, CH FERRIER, B LANG, S SCALA, J CHOU, MD PICKERING, K AF TAO, WK SIMPSON, J SUI, CH FERRIER, B LANG, S SCALA, J CHOU, MD PICKERING, K TI HEATING, MOISTURE, AND WATER BUDGETS OF TROPICAL AND MIDLATITUDE SQUALL LINES - COMPARISONS AND SENSITIVITY TO LONGWAVE RADIATION SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MESOSCALE CONVECTIVE SYSTEM; COPT 81 EXPERIMENT; 10-11 JUNE 1985; CLOUD CLUSTERS; NUMERICAL-SIMULATION; STRATIFORM REGION; PARAMETERIZATION SCHEMES; TRANSMISSION FUNCTIONS; STORM DYNAMICS; DEEP CUMULUS AB A two-dimensional, time-dependent, and nonhydrostatic numerical cloud model is used to estimate the heating (Q1), moisture (Q2), and water budgets in the convective and stratiform regions for a tropical and a midlatitude squall line (EMEX and PRE-STORM). The model is anelastic and includes a parameterized three-class ice-phase microphysical scheme and longwave radiative transfer processes. A quantitative estimate of the impact of the longwave radiative cooling on the total surface precipitation as well as on the development and structure of these two squall lines is presented. It was found that the vertical eddy moisture fluxes are a major contribution to the model-derived Q2 budgets in both squall cases. A distinct midlevel minimum in the Q2 profile for the EMEX case is due to vertical eddy transport in the convective region. On the other hand, the contribution to the Q1 budget by the cloud-scale fluxes is minor for the EMEX case. In contrast, the vertical eddy heat flux is relatively important for the PRE-STORM case due to the stronger vertical velocities present in the PRE-STORM convective cells. It was found that the convective region plays an important role in the generation of stratiform rainfall for both cases. Although the EMEX case has more stratiform rainfall than its PRE-STORM counterpart, the relative contribution to the stratiform water budget made by the horizontal transfer of hydrometeors from the convective region is less. But the transfer of condensate from the convective region became relatively less important with time in the stratiform water budget of the PRE-STORM system as it developed from its initial stage, such that the relative contribution to the stratiform water budget made by the horizontal transfer of hydrometeors from the convective region is similar at the mature stages of both systems. Longwave radiative cooling enhanced the total surface precipitation about 14% and 31% over a 16-h simulation time for the PRE-STORM and EMEX cases, respectively. The relative contribution to the stratiform water budget from the convective region is, however, more sensitive to the longwave radiative cooling for the PRE-STORM case than for the EMEX case. These results are due to the relatively moist environment and comparatively earlier development of the stratiform cloud in the EMEX squall system. Nevertheless, the effect of radiative cooling is shown to increase as systems age in both cases. It was also determined that the Q1 and Q2 budgets in the convective and stratiform regions are only quantitatively, not qualitatively, altered by the inclusion or exclusion of longwave radiative transfer processes. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. SCI SYST & APPLICAT INC,GREENBELT,MD. NATL RES COUNCIL,RRA,WASHINGTON,DC 20418. RP TAO, WK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771, USA. RI Pickering, Kenneth/E-6274-2012 NR 55 TC 201 Z9 211 U1 1 U2 9 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 MAR 1 PY 1993 VL 50 IS 5 BP 673 EP 690 DI 10.1175/1520-0469(1993)050<0673:HMAWBO>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KT136 UT WOS:A1993KT13600001 ER PT J AU OGBUJI, LUT JAYNE, DT AF OGBUJI, LUT JAYNE, DT TI MECHANISM OF INCIPIENT OXIDATION OF BULK CHEMICAL VAPOR-DEPOSITED SI3N4 SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID SILICON-NITRIDE FILMS; RAY PHOTOELECTRON-SPECTROSCOPY; OXIDIZED-SILICON; OXYNITRIDE FILMS; THIN-FILMS; DIOXIDE; SIO2-FILMS; SURFACE; AMMONIA; OXYGEN AB X-ray photoelectron spectroscopy was employed, in conjunction with ion bombardment, to analyze the chemical composition profile across thin (<50 nm) oxide films on chemically vapor deposited Si3N4. The thermal oxides were grown in dry oxygen at 1100-degrees-C on samples with or without native oxide film (formed in room air). The results show that the thermal oxidation product was silicon oxynitride of graded N:O ratio, and that the presence of a native oxide film promotes the formation of a SiO2 crust Over the oxynitride. It is proposed that the fundamental mechanism of Si3N, oxidation is progressive O-for-N substitution in the silicon oxynitride unit tetrahedron, which is best designated SiN2-xO2+x, where x is also an index of depth. The corresponding equation for nonstoichiometric oxidation of Si3N4 describes a bulk (rather than an interface) reaction process, with significant implications for O2 and N2 fluxes and diffusivities. C1 SVERDRUP TECHNOL,CLEVELAND,OH 44070. CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44070. RP OGBUJI, LUT (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44070, USA. NR 35 TC 37 Z9 37 U1 0 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 MAR PY 1993 VL 140 IS 3 BP 759 EP 766 DI 10.1149/1.2056154 PG 8 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA KT622 UT WOS:A1993KT62200042 ER PT J AU HERRERAFIERRO, P JONES, WR PEPPER, SV AF HERRERAFIERRO, P JONES, WR PEPPER, SV TI INTERFACIAL CHEMISTRY OF A PERFLUOROPOLYETHER LUBRICANT STUDIED BY X-RAY PHOTOELECTRON-SPECTROSCOPY AND TEMPERATURE DESORPTION SPECTROSCOPY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID ION MASS-SPECTROMETRY; ATOMIC FORCE MICROSCOPY; POLYMERIC LIQUID-FILMS; PERFLUOROPOLYALKYLETHER OIL; PERFLUORINATED POLYETHER; ULTRAHIGH-VACUUM; STAINLESS-STEEL; SOLID-SURFACES; OXIDE SURFACES; ALUMINUM AB The interfacial chemistry of Fomblin Z25, a commercial perfluoropolyether used as lubricant for space applications, with different metallic surfaces-440 C steel, gold, and aluminum-was studied. Thin layers of Fomblin Z25 were evaporated onto the oxide-free substrates and the interfacial chemistry studied using x-ray photoelectron spectroscopy and temperature desorption spectroscopy. The reactions were induced by heating the substrate and by rubbing the substrate with a steel ball. Gold was found to be completely unreactive towards Fomblin at any temperature. Reaction at room temperature was observed only in the case of the aluminum substrate, the most reactive towards Fomblin Z25 of the substrates studied. It was necessary to heat the 440C steel substrate to 190-degrees-C to induce decomposition of the fluid. The degradation of the fluid was indicated by the formation of a debris layer at the interface, This debris layer, composed of inorganic and organic reaction products, when completely formed, passivated the surface from further attack to the Fomblin on top. The tribologically induced reactions on 440C steel formed a debris layer of similar chemical characteristics to the thermally induced layer. In all cases, the degradation reaction resulted in preferential consumption of the difluoroformyl carbon (-OCF2O-). RP HERRERAFIERRO, P (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 67 TC 55 Z9 55 U1 4 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAR-APR PY 1993 VL 11 IS 2 BP 354 EP 367 DI 10.1116/1.578737 PG 14 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA KT850 UT WOS:A1993KT85000012 ER PT J AU HOOKER, SB MCCLAIN, CR HOLMES, A AF HOOKER, SB MCCLAIN, CR HOLMES, A TI OCEAN COLOR IMAGING - CZCS TO SEAWIFS SO MARINE TECHNOLOGY SOCIETY JOURNAL LA English DT Article ID SCANNER; NIMBUS-7; PHYTOPLANKTON; CALIBRATION; IMAGERY; SHIP AB The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) will be the first ocean color satellite since the Nimbus-7 Coastal Zone Color Scanner (CZCS), which ceased sending data in 1986 after more than seven years of operation. Unlike the CZCS, which was conceived as a proof-of-concept experiment, SeaWiFS will provide routine global coverage every two days and is designed to provide estimates of photosynthetic pigment concentrations of sufficient accuracy for use in quantitative studies of the ocean's primary productivity and biogeochemistry. The SeaWiFS instrument is described within a comparative review of the CZCS mission, from which the many design features employed to improve radiometric accuracy and minimize instrumental effects are elucidated. The former includes the use of solar and lunar calibration signals, and an internal electric signal to track long-term gain shifts, while the latter includes detector nonlinearity, offsets, bright target recovery, parasitic response, filter spectral shifts with temperature and humidity, out-of-band radiation, polarization sensitivity, stray light, mirror coating degradation, coherent noise, and electromagnetic interference (EMI) effects. C1 HUGHES SANTA BARBARA RES CTR,GOLETA,CA. RP HOOKER, SB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SEAWIFS PROJECT,GREENBELT,MD 20771, USA. RI Hooker, Stanford/E-2162-2012 NR 35 TC 21 Z9 21 U1 1 U2 2 PU MARINE TECHNOLOGY SOC INC PI WASHINGTON PA C/O I CLAYION MATTHEWS, 1828 L ST, NW, 9TH FL, WASHINGTON, DC 20036 SN 0025-3324 J9 MAR TECHNOL SOC J JI Mar. Technol. Soc. J. PD SPR PY 1993 VL 27 IS 1 BP 3 EP 15 PG 13 WC Engineering, Ocean; Oceanography SC Engineering; Oceanography GA LH924 UT WOS:A1993LH92400001 ER PT J AU VARY, A AF VARY, A TI NDE OF THE UNIVERSE - NEW WAYS TO LOOK AT OLD FACTS SO MATERIALS EVALUATION LA English DT Editorial Material RP VARY, A (reprint author), NASA,LEWIS RES CTR,STRUCT INTEGR BRANCH,MS 6-1,21000 BROOK PK RD,CLEVELAND,OH 44135, USA. NR 3 TC 1 Z9 1 U1 0 U2 0 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 MAR PY 1993 VL 51 IS 3 BP 380 EP 387 PG 8 WC Materials Science, Characterization & Testing SC Materials Science GA KR562 UT WOS:A1993KR56200004 ER PT J AU WANGLER, TG SWETITS, JJ BUONCRISTIANI, AM AF WANGLER, TG SWETITS, JJ BUONCRISTIANI, AM TI TEMPORAL MODEL OF AN OPTICALLY PUMPED CO-DOPED SOLID-STATE LASER SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article AB Currently, research is being conducted on the optical properties of materials associated with the development of solid-state lasers in the 2 micron region. In support of this effort, a mathematical model describing the energy transfer in a holmium laser sensitized with thulium is developed. In this paper, we establish some qualitative properties of the solution of the model, such as non-negativity, boundedness, and integrability. A local stability analysis is then performed from which conditions for asymptotic stability are obtained. Finally, we report on our numerical analysis of the system and how it compares with experimental results. C1 OLD DOMINION UNIV,DEPT MATH,NORFOLK,VA 23508. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP WANGLER, TG (reprint author), ILLINOIS BENEDICTINE COLL,DEPT MATH & COMP SCI,LISLE,IL 60532, 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 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD MAR PY 1993 VL 17 IS 6 BP 67 EP 82 DI 10.1016/0895-7177(93)90197-7 PG 16 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA KX601 UT WOS:A1993KX60100008 ER PT J AU AIKIN, BJM COURTNEY, TH AF AIKIN, BJM COURTNEY, TH TI THE KINETICS OF COMPOSITE PARTICLE FORMATION DURING MECHANICAL ALLOYING SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article AB The kinetics of composite particle formation during attritor milling of insoluble binary elemental powders have been examined. The effects of processing conditions (i.e., mill power, temperature, and charge ratio) on these kinetics were studied. Particle size distributions and fractions of elemental and composite particles were determined as functions of milling time and processing conditions. This allowed the deduction of phenomenological rate constants describing the propensity for fracture and welding during processing. For the mill-operating conditions investigated, the number of particles in the mill generally decreased with milling time, indicating a greater tendency for particle welding than fracture. Moreover, a bimodal size distribution is often obtained as a result of preferential welding. Copper and chromium ''alloy'' primarily by encapsulation of Cr particles within Cu. This form of alloying also occurs in Cu-Nb alloys processed at low mill power and/or for short milling times. For other conditions, however, Cu-Nb alloys develop a lamellar morphology characteristic of mechanically alloyed two-phase ductile metals. Increasing mill power or charge (ball-to-powder weight) ratio (CR) increases the rate of composite particle formation. C1 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 21 TC 75 Z9 78 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD MAR PY 1993 VL 24 IS 3 BP 647 EP 657 DI 10.1007/BF02656633 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA KP614 UT WOS:A1993KP61400013 ER PT J AU FRENCH, BM AF FRENCH, BM TI METEORITICAL-SOCIETY CITATION FOR BARRINGER,J.PAUL AND THE BARRINGER-CRATER-COMPANY, 1992 JULY 30, COPENHAGEN, DENMARK SO METEORITICS LA English DT Item About an Individual RP FRENCH, BM (reprint author), NASA HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD MAR PY 1993 VL 28 IS 1 BP 7 EP 8 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LA778 UT WOS:A1993LA77800005 ER PT J AU TREIMAN, AH BARRETT, RA GOODING, JL AF TREIMAN, AH BARRETT, RA GOODING, JL TI PRETERRESTRIAL AQUEOUS ALTERATION OF THE LAFAYETTE (SNC) METEORITE SO METEORITICS LA English DT Article ID ABERT LAKE; AEM-TEM; TRANSFORMATION; FERRIHYDRITE; DIAGENESIS; HEMATITE; OREGON AB The Lafayette meteorite, a nakhlite of the SNC (Martian?)group, contains hydrous alteration materials as intergranular films and as veinlets and patches replacing olivine, pyroxenes, and high-Si glass. The alteration materials (''iddingsite'') consist of ferroan smectite clays, magnetite (or maghemite), and ferrihydrite, as shown by SEM and TEM. Three varieties of veinlets are present and formed in the order: coarse phyllosilicate; fine-grained (phyllosilicate-oxide), and porous oxide. Veinlets of fine-grained material cross-cut coarse phyllosilicate veinlets. The alteration materials are preterrestrial, as they are older than Lafayette's fusion crust, which is glassy and not affected by any alterations. Approaching the crust, the veinlets are progressively modified to the point of melting, and progressively depleted in adsorbed volatile constituents (S, Cl, and P). Bulk compositions of the alteration veinlets (SEM and TEM EDX) are consistent with the observed mineralogy, and suggest: that the smectite contains significant adsorbed S and Cl; that the ferrihydrite contains significant adsorbed S, but not Cl; that rare grains of sulfate (Ca?) and chloride (Na or K?) are present; and that the compositions of the alteration materials are approximated by Lafayette's olivine + high-Si glass + water. We estimate that Lafayette's alteration materials formed at less than 100-degrees-C. The oxidation potential of the water was near or slightly below that of the magnetite-hematite buffer. The presence of sulfate and chloride in discrete phases and as adsorbates on ferrihydrite and smectite suggests that the altering solutions were saline. However, relatively little mass was transferred into or out of Lafayette because the bulk composition of the alteration materials is nearly isochemical with a mixture of magmatic silicate phases and water. Chemical transport within Lafayette was also limited, as alteration materials preserve some chemical signature of their host minerals. Presence of alteration materials along only some grain boundaries and some cracks suggests that Lafayette was not soaked in fluid. These last two inferences suggest that the alteration of Lafayette took place during episodic infiltrations of small volumes of saline water. C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP LOCKHEED ENGN & SCI CO, JOHNSON SPACE CTR, C-23, HOUSTON, TX 77058 USA. NR 34 TC 164 Z9 164 U1 0 U2 8 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORITICS JI Meteoritics PD MAR PY 1993 VL 28 IS 1 BP 86 EP 97 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA LA778 UT WOS:A1993LA77800013 ER PT J AU MCCAMMON, D CUI, W JUDA, M MORGENTHALER, J ZHANG, J KELLEY, RL HOLT, SS MADEJSKI, GM MOSELEY, SH SZYMKOWIAK, AE AF MCCAMMON, D CUI, W JUDA, M MORGENTHALER, J ZHANG, J KELLEY, RL HOLT, SS MADEJSKI, GM MOSELEY, SH SZYMKOWIAK, AE TI THERMAL CALORIMETERS FOR HIGH-RESOLUTION X-RAY SPECTROSCOPY SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 6TH EUROPEAN SYMP ON SEMICONDUCTOR DETECTORS CY FEB 24-26, 1992 CL MILAN, ITALY ID NOISE AB Thermal detection of individual X-ray photons by small (0.5 x 0.5 mm) calorimeters has been used to achieve an energy resolution as good as 7.5 eV FWHM for 6 keV X-rays. Such detectors should have interesting applications in X-ray astronomy as well as laboratory spectroscopy, and they promise a high tolerance for embedded sources. Ideally, it should be possible to improve the resolution greatly by making smaller detectors or operating them at lower temperatures than the 50-100 mK currently used. However, there appear to be fairly fundamental limitations when semiconductor thermistors are used as the thermometer. When trying to achieve energy resolution of 0.1% or better, fluctuations in the thermalization efficiency of the detector must also be considered, and this places additional restrictions on suitable detector materials. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MCCAMMON, D (reprint author), UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706, USA. RI Moseley, Harvey/D-5069-2012; Kelley, Richard/K-4474-2012; OI Juda, Michael/0000-0002-4375-9688; Cui, Wei/0000-0002-6324-5772 NR 17 TC 60 Z9 60 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD MAR 1 PY 1993 VL 326 IS 1-2 BP 157 EP 165 DI 10.1016/0168-9002(93)90346-J PG 9 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA KP972 UT WOS:A1993KP97200023 ER PT J AU ROBINSON, DL CHEN, CC HEMMATI, H AF ROBINSON, DL CHEN, CC HEMMATI, H TI 10-MBPS ELECTROOPTIC RESONANT PHASE MODULATOR SO OPTICAL ENGINEERING LA English DT Article DE PHASE MODULATOR; OPTICAL COMMUNICATIONS; RESONANT MODULATOR; ELECTROOPTIC MODULATION; MODULATION; ELECTROOPTICS; FABRY-PEROT ID CAVITY AB A resonant cavity electro-optic phase modulator has been designed and implemented to operate at a data rate of 10 Mbps. The modulator consists of an electro-optic crystal located in a highly resonant cavity. The cavity is electro-optically switched on and off resonance, and the phase dispersion near the cavity resonance provides the output phase modulation. The performance of the modulator was measured by first heterodyne-detecting the signal to an intermediate frequency and then measuring the spectral characteristics using an rf spectrum analyzer. The measured phase shift is shown to be in good agreement with the theoretical predictions. Further theoretical analysis shows that the design of the modulator can be scaled to operate at 100 Mbps. RP ROBINSON, DL (reprint author), JET PROP LAB,OPT COMMUN GRP,MS 161-135,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 0 Z9 0 U1 0 U2 1 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 MAR PY 1993 VL 32 IS 3 BP 458 EP 463 DI 10.1117/12.61044 PG 6 WC Optics SC Optics GA KQ388 UT WOS:A1993KQ38800004 ER PT J AU DOWNIE, JD AF DOWNIE, JD TI CASE-STUDY OF BINARY AND TERNARY SYNTHETIC DISCRIMINANT FUNCTION FILTERS WITH SIMILAR IN-CLASS AND OUT-OF-CLASS IMAGES SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL PATTERN RECOGNITION; OPTICAL CORRELATORS; SYNTHETIC DISCRIMINANT FUNCTIONS; BINARY PHASE-ONLY FILTERS; TERNARY PHASE-AMPLITUDE FILTERS ID SPATIAL LIGHT-MODULATOR; PHASE-AMPLITUDE FILTERS; PATTERN-RECOGNITION; RATIO; FORMULATION; SIGNAL AB We compare computer simulation results of optical correlator performance using synthetic discriminant function filters encoded in binary phase versus ternary phase and amplitude for distortion-tolerant pattern recognition. We examine two different ternary filter formulations designed to enhance discrimination and SNR. The simulated situation is for very similar in-class and out-of-class images, which makes discrimination between the two sets difficult. The ultimate performance criterion of interest is the probability of correct identification in the presence of image noise, which we address as a function of the range of distortion tolerance offered by the filters. We find that the ternary filters offer improved system performance and greater possible distortion range in comparison to the binary filters, and in particular that the ternary filters with a region of support designed to enhance SNR have the best performance for the image sets studied here. Knowledge of the out-of-class images allows the filter designer to create filters that maximize the probability of correct identification. We present numerical examples of this performance figure for two sets of training images. RP DOWNIE, JD (reprint author), NASA,AMES RES CTR,DIV INFORMAT SCI,PHOTON GRP,M-S 269-3,MOFFETT FIELD,CA 94035, USA. NR 22 TC 4 Z9 4 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 MAR PY 1993 VL 32 IS 3 BP 560 EP 570 DI 10.1117/12.61203 PG 11 WC Optics SC Optics GA KQ388 UT WOS:A1993KQ38800021 ER PT J AU CARDER, KL STEWARD, RG CHEN, RF HAWES, S LEE, Z DAVIS, CO AF CARDER, KL STEWARD, RG CHEN, RF HAWES, S LEE, Z DAVIS, CO TI AVIRIS CALIBRATION AND APPLICATION IN COASTAL OCEANIC ENVIRONMENTS - TRACERS OF SOLUBLE AND PARTICULATE CONSTITUENTS OF THE TAMPA BAY COASTAL PLUME SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 1st Thematic Conf on Remote Sensing for Marine and Coastal Environments CY JUN 15-17, 1992 CL NEW ORLEANS, LA SP ENVIRONM RES INST MICHIGAN, MARINE SPILL RESPONSE CORP ID REFLECTANCE MODEL; CHLOROPHYLL-A; WATER; MATTER; COLOR; SEA AB AVIRIS is a test bed for future spacecraft sensors such as HIRIS and MODIS planned for the Earth Observing System. Model-derived absorption coefficients at 415 nm, a(415), and back-scattering coefficients at 671 nm, b(b)(671) for Tampa Bay waters were used to create images from AVIRIS data of the dissolved component of a(415) due to gelbstoff, a(g)(415), and salinity. Images of a(g)(415), salinity, and b(b)(671) were used to depict the distribution of dissolved and particulate constituents, respectively, for Tampa Bay plume during late, ebb-tidal conditions. Salinity covaried with a(g)(415), which provided a means of mapping salinity from the a(g)(415) imagery. The concentration of suspended particles, as inferred from b(b)(671), was extremely variable in the shallow regions where waves and currents interacted. Pollutants covarying with fresh water or suspended sediments can be mapped from a(g)(415) and b(b)(671) images, respectively. C1 JET PROP LAB,PASADENA,CA 91109. RP CARDER, KL (reprint author), UNIV S FLORIDA,DEPT MARINE SCI,140 7TH AVE S,ST PETERSBURG,FL 33701, USA. NR 22 TC 17 Z9 17 U1 0 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD MAR PY 1993 VL 59 IS 3 BP 339 EP 344 PG 6 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA LC775 UT WOS:A1993LC77500005 ER PT J AU TRIPATHI, RK KHAN, F AF TRIPATHI, RK KHAN, F TI PHENOMENOLOGY OF FLOW DISAPPEARANCE IN INTERMEDIATE-ENERGY HEAVY-ION COLLISIONS SO PHYSICAL REVIEW C LA English DT Note ID MOMENTUM-DEPENDENT INTERACTIONS; NUCLEUS-NUCLEUS COLLISIONS; COLLECTIVE MOTION; FRAGMENT FLOW; EQUATION; STATE; MATTER; MODELS AB The disappearance of collective flow effects in heavy ion collisions is investigated using a microscopic optical model formalism for estimating collision momentum transfers. Phenomenological expressions for the balance energy are obtained which agree very well with measurements for various experimental collision pairs and with results obtained from Boltzmann-Uehling-Uhlenbeck simulations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. OLD DOMINION UNIV,NORFOLK,VA 23529. RP TRIPATHI, RK (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 39 TC 8 Z9 8 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD MAR PY 1993 VL 47 IS 3 BP R935 EP R937 DI 10.1103/PhysRevC.47.R935 PG 3 WC Physics, Nuclear SC Physics GA KT881 UT WOS:A1993KT88100005 ER PT J AU SUTTON, JF SPANIOL, GC AF SUTTON, JF SPANIOL, GC TI A BROAD-BAND ACTIVE ANTENNA FOR ELF MAGNETIC-FIELDS SO PHYSICS ESSAYS LA English DT Article DE ANTENNA; ACTIVE ANTENNA; BROAD-BAND ANTENNA; ELF ANTENNA; MAGNETIC ANTENNA; EARTH-IONOSPHERE CAVITY; NEGATIVE IMPEDANCE; BLACK HOLE AB A unique broadband ULF-ELF magnetic antenna is described. Active circuitry is employed to introduce a negative impedance that combines with the wire resistance, the distributed winding capacitance, and the inductance of a physically small search coil to produce an antenna with a very small impedance. The result is increased search coil current and an enhanced dipole-plane wave field interaction, which greatly increases the effective area of the antenna, independent of frequency- a ''black bole'' antenna. RP SUTTON, JF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV INSTRUMENT,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU UNIV TORONTO PRESS INC PI TORONTO PA JOURNALS DIVISION, 5201 DUFFERIN ST, DOWNSVIEW, TORONTO ON M3H 5T8, CANADA SN 0836-1398 J9 PHYS ESSAYS JI Phys. Essays PD MAR PY 1993 VL 6 IS 1 BP 52 EP 59 PG 8 WC Physics, Multidisciplinary SC Physics GA LH045 UT WOS:A1993LH04500008 ER PT J AU SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW AF SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW TI MATHEMATICAL-MODELING OF THE HUMAN CARDIOVASCULAR-SYSTEM IN THE PRESENCE OF STENOSIS SO PHYSICS IN MEDICINE AND BIOLOGY LA English DT Article ID HUMAN ARTERIAL SYSTEM; FLOW CHARACTERISTICS; STEADY FLOW; BLOOD-FLOW; PULSATILE; TUBES AB This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by Stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large number of interconnected segments in the model. Values for the model parameters are based upon the published data on the physiological and rheological properties of blood. Computational results show how blood flow through various parts of the cardiovascular system is affected by stenosis in different blood vessels. No significant changes in the flow parameters of the cardiovascular system were found to occur when the reduction in the lumen diameter of the stenosed vessels was less than 65%. C1 KRUG INT,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SUD, VK (reprint author), ALL INDIA INST MED SCI,DEPT BIOPHYS,NEW DELHI 110016,INDIA. NR 18 TC 4 Z9 4 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0031-9155 J9 PHYS MED BIOL JI Phys. Med. Biol. PD MAR PY 1993 VL 38 IS 3 BP 369 EP 378 DI 10.1088/0031-9155/38/3/004 PG 10 WC Engineering, Biomedical; Radiology, Nuclear Medicine & Medical Imaging SC Engineering; Radiology, Nuclear Medicine & Medical Imaging GA KR907 UT WOS:A1993KR90700004 PM 8451280 ER PT J AU GOLDSTEIN, ME MATHEW, J AF GOLDSTEIN, ME MATHEW, J TI THE DEVELOPMENT OF A MIXING LAYER UNDER THE ACTION OF WEAK STREAMWISE VORTICES SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article AB The action of weak, streamwise vortices on a plane, incompressible, steady mixing layer is examined in the large Reynolds number limit. The outer, inviscid region is bounded by a vortex sheet to which the viscous region is confined. It is shown that the local linear analysis becomes invalid at streamwise distances O(epsilon-1), where epsilon much less than 1 is the cross-flow amplitude, and a new nonlinear analysis is constructed for this region. Numerical solutions of the nonlinear problem show that the vortex sheet undergoes an O(1) change in position and that the solution is ultimately terminated by a breakdown in the numerical procedure. The corresponding viscous layer shows downstream thickening, but appears to remain well behaved up to the terminal location. C1 NASA,LEWIS RES CTR,ICOMP,CLEVELAND,OH 44135. RP GOLDSTEIN, ME (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 7 TC 1 Z9 1 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 MAR PY 1993 VL 5 IS 3 BP 600 EP 607 DI 10.1063/1.858646 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KQ417 UT WOS:A1993KQ41700008 ER PT J AU WALEFFE, F AF WALEFFE, F TI INERTIAL TRANSFERS IN THE HELICAL DECOMPOSITION SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID ISOTROPIC TURBULENCE; 3-DIMENSIONAL INSTABILITY; ROTATION AB The directions of the triadic energy transfers assumed in a previous paper [Phys. Fluids A 4, 350 (1992)] agree with the spectral closures, in a similarity range, if the exponent of the power-law energy spectrum is less than unity. The helical interactions showing a strong local energy transfer when the triad is nonlocal, sum up to a reverse cascade unless the spectrum falls off faster than a -7/3 power of the wave number. The energy cascades from each type of helical interaction are calculated for a -5/3 inertial range using the eddy damped quasinormal Markovian (EDQNM) model. One type of interaction is responsible for 86% of the cascade. The contributions of the two classes of helical interactions to the subgrid-scale eddy viscosity are presented, together with the contributions from the forward and reverse cascading interactions. An application of the assumption on the triadic energy transfers to turbulence under rapid rotation gives a simple argument for the tendency toward nonlinear two-dimensionalization of the flow. C1 STANFORD UNIV,NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. NR 20 TC 119 Z9 119 U1 1 U2 5 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 MAR PY 1993 VL 5 IS 3 BP 677 EP 685 DI 10.1063/1.858651 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KQ417 UT WOS:A1993KQ41700014 ER PT J AU KIM, J HUSSAIN, F AF KIM, J HUSSAIN, F TI PROPAGATION VELOCITY OF PERTURBATIONS IN TURBULENT CHANNEL FLOW SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID PRESSURE-FLUCTUATIONS; COHERENT STRUCTURES; TAYLOR HYPOTHESIS; WALL TURBULENCE; BOUNDARY-LAYER; VORTICES; FIELD; BAND AB A database obtained from direct numerical simulation of a turbulent channel flow is analyzed to extract the streamwise component of the propagation velocity V of velocity, vorticity, and pressure fluctuations from their space-time correlations. A surprising result is that V is approximately the same as the local mean velocity for most of the channel, except for the near-wall region. For y+ less-than-or-equal-to 15, V is virtually constant, implying that perturbations of all flow variables propagate like waves near the wall. In this region, V is 55% of the centerline velocity U(c) for velocity and vorticity perturbations and 75% of U(c) for pressure perturbations. This is equal to U at y+ = 15 for velocity and vorticity perturbations, and equal to U at y+ = 20 for pressure perturbations, indicating that the dynamics of the near-wall turbulence is controlled by turbulence structures present near y+ congruent-to 15-20. Scale dependence of V is also examined by analyzing the bandpass-filtered flow fields. This paper contains comprehensive documentation on the propagation velocities, which should prove useful in the evaluation of Taylor's hypothesis. An attempt has been made to explain some of the data in terms of the current understanding of organized structures. C1 UNIV HOUSTON,HOUSTON,TX 77204. RP KIM, J (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 46 TC 118 Z9 121 U1 0 U2 5 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 MAR PY 1993 VL 5 IS 3 BP 695 EP 706 DI 10.1063/1.858653 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KQ417 UT WOS:A1993KQ41700016 ER PT J AU JACKSON, TL HUSSAINI, MY RIBNER, HS AF JACKSON, TL HUSSAINI, MY RIBNER, HS TI INTERACTION OF TURBULENCE WITH A DETONATION-WAVE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID SHOCK-WAVE; AMPLIFICATION; VORTICITY; FLOW AB This paper addresses a specific reactive-flow configuration, namely, the interaction of a detonation wave with convected homogeneous isotropic weak turbulence (which can be constructed by a Fourier synthesis of small-amplitude vorticity waves). The effect of chemical heat release on the rms fluctuations downstream of the detonation is presented as a function of Mach number. In addition, for the particular case of the von Karman spectrum, the one-dimensional power spectra of these flow quantities are given. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. UNIV TORONTO,INST AEROSP STUDIES,TORONTO M3H 5T6,ONTARIO,CANADA. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP JACKSON, TL (reprint author), OLD DOMINION UNIV,DEPT MATH & STAT,NORFOLK,VA 23529, USA. NR 30 TC 9 Z9 9 U1 0 U2 1 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 MAR PY 1993 VL 5 IS 3 BP 745 EP 749 DI 10.1063/1.858657 PG 5 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA KQ417 UT WOS:A1993KQ41700020 ER PT J AU DAWSON, JM DECYK, V SYDORA, R LIEWER, P AF DAWSON, JM DECYK, V SYDORA, R LIEWER, P TI HIGH-PERFORMANCE COMPUTING AND PLASMA PHYSICS SO PHYSICS TODAY LA English DT Article ID PARTICLE SIMULATION; TRANSPORT; INSTABILITY; TOKAMAK; WAVES C1 CALTECH,JET PROPULSION LAB,SPACE & ASTROPHYS SECT,PASADENA,CA 91125. CALTECH,NSF,CTR RES PARALLEL COMPUTAT,PASADENA,CA 91125. RP DAWSON, JM (reprint author), UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024, USA. NR 24 TC 16 Z9 16 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD MAR PY 1993 VL 46 IS 3 BP 64 EP 70 DI 10.1063/1.881386 PG 7 WC Physics, Multidisciplinary SC Physics GA KT929 UT WOS:A1993KT92900018 ER PT J AU SCHAEFER, BE AHMAD, IA DOGGETT, L AF SCHAEFER, BE AHMAD, IA DOGGETT, L TI RECORDS FOR YOUNG MOON SIGHTINGS SO QUARTERLY JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID VISIBILITY AB We examine various claims of record and near record young moon sightings. We find that the claims for 1916 May 2, 1895 July 22, and 1910 February 10 were made under cloudy skies, hence the reports are likely to have an error in the date of observation. Similar problems with the reported date have occurred for the claimed sightings on 1885 December II, 1989 May 5, and 1991 September 7. Other reports from 1989 May 5 are shown to have reported incorrectly the moon's position and orientation, and so the observed source was not the moon. Of the reliable reports, the record for sightings with the unaided eye is 15.4 h by Julius Schmidt, while the record for sightings with optical aid is 13 h 28 min by Robert C. Victor. We find that the reliable reports can be sharply distinguished from the dubious reports based on such factors as observer experience, promptness of report, and observer preparation. C1 USN OBSERV,OFF NAVT ALMANAC,WASHINGTON,DC 20390. IMAD AD DEAN INC,BETHESDA,MD 20814. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 21 TC 3 Z9 3 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8738 J9 Q J ROY ASTRON SOC JI Q. J. R. Astron. Soc. PD MAR PY 1993 VL 34 IS 1 BP 53 EP 56 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KQ768 UT WOS:A1993KQ76800004 ER PT J AU BREWER, DW BURNS, JA CLIFF, EM AF BREWER, DW BURNS, JA CLIFF, EM TI PARAMETER-IDENTIFICATION FOR AN ABSTRACT CAUCHY-PROBLEM BY QUASI-LINEARIZATION SO QUARTERLY OF APPLIED MATHEMATICS LA English DT Article ID FUNCTIONAL-DIFFERENTIAL EQUATIONS; APPROXIMATIONS AB A parameter identification problem is considered in the context of a linear abstract Cauchy problem with a parameter-dependent evolution operator. Conditions are investigated under which the gradient of the state with respect to a parameter possesses smoothness properties which lead to local convergence of an estimation algorithm based on quasilinearization. Numerical results are presented concerning estimation of unknown parameters in delay-differential equations. C1 VIRGINIA POLYTECH INST & STATE UNIV,BLACKSBURG,VA 24061. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. INTERDISCIPLINARY CTR APPL MATH,BLACKSBURG,VA 24061. RP BREWER, DW (reprint author), UNIV ARKANSAS,FAYETTEVILLE,AR 72701, USA. NR 19 TC 15 Z9 15 U1 0 U2 0 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0033-569X J9 Q APPL MATH JI Q. Appl. Math. PD MAR PY 1993 VL 51 IS 1 BP 1 EP 22 PG 22 WC Mathematics, Applied SC Mathematics GA KR249 UT WOS:A1993KR24900001 ER PT J AU HANSEN, J LACIS, A RUEDY, R SATO, M WILSON, H AF HANSEN, J LACIS, A RUEDY, R SATO, M WILSON, H TI HOW SENSITIVE IS THE WORLDS CLIMATE SO RESEARCH & EXPLORATION LA English DT Article ID CLOUD ALBEDO; SOLAR-CYCLE; TEMPERATURE; AEROSOLS; SULFUR; TRENDS AB We estimate climate sensitivity from observed climate change on time scales ranging from the 100 000-year periods of major ice ages to brief periods of cooling after major volcanic eruptions. The real-world data indicate that climate is very sensitive, equivalent to a warming of 3 +/- 1-degrees-C for doubled atmospheric CO2. Observed global warming of approximately 0.5-degrees-C in the past 140 years is consistent with anthropogenic greenhouse gases being the dominant climate-forcing in that period. But interpretation of current climate change is extraordinarily complex, because of lack of observations of several climate forcings as well as an unpredictable chaotic aspect of climate change. Climate change during the next decade may help confirm knowledge of climate sensitivity, if global climate forcings are accurately observed. C1 HUGHES STX CORP,NEW YORK,NY 10025. COLUMBIA UNIV,NEW YORK,NY 10025. RP HANSEN, J (reprint author), NASA,GODDARD INST SPACE SCI,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Lacis, Andrew/D-4658-2012 NR 42 TC 98 Z9 99 U1 0 U2 5 PU NATL GEOGRAPHIC SOC PI WASHINGTON PA 17TH AND M STS NW, WASHINGTON, DC 20036 SN 8755-724X J9 RES EXPLOR JI Res. Explor. PD SPR PY 1993 VL 9 IS 2 BP 142 EP 158 PG 17 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LG925 UT WOS:A1993LG92500001 ER PT J AU ROSENZWEIG, C HILLEL, D AF ROSENZWEIG, C HILLEL, D TI AGRICULTURE IN A GREENHOUSE WORLD SO RESEARCH & EXPLORATION LA English DT Article ID CLIMATE CHANGE AB While agriculture in some temperate regions may benefit from global climate change, tropical and subtropical regions may suffer. Even where potential production will improve, the required adjustments may disrupt ecosystems and land-use patterns. Agricultural zones will shift toward high latitudes, while heat stress and increased droughts will reduce productivity in lower latitudes. On the positive side, higher CO2 may enhance photosynthesis and water-use efficiency. Future hazards include sea-level rise, insect infestation, and greater evaporation losses. Some agricultural activities augment the greenhouse effect by releasing CO2, CH4, and N2O. Understanding the potential impacts of climate change is a prerequisite to developing societal responses. C1 GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV MASSACHUSETTS,DEPT PLANT SOIL & ENVIRONM,AMHERST,MA 01003. RP ROSENZWEIG, C (reprint author), COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10025, USA. NR 27 TC 9 Z9 9 U1 1 U2 7 PU NATL GEOGRAPHIC SOC PI WASHINGTON PA 17TH AND M STS NW, WASHINGTON, DC 20036 SN 8755-724X J9 RES EXPLOR JI Res. Explor. PD SPR PY 1993 VL 9 IS 2 BP 208 EP 221 PG 14 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA LG925 UT WOS:A1993LG92500006 ER PT J AU ELDRIDGE, J AF ELDRIDGE, J TI A LOW-COST DESK-TOP EVALUATION TEST FOR COMPOSITE-MATERIALS SO SAMPE JOURNAL LA English DT Note RP ELDRIDGE, J (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0091-1062 J9 SAMPE J JI Sampe J. PD MAR-APR PY 1993 VL 29 IS 2 BP 41 EP 41 PG 1 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA MV546 UT WOS:A1993MV54600008 ER PT J AU CARTER, RG AF CARTER, RG TI NUMERICAL EXPERIENCE WITH A CLASS OF ALGORITHMS FOR NONLINEAR OPTIMIZATION USING INEXACT FUNCTION AND GRADIENT INFORMATION SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE UNCONSTRAINED OPTIMIZATION; TRUST REGION METHODS; INEXACT FUNCTION EVALUATION; INEXACT GRADIENTS; VARIABLE-ACCURACY SIMULATIONS ID GLOBAL CONVERGENCE; SOFTWARE AB For optimization problems associated with engineering design, parameter estimation, image reconstruction, and other optimization/simulation applications, low accuracy function and gradient values are frequently much less expensive to obtain than high accuracy values. The computational performance of trust region methods for nonlinear optimization is investigated for cases when high accuracy evaluations are unavailable or prohibitively expensive, and earlier theoretical predictions that such methods are convergent even with relative gradient errors of 0.5 or more is confirmed. The proper choice of the amount of accuracy to use in function and gradient evaluations can result in orders-of-magnitude savings in computational cost. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP CARTER, RG (reprint author), STONER ASSOCIATES INC,5177 RICHMOND AVE,SUITE 1075,HOUSTON,TX 77056, USA. NR 19 TC 18 Z9 18 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD MAR PY 1993 VL 14 IS 2 BP 368 EP 388 DI 10.1137/0914023 PG 21 WC Mathematics, Applied SC Mathematics GA KP467 UT WOS:A1993KP46700007 ER PT J AU FREUND, RW AF FREUND, RW TI A TRANSPOSE-FREE QUASI-MINIMAL RESIDUAL ALGORITHM FOR NON-HERMITIAN LINEAR-SYSTEMS SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE NON-HERMITIAN LINEAR SYSTEMS; BICONJUGATE GRADIENTS; TRANSPOSE-FREE; CONJUGATE GRADIENTS SQUARED; QUASI-MINIMAL RESIDUAL PROPERTY AB The biconjugate gradient method (BCG) for solving general non-Hermitian linear systems Ax = b and its transpose-free variant, the conjugate gradients squared algorithm (CGS), both typically exhibit a rather irregular convergence behavior with wild oscillations in the residual norm. Recently, Freund and Nachtigal proposed a BCG-like approach, the quasi-minimal residual method (QMR), that remedies this problem for BCG and produces smooth convergence curves. However, like BCG, QMR requires matrix-vector multiplications with both the coefficient matrix A and its transpose A(T). In this note, it is demonstrated that the quasi-minimal residual approach can also be used to obtain a smoothly convergent CGS-like algorithm that does not involve matrix-vector multiplications with A(T). It is shown that the resulting transpose-free QMR method (TFQMR) can be implemented very easily by changing only a few lines in the standard CGS algorithm. Finally, numerical experiments are reported. C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. NR 16 TC 349 Z9 358 U1 3 U2 11 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD MAR PY 1993 VL 14 IS 2 BP 470 EP 482 DI 10.1137/0914029 PG 13 WC Mathematics, Applied SC Mathematics GA KP467 UT WOS:A1993KP46700013 ER PT J AU KEENAN, FP THOMAS, RJ NEUPERT, WM CONLON, ES BURKE, VM AF KEENAN, FP THOMAS, RJ NEUPERT, WM CONLON, ES BURKE, VM TI A COMPARISON OF THEORETICAL-C IV EMISSION-LINE STRENGTHS WITH ACTIVE REGION OBSERVATIONS OBTAINED WITH THE SOLAR EUV ROCKET TELESCOPE AND SPECTROGRAPH (SERTS) SO SOLAR PHYSICS LA English DT Article ID SPECTRA; PLASMAS AB Theoretical line ratios involving 2s 2S - 3p 2P, 2p 2P - 3S 2S , and 2p 2S - 3d 2D transitions in CIV between 312 and 420 angstrom are presented. A comparison of these with solar active region observational data obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS) reveals good agreement between theory and experiment, with discrepancies that average only 22%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on board Skylab. The potential usefulness of the CIV line ratios as electron temperature diagnostics for the solar transition region is briefly discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. QUEENS UNIV BELFAST,DEPT APPL MATH & THEORET PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. RP KEENAN, FP (reprint author), QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NR 15 TC 10 Z9 10 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 1993 VL 144 IS 1 BP 69 EP 74 DI 10.1007/BF00667983 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP563 UT WOS:A1993KP56300006 ER PT J AU POLETTO, G GARY, GA MACHADO, ME AF POLETTO, G GARY, GA MACHADO, ME TI INTERACTIVE FLARE SITES WITHIN AN ACTIVE REGION COMPLEX SO SOLAR PHYSICS LA English DT Article ID RAY-IMAGING SPECTROMETER; MAGNETIC-FIELDS; ELECTRIC CURRENTS; CURRENT SHEETS; SOLAR-FLARES; RELEASE; HXIS AB The problem of physical relationships between different active regions has been dealt with only rarely and mainly in connection with flares. How sympathetic activity can be triggered between distant regions is therefore, so far, largely unknown. Soft X-ray images of large-scale coronal structures connecting different active regions were obtained by Skylab nearly 20 years ago, while SMM, more recently, did not provide any clear evidence for this kind of loop. As a consequence, we do not know how common these features are nor how they form nor whether they represent the only means by which distant active regions may be linked. In the latter case, however, interconnecting loops should be detected by analyzing the interaction between different active regions. We examine here a set of images of an active region complex, acquired on June 24-25, 1980, by the Hard X-rav Imaging Spectrometer on SMM, with the purpose of establishing whether there was any interplay between the frequent activity observed at different sites in the activity center and, in such a case, how the interaction was established. By analyzing both quiet and active orbits we show that, as a rule, activity originating in one region triggers the other region's activity. However, we find little unambiguous evidence for the presence of large-scale interconnecting loops. A comparison of X-ray images with magnetic field observations suggested that we interpret the active region behavior in terms of the interaction between different loop systems, in a scenario quite analogous to the interacting bipole representation of individual flares. We conclude that active region interplay provides an easily observable case to study the time-dependent topology and the mechanisms for the spreading of activity in transient events over all energy scales. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP POLETTO, G (reprint author), OSSERV ASTROFIS ARCETRI,LARGO ENRICO FERMI 5,I-50125 FLORENCE,ITALY. NR 39 TC 15 Z9 15 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 1993 VL 144 IS 1 BP 113 EP 140 DI 10.1007/BF00667987 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP563 UT WOS:A1993KP56300010 ER PT J AU HAGYARD, MJ WEST, EA SMITH, JE AF HAGYARD, MJ WEST, EA SMITH, JE TI MAGNETIC-FIELD CHANGES ASSOCIATED WITH A SUB-FLARE AND SURGE SO SOLAR PHYSICS LA English DT Article ID VECTOR MAGNETOGRAPH AB A sub-flare and surge were observed on June 13, 1990, with the Marshall Space Flight Center vector magnetograph and coaligned Halpha telescope. This activity occurred at the site of a parasitic polarity near a large, mature sunspot. Analysis of the vector magnetic field showed that while flux emergence and other field changes occurred sporadically throughout a period of 4 days, the sub-flare and surge only took place after an increase in magnetic shear in the field of the parasitic polarity. This event also provided an example of relaxation of magnetic shear following the flare and surging. RP HAGYARD, MJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 16 TC 9 Z9 9 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 1993 VL 144 IS 1 BP 141 EP 153 DI 10.1007/BF00667988 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KP563 UT WOS:A1993KP56300011 ER PT J AU RIND, D LACIS, A AF RIND, D LACIS, A TI THE ROLE OF THE STRATOSPHERE IN CLIMATE CHANGE SO SURVEYS IN GEOPHYSICS LA English DT Review ID 11-YEAR SOLAR-CYCLE; LATITUDE LOWER STRATOSPHERE; GENERAL-CIRCULATION MODEL; ANTARCTIC OZONE HOLE; NORTHERN-HEMISPHERE; MIDDLE ATMOSPHERE; ULTRAVIOLET VARIATIONS; SOUTHERN OSCILLATION; 2-DIMENSIONAL MODEL; TEMPERATURE TRENDS AB A variety of climate perturbations have the potential to alter the thermodynamic and dynamical characteristics of the middle atmosphere, which may then affect tropospheric climate. Increased thermal emission from rising stratospheric CO2 levels and scattering of solar radiation from stratospheric volcanic aerosols have a direct impact on surface temperatures, while variations in stratospheric water vapor and ozone can affect tropospheric temperatures. Observations and modeling experiments suggest that these perturbations. as well as solar irradiance variations operating through the stratosphere, may affect tropospheric dynamics, such as planetary wave amplitudes and Hadley cell intensity. In addition, climate changes will probably alter tropospheric/stratospheric exchange. with the potential for modifying trace gas distributions and climate forcing. These issues are reviewed in the light of the incorporation of middle atmosphere studies into IGBP. RP RIND, D (reprint author), INST SPACE STUDIES,GODDARD SPACE FLIGHT CTR,NEW YORK,NY 10025, USA. RI Lacis, Andrew/D-4658-2012 NR 69 TC 22 Z9 22 U1 0 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0169-3298 J9 SURV GEOPHYS JI Surv. Geophys. PD MAR PY 1993 VL 14 IS 2 BP 133 EP 165 DI 10.1007/BF02179221 PG 33 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KV135 UT WOS:A1993KV13500002 ER PT J AU FIORINO, M GOERSS, JS JENSEN, JJ HARRISON, EJ AF FIORINO, M GOERSS, JS JENSEN, JJ HARRISON, EJ TI AN EVALUATION OF THE REAL-TIME TROPICAL CYCLONE FORECAST SKILL OF THE NAVY OPERATIONAL GLOBAL ATMOSPHERIC PREDICTION SYSTEM IN THE WESTERN NORTH PACIFIC SO WEATHER AND FORECASTING LA English DT Article AB The meteorological quality and operational utility of the Navy Operational Global Atmospheric Prediction System (NOGAPS) in forecasting tropical cyclones is evaluated and it is shown that the model can provide useful predictions of motion and formation on a real-time basis in the western North Pacific. The evaluation was conducted during the 1990 operational testing of a procedure to improve the initial analysis or specification of tropical cyclones (TCs) in NOGAPS by the U.S. Navy Fleet Numerical Oceanography Center (FNOC). The NOGAPS TC analysis procedure generates synthetic TC observations based on operational vortex data (e.g., location and maximum surface wind speed) and then adds the observations to the observational data base with flags to force their assimilation. Results from the first Year of testing were favorable, despite intermittent application of the procedure. The meteorological characteristics of the NOGAPS tropical cyclone predictions were evaluated by examining the formation of tow-level cyclone circulation systems in the tropics and vortex structure in the NOGAPS analysis and verifying 72-h forecasts. Analyzed circulations were found in the vicinity of developing TCs for nearly all cyclones during the operational test period. This finding implies that the model is ''primed'' for assimilating the synthetic observations and may be accurately simulating the large-scale environments favorable to TC formation. The analyzed TC circulations had greater than observed horizontal extent due to coarse grid spacing (DELTAx approximately 160 km) in the global model; however, the vortices, in general, were vertically stacked and maintained during the forecast by realistic amounts of thermodynamic forcing from the cumulus parameterization. Despite the large size of the NOGAPS TC vortices, the track forecasts were not overly biased with regard to track or speed. The operational utility of the NOGAPS track forecasts was analyzed through a comparison with the real-time runs of a baseline climatology persistence aid and with the best dynamical model used by the Joint Typhoon Warning Center, Guam. To ensure a realistic comparison of the forecasts and to improve the appearance of the global model tracks, a postprocessing adjustment procedure was employed that accounts for the observed initial motion and position. The adjusted NOGAPS track forecasts showed equitable skill to the baseline aid and the dynamical model. In fact, NOGAPS successfully predicted unusual equatorward turns for several straight-running cyclones. Overall, the adjusted NOGAPS track forecasts were judged to be competitive with other aids used by the operational forecasters at JTWC and it is suggested that global models may make important contributions to improving TC forecasting in the future. RP FIORINO, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Fiorino, Michael/N-4150-2014 OI Fiorino, Michael/0000-0002-2819-8157 NR 0 TC 19 Z9 20 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0882-8156 J9 WEATHER FORECAST JI Weather Forecast. PD MAR PY 1993 VL 8 IS 1 BP 3 EP 24 DI 10.1175/1520-0434(1993)008<0003:AEOTRT>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA LL626 UT WOS:A1993LL62600001 ER PT J AU CSANAK, G CARTWRIGHT, DC TRAJMAR, S AF CSANAK, G CARTWRIGHT, DC TRAJMAR, S TI MAGNETIC-SUBLEVEL DIFFERENTIAL CROSS-SECTIONS FOR ELECTRON-IMPACT EXCITATION OF HE NP-1 LEVELS - THEORY AND EXPERIMENT IN NATURAL AND ATOMIC COORDINATE FRAMES SO ZEITSCHRIFT FUR PHYSIK D-ATOMS MOLECULES AND CLUSTERS LA English DT Article ID PHOTON ANGULAR-CORRELATIONS; EXPERIMENTAL-THEORETICAL COMPARISONS; HELIUM COLLISIONS; 21P STATE; ORIENTATION; ALIGNMENT; AMPLITUDES; SCATTERING; POLARIZATION; PARAMETERS AB Experimental data for the average transferred angular momentum, [L(perpendicular-to)], have been combined with experimental differential cross section [DCS] data for electron impact excitation of the 2(1)P and 3(1)P levels of helium to obtain the individual magnetic-sublevel differential cross-sections, [DCS(M)n], in the natural (and atomic) coordinate system. First-order many-body theory (FOMBT) has been used to obtain corresponding theoretical predictions for DCS(M)n which are compared to these results. This comparison shows that FOMBT generally predicts M = +1 sublevel excitation DCS better than that for M = -1. C1 JET PROP LAB,PASADENA,CA 91109. RP CSANAK, G (reprint author), LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545, USA. NR 40 TC 1 Z9 1 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0178-7683 J9 Z PHYS D ATOM MOL CL JI Z. Phys. D-Atoms Mol. Clusters PD MAR PY 1993 VL 25 IS 4 BP 327 EP 336 PG 10 WC Physics, Atomic, Molecular & Chemical SC Physics GA KT550 UT WOS:A1993KT55000009 ER PT J AU BOWMAN, KJ JENNY, J KIM, S NOEBE, RD AF BOWMAN, KJ JENNY, J KIM, S NOEBE, RD TI TEXTURE IN HOT-WORKED B2-STRUCTURE ALUMINIDES SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article AB Three B2 structure aluminide sheet materials produced by hot-rolling of alloys from compacted powders were evaluated for crystallographic texture. Two essentially binary NiAl alloys showed strong {111} components in the plane of the sheet. A NiFeAl alloy had dramatically different texture which consisted of a strong {112} component in the plane of the sheet. In addition to microstructures, measured pole figures and the orientation distribution function are reported and compared with textures produced in similar materials via extrusion. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOWMAN, KJ (reprint author), PURDUE UNIV,SCH MAT ENGN,W LAFAYETTE,IN 47907, USA. NR 6 TC 12 Z9 12 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 FEB 28 PY 1993 VL 160 IS 2 BP 201 EP 208 DI 10.1016/0921-5093(93)90448-N PG 8 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA KR303 UT WOS:A1993KR30300005 ER PT J AU MCFADDEN, LA COCHRAN, AL BARKER, ES CRUIKSHANK, DP HARTMANN, WK AF MCFADDEN, LA COCHRAN, AL BARKER, ES CRUIKSHANK, DP HARTMANN, WK TI THE ENIGMATIC OBJECT-2201 OLJATO - IS IT AN ASTEROID OR AN EVOLVED COMET SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID NEAR-EARTH ASTEROIDS; ARAKI-ALCOCK 1983D; RADAR OBSERVATIONS; APOLLO; PHOTOMETRY; NUCLEUS; STREAMS AB The study of the near-Earth object 2201 Oljato has resulted in many surprises in the decade in which it has been examined. Its orbital properties have been associated with meteor showers, and its modeled orbital evolution is chaotic, a property which might indicate a history related to comets. Telescopic observations of its visible and near-infrared spectral reflectance, broad-band visible and near-infrared photometry, infrared radiometric measurements, and radar echoes are reponed here from two apparitions, 1979 and 1983. A look at all available observational data shows that this asteroid has a high radiometric albedo, a property not associated with comet nuclei. In certain wavelength regimes it is classified as an S-type asteroid, in others, an E-type, but its overall spectral reflectance is not typical of either taxonomic type, and neither type is thought of as cometlike. Unexpectedly high ultraviolet reflectance at the 1979 apparition was suggested to be the result of residual outgassing as in a comet. The UV photometric data are modeled as fluorescent emission from neutral species found in comets. The resulting calculations indicate a plausible value for OH and CN emission at 0.3085 and 0.38 mum relative to the observed range of active comets. Observations to monitor photometric variations and to search for gaseous activity using observational techniques designed specifically for this purpose were planned and executed in October 1992 to verify or refute the interpretations presented here. C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV TEXAS,MCDONALD OBSERV,FT DAVIS,TX 79734. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. PLANETARY SCI INST,TUCSON,AZ 85704. RI McFadden, Lucy-Ann/I-4902-2013 OI McFadden, Lucy-Ann/0000-0002-0537-9975 NR 57 TC 27 Z9 27 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 FEB 25 PY 1993 VL 98 IS E2 BP 3031 EP 3041 DI 10.1029/92JE01895 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700001 ER PT J AU HUBA, JD GREBOWSKY, JM AF HUBA, JD GREBOWSKY, JM TI SMALL-SCALE DENSITY IRREGULARITIES IN THE NIGHTSIDE VENUS IONOSPHERE - COMPARISON OF THEORY AND OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HYBRID-DRIFT INSTABILITY; PLASMA; ORBITER; SIGNALS AB The lower-hybrid-drift instability has been proposed as a mechanism to generate small-scale density and 100 Hz electric field fluctuations in the nightside Venus ionosphere [Huba, 1992]. The primary purpose of this paper is to compare this theory with observations of density irregularities. Marginal stability boundaries (gamma = 0) for the lower-hybrid-drift instability and the occurrence of small-scale density fluctuations are presented as a function of magnetic field B and density n. For density gradient scale lengths in the range 2 - 10 km, 80 - 85% of the density fluctuations lie in the unstable B/n parameter regime (gamma > 0). A secondary purpose of the paper is to present stability boundaries for the onset of instability at a wavelength for which the Pioneer Venus Orbiter (PVO) could measure a Doppler-shifted frequency of 100 Hz. The conditions on B and n for instability in this situation are more stringent than those for marginal stability, especially at low densities (n less-than-or-equal-to 5 x 10(3) cm-3). In general, the instability is most likely to be generated in regions of low beta: high magnetic field strength and low density, as found in ionospheric holes or troughs. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP HUBA, JD (reprint author), USN,RES LAB,DIV PLASMA PHYS,SPACE PLASMA BRANCH,CODE 6780,WASHINGTON,DC 20375, USA. RI Grebowsky, Joseph/I-7185-2013 NR 35 TC 6 Z9 6 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 FEB 25 PY 1993 VL 98 IS E2 BP 3079 EP 3086 DI 10.1029/92JE02841 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700005 ER PT J AU HABERLE, RM AF HABERLE, RM TI INTRODUCTION TO THE MSATT SPECIAL SECTION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material RP HABERLE, RM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 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 FEB 25 PY 1993 VL 98 IS E2 BP 3091 EP 3091 DI 10.1029/93JE00187 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700008 ER PT J AU HABERLE, RM POLLACK, JB BARNES, JR ZUREK, RW LEOVY, CB MURPHY, JR LEE, H SCHAEFFER, J AF HABERLE, RM POLLACK, JB BARNES, JR ZUREK, RW LEOVY, CB MURPHY, JR LEE, H SCHAEFFER, J TI MARS ATMOSPHERIC DYNAMICS AS SIMULATED BY THE NASA AMES GENERAL-CIRCULATION MODEL .1. THE ZONAL-MEAN CIRCULATION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID GREAT DUST STORMS; MARTIAN ATMOSPHERE; SURFACE; TEMPERATURES; CLOUDS AB This is the first in a series of papers that will discuss Mars atmospheric dynamics as simulated by the NASA Ames General Circulation Model (GCM). This paper describes the GCM's zonal-mean circulation and how it responds to seasonal variations and dust loading. The results are compared to Mariner 9 and Viking observations, and the processes responsible for maintaining the simulated circulation are discussed. At the solstices the zonal-mean circulation consists of a single cross-equatorial Hadley circulation between 30-degrees-S and 30-degrees-N. For relatively modest dust loadings (tau=0.3), the associated peak mass flux is 100 x 10(8) kg s-1 at northern winter solstice and 55 x 10(8) kg s-1 at southern winter solstice. At both seasons, westerlies dominate the winter hemisphere, and easterlies dominate the summer hemisphere. Maximum zonal winds occur near the model top (approximately 47 km) and are about the same at both seasons: 120 m s-1 in the winter hemisphere and 60 m s-1 in the summer hemisphere. Mean surface westerlies of 10(-20) m s-I are predicted at the middle and high latitudes of the winter hemisphere, as well as in the summer hemisphere near the rising branch of the Hadley circulation. The latter has the structure of a ''jet'' and is particularly strong (>20 m s-1) at northern winter solstice. With increasing amounts of dust (up to tau=5), the zonal mean circulation at northern winter solstice intensifies and gives no indication of a negative feedback. Dust can easily double the mass flux of the Hadley circulation. In the solstice simulations, the mean meridional circulation is the main dynamical contributor to the heat and momentum balance; the eddies play a relatively minor role. There is no evidence in these simulations for a polar warming. At the equinoxes the zonal mean circulation is more Earth-like and consists of two roughly symmetric Hadley cells with westerly winds in the mid-latitudes of each hemisphere and easterlies in the tropics. The simulated zonal winds are about half as strong as they are at solstice. However, the strength of the mean meridional circulation is much less than at solstice and averages between 5 and 10 x 10(8) kg s-1. At these seasons, the eddies and mean circulation make comparable, but opposing, contributions to the heat and momentum balances. C1 OREGON STATE UNIV,DEPT ATMOSPHER SCI,CORVALLIS,OR 97331. JET PROP LAB,PASADENA,CA 91109. UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. STERLING SOFTWARE INC,PALO ALTO,CA. RP HABERLE, RM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 54 TC 232 Z9 232 U1 3 U2 24 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 FEB 25 PY 1993 VL 98 IS E2 BP 3093 EP 3123 DI 10.1029/92JE02946 PG 31 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700009 ER PT J AU BARNES, JR POLLACK, JB HABERLE, RM LEOVY, CB ZUREK, RW LEE, H SCHAEFFER, J AF BARNES, JR POLLACK, JB HABERLE, RM LEOVY, CB ZUREK, RW LEE, H SCHAEFFER, J TI MARS ATMOSPHERIC DYNAMICS AS SIMULATED BY THE NASA AMES GENERAL-CIRCULATION MODEL .2. TRANSIENT BAROCLINIC EDDIES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID MARTIAN ATMOSPHERE; DUST STORMS; WAVE; INSTABILITY; TROPOSPHERE AB A large set of experiments performed with the NASA Ames Mars general circulation model (GCM) have been analyzed to determine the properties, structure, and dynamics of the simulated transient baroclinic eddies. The Mars GCM simulations span a wide range of seasonal dates and dust loadings and include a number of special sensitivity experiments (e.g., with flat topography). There is strong transient baroclinic eddy activity in the extratropics of the northern hemisphere during the northern autumn, winter, and spring seasons. The eddy activity remains strong for very large dust loadings, though it shifts northward. The eastward propagating eddies are characterized by zonal wavenumbers of 1-4 and periods of approximately 2-10 days. In several simulations, the eddy variance is dominated by a single zonal wavenumber and a narrow range of periods. The longer (wavenumbers 1 and 2) transient eddies have a very deep vertical structure, exhibiting a maximum kinetic energy density at the model top (approximately 45-50 km) in many of the simulations. In a simulation for early northern spring the eddies are quite shallow however. The transient eddies generate the bulk of their energy baroclinically via large meridional and vertical heat fluxes, at both lower and upper levels. This is despite the fact that their vertical structure is typically close to equivalent barotropic above the lowest 10 km. The eddies also appear to generate a substantial amount of energy barotropically, via large meridional momentum fluxes at both lower and upper levels. In the tropics and northern subtropics at upper levels(approximately 25-50 km) there are strong transient eddy motions with structures resembling those characterisitic of inertially unstable modes. This eddy activity appears to be a response to the forcing of a region of marginal inertial stability by the extratropical transient baroclinic eddies, as the wavenumbers and periods are the same as those in the extratropics. A major surprise is the presence of very weak transient eddy activity in a number of the southern winter simulations. It appears that this is partly a consequence of the stabilizing effects of the zonally symmetric topography in the GCM, but it also must be associated with certain aspects of the zonal-mean circulation in southern winter. This is indicated by the presence of relatively large amplitude eddies in simulations for early southern autumn and spring and in a southern winter solstice simulation incorporating a different topography (derived from the Mars Digital Terrain Model). This topography differs from that used in most of the GCM simulations in not being characterized by steep symmetric slopes (which are stabilizing to baroclinic instability) in southern high latitudes. It is hypothesized that the very large extent of the southern seasonal polar cap and high elevations in the south both might contribute to weakening the transient eddy activity. Large zonally symmetric topography in the northern hemisphere of the Mars GCM also appears to have a strong impact on the transient eddies, acting to increase the dominant zonal wavenumbers and phase speeds. The properties of the GCM baroclinic eddies in the northern extratropics are compared in detail with analogous properties inferred from Viking Lander meteorology observations. The GCM eddies are found to be very similar to those observed in most respects. A notable exception is that the eddy amplitudes in the highly dusty GCM simulations are much larger than those observed by Viking during the 1977 winter solstice dust storm. This is almost certainly at least partly due to the relatively small latitudinal expansion of the Hadley circulation in the highly dusty GCM experiments. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. JET PROP LAB,PASADENA,CA 91109. STERLING SOFTWARE INC,PALO ALTO,CA. RP BARNES, JR (reprint author), OREGON STATE UNIV,STAND AGR HALL 326,CORVALLIS,OR 97331, USA. NR 35 TC 89 Z9 89 U1 1 U2 5 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 FEB 25 PY 1993 VL 98 IS E2 BP 3125 EP 3148 DI 10.1029/92JE02935 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700010 ER PT J AU POLLACK, JB HABERLE, RM MURPHY, JR SCHAEFFER, J LEE, H AF POLLACK, JB HABERLE, RM MURPHY, JR SCHAEFFER, J LEE, H TI SIMULATIONS OF THE GENERAL-CIRCULATION OF THE MARTIAN ATMOSPHERE .2. SEASONAL PRESSURE VARIATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID SOUTH POLAR-CAP; GLOBAL DUST STORMS; SUMMER TEMPERATURES; MARS; VIKING; CO2; BALANCE; MODEL AB We have simulated the CO2 seasonal cycle of the Martian atmosphere and surface with a hybrid energy balance model that incorporates dynamical and radiation information from a large number of general circulation model (GCM) runs. This information includes heating due to atmospheric heat advection, the seasonally varying ratio of the surface pressure at the two Viking landing sites to the globally averaged pressure (r(k)), the rate of CO2 condensation in the atmosphere, and solar heating of the atmosphere and surface. The GCM runs collectively covered a full set of seasonal dates and a large range of dust optical depths. We have compared the predictions of the energy balance model with the seasonal pressure variations measured at the two Viking landing (VL) sites and the springtime retreat of the seasonal polar cap boundaries. Numerical experiments with the energy balance model indicate that the following quantities have a strong influence on the VL seasonal pressures: albedo A(is) of the seasonal CO2 ice deposits, emissivity e(is) of this deposit, atmospheric heat advection, and the pressure ratio r(k). This last factor does not enter into the seasonal CO2 condensation/sublimation cycle in a significant way. The numerical experiments also indicate that the following factors have only a minor effect on the VL pressures: (1) the net radiative effects (solar plus thermal) of atmospheric dust at the latitudes of the polar caps, and (2) the subsurface heat conduction. The significant influence of the pressure ratio r(k) on the VL, seasonal pressures is due to large seasonal variations in the global distribution of surface pressure. At low and mid-latitudes, these ''weather'' variations are engendered by seasonal changes in the Hadley circulation and by seasonal changes in the atmospheric scale height close to the surface. Comparison of the VL1 and VL2 pressures with one another provide direct evidence for the presence of such a ''weather component'' in the measured pressures. The differential weather component (VL2-VL1) derived from the data is reproduced approximately by the energy balance model. We find that the seasonal weather variations account for about 20% and 30% of the seasonal pressure variations measured at VL1 and VL2, respectively, that dynamical and scale height variations make comparable contributions to the weather component during years without global dust storms, and that the dynamical contribution is the larger one during years with global dust storms. Interannual variations in the weather component, rather than variations in CO2 condensation rates, are the dominant sources of the observed interannual variations of pressure during the season of global dust storms. Optimum fits to the Viking pressure measurements and the data on the polar cap boundaries are achieved with values of about 0.45 and 0.75 for A(is) and e(is), respectively. The former value is consistent with available photometric determinations of the albedo of the seasonal caps, while the latter value, especially in light of infrared thermal mapper brightness temperatures at high latitudes, may reflect, in part, the influence of the polar hood on the radiation balance of the winter polar regions. C1 STERLING SOFTWARE INC,PALO ALTO,CA. RP POLLACK, JB (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 34 TC 51 Z9 51 U1 2 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 FEB 25 PY 1993 VL 98 IS E2 BP 3149 EP 3181 DI 10.1029/92JE02947 PG 33 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700011 ER PT J AU GREELEY, R SKYPECK, A POLLACK, JB AF GREELEY, R SKYPECK, A POLLACK, JB TI MARTIAN AEOLIAN FEATURES AND DEPOSITS - COMPARISONS WITH GENERAL-CIRCULATION MODEL RESULTS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID WIND STREAKS; EOLIAN FEATURES; SLOPE WINDS; MARS; MARINER-9; CLASSIFICATION; SIMULATIONS; EQUATORIAL; ATMOSPHERE; TRANSPORT AB The development of a general circulation model (GCM) of Mars' atmosphere allows questions to be addressed concerning the relationships between near-surface winds and the distribution of wind-related features and deposits. Predictions of wind surface stress as a function of season and dust optical depth are used to investigate the distribution and orientation of wind streaks, yardangs, and rock abundance on the surface. The occurrence and orientation of bright streaks are well accounted for by the GCM. Results suggest that bright streaks form during southern hemisphere summer by Hadley cell circulation, in which dust is raised in the southern hemisphere, carried northward at high altitudes, then deposited in the wake of craters and other topographic obstacles by the descending Hadley cell. The reduction in the number of bright streaks southward from 30-degrees-N is interpreted to reflect the depletion of dust by near-surface winds blowing to the south. Although the winds responsible for the formation of the dark streaks are not well reproduced in all areas by GCM simulations, a band of high wind surface stresses in the southern subtropics corresponding to the latitude band where most of the dark streaks are found are predicted at the height of the dust storm season (southern hemisphere summer). Yardang orientations do not match the GCM simulations for any season; their orientation is attributed to either structural control in the rocks (such as joint patterns) or to a change in wind patterns from the time when the yardangs formed. The global distribution of rocks on the surface is correlated well with predicted wind stress, particularly during dust storm season; the rocky areas are sites of strong winds, suggesting that fine material is swept away by the wind, leaving rocks and coarser material behind. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP GREELEY, R (reprint author), ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287, USA. NR 39 TC 76 Z9 78 U1 1 U2 6 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 FEB 25 PY 1993 VL 98 IS E2 BP 3183 EP 3196 DI 10.1029/92JE02580 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700012 ER PT J AU MURPHY, JR HABERLE, RM TOON, OB POLLACK, JB AF MURPHY, JR HABERLE, RM TOON, OB POLLACK, JB TI MARTIAN GLOBAL DUST STORMS - ZONALLY SYMMETRICAL NUMERICAL SIMULATIONS INCLUDING SIZE-DEPENDENT PARTICLE-TRANSPORT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID NONSPHERICAL PARTICLES; MARS ATMOSPHERE; SAHARAN DUST; CIRCULATION; SCATTERING; DYNAMICS; AEROSOLS; OPACITY AB The size-dependent transport of dust particles in the Martian atmosphere away from a specified surface source is numerically investigated employing a coupled system of a zonally symmetric primitive equation grid point model of the Martian atmosphere and an aerosol transport/microphysical model. The coupled model accounts for diabatic heating due to a radiatively active evolving dust field but neglects feedbacks between atmosphere-surface interactions and surface dust lifting, which is prescribed. The differing suspension lifetimes of various sized dust particles (radius = 1-80 mum) in conjunction with spatially varying atmospheric dynamics results in latitudinal differences in several measurements of the column integrated particle concentration. The latitudinal extent of dust (opacity) transport away from a southern subtropical source is enhanced by the presence in suspension of smaller dust particles (r < 1 mum) when compared to the presence of only a single dust particle size (2.5 mum). The input particle size distribution, that inferred by Toon et al. (1977) from Mariner 9 IRIS measurements, is not preserved in suspension at subsolar latitudes for spherical particles (r = 1 - 10 mum), counter to Toon et al.'s interpretation of IRIS spectra. Visible to 9-mum dust opacity ratios, which provide an indication of the relative number of large particles, are generally smaller (<1.7) than values (2-2.5) inferred from both Mariner 9 and Viking measurements. The invocation of slower falling nonspherical (disk) shaped particles results in an improved maintenance in suspension of the input particle size distribution at subtropical latitudes and visible to 9-mum opacity ratios in better agreement with inferred values. Calculated visible opacity values at the Viking lander latitudes increase less abruptly than was observed at the onsets of the two 1977 dust storms, which has implications for both source locations and magnitudes. This work indicates the importance of considering the full range of particle sizes (and shapes) of the suspended dust during Martian global dust storms and their impact upon the spatial extent and wavelength-dependent radiative influence of such storms. C1 UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. RP MURPHY, JR (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 43 TC 46 Z9 46 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 FEB 25 PY 1993 VL 98 IS E2 BP 3197 EP 3220 DI 10.1029/92JE02945 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700013 ER PT J AU MARTIN, LJ ZUREK, RW AF MARTIN, LJ ZUREK, RW TI AN ANALYSIS OF THE HISTORY OF DUST ACTIVITY ON MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID SOUTH POLAR-CAP; POLARIMETRIC ANALYSIS; MARTIAN ATMOSPHERE; STORMS; VIKING AB A new comprehensive list of possible and probable dust activity has been compiled from various published lists and additional data. All previously listed events have been reviewed and evaluated. For uniformity and clarity, each event is classified using a new system that includes a well-defined nomenclature. Maps showing the reported locations of individual major events, as well as a summary map of the smaller ''local'' events, have been compiled. Detailed commentaries describe the events and/or circumstances of their observation. The seasonal distribution of Martian dust events is diagrammed and discussed together with a seasonal and annual (Mars years) timeline that includes the frequency of photographic coverage. The new compilation shows that major dust storms have originated in many different regions across the planet, with some evidence of more activity in the southern hemisphere generally and in specific regions like Hellas. Regional dust storms have been observed in nearly all seasons, except for two relatively narrow periods which occur near times when the polar caps have reached their maximum/minimum extent. Regional dust storms tend to occur most frequently, and all planet-encircling dust storms have been observed during the southern spring and summer seasons, although there is significant interannual variability. C1 JET PROP LAB,PASADENA,CA 91109. RP MARTIN, LJ (reprint author), LOWELL OBSERV,1400 W MARS HILL RD,FLAGSTAFF,AZ 86001, USA. NR 86 TC 99 Z9 99 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-PLANET JI J. Geophys. Res.-Planets PD FEB 25 PY 1993 VL 98 IS E2 BP 3221 EP 3246 DI 10.1029/92JE02937 PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700014 ER PT J AU ZUREK, RW MARTIN, LJ AF ZUREK, RW MARTIN, LJ TI INTERANNUAL VARIABILITY OF PLANET-ENCIRCLING DUST STORMS ON MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID MARTIAN ATMOSPHERE; IMAGING OBSERVATIONS; THERMAL TIDES; OSCILLATIONS; CIRCULATION; HISTORY; SURFACE; OPACITY AB Interannual variability of the atmosphere of Mars is dominated by the occurence, or absence, of planet-encircling dust storms. In this paper we use a recent review of Earth-based telescopic observations of Mars together with Viking orbiter and lander data to estimate the frequency of occurrence of planet-encircling dust storms over the past century and to test whether the period spanned by the Mariner 9 and Viking missions to Mars is representative of the decades prior to 1950. In doing so, we take into account the practical limitations imposed on Earth-based coverage of Mars by the orbital geometries of the two planets. Both spacecraft and Earth-based observations suggest that planet-encircling dust storms on Mars occur during a so-called ''dust storm season'' in southern spring and summer. Viking data demonstrate decidedly that planet-encircling dust storms could have occurred in the past on Mars without being detected from Earth during years in which Mars was far from Earth during the dust storm season and thus difficult to observe. However, the same historical record indicates that planet-encircling storms were absent during the dust storm seasons monitored during several favorable oppositions prior to 1956 and after 1986. Overall, the chance of a planet-encircling dust storm occurring in any arbitrary Mars year is estimated to be approximately one in three (18-55 % at the 95 % level of confidence), if such occurrence is random from year-to-year and yet restricted seasonally to southern spring and summer. C1 LOWELL OBSERV,FLAGSTAFF,AZ 86001. RP ZUREK, RW (reprint author), JET PROP LAB,MS 169-237,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 48 TC 81 Z9 82 U1 3 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 FEB 25 PY 1993 VL 98 IS E2 BP 3247 EP 3259 DI 10.1029/92JE02936 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700015 ER PT J AU SANTEE, M CRISP, D AF SANTEE, M CRISP, D TI THERMAL STRUCTURE AND DUST LOADING OF THE MARTIAN ATMOSPHERE DURING LATE SOUTHERN SUMMER - MARINER-9 REVISITED SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID RADIO OCCULTATION MEASUREMENTS; RADIATIVE TRANSFER EQUATION; INFRARED SPECTROSCOPY; MARS; TEMPERATURE; SURFACE; MESOSPHERE; ALGORITHMS; SCATTERING; TOPOGRAPHY AB The temperature structure and dust loading of the Martian atmosphere are investigated using thermal emission spectra recorded by the Mariner 9 infrared interferometer spectrometer (IRIS). The analysis is restricted to a subset of the IRIS data consisting of approximately 2400 spectra in a 12-day period extending from L(S) = 343-degrees to L(S) = 348-degrees, corresponding to late southern summer on Mars. Simultaneous retrieval of the vertical distribution of both atmospheric temperature and dust optical depth is accomplished through an iterative procedure which is performed on each spectrum. The inclusion of dust opacity in the retrieval algorithm causes the retrieved temperatures to change by more than 20 K in some atmospheric layers. The largest column-integrated 9 mum dust optical depths (approximately 0.4) occur over the equatorial regions. The highest atmospheric temperatures (> 260 K) are found at low altitudes near the subsolar latitude (approximately 6-degrees-S), while the coldest temperatures (< 150 K) are found at levels near 1.0 mbar over the winter pole. A comparison of temperature maps for 1400 LT and 0200 LT indicates diurnal temperature variations as large as 80 K at low altitudes near the subsolar latitude, whereas diurnal temperature changes at pressures less than 1.0 mbar are typically about 10 K. Both dayside and nightside temperatures above about 0.1 mbar (approximately 40 km) are warmer over the winter (north) polar region than over the equator or the summer (south) polar region. This thermal structure suggests the existence of a net zonally averaged meridional circulation with rising motion at low latitudes, poleward flow at altitudes above 40 km, and subsidence over the poles. Because a meridional circulation transports atmospheric constituents as well as heat, it has significant implications for the net flux of dust and water into the polar regions. C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP SANTEE, M (reprint author), JET PROP LAB,MAIL CODE 183-701,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 49 TC 66 Z9 66 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 FEB 25 PY 1993 VL 98 IS E2 BP 3261 EP 3279 DI 10.1029/92JE01896 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700016 ER PT J AU BOUGHER, SW FESEN, CG RIDLEY, EC ZUREK, RW AF BOUGHER, SW FESEN, CG RIDLEY, EC ZUREK, RW TI MARS MESOSPHERE AND THERMOSPHERE COUPLING - SEMIDIURNAL TIDES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID GENERAL-CIRCULATION MODEL; SOLAR-CYCLE VARIATION; GREAT DUST STORMS; MARTIAN ATMOSPHERE; DYNAMICS; SIMULATIONS; TEMPERATURE; IONOSPHERE; COMPONENT; EQUINOX AB The National Center for Atmospheric Research thermosphere ionosphere general circulation model for Earth has been modified to examine the three-dimensional structure and circulation of the upper atmosphere of Mars (MTGCM) (Bougher et al., 1988b, 1990). Recent examination of Mariner 9 UVS airglow measurements taken during a global dust storm provide evidence of large temperature variations and atomic oxygen distributions uncorrelated with solar activity and the corresponding MTGCM in situ driven winds. We suspect significant forcing of the thermosphere from below as a result of upward propagating gravity waves or tides generated by solar heating of airborne dust (Stewart et al., 1992). The effects of upward propagating tides are introduced into the MTGCM by appropriately specifying its lower boundary condition according to classical tidal theory. We initially adapt the terrestrial scheme used by Fesen et al. (1986) to a Mars model appropriate to Mariner 9 near-solar-minimum conditions. Estimates of the amplitude and phase of the likely dominant semidiurnal (2,2) mode at the mesopause (approximately 100 km) are specified for a range of possible lower atmosphere dust conditions. MTGCM simulations contrasting tidally driven fields with solar-only forced ones show a dramatic change in the horizontal and vertical wind patterns, whereby the global temperature and oxygen distributions are also modified significantly. This semidiurnal component predominates below 135 km, while the in situ solar-driven diurnal component is largely dominant above. Constructive interference serves to enhance midafternoon exospheric temperatures toward Mariner 9 observed values. The thermospheric response and the altitude of penetration of these semidiurnal tides is found to be much greater during solar minimum periods when dissipation due to viscosity and thermal conductivity is diminished from that at solar maximum. Finally, the Martian response during dusty periods is predicted to be much larger than that typically observed for Earth. Martian dust-driven tides, especially during solar minimum time periods, cannot be ignored when addressing the Mars thermospheric structure and dynamics. C1 DARTMOUTH COLL,THAYER SCH ENGN,HANOVER,NH 03775. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. JET PROP LAB,PASADENA,CA 91109. RP BOUGHER, SW (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. RI Bougher, Stephen/C-1913-2013 OI Bougher, Stephen/0000-0002-4178-2729 NR 35 TC 28 Z9 29 U1 1 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 FEB 25 PY 1993 VL 98 IS E2 BP 3281 EP 3295 DI 10.1029/92JE02727 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700017 ER PT J AU ZENT, AP HABERLE, RM HOUBEN, HC JAKOSKY, BM AF ZENT, AP HABERLE, RM HOUBEN, HC JAKOSKY, BM TI A COUPLED SUBSURFACE-BOUNDARY LAYER MODEL OF WATER ON MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID THERMAL INERTIA; VAPOR AB We have written a one-dimensional numerical model of the exchange of H2O between the atmosphere and subsurface of Mars through the planetary boundary layer (PBL). Our goal is to explore the mechanisms of H2O exchange and to elucidate the role played by the regolith in the local H2O budget. The atmospheric model includes effects of Coriolis, pressure gradient, and frictional forces for momentum: radiation, sensible heat flux, and advection for heat. The model differs from Flasar and Goody by use of appropriate Viking-based physical constants and inclusion of the radiative effects of atmospheric dust. The pressure gradient force is specified or computed from a simple slope model. The subsurface model accounts for conduction of heat and diffusion of H2O through a porous adsorbing medium in response to diurnal forcing. The model is initialized with depth-independent H2O concentrations (2 kg m-3) in the regolith and a dry atmosphere. The model terminates when the atmospheric H2O column abundance stabilizes to 0.1% per sol. Results suggest that in most cases, the flux through the Martian surface reverses twice in the course of each sol. In the midmorning, the regolith begins to release H2O to the atmosphere and continues to do so until midafternoon, when it once more becomes a sink. ft remains an H2O sink throughout the Martian night. In the early morning and late afternoon, while the atmosphere is convective, the atmosphere supplies H2O to the ground al a rapid rate, occasionally resulting in strong pulses of H2O into the ground. The model also predicts that for typical conditions, perhaps 15-20 sols are required tor the regolith to supply an initially dry atmosphere with its equilibrium load The effects of surface albedo, thermal inertia, solar declination, atmospheric optical depth, and regolith pore structure are explored. Increased albedo cools the regolith, so less H2O appears in the atmospheric column above a bright surface. The friction velocity is higher above a dark surface, so there is more diurnal H2O exchange: relative humidities are much higher above a bright surface. Thermal inertia I affects the propagation of energy through a periodically heated homogeneous surface. Our results suggest that higher thermal inertia forces more H2O into the atmosphere because the regolith is warmer at depth. Surface stresses are higher above a low I surface, but there is less diurnal exchange because the atmosphere is dry. The latitude experiment predicts that the total diurnal insolation is more important to the adsorptively controlled H2O column abundance than the peak daytime surface temperature. Fogs and high relative humidity will be far more prevalent in the winter hemisphere. The dust opacity of the atmosphere plays a very significant role; the PBL height, column abundances, relative humidity. and surface stresses all increase very strongly as the optical depth approaches zero. The dust opacity of the atmosphere must be considered in subsequent PBL models. C1 NASA,AMES RES CTR,CTR MARS EXPLORAT,MOFFETT FIELD,CA 94035. SPACE PHYS RES INST,SUNNYVALE,CA 94087. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. UNIV COLORADO,DEPT GEOL SCI,BOULDER,CO 80309. RP ZENT, AP (reprint author), NASA,AMES RES CTR,INST SETI,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 32 TC 64 Z9 65 U1 0 U2 5 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 FEB 25 PY 1993 VL 98 IS E2 BP 3319 EP 3337 DI 10.1029/92JE02805 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700020 ER PT J AU BELL, JF MORRIS, RV ADAMS, JB AF BELL, JF MORRIS, RV ADAMS, JB TI THERMALLY ALTERED PALAGONITIC TEPHRA - A SPECTRAL AND PROCESS ANALOG TO THE SOIL AND DUST OF MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID REFLECTANCE SPECTROSCOPY; MAGNETIC-PROPERTIES; IRON-OXIDES; HEMATITE; PHOTOMETRY; MINERALOGY; GLASS; RATES AB We studied six palagonitic soil samples (PH-1 through PH-6) which were collected at 30-cm intervals from a lava slab on Mauna Kea, Hawaii. The samples represent an alteration sequence caused by heating during emplacement of molten lava over a preexisting tephra cone. They are both spectral and weathering/alteration process analogs to the Martian surface. Techniques employed included visible and near-IR spectroscopy, Mossbauer spectroscopy, and magnetic analysis. The two samples collected from beyond 90 cm from the slab (PH-5 and PH-6) did not see the transient heating event and are composed of coarse-grained glassy basaltic (hawaiitic) particles, some of which have been moderately palagonitized since formation of the cone in the late Pleistocene. The four samples closest to the slab (PH-1 through PH-4) have been strongly altered in response to heating during its emplacement; their iron oxide mineralogy is dominated by nanophase ferric oxide. The sample adjacent to the slab (PH-1), which would have seen the highest temperatures, has a factor of 3 less H2O and contains crystalline hematite and magnetite in addition to nanophase ferric oxide. Lesser amounts of magnetite, but not hematite, are present in samples 30 cm (PH-2) and 60 cm (PH-3) from the slab. The reflectivity spectra of samples PH-2 through PH-4 are similar to spectra of palagonites reported by other workers to be good Mars visible to near-IR spectral analogs. The reflectivity spectrum of PH-1 is an even better spectral analog to Mars in that it exhibits absorption features indicative of both nanophase and crystalline ferric oxides (similar to several new Martian telescopic data sets). Our sampling site may also be a process analog for Mars, in that heating episodes by volcanism and/or impact cratering could produce crystalline ferric oxides from poorly crystalline palagonitic material. Thus, localized thermal alteration events may provide a volumetrically important mechanism for the palagonitization of basaltic glass and the production of crystalline ferric oxides on Mars. C1 UNIV HAWAII MANOA,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058. UNIV WASHINGTON,DEPT GEOL,SEATTLE,WA 98195. NR 61 TC 69 Z9 69 U1 3 U2 6 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 FEB 25 PY 1993 VL 98 IS E2 BP 3373 EP 3385 DI 10.1029/92JE02367 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700024 ER PT J AU GOLDEN, DC MORRIS, RV MING, DW LAUER, HV YANG, SR AF GOLDEN, DC MORRIS, RV MING, DW LAUER, HV YANG, SR TI MINERALOGY OF 3 SLIGHTLY PALAGONITIZED BASALTIC TEPHRA SAMPLES FROM THE SUMMIT OF MAUNA-KEA, HAWAII SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT WORKSHOP ON THE MARTIAN SURFACE AND ATMOSPHERE THROUGH TIME CY SEP 23-25, 1991 CL BOULDER, CO ID MAGNETIC-PROPERTIES; MARS; SOIL; HEMATITE; SPECTRA; OXIDES; ROCK; DUST AB Certain palagonites from Hawaii are considered to be among the best analogs for Martian fines, based upon similar spectral properties. For this study, three distinctly colored layers were sampled from slightly palagonitized basaltic tephra just below the summit of Mauna Kea at 4145 m elevation. The mineralogy of size fractions of these samples was examined by diffuse reflectance (visible and near-IR) and far-IR spectroscopy, optical microscopy, X ray diffraction, Mossbauer spectroscopy, magnetic analysis, electron microprobe analysis (EMPA), and transmission and scanning electron microscopy. For the 20-1000 mum size fraction, sample HWMK11 (red) is essentially completely oxidized and has a hematite (Ti-hematite) pigment dispersed throughout the silicate matrix. The alteration is present throughout particle volumes, and only a trace amount of glass is present; no palagonitic rinds were detected. In addition to ferric Fe-Ti oxides, other phases detected were plagioclase feldspar and a trace of olivine. Sample HWMK12 (black) has the lowest proportion of ferric-bearing phases and is thus least weathered. It consists mostly of unaltered glass with embedded plagioclase and minor amounts of pyroxene, olivine, and Ti-magnetite. In some grains, a thin palagonitic rind is visible, indicating some surface alteration. The mineralogy for sample HWMK13 (yellow) is the same as that for HWMK12, except that it has distinct, well-developed palagonitic rinds consisting of erionite and smectite. For all samples, the amount of glass and plagioclase decreases and the amount of smectite increases with decreasing particle size for size fractions <20 mum. For HWMK11, the amount of hematite is essentially constant and mica is present only in the coarse clay-sized fraction; smectites are low in structural Fe. For HWMK12 and HWMK13, the zeolite erionite is present along with smectites and nanophase ferric oxides (np-Ox). Erionite abundance decreases and np-Ox abundance increases with decreasing particle size. The smectite in both black and yellow samples contains some Fe3+ in octahedral layers. There were only two mineral phases containing iron in the fine clay fraction. namely, smectites and iron oxides. For HWMK11, relatively large iron oxide particles (0.1 to 0.4 mum) were dispersed on clay surfaces; for HWMK12 and HWMK13, much finer np-Ox particles were present in lesser concentrations. Formation of the zeolite erionite is consistent with the arid climate zone where these samples were collected. However, transient hydrothermal processes that occurred during the eruption of Mauna Kea volcano under its permanent ice cap during the Pleistocene may have resulted in minerals such as zeolites and smectites which may persist as relicts over a long period of time. Most of the iron released during weathering of basaltic tephra precipitated as poorly crystalline iron oxides and some of the Fe has substituted for the octahedral cations in the structure of authigenic smectites. The Ti-hematite in HWMK11, however, is the result of high-temperature oxidation of Ti-magnetite and exsolution from iron-bearing silicate phases. Visible and near-IR reflectivity spectrum for the <20 mum size fraction of HWMK11 is dominated by well-crystalline Ti-hematite. Corresponding spectra for HWMK12 and HWMK13, whose ferric mineralogy is dominated by np-Ox particles, are more similar to Martian bright-region spectra. C1 LOCKHEED ESC,HOUSTON,TX 77058. RP GOLDEN, DC (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN4,HOUSTON,TX 77058, USA. NR 43 TC 48 Z9 48 U1 3 U2 10 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 FEB 25 PY 1993 VL 98 IS E2 BP 3401 EP 3411 DI 10.1029/92JE02590 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KX587 UT WOS:A1993KX58700026 ER PT J AU SCHATTEN, KH AF SCHATTEN, KH TI SOLAR PHYSICS - NATURAL-SELECTION IN THE CORONA SO NATURE LA English DT Editorial Material RP SCHATTEN, KH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 8 TC 0 Z9 0 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 FEB 25 PY 1993 VL 361 IS 6414 BP 683 EP 684 DI 10.1038/361683a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KN789 UT WOS:A1993KN78900025 ER PT J AU GEHRELS, N CHEN, W AF GEHRELS, N CHEN, W TI THE GEMINGA SUPERNOVA AS A POSSIBLE CAUSE OF THE LOCAL INTERSTELLAR BUBBLE SO NATURE LA English DT Article ID GAMMA-RAY SOURCE; OPTICAL COUNTERPART; UNIQUE OBJECT; 1E 0630+178; ERROR BOX; IDENTIFICATION; EXPLOSIONS; FIELD AB THE Solar System resides at the edge of a cavity of hot (10(6) K), low-density (5 x 10(-3) cm-3), X-ray emitting gas embedded in the interstellar medium1-4. This void, sometimes called the Local Bubble, is thought to be less than 10(7) years old, but its origin is unknown. Here we propose that the void was caused by the supernova that produced the Geminga pulsar. The initial identification5 of Geminga as a pulsar, and the subsequent detection6-8 of pulsations in high-energy gamma-rays, give an age of 3 x 10(5) years and a pulsar distance in the range 40 to 400 pc (refs 6, 7). Using this information, and the recently discovered9,10 proper motion of a likely optical counterpart, we find that the supernova was well positioned to produce the local void, provided that the explosion occurred within about 60 pc of the Solar System. Larger distances are not excluded by our analysis, but they would put the supernova at a position for which there is no evidence for such an energy input. RP GEHRELS, N (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RI Gehrels, Neil/D-2971-2012 NR 25 TC 66 Z9 66 U1 0 U2 0 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 25 PY 1993 VL 361 IS 6414 BP 706 EP 707 DI 10.1038/361706a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KN789 UT WOS:A1993KN78900048 ER PT J AU BREIT, GA WATENPAUGH, DE BALLARD, RE MURTHY, G HARGENS, AR AF BREIT, GA WATENPAUGH, DE BALLARD, RE MURTHY, G HARGENS, AR TI CUTANEOUS MICROVASCULAR FLOW RESPONSES DURING HEAD-UP TILT, CENTRIFUGATION, AND LBNP STRESSES SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A666 EP A666 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500849 ER PT J AU CHARLES, JB FRITSCH, JM JONES, MM AF CHARLES, JB FRITSCH, JM JONES, MM TI CHANGES IN BLOOD-PRESSURE DURING SPACE-FLIGHT RELATE TO CHANGES IN CAROTID BAROREFLEX FUNCTION IN HUMANS SO FASEB JOURNAL LA English DT Meeting Abstract C1 KRUG LIFE SCI,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 2 Z9 2 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A665 EP A665 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500844 ER PT J AU CRANDALL, CG ENGELKE, KA CONVERTINO, VA RAVEN, PB AF CRANDALL, CG ENGELKE, KA CONVERTINO, VA RAVEN, PB TI AORTIC BAROREFLEX CONTROL OF HEART-RATE FOLLOWING 15 DAYS OF SIMULATED MICROGRAVITY SO FASEB JOURNAL LA English DT Meeting Abstract C1 TEXAS COLL OSTEOPATH MED,FT WORTH,TX 76116. NASA,KENNEDY SPACE CTR,FL 32899. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A666 EP A666 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500850 ER PT J AU FORTNEY, S CHARLES, J WOOD, M DUSSACK, L AF FORTNEY, S CHARLES, J WOOD, M DUSSACK, L TI RESPONSES TO GRADED LOWER-BODY NEGATIVE-PRESSURE (LBNP) AFTER SPACE-FLIGHT SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 1 Z9 1 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A665 EP A665 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500842 ER PT J AU FRITSCH, JM REHBEIN, TL GOODENBERGER, EJ AF FRITSCH, JM REHBEIN, TL GOODENBERGER, EJ TI SPACEFLIGHT REDUCES ORTHOSTATIC TOLERANCE AND ARTERIAL BAROREFLEX SENSITIVITY IN HUMANS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A665 EP A665 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500846 ER PT J AU GRETEBECK, RJ SOCKI, RA DAVISSTREET, J SCHOELLER, D GIBSON, EK LANE, HW AF GRETEBECK, RJ SOCKI, RA DAVISSTREET, J SCHOELLER, D GIBSON, EK LANE, HW TI ENERGY-UTILIZATION DURING SPACE-FLIGHT - DOUBLY LABELED WATER MEASUREMENTS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,NUTR BIOCHEM LAB,HOUSTON,TX 77058. UNIV CHICAGO,CHICAGO,IL 60637. NR 0 TC 2 Z9 2 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A840 EP A840 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97501842 ER PT J AU GRINDELAND, RE GROSSMAN, E GOSSELINK, K TIPTON, CM WOODMAN, C MUKKU, VR ARNAUD, SB AF GRINDELAND, RE GROSSMAN, E GOSSELINK, K TIPTON, CM WOODMAN, C MUKKU, VR ARNAUD, SB TI ENDOCRINE FUNCTION IN THE SUSPENDED RAT SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV ARIZONA,DEPT EXERCISE & SPORTS SCI,TUCSON,AZ 85721. GENENTECH INC,S SAN FRANCISCO,CA 94080. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A667 EP A667 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500859 ER PT J AU HUTCHINSON, KJ HARGENS, AR MURTHY, G WATENPAUGH, DE CONVERTINO, VA WING, PC AF HUTCHINSON, KJ HARGENS, AR MURTHY, G WATENPAUGH, DE CONVERTINO, VA WING, PC TI 6-DEGREES HEAD-DOWN TILT AS A BACK PAIN MODEL FOR ACTUAL MICROGRAVITY SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,ARC,DIV LIFE SCI 23911,MOFFETT FIELD,CA 94035. NASA,KENNEDY SPACE CTR,FL 32899. UNIV BC,DEPT ORTHOPED SURG,VANCOUVER,BC,CANADA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A666 EP A666 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500853 ER PT J AU JONES, MM CHARLES, JB AF JONES, MM CHARLES, JB TI HUMAN BLOOD-PRESSURE AND HEART-RATE CHANGES DURING SPACE-SHUTTLE LANDING AND CREW EGRESS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 5 Z9 6 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A665 EP A665 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500843 ER PT J AU LATHERS, CM CHARLES, JB AF LATHERS, CM CHARLES, JB TI ORTHOSTATIC HYPOTENSION IN PATIENTS, BED REST SUBJECTS, AND ASTRONAUTS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. US FDA,ROCKVILLE,MD 20857. NR 6 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A666 EP A666 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500851 ER PT J AU LINDERMAN, JK GOSSELINK, KL GRINDELAND, RE BOOTH, FW MUKKU, VR AF LINDERMAN, JK GOSSELINK, KL GRINDELAND, RE BOOTH, FW MUKKU, VR TI THE SYNERGISTIC EFFECT OF EXERCISE AND GROWTH-HORMONE ON SKELETAL-MUSCLE ATROPHY DURING HIND-LIMB SUSPENSION SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV TEXAS,SCH MED,DEPT PHYSIOL,HOUSTON,TX 77225. GENENTECH INC,S SAN FRANCISCO,CA 94080. NR 1 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A668 EP A668 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500863 ER PT J AU MOORE, AD LEE, SMC BARROWS, LH FORTNEY, SM GREENISEN, MC AF MOORE, AD LEE, SMC BARROWS, LH FORTNEY, SM GREENISEN, MC TI ACCURACY OF SUBMAXIMAL PREDICTIONS OF MAXIMUM OXYGEN-CONSUMPTION SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,SBRI,EXERCISE PHYSIOL LAB,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A666 EP A666 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500848 ER PT J AU MURTHY, G BALLARD, RE BREIT, GA WATENPAUGH, DE HARGENS, AR AF MURTHY, G BALLARD, RE BREIT, GA WATENPAUGH, DE HARGENS, AR TI INELASTIC COMPRESSION DURING LEG EXERCISE INCREASES EFFICIENCY OF THE SKELETAL-MUSCLE PUMP SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A749 EP A749 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97501319 ER PT J AU NAVIDI, M HARPER, J FUNG, P EVANS, J WOLINSKY, I ARNAUD, SB AF NAVIDI, M HARPER, J FUNG, P EVANS, J WOLINSKY, I ARNAUD, SB TI THE EFFECT OF A SPACE-FLIGHT MODEL ON THE EXCRETION OF MINERALS AND ELECTROLYTES IN THE URINE OF MATURE RATS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HOUSTON,HOUSTON,TX 77204. NR 1 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A667 EP A667 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500855 ER PT J AU SICONOLFI, SF RODGERS, SL AF SICONOLFI, SF RODGERS, SL TI EFFECTS OF SPACE-FLIGHT AND EXERCISE ON ANAEROBIC CAPACITIES SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,HOUSTON,TX 77058. LOUISIANA STATE UNIV,RUSTON,LA 71272. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A665 EP A665 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500847 ER PT J AU VASGUES, M LANG, C GRINDELAND, R DAUNTON, N WADE, CE AF VASGUES, M LANG, C GRINDELAND, R DAUNTON, N WADE, CE TI EFFECTS OF HYPERGRAVITY AND MICROGRAVITY ON RAT-TISSUE WEIGHTS AND PLASMA CHEMISTRY SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A667 EP A667 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500857 ER PT J AU WHITSON, PA CHARLES, JB WILLIAMS, WJ AF WHITSON, PA CHARLES, JB WILLIAMS, WJ TI HUMAN SYMPATHOADRENAL RESPONSE TO STANDING AFTER SPACE-FLIGHT SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 1 Z9 1 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A620 EP A620 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500584 ER PT J AU WILLIAMS, WJ FORTNEY, SM STUART, CA PIETRZYK, RA CHEN, YM WHITSON, PA AF WILLIAMS, WJ FORTNEY, SM STUART, CA PIETRZYK, RA CHEN, YM WHITSON, PA TI HUMAN CARDIOVASCULAR-RESPONSE TO ALPHA-ADRENERGIC AND BETA-ADRENERGIC AGONISTS DURING BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV TEXAS,MED BRANCH,GEN CLIN RES CTR,GALVESTON,TX 77550. KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 23 PY 1993 VL 7 IS 4 BP A620 EP A620 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP975 UT WOS:A1993KP97500586 ER PT J AU MAOZ, D NETZER, H PETERSON, BM BECHTOLD, J BERTRAM, R BOCKAREV, NG CARONE, TE DIETRICH, M FILIPPENKO, AV KOLLATSCHNY, W KORISTA, KT SHAPOVALOVA, AI SHIELDS, JC SMITH, PS THIELE, U WAGNER, RM AF MAOZ, D NETZER, H PETERSON, BM BECHTOLD, J BERTRAM, R BOCKAREV, NG CARONE, TE DIETRICH, M FILIPPENKO, AV KOLLATSCHNY, W KORISTA, KT SHAPOVALOVA, AI SHIELDS, JC SMITH, PS THIELE, U WAGNER, RM TI VARIATIONS OF THE ULTRAVIOLET FE II AND BALMER CONTINUUM EMISSION IN THE SEYFERT-GALAXY NGC-5548 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-5548); GALAXIES, SEYFERT; TECHNIQUES, SPECTROSCOPIC; ULTRAVIOLET, GALAXIES ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; SIZE AB We present measurements of the Balmer continuum/Fe II emission blend (the '' small blue bump '') between 2160 and 4130 angstrom in the Seyfert galaxy NGC 5548. The measurements are from spectra obtained as part of the combined space-based and ground-based monitoring program of this object in 1988-1989. An iterative scheme is used to determine and subtract the continuum emission underlying the emission blend so as to obtain a light curve sampled once every 4 days. The small blue bump is an important component of the emission-line cooling, constituting about one third of the line flux in this object. Its flux varies with an amplitude of approximately +/- 20% about the mean, similar to the amplitude of the Balmer line variations during the same period. Its light curve resembles that of Lyalpha, with a lag of approximately 10 days behind the continuum variations. The bump variation amplitude is independent of the wavelength interval where it is measured, which indicates that both the Balmer continuum and Fe II emission have comparable variation amplitudes. These results suggest that the Fe II UV multiplets and the Balmer continuum are emitted in the same parts of the broad-line region as most other broad emission lines in this object. C1 CARNEGIE INST WASHINGTON OBSERV,PASADENA,CA 91101. ACAD SCI MOSCOW,SPECIAL ASTROPHYS OBSERV,MOSCOW,RUSSIA. MAX PLANCK INST ASTRON,W-6900 HEIDELBERG,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. TEL AVIV UNIV,SCH PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. UNIV MOSCOW,STERNBERG ASTRON INST,MOSCOW,RUSSIA. RP MAOZ, D (reprint author), INST ADV STUDY,PRINCETON,NJ 08540, USA. NR 20 TC 73 Z9 73 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 FEB 20 PY 1993 VL 404 IS 2 BP 576 EP 583 DI 10.1086/172310 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KL879 UT WOS:A1993KL87900017 ER PT J AU KIMBLE, RA DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KRISS, GA KRUK, JW LONG, KS MOOS, HW VANCURA, O AF KIMBLE, RA DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KRISS, GA KRUK, JW LONG, KS MOOS, HW VANCURA, O TI EXTREME ULTRAVIOLET OBSERVATIONS OF G191-B2B AND THE LOCAL INTERSTELLAR-MEDIUM WITH THE HOPKINS ULTRAVIOLET TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, ABUNDANCES; STARS, INDIVIDUAL (G191-B2B); ULTRAVIOLET, STARS ID X-RAY SPECTRUM; WHITE-DWARFS; IONIZATION; HYDROGEN; EXOSAT; MODEL; GAS AB During the Astro-1 mission in 1990 December, the Hopkins Ultraviolet Telescope (HUT) was used to observe the extreme ultraviolet spectrum (415-912 angstrom) of the hot DA white dwarf G191-B2B. Absorption by neutral helium shortward of the 504 angstrom He I absorption edge is clearly detected in the raw spectrum. Model fits to the observed spectrum require interstellar neutral helium and neutral hydrogen column densities of 1.45 +/- 0.065 x 10(17) cm-2 and 1.69 +/- 0.12 x 10(18) cm-2, respectively. Comparison of the neutral columns yields a direct assessment of the ionization state of the local interstellar cloud surrounding the Sun. The neutral hydrogen to helium ratio of 11.6 +/- 1.0 observed by HUT, like the lower signal-to-noise results of a similar measurement by Green, Jelinsky, & Bowyer (1990b), strongly contradicts the widespread view that hydrogen is much more ionized than helium in the local interstellar medium, a view which has motivated some exotic theoretical explanations for the supposed high ionization. In fact, the HUT observation implies somewhat greater ionization of helium than hydrogen in the local cloud, consistent with models of the local cloud based on known sources of ionization. Consistency with solar radiation backscatter measurements can be achieved if a neutral hydrogen attenuation mechanism such as the charge-exchange proposed by Ripken & Fahr (1983) operates at the heliopause. In that case, adjusting the typical backscatter-derived local densities for such an effect. we find that within the local cloud the particle densities are n(H) congruent-to 0.13-0.15 cm-3, n(He) congruent-to 0.01 3-0.015 cm-3 and n(e) congruent-to 0.03 cm-3; the ionized fractions are X(H) congruent-to 0.1-0.2 and X(He) congruent-to 0.1-0.35; the total hydrogen column density of the local cloud toward G191-B2B is approximately 2.2 x 10(18) CM-2 ; and the cloud extends approximately 5 pc in that direction. C1 JOHNS HOPKINS UNIV HOSP,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. UNIV CAMBRIDGE,OBSERV INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP KIMBLE, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. RI Kruk, Jeffrey/G-4047-2012 NR 44 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 FEB 20 PY 1993 VL 404 IS 2 BP 663 EP 672 DI 10.1086/172319 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KL879 UT WOS:A1993KL87900026 ER PT J AU SCHAEFER, BE COHEN, J TEEGARDEN, BJ CLINE, TL FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS PENDLETON, GN MATTESON, JL BAND, DL LESTRADE, JP AF SCHAEFER, BE COHEN, J TEEGARDEN, BJ CLINE, TL FISHMAN, GJ MEEGAN, CA WILSON, RB PACIESAS, WS PENDLETON, GN MATTESON, JL BAND, DL LESTRADE, JP TI MICROSECOND FLARES IN GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, BURSTS; GAMMA-RAYS, THEORY ID TELESCOPE; CATALOG AB It has been suggested that gamma-ray burst light curves may consist of many superposed flares with a duration shorter than 30 mus. If true, the implications for the interpretation of burst data are enormous. With the launch of the Compton Gamma-Ray Observatory, four predictions of Mitrofanov's suggestion can be tested. Our results which contradict this suggestion are (1) the photon arrival times are not correlated between independent detectors, (2) the spectral hardness and intensity does not depend on the detector area, (3) the bursts seen by detectors which measure photon positions do not see microsecond flares, and (4) burst positions deduced from detectors with different projected areas are close to the positions deduced from time-of-flight differences between separated spacecraft. We conclude, therefore, that gamma-ray bursts are not composed of microsecond flares. C1 UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. MISSISSIPPI STATE UNIV,MISSISSIPPI STATE,MS 39762. RP SCHAEFER, BE (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-62,HUNTSVILLE,AL 35812, USA. NR 20 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 FEB 20 PY 1993 VL 404 IS 2 BP 673 EP 677 DI 10.1086/172320 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KL879 UT WOS:A1993KL87900027 ER PT J AU MAZUR, JE MASON, GM KLECKER, B MCGUIRE, RE AF MAZUR, JE MASON, GM KLECKER, B MCGUIRE, RE TI THE ABUNDANCES OF HYDROGEN, HELIUM, OXYGEN, AND IRON ACCELERATED IN LARGE SOLAR PARTICLE EVENTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, ABUNDANCES; SUN, FLARES; SUN, PARTICLE EMISSION ID IONIC CHARGE-DISTRIBUTION; ENERGETIC PARTICLES; SHOCK ACCELERATION; FLARES AB Energy spectra measured in 10 large flares with the University of Maryland/Max-Planck-Institut sensors on ISEE 1 and Goddard Space Flight Center sensors on IMP 8 allowed us to determine the average H, He, O, and Fe abundances as functions of energy in the range of approximately 0.3-80 MeV nucleon-1. Model fits to the spectra of individual events using the predictions of a steady state stochastic acceleration model with rigidity-dependent diffusion provided a means of interpolating small portions of the energy spectra not measured with the instrumentation. Particles with larger mass-to-charge ratios were relatively less abundant at higher energies in the flare-averaged composition. The Fe/0 enhancement at low SEP energies was less than the Fe/O ratios observed in He-3-rich flares. Unlike the SEP composition averaged above 5 MeV nucleon-1, the average SEP abundances above 0.3 MeV nucleon-1 were similar to the average solar wind. C1 MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MAZUR, JE (reprint author), UNIV MARYLAND,DEPT PHYS,COLL PK,MD 20742, USA. OI Klecker, Berndt/0000-0001-8337-5120 NR 29 TC 41 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 FEB 20 PY 1993 VL 404 IS 2 BP 810 EP 817 DI 10.1086/172336 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KL879 UT WOS:A1993KL87900043 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI METHODOLOGICAL PROBLEMS WITH GAMMA-RAY BURST HARDNESS INTENSITY CORRELATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS ID EMISSION AB The hardness and intensity are easily measured quantities for all gamma-ray bursts (GRBs), and so, many past and current studies have sought correlations between them. This Letter presents many serious methodological problems with the practical definitions for both hardness and intensity. These difficulties are such that significant correlations can be easily introduced as artifacts of the reduction procedure. In particular, cosmological models of GRBs cannot be tested with hardness/intensity correlations with current instrumentation and the time evolution of the hardness in a given burst may be correlated with intensity for reasons that are unrelated to intrinsic change in the spectral shape. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 34 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 FEB 20 PY 1993 VL 404 IS 2 BP L87 EP L90 DI 10.1086/186750 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA KL881 UT WOS:A1993KL88100014 ER PT J AU BYRNE, GJ BENBROOK, JR BERING, EA FEW, AA MORRIS, GA TRABUCCO, WJ PASCHAL, EW AF BYRNE, GJ BENBROOK, JR BERING, EA FEW, AA MORRIS, GA TRABUCCO, WJ PASCHAL, EW TI GROUND-BASED INSTRUMENTATION FOR MEASUREMENTS OF ATMOSPHERIC CONDUCTION CURRENT AND ELECTRIC-FIELD AT THE SOUTH-POLE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB We have constructed instruments to measure the atmospheric conduction current and the atmospheric electric field: two fundamental parameters of the global-electric circuit. The instruments were deployed at the Amundsen-Scott South Pole Station in January 1991 and are designed to operate continuously for up to one year without operator intervention. The atmospheric current is measured by a sensor that uses a split-hemispheric conducting shell of 17.8-cm radius, separated by a thin Teflon insulating disk. The detection electronics are inside the sphere. In principle, the atmospheric current flows into one hemisphere, through the electronics where it is measured, and out the other hemisphere. The electric field is measured by a field mill of the rotating dipole type. The electric field sensing elements are two 30-cm-long antennas, driven to rotate in the vertical plane at 1800 rotations per minute. Two arrays of identical instruments have been deployed, separated by 600 m, in order to distinguish between atmospheric electrical signals of local and global origin. The separation distance of the arrays was determined by the climatology of the Antarctic plateau. Sample data from the first days of operation at the South Pole indicate variations in the global circuit over time scales from minutes, to hours, to days. C1 RICE UNIV,DEPT SPACE PHYS & ASTRON,HOUSTON,TX 77251. STANFORD UNIV,SPACE TELECOMMUN & RADIOSCI LAB,STANFORD,CA 94305. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP BYRNE, GJ (reprint author), UNIV HOUSTON,DEPT PHYS,HOUSTON,TX 77204, USA. NR 10 TC 22 Z9 22 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 FEB 20 PY 1993 VL 98 IS D2 BP 2611 EP 2618 DI 10.1029/92JD02303 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900001 ER PT J AU KAUFMAN, YJ AF KAUFMAN, YJ TI AEROSOL OPTICAL-THICKNESS AND ATMOSPHERIC PATH RADIANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SCALE AIR-POLLUTION; SATELLITE MEASUREMENTS; TROPOSPHERIC AEROSOLS; SCATTERING; CLIMATE; IMAGERY; DUST; REFLECTANCE; RADIATION; PARTICLES AB Spaceborne remote sensing of aerosol particles, evaluation of the climatic effects of aerosol, and atmospheric corrections of spaceborne imagery of the Earth's surface are based on an assumed relationship between the spectral aerosol optical thickness and the spectral path radiance. Path radiance is the radiance detected by a spaceborne sensor above a nonreflective surface and is the result of backscattering to space by particles and molecules in the atmosphere. In specific measurement conditions the path radiance can be measured also from the ground. Simultaneous measurements of the path radiance and the optical thickness from the ground are reported at over 30 locations spread all over the world. All the measurements are performed with a single eight-channel portable sunphotometer/radiometer in the 0.44- to 1.03-mum range. The observations are taken for constant solar and view directions, resulting in a constant scattering angle of 120-degrees, which resembles space observations. One set of measurements is used to develop empirical relationships between the aerosol spectral optical thickness and the scattered spectral path radiance. A second independent set is used to test these relationships. It is shown that simple measurements performed from the ground can yield empirical relationships that can be used to check some of the common but not validated assumptions about the particle homogeneity, sphericity, composition, and size distribution used in remote sensing models and in estimates of the radiative effects of aerosol. Results are summarized in Table 4 and used to test concepts of atmospheric corrections and remote sensing of aerosol from space. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 49 TC 113 Z9 116 U1 1 U2 8 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 FEB 20 PY 1993 VL 98 IS D2 BP 2677 EP 2692 DI 10.1029/92JD02427 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900008 ER PT J AU KING, MD RADKE, LF HOBBS, PV AF KING, MD RADKE, LF HOBBS, PV TI OPTICAL-PROPERTIES OF MARINE STRATOCUMULUS CLOUDS MODIFIED BY SHIPS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONDENSATION NUCLEI; SOLAR-RADIATION; SCATTERING; ATMOSPHERE; ABSORPTION; PHYSICS; ALBEDO AB The angular distribution of scattered radiation deep within a cloud layer was measured in marine stratocumulus clouds modified by the emissions from ships. These observations, obtained at 13 discrete wavelengths between 0.5 and 2.3 mum, were acquired as the University of Washington C-131A aircraft flew through a pair of roughly parallel ship track signatures produced in clouds off the coast of southern California on July 10, 1987. In the first of these ship tracks, the nadir (upwelling) intensity increased from 40 to 110 W m-2 mum-1 sr-1 at 0.744 mum. The second ship track produced a less dramatic, but more uniform, increase in the upwelling intensity. In contrast, the nadir intensity at 2.20 mum decreased from 1 to 0.13 W m-2 mum-1 sr-1 in the first ship track and to 0.6 W m-2 mum-1 sr-1 in the second ship track. The relative angular distribution of the intensity field at each wavelength was used to determine the similarity parameter, and hence single scattering albedo, of the cloud using the diffusion domain method. Besides the spectral similarity parameter, these measurements provide a good estimate of the optical depth of the cloud layer both above and below the aircraft. Results of this analysis are presented for a 120-km section of marine stratocumulus cloud including both ship tracks. This analysis shows that the total optical thickness of the cloud layer increased in the ship tracks, in contrast to the similarity parameter which decreased. The decrease in absorption was a direct consequence of the reduction in cloud droplet size that occurred within the ship tracks. C1 UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. RP KING, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 900,GREENBELT,MD 20771, USA. RI King, Michael/C-7153-2011 OI King, Michael/0000-0003-2645-7298 NR 35 TC 60 Z9 62 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 FEB 20 PY 1993 VL 98 IS D2 BP 2729 EP 2739 DI 10.1029/92JD02082 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900012 ER PT J AU KUMMEROW, C AF KUMMEROW, C TI ON THE ACCURACY OF THE EDDINGTON APPROXIMATION FOR RADIATIVE-TRANSFER IN THE MICROWAVE-FREQUENCIES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONVECTIVE RAINFALL; MULTIPLE-SCATTERING; SATELLITE; HYDROMETEORS; RADIANCES; CLOUDS; RATES; MEDIA AB Radiative transfer calculations in the presence of clouds and precipitation simplify as the wavelengths of the radiation approach the Rayleigh scattering regime. In particular, the transfer of microwave radiation is often simpler than the equivalent calculations at shorter wavelengths because the order of quadrature and moments of the phase function needed for the treatment of scattering decrease as the wavelength increases. The purpose of this paper is to examine how well an Eddington approximation can reproduce brightness temperatures obtained from a more complete, N-stream discrete ordinate solution in the microwave regime. Radiation propagating through a plane parallel medium will be considered in this discussion. Although model discrepancies are complicated functions of the cloud constituents, the differences between an eight-stream discrete ordinate solution and an analytical Eddington solution were generally small, ranging from 0 to 6-degrees-K when only one uniform layer of hydrometeors was considered. When realistic, multilayered cloud hydrometeor profiles were used, the differences between these two models never exceeded 3-degrees-K over the entire range of microwave frequencies considered (6.6-183 GHz). The models agreed to within 0.2-degrees-K in the absence of scattering constituents. RP KUMMEROW, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 22 TC 126 Z9 129 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 FEB 20 PY 1993 VL 98 IS D2 BP 2757 EP 2765 DI 10.1029/92JD02472 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900015 ER PT J AU SCHOEBERL, MR DOIRON, SD LAIT, LR NEWMAN, PA KRUEGER, AJ AF SCHOEBERL, MR DOIRON, SD LAIT, LR NEWMAN, PA KRUEGER, AJ TI A SIMULATION OF THE CERRO HUDSON SO2 CLOUD SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB An isentropic trajectory model is used to simulate the evolution of the southern hemisphere SO2 cloud associated with the eruption of Cerro Hudson. By matching the parcel trajectories with total ozone mapping spectrometer SO2 retrievals, the principal stratospheric injection region is determined to be between 11 and 16 km in altitude. This region is characterized by weak wind shears and is located just poleward of the subtropical jet in the outer fringe of the stratospheric polar vortex. The lack of wind shear in the injection region explains the slow zonal dispersal of the SO2 cloud which was still clearly observed 19 days after the eruption. The trajectory model simulation of the SO2 cloud shows good agreement with observations for 7 days after the eruption, Using the potential vorticity and potential temperature estimates of the initial eruption cloud, the cloud position relative to the polar night jet is shown to be nearly fixed up to September 2, 1991, which was as long as the cloud was observed. This result suggests that the lower stratospheric polar and mid-latitude regions are nearly isolated from each other during the late August period. C1 HUGHES STX CORP,LANHAM,MD 20706. RP SCHOEBERL, MR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 916,GREENBELT,MD 20771, USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 9 TC 63 Z9 63 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 FEB 20 PY 1993 VL 98 IS D2 BP 2949 EP 2955 DI 10.1029/92JD02517 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900028 ER PT J AU DELUISI, JJ LONGENECKER, DU MATEER, CL CHU, WP AF DELUISI, JJ LONGENECKER, DU MATEER, CL CHU, WP TI ESTIMATION OF SOLAR BACKSCATTER ULTRAVIOLET ALBEDO USING GROUND-BASED UMKEHR MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE AB A retrieval method was developed to estimate the solar backscatter ultraviolet (SBUV) satellite albedo for the ozone profiler wavelengths using ground-based ultraviolet measurements. For the present investigation the Umkehr was used as the ground-based ultraviolet measurement. Simulated SBUV data and Umkehr data theoretically computed from a priori ozone profiles observed by the SAGE 11 satellite were used to develop the retrieval algorithm and to test its capability. The test indicated that albedos for the SBUV ozone profiler wavelengths should allow estimates to a precision of +/-5% or better, depending on the accuracy of the ultraviolet measurement. Retrievals using actual Umkehr observations were also performed to provide a preliminary look at the magnitude and annual variation of retrieved albedos. A case study was performed, comparing retrieved albedos with SBUV-measured albedos. The SBUV albedo change was seen to be approximately twice as large as the albedo changes estimated by the Umkehr method. Results of the investigation suggest that the method of estimation may be useful for determining the drift rate of the SBUV calibration. C1 UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DELUISI, JJ (reprint author), NOAA,ENVIRONM RES LABS,BOULDER,CO 80303, USA. NR 20 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 FEB 20 PY 1993 VL 98 IS D2 BP 2985 EP 2993 DI 10.1029/92JD02214 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA KN689 UT WOS:A1993KN68900032 ER PT J AU SODUPE, M BAUSCHLICHER, CW AF SODUPE, M BAUSCHLICHER, CW TI THE BONDING IN THE LOW-LYING STATES OF MGO2+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID LIGAND BINDING-ENERGIES; GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; ROW ATOMS; CONTRACTION; O2 AB The 2A2 ground state of MgO2+, is of Mg2+O2- character with an Mg+-O2 binding energy of 23.3 kcal/mol. The linear 4SIGMA- state, which is bound by a charge-quadrupole interaction, has a significantly smaller binding energy (5.9 kcal/mol). Unlike many Mg+-ligand systems, there are no observable bound-bound transitions for MgO2+ below 35000 cm-1. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 26 TC 18 Z9 18 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 FEB 19 PY 1993 VL 203 IS 2-3 BP 215 EP 219 DI 10.1016/0009-2614(93)85390-A PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KL975 UT WOS:A1993KL97500022 ER PT J AU KREBS, JM DENNEY, RM SCHNEIDER, VS LANE, HW AF KREBS, JM DENNEY, RM SCHNEIDER, VS LANE, HW TI THE EFFECT OF SLIGHTLY ELEVATED EXTERNAL POTASSIUM (12 MM) ON RAT MYOBLAST OMEGA (RMO) CELLS SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV TEXAS,MED BRANCH,GALVESTON,TX 77550. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A223 EP A223 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97401286 ER PT J AU LEE, SMC MOORE, AD BARROWS, LH FORTNEY, SM GREENISEN, MC AF LEE, SMC MOORE, AD BARROWS, LH FORTNEY, SM GREENISEN, MC TI PREDICTION SENSITIVITY OF MAXIMAL OXYGEN-CONSUMPTION ON THE CYCLE ERGOMETER SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,SBRI,EXERCISE PHYSIOL LAB,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A452 EP A452 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97402616 ER PT J AU REID, IA GOYER, M CHOU, L EVANS, J KEIL, LC AF REID, IA GOYER, M CHOU, L EVANS, J KEIL, LC TI EFFECT OF INHIBITION OF NITRIC-OXIDE SYNTHESIS ON VASOPRESSIN SECRETION IN CONSCIOUS RABBITS SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A433 EP A433 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97402504 ER PT J AU RODGERS, SL SICONOLFI, SF AF RODGERS, SL SICONOLFI, SF TI ESTIMATING ANAEROBIC CAPACITY (ANC) FROM A GRADED-EXERCISE TEST (GXT) SO FASEB JOURNAL LA English DT Meeting Abstract C1 LOUISIANA TECH UNIV,RUSTON,LA 71270. NASA,HOUSTON,TX 77058. NR 0 TC 1 Z9 1 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A452 EP A452 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97402614 ER PT J AU VONDEUTSCH, DA JAWEED, MM FEEBACK, DL AF VONDEUTSCH, DA JAWEED, MM FEEBACK, DL TI EFFECT OF CLENBUTEROL ON PRIMARY HUMAN MYOTUBES SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77059. NATL RES COUNCIL,HOUSTON,TX 77054. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A479 EP A479 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97402776 ER PT J AU WADE, CE AF WADE, CE TI ATTENUATION BY EXERCISE OF CARDIOVASCULAR AND NEUROENDOCRINE RESPONSES TO HEMORRHAGIC HYPOTENSION SO FASEB JOURNAL LA English DT Meeting Abstract C1 LETTERMAN ARMY INST RES,SAN FRANCISCO,CA 94129. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD FEB 19 PY 1993 VL 7 IS 3 BP A19 EP A19 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA KP974 UT WOS:A1993KP97400108 ER PT J AU KIEFER, WS AF KIEFER, WS TI MANTLE VISCOSITY STRATIFICATION AND FLOW GEOMETRY - IMPLICATIONS FOR SURFACE MOTIONS ON EARTH AND VENUS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ISHTAR TERRA; EVOLUTION; MODEL; MECHANISMS; TECTONICS AB For a fixed heat flow, the surface flow velocity of a convecting layer is not strongly sensitive to the variation of viscosity as a function of depth. Thus, the inferred absence of a low viscosity asthenosphere on Venus can not account for the limited surface motions there. The surface velocity is dependent on the convective geometry. Cartesian geometry convection can produce large surface velocities if the high viscosity surface layer is broken in places by weak zones. On the other hand, a high viscosity surface layer may inhibit the development of large surface velocities in axisymmetric convection. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. RP KIEFER, WS (reprint author), LUNAR & PLANETARY INST,3600 BAY AREA BLVD,HOUSTON,TX 77058, USA. OI Kiefer, Walter/0000-0001-6741-5460 NR 20 TC 3 Z9 3 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 FEB 19 PY 1993 VL 20 IS 4 BP 265 EP 268 DI 10.1029/93GL00129 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KQ020 UT WOS:A1993KQ02000003 ER PT J AU GROSS, RS AF GROSS, RS TI THE EFFECT OF OCEAN TIDES ON THE EARTHS ROTATION AS PREDICTED BY THE RESULTS OF AN OCEAN TIDE MODEL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INNER CORE DYNAMICS; FORCED NUTATIONS; PERIODIC CHANGES; ATMOSPHERE; WOBBLE AB The published ocean tidal angular momentum results of Seiler [1991] are used to predict the effects of the most important semidiurnal (M2, S2, N2), diurnal (K1, O1, P1), and long period (Mf, Mf', Mm, and Ssa) ocean tides on the Earth's rotation. The separate, as well as combined, effects of ocean tidal currents and sea level height changes on the length-of-day, UTI, and polar motion are computed. The predicted polar motion results reported here account for the presence of the free core nutation and are given in terms of the motion (within the rotating, body-fixed terrestrial reference frame) of the celestial ephemeris pole so that they can be compared directly to the results of observations. Outside the retrograde diurnal tidal band, the summed effect of the semidiurnal and diurnal ocean tides studied here predict peak-to-peak polar motion amplitudes as large as 2 mas. Within the retrograde diurnal tidal band, the resonant enhancement caused by the free core nutation leads to predicted polar motion (or, equivalently, nutation) amplitudes as large as 9 mas (at the unobservable retrograde K1 tidal frequency). RP GROSS, RS (reprint author), JET PROP LAB,MS 238-232,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 50 Z9 50 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 FEB 19 PY 1993 VL 20 IS 4 BP 293 EP 296 DI 10.1029/93GL00297 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KQ020 UT WOS:A1993KQ02000010 ER PT J AU GAO, BC GOETZ, AFH WISCOMBE, WJ AF GAO, BC GOETZ, AFH WISCOMBE, WJ TI CIRRUS CLOUD DETECTION FROM AIRBORNE IMAGING SPECTROMETER DATA USING THE 1.38 MU-M WATER-VAPOR BAND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SATELLITE AB Thin cirrus clouds are difficult to detect, particularly over land, in images taken from current satellite platforms. Using spectral images acquired by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at 20 km altitude, we show that wavelengths close to the center of the strong 1.38 mum water vapor band are useful for detecting thin cirrus clouds. The detection makes use of the fact that cirrus clouds are located above almost all the atmospheric water vapor. Because of the strong water vapor absorption in the lower atmosphere, AVIRIS channels near 1.38 mum receive little scattered solar radiance from the surface or low level clouds. When cirrus clouds are present, however, these channels receive large amounts of scattered solar radiance from the cirrus clouds. Our ability to determine cirrus cloud cover using space-based remote sensing will be improved if channels near the center of the 1.38 mum water vapor band are added to future satellites. C1 NASA,GODDARD SPACE FLIGHT CTR,CLIMATE & RADIAT BRANCH,GREENBELT,MD 20770. RP GAO, BC (reprint author), UNIV COLORADO,CIRES,CTR STUDY EARTH SPACE,CAMPUS BOX 449,BOULDER,CO 80309, USA. RI Wiscombe, Warren/D-4665-2012 OI Wiscombe, Warren/0000-0001-6844-9849 NR 10 TC 103 Z9 111 U1 0 U2 5 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 FEB 19 PY 1993 VL 20 IS 4 BP 301 EP 304 DI 10.1029/93GL00106 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KQ020 UT WOS:A1993KQ02000012 ER PT J AU REINER, MJ FAINBERG, J STONE, RG AF REINER, MJ FAINBERG, J STONE, RG TI SOURCE CHARACTERISTICS AND LOCATIONS OF HECTOMETRIC RADIO EMISSIONS FROM THE NORTHERN JOVIAN HEMISPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND CONTROL; KILOMETRIC RADIATION AB Northern Jovian hectometric (HOM) radio emissions, detected from high Jovian latitudes by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft, were observed at all Jovian longitudes. This emission was observed to be predominantly right-hand circularly polarized, but some left-hand circular polarization was observed implying the presence of 0 mode emissions from the northern Jovian hemisphere. Intense HOM emissions, with well-defined directions and polarizations, were often confined to similar longitudinal regions where intense HOM emissions were previously observed at low latitudes. The present analysis confirms that these northern HOM sources lie in the Jovian polar regions on magnetic field lines that pass through the lo plasma torus. The observations may be consistent with emission from either a filled cone beam or a longitudinal distribution of thin hollow cones. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERRESTRIAL PHYS LAB,GREENBELT,MD 20771. RP REINER, MJ (reprint author), HUGHES STX CORP,LANHAM,MD, USA. NR 18 TC 26 Z9 26 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 FEB 19 PY 1993 VL 20 IS 4 BP 321 EP 324 DI 10.1029/93GL00245 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KQ020 UT WOS:A1993KQ02000017 ER PT J AU SUESS, ST NERNEY, S AF SUESS, ST NERNEY, S TI THE POLAR HELIOSPHERIC MAGNETIC-FIELD SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLOW DOWNSTREAM; TERMINAL SHOCK; HELIOPAUSE AB We describe the large-scale magnetic field morphology in the heliosheath. A simple argument, which depends only on the interstellar wind flowing nearly in the solar equatorial plane, shows that polar heliospheric magnetic fieldlines never approach the heliopause and therefore are accessible to galactic cosmic rays only through perpendicular diffusion. The same argument implies reconnection, at fine scales (ca. 0.2 AU), on the nose of the heliopause, between the interplanetary magnetic field and the magnetic field in the local interstellar medium (LISM). Galactic cosmic rays therefore have direct access across the heliopause to fieldlines connected to equatorial regions of the inner solar system. RP SUESS, ST (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES52,HUNTSVILLE,AL 35812, USA. NR 14 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 FEB 19 PY 1993 VL 20 IS 4 BP 329 EP 332 DI 10.1029/93GL00240 PG 4 WC Geosciences, Multidisciplinary SC Geology GA KQ020 UT WOS:A1993KQ02000019 ER PT J AU SCHUTTE, WA ALLAMANDOLA, LJ SANDFORD, SA AF SCHUTTE, WA ALLAMANDOLA, LJ SANDFORD, SA TI FORMALDEHYDE AND ORGANIC-MOLECULE PRODUCTION IN ASTROPHYSICAL ICES AT CRYOGENIC TEMPERATURES SO SCIENCE LA English DT Article ID MU-M; COMET; EMISSION AB Thermally promoted formaldehyde (H2CO) reactions in cryogenic ices have been studied to test their importance as a source of organic molecules in comets and interstellar ices. Ices containing H2CO, H2O, CH3OH, CO, and NH3 were investigated by using infrared spectroscopy. Small traces of NH3 (NH3/H2CO greater-than-or-equal-to 0.005) are sufficient to convert significant fractions (greater-than-or-equal-to 40%) of the H2CO into more complex organics. However, H2CO reactions do not proceed without NH3. Spectral evidence for reaction onset appeared between 40 and 80 kelvin, depending on the ice. Five distinct products were formed. These principally consist of polyoxymethylene and related derivatives. Polyoxymethylene itself was not made in significant amounts in cometary analogs. These products differ from those produced by ultraviolet and particle irradiation. The nature and relative amounts of the products depend on the initial composition, making these materials excellent tracers of a comet's history. About 3% of the organics in p-Halley's coma could have been produced by thermal H2CO reactions. RP SCHUTTE, WA (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 15 TC 64 Z9 64 U1 3 U2 15 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD FEB 19 PY 1993 VL 259 IS 5098 BP 1143 EP 1145 DI 10.1126/science.11540093 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KM917 UT WOS:A1993KM91700033 PM 11540093 ER PT J AU MARGOLIS, JS AF MARGOLIS, JS TI SPECTROSCOPY OF THE EARTHS ATMOSPHERE AND INTERSTELLAR-MEDIUM - RAO,KN, WEBER,A SO SCIENCE LA English DT Book Review RP MARGOLIS, JS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 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 FEB 19 PY 1993 VL 259 IS 5098 BP 1209 EP 1210 DI 10.1126/science.259.5098.1209 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA KM917 UT WOS:A1993KM91700046 PM 17794402 ER PT J AU SIMONS, RN TAUB, SR AF SIMONS, RN TAUB, SR TI COPLANAR WAVE-GUIDE RADIAL LINE STUB SO ELECTRONICS LETTERS LA English DT Article DE WAVE-GUIDES; RESONATORS; SILICON AB A coplanar waveguide radial line stub resonator is experimentally characterised with respect to stub radius, sectoral angle, substrate thickness and relative dielectric constant. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 3 Z9 3 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD FEB 18 PY 1993 VL 29 IS 4 BP 412 EP 414 DI 10.1049/el:19930276 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA LB766 UT WOS:A1993LB76600057 ER PT J AU SICONOLFI, SF AF SICONOLFI, SF TI A SIMPLE, VALID STEP TEST FOR ESTIMATING MAXIMAL OXYGEN-UPTAKE IN EPIDEMIOLOGIC STUDIES - REPLY SO AMERICAN JOURNAL OF EPIDEMIOLOGY LA English DT Letter RP SICONOLFI, SF (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058, USA. NR 5 TC 0 Z9 0 U1 1 U2 1 PU JOHNS HOPKINS UNIV SCHOOL HYGIENE PUB HEALTH PI BALTIMORE PA 111 MARKET PLACE, STE 840, BALTIMORE, MD 21202-6709 SN 0002-9262 J9 AM J EPIDEMIOL JI Am. J. Epidemiol. PD FEB 15 PY 1993 VL 137 IS 4 BP 483 EP 484 PG 2 WC Public, Environmental & Occupational Health SC Public, Environmental & Occupational Health GA KV977 UT WOS:A1993KV97700014 ER PT J AU MACINNES, AN POWER, MB BARRON, AR JENKINS, PP HEPP, AF AF MACINNES, AN POWER, MB BARRON, AR JENKINS, PP HEPP, AF TI ENHANCEMENT OF PHOTOLUMINESCENCE INTENSITY OF GAAS WITH CUBIC GAS CHEMICAL VAPOR-DEPOSITED USING A STRUCTURALLY DESIGNED SINGLE-SOURCE PRECURSOR SO APPLIED PHYSICS LETTERS LA English DT Article ID PHOTOCHEMICALLY UNPINNED GAAS; PHOTOELECTRON-SPECTROSCOPY; SURFACE RECOMBINATION; ELECTRONIC-PROPERTIES; BIPOLAR-TRANSISTOR; GAAS(100) SURFACES; PASSIVATION; HETEROJUNCTION; STABILITY; BONDS AB A two order-of-magnitude enhancement of photoluminescence intensity relative to untreated GaAs has been observed for GaAs surfaces coated with chemical vapor-deposited GaS. The increase in photoluminescence intensity can be viewed as an effective reduction in surface recombination velocity and/or band bending. The gallium cluster [(t-Bu)GaS]4 was used as a single-source precursor for the deposition of GaS thin films. The cubane core of the structurally characterized precursor is retained in the deposited film producing a cubic phase. Furthermore, a near-epitaxial growth is observed for the GaS passivating layer. Films were characterized by transmission electron microscopy, x-ray powder diffraction, and x-ray photoelectron and Rutherford backscattering spectroscopies. C1 HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. HARVARD UNIV,MAT RES LAB,CAMBRIDGE,MA 02138. OI Barron, Andrew/0000-0002-2018-8288 NR 38 TC 73 Z9 74 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 15 PY 1993 VL 62 IS 7 BP 711 EP 713 DI 10.1063/1.108847 PG 3 WC Physics, Applied SC Physics GA KL878 UT WOS:A1993KL87800017 ER PT J AU WALCH, SP AF WALCH, SP TI COMPUTED BARRIER HEIGHTS FOR H+CH2O[--]CH3O[--]CH2OH SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; CH3O AB The barrier heights (including zero-point effects) for H + CH2O --> CH3O and CH3O --> CH2OH have been computed using complete active space self-consistent field (CASSCF)/gradient calculations to define the stationary point geometries and harmonic frequencies and internally contracted configuration-interaction (CCI) to refine the energetics. The computed barrier heights are 5.6 and 30.1 kcal/mol, respectively. The former barrier height compares favorably to an experimental activation energy of 5.2 kcal/mol. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP WALCH, SP (reprint author), ELORET INST,PALO ALTO,CA 94303, USA. NR 11 TC 48 Z9 48 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD FEB 15 PY 1993 VL 98 IS 4 BP 3076 EP 3077 DI 10.1063/1.464134 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA KP938 UT WOS:A1993KP93800057 ER PT J AU COMISO, JC MCCLAIN, CR SULLIVAN, CW RYAN, JP LEONARD, CL AF COMISO, JC MCCLAIN, CR SULLIVAN, CW RYAN, JP LEONARD, CL TI COASTAL ZONE COLOR SCANNER PIGMENT CONCENTRATIONS IN THE SOUTHERN-OCEAN AND RELATIONSHIPS TO GEOPHYSICAL SURFACE-FEATURES SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID MARGINAL ICE-ZONE; WINTER MIXED LAYER; WEDDELL SEA; PHYTOPLANKTON GROWTH; SOLAR IRRADIANCE; ROSS SEA; PACK ICE; EDGE; AUTUMN; DISTRIBUTIONS AB The spatial and seasonal distributions of phytoplankton pigment concentration over the entire southern ocean have been studied for the first time using the coastal zone color scanner historical data set (from October 1978 through June 1986). Enhanced pigment concentrations are observed between 35-degrees-S and 55-degrees-S throughout the year, with such enhanced regions being more confined to the south in the austral summer and extending further north in the winter. North and south of the polar front, phytoplankton blooms (>1 mg/m3) are not uniformly distributed around the circumpolar region. Instead, blooms appear to be located in regions of ice retreat (or high melt areas) such as the Scotia Sea and the Ross Sea, in relatively shallow areas (e.g., the Patagonian and the New Zealand shelves), in some regions of Ekman upwelling like the Tasman Sea, and near areas of high eddy kinetic energy such as the Agulhas retroflection. Among all features examined by regression analysis, bathymetry appears to be the one most consistently correlated with pigments (correlation coefficient being about -0.3 for the entire region). The cause of negative correlation with bathymetry is unknown but is consistent with the observed abundance of iron in shallow areas in the Antarctic region. It is also consistent with resuspension of phytoplankton cells by wind-induced mixing, especially in shallow waters. On the other hand, in the deep ocean (especially at latitudes <45-degrees-S where surface nutrients may be limiting), upwelling induced by topographic features may cause resupply of nutrients to the surface and shoaling of the subsurface chlorophyll maximum. Low pigment values are common at low latitudes and in regions of high wind stress, where deep mixing and net loss of surface pigment occur. Nutrients (phosphate, nitrate, and silicate) are found to correlate significantly with pigments when the entire southern ocean is considered, but south of 55-degrees-S the correlation is poor, probably because the Antarctic waters are not nutrient limited. Nutrients are also highly correlated with Ekman upwelling. Although cloud cover and normalized aerosol radiance are correlated to the patterns of pigment concentrations in some areas, the correlations are weak in other areas, suggesting that light and iron may not be the primary factors responsible for the spatial variability of pigment concentrations, especially during summer. Large interannual variability (>30%) in average pigment concentration over the entire region during different seasons indicates possible influence of time dependent parameters. C1 UNIV MARYLAND,MARINE ESTUARINE ENVIRONM SCI GRAD PROGRAM,COLL PK,MD 20742. UNIV RHODE ISL,GRAD SCH OCEANOG,NARRAGANSETT,RI 02882. UNIV SO CALIF,HANCOCK INST MARINE STUDIES,LOS ANGELES,CA 90089. RP COMISO, JC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,CODE 971,GREENBELT,MD 20771, USA. NR 68 TC 222 Z9 224 U1 3 U2 20 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 FEB 15 PY 1993 VL 98 IS C2 BP 2419 EP 2451 DI 10.1029/92JC02505 PG 33 WC Oceanography SC Oceanography GA KM443 UT WOS:A1993KM44300019 ER PT J AU GLAZMAN, RE GREYSUKH, A AF GLAZMAN, RE GREYSUKH, A TI SATELLITE ALTIMETER MEASUREMENTS OF SURFACE WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SPEED ALGORITHM; DEVELOPED SEA AB Recent analyses of wind speed measurements by the Geosat altimeter showed that the radar cross section is affected by oceanographic factors, particularly by the degree of sea development, which are not directly accounted for in the geophysical model functions (GMF). In the present work, two new GMFs which account for the effects of the actual degree of sea development are proposed. Along with the radar cross section, these models use significant wave height information. One particular version is recommended for applications in oceanographic and climate studies where wind speed (or wind stress) data have to be binned (i.e., averaged over time and/or space intervals). The accuracy of this GMF (overall bias of 0.1 m/s and rms error of about 1.6 m/s) is higher than the accuracy of commonly employed GMFs, while the wave-age-related trend is reduced to a geophysically insignificant level. Finally, the wind speed histograms for the collocated data set are derived and compared with the ground truth data as well as with the histograms yielded by presently known GMFs. It is also shown that the accuracy of altimeter measurements could be increased even further if some additional information on the wave field were available from independent sources (e.g., the dominant wavelength from synthetic aperture radar images). RP GLAZMAN, RE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 32 Z9 39 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 FEB 15 PY 1993 VL 98 IS C2 BP 2475 EP 2483 DI 10.1029/92JC02659 PG 9 WC Oceanography SC Oceanography GA KM443 UT WOS:A1993KM44300022 ER PT J AU ZLOTNICKI, V SIEDLER, G KLEIN, B AF ZLOTNICKI, V SIEDLER, G KLEIN, B TI CAN THE WEAK SURFACE CURRENTS OF THE CAPE VERDE FRONTAL ZONE BE MEASURED WITH ALTIMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TROPOSPHERIC RANGE CORRECTION; TROPICAL ATLANTIC-OCEAN; SATELLITE ALTIMETRY; GEOSAT ALTIMETER; NORTH-ATLANTIC; GULF-STREAM; KUROSHIO EXTENSION; AZORES CURRENT; TRANSPORT; VARIABILITY AB Three data types are compared in the low-current-velocity regime in the southeastern North Atlantic, between 12-degrees-N and 30-degrees-N, 29-degrees-W and 18-degrees-W: Geosat altimetric sea level and derived surface geostrophic velocities, shallow current meter velocities, and dynamic heights derived from hydrographic data from cruises 4, 6, and 9 of the research vessel Meteor. The four current meter daily time series, at depths around 200 m, were smoothed over 1 month; the altimetric geostrophic velocities were computed from sea surface slopes over 142 km every 17 days. The correlation coefficients between the current meter and altimetric geostrophic velocities range between 0.64 and 0.90 for the moorings near 29-degrees-N but between 0.32 and 0.71 for the two around 21-degrees-N; the associated rms discrepancies between the two measurement types range between 1.5 and 4.4 cm/s, which is 49% to 127% of the rms of the respective current meter time series. Dynamic heights relative to 1950 dbar for the months of November 1986 (d(M4)), November 1987 (d(M6)), and February 1989 (d(M9)) were computed from Meteor cruises 4, 6, and 9. Both dynamic heights and altimetric heights (h(M4), h(M6), h(M9)) were averaged over 1-degrees boxes for the duration of each cruise. Differences d(M4) - d(M6) and d(M9) - d(M6) were computed only at bins where at least one station from both cruises existed, Assuming that dynamic heights d in dynamic centimeters are equivalent to sea level h in centimeters, the standard deviation sigma of the differences ((h(M4) - h(M6)) - (d(M4) - d(M6))) and corresponding M9 - M6 values was 2.1 cm. This value (squared) is only 13% of the (5.8 cm)2 variance of the dynamic height differences and is indistinguishable from the 2.7- to 5.6-cm natural variability of sea level in the area expected between the times when the ship and the satellite sampled the ocean. The areally averaged discrepancy for M9 - M6 was only 0.7 cm, but the corresponding value for M4 - M6 was 5.2 cm. A systematic difference between the water vapor corrections used before and after July 1987 is responsible for the M4 - M6 difference. The average M4 - M6 discrepancy is only 0.1 cm using the Fleet Numerical Oceanography Center correction, with a standard deviation of 3.1 cm. In spite of the underlying differences in sampling and physics, including unknown barotropic components not included in our hydrographic dynamic heights, and in data errors, including water vapor, ionospheric, and orbital effects on the altimetry, consistent interannual changes of the mean sea level from the independently obtained altimetric and hydrographic data sets are obtained, and correlated seasonal changes in surface currents are observed with both altimetry and current meters. C1 UNIV KIEL,INST MEERESKUNDE,W-2300 KIEL 1,GERMANY. RP ZLOTNICKI, V (reprint author), JET PROP LAB,M-S 300-323,PASADENA,CA 91109, USA. NR 50 TC 9 Z9 9 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-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 1993 VL 98 IS C2 BP 2485 EP 2493 DI 10.1029/92JC02729 PG 9 WC Oceanography SC Oceanography GA KM443 UT WOS:A1993KM44300023 ER PT J AU RAY, R WHITTENBERGER, JD AF RAY, R WHITTENBERGER, JD TI MICROSTRUCTURES AND COMPRESSION FLOW BEHAVIOR OF A RAPIDLY SOLIDIFIED MOSI2 COMPOSITE CONTAINING HFB2 DISPERSOIDS SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAY, R (reprint author), MARKO MAT INC,POB 3,N BILLERICA,MA 01862, USA. NR 8 TC 0 Z9 0 U1 0 U2 2 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD FEB 15 PY 1993 VL 12 IS 4 BP 260 EP 262 DI 10.1007/BF00539819 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA KN486 UT WOS:A1993KN48600023 ER EF