FN Thomson Reuters Web of Science™ VR 1.0 PT J AU GOLDADER, JD THOLEN, DJ CRUIKSHANK, DP HARTMANN, WK AF GOLDADER, JD THOLEN, DJ CRUIKSHANK, DP HARTMANN, WK TI GALILEO SUPPORT OBSERVATIONS OF ASTEROID 951-GASPRA SO ASTRONOMICAL JOURNAL LA English DT Article AB We report observations of 951 Gaspra in support of the Galileo spacecraft encounter. Photometric observations yield a synodic rotational period of 7.042 46 +/- 0.000 06 hr (0.293 436 +/- 0.000 003 days), a mean absolute visual magnitude of 11.8026 +/- 0.0025, and a slope parameter of 0.285 +/- 0.005. We review another determination of the slope parameter and suggest that the sub-Earth latitude was changing significantly during the opposition, and so neither we nor other investigators were able to sample uniquely the asteroid's phase function during the 1990 opposition. We suggest adopting a slope parameter of 0.25 from combining available observations, and we also place limits on a possible pole orientation. Our infrared reflectance spectrum (0.8-2.5-mu-m) shows an absorption band near 1-mu-m attributed to olivine and pyroxene, and a weak second pyroxene band centered near 2.0-mu-m. This mineral signature plus the overall redness of the spectrum suggest that Gaspra originated in the lower mantle of a differentiated parent body. Astrometric positions obtained during the course of these observations are also reported. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. PLANETARY SCI INST,TUCSON,AZ 85719. RP GOLDADER, JD (reprint author), UNIV HAWAII,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822, USA. NR 21 TC 15 Z9 15 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1991 VL 102 IS 4 BP 1503 EP 1509 DI 10.1086/115976 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GG675 UT WOS:A1991GG67500027 ER PT J AU NERNEY, S SUESS, ST SCHMAHL, EJ AF NERNEY, S SUESS, ST SCHMAHL, EJ TI FLOW DOWNSTREAM OF THE HELIOSPHERIC TERMINAL SHOCK - MAGNETIC-FIELD KINEMATICS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COSMIC RAYS; GALAXY (THE), SOLAR NEIGHBORHOOD; HYDROMAGNETICS; INTERPLANETARY MEDIUM ID SOLAR-WIND; INTERSTELLAR-MEDIUM; APPROXIMATION; HELIOPAUSE AB We have developed a kinematic model of the interplanetary magnetic field in the heliosheath beyond the solar wind terminal shock. The purpose of the calculation is to evaluate the possible importance of MHD effects in that region of space. The need for this evaluation arises because the interplanetary magnetic field is compressed across the terminal shock and further amplified by the decreasing flow speed beyond the shock. This effect is enhanced because the shocked subsonic wind is turned back by the streaming local interstellar medium. Streamlines which approach the stagnation point before turning in the down-stream direction lead to the strongest effects due to the extreme slowing of the solar wind and consequent compression of the embedded magnetic field. The magnetic volume force therefore cannot be neglected on streamlines that approach the heliopause in the upstream direction, where the volume containing them is a large fraction of the overall volume of the heliosheath in the upstream direction. The increase in the magnetic pressure may act to bring the upstream terminal shock significantly closer to the Sun, potentially reconciling a conflict between models and observations. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB ES52, HUNTSVILLE, AL 35812 USA. SAN JUAN COLL, FARMINGTON, NM 87401 USA. NASA, GODDARD SPACE FLIGHT CTR, NRC, GREENBELT, MD 20771 USA. NR 14 TC 28 Z9 28 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 1991 VL 250 IS 2 BP 556 EP 564 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GL424 UT WOS:A1991GL42400031 ER PT J AU YOKOYAMA, J SUTO, Y AF YOKOYAMA, J SUTO, Y TI BARYON ISOCURVATURE SCENARIO IN INFLATIONARY COSMOLOGY - A PARTICLE PHYSICS MODEL AND ITS ASTROPHYSICAL IMPLICATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; EARLY UNIVERSE; ELEMENTARY PARTICLES; GALAXIES FORMATION ID ISOTHERMAL DENSITY PERTURBATIONS; PECULIAR VELOCITY-FIELD; QUANTUM FLUCTUATIONS; UNIVERSE SCENARIO; PHASE-TRANSITION; VIRGO CLUSTER; GALAXY; ANISOTROPY; ORIGIN; NUMBER AB A phenomenological model to produce isocurvature baryon-number fluctuations is proposed in the frame-work of inflationary cosmology. The resulting spectrum of density fluctuation is very different from the conventional Harrison-Zel'dovich shape. The model, with the parameters satisfying several requirements from particle physics and cosmology, provides an appropriate initial condition for the minimal baryon isocurvature scenario of galaxy formation discussed by Peebles. C1 NASA, FERMILAB ASTROPHYS CTR, FERMI NATL ACCELERATOR LAB, BATAVIA, IL 60510 USA. KYOTO UNIV, INST THEORET PHYS, UJI RES CTR, UJI, KYOTO 611, JAPAN. RP YOKOYAMA, J (reprint author), UNIV TOKYO, FAC SCI, DEPT PHYS, BUNKYO KU, TOKYO 113, JAPAN. NR 75 TC 34 Z9 34 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 OCT 1 PY 1991 VL 379 IS 2 BP 427 EP 439 DI 10.1086/170519 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800001 ER PT J AU BIRKINSHAW, M HUGHES, JP ARNAUD, KA AF BIRKINSHAW, M HUGHES, JP ARNAUD, KA TI A MEASUREMENT OF THE VALUE OF THE HUBBLE CONSTANT FROM THE X-RAY-PROPERTIES AND THE SUNYAEV-ZELDOVICH EFFECT OF ABELL-665 SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; GALAXIES CLUSTERING; GALAXIES INTERGALACTIC MEDIUM; GALAXIES X-RAYS ID MICROWAVE BACKGROUND-RADIATION; LUMINOSITY FUNCTION; DISTANCE SCALE; RICH CLUSTERS; GAS CONTENTS; 3 CLUSTERS; HOT PLASMA; GALAXIES; ABELL-2218; EVOLUTION AB A comparison of the X-ray properties and the Sunyaev-Zel'dovich effect for a cluster of galaxies may be used to measure the distance of the cluster, and hence the Hubble constant. We have applied this method to the rich cluster Abell 665 using IPC, HRI, and MPC data from the Einstein Observatory, LAC data from the Ginga satellite, and Sunyaev-Zel'dovich data from the OVRO 40 m telescope. The X-ray and Sunyaev-Zel'dovich effect data are consistent in their description of the cluster gas and may be fitted by a simple isothermal beta-model with beta almost-equal-to 0.66, cluster core radius almost-equal-to 1.6, and gas temperature almost-equal-to 8.2 keV. The relative normalizations of the X-ray and Sunyaev-Zel'dovich effect data then lead to an estimated Hubble constant H0 = 40 +/- 9 km s-1 Mpc-1 if only the random errors are included. When the possible systematic errors (which are most important if they are present in the Sunyaev-Zel'dovich data) are added in quadrature, the range of possible values of the Hubble constants expands to (40 to 50) +/- 12 km s-1 Mpc-1. The most immediate improvements in the error in this estimate for the Hubble constant would be produced by setting better limits on the zero level of the Sunyaev-Zel'dovich effect data (involving extensive observation), and by improved X-ray observations of the cluster, possibly with ROSAT, Astro-D, and AXAF. However, systematic errors associated with the unknown detailed thermal and density structures of the gas (clumping and low-surface brightness structures) provide limits to the accuracy of the method in principle. C1 UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BIRKINSHAW, M (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 55 TC 143 Z9 144 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 OCT 1 PY 1991 VL 379 IS 2 BP 466 EP 481 DI 10.1086/170522 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800004 ER PT J AU MARTINMIRONES, JM DEZOTTI, G BOLDT, EA MARSHALL, FE DANESE, L FRANCESCHINI, A PERSIC, M AF MARTINMIRONES, JM DEZOTTI, G BOLDT, EA MARSHALL, FE DANESE, L FRANCESCHINI, A PERSIC, M TI SMALL-SCALE FLUCTUATIONS AND ANGULAR-CORRELATIONS OF THE X-RAY-BACKGROUND IN THE HEAO-1 A-2 ENERGY-BAND - CONSTRAINTS ON CLUSTERING OF X-RAY SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; GALAXIES CLUSTERING; QUASARS; X-RAYS SOURCES ID ACTIVE GALACTIC NUCLEI; RICH CLUSTERS; GALAXIES; EVOLUTION; UNIVERSE; SPECTRUM; QUASARS AB Using HEAO 1 A-2 all-sky survey data we have determined the amplitude of intensity fluctuations of the extragalactic 2-10 keV X-ray background (XRB) over an effective solid angle of 1.84 deg2 and their angular correlation function on angular scales of less than 3-degrees (i.e., smaller than the detector's field of view). The observed fluctuations are congruent-to 3 sigma above those expected if the counts keep a Euclidean slope well below the limit of the Piccinotti survey, as indicated by the Einstein Observatory medium sensitivity and deep surveys. A good empirical fit to the data is obtained assuming that the integral counts in the A-2 band have a slope of 1.65(-0.07)+0.06, fully consistent with the best-fit slope of 1.72(-0.10)+0.15 obtained by Piccinotti et al. directly from source counts with the same experiment. Alternatively, the data may imply a significant clustering of extragalactic X-ray sources. However, the non-Poisson constribution of rich clusters of galaxies with clustering radii consistent with optical data (r0 less-than-or-equal-to 50-60 Mpc, H0 = 50) do not fully account for the observed signal. Clustering of AGNs could do the job; the required amplitude of the two-point correlation function depends primarily on the evolution of their luminosity and/or space density and of their clustering properties. The resulting values are consistent with optical data on quasar clustering. C1 OSSERV ASTRON PADOVA,I-35122 PADUA,ITALY. DIPARTIMENTO ASTRON,I-35122 PADUA,ITALY. SISSA,I-34014 TRIESTE,ITALY. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771. RP MARTINMIRONES, JM (reprint author), UNIV CANTABRIA,DEPT FIS MODERNA,AVDA LOS CASTROS S-N,E-39005 SANTANDER,SPAIN. NR 53 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1991 VL 379 IS 2 BP 507 EP 516 DI 10.1086/170524 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800006 ER PT J AU BRUHWEILER, FC TRUONG, KQ ALTNER, B AF BRUHWEILER, FC TRUONG, KQ ALTNER, B TI IUE OBSERVATIONS OF NGC-1068 - THE EXTREMELY LUMINOUS STARBURST KNOTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES INDIVIDUAL (NGC-1068); GALAXIES SEYFERT; NEBULAE H II REGIONS; ULTRAVIOLET SPECTRA ID H-II REGIONS; INFRARED-BRIGHT GALAXIES; NGC 1068; STAR FORMATION; MAGELLANIC CLOUDS; SEYFERT-GALAXIES; EXTENDED GAS; ULTRAVIOLET; DISK; WINDS AB We present a complete study of the UV characteristics of the starburst knots in the inner 3 kpc region of NGC 1068 mapped by the International Ultraviolet Explorer (IUE) satellite. These knots likely represent the most luminous H II regions yet studied at optical and ultraviolet wavelengths. Comparisons indicate the brightest UV knot, knot 1, is 30 times brighter than NGC 604 in M33 and has a total luminosity greater-than-or-equal-to 10(43) ergs s-1. Moreover, the total observed flux of the UV knots at 1350 angstrom exceeds that of the nucleus of this nearby Seyfert 2 galaxy. The UV spectra clearly show that the starburst knots have undergone recent intense star formation. The stellar population of the knots is dominated by luminous B0-B1 supergiants with ages less than 10(7) yr. The spectra of the knots, especially those in the direction northeast of the nucleus, exhibit with very strong emission of N V, C IV, He II, and C III]. This emission does not arise from Wolf-Rayet stars as often seen in other star-forming regions. Rather, the spectrum of a very highly ionized extended nebular emission line region is superposed upon that of the UV knots. There is no evidence of excessive extinction by dust in the vicinity of the starburst knots. The interstellar extinction deduced from the UV data for the knots corresponds to an intrinsic E(B-V) = 0.15 assuming an LMC extinction law plus an additional Galactic foreground component of 0.03 mag. This is far less than the values of 0.3-0.6 inferred from data acquired at visual wavelengths. The low reddening deduced from the UV may reflect the preferential destruction of small dust grains in the inner disk of NGC 1068 as a result of supernova shocks and the intense EUV radiation field of both the central active galactic nucleus and the starburst knots. The UV data are compared to the morphologies of the IR disk, the CO ring, and the radio emission to investigate the nature of the star formation activity in the inner disk of this nearby Seyfert 2 galaxy. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. RP BRUHWEILER, FC (reprint author), CATHOLIC UNIV AMER,DEPT PHYS,ASTROPHYS PROGRAM,WASHINGTON,DC 20064, USA. NR 63 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 OCT 1 PY 1991 VL 379 IS 2 BP 596 EP & DI 10.1086/170532 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800014 ER PT J AU KWOK, PW CHENG, KS LAU, MM AF KWOK, PW CHENG, KS LAU, MM TI A MODEL OF UNPULSED VERY-HIGH-ENERGY GAMMA-RAYS FROM THE CRAB-NEBULA AND PULSAR SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS GENERAL; NEBULAE CRAB NEBULA; PULSARS ID RAPIDLY SPINNING PULSARS; RADIATION AB The angular resolution of gamma-ray detectors does not allow one to separate the nebula from the pulsar in the Crab. It is generally assumed that the steady emission of gamma rays comes from the nebula. Using the "outer magnetospheric gap" model, we propose an alternative mechanism in which the steady emission of gamma rays could come from a compact region, a couple of light cylinder radii beyond the pulsar. In that region, the magnetic field has been transformed from a dipole field to a swirling field. In the model, two mono-energetic beams of gap primary e+(e-) if OMEGA . B(s) > 0 (< 0) with a Lorentz factor approximately 4 x 10(7) are streaming out from the outer gaps through the light cylinder. The gap primary e+(e-) beam from the first outer gap can produce approximately 10 TeV primary very high energy (VHE) gamma rays through inverse Compton scattering with the IR photons from the second gap, and vice versa. The primary VHE gamma rays are sufficiently energetic to produce secondary e+/- pairs by collision with the same pulsed IR photons. Since the mean free path of these conversion processes is comparable to the local radius of curvature, the pitch angles of the secondary pairs are large enough to result in isotropic secondary VHE gamma rays with E-gamma approximately TeV. Comparisons between the model spectra and the observed data are discussed in the text. C1 CITY POLYTECH HONG KONG,DEPT APPL SCI,HONG KONG,HONG KONG. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV HONG KONG,DEPT PHYS,HONG KONG,HONG KONG. RP KWOK, PW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 662,GREENBELT,MD 20771, USA. RI Cheng, Kwong Sang/D-3073-2009 NR 25 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1991 VL 379 IS 2 BP 653 EP 658 DI 10.1086/170538 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800020 ER PT J AU FUSELIER, SA SHELLEY, EG GOLDSTEIN, BE GOLDSTEIN, R NEUGEBAUER, M IP, WH BALSIGER, H REME, H AF FUSELIER, SA SHELLEY, EG GOLDSTEIN, BE GOLDSTEIN, R NEUGEBAUER, M IP, WH BALSIGER, H REME, H TI OBSERVATIONS OF SOLAR-WIND ION CHARGE-EXCHANGE IN THE COMET HALLEY COMA SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS; MOLECULAR PROCESSES; SUN SOLAR WIND ID P/HALLEY; COMETOPAUSE; DYNAMICS; GIOTTO AB Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of comet Halley. As the comet was approached, the He2+ to proton density ratio increased from 2.5% in the solar wind to approximately 4% about 1 hr before closest approach after which time it decreased to approximately 1%. Abrupt increases in this ratio from 2.5% to 4.5% were also observed in the beginning and near the end of the so-called Mystery Region (8.6-5.5 x 10(5) km from the comet along the spacecraft trajectory). These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He2+ to proton density ratio is quantitatively consistent with a combination of the addition of protons of Cometary origin to the plasma and loss of plasma through charge exchange of protons and He2+. In agreement with the solar wind proton and He2+ observations, solar wind oxygen and carbon ions were observed to charge exchange from higher to lower charge states with decreasing distance to the comet. The more abrupt increases in the He2+ to proton and the He2+ to O6+ density ratios in the mystery region require a change in the solar wind ion composition in this region, while the correlation with energetic electrons and properties of the exit from this region indicate processes associated with the comet. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. CTR ETUD SPATIALE RAYONNEMENTS,F-31400 TOULOUSE,FRANCE. RP FUSELIER, SA (reprint author), LOCKHEED PALO ALTO RES LABS,DEPT 91-20,BLDG 255,3251 HANOVER ST,PALO ALTO,CA 94304, USA. NR 21 TC 28 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1991 VL 379 IS 2 BP 734 EP 740 DI 10.1086/170549 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800031 ER PT J AU CLIVER, EW CANE, HV FORREST, DJ KOOMEN, MJ HOWARD, RA WRIGHT, CS AF CLIVER, EW CANE, HV FORREST, DJ KOOMEN, MJ HOWARD, RA WRIGHT, CS TI SOLAR GAMMA-RAY-LINE FLARES, TYPE-II RADIO-BURSTS, AND CORONAL MASS EJECTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS; GENERAL; SHOCK WAVES; SUN FLARES; SUN PARTICLE EMISSION; SUN RADIO RADIATION ID ENERGETIC PARTICLE EVENTS; PROTON EVENTS; ACCELERATION; ASSOCIATIONS; ELECTRONS; EMISSION; PHASE; SUN AB We use a Big Flare Syndrome (BFS) test to substantiate earlier reports of a statistically significant association between nuclear gamma-ray-line (GRL) flares (observed by the Gamma Ray Spectrometer on the Solar Maximum Mission) and metric type II bursts from coronal shocks. The type II onset characteristically follows the onset of gamma-ray emission with a median delay of 2 minutes. We find that 70%-90% of GRL flares for which coronagraph data were available were associated with coronal mass ejections (CMEs). Gradual and impulsive GRL flares were equally well associated with CMEs. The CMEs were typically fast, with a median speed greater than 800 km s-1. We discuss the following possible "non-BFS" explanations for the GRL-type II association: (1) the "type II shock" accelerates GRL protons in a "second step" process as it traverses lowlying coronal loops, (2) the observed shocks are blast waves resulting from the sudden deposition of energy in the low corona signaled by the GRL event, and (3) a fast CME is the underlying independent cause of both GRL and type II emission from GRL flares. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. USN,RES LAB,EO HULBERT CTR SPACE RES,WASHINGTON,DC 20375. AUSTRALIAN DEF SCI & TECHNOL ORG,ELECTR RES LAB,SALISBURY,SA 5108,AUSTRALIA. SFA INC,LANDOVER,MD 20785. RP CLIVER, EW (reprint author), PHILLIPS LAB,OL AA,PHG,BEDFORD,MA 01731, USA. NR 56 TC 3 Z9 3 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1991 VL 379 IS 2 BP 741 EP 750 DI 10.1086/170550 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH078 UT WOS:A1991GH07800032 ER PT J AU BRAINERD, JJ AF BRAINERD, JJ TI THE INABILITY OF THE RESONANT COMPTON UPSCATTERING MODEL OF GAMMA-RAY BURSTS TO PRODUCE A 3RD CYCLOTRON HARMONIC SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS; BURSTS LINE FORMATION STARS; NEUTRON ID STRONG MAGNETIC-FIELDS; SCATTERING; ABSORPTION; SPECTRA; FEATURES; LINES AB The resonant Compton upscattering model for gamma-ray bursts cannot produce a third cyclotron harmonic under plausible physical conditions. If one observes a third harmonic in a burst spectrum, resonant Compton upscattering cannot be responsible for the burst emission. The second harmonic may be produced by this model for sufficiently large optical depths. RP BRAINERD, JJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 11 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 OCT 1 PY 1991 VL 379 IS 2 BP L57 EP L59 DI 10.1086/186153 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH081 UT WOS:A1991GH08100004 ER PT J AU CHIN, CW STOTHERS, RB AF CHIN, CW STOTHERS, RB TI EVOLUTIONARY SEQUENCES OF STELLAR MODELS OF INTERMEDIATE AND HIGH MASS INCLUDING CONVECTIVE CORE OVERSHOOTING SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE STARS, EVOLUTION; STARS, INTERIORS; STARS, MASSIVE ID 30-M. STARS; TABLES; NUCLEOSYNTHESIS; CEPHEIDS; DIAGRAM; LOOPS; PHASE; TESTS; GRIDS; HRD AB Stellar evolution with parameterized overshooting from the convective core has been studied for the stellar mass range M/M. = 3-30 and for the initial chemical composition range X(e) = 0.650-0.739 (hydrogen) and Z(e) = 0.021-0.044 (metals). Evolutionary sequences run from the zero-age main sequence to the end of core helium burning, but emphasis is placed here on the core helium-burning phase. Convective core overshooting during the previous main-sequence phase leads, in most cases, to a shortening of the blue loop on the H-R diagram that forms when helium is being depleted in the core. On the other hand, convective overshooting from the helium-burning core has the opposite effect. A larger initial metals abundance also tends to shorten the blue loop. In an extreme case the blue loop can be fully suppressed, but in a marginal case the normal trend can be reversed. The fraction of the core helium-burning lifetime that is spent in the blue phase is generally very sensitive to the physical input parameters. Detailed tables and plots of evolutionary tracks on the H-R diagram are provided. RP CHIN, CW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 49 TC 27 Z9 28 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD OCT PY 1991 VL 77 IS 2 BP 299 EP 316 DI 10.1086/191605 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH386 UT WOS:A1991GH38600004 ER PT J AU HARGENS, AR WHALEN, RT WATENPAUGH, DE SCHWANDT, DF KROCK, LP AF HARGENS, AR WHALEN, RT WATENPAUGH, DE SCHWANDT, DF KROCK, LP TI LOWER-BODY NEGATIVE-PRESSURE TO PROVIDE LOAD BEARING IN SPACE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID EXERCISE AB Presently, exercise protocols and equipment for spaceflight are unresolved, although recent calculations suggest that all exercise in space to date has lacked sufficient loads to maintain preflight musculoskeletal mass. We hypothesized that lower body negative pressure (LBNP) produces a footward force equal to the product of the pressure differential and body cross-sectional area at the waist seal. Twelve male volunteers weighing 67.6-86.9 kg were sealed at the superior iliac crest in upright and supine LBNP chambers. Neither configuration included a saddle, so that the force due to LBNP was transmitted to the feet of our subjects. Each subject was exposed to 10 mm Hg increments of LBNP up to 70 mm Hg (standing) or to 50-100 mm Hg (supine), depending upon individual tolerance. Static reaction force was measured at each LBNP level for approximately 1-2 min. An additional static force approximately equivalent to 1% Earth body weight was generated against the feet by each mm Hg of LBNP either during upright standing or supine posture. Furthermore, the forces measured during LBNP agreed well with forces calculated from the cross-sectional areas of our subjects' waists. These results indicate that exercise in microgravity against 100 mm Hg LBNP could produce static and inertial forces similar in magnitude to those occurring on Earth. This gravity-independent technique may help maintain the musculoskeletal and cardiovascular systems of crewmembers during prolonged exposure to microgravity. C1 USAF,SCH AEROSP MED,DIV CREW TECHNOL,BROOKS AFB,TX 78235. RP HARGENS, AR (reprint author), NASA,AMES RES CTR,DIV LIFE SCI 23911,MOFFETT FIELD,CA 94035, USA. NR 18 TC 34 Z9 34 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 OCT PY 1991 VL 62 IS 10 BP 934 EP 937 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA GG489 UT WOS:A1991GG48900003 PM 1764003 ER PT J AU SEVERS, WB MORROW, BA KEIL, LC AF SEVERS, WB MORROW, BA KEIL, LC TI CEREBROSPINAL-FLUID PRESSURE IN CONSCIOUS HEAD-DOWN TILTED RATS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SUSPENSION AB Cerebrospinal fluid pressure (PCSF) was continuously measured in conscious male Sprague-Dawley rats gently restrained by a cotton towel. PCSF, evaluated in 15-min time blocks over a 3-h experiment, increased slightly (p < 0.05) during the first 30 min of a control hour at 0-degrees. There was a transient increase for about 5 min immediately after tilt (-45-degrees) that may have been due to head movement after the position change. However, PCSF was statistically unchanged (p < 0.05) during the 2nd (-45-degrees) hour and the 3rd (0-degrees) recovery hour. The data show that the dynamics of intracranial pressure regulation can accommodate the acute cephalad fluid shift after tilting. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SEVERS, WB (reprint author), PENN STATE UNIV,MILTON S HERSHEY MED CTR,COLL MED,DEPT PHARMACOL,HERSHEY,PA 17033, USA. NR 11 TC 16 Z9 16 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 OCT PY 1991 VL 62 IS 10 BP 944 EP 946 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA GG489 UT WOS:A1991GG48900005 PM 1764005 ER PT J AU MEDNIEKS, MI POPOVA, IA GRINDELAND, RE AF MEDNIEKS, MI POPOVA, IA GRINDELAND, RE TI CYCLIC AMP-RECEPTOR PROTEINS IN HEART-MUSCLE OF RATS FLOWN ON COSMOS 1887 SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID BETA-ADRENERGIC-RECEPTOR; PAROTID ACINAR-CELLS; REGULATORY SUBUNIT; KINASE; PHOSPHORYLATION; DESENSITIZATION; ULTRASTRUCTURE; LOCALIZATION; MYOCARDIUM; MECHANISMS AB A frequent cellular response to organismal stress is the increase in ligand binding by beta-adrenergic receptors. The extracellular signal is amplified by intracellular increases in cyclic AMP and the ensuing activation of cyclic AMP-dependent protein kinase (cAPK). The molecular mechanisms involve the binding of cyclic AMP to regulatory (R) subunits of cAPK, thus freeing the catalytic subunit for protein phosphorylation. This study was carried out to determine the cellular compartmentalization of the cyclic AMP-receptor proteins in heart ventricular tissue obtained from rats flown on the Cosmos 1887 mission. Photoaffinity labeling of soluble and particulate cell fractions with an [P-32]-8-azido analog of cyclic AMP was followed by electrophoretic separation of the proteins and by autoradiographic identification of the labeled isoforms of cAPK R subunits. The results showed that RII in the particulate subcellular fraction was significantly decreased in heart cells from rats in the flight group when compared to controls. Protein banding patterns in both the cytoplasmic fraction and in a fraction enriched in chromatin-bound proteins showed some variability in tissues of individual animals, but exhibited no changes that could be directly attributed to flight conditions. No significant change was apparent in the distribution of RI or RII cyclic AMP binding in the soluble fractions. These findings indicate that the cardiac cell integrity or its protein content is not compromised under flight conditions. There is, however, what appears to be an adaptive molecular response which can be detected using microanalytical methods, indicating that a major hormone regulated mechanism may be affected during some phase of travel in space. C1 MINIST PUBL HLTH USSR,INST BIOMED PROBLEMS,MOSCOW,USSR. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MEDNIEKS, MI (reprint author), UNIV CHICAGO,PRITZKER SCH MED,DEPT PEDIAT,5841 S MARYLAND AVE,CHICAGO,IL 60637, USA. FU NICHD NIH HHS [HD-HD06308] NR 31 TC 3 Z9 3 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 OCT PY 1991 VL 62 IS 10 BP 947 EP 952 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA GG489 UT WOS:A1991GG48900006 PM 1662483 ER PT J AU SANTY, PA HOLLAND, AW FAULK, DM AF SANTY, PA HOLLAND, AW FAULK, DM TI PSYCHIATRIC DIAGNOSES IN A GROUP OF ASTRONAUT APPLICANTS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SPACE AB Between 1959 and 1987, the psychiatric evaluation of astronaut candidates evolved from a 30-h intensive examination evaluating applicants for psychopathology, and studying their performance under stress, to a 2-h clinical interview whose structure and contents were determined by the individual examiner. Evaluations done during these years applied both psychiatric (or, "select-out") criteria and psychological (or, "selectiin") criteria. In an attempt to more rigorously define the psychiatric, "select-out" component, a standardized, semi-structured clinical interview was developed to identify the presence or history of psychiatric disorders listed in the Diagnostic and Statistical Manual of Mental Disorders, 3rd Ed. ("DSM-III"). A total of 117 astronaut applicants underwent this clinical interview as part of a comprehensive medical evaluation during a recent astronaut selection. Of the 117 applicants, 9 (7.7%) met DSM-III criteria for a variety of Axis I and Axis II diagnoses, including V-code diagnoses. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOBEHAV LAB,HOUSTON,TX 77058. RP SANTY, PA (reprint author), UNIV TEXAS,MED BRANCH,DEPT PSYCHIAT & BEHAV SCI,GALVESTON,TX 77550, USA. NR 14 TC 6 Z9 6 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 OCT PY 1991 VL 62 IS 10 BP 969 EP 973 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA GG489 UT WOS:A1991GG48900010 PM 1764009 ER PT J AU BIGFORD, TE AF BIGFORD, TE TI SEA-LEVEL RISE, NEARSHORE FISHERIES, AND THE FISHING INDUSTRY SO COASTAL MANAGEMENT LA English DT Article DE FISHERIES; COASTAL MANAGEMENT; FISHERY MANAGEMENT; SEA-LEVEL CHANGE; HABITAT; COASTAL DEVELOPMENT AB Global meteorological conditions may be changing, and sea levels over the next centuries could rise at rates usually measured over millennia. As a result, fish habitats, fishery yields, and the industry's shoreside infrastructure could change dramatically. This article (1) summarizes predicted sea-level changes; (2) forecasts possible short- and long-term effects on fish habitats, valued estuarine and coastal species, and fishing industry sectors; and (3) recommends specific actions to maintain a viable fishing industry. Lacking applicable research results, most effects are extrapolated from professional opinions and related research on other coastal industries or features. Emphasis is on the United States' Atlantic Coast. Predicted impacts should change over time. Some short-term changes could be beneficial as new habitats are created for estuarine species, but the long-term implications on most sectors, especially shoreside industries, are more negative than positive. Potential impacts should inspire harvesting and processing sectors to participate in remedial planning, where assistance is available from coastal managers. Recommendations address deficiencies in natural resource management strategies, development policies, short- and long-term waterfront plans, decision-making protocols for actions such as wetland permits, and priorities for remedial action. RP BIGFORD, TE (reprint author), NOAA,NATL MARINE FISHERIES SERV,1 BLACKBURN DR,GLOUCESTER,MA 01930, USA. NR 0 TC 6 Z9 6 U1 1 U2 4 PU TAYLOR & FRANCIS PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 0892-0753 J9 COAST MANAGE JI Coast. Manage. PD OCT-DEC PY 1991 VL 19 IS 4 BP 417 EP 437 DI 10.1080/08920759109362152 PG 21 WC Environmental Sciences; Environmental Studies SC Environmental Sciences & Ecology GA GR504 UT WOS:A1991GR50400002 ER PT J AU CUSHING, S AF CUSHING, S TI MINDS AND MACHINES FOR HUMANITIES MAJORS - A LIBERAL-ARTS COURSE IN COMPUTERS AND COGNITION SO COMPUTERS AND THE HUMANITIES LA English DT Article; Proceedings Paper CT 2ND CONF ON TEACHING COMPUTERS AND HUMANITIES COURSES CY JUN, 1988 CL OBERLIN COLL, OBERLIN, OH HO OBERLIN COLL DE COGNITION; PHILOSOPHY; KNOWLEDGE; LANGUAGE; HUMAN NATURE; TEACHING; COMPUTERS AND HUMANISTS AB A new one-semester course is described in which undergraduate students in non-technical majors are shown how traditional philosophical problems of knowledge, cognition, language, and human nature can be fruitfully investigated with computer-related concepts and techniques. A series of simple experiments is used to demonstrate to undergraduates that mental phenomena are real, that they can be studied experimentally, and that they can be modeled insightfully in computational - i.e., information-processing - terms. Each experiment illustrates a basic fact or principle of cognitive science: the formal character of algorithms; creativity and the variants of the Turing test; limitations on human memories; the use of cognitive strategies; heuristic techniques of artificial intelligence; formal grammars and their associated parsers; social, societal, and anthropological dimensions of mind; and degrees of logicality in human reasoning. Students are also taught the essentials of PROLOG, a programming language that is based explicitly on formal logic, incorporating such notions as fact, database, and query, thereby lending itself readily to the description of complex relational networks of a sort not commonly expected to be amenable to computer analysis. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CUSHING, S (reprint author), BOSTON UNIV,COMP SCI,BOSTON,MA 02215, USA. NR 26 TC 0 Z9 0 U1 3 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0010-4817 J9 COMPUT HUMANITIES JI Comput. Humanit. PD OCT PY 1991 VL 25 IS 5 BP 275 EP 280 DI 10.1007/BF00120963 PG 6 WC Computer Science, Interdisciplinary Applications SC Computer Science GA HB682 UT WOS:A1991HB68200003 ER PT J AU BILLICA, RD DOARN, CR AF BILLICA, RD DOARN, CR TI A HEALTH MAINTENANCE FACILITY FOR SPACE STATION FREEDOM SO CUTIS LA English DT Article AB We describe a health care facility to be built and used on an orbiting space station in low Earth orbit. This facility, called the health maintenance facility, is based on and modeled after isolated terrestrial medical facilities. It will provide a phased approach to health care for the crews of Space Station Freedom. This paper presents the capabilities of the health maintenance facility. As Freedom is constructed over the next decade there will be an increase in activities, both construction and scientific. The health maintenance facility will evolve with this process until it is a mature, complete, stand-alone health care facility that establishes a foundation to support interplanetary travel. As our experience in space continues to grow so will the commitment to providing health care. C1 NASA,LYNDON B JOHNSON SPACE CTR,MED OPERAT BRANCH SD2,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,KRUG LIFE SCI,HLTH MAINTENANCE FACIL PROJECT,HOUSTON,TX 77058. NR 3 TC 9 Z9 9 U1 0 U2 0 PU EXCERPTA MEDICA INC PI NEW YORK PA 245 WEST 17TH STREET, NEW YORK, NY 10011 SN 0011-4162 J9 CUTIS JI Cutis PD OCT PY 1991 VL 48 IS 4 BP 315 EP 318 PG 4 WC Dermatology SC Dermatology GA GK903 UT WOS:A1991GK90300010 PM 1743067 ER PT J AU ZDANOWICZ, VS AF ZDANOWICZ, VS TI DETERMINING THE FATES OF CONTAMINATED WASTES DUMPED IN THE NEW-YORK BIGHT APEX BY USE OF METAL ENRICHMENT FACTORS SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID SOUTHERN-CALIFORNIA; RIVER ESTUARY; HEAVY-METALS; SANTA-MONICA; SEDIMENTS; POLLUTION; HISTORY AB The major sources of contaminants to the New York Bight apex in 1983 were sewage sludge and dredged spoils dumping and the outflow of the Hudson-Raritan estuary. Metal distributions were determined in sediments collected during a 1983 survey and metal enrichment factors, based on ratios of trace metals to iron, were used to distinguish fates of sewage sludge and dredged spoils dumped in the Bight apex. Lead enrichment factors indicated that the portion of the apex that was directly affected by dredged spoils dumping was in the immediate vicinity of that site, even though this activity constituted the largest source of solid materials to the apex. Sewage sludge dumping, in contrast, while contributing much less total mass than dredged spoils dumping, appeared to directly affect approximately 8 times as much area. RP ZDANOWICZ, VS (reprint author), NOAA,NATL MARINE FISHERIES SERV,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 40 TC 9 Z9 9 U1 0 U2 4 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 OCT PY 1991 VL 25 IS 10 BP 1760 EP 1766 DI 10.1021/es00022a013 PG 7 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GH491 UT WOS:A1991GH49100017 ER PT J AU CRENSHAW, AG FRIDEN, J THORNELL, LE HARGENS, AR AF CRENSHAW, AG FRIDEN, J THORNELL, LE HARGENS, AR TI EXTREME ENDURANCE TRAINING - EVIDENCE OF CAPILLARY AND MITOCHONDRIA COMPARTMENTALIZATION IN HUMAN SKELETAL-MUSCLE SO EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY LA English DT Article DE SUBSARCOLEMMAL MITOCHONDRIA; ULTRAMARATHON; INTERFASCICULAR SPACE; PERIPHERAL FIBERS; CENTRAL FIBERS ID 36 HUMAN MUSCLES; FIBER COMPOSITION; ENZYME-ACTIVITIES; DISTANCE RUNNERS; UNTRAINED MEN; ADAPTATION; DENSITY; AUTOPSY AB Biopsies from the medial gastrocnemius muscle of three experienced endurance runners who had completed an ultramarathon run (160 km) the previous day were assessed for their oxidative characteristics (fibre types, capillarization and mitochondria content). Also, a regional comparison was made for fibres located centrally (completely surrounded by other fibres) versus fibres located peripherally (next to the interfascicular space) and the capillarization of these peripheral fibres was determined. Subsarcolemmal mitochondria were abundant and 'compartmentalized' close to the capillaries. The number of capillaries around fibres ranged from 5.8 to 8.5 and 5.7 to 8.5, and the number of capillaries.mm-2 ranged from 665 to 810 and 727 to 762, for type I (slow twitch) and type II (fast twitch) fibres, respectively. Central fibres contained a greater number of capillaries and more capillaries.mm-2 than their peripheral counterparts. Peripheral fibres contained more capillaries.mu-m-1 between fibres than at the interfascicular space. Type I fibres were more distributed (63%-78%) and larger than type II fibres. An abundance of subsarcolemmal mitochondria located close to the capillaries, efficient capillary proliferation between fibres where sharing can occur and greater relative distribution and size of type I fibres are, collectively, efficient characteristics of extreme endurance training. C1 UMEA UNIV,DEPT HAND SURG,S-90187 UMEA,SWEDEN. UNIV CALIF,SAN DIEGO,CA 92161. VET ADM MED CTR,DIV ORTHOPAED & REHABIL V-151,SAN DIEGO,CA 92161. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CRENSHAW, AG (reprint author), UMEA UNIV,DEPT ANAT,S-90187 UMEA,SWEDEN. FU NIADDK NIH HHS [AM-25501] NR 33 TC 7 Z9 7 U1 0 U2 5 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0301-5548 J9 EUR J APPL PHYSIOL O JI Eur. J. Appl. Physiol. Occup. Physiol. PD OCT PY 1991 VL 63 IS 3-4 BP 173 EP 178 DI 10.1007/BF00233843 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA GM413 UT WOS:A1991GM41300003 PM 1836991 ER PT J AU BOGGS, CH AF BOGGS, CH TI BIOENERGETICS AND GROWTH OF NORTHERN ANCHOVY ENGRAULIS-MORDAX SO FISHERY BULLETIN LA English DT Article ID FILTER-FEEDING PLANKTIVORE; BREVOORTIA-TYRANNUS PISCES; ATLANTIC MENHADEN; ENERGY; ENERGETICS; CONSUMPTION; CLUPEIDAE; RATION; SIZE; FISH AB Changes in total body energy content of adult (total length approximately 9 cm, wet mass approximately 9 g) northern anchovy Engraulis mordax were estimated by sampling captive groups swimming at 8.7 and 21.1 cm/s for 12 hours daily. Anchovy were fed euphausiids at rations of 5 and 3.4% of fish wet mass per day (approximately 54 and 37 cal . g fish wet mass-1 . day-1, respectively). Gross energy conversion efficiency increased with ration levels and declined with swimming speed, ranging from 39% to 1%. Dry mass and lipid losses were estimated in fasting fish swimming at the same speeds. Energy losses were 17.6 and 28.2 cal . g fish wet mass-1 . day-1 at the slow and fast speeds, respectively. The proportion of food energy used for growth and maintenance metabolism was about 65%. A model derived for adult anchovy metabolism was consistent with observed growth and reproduction rates, and the few measurements of ration and swimming speed in nature. RP BOGGS, CH (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 32 TC 9 Z9 9 U1 1 U2 3 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 OCT PY 1991 VL 89 IS 4 BP 555 EP 566 PG 12 WC Fisheries SC Fisheries GA GU460 UT WOS:A1991GU46000002 ER PT J AU CAILLOUET, CW DURONSLET, MJ LANDRY, AM REVERA, DB SHAVER, DJ STANLEY, KM HEINLY, RW STABENAU, EK AF CAILLOUET, CW DURONSLET, MJ LANDRY, AM REVERA, DB SHAVER, DJ STANLEY, KM HEINLY, RW STABENAU, EK TI SEA-TURTLE STRANDINGS AND SHRIMP FISHING EFFORT IN THE NORTHWESTERN GULF OF MEXICO, 1986-89 SO FISHERY BULLETIN LA English DT Note ID LEPIDOCHELYS-KEMPI; CARETTA-CARETTA; UNITED-STATES; LOGGERHEAD; RIDLEY C1 TEXAS A&M UNIV SYST,DEPT MARINE BIOL,GALVESTON,TX 77553. US DEPT INTERIOR,NATL PK SERV,PADRE ISLAND NATL SEASHORE,CORPUS CHRISTI,TX 78418. RP CAILLOUET, CW (reprint author), NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,GALVESTON LAB,GALVESTON,TX 77551, USA. NR 30 TC 22 Z9 23 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 OCT PY 1991 VL 89 IS 4 BP 712 EP 718 PG 7 WC Fisheries SC Fisheries GA GU460 UT WOS:A1991GU46000016 ER PT J AU BOSQUED, JM BERTHELIER, A BERTHELIER, JJ ESCOUBET, CP AF BOSQUED, JM BERTHELIER, A BERTHELIER, JJ ESCOUBET, CP TI A CASE-STUDY OF THE CUSP ELECTRODYNAMICS BY THE AUREOL-3 SATELLITE - EVIDENCE FOR FTE SIGNATURES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLUX-TRANSFER EVENTS; LOW-ALTITUDE SIGNATURES; DAYSIDE MAGNETOPAUSE; RECONNECTION; PATCHY AB Particle and field data from a pass of the AUREOL-3 satellite through the polar cusp, several minutes after the southward turning of the IMF, are analyzed in detail. Superposed on the classical cusp, characterized by the typical ion and electron precipitations, several very narrow arcs are detected where large fluxes of electrons and ions, accelerated to 2-4 keV, precipitate simultaneously. These localized arcs correspond to the upward current sheets of a succession in latitude of narrow, alternatively upward and downward field-aligned current sheets. The data suggest that the satellite has crossed the ionospheric footprints of 2 adjacent flux transfer events separated by 100 - 150 km in latitude. Electric spikes and electromagnetic turbulence are typically associated with the region of downward currents. C1 CTR RECH PHYS ENVIRONN,CNRS,F-94107 ST MAUR FOSSES,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BOSQUED, JM (reprint author), UNIV PAUL SABATIER,CTR ETUD SPATIALE RAYONNEMENTS,CNRS,BP 4346,F-31029 TOULOUSE,FRANCE. 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 OCT PY 1991 VL 18 IS 10 BP 1833 EP 1836 DI 10.1029/91GL02087 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GK002 UT WOS:A1991GK00200010 ER PT J AU BROWN, DG WILSON, GR HORWITZ, JL GALLAGHER, DL AF BROWN, DG WILSON, GR HORWITZ, JL GALLAGHER, DL TI SELF-CONSISTENT PRODUCTION OF ION CONICS ON RETURN CURRENT REGION AURORAL FIELD LINES - A TIME-DEPENDENT, SEMI-KINETIC MODEL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CYCLOTRON RESONANCE; ACCELERATION AB We describe initial results from a time-dependent, semi-kinetic model of plasma outflow incorporating wave-particle interactions along current-carrying auroral field lines. Electrostatic waves are generated by the current driven ion cyclotron instability (CDICI), causing perpendicular velocity diffusion of ions plus electron heating via anomalous resistivity when and where the relative drift between electrons and ions exceeds certain critical velocities. Using the local bulk parameters we calculate these critical velocities, and so are able to self-consistently switch on and off the heating of the various particle species. Due to the dependence of these critical velocities on the bulk parameters of the species the heating effects exhibit quite complex spatial and temporal variations. A wide range of ion distribution functions are observed in these simulations, including conics with energies of a few electron volts and 'ring' distributions. The rings are seen to be a natural result of transverse heating and velocity filter effects and do not require coherent acceleration processes. We also observe the formation of a density depletion in hydrogen and enhanced oxygen densities at high altitudes. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP BROWN, DG (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899, USA. NR 15 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT PY 1991 VL 18 IS 10 BP 1841 EP 1844 DI 10.1029/91GL02244 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GK002 UT WOS:A1991GK00200012 ER PT J AU JENSEN, EJ TOON, OB HAMILL, P AF JENSEN, EJ TOON, OB HAMILL, P TI HOMOGENEOUS FREEZING NUCLEATION OF STRATOSPHERIC SOLUTION DROPLETS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NITRIC-ACID AB We have used the classical theory of homogeneous nucleation to calculate the freezing rate of sulfuric acid solution aerosols under stratospheric conditions. The freezing of stratospheric aerosols would be important for the nucleation of nitric acid trihydrate particles in the Arctic and Antarctic stratospheres. In addition, the rate of heterogeneous chemical reactions on stratospheric aerosols may be very sensitive to their state. Our calculations indicate that homogeneous freezing nucleation of pure water ice in the stratospheric solution droplets would occur at temperatures below about 192 K. However, the physical properties of H2SO4 solution at such low temperatures are not well known, and it is possible that sulfuric acid aerosols will freeze out at temperatures ranging from about 180-195 K. We also show that the temperature at which the aerosols freeze is nearly independent of their size. C1 SAN JOSE STATE UNIV,SAN JOSE,CA 95192. RP JENSEN, EJ (reprint author), NASA,MAIL STOP 245-4,MOFFETT FIELD,CA 94035, USA. NR 12 TC 48 Z9 48 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 OCT PY 1991 VL 18 IS 10 BP 1857 EP 1860 DI 10.1029/91GL01848 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GK002 UT WOS:A1991GK00200016 ER PT J AU WESTPHAL, DL TOON, OB AF WESTPHAL, DL TOON, OB TI THE SHORT-TERM TEMPERATURE RESPONSE TO SMOKE FROM OIL FIRES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CLIMATE AB Simulations with a model of atmospheric dynamics, aerosols, and radiative transfer show that both ground cooling and warming are possible after one diurnal cycle beneath smoke plumes of moderate visible absorption optical depths representative of oil smoke downwind of Kuwait. For an elevated smoke plume, the calculated ground temperature changes range from +1 to -6 K, while within the smoke plume temperature increases range from 0 to 8 K. The response of the ground temperature and boundary layer dynamics depends strongly upon the surface characteristics with deserts exhibiting the strongest cooling of all land use types. The variability of meteorology generally precludes the possibility of a persistent smoke plume, or its effects, over any location other than the immediate surroundings of a persistent fire. For the Middle East these results suggest persistent effects only near Kuwait, with short-term coolings of about 5 K over desert regions a few thousand kilometers downwind of Kuwait. RP WESTPHAL, DL (reprint author), NASA,AMES RES CTR,DIV EARTH SYST SCI,ATMOSPHER CHEM & DYNAM BRANCH,MAIL STOP 2455,MOFFETT FIELD,CA 94035, USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT PY 1991 VL 18 IS 10 BP 1873 EP 1876 DI 10.1029/91GL02239 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GK002 UT WOS:A1991GK00200020 ER PT J AU HUI, J HORN, LJ LANE, AL AF HUI, J HORN, LJ LANE, AL TI PARTICLE SIZES OF THE URANUS DELTA-RINGS INNER DIFFUSE COMPANION THROUGH COMPARISON OF RSS AND PPS VOYAGER OCCULTATION DATA SO ICARUS LA English DT Article ID 1982 STELLAR OCCULTATION; URANIAN RINGS; PHOTOPOLARIMETER EXPERIMENT; ATMOSPHERE; SEGREGATION; SIMULATION; SATELLITES; ORBITS; SYSTEM RP HUI, J (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 30 TC 1 Z9 1 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1991 VL 93 IS 2 BP 347 EP 353 DI 10.1016/0019-1035(91)90217-H PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GN343 UT WOS:A1991GN34300012 ER PT J AU COYLE, DB AF COYLE, DB TI DESIGN OF A HIGH-GAIN LASER DIODE-ARRAY PUMPED ND - YAG ALTERNATING PRECESSIVE SLAB AMPLIFIER (APS AMPLIFIER) SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article AB In the design of space-qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. This paper focuses on a novel preamplifier design that requires no external beam-steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium. C1 NASA,GODDARD SPACE FLIGHT CTR,PHOTON BRANCH,CODE 726,GREENBELT,MD 20771. RP COYLE, DB (reprint author), AMERICAN UNIV,DEPT PHYS,WASHINGTON,DC 20016, USA. NR 9 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 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD OCT PY 1991 VL 27 IS 10 BP 2327 EP 2331 DI 10.1109/3.97277 PG 5 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA GM521 UT WOS:A1991GM52100012 ER PT J AU DURDEN, SL KLEIN, JD ZEBKER, HA AF DURDEN, SL KLEIN, JD ZEBKER, HA TI RADAR MEASUREMENT OF L-BAND SIGNAL FLUCTUATIONS CAUSED BY PROPAGATION THROUGH TREES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB Fluctuations are examined of an L-band, horizontally polarized signal that was transmitted from the ground through a coniferous forest canopy to an airborne radar. The azimuth synthetic aperture radar (SAR) impulse response in the presence of the measured magnitude fluctuations shows increased sidelobes over the case with no trees. Statistics of the observed fluctuations are similar to other observations. RP DURDEN, SL (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD OCT PY 1991 VL 39 IS 10 BP 1537 EP 1539 DI 10.1109/8.97388 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GL907 UT WOS:A1991GL90700014 ER PT J AU EDMONDS, LD AF EDMONDS, LD TI THEORETICAL PREDICTION OF THE IMPACT OF AUGER RECOMBINATION ON CHARGE COLLECTION FROM AN ION TRACK SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB The theoretical analysis presented here concludes that Auger recombination can reduce charge collection from very dense ion tracks in silicon devices. It is of marginal importance for tracks produced by 270 MeV krypton, and therefore, it is of major importance for ions exhibiting a significantly larger loss. The analysis shows that recombination loss is profoundly affected by track diffusion. As the track diffuses, the density and recombination rate decrease so fast that the linear density (number of electron-hole pairs per unit length) approaches a nonzero limiting value as t --> infinity. Furthermore, the linear density is very nearly equal to this limiting value in a few picoseconds or less. When Auger recombination accompanies charge transport processes that have much longer time scales, it can be simulated by assigning a reduced linear energy transfer to the ion. RP EDMONDS, LD (reprint author), CALTECH,JET PROP LAB,MS 303-220,PASADENA,CA 91109, USA. NR 5 TC 17 Z9 17 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 1991 VL 38 IS 5 BP 999 EP 1004 DI 10.1109/23.108360 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA GX349 UT WOS:A1991GX34900004 ER PT J AU KOELBEL, C MEHROTRA, P AF KOELBEL, C MEHROTRA, P TI COMPILING GLOBAL NAME-SPACE PARALLEL LOOPS FOR DISTRIBUTED EXECUTION SO IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS LA English DT Article DE COMPILE-TIME ANALYSIS; DISTRIBUTED MEMORY MACHINES; GLOBAL NAME SPACE; PROGRAM TRANSFORMATIONS; RUN-TIME ANALYSIS AB Distributed memory machines do not provide hardware support for a global address space. Thus, programmers are forced to partition the data across the memories of the architecture and use explicit message passing to communicate data between processors. In this paper, we focus on the compiler support required to allow programmers to express their algorithms using a global name-space. We present a general method for analysis of a high-level source program and its translation to a set of independently executing tasks communicating via messages. If the compiler has enough information, this translation can be carried out at compile-time. Otherwise, run-time code is generated to implement the required data movement. We describe the analyis required in both situations and present the performance of the generated code on the Intel iPSC/2. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP KOELBEL, C (reprint author), RICE UNIV,CTR RES PARALLEL COMPUTAT,HOUSTON,TX 77251, USA. NR 32 TC 68 Z9 69 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 1045-9219 J9 IEEE T PARALL DISTR JI IEEE Trans. Parallel Distrib. Syst. PD OCT PY 1991 VL 2 IS 4 BP 440 EP 451 DI 10.1109/71.97901 PG 12 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GK698 UT WOS:A1991GK69800006 ER PT J AU LEE, S HAHN, H AF LEE, S HAHN, H TI AN OPTIMAL SENSING STRATEGY FOR RECOGNITION AND LOCALIZATION OF 3-D NATURAL QUADRIC OBJECTS SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE ACTIVE SENSING; MEASURE OF DISCRIMINATION POWER; NATURAL QUADRIC OBJECTS; OBJECT LOCALIZATION; OBJECT RECOGNITION; OBJECT REPRESENTATION; PROBING ID RANGE AB Active sensing aims at achieving a goal-directed collection of data critical for sensing goals by controlling sensor configurations and poses. Active sensing thus requires an optimal sensing strategy for controlling sensor configurations and poses in such a way as to minimize data collection operations necessary for achieving sensing goals. This paper presents an optimal sensing strategy of an optical proximity sensor system engaged in the recognition and localization of 3-D natural quadric objects. The optimal sensing strategy consists of the selection of an optimal beam orientation and the determination of an optimal probing plane that compose an optimal data collection operation known as an optimal probing. The decision of an optimal probing is based on the measure of discrimination power for a cluster of surfaces on a multiple interpretation image (MII), where the measure of discrimination power is defined in terms of a utility function computing the expected number of interpretations that can be pruned out by a probing. This paper also presents an object representation suitable for active sensing based on a surface description vector (SDV) distribution graph and hierarchical tables. Experimental results are shown. C1 UNIV SO CALIF,DEPT ELECT ENGN SYST,LOS ANGELES,CA 90089. RP LEE, S (reprint author), CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 27 TC 2 Z9 2 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0162-8828 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD OCT PY 1991 VL 13 IS 10 BP 1018 EP 1037 DI 10.1109/34.99236 PG 20 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GM763 UT WOS:A1991GM76300005 ER PT J AU LI, ZF TARN, TJ BEJCZY, AK AF LI, ZF TARN, TJ BEJCZY, AK TI DYNAMIC WORKSPACE ANALYSIS OF MULTIPLE COOPERATING ROBOT ARMS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB One of the advantages of using two or more robot arms to perform the same task is the increased load carrying, handling, and manipulation capability. In order to make full use of this increased capability it is necessary to know the maximum force/torque that the robots can jointly generate at each point within their common workspace. This is the main subject of dynamic workspace analysis. Furthermore, when multiple robot arms are in rigid contact with an object and applying forces/torques to the environment through it, an internal force/torque is produced that, in many cases, needs to be bounded in magnitude. Conceptually simple procedures are presented in this paper to solve the dynamic workspace analysis problem for multiple cooperating robot arms with or without the internal force/torque constraint. These procedures model the cooperating robot arms as a closed mechanical chain and are based on the theory of linear transformations and the properties of mechanics. C1 WASHINGTON UNIV,DEPT SYST SCI & MATH,ST LOUIS,MO 63130. WASHINGTON UNIV,CTR ROBOT & AUTOMAT,ST LOUIS,MO 63130. CALTECH,JET PROP LAB,TELEROBOT RES PROGRAM,PASADENA,CA 91109. RP LI, ZF (reprint author), WASHINGTON UNIV,SCH MED,MALLINCKRODT INST RADIOL,PHYS SECT,ST LOUIS,MO 63130, USA. NR 13 TC 17 Z9 17 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1991 VL 7 IS 5 BP 589 EP 596 DI 10.1109/70.97870 PG 8 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA GH852 UT WOS:A1991GH85200003 ER PT J AU DEMELLO, LSH SANDERSON, AC AF DEMELLO, LSH SANDERSON, AC TI 2 CRITERIA FOR THE SELECTION OF ASSEMBLY PLANS - MAXIMIZING THE FLEXIBILITY OF SEQUENCING THE ASSEMBLY TASKS AND MINIMIZING THE ASSEMBLY TIME THROUGH PARALLEL EXECUTION OF ASSEMBLY TASKS SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB This paper introduces two criteria for the evaluation and selection of assembly plans. The first criterion is to maximize the number of different sequences in which the assembly tasks can be executed. The second criterion is to minimize the total assembly time through simultaneous execution of assembly tasks. This paper also shows an algorithm that performs a heuristic search for the best assembly plan over the AND/OR graph representation of assembly plans introduced in previous work. Admissible heuristics for each of the two criteria introduced are presented. Some implementation issues that affect the computational efficiency are addressed. C1 RENSSELAER POLYTECH INST, DEPT ELECT COMP & SYST ENGN, TROY, NY 12180 USA. RP CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 16 TC 35 Z9 35 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD OCT PY 1991 VL 7 IS 5 BP 626 EP 633 PG 8 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA GH852 UT WOS:A1991GH85200007 ER PT J AU WHITAKER, SR MAKI, GK SHAMANNA, M AF WHITAKER, SR MAKI, GK SHAMANNA, M TI RELIABLE VLSI SEQUENTIAL CONTROLLERS SO INTERNATIONAL JOURNAL OF ELECTRONICS LA English DT Article AB A VLSI architecture for synchronous sequential controllers is presented that has attractive qualities for producing reliable circuits. In these circuits, one hardware implementation can realize any flow table with a maximum of 2n internal states and m inputs. A real time fault detection means is presented along with a strategy for verifying the correctness of the checking hardware. This self-check feature can be employed with no increase in hardware. The architecture can be modified to achieve fail-safe designs. With no increase in hardware, an adaptable circuit can be realized that allows replacement of faulty transitions with fault-free transitions. RP WHITAKER, SR (reprint author), UNIV IDAHO,NASA,SPACE ENGN RES CTR VLSI SYSTEM DESIGN,MOSCOW,ID 83843, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0020-7217 J9 INT J ELECTRON JI Int. J. Electron. PD OCT PY 1991 VL 71 IS 4 BP 609 EP 620 DI 10.1080/00207219108925504 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA GK623 UT WOS:A1991GK62300004 ER PT J AU TOLMUNEN, TJ FRERKING, MA AF TOLMUNEN, TJ FRERKING, MA TI THEORETICAL PERFORMANCE OF NOVEL MULTIPLIERS AT MILLIMETER AND SUBMILLIMETER WAVELENGTHS SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article DE MILLIMETER WAVELENGTHS; SUBMILLIMETER WAVELENGTHS; FREQUENCY MULTIPLIERS; SCHOTTKY VARACTOR; QUANTUM WELL DIODE; SINGLE BARRIER VARACTOR; BIN DIODE; BNN DIODE; DELTA-DOPED VARACTOR; HIGH ELECTRON MOBILITY VARACTOR ID VARACTOR FREQUENCY-MULTIPLIER; WAVE MULTIPLIERS; DIODES; MICROWAVE AB A theoretical comparison of various low and high order multipliers for 200 GHz and 1 THz has been carried out. Novel diodes including single barrier varactors, barrier-intrinsic-n+ diodes and high electron mobility varactors are shown to have excellent theoretical performance, comparable or better than the conventional Schottky varactors for single and double diode frequency multipliers at millimeter and submillimeter wavelengths, whereas quantum well diodes, since they suffer from high resistive losses, are shown to be less attractive. In comparison to the conventional Schottky varactor, these new diodes have some potential advantages in their characteristics such as a stronger nonlinearity or a special symmetry. For future optimization some general comments on these advantages as well as other factors affecting multiplication is given. C1 HELSINKI UNIV TECHNOL,RADIO LAB,SF-02150 ESPOO,FINLAND. RP TOLMUNEN, TJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 29 TC 7 Z9 7 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD OCT PY 1991 VL 12 IS 10 BP 1111 EP 1133 DI 10.1007/BF01008554 PG 23 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA GJ575 UT WOS:A1991GJ57500001 ER PT J AU KIMES, DS HARRISON, PR RATCLIFFE, PA AF KIMES, DS HARRISON, PR RATCLIFFE, PA TI A KNOWLEDGE-BASED EXPERT SYSTEM FOR INFERRING VEGETATION CHARACTERISTICS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID REFLECTANCE FACTOR DISTRIBUTIONS; HEMISPHERICAL REFLECTANCE; CANOPY REFLECTANCE; SURFACE; TRANSPIRATION; RADIOMETER; RADIANCE; CLIMATE; ALBEDO; NADIR AB The overall goal of the research is to develop a robust extraction technique for inferring physical and biological surface properties of vegetation using nadir and/or directional reflectance data as input. A prototype knowledge-based expert system VEG is described that concentrates on extracting spectral hemispherical reflectance using any combination of nadir and/or directional reflectance data as input. VEG is designed to facilitate expansion to handle other inferences regarding vegetation properties such as total hemispherical reflectance, per cent ground cover, leaf area index, biomass, and photosynthetic capacity. This approach is more accurate and robust than conventional extraction techniques developed by the investigator and others. VEG combines methods from remote sensing and Artificial Intelligence (AI). It integrates input spectral measurements with diverse knowledge bases available from the literature, data sets of directional reflectance measurements, and form experts, into an intelligent and efficient system for making vegetation inferences. VEG accepts spectral data of an unknown target as input, determines the best strategy or strategies for inferring hemispherical reflectance, applies the strategy or strategies to the target data, and provides a rigorous estimate of the accuracy of the inference. VEG is also intended to become a valuable research tool with provisions for testing and developing new extraction techniques on an internal spectral data base, for browsing and analysis (multiple plotting schemes) of the data in the system's spectral data base, and for the development of discrimination learning algorithms that discriminate the spectral and directional reflectance relationships between user-defined vegetation classes. C1 USN ACAD,ANNAPOLIS,MD 21402. JORGE SCI CORP,ARLINGTON,VA 22202. RP KIMES, DS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 43 TC 22 Z9 25 U1 1 U2 6 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD OCT PY 1991 VL 12 IS 10 BP 1987 EP 2020 PG 34 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA GH736 UT WOS:A1991GH73600001 ER PT J AU SMITH, RCG CHOUDHURY, BJ AF SMITH, RCG CHOUDHURY, BJ TI ANALYSIS OF NORMALIZED DIFFERENCE AND SURFACE-TEMPERATURE OBSERVATIONS OVER SOUTHEASTERN AUSTRALIA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID LEAF-AREA INDEX; VEGETATION INDEXES; SPECTRAL ESTIMATION; CORN CANOPIES; WINTER-WHEAT; REFLECTANCE; EVAPOTRANSPIRATION; PHOTOSYNTHESIS; VARIABILITY; EVAPORATION AB Relations between radiative surface temperature (T(R)) and visible and near-infrared reflectances expressed as the normalized difference (ND) from a Landsat Thematic Mapper scene were analysed to study the heat balance of agriculture and native evergreen forests in southeastern Australia. The scene was at 0922 h (local time) during late spring (15 October 1986) with phenology of winter annual species between flowering and grain filling. Factors determining the slope of, and residual scatter about, the T(R)/ND relationships were analysed using a coupled two-layer soil-vegetation model of the surface heat balance. Inverse linear relationships were found between T(R) and ND for agriculture, but not for forests. This was a result of a wide range of ND and T(R) values in agricultural areas caused by wide variations in fractional vegetation cover. The relationships between ND and fractional vegetation cover was not general, thus, when forest and agricultural data were combined, the lower near-infrared reflectance of forests (16.9 per cent) compared with agricultural crops (29.0 per cent) resulted in forest data falling below the regression line for agriculture. From the agricultural relations, 60 to 70 per cent of the variation in T(R) was explained by ND, indicating that fractional vegetation cover was the dominant factor determining T(R). Residual variability of T(R) was attributed to spatial variability in ambient temperature, rates of soil evaporation and variations in stage of phenological development affecting stomatal resistance. Energy-balance analysis of the effect of soil water availability on the slope of the T(R)/ND relationship indicated opposite effects depending on whether the reduction in evaporation was from soil or from vegetation. Thus, the generality of using the slope of the T(R)/ND relationship to predict surface resistance to evaporation may be limited. It was concluded that extraction of information contained in T(R) and ND data for regional estimation of evaporation requires the separation of T(R) into soil and vegetation temperatures and an alternative to ND that relates more generally to fractional vegetation cover. RP SMITH, RCG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,HYDROL SCI BRANCH,CODE 624,GREENBELT,MD 20771, USA. NR 49 TC 67 Z9 81 U1 1 U2 7 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD OCT PY 1991 VL 12 IS 10 BP 2021 EP 2044 PG 24 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA GH736 UT WOS:A1991GH73600002 ER PT J AU HANNAFORD, B LEE, P AF HANNAFORD, B LEE, P TI HIDDEN MARKOV MODEL ANALYSIS OF FORCE TORQUE INFORMATION IN TELEMANIPULATION SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article ID RECOGNITION AB A new model is developed for prediction and analysis of sensor information recorded during robotic performance of tasks by telemanipulation. The model uses the Hidden Markov Model (stochastic functions of Markov nets; HMM) to describe the task structure, the operator or intelligent controller's goal structure, and the sensor signals such as forces and torques arising from interaction with the environment. The Markov process portion encodes the task sequence/subgoal structure, and the observation densities associated with each subgoal state encode the expected sensor signals associated with carrying out that subgoal. Methodology is described for construction of the model parameters based on engineering knowledge of the task. The Viterbi algorithm is used for model based analysis of force signals measured during experimental teleoperation and achieves excellent segmentation of the data into subgoal phases. The Baum-Welch algorithm is used to identify the most likely HMM from a given experiment. The HMM achieves a structured, knowledge-based model with explicit uncertainties and mature, optimal identification algorithms. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP HANNAFORD, B (reprint author), UNIV WASHINGTON, DEPT ELECT ENGN, SEATTLE, WA 98195 USA. NR 15 TC 54 Z9 54 U1 0 U2 4 PU SAGE PUBLICATIONS LTD PI LONDON PA 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND SN 0278-3649 EI 1741-3176 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD OCT PY 1991 VL 10 IS 5 BP 528 EP 539 DI 10.1177/027836499101000508 PG 12 WC Robotics SC Robotics GA GL396 UT WOS:A1991GL39600008 ER PT J AU SCHIFF, LB CUMMINGS, RM SORENSON, RL RIZK, YM AF SCHIFF, LB CUMMINGS, RM SORENSON, RL RIZK, YM TI NUMERICAL-SIMULATION OF HIGH-INCIDENCE FLOW OVER THE ISOLATED F-18 FUSELAGE FOREBODY SO JOURNAL OF AIRCRAFT LA English DT Article AB As part of the NASA High Alpha Technology Program, fine-grid Navier-Stokes solutions have been obtained for flow over the fuselage forebody and wing leading-edge extension of the F/A-18 high alpha research vehicle at large incidence. The resulting flows are complex, and exhibit crossflow separation from the sides of the forebody and from the leading edge extension. A well-defined vortex pattern is observed in the leeward-side flow. Results obtained for laminar flow good agreement with flow visualizations obtained in ground-based experiments. Further, turbulent flows computed at high-Reynolds-number flight-test conditions show good agreement with surface and offsurface visualizations obtained in flight. RP SCHIFF, LB (reprint author), NASA,AMES RES CTR,DIV FLUID DYNAM,MAIL STOP 258-1,MOFFETT FIELD,CA 94035, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD OCT PY 1991 VL 28 IS 10 BP 609 EP 617 DI 10.2514/3.46072 PG 9 WC Engineering, Aerospace SC Engineering GA GJ504 UT WOS:A1991GJ50400001 ER PT J AU ANDERSON, BT MEYER, RR CHILES, HR AF ANDERSON, BT MEYER, RR CHILES, HR TI TECHNIQUES USED IN THE F-14 VARIABLE-SWEEP TRANSITION FLIGHT EXPERIMENT SO JOURNAL OF AIRCRAFT LA English DT Article AB This article discusses and evaluates the test measurement techniques used to determine the laminar-to-turbulent boundary-layer transition location in the F-14 variable-sweep transition flight experiment (VSTFE). The main objective of the VSTFE was to determine the effects of wing sweep on the laminar-to-turbulent transition location at conditions representative of transport aircraft. Four methods were used to determine the transition location: 1) a hot-film anemometer system, 2) two boundary-layer rakes, 3) surface pitot tubes, and 4) liquid crystals for flow visualization. Of the four methods, the hot-film anemometer system was the most reliable indicator of transition. RP ANDERSON, BT (reprint author), NASA,AMES RES CTR,DRYDEN FLIGHT RES FACIL,AERODYNAM BRANCH,DIV RES ENGN,EDWARDS AFB,CA 93523, USA. NR 0 TC 2 Z9 2 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD OCT PY 1991 VL 28 IS 10 BP 622 EP 629 DI 10.2514/3.46074 PG 8 WC Engineering, Aerospace SC Engineering GA GJ504 UT WOS:A1991GJ50400003 ER PT J AU MANUEL, GS DOTY, WA AF MANUEL, GS DOTY, WA TI FLIGHT-TEST INVESTIGATION OF CERTIFICATION REQUIREMENTS FOR LAMINAR-FLOW GENERAL-AVIATION AIRPLANES SO JOURNAL OF AIRCRAFT LA English DT Article AB A flight investigation has been conducted using a modified Cessna T210R to evaluate the performance, stability, and control characteristics of a general aviation airplane with significant natural laminar flow (NLF). Development of NLF technology for application to general-aviation-type aircraft requires an examination of the adequacy of existing certification requirements. The study focused on the aircraft's ability to meet certification requirements with significant NLF and also with the boundary-layer transition fixed near the leading edge. The investigation showed that large regions of NLF on the airplane's surfaces significantly enhanced cruise performance. Loss of laminar flow did not produce significant changes in the stability and control characteristics of this conventional configuration because of the well-designed NLF sections used. The research airplane met the Federal Aviation Regulations Part 23 certification requirements even though it was not intended to be certified. RP MANUEL, GS (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 247,HAMPTON,VA 23665, 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 OCT PY 1991 VL 28 IS 10 BP 652 EP 656 DI 10.2514/3.46078 PG 5 WC Engineering, Aerospace SC Engineering GA GJ504 UT WOS:A1991GJ50400007 ER PT J AU ELLIOTT, S TURCO, RP TOON, OB HAMILL, P AF ELLIOTT, S TURCO, RP TOON, OB HAMILL, P TI APPLICATION OF PHYSICAL ADSORPTION THERMODYNAMICS TO HETEROGENEOUS CHEMISTRY ON POLAR STRATOSPHERIC CLOUDS SO JOURNAL OF ATMOSPHERIC CHEMISTRY LA English DT Article DE ISOTHERM; ADSORPTIVE EQUILIBRIUM; ISOSTERE; DIFFERENTIAL AND INTEGRAL ENTHALPY; CLAUSIUS CLAPEYRON RELATION; STRATOSPHERIC ACIDS; SURFACE COVERAGE; DESORPTION RATES; SURFACE ENCOUNTER ID NITRIC-ACID TRIHYDRATE; REACTION-KINETICS; VAPOR-PRESSURES; ICE; HCL; DIFFUSION; OZONE; SOLUBILITY; MODEL AB Laboratory isotherms for the binding of several nonheterogeneously active atmospheric gases and for HCl to water ice are translated into adsorptive equilibrium constants and surface enthalpies. Extrapolation to polar conditions through the Clausius Clapeyron relation yields coverage estimates below the percent level for N2, Ar, CO2, and CO, suggesting that the crystal faces of type II stratospheric cloud particles may be regarded as clean with respect to these species. For HCl, and perhaps HF and HNO3, estimates rise to several percent, and the adsorbed layer may offer acid or proton sources alternate to the bulk solid for heterogeneous reactions with stratospheric nitrates. Measurements are lacking for many key atmospheric molecules on water ice, and almost entirely for nitric acid trihydrate as substrate. Adsorptive equilibria enter into gas to particle mass flux descriptions, and the binding energy determines rates for desorption of, and encounter between, potential surface reactants. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV,DEPT PHYS,SAN JOSE,CA 95192. NR 45 TC 30 Z9 30 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-7764 J9 J ATMOS CHEM JI J. Atmos. Chem. PD OCT PY 1991 VL 13 IS 3 BP 211 EP 224 DI 10.1007/BF00058133 PG 14 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA GR097 UT WOS:A1991GR09700001 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H RICE, JE KOMORNICKI, A AF BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H RICE, JE KOMORNICKI, A TI A THEORETICAL-STUDY OF NA(H2O)N+ (N = 1-4) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; ELECTRON CORRELATION; BINDING-ENERGIES; WATER-MOLECULES; GAS-PHASE; FAST ION; CONTRACTION AB The successive H2O binding energies of Na(H2O)n+ are in excellent agreement with experiment and are rather insensitive to electron correlation since the bonding is predominantly electrostatic. A point-charge model shows that changes in the successive binding energies are due primarily to ligand-ligand repulsion. Vibrational frequencies and infrared intensities are determined for Na(H2O)n+ (n = 1-4) at the self-consistent-field and second-order Moller-Plesset levels of theory to facilitate experimental study of these ions. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. IBM CORP, ALMADEN RES CTR, DIV RES, SAN JOSE, CA 95120 USA. POLYATOM RES INST, MT VIEW, CA 95120 USA. RI Rice, Julia/K-4928-2012 OI Rice, Julia/0000-0001-5059-5127 NR 28 TC 150 Z9 150 U1 3 U2 7 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 OCT 1 PY 1991 VL 95 IS 7 BP 5142 EP 5148 DI 10.1063/1.461682 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA GH356 UT WOS:A1991GH35600044 ER PT J AU LIU, WT TANG, WQ NIILER, PP AF LIU, WT TANG, WQ NIILER, PP TI HUMIDITY PROFILES OVER THE OCEAN SO JOURNAL OF CLIMATE LA English DT Article AB The distribution of water vapor in the atmosphere affects climate change through radiative balance and surface evaporation. The variabilities of atmospheric humidity profile over oceans from daily to interannual time scales were examined using nine years of daily and semidaily radiosonde soundings at island stations extending from the Arctic to the South Pacific. The relative humidity profiles were found to have considerable temporal and geographic variabilities, contrary to the prevalent assumption. Principal component analysis on the profiles of specific humidity were used to examine the applicability of a relation between the surface-level humidity and the integrated water vapor; this relation has been used to estimate large-scale evaporation from satellite data. The first principal component was found to correlate almost perfectly with the integrated water vapor. The fractional variance represented by this mode increases with increasing period. It reaches approximately 90% at two weeks and decreases sharply, below one week, down to approximately 60% at the daily period. At low frequencies, the integrated water vapor appeared to be an adequate estimator of the humidity profile and the surface-level humidity. At periods shorter than a week, more than one independent estimator is needed. High-frequency surface humidity can be estimated if additional information on the vertical structure of the humidity profile is available or if the integrated water vapor in the boundary layer, instead of the entire atmospheric column, can be measured accurately by spaceborne sensors. RP LIU, WT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 61 Z9 64 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT PY 1991 VL 4 IS 10 BP 1023 EP 1034 DI 10.1175/1520-0442(1991)004<1023:HPOTO>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GU112 UT WOS:A1991GU11200004 ER PT J AU FREY, MAB RIDDLE, J CHARLES, JB BUNGO, MW AF FREY, MAB RIDDLE, J CHARLES, JB BUNGO, MW TI BLOOD AND URINE RESPONSES TO INGESTING FLUIDS OF VARIOUS SALT AND GLUCOSE-CONCENTRATIONS SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID PLASMA-VOLUME; TRANSPORT; VASOPRESSIN; OSMOLALITY; EXERCISE; HUMANS AB Several hours before returning to Earth, Space Shuttle astronauts consume fluid and salt tablets equivalent to a liter of 0.9% saline as a countermeasure to postflight orthostatic intolerance. This countermeasure is not completely successful. Therefore, in search of a countermeasure that would protect against orthostatic intolerance better and for a longer duration, the authors compared the blood and urine responses of five men (21-41 yr) after they drank 1 L of 0.9% saline to their responses after drinking five other solutions: distilled water, 1% glucose, 0.74% saline with 1% glucose, 0.9% saline with 1% glucose, and 1.07% saline. Each subject ingested a different solution on 6 different days and remained seated for the ensuing 4 hours. Heart rate, blood pressures, and urine variables were measured before ingestion of the fluids and every 30 minutes thereafter; blood samples were drawn before, immediately after, and every 60 minutes after ingestion. Change in plasma volume, which was estimated from hemoglobin and hematocrit, was considered the most critical variable. Data for all solutions were compared by analysis of variance. Since plasma volume was increased most after ingestion of 1.07% saline, all variables (at 2 hours, at 3 hours and at 4 hours) were compared between 1.07% saline and 0.9% saline, the current countermeasure. Plasma volume was increased more after 1.07% saline than after 0.9% saline, and this difference was most significant at 4 hours after ingestion (P = .056). Diuresis occurred promptly after ingestion of the two saline-free solutions, water and 1% glucose. Subjects' heart rates and blood pressures did not differ as a function of the solution consumed or the time after ingestion except that heart rate (for all drinks) was higher immediately after ingestion than at all other times. The solutions containing glucose did not significantly enhance any variables as compared with 0.9% saline. The authors conclude that the addition of 1% glucose will not improve the effectiveness or the duration of plasma volume expansion as compared with the present fluid countermeasure but that increasing salt concentration may. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. WRIGHT STATE UNIV,DAYTON,OH 45435. KRUG INT,SAN ANTONIO,TX. UNIV SPACE RES ASSOC,COLUMBIA,MD. NR 20 TC 10 Z9 10 U1 1 U2 4 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 880 EP 887 PG 8 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000002 PM 1761715 ER PT J AU FORTNEY, SM AF FORTNEY, SM TI DEVELOPMENT OF LOWER-BODY NEGATIVE-PRESSURE AS A COUNTERMEASURE FOR ORTHOSTATIC INTOLERANCE SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID RESPONSES; FLIGHT AB Exposure to prolonged (1-4 hr) lower body negative pressure (LBNP) is a countermeasure against postflight orthostatic intolerance which is used in the Soviet space program and planned for use in the American space program. LBNP in combination with fluid-loading is believed to act by promoting a transient positive fluid balance resulting in an increase in vascular, as well as extravascular fluid. Inflight LBNP also may provide beneficial orthostatic effects by restoring baroreceptor reflex functions and/or lower body venous compliance. Current research efforts at the Johnson Space Center are directed towards increasing the effectiveness and efficiency of the LBNP and saline countermeasure. A promising avenue may involve combining pharmacologic agents, such as inhaled anti-diuretic hormone, or mineralocorticoids, with mechanical stimuli such as LBNP. RP FORTNEY, SM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,MAIL CODE SD5,HOUSTON,TX 77058, USA. NR 29 TC 20 Z9 23 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 888 EP 892 PG 5 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000003 PM 1761716 ER PT J AU LATHERS, CM DIAMANDIS, PH RIDDLE, JM MUKAI, C ELTON, KF BUNGO, MW CHARLES, JB AF LATHERS, CM DIAMANDIS, PH RIDDLE, JM MUKAI, C ELTON, KF BUNGO, MW CHARLES, JB TI ORTHOSTATIC FUNCTION DURING A STAND TEST BEFORE AND AFTER HEAD-UP OR HEAD-DOWN BEDREST SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID EARLY CARDIOVASCULAR ADAPTATION; ZERO GRAVITY; SPACE; MIDODRINE; TILT; PHARMACOLOGY; RESPONSES; AGENT AB Astronauts may exhibit orthostatic dysfunction upon returning to 1 g after space flight. Understanding cardiovascular changes at 0 G will provide insights into the mechanisms of the loss of orthostatic tolerance, whether due to space flight or bedrest. Bedrest is one model used to produce cardiovascular changes that are associated with space flight. In the current study, young male adults were placed at -5-degrees, +10, +20, or +42-degrees bedrest (0, 1/6, 1/3, and 2/3g, respectively) for 6 hours on 4 different days. This was preceded and followed by a stand test: 5 minutes in the supine position, and then 5 minutes in the standing position, with the feet 9 inches apart and 6 inches from the wall. Cardiovascular values were measured at 1-minute intervals. Systolic and diastolic pressures were measured using an automated blood pressure device; mean arterial pressure (MAP; mm Hg) was calculated. Heart rate (bpm) and cardiac parameters were measured with a thoracic impedance device. Minute 3, 4, and 5 values were used to determine whether there were time or angle effects. Of six subjects, one reported nausea upon 3 minutes of standing after 6 hours of bedrest at -5-degrees. The same subject was lightheaded in the first minute of standing after 6 hours of bedrest at +10-degrees. Mean heart rate pre-bedrest in the supine position was 63 and increased by 24 bpm on standing. Heart rate post-bedrest in the supine position was 65 and increased by 35 bpm on standing; standing heart rate increased 11 bpm after -5-degrees bedrest. The increases after +10-degrees, +20-degrees, and +42-degrees tilts were 4, 3, and 4 bpm, respectively. Changes in the mean arterial blood pressure were minimal. Results from the stand test pre- and post-6 hours of bedrest at -5-degrees but not at +10-degrees, +20-degrees, or +42-degrees are similar to those after space flight. C1 MIT,DEPT AERONAUT & ASTRONAUT,CAMBRIDGE,MA 02139. HARVARD UNIV,SCH MED,BOSTON,MA 02115. KRUG INT,HOUSTON,TX. NATL SPACE DEV AGCY JAPAN,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,SPAC BIOMED RES INST,HOUSTON,TX 77058. RP LATHERS, CM (reprint author), UNIV SPACE RES ASSOC,DIV SPACE BIOMED,17225 EL CAMINO REAL,SUITE 450,HOUSTON,TX 77058, USA. NR 27 TC 15 Z9 16 U1 0 U2 2 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 893 EP 903 PG 11 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000004 PM 1761717 ER PT J AU BAGIAN, JP AF BAGIAN, JP TI 1ST INTRAMUSCULAR ADMINISTRATION IN THE UNITED-STATES SPACE PROGRAM SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 13 Z9 13 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 920 EP 920 PG 1 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000008 PM 1761721 ER PT J AU LEACH, CS CINTRON, NM KRAUHS, JM AF LEACH, CS CINTRON, NM KRAUHS, JM TI METABOLIC CHANGES OBSERVED IN ASTRONAUTS SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID PROLONGED SPACE-FLIGHT; VENOUS-PRESSURE; WEIGHTLESSNESS AB Study of metabolic alterations that occur during space flight can provide insight into mechanisms of physiologic regulation. Results of medical experiments with astronauts reveal rapid loss of volume (2 L) from the legs and a transient early increase in left ventricular volume index. These findings indicate that, during space flight, fluid is redistributed from the legs toward the head. In about 2 days, total body water decreases 2 to 3%. Increased levels of plasma renin activity and antidiuretic hormone while blood sodium and plasma volume are reduced suggest that space flight-associated factors are influencing the regulatory systems. In addition to fluid and electrolyte loss, Skylab astronauts lost an estimated 0.3 kg of protein. Endocrine factors, including increased cortisol and thyroxine and decreased insulin, are favorable for protein catabolism. The body appears to adapt to weightlessness at some physiologic cost. Readaptation to Earth's gravity at landing becomes another physiologic challenge. RP LEACH, CS (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,MAIL CODE SD4,HOUSTON,TX 77058, USA. NR 46 TC 23 Z9 24 U1 0 U2 2 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 921 EP 927 PG 7 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000009 PM 1761722 ER PT J AU SANTY, PA BUNGO, MW AF SANTY, PA BUNGO, MW TI PHARMACOLOGICAL CONSIDERATIONS FOR SHUTTLE ASTRONAUTS SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM AB Medication usage by crewmembers in the preflight and inflight mission periods is common in the Shuttle Program. The most common medical reports for which medication is used are: space motion sickness (SMS), sleeplessness, headache, and backache. A number of medications are available in the Shuttle Medical Kit to treat these problems. Currently, astronauts test all frequently used medications before mission assignment to identify potential side-effects, problems related to performance, personal likes/dislikes, and individual therapeutic effect. However, microgravity-induced changes in drug pharmacokinetics, in combination with multiple operational factors, may significantly alter crewmember responses inflight. This article discusses those factors that may impact pharmacologic efficacy during Shuttle missions. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. NR 7 TC 13 Z9 14 U1 2 U2 4 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 931 EP 933 PG 3 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000011 PM 1761724 ER PT J AU KOHL, RL MACDONALD, S AF KOHL, RL MACDONALD, S TI NEW PHARMACOLOGICAL APPROACHES TO THE PREVENTION OF SPACE MOTION SICKNESS SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID CHEMOTHERAPY-INDUCED EMESIS; KAPPA-OPIOID RECEPTORS; ARGININE VASOPRESSIN; SQUIRREL-MONKEY; AREA POSTREMA; PARAVENTRICULAR NUCLEUS; RAT NEUROHYPOPHYSIS; CANCER-CHEMOTHERAPY; SUPRAOPTIC NUCLEI; DIURETIC ACTIVITY AB Fundamental approaches in selection of new agents for evaluation in prevention of space/motion sickness (SMS) are reviewed. The discussion centers on drugs under investigation at the Johnson Space Center. Methodology that employs the rotating chair for measuring SMS symptomatology and susceptibility is described. The most obvious approach to the development of new agents relies on selection of agents from drug classes that possess pharmacologic properties of established anti-motion sickness agents. A second approach selects drugs that are used to prevent emesis caused by means other than exposure to motion. The third approach relies on basic research that characterizes individual differences in susceptibility. The hypothesis is: detection of individual differences leads to identification of specific drugs, which target physiologic systems that show individual differences. These physiologic systems are targets for therapy and may play a role in the etiology of SMS. Two drugs that reduce susceptibility to SMS include dexamethasone and d(CH2)5Tyr(Me)AVP, a vasopressin (AVP)V1 antagonist. The latter peptide has demonstrated complete blockade of emesis and other significant symptoms in squirrel monkeys. These studies were predicated on observations that subjects who were more resistant to SMS had higher plasma AVP after severe nausea than subjects with lower resistances. Investigations are underway to test a 0.5-mg intravenous dose in humans. Kappa opioid agonists inhibit AVP release and offer new therapeutic possibilities and advantages over AVP peptides. This review details the experimental data collected on AVP and adrenocorticotropin. The literature supports interrelated roles for AVP and opioid peptides in SMS. Experimental testing of kappa agonists is warranted because specific opioid agonists act at neuroanatomical sites causing nausea and vomiting. It is argued opioid receptors in the chemoreceptor trigger zone and vomiting center stimulate and inhibit the emetic response, respectively. The evidence suggests kappa and/or mu receptors at VC are involved in inhibition of emesis, whereas delta opioid receptors at CTZ are involved in stimulation of emesis. C1 UNIV TEXAS,MED BRANCH,GALVESTON,TX 77550. NASA,LYNDON B JOHNSON SPACE CTR,UNIV SPACE RES ASSOC,DIV SPACE BIOMED,HOUSTON,TX 77058. NR 126 TC 24 Z9 26 U1 1 U2 2 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 934 EP 946 PG 13 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000012 PM 1662231 ER PT J AU VERNIKOS, J DALLMAN, MF VANLOON, G KEIL, LC AF VERNIKOS, J DALLMAN, MF VANLOON, G KEIL, LC TI DRUG EFFECTS ON ORTHOSTATIC INTOLERANCE INDUCED BY BEDREST SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID BED-REST; SPACE-FLIGHT; RESPONSES; HYPOTENSION; TOLERANCE; EXERCISE; BLOCKADE; PLASMA; VOLUME AB Effective and practical preventive procedures for postflight orthostatic intolerance are highly desirable. The current practice of attempts to expand plasma volume by ingestion of salt and fluids before reentry has proven benefits. This study evaluated alternative options using fludrocortisone (F) to expand plasma volume (PV), dextroamphetamine (Dex) to enhance norepinephrine (NE) release and atropine (A) to reduce the effects of vagal stimulation. Seven subjects with proven post-bedrest orthostatic intolerance returned for a 7-day 6-degrees head-down bedrest study. F (0.2 mg) was given at 8:00 AM and 8:00 PM the day before and 8:00 AM the day the subjects got out of bed (2 hours before standing). PV was measured before and 1 hour after the last dose of F. D (5 mg) and A (0.8 mg) were then taken orally 1 hour before the stand test. F expanded PV by 16% and caused sodium retention. Four of the 7 subjects stood for 1 hour post-bedrest and HR, plasma NE and PRA responses to standing were greatly enhanced and sustained. Although there was a narrowing of pulse pressure, the ability to overcome orthostatic intolerance with these countermeasures was largely due to vasoconstriction and sustained high heart rate. The existing literature on pharmacologic countermeasures for post-flight and post-bedrest orthostatic hypotension is reviewed, and the results are discussed in that context. C1 UNIV CALIF SAN FRANCISCO,SCH MED,DEPT PHYSIOL,SAN FRANCISCO,CA 94143. BILLINGS CLIN,BILLINGS,MN. RP VERNIKOS, J (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035, USA. NR 56 TC 23 Z9 26 U1 1 U2 1 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 974 EP 984 PG 11 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000018 PM 1761730 ER PT J AU MUKAI, CN LATHERS, CM CHARLES, JB BENNETT, BS IGARASHI, M PATEL, S AF MUKAI, CN LATHERS, CM CHARLES, JB BENNETT, BS IGARASHI, M PATEL, S TI ACUTE HEMODYNAMIC-RESPONSES TO WEIGHTLESSNESS DURING PARABOLIC FLIGHT SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM AB Pilots and astronauts experience fluid shifts in variable gravity. Acute effects of fluid shifts on the cardiovascular system were monitored on NASA's KC-135 aircraft during parabolic flight. The variability of R-R intervals in the electrocardiogram was measured as an indication of vagal cardiac neural activity. R-R intervals were measured during the gravity transition from 2-G to 0-G produced by parabolic flight to assess the involvement of the autonomic nervous system in regulating the acute effects of fluid shifts. In seven subjects, a BoMed noninvasive continuous cardiac output monitor (NCCOM 3) monitored thoracic fluid index (TFI, ohms), heart rate (bpm), and cardiac output (1/min). Data were stored on a lap-top computer with the subject in one of four postures: sitting, standing, supine, and semi-supine, during one of four sets of eight to ten parabolas. Five seconds of data were averaged: before parabola onset (1.3-G); parabola entry (1.9-G); 0-G; and parabola exit (1.7-G). Three to eight parabolas were averaged for subjects in each posture; the mean for each posture was calculated. In each of five additional subjects, the coefficient of variation was calculated by dividing mean value by the standard deviation of 3 to 15 R-R intervals. Eight to ten parabolas were averaged for each postural set. Compared with values collected before 0-G, standing values during 0-G showed that the thoracic fluid index decreased 2.5 ohms, heart rate decreased 22 bpm, and cardiac output increased 1 L/min. During sitting, thoractic fluid index decreased 1.25 ohms, heart rate decreased 10 bpm, whereas cardiac output increased 0.5 L/min. In the supine position, thoracic fluid index and heart rate were constant whereas cardiac output decreased 0.55 L/min. In the semi-supine position, thoracic fluid index and heart rate were constant. Compared with values collected from 2-G and 0-G the coefficient of variation increased 66.4% in the standing position, 53.4% in the sitting position, and 43.3% in the semi-supine position and decreased 11.6% in the supine position. The data indicated that cardiovascular changes are dependent on posture and gravity. During the four sets of parabolas in the four different postures, the greatest and smallest changes were observed in the standing and supine positions, respectively, during 0-G. Fluid shifts from the legs to the thorax occurred during 0-G in the supine and standing positions. The high values of the coefficient of variation at the onset of 0-G suggest that vagal cardiac neural activity increases, but not significantly, in all positions except supine. C1 US FDA,DIV CARDIORENAL,ROCKVILLE,MD 20857. KRUG LIFE SCI,HOUSTON,TX. BAYLOR COLL MED,DEPT OTORHINOLARYNGOL & COMMUN SCI,HOUSTON,TX 77030. RP MUKAI, CN (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058, USA. NR 7 TC 22 Z9 24 U1 1 U2 3 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 993 EP 1000 PG 8 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000021 PM 1761733 ER PT J AU LEACH, CS INNERS, D CHARLES, JB AF LEACH, CS INNERS, D CHARLES, JB TI CHANGES IN TOTAL-BODY WATER DURING SPACEFLIGHT SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID SALIVA; O-18 C1 KRUG LIFE SCI,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,DIV MED SCI,HOUSTON,TX 77058. RP LEACH, CS (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE & LIFE SCI DIRECTORATE,MAIL CODE SA,HOUSTON,TX 77058, USA. NR 14 TC 24 Z9 25 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 1001 EP 1006 PG 6 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000022 PM 1761710 ER PT J AU CHARLES, JB LATHERS, CM AF CHARLES, JB LATHERS, CM TI CARDIOVASCULAR ADAPTATION TO SPACEFLIGHT SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID SPACE-FLIGHT; HUMANS C1 US FDA,DIV CARDIORENAL DRUG PROD,ROCKVILLE,MD 20857. RP CHARLES, JB (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058, USA. NR 13 TC 68 Z9 71 U1 0 U2 2 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 1010 EP 1023 PG 14 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000024 PM 1761711 ER PT J AU MULVAGH, SL CHARLES, JB RIDDLE, JM REHBEIN, TL BUNGO, MW AF MULVAGH, SL CHARLES, JB RIDDLE, JM REHBEIN, TL BUNGO, MW TI ECHOCARDIOGRAPHIC EVALUATION OF THE CARDIOVASCULAR EFFECTS OF SHORT-DURATION SPACEFLIGHT SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM ID ULTRASOUND C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. KRUG INT,HOUSTON,TX. RP MULVAGH, SL (reprint author), UNIV SPACE RES ASSOC,DIV SPACE LIFE SCI,17225 EL CAMINO REAL,SUITE 450,HOUSTON,TX 77058, USA. NR 10 TC 60 Z9 62 U1 0 U2 2 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 1024 EP 1026 PG 3 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000025 PM 1761712 ER PT J AU LLOYD, CW AF LLOYD, CW TI SPACE-MEDICINE - ANSWERING THE CHALLENGE SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM RP LLOYD, CW (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SD5,HOUSTON,TX 77058, USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 1027 EP 1035 PG 9 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000026 PM 1761713 ER PT J AU BAGIAN, JP HACKETT, P AF BAGIAN, JP HACKETT, P TI CEREBRAL BLOOD-FLOW - COMPARISON OF GROUND-BASED AND SPACEFLIGHT DATA AND CORRELATION WITH SPACE ADAPTATION SYNDROME SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article; Proceedings Paper CT 10TH SYMP ON FRONTIERS OF PHARMACOLOGY CY MAY 10, 1990 CL HOUSTON, TX SP AMER COLL CLIN PHARM C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV ALASKA,FAIRBANKS,AK 99701. NR 4 TC 17 Z9 18 U1 0 U2 1 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 1991 VL 31 IS 10 BP 1036 EP 1040 PG 5 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GL990 UT WOS:A1991GL99000027 PM 1761714 ER PT J AU FARLEY, GL AF FARLEY, GL TI THE EFFECTS OF CRUSHING SPEED ON THE ENERGY-ABSORPTION CAPABILITY OF COMPOSITE TUBES SO JOURNAL OF COMPOSITE MATERIALS LA English DT Article AB The energy-absorption capability as a function of crushing speed was determined for Thornel 300-Fiberite 934 (Gr-E) and Kevlar-49-Fiberite 934 (K-E) composite material. Circular cross section tube specimens were crushed at speeds ranging from 0.01 m/sec to 12 m/sec. Ply orientations of the tube specimens were [0/ +/- THETA]2 and [+/- THETA]2 where THETA = 15, 45, and 75 degrees. Based upon the results of these tests the energy-absorption capability of Gr-E and K-E was determined to be a function of crushing speed. The magnitude of the effects of crushing speed on energy-absorption capability was determined to be a function of the mechanisms that control the crushing process. The effects of crushing speed on the energy-absorption capability is related to whether the mechanical response of the crushing mechanism that controls the crushing process is a function of strain rate. Energy-absorption capability of Gr-E and K-E tubes ranged between 0 and 35 percent and 20 and 45 percent, respectively depending upon ply orientation. The crushing modes based upon exterior appearance of the crushed tubes were unchanged as a result of changing crushing speed for either material. However, the interlaminar crushing behavior of the Gr-E specimens changed with crushing speed. RP FARLEY, GL (reprint author), USA,NASA,LANGLEY RES CTR,AVIAT RES & TECHNOL ACT,AEROSTRUCT & DIRECTORATE,HAMPTON,VA 23665, USA. NR 26 TC 65 Z9 66 U1 1 U2 6 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0021-9983 J9 J COMPOS MATER JI J. Compos Mater. PD OCT PY 1991 VL 25 IS 10 BP 1314 EP 1329 PG 16 WC Materials Science, Composites SC Materials Science GA GQ859 UT WOS:A1991GQ85900004 ER PT J AU DAVIDSON, BD AF DAVIDSON, BD TI DELAMINATION BUCKLING - THEORY AND EXPERIMENT SO JOURNAL OF COMPOSITE MATERIALS LA English DT Article ID GROWTH; FAILURE AB A Rayleigh-Ritz analysis is presented to determine the load or strain at which delamination buckling will occur for a composite laminate containing a single delamination. This delamination is assumed to be elliptical in shape, with local axes of symmetry which may be at an angle relative to the global plate axes. The laminate is assumed to be subjected to global loading which transforms to a loading with a relatively small shear component when taken about the local axes of the elliptical delamination, Special cases of this type of loading include uniaxial and biaxial compression. Possible bending-stretching coupling behavior of the delaminated region and the effect of Poisson's ratio mismatch between the delaminated and base region are investigated. Analytical predictions for delamination buckling loads are shown to correlate well with experimental results for a number of different geometries. C1 CALTECH,JET PROP LAB,DIV MECH SYST ENGN & RES,PASADENA,CA 91109. NR 41 TC 37 Z9 39 U1 0 U2 3 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0021-9983 J9 J COMPOS MATER JI J. Compos Mater. PD OCT PY 1991 VL 25 IS 10 BP 1351 EP 1378 PG 28 WC Materials Science, Composites SC Materials Science GA GQ859 UT WOS:A1991GQ85900007 ER PT J AU SPALART, PR MOSER, RD ROGERS, MM AF SPALART, PR MOSER, RD ROGERS, MM TI SPECTRAL METHODS FOR THE NAVIER-STOKES EQUATIONS WITH ONE INFINITE AND 2 PERIODIC DIRECTIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID SECONDARY INSTABILITY; NUMERICAL-SIMULATION; FLOWS; LAYER RP SPALART, PR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 26 TC 330 Z9 333 U1 2 U2 21 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT PY 1991 VL 96 IS 2 BP 297 EP 324 DI 10.1016/0021-9991(91)90238-G PG 28 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA GH413 UT WOS:A1991GH41300004 ER PT J AU FATEMI, NS WEIZER, VG AF FATEMI, NS WEIZER, VG TI THE FORMATION OF LOW RESISTANCE ELECTRICAL CONTACTS TO SHALLOW JUNCTION INP DEVICES WITHOUT COMPROMISING EMITTER INTEGRITY SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article; Proceedings Paper CT SYMP AT THE 1991 ANNUAL MEETING OF THE MINERALS, METALS AND MATERIALS SOC : STRAIN RELAXATION IN EPITAXIAL FILMS CY 1991 CL NEW ORLEANS, LA SP MINERALS MET & MAT SOC DE INP; CONTACTS; REFRACTORY METALS ID OHMIC CONTACTS; INDIUM-PHOSPHIDE; N-INP; BARRIER; METALS; GAAS AB An investigation is made into the possibility of providing low resistance contacts to shallow junction InP devices which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity R(c) to the 10(-5) ohm-cm2 range. If the In content is made to correspond exactly to that required to form the intermediate compound Au9In4, then the contacts so formed are stable, both electrically and metallurgically, even after extended annealing (12 hr) at 400-degrees-C. We next consider the contact system Au/Au2P3 which has been shown to exhibit as-fabricated R(c) values in the 10(-6) ohm-cm2 range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R(c) values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R(c) values in the 10(-7) ohm-cm2 range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP FATEMI, NS (reprint author), SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 18 TC 7 Z9 7 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD OCT PY 1991 VL 20 IS 10 BP 875 EP 880 DI 10.1007/BF02665977 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA GH657 UT WOS:A1991GH65700024 ER PT J AU BIELAK, J MACCAMY, RC MCGHEE, DS BARRY, A AF BIELAK, J MACCAMY, RC MCGHEE, DS BARRY, A TI UNIFIED SYMMETRICAL BEM-FEM FOR SITE EFFECTS ON GROUND MOTION SH-WAVES SO JOURNAL OF ENGINEERING MECHANICS-ASCE LA English DT Article ID LAYERED HALF-SPACE; GREEN-FUNCTIONS; RAYLEIGH-WAVES; P-WAVES; BOUNDARY; VALLEYS AB This paper is concerned with the numerical solution of time-harmonic transition problems in elasticity, in general, and with soil amplification in inhomogeneous alluvial valleys, in particular. A mixed variational formulation based on Hamilton's principle, involving field equations only within the valley and an integral representation for the surrounding medium, is developed and used to derive a symmetric finite element-boundary-element method for this problem. This method, valid for all frequencies, incorporates automatically the displacement and traction interface continuity conditions; therefore, it imposes no boundary constraints on the approximating functions. The BEM-FEM is applied to the response of semicircular inhomogeneous valleys with linearly increasing shear modulus with depth, due to oblique incident SH waves. Numerical results emphasize the importance of two-dimensional resonant effects in deep valleys, and the strong effects of varying stiffness on surface motion, including a rapid spatial variation, especially near valley edges. This can have practical implications in design as it suggests that it is possible for two similar structures located near each other to experience different levels of shaking and, thus, different damage levels during the same earthquake. C1 CARNEGIE MELLON UNIV,DEPT MATH,PITTSBURGH,PA 15213. EIDGENOSS TH LAUSANNE,LAUSANNE,SWITZERLAND. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP BIELAK, J (reprint author), CARNEGIE MELLON UNIV,DEPT CIVIL ENGN,PITTSBURGH,PA 15213, USA. NR 27 TC 16 Z9 16 U1 0 U2 0 PU ASCE-AMER SOC CIVIL ENG 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 OCT PY 1991 VL 117 IS 10 BP 2265 EP 2285 DI 10.1061/(ASCE)0733-9399(1991)117:10(2265) PG 21 WC Engineering, Mechanical SC Engineering GA GH419 UT WOS:A1991GH41900006 ER PT J AU SUKHAN, L JUN, P AF SUKHAN, L JUN, P TI NEURAL COMPUTATION FOR COLLISION-FREE PATH PLANNING SO JOURNAL OF INTELLIGENT MANUFACTURING LA English DT Article DE PATH PLANNING; NEURAL OPTIMIZATION; PATH REPRESENTATION; COLLISION AVOIDANCE; POTENTIAL FIELD ID TIME OBSTACLE AVOIDANCE; MOBILE ROBOTS; OPTIMIZATION; SPACE AB Automatic path planning plays an essential role in planning of assembly or disassembly of products, motions of robot manipulators handling part, and material transfer by mobile robots in an intelligent and flexible manufacturing environment. The conventional methodologies based on geometric reasoning suffer not only from the algorithmic difficulty but also from the excessive time complexity in dealing with 3-D path planning. This paper presents a massively parallel, connectionist algorithm for collision-free path planning. The path planning algorithm is based on representing a path as a series of via points or beads connected by elastic strings which are subject to displacement due to a potential field or a collision penalty function generated by polyhedral obstacles. Mathematically, this is equivalent to optimizing a cost function, defined in terms of the total path length and the collision penalty function, by moving the via points simultaneously but individually in the direction that minimizes the cost function. Massive parallelism comes mainly from: (1) the connectionist model representation of obstacles and (2) the parallel computation of individual via-point motions with only local information. The algorithm has power to deal effectively with path planning of three-dimensional objects with translational and rotational motions. Finally, the algorithm incorporates simulated annealing to solve a local minimum problem. Simulation results are shown. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,INST ROBOT & INTELLIGENT SYST,DEPT ELECT ENGN SYST,LOS ANGELES,CA 90089. NR 14 TC 1 Z9 1 U1 1 U2 4 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0956-5515 J9 J INTELL MANUF JI J. Intell. Manuf. PD OCT PY 1991 VL 2 IS 5 BP 315 EP 326 PG 12 WC Computer Science, Artificial Intelligence; Engineering, Manufacturing SC Computer Science; Engineering GA GK250 UT WOS:A1991GK25000007 ER PT J AU ROTH, DJ DEGUIRE, MR DOLHERT, LE HEPP, AF AF ROTH, DJ DEGUIRE, MR DOLHERT, LE HEPP, AF TI SPATIAL VARIATIONS IN AC SUSCEPTIBILITY AND MICROSTRUCTURE FOR THE YBA2CU3O7-X SUPERCONDUCTOR AND THEIR CORRELATION WITH ROOM-TEMPERATURE ULTRASONIC MEASUREMENTS SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID HIGH-TC SUPERCONDUCTORS; CU-O SYSTEM; CERAMIC SUPERCONDUCTORS; CRITICAL CURRENTS; DENSITY AB The purpose of this study was to (1) examine the spatial (within-sample) uniformity of superconducting behavior and microstructure in YBa2Cu3O7-x specimens over the pore fraction range 0.10-0.25 and (2) determine the viability of using a room-temperature, nondestructive characterization method (ultrasonic velocity imaging) to predict spatial variability. Spatial variations in a.c. susceptibility were observed for specimens containing 0.10 pore fraction. An ultrasonic velocity image constructed from measurements at 1 mm increments across one such specimen revealed microstructural variation between edge and center locations that correlated with variations in a.c. shielding and loss behavior. Optical quantitative image analysis on sample cross sections revealed pore fraction to be the varying microstructural feature. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. WR GRACE & CO,DIV RES,COLUMBIA,MD 21044. RP ROTH, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 50 TC 3 Z9 3 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD OCT PY 1991 VL 6 IS 10 BP 2041 EP 2053 DI 10.1557/JMR.1991.2041 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA GJ509 UT WOS:A1991GJ50900005 ER PT J AU FARRENQ, R GUELACHVILI, G SAUVAL, AJ GREVESSE, N FARMER, CB AF FARRENQ, R GUELACHVILI, G SAUVAL, AJ GREVESSE, N FARMER, CB TI IMPROVED DUNHAM COEFFICIENTS FOR CO FROM INFRARED SOLAR LINES OF HIGH ROTATIONAL-EXCITATION SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID HETERODYNE FREQUENCY MEASUREMENTS; (CO)-C-12-O-16 LASER TRANSITIONS; MU-M; CONSTANTS; SPECTRUM; DEPENDENCE; STANDARDS; CM-1; N2O; HCL C1 UNIV PARIS 06, PHYS MOLEC & APPLICAT LAB, F-75230 PARIS 05, FRANCE. OBSERV ROYAL BELGIQUE, B-1180 BRUSSELS, BELGIUM. UNIV LIEGE, INST ASTROPHYS, B-4000 COINTE OUGREE, BELGIUM. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP UNIV PARIS 11, CNRS, PHYS MOLEC & APPLICAT LAB, BAT 350, F-91405 ORSAY, FRANCE. NR 33 TC 103 Z9 103 U1 1 U2 8 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 EI 1096-083X J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD OCT PY 1991 VL 149 IS 2 BP 375 EP 390 DI 10.1016/0022-2852(91)90293-J PG 16 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA GE833 UT WOS:A1991GE83300006 ER PT J AU RINSLAND, CP SMITH, MAH DEVI, VM PERRIN, A FLAUD, JM CAMYPEYRET, C AF RINSLAND, CP SMITH, MAH DEVI, VM PERRIN, A FLAUD, JM CAMYPEYRET, C TI THE NU-2-BANDS OF (O3)-O-16-O-17-O-16 AND (O3)-O-16-O-16-O-17 - LINE POSITIONS AND INTENSITIES SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID ROTATIONAL SPECTRA; NU-2 BANDS C1 COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. UNIV PARIS 06,CNRS,PHYS MOLEC & APPLICAT LAB,F-75252 PARIS 05,FRANCE. UNIV PARIS 11,PHYS MOLEC & APPLICAT LAB,F-91405 ORSAY,FRANCE. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23665, USA. NR 9 TC 21 Z9 23 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD OCT PY 1991 VL 149 IS 2 BP 474 EP 480 DI 10.1016/0022-2852(91)90302-Q PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA GE833 UT WOS:A1991GE83300015 ER PT J AU CAMYPEYRET, C FLAUD, JM GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD BONOMO, FS MURCRAY, DG RINSLAND, CP AF CAMYPEYRET, C FLAUD, JM GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD BONOMO, FS MURCRAY, DG RINSLAND, CP TI THE NU-4-BAND OF CARBONYL FLUORIDE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID RESOLUTION; STRATOSPHERE; FREQUENCIES; SPECTRA; COF2; BAND; N2O C1 UNIV DENVER,DEPT PHYS,DENVER,CO 80208. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP CAMYPEYRET, C (reprint author), UNIV PARIS 06,CNRS,PHYS MOLEC & APPLICAT LAB,TOUR 13,BTE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 16 TC 13 Z9 13 U1 1 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD OCT PY 1991 VL 149 IS 2 BP 481 EP 490 DI 10.1016/0022-2852(91)90303-R PG 10 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA GE833 UT WOS:A1991GE83300016 ER PT J AU PERRIN, A VASSEROT, AM FLAUD, JM CAMYPEYRET, C DEVI, VM SMITH, MAH RINSLAND, CP BARBE, A BOUAZZA, S PLATEAUX, JJ AF PERRIN, A VASSEROT, AM FLAUD, JM CAMYPEYRET, C DEVI, VM SMITH, MAH RINSLAND, CP BARBE, A BOUAZZA, S PLATEAUX, JJ TI THE 2.5-MU-M BANDS OF OZONE - LINE POSITIONS AND INTENSITIES SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID SPECTRAL REGION; NU-3 BANDS; O-16(3); PARAMETERS; O-16O-18O-16; O-16O-16O-18; RESONANCE C1 UNIV PARIS 11,PHYS MOLEC & APPLICAT LAB,F-91405 ORSAY,FRANCE. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. UNIV REIMS,PHYS MOLEC LAB,CNRS,UA 776,F-51062 REIMS,FRANCE. RP PERRIN, A (reprint author), UNIV PARIS 06,PHYS MOLEC & APPLICAT LAB,BTE 76,TOUR 13,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 21 TC 37 Z9 37 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD OCT PY 1991 VL 149 IS 2 BP 519 EP 529 DI 10.1016/0022-2852(91)90307-V PG 11 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA GE833 UT WOS:A1991GE83300020 ER PT J AU SALTZ, J PETITON, S BERRYMAN, H RIFKIN, A AF SALTZ, J PETITON, S BERRYMAN, H RIFKIN, A TI PERFORMANCE EFFECTS OF IRREGULAR COMMUNICATION PATTERNS ON MASSIVELY PARALLEL MULTIPROCESSORS SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article C1 ETAB TECH CENT ARMEMENT,F-94114 ARCUEIL,FRANCE. COLL WILLIAM & MARY,DEPT COMP SCI,WILLIAMSBURG,VA 23185. RP SALTZ, J (reprint author), NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,MAIL STOP 132C,HAMPTON,VA 23665, USA. NR 25 TC 5 Z9 5 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 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD OCT PY 1991 VL 13 IS 2 BP 202 EP 212 DI 10.1016/0743-7315(91)90089-R PG 11 WC Computer Science, Theory & Methods SC Computer Science GA GJ341 UT WOS:A1991GJ34100008 ER PT J AU CONNELL, JW HERGENROTHER, PM AF CONNELL, JW HERGENROTHER, PM TI SYNTHESIS AND CHARACTERIZATION OF POLY(ARYLENE ETHER IMIDAZOLE)S SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article AB Poly(arylene ether imidazole)s were prepared by the aromatic nucleophilic displacement reaction of a bisphenol imidazole with activated aromatic dihalides. The polymers had glass transition temperatures ranging from 230 to 318-degrees-C and number-average molecular weights as high as 82,000 g/mol. Thermogravimetric analysis showed a 5% weight loss occurring approximately 400-degrees-C in air and approximately 500-degrees-C in nitrogen. Typical neat resin mechanical properties obtained at room temperature included tensile strength and tensile modulus of 14.2 and 407 ksi and fracture energy (G(lc)) of 23 in.lb/in.2 Titanium-to-titanium tensile shear strengths measured at 23 and 200-degrees-C were 4800 and 3000 psi, respectively. In addition, preliminary data were obtained on carbon fiber laminates. The chemistry, physical, and mechanical properties of these polymers are discussed. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 12 TC 34 Z9 34 U1 1 U2 5 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD OCT PY 1991 VL 29 IS 11 BP 1667 EP 1674 DI 10.1002/pola.1991.080291118 PG 8 WC Polymer Science SC Polymer Science GA GF543 UT WOS:A1991GF54300018 ER PT J AU MYNENI, RB MARSHAK, AL KNYAZIKHIN, YV AF MYNENI, RB MARSHAK, AL KNYAZIKHIN, YV TI TRANSPORT-THEORY FOR A LEAF CANOPY OF FINITE-DIMENSIONAL SCATTERING CENTERS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID VEGETATION CANOPIES; REFLECTANCE; MODEL AB A formalism for photon transport in leaf canopies with finite-dimensional scattering centers that cross shade mutually is developed. Starting from first principles, expressions for the interaction cross sections are derived. The problem of illumination by a monodirectional source is studied in detail using a successive collisions approach. A balance equation is formulated in R3 and the interaction between a leaf canopy and the adjacent atmosphere is discussed. Although the details are those relating to a leaf canopy, the formalism is equally applicable to other media where the constituents cross shade mutually such as planetary surfaces, rings and ridged-ice in polar regions, i.e., media that exhibit opposition brightening. C1 UNIV GOTTINGEN,INST BIOKLIMATOL,W-3400 GOTTINGEN,GERMANY. TARTU STATE UNIV,DEPT GEOPHYS,TARTU 202400,ESTONIA,USSR. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,MAIL CODE 974,GREENBELT,MD 20771, USA. RI Marshak, Alexander/D-5671-2012; Myneni, Ranga/F-5129-2012 NR 19 TC 25 Z9 25 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT PY 1991 VL 46 IS 4 BP 259 EP 280 DI 10.1016/0022-4073(91)90091-4 PG 22 WC Optics; Spectroscopy SC Optics; Spectroscopy GA GJ335 UT WOS:A1991GJ33500004 ER PT J AU FIJANY, A BEJCZY, AK AF FIJANY, A BEJCZY, AK TI PARALLEL COMPUTATION OF MANIPULATOR INVERSE DYNAMICS SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB In this article, parallel computation of manipulator inverse dynamics is investigated. A hierarchical graph-based mapping approach is devised to analyze the inherent parallelism in the Newton-Euler formulation at several computational levels, and to derive the features of an abstract architecture for exploitation of parallelism. At each level, a parallel algorithm represents the application of a parallel model of computation that transforms the computation into a graph whose structure defines the features of an abstract architecture, i.e., number of processors, communication structure, etc. Data flow analysis is employed to derive the time lower bound in the computation as well as the sequencing of the abstract architecture. The features of the target architecture are defined by optimization of the abstract architecture to exploit maximum parallelism while minimizing various overheads and architectural complexity. An algorithmically specialized, highly parallel, MIMD-SIMD architecture is designed and implemented that is capable of efficient exploitation of parallelism at several computational levels. The computation time of the Newton-Euler formulation for a 6-degree-of-freedom (dof) general manipulator is measured as 187-mu-s. The increase in computation time for each additional dof is 23-mu-s, which leads to a computation time of less than 500-mu-s, even for a 12-dof redundant arm. RP FIJANY, A (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 42 TC 8 Z9 8 U1 0 U2 0 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 OCT PY 1991 VL 8 IS 5 BP 599 EP 635 DI 10.1002/rob.4620080504 PG 37 WC Robotics SC Robotics GA GH382 UT WOS:A1991GH38200003 ER PT J AU CRANE, CD DUFFY, J CARNAHAN, T AF CRANE, CD DUFFY, J CARNAHAN, T TI A KINEMATIC ANALYSIS OF THE SPACE STATION REMOTE MANIPULATOR SYSTEM (SSRMS) SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB An efficient reverse analysis of three 6-degree-of-freedom (dof) subchains of the 7-dof SSRMS is presented. The first subchain is formed by locking the seventh joint. The second subchain is formed by locking the second joint, while the third subchain is formed by locking the first joint (the grounded joint is counted as the first joint in the chain). There are a maximum of eight different arm configurations in each of the three subchains, and these were determined by employing a computer-efficient algorithm, which required the rooting of only at most quadratic polynomials. The algorithms were implemented, and the SSRMS was employed in an animated environment to perform and practice a number of useful tasks for space station servicing. The locking of the second joint has the advantage in that an operator could, at the outset, choose the orientation of the plane that contains the two longest links (the upper arm and forearm) so as to avoid collisions with obstacles. However, it has the disadvantage that when the second joint angle equals 0-degrees or 180-degrees, the manipulator is in a singularity configuration (a singularity analysis of the SSRMS is presented in a second article). It is interesting to note that this plane can also be oriented by specifying the first joint angle. This has the distinct advantage that the plane can be oriented arbitrarily and, in this way, the singularity is avoided. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CRANE, CD (reprint author), UNIV FLORIDA,DEPT MECH ENGN,CTR INTELLIGENT MACHINES & ROBOTS,GAINESVILLE,FL 32611, USA. NR 6 TC 7 Z9 9 U1 1 U2 5 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 OCT PY 1991 VL 8 IS 5 BP 637 EP 658 DI 10.1002/rob.4620080505 PG 22 WC Robotics SC Robotics GA GH382 UT WOS:A1991GH38200004 ER PT J AU SHEN, HH WRAY, AA AF SHEN, HH WRAY, AA TI STATIONARY TURBULENT CLOSURE VIA THE HOPF FUNCTIONAL-EQUATION SO JOURNAL OF STATISTICAL PHYSICS LA English DT Article DE NAVIER-STOKES TURBULENCE; CLOSURE; GENERATING FUNCTIONAL; HOPF EQUATION ID FLOWS AB Exact closed-form solutions are exhibited for the Hopf equation for stationary incompressible 3D Navier Stokes flow, for the cases of homogeneous forced flow (including a solution with depleted nonlinearity) and inhomogeneous flow with arbitrary boundary conditions. This provides an exact method for computing two- and higher-point moments, given the mean flow. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SHEN, HH (reprint author), STANFORD UNIV,NASA,AMES RES CTR,CTR TURBULENCE RES,STANFORD,CA 94305, USA. NR 18 TC 2 Z9 2 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-4715 J9 J STAT PHYS JI J. Stat. Phys. PD OCT PY 1991 VL 65 IS 1-2 BP 33 EP 52 DI 10.1007/BF01329849 PG 20 WC Physics, Mathematical SC Physics GA GM637 UT WOS:A1991GM63700002 ER PT J AU KALETKA, J TISCHLER, MB VONGRUNHAGEN, W FLETCHER, JW AF KALETKA, J TISCHLER, MB VONGRUNHAGEN, W FLETCHER, JW TI TIME AND FREQUENCY-DOMAIN IDENTIFICATION AND VERIFICATION OF BO-105 DYNAMIC-MODELS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Mathematical models for the dynamics of the DLR BO 105 helicopter are extracted from flight test data using two different approaches: frequency-domain and time-domain identification. Both approaches are reviewed. Results from an extensive data consistency analysis are given. Identifications for 6-degrees-of-freedom (DOF) rigid-body models are presented and compared in detail. The extracted models compare favorably and their prediction capability is demonstrated. Approaches to extend the 6-DOF models are addressed and first results are presented. C1 USA,AVIAT RES & TECHNOL ACT,AMES RES CTR,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA. RP KALETKA, J (reprint author), DFVLR,INST FLUGMECH,BRAUNSCHWEIG,GERMANY. NR 14 TC 2 Z9 2 U1 0 U2 4 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1991 VL 36 IS 4 BP 25 EP 38 PG 14 WC Engineering, Aerospace SC Engineering GA GR647 UT WOS:A1991GR64700003 ER PT J AU BALLIN, MG DALANGSECRETAN, MA AF BALLIN, MG DALANGSECRETAN, MA TI VALIDATION OF THE DYNAMIC-RESPONSE OF A BLADE-ELEMENT UH-60 SIMULATION-MODEL IN HOVERING FLIGHT SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB The dynamic fidelity of an operational blade-element simulation model of the UH-60A helicopter is assessed for the hovering and low-speed flight regimes. Nonparametric frequency-response identification techniques and time-history comparisons are used to determine the validity of vehicle responses. Frequency-domain methods are applied to the model to isolate deficiencies and verify refinements and corrections. A dedicated flight-test program was conducted to provide data used in the analyses. Model deficiencies are also identified by using side-by-side pilot assessments of a motion-based simulation and of a test aircraft. Model refinements are found to improve fidelity significantly in the frequency range of interest to handling-qualities research. The applicability of the model to high-bandwidth flight-control research is also discussed. C1 STERLING FED SYST INC,PALO ALTO,CA. RP BALLIN, MG (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 31 TC 7 Z9 7 U1 0 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1991 VL 36 IS 4 BP 77 EP 88 PG 12 WC Engineering, Aerospace SC Engineering GA GR647 UT WOS:A1991GR64700008 ER PT J AU MULLINS, LD AF MULLINS, LD TI CALCULATING SATELLITE UMBRA PENUMBRA ENTRY AND EXIT POSITIONS AND TIMES SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The problem of calculating Earth satellite entry/exit positions and times through the Earth's umbra and penumbra for elliptical satellite orbits is solved in closed form; i.e., without iteration, by reducing the problem to that of finding the roots of a quartic polynomial in a cartesian coordinate. Typical results from an algorithm constructed from the method are shown. RP MULLINS, LD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 5 TC 9 Z9 16 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1991 VL 39 IS 4 BP 411 EP 422 PG 12 WC Engineering, Aerospace SC Engineering GA GW900 UT WOS:A1991GW90000002 ER PT J AU MCENEANEY, WM MEASE, KD AF MCENEANEY, WM MEASE, KD TI ERROR ANALYSIS FOR A GUIDED MARS LANDING SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This paper presents the methodology and results of a Mars landing error study. Bank maneuvers are used to reduce the landing error due to entry point and atmospheric density errors. The guidance and navigation logic is a derivative of that used for the reentry of the Space Shuttle. Simulations of the guided landing of a biconic vehicle with a maximum L/D of 1.5 show that, using unaided inertial navigation, the approximate bounds on the magnitudes of the downrange and crossrange errors at parachute deployment are 15 km and 1 km, respectively. The limiting error sources are the entry knowledge of downrange and flight path angle and the accelerometer scale factor and bias. The down-range error can be reduced to 5 km if an extended Kalman-filter based navigation logic is used to process the accelerometer data, however, the performance is sensitive to the tuning parameters of the filter. A more robust means of reducing the downrange error is to use ranging relative to either an orbiting vehicle or a vehicle already on the Martian surface, which provides navigation information complementing that derived from the accelerometer data. With range data, the downrange and crossrange errors are both less than 1 km. Similar performance can be achieved with a maximum L/D of 0.5, if the guidance logic is modified so that trajectory corrections are initiated as soon as possible after entry. C1 PRINCETON UNIV,DEPT MECH & AEROSP ENGN,PRINCETON,NJ 08544. CALTECH,JET PROP LAB,NAVIGAT SYST SECT,PASADENA,CA 91109. OI Mease, Kenneth D/0000-0002-5625-8233 NR 10 TC 3 Z9 3 U1 0 U2 4 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1991 VL 39 IS 4 BP 423 EP 445 PG 23 WC Engineering, Aerospace SC Engineering GA GW900 UT WOS:A1991GW90000003 ER PT J AU DESAI, PN BRAUN, RD AF DESAI, PN BRAUN, RD TI MARS PARKING ORBIT SELECTION SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB For a Mars mission, the selection of a parking orbit is greatly influenced by the precession caused by the oblateness of the planet. This affects the departure condition for Earth return, and therefore, the mass required in low-Earth orbit (LEO) for a Mars mission. In this investigation, minimum LEO mass penalties were observed for parking orbits characterized by having near-equatorial inclinations, high eccentricities, and requiring a three-dimensional departure burn. However, because near-equatorial inclination orbits have poor planetary coverage characteristics, they are not desirable from a science viewpoint. To enhance these science requirements along with landing site accessibility, a penalty in mission performance (initial LEO mass) is required. This study shows that this initial LEO mass penalty is reduced for orbits characterized with low to moderate eccentricities, non-equatorial inclinations, and a tangential periapsis arrival and departure burn. This investigation also shows that the use of retrograde orbits (inclinations above 90-degrees) can reduce the penalty in mission peformance. Finally, for a particular mission, the selection of a final Mars parking orbit cannot be based purely on mission performance. A tradeoff between mission performance, science requirements, and landing site accessibility needs to be made. RP DESAI, PN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 15 TC 5 Z9 5 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1991 VL 39 IS 4 BP 447 EP 467 PG 21 WC Engineering, Aerospace SC Engineering GA GW900 UT WOS:A1991GW90000004 ER PT J AU OGBUJI, LUJT SMIALEK, JL AF OGBUJI, LUJT SMIALEK, JL TI EVIDENCE FROM TRANSMISSION ELECTRON-MICROSCOPY FOR AN OXYNITRIDE LAYER IN OXIDIZED SI3N4 SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Letter ID SILICON-NITRIDE; OXIDATION AB Microstructural and energy dispersive spectrometry evidence is produced, from transmission electron microscopy, to show that a silicon oxynitride inner layer is produced by the oxidation of silicon nitride in dry oxygen at 1350-degrees-C, as proposed by Tressler and co-workers. However, details of the microstructures at the oxide/nitride interface do not agree entirely with the rest of the Tressler model for the oxidation of Si3N4 RP OGBUJI, LUJT (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 10 TC 30 Z9 30 U1 0 U2 3 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD OCT PY 1991 VL 138 IS 10 BP L51 EP L53 DI 10.1149/1.2085384 PG 3 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA GJ144 UT WOS:A1991GJ14400002 ER PT J AU OGBUJI, LUJT AF OGBUJI, LUJT TI OXIDATION INSTABILITY OF SIC AND SI3N4 FOLLOWING THERMAL EXCURSIONS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Letter ID GROWN SIO2-FILMS; SILICON-NITRIDE; EXPANSION AB The effect of thermal excursion and thermal cycling on the oxidation stability of chemical vapor-deposited (CVD) SiC and Si3N4 was studied at 1350-degrees-C. Thermal cycling alone produced no noticeable change in oxidation kinetics. However, transmission electron microscopy showed that oxide scales grown in cycles consist of alternating layers of SiO2 and Si2N2O. When the oxidation of CVD SiC or Si3N4 at 1350-degrees-C was interrupted with a 1.5-h annealing in Ar at 1500-degrees-C, the kinetics of reoxidation at 1350-degrees-C were found to be drastically increased. The SiC and Si3N4 then oxidized essentially at the same rate, which is over 50 times the preannealing rate, and comparable to the expected oxidation rate of these materials at 1500-degrees-C. This loss of passivity induced by excursion to higher temperature has also been reported for Si, and is considered an intrinsic instability in materials that oxidize to silica. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 19 TC 7 Z9 7 U1 1 U2 1 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 EI 1945-7111 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD OCT PY 1991 VL 138 IS 10 BP L53 EP L56 DI 10.1149/1.2085385 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA GJ144 UT WOS:A1991GJ14400003 ER PT J AU LOCK, JA HOVENAC, EA AF LOCK, JA HOVENAC, EA TI INTERNAL CAUSTIC STRUCTURE OF ILLUMINATED LIQUID DROPLETS SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID CRITICAL-ANGLE SCATTERING; LASER-INDUCED BREAKDOWN; SINGLE WATER DROPLET; DIELECTRIC SPHERES; MIE SCATTERING; ELECTROMAGNETIC ENERGY; FLUORESCENT SCATTERING; SPHERICAL-PARTICLES; ABSORPTION CENTERS; IRRADIATED SPHERES AB The internal electric field of an illuminated liquid droplet is studied in detail with the use of both wave theory and ray theory. The internal field attains its maximum values on the caustics within the droplet. Ray theory is used to determine the equations of these caustics and the density of rays on them. The Debye-series expansion of the interior-field Mie amplitudes is used to calculate the wave-theory version of these caustics. The physical interpretation of the sources of stimulated Raman scattering and fluorescence emission within a liquid droplet is then given. C1 NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP LOCK, JA (reprint author), CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115, USA. NR 52 TC 41 Z9 41 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 OCT PY 1991 VL 8 IS 10 BP 1541 EP 1553 DI 10.1364/JOSAA.8.001541 PG 13 WC Optics SC Optics GA GH718 UT WOS:A1991GH71800003 ER PT J AU WINKER, DM AF WINKER, DM TI EFFECT OF A FINITE OUTER SCALE ON THE ZERNIKE DECOMPOSITION OF ATMOSPHERIC OPTICAL TURBULENCE SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID POLYNOMIALS; PROPAGATION AB Phase distortions in optical systems induced by atmospheric turbulence are investigated with the use of Zernike polynomial decompositions. An analytic solution for the variances of the Zernike coefficients is found for the case of Kolmogorov turbulence with a finite outer-scale length. It is shown that the effect of finite outer scale is to attenuate low-order Zernike components, even when the outer-scale length is much larger than the optical aperture. Effects are investigated for constant outer-scale size and for height-dependent outer scales. It is found that seeing effects on large telescopes are dependent more on the magnitude of the outer scale than on the shape of the outer-scale vertical profile. RP WINKER, DM (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 16 TC 85 Z9 91 U1 0 U2 1 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 OCT PY 1991 VL 8 IS 10 BP 1568 EP 1573 DI 10.1364/JOSAA.8.001568 PG 6 WC Optics SC Optics GA GH718 UT WOS:A1991GH71800006 ER PT J AU NOEVER, DA AF NOEVER, DA TI FRACTAL DYNAMICS OF BIOCONVECTIVE PATTERNS SO JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN LA English DT Article ID MICROORGANISMS; GROWTH; MODEL; FLUID AB Biologically generated cellular patterns, sometimes called bioconvective patterns, are found to cluster into aggregates which follow fractal growth dynamics akin to diffusion-limited aggregation (DLA) models. The pattern formed is self-similar with fractal dimension of 1.66 +/- 0.038. Bioconvective DLA branching results from thermal roughening which shifts the balance between ordering viscous forces and disordering cell motility and random diffusion. The phase diagram for pattern morphology includes DLA, boundary spokes, random clusters and reverse clusters. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES-76,HUNTSVILLE,AL 35812, USA. NR 23 TC 3 Z9 3 U1 0 U2 1 PU PHYSICAL SOCIETY JAPAN KIKAI-SHINKO BUILDING PI TOKYO PA 3-5-8 SHIBA-KOEN MINATO-KU, TOKYO 105, JAPAN SN 0031-9015 J9 J PHYS SOC JPN JI J. Phys. Soc. Jpn. PD OCT PY 1991 VL 60 IS 10 BP 3573 EP 3578 DI 10.1143/JPSJ.60.3573 PG 6 WC Physics, Multidisciplinary SC Physics GA GT499 UT WOS:A1991GT49900045 ER PT J AU Rochelle, WC Ting, PC Bouslog, SA Mueller, SR Colovin, JE Curry, DM Scott, CD AF Rochelle, W. C. Ting, P. C. Bouslog, S. A. Mueller, S. R. Colovin, J. E., Jr. Curry, D. M. Scott, C. D. TI Aeroassist Flight Experiment Heating-Rate Sensitivity Study SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A description of the sensitivities associated with predicting the aerothermodynamic environment on the aeroassist flight experiment (AFE) aerobrake is presented. The objective of the study was to evaluate the sensitivity of heating-rate predictions to parametric uncertainties and to differences in methodology. Principal areas of sensitivity which were evaluated include trajectories, angle of attack, thermal protection system (TPS) tile catalycity, nose radius/surface pressure distributions, and viscous interactions. Other areas of concern include thermodynamic/transport properties, wall-temperature variations, and gas cap radiation-prediction methods. The relative importance of each of these effects on AFE heating rates using the boundary-layer integral matrix procedure (BLIMP) program is discussed, and sample results for several of the sensitivity parameters are presented. The most important contribution to the heating rate was determined to be the catalytic wall recombination coefficient, with about a 10 W/cm(2) or 25% deviation from the standard. C1 [Rochelle, W. C.; Ting, P. C.; Bouslog, S. A.; Mueller, S. R.; Colovin, J. E., Jr.] Lockheed Engn & Sci Co, Houston, TX 77058 USA. [Curry, D. M.; Scott, C. D.] NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Rochelle, WC (reprint author), Lockheed Engn & Sci Co, Houston, TX 77058 USA. NR 25 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1991 VL 5 IS 4 BP 456 EP 462 DI 10.2514/3.287 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZX UT WOS:000208449400002 ER PT J AU Sharma, SP Schwenke, DW AF Sharma, Surendra P. Schwenke, David W. TI Rate Parameters for Coupled Rotation-Vibration-Dissociation Phenomena in H-2 SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A theoretical study of the effects of molecular rotation on coupled vibration-dissociation phenomena for H-2, undergoing a nonequilibrium relaxation in a heating and cooling environment, is reported. The rate coefficients for the collisional bound-bound and bound-free transitions have been calculated using a quasi-classical trajectory method. These state-to-state transition rates were fed into the master equation, which was numerically solved to determine the rotational and vibrational population densities as well as the bulk thermodynamic properties. Our results show that a) the vibrational transition rates of H-2 increase monotonically with the vibrational levels, faster than the Landau-Teller model, b) the rotation of the molecules helps relax the low vibrational levels, serves as a temporary storage of vibrational energy during the relaxation, and thereby delays the dissociation process, c) the dissociation and recombination rates can be approximated within an order of magnitude using equilibrium formulations and Park's two-temperature model for temperature averaging, d) lower vibrational levels tend to over-relax, and e) the average energy loss due to the dissociation is about 80-90% of the dissociation energy. C1 [Sharma, Surendra P.; Schwenke, David W.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sharma, SP (reprint author), NASA, Ames Res Ctr, Mail Stop 230-2, Moffett Field, CA 94035 USA. RI schwenke, david/I-3564-2013 NR 15 TC 7 Z9 7 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1991 VL 5 IS 4 BP 469 EP 480 DI 10.2514/3.289 PG 12 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZX UT WOS:000208449400004 ER PT J AU Siegel, R AF Siegel, Robert TI Transient Cooling of a Square Region of Radiating Medium SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A time-accurate numerical solution was carried out for transient radiative cooling of a gray emitting and absorbing medium in a square two-dimensional region. The integro-differential energy equation for transient temperature distributions was solved in two stages. At each time increment, the local radiative source term was obtained by numerical integration of the temperature field using two-dimensional Gaussian integration over rectangular subregions. Then the differential portion of the equation was integrated forward in time by use of the local first and second time derivatives. The results were compared with available limiting cases, and excellent agreement was obtained. Transient results are given for a wide range of optical thicknesses of the region. Optimum transient cooling is obtained when the optical side length is about 4. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Siegel, R (reprint author), NASA, Lewis Res Ctr, Mail Stop 5-9, Cleveland, OH 44135 USA. NR 12 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1991 VL 5 IS 4 BP 495 EP 501 DI 10.2514/3.292 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZX UT WOS:000208449400007 ER PT J AU Dechaumphai, P AF Dechaumphai, Pramote TI Evaluation of an Adaptive Unstructured Remeshing Technique for Integrated Fluid-Thermal-Structural Analysis SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB An adaptive unstructured remeshing technique is evaluated for integrating fluid-thermal-structural analysis. The technique is combined with the finite element method to solve 1) the Navier-Stokes equations for high-speed compressible flow, 2) the energy equation for the structure's thermal response, and 3) the quasistatic equilibrium equations for the structural response. The remeshing technique and the analysis procedure are described. The effectiveness of the approach is evaluated with two application studies. The flow analysis of Mach 8 shock-shock interference on a 3-in.-diam cylinder is used as the first application to demonstrate the capability of the remeshing technique to capture the physics features of a complex high-speed flow. The applicability of the approach for the thermal and structural analyses of the structure is evaluated in the second application of a 0.25-in.-diam convectively cooled leading edge subjected to intense aerodynamic heating. The adaptive unstructured remeshing procedure and finite element solution algorithms combine to yield increased accuracy and efficiency over standard structured meshes. C1 [Dechaumphai, Pramote] NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 16 TC 4 Z9 5 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1991 VL 5 IS 4 BP 599 EP 606 DI 10.2514/3.305 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZX UT WOS:000208449400020 ER PT J AU Lin, CS Hasan, MM AF Lin, C. S. Hasan, M. M. TI Vapor Condensation on Liquid Surface Due to Laminar Jet-Induced Mixing SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The effects of system parameters on the interface condensation rate in a laminar jet-induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a subcooled jet discharge from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The steady-state conservation equations in nondimensional form are solved by a finite-difference method for various system parameters including liquid height to tank diameter ratio (HID), tank to jet diameter ratio (D/d), liquid outflow to jet area ratio (A(out)/A(j)), and a heat leak parameter (Nh) which characterizes the uniform wall heat-flux. It is found that the average condensation Stanton number ((St) over bar (c)) is decreasing with increasing H/D, D/d, and Nh. For small Nh, (St) over bar (c), is nearly independent of A(out)/A(j). For Re-j <= 600, (St) over bar (c) is essentially equal to (d/D)(2) if (D/d) >= 20 and Nh << 1. C1 [Lin, C. S.] NASA, Lewis Res Ctr, Analex Corp, 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 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1991 VL 5 IS 4 BP 607 EP 612 DI 10.2514/3.306 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZX UT WOS:000208449400021 ER PT J AU JANG, HM EKATERINARIS, JA PLATZER, MF CEBECI, T AF JANG, HM EKATERINARIS, JA PLATZER, MF CEBECI, T TI ESSENTIAL INGREDIENTS FOR THE COMPUTATION OF STEADY AND UNSTEADY BLADE BOUNDARY-LAYERS SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 35TH INTERNATIONAL GAS TURBINE AND AEROENGINE CONGRESS AND EXPOSITION CY JUN 11-14, 1990 CL BRUSSELS, BELGIUM ID EQUATIONS AB Two methods are described for calculating pressure distributions and boundary layers on blades subjected to low Reynolds numbers and ramp-type motion. The first is based on an interactive scheme in which the inviscid flow is computed by a panel method and the boundary layer flow by an inverse method that makes use of the Hilbert integral to couple the solutions of the inviscid and viscous flow equations. The second method is based on the solution of the compressible Navier-Stokes equations with an embedded grid technique that permits accurate calculation of boundary layer flows. Studies for the Eppler-387 and NACA-0012 airfoils indicate that both methods can be used to calculate the behavior of unsteady blade boundary layers at low Reynolds numbers provided that the location of transition is computed with the e(n) method and the transitional region is modeled properly. C1 UNIV MICHIGAN,DEPT MECH ENGN,ANN ARBOR,MI 48109. NAVY,NASA,JOINT INST AERONAUT,MONTEREY,CA 93943. USN,NAVAL POSTGRAD SCH,DEPT AERONAUT & ASTRONAUT,MONTEREY,CA 93943. CALIF STATE UNIV LONG BEACH,DEPT AEROSP ENGN,LONG BEACH,CA 90840. NR 23 TC 1 Z9 1 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 OCT PY 1991 VL 113 IS 4 BP 608 EP 616 DI 10.1115/1.2929124 PG 9 WC Engineering, Mechanical SC Engineering GA HP741 UT WOS:A1991HP74100009 ER PT J AU GARDNER, SD HOFLUND, GB SCHRYER, DR SCHRYER, J UPCHURCH, BT KIELIN, EJ AF GARDNER, SD HOFLUND, GB SCHRYER, DR SCHRYER, J UPCHURCH, BT KIELIN, EJ TI CATALYTIC BEHAVIOR OF NOBLE-METAL REDUCIBLE OXIDE MATERIALS FOR LOW-TEMPERATURE CO OXIDATION .1. COMPARISON OF CATALYST PERFORMANCE SO LANGMUIR LA English DT Article ID CARBON-MONOXIDE; MANGANESE-DIOXIDE; GOLD CATALYSTS; PRETREATMENT; OXYGEN AB MnOx, Ag/MnOx, Au/MnOx, Cu/MnOx, Pd/MnOx, Pt/MnOx, Ru/MnOx, Au/CeOx, and Au/Fe2O3 were synthesized and tested for CO oxidation activity in low concentrations of stoichiometric CO and O2 at 30-75-degrees-C. Catalytic activity was measured for periods as long as 18 000 min. At 75-degrees Au/MnOx is most active sustaining nearly 100% CO conversion for 10 000 min. It also retains high activity at 50 and 30-degrees-C with negligible decay in activity. Other catalysts including Au/CeOx and Au/Fe2O3 also perform well. The Cu/MnOx exhibits a high initial activity which decays rapidly. After the decay period the activity remains very stable, making Cu/MnOx a potential candidate for long-term applications such as CO2 lasers in space. C1 UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 27 TC 130 Z9 134 U1 2 U2 22 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD OCT PY 1991 VL 7 IS 10 BP 2135 EP 2139 DI 10.1021/la00058a027 PG 5 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA GL794 UT WOS:A1991GL79400027 ER PT J AU GARDNER, SD HOFLUND, GB DAVIDSON, MR LAITINEN, HA SCHRYER, DR UPCHURCH, BT AF GARDNER, SD HOFLUND, GB DAVIDSON, MR LAITINEN, HA SCHRYER, DR UPCHURCH, BT TI CATALYTIC BEHAVIOR OF NOBLE-METAL REDUCIBLE OXIDE MATERIALS FOR LOW-TEMPERATURE CO OXIDATION .2. SURFACE CHARACTERIZATION OF AU/MNOX SO LANGMUIR LA English DT Article ID BINDING-ENERGY SHIFTS; SUPPORTED GOLD; CARBON-MONOXIDE; MANGANESE; SPECTROSCOPY; PRETREATMENT; REACTIVITY; DISPERSION; PARTICLES AB Au/MnOx and MnOx surfaces used for low-temperature CO oxidation have been characterized by using ion scattering spectroscopy (ISS), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS or ESCA) before and after pretreatment in He at 55-degrees-C. The pretreatment enriches the surface of Au/MnOx with O and Au and decreases the surface O concentration on MnOx. It also causes complex changes in the chemical state of the Mn. C1 UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611. UNIV FLORIDA,DEPT CHEM,GAINESVILLE,FL 32611. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RI Davidson, Mark/C-1135-2009 NR 38 TC 66 Z9 66 U1 0 U2 11 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD OCT PY 1991 VL 7 IS 10 BP 2140 EP 2145 DI 10.1021/la00058a028 PG 6 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA GL794 UT WOS:A1991GL79400028 ER PT J AU RAU, GH HOPKINS, TL TORRES, JJ AF RAU, GH HOPKINS, TL TORRES, JJ TI N-15/N-14 AND C-13/C-12 IN WEDDELL SEA INVERTEBRATES - IMPLICATIONS FOR FEEDING DIVERSITY SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article ID KRILL EUPHAUSIA-SUPERBA; ANTARCTIC KRILL; FOOD WEB; BEHAVIOR; ICE; SIPHONOPHORES; MARINE; OCEAN; N-15 AB Biomass delta-C-13, delta-N-15, and C/N were measured for each of 29 taxa of pelagic invertebrates sampled from the Weddell Sea in March 1986. The delta-C-13 values of these animals ranged from -33.2 to -23.9 parts per thousand, and a significant negative logarithmic relationship was observed between these values and biomass C/N. This implies that the relative proportion of carbon-rich C-13-depleted lipid in these animals significantly influenced the delta-C-13 of their bulk biomass. No such relationship with C/N is evident with respect to biomass delta-N-15 where values ranged from -1.2 to +7.3 parts per thousand. This spread of values reflects a wide diversity of food sources and trophic positions among the species analyzed. Isotopic abundances within krill Euphausia superba varied with individual length, apparently reflecting dietary changes during growth. Isotope values within E superba from the Weddell Sea overlap those of krill from other Southern Ocean locations in the Scotia Sea/Drake Passage, the Ross Sea, and Prydz Bay, Antarctica, C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV S FLORIDA, DEPT MARINE SCI, ST PETERSBURG, FL 33701 USA. RP RAU, GH (reprint author), UNIV CALIF SANTA CRUZ, INST MARINE SCI, SANTA CRUZ, CA 95064 USA. NR 33 TC 70 Z9 72 U1 0 U2 9 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0171-8630 J9 MAR ECOL PROG SER JI Mar. Ecol.-Prog. Ser. PD OCT PY 1991 VL 77 IS 1 BP 1 EP 6 DI 10.3354/meps077001 PG 6 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA GP098 UT WOS:A1991GP09800001 ER PT J AU CHIANG, YM MESSNER, RP TERWILLIGER, CD BEHRENDT, DR AF CHIANG, YM MESSNER, RP TERWILLIGER, CD BEHRENDT, DR TI REACTION-FORMED SILICON-CARBIDE SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article; Proceedings Paper CT SYMP OF THE AMERICAN SOC OF METALS INTERNATIONAL MATERIALS WEEK : INNOVATIVE INORGANIC COMPOSITES CY OCT 08-11, 1990 CL DETROIT, MI SP AMER SOC METALS ID ZIRCON-ALUMINA MIXTURES; MECHANICAL-PROPERTIES; COMPOSITES; CERAMICS; MULLITE; SYSTEM AB The reaction bonding of silicon carbide (SiC) typifies liquid-solid reaction processes for the synthesis of refractory ceramic composites. These processes have particular advantages over conventional sintering and hot-pressing techniques in their lower processing temperatures, shorter times and near-net shape fabrication capabilities. Two particular modifications that we have employed in order to improve the mechanical properties and the ultimate use temperature of reaction-bonded SiC are the use of microporous carbon pre-forms derived from polyfurfural alcohol for refinement of microstructure, and the use of alloyed melts in order to replace detrimental residual silicon with a refractory silicide, The control of reaction rate is always a kev issue in reaction processing. We have studied the kinetics and mechanisms of the liquid Si-C reaction. Experiments on carbon fibers and plates show that the principle mechanism is one of solution-reprecipitation. There is an increased solubility of carbon at very fine SiC particles formed by the spallation of the misfitting carbide from the carbon interface. leading to reprecipitation of SiC at defective seed crystals. Molybdenum and boron at low concentrations (3.2 mol.%) have little effect on reaction kinetics, Whereas aluminum is able to impede the reaction through the formation of an inter-facial carbide layer. C1 NATL AERONAUT & SPACE ADM,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHIANG, YM (reprint author), MIT,DEPT MAT SCI & ENGN,CAMBRIDGE,MA 02139, USA. RI Demetry, Chrysanthe/F-7641-2015 NR 48 TC 109 Z9 119 U1 5 U2 41 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 OCT 1 PY 1991 VL 144 BP 63 EP 74 DI 10.1016/0921-5093(91)90210-E PG 12 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA GN778 UT WOS:A1991GN77800008 ER PT J AU PIASCIK, RS GANGLOFF, RP AF PIASCIK, RS GANGLOFF, RP TI ENVIRONMENTAL FATIGUE OF AN AL-LI-CU ALLOY .1. INTRINSIC CRACK-PROPAGATION KINETICS IN HYDROGENOUS ENVIRONMENTS SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID ALUMINUM-LITHIUM ALLOYS; CORROSION-FATIGUE; CRYOGENIC TOUGHNESS; BEHAVIOR; GROWTH; MAGNESIUM; FRACTURE; RESISTANCE AB Deleterious environmental effects on steady-state, intrinsic fatigue crack propagation (FCP) rates (da/dN) in peak-aged Al-Li-Cu alloy 2090 are established by electrical potential monitoring of short cracks with programmed constant DELTA-K and K(max) loading. Such rates are equally unaffected by vacuum, purified helium, and oxygen but are accelerated in order of decreasing effectiveness by aqueous 1 pct NaCl with anodic polarization, pure water vapor, moist air, and NaCl with cathodic polarization. While da/dN depend on DELTA-K4.0 for the inert gases, water vapor and chloride induce multiple power laws and a transition growth rate "plateau." Environmental effects are strongest at low DELTA-K. Crack tip damage is ascribed to hydrogen embrittlement because of accelerated da/dN due to parts-per-million (ppm) levels of H2O without condensation, impeded molecular flow model predictions of the measured water vapor pressure dependence of da/dN as affected by mean crack opening, the lack of an effect of film-forming O2, the likelihood for crack tip hydrogen production in NaCl, and the environmental and DELTA-K-process zone volume dependencies of the microscopic cracking modes. For NaCl, growth rates decrease with decreasing loading frequency, with the addition of passivating Li2CO3 and upon cathodic polarization. These variables increase crack surface film stability to reduce hydrogen entry efficiency. Small crack effects are not observed for 2090; such cracks do not grow at abnormally high rates in single grains or in NaCl and are not arrested at grain boundaries. The hydrogen environmental FCP resistance of 2090 is similar to other 2000 series alloys and is better than 7075. C1 UNIV VIRGINIA,DEPT MAT SCI,CHARLOTTESVILLE,VA 22903. RP PIASCIK, RS (reprint author), NASA,LANGLEY RES CTR,MECH MAT BRANCH,HAMPTON,VA 23665, USA. NR 86 TC 66 Z9 67 U1 1 U2 8 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD OCT PY 1991 VL 22 IS 10 BP 2415 EP 2428 DI 10.1007/BF02665008 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA GJ165 UT WOS:A1991GJ16500026 ER PT J AU MISRA, AK AF MISRA, AK TI PRELIMINARY STUDIES ON NIAL NB2BE17 REACTION AND EFFECTIVENESS OF BEO AS AN INTERFACIAL REACTION BARRIER SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Note RP MISRA, AK (reprint author), SVERDRUP TECHNOL INC,NASA LEWIS RES CTR GRP,CLEVELAND,OH 44135, USA. NR 7 TC 6 Z9 6 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD OCT PY 1991 VL 22 IS 10 BP 2535 EP 2538 DI 10.1007/BF02665019 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA GJ165 UT WOS:A1991GJ16500037 ER PT J AU WU, KW WICKRAMASINGHE, DT AF WU, KW WICKRAMASINGHE, DT TI MAGNETIC-MOMENT DISTRIBUTION OF MAGNETIC CATACLYSMIC VARIABLES SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID WHITE-DWARF MASSES; DISK ACCRETION; NEUTRON STARS; POLARIZED RADIATION; INTERMEDIATE POLARS; EX HYDRAE; EVOLUTION; BINARIES; SPECTROSCOPY; EMISSION AB We have presented a simulation study of the relative numbers of the AM Herculis binaries and the intermediate polars as a function of the orbital period using random variables subject to suitable constraints to describe the various parameters. We show that the observations can be matched by a single distribution in magnetic moment mu, that is, Gaussian in logarithm space with = 0.7 +/- 0.3. For such an ensemble the intermediate polars are distributed in the log(P(orb)) - log(P(s)) diagram about the critical disc line but with a larger scatter than observed. C1 AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 2601,AUSTRALIA. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP WU, KW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 45 TC 11 Z9 11 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 1 PY 1991 VL 252 IS 3 BP 386 EP 393 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH338 UT WOS:A1991GH33800008 ER PT J AU ALLEN, DJ DOUGLASS, AR ROOD, RB GUTHRIE, PD AF ALLEN, DJ DOUGLASS, AR ROOD, RB GUTHRIE, PD TI APPLICATION OF A MONOTONIC UPSTREAM-BIASED TRANSPORT SCHEME TO 3-DIMENSIONAL CONSTITUENT TRANSPORT CALCULATIONS SO MONTHLY WEATHER REVIEW LA English DT Article ID CONSERVATIVE DIFFERENCE SCHEME; WINTER POLAR STRATOSPHERES; HYDROGEN-CHLORIDE; DENITRIFICATION; SIMULATION AB The application of van Leer's scheme, a monotonic, upstream-biased differencing scheme, to three-dimensional constituent transport calculations is shown. The major disadvantage of the scheme is shown to be a self-limiting diffusion. A major advantage of the scheme is shown to be its ability to maintain constituent correlations. The scheme is adapted for a spherical coordinate system with a hybrid sigma-pressure coordinate in the vertical. Special consideration is given to cross-polar flow. The vertical wind calculation is shown to be extremely sensitive to the method of calculating the divergence. This sensitivity implies that a vertical wind formulation consistent with the transport scheme is essential for accurate transport calculations. The computational savings of the time-splitting method used to solve this equation are shown. Finally, the capabilities of this scheme are illustrated by an ozone transport and chemistry model simulation. C1 NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. APPL RES CORP, LANDOVER, MD USA. RI Allen, Dale/F-7168-2010; Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Allen, Dale/0000-0003-3305-9669; Rood, Richard/0000-0002-2310-4262 NR 23 TC 61 Z9 61 U1 2 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 EI 1520-0493 J9 MON WEATHER REV JI Mon. Weather Rev. PD OCT PY 1991 VL 119 IS 10 BP 2456 EP 2464 DI 10.1175/1520-0493(1991)119<2456:AOAMUB>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GL879 UT WOS:A1991GL87900007 ER PT J AU PERRY, ME BROOKS, NH CONTENT, DA HULSE, RA MAHDAVI, MA MOOS, HW AF PERRY, ME BROOKS, NH CONTENT, DA HULSE, RA MAHDAVI, MA MOOS, HW TI IMPURITY TRANSPORT DURING THE H-MODE IN DIII-D SO NUCLEAR FUSION LA English DT Article ID ALCATOR-C TOKAMAK; ENERGY CONFINEMENT; DISCHARGES; PLASMAS; INJECTION; BEHAVIOR; PROFILES; ACCUMULATION; RADIATION AB In H-mode plasmas in DIII-D, large modulations in spectroscopically measured impurity densities have been observed during shots with giant edge localized modes (ELMs). These spectral modulations have been analysed with the MIST impurity transport code. This analysis indicates that impurities are alternately flowing towards the plasma centre and then away from it. This alternating flow is correlated with ELM produced changes in the electron density. The electron density oscillations are extreme, causing the density profile to switch from hollow (just before an ELM) to centrally peaked (just after an ELM). Neoclassical convection, dependent on ion density gradients, causes impurities to concentrate most heavily where the electron density is largest and can explain the modulating impurity behaviour. Anomalous diffusion, D congruent-to 1.0 x 10(4) cm2/s, reduces the degree of impurity peaking. As the plasma current increases, the increase in hollowness of electron density profiles can account for the observed decrease in central impurity accumulation. Transport of cobalt, injected by laser ablation, has also been studied; cobalt transport variations are consistent with the ELM induced changes seen in intrinsic impurity transport. The transport results may be consistent with neoclassical impurity convective fluxes and suggest that impurity accumulation in tokamaks will occur unless the electron density profile is flat or particle confinement is low. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,34TH & N CHARLES,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. PRINCETON UNIV,PLASMA PHYS LAB,PRINCETON,NJ 08543. RP PERRY, ME (reprint author), GEN ATOM CO,SAN DIEGO,CA 92138, USA. RI Perry, Mark/B-8870-2016 OI Perry, Mark/0000-0003-1600-6856 NR 50 TC 24 Z9 24 U1 1 U2 1 PU INT ATOMIC ENERGY AGENCY PI VIENNA PA WAGRAMERSTRASSE 5 PO BOX 100, A-1400 VIENNA, AUSTRIA SN 0029-5515 J9 NUCL FUSION JI Nucl. Fusion PD OCT PY 1991 VL 31 IS 10 BP 1859 EP 1875 DI 10.1088/0029-5515/31/10/005 PG 17 WC Physics, Fluids & Plasmas SC Physics GA GP406 UT WOS:A1991GP40600005 ER PT J AU OWENS, A NOLAN, T GEHRELS, N SMITH, G AF OWENS, A NOLAN, T GEHRELS, N SMITH, G TI THE GROUND SUPPORT EQUIPMENT FOR THE TRANSIENT GAMMA-RAY SPECTROMETER SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article AB We describe the function and implementation of the ground support equipment (GSE) for the transient gamma-ray spectrometer (TGRS), to be flown on-board the WIND spacecraft. A particularly novel feature of the system is that it was assembled almost entirely from commercially available, off-the-shelf components (including software), offering simplicity, portability, reliability and low cost. It was designed so that nearly every aspect of data accumulation, instrument verification, and analysis can be carried out by the GSE, which alleviates the necessity of a mainframe computer for all but the most comprehensive of data processing. For example, the bulk of the spectral analysis can be carried out using a commercially available, PC based PHA/MCA analysis package. Data products are archived directly onto a removable media optical disk drive, providing more than 20 days storage per disk at the nominal telemetry bit rate of approximately 400 bps. Data packets are made available for distribution over a local area network based on thin-wire Ethernet. RP OWENS, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012 NR 4 TC 0 Z9 0 U1 0 U2 0 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 OCT 1 PY 1991 VL 307 IS 2-3 BP 420 EP 424 DI 10.1016/0168-9002(91)90212-9 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA GJ748 UT WOS:A1991GJ74800037 ER PT J AU SAKURAI, H RAMSEY, BD WEISSKOPF, MC AF SAKURAI, H RAMSEY, BD WEISSKOPF, MC TI HIGH-PRESSURE XENON PROPORTIONAL COUNTER UP TO 10 ATM SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article AB The characteristics of a conventional cylindrical geometry proportional counter filled with high pressure xenon gas up to 10 atm were investigated for use as a detector in hard X-ray astronomy. With a 2% methane gas mixture the energy resolutions at 10 atm were 9.8% and 7.3% for 22 and 60 keV X-rays, respectively. The corresponding resolutions at 1 atm were 7.7% and 5.1%. From calculations of the Townsend ionization coefficient it is shown that proportional counters at high pressure operate at weaker reduced electric field than low pressure counters. It is suggested that this is the fundamental reason for the degradation of resolution observed with increasing pressure. RP SAKURAI, H (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 15 TC 14 Z9 14 U1 1 U2 3 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 OCT 1 PY 1991 VL 307 IS 2-3 BP 504 EP 511 DI 10.1016/0168-9002(91)90224-E PG 8 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA GJ748 UT WOS:A1991GJ74800049 ER PT J AU HUNTER, SD AF HUNTER, SD TI CALIBRATION AND ADJUSTMENT OF THE EGRET COINCIDENCE TIME-OF-FLIGHT SYSTEM SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article AB The coincidence/time-of-flight system of the energetic gamma ray experiment telescope (EGRET) on NASA's Gamma Ray Observatory (GRO) consists of two layers of sixteen scintillator tiles. These tiles are paired into 96 coincidence telescopes. Valid coincidence and time-of-flight values (indicating downward moving particles) from one of these telescopes are two of the requirements for an EGRET event trigger. To maximize up-down discrimination, variations in the mean timing value of the telescopes must be minimized. The timing values of the 96 telescopes are not independent, hence they cannot be individually adjusted to calibrate the system. An iterative approach was devised to determine adjustments to the length of the photomultiplier signal cables. These adjustments were made directly in units of time using a time domain reflectometry technique, by timing the reflection of a fast pulse from the unterminated end of the cable, and observing the change in signal propagation time as the length of the cable was shortened. Two constant fraction discriminators, a time-to-amplitude converter and a pulse height analyzer were used for these measurements. Using this direct time measuring approach, the timing values for the 96 EGRET coincidence/time-of-flight telescopes were adjusted with an FWHM variation of less than 450 ps (+/- 1 TOF timing channel). RP HUNTER, SD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Hunter, Stanley/D-2942-2012 NR 4 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD OCT 1 PY 1991 VL 307 IS 2-3 BP 520 EP 525 DI 10.1016/0168-9002(91)90226-G PG 6 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA GJ748 UT WOS:A1991GJ74800051 ER PT J AU SHOLTIS, JA HUFF, DA GRAY, LB KLUG, NP WINCHESTER, RO AF SHOLTIS, JA HUFF, DA GRAY, LB KLUG, NP WINCHESTER, RO TI TECHNICAL NOTE - THE INTERAGENCY NUCLEAR SAFETY REVIEW PANELS EVALUATION OF THE ULYSSES SPACE MISSION SO NUCLEAR SAFETY LA English DT Note AB The October 1990 launch and deployment of the nuclear-powered Ulysses spacecraft from the Space Shuttle Discovery culminated an extensive safety review and evaluation effort by the Interagency Nuclear Safety Review Panel (INSRP). After more than a year of detailed independent review, study, and analysis, the INSRP prepared a Safety Evaluation Report (SER) on the Ulysses mission in accordance with Presidential Directive/National Security Council Memorandum 25. The SER, which included a review of the Ulysses Final Safety Analysis Report (FSAR) and an independent characterization of the mission risks, was used by the National Aeronautics and Space Administration (NASA) in its decision to request launch approval as well as by the Executive Office of the President in arriving at a launch decision based on risk-benefit considerations. This paper provides an overview of the Ulysses mission and the conduct, as well as results, of the INSRP evaluation. Although the mission risk determined by the INSRP in the SER was higher than that characterized by the Ulysses project in the FSAR, both reports indicated that the radiological risks were relatively small. In the final analysis, the SER proved to be supportive of a positive launch decision. The INSRP evaluation process has demonstrated its effectiveness numerous times since the 1960s. In every case it has provided the essential ingredients and perspective to permit an informed launch decision at the highest level of our government. C1 US DOE,WASHINGTON,DC 20585. NATL AERONAUT & SPACE ADM,WASHINGTON,DC. NR 11 TC 1 Z9 1 U1 0 U2 1 PU US GOVERNMENT PRINTING OFFICE PI WASHINGTON PA SUPT OF DOCUMENTS, WASHINGTON, DC 20402-9325 SN 0029-5604 J9 NUCL SAFETY JI Nucl. Saf. PD OCT-DEC PY 1991 VL 32 IS 4 BP 494 EP 501 PG 8 WC Environmental Sciences; Nuclear Science & Technology SC Environmental Sciences & Ecology; Nuclear Science & Technology GA HW450 UT WOS:A1991HW45000003 ER PT J AU SINGH, DJ KUMAR, A TIWARI, SN AF SINGH, DJ KUMAR, A TIWARI, SN TI NUMERICAL-SIMULATION OF SHOCK IMPINGEMENT ON BLUNT COWL LIP IN VISCOUS HYPERSONIC FLOWS SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article AB The effect of shock impingement on the blunt leading edge of the cowl of a scramjet engine is investigated numerically. The flow-field is calculated by solving the full Navier-Stokes equations using the finite-volume, flux-splitting technique of van Leer. To resolve the finer details of the flow structure as well as to predict the surface heat transfer accurately, an adaptive-grid technique is used. The downstream effects are calculated by solving the thin-layer Navier-Stokes equations suitably modified for marching in space and iterating locally in time to steady-state solution at each spatial station. Results are compared with the available experimental and numerical results. C1 NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665. OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529. RP SINGH, DJ (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 23 TC 2 Z9 2 U1 1 U2 1 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7782 J9 NUMER HEAT TR A-APPL JI Numer. Heat Tranf. A-Appl. PD OCT-NOV PY 1991 VL 20 IS 3 BP 329 EP 344 DI 10.1080/10407789108944825 PG 16 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA GM106 UT WOS:A1991GM10600005 ER PT J AU SMITH, AT WALKUP, JF AF SMITH, AT WALKUP, JF TI OPTICAL IMPLEMENTATIONS OF THE ALTERNATING PROJECTION NEURAL NETWORK SO OPTICAL ENGINEERING LA English DT Article DE NEURAL NETWORKS; PARALLEL PROCESSING; INCOHERENT LIGHT; SPATIAL LIGHT MODULATORS; ELECTROOPTICS; POLARIZATION; SPATIAL RESOLUTION AB The results of two electro-optical implementations of the alternating projection neural network (APNN) are presented. Both configurations use optical matrix-vector multipliers with electronic feedback, but different spatial light modulators are employed. The first implementation is passive, employing a photographic transparency that intensity-modulates the incident incoherent light. In the second implementation, two spatial light modulators actively modulate the light, permitting real-time updating of the interconnection matrix elements. To the authors' knowledge, the implementations described are the first of the APNN. C1 TEXAS TECH UNIV,DEPT ELECT ENGN,LUBBOCK,TX 79409. RP SMITH, AT (reprint author), LOCKHEED ENGN & SCI CO,JOHNSON SPACE CTR,MAIL CODE C02,2400 NASA RD,HOUSTON,TX 77058, USA. NR 26 TC 1 Z9 1 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 OCT PY 1991 VL 30 IS 10 BP 1522 EP 1528 DI 10.1117/12.55972 PG 7 WC Optics SC Optics GA GK745 UT WOS:A1991GK74500011 ER PT J AU MENDENHALL, MH WELLER, RA WHITAKER, AF AF MENDENHALL, MH WELLER, RA WHITAKER, AF TI EVOLUTION OF OPTICAL COATINGS IN EARTH ORBIT SO OPTICS LETTERS LA English DT Article AB High-resolution medium-energy backscattering analyses have been performed on SiO and SiO2 optical coatings that were exposed to the space environment aboard the NASA long-duration experiment module flight (LDEF). The data show an increase in areal density of 1% (resolved at the 10-sigma-level) in the SiO film as a result of this exposure. It appears that this effect has been produced by the incorporation of atomic oxygen from the ambient environment. Data on the SiO2 film are less compelling but are consistent with some loss of material from the surface. These analyses set a new standard for profiling film thicknesses by ion backscattering. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP MENDENHALL, MH (reprint author), VANDERBILT UNIV,NASHVILLE,TN 37235, USA. NR 4 TC 0 Z9 0 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD OCT 1 PY 1991 VL 16 IS 19 BP 1466 EP 1468 DI 10.1364/OL.16.001466 PG 3 WC Optics SC Optics GA GH880 UT WOS:A1991GH88000004 PM 19777002 ER PT J AU PAL, SK ROSENFELD, A AF PAL, SK ROSENFELD, A TI A FUZZY MEDIAL AXIS TRANSFORMATION BASED ON FUZZY DISKS SO PATTERN RECOGNITION LETTERS LA English DT Article DE FUZZY DISK; FUZZY MEDIAL AXIS; FUZZY MAT AB A fuzzy disk with center P is a fuzzy set in which membership depends only on distance from P. For any fuzzy set f, there is a maximal fuzzy disk g(p)f less-than-or-equal-to f centered at every point P, and f is the sup of the g(P)f's. (Moreover, if f is fuzzy convex, so is every g(P)f, but not conversely.) We call a set S(f) of points f-sufficient if every g(P)f less-than-or-equal-to g(Q)f for some Q in S(f); evidently f is then the sup of the g(Q)f's. In particular, in a digital image, the set of Q's at which g(f) is a (nonstrict) local maximum is f-sufficient. This set is called the fuzzy medial axis of f, and the set of g(Q)f's is called the fuzzy medial axis transformation (FMAT) of f. These definitions evidently reduce to the standard one if f is a crisp set. Unfortunately, for an arbitrary f, specifying the FMAT may require more storage space than specifying f itself. C1 UNIV MARYLAND,CTR AUTOMAT RES,COMP VIS LAB,COLLEGE PK,MD 20742. INDIAN STAT INST,ELECTR & COMMUN SCI UNIT,CALCUTTA 700035,W BENGAL,INDIA. RP PAL, SK (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV INFORMAT TECHNOL,SOFTWARE TECHNOL BRANCH PT4,HOUSTON,TX 77058, USA. NR 10 TC 12 Z9 12 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8655 J9 PATTERN RECOGN LETT JI Pattern Recognit. Lett. PD OCT PY 1991 VL 12 IS 10 BP 585 EP 590 DI 10.1016/0167-8655(91)90011-A PG 6 WC Computer Science, Artificial Intelligence SC Computer Science GA GL811 UT WOS:A1991GL81100001 ER PT J AU RAST, M HOOK, SJ ELVIDGE, CD ALLEY, RE AF RAST, M HOOK, SJ ELVIDGE, CD ALLEY, RE TI AN EVALUATION OF TECHNIQUES FOR THE EXTRACTION OF MINERAL ABSORPTION FEATURES FROM HIGH SPECTRAL RESOLUTION REMOTE-SENSING DATA SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB Airborne imaging spectrometer data are influenced by a number of external factors, which mask subtle absorption features that permit the identification of surface mineralogy. This paper examines a variety of techniques developed to remove those factors, which result from the solar irradiance drop off, atmospheric absorption, and topographic effects. The techniques investigated are the flat-field correction, log residuals, and corrections using the LOWTRAN 7 atmospheric transfer code. These techniques were applied to Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) data acquired over Cuprite, Nevada. The processed data were evaluated for their ability to display the diagnostic absorption features of three areas of known mineralogy. These areas are dominated by the minerals alunite, buddingtonite, and kaolinite. The spectral features observed in the manipulated data were compared against those observed in the original data. Results indicate that the data corrected using the LOWTRAN 7 atmospheric transfer code constrained with local weather station data were the most effective at displaying the diagnostic absorption features of the areas of known mineralogy and introduced the least number of artifacts into the data. Of the remaining techniques, log residuals was the next most effective, based on the previous criteria, and has the additional advantage of not requiring any external data. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV NEVADA, DESERT RES INST, RENO, NV 89506 USA. UNIV NEVADA, AGR EXPT STN, RENO, NV 89506 USA. RP RAST, M (reprint author), EUROPEAN SPACE TECHNOL CTR, EUROPEAN SPACE AGCY, NOORDWIJK, NETHERLANDS. RI Elvidge, Christopher/C-3012-2009 NR 23 TC 13 Z9 14 U1 1 U2 5 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD OCT PY 1991 VL 57 IS 10 BP 1303 EP 1309 PG 7 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA GH859 UT WOS:A1991GH85900004 ER PT J AU MANSOUR, NN SHIH, TH REYNOLDS, WC AF MANSOUR, NN SHIH, TH REYNOLDS, WC TI THE EFFECTS OF ROTATION ON INITIALLY ANISOTROPIC HOMOGENEOUS FLOWS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID 3-DIMENSIONAL INSTABILITY; TURBULENCE; STRAIN AB Rotation of initially anisotropic homogeneous flows is studied using a model spectral tensor. It is shown that the anisotropy changes because of the influence of rotation through phase scrambling. Phase scrambling causes the Reynolds stresses to develop with damped oscillations. The final Reynolds stress anisotropy is found to be proportional to the initial structural tensor anisotropy. Closure models for the rapid pressure strain terms should reflect this change in anisotropy, and should drive the anisotropy to reach its final predicted state. Finally, it is shown that long-time integration using direct numerical simulations should be treated with care because phase scrambling effects on a discrete wave space can cause loss of resolution when time becomes large. C1 STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. RP MANSOUR, NN (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 36 Z9 38 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 OCT PY 1991 VL 3 IS 10 BP 2421 EP 2425 DI 10.1063/1.858180 PG 5 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GM595 UT WOS:A1991GM59500013 ER PT J AU FAWCETT, SC DOW, TA AF FAWCETT, SC DOW, TA TI DEVELOPMENT OF A MODEL FOR PRECISION CONTOUR GRINDING OF BRITTLE MATERIALS SO PRECISION ENGINEERING-JOURNAL OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING LA English DT Article DE PRECISION GRINDING; BRITTLE MATERIALS; SURFACE FINISH; COMPUTER SIMULATIONS AB A graphical computer model of the chip geometry resulting from a three-dimensional grinding operation was developed for use in relating the critical depth data obtained from the one-dimensional plunge-grinding technique. This model predicts the resulting surface finish and calculates the theoretical roughness and the final chip geometry for a precision grinding operation. The model is based on eluclidean geometry at the intersection of the surfaces of two solid objects. This model was programmed to calculate the remaining surface height as the wheel progresses across the part. The output of the surface profile for successive cuts can be subtracted to illustrate the shape of the chip removed for each revolution of the grinding wheel. Chip geometry as influenced by depth of cut, feed rate, and tool shape was shown to be an important parameter in diamond turning of brittle materials. Similar relationships are developed for the additional geometric complexities of a precision grinding operation. The theoretical surface features are then compared with the actual features generated by grinding brittle materials. RP FAWCETT, SC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAIL CODE EB23,HUNTSVILLE,AL 35812, USA. NR 0 TC 7 Z9 7 U1 1 U2 2 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0141-6359 J9 PRECIS ENG JI Precis. Eng.-J. Am. Soc. Precis. Eng. PD OCT PY 1991 VL 13 IS 4 BP 270 EP 276 DI 10.1016/0141-6359(91)90005-4 PG 7 WC Engineering, Multidisciplinary; Engineering, Manufacturing; Nanoscience & Nanotechnology; Instruments & Instrumentation SC Engineering; Science & Technology - Other Topics; Instruments & Instrumentation GA GK708 UT WOS:A1991GK70800005 ER PT J AU MIDDLETON, EM AF MIDDLETON, EM TI SOLAR ZENITH ANGLE EFFECTS ON VEGETATION INDEXES IN TALLGRASS PRAIRIE SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF-AREA INDEX; SPECTRAL REFLECTANCE; CANOPY REFLECTANCE; PLANT CANOPY; WHEAT; ANISOTROPY; RADIATION; SURFACES; FIFE AB Nadir spectral reflectances for a range of grass-land conditions on the Konza prairie in Kansas were acquired in 1987 from June to October during the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment, or FIFE. Measurements in the red (0.668 +/- 0.005-mu-m) and near-infrared (0.821 +/- 0.006-mu-m) were obtained at numerous solar zenith angles (SZAs) during the diurnal cycle. Reflectance factors were utilized for computation of two spectral vegetation indices (VIs) - the simple ratio (SR) and the normalized difference vegetation index (NDVI). The diurnal change in the narrow red and near-infrared bands and their VIs as a function of SZA, and the relationship of these spectral data to biophysical measurements, were examined throughout the growing season. The assumption of independence of VIs from illumination geometry was specifically addressed. Both the SR and the NDVI were significantly affected by SZA for many prairie conditions. SR was significantly related to more canopy variables over a wider SZA range (27-degrees-61-degrees) than was NDVI. For intermediate green LAI (0.5 < LAI < 2.0), both indices were at a minimum value at solar noon, increasing with SZA. Conversely, the higher biomass sites (LAI > 2.0) with especially tall grass exhibited either a maximum value at solar noon which decreased as SZA increased or a moderate to high constant VI. Low density canopies (LAI < 0.5) exhibited no change in their low VI values over the diurnal course. These qualitatively different responses precluded the use of a general "correction" to remove the observed SZA effects on the measured VI values. The strength of the relationships between VI and LAI also varied, depending on SZA, with lower predictive capability at the traditionally used "high sun" condition than at oblique sun angles (SZA > 40-degrees). The restriction of surface measurements to a standard acquisition SZA of 45-degrees produced a good correspondence of both the SR and NDVI to LAI (r2 = 0.69). The best predictive linear model for the SR was obtained at SZA = 45-degrees (r2 = 0.82) and was based on two canopy variables, the green LAI and the canopy standing green to standing dead dry weight ratio. Therefore, a standard SZA for data acquisitions at 45-degrees is recommended over the traditional "high sun" practice. The results suggest that the VIs measure the instantaneous, projected, and illuminated LAI canopy fraction relative to the illuminated substrate. RP MIDDLETON, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. NR 41 TC 51 Z9 54 U1 0 U2 6 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1991 VL 38 IS 1 BP 45 EP 62 DI 10.1016/0034-4257(91)90071-D PG 18 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GU491 UT WOS:A1991GU49100004 ER PT J AU RONDEAUX, G HERMAN, M AF RONDEAUX, G HERMAN, M TI POLARIZATION OF LIGHT REFLECTED BY CROP CANOPIES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF; MODEL AB This paper presents an analysis of polarization measurements acquired over corn and soybean crop canopies. Simultaneous plant physiological data and canopy polarization and reflectance data were collected before and after the tasseling development stage of the corn canopy, and before and during a period when the soybean canopy was water stressed. A simple model based upon the hypothesis that leaves specularly reflect light according to the Fresnel equations relates the observed bidirectional effects to the architectural and phenological conditions of the canopy. C1 UNIV LILLE 1,OPT ATMOSPHER LAB,F-59655 VILLENEUVE DASCQ,FRANCE. RP RONDEAUX, G (reprint author), NASA,AMES RES CTR,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 15 TC 55 Z9 62 U1 1 U2 12 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1991 VL 38 IS 1 BP 63 EP 75 DI 10.1016/0034-4257(91)90072-E PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GU491 UT WOS:A1991GU49100005 ER PT J AU WARSHAWSKY, I AF WARSHAWSKY, I TI LAG COMPENSATION OF OPTICAL FIBERS OR THERMOCOUPLES TO ACHIEVE WAVE-FORM FIDELITY IN DYNAMIC GAS PYROMETRY SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID TEMPERATURE; THERMOMETER AB Fidelity of waveform reproduction requires constant amplitude ratio and constant time lag of a temperature sensor's indication, at all frequencies of interest. However, heat-transfer type sensors usually cannot satisfy these requirements. Equations for the actual indication of a thermocouple and an optical-fiber pyrometer are given explicitly, in terms of sensor and flowing-gas properties. A practical, realistic design of each type of sensor behaves like a first-order system with amplitude-ratio attenuation inversely proportional to frequency when the frequency exceeds the corner frequency. Only at much higher frequencies does the amplitude-ratio attenuation for the optical fiber sensor become inversely proportional to the square root of the frequency. Design options for improving the frequency response are discussed. On-line electrical lag compensation, using a linear amplifier and a passive compensation network, can extend the corner frequency of the thermocouple 100 fold or more; a similar passive network can be used for the optical-fiber sensor. Design details for these networks are presented. RP WARSHAWSKY, I (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1991 VL 62 IS 10 BP 2443 EP 2450 DI 10.1063/1.1142261 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA GH598 UT WOS:A1991GH59800027 ER PT J AU YOST, WT CANTRELL, JH KUSHNICK, PW AF YOST, WT CANTRELL, JH KUSHNICK, PW TI CONSTANT FREQUENCY PULSED PHASE-LOCKED-LOOP INSTRUMENT FOR MEASUREMENT OF ULTRASONIC VELOCITY SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID DIFFRACTION AB A new instrument based on a constant, frequency pulsed phase-locked-loop (CFPPLL) concept has been developed to accurately measure the ultrasonic wave velocity in liquids and changes in ultrasonic wave velocity in solids and liquids. An analysis of the system shows that it is immune to many of the frequency-dependent effects that plague other techniques including the constant phase shifts of reflectors placed in the path of the ultrasonic wave. Measurements of the sound velocity in ultrapure water are used to confirm the analysis. The results are in excellent agreement with values from the literature, and establish that the CFPPLL provides a reliable, accurate way to measure velocities, as well as for monitoring small changes in velocity without the sensitivity to frequency-dependent phase shifts common to other measurement systems. The estimated sensitivity to phase changes is better than a few parts in 10(7). C1 CONTINUOUS ELECTRON BEAM ACCELERATOR FACIL,NEWPORT NEWS,VA 23606. RP YOST, WT (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 19 TC 2 Z9 2 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1991 VL 62 IS 10 BP 2451 EP 2456 DI 10.1063/1.1142262 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA GH598 UT WOS:A1991GH59800028 ER PT J AU COOK, JD ZWART, JW LONG, KJ HEINEN, VO STANKIEWICZ, N AF COOK, JD ZWART, JW LONG, KJ HEINEN, VO STANKIEWICZ, N TI AN EXPERIMENTAL APPARATUS FOR MEASURING SURFACE-RESISTANCE IN THE SUBMILLIMETER-WAVELENGTH REGION SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID MILLIMETER WAVE FREQUENCIES; FABRY-PEROT; GHZ AB A simple comparative technique to characterize surface electrical resistance of small metallic samples at submillimeter wavelengths is presented. A quasioptical hemispherical resonator, fed by an optically pumped far-infrared laser is used, with the sample serving as the plane mirror. The cavity developed combines a small beam size at the sample, enabling measurements on samples with widths as small as 5 mm, with a large quality factor Q, so that surface resistance losses are readily measurable. This cavity uses a simple new geometry that feeds the cavity through a single small coupling hole that also serves as a system of monitoring energy storage in the cavity by means of a single external beamsplitter. An alternate approach of inserting an internal beamsplitter into the resonator was found to be unacceptable due to excessive losses and alignment problems. C1 DORDT COLL,DEPT PHYS SCI,SIOUX CTR,IA 51250. NASA,LEWIS RES CTR,DIV SPACE ELECTR,CLEVELAND,OH 44135. RP COOK, JD (reprint author), EASTERN KENTUCKY UNIV,DEPT PHYS & ASTRON,RICHMOND,KY 40475, USA. NR 20 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1991 VL 62 IS 10 BP 2480 EP 2485 DI 10.1063/1.1142269 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA GH598 UT WOS:A1991GH59800035 ER PT J AU COTTON, JD KAUFMAN, MJ NOEBE, RD AF COTTON, JD KAUFMAN, MJ NOEBE, RD TI A SIMPLIFIED METHOD FOR DETERMINING THE NUMBER OF INDEPENDENT SLIP SYSTEMS IN CRYSTALS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP COTTON, JD (reprint author), UNIV FLORIDA,DEPT MAT SCI & ENGN,GAINESVILLE,FL 32611, USA. RI Kaufman, Michael/A-7737-2012 NR 7 TC 18 Z9 18 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD OCT PY 1991 VL 25 IS 10 BP 2395 EP 2398 DI 10.1016/0956-716X(91)90036-Z PG 4 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA GH241 UT WOS:A1991GH24100036 ER PT J AU DUNDAS, JA AF DUNDAS, JA TI IMPLEMENTING DYNAMIC MINIMAL-PREFIX TRIES SO SOFTWARE-PRACTICE & EXPERIENCE LA English DT Article DE TREES; SEARCHING; PATTERN MATCHING; DICTIONARY AB A modified trie-searching algorithm and corresponding data structure are introduced which permit rapid search of a dictionary for a symbol or a valid abbreviation. The dictionary-insertion algorithm automatically determines disambiguation points, where possible, for each symbol. The search operation will classify a symbol as one of the following: unknown (i.e. not a valid symbol), ambiguous (i.e. is a prefix of more than one valid symbol) or known. The search operation is performed in linear time proportional to the length of the input symbol, rather than the complexity of the trie. An example implementation is given in the C programming language. RP DUNDAS, JA (reprint author), CALTECH,JET PROP LAB,MAIL STOP 510-202,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 TC 18 Z9 21 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0038-0644 J9 SOFTWARE PRACT EXPER JI Softw.-Pract. Exp. PD OCT PY 1991 VL 21 IS 10 BP 1027 EP 1040 DI 10.1002/spe.4380211004 PG 14 WC Computer Science, Software Engineering SC Computer Science GA GJ035 UT WOS:A1991GJ03500003 ER PT J AU GOLUB, MA WYDEVEN, T AF GOLUB, MA WYDEVEN, T TI WASTE MANAGEMENT IN SPACE - PREFACE SO WASTE MANAGEMENT & RESEARCH LA English DT Editorial Material RP GOLUB, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD OCT PY 1991 VL 9 IS 5 BP 323 EP 323 PG 1 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GR065 UT WOS:A1991GR06500001 ER PT J AU MENDELL, WW AF MENDELL, WW TI THE SPACE EXPLORATION INITIATIVE - A CHALLENGE TO ADVANCED LIFE-SUPPORT TECHNOLOGIES - KEYNOTE PRESENTATION SO WASTE MANAGEMENT & RESEARCH LA English DT Editorial Material CT SYMP ON WASTE PROCESSING IN SPACE FOR ADVANCED LIFE SUPPORT CY SEP 11-13, 1990 CL AMES RES CTR, MOFFETT FIELD, CA SP NASA HO AMES RES CTR DE SPACE EXPLORATION INITIATIVE; MOON; MARS; LIFE SUPPORT SYSTEM; INSITU RESOURCES; SELF-SUFFICIENCY; NASA; CELSS; SPACE-STATION-FREEDOM RP MENDELL, WW (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,MISS SCI & TECHNOL OFF,MS SN14,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD OCT PY 1991 VL 9 IS 5 BP 327 EP 329 PG 3 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GR065 UT WOS:A1991GR06500003 PM 11537682 ER PT J AU BOURLAND, CT SMITH, MC AF BOURLAND, CT SMITH, MC TI SELECTION OF HUMAN CONSUMABLES FOR FUTURE SPACE MISSIONS SO WASTE MANAGEMENT & RESEARCH LA English DT Article; Proceedings Paper CT SYMP ON WASTE PROCESSING IN SPACE FOR ADVANCED LIFE SUPPORT CY SEP 11-13, 1990 CL AMES RES CTR, MOFFETT FIELD, CA SP NASA HO AMES RES CTR DE SPACE FOOD; SPACE-STATION-FREEDOM; SHUTTLE ORBITER; SPACECRAFT WATER; FOOD DEHYDRATION; COMPACTOR; RECYCLING; ASEPTIC PACKAGING RP BOURLAND, CT (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 3 Z9 4 U1 5 U2 9 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD OCT PY 1991 VL 9 IS 5 BP 339 EP 344 DI 10.1177/0734242X9100900150 PG 6 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GR065 UT WOS:A1991GR06500005 PM 11537684 ER PT J AU BUBENHEIM, DL AF BUBENHEIM, DL TI PLANTS FOR WATER RECYCLING, OXYGEN REGENERATION AND FOOD-PRODUCTION SO WASTE MANAGEMENT & RESEARCH LA English DT Article; Proceedings Paper CT SYMP ON WASTE PROCESSING IN SPACE FOR ADVANCED LIFE SUPPORT CY SEP 11-13, 1990 CL AMES RES CTR, MOFFETT FIELD, CA SP NASA HO AMES RES CTR DE CONTROLLED ECOLOGICAL LIFE SUPPORT SYSTEMS (CELSS); CROP PHYSIOLOGY; BIOLOGICAL WASTE PROCESSING; CONTROLLED ENVIRONMENT AGRICULTURE; PHOTOSYNTHESIS; OXYGEN; CARBON DIOXIDE; WATER PURIFICATION; FOOD RP BUBENHEIM, DL (reprint author), NASA,AMES RES CTR,DIV ADV LIFE SUPPORT,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 0 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD OCT PY 1991 VL 9 IS 5 BP 435 EP 443 DI 10.1177/0734242X9100900162 PG 9 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GR065 UT WOS:A1991GR06500017 PM 11537696 ER PT J AU BARESI, L KERN, R AF BARESI, L KERN, R TI WASTE TREATMENT INTEGRATION IN SPACE SO WASTE MANAGEMENT & RESEARCH LA English DT Article; Proceedings Paper CT SYMP ON WASTE PROCESSING IN SPACE FOR ADVANCED LIFE SUPPORT CY SEP 11-13, 1990 CL AMES RES CTR, MOFFETT FIELD, CA SP NASA HO AMES RES CTR DE ANAEROBIC DIGESTION; WASTE TREATMENT; CONSORTIA; HYBRID-SYSTEMS; ABIOLOGICAL OXIDATION; ENERGY ANALYSIS; ENTROPY; BIOLOGICAL TREATMENT; SYSTEM ANALYSIS; CHEMICAL BIOLOGICAL WASTE TREATMENT RP BARESI, L (reprint author), CALTECH,JET PROP LAB,MS 125-112,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 2 U2 2 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD OCT PY 1991 VL 9 IS 5 BP 485 EP 490 PG 6 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA GR065 UT WOS:A1991GR06500023 PM 11537702 ER PT J AU MATUS, LG POWELL, JA SALUPO, CS AF MATUS, LG POWELL, JA SALUPO, CS TI HIGH-VOLTAGE 6H-SIC P-N-JUNCTION DIODES SO APPLIED PHYSICS LETTERS LA English DT Article ID LIGHT-EMITTING-DIODES; GROWTH; FABRICATION; FILMS AB A chemical vapor deposition (CVD) process has been used to produce device structures of n- and p-type 6H-SiC epitaxial layers on commercially produced single-crystal 6H-SiC wafers. Mesa-style p-n junction diodes were successfully fabricated from these device structures using reactive ion etching, oxide passivation, and electrical contact metallization techniques. When tested in air, the 6H-SiC diodes displayed excellent rectification characteristics up to the highest temperature tested, 600-degrees-C. To observe avalanche breakdown of the p-n junction diodes, testing under a high-electrical-strength liquid was necessary. The avalanche breakdown voltage was 1000 V representing the highest reverse breakdown voltage to be reported for any CVD-grown SiC diode. C1 CALSPAN CORP,MIDDLEBURG HTS,OH 44130. RP MATUS, LG (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 52 Z9 52 U1 2 U2 8 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 SEP 30 PY 1991 VL 59 IS 14 BP 1770 EP 1772 DI 10.1063/1.106195 PG 3 WC Physics, Applied SC Physics GA GH409 UT WOS:A1991GH40900040 ER PT J AU MUHLEMAN, DO BUTLER, BJ GROSSMAN, AW SLADE, MA AF MUHLEMAN, DO BUTLER, BJ GROSSMAN, AW SLADE, MA TI RADAR IMAGES OF MARS SO SCIENCE LA English DT Article ID SURFACE PROPERTIES; EXTENDED COVERAGE; WIND STREAKS; MARINER-9; THARSIS AB Full disk images of Mars have been obtained with the use of the Very Large Array (VLA) to map the radar reflected flux density. The transmitter system was the 70-m antenna of the Deep Space Network at Goldstone, California. The surface of Mars was illuminated with continuous wave radiation at a wavelength of 3.5 cm. The reflected energy was mapped in individual 12-minute snapshots with the VLA in its largest configuration; fringe spacings as small as 67 km were obtained. The images reveal near-surface features including a region in the Tharsis volcano area, over 2000 km in east-west extent, that displayed no echo to the very low level of the radar system noise. The feature, called Stealth, is interpreted as a deposit of dust or ash with a density less than about 0.5 gram per cubic centimeter and free of rocks larger than 1 cm across. The deposit must be several meters thick and may be much deeper. The strongest reflecting geological feature was the south polar ice cap, which was reduced in size to the residual south polar ice cap at the season of observation. The cap image is interpreted as arising from nearly pure CO2 or H2O ice with a small amount of martian dust (less than 2 percent by volume) and a depth greater than 2 to 5 m. Only one anomalous reflecting feature was identified outside of the Tharsis region, although the Elysium region was poorly sampled in this experiment and the north pole was not visible from Earth. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP MUHLEMAN, DO (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. NR 32 TC 98 Z9 98 U1 0 U2 8 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1508 EP 1513 DI 10.1126/science.253.5027.1508 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100033 PM 17784090 ER PT J AU JOHNSON, TV YEATES, CM YOUNG, R DUNNE, J AF JOHNSON, TV YEATES, CM YOUNG, R DUNNE, J TI THE GALILEO VENUS ENCOUNTER SO SCIENCE LA English DT Article ID SIDE AB The Galileo spacecraft passed Venus on its way to Jupiter on 10 February 1990, less than 4 months after launch from Earth aboard the shuttle Atlantis. Because Galileo's instruments were selected for broad-based planetary exploration, the spacecraft was able to obtain a wide range of measurements during the Venus encounter. Together with ground-based observations conducted during the encounter, these observations have yielded more accurate information about the planet's plasma environment, cloud patterns, and the possible existence of lightning. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JOHNSON, TV (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 5 Z9 5 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1516 EP 1518 DI 10.1126/science.253.5027.1516 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100034 PM 17784091 ER PT J AU GURNETT, DA KURTH, WS ROUX, A GENDRIN, R KENNEL, CF BOLTON, SJ AF GURNETT, DA KURTH, WS ROUX, A GENDRIN, R KENNEL, CF BOLTON, SJ TI LIGHTNING AND PLASMA-WAVE OBSERVATIONS FROM THE GALILEO FLYBY OF VENUS SO SCIENCE LA English DT Article ID EARTHS BOW SHOCK; TURBULENCE; FORESHOCK AB During the Galileo flyby of Venus the plasma wave instrument was used to search for impulsive radio signals from lightning and to investigate locally generated plasma waves. A total of nine events were detected in the frequency range from 100 kilohertz to 5.6 megahertz. Although the signals are weak, lightning is the only known source of these signals. Near the bow shock two types of locally generated plasma waves were observed, low-frequency electromagnetic waves from about 5 to 50 hertz and electron plasma oscillation at about 45 kilohertz. The plasma oscillations have considerable fine structure, possibly because of the formation of soliton-like wave packets. C1 CTR NATL ETUD TELECOMMUN,CTR RECH PHYS ENVIRONNEMENT,F-92131 ISSY MOULINEAUX,FRANCE. UNIV CALIF LOS ANGELES,DEPT PHYS,LOS ANGELES,CA 90024. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP GURNETT, DA (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. OI Kurth, William/0000-0002-5471-6202 NR 23 TC 50 Z9 50 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1522 EP 1525 DI 10.1126/science.253.5027.1522 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100036 PM 17784093 ER PT J AU BELTON, MJS GIERASCH, PJ SMITH, MD HELFENSTEIN, P SCHINDER, PJ POLLACK, JB RAGES, KA INGERSOLL, AP KLAASEN, KP VEVERKA, J ANGER, CD CARR, MH CHAPMAN, CR DAVIES, ME FANALE, FP GREELEY, R GREENBERG, R HEAD, JW MORRISON, D NEUKUM, G PILCHER, CB AF BELTON, MJS GIERASCH, PJ SMITH, MD HELFENSTEIN, P SCHINDER, PJ POLLACK, JB RAGES, KA INGERSOLL, AP KLAASEN, KP VEVERKA, J ANGER, CD CARR, MH CHAPMAN, CR DAVIES, ME FANALE, FP GREELEY, R GREENBERG, R HEAD, JW MORRISON, D NEUKUM, G PILCHER, CB TI IMAGES FROM GALILEO OF THE VENUS CLOUD DECK SO SCIENCE LA English DT Article ID ATMOSPHERE; WAVES; CIRCULATION; MESOSPHERE; PICTURES; DYNAMICS; PATTERNS; JUPITER; FLUXES; WINDS AB Images of Venus taken at 418 (violet) and 986 [near-infrared (NIR)] nanometers show that the morphology and motions of large-scale features change with depth in the cloud deck. Poleward meridional velocities, seen in both spectral regions, are much reduced in the NIR. In the south polar region the markings in the two wavelength bands are strongly anticorrelated. The images follow the changing state of the upper cloud layer downwind of the subsolar point, and the zonal flow field shows a longitudinal periodicity that may be coupled to the formation of large-scale planetary waves. No optical lightning was detected. C1 CORNELL UNIV,ITHACA,NY 14853. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CALTECH,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. ITRES RES LTD,CALGARY T2E 7H7,ALBERTA,CANADA. US GEOL SURVEY,MENLO PK,CA 94025. SCI APPLICAT INT CORP,INST CHAPMAN PLANETARY SCI,TUCSON,AZ 85719. RAND CORP,SANTA MONICA,CA 90406. INST GEOPHYS,HONOLULU,HI 96822. NASA HEADQUARTERS,WASHINGTON,DC 20546. ARIZONA STATE UNIV,TEMPE,AZ 85281. UNIV ARIZONA,TUCSON,AZ 85721. BROWN UNIV,PROVIDENCE,RI 02912. DFVLR,W-8031 OBERPFAFFENHOFEN,GERMANY. RP BELTON, MJS (reprint author), NATL OPT ASTRON OBSERV,TUCSON,AZ 85719, USA. RI Smith, Michael/C-8875-2012 NR 37 TC 73 Z9 75 U1 0 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1531 EP 1536 DI 10.1126/science.253.5027.1531 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100039 PM 17784096 ER PT J AU ORTON, GS CALDWELL, J FRIEDSON, AJ MARTIN, TZ AF ORTON, GS CALDWELL, J FRIEDSON, AJ MARTIN, TZ TI MIDDLE INFRARED THERMAL MAPS OF VENUS AT THE TIME OF THE GALILEO ENCOUNTER SO SCIENCE LA English DT Article AB Images of the disk of Venus, taken at wavelengths between 8 and 22 micrometers, were obtained a few days after the Galileo spacecraft's closest approach on 8 February 1990; these images show variations in the thickness of the main H2SO4 cloud deck and the overlying temperature structure. Several features are qualitatively similar to those of earlier observations, such as a hot region at the south pole, surrounded by a cold "collar," and brightening toward the lower latitudes, where low-contrast banding appears. The collar does have a northern counterpart that is warmer, however. Equatorial limb darkening is quantitatively similar to that of previous observations; fairly constant at wavelengths up to 20 micrometers, where limb darkening increases substantially. In contrast to what was found in previous observations, polar and equatorial limb darkening are nearly the same at most wavelengths. A longitudinal variation is observable that is consistent with a wavenumber-2 behavior and a brightness maximum near local midnight. C1 YORK UNIV,DEPT PHYS,N YORK M3J 1P3,ONTARIO,CANADA. RP ORTON, GS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 169-237,PASADENA,CA 91109, USA. NR 22 TC 2 Z9 2 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1536 EP 1538 DI 10.1126/science.253.5027.1536 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100040 PM 17784097 ER PT J AU CRISP, D MCMULDROCH, S STEPHENS, SK SINTON, WM RAGENT, B HODAPP, KW PROBST, RG DOYLE, LR ALLEN, DA ELIAS, J AF CRISP, D MCMULDROCH, S STEPHENS, SK SINTON, WM RAGENT, B HODAPP, KW PROBST, RG DOYLE, LR ALLEN, DA ELIAS, J TI GROUND-BASED NEAR-INFRARED IMAGING OBSERVATIONS OF VENUS DURING THE GALILEO ENCOUNTER SO SCIENCE LA English DT Article ID NIGHT-SIDE; ATMOSPHERE; SPECTRA AB Near-infrared images of Venus, obtained from a global network of ground-based observatories during January and February 1990, document the morphology and motions of the night-side near-infrared markings before, during, and after the Galileo Venus encounter. A dark cloud extended halfway around the planet at low latitudes (< +/- 40-degrees) and persisted throughout the observing program. It had a rotation period of 5.5 +/- 0.15 days. The remainder of this latitude band was characterized by small-scale (400 to 1000 kilometers) dark and bright markings with rotation periods of 7.4 +/- 1 days. The different rotation periods for the large dark cloud and the smaller markings suggests that they are produced at different altitudes. Mid-latitudes (+/- 40-degrees to 60-degrees) were usually occupied by bright east-west bands. The highest observable latitudes (+/- 60-degrees to 70-degrees) were always dark and featureless, indicating greater cloud opacity. Maps of the water vapor distribution show no evidence for large horizontal gradients in the lower atmosphere of Venus. C1 CALTECH,PALOMAR OBSERV,PASADENA,CA 91125. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. LAS CAMPANAS OBSERV,LA SERENE,CHILE. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. SAN JOSE STATE UNIV FDN,SAN JOSE,CA 95192. UNIV HAWAII,MAUNA KEA OBSERV,MAUNA KEA,HI. KITT PEAK NATL OBSERV,TUCSON,AZ 85719. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. RP CRISP, D (reprint author), CALTECH,JET PROP LAB,MS 169-237,PASADENA,CA 91109, USA. NR 29 TC 52 Z9 53 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1538 EP 1541 DI 10.1126/science.253.5027.1538 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100041 PM 17784098 ER PT J AU CARLSON, RW BAINES, KH ENCRENAZ, T TAYLOR, FW DROSSART, P KAMP, LW POLLACK, JB LELLOUCH, E COLLARD, AD CALCUTT, SB GRINSPOON, D WEISSMAN, PR SMYTHE, WD OCAMPO, AC DANIELSON, GE FANALE, FP JOHNSON, TV KIEFFER, HH MATSON, DL MCCORD, TB SODERBLOM, LA AF CARLSON, RW BAINES, KH ENCRENAZ, T TAYLOR, FW DROSSART, P KAMP, LW POLLACK, JB LELLOUCH, E COLLARD, AD CALCUTT, SB GRINSPOON, D WEISSMAN, PR SMYTHE, WD OCAMPO, AC DANIELSON, GE FANALE, FP JOHNSON, TV KIEFFER, HH MATSON, DL MCCORD, TB SODERBLOM, LA TI GALILEO INFRARED IMAGING SPECTROSCOPY MEASUREMENTS AT VENUS SO SCIENCE LA English DT Article ID NIGHT-SIDE; ATMOSPHERE; SPECTRA AB During the 1990 Galileo Venus flyby, the Near Infrared Mapping Spectrometer investigated the night-side atmosphere of Venus in the spectral range 0.7 to 5.2 micrometers. Multispectral images at high spatial resolution indicate substantial cloud opacity variations in the lower cloud levels, centered at 50 kilometers altitude. Zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a Hadley cell. Northern and southern hemisphere clouds appear to be markedly different. Spectral profiles were used to derive lower atmosphere abundances of water vapor and other species. C1 OBSERV PARIS,F-92195 MEUDON,FRANCE. UNIV OXFORD,OXFORD OX1 3PU,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91109. UNIV HAWAII,HONOLULU,HI 96822. US GEOL SURVEY,FLAGSTAFF,AZ 86001. RP CARLSON, RW (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. OI Calcutt, Simon/0000-0002-0102-3170 NR 36 TC 111 Z9 113 U1 0 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1541 EP 1548 DI 10.1126/science.253.5027.1541 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100042 PM 17784099 ER PT J AU HORD, CW BARTH, CA ESPOSITO, LW MCCLINTOCK, WE PRYOR, WR SIMMONS, KE STEWART, AIF THOMAS, GE AJELLO, JM LANE, AL WEST, RW SANDEL, BR BROADFOOT, AL HUNTEN, DM SHEMANSKY, DE AF HORD, CW BARTH, CA ESPOSITO, LW MCCLINTOCK, WE PRYOR, WR SIMMONS, KE STEWART, AIF THOMAS, GE AJELLO, JM LANE, AL WEST, RW SANDEL, BR BROADFOOT, AL HUNTEN, DM SHEMANSKY, DE TI GALILEO ULTRAVIOLET SPECTROMETER EXPERIMENT - INITIAL VENUS AND INTERPLANETARY CRUISE RESULTS SO SCIENCE LA English DT Article ID SOLAR-WIND; PIONEER-VENUS; ANISOTROPY; EMISSIONS AB The Galileo Extreme Ultraviolet Spectrometer obtained a spectrum of Venus atmospheric emissions in the 55.0- to 125.0-nanometer (nm) wavelength region. Emissions of helium (58.4 nm), ionized atomic oxygen (83.4 nm), and atomic hydrogen (121.6 nm), as well as a blended spectral feature of atomic hydrogen (Lyman-beta) and atomic oxygen (102.5 nm), were observed at 3.5-nm resolution. During the Galileo spacecraft cruise from Venus to Earth, Lyman-alpha emission from solar system atomic hydrogen (121.6 nm) was measured. The dominant source of the Lyman-alpha emission is atomic hydrogen from the interstellar medium. A model of Galileo observations at solar maximum indicates a decrease in the solar Lyman-alpha flux near the solar poles. A strong day-to-day variation also occurs with the 27-day periodicity of the rotation of the sun. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP HORD, CW (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. NR 13 TC 13 Z9 13 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 27 PY 1991 VL 253 IS 5027 BP 1548 EP 1550 DI 10.1126/science.253.5027.1548 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG651 UT WOS:A1991GG65100043 PM 17784100 ER PT J AU KAZANAS, D AF KAZANAS, D TI NEUTRINO ASTRONOMY - PUTTING A PROJECT ON ICE SO NATURE LA English DT Editorial Material ID ORIGIN RP KAZANAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 665,GREENBELT,MD 20771, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD SEP 26 PY 1991 VL 353 IS 6342 BP 298 EP 299 DI 10.1038/353298a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GG654 UT WOS:A1991GG65400024 ER PT J AU PEARL, J NGOH, M OSPINA, M KHANNA, R AF PEARL, J NGOH, M OSPINA, M KHANNA, R TI OPTICAL-CONSTANTS OF SOLID METHANE AND ETHANE FROM 10,000 TO 450 CM-1 SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID INFRARED-SPECTRA; VOYAGER-2; CH4; NH3 AB We made thin film transmission measurements of solid CH4 (phases I and II) and C2H6 (phase II). From these, the complex indices of refraction at near- and mid-infrared wavelengths were determined by using a combined least squares and Kramers-Kronig analysis. C1 UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742. RP PEARL, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 22 TC 44 Z9 44 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1991 VL 96 IS E2 BP 17477 EP 17482 DI 10.1029/91JE01741 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500005 ER PT J AU FOX, K QUILLEN, DT JENNINGS, DE WAGNER, J PLYMATE, C AF FOX, K QUILLEN, DT JENNINGS, DE WAGNER, J PLYMATE, C TI METHANE SPECTRAL-LINE WIDTHS AND SHIFTS, AND DEPENDENCES ON PHYSICAL PARAMETERS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID COLLISIONS; HYDROGEN; NITROGEN; HELIUM; ARGON; CM-1 AB High-resolution measurements of widths and shifts of vibrational-rotational lines in infrared spectra of gaseous methane have been made in the laboratory. This research introduced at ambient temperatures the rare gases helium, neon, argon, krypton, and xenon and the diatomics hydrogen, nitrogen, oxygen, and carbon monoxide at pressures from 100 to 700 torr. Detailed quantitative studies of correlations with masses, polarizabilities and quadrupole moments suggest that there may be some functional dependences on these physical parameters. C1 UNIV TENNESSEE,DEPT PHYS & ASTRON,KNOXVILLE,TN 37996. BOWIE STATE UNIV,DEPT COMP SCI,BOWIE,MD 20715. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. RP FOX, K (reprint author), UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742, USA. RI Jennings, Donald/D-7978-2012 NR 11 TC 7 Z9 7 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1991 VL 96 IS E2 BP 17483 EP 17488 DI 10.1029/91JE01678 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500006 ER PT J AU KURTZ, J REUTER, DC JENNINGS, DE HILLMAN, JJ AF KURTZ, J REUTER, DC JENNINGS, DE HILLMAN, JJ TI LABORATORY SPECTRA OF C-13 ETHANE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID INFRARED OBSERVATIONS; C-12-C-13 RATIO; JUPITER; SATURN; ATMOSPHERES; ACETYLENE AB The laboratory infrared spectrum of C-13 monosubstituted ethane has been obtained at high resolution (0.0025 cm-1) using the McMath Fourier transform spectrometer at Kitt Peak National Observatory in May 1990. A preliminary analysis of the V12 (r)Q(o) branch (substituted species) suggests that its intensity is 1.15 +/- 0.05 times stronger than the equivalent V9 branch in the normal (C2H6)-C-12-H-6 species. This result leads to a correction of a previously published estimate for the C-12/C-13 ratio in the atmosphere of Jupiter from approximately 94 to approximately 106. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RP KURTZ, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,ASTROPHYS BRANCH,CODE 691,GREENBELT,MD 20771, USA. RI Jennings, Donald/D-7978-2012 NR 13 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 SEP 25 PY 1991 VL 96 IS E2 BP 17489 EP 17492 DI 10.1029/91JE01742 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500007 ER PT J AU MAGUIRE, WC HILLMAN, JJ WEBER, M BLASS, WE AF MAGUIRE, WC HILLMAN, JJ WEBER, M BLASS, WE TI HERMAN-WALLIS FACTORS IN THE C2H2-NU-5 INFRARED FUNDAMENTAL NEAR 14-MU-M SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID INTENSITIES AB The presence of acetylene has been confirmed for some time in the atmospheres of the outer planets Jupiter, Saturn, Neptune, and Saturn's satellite Titan. For these atmospheres, the determination of C2H2 abundances using its strong nu-5 fundamental requires laboratory line position and intensity measurements. The 1-meter Fourier transform spectrometer at McMath solar telescope of Kitt Peak National Observatory was used to measure C2H2 at an unapodized spectral resolution of 0.0025 cm-1. Synthetic spectra are generated by convolving a Voigt line shape with an instrument function and varying intensity parameters by means of a nonlinear least squares technique. Intensities of 37 nu-5 lines spanning P18 through R20 were measured using 0.123 torr of gas in a 1-cm cell. A Herman-Wallis intensity correction parameter A1pr = 1.3(4) x 10(-3) has been derived using a least squares linear fit. C1 UNIV TENNESSEE,DEPT PHYS,KNOXVILLE,TN 37966. RP MAGUIRE, WC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,MAIL CODE 693 2,GREENBELT,MD 20771, USA. RI Blass, William/A-2792-2008; Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1991 VL 96 IS E2 BP 17493 EP 17496 DI 10.1029/91JE01773 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500008 ER PT J AU MOORE, MH KHANNA, R DONN, B AF MOORE, MH KHANNA, R DONN, B TI STUDIES OF PROTON IRRADIATED H2O+CO2 AND H2O+CO ICES AND ANALYSIS OF SYNTHESIZED MOLECULES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID COMET P/HALLEY; SPECTRUM; EMISSION; HALLEY AB Infrared spectra of H2O+CO2 and H2O+CO ices before and after proton irradiation showed that a major reaction in both mixtures was the interconversion of CO2 half-arrow-right-over-half-arrow-left CO. Radiation synthesized organic compounds such as carbonic acid were identified in the H2O+CO2 ice. Different chemical pathways dominate in the H2O+CO ice in which formaldehyde, methanol, ethanol, and methane were identified. Sublimed material was also analyzed using a mass spectrometer. Implications of these results are discussed in reference to comets. C1 UNIV VIRGINIA,DEPT NUCL ENGN & ENGN PHYS,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MOORE, MH (reprint author), UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742, USA. NR 18 TC 87 Z9 87 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1991 VL 96 IS E2 BP 17541 EP 17545 DI 10.1029/91JE01682 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500016 ER PT J AU RATLIFF, JM JAMES, GK TRAJMAR, S AJELLO, JM SHEMANSKY, DE AF RATLIFF, JM JAMES, GK TRAJMAR, S AJELLO, JM SHEMANSKY, DE TI ELECTRON-IMPACT EXCITATION AND DISSOCIATION OF N-2 VIA THE B(1)PI(U) STATE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID CROSS-SECTIONS; N2 AB Electron impact excitation of the b PI-1-u state in N2 plays a prominent role in the dissociation of the molecule and thus in the production of atomic nitrogen in planetary atmospheres. Electron impact excitation cross sections combined with electron-impact-induced fluorescence mesurements can yield the corresponding dissociation cross sections. Serious discrepancies exist among excitation cross sections reported in the literature. To clarify the situation, we measured these cross sections at two impact energies using electron energy loss spectroscopy. The new results are in agreement with recent values deduced from optical measurements and fall midway between previous results which are too high or low by factors of 2. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP RATLIFF, JM (reprint author), CALTECH,JET PROP LAB,MS 183601,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 11 Z9 11 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 SEP 25 PY 1991 VL 96 IS E2 BP 17559 EP 17561 DI 10.1029/91JE01685 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500019 ER PT J AU RAO, MVVS SRIVASTAVA, SK AF RAO, MVVS SRIVASTAVA, SK TI CROSS-SECTIONS FOR DIRECT AND DISSOCIATIVE IONIZATION OF NH3 AND CS2 BY ELECTRON-IMPACT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT 2ND INTERNATIONAL CONF ON LABORATORY RESEARCH FOR PLANETARY ATMOSPHERES ( 2ND ICLRPA ) CY OCT 21, 1990 CL UNIV VIRGINIA CHARLOTTESVILLE, CHARLOTTESVILLE, VA SP NASA, GODDARD SPACE FLIGHT CTR, UNIV MARYLAND, UNIV TENNESSEE, UNIV VIRGINIA HO UNIV VIRGINIA CHARLOTTESVILLE ID AMMONIA; GAS AB Cross sections for the production of positive ions by electron impact on NH3 and CS2 have been measured using a crossed electron beam-molecular beam collision geometry. The present results on NH3 are considerably different from previous measurements which disagree among themselves. Except for the formation of CS2+, cross sections for other fragment ions resulting from CS2 have not been measured in the past. Threshold energies for the appearance of various positive ions are also reported. It is estimated that the present results are accurate to within 15%. RP RAO, MVVS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 17 Z9 17 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1991 VL 96 IS E2 BP 17563 EP 17567 DI 10.1029/91JE01689 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GJ255 UT WOS:A1991GJ25500020 ER PT J AU STIEGMAN, AE GRAHAM, E PERRY, KJ KHUNDKAR, LR CHENG, LT PERRY, JW AF STIEGMAN, AE GRAHAM, E PERRY, KJ KHUNDKAR, LR CHENG, LT PERRY, JW TI THE ELECTRONIC-STRUCTURE AND 2ND-ORDER NONLINEAR OPTICAL-PROPERTIES OF DONOR-ACCEPTOR ACETYLENES - A DETAILED INVESTIGATION OF STRUCTURE PROPERTY RELATIONSHIPS SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID CONJUGATED MOLECULES; HYPERPOLARIZABILITIES; SUSCEPTIBILITIES; SYSTEMS AB A series of donor-acceptor acetylene compounds was synthesized in which systematic changes in both the conjugation length and the donor-acceptor strength were made. The effect of these structural changes on the spectroscopic and electronic properties of the molecules and, ultimately, on the measured second-order molecular hyperpolarizabilities (beta) was investigated. It was found that increases in the donor-acceptor strength resulted in increases in the magnitude of beta. For this class of molecules the increase is dominated by the energy of the intramolecular charge-transfer transition, while factors such as the ground to excited-state dipole moment change and the transition-moment integral are much less important. Increasing the conjugation length from one to two acetylene linkers did not result in an increase in the value of beta; however, beta increased sharply in going from two acetylenes to three. This increase is attributed to the superposition of several nearly isoenergetic excited states. C1 DUPONT CO INC, DEPT CENT RES & DEV, EXPTL STN, WILMINGTON, DE 19880 USA. RP STIEGMAN, AE (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 27 TC 179 Z9 182 U1 1 U2 10 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 SEP 25 PY 1991 VL 113 IS 20 BP 7658 EP 7666 DI 10.1021/ja00020a030 PG 9 WC Chemistry, Multidisciplinary SC Chemistry GA GH058 UT WOS:A1991GH05800030 ER PT J AU RAJ, SV WHITTENBERGER, JD PHARR, GM AF RAJ, SV WHITTENBERGER, JD PHARR, GM TI DOES THE SUBGRAIN SIZE INFLUENCE THE RATE OF CREEP - COMMENT SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Letter ID COPPER SINGLE CRYSTALS; SUBSTRUCTURE FORMATION; STRESS REDUCTION; BEHAVIOR; AL AB A recent paper questions the validity of the experimental observations and the conclusions reached by other researchers on the importance of cells in determining the creep behavior of materials. In an attempt to duplicate the stress change experiment described by the latter researchers, which resulted in a cellular microstructure, it was reported that cells were not observed in the test described in that recent paper. As a result, it was suggested that the microstructural observations reported by the latter researchers were an artifact since they may have been made too close to the compression surface. The present letter clarifies our experimental procedures and observations on NaCl single crystals in the light of the points raised by the authors of the recent paper and examines the importance of cells in determining creep behavior. It is concluded that cells are not spurious microstructural features and that they should be included along with subgrains and "free" dislocations in developing creep models. C1 RICE UNIV,DEPT MAT SCI,HOUSTON,TX 77251. RP RAJ, SV (reprint author), NASA,LEWIS RES CTR,MS 49-1,CLEVELAND,OH 44135, USA. NR 11 TC 2 Z9 2 U1 0 U2 3 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD SEP 25 PY 1991 VL 145 IS 1 BP L13 EP L17 DI 10.1016/0921-5093(91)90308-A PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA GN814 UT WOS:A1991GN81400019 ER PT J AU MEIER, DL SADUN, AC LIND, KR AF MEIER, DL SADUN, AC LIND, KR TI HEAVY, OVERPRESSURED JETS AND THE RADIO-SOURCE HERCULES-A SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES - INDIVIDUAL (HERCULES A); GALAXIES - JETS; HYDRODYNAMICS ID MACH NUMBER JET; SURFACE BRIGHTNESS; TURBULENT; MODEL; RINGS AB We investigate the flow of jets with pressure and density initially much greater than the medium into which they are injected. While having many features in common with the classical light, pressure-balanced jets studied in recent investigations, heavy, overpressured jets differ in that they expand at the Mach angle and have a conical expansion shock and large convex Mach disk. The ''ice cream cone'' shape of these shocks should be visible in high-dynamic-range radio maps. Some numerical models are observed to recollimate, creating broader jets at lower density. We develop analytic expressions which describe the cocoon formation and recollimation processes. The concept of a jet with a large overpressure should be applicable to many situations where the observed jet has a conical appearance and, perhaps, recollimates. Under the assumption that the rings seen in high-resolution images of Hercules A are shocks, we model the western lobe of this source as a heavy overpressured flow where, about 20'' from the nucleus, the jet suddenly becomes much greater in pressure than the surrounding medium and freely expands. We argue that jet models which are supersonic with respect to both the internal and external speeds are applicable and find that, in spite of the prominent ring structure in Her A, the flow must be dominated by a smooth conical jet. This result is consistent with the kinematic model of Morrison, & Sadun. Although we do not numerically simulate the rings in the western lobe, our models are also consistent with MMS suggestion that the rings are weak spherical shocks in that flow: their size is small compared to the scale length for the sound speed to change. Depending on the exact flow velocity and Mach number, the jet may be initially heavy (eta-o > 1) compared to the ambient medium at the point where expansion begins. The flow becomes light (eta > 6 x 10(-3)) much further out due to the expansion and is able to produce the cocoon seen in low-resolution radio maps. We have tentatively identified the Mach disk, bow shock, and the plug in the radio map of the western lobe as the two outer arcs of emission and the space between them, respectively. The identification of these arcs as strong shocks is strengthened by their observed magnetic field structure. Additional studies are needed to understand ring formation and propagation in such flows and to understand why the sudden expansion in Her A takes place. The former problem can be addressed with detailed, high-resolution numerical studies of perturbed heavy, overpressured jets. The latter should benefit from high-resolution X-ray imaging of the inner arcminute of the Her A region to understand better the structure of the ambient medium and to determine what influence, if any, it may have on the jet flow. C1 AGNES SCOTT COLL,BRADLEY OBSERV,DECATUR,GA 30030. USN,RES LAB,CTR ADV SPACE SENSING,WASHINGTON,DC 20375. RP MEIER, DL (reprint author), CALTECH,JET PROP LAB,238-700,4800 OAK GROVE,PASADENA,CA 91109, USA. NR 20 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 SEP 20 PY 1991 VL 379 IS 1 BP 141 EP 156 DI 10.1086/170491 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GF749 UT WOS:A1991GF74900013 ER PT J AU STEVENS, IR AF STEVENS, IR TI X-RAY-ILLUMINATED STELLAR WINDS - OPTICALLY THICK WIND MODELS FOR MASSIVE X-RAY BINARIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS - NEUTRON; STARS - WINDS; X-RAYS - BINARIES ID RADIATION-DRIVEN WINDS; VELA X-1; O-STAR; ACCRETION; SYSTEMS; ULTRAVIOLET; ATMOSPHERES; IONIZATION AB In massive X-ray binary systems (MXRBs), such as Vela X-1, the accretion-powered X-rays from the neutron star will alter the dynamics of the line-driven stellar wind of the early-type primary, by changing both the thermal and the ionization structure of the wind material. In a previous paper, Stevens and Kallman investigated this effect, neglecting optical depth effects in the transfer of X-rays through the stellar wind material. In this paper we extend this work and calculate radiative force multipliers M(t, xi, N(H)) that now depend on the column of attenuating material N(H), as well as the ionization parameter xi. Optical depth effects tend to suppress the effects of X-ray ionization on the force multipliers. We have calculated a number of dynamical models for the winds of MXRBs with these force multipliers. In contrast to the optically thin models, we were able to find self-consistent dynamical solutions for reasonable values of the X-ray luminosity L(x). These solutions also reveal the presence of nonlinear mechanisms that affect the wind dynamics, whereby relatively small changes in the force multipliers can lead to large changes in the wind structure. The models find the existence of a self-consistent region of solution at an X-ray luminosity of L(x) approximately 10(36) ergs s-1, and suggest the possible existence of high-luminosity states. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NR 35 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1991 VL 379 IS 1 BP 310 EP 326 DI 10.1086/170506 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GF749 UT WOS:A1991GF74900028 ER PT J AU BLAIR, WP LONG, KS VANCURA, O BOWERS, CW DAVIDSEN, AF DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KIMBLE, RA KRISS, GA KRUK, JW MOOS, HW GULL, TR AF BLAIR, WP LONG, KS VANCURA, O BOWERS, CW DAVIDSEN, AF DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KIMBLE, RA KRISS, GA KRUK, JW MOOS, HW GULL, TR TI DISCOVERY OF A FAST RADIATIVE SHOCK-WAVE IN THE CYGNUS LOOP USING THE HOPKINS-ULTRAVIOLET-TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, INDIVIDUAL (CYGNUS LOOP); NEBULAE, SUPERNOVA REMNANTS; SHOCK WAVES; ULTRAVIOLET, SPECTRA ID SUPERNOVA REMNANT; MODELS AB We have observed the far-ultraviolet spectrum of a bright radiative filament on the eastern edge of the Cygnus Loop supernova remnant using the Hopkins Ultraviolet Telescope aboard the Astro-1 space shuttle mission in 1990 December. These are the first data to resolve the sub-Lyman-alpha emission of an interstellar shock wave. We observe strong emission lines of C III lambda-977, N III lambda-991, and O VI lambda-lambda-1032, 1038 and many fainter lines, as well as lines seen above Lyman-alpha in IUE spectra of supernova remnants. Comparison of this spectrum with shock model calculations indicates that the emission at this position in the Cygnus Loop is dominated by a approximately 170 km s-1 shock wave, although emission from lower shock velocities may also contribute. Both faster and slower shocks have been identified in the Cygnus Loop, but little attention has been given to the possible presence and importance of fast radiative shocks such as the one reported here. We briefly compare these results to Voyager UVS spectra of the Cygnus Loop and discuss the more global implications of these data for the understanding of the Cygnus Loop. C1 UNIV CAMBRIDGE OBSERV,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP BLAIR, WP (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CHARLES & 34TH ST,BALTIMORE,MD 21218, USA. RI Gull, Theodore/D-2753-2012; Kruk, Jeffrey/G-4047-2012 OI Gull, Theodore/0000-0002-6851-5380; NR 18 TC 49 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1991 VL 379 IS 1 BP L33 EP & DI 10.1086/186147 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GF750 UT WOS:A1991GF75000008 ER PT J AU FELDMAN, PD DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FERGUSON, HC HENRY, RC KIMBLE, RA KRISS, GA KRUK, JW LONG, KS MOOS, HW VANCURA, O GULL, TR AF FELDMAN, PD DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FERGUSON, HC HENRY, RC KIMBLE, RA KRISS, GA KRUK, JW LONG, KS MOOS, HW VANCURA, O GULL, TR TI OBSERVATIONS OF COMET LEVY (1990C) WITH THE HOPKINS-ULTRAVIOLET-TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS; ULTRAVIOLET, SPECTRA ID P/HALLEY; N-2 AB Observations of comet Levy (1990c) were made with the Hopkins Ultraviolet Telescope during the Astro-1 Space Shuttle mission on 1990 December 10. The spectrum, covering the wavelength range 415-1850 angstrom at a spectral resolution of 3 angstrom (in first order), shows the presence of carbon monoxide and atomic hydrogen, carbon, and sulfur in the coma. Aside from H I Lyman-beta, no cometary features are detected below 1200 angstrom, although cometary O I and O II would be masked by the same emissions present in the day airglow spectrum. The 9.4 x 116 arcsecond aperture corresponds to 12,000 x 148,000 km at the comet. The derived production rate of CO relative to water is 0.11 +/- 0.02, compared with 0.04 +/- 0.01 derived from IUE observations (made in 1990 September) which sample a much smaller region of the coma. This suggests the presence of an extended source of CO, as was found in comet Halley. Upper limits on Ne and Ar abundance are within one order of magnitude of solar abundances. C1 CAMBRIDGE UNIV OBSERV,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP FELDMAN, PD (reprint author), JOHNS HOPKINS UNIV,CTR ASTROPHYS SCI,DEPT PHYS & ASTRON,BALTIMORE,MD 21218, USA. RI Gull, Theodore/D-2753-2012; Kimble, Randy/D-5317-2012; Kruk, Jeffrey/G-4047-2012 OI Gull, Theodore/0000-0002-6851-5380; NR 23 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 SEP 20 PY 1991 VL 379 IS 1 BP L37 EP L40 DI 10.1086/186148 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GF750 UT WOS:A1991GF75000009 ER PT J AU PRUETT, CD STREETT, CL AF PRUETT, CD STREETT, CL TI A SPECTRAL COLLOCATION METHOD FOR COMPRESSIBLE, NON-SIMILAR BOUNDARY-LAYERS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE SPECTRAL COLLOCATION METHODS; COMPRESSIBLE FLOW; BOUNDARY LAYER EQUATIONS; STABILITY THEORY; TRANSVERSE CURVATURE AB An efficient and highly accurate algorithm based on a spectral collocation method is developed for numerical solution of the compressible, two-dimensional and axisymmetric boundary layer equations. The numerical method incorporates a fifth-order, fully implicit marching scheme in the streamwise (timelike) dimension and a spectral collocation method based on Chebyshev polynomial expansions in the wall-normal (spacelike) dimension. The discrete governing equations are cast in residual form and the residuals are minimized at each marching step by a preconditioned Richardson iteration scheme which fully couples energy, momentum and continuity equations. Preconditioning on the basis of the finite difference analogues of the governing equations results in a computationally efficient iteration with acceptable convergence properties. A practical application of the algorithm arises in the area of compressible linear stability theory, in the investigation of the effects of transverse curvature on the stability of flows over axisymmetric bodies. The spectral collocation algorithm is used to derive the non-similar mean velocity and temperature profiles in the boundary layer of a 'fuselage' (cylinder) in a high-speed (Mach 5) flow parallel to its axis. The stability of the flow is shown to be sensitive to the gradual streamwise evolution of the mean flow and it is concluded that the effects of transverse curvature on stability should not be ignored routinely. RP PRUETT, CD (reprint author), NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,MAIL STOP 156,HAMPTON,VA 23665, USA. NR 18 TC 26 Z9 26 U1 0 U2 4 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD SEP 20 PY 1991 VL 13 IS 6 BP 713 EP 737 DI 10.1002/fld.1650130605 PG 25 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA GG012 UT WOS:A1991GG01200004 ER PT J AU MLYNCZAK, MG AF MLYNCZAK, MG TI NONLOCAL THERMODYNAMIC-EQUILIBRIUM PROCESSES IN OZONE - IMPLICATIONS FOR THE ENERGY BUDGET OF THE MESOSPHERE AND LOWER THERMOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TERRESTRIAL MIDDLE ATMOSPHERE; INFRARED LIMB EMISSION; 3-BODY RECOMBINATION; DYNAMICS; SPECTROSCOPY; KINETICS AB The conversion of chemical potential energy and infrared radiative energy to kinetic energy by nonlocal thermodynamic equilibrium (non-LTE) processes involving ozone is a potentially significant source of heat in the terrestrial upper mesosphere and lower thermosphere. Heating rates in excess of 6 K d-1 could occur near the mesopause if all potential energy is converted to heat. Calculation of the heating rate requires knowledge of the processes which convert chemical potential energy to internal energy of ozone during the exothermic recombination reaction that forms ozone. In addition, the rates at which ozone exchanges internal energy with its surroundings through collisional and radiative processes must be known. The lack of a detailed data base of kinetic and spectroscopic information limits the ability to accurately model the heating by ozone. Therefore heating rates are calculated and compared using two different statistical equilibrium models previously applied in the analysis of measurements of limb emission from ozone. The calculated heating depends strongly on the assumed distribution and relaxation of energy in the quasi-nascent ozone molecule. Finally, in the absence of a detailed data base of rate coefficients it may be possible to estimate the heating rate due to non-LTE processes in ozone from appropriate satellite measurements of the ozone concentration and of the infrared emission from ozone in the 9-12-mu-m spectral interval. RP MLYNCZAK, MG (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 401B, HAMPTON, VA 23665 USA. RI Mlynczak, Martin/K-3396-2012 NR 22 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17217 EP 17228 DI 10.1029/91JD01833 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500009 ER PT J AU HERMAN, JR MCPETERS, R STOLARSKI, R LARKO, D HUDSON, R AF HERMAN, JR MCPETERS, R STOLARSKI, R LARKO, D HUDSON, R TI GLOBAL AVERAGE OZONE CHANGE FROM NOVEMBER 1978 TO MAY 1990 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INSTRUMENT; DEPLETION; TREND AB A recent recalibration and reprocessing of the total ozone mapping spectrometer (TOMS) data have made possible a new determination of the global average (69-degrees-S to 69-degrees-N) total ozone decrease of 3.5% over the 11-year period, January 1, 1979, to December 31, 1989, with a 2-sigma error of 1.4%. The revised TOMS ozone trend data are in agreement, within error limits, with the average of 39 ground-based Dobson stations and with the world standard Dobson spectrometer 83 at Mauna Loa, Hawaii. Superimposed on the 11-year ozone trend is a possible solar cycle effect, quasi-biennial oscillation (QBO), annual, and semiannual cycles. Using solar 10.7-cm flux data and 30-mbar Singapore wind data (QBO), a time series has been constructed that reproduces the long-term behavior of the globally averaged ozone. Removal of the apparent solar cycle effect from the global average reduces the net ozone loss to 2.66 +/- 1.4% per decade. The precise value of the global average ozone trend depends on the latitude range selected, with ranges greater than +/- 69-degrees emphasizing the larger variations at high latitudes. C1 ST SYST CORP, LANHAM, MD 20706 USA. UNIV MARYLAND, DEPT METEOROL, COLLEGE PK, MD 20742 USA. RP HERMAN, JR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI Stolarski, Richard/B-8499-2013; McPeters, Richard/G-4955-2013 OI Stolarski, Richard/0000-0001-8722-4012; McPeters, Richard/0000-0002-8926-8462 NR 17 TC 23 Z9 23 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17297 EP 17305 DI 10.1029/91JD01553 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500014 ER PT J AU BOUGHNER, RE CALLIS, LB NATARAJAN, M AF BOUGHNER, RE CALLIS, LB NATARAJAN, M TI SENSITIVITY OF CALCULATED ODD NITROGEN DISTRIBUTIONS TO THE DIABATIC WIND FIELDS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRACE GASES; NITRIC-ACID; STRATOSPHERE; N2O; CIRCULATION; LATITUDES; TRANSPORT; NIMBUS-7; CF2CL2; RATES AB Two-dimensional and three-dimensional model calculations are known to give stratospheric total odd nitrogen (NO(y) = N + NO + NO2 + 2xN2O5 + HNO3 + HNO4 + ClONO2) mixing ratios which are significantly smaller than values inferred using measurements obtained from the limb infrared monitor of the stratosphere (LIMS) instrument. We examine NO(y) distributions calculated with two different advective transport fields, one derived from reported climatological data and one derived from LIMS T, O3, and H2O data. Specifically, it is of interest to see if the use of the advective fields derived from the LIMS data leads to a reconciliation of the inferred and calculated NO(y) distributions. Calculations with the advective field derived from climatological data show stronger poleward and downward motion in the winter season compared to the advective field derived from LIMS data. This leads to NO(y) mixing ratios in the lower stratosphere that are about 20% larger in the polar regions of both hemispheres and approximately 40% higher in the equatorial region for climatological transport fields compared to those derived from LIMS data. As a consequence, the NO(y) distributions calculated in the present model with the LIMS advective field show worse agreement with NO(y) values inferred from the LIMS measurements than similar results obtained with the climatological wind field. Ozone levels in the lower stratosphere calculated with the climatological wind field are smaller than those computed with the LIMS wind field, which is most likely an indirect chemical effect associated with the larger NO(y) values. C1 STX CORP, HAMPTON, VA USA. RP BOUGHNER, RE (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 28 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17315 EP 17327 DI 10.1029/91JD01922 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500016 ER PT J AU COFER, WR PURGOLD, GC WINSTEAD, EL EDAHL, RA AF COFER, WR PURGOLD, GC WINSTEAD, EL EDAHL, RA TI SPACE-SHUTTLE EXHAUSTED ALUMINUM-OXIDE - A MEASURED PARTICLE-SIZE DISTRIBUTION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Note ID SOLID-FUELED ROCKETS; CLOUD NUCLEI; EFFLUENTS; CHLORIDE; LAUNCHES AB Aluminum oxide (A2O3) particles were collected from the space shuttle exhaust plume immediately following the launch of STS-34 on October 18, 1989. A2O3 samples were obtained at 2.4, 3.0, 3.2, and 7.4 km in altitude. The samples were analyzed using scanning electron microscopy to develop particle size distributions. There were no indications that the particle size distribution changed as a function of altitude. The particle number concentrations per cubic meter of air sampled (N(C)) for the four collections was found to fit the exponential expression N(C) = (3.2 x 10(8))10(-0.89d), where d is particle diameter in micrometers, over the interval of 0.3-7-mu-m. The mass median diameter for this distribution occurred at about 4-mu-m. C1 NASA, LANGLEY RES CTR, DIV MAT, HAMPTON, VA 23665 USA. ST SYST CORP, HAMPTON, VA 23666 USA. RP COFER, WR (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 28 TC 12 Z9 12 U1 3 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17371 EP 17376 DI 10.1029/91JD01713 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500023 ER PT J AU MCPETERS, R PRATHER, M DOIRON, S AF MCPETERS, R PRATHER, M DOIRON, S TI THE SPACE SHUTTLES IMPACT ON THE STRATOSPHERE - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Letter C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. ST SYST CORP, LANHAM, MD 20706 USA. RP MCPETERS, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 2 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17379 EP 17381 DI 10.1029/91JD01926 PG 3 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500025 ER PT J AU SPIVAKOVSKY, CM YEVICH, R LOGAN, JA WOFSY, SC MCELROY, MB PRATHER, MJ AF SPIVAKOVSKY, CM YEVICH, R LOGAN, JA WOFSY, SC MCELROY, MB PRATHER, MJ TI TROPOSPHERIC OH IN A 3-DIMENSIONAL CHEMICAL TRACER MODEL - AN ASSESSMENT BASED ON OBSERVATIONS OF CH3CCL3 - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Letter C1 HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP SPIVAKOVSKY, CM (reprint author), HARVARD UNIV, DIV APPL SCI, CAMBRIDGE, MA 02138 USA. RI 欧阳, 冰洁/G-2925-2011 NR 2 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17389 EP 17390 DI 10.1029/91JD01670 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500027 ER PT J AU PFISTER, L RUSSELL, PB DANIELSEN, EF WATSON, RT AF PFISTER, L RUSSELL, PB DANIELSEN, EF WATSON, RT TI SPECIAL SECTION - THE STRATOSPHERE-TROPOSPHERE EXCHANGE PROJECT (STEP) - PREFACE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Editorial Material RP PFISTER, L (reprint author), NASA, AMES RES CTR, MS 245-5, MOFFETT FIELD, CA 94035 USA. NR 0 TC 1 Z9 1 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17400 EP 17400 DI 10.1029/91JD01970 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500030 ER PT J AU RUSSELL, PB DANIELSEN, EF CRAIG, RA SELKIRK, HB AF RUSSELL, PB DANIELSEN, EF CRAIG, RA SELKIRK, HB TI THE NASA SPRING 1984 STRATOSPHERE-TROPOSPHERE EXCHANGE EXPERIMENT - SCIENCE OBJECTIVES AND OPERATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-MONOXIDE; TROPOPAUSE; OZONE AB We present an overview of the first experiment of the Stratosphere-Troposphere Exchange Project (STEP), conducted in spring 1984 over the southwestern United States. The objective was to identify modes of transport during large-scale cyclogenesis, both (1) within the stratosphere, from the anticyclonic to the cyclonic side of the jet, and (2) from the troposphere to the stratosphere. The primary platform was the NASA U-2 high-altitude research aircraft, supported by the regular twice-daily radiosonde network. Measurements included temperature, pressure, horizontal wind, ozone, cosmogenic radionuclides, water vapor, and condensation nuclei. U-2 flights were made on 4 days. On 3 days the flight path was in a vertical plane orthogonal to the jet stream flow, extending from the anticyclonic side of the jet, across it, and into the cyclonic vortex. The other flight was directed at processes associated with the upper level cirrus outflow from a tropical vortex. Aircraft direction was performed using analysis of NMC prognostications, commercial diagnostics and predictions, radiosonde data, and satellite infrared imagery. The cross-jet flight most intensively analyzed (April 20-21, 1984) was coordinated with simultaneous flights in the troposphere and lower stratosphere made by the NASA CV-990 and Electra as a part of the Global Tropospheric Experiment. This paper briefly reviews the U-2 instrument payload, shows the flight paths of April 20-21 and May 6 in relation to the respective meteorological situations, and reviews the procedures used to predict large-scale cyclogenesis and associated tropopause folding and to direct the aircraft. The following papers report the measurement data and interpret the results in terms of reversible and irreversible cross-jet transport mechanisms. RP RUSSELL, PB (reprint author), NASA, AMES RES CTR, MAIL CODE SGG 245-5, MOFFETT FIELD, CA 94035 USA. RI Selkirk, Henry/H-2021-2012 NR 10 TC 7 Z9 7 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17401 EP 17404 DI 10.1029/91JD01359 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500031 ER PT J AU KRITZ, MA ROSNER, SW DANIELSEN, EF SELKIRK, HB AF KRITZ, MA ROSNER, SW DANIELSEN, EF SELKIRK, HB TI AIR-MASS ORIGINS AND TROPOSPHERE-TO-STRATOSPHERE EXCHANGE ASSOCIATED WITH MIDLATITUDE CYCLOGENESIS AND TROPOPAUSE FOLDING INFERRED FROM BE-7 MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The 1984 extratropical mission of NASA's Stratosphere-Troposphere Exchange Project (STEP) studied cross-jet transports in regions of cyclogenesis and tropopause folding. Correlations of Be-7, ozone, water vapor, and potential vorticity measured on a NASA U-2 research aircraft flying in high shear regions above the jet core are indicative of mixing between the cyclonic and the anticyclonic sides of the jet and are consistent with the hypothesis that small-scale entrainments of upper tropospheric air into the lower stratosphere during cyclogenesis are important in maintaining the vertical gradients of Be-7, ozone, water vapor and other trace constituents in the lower few kilometers of the mid-latitude stratosphere. Correlations between Be-7 and ozone suggest a lower tropical stratospheric origin for the ozone-poor lamina observed above the jet core. C1 NASA, AMES RES CTR, DIV EARTH SYST SCI, MOFFETT FIELD, CA 94035 USA. NASA, AMES RES CTR, ATMOSPHER CHEM & DYNAM BRANCH, MOFFETT FIELD, CA 94035 USA. RP KRITZ, MA (reprint author), SUNY ALBANY, ATMOSPHER SCI RES CTR, ALBANY, NY 12222 USA. RI Selkirk, Henry/H-2021-2012 NR 17 TC 37 Z9 39 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17405 EP 17414 DI 10.1029/91JD01358 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500032 ER PT J AU CHAN, KR SCOTT, SG BOWEN, SW GAINES, SE DANIELSEN, EF PFISTER, L AF CHAN, KR SCOTT, SG BOWEN, SW GAINES, SE DANIELSEN, EF PFISTER, L TI HORIZONTAL WIND FLUCTUATIONS IN THE STRATOSPHERE DURING LARGE-SCALE CYCLOGENESIS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INERTIA-GRAVITY-WAVES; TROPOSPHERE; RADAR AB The meteorological measurement system (MMS) on the U-2 aircraft measured pressure, temperature, and the horizontal wind during a cyclogenesis event over western United States on April 20, 1984. The aircraft flew above the jet core and traversed in a vertical plane normal to the jet stream axis at four altitudes, making measurements on both the cyclonic and anticyclonic sides of the jet. Horizontal wind data were processed by digital filters to permit analyses of large-scale gradients and of small-scale fluctuations. The mean horizontal wind in the stratosphere decreases monotonically with altitude. Superimposed on the mean stratospheric wind is a perturbation wind vector, which is an elliptically polarized wave with an amplitude of 4 to 10 m s-1 and a vertical wavelength of 2 to 3 km. The perturbation wind vector rotates anticyclonically (clockwise) with altitude and produces alternating advection in the plane of the aircraft flight path. This differential advection folds surfaces of constant tracer mixing ratio and contributes to the observed tracer laminar structures and inferred cross-jet transport. C1 STERLING SOFTWARE, PALO ALTO, CA 94043 USA. SAN JOSE STATE UNIV, SAN JOSE, CA 95192 USA. RP CHAN, KR (reprint author), NASA, AMES RES CTR, MS 245-5, MOFFETT FIELD, CA 94035 USA. NR 22 TC 9 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17425 EP 17432 DI 10.1029/91JD01360 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500034 ER PT J AU DANIELSEN, EF HIPSKIND, RS STARR, WL VEDDER, JF GAINES, SE KLEY, D KELLY, KK AF DANIELSEN, EF HIPSKIND, RS STARR, WL VEDDER, JF GAINES, SE KLEY, D KELLY, KK TI IRREVERSIBLE TRANSPORT IN THE STRATOSPHERE BY INTERNAL WAVES OF SHORT VERTICAL WAVELENGTH SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The U-2 aircraft was instrumented and flown in the stratosphere during the Stratosphere-Troposphere Exchange Project's experiments of April 1984 to provide a set of simultaneous measurements by fast responding sensors that would aid in the identification of the modes of cross-jet transport. The measurements confirm the preexperimental deductions that transport is dominated by waves, not by large-scale circulations. Monotonic gradients of trace constituents normal to the jet axis, with upper stratospheric tracers increasing poleward and tropospheric tracers increasing equatorward, are augmented by large-scale confluence as the jet intensifies during cyclogenesis. These gradients are rotated, intensified, and significantly increased in area as their mixing ratio surfaces are folded by the differential transport of a very low frequency, transverse wave. The quasi-horizontal transport produces a laminar structure with stable layers rich in upper stratospheric tracers alternating vertically with less stable layers rich in tropospheric tracers. The transport proceeds toward irreversibility as higher frequency, shear-gravity waves extend the folding to smaller horizontal scales. It becomes irreversible when these short waves actually fold the isentropic surfaces and small-scale mixing develops. The progression to higher wave numbers is a discrete, not a continuous, cascade with major gaps in the observed horizontal wavelengths. The wave modes are identified by matching the observed amplitudes and phases against those obtained by linear perturbation theory. Prior to mixing, the wave-generated perturbations maintain the correlations produced by advecting the larger-scale mean gradients; thus the high resolution measurements support the linear turbulence closure assumption. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. STERLING SOFTWARE, PALO ALTO, CA 94043 USA. FORSCHUNGSZENTRUM JULICH, W-5170 JULICH 1, GERMANY. NOAA, AERON LAB, ENVIRONM RES LABS, BOULDER, CO 80303 USA. NR 28 TC 59 Z9 59 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1991 VL 96 IS D9 BP 17433 EP 17452 DI 10.1029/91JD01362 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GH375 UT WOS:A1991GH37500035 ER PT J AU SCHNEIDER, NM TRAUGER, JT WILSON, JK BROWN, DI EVANS, RW SHEMANSKY, DE AF SCHNEIDER, NM TRAUGER, JT WILSON, JK BROWN, DI EVANS, RW SHEMANSKY, DE TI MOLECULAR-ORIGIN OF IOS FAST SODIUM SO SCIENCE LA English DT Article ID ATMOSPHERIC ESCAPE; PLASMA; MODELS; IMPACT; TORUS; ATOMS; CLOUD AB Neutral sodium emissions encircling Jupiter exhibit an intricate and variable structure that is well matched by a simple loss process from Io's atmosphere. These observations imply that fast neutral sodium is created locally in the lo plasma torus, both near Io and as much as 8 hours downstream. Sodium-bearing molecules may be present in Io's upper atmosphere, where they are ionized by the plasma torus and swept downstream. The molecular ions dissociate and dissociatively recombine on a short time scale, releasing neutral fragments into escape trajectories from Jupiter. This theory explains a diverse set of sodium observations, and it implies that molecular reactions (particularly electron impact ionization and dissociation) are important at the top of Io's atmosphere. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP SCHNEIDER, NM (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. OI SCHNEIDER, NICHOLAS/0000-0001-6720-5519 NR 31 TC 47 Z9 47 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 20 PY 1991 VL 253 IS 5026 BP 1394 EP 1397 DI 10.1126/science.253.5026.1394 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GF851 UT WOS:A1991GF85100033 PM 17793479 ER PT J AU RAMATY, R LINGENFELTER, RE AF RAMATY, R LINGENFELTER, RE TI MILKY-WAY GALAXY - ANNIHILATION NEAR THE CENTER SO NATURE LA English DT Editorial Material ID GALACTIC-CENTER REGION; RADIATION; RAYS C1 UNIV CALIF SAN DIEGO, CTR ASTROPHYS & SPACE SCI, LA JOLLA, CA 92093 USA. RP RAMATY, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 16 TC 1 Z9 1 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 SEP 19 PY 1991 VL 353 IS 6341 BP 215 EP 216 DI 10.1038/353215a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GF674 UT WOS:A1991GF67400034 ER PT J AU SINHA, MP GUTNIKOV, G AF SINHA, MP GUTNIKOV, G TI DEVELOPMENT OF A MINIATURIZED GAS-CHROMATOGRAPH MASS-SPECTROMETER WITH A MICROBORE CAPILLARY COLUMN AND AN ARRAY DETECTOR SO ANALYTICAL CHEMISTRY LA English DT Article ID OPEN TUBULAR COLUMNS; SPEED AB A miniaturized focal plane mass spectrograph with an array detector is demonstrated to measure multiple mass spectra from narrow GC peaks eluted from a short microbore capillary column (50-mu-m i.d., 3 m in length). The GC peaks of dichlorodifluoromethane, chloromethane, bromomethane, and chloroethane from a mixture of compounds are found to have full width at half-maximum in the range 200-300 ms and are separated by approximately 700 ms. The simultaneous measurement of all ions by the array detector enables mass spectral measurements of these peaks possible without affecting the GC resolution and the sensitivity of the mass spectrograph. The system is shown to possess high sensitivity (e.g., 7.5 x 10(-14) g for benzene) and a linear dynamic range of > 10(3). A microbore capillary column requires an extremely small carrier gas flow rate (approximately 0.05 atm cm3 min-1 for helium) and drastically reduces the weight and power needs of the mass spectrograph. The combination of such a column with a miniaturized focal plane mass spectrograph is thus uniquely suited for the development of a field-portable, high-performance GC-MS system. C1 CALIF STATE POLYTECH UNIV POMONA,DEPT CHEM,POMONA,CA 91768. RP SINHA, MP (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 18 TC 33 Z9 34 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD SEP 15 PY 1991 VL 63 IS 18 BP 2012 EP 2016 DI 10.1021/ac00018a021 PG 5 WC Chemistry, Analytical SC Chemistry GA GE858 UT WOS:A1991GE85800021 ER PT J AU GREEN, S AF GREEN, S TI PRESSURE BROADENING DATA AS A TEST OF A RECENTLY PROPOSED AR-H2O INTERACTION POTENTIAL SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SYMMETRIC TOP MOLECULES; SCATTERING CALCULATIONS; PERTURBER DEPENDENCES; ROTATIONAL EXCITATION; COUPLED STATES; LINE-SHAPES; CO-HE; AR; TEMPERATURE; SPECTROSCOPY AB An interaction potential for H2O-Ar that was recently determined from spectra of the van der Waals complex [R. C. Cohen and R. J. Saykally, J. Chem. Phys. 94, 7991 (1990)] is used with accurate molecular scattering calculations to predict line broadening parameters for the 183 and 380 GHz transitions of water vapor. Theoretical values are about 15% higher than experiment. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 18 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 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 15 PY 1991 VL 95 IS 6 BP 3888 EP 3890 DI 10.1063/1.460795 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA GF099 UT WOS:A1991GF09900003 ER PT J AU BISHOP, JKB ROSSOW, WB AF BISHOP, JKB ROSSOW, WB TI SPATIAL AND TEMPORAL VARIABILITY OF GLOBAL SURFACE SOLAR IRRADIANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID CLOUD-CLIMATOLOGY-PROJECT; SATELLITE DATA; PHYTOPLANKTON GROWTH; PACIFIC-OCEAN; MODEL; RADIATION; LIGHT; ISCCP; COMPUTATIONS; ABSORPTION AB A fast scheme for computing surface solar irradiance using data from the International Satellite Cloud Climatology Project (ISCCP) is described. Daily mean solar irradiances from the fast scheme reproduce the detailed global results from full radiative transfer model calculations to within 6 and 10 W m-2 over the ocean and land, respectively. In particular, the fast scheme reproduces the same dependence of surface irradiance on solar zenith angle which is critical for proper calculation of daily, seasonal, and latitudinal variability. Validation of both model results is limited because globally distributed data sets of high quality are lacking, particularly over the oceans. However, comparison of calculated monthly mean results using 5 months of ISCCP data (July 1983 to July 1984) with climatology from the 1970s at six temperate latitude ocean weather stations shows agreement within published estimates of interannual variability of monthly means at the individual stations. A further test against a 17-day time series at a continental site (43-degrees-N, 90-degrees-W, October-November 1986; 13-170 W m-2 range of irradiance), where ground and satellite data were spatially and temporally coincident, showed an accuracy of better than 9 W m-2 on a daily basis and less than 4% bias in the 17-day mean. Frequently used bulk formulae for solar irradiance were also evaluated in each of these tests. All suffered in comparison because they did not include a parameterization of the effects of the global variability in mean cloud optical thickness. Data from July (1983 and 1984) and January (1984 and 1985) were used to examine the spatial and temporal variability of surface irradiance and its potential impact on biospheric processes. Results show that the oceans and land experience fundamentally different light regimes, with continents receiving significantly greater irradiance. In summer, major interocean differences in zonally averaged irradiance are found in the northern hemisphere with the Atlantic greater than Pacific by up to 80 W m-2; in the southern hemisphere, interocean differences are small. Regional interannual variability (July 1983 versus 1984) ranged between +100 and -100 W m-2. The variability, perhaps due to the 1982-1983 El Nino event, occurred mostly in the Pacific but extended beyond the tropics over the entire north Pacific basin. The nutrient-rich northern and southern ocean waters are almost perpetually cloud covered; however, there is a correspondence between higher than average surface irradiance and productivity in nutrient-rich areas of the southwest Atlantic and Weddell Sea sector of the circumpolar current. This suggests that solar irradiance must be considered as an important factor governing the productivity of these waters. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP BISHOP, JKB (reprint author), COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964, USA. RI Rossow, William/F-3138-2015 NR 53 TC 213 Z9 213 U1 2 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 SEP 15 PY 1991 VL 96 IS C9 BP 16839 EP 16858 DI 10.1029/91JC01754 PG 20 WC Oceanography SC Oceanography GA GG239 UT WOS:A1991GG23900013 ER PT J AU CARTWRIGHT, DE RAY, RD AF CARTWRIGHT, DE RAY, RD TI ENERGETICS OF GLOBAL OCEAN TIDES FROM GEOSAT ALTIMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ELASTIC EARTH; TIDAL ENERGY; NORMAL-MODES; WORLD OCEAN; MISSION; ORBIT; M2; S2; DISSIPATION; DEFORMATION AB The authors' global ocean tide maps derived from Geosat altimetry are here improved in quality and coverage; they compare favorably with ground truth data at about the same rms level as Schwiderski's models, slightly better in lunar than in solar tides. Diurnal admittances clearly show Kelvin wave structure in the southern ocean and confirm Platzman's resonant mode at 28.5 +/- 0.1 hours with an apparent Q of about 4. Driving energy enters dominantly in the North Pacific for the daily tides and is strongly peaked in the tropical oceans for the half-daily tides. Global rates of working on all major tide constituents except S2 agree well with independent results from analyses of gravity through satellite tracking. Comparison at S2 is improved by allowing for the air tide in gravitational results but suggests deficiencies in all solar tide models. Estimates of Q factors based on potential energy (approximately 8 for daily tides and 13 for half-daily tides) agree reasonably well with hydrodynamic models. C1 NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,GREENBELT,MD 20771. RI Ray, Richard/D-1034-2012 NR 49 TC 114 Z9 118 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-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1991 VL 96 IS C9 BP 16897 EP 16912 DI 10.1029/91JC01059 PG 16 WC Oceanography SC Oceanography GA GG239 UT WOS:A1991GG23900016 ER PT J AU SMITH, JR PERRY, T BANERJEA, A FERRANTE, J BOZZOLO, G AF SMITH, JR PERRY, T BANERJEA, A FERRANTE, J BOZZOLO, G TI EQUIVALENT-CRYSTAL THEORY OF METAL AND SEMICONDUCTOR SURFACES AND DEFECTS SO PHYSICAL REVIEW B LA English DT Article ID EMBEDDED-ATOM-METHOD; TOTAL-ENERGY CALCULATIONS; OSCILLATORY RELAXATION; TRANSITION-METALS; MULTILAYER RELAXATION; UNIVERSAL FEATURES; CU(110) SURFACE; AL(110) SURFACE; INTERNAL STRAIN; ELECTRON AB A method is proposed for computing material defect and surface properties accurately at the atomic level. The method is both simple and accurate and treats both semiconductors and metals. Lattice defect and surface energies are determined via perturbation theory on a crystal whose lattice constant is chosen to minimize the perturbation. The energy of the equivalent crystal as a function of its lattice constant is given by a universal energy relation. This simple method is tested via predictions of surface energies, surface reconstructions, and bulk distortions of metals and semiconductors. Good agreement is obtained with the results of both experiment and first-principles calculations. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. KENT STATE UNIV, DEPT PHYS, KENT, OH 44242 USA. ANALEX CORP, FAIRVIEW PK, OH 44126 USA. RP GM CORP, RES LABS, DEPT PHYS, WARREN, MI 48090 USA. NR 68 TC 121 Z9 127 U1 0 U2 6 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD SEP 15 PY 1991 VL 44 IS 12 BP 6444 EP 6465 DI 10.1103/PhysRevB.44.6444 PG 22 WC Physics, Condensed Matter SC Physics GA GH553 UT WOS:A1991GH55300049 ER PT J AU KAISER, WJ HECHT, MH FATHAUER, RW BELL, LD LEE, EY DAVIS, LC AF KAISER, WJ HECHT, MH FATHAUER, RW BELL, LD LEE, EY DAVIS, LC TI BALLISTIC-CARRIER SPECTROSCOPY OF THE COSI2/SI INTERFACE SO PHYSICAL REVIEW B LA English DT Note ID ELECTRON-EMISSION MICROSCOPY; TRANSISTOR; SILICIDES; EPITAXY; BAND AB Ballistic-electron-emission microscopy and related ballistic-hole and carrier-scattering spectroscopies have been used to investigate carrier transport in the expitaxial CoSi2/Si system. An unexpected degree of variation in interface transmission is observed despite the high crystal quality of the epitaxial silicide layer. Furthermore, clear evidence of the CoSi2 band structure is observed, which has a dramatic effect on interface transport. The major effect of the silicide band structure is to increase the interfacial barrier to electron transmission to a value in excess of the Schottky barrier height. C1 RENSSELAER POLYTECH INST,DEPT PHYS,TROY,NY 12180. RENSSELAER POLYTECH INST,CTR INTEGRATED ELECTR,TROY,NY 12180. FORD MOTOR CO,SCI RES STAFF,DEARBORN,MI 48121. RP KAISER, WJ (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 16 TC 40 Z9 40 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD SEP 15 PY 1991 VL 44 IS 12 BP 6546 EP 6549 DI 10.1103/PhysRevB.44.6546 PG 4 WC Physics, Condensed Matter SC Physics GA GH553 UT WOS:A1991GH55300066 ER PT J AU GRADWOHL, BA AF GRADWOHL, BA TI COSMIC SUPERFLUID PHASE SO PHYSICAL REVIEW D LA English DT Article ID REDSHIFT-DISTANCE SAMPLES; GOLDSTONE BOSONS; GLOBAL STRINGS; ELLIPTICAL GALAXIES; DENSITY FIELDS; EARLY UNIVERSE; ORIGIN; SPECTROSCOPY; BARYOGENESIS; PHOTOMETRY AB The Universe may have undergone a superfluidlike phase during its evolution, resulting from the injection of nontopological charge into the spontaneously broken vacuum. In the presence of vortices this charge is identified with angular momentum. This leads to turbulent domains on the scale of the correlation length. By restoring the symmetry at low temperatures the vortices dissociate and push the charges to the boundaries of these domains. If we (phenomenologically) scale our model to very low energies, we can incorporate it in a late-time phase transition and form large-scale structure in the boundary layers of the correlation volumes. The novel feature of our model lies in the fact that the dark matter is endowed with coherent motion. We elaborate on the possibilities of identifying this flow around superfluid vortices with the observed large-scale bulk motion. If this identification is possible, then we can make the definite prediction that a more extended map of peculiar velocities would have to reveal large-scale circulations in the flow pattern. RP GRADWOHL, BA (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 43 TC 6 Z9 6 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1991 VL 44 IS 6 BP 1685 EP 1690 DI 10.1103/PhysRevD.44.1685 PG 6 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA GG502 UT WOS:A1991GG50200009 ER PT J AU BOWCOCK, P GREGORY, R AF BOWCOCK, P GREGORY, R TI MULTIDIMENSIONAL TUNNELING AND COMPLEX MOMENTUM SO PHYSICAL REVIEW D LA English DT Article ID COUPLED ANHARMONIC OSCILLATORS; FALSE-VACUUM DECAY; TRAVERSAL TIME; TRANSMISSION; REFLECTION; INFLATION AB We examine the problem of modeling tunneling phenomena in more than one dimension. We find that existing techniques are inadequate in a wide class of situations because of their inability to deal with concurrent classical motion. We show how to generalize these methods to allow for complex momenta, and demonstrate the improved techniques with a selection of illustrative examples. We comment on possible applications. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP BOWCOCK, P (reprint author), UNIV CHICAGO,ENRICO FERMI INST,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 21 TC 14 Z9 14 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1991 VL 44 IS 6 BP 1774 EP 1785 DI 10.1103/PhysRevD.44.1774 PG 12 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA GG502 UT WOS:A1991GG50200019 ER PT J AU CRISP, D ALLEN, DA GRINSPOON, DH POLLACK, JB AF CRISP, D ALLEN, DA GRINSPOON, DH POLLACK, JB TI THE DARK SIDE OF VENUS - NEAR-INFRARED IMAGES AND SPECTRA FROM THE ANGLO-AUSTRALIAN-OBSERVATORY SO SCIENCE LA English DT Article ID HEATING RATES; NIGHT-SIDE; RADIATIVE-TRANSFER; LINE PARAMETERS; ENERGY-LEVELS; SOLAR FLUXES; ATMOSPHERE; INTENSITIES; GREENHOUSE; MESOSPHERE AB Near-infrared images and spectra of the night side of Venus taken at the Anglo-Australian Telescope during February 1990 reveal four new thermal emission windows at 1.10, 1.18, 1.27, and 1.31 micrometers (mu-m), in addition to the previously discovered windows at 1.74 and 2.3-mu-m. Images of the Venus night side show similar bright and dark markings in all windows, but their contrast is much lower at short wavelengths. The 1.27-mu-m window includes a bright, high-altitude O2 airglow feature in addition to a thermal contribution from the deep atmosphere. Simulations of the 1.27- and 2.3-mu-m spectra indicate water vapor mixing ratios near 40 +/- 20 parts per million by volume between the surface and the cloud base. No large horizontal gradients in the water vapor mixing ratios were detected at these altitudes. C1 ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CRISP, D (reprint author), CALTECH,JET PROP LAB,MS 169-237,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 37 TC 63 Z9 64 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 13 PY 1991 VL 253 IS 5025 BP 1263 EP 1266 DI 10.1126/science.11538493 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GE689 UT WOS:A1991GE68900035 PM 11538493 ER PT J AU TAMURA, M GATLEY, I JOYCE, RR UENO, M SUTO, H SEKIGUCHI, M AF TAMURA, M GATLEY, I JOYCE, RR UENO, M SUTO, H SEKIGUCHI, M TI INFRARED POLARIZATION IMAGES OF STAR-FORMING REGIONS .1. THE UBIQUITY OF BIPOLAR STRUCTURE SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; NEBULAE, REFLECTION; NEBULAE, STRUCTURE; POLARIZATION; STARS, FORMATION ID HERBIG-HARO OBJECTS; YOUNG STELLAR OBJECTS; OPHIUCHUS DARK-CLOUD; H II REGIONS; REFLECTION NEBULA; MOLECULAR OUTFLOWS; MICRON POLARIZATION; CONTINUUM EMISSION; CARBON-MONOXIDE; NGC-7538 REGION AB The inefficiency of the stellar formation process leads rather generally to high residual dust densities, and so to the existence of infrared reflection nebulosity (IRN), in regions of star formation. Polarization images of several star-forming regions with mass outflows (GSS 30, S255, GL 5180, GL 2591, GGD 27, and NGC 7538) presented here (1) establish the universality of bipolarity and of shell or cavity structure in the IRN consistent with that of CO outflow, (2) identify the source of the mass outflow in each case, (3) show that the opening angle near this central source is large, and (4) demonstrate several instances of multiple shells, probably arising from episodic mass loss. Astrometry of 2.2-mu-m sources with arcsecond accuracy identifies the illuminating source of each IRN uniquely with a compact H II region or a bright IR source. The polarization images provide strong evidence for large-scale dust toroids around each of these sources. The density and mass of these disks are estimated from the extinction through the disk. C1 UNIV MASSACHUSETTS,AMHERST,MA 01003. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. NATL ASTRON OBSERV,MITAKA,TOKYO,JAPAN. RP TAMURA, M (reprint author), CALTECH,JET PROP LAB,MAIL STOP 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 85 TC 80 Z9 81 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1991 VL 378 IS 2 BP 611 EP & DI 10.1086/170462 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD781 UT WOS:A1991GD78100018 ER PT J AU SEO, ES ORMES, JF STREITMATTER, RE STOCHAJ, SJ JONES, WV STEPHENS, SA BOWEN, T AF SEO, ES ORMES, JF STREITMATTER, RE STOCHAJ, SJ JONES, WV STEPHENS, SA BOWEN, T TI MEASUREMENT OF COSMIC-RAY PROTON AND HELIUM SPECTRA DURING THE 1987 SOLAR MINIMUM SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS, GENERAL; PARTICLE ACCELERATION ID ENERGY-SPECTRA; SHOCK FRONTS; ACCELERATION; HELIOSPHERE; MODULATION; GALAXY AB The differential cosmic-ray proton and helium spectra have been measured during the 1987 solar minimum using a balloon-borne superconducting magnetic spectrometer launched from Prince Albert, Canada. The changing geomagnetic cutoff along the balloon trajectory was observed in the low-energy proton data to be about 25% below the nominal calculated values. The absolute particle fluxes were approximately equal to the highest fluxes observed at the previous solar minimum in 1977. Above 10 GV the observed spectra are represented by a power law in rigidity with spectral indices of 2.74 +/- 0.02 for protons and 2.68 +/- 0.03 for helium. The measurements above 200 MeV per nucleon are consistent with rigidity power-law interstellar spectra modulated with the solar modulation parameter phi = 500 MV. The energy dependence of the proton-to-helium ratio is consistent with rigidity power-law injection spectra and rigidity-dependent propagation without reacceleration. C1 LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. UNIV ARIZONA,DEPT PHYS,TUCSON,AZ 85721. NEW MEXICO STATE UNIV,PARTICLE ASTROPHYS LAB,LAS CRUCES,NM 88003. RP SEO, ES (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. OI Seo, Eun-Suk/0000-0001-8682-805X NR 59 TC 124 Z9 124 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1991 VL 378 IS 2 BP 763 EP 772 DI 10.1086/170477 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD781 UT WOS:A1991GD78100033 ER PT J AU JAHODA, K LAHAV, O MUSHOTZKY, RF BOLDT, E AF JAHODA, K LAHAV, O MUSHOTZKY, RF BOLDT, E TI CROSS-CORRELATION OF THE X-RAY-BACKGROUND WITH NEARBY GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; GALAXIES, CLUSTERING; X-RAYS, SOURCES ID LOCAL GROUP; SPECTRUM; SAMPLE; MOTION AB We have cross-correlated the diffuse 2-10 keV X-ray surface brightness (using the HEAO 1 A-2 data) with the galaxy surface density from the diameter-limited UGC and the ESO catalog. Although the galaxies are nearby (z < 0.03) and sample only a small fraction of the volume believed to produce the X-ray background, we present a statistically significant correlation. The "zero-lag" (for 17 square degree cells) cross-correlation and associated 1-sigma interval is W triple-overdot xg = (3 +/- 1) x 10(-3). We estimate the volume X-ray emissivity of the local universe, rho-x = (2.8 +/- 1.0) x 10(38) ergs s-1 Mpc-3, which implies that unevolved populations of X-ray sources correlated with present-epoch galaxies can contribute only 13% +/- 5% of the cosmic X-ray background. C1 UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. INST ADV STUDY,PRINCETON,NJ 08540. RP JAHODA, K (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 666,GREENBELT,MD 20771, USA. RI Jahoda, Keith/D-5616-2012 NR 23 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 SEP 10 PY 1991 VL 378 IS 2 BP L37 EP L40 DI 10.1086/186136 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD782 UT WOS:A1991GD78200002 ER PT J AU KEPLER, SO WINGET, DE NATHER, RE BRADLEY, PA GRAUER, AD FONTAINE, G BERGERON, P VAUCLAIR, G CLAVER, CF MARAR, TMK SEETHA, S ASHOKA, BN MAZEH, T LEIBOWITZ, E DOLEZ, N CHEVRETON, M BARSTOW, MA CLEMENS, JC KLEINMAN, SJ SANSOM, AE TWEEDY, RW KANAAN, A HINE, BP PROVENCAL, JL WESEMAEL, F WOOD, MA BRASSARD, P SOLHEIM, JE EMANUELSEN, PI AF KEPLER, SO WINGET, DE NATHER, RE BRADLEY, PA GRAUER, AD FONTAINE, G BERGERON, P VAUCLAIR, G CLAVER, CF MARAR, TMK SEETHA, S ASHOKA, BN MAZEH, T LEIBOWITZ, E DOLEZ, N CHEVRETON, M BARSTOW, MA CLEMENS, JC KLEINMAN, SJ SANSOM, AE TWEEDY, RW KANAAN, A HINE, BP PROVENCAL, JL WESEMAEL, F WOOD, MA BRASSARD, P SOLHEIM, JE EMANUELSEN, PI TI A DETECTION OF THE EVOLUTIONARY TIME SCALE OF THE DA WHITE-DWARF G117-B15A WITH THE WHOLE EARTH TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EVOLUTION; STARS, VARIABLES; STARS, WHITE DWARFS ID ZZ-CETI STARS; PULSATIONS; STABILITY; AGE AB We have detected the time rate of change for the main pulsation period of the 13,000 K DA white dwarf G117-B15A, using the Whole Earth Telescope (WET). The observed rate of period change, P = (12.0 +/- 3.5) x 10(-15) s s -1, is somewhat larger than the published theoretical calculations of the rate of period change due to cooling, based on carbon core white dwarf models. We discuss other effects that could contribute to the observed rate of period change. C1 OBSERV MIDI PYRENEES,F-31400 TOULOUSE,FRANCE. ISRO,CTR SATELLITE,DIV TECH PHYS,BANGALORE 560017,INDIA. OBSERV PARIS,F-921925 PRINCIPAL,FRANCE. UNIV TROMSO,INST MATH & PHYS SCI,N-9000 TROMSO,NORWAY. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV ARKANSAS,DEPT PHYS & ASTRON,LITTLE ROCK,AR 72204. TEL AVIV UNIV,SACKLER FAC EXACT SCI,WISE OBSERV,IL-69978 TEL AVIV,ISRAEL. UNIV LEICESTER,DEPT PHYS & ASTRON,LEICESTER LE1 7RH,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Kepler, S. O. /H-5901-2012 OI Kepler, S. O. /0000-0002-7470-5703 NR 37 TC 60 Z9 60 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1991 VL 378 IS 2 BP L45 EP L48 DI 10.1086/186138 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD782 UT WOS:A1991GD78200004 ER PT J AU BRADLEY, LM FREY, H AF BRADLEY, LM FREY, H TI MAGSAT MAGNETIC ANOMALY CONTRAST ACROSS LABRADOR SEA PASSIVE MARGINS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GREENLAND; EVOLUTION; MODEL; CRUST; MAP AB Many passive margins not complicated by nearby anomalous crustal structure have satellite elevation crustal magnetic anomaly contrasts across them that are recognizable in reduced-to-pole versions of the Magsat and POGO data. In the Labrador Sea region this contrast is particularly well developed with strong positive anomalies overlying the continental crust of Greenland and eastern Canada and prominent negative anomalies situated over the Labrador Sea and Baffin Bay. We use forward modeling of the large-scale crustal bodies in this region (continental, oceanic, passive margin, several anomalous structures) to show that the Magsat anomaly contrast is due simply to the change in crustal susceptibility and thickness at the continental/oceanic crustal transition. Because the thickness varies more than the average susceptibility from continental to oceanic crust, the strong anomaly contrast is essentially an edge effect due mostly to the change in crustal structure. C1 NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. RP UNIV MARYLAND, ASTRON PROGRAM, COLLEGE PK, MD 20742 USA. NR 40 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD SEP 10 PY 1991 VL 96 IS B10 BP 16161 EP 16168 DI 10.1029/91JB01500 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GH508 UT WOS:A1991GH50800009 ER PT J AU LARSON, KM WEBB, FH AGNEW, DC AF LARSON, KM WEBB, FH AGNEW, DC TI APPLICATION OF THE GLOBAL POSITIONING SYSTEM TO CRUSTAL DEFORMATION MEASUREMENT .2. THE INFLUENCE OF ERRORS IN ORBIT DETERMINATION NETWORKS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID PHASE AMBIGUITY RESOLUTION; PRECISION; INTERFEROMETRY; MOTIONS AB Global Positioning System (GPS) measurements of a geodetic network in southern and central California have been used to investigate the errors introduced by adopting different sets of stations as fixed. Such fixed points, called fiducial stations, are necessary to eliminate the errors of imprecise satellites orbits, which otherwise would dominate the error budget for distances greater than tens of kilometers. These fiducial stations also define the reference frame of the crustal deformation network. Establishing the magnitude of the effect of changing the fiducial network is essential for crustal deformation studies, so that these artifacts of the differences between fiducial networks used for the data analyses are not interpreted as geophysical signals. Solutions for a crustal deformation network spanning distances up to 350 km were computed with a variety of fiducial networks. We use fiducial coordinates determined from very long baseline interferometry (VLBI). We compare these solutions by computing the equivalent uniform strain and rotation that best maps one solution into another. If we use a continental-scale fiducial network with good geometry, the distortions between the solutions are about 10(-8), largely independent of the exact choice of stations. The one case of a large-scale fiducial network where the distortions are larger is when the three fiducial stations chosen all lie close to a great circle. Use of a fiducial network no larger than the crustal deformation network can produce apparent strains of up to 10(-7). Our work suggests that fiducial coordinates determined from GPS data analysis may be used, although they should be determined using a consistent reference frame, such as provided by VLBI and satellite laser ranging. C1 CALTECH,JET PROP LAB,SATELLITE GEODESY & GEODYNAM SYST GRP,PASADENA,CA 91109. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,INST GEOPHYS & PLANETARY PHYS,LA JOLLA,CA 92093. RP LARSON, KM (reprint author), UNIV COLORADO,COLORADO CTR ASTRODYNAM RES,DEPT AEROSP ENGN,BOULDER,CO 80309, USA. OI Agnew, Duncan/0000-0002-2360-7783 NR 20 TC 19 Z9 19 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-SOL EA JI J. Geophys. Res.-Solid Earth PD SEP 10 PY 1991 VL 96 IS B10 BP 16567 EP 16584 DI 10.1029/91JB01276 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GH508 UT WOS:A1991GH50800036 ER PT J AU MCKAY, CP POLLACK, JB COURTIN, R AF MCKAY, CP POLLACK, JB COURTIN, R TI THE GREENHOUSE AND ANTIGREENHOUSE EFFECTS ON TITAN SO SCIENCE LA English DT Article ID ATMOSPHERE; OCEAN AB There are many parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the terrestrial greenhouse effect; these parallels provide a comparison for theories of the heat balance of Earth. Titan's atmosphere has a greenhouse effect caused primarily by pressure-induced opacity of N2, CH4, and H-2. H-2 is a key absorber because it is primarily responsible for the absorption in the wave number 400 to 600 cm-1 "window" region of Titan's infrared spectrum. The concentration of CH4, also an important absorber, is set by the saturation vapor pressure and hence is dependent on temperature. In this respect there is a similarity between the role of H-2 and CH4 on Titan and that of CO2 and H2O on Earth. Titan also has an antigreenhouse effect that results from the presence of a high-altitude haze layer that is absorbing at solar wavelengths but transparent in the thermal infrared. The antigreenhouse effect on Titan reduces the surface temperature by 9 K whereas the greenhouse effect increases it by 21 K. The net effect is that the surface temperature (94 K) is 12 K warmer than the effective temperature (82 K). If the haze layer were removed, the antigreenhouse effect would be greatly reduced, the greenhouse effect would become even stronger, and the surface temperature would rise by over 20 K. C1 OBSERV PARIS,RECH SPATIALE LAB,F-92195 MEUDON,FRANCE. RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 18 TC 124 Z9 127 U1 4 U2 25 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 6 PY 1991 VL 253 IS 5024 BP 1118 EP 1121 DI 10.1126/science.11538492 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GD808 UT WOS:A1991GD80800025 PM 11538492 ER PT J AU SOBIESZCZANSKISOBIESKI, J TULINIUS, J AF SOBIESZCZANSKISOBIESKI, J TULINIUS, J TI MDO CAN HELP RESOLVE THE DESIGNERS DILEMMA SO AEROSPACE AMERICA LA English DT Article RP SOBIESZCZANSKISOBIESKI, J (reprint author), NASA,LANGLEY RES CTR,INTERDISCIPLINARY OFF,HAMPTON,VA 23665, USA. NR 0 TC 7 Z9 10 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 1991 VL 29 IS 9 BP 32 EP & PG 0 WC Engineering, Aerospace SC Engineering GA GE198 UT WOS:A1991GE19800008 ER PT J AU BIESIADNY, T AF BIESIADNY, T TI V/STOL GET A LIFT SO AEROSPACE AMERICA LA English DT Article RP BIESIADNY, T (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 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 1991 VL 29 IS 9 BP 52 EP 55 PG 4 WC Engineering, Aerospace SC Engineering GA GE198 UT WOS:A1991GE19800018 ER PT J AU STICKLE, JW STEWART, RJ HOLMES, BJ AF STICKLE, JW STEWART, RJ HOLMES, BJ TI GENERAL-AVIATION - TRANSPORTATION IN TRANSITION SO AEROSPACE AMERICA LA English DT Article RP STICKLE, JW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD SEP PY 1991 VL 29 IS 9 BP 56 EP 58 PG 3 WC Engineering, Aerospace SC Engineering GA GE198 UT WOS:A1991GE19800019 ER PT J AU WHEELER, RM MACKOWIAK, CL SAGER, JC AF WHEELER, RM MACKOWIAK, CL SAGER, JC TI SOYBEAN STEM GROWTH UNDER HIGH-PRESSURE SODIUM WITH SUPPLEMENTAL BLUE LIGHTING SO AGRONOMY JOURNAL LA English DT Article ID SEEDLINGS; PHYTOCHROME; ELONGATION; EFFICIENCY; RESPONSES; MUSTARD AB High-pressure sodium (HPS) lamps are popular for plant lighting because of their high energy conversion efficiencies. Yet their spectrum has very little blue light (BL), which may cause undesirable morphological responses. To study this, 'McCall' soybean [Glycine max (L.) Merr.] plants were grown for 28 d in growth chambers using HPS lamps, with or without supplemental light from blue phosphor fluorescent lamps. Total photosynthetic photon flux (PPF) levels (including blue fluorescent) were kept near 300 or 500-mu-mol m-2 s-1. Blue fluorescent levels ranged from 7 to 20-mu-mol m-2 s-1, providing from 6 to 18-mu-mol m-2 s-1 of supplemental BL (400-500 nm). Stem and internode lengths were longest under 300-mu-mol m-2 s-1 HPS lighting and became progressively shorter with increasing supplemental BL until a total of approximately 30-mu-mol m-2 s-1 of BL (from HPS and BL supplement) was present in the spectrum. Beyond this, extra BL had no effect. Two other lamps rich in BL, metal halide (Optimarc) and fluorescent (Vita-Lite), also produced plants with short stems, as did HPS lighting maintained at 500-mu-mol m-2 s-1. Results suggest that use of high-pressure sodium or other blue-deficient sources for lighting at low to moderate photosynthetic photon flux levels may cause abnormal stem elongation, but this can be prevented by adding a small amount of supplemental blue light. C1 BIONET CORP,KENNEDY SPACE CTR,FL 32899. RP WHEELER, RM (reprint author), NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899, USA. NR 19 TC 55 Z9 57 U1 0 U2 11 PU AMER SOC AGRONOMY PI MADISON PA 677 S SEGOE RD, MADISON, WI 53711 SN 0002-1962 J9 AGRON J JI Agron. J. PD SEP-OCT PY 1991 VL 83 IS 5 BP 903 EP 906 PG 4 WC Agronomy SC Agriculture GA GG706 UT WOS:A1991GG70600024 PM 11537676 ER PT J AU LEE, DJ SMITH, CA AF LEE, DJ SMITH, CA TI EFFECT OF VORTEX CORE DISTORTION ON BLADE-VORTEX INTERACTION SO AIAA JOURNAL LA English DT Article AB The effect of vortex distortion on the flow arising from the interaction of a convecting vortex and an airfoil is analyzed for two-dimensional, incompressible, inviscid flow. Significant distortion of the vortex structure, owing to interaction with the airfoil, can occur, especially during close interactions. The vorticity field is represented by multiple vortex elements. Vortex instability and diffusion, resulting from discretization in space and time, are discussed. An integral-boundary-element method is used to represent the airfoil surface and its effect on the flowfield. The body panels are redistributed on the surface as the vortices are convected past the airfoil to calculate the effect of the vorticity field more accurately. The method is applied to several cases to examine effects of vortex strength, distribution, and initial separation position. The distortion, even splitting, of the vortex core is observed for the case of close interaction. However, the extent of distortion depends strongly on the initial size and strength of the vortex. Also, the unsteady pressure term contributes significantly to both the surface-pressure distribution and total lift in addition to the quasisteady term. Circulation around the airfoil is also presented. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Lee, Duck Joo/C-1967-2011 NR 22 TC 19 Z9 19 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 SEP PY 1991 VL 29 IS 9 BP 1355 EP 1362 DI 10.2514/3.10746 PG 8 WC Engineering, Aerospace SC Engineering GA GD700 UT WOS:A1991GD70000002 ER PT J AU WATSON, WR MYERS, MK AF WATSON, WR MYERS, MK TI INFLOW-OUTFLOW BOUNDARY-CONDITIONS FOR 2-DIMENSIONAL ACOUSTIC-WAVES IN CHANNELS WITH FLOW SO AIAA JOURNAL LA English DT Article ID DIFFERENCE AB An analysis of the number and form of the required inflow-outflow boundary conditions for the full two-dimensional time-dependent nonlinear acoustic system in subsonic mean flow is performed. The analysis is performed in a rectangular channel with rigid walls and is extendable to more complicated geometries and wall conditions. The explicit predictor-corrector method of MacCormack is used to integrate the acoustic system coupled with the derived boundary conditions. The methodology is tested on both uniform and sheared mean flows with plane and nonplanar sources. Results show that the acoustic system requires three physical boundary conditions on the inflow and one on the outflow boundary. The most natural choice for the inflow boundary conditions is judged to be a specification of the vorticity, the normal acoustic impedance, and a pressure gradient-density gradient relationship normal to the boundary. Specification of the acoustic pressure at the outflow boundary along with these inflow boundary conditions is found to give consistent reliable results. A set of boundary conditions developed earlier by K. W. Thompson, which were intended to be nonreflecting, is tested using the current method and is shown to yield unstable results for nonplanar acoustic waves. C1 GEORGE WASHINGTON UNIV,JOINT INST ADV FLIGHT SCI,HAMPTON,VA 23665. RP WATSON, WR (reprint author), NASA,LANGLEY RES CTR,F47Z,APPL ACOUST BRANCH,MAIL STOP 460,HAMPTON,VA 23665, USA. NR 14 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1991 VL 29 IS 9 BP 1383 EP 1389 DI 10.2514/3.10751 PG 7 WC Engineering, Aerospace SC Engineering GA GD700 UT WOS:A1991GD70000007 ER PT J AU KOPRIVA, DA ZANG, TA HUSSAINI, MY AF KOPRIVA, DA ZANG, TA HUSSAINI, MY TI SPECTRAL METHODS FOR THE EULER EQUATIONS - THE BLUNT BODY PROBLEM REVISITED SO AIAA JOURNAL LA English DT Article AB We solve the blunt body problem using shock fitting and a Chebyshev spectral collocation method. Careful attention is paid to the boundary and shock acceleration equations. We show that converged solutions can be obtained without artificial smoothing and that spectral accuracy is observed. C1 FLORIDA STATE UNIV,SUPERCOMP COMP RES INST,TALLAHASSEE,FL 32306. NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP KOPRIVA, DA (reprint author), FLORIDA STATE UNIV,DEPT MATH,TALLAHASSEE,FL 32306, USA. NR 4 TC 26 Z9 27 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1991 VL 29 IS 9 BP 1458 EP 1462 DI 10.2514/3.10760 PG 5 WC Engineering, Aerospace SC Engineering GA GD700 UT WOS:A1991GD70000016 ER PT J AU CHIN, S LAN, CE GAINER, TG AF CHIN, S LAN, CE GAINER, TG TI CALCULATION OF ASYMMETRIC VORTEX SEPARATION ON CONES AND TANGENT OGIVES BASED ON A DISCRETE VORTEX MODEL - REPLY SO AIAA JOURNAL LA English DT Note C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP CHIN, S (reprint author), UNIV KANSAS,AEROSP ENGN,LAWRENCE,KS 66095, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1991 VL 29 IS 9 BP 1536 EP 1536 DI 10.2514/3.59968 PG 1 WC Engineering, Aerospace SC Engineering GA GD700 UT WOS:A1991GD70000031 ER PT J AU TEPPER, A COMSTOCK, GW LEVINE, M AF TEPPER, A COMSTOCK, GW LEVINE, M TI A LONGITUDINAL-STUDY OF PULMONARY-FUNCTION IN FIRE FIGHTERS SO AMERICAN JOURNAL OF INDUSTRIAL MEDICINE LA English DT Article DE OCCUPATIONAL DISEASE; RESPIRATORY DISEASE; SPIROMETRY; FIRE FIGHTING; AMMONIA; PERSONAL PROTECTION EQUIPMENT ID FORCED EXPIRATORY VOLUME; RESPIRATORY-TRACT; AIR CONTAMINANTS; AMMONIA BURNS; FIREFIGHTERS; SPIROMETRY; INHALATION; MORTALITY; SELECTION; EXPOSURE AB Pulmonary function changes among fire fighters were evaluated by re-examining 632 Baltimore city fire fighters six to ten years after a baseline examination. Spirometry was used to determine forced expiratory volume in 1 second (FEV1). Information about exposures was obtained by questionnaire and by combining data from fire department records regarding the number of fires fought by fire fighting units with individual work histories. Men who never wore a mask while extinguishing fires experienced a 1.7 times greater rate of FEV1 decline than mask wearers. Men with ammonia exposure experienced a rate of decline 1.7 times greater than non-exposed men. Neither length of time spent in exposed jobs nor number of responses were associated with the rate of decline. Active fire fighters experienced a rate of decline 2.5 times greater than those who had retired or resigned. Some effects differed between men who were able to perform repeatable pulmonary function tests and those who were not. C1 JOHNS HOPKINS UNIV,SCH HYG & PUBL HLTH,DEPT EPIDEMIOL,BALTIMORE,MD 21218. NASA,DIV OCCUPAT HLTH,WASHINGTON,DC 20546. RP TEPPER, A (reprint author), NIOSH,DIV SURVEILLANCE HAZARD EVALAT & FIELD STUDIES,R-18,CINCINNATI,OH 45226, USA. FU NHLBI NIH HHS [HL 21,670]; NIOSH CDC HHS [5 R03 OH01756] NR 30 TC 26 Z9 26 U1 0 U2 2 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0271-3586 J9 AM J IND MED JI Am. J. Ind. Med. PD SEP PY 1991 VL 20 IS 3 BP 307 EP 316 DI 10.1002/ajim.4700200304 PG 10 WC Public, Environmental & Occupational Health SC Public, Environmental & Occupational Health GA GC246 UT WOS:A1991GC24600003 PM 1928108 ER PT J AU ULVESTAD, JS ANTONUCCI, RRJ AF ULVESTAD, JS ANTONUCCI, RRJ TI 2ND-EPOCH VLA OBSERVATIONS OF COMPACT RADIO-SOURCES IN NGC-253 SO ASTRONOMICAL JOURNAL LA English DT Article ID EMISSION; SUPERNOVAE AB The nearby starburst galaxy NGC 253 has been reobserved with the highest resolution configuration of the VLA at 6 cm, and observed for the first time at 3.6 cm. No new compact radio sources stronger than 3 mJy at 6 cm appeared in the 18 months since the first-epoch observations at 6 cm. This flux-density limit corresponds to an intrinsic luminosity three times that of the galactic supernova remnant Cas A. The 95% confidence upper limit to the type II supernova rate is 3.0 yr-1, assuming that 2/3 of such supernovae reaching their 6 cm maxima between epochs would have been strong enough radio sources to be detected at the second epoch. None of the 6 cm sources stronger than 1 mJy was found to undergo significant flux decreases over 18 months, a result differing from that found for M82 by Kronberg & Sramek [Sci, 227, 88 (1985)]. Errors in the flux-density scales should not have caused this difference between NGC 253 and M82, implying that the sources in NGC 253 are intrinsically different from those in M82. In principle, the bulk of the sources in NGC 253 could be supernova remnants or H II regions, or they may be young supernovae of a different type from those in M82. The 3.6 cm data show a substantial reduction in confusion and support the estimate that there are approximately 100 compact radio sources in NGC 253; some of the sources seen at both 3.6 and 6 cm probably have flat spectra and may be H II regions. A shell supernova remnant whose intrinsic radio size and luminosity are similar to Cas A has been discovered about 330 pc from the galaxy nucleus. C1 UNIV CALIF SANTA BARBARA, DEPT PHYS, SANTA BARBARA, CA 93106 USA. RP ULVESTAD, JS (reprint author), CALTECH, JET PROP LAB, MAIL CODE 301-125J, PASADENA, CA 91109 USA. OI Ulvestad, James/0000-0002-9362-7237 NR 15 TC 36 Z9 36 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1991 VL 102 IS 3 BP 875 EP 881 DI 10.1086/115918 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD160 UT WOS:A1991GD16000005 ER PT J AU HUBENY, I PLAVEC, MJ AF HUBENY, I PLAVEC, MJ TI CAN A DISK MODEL EXPLAIN BETA LYRAE SO ASTRONOMICAL JOURNAL LA English DT Article ID PRIMITIVE SOLAR NEBULA; ACCRETION DISKS; TURBULENT CONVECTION; ALGOL; SPECTRA; STARS AB The peculiar eclipsing binary system beta-Lyrae still eludes interpretation. We have attempted to interpret it in terms of a model where the primary, i.e., the spectroscopically observable B star transfers matter to a "canonical" accretion disk surrounding a "gainer" which may be a rather ordinary B0.5 V star. We calculated disk models using the program TLUSDISK, which computes the vertical structure of each disk ring self-consistently, without a priori assumption about its optical thickness, and then permits one to calculate the emergent radiation field at a number of frequencies and for various inclination angles. We find that most of the optical radiation from the secondary object probably comes from the disk rim, provided that the rate of mass transfer is not much lower than about 10(-4) solar masses per year. The rather high disk rim then introduces severe constraints on the orbital inclination; these constraints are discussed in detail. We conclude that the disk plays an essential passive role, and the observable radiation from its face is insignificant. We find in particular that a model in which most ultraviolet radiation would be coming from the face of the disk is unacceptable both because of these constraints and because it would require an unrealistically small radius (almost-equal-to 1 R.) for the accreting star whose mass exceeds 10 M.. We propose instead that the bulk of the ultraviolet radiation is coming from a small unocculted segment of the gainer, which probably is a rather normal main-sequence star of spectral type near B0.5 V, although a Wolf-Rayet star cannot be quite ruled out. C1 UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. RP HUBENY, I (reprint author), NASA, GODDARD SPACE FLIGHT CTR, USRA, CODE 681, GREENBELT, MD 20771 USA. NR 43 TC 40 Z9 41 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1991 VL 102 IS 3 BP 1156 EP 1170 DI 10.1086/115942 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD160 UT WOS:A1991GD16000029 ER PT J AU GAO, YT STECKER, FW CLINE, DB AF GAO, YT STECKER, FW CLINE, DB TI THE LIGHTEST SUPERSYMMETRIC PARTICLE AND THE EXTRAGALACTIC GAMMA-RAY BACKGROUND SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COSMOLOGY; DARK MATTER; ELEMENTARY PARTICLES; GAMMA-RAYS, GENERAL; RADIATION MECHANISMS, GENERAL ID DARK MATTER ANNIHILATION; COSMOLOGY; UNIVERSE AB Studies of cosmic dark matter (DM) and gamma-rays are in the forefront of particle astrophysics. On the eve of the launch of the Gamma Ray Observatory (GRO), effort has been devoted to investigate the low-energy diffuse cosmic gamma-ray spectrum due to the cosmological photino annihilation. Using a corrected assumption for annihilation cross section, we now generalize this work to the annihilation of a general type of the best-motivated cold dark matter (CDM) candidates, the lightest supersymmetric particle (LSP), with our cosmological integrations back into the history of the Universe. Our conclusion is that the cosmological LSP-type annihilation can not be a major contributor to the observed extragalactic gamma-ray background (EGB). C1 UNIV CALIF LOS ANGELES, DEPT PHYS, LOS ANGELES, CA 90024 USA. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. FERMI NATL ACCELERATOR LAB, BATAVIA, IL 60510 USA. RP GAO, YT (reprint author), UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. RI Stecker, Floyd/D-3169-2012 NR 23 TC 13 Z9 13 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1991 VL 249 IS 1 BP 1 EP 4 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GF566 UT WOS:A1991GF56600002 ER PT J AU GELLER, M SAUVAL, AJ GREVESSE, N FARMER, CB NORTON, RH AF GELLER, M SAUVAL, AJ GREVESSE, N FARMER, CB NORTON, RH TI 1ST IDENTIFICATION OF PURE ROTATION LINES OF NH IN THE INFRARED SOLAR SPECTRUM SO ASTRONOMY & ASTROPHYSICS LA English DT Note DE SOLAR SPECTRUM, IDENTIFICATION; MOLECULAR SPECTRA, PURE ROTATION LINES; INFRARED, SPECTRUM ID DIPOLE-MOMENT FUNCTIONS; DIATOMIC HYDRIDES; STATES; ABINITIO; CL AB High resolution solar spectra obtained from space (ATMOS Fourier Transform Spectrometer) have permitted us to detect for the first time pure rotation lines of NH of the X 3-SIGMA ground state near 600-900 cm-1. All these very weak NH solar lines have never been observed before in the laboratory. C1 OBSERV ROYAL BELGIQUE, B-1180 BRUSSELS, BELGIUM. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV LIEGE, INST ASTROPHYS, B-4000 COINTE OUGREE, BELGIUM. NR 17 TC 11 Z9 11 U1 1 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1991 VL 249 IS 2 BP 550 EP 552 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GJ844 UT WOS:A1991GJ84400041 ER PT J AU HARDING, AK MASTICHIADIS, A PROTHEROE, RJ SZABO, AP AF HARDING, AK MASTICHIADIS, A PROTHEROE, RJ SZABO, AP TI COSMIC-RAY TRANSPORT AND GAMMA-RAY EMISSION IN SUPERNOVA SHELLS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS, GENERAL; GAMMA RAYS, GENERAL; NEBULAE, SUPERNOVAE REMNANTS; PARTICLE ACCELERATION ID PARTICLE-ACCELERATION; SN 1987A; SN1987A; PULSARS; SEARCH; TEV AB We examine the mixing and transport of cosmic rays accelerated by a pulsar inside an expanding supernova remnant and the resulting high-energy gamma-ray emission from nuclear interactions of these accelerated particles in the shell. Rayleigh-Taylor instability at the interface between a pulsar wind cavity and the inner supernova envelope is assumed to be the mixing mechanism. We apply our analysis to the model of Gaisser, Harding, & Stanev, where protons are accelerated at the reverse shock in the pulsar wind. We estimate the instability time scale from the dynamics of the pulsar wind cavity, and model the injection, diffusion, and interaction of protons in the shell. The resulting gamma-ray flux is lower than previous estimates due to proton adiabatic losses in the expanding pulsar wind. We find that the protons mix and diffuse only into the innermost regions of the envelope before interacting. Energy-dependent diffusion causes the higher energy gamma-ray light curves to decay faster than those at lower energy. C1 UNIV ADELAIDE, DEPT PHYS & MATH PHYS, ADELAIDE, SA 5001, AUSTRALIA. RP HARDING, AK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY PHYS LAB, GREENBELT, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 32 TC 2 Z9 2 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1991 VL 378 IS 1 BP 163 EP 169 DI 10.1086/170416 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300017 ER PT J AU GUESSOUM, N RAMATY, R LINGENFELTER, RE AF GUESSOUM, N RAMATY, R LINGENFELTER, RE TI POSITRON-ANNIHILATION IN THE INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Article DE ELEMENTARY PARTICLES; GAMMA-RAYS, GENERAL; INTERSTELLAR, GRAINS; INTERSTELLAR, MAGNETIC FIELDS; INTERSTELLAR, MATTER ID GALACTIC-CENTER DIRECTION; CENTER REGION; NEUTRAL-HYDROGEN; RADIATION; ENVIRONMENT; LINE; CONTINUUM; FRACTION; SPECTRUM; SOLAR AB We study positronium formation and positron annihilation in a model for the interstellar medium consisting of cold cloud cores, warm, partially ionized cloud envelopes, and hot intercloud gas. We calculate the gamma-ray spectra resulting from positron annihilation in these components of the interstallar medium. We then combine the spectra from the individual components using two limiting assumptions for the propagation of the positrons: (1) the positrons propagate freely throughout the interstellar medium, and (2) the positrons are excluded from the cold cloud cores. In the first case, the bulk of the positrons annihilate in the cloud cores and the annihilation line exhibits broad wings resulting from the annihilation of positronium formed by charge exchange in flight. In the second case, the positrons annihilate mainly in the warm envelopes, and the line wings are suppressed. Positrons could be prevented from penetrating into the cores by magnetic fields. The fraction f of positrons annihilating via positronium is congruent-to 0.9 for the first model, independent of the amount of dust in the interstellar medium. This fraction is also congruent-to 0.9 for the second model, provided the amount of dust is not large. The comparison of this value with observations suggests that for the compact object near the Galactic center, whose existence is implied by observations of time-variable 511 keV line emission, f is lower than the value calculated for the interstellar component. In the compact source a low f could result from annihilation in a hot (greater-than-or-similar-to 5 x 10(5) K) gas or in a dusty, partially ionized medium. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. RI Guessoum, Nidhal/C-3051-2013 NR 41 TC 97 Z9 97 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1991 VL 378 IS 1 BP 170 EP 180 DI 10.1086/170417 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300018 ER PT J AU MCCLUSKEY, GE MCCLUSKEY, CPS KONDO, Y AF MCCLUSKEY, GE MCCLUSKEY, CPS KONDO, Y TI IUE INVESTIGATION OF MASS-FLOW IN THE INTERACTING BINARY-U-SAGITTAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ECLIPSING BINARIES; STARS, INDIVIDUAL (U SGE); ULTRAVIOLET, SPECTRA ID CLASSICAL ALGOL SYSTEMS; CHEMICAL-COMPOSITION; CEPHEI; SGE AB Fifteen far-ultraviolet and 13 mid-ultraviolet high-resolution spectra of the interacting Algol-type binary U Sagittae have been obtained with the International Ultraviolet Explorer (IUE) satellite. The resonance lines of Si IV and C IV are present in absorption of moderate strength at all phases. At several phases weak absorption due to the N V resonance lines is present. The high-temperature pseudophotospheric region which is found surrounding the equatorial regions of the primary star in all active Algol-type binaries is present in U Sge, indicating that it is not as dormant as once believed. This is also consistent with recent ground-based studies. It is likely that all classical Algol-type binaries will show pseudophotospheric accretion phenomena and gas streaming effects with occasional short-term increases in activity if monitored closely enough. C1 PENN STATE UNIV,DEPT COMP SCI,FOGELSVILLE,PA 18051. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP MCCLUSKEY, GE (reprint author), LEHIGH UNIV,DEPT MATH,DIV ASTRON,BETHLEHEM,PA 18015, USA. NR 33 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1991 VL 378 IS 1 BP 281 EP 285 DI 10.1086/170427 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300028 ER PT J AU DEJAGER, OC AF DEJAGER, OC TI THE UNUSUAL X-RAY PULSE TIMING OF AE AQUARII SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, BINARIES; STARS, INDIVIDUAL (AE AQUARII); STARS, X-RAYS ID EMISSION AB The novalike variable AE Aquarii exhibits emission and absorption lines of which the radial velocities are antiphased by 180-degrees and both describe a circular orbit with a period of 9.88 hr. There is therefore good reason to believe that the emission-line orbit describes the true orbit of the white dwarf. The system also emits coherent pulsed optical light with a period of 33.s0767 and the corresponding timing delays describe a distorted orbit which is shifted by 60-degrees relative to the emission-line orbit. The semiamplitude of the pulse-timing orbit is also a factor (0.865 +/- 0.077) smaller than that of the emission-line orbit. The pulsed optical light may then be due to the reprocessing of the EUV/X-rays emitted from the white dwarf (with a rotation period of 33.s0460) incident on a target fixed in the orbital frame of the binary (Robinson, Shafter, & Balachandran), to give optical pulsations at an orbital beat period. From a reanalysis of the Einstein X-ray data on AE Aqr we show the following: (1) The most significant X-ray period is indeed the optical period and (2) at this period, the X-ray pulse-timing orbit follows the same orbit as the optical pulse-timing orbit. (3) The direct X-ray beam from the white dwarf is at least 4 times weaker than the pulsed X-ray signal at the optical period. (4) Given the above mentioned correlations with the optical, we infer that the X-ray pulsations must be originating at the same target in the orbit responsible for the optical pulsations. (5) There is a possible orbital modulation of the pulsed X-ray signal with a minimum in the almost-equal-to 60-degrees phase interval between superior conjunction of the optical pulse-timing and emission-line orbits. (6) We also show that the X-ray pulse has slipped at least twice in phase by more than 30% in 2 years' time. It remains then to be shown how the direct X-ray pulse from the white dwarf can be so weak given the optically thin disk which is viewed at an elevation angle > 30-degrees above the disk. RP DEJAGER, OC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771, USA. NR 28 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 SEP 1 PY 1991 VL 378 IS 1 BP 286 EP 292 DI 10.1086/170428 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300029 ER PT J AU GURZADYAN, GA KONDO, Y RUSTAMBEKYAN, SS TERZIAN, Y PEREZ, MR AF GURZADYAN, GA KONDO, Y RUSTAMBEKYAN, SS TERZIAN, Y PEREZ, MR TI A COOL SUPERGIANT WITH ANOMALOUS BEHAVIOR OF THE 2800-MG-II-DOUBLET SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, BINARIES; STARS, INDIVIDUAL (HD-135345); ULTRAVIOLET, SPECTRA AB The IUE ultraviolet spectrum for a supergiant of type G Ia, HD 135345, was obtained for the wavelength region 2000-3000 angstrom. In this spectrum, the continuum as well as the feature of the Mg II doublet at 2800 angstrom is anomalous. The observed level of continuum increases toward short wavelengths to 2000 angstrom, verifying that this supergiant actually is a binary system with a hot companion. The anomalies in the magnesium doublet are the complete absence of chromospheric emission and the very small equivalent width of the doublet absorption: the equivalent width is 4 angstrom, which is 7.5 times smaller than that for a typical G5 star. This too can be explained in terms of the binary nature of this supergiant with a hot companion. The main parameters of this binary system have been obtained: the spectral classes are G5 Ib and B2 II, the effective temperatures T(G) = 5500 K and T(B) = 20,000 K, the ratio of radii R(G)/R(B) = 10.8, the radii R(G) = 125 R. and R(B) = 11.6 R., the visible magnitudes are V(G) = 5.45 and V(B) = 6.85. C1 ACAD SCI ARSSR,BYURAKAN ASTROPHYS OBSERV,YEREVAN,ARMENIA,USSR. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. CORNELL UNIV,NATL ASTRON & IONISPHERE CTR,ITHACA,NY 14853. NR 11 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 SEP 1 PY 1991 VL 378 IS 1 BP 298 EP 301 DI 10.1086/170430 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300031 ER PT J AU WINGET, DE NATHER, RE CLEMENS, JC PROVENCAL, J KLEINMAN, SJ BRADLEY, PA WOOD, MA CLAVER, CF FRUEH, ML GRAUER, AD HINE, BP HANSEN, CJ FONTAINE, G ACHILLEOS, N WICKRAMASINGHE, DT MARAR, TMK SEETHA, S ASHOKA, BN ODONOGHUE, D WARNER, B KURTZ, DW BUCKLEY, DA BRICKHILL, J VAUCLAIR, G DOLEZ, N CHEVRETON, M BARSTOW, MA SOLHEIM, JE KANAAN, A KEPLER, SO HENRY, GW KAWALER, SD AF WINGET, DE NATHER, RE CLEMENS, JC PROVENCAL, J KLEINMAN, SJ BRADLEY, PA WOOD, MA CLAVER, CF FRUEH, ML GRAUER, AD HINE, BP HANSEN, CJ FONTAINE, G ACHILLEOS, N WICKRAMASINGHE, DT MARAR, TMK SEETHA, S ASHOKA, BN ODONOGHUE, D WARNER, B KURTZ, DW BUCKLEY, DA BRICKHILL, J VAUCLAIR, G DOLEZ, N CHEVRETON, M BARSTOW, MA SOLHEIM, JE KANAAN, A KEPLER, SO HENRY, GW KAWALER, SD TI ASTEROSEISMOLOGY OF THE DOV STAR PG-1159-035 WITH THE WHOLE EARTH TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (PG-1159-035); STARS, PULSATION; STARS, WHITE DWARFS ID WHITE-DWARFS; EVOLUTION; PULSATIONS; HOT AB We report the results from 264.1 hr of nearly continuous time-series photometry on the pulsating pre-white dwarf star (DOV) PG 1159-035. The high-resolution power spectrum of this data set is dominated by power in the range from roughly 1000 to 2600-mu-Hz (1000 s to 385 s periods). This power is completely resolved into 125 individual frequencies; we have identified 101 of them with specific, quantized pulsation modes, and the rest are completely consistent with such modal assignment. The luminosity variations are therefore certainly the result of g-mode pulsations. Although the amplitudes of some of the peaks exhibits significant variations on time scales of a year or so, the underlying frequency structure of the pulsations is stable over much longer intervals. With the help of existing linear theory we use these identifications to determine, or strongly constrain, many of the fundamental physical parameters describing this star. We find its mass to be 0.586 M., its rotation period 1.38 days, its magnetic field less than 6000 G, its pulsation and rotation axes to be aligned, and its outer layers to be compositionally stratified. With straightforward extensions of existing theory it may be possible to determine uniquely from this data set all of the parameters necessary to construct a quantitative model of its interior. These observations also reveal several interesting phenomena that challenge the current theory of nonradial pulsations, and may require substantial new developments to describe them. C1 UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV ARKANSAS,DEPT PHYS & ASTRON,LITTLE ROCK,AR 72204. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 2600,AUSTRALIA. ISRO SATELLITE CTR,DIV TECH PHYS,INDIAN SPACE RES ORG,BANGALORE 560017,INDIA. UNIV CAPE TOWN,DEPT ASTRON,RONDEBOSCH 7700,SOUTH AFRICA. OBSERV MIDI PYRENEES,F-31400 TOULOUSE,FRANCE. OBSERV PARIS,F-92190 MEUDON,FRANCE. UNIV LEICESTER,DEPT PHYS,LEICESTER LE1 7RH,ENGLAND. UNIV TROMSO,INST MATEMAT REALFAG,N-9000 TROMSO,NORWAY. UNIV FED RIO GRANDE SUL,INST FIS,BR-90049 PORTO ALEGRE,RS,BRAZIL. TENNESSEE STATE UNIV,CTR EXCELLENCE INFORMAT SYST,NASHVILLE,TN 37203. IOWA STATE UNIV,DEPT PHYS & ASTRON,AMES,IA 50211. RP WINGET, DE (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. RI Achilleos, Nicholas/C-1647-2008; Kepler, S. O. /H-5901-2012; OI Kepler, S. O. /0000-0002-7470-5703; Achilleos, Nicholas/0000-0002-5886-3509; Kawaler, Steven/0000-0002-6536-6367 NR 35 TC 239 Z9 239 U1 0 U2 9 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1991 VL 378 IS 1 BP 326 EP & DI 10.1086/170434 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300035 ER PT J AU MOORE, RL MUSIELAK, ZE SUESS, ST AN, CH AF MOORE, RL MUSIELAK, ZE SUESS, ST AN, CH TI ALFVEN-WAVE TRAPPING, NETWORK MICROFLARING, AND HEATING IN SOLAR CORONAL HOLES SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; SUN, CORONA; SUN, FLARES; WAVE MOTIONS ID TRANSITION REGION; MAGNETIC-FIELD; ATMOSPHERE; MODEL; WIND; SUN AB We present new evidence that much of the heating in coronal holes is provided by Alfven waves. This evidence comes from examining the reflection of Alfven waves in an isothermal hydrostatic model coronal hole with open magnetic field. Reflection occurs if the wavelength is as long as of the order of the scale height of the Alfven velocity. For Alfven waves with periods of about 5 minutes, and for realistic density, magnetic field strength, and magnetic field spreading in the model, the waves are reflected back down (trapped) within the model hole if the coronal temperature is only slightly less than 1.0 x 10(6) K, but are not reflected and escape out the top of the model (which escape corresponds to the escape of the Alfven waves into the solar wind) if the coronal temperature is only slightly greater than 1.0 x 10(6) K. Because the spectrum of Alfven waves in real coronal holes is expected to peak around 5 minutes and the temperature is observed to be close to 1.0 x 10(6) K, the sensitive temperature dependence of the trapping suggests that the temperature in coronal holes is regulated by heating by the trapped Alfven waves. In addition, the dependence of the trapping on the spreading rate and leaning of the open magnetic field suggests that polar coronal holes should be cooler at their edges than in their centers, in agreement with the observation in thermal radio emission that polar coronal holes are dimmer at their edges and brighter in their centers. In light of our findings in favor Alfven wave heating in coronal holes, we discuss the heating of the quiet corona in general and the possible role of network microflares in particular. We point out that the network microflares might be the source of the Alfven waves that heat coronal holes. C1 UNIV ALABAMA,DEPT MECH ENGN,HUNTSVILLE,AL 35899. UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. APPL RES INC,HUNTSVILLE,AL 35806. RP MOORE, RL (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES52,HUNTSVILLE,AL 35812, USA. NR 46 TC 63 Z9 63 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1991 VL 378 IS 1 BP 347 EP 359 DI 10.1086/170435 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC363 UT WOS:A1991GC36300036 ER PT J AU PRATT, WM SICONOLFI, SF WEBSTER, L HAYES, JC MAZZOCCA, AD HARRIS, BA AF PRATT, WM SICONOLFI, SF WEBSTER, L HAYES, JC MAZZOCCA, AD HARRIS, BA TI A COMPARISON BETWEEN COMPUTER-CONTROLLED AND SET WORK RATE EXERCISE BASED ON TARGET HEART-RATE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note ID STRESS AB Good exercise prescriptions provide work rates (WRs) that maintain heart rates (HR) in a target zone and at a percent of maximum metabolic equivalent (%METmax). HR and MET were evaluated from computer-controlled and set WR (constant speed) sessions (20 min at 65%METmax). Computer-controlled WR used a control algorithm to adjust speed and grade to maintain the target HR. The set WR (mean +/- S.D.) HR (139 +/- 8 bpm) was lower (p < 0.05) than the target (147 +/- 3 bpm) and computer-controlled HRs (153 +/- 5 bpm). The set WR MET (8.6 +/- 2.2) was not different than the target (8.6 +/- 2.2), but both were lower than computer-controlled exercise (9.7 +/- 2.2). Computer-control time in target HR zone (16 +/- 5 min) was significantly (p < 0.004) greater than set WR exercise (6 +/- 5 min). Computer-controlled WR was significantly better in maintaining target HR and the MET values were not physiologically different than target WRs. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,EXERCISE PHYSIOL LAB,HOUSTON,TX 77058. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1991 VL 62 IS 9 BP 899 EP 902 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA GC826 UT WOS:A1991GC82600017 PM 1930084 ER PT J AU ATLAS, D AF ATLAS, D TI EVOLUTION - BATS, RADAR, AND SCIENCE SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Editorial Material C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ATLAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 11 TC 0 Z9 0 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 SEP PY 1991 VL 72 IS 9 BP 1381 EP 1386 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GK190 UT WOS:A1991GK19000007 ER PT J AU ABRAMS, M GLAZE, L SHERIDAN, M AF ABRAMS, M GLAZE, L SHERIDAN, M TI MONITORING COLIMA VOLCANO, MEXICO, USING SATELLITE DATA SO BULLETIN OF VOLCANOLOGY LA English DT Note AB The Colima Volcanic Complex at the western end of the Mexican Volcanic Belt is the most active andesitic volcano in Mexico. Short-wavelength infrared data from the Landsat Thematic Mapper satellite were used to determine the temperature and fractional area of radiant picture elements for two January data acquisitions in 1985 and 1986. The 1986 data showed four 28.5 m by 28.5 m pixels (picture elements) whose hot subpixel components had temperatures ranging from 511-774-degrees-C and areas of 1.8-13 m2. The 1985 data had no radiating areas above background temperatures. Ground observations and measurements in November 1985 and February 1986 reported the presence of hot fumaroles at the summit with temperatures of 135-895-degrees-C. This study demonstrates the utility of satellite data for monitoring volcanic activity. RP ABRAMS, M (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Glaze, Lori/D-1314-2012 NR 0 TC 14 Z9 14 U1 1 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0258-8900 J9 B VOLCANOL JI Bull. Volcanol. PD SEP PY 1991 VL 53 IS 7 BP 571 EP 574 DI 10.1007/BF00298157 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GH534 UT WOS:A1991GH53400005 ER PT J AU VITOUSEK, PM MATSON, PA AF VITOUSEK, PM MATSON, PA TI EFFECTS OF TROPICAL DEFORESTATION ON GLOBAL AND REGIONAL ATMOSPHERIC CHEMISTRY - COMMENT SO CLIMATIC CHANGE LA English DT Editorial Material ID FLOODPLAIN; METHANE C1 NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. RP VITOUSEK, PM (reprint author), STANFORD UNIV,DEPT BIOL SCI,STANFORD,CA 94305, USA. NR 10 TC 0 Z9 0 U1 1 U2 9 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 SEP PY 1991 VL 19 IS 1-2 BP 159 EP 162 DI 10.1007/BF00142222 PG 4 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA GH182 UT WOS:A1991GH18200015 ER PT J AU ARYA, VK AF ARYA, VK TI APPLICATION OF FINITE-ELEMENT-BASED SOLUTION TECHNOLOGIES FOR VISCOPLASTIC STRUCTURAL-ANALYSES SO COMMUNICATIONS IN APPLIED NUMERICAL METHODS LA English DT Article ID CONSTITUTIVE-EQUATIONS AB Finite-element solution technology developed for use in conjunction with advanced viscoplastic models is described. The development of such solution technology is necessary for performing stress/life analyses of engineering structural problems where the complex geometries and loadings make the conventional analytical solutions difficult. The versatility of the solution technology is demonstrated by applying it to viscoplastic models possessing different mathematical structures and encompassing isotropic and anisotropic materials. The computational results qualitatively replicate deformation behaviour observed in experiments on prototypical structural components. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP ARYA, VK (reprint author), UNIV TOLEDO,TOLEDO,OH 43606, USA. NR 20 TC 3 Z9 3 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0748-8025 J9 COMMUN APPL NUMER M PD SEP PY 1991 VL 7 IS 6 BP 435 EP 444 DI 10.1002/cnm.1630070604 PG 10 WC Engineering, Multidisciplinary; Mathematics, Applied SC Engineering; Mathematics GA GE964 UT WOS:A1991GE96400003 ER PT J AU NOOR, AK PETERS, JM AF NOOR, AK PETERS, JM TI STRATEGIES FOR LARGE-SCALE STRUCTURAL PROBLEMS ON HIGH-PERFORMANCE COMPUTERS SO COMMUNICATIONS IN APPLIED NUMERICAL METHODS LA English DT Article ID REDUCTION AB Novel computational strategies are presented for the analysis of large and complex structures. The strategies are based on generating the response of the complex structure using large perturbations from that of a simpler model, associated with a simpler structure (or a simpler mathematical/discrete model of the original structure). Numerical examples are presented to demonstrate the effectiveness of the strategies developed. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23665, USA. NR 21 TC 3 Z9 3 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0748-8025 J9 COMMUN APPL NUMER M PD SEP PY 1991 VL 7 IS 6 BP 465 EP 478 DI 10.1002/cnm.1630070607 PG 14 WC Engineering, Multidisciplinary; Mathematics, Applied SC Engineering; Mathematics GA GE964 UT WOS:A1991GE96400006 ER PT J AU RAMESH, AV UTKU, S WADA, BK AF RAMESH, AV UTKU, S WADA, BK TI REAL-TIME CONTROL OF GEOMETRY AND STIFFNESS IN ADAPTIVE STRUCTURES SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article AB Adaptive structures are those which can adjust their geometry, stiffness and damping on demand to meet the changes in their loading environment. With the advents in the piezo-electric device and composite material technologies, such structures are already being considered seriously in aero-space industry. The success of these structures depends largely on the effective control of the structure through the actuators, and the sensors embedded in their load carrying members. This work outlines the basic theory for the geometry, stiffness and damping control. Necessary and sufficient conditions for stress free geometry control in statically determinate and indeterminate adaptive discrete structures are given. In particular, for the subset of discrete adaptive structures viz. adaptive truss structures the equations similar to the forward and inverse kinematic equations of open loop mechanical manipulators are derived. These equations describe the large geometry control under slow motion (i.e., no inertia forces) assumption. Two criteria for choosing the optimum control from among the possible ones are established. A fast algorithm based on variable order variable step multistep method is given that can compute the controls for a large maneuver in real-time. Numerical results from the algorithm are presented. As an example of damping and stiffness alteration on demand, the vibration control in adaptive trusses by means of elongations and elongation-rates of the active elements is also given. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RAMESH, AV (reprint author), DUKE UNIV,DURHAM,NC 27706, USA. NR 29 TC 4 Z9 4 U1 0 U2 1 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 SEP PY 1991 VL 90 IS 1-3 BP 761 EP 779 DI 10.1016/0045-7825(91)90183-7 PG 19 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA GM296 UT WOS:A1991GM29600012 ER PT J AU VAZIRI, A AF VAZIRI, A TI SCIENTIFIC VISUALIZATION IN HIGH-SPEED NETWORK ENVIRONMENTS SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article DE SCIENTIFIC VISUALIZATION; SUPERCOMPUTER NETWORKS; COMPUTER GRAPHICS; DISTRIBUTED VISUALIZATION; VOLUME RENDERING; VISUALIZATION ENVIRONMENTS; COMPUTATIONAL FLUID DYNAMICS; NUMERICAL FLOW VISUALIZATION AB In several cases, new visualization techniques have vastly increased the researchers' ability to analyze and comprehend data. Similarly, the role of networks in providing an efficient supercomputing environment has become more critical and continues to grow and at a faster rate than the increase in the processing capabilities of supercomputers. A close relationship between scientific visualization and high-speed networks in providing an important link to support efficient supercomputing is identified. The two technologies are driven by the increasing complexities and volume of supercomputer data. The interactions of scientific visualization and high-speed networks in a Computational Fluid Dynamics simulation/visualization environment are given. Current capabilities supported by high-speed networks, supercomputers, and high-performance graphics workstations at the Numerical Aerodynamic Simulation Facility (NAS), NASA Ames Research Center are described. Applied research in providing a supercomputer visualization environments to support future computational requirements are summarized. C1 NASA,AMES RES CTR,NUMER AERODYNAM SIMULAT SYST,APPL RES OFF,MOFFETT FIELD,CA 94035. NR 50 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD SEP PY 1991 VL 22 IS 2 BP 111 EP 129 DI 10.1016/0169-7552(91)90004-V PG 19 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA GL352 UT WOS:A1991GL35200004 ER PT J AU JOHNSON, MJ AF JOHNSON, MJ TI COPING WITH DATA FROM SPACE STATION FREEDOM SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article DE SPACE STATION FREEDOM; NASA; HIGH-SPEED NETWORKS; SPACE COMMUNICATIONS; SPACE NETWORKING; DATA-HANDLING REQUIREMENTS AB The volume of data from future NASA space missions will be phenomenal. In this paper we examine the expected data flow from the Space Station Freedom and describe techniques that are being developed to transport and process that data. C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. NR 15 TC 0 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD SEP PY 1991 VL 22 IS 2 BP 131 EP 142 DI 10.1016/0169-7552(91)90005-W PG 12 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA GL352 UT WOS:A1991GL35200005 ER PT J AU WHEELER, RM TIBBITTS, TW FITZPATRICK, AH AF WHEELER, RM TIBBITTS, TW FITZPATRICK, AH TI CARBON-DIOXIDE EFFECTS ON POTATO GROWTH UNDER DIFFERENT PHOTOPERIODS AND IRRADIANCE SO CROP SCIENCE LA English DT Article ID DRY-MATTER PRODUCTION; LIFE SUPPORT SYSTEMS; CO2 ENRICHMENT; CONTROLLED ENVIRONMENTS; ATMOSPHERIC CO2; PLANT-GROWTH; PHOTOSYNTHESIS; TEMPERATURE; LIGHT; SPACE AB Carbon dioxide concentration can exert a strong influence on plant growth, but this influence can vary depending on irradiance. To study this, potato plants (Solanum tuberosum L.) cultivars 'Norland'. 'Russet Burbank', and 'Denali' were grown in controlled-environment rooms at different levels of CO2 and irradiance. Carbon dioxide levels were maintained either at 350 or 100-mu-mol mol-1 and applied in combination with 12- or 24-h photoperiods at 400 or 800-mu-mol m-2 s-1 photosynthetic photon flux. Air temperatures and relative humidity were held constant at 16-degrees-C and 70%, respectively, and plants were harvested 90 d after planting. When averaged across all cultivars, CO2 enrichment increased tuber yield and total plant dry weight by 39 and 34%, respectively, under a 12-h photoperiod at 400-mu-mol m-2 s-1; 27 and 19% under 12 h at 800-mu-mol m-2 s-1; 9 and 9% under 24 h at 400-mu-mol m-2 s-1. It decreased dry weights by 9 and 9% under 24 h at 800-mu-mol m-2 s-1. Tuber yield of Denali showed the greatest increase (21%) in response to increased CO2 across all irradiance treatments, while tuber yields of Russet Burbank and Norland were increased 18 and 9%, respectively. The results show a pattern of greater plant growth from CO2 enrichment under lower PPF and a short photoperiod. C1 UNIV WISCONSIN,DEPT HORT,MADISON,WI 53706. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. NR 28 TC 50 Z9 50 U1 0 U2 8 PU CROP SCIENCE SOC AMER PI MADISON PA 677 S SEGOE ROAD, MADISON, WI 53711 SN 0011-183X J9 CROP SCI JI Crop Sci. PD SEP-OCT PY 1991 VL 31 IS 5 BP 1209 EP 1213 PG 5 WC Agronomy SC Agriculture GA GH123 UT WOS:A1991GH12300026 PM 11537629 ER PT J AU WAGNER, JA AF WAGNER, JA TI CORRELATION OF MECHANICAL-PROPERTIES WITH METALLURGICAL STRUCTURE FOR 18NI 200 GRADE MARAGING-STEEL AT ROOM AND CRYOGENIC TEMPERATURES SO CRYOGENICS LA English DT Article DE STEEL; MECHANICAL PROPERTIES; METALLURGICAL CHARACTERIZATION AB An extensive metallurgical study was conducted to explain variations observed in the mechanical properties of 18Ni 200 grade maraging steel in various product forms and orientations. Fracture toughness, charpy impact strength, tensile properties and fatigue crack growth rate behaviour were evaluated at room and cryogenic temperatures. Fracture toughness and charpy impact values decreased with decreasing temperature and were dependent on product form, specimen orientation and metallurgical condition. Fatigue crack growth rates were found to be dependent on temperature only. Metallurgical examination was conducted using optical and scanning electron microscopy with associated energy dispersive X-ray analysis. Fractographic analysis revealed that the decrease in toughness observed at - 170-degrees-C was not associated with cleavage-type fracture morphology. Fracture was typified by microvoid coalescence at room temperature and - 170-degrees-C. However, finer dimple formation on specimens tested at - 170-degrees-C suggests that ductility may be more localized at the cryogenic temperature. Room temperature fracture surfaces were typified by a bimodal size distribution of microvoids. Those specimens exhibiting low fracture toughness at room temperature or - 170-degrees-C had a significantly larger number of titanium-rich particles associated with dimple formation on the fracture surface. RP WAGNER, JA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 10 TC 1 Z9 1 U1 0 U2 4 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD SEP PY 1991 VL 31 IS 9 BP 780 EP 785 DI 10.1016/0011-2275(91)90134-I PG 6 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA GC482 UT WOS:A1991GC48200002 ER PT J AU LEE, S KAY, YC AF LEE, S KAY, YC TI A KALMAN FILTER APPROACH FOR ACCURATE 3-D MOTION ESTIMATION FROM A SEQUENCE OF STEREO IMAGES SO CVGIP-IMAGE UNDERSTANDING LA English DT Article ID 3-DIMENSIONAL MOTION; OBJECTS; PARAMETERS C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP LEE, S (reprint author), UNIV SO CALIF,DEPT ELECT ENGN SYST,INST ROBOT & INTELLIGENT SYST,LOS ANGELES,CA 90089, USA. NR 18 TC 21 Z9 22 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 1049-9660 J9 CVGIP-IMAG UNDERSTAN PD SEP PY 1991 VL 54 IS 2 BP 244 EP 258 DI 10.1016/1049-9660(91)90066-X PG 15 WC Computer Science, Software Engineering SC Computer Science GA GC107 UT WOS:A1991GC10700006 ER PT J AU BAND, LE PETERSON, DL RUNNING, SW COUGHLAN, J LAMMERS, R DUNGAN, J NEMANI, R AF BAND, LE PETERSON, DL RUNNING, SW COUGHLAN, J LAMMERS, R DUNGAN, J NEMANI, R TI FOREST ECOSYSTEM PROCESSES AT THE WATERSHED SCALE - BASIS FOR DISTRIBUTED SIMULATION SO ECOLOGICAL MODELLING LA English DT Article ID TERRAIN; PHOTOSYNTHESIS; BALANCE AB A framework is described to compute and map forest evapotranspiration and net primary productivity over complex mountainous terrain. The methodology is based on the interface of geographic information processing and remote sensing with FOREST-BGC, a nonlinear deterministic model designed to simulate carbon, water and nitrogen cycles in a forest ecosystem. The model requires as input the geographic patterns of leaf area index (LAI), available soil water capacity (SWC) and microclimatic parameters over the landscape. These patterns are represented with the use of a template consisting of the set of hillslopes, stream channels and subwatersheds that completely define the landscape. A geo-referenced database containing digital elevation data, remotely sensed information and other environmental data are stratified by this template. We have found that the stratification of the surface data sets by a hillslope or watershed template produces landscape units with low internal variance of the important model parameters but high between unit variance. By producing templates at different levels of resolution, we have the ability to reorganize the model parameter set to different levels of surface generalization. The model is directly parameterized for each of these surface units which can then be simulated in parallel, providing the ability to expand the simulation to large regions. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV MONTANA,SCH FORESTRY,MISSOULA,MT 59812. RP BAND, LE (reprint author), UNIV TORONTO,DEPT GEOG,TORONTO M5S 1A1,ONTARIO,CANADA. RI Dungan, Jennifer/G-9921-2016 OI Dungan, Jennifer/0000-0002-4863-1616 NR 17 TC 93 Z9 103 U1 2 U2 12 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3800 J9 ECOL MODEL JI Ecol. Model. PD SEP PY 1991 VL 56 IS 1-4 BP 171 EP 196 DI 10.1016/0304-3800(91)90199-B PG 26 WC Ecology SC Environmental Sciences & Ecology GA GN057 UT WOS:A1991GN05700010 ER PT J AU CASTENHOLZ, RW JORGENSEN, BB DAMELIO, E BAULD, J AF CASTENHOLZ, RW JORGENSEN, BB DAMELIO, E BAULD, J TI PHOTOSYNTHETIC AND BEHAVIORAL VERSATILITY OF THE CYANOBACTERIUM OSCILLATORIA-BORYANA IN A SULFIDE-RICH MICROBIAL MAT SO FEMS MICROBIOLOGY ECOLOGY LA English DT Article DE OSCILLATORIA; CYANOBACTERIA; SULFIDE SPRINGS; MICROBIAL MATS; GLIDING MOTILITY; PHOTOTAXIS; ANOXYGENIC PHOTOSYNTHESIS AB The diel pattern of vertical migratory movements and photosynthetic activity of Oscillatoria cf. boryana was monitored periodically in microbial mats of a shallow tepid pond fed by sulfide-rich, hot, geothermal spring water in Rotorua, New Zealand. Motile O. boryana formed a conspicuous and predominant population which was spread over the mat surface during darkness and on overcast days (< 50-100 W m-2). Macrophotography has documented that under higher light (100-300 W m-2) much of the population contracted into streaks or patches. During periods of even higher irradiance (> 300 W m-2), O. boryana disappeared almost entirely from the mat surface to a position of about 1 mm below the surface pellicle of the mat. O2, sulfide, and pH microelectrodes inserted into excised mat cores with dense O. boryana populations were used to make vertical profiles at intervals of 0.1-0.2 mm and also to estimate rates of oxygenic and anoxygenic photosynthesis during rapid light-dark transitions. In addition, attenuation of irradiance was measured in mats with O. boryana by a spectroradiometer with mini-fiber optic probe. Light-dependent incorporation of [C-14]-bicarbonate and [C-14]-acetate was measured in collected field populations of O. boryana. The combined results led to the conclusion that populations of O. boryana typically employed sulfide-dependent anoxygenic photosynthesis in early morning which depleted sulfide locally. As irradiance increased and sulfide concentration fell below about 50-mu-M within the Oscillatoria population, oxygenic photosynthesis became dominant. [C-14]-Bicarbonate incorporation results indicate that sulfide concentrations over 1.0 mM inhibit oxygenic photosynthesis completely. In populations on excised mats, irradiance levels of about 150-200 W m-2 were required for light-enhanced oxidation of sulfide to balance sulfide input from diffusion and local production. Below that surface-irradiance level it is likely that mainly sulfide-dependent anoxygenic photosynthesis of O. boryana occurred. This capability was confirmed for O. boryana by [C-14]-photoincorporation and sulfide-microelectrode experiments. Forced exposure to high irradiance levels (500-700 W m-2) was inhibitory to oxygenic photosynthesis in O. boryana, but these intensities impinging on mats resulted in a downward retreat. The result was a lowered irradiance level for the Oscillatoria but, nevertheless, a high rate of oxygenic photosynthesis. O. boryana is a versatile cyanobacterium that appears to avoid photoinhibitory conditions and to optimize its light intensity for photosynthesis by vertical migrations, using gliding motility and some form of photoresponse. It is also able to photosynthesize at substantial rates over a wide range of sulfide concentrations by shifting between oxygenic and anoxygenic modes or possibly by combining both. C1 BAAS BECKING GEOBIOL RES LAB,CANBERRA,AUSTRALIA. AARHUS UNIV,INST ECOL & GENET,DK-8000 AARHUS,DENMARK. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CSIRO,DIV MINERAL PHYS & MINERALOL,CANBERRA,ACT 2601,AUSTRALIA. RP CASTENHOLZ, RW (reprint author), UNIV OREGON,DEPT BIOL,EUGENE,OR 97403, USA. RI Jorgensen, Bo/C-2214-2013 OI Jorgensen, Bo/0000-0001-9398-8027 NR 22 TC 34 Z9 36 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-6496 J9 FEMS MICROBIOL ECOL JI FEMS Microbiol. Ecol. PD SEP PY 1991 VL 86 IS 1 BP 43 EP 58 DI 10.1111/j.1574-6968.1991.tb04794.x PG 16 WC Microbiology SC Microbiology GA GG567 UT WOS:A1991GG56700006 ER PT J AU LIU, HS CHAO, BF AF LIU, HS CHAO, BF TI THE EARTHS EQUATORIAL PRINCIPAL AXES AND MOMENTS OF INERTIA SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Note DE EARTHS MOMENT OF INERTIA; EARTHS ROTATION ID GRAVITATIONAL-FIELD; ROTATION; HARMONICS; GRAVITY; MARS; MODEL AB Let the Earth's equatorial principal moments of inertia be A and B, where A < B, and the corresponding principal axes be a and b. Explicit formulae are here derived for determining the orientation of a and b axes and the difference B - A using C22 and S22, the two gravitational harmonic coefficients of degree 2 and order 2. For the Earth, the a axis lies along the (14.93-degrees-W, 165.07-degrees-E) diameter, and the b axis lies perpendicular to it along the (75.07-degrees-E, 104.93-degrees-W) diameter. The difference B - A is 7.260 x 10(-6) MR2. These quantities for other planets are contrasted, and geophysical implications are discussed. RP LIU, HS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 32 TC 18 Z9 19 U1 0 U2 1 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 SEP PY 1991 VL 106 IS 3 BP 699 EP 702 DI 10.1111/j.1365-246X.1991.tb06341.x PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GD658 UT WOS:A1991GD65800017 ER PT J AU SHEMANSKY, DE MORGAN, TH AF SHEMANSKY, DE MORGAN, TH TI SOURCE PROCESSES FOR THE ALKALI-METALS IN THE ATMOSPHERE OF MERCURY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SODIUM ATMOSPHERE; POTASSIUM AB A large (fivefold) increase in Mercury's potassium(K) column abundance on 14 October 1987, has been reported by Sprague et al.[1990](SKH), who attributed the enhancement to diffusion through the surface in the Caloris Basin, from depths of order 10 km. The postulated source rate is much larger than any previously estimated diffusion rate, and if true certainly affects consideration of the origin of other atmospheric species. However, Killen et al.[1991] have pointed out that the claim is not supported by the published observations of K or sodium(Na) as a whole. Sprague et al.[1991] have responded by further hypothesizing the existence of several other sources of gas diffusing out of the regolith, all of which are time variable. In any case the SKH data indicate large variations in abundance, and it is important to understand the cause. With this issue in mind we have examined the available abundance estimates for correlation with possible controlling physical parameters. We have found a significant correlation between the average zenith K column abundance and indices of solar activity, although we are left with the intrinsic uncertainty of a small data set. C1 NASA,WASHINGTON,DC 20546. RP SHEMANSKY, DE (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. RI Morgan, Thomas/I-5943-2013 NR 13 TC 25 Z9 25 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP PY 1991 VL 18 IS 9 BP 1659 EP 1662 DI 10.1029/91GL02000 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GF593 UT WOS:A1991GF59300002 ER PT J AU GLASSMEIER, KH NEUBAUER, FM BRACH, G MARSCHALL, H ACUNA, MH BURLAGA, LF MARIANI, F MUSMANN, G NESS, NF WALLIS, MK UNGSTRUP, E SCHMIDT, HU AF GLASSMEIER, KH NEUBAUER, FM BRACH, G MARSCHALL, H ACUNA, MH BURLAGA, LF MARIANI, F MUSMANN, G NESS, NF WALLIS, MK UNGSTRUP, E SCHMIDT, HU TI GIOTTO MISSION TO PLANET EARTH SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOPAUSE AB After its successful encounter with comet P/Halley and a four-years hibernation period ESA's Giotto spacecraft has been reactivated in February 1990 and performed the first-ever Earth gravity-assisted maneuver on July 2, 1990 to be retargeted for comet P/Grigg-Skjellerup. This swing-by is of unique scientific interest due to Giotto's hyperbolic, high-inclination orbit. Here, we shall report on scientific results of the Giotto magnetic field experiment. Due to the high fly-by velocity and the relative quietness of the magnetosphere during the swing-by period these measurements present a snapshot view of the Earth magnetosphere with clearly identified inbound and outbound bow shock and magnetopause crossings. The outbound crossings are of particular interest as surface waves at the polar magnetopause at a distance of 28 R(E) as well as a strong quasi-perpendicular bow shock at a distance of about 64 R(E) are observed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV ROME,DIPARTIMENTO FIS,I-00173 ROME,ITALY. TECH UNIV BRAUNSCHWEIG,INST GEOPHYS & METEOROL,W-3300 BRAUNSCHWEIG,GERMANY. UNIV DELAWARE,BARTOL RES FDN,NEWARK,DE 19716. DANISH SPACE RES INST,DK-2800 LYNGBY,DENMARK. MAX PLANCK INST ASTROPHYS,W-8046 GARCHING,GERMANY. UNIV WALES COLL CARDIFF,CARDIFF CF1 1XL,S GLAM,WALES. RP GLASSMEIER, KH (reprint author), UNIV COLOGNE,INST GEOPHYS & METEOROL,W-5000 COLOGNE 41,GERMANY. NR 14 TC 8 Z9 8 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 SEP PY 1991 VL 18 IS 9 BP 1663 EP 1666 DI 10.1029/91GL00550 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GF593 UT WOS:A1991GF59300003 ER PT J AU VANZYL, JJ BURNETTE, CF FARR, TG AF VANZYL, JJ BURNETTE, CF FARR, TG TI INFERENCE OF SURFACE POWER SPECTRA FROM INVERSION OF MULTIFREQUENCY POLARIMETRIC RADAR DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LAVA AB During the summer of 1988 an intensive field experiment was conducted in the vicinity of Pisgah lava field in the Mojave Desert of southern California. As part of the experiment, physical properties such as microtopography, composition, soil moisture and dielectric constant at five different sites representing surfaces with r.m.s. heights varying from less than one centimeter to tens of centimeters, were measured. In addition, polarimetric radar images at P-band (68 cm wavelength), L-band (24 cm) and C-band (5.7 cm) were acquired at three different incidence angles with the NASA/JPL airborne imaging radar polarimeter. Using trihedral corner reflectors deployed in the area prior to imaging, the radar images were calibrated to provide sigma-0 values for each resolution element in each scene. This paper reports on the derivation of the power spectrum of surface microtopography by solution of the small perturbation model for multiple incidence angle and multiple frequency radar data. Power-law fits to the power spectra have exponents (slope in log-log plots) that are nearly the same for all surfaces. These values are close to those from measured microtopography profiles. The offset in log-log plots shows very good correlation with measured power spectrum offsets, however the image-derived offsets are consistently lower than measured values. This may be the result of calibration errors, using the wrong dielectric constants in the inversion, or the fact that not all observed energy was scattered by the surface interface alone. RP VANZYL, JJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. OI Farr, Thomas/0000-0001-5406-2096 NR 11 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP PY 1991 VL 18 IS 9 BP 1787 EP 1790 DI 10.1029/91GL02162 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GF593 UT WOS:A1991GF59300034 ER PT J AU MLYNCZAK, MG SOLOMON, S AF MLYNCZAK, MG SOLOMON, S TI MIDDLE ATMOSPHERE HEATING BY EXOTHERMIC CHEMICAL-REACTIONS, INVOLVING ODD-HYDROGEN SPECIES - REPLY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Note ID DIPOLE-MOMENT FUNCTION; TRANSITION-PROBABILITIES; HYDROXYL; OH C1 NOAA,AERON LAB,BOULDER,CO 80303. RP MLYNCZAK, MG (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 401B,HAMPTON,VA 23665, USA. RI Mlynczak, Martin/K-3396-2012 NR 10 TC 3 Z9 3 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 SEP PY 1991 VL 18 IS 9 BP 1793 EP 1794 DI 10.1029/91GL02139 PG 2 WC Geosciences, Multidisciplinary SC Geology GA GF593 UT WOS:A1991GF59300036 ER PT J AU HOOK, SJ ELVIDGE, CD RAST, M WATANABE, H AF HOOK, SJ ELVIDGE, CD RAST, M WATANABE, H TI AN EVALUATION OF SHORT-WAVE-INFRARED (SWIR) DATA FROM THE AVIRIS AND GEOSCAN INSTRUMENTS FOR MINERALOGICAL MAPPING AT CUPRITE, NEVADA SO GEOPHYSICS LA English DT Article ID MU-M; SCANNER; IMAGES AB An evaluation was performed on SWIR (2000-2400 nm) data from two airborne remote sensing systems for discriminating and identifying alteration minerals at Cuprite, Nevada. The data were acquired by the NASA Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) and the GEOSCAN Mk II multispectral scanner. The evaluation involved comparison of processed imagery and image-derived spectra with existing alteration maps and laboratory spectra of rock samples from Cuprite. Results indicate that both the AVIRIS and GEOSCAN data permit the discrimination of areas of alunite, buddingtonite, kaolinite, and silicification using color composite images formed from three SWIR bands processed with either the decorrelation stretch or a log residual algorithm. The laboratory spectral features of alunite, kaolinite and buddingtonite could be seen clearly only in the log residual processed AVIRIS data. However, this does not preclude their identification with the GEOSCAN data. C1 UNIV NEVADA SYST,DESERT RES INST,RENO,NV. UNIV NEVADA SYST,RENO,NV. JAPEX GEOSCI INST,TOKYO,JAPAN. EUROPEAN SPACE AGCY,2200 AG NOORDWIJK,NETHERLANDS. RP HOOK, SJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Elvidge, Christopher/C-3012-2009 NR 31 TC 17 Z9 17 U1 0 U2 4 PU SOC EXPLORATION GEOPHYSICISTS PI TULSA PA 8801 S YALE ST, TULSA, OK 74137 SN 0016-8033 J9 GEOPHYSICS JI Geophysics PD SEP PY 1991 VL 56 IS 9 BP 1432 EP 1440 DI 10.1190/1.1443163 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GF113 UT WOS:A1991GF11300012 ER PT J AU SHINN, JL WILSON, JW AF SHINN, JL WILSON, JW TI NUCLEAR-REACTION EFFECTS IN USE OF NEWLY RECOMMENDED QUALITY FACTOR SO HEALTH PHYSICS LA English DT Note ID RISK ASSESSMENT AB The biological risk for energetic ion exposure cannot be reliably estimated exclusive of the target nuclear reaction products produced within the local tissue. A theoretical basis is derived for evaluating target fragment contributions that are evaluated for the newly proposed quality factor. RP SHINN, JL (reprint author), NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NR 16 TC 3 Z9 3 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0017-9078 EI 1538-5159 J9 HEALTH PHYS JI Health Phys. PD SEP PY 1991 VL 61 IS 3 BP 415 EP 419 DI 10.1097/00004032-199109000-00013 PG 5 WC Environmental Sciences; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA GD979 UT WOS:A1991GD97900013 PM 1652577 ER PT J AU OLIVERSEN, RJ SCHERB, F ROESLER, FL AF OLIVERSEN, RJ SCHERB, F ROESLER, FL TI THE IO SULFUR TORUS IN 1981 SO ICARUS LA English DT Article ID JUPITER PLASMA TORUS; PLANETARY-NEBULAE; LO TORUS; S-III; EMISSION; VOYAGER; WAVELENGTHS; ASYMMETRY; IMAGES; ENERGY C1 UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. RP OLIVERSEN, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 684,GREENBELT,MD 20771, USA. NR 41 TC 16 Z9 16 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1991 VL 93 IS 1 BP 53 EP 62 DI 10.1016/0019-1035(91)90163-N PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE545 UT WOS:A1991GE54500004 ER PT J AU HOBAN, S MUMMA, M REUTER, DC DISANTI, M JOYCE, RR STORRS, A AF HOBAN, S MUMMA, M REUTER, DC DISANTI, M JOYCE, RR STORRS, A TI A TENTATIVE IDENTIFICATION OF METHANOL AS THE PROGENITOR OF THE 3.52-MU-M EMISSION FEATURE IN SEVERAL COMETS SO ICARUS LA English DT Article ID MU-M; HALLEY; SPECTRUM; SPECTROSCOPY; FORMALDEHYDE; P/HALLEY; FIELD C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,PLANETARY SYST BRANCH,GREENBELT,MD 20771. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RP HOBAN, S (reprint author), KITT PEAK NATL OBSERV,POB 26732,TUCSON,AZ 85727, USA. RI mumma, michael/I-2764-2013 NR 28 TC 65 Z9 65 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1991 VL 93 IS 1 BP 122 EP 134 DI 10.1016/0019-1035(91)90168-S PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE545 UT WOS:A1991GE54500009 ER PT J AU HALTHORE, R KRATZ, D AF HALTHORE, R KRATZ, D TI SIMULATION OF THE SPECTRAL CONTENT OF THE 7.8-MU-M EMISSION FROM JUPITER AT HIGH-RESOLUTION SO ICARUS LA English DT Note ID H-3+ C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. RP HALTHORE, R (reprint author), ST SYST CORP,LANHAM,MD 20706, USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1991 VL 93 IS 1 BP 174 EP 178 DI 10.1016/0019-1035(91)90172-P PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE545 UT WOS:A1991GE54500013 ER PT J AU REED, IS SHIH, MT TRUONG, TK AF REED, IS SHIH, MT TRUONG, TK TI VLSI DESIGN OF INVERSE-FREE BERLEKAMP-MASSEY ALGORITHM SO IEE PROCEEDINGS-E COMPUTERS AND DIGITAL TECHNIQUES LA English DT Article DE VERY LARGE SCALE INTEGRATION; ALGORITHMS AB The Berlekamp-Massey algorithm for decoding BCH codes is modified to eliminate the calculation of inverses. This new algorithm is useful in the practical application of multiple-error-correcting BCH or RS codes. A VLSI architecture is developed for this algorithm. C1 CALTECH,JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109. RP REED, IS (reprint author), UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089, USA. NR 7 TC 51 Z9 58 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 SEP PY 1991 VL 138 IS 5 BP 295 EP 298 PG 4 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA GG019 UT WOS:A1991GG01900002 ER PT J AU HWANG, IH LEE, JH AF HWANG, IH LEE, JH TI EFFICIENCY AND THRESHOLD PUMP INTENSITY OF CW SOLAR-PUMPED SOLID-STATE LASERS SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID ALEXANDRITE LASERS; YAG LASER AB The efficiencies and threshold pump intensities of various solid-state laser materials have been estimated to compare their performance characteristics as direct solar-pumped CW lasers. Among the laser materials evaluated in this research, alexandrite has the highest slope efficiency of about 12.6%; however, it does not seem to be practical for solar-pumped laser application because of its high threshold pump intensity. Cr:Nd:GSGG is the most promising for solar-pumped lasing. Its threshold pump intensity is about 100 airmass-zero (AM0) solar constants and its slope efficiency is about 12% when thermal deformation is completely prevented. C1 HAMPTON UNIV,INST SPACEBORNE PHOTON,HAMPTON,VA 23668. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HWANG, IH (reprint author), HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668, USA. NR 23 TC 8 Z9 8 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD SEP PY 1991 VL 27 IS 9 BP 2129 EP 2134 DI 10.1109/3.135171 PG 6 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA GJ183 UT WOS:A1991GJ18300008 ER PT J AU FLOWER, J KOLAWA, A LIANG, T WEINGARTEN, V AF FLOWER, J KOLAWA, A LIANG, T WEINGARTEN, V TI FINITE-ELEMENT ANALYSIS ON A PC SO IEEE SOFTWARE LA English DT Article C1 PARASOFT CORP,GIGABIT PROJECT,PASADENA,CA 91107. UNIV SO CALIF,ENGN,LOS ANGELES,CA 90089. RP FLOWER, J (reprint author), PARASOFT CORP,JET PROPUL LAB,2500 E FOOTHILL BLVD,STE 205,PASADENA,CA 91107, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD SEP PY 1991 VL 8 IS 5 BP 50 EP 57 DI 10.1109/52.84216 PG 8 WC Computer Science, Software Engineering SC Computer Science GA GD057 UT WOS:A1991GD05700010 ER PT J AU IMBRIALE, WA GALINDOISRAEL, V RAHMATSAMII, Y AF IMBRIALE, WA GALINDOISRAEL, V RAHMATSAMII, Y TI ON THE REFLECTIVITY OF COMPLEX MESH SURFACES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB Wire mesh knit reflecting surfaces are now frequently used on unfurlable type spacecraft reflector antennas (Tracking and Data Relay Satellite System (TDRSS), Galileo, etc.). The fineness of the wires and the complexity of the weave has made the problem of an exact numerical diffraction analysis quite formidable. In this paper this type of mesh is analyzed by treating it as a flat weave of intertwined wire strips in a periodic array. The analysis is by moment methods using a piecewise triangular basis function with a Floquet mode analysis of the periodic structure. Since the analysis uses a flat strip model and the actual mesh is composed of round wire, an equivalent radius of one-fourth the strip width is used to equate round wire and flat strips. In particular, it is found that bends and junctions can be properly treated only if precise and careful attention is paid to the vector continuity of current through the bends. It is common in some fine wire mesh grids to avoid soldering the junctions of wires and to depend upon contact pressure in order to obtain good electrical continuity at junction points. Under certain conditions, as has been found experimentally, poor electrical contact at the junction points can result in poor surface reflectivity and considerable transmission loss. Analytical examples of this loss are presented. Data are also presented for the cases of nonreflective (resistive) junction contacts. This leads to a simple model of the tricot mesh that provides an explanation of poor reflectivity. Finally, a comprehensive set of experiments is conducted to provide a solid validation of the theory. C1 UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024. RP IMBRIALE, WA (reprint author), CALTECH,JET PROP LAB,GROUND ANTENNAS & FACIL ENGN SECT,PASADENA,CA 91109, USA. NR 8 TC 19 Z9 20 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 SEP PY 1991 VL 39 IS 9 BP 1352 EP 1365 DI 10.1109/8.99044 PG 14 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GL904 UT WOS:A1991GL90400011 ER PT J AU HAO, L KIM, HD HALLOCK, GA BIRKNER, BW ZAMAN, AJM AF HAO, L KIM, HD HALLOCK, GA BIRKNER, BW ZAMAN, AJM TI EFFECT OF AN ARCJET PLUME ON SATELLITE REFLECTOR PERFORMANCE SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB The effect of an arcjet plume on the performance of satellite reflector antennas is studied. The arcjet plume is modeled as a weakly ionized plasma. Spatial permittivity distribution of the plume is approximated using the measured electron density profile and a cold plasma model. Geometrical optics is applied to determine the ray paths as well as the transmitted fields through the inhomogenous plume. The ray optics results are compared against several exact solutions for scattering from inhomogenous dielectrics and good agreement is observed for sufficiently large scatterer size. The far-field antenna patterns of the reflector in the presence of the plume are calculated from the transmitted ray fields using a ray-tube integration scheme. For arcjet prototypes in the 1-kW class, the plume effect on the antenna performance is small. As the electron density increases (corresponding to higher arcjet power), a gradual degradation of the main beam and sidelobe level is observed. In addition, the main beam tends to squint away from the plume region. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP HAO, L (reprint author), UNIV TEXAS,DEPT ELECT & COMP ENGN,AUSTIN,TX 78712, USA. NR 19 TC 11 Z9 11 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 SEP PY 1991 VL 39 IS 9 BP 1412 EP 1420 DI 10.1109/8.99052 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GL904 UT WOS:A1991GL90400019 ER PT J AU BAYARD, DS AF BAYARD, DS TI A FORWARD METHOD FOR OPTIMAL STOCHASTIC NONLINEAR AND ADAPTIVE-CONTROL SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note ID SYSTEMS AB A computational approach is taken to solve the optimal partially observed nonlinear stochastic control problem. The approach is to systematically solve the stochastic dynamic programming equations forward in time, using a nested stochastic approximation technique. Although computationally intensive, this provides a straightforward numerical solution for this class of problems and provides an alternative to the usual "curse of dimensionality" associated with solving the dynamic programming equations backwards in time. In particular, the "curse" is seen to take a new form, where the amount of computation depends on the amount of uncertainty in the problem and the length of the horizon. As a matter of more practical interest, it is shown that the cost degrades monotonically as the complexity of the algorithm is reduced. This provides a strategy for suboptimal control with clear performance/computation trade-offs. Due to a strong connection with the work of Bellman on policy iteration, the method is denoted as the iteration in policy space (IPS) algorithm. A numerical study focusing on a generic optimal stochastic adaptive control example is included to demonstrate the feasibility of the method. RP BAYARD, DS (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 31 TC 25 Z9 25 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD SEP PY 1991 VL 36 IS 9 BP 1046 EP 1053 DI 10.1109/9.83535 PG 8 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA GC110 UT WOS:A1991GC11000005 ER PT J AU KOZU, T NAKAMURA, K MENEGHINI, R BONCYK, WC AF KOZU, T NAKAMURA, K MENEGHINI, R BONCYK, WC TI DUAL-PARAMETER RADAR RAINFALL MEASUREMENT FROM SPACE - A TEST RESULT FROM AN AIRCRAFT EXPERIMENT SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB An aircraft experiment has been conducted with a dual-frequency (X/Ka-bands) radar to test various rainfall retrieval methods from space. In this paper, we test a method to derive raindrop size distribution (DSD) parameters from the combination of a radar reflectivity profile (in our test, X-band) and a path-integrated attenuation derived from surface return, which may be available from most spaceborne radars. The estimated DSD parameters are reasonable in that the values generally fall within the range of commonly measured ones and that shifts in DSD parameters appear to be correlated with changes in storm type. The validity of the estimation result is also demonstrated by a consistency check using the Ka-band reflectivity profile which is independent of the DSD estimation process. Although errors may occur in the cases of nonuniform beam filling, these test results indicate the feasibility of the dual-parameter radar measurement from space to achieve a better accuracy in quantitative rainfall remote measurements. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KOZU, T (reprint author), COMMUN RES LABS,KOGANEI,TOKYO 184,JAPAN. NR 23 TC 29 Z9 30 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 SEP PY 1991 VL 29 IS 5 BP 690 EP 703 DI 10.1109/36.83983 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA GD090 UT WOS:A1991GD09000001 ER PT J AU FREEMAN, A AF FREEMAN, A TI A NEW SYSTEM MODEL FOR RADAR POLARIMETERS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID CALIBRATION; IMAGES AB The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed in [1], is questioned. The model is found to be invalid for many practical realizations of radar polarimeters. This can lead to significant errors in the calibration of polarimetric radar images. A new, more general model is put forward, which includes the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARC's in polarimetric calibration and to measure the orientation angle of the H-V coordinate system are also presented. RP FREEMAN, A (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 12 Z9 17 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 SEP PY 1991 VL 29 IS 5 BP 761 EP 767 DI 10.1109/36.83991 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA GD090 UT WOS:A1991GD09000009 ER PT J AU VANZYL, JJ BURNETTE, CF AF VANZYL, JJ BURNETTE, CF TI DATA VOLUME REDUCTION FOR SINGLE-LOOK POLARIMETRIC IMAGING RADAR DATA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note AB An 8-b quantization scheme to reduce the data volume for single-look complex scattering matrix data measured by polarimetric imaging radar systems is described. The scattering matrices are not symmetrized before compression, retaining information about background noise and system effects. The data volume is reduced by a factor of 3.2. It is shown, with measured data, that the singal to quantization noise ratio for the compression scheme is more than 35 dB for the cross-polarized channels, and more than 45 dB for the copolarized channels. RP VANZYL, JJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 4 Z9 4 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 SEP PY 1991 VL 29 IS 5 BP 784 EP 786 DI 10.1109/36.83994 PG 3 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA GD090 UT WOS:A1991GD09000012 ER PT J AU CWIK, T PARTEE, J PATTERSON, J AF CWIK, T PARTEE, J PATTERSON, J TI METHOD OF MOMENT SOLUTIONS TO SCATTERING PROBLEMS IN A PARALLEL PROCESSING ENVIRONMENT SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 4TH BIENNIAL CONF ON ELECTROMAGNETIC FIELD COMPUTATION CY OCT 22-24, 1990 CL TORONTO, CANADA SP IEEE ID RADIATION AB This paper describes the implementation of a parallelized method of moments (MoM) code into an interactive workstation environment. The workstation allows interactive solid body modeling and mesh generation, MoM analysis, and the graphical display of results. After describing the parallel computing environment, the implementation and results of parallelizing a general MoM code is presented in detail. RP CWIK, T (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 10 Z9 10 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 1991 VL 27 IS 5 BP 3837 EP 3840 DI 10.1109/20.104938 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA GT689 UT WOS:A1991GT68900016 ER PT J AU BAUMEISTER, KJ AF BAUMEISTER, KJ TI EFFECT OF SURFACE DEPOSITS ON ELECTROMAGNETIC PROPAGATION IN UNIFORM DUCTS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 4TH BIENNIAL CONF ON ELECTROMAGNETIC FIELD COMPUTATION CY OCT 22-24, 1990 CL TORONTO, CANADA SP IEEE AB A finite-element Galerkin formulation has been used to study the effect of material surface deposits on the reflective characteristics of straight uniform ducts with PEC (perfectly electric conducting) walls. Over a wide frequency range, the effect of both single and multiple dielectric surface deposits on the duct reflection coefficient were examined. The power reflectior coefficient was found to be significantly increased by the addition of deposits on the wall. RP BAUMEISTER, KJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 7 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 1991 VL 27 IS 5 BP 4044 EP 4047 DI 10.1109/20.104989 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA GT689 UT WOS:A1991GT68900067 ER PT J AU CHEW, W RILEY, AL RASCOE, DL HUNT, BD FOOTE, MC COOLEY, TW BAJUK, LJ AF CHEW, W RILEY, AL RASCOE, DL HUNT, BD FOOTE, MC COOLEY, TW BAJUK, LJ TI DESIGN AND PERFORMANCE OF A HIGH-TC SUPERCONDUCTOR COPLANAR WAVE-GUIDE FILTER SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID TRANSMISSION-LINE RESONATOR; EQUIVALENCE METHOD; THIN-FILMS; YBA2CU3O7-X; PULSES AB Coplanar waveguide is a convenient structure for microwave circuits using high-critical-temperature superconductor thin films. The design of a coplanar waveguide low-pass filter made of YBa2Cu3O7-delta (YBCO) on an LaAlO3 substrate is described. Measurements were incorporated into simple models for microwave CAD analysis to develop a final design. The patterned and packaged coplanar waveguide low-pass filter of YBCO, with dimensions suited for integrated circuits, exhibited measured insertion losses when cooled in liquid nitrogen superior to those of a similarly cooled thin-film copper filter throughout the 0 to 9.5 GHz passband. Coplanar waveguide models for use with thin-film normal metal (with thickness either greater or less than the skin depth) and YBCO are discussed and used to compare the losses of the measured YBCO and copper circuits. C1 CALTECH,JET PROP LAB,NASA COMMUN TECHNOL PROGRAM,PASADENA,CA 91109. RP CHEW, W (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 20 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD SEP PY 1991 VL 39 IS 9 BP 1455 EP 1461 DI 10.1109/22.83817 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA GA255 UT WOS:A1991GA25500003 ER PT J AU CHOREY, CM KONG, KS BHASIN, KB WARNER, JD ITOH, T AF CHOREY, CM KONG, KS BHASIN, KB WARNER, JD ITOH, T TI YBCO SUPERCONDUCTING RING RESONATORS AT MILLIMETER-WAVE FREQUENCIES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID YBA2CU3O7-X AB Superconducting microstrip ring resonators operating at 35 GHz have been fabricated from laser ablated YBa2Cu3O7-x (YBCO) films on lanthanum aluminate substrates. The circuits consist of superconducting strips over normal metal ground planes. The circuits are measured from 20 K to 90 K and with microwave input powers ranging from 0.25 mW to 10 mW. The superconducting resonators show significant improvement in Q (six to seven times higher) over identical gold resonators at 20 K, but only marginal improvement at 77 K. No variation in the superconductor performance is observed with varying input power. Using a microstrip loss model, the microwave surface resistance of the superconductors is extracted; the lowest value obtained at 77 K is 9 m-OMEGA. The change in the resonant frequency with temperature is analyzed and a value for the penetration depth computed. "Double resonances" observed in some superconducting ring resonators are described and an explanation for their presence advanced. Factors limiting millimeter-wave high-temperature superconductor circuits are explored and potential performance levels calculated based on current reported values for high-temperature superconductor surface resistances. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV TEXAS,DEPT ELECT & COMP ENGN,AUSTIN,TX 78712. RP CHOREY, CM (reprint author), SVERDRUP TECHNOL INC,LERC GRP,2001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 15 TC 37 Z9 37 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD SEP PY 1991 VL 39 IS 9 BP 1480 EP 1487 DI 10.1109/22.83821 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA GA255 UT WOS:A1991GA25500007 ER PT J AU FALES, CL HUCK, FO AF FALES, CL HUCK, FO TI AN INFORMATION-THEORY OF IMAGE GATHERING SO INFORMATION SCIENCES LA English DT Article ID RESTORATION; FIDELITY; DESIGN; CORTEX; MODEL AB Shannon's mathematical theory of communication is extended to image gathering. The performance of image gathering, as well as of natural vision, is critically constrained by the realizability of the spatial-frequency response of optical apertures, the sampling passband of the photon-detection mechanism, and the signal-to-noise ratio. Hence, whereas Shannon could assume sufficient sampling, we have to deal with insufficient sampling. This extension requires a careful examination of the basic principles of information theory to obtain an unambiguous quantitative description of information for undersampled systems. In this paper we obtain expressions for the total information that is received with a single image-gathering channel and with parallel channels. Some of these expressions challenge intuition, but, when properly interpreted, have clear and precise meaning. The thrust of this meaning leads inexorably to the conclusion that the aliased signal components carry information even though these components interfere with the within-passband signal components in conventional image gathering and restoration, thereby degrading the fidelity and visual quality of the restored image. But a close examination of the expression for minimum mean-square-error, or Wiener-matrix, restoration from parallel image-gathering channels also reveals a method for unscrambling the within-passband and aliased signal components to restore spatial frequencies beyond the sampling passband out to the spatial-frequency response cutoff of the optical aperture. This method requires us to gather K discrete images, each with a different image-gathering response, i.e., channel as obtained, for example, by changing the objective lens aperture, to restore images with a resolution that is square-root K times finer than the sampling interval. RP FALES, CL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 17 TC 13 Z9 13 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0020-0255 J9 INFORM SCIENCES JI Inf. Sci. PD SEP-DEC PY 1991 VL 57-8 BP 245 EP 285 DI 10.1016/0020-0255(91)90082-6 PG 41 WC Computer Science, Information Systems SC Computer Science GA FN459 UT WOS:A1991FN45900018 ER PT J AU CHAUDHRY, MI BERRY, WB ZELLER, MV AF CHAUDHRY, MI BERRY, WB ZELLER, MV TI A STUDY OF OHMIC CONTACTS ON BETA-SIC SO INTERNATIONAL JOURNAL OF ELECTRONICS LA English DT Article AB A study on ohmic contacts on beta-SiC is reported. The contacts were formed using titanium, tungsten, and their silicides. The tungsten and titanium contacts exhibited ohmic behaviour following annealing at a low-temperature (300-degrees-C) but deteriorated when annealed at 600-degrees-C. The minimum contact resistance for titanium and tungsten on SiC was 7.6 x 10(-3) and 6.1 x 10(-3) ohm-cm2, respectively. The silicides of titanium and tungsten yielded a lower contact resistance than the metallic Ti and W. The minimum contact resistance for TiSi2 and WSi2 is 1.1 x 10(-4) and 3.0 x 10(-4) ohm-cm2, respectively. C1 UNIV NOTRE DAME,DEPT ELECT & COMP ENGN,NOTRE DAME,IN 46556. NASA,LEWIS RES CTR,RES SENSOR BRANCH,CLEVELAND,OH 44135. RP CHAUDHRY, MI (reprint author), CLARKSON UNIV,DEPT ELECT & COMP ENGN,POTSDAM,NY 13676, USA. NR 10 TC 15 Z9 15 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0020-7217 J9 INT J ELECTRON JI Int. J. Electron. PD SEP PY 1991 VL 71 IS 3 BP 439 EP 444 DI 10.1080/00207219108925489 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA GE541 UT WOS:A1991GE54100006 ER PT J AU WADHAMS, P DAVIS, NR COMISO, JC KUTZ, R CRAWFORD, J JACKSON, G KRABILL, W SEAR, CB SWIFT, R TUCKER, WB AF WADHAMS, P DAVIS, NR COMISO, JC KUTZ, R CRAWFORD, J JACKSON, G KRABILL, W SEAR, CB SWIFT, R TUCKER, WB TI CONCURRENT REMOTE-SENSING OF ARCTIC SEA ICE FROM SUBMARINE AND AIRCRAFT SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB In May 1987 a concurrent remote sensing study of Arctic sea ice from above and below was carried out. A submarine equipped with sidescan and upward looking sonar collaborated with two remote sensing aircraft equipped with passive microwave, synthetic aperture radar (SAR), a laser profilometer and an infrared radiometer. By careful registration of the three tracks it has been possible to find relationships between ice type, ice morphology and thickness, SAR backscatter and microwave brightness temperatures. The key to the process has been the sidescan sonar's ability to identify ice type through differences in characteristic topography. Over a heavily ridged area of mainly multiyear ice there is a strong positive correlation between SAR backscatter and ice draft or elevation. We also found that passive and active microwave complement each other in that SAR has a high contrast between open water and multiyear ice, while passive microwave has a high contrast between open water and first-year ice. C1 NASA,GODDARD SPACE FLIGHT CTR,GODDARD SPACE FLIGHT LAB,OCEAN LAB,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. ADMIRALTY RES ESTAB,PORTLAND,DORSET,ENGLAND. NASA,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. SCI APPLICAT INT CORP,WESTBROOK CTR,CAMBRIDGE CB4 1YQ,ENGLAND. EGEG WASHINGTON ANALYT SERV CTR,POCOMOKE CITY,MD 21851. USA,COLD REG RES & ENGN LAB,HANOVER,NH 03755. RP WADHAMS, P (reprint author), UNIV CAMBRIDGE,SCOTT POLAR RES INST,CAMBRIDGE CB2 1ER,ENGLAND. NR 8 TC 17 Z9 17 U1 1 U2 7 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD SEP PY 1991 VL 12 IS 9 BP 1829 EP 1840 PG 12 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA GE543 UT WOS:A1991GE54300004 ER PT J AU RAY, RD KOBLINSKY, CJ BECKLEY, BD AF RAY, RD KOBLINSKY, CJ BECKLEY, BD TI ON THE EFFECTIVENESS OF GEOSAT ALTIMETER CORRECTIONS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Letter ID OCEAN TIDE AB Measurements of sea level by a satellite altimeter require a number of corrections for atmospheric and geophysical effects. We have examined the effectiveness of a large suite of correction terms for Geosat by studying how each correction affects the variances of altimetric sea-surface height differences. Most corrections were found to provide a significant reduction in variance, the most important exception being certain short-period wet-troposphere corrections. Our procedure of using height differences implies nothing about the time-invariant parts of corrections. C1 NASA,GODDARD SPACE FLIGHT CTR,SPAE GEODESY BRANCH,GREENBELT,MD 20771. ST SYST CORP,LANHAM,MD. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012 NR 13 TC 13 Z9 14 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD SEP PY 1991 VL 12 IS 9 BP 1979 EP 1984 PG 6 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA GE543 UT WOS:A1991GE54300017 ER PT J AU DAWSON, JM SYDORA, RD DECYK, VK LIEWER, PC FERRARO, RD AF DAWSON, JM SYDORA, RD DECYK, VK LIEWER, PC FERRARO, RD TI PHYSICS MODELING OF TOKAMAK TRANSPORT - A GRAND CHALLENGE FOR CONTROLLED FUSION SO INTERNATIONAL JOURNAL OF SUPERCOMPUTER APPLICATIONS AND HIGH PERFORMANCE COMPUTING LA English DT Article ID GYROKINETIC PARTICLE SIMULATION; MICROTURBULENCE AB A challenge facing fusion is accurate prediction and understanding of plasma and heat confinement. Computers and modeling techniques have advanced to where we can envision simulating real Tokamaks starting from fundamental physics models. Charged particles in magnetic fields execute rapidly gyrating motions about the field. These orbits gradually drift where electric fields and magnetic nonuniformities exist. The gyrokinetic model averages out the rapid gyration and treats the plasma as a large number of drifting rings of charge and current; large numbers (approx. 10(6)) of such rings are followed in their self-consistent electric and magnetic fields. Three-dimensional simulations of plasma and heat confinement for situations relevant to fusion give turbulence spectra and transport coefficients similar to experiments. Simpler particle models of plasma run on hypercubes achieves a high degree of parallelism (95%). With new parallel machines substantial gains in speed and memory can be expected; modeling of real Tokamaks should be possible. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. RP DAWSON, JM (reprint author), UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024, USA. NR 14 TC 5 Z9 5 U1 1 U2 1 PU SAGE SCIENCE PRESS PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 SN 1078-3482 J9 INT J SUPERCOMPUT AP JI Int. J. Supercomput. Appl. High Perform. Comput. PD FAL PY 1991 VL 5 IS 3 BP 13 EP 35 DI 10.1177/109434209100500303 PG 23 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications SC Computer Science GA GK699 UT WOS:A1991GK69900003 ER PT J AU BAILEY, DH BARSZCZ, E BARTON, JT BROWNING, DS CARTER, RL DAGUM, L FATOOHI, RA FREDERICKSON, PO LASINSKI, TA SCHREIBER, RS SIMON, HD VENKATAKRISHNAN, V WEERATUNGA, SK AF BAILEY, DH BARSZCZ, E BARTON, JT BROWNING, DS CARTER, RL DAGUM, L FATOOHI, RA FREDERICKSON, PO LASINSKI, TA SCHREIBER, RS SIMON, HD VENKATAKRISHNAN, V WEERATUNGA, SK TI THE NAS PARALLEL BENCHMARKS SO INTERNATIONAL JOURNAL OF SUPERCOMPUTER APPLICATIONS AND HIGH PERFORMANCE COMPUTING LA English DT Article AB A new set of benchmarks has been developed for the performance evaluation of highly parallel supercomputers. These consist of five "parallel kernel" benchmarks and three "simulated application" benchmarks. Together they mimic the computation and data movement characteristics of large-scale computational fluid dynamics applications. The principal distinguishing feature of these benchmarks is their "pencil and paper" specification-all details of these benchmarks are specified only algorithmically. In this way many of the difficulties associated with conventional benchmarking approaches on highly parallel systems are avoided. RP BAILEY, DH (reprint author), NASA,AMES RES CTR,NAS APPL RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 14 TC 288 Z9 291 U1 0 U2 0 PU SAGE SCIENCE PRESS PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 SN 1078-3482 J9 INT J SUPERCOMPUT AP JI Int. J. Supercomput. Appl. High Perform. Comput. PD FAL PY 1991 VL 5 IS 3 BP 63 EP 73 DI 10.1177/109434209100500306 PG 11 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications SC Computer Science GA GK699 UT WOS:A1991GK69900006 ER PT J AU SHEEHAN, W AF SHEEHAN, W TI THE FINAL FRONTIER SO ISSUES IN SCIENCE AND TECHNOLOGY LA English DT Editorial Material RP SHEEHAN, W (reprint author), NASA,PUBL AFFAIRS,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 SN 0748-5492 J9 ISSUES SCI TECHNOL JI Issues Sci. Technol. PD FAL PY 1991 VL 8 IS 1 BP 8 EP & PG 0 WC Engineering, Multidisciplinary; Engineering, Industrial; Multidisciplinary Sciences; Social Issues SC Engineering; Science & Technology - Other Topics; Social Issues GA GJ757 UT WOS:A1991GJ75700005 ER PT J AU JOHNSON, WS BIRT, MJ AF JOHNSON, WS BIRT, MJ TI COMPARISON OF SOME MICROMECHANICS MODELS FOR DISCONTINUOUSLY REINFORCED METAL MATRIX COMPOSITES SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE ALUMINUM MATRIX; SILICON-CARBIDE PARTICULATE; SILICON-CARBIDE WHISKERS; MICROSTRUCTURE; MODULI AB A systematic experimental evaluation of whisker- and particulate-reinforced aluminum matrix composites was conducted to assess the variation in tensile properties with reinforcement type, volume fraction, and specimen thickness. Each material was evaluated in three thicknesses, 1.8, 3.18, and 6.35 mm, to determine the size, distribution, and orientation of the reinforcements. This information was used to evaluate several micromechanics models that predict composite moduli. The longitudinal and transverse moduli were predicted for 15 volume percent (v/%) SiCp-reinforced aluminum and for 15 and 30 v/% SiCw-reinforced aluminum. The Paul, Cox, and Halpin-Tsai models were evaluated. The Paul model gave a good upper bound prediction for the particulate-reinforced composites but underpredicted whisker-reinforced composite moduli. The Cox model gave good moduli predictions for the whisker reinforcement but was too low for the particulate. The Halpin-Tsai model gave good results for both whisker- and particulate-reinforced composites. An approach using a trigonometric projection of whisker length to predict the fiber contribution to the modulus in the longitudinal and transverse directions was compared to the more conventional lamination theory approach. RP JOHNSON, WS (reprint author), NASA,LANGLEY RES CTR,ANALYT SERV & MAT,MS 188E,HAMPTON,VA 23665, USA. NR 9 TC 7 Z9 7 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 FAL PY 1991 VL 13 IS 3 BP 161 EP 167 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA GG632 UT WOS:A1991GG63200003 ER PT J AU RAI, MM MOIN, P AF RAI, MM MOIN, P TI DIRECT SIMULATIONS OF TURBULENT-FLOW USING FINITE-DIFFERENCE SCHEMES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article C1 STANFORD UNIV,STANFORD,CA 94305. RP RAI, MM (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 242 Z9 271 U1 3 U2 19 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 SEP PY 1991 VL 96 IS 1 BP 15 EP 53 PG 39 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA GA366 UT WOS:A1991GA36600002 ER PT J AU PUSEY, ML MUNSON, S AF PUSEY, ML MUNSON, S TI MICRO-APPARATUS FOR RAPID DETERMINATIONS OF PROTEIN SOLUBILITIES SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID LYSOZYME AB We have developed a column-based micro-technique for rapid determination of protein solubilities. While retaining a large crystal surface area, the column dead volume has been reduced to less-than-or-equal-to 5-mu-l. The technique was tested with tetragonal lysozyme (pH 4.5, 0.1M acetate, 3.0% NaCl, 5-25-degrees-C) and column volumes of approximately 60, 300, and 900-mu-l. Identical solubility data were obtained, indicating that equilibration was obtained even in the smallest columns. In addition, solubility data for Br- and I- salts of lysozyme (pH 4.5, 0.1M acetate buffer, 0.5M salt concentrations) were obtained. It appears that the technique can be further miniaturized. The limit in further reducing the crystalline column volume is determined by the minimum solution sample size needed to determine the protein concentration. C1 UNIV WISCONSIN,DEPT BACTERIOL,MADISON,WI 53706. RP PUSEY, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812, USA. NR 11 TC 22 Z9 22 U1 2 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 SEP PY 1991 VL 113 IS 3-4 BP 385 EP 389 DI 10.1016/0022-0248(91)90071-C PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA GM356 UT WOS:A1991GM35600005 ER PT J AU COLONIUS, T LELE, SK MOIN, P AF COLONIUS, T LELE, SK MOIN, P TI THE FREE COMPRESSIBLE VISCOUS VORTEX SO JOURNAL OF FLUID MECHANICS LA English DT Article AB The effects of compressibility on free (unsteady) viscous heat-conducting vortices are investigated. Analytical solutions are found in the limit of large, but finite, Reynolds number, and small, but finite, Mach number. The analysis shows that the spreading of the vortex causes a radial flow. This flow is given by the solution of an ordinary differential equation (valid for any Mach number), which gives the dependence of the radial velocity on the tangential velocity, density, and temperature profiles of the vortex; estimates of the radial velocity found by solving this equation are found to be in good agreement with numerical solutions of the full equations. The experiments of Mandella (1987) also report a radial flow in the vortex, but their estimates are much larger than the analytical predictions, and it is found that the flow inferred from the experiments violates the Second Law of Thermodynamics for two-dimensional axisymmetric flow. It is speculated that three-dimensionality is the cause of this discrepancy. To obtain detailed analytical solutions, the equations for the viscous evolution are expanded in powers of Mach number, M. Solutions valid to O(M2), are discussed for vortices with finite circulation. Two specific initial conditions - vortices with initially uniform entropy and with initially uniform density - are analysed in detail. It is shown that swirling axisymmetric compressible flows generate negative radial velocities far from the vortex core owing to viscous effects, regardless of the initial distributions of vorticity, density and entropy. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP COLONIUS, T (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 22 TC 38 Z9 38 U1 1 U2 5 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 SEP PY 1991 VL 230 BP 45 EP 73 DI 10.1017/S0022112091000708 PG 29 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GH088 UT WOS:A1991GH08800002 ER PT J AU HO, CM ZOHAR, Y FOSS, JK BUELL, JC AF HO, CM ZOHAR, Y FOSS, JK BUELL, JC TI PHASE DECORRELATION OF COHERENT STRUCTURES IN A FREE SHEAR-LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TURBULENT MIXING LAYERS; RATIO AB The vortices near the origin of an initially laminar mixing layer have a single frequency with a well-defined phase; i.e. there is little phase jitter. Further downstream, however, the phase jitter increases suddenly. Even when the flow is forced, this same transition is observed. The forcing partially loses its influence because of the decorrelation of the phase between the forcing signal and the passing coherent structures. In the present investigation, this phenomenon is documented and the physical mechanism responsible for the phase decorrelation is identified. C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. RP HO, CM (reprint author), UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089, USA. RI Ho, Chih-ming/I-6537-2012 NR 28 TC 18 Z9 18 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 SEP PY 1991 VL 230 BP 319 EP 337 DI 10.1017/S0022112091000800 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GH088 UT WOS:A1991GH08800012 ER PT J AU SMITH, CW WONG, HK GOLDSTEIN, ML AF SMITH, CW WONG, HK GOLDSTEIN, ML TI WHISTLER WAVES ASSOCIATED WITH THE URANIAN BOW SHOCK - OUTBOUND OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTRON VELOCITY DISTRIBUTIONS; PROTON-BEAM GENERATION; SOLAR-WIND; EARTHS FORESHOCK; UPSTREAM WAVES; URANUS; VOYAGER-2; COLLISIONLESS; INSTABILITIES; PROPAGATION AB The encounter of the Voyager 2 spacecraft with the Uranian planetary system led to a series of outbound crossings of the Uranian bow shock between January 27 and January 30 of 1986. Examination of magnetic field data recorded in close proximity to the shock reveals a series of whistler wave events that appear to result from processes associated with the shock. Two wave events display two separate and simultaneous wave enhancements each, one at approximately 0.2 Hz and the second more nearly at 1 Hz in the spacecraft reference frame. The actual frequencies of the waves vary with the two events. Both wave enhancements of the two events are right-hand polarized in the spacecraft frame of reference. We have examined these wave events using high-resolution magnetic field data and conclude that they are analogous to those whistler waves upstream of the Earth's bow shock that are driven by beams of electrons. Using observations by the plasma wave science experiment on Voyager 2 to infer the likely presence of electron beams with modest beam speeds, we present an instability analysis and show that a single electron beam with reasonable parameters can generate both of the observed whistler wave forms simultaneously. A third wave event is also seen which occurs both upstream and downstream of a shock crossing. This event displays only one relatively broad spectral enhancement in the same frequency regime and is left-hand polarized in the spacecraft frame. We argue that this event is most likely the result of a gyrating proton distribution associated with the oblique shock. As such, it is analagous to whistler waves observed earlier during the inbound crossing of the Uranian shock. C1 SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78284. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SMITH, CW (reprint author), UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716, USA. RI Goldstein, Melvyn/B-1724-2008 NR 39 TC 11 Z9 11 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1991 VL 96 IS A9 BP 15841 EP 15852 DI 10.1029/91JA01460 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE416 UT WOS:A1991GE41600013 ER PT J AU FLAMMER, KR MENDIS, DA NORTHROP, TG WHIPPLE, EC AF FLAMMER, KR MENDIS, DA NORTHROP, TG WHIPPLE, EC TI A SELF-CONSISTENT MODEL FOR THE PARTICLES AND FIELDS UPSTREAM OF AN OUTGASSING COMET .1. GYROTROPIC AND ISOTROPIC ION DISTRIBUTIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND INTERACTION; PICKED-UP IONS; GIACOBINI-ZINNER; GLOBAL-MODEL; HALLEY; TURBULENCE; SIMULATION AB The magnetic field and solar wind flow parameters in the vicinity of a weakly outgassing comet are determined using a self-consistent model which treats the cometary ions kinetically. Two different assumptions are made concerning the cometary ion distribution function; the pickup cometary ions form either a velocity space gyrotropic ring distribution or a velocity space isotropic shell distribution in the solar wind frame of reference. The individual currents due to the solar wind and cometary ions, which determine the magnetic field, are calculated in each case. Using theoretically determined parameters which reflect the conditions expected at comet Kopff (a typical short-period comet and one possible target for the future CRAF/Cassini mission) for various heliocentric distances, we are able to determine how the global field and flow characteristic are influenced by the nature of the cometary ion distribution function. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. RP FLAMMER, KR (reprint author), UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093, USA. NR 32 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1991 VL 96 IS A9 BP 15907 EP 15916 DI 10.1029/91JA01265 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE416 UT WOS:A1991GE41600019 ER PT J AU ROBERTS, DA AF ROBERTS, DA TI IS THERE A STRANGE ATTRACTOR IN THE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CHAOTIC TIME-SERIES; SMALL DATA SETS; CORRELATION DIMENSION; GEOMAGNETIC-ACTIVITY; DETERMINISTIC CHAOS; FRACTAL DIMENSION; SYSTEMS; INFORMATION; PREDICTION; TURBULENCE AB This paper reviews recent attempts to determine if some aspects of magnetospheric dynamics, and in particular substorms as measured by AE and AL geomagnetic indices, can be represented by a low-dimensional dynamical system. If true, this result would imply that a small set of ordinary differential equations could describe important aspects of substorm dynamics, greatly simplifying modeling and prediction efforts and providing significant input to more detailed modeling. The "embedding" and "correlation dimension" methods used to investigate the dimensionality of a physical process from a single time series are considered in detail with an emphasis on what can go wrong and what can be done about it. Two main conclusions of this work, which includes some new results on the particular case of AL, are (1) that a low-dimensional and probably strange attractor does exist in magnetospheric dynamics, and (2) that there is no reliable substitute for using large numbers of data points in performing analyses leading to this conclusion. RP ROBERTS, DA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 48 TC 35 Z9 35 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1991 VL 96 IS A9 BP 16031 EP 16046 DI 10.1029/91JA01088 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE416 UT WOS:A1991GE41600031 ER PT J AU TISCHLER, MB FLETCHER, JW MORRIS, PM TUCKER, GE AF TISCHLER, MB FLETCHER, JW MORRIS, PM TUCKER, GE TI FLYING QUALITY ANALYSIS AND FLIGHT EVALUATION OF A HIGHLY AUGMENTED COMBAT ROTORCRAFT SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper discusses implications of digital flight control system design for rotocraft and illustrates the analysis of the resulting handling qualities obtained with the Advanced Digital Optical Control System demonstrator in the context of the proposed new handling-qualities specification for rotorcraft. Topics covered are digital flight control design and analysis methods, flight testing techniques, handling-qualities evaluation results, and correlation of flight test results with analytical models and the proposed handling-qualities specification. The evaluation of the demonstrator system indicates desirable response characteristics based on equivalent damping and frequency, but undesirably large effective time delays (exceeding 240 ms in all axes). Piloted handling qualities are found to be desirable or adequate for all low, medium, and high pilot gain tasks, but handling qualities are inadequate for ultrahigh gain tasks such as slope and running landings. Correlation of these results with the proposed handling-qualities specification indicates good agreement for the bandwidth boundaries, but suggests the need for more stringent limits on allowable phase delay. Analytical models based on emulation (s-plane) techniques compare favorably with flight-extracted frequency-domain characteristics of the overall (end-to-end) system responses. RP TISCHLER, MB (reprint author), NASA,AMES RES CTR,FLIGHT OPERAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 19 TC 13 Z9 13 U1 0 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 SEP-OCT PY 1991 VL 14 IS 5 BP 954 EP 963 DI 10.2514/3.20736 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GF532 UT WOS:A1991GF53200012 ER PT J AU WANG, TC DUXBURY, TC SYNNOTT, SP EDWARDS, K AF WANG, TC DUXBURY, TC SYNNOTT, SP EDWARDS, K TI APPROACH FOR TARGETING LANDERS AND PENETRATORS USING ORBITAL OPTICAL NAVIGATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID CONTROL NETWORKS; PLANETS; SATELLITES; PHOBOS AB A new approach for targeting landers, rovers, and penetrators to specific points on the surfaces of planetary bodies using onboard, orbital optical navigation data is presented. Earth-based radiometric tracking of the orbiting spacecraft provides a very precise determination of the spacecraft orbit about the primary planetary body. Onboard optical navigation images are then used to relate the spacecraft orbit to the surface of the target body. This paper concentrates on the problem associated with using the onboard optical navigation data, which will have to estimate, in a near-real time orbit determination process, a large set of parameters including the spacecraft orbit and primary body gravity field, the rotational properties of the planetary body, the coordinates of surface features, and the camera pointing and orientation of each picture. A batch-sequential formulation of the standard least squares problem is used with the addition of backward smoothing. A square-root information filter is also used for numerical precision and stability and to minimize computer memory. To illustrate this approach, over 100 images of Phobos were processed to estimate about 2000 parameters including the camera pointing angles, the rotational properties of Phobos, and the locations of surface features. C1 US GEOL SURVEY,ASTROGEOL BRANCH,FLAGSTAFF,AZ 86001. CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. CALTECH,JET PROP LAB,NAVIGAT SYST SECT,OPT SYST ANAL GRP,PASADENA,CA 91109. RP WANG, TC (reprint author), CALTECH,JET PROP LAB,NAVIGAT SYST SECT,TECH STAFF,MAIL STOP 301-220G,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1991 VL 14 IS 5 BP 973 EP 980 DI 10.2514/3.20738 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GF532 UT WOS:A1991GF53200014 ER PT J AU GILBERT, MG SCHMIDT, DK AF GILBERT, MG SCHMIDT, DK TI INTEGRATED STRUCTURE CONTROL LAW DESIGN BY MULTILEVEL OPTIMIZATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SENSITIVITY AB A new approach to integrated structure/control law design based on multilevel optimization is presented. This new approach is applicable to aircraft and spacecraft and allows for the independent design of the structure and control law. Integration of the designs is achieved through use of an upper level coordination problem formulation within the multilevel optimization framework. The method requires the use of structure and control law design sensitivity information. A general multilevel structure/control law design problem formulation is given, and the use of linear quadratic Gaussian control law design and design sensitivity methods within the formulation is illustrated. Results of three simple integrated structure/control law design examples are presented. These results show the capability of structure and control law design tradeoffs to improve controlled system performance within the multilevel approach. C1 ARIZONA STATE UNIV,DEPT MECH & AEROSP ENGN,TEMPE,AZ 85287. RP GILBERT, MG (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 19 TC 13 Z9 14 U1 1 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 SEP-OCT PY 1991 VL 14 IS 5 BP 1001 EP 1007 DI 10.2514/3.20742 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GF532 UT WOS:A1991GF53200018 ER PT J AU MOOK, DJ LEW, JS AF MOOK, DJ LEW, JS TI EXISTENCE AND UNIQUENESS PROOF FOR THE MINIMUM MODEL ERROR OPTIMAL ESTIMATION ALGORITHM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note ID IDENTIFICATION C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP MOOK, DJ (reprint author), SUNY BUFFALO,DEPT MECH & AEROSP ENGN,CLIFFORD C FURNAS HALL,BUFFALO,NY 14260, USA. NR 15 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1991 VL 14 IS 5 BP 1064 EP 1067 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GF532 UT WOS:A1991GF53200028 ER PT J AU WANG, YJ SHIEH, LS SUNKEL, JW AF WANG, YJ SHIEH, LS SUNKEL, JW TI LINEAR QUADRATIC REGULATOR APPROACH TO THE STABILIZATION OF MATCHED UNCERTAIN LINEAR-SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note ID RICCATI EQUATION APPROACH; CONTROLLERS; STABILITY C1 NASA,JOHNSON SPACE CTR,DIV AVION SYST,HOUSTON,TX 77508. RP WANG, YJ (reprint author), UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1991 VL 14 IS 5 BP 1074 EP 1077 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GF532 UT WOS:A1991GF53200033 ER PT J AU BREININGER, DR SCHMALZER, PA HINKLE, CR AF BREININGER, DR SCHMALZER, PA HINKLE, CR TI ESTIMATING OCCUPANCY OF GOPHER TORTOISE (GOPHERUS-POLYPHEMUS) BURROWS IN COASTAL SCRUB AND SLASH PINE FLATWOODS SO JOURNAL OF HERPETOLOGY LA English DT Article AB One hundred twelve plots were established in coastal scrub and slash pine flatwoods habitats on the John F. Kennedy Space Center (KSC) to evaluate relationships between the number of burrows and gopher tortoise (Gopherus polyphemus) density. All burrows were located within these plots and were classified according to tortoise activity. Depending on season, bucket trapping, a stick method, a gopher tortoise pulling device, and a camera system were used to estimate tortoise occupancy. Correction factors (% of burrows occupied) were calculated by season and habitat type. Our data suggest that < 20% of the active and inactive burrows combined were occupied during seasons when gopher tortoises were active. Correction factors were higher in poorly-drained areas and lower in well-drained areas during the winter, when gopher tortoise activity was low. Correction factors differed from studies elsewhere, indicating that population estimates require correction factors specific to the site and season to accurately estimate population size. RP BREININGER, DR (reprint author), NASA,BIONET CORP,BIOMED OPERAT & RES OFF,MAIL CODE BIO-2,KENNEDY SPACE CTR,FL 32899, USA. NR 20 TC 22 Z9 24 U1 1 U2 13 PU SOC STUD AMPHIBIANS REPTILES PI OXFORD PA DEPT OF ZOOLOGY MIAMI UNIV, OXFORD, OH 45056 SN 0022-1511 J9 J HERPETOL JI J. Herpetol. PD SEP PY 1991 VL 25 IS 3 BP 317 EP 321 DI 10.2307/1564590 PG 5 WC Zoology SC Zoology GA GD953 UT WOS:A1991GD95300009 ER PT J AU GILBERT, JR SCHREIBER, R AF GILBERT, JR SCHREIBER, R TI OPTIMAL EXPRESSION EVALUATION FOR DATA PARALLEL ARCHITECTURES SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article ID TREES C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. RP GILBERT, JR (reprint author), XEROX CORP,PALO ALTO RES CTR,COMP SCI LAB,3333 COYOTE HILL RD,PALO ALTO,CA 94304, USA. NR 14 TC 17 Z9 17 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 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD SEP PY 1991 VL 13 IS 1 BP 58 EP 64 DI 10.1016/0743-7315(91)90109-M PG 7 WC Computer Science, Theory & Methods SC Computer Science GA GD671 UT WOS:A1991GD67100005 ER PT J AU HERGENROTHER, PM BELTZ, MW HAVENS, SJ AF HERGENROTHER, PM BELTZ, MW HAVENS, SJ TI POLYIMIDES CONTAINING CARBONYL AND ETHER CONNECTING GROUPS .3. SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Article AB Several new polyimides were prepared from the reaction of three aromatic dianhydrides with two new methyl substituted aromatic diamines containing carbonyl and ether connecting groups between the aromatic rings. The diamines were prepared from the reactions of 3-methyl-4-aminophenol and 3,5-dimethyl-4-aminophenol with 1,3-bis(4-fluorobenzoyl) benzene in the presence of potassium carbonate. The 300-degrees-C cured polyimides containing methyl substituents were shown to be amorphous by wide angle X-ray diffraction and exhibited glass transition temperatures between 231-281-degrees-C. The properties of these new polyimides containing methyl substituents were compared with polyimides of the same chemical structure but without methyl substituents. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. UNIV AKRON,AKRON,OH 44325. RP HERGENROTHER, PM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 7 TC 18 Z9 18 U1 1 U2 4 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD SEP PY 1991 VL 29 IS 10 BP 1483 EP 1489 DI 10.1002/pola.1991.080291012 PG 7 WC Polymer Science SC Polymer Science GA GB718 UT WOS:A1991GB71800012 ER PT J AU RONCACE, EA AF RONCACE, EA TI LIQUID-OXYGEN COOLING OF HYDROCARBON FUELED ROCKET THRUST CHAMBERS SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 25TH JOINT PROPULSION CONF CY JUL 10-12, 1989 CL MONTEREY, CA SP AMER INST AERONAUT & ASTRONAUT, AMER SOC MECH ENGINEERS, AMER SOC ENGN EDUC, SOC AUTOMOT ENGINEERS AB Rocket engines using liquid oxygen (LOX) and hydrocarbon fuel as the propellants are being given serious consideration for future launch vehicle propulsion. Normally, the fuel is used to regeneratively cool the combustion chamber. However, hydrocarbons such as RP-1 are limited in their cooling capability. Another possibility for the coolant is the liquid oxygen. Combustion chambers previously tested with LOX and RP-1 as propellants and LOX as the coolant have demonstrated the feasibility of using liquid oxygen as a coolant up to a chamber pressure of 13.8 MPa (2000 psia). However, there has been concern as to the effect on the integrity of the chamber liner if oxygen leaks into the combustion zone through fatigue cracks that may develop between the cooling passages and the hot-gas-side wall. In order to study this effect, chambers were fabricated with slots machined upstream of the throat between the cooling passage wall and the hot-gas-side wall to simulate cracks. The chambers were tested at a nominal chamber pressure of 8.6 MPa (1247 psia) over a range of mixture ratios from 1.5 to 3.1 using liquid oxygen as the coolant. The results of the testing showed that the leaking LOX did not have a deleterious effect on the chambers, i.e., there was no evidence of melting in the region of the slots or of the wall reaching its ignition temperature. However, there was melting in the throat region of two chambers but not in line with the slots. The cause of the melting was thoroughly investigated and was determined to be a result of injector anomalies. RP RONCACE, EA (reprint author), NASA,LEWIS RES CTR,LAUNCH VEHICLE TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1991 VL 7 IS 5 BP 717 EP 723 DI 10.2514/3.23384 PG 7 WC Engineering, Aerospace SC Engineering GA GG764 UT WOS:A1991GG76400009 ER PT J AU GRUBER, RP GOTT, RW HAAG, TW AF GRUBER, RP GOTT, RW HAAG, TW TI 5-KILOWATT ARCJET POWER ELECTRONICS SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 25TH JOINT PROPULSION CONF CY JUL 10-12, 1989 CL MONTEREY, CA SP AMER INST AERONAUT & ASTRONAUT, AMER SOC MECH ENGINEERS, AMER SOC ENGN EDUC, SOC AUTOMOT ENGINEERS AB Future, large Earth orbital spacecraft could benefit from arcjet systems in the 2 to 5 kW power range for a variety of applications including stationkeeping, orbit adjustments, and logistics. The arcjet power processor represents the system element with the largest mass and system interfaces with the most impact. Described in this paper is the initial design and evaluation of a 5-kW arcjet power electronics breadboard which has been integrated with a modified 1-kW design laboratory arcjet. A single stage, 5-kW full bridge, pulse width modulated (PWM), power converter was developed which was phase shift regulated. The converter used metal oxide semiconductor field effect transistor (MOSFET) power switches and incorporated current mode control and an integral arcjet pulse ignition circuit. The unoptimized power efficiency was 93.5% and 93.9% at 5 kW and 50 A output at input voltages of 130 and 150 V, respectively. Line and load current regulation at 50 A output was within 1%. The converter provided up to 6.6 kW to the arcjet with simulated ammonia used as a propellant. RP GRUBER, RP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1991 VL 7 IS 5 BP 740 EP 748 DI 10.2514/3.23387 PG 9 WC Engineering, Aerospace SC Engineering GA GG764 UT WOS:A1991GG76400012 ER PT J AU SRIVASTAVA, R SANKAR, LN REDDY, TSR HUFF, DL AF SRIVASTAVA, R SANKAR, LN REDDY, TSR HUFF, DL TI APPLICATION OF AN EFFICIENT HYBRID SCHEME FOR AEROELASTIC ANALYSIS OF ADVANCED PROPELLERS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB An efficient three-dimensional hybrid scheme is applied for solving Euler equations to analyze advanced propellers. The scheme treats the spanwise direction semiexplicitly and the other two directions implicitly, without affecting the accuracy, as compared to a fully implicit scheme. This leads to a reduction in computer time and memory requirement. The calculated power coefficients for two advanced propellers, SR3 and SR7L, at various advance ratios showed good correlation with experiment. Spanwise distribution of elemental power coefficient and steady pressure coefficient differences also showed good agreement with experiment. A study of the effect of structural flexibility on the performance of the advanced propellers showed that structural deformation due to centrifugal and aeroloading should be included for better correlation. The study also showed that adjustments to the setting angle by rigid-body rotation does not simulate the correct blade shape. C1 GEORGIA INST TECHNOL,ATLANTA,GA 30332. UNIV TOLEDO,TOLEDO,OH 43606. RP SRIVASTAVA, R (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 26 TC 9 Z9 11 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 SEP-OCT PY 1991 VL 7 IS 5 BP 767 EP 775 DI 10.2514/3.23390 PG 9 WC Engineering, Aerospace SC Engineering GA GG764 UT WOS:A1991GG76400015 ER PT J AU MYNENI, RB GANAPOL, BD AF MYNENI, RB GANAPOL, BD TI A SIMPLIFIED FORMULATION OF PHOTON TRANSPORT IN LEAF CANOPIES WITH SCATTERERS OF FINITE DIMENSIONS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB A formalism for photon transport in leaf canopies with finite-dimensional scattering centers that mutually cross-shade was recently proposed resulting in an equation set which is rather complicated. In this paper, we propose a simplification of the correction factors that describe the correlation in photon fates. These simplified correction factors permit the derivation of a modified integro-differential transfer equation with two additional terms that arise from considerations of finite size scatteres. A numerical procedure for the solution of this transfer equation in the framework of a successive collisions approach is also presented. C1 UNIV ARIZONA,DEPT NUCL & ENERGY ENGN,TUCSON,AZ 85721. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,MAIL CODE 974,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 8 TC 4 Z9 4 U1 0 U2 1 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 SEP PY 1991 VL 46 IS 3 BP 135 EP 140 DI 10.1016/0022-4073(91)90017-K PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA GF531 UT WOS:A1991GF53100002 ER PT J AU BOWLES, DE GRIFFIN, OH AF BOWLES, DE GRIFFIN, OH TI MICROMECHANICS ANALYSIS OF SPACE SIMULATED THERMAL-STRESSES IN COMPOSITES .1. THEORY AND UNIDIRECTIONAL LAMINATES SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB A micromechanics approach was utilized to investigate the thermally induced stress fields developed in the fiber and matrix of continuous fiber reinforced polymer matrix composites at cold temperatures typical of spacecraft operating temperatures. Results from a finite element stress analysis of a periodic array of fibers were compared to the closed-form solution of the composite cylinder model for several fiber/matrix materials. The influence of microstructural geometry, constituent properties, and fiber volume fraction were investigated. The results of this investigation showed that the assumed microstructural geometry of the composite (i.e., composite cylinder, square or hexagonal array) did affect the distributions and magnitudes of thermally induced stresses. The matrix stresses were shown not to be strong functions of the fiber properties. Matrix stresses increased in absolute value with increasing fiber volume fraction, V(f). A global/local analysis was used to approximate the stresses in localized regions of high V(f), constrained by a lower global V(f). RP BOWLES, DE (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 191,HAMPTON,VA 23665, USA. NR 0 TC 8 Z9 8 U1 0 U2 1 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0731-6844 J9 J REINF PLAST COMP JI J. Reinf. Plast. Compos. PD SEP PY 1991 VL 10 IS 5 BP 504 EP 521 DI 10.1177/073168449101000506 PG 18 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA GH308 UT WOS:A1991GH30800006 ER PT J AU BOWLES, DE GRIFFIN, OH AF BOWLES, DE GRIFFIN, OH TI MICROMECHANICS ANALYSIS OF SPACE SIMULATED THERMAL-STRESSES IN COMPOSITES .2. MULTIDIRECTIONAL LAMINATES AND FAILURE PREDICTIONS SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB A finite element micromechanics approach was used to predict thermally induced stresses in fiber reinforced polymer matrix composites at temperatures typical of spacecraft operating environments. The influence of laminate orientation was investigated with a simple global/local formulation. Thermal stress calculations were used to predict probable damage initiation locations, and the results were compared to experimentally observed damage in several epoxy matrix composites. Multidirectional [0(2)/ +/- theta]s laminates had larger predicted matrix stresses than unidirectional [0] laminates. The stresses increased with increasing lamination angle-theta, and resulted in large tensile radial stresses at the fiber/matrix interface, that were not present in unidirectional laminates. Thermally induced matrix failure predictions, using a failure criterion based on the maximum radial interfacial stress and the ultimate radial interfacial strength, were in excellent agreement with experimental data. This criterion was able to accurately account for the influence of both laminate configuration and constituent properties. Predictions based on the bulk matrix tensile strength or on lamina stresses (computed from laminated plate theory) and strengths were in poor agreement with experimental data. RP BOWLES, DE (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 6 Z9 7 U1 0 U2 0 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0731-6844 J9 J REINF PLAST COMP JI J. Reinf. Plast. Compos. PD SEP PY 1991 VL 10 IS 5 BP 522 EP 539 DI 10.1177/073168449101000507 PG 18 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA GH308 UT WOS:A1991GH30800007 ER PT J AU MCKINLEY, EL AF MCKINLEY, EL TI MARS OBSERVER PROJECT - AN INTRODUCTION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Editorial Material RP MCKINLEY, EL (reprint author), CALTECH,JET PROP LAB,MARS OBSERVER PROJECT,PASADENA,CA 91109, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 489 EP 490 DI 10.2514/3.55627 PG 2 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900001 ER PT J AU ALBEE, AL PALLUCONI, FD AF ALBEE, AL PALLUCONI, FD TI MARS OBSERVER - THE NEXT MARS MISSION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The next mission to Mars, called Mars Observer, will be launched in September 1992. After the capture of the spacecraft by the planet and (he adjustment into a low, Sun-synchronous, polar-mapping orbit in late 1993, observations will continue for a Mars year (687 days). The scientific mission centers around global geoscience and climatology observations of the Mars atmosphere, surface, and interior. The seven experiments carried by the spacecraft involve gamma-ray spectroscopy, magnetometry, surface and atmospheric imaging, atmospheric sounding, laser altimetry, gravity mapping, and thermal emission spectroscopy. All experiments contain micro-processors, which will be controlled remotely from the investigator's home institution. The long planned period of continuous 24 h/day observation promises a rich harvest of global and seasonal information. Mars Observer stands between the initial exploration of Mars and the more intensive explorations, possibly involving human beings, that are only now being planned. C1 CALTECH,JET PROP LAB,MARS OBSERVER PROJECT,PASADENA,CA 91109. RP ALBEE, AL (reprint author), CALTECH,MARS OBSERVER PROJECT,PASADENA,CA 91125, USA. NR 0 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 498 EP 500 DI 10.2514/3.26272 PG 3 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900003 ER PT J AU POTTS, DL AF POTTS, DL TI MARS OBSERVER SPACECRAFT DESCRIPTION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars Observer spacecraft implements the science and mission objectives for a planetary observer program with a design baseline evolving from existing, proven, flight subsystem designs and production techniques. The spacecraft conforms to a set of high-level functional requirements, allowing a development process with a high degree of flexibility in meeting performance, mission, and science requirements. The intent of the implementation approach is to procure a design-to-cost, reliable, production-type spacecraft that can accommodate the complement of science instruments and meet mission requirements with adequate margins. RP POTTS, DL (reprint author), CALTECH,JET PROP LAB,MARS OBSERVER PROJECT,MS 264-627,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 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 SEP-OCT PY 1991 VL 28 IS 5 BP 507 EP 514 DI 10.2514/3.26274 PG 8 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900005 ER PT J AU BEERER, JG RONCOLI, RB AF BEERER, JG RONCOLI, RB TI MARS OBSERVER TRAJECTORY AND ORBIT DESIGN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars Observer launch, interplanetary, Mars orbit insertion, and mapping orbit designs are described. The design objective is to enable a near-maximum spacecraft mass to be placed in orbit about Mars. This is accomplished by keeping spacecraft propellant requirements to a minimum, selecting a minimum acceptable launch period, equalizing the spacecraft velocity change requirement at the beginning and end of the launch period, and constraining the orbit insertion maneuvers to be coplanar. The mapping orbit design objective is to provide the opportunity for global observation of the planet by the science instruments while facilitating the spacecraft design. This is realized with a Sun-synchronous near-polar orbit whose ground-track pattern covers the planet at progressively finer resolution. RP BEERER, JG (reprint author), CALTECH,JET PROP LAB,MISSION DESIGN SECT,TECH STAFF,PASADENA,CA 91109, USA. NR 2 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 515 EP 521 DI 10.2514/3.26275 PG 7 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900006 ER PT J AU BLUME, WH DODD, SR WHETSEL, CW AF BLUME, WH DODD, SR WHETSEL, CW TI MARS OBSERVER MISSION PLAN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Plans are described for operating the Mars Observer mission. These have been developed to help reverse the trend toward increasing complexity in operating interplanetary spacecraft. The normal data return strategy uses continuously recorded data with a single daily playback through the Deep Space Network. Although the mission has been planned with constrained data return strategies and modest data rates, it will still provide, both in temporal and spatial coverage and resolution, the most comprehensive study of an extraterrestrial planet to date. RP BLUME, WH (reprint author), CALTECH,JET PROP LAB,DIV SYST,MISSION DESIGN SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 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 SEP-OCT PY 1991 VL 28 IS 5 BP 522 EP 529 DI 10.2514/3.26276 PG 8 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900007 ER PT J AU ESPOSITO, P ROTH, D DEMCAK, S AF ESPOSITO, P ROTH, D DEMCAK, S TI MARS OBSERVER ORBIT DETERMINATION ANALYSIS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID MODEL AB Orbital accuracies throughout the Mars Observer mission are summarized and a plan is developed for achieving navigation objectives. These objectives are 1) to navigate the Mars Observer spacecraft to Mars and achieve accurate targeting at Mars, 2) to propulsively maneuver the spacecraft into a three-day period, capture orbit, 3) to navigate the spacecraft into a short-period (1.96 h), low-altitude, nearly circular mapping orbit, and 4) to maintain Mars Observer in the mapping orbit throughout 687 days devoted to scientific data acquisition. During the orbital phase, gravity field and atmospheric drag perturbations will control the spacecraft's orbital evolution. They are also the major factors influencing the accuracy of the prediction and reconstruction of the spacecraft' s orbital motion. Initially, the current best estimate of the Mars gravitational field model will be used during flight operations. However, this will be superseded by a 20th degree and order model developed by the navigation team early in the mapping phase. With this implementation, spacecraft reconstructed position errors will be improved significantly. In addition, estimates of the average atmospheric density (over four to five orbits) will be possible throughout Mars' perihelion. C1 OAO CORP,ALTADENA,CA 91001. RP ESPOSITO, P (reprint author), CALTECH,JET PROP LAB,NAVIGAT SYST SECT,TECH STAFF,PASADENA,CA 91109, USA. NR 9 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 SEP-OCT PY 1991 VL 28 IS 5 BP 530 EP 535 DI 10.2514/3.26277 PG 6 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900008 ER PT J AU HALSELL, CA BOLLMAN, WE AF HALSELL, CA BOLLMAN, WE TI MARS OBSERVER TRAJECTORY AND ORBIT CONTROL SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars Observer mission will study Mars from a low-altitude orbit. During interplanetary cruise, propulsive maneuvers are required to ensure capture, with a secondary constraint to satisfy limits on the probability of impact with Mars. After capture, the spacecraft will be brought to a near-circular mapping orbit through a series of maneuvers. Mapping orbit maneuvers will be performed in order to follow a predetermined set of ground tracks and to maintain orbit altitude. This will allow accurate spacecraft command sequence generation and aid science planning throughout the mapping phase. Specific orbit control plans for the open and close of the launch period have been developed to meet these needs. This paper describes the control capabilities and the associated expected velocity changes for the mission. RP HALSELL, CA (reprint author), CALTECH,JET PROP LAB,NAVIGAT SYST SECT,TECH STAFF,PASADENA,CA 91109, USA. NR 8 TC 2 Z9 2 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 SEP-OCT PY 1991 VL 28 IS 5 BP 536 EP 541 DI 10.2514/3.26278 PG 6 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900009 ER PT J AU ERICKSON, KD MCKINLEY, EL AF ERICKSON, KD MCKINLEY, EL TI MARS OBSERVER MISSION OPERATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Mars Observer, planned for a launch in September 1992, will be the first deep space planetary mission to fully utilize a distributed operations concept for science planning, instrument control, and data distribution. In addition, several other concepts in the area of data handling and operations proposed by the Mission Operations and Information Systems Subcommittee of the Solar System Exploration Committee have been adopted for the purpose of improving the efficiency and reducing the costs of deep space mission operations. At the completion of its 687-day prime mission, Mars Observer will have produced and deposited a terabyte of information on its project data base. RP ERICKSON, KD (reprint author), CALTECH,JET PROP LAB,MARS OBSERVER PROJECT,SECT 317,PASADENA,CA 91109, USA. NR 10 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 SEP-OCT PY 1991 VL 28 IS 5 BP 542 EP 551 DI 10.2514/3.26279 PG 10 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900010 ER PT J AU MITCHELTREE, RA GNOFFO, PA AF MITCHELTREE, RA GNOFFO, PA TI THERMOCHEMICAL NONEQUILIBRIUM ISSUES FOR EARTH REENTRY OF MARS MISSION VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The thermochemical environment about an axisymmetric 60-deg sphere cone with a circular aft skirt is computed using the NASA Langley Aerothermodynamic Upwind Relaxation Algorithm. Earth entry at 12 km/s is examined at 70- and 80-km altitude for two vehicle base radii of 2 and 6 m. These four test cases bracket some proposed scenarios for Earth re-entry of a manned Mars mission aerobrake at this velocity. Thermochemical nonequilibrium results are examined for each case and compared with thermal equilibrium results produced by artificially accelerating vibrational relaxation rates and with equilibrium results produced by a viscous shock layer method. The thermal and chemical nonequilibrium effects present in the four cases range from minimal in the largest body at 70-km altitude to dominant in the smaller body at 80-km altitude. RP MITCHELTREE, RA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 15 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 552 EP 559 DI 10.2514/3.26280 PG 8 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900011 ER PT J AU LEPSCH, RA STANLEY, DO CRUZ, CI MORRIS, SJ AF LEPSCH, RA STANLEY, DO CRUZ, CI MORRIS, SJ TI UTILIZING AIR-TURBOROCKET AND ROCKET PROPULSION FOR A SINGLE-STAGE-TO-ORBIT VEHICLE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A horizontal-takeoff, single-stage-to-orbit launch vehicle was designed that utilized a combination of air-turborocket and rocket propulsion systems. Weight reductions were taken on vehicle systems to simulate an advanced technology level. Both air-turborocket and rocket thrust were varied to optimize vehicle weight. For the reference vehicle, weight, propulsion, geometry, and performance characteristics are summarized. A detailed ascent trajectory analysis including trim of the reference vehicle was conducted. Finally, the sensitivity of vehicle weight-to-weight reduction assumptions is presented. C1 NASA,LANGLEY RES CTR,DIV ADV VEHICLES,HAMPTON,VA 23665. RP LEPSCH, RA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 16 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 560 EP 566 DI 10.2514/3.26281 PG 7 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900012 ER PT J AU NAFTEL, JC POWELL, RW AF NAFTEL, JC POWELL, RW TI GUIDANCE SCHEME FOR A MACH-3 STAGED GLIDING BOOSTER SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB One of the promising launch concepts that could replace the current Space Shuttle launch system is a two-stage, winged, vertical-takeoff, parallel-burn, fully reusable launch vehicle comprised of a manned orbiter and an unmanned booster. During the boost phase of ascent, the booster provides propellant for the orbiter engines through a cross-feed system. When the vehicle reaches Mach 3, the booster propellants are depleted and the booster is staged and glides to a horizontal landing al a launch site runway. One of the major design issues for this class of vehicle is the unpowered glide back of the booster after the staging maneuver is completed. A guidance algorithm was developed for the glide-back maneuver and verified using a three-degree-of-freedom trajectory simulation that included static trim in pitch. The guidance algorithm was tested using off-nominal atmospheric, staging, and booster aerodynamic characteristics. RP NAFTEL, JC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 11 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1991 VL 28 IS 5 BP 567 EP 573 DI 10.2514/3.26282 PG 7 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900013 ER PT J AU VAUGHAN, DA SCHMIDT, GR AF VAUGHAN, DA SCHMIDT, GR TI ANALYTICAL MODELING OF NO-VENT FILL PROCESS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper describes a finite difference computer model that predicts no-vent fill performance in a 1-g environment. Derived from the Shuttle External Tank pressurization code, the model accounts for several major effects that influence the process, such as tank and fluid inlet temperature, interfacial mass transfer, and inlet jet characteristics. The paper also explains how ground test data with Freon-114 were used to validate the model's accuracy and to compare, over a restricted range of inflow regimes (0.1 < z/D < 2.0), experimentally measured condensation rates with predictions from universal submerged jet theory. C1 MARTIN MARIETTA CORP,MANNED SPACE SYST,HUNTSVILLE,AL 35812. RP VAUGHAN, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BLDG 4666,HUNTSVILLE,AL 35812, USA. NR 9 TC 12 Z9 12 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 SEP-OCT PY 1991 VL 28 IS 5 BP 574 EP 579 DI 10.2514/3.26283 PG 6 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900014 ER PT J AU EUGENE, LP FERNANDES, PJ JAMALI, MM KWATRA, SC BUDINGER, J AF EUGENE, LP FERNANDES, PJ JAMALI, MM KWATRA, SC BUDINGER, J TI MULTICARRIER DEMODULATOR ARCHITECTURE FOR ONBOARD PROCESSING SATELLITES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A parallel pipelined architecture is presented for demultiplexing and demodulating single channel per carrier/frequency division multiple access (SCPC/FDMA) channels in real time. Specific algorithms are selected for each of the operations necessary for multicarrier demodulation. The selection is made based on their suitability for implementation into parallel-pipelined and sharing schemes. The algorithms are analyzed for data dependencies and divided into data dependent and independent sections. The segregated sections are mapped by implementing the independent sections in a parallel scheme and the dependent sections in a pipelined scheme. The demultiplexing is performed by the polyphase fast Fourier transform (FFT) method, which requires a bank of filters followed by an FFT operation. A shared filter bank module and a pipelined FFT module are designed to implement the bank of filters and the FFT operation, respectively. The demodulator uses a single hardware module that is shared amongst all of the channels for the recovery of timing, carrier, and data. This sharing of hardware to perform the demultiplexing and demodulating of all of the channels results in savings of power and hardware. The system is suitable for onboard processing of signals in satellites where power and ares requirements are critical. The architecture is also highly modular and therefore lends itself well to very large scale integration (VLSI) implementation. This design is illustrated for the specific case of processing 800 FDMA channels at 64 kbps each. C1 NASA,LEWIS RES CTR,DIV SPACE ELECTR,DIGITAL SYST TECHNOL BRANCH,CLEVELAND,OH 44135. RP EUGENE, LP (reprint author), UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606, USA. NR 19 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 SEP-OCT PY 1991 VL 28 IS 5 BP 580 EP 586 DI 10.2514/3.27582 PG 7 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900015 ER PT J AU FEREBEE, MJ ALLEN, CL AF FEREBEE, MJ ALLEN, CL TI OPTIMIZATION OF PAYLOAD PLACEMENT ON ARBITRARY SPACECRAFT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 NASA,LANGLEY RES CTR,COMP SYST OFF,SPACE STN FREEDOM OFF,HAMPTON,VA 23665. RP FEREBEE, MJ (reprint author), NASA,LANGLEY RES CTR,SYST ENGN & ANAL OFF,SPACE STN FREEDOM OFF,MAIL STOP 288,HAMPTON,VA 23665, USA. NR 4 TC 10 Z9 12 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 SEP-OCT PY 1991 VL 28 IS 5 BP 612 EP 614 DI 10.2514/3.26288 PG 3 WC Engineering, Aerospace SC Engineering GA GM559 UT WOS:A1991GM55900020 ER PT J AU BISWAS, A LEUNG, EW TRINH, EH AF BISWAS, A LEUNG, EW TRINH, EH TI ROTATION OF ULTRASONICALLY LEVITATED GLYCEROL DROPS SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article AB Ultrasonic levitation is used to suspend single millimeter-size glycerol drops in a rectangular chamber. Audio-frequency laterally standing waves set up in the chamber are used to torque the suspended drops. The shape evolution of the drop under the combined effect of centrifugal forces and the acoustic radiation stress, along with its angular velocity are monitored, using video imaging and light scattering techniques. The results show good qualitative agreement with the theoretically predicted shape evolution as a function of angular velocity. RP BISWAS, A (reprint author), CALTECH,JET PROP LAB,MS 183-401,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 20 Z9 20 U1 1 U2 7 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD SEP PY 1991 VL 90 IS 3 BP 1502 EP 1507 DI 10.1121/1.401889 PG 6 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA GE466 UT WOS:A1991GE46600032 ER PT J AU RIGNOT, E CHELLAPPA, R AF RIGNOT, E CHELLAPPA, R TI SEGMENTATION OF SYNTHETIC-APERTURE-RADAR COMPLEX DATA SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID IMAGES; MODEL; SIMULATION; CLUTTER; NOISE AB Several algorithms used for segmenting highly speckled high-resolution synthetic-aperture-radar (SAR) complex data into spatially and radiometrically homogeneous regions are presented. The procedure is based on two models, one for the speckled complex amplitudes and the other for the regions. The first model uses the physics of the SAR imaging and processing system to characterize the statistics of speckle, while the second model uses a Markov random field to describe the statistics of the regions. Based on the combination of these two models from Bayes theory, two possible optimality criteria are considered for the segmentation of the complex data into regions. The different algorithms are implemented on a parallel optimization network. Results from both simulated and actual SAR complex data are presented for a comparison of the different alternatives and evaluation of the performance of the segmentation techniques. C1 UNIV SO CALIF,INST SIGNAL & IMAGE PROC,LOS ANGELES,CA 90089. RP RIGNOT, E (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 32 TC 19 Z9 20 U1 0 U2 1 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 SEP PY 1991 VL 8 IS 9 BP 1499 EP 1509 DI 10.1364/JOSAA.8.001499 PG 11 WC Optics SC Optics GA GC968 UT WOS:A1991GC96800019 ER PT J AU CHERN, EJ AF CHERN, EJ TI CONCEPT OF NONDESTRUCTIVE EVALUATION SO MATERIALS EVALUATION LA English DT Article RP CHERN, EJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 3134,GREENBELT,MD 20771, USA. NR 0 TC 2 Z9 2 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 SEP PY 1991 VL 49 IS 9 BP 1228 EP & PG 0 WC Materials Science, Characterization & Testing SC Materials Science GA GF150 UT WOS:A1991GF15000019 ER PT J AU WHITAKER, AF AF WHITAKER, AF TI COATINGS COULD PROTECT COMPOSITES FROM HOSTILE SPACE ENVIRONMENT (REPRINTED FROM ADVANCED MATERIALS AND PROCESSES, APRIL, 1991) SO MATERIALS PERFORMANCE LA English DT Reprint AB Preliminary results from the low-Earth orbit exposure of coating materials on NASA's long-duration exposure facility (LDEF) are presented. Results show that many structural materials will require protection from coatings to resist the aggressive aspects of prolonged space flight. RP WHITAKER, AF (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAT & PROC LAB,CODE EH11,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NATL ASSN CORROSION ENG PI HOUSTON PA 1440 SOUTH CREEK DRIVE, HOUSTON, TX 77084-4906 SN 0094-1492 J9 MATER PERFORMANCE JI Mater. Perform. PD SEP PY 1991 VL 30 IS 9 BP 48 EP 50 PG 3 WC Materials Science, Characterization & Testing SC Materials Science GA GH641 UT WOS:A1991GH64100010 ER PT J AU LEE, RB BARKSTROM, BR AF LEE, RB BARKSTROM, BR TI CHARACTERIZATION OF THE EARTH RADIATION BUDGET EXPERIMENT RADIOMETERS SO METROLOGIA LA English DT Article; Proceedings Paper CT 3RD MEETING ON NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY CY SEP 20-22, 1990 CL DAVOS, SWITZERLAND SP PHYSIKALISCH METEOROLOG OBSERV DAVOS ID INSTRUMENT AB The Earth Radiation Budget Experiment (ERBE) scanning radiometers were used to measure the Earth's radiation fields during the period November 1984 through February 1990. The ERBE radiometric packages were placed into orbit aboard the Earth Radiation Budget Satellite (ERBS) and the National Oceanic and Atmospheric Administration NOAA-9 and NOAA-10 spacecraft platforms. In each radiometric package, thermistor bolometers were used as detection elements for the broadband total (0,2 - 50,0-mu-m), shortwave (0,2 - 5,0-mu-m), and longwave (5,0 - 50,0-mu-m) spectral regions. Flight calibration facilities were built into each of the spacecraft radiometric packages. The flight facilities consisted of black bodies, tungsten lamps, and silicon photodiodes. The black bodies and tungsten lamps were found to be reliable at precision levels approaching 0,5 % over a five-year period. The photodiodes were found to degrade more than 2 % during the first year in orbit. In this paper, the flight calibration systems for the ERBE scanning radiometers are described along with the resultant measurements. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. NR 11 TC 8 Z9 8 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD SEP PY 1991 VL 28 IS 3 BP 183 EP 187 DI 10.1088/0026-1394/28/3/015 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JB184 UT WOS:A1991JB18400016 ER PT J AU GUENTHER, B MCLEAN, J COOPER, J AF GUENTHER, B MCLEAN, J COOPER, J TI ACCURACY AND PRECISION ACTUALLY ACHIEVED FOR LARGE-APERTURE INTEGRATOR SOURCES FOR AIRCRAFT AND SPACE INVESTIGATIONS SO METROLOGIA LA English DT Article; Proceedings Paper CT 3RD MEETING ON NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY CY SEP 20-22, 1990 CL DAVOS, SWITZERLAND SP PHYSIKALISCH METEOROLOG OBSERV DAVOS AB Large-aperture integrator sources are required to calibrate a number of the satellite instruments which will be used for documenting and understanding global change in the US Earth Observing System (EOS) satellite program. In this paper the salient characteristics of large-aperture sources as used at the NASA/Goddard Space Flight Center are identified. These characteristics are source spatial uniformity, calibration accuracy and output stability. One use of these sources in maintaining the satellite sensor performance in orbit through vicarious calibrations is reviewed. A transportable hemispherical source is shown to have spatial uniformity of better than 0,3 %, have stability of near 1 %, and to be capable of being calibrated with an uncertainty near 1,6 %. Vicarious calibrations of the AVHRR with a transfer spectrometer on board a NASA ER-2 platform flown at 21 km are shown to be capable of individual calibrations with an uncertainty of 3,5 %. Annual trends in the satellite responsivity can be corrected to an uncertainty of 1,5 % with this approach. C1 NASA,GODDARD SPACE FLIGHT CTR,STAND & CALIBRAT OFF,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,GREENBELT,MD 20771. NR 8 TC 0 Z9 0 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD SEP PY 1991 VL 28 IS 3 BP 229 EP 232 DI 10.1088/0026-1394/28/3/024 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JB184 UT WOS:A1991JB18400025 ER PT J AU LEE, RB GIBSON, MA SHIVAKUMAR, N WILSON, R KYLE, HL MECHERIKUNNEL, AT AF LEE, RB GIBSON, MA SHIVAKUMAR, N WILSON, R KYLE, HL MECHERIKUNNEL, AT TI SOLAR IRRADIANCE MEASUREMENTS - MINIMUM THROUGH MAXIMUM SOLAR-ACTIVITY SO METROLOGIA LA English DT Article; Proceedings Paper CT 3RD MEETING ON NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY CY SEP 20-22, 1990 CL DAVOS, SWITZERLAND SP PHYSIKALISCH METEOROLOG OBSERV DAVOS ID MODEL AB The Earth Radiation Budget Satellite (ERBS) and the NOAA-9 spacecraft solar monitors were used to measure the total solar irradiance during the period October 1984 to December 1989. Decreasing trends in the irradiance measurements were observed as sunspot activity decreased to minimum levels in 1986; after 1986, increasing trends were observed as sunspot activity increased. The magnitude of the irradiance variability was found to be approximately 0,1 % between sunspot minimum and maximum (late 1989). When compared with the 1984 to 1989 indices of solar magnetic activity, the irradiance trends appear to be in phase with the 11-year sunspot cycle. Both irradiance series yielded 1 365 Wm-2 as the mean value of the solar irradiance, normalized to the mean Earth/Sun distance. The monitors are electrical substitution, active-cavity radiometers with estimated measurement precisions and accuracies of less than 0,02 % and 0,2 %, respectively. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. ST SYST CORP,HAMPTON,VA 23666. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 16 TC 15 Z9 15 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD SEP PY 1991 VL 28 IS 3 BP 265 EP 268 DI 10.1088/0026-1394/28/3/032 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JB184 UT WOS:A1991JB18400033 ER PT J AU HICKEY, JR FRIEDEN, RG BRINKER, DJ AF HICKEY, JR FRIEDEN, RG BRINKER, DJ TI REPORT ON AN H-F TYPE CAVITY RADIOMETER AFTER 6 YEARS EXPOSURE IN SPACE ABOARD THE LDEF SATELLITE SO METROLOGIA LA English DT Article; Proceedings Paper CT 3RD MEETING ON NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY CY SEP 20-22, 1990 CL DAVOS, SWITZERLAND SP PHYSIKALISCH METEOROLOG OBSERV DAVOS AB A cavity radiometer for the H-F type was included as the total irradiance monitor of the Advanced Photovoltaic Experiment (APEX) aboard the Long Duration Exposure Facility (LDEF) satellite. This is the same type of cavity radiometer which has returned data from Nimbus-7 for almost twelve years. The LDEF was retrieved by the Space Shuttle Columbia on 12 January 1990 after almost six years in space. Initial results show that the electrical properties of the thermopile and heater circuits were unaffected. There was a slight visible change to the painted surface of the cavity, possibly caused by atomic oxygen impingement late in the mission. This apparently has not affected the agreement with ground-based reference standards. Intercomparisons to date indicate agreement of approximately 0,1 %, but with an uncertainty at this same 0,1 % level. The radiometer was included in the International Pyrheliometric Comparison (IPC VII) in September 1990. In-flight data was taken by an on-board data system (no telemetry) for the period from 7 April 1984 to 16 March 1985. Digital flight data from which solar pointing and irradiance information can be calculated has recently become available. C1 EPPLEY LAB INC,NEWPORT,RI 02840. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 6 TC 1 Z9 1 U1 1 U2 2 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD SEP PY 1991 VL 28 IS 3 BP 269 EP 273 DI 10.1088/0026-1394/28/3/033 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JB184 UT WOS:A1991JB18400034 ER PT J AU HILSENRATH, E CEBULA, RP CAFFREY, R HYNES, S AF HILSENRATH, E CEBULA, RP CAFFREY, R HYNES, S TI IMPLICATIONS OF SPACE-SHUTTLE FLIGHT ON THE CALIBRATION OF INSTRUMENTS OBSERVING ATMOSPHERIC OZONE AND THE SOLAR IRRADIANCE SO METROLOGIA LA English DT Article; Proceedings Paper CT 3RD MEETING ON NEW DEVELOPMENTS AND APPLICATIONS IN OPTICAL RADIOMETRY CY SEP 20-22, 1990 CL DAVOS, SWITZERLAND SP PHYSIKALISCH METEOROLOG OBSERV DAVOS AB Accurate calibration of remote-sensing instruments has become increasingly more important for studying long-term changes in our environment. Changes in atmospheric ozone are of great concern and have been observed from satellites for over a decade. Despite this record, long-term trends in ozone remain uncertain, primarily due to uncertainties in satellite instrument calibration after launch. In order to overcome this problem a Shuttle-borne Solar Backscatter Ultraviolet (SSBUV) radiometer is being flown almost yearly in conjunction with the series of SBUV-type ozone sounders that are being flown on NASA research and NOAA operational satellites. The SSBUV calibration must be tracked to 1 % or better to provide the requisite calibration transfer so that an ozone trend can be derived from the satellite data set. The first flight of the SSBUV occurred in October 1989. Calibration of the instrument was tracked before and after flight to a precision of 1 % through laboratory calibrations, field calibration checks, and in-flight calibration checks. As a result of the flight, the instrument experienced a 1 % to 2 % change in sensitivity in the wavelengths used for measuring ozone. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ST SYST CORP,LANHAM,MD 20706. INT DEV & ENERGY ASSOC INC,LAUREL,MD 20707. NR 9 TC 13 Z9 13 U1 0 U2 0 PU BUREAU INT POIDS MESURES PI SEVRES CEDEX PA B1 PM PAVILLION DE BRETUEIL, F-92312 SEVRES CEDEX, FRANCE SN 0026-1394 J9 METROLOGIA JI Metrologia PD SEP PY 1991 VL 28 IS 3 BP 301 EP 304 DI 10.1088/0026-1394/28/3/039 PG 4 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA JB184 UT WOS:A1991JB18400040 ER PT J AU WHITE, DA FABIAN, AC JOHNSTONE, RM MUSHOTZKY, RF ARNAUD, KA AF WHITE, DA FABIAN, AC JOHNSTONE, RM MUSHOTZKY, RF ARNAUD, KA TI THE DISCOVERY OF LARGE AMOUNTS OF COLD, X-RAY ABSORBING MATTER IN COOLING FLOWS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID SOLID-STATE SPECTROMETER; PERSEUS CLUSTER; INFRARED-EMISSION; HOT PLASMA; H-I; GALAXIES; EINSTEIN; GAS; ABSORPTION; LINE AB We report the discovery of significant excess absorption in the X-ray spectra of 12 clusters of galaxies. The spectra, from the Einstein Observatory Solid State Spectrometer, also require a cooling-flow component, which confirms the results of imaging studies of the clusters showing the strongly peaked emission characteristic of cooling flows. Several other clusters, such as the Coma cluster, do not require either extra absorption of a cooling flow component. The total mass of absorbing gas is approximately 3 x 10(11)-10(12) M., on the assumption that it is distributed through the cooling flow region and has cosmic abundance. It represents a significant new component of the intracluster medium. We show that the gas is most likely in the form of small cold clouds. It may be difficult to detect at other wavelengths, although further studies of the 21-cm line of hydrogen should be most successful. The absorbing gas should be readily observable in spectra from the X-ray detectors on BBXRT and ROSAT. C1 UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WHITE, DA (reprint author), UNIV CAMBRIDGE,INST ASTRON,MADINGLEY RD,CAMBRIDGE CB3 0HA,ENGLAND. NR 55 TC 188 Z9 188 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD SEP 1 PY 1991 VL 252 IS 1 BP 72 EP 81 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GE368 UT WOS:A1991GE36800010 ER PT J AU SHARMA, AK CHANG, ATC WILHEIT, TT AF SHARMA, AK CHANG, ATC WILHEIT, TT TI ESTIMATION OF THE DIURNAL CYCLE OF OCEANIC PRECIPITATION FROM SSM/I DATA SO MONTHLY WEATHER REVIEW LA English DT Article ID RAINFALL AB A study of differences between the morning and evening monthly rainfall for 5-degrees x 5-degrees cells over the oceans from the SSM/I data has been conducted. The monthly rainfalls are estimated from the technique given by Wilheit et al. The difference between the morning and evening monthly rainfall arises due to the various random errors involved in the retrieval process, the sampling error in the observations, and the diurnal component of oceanic rainfall. The diurnal component is weak but clearly visible when averaged over large areas and for long time periods. The analysis shows that morning rainfall is consistently greater than evening rainfall. The Northern Hemisphere seems to have a larger diurnal variation than does the Southern Hemisphere. The maximum ratio between the morning and evening monthly rainfall is 1.7 while 1.2 is the more typical value. C1 ST SYST CORP,LANHAM,MD. TEXAS A&M UNIV SYST,DEPT METEOROL,COLLEGE STN,TX 77843. RP SHARMA, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 975,BLDG 22,ROOM 301-B,GREENBELT,MD 20771, USA. RI Wilheit, Thomas/G-9438-2012 NR 17 TC 21 Z9 21 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 1991 VL 119 IS 9 BP 2168 EP 2175 DI 10.1175/1520-0493(1991)119<2168:EOTDCO>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GF876 UT WOS:A1991GF87600007 ER PT J AU KELLER, JW OGILVIE, KW BORING, JW MCKEMIE, RW AF KELLER, JW OGILVIE, KW BORING, JW MCKEMIE, RW TI MEASUREMENT OF THE SECONDARY-EMISSION YIELD OF ELECTRONS FROM THIN CARBON FOILS AFTER PASSAGE OF LOW-ENERGY IONS SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article ID HEAVY-IONS; IDENTIFICATION; SURFACES AB Measurements were made of the forward scattered secondary electron yield from thin carbon foils bombarded by heavy ions in the energy range from 2 to 100 keV/amu. The ratio, LAMBDA-f, of the forward scattered yield to the stopping power is constant from 2 to 10 keV/amu at 3.6 electrons cm2/(eV-mu-g) but as the ion energy is increased above 10 keV/amu, LAMBDA-f decreases to near 2.2 electrons cm2/(eV-mu-g). C1 UNIV VIRGINIA,DEPT NUCL ENGN & ENGN PHYS,CHARLOTTESVILLE,VA 22903. RP KELLER, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Keller, John/I-5097-2013 NR 23 TC 5 Z9 5 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD SEP PY 1991 VL 61 IS 3 BP 291 EP 294 DI 10.1016/0168-583X(91)95632-N PG 4 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA GG333 UT WOS:A1991GG33300003 ER PT J AU KERR, EL AF KERR, EL TI INTEGRAL SUNSHADE FOR AN OPTICAL RECEPTION ANTENNA SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL COMMUNICATIONS; DEEP-SPACE COMMUNICATIONS; OPTICAL RECEPTION ANTENNA; INTEGRAL SUNSHADE; LARGE TELESCOPE; SEGMENTED APERTURE AB Optical reception antennas (telescopes) must be capable of receiving communications even when the deep-space laser source is at a small solar elongation (appears form Earth to be located within a small angle of the Sun.) Direct sunlight must not be allowed to shine on the primary reflector of an optical reception antenna, because too much light would be scattered into the signal detectors. A conventional sunshade that does not obstruct the antenna aperture would have to be about five times longer than its diameter for reception at a solar elongation of 12 deg. Such a long sunshade is unwieldy, either on the ground or in space. Since a new large-aperture optical reception antenna will probably have a hexagonally segmented primary reflector, a sunshade consisting of closely packed hexagonal tubes is proposed. It will be mounted in alignment with the segmentation to avoid producing any additional geometric obstruction. The tubes will be extended downward toward the primary reflector, until they reach the envelope of the focused beam to the secondary reflector. When the optical reception antenna is ground based, the other ends of the tubes will be trimmed and the antenna will be mounted so that both the sunshade and the antenna will swing within a sphere whose diameter is only six-fifths the diameter of the primary reflector. If the segmentation involves four rings of hexagons around an absent central hexagon, then this sunshade will be useful when the solar elongation is as small as 12 deg. The usefulness can be extended to 10 deg by adding shutters to block the tube corners that admit off-axis sunlight. Vanes or slats may be inserted in the tubes to permit operation at 6 deg, or double vanes down to 3 deg. The structure of the sunshade is very strong and may be used to support the secondary reflector instead of an independent support. C1 CALTECH,JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109. NR 6 TC 0 Z9 0 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 SEP PY 1991 VL 30 IS 9 BP 1372 EP 1381 DI 10.1117/12.55932 PG 10 WC Optics SC Optics GA GF746 UT WOS:A1991GF74600017 ER PT J AU LANG, RJ AF LANG, RJ TI GEOMETRIC FORMULATION OF UNSTABLE-RESONATOR DESIGN AND APPLICATION TO SELF-COLLIMATING UNSTABLE-RESONATOR DIODE-LASERS SO OPTICS LETTERS LA English DT Article AB A new set of design parameters for unstable resonators is presented that yields simpler expressions for the mirror and beam radii and magnification than those given by the usual g parameters. The new formalism is applied to determine the design of a solid unstable resonator of index n with a self-collimated output beam, applicable to unstable-resonator diode lasers. RP LANG, RJ (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 7 TC 3 Z9 3 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD SEP 1 PY 1991 VL 16 IS 17 BP 1319 EP 1321 DI 10.1364/OL.16.001319 PG 3 WC Optics SC Optics GA GE692 UT WOS:A1991GE69200009 PM 19776957 ER PT J AU SEVERS, WB HARTMAN, RD MORROW, BA KEIL, LC AF SEVERS, WB HARTMAN, RD MORROW, BA KEIL, LC TI CEREBROSPINAL-FLUID PRESSURE OF CONSCIOUS RATS AFTER VENOUS CONSTRICTION AT THE RIGHT ATRIUM SO PHARMACOLOGY LA English DT Article DE CEREBROSPINAL FLUID PRESSURE; VASOPRESSIN; WATER BALANCE ID RENAL RESPONSES; VOLUME EXPANSION; NONHUMAN PRIMATE; WATER IMMERSION; VASOPRESSIN; ANGIOTENSIN; RELEASE AB Thoracic shifts of blood stimulate diuresis and natriuresis during spaceflight. The available literature is not conclusive as to whether thoracic afferent neurons are essential for this response. Possibly, an acute elevation in cerebrospinal fluid pressure (CSF-p) activates central compensatory mechanisms. This is because central venous pressure is elevated by thoracic blood shifts and may reduce the pressure gradient for drainage of CSF into the venous sinuses. We tested whether rats with constriction of the venous return at the level of the heart (0.4 mm maximum diameter) had CSF-p different from sham-operated controls. CSF-p in the immediate postoperative period, as well as 1 and 10 days after surgery, were within normal limits and did not differ (p > 0.05). Blood collected at the end of the experiment showed no group differences (p > 0.05) in the hematocrit, or concentrations of sodium, potassium or vasopressin. Thus, changes in CSF-p, per se, appear to be insufficient to explain the cardiovascular or salt/water balance readjustments observed in spaceflight. It is likely that compensatory systems are highly redundant. C1 PENN STATE UNIV,MILTON S HERSHEY MED CTR,COLL MED,DEPT PHARMACOL,HERSHEY,PA 17033. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 19 TC 5 Z9 5 U1 0 U2 0 PU KARGER PI BASEL PA ALLSCHWILERSTRASSE 10, CH-4009 BASEL, SWITZERLAND SN 0031-7012 J9 PHARMACOLOGY JI Pharmacology PD SEP PY 1991 VL 43 IS 3 BP 151 EP 155 DI 10.1159/000138840 PG 5 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA GR373 UT WOS:A1991GR37300005 PM 1775518 ER PT J AU WARNER, TA CAMPAGNA, DJ EVANS, CS LEVANDOWSKI, DW CETIN, H AF WARNER, TA CAMPAGNA, DJ EVANS, CS LEVANDOWSKI, DW CETIN, H TI ANALYZING REMOTE-SENSING GEOBOTANICAL TRENDS IN QUETICO-PROVINCIAL-PARK, ONTARIO, CANADA, USING DIGITAL ELEVATION DATA SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 8TH THEMATIC CONF ON GEOLOGIC REMOTE SENSING CY APR 29-MAY 02, 1991 CL DENVER, CO SP ENVIRONM RES INST MICHIGAN ID SUPERIOR PROVINCE AB Field geological mapping of a 10- by 13-km area in Quetico Provincial Park, Ontario, Canada, depicts a broad central band of metamorphosed mafic and occasional ultramafic lithologies, surrounded by granites and granodiorites. Glacial till is thin and capped by loess in places. The soils are mainly Histosols and Boralfs. The vegetation is dominantly Boreal in nature. To investigate subtle site influences on vegetation, topographic information was analyzed using a digital terrain model. The elevation data were filtered to separate ridge tops and other flat, dry areas from flat moist sites. Landsat Thematic Mapper (TM) data were classified into six forest classes of varying deciduous-coniferous cover using nPDF, a procedure based on probability density functions. The distribution of cover classes on each of the two lithologies shows that forests growing on mafic lithologies are enriched in deciduous species, compared to those growing on granites. Of the forest classes found on mafics, the highest coniferous component was on north facing slopes, and the highest deciduous component on south facing slopes. By contrast, granites showed no appreciable varaition between site classes. Digital elevation derived site data is found to be an important tool in geobotanical investigations in Quetico Provincial Park. C1 UNIV MARYLAND,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WARNER, TA (reprint author), PURDUE UNIV,DEPT EARTH & ATMOSPHER SCI,W LAFAYETTE,IN 47907, USA. RI Warner, Timothy/F-1483-2010 NR 21 TC 3 Z9 3 U1 0 U2 0 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 SEP PY 1991 VL 57 IS 9 BP 1179 EP 1183 PG 5 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA GD546 UT WOS:A1991GD54600006 ER PT J AU MCKEAN, J BUECHEL, S GAYDOS, L AF MCKEAN, J BUECHEL, S GAYDOS, L TI REMOTE-SENSING AND LANDSLIDE HAZARD ASSESSMENT SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 8TH THEMATIC CONF ON GEOLOGIC REMOTE SENSING CY APR 29-MAY 02, 1991 CL DENVER, CO SP ENVIRONM RES INST MICHIGAN ID MAPPER SIMULATOR DATA AB Remotely acquired multispectral data are used to improve landslide hazard assessments at all scales of investigation. A vegetation map produced from automated interpretation of TM data is used in a GIS context to explore the effect of vegetation type on debris flow occurrence in preparation for inclusion in debris flow hazard modeling. Spectral vegetation indices map spatial patterns of grass senescence which are found to be correlated with soil thickness variations on hillslopes. Grassland senescence is delayed over deeper, wetter soils that are likely debris flow source areas. Prediction of actual soil depths using vegetation indices may be possible up to some limiting depth greater than the grass rooting zone. On forested earthflows, the slow slide movement disrupts the overhead timber canopy, exposes understory vegetation and soils, and alters site spectral characteristics. Both spectral and textural measures from broad band multispectral data are successful at detecting an earthflow within an undisturbed old-growth forest. C1 TGS INC,NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,US GEOL SURVEY,MOFFETT FIELD,CA 94035. RP MCKEAN, J (reprint author), US FOREST SERV,PLEASANT HILL,CA 94523, USA. RI McKean, Jim/C-3581-2011 NR 20 TC 35 Z9 37 U1 0 U2 6 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 SEP PY 1991 VL 57 IS 9 BP 1185 EP 1193 PG 9 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA GD546 UT WOS:A1991GD54600007 ER PT J AU DEGUIRE, MR BANSAL, NP FARRELL, DE FINAN, V KIM, CJ HILLS, BJ ALLEN, CJ AF DEGUIRE, MR BANSAL, NP FARRELL, DE FINAN, V KIM, CJ HILLS, BJ ALLEN, CJ TI THE SERIES BI2SR2CAN-1CUNO2N+4 (1 LESS-THAN-OR-EQUAL-TO N LESS-THAN-OR-EQUAL-TO 5) - PHASE-STABILITY AND SUPERCONDUCTING PROPERTIES SO PHYSICA C LA English DT Article ID CA-CU-O; PHYSICAL-PROPERTIES; CRYSTAL-CHEMISTRY; X-RAY; SYSTEM; TC; EQUILIBRIA; OXIDE; 800-DEGREES-C AB Phase relations at 850-degrees-C and 870-degrees-C, and melting transitions in air, oxygen, and helium have been studied for Bi2.1Sr1.9CuO6 and for the series Bi2Sr2Can-1CunO2n+4 for n = 1, 2, 3, 4, 5 and infinity ("CaCuO2"). Up to 870-degrees-C, the n = 2 composition resides in the compatibility tetrahedron bounded by Bi2+x(Sr, Ca)3-yCu2O8, (Sr, Ca)14Cu24O41, Ca2CuO3, and a Bi-Sr-Ca-O phase. The n greater-than-or-equal-to 3 compositions reside in the compatibility tetrahedron Bi2+x(Sr, Ca)3-yCu2O8-(Sr, Ca)14Cu24O41-Ca2CuO3-CuO up to 850-degrees-C. However, Bi2+x(Sr, Ca)4-yCu3O10 forms for n greater-than-or-equal-to 3 after extended heating at 870-degrees-C. Bi2+xSr2-yCuO6 (i.e. the Ca-free, very low-T(c) phase) melts in air at 914-degrees-C, while the Bi2+x(Sr, Ca)3-yCu2O8 composition that coexists with (Sr, Ca)14Cu24O41, Ca2CuO3, and CuO melts at 895-degrees-C. During melting, all of the compositions studied lose 1-2% by weight of oxygen from the reduction of copper. C1 CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. NASA,LEWIS RES CTR,CERAM BRANCH,DIV MAT,CLEVELAND,OH 44135. RP DEGUIRE, MR (reprint author), CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106, USA. NR 37 TC 37 Z9 37 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD SEP 1 PY 1991 VL 179 IS 4-6 BP 333 EP 346 DI 10.1016/0921-4534(91)92179-F PG 14 WC Physics, Applied SC Physics GA GE034 UT WOS:A1991GE03400011 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI 1,3P(0) RESONANCE STATES IN POSITRONIUM IONS SO PHYSICAL REVIEW A LA English DT Article ID NEGATIVE-ION; BOUND-STATES; PHOTODETACHMENT; SYSTEMS AB Doubly excited 1,3P0 autodetaching resonances in Ps- have been calculated using the complex-rotation method, which has the advantage of giving resonance position and width at the same time. The wave function is of the Hylleraas type with number of terms up to 1330. Feshbach resonances associated with the positronium n = 4, 5, and 6 thresholds are reported. In addition, we have also identified 1P0 shape resonances associated with the positronium n = 4 and 6 thresholds, and a 3P0 shape resonance associated with the n = 5 positronium threshold. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HO, YK (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. RI Ho, Yew Kam/F-7912-2012 NR 25 TC 31 Z9 31 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 SEP 1 PY 1991 VL 44 IS 5 BP 2890 EP 2894 DI 10.1103/PhysRevA.44.2890 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA GE936 UT WOS:A1991GE93600020 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI COMPLEX-COORDINATE CALCULATION OF 1,3D RESONANCES IN 2-ELECTRON SYSTEMS SO PHYSICAL REVIEW A LA English DT Article ID DOUBLY EXCITED-STATES; ELECTRON-SPECTROSCOPY; HE; AUTOIONIZATION; COLLISIONS; SCATTERING; THRESHOLD; ENERGIES; IMPACT AB Feshbach-type 1,3D resonances in two-electron systems, Z = 2-10, have been investigated using the method of complex rotation. These states lie below the n = 2 and 3 thresholds of hydrogenic systems. Wave functions containing up to 1230 Hylleraas functions have been used, giving accurate results for positions and widths. Comparisons between various calculations are given. 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 17 TC 60 Z9 60 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 SEP 1 PY 1991 VL 44 IS 5 BP 2895 EP 2899 DI 10.1103/PhysRevA.44.2895 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA GE936 UT WOS:A1991GE93600021 ER PT J AU DEGANI, D AF DEGANI, D TI EFFECT OF SPLITTER PLATE ON UNSTEADY FLOWS AROUND A BODY OF REVOLUTION AT INCIDENCE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID VORTEX ASYMMETRY; CYLINDER AB Numerical solutions of the thin-layer approximation of the three-dimensional Navier-Stokes equations have been obtained for flows around an ogive-cylinder body with and without a splitter plate. The numerical results were compared qualitatively with experimental surface pressure, hot-wire anemometer measurements, and smoke visualization of the leeside vortex flow field at high angles of attack. Both experimental and numerical results show that the presence of a splitter plate in the leeward plane of symmetry suppresses the low-frequency, large-scale von Karman vortex shedding from the body and leaves the two primary vortices symmetric and almost parallel to the upper surface of the body. It is suggested that the presence of the splitter plate prevents the interaction between flows on either side of the symmetry plane. As a result of the enforced symmetry (a) the antisymmetric mode of the convective instability near the apex of the body cannot be excited and therefore the vortices remain symmetric, staying low and parallel to the upper body surface; and (b) the antisymmetric mode of the absolute instability mechanism cannot be initiated, which suppresses the alternate shedding of vortices from the cylindrical portion of the body. On the other hand, high-frequency fluctuations of the shear layer (which could be the result of a local instability not subject to symmetry conditions) remain virtually unaffected by the presence of the splitter plate. RP DEGANI, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 27 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 0899-8213 J9 PHYS FLUIDS A-FLUID PD SEP PY 1991 VL 3 IS 9 BP 2122 EP 2131 DI 10.1063/1.858210 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GD545 UT WOS:A1991GD54500013 ER PT J AU DANABASOGLU, G BIRINGEN, S STREETT, CL AF DANABASOGLU, G BIRINGEN, S STREETT, CL TI SPATIAL SIMULATION OF INSTABILITY CONTROL BY PERIODIC SUCTION BLOWING SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID ORR-SOMMERFELD EQUATION; TRANSITION AB The applicability of active control by periodic suction blowing in spatially evolving plane Poiseuille flow is investigated by the direct simulation of the three-dimensional, incompressible Navier-Stokes equations. The results reveal that significant reductions in perturbation amplitudes can be obtained by a proper choice of the control wave amplitude and phase. The upstream influence of the control wave is shown to be confined to a region in the vicinity of the control slot with no apparent effect on the flow development. C1 NASA,LANGLEY RES CTR,DIV FLUID DYNAM,THEORET AERODYNAM BRANCH,HAMPTON,VA 23665. RP DANABASOGLU, G (reprint author), UNIV COLORADO,DEPT AEROSP ENGN SCI,BOULDER,CO 80309, USA. NR 19 TC 24 Z9 24 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 SEP PY 1991 VL 3 IS 9 BP 2138 EP 2147 DI 10.1063/1.857896 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GD545 UT WOS:A1991GD54500015 ER PT J AU COLEMAN, GN MANSOUR, NN AF COLEMAN, GN MANSOUR, NN TI MODELING THE RAPID SPHERICAL COMPRESSION OF ISOTROPIC TURBULENCE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID FLOWS AB Rapid distortion analysis is used to modify the form of the closure model for the dissipation rate of the turbulent kinetic energy. The modification is such that the evolution of the dissipation rate during a rapid compression is predicted exactly; good agreement between the model prediction and direct simulation data is obtained. Previous closure proposals fail to properly predict the rapid compression case. The reason for the difference between the present and previous models is traced to the fact that previous workers neglected variations of kinematic viscosity. RP COLEMAN, GN (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 15 TC 29 Z9 30 U1 0 U2 3 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 SEP PY 1991 VL 3 IS 9 BP 2255 EP 2259 DI 10.1063/1.857906 PG 5 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GD545 UT WOS:A1991GD54500025 ER PT J AU SPEZIALE, CG GATSKI, TB FITZMAURICE, N AF SPEZIALE, CG GATSKI, TB FITZMAURICE, N TI AN ANALYSIS OF RNG-BASED TURBULENCE MODELS FOR HOMOGENEOUS SHEAR-FLOW SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Note AB In a recent paper [Phys. Fluids A 2, 1678 (1990)], the authors compared the performance of a variety of turbulence models including the K-epsilon model and the second-order closure model derived by Yakhot and Orszag based on renormalization group (RNG) methods. The performance of these RNG models in homogeneous turbulent shear flow was found to be quite poor, apparently due to the value of the constant C-epsilon-1 in the modeled dissipation rate equation, which was substantially lower than its traditional value. However, recently a correction has been made in the RNG-based calculation of C-epsilon-1. It is shown herein that, with the new value of C-epsilon-1, the performance of the RNG K-epsilon model is substantially improved. On the other hand, while the predictions of the revised RNG second-order closure model are better, some lingering problems still remain that can be remedied by the addition of higher-order terms. C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. RP SPEZIALE, CG (reprint author), NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23665, USA. NR 11 TC 18 Z9 25 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 SEP PY 1991 VL 3 IS 9 BP 2278 EP 2281 DI 10.1063/1.857963 PG 4 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GD545 UT WOS:A1991GD54500028 ER PT J AU LUMPKIN, FE HAAS, BL BOYD, ID AF LUMPKIN, FE HAAS, BL BOYD, ID TI RESOLUTION OF DIFFERENCES BETWEEN COLLISION NUMBER DEFINITIONS IN PARTICLE AND CONTINUUM SIMULATIONS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Note AB The use of the same symbol, Z, representing a "collision number" for thermal relaxation, has led to confusion regarding its definition in the context of both continuum and particle simulations. Examination of the relaxation mechanics employed in particle simulations demonstrates that these definitions differ by a numerical factor that depends upon the intermolecular potential. Particle and continuum simulations employing appropriate definitions of Z lead to identical results during isothermal and adiabatic stationary relaxation. C1 ELORET INST,PALO ALTO,CA 94303. RP LUMPKIN, FE (reprint author), NASA,AMES RES CTR,AEROTHERMODYNAM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 5 TC 35 Z9 37 U1 0 U2 4 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 SEP PY 1991 VL 3 IS 9 BP 2282 EP 2284 DI 10.1063/1.857964 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GD545 UT WOS:A1991GD54500029 ER PT J AU HELGERT, HJ AF HELGERT, HJ TI SERVICES, ARCHITECTURES, AND PROTOCOLS FOR SPACE DATA SYSTEMS SO PROCEEDINGS OF THE IEEE LA English DT Article AB The next generation space data systems currently in the planning stages are being designed to implement standardized and internationally agreed upon techniques of data handling, data classification, and data transmission. These techniques are for the most part being developed by the Consultative Committee for Space Data Systems (CCSDS), a worldwide cooperative effort of national space agencies. In this paper we present a comprehensive discussion of three major aspects of the work of the CCSDS. First, we examine the CCSDS space data communications network concept on which the data communications facilities of future advanced orbiting systems will be based. Second, we derive the specifications of an open communications architecture as a reference model for the development of services and protocols that support the transfer of information over space data communications networks. Third, we offer detailed specifications of the communication services and information transfer protocols that have reached a high degree of maturity and stability. The paper also includes a complete list of currently available CCSDS standards and supporting documentation. C1 CORNELL UNIV,AERONAUT LAB,ITHACA,NY 14853. CLEMSON UNIV,CLEMSON,SC 29631. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HELGERT, HJ (reprint author), GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052, USA. NR 7 TC 1 Z9 1 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 0018-9219 J9 P IEEE JI Proc. IEEE PD SEP PY 1991 VL 79 IS 9 BP 1213 EP 1231 DI 10.1109/5.97293 PG 19 WC Engineering, Electrical & Electronic SC Engineering GA GL053 UT WOS:A1991GL05300002 ER PT J AU MADORE, BF FREEDMAN, WL AF MADORE, BF FREEDMAN, WL TI THE CEPHEID DISTANCE SCALE SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Review DE GALAXIES; DISTANCES; STARS; PHOTOMETRY; STARS; CEPHEIDS ID MAGELLANIC CLOUD CEPHEIDS; SURFACE-BRIGHTNESS FLUCTUATIONS; PERIOD-LUMINOSITY RELATION; NEAR-INFRARED OBSERVATIONS; DWARF IRREGULAR GALAXIES; COLD DARK MATTER; PLANETARY-NEBULAE; STANDARD CANDLES; BRIGHTEST STARS; SEXTANS-A AB Developments concerning of the period-luminosity (PL) relation for classical Cepheids are discussed with particular emphasis on the fact that Cepheids continue to provide the most homogeneous and reliable set of distances to many nearby galaxies. Observational programs relating to extragalactic Cepheids are also reviewed, and new distances and reddenings to individual galaxies are determined from these data using multiwavelength PL relations, based for the first time on self-consistent calibrating data sets. Three recent promising secondary extragalactic distance indicators (Tully-Fisher, planetary nebula luminosity functions, and surface-brightness fluctuations) tie their zero points to the Cepheid distance scale and give globally consistent values for the Hubble constant of about 80 km sec-1 Mpc-1. Tying the Faber-Jackson relation and the supernova distance scales to the Leo and Virgo clusters yields similar results. Such a value for the Hubble constant is marginally inconsistent with new estimates of the ages of globular clusters, and it may prove to be a serious problem for standard cold dark-matter models of the universe. C1 CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. RP MADORE, BF (reprint author), CALTECH,JET PROP LAB,NASA,CTR INFRARED PROC & ANAL EXTRAGALACT DATABASE,PASADENA,CA 91125, USA. NR 147 TC 376 Z9 378 U1 1 U2 3 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 SEP PY 1991 VL 103 IS 667 BP 933 EP 957 DI 10.1086/132911 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GJ187 UT WOS:A1991GJ18700001 ER PT J AU KRISCIUNAS, K SCHAEFER, BE AF KRISCIUNAS, K SCHAEFER, BE TI A MODEL OF THE BRIGHTNESS OF MOONLIGHT SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article DE NIGHT-SKY BRIGHTNESS; MOONLIGHT; ATMOSPHERIC EXTINCTION ID SKY BRIGHTNESS AB A knowledge of the brightness of moonlight is needed for detailed calculations of the limiting magnitude of astronomical detectors, whether they be visual, photographic, or electronic. The previous literature contains no method for making even crude estimates and has few actual measurements of moonlight brightness. In this paper we report new measurements of the sky brightness from the 2800-m level of Mauna Kea. In addition, we present a model for predicting the moonlight as a function of the Moon's phase, the zenith distance of the Moon, the zenith distance of the sky position, the angular separation of the Moon and sky position, and the local extinction coefficient. The model equations can be quickly calculated on a pocket calculator. A comparison of our model with our lunar data and with some Russian solar data shows the accuracy of our predictions to range from 8% to 23%. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KRISCIUNAS, K (reprint author), JOINT ASTRON CTR,665 KOMOHANA ST,HILO,HI 96720, USA. NR 26 TC 76 Z9 76 U1 1 U2 3 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 SEP PY 1991 VL 103 IS 667 BP 1033 EP 1039 DI 10.1086/132921 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GJ187 UT WOS:A1991GJ18700011 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI LENGTH OF THE LUNAR CRESCENT SO QUARTERLY JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article AB The thin crescent Moon is observed not to extend the full 180-degrees arc expected if the Moon had an ideal surface. I report on a collection of 65 crescent arc length observations made across North America on 1989 April 6. These observations show the crescent length to be independent of whether or not the observer used any optical aid. Since the resolution of a naked eye observer is more than an order of magnitude larger then either the seeing disk size or the resolution of a telescopic observer, the effect of the seeing on the perceived arc length must be negligible. A theory to explain the crescent shortening is that the brightness falls of steeply to the cusps so that visual observers will not detect the cusps because they are fainter than the threshold for visual detection. Lunar surface brightnesses are calculated according to the accurate model by Hapke (1984), and it is found that all Danjon's (1932, 1936) collected observations and my new data are well fitted by this model. One implication for lunar calendars is that the crescent cannot be detected if the Moon is within 7-degrees of the Sun, although other effects will always cause the Moon to be invisible until the distance from the Sun is significantly greater. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 21 TC 8 Z9 8 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 SEP PY 1991 VL 32 IS 3 BP 265 EP 277 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD504 UT WOS:A1991GD50400005 ER PT J AU MYNENI, RB ASRAR, G AF MYNENI, RB ASRAR, G TI PHOTON INTERACTION CROSS-SECTIONS FOR AGGREGATIONS OF FINITE-DIMENSIONAL LEAVES SO REMOTE SENSING OF ENVIRONMENT LA English DT Note AB The plate turbid medium theory developed by Ross abstracts the leaf canopy as a gaseous mixture of oriented planar nondimensional plates randomly distributed in the configuration space. This theory fails to explain the hot spot effect that is characteristic of all layered media that contain finite-dimensional scattering centers. The dimensions of the scatterer was included in a new formalism recently developed by Myneni et al. (1991). However, the arguments used in the derivation of the cross sections were intuitive and lack a basis in rigorous theory. In this paper, using the concept of particle distribution functions, the interaction cross sections are derived. C1 NASA,WASHINGTON,DC 20546. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROLOG SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 14 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD SEP PY 1991 VL 37 IS 3 BP 219 EP 224 DI 10.1016/0034-4257(91)90083-I PG 6 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GL838 UT WOS:A1991GL83800006 ER PT J AU SHAKKOTTAI, P KWACK, EY BACK, LH AF SHAKKOTTAI, P KWACK, EY BACK, LH TI AEROACOUSTIC FLOW SENSOR SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID AERO-ACOUSTIC SOURCES; TONE GENERATION AB A theoretical analysis of standing waves in a pipe with flow was conducted aimed toward the development of a flowmeter based on a measurement of phase difference between two points on the circumference of a pipe separated axially by an integral multiple of half sound wavelength. Effects of nonzero Mach number, variable ratios of upstream and downstream running waves, choice of location of the sensing pressure taps, and the incorrect spacings were examined numerically. Calculations were also made for steam flow where the maximum Mach number is much smaller than in cold air flows. For an industrial application where steam flow velocities are below 50 m/s, a very accurate sensor is shown to be possible. Experimental data were obtained by using an active aeroacoustic source over the range of 50 m/s to zero in an air flow. Experimental phase plots obtained from several coast-down tests have been compared with analytical results. The agreement with theory is excellent when the spacings are near N-lambda/2 and the sensing locations are near the pressure antinodes. Otherwise, some zero shifts are introduced. Theory predicts that for steam flow much better results can be expected because the maximum Mach number is much smaller. Effects due to the (1 - M2) factor would be imperceptible for steam flow. RP CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0034-6748 EI 1089-7623 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 1991 VL 62 IS 9 BP 2205 EP 2212 DI 10.1063/1.1142338 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA GD506 UT WOS:A1991GD50600025 ER PT J AU BAILEY, DH SWARZTRAUBER, PN AF BAILEY, DH SWARZTRAUBER, PN TI THE FRACTIONAL FOURIER-TRANSFORM AND APPLICATIONS SO SIAM REVIEW LA English DT Article DE DISCRETE FOURIER TRANSFORM; FAST FOURIER TRANSFORM ID CONVOLUTION; ALGORITHMS; FFTS AB This paper describes the "fractional Fourier transform," which admits computation by an algorithm that has complexity proportional to the fast Fourier transform algorithm. Whereas the discrete Fourier transform (DFT) is based on integral roots of unity e-2-pi-i/n, the fractional Fourier transform is based on fractional roots of unity e-2-pi-i-alpha, where alpha is arbitrary. The fractional Fourier transform and the corresponding fast algorithm are useful for such applications as computing DFTs of sequences with prime lengths, computing DFTs of sparse sequences, analyzing sequences with noninteger periodicities, performing high-resolution trigonometric interpolation, detecting lines in noisy images, and detecting signals with linearly drifting frequencies. In many cases, the resulting algorithms are faster by arbitrarily large factors than conventional techniques. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP BAILEY, DH (reprint author), NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT SYST,MOFFETT FIELD,CA 94035, USA. NR 17 TC 146 Z9 152 U1 0 U2 11 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0036-1445 J9 SIAM REV JI SIAM Rev. PD SEP PY 1991 VL 33 IS 3 BP 389 EP 404 DI 10.1137/1033097 PG 16 WC Mathematics, Applied SC Mathematics GA GE704 UT WOS:A1991GE70400002 ER PT J AU WOODYARD, JR LANDIS, GA AF WOODYARD, JR LANDIS, GA TI RADIATION-RESISTANCE OF THIN-FILM SOLAR-CELLS FOR SPACE PHOTOVOLTAIC POWER SO SOLAR CELLS LA English DT Article ID HYDROGENATED AMORPHOUS-SILICON; ELECTRON-IRRADIATION; DEFECTS AB Copper indium diselenide, cadmium telluride and amorphous silicon alloy solar cells have achieved noteworthy performance and are currently being investigated for space power applications. Cadmium sulphide cells had been the subject of considerable effort but are no longer considered for space applications. This article presents a review of what is known about the radiation-induced degradation of thin-film solar cells in space. Experimental investigations of electron and proton irradiation of cadmium sulphide, copper indium diselenide, cadmium telluride and amorphous silicon alloy cells are reviewed. Damage mechanisms and radiation-induced defect generation and passivation in the amorphous silicon alloy cell are discussed in detail owing to the greater amount of experimental data available. C1 NASA,LEWIS RES CTR 302-1,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP WOODYARD, JR (reprint author), WAYNE STATE UNIV,DEPT ELECT & COMP ENGN,DETROIT,MI 48202, USA. NR 63 TC 31 Z9 31 U1 1 U2 7 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6787 J9 SOL CELLS PD SEP PY 1991 VL 31 IS 4 BP 297 EP 329 DI 10.1016/0379-6787(91)90103-V PG 33 WC Energy & Fuels SC Energy & Fuels GA GE166 UT WOS:A1991GE16600002 ER PT J AU WEINBERG, I AF WEINBERG, I TI RADIATION-DAMAGE IN INP SOLAR-CELLS SO SOLAR CELLS LA English DT Article ID ELECTRON-IRRADIATED INP; INDUCED DEFECTS; RESISTANCE; IDENTIFICATION; SEMICONDUCTORS; CRYSTALS; CENTERS AB The effects of radiation on InP solar cells is reviewed. Included are: a performance overview comparing InP, GaAs and silicon cells under laboratory irradiations, space flight data, defect studies using both electron paramagnetic resonance and deep level transient spectroscopy, carrier removal, thermal and minority carrier injection annealing and lifetime and diffusion length radiation damage coefficients. A discussion of the primary reason for the superior performance, under irradiation, of InP solar cells is followed by an exposition of the barrier problems requiring solution before InP can be considered for widespread use in space. RP WEINBERG, I (reprint author), NASA,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 59 TC 10 Z9 10 U1 0 U2 2 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6787 J9 SOL CELLS PD SEP PY 1991 VL 31 IS 4 BP 331 EP 348 DI 10.1016/0379-6787(91)90104-W PG 18 WC Energy & Fuels SC Energy & Fuels GA GE166 UT WOS:A1991GE16600003 ER PT J AU WEINBERG, I AF WEINBERG, I TI RADIATION EFFECTS ON SOLAR-CELLS - PREFACE SO SOLAR CELLS LA English DT Editorial Material RP WEINBERG, I (reprint author), NASA,LEWIS RES CTR,PHOTOVOLTAIC BRANCH,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6787 J9 SOL CELLS PD SEP PY 1991 VL 31 IS 4 BP R5 EP R6 DI 10.1016/0379-6787(91)90102-U PG 2 WC Energy & Fuels SC Energy & Fuels GA GE166 UT WOS:A1991GE16600001 ER PT J AU BATCHELOR, DA HINDSLEY, KP AF BATCHELOR, DA HINDSLEY, KP TI X-RAY OBSERVATIONS OF FILAMENT ERUPTION IN THE 1980 MAY 21 FLARE SO SOLAR PHYSICS LA English DT Article ID SOLAR MAXIMUM MISSION; CHROMOSPHERIC EVAPORATION; IMPULSIVE PHASE; RECONNECTION; SPECTROMETER; PROMINENCE; BURST; ARCH AB X-ray and H-alpha observations of an erupting filament, discussed herein, and other observations of the associated flare on 1980 May 21, suggest that an erupting filament played a major role in the X-ray flare. While Antonucci et al. (1985) analyzed the May 21 flare as one of the best cases of chromospheric evaporation, the possible contribution from X-ray emitting erupting plasma has been ignored. We show that pre-heated plasma existed and may have contributed part of the blue-shifted X-ray emission observed in the Ca XIX line, which was formerly attributed solely to chromospheric evaporation. Thus it remains an open question - in two-ribbon flares in particular - just how important chromospheric evaporation is in flare dynamics. RP BATCHELOR, DA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,MAIL CODE 933,GREENBELT,MD 20771, USA. NR 33 TC 5 Z9 5 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 SEP PY 1991 VL 135 IS 1 BP 99 EP 105 DI 10.1007/BF00146701 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GH218 UT WOS:A1991GH21800007 ER PT J AU BAILEY, DH AF BAILEY, DH TI 12 WAYS TO FOOL THE MASSES WHEN GIVING PERFORMANCE RESULTS ON PARALLEL COMPUTERS SO SUPERCOMPUTER LA English DT Editorial Material AB Many of us in the field of highly parallel scientific computing recognize that it is often quite difficult to match the run time performance of the best conventional supercomputers. This humorous article outlines twelve ways commonly used in scientific papers and presentations to artificially boost performance rates and to present these results in the "best light possible" compared to other systems. RP BAILEY, DH (reprint author), NASA,AMES RES CTR,DIV NUMERICAL AERODYNAM SIMULAT SYST,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ASFRA PI EDAM PA VOORHAVEN 33, 1135 BL EDAM, NETHERLANDS SN 0168-7875 J9 SUPERCOMPUTER JI Supercomputer PD SEP PY 1991 VL 8 IS 5 BP 4 EP 7 PG 4 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA GV975 UT WOS:A1991GV97500001 ER PT J AU COOPER, KP AYERS, JD KAMPE, JCM FENG, CR LOCCI, IE AF COOPER, KP AYERS, JD KAMPE, JCM FENG, CR LOCCI, IE TI MICROSTRUCTURAL EVOLUTION AND THERMAL-STABILITY IN RAPIDLY SOLIDIFIED HIGH-CHROMIUM-CONTAINING COPPER-ALLOYS SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID PHASE AB Rapidly solidified samples of Cu-Cr alloys containing 2 wt.% Ag were prepared by high pressure gas atomization and by melt spinning. Both quenching techniques yielded microstructures which showed evidence of the formation of two immiscible liquids prior to solidification. To evaluate the effect of high temperatures on the stability of the as-solidified microstructures, samples prepared by hot isostatic pressing (HIP) consolidation of the atomized powder and by heat treatment of the melt-spun ribbons were examined in the scanning electron microscope and transmission electron microscope. Results showed that the shape of the chromium phase in all cases was spheroidal and the spheroid size depended upon the solidification rate and alloy composition. The chromium spheriods in the melt-spun ribbon readily coarsened at higer temperatures, but the coarser chromium spheroids in the atomized powders ripened less quickly when hot isostatically pressed at comparable temperatures. Although capillary-driven diffusional coarsening predominated, diffusion-controlled growth from supersaturation also played a part in increasing the spheroid size. Coarsening in the annealed melt-spun ribbons resulted in a loss of microhardness, while HIP consolidation had little effect on the microhardness of the atomized powder. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP COOPER, KP (reprint author), USN,RES LAB,DIV MAT SCI & TECHNOL,CODE 6320,WASHINGTON,DC 20375, USA. NR 22 TC 18 Z9 19 U1 1 U2 2 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 AUG 30 PY 1991 VL 142 IS 2 BP 221 EP 233 DI 10.1016/0921-5093(91)90661-6 PG 13 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA GD452 UT WOS:A1991GD45200010 ER PT J AU POKELA, PJ KOLAWA, E RUIZ, R NICOLET, MA AF POKELA, PJ KOLAWA, E RUIZ, R NICOLET, MA TI CHARACTERIZATION OF THE A1/TA-SI-N/AU METALLIZATION SO THIN SOLID FILMS LA English DT Article ID DIFFUSION; ALUMINUM; SYSTEM; SI AB The thermal stability of amorphous, r.f.-sputtered Ta36Si14N50 films is studied for application as a diffusion barrier between aluminium and gold layers. Analyses by backscattering spectrometry, scanning electron microscopy together with energy-dispersive analysis of X-rays, and optical microscopy are performed to evaluate the effectiveness of the diffusion barriers. A 300 nm thick Ta36Si14N50 film prevents the intermixing between aluminum and gold contacts up to 30 min annealing at 550-degrees-C in vacuum. Films about 150 nm and 80 nm in thickness fail already during 30 min annealings at 550-degrees-C and 500-degrees-C respectively. The failure of the metallization is caused by the Al-Au interdiffusion which takes place in a highly localized manner through the ternary thin film. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP POKELA, PJ (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 15 TC 19 Z9 19 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD AUG 30 PY 1991 VL 203 IS 2 BP 259 EP 266 DI 10.1016/0040-6090(91)90133-I PG 8 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA GG386 UT WOS:A1991GG38600006 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H AF LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H TI THE STUDY OF THE SPECTROSCOPY OF SMALL MOLECULES BY ABINITIO METHODS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 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 AUG 25 PY 1991 VL 202 BP 5 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100545 ER PT J AU FRIEDL, RR AF FRIEDL, RR TI SHORT-LIVED MOLECULES OF RELEVANCE IN THE EARTHS ATMOSPHERE - EXPERIMENTAL STUDIES OF THE SPECTROSCOPY OF NO3, CL2O2, AND CL2O3 SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. 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 AUG 25 PY 1991 VL 202 BP 17 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100557 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI SYNTHESIS AND PROPERTIES OF POLY(ARYLENE ETHER BENZIMIDAZOLE)S 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 AUG 25 PY 1991 VL 202 BP 25 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100927 ER PT J AU JENSEN, BJ AF JENSEN, BJ TI PREPARATION, CHARACTERIZATION AND TOUGHNESS OF ETHYNYL CONTAINING BLENDS 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 AUG 25 PY 1991 VL 202 BP 40 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100942 ER PT J AU VALENTIN, JR DIRB, L HALL, KW PHILLIPS, JB BANIN, A AF VALENTIN, JR DIRB, L HALL, KW PHILLIPS, JB BANIN, A TI A CHEMICAL MODULATOR TO MEASURE WATER-VAPOR IN A GASEOUS MIXTURE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV,DEPT PHYS,SAN JOSE,CA 95192. SO ILLINOIS UNIV,DEPT CHEM & BIOCHEM,CARBONDALE,IL 62901. HEBREW UNIV JERUSALEM,DEPT SOIL & WATER SCI,IL-76100 REHOVOT,ISRAEL. 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 AUG 25 PY 1991 VL 202 BP 52 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08000421 ER PT J AU MARGALIT, R VASQUEZ, R AF MARGALIT, R VASQUEZ, R TI STUDY OF SURFACE ORIENTATION FOR THE DESIGN OF MOLECULAR ELECTRONICS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. 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 AUG 25 PY 1991 VL 202 BP 53 EP BIOT PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08000562 ER PT J AU KUNDU, KP DEUR, J AF KUNDU, KP DEUR, J TI OXIDATION OF NITROGEN-OXIDES IN HOMOGENEOUS GAS-PHASE REACTIONS - COMBUSTION EMISSION MODELING 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 AUG 25 PY 1991 VL 202 BP 127 EP FUEL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08001909 ER PT J AU BERATAN, DN AF BERATAN, DN TI ELECTRON-TUNNELING PATHWAYS IN NATIVE AND MODIFIED PROTEINS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093. 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 AUG 25 PY 1991 VL 202 BP 133 EP BIOL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08000890 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H AF BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H TI STUDY OF LIGAND LIGAND INTERACTIONS IN MLN+ SYSTEMS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 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 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 AUG 25 PY 1991 VL 202 BP 171 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100706 ER PT J AU BERATAN, DN CHENG, LT MARDER, SR MURDOCH, J PERRY, JW TIEMANN, BG TSENG, JCC VANDOREMAELE, G AF BERATAN, DN CHENG, LT MARDER, SR MURDOCH, J PERRY, JW TIEMANN, BG TSENG, JCC VANDOREMAELE, G TI DESIGN OF NONLINEAR OPTICAL-MATERIALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 DUPONT CO,EXPTL STN,WILMINGTON,DE 19880. CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 2 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 AUG 25 PY 1991 VL 202 BP 173 EP BIOT PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08000680 ER PT J AU PERRY, JW AF PERRY, JW TI NONLINEAR OPTICAL-DEVICES USING ORGANIC MATERIALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 2 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 AUG 25 PY 1991 VL 202 BP 176 EP BIOT PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08000683 ER PT J AU JAFFE, RL RICCITIELLO, S HSU, MT CHEN, T AF JAFFE, RL RICCITIELLO, S HSU, MT CHEN, T TI CHARACTERIZATION AND OXIDATION REACTIONS OF SI-B-C POLYMERS - EXPERIMENTAL AND THEORETICAL-STUDIES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 BC CHEM RES SERV CORP,SAN JOSE,CA. POLYATOM RES INST,MT VIEW,CA 94043. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 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 AUG 25 PY 1991 VL 202 BP 187 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08101089 ER PT J AU LEE, TJ TAYLOR, PR AF LEE, TJ TAYLOR, PR TI AN ABINITIO STUDY OF THE MOLECULAR-STRUCTURE, VIBRATIONAL-SPECTRUM AND BINDING-ENERGY OF THE LOWEST SINGLET AND TRIPLET-STATES OF MGC2 SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 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 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 AUG 25 PY 1991 VL 202 BP 276 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08100809 ER PT J AU ALVAREZ, D CUMMINGS, G MARDER, SR PERRY, KJ PERRY, JW AF ALVAREZ, D CUMMINGS, G MARDER, SR PERRY, KJ PERRY, JW TI SYNTHETIC AND OPTICAL LIMITING STUDIES OF METALLOPHTHALOCYANINES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 3 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 AUG 25 PY 1991 VL 202 BP 303 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08002356 ER PT J AU SPOTTS, JM SCHAEFER, WP MARDER, SR AF SPOTTS, JM SCHAEFER, WP MARDER, SR TI THE SYNTHESIS AND SPECTROSCOPIC PROPERTIES OF ORGANOMETALLIC CYANINES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. CALTECH,DIV CHEM & CHEM ENGN,PASADENA,CA 91125. 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 AUG 25 PY 1991 VL 202 BP 335 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG080 UT WOS:A1991HG08002388 ER PT J AU JAFFE, RL AF JAFFE, RL TI ABINITIO QUANTUM CHEMICAL-POTENTIAL ENERGY FUNCTIONS FOR THE ATOMISTIC SIMULATION OF POLYMERIC MATERIALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 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 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 AUG 25 PY 1991 VL 202 BP 350 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08101249 ER PT J AU LUDOVICE, PJ JAFFE, RL YOON, DY AF LUDOVICE, PJ JAFFE, RL YOON, DY TI STRUCTURAL-ANALYSIS OF POLYVINYLCHLORIDE USING AN ABINITIO DERIVED CLASSICAL FORCE-FIELD SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 POLYGEN CORP,WALTHAM,MA 02254. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. 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 AUG 25 PY 1991 VL 202 BP 351 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HG081 UT WOS:A1991HG08101250 ER PT J AU TANAKA, KL GOLOMBEK, MP BANERDT, WB AF TANAKA, KL GOLOMBEK, MP BANERDT, WB TI RECONCILIATION OF STRESS AND STRUCTURAL HISTORIES OF THE THARSIS REGION OF MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID LITHOSPHERIC STRESS; VALLES MARINERIS; MAGMATIC SYSTEMS; TECTONIC HISTORY; RIDGED PLAINS; GROUND ICE; GEOMETRY; GRAVITY; THICKNESS; PROVINCE AB We present a new compilation of the structural and stratigraphic evolution of the Tharsis region of Mars that incorporates recent advances in understanding its stratigraphy, and we introduce a lithospheric deformation model that can account for the observations. The first period in the formation of Tharsis occurred in Late Noachian/Early Hesperian time with the deposition of volcanic plains materials throughout the surrounding highlands (e.g., Lunae Planum) and on the Tharsis rise (which includes the giant volcanoes and surrounding, elevated lava fields). Extensive radial normal faulting occurred on the rise, locally extending outward at Valles Marineris and Tempe Terra, and concentric wrinkle ridges formed along the edge of the rise. This regional deformation appears to have been modulated by a global compressional stress field due to rapid planetary cooling and contraction. The second period occurred during the Late Hesperian/Amazonian with Tharsis volcanism centered on the rise and radial extensional deformation that extended from the center of the rise for thousands of kilometers. We propose a model in which the lithosphere beneath Tharsis consists of a thin elastic crustal cap on the rise that is mechanically detached from the strong upper mantle by a volcanically thickened, hot, weak lower crust. These layers merge into a single cooler, strong lithospheric layer around the edges of the rise. This model is capable of generating large extensional hoop stresses throughout much of the western hemisphere, in agreement with observations. The tectonic interpretation of the stresses predicted by this model requires the reconciliation of extensional strain within narrow grabens and compressional strain within wrinkle ridges with (1) processes in the deeper lithosphere, (2) the sparsity of strike-slip faults, and (3) other global or locally important stress fields. Stresses predicted by global models affect the entire thickness of the lithosphere, and they can be reconciled with narrow, closely spaced grabens that accommodate large amounts of extensional strain in the upper few kilometers of the lithosphere if the grabens are underlain and kinematically linked with dikes or other tension cracks, such as hydrofractures. Deeper levels of the lithosphere can accommodate this strain by elastic expansion if grabens are spaced far apart (many tens to hundreds of kilometers). Mechanical considerations suggest that deformation on faults beneath wrinkle ridges could extend through a significant thickness of the brittle crust. A number of factors, including stresses generated by the addition of overburden, intrusion of dikes, weakness of geologic materials under extension, and the laterally constrained nature of a single lithospheric plate, may have inhibited the formation of strike-slip faults on Mars. Stresses generated from the removal of overburden could have augmented planetwide wrinkle ridge formation during the Late Noachian/Early Hesperian and in Kasei Valles and western Chryse Planitia during the Early Amazonian. The nonuniform distribution of tectonic features around Tharsis can be understood in terms of the concentration of regional stresses and strain near weaker volcanotectonic centers. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TANAKA, KL (reprint author), US GEOL SURVEY,2255 GEMINI DR,FLAGSTAFF,AZ 86001, USA. NR 82 TC 110 Z9 110 U1 1 U2 3 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 AUG 25 PY 1991 VL 96 IS E1 BP 15617 EP 15633 DI 10.1029/91JE01194 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GH507 UT WOS:A1991GH50700006 ER PT J AU SCHENK, PM AF SCHENK, PM TI GANYMEDE AND CALLISTO - COMPLEX CRATER FORMATION AND PLANETARY CRUSTS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID IMPACT CRATERS; INTERNAL STRUCTURE; ICY SATELLITES; RELAXATION; URANUS; VISCOSITY; VOYAGER-1; SATURN; SYSTEM; MIMAS AB New depth/diameter (d/D), rim, and peak height and width measurements of fresh craters on Ganymede and Callisto are utilized to explore not only crater mechanics on icy satellites but intersatellite crater scaling and crustal properties and composition. Significant systematic differences in crater morphology on icy and rocky planets are confirmed. Simple-to-complex transition diameters on icy satellites, including Ganymede and Callisto, are much lower than those on rocky planets. Also, complex crater depths and rim heights on Ganymede and Callisto are inherently 60-70% shallower than lunar complex craters, despite similar surface gravity. Hence viscous relaxation is not as important as is generally assumed. Central peaks on most icy satellites are 1-2 km higher and considerably wider with respect to diameter than for similar-sized lunar craters. Terracing and rim slumping is also rare in these craters. Central peaks in craters in Ganymede (and Callisto) larger than approximately 15 km, however, are relatively small in both width and height, however, correlating with the occurrence of rim slumping. Thus central peak dimensions are an indirect indicator of the degree of rim slumping. Transition diameters for the occurrence of central peaks and rim slumps and for d/D curve inflections for icy satellites scale approximately with the inverse of surface gravity, except possibly at very low g. The transition diameters for central peaks and for rim slumping differ, however, by 5-15 km on Ganymede and Callisto but by 50 or more km on the smaller icy satellites. These large differences suggest that d/D curves on icy satellites are comprised of three segments of decreasing slope: one for smaller simple craters, a second for central peak craters, and a third for larger true complex craters with both central peaks and rim larger true complex craters with both central peaks and rim slumping. The shallow slopes of d/D curves on Ganymede and Callisto resemble that of the Moon, consistent with the occurrence of both central peaks and rim failure. The high slopes of d/D curves on the middle-sized icy satellites indicate that they are middle segments, consistent with the dominance of central peaks in those craters. Complex crater depths on icy satellites in general scale with the inverse of surface gravity. The depths of all the observed large basin-scale craters on these small satellites, when scaled to Ganymede gravity, are very similar to those of complex craters on Ganymede (and Callisto). These large craters, including Odysseus (425-km diameter) on Tethys, are probably true complex craters that have not undergone significant viscous relaxation. Ithaca Chasma on Tethys probably formed during the prompt collapse of the transient Odysseus crater. Crater morphology is clearly controlled by both gravity and by large variations in material properties (i.e., composition) and should be useful in constraining bulk crustal composition (i.e., ice-rock ratios). The similarity of various morphological transition diameters and complex crater depths on Ganymede and Callisto, two geophysically very similar but geologically divergent large icy satellites, indicates that the crusts of both bodies are dominated by water ice with only a "minor" rocky component. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 86 TC 50 Z9 50 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 AUG 25 PY 1991 VL 96 IS E1 BP 15635 EP 15664 DI 10.1029/91JE00932 PG 30 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GH507 UT WOS:A1991GH50700007 ER PT J AU CESS, RD POTTER, GL ZHANG, MH BLANCHET, JP CHALITA, S COLMAN, R DAZLICH, DA DELGENIO, AD DYMNIKOV, V GALIN, V JERRETT, D KEUP, E LACIS, AA LETREUT, H LIANG, XZ MAHFOUF, JF MCAVANEY, BJ MELESHKO, VP MITCHELL, JFB MORCRETTE, JJ NORRIS, PM RANDALL, DA RIKUS, L ROECKNER, E ROYER, JF SCHLESE, U SHEININ, DA SLINGO, JM SOKOLOV, AP TAYLOR, KE WASHINGTON, WM WETHERALD, RT YAGAI, I AF CESS, RD POTTER, GL ZHANG, MH BLANCHET, JP CHALITA, S COLMAN, R DAZLICH, DA DELGENIO, AD DYMNIKOV, V GALIN, V JERRETT, D KEUP, E LACIS, AA LETREUT, H LIANG, XZ MAHFOUF, JF MCAVANEY, BJ MELESHKO, VP MITCHELL, JFB MORCRETTE, JJ NORRIS, PM RANDALL, DA RIKUS, L ROECKNER, E ROYER, JF SCHLESE, U SHEININ, DA SLINGO, JM SOKOLOV, AP TAYLOR, KE WASHINGTON, WM WETHERALD, RT YAGAI, I TI INTERPRETATION OF SNOW-CLIMATE FEEDBACK AS PRODUCED BY 17 GENERAL-CIRCULATION MODELS SO SCIENCE LA English DT Article AB Snow feedback is expected to amplify global warming caused by increasing concentrations of atmospheric greenhouse gases. The conventional explanation is that a warmer Earth will have less snow cover, resulting in a darker planet that absorbs more solar radiation. An intercomparison of 17 general circulation models, for which perturbations of sea surface temperature were used as a surrogate climate change, suggests that this explanation is overly simplistic. The results instead indicate that additional amplification or moderation may be caused both by cloud interactions and longwave radiation. One measure of this net effect of snow feedback was found to differ markedly among the 17 climate models, ranging from weak negative feedback in some models to strong positive feedback in others. C1 UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. CANADIAN CLIMATE CTR,TORONTO M3H 574,ONTARIO,CANADA. LAB METEOROL DYNAM,F-75231 PARIS 05,FRANCE. BUR METEOROL RES CTR,MELBOURNE,VIC 3001,AUSTRALIA. COLORADO STATE UNIV,FT COLLINS,CO 80523. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. ACAD SCI USSR,DEPT NUMERICAL MATH,MOSCOW 119034,USSR. HADLEY CTR CLIMATE PREDICT & RES,METEOROL OFF,BRACKNELL RG12 2SZ,BERKS,ENGLAND. MAX PLANCK INST METEOROL,W-2000 HAMBURG 13,GERMANY. SUNY ALBANY,ALBANY,NY 12222. CTR NATL RECH MET,DIRECT METEOROL NAT,F-31057 TOULOUSE,FRANCE. LENINGRAD MAIN GEOPHYS OBSERV,LENINGRAD 194018,USSR. EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS,READING RG2 92X,BERKS,ENGLAND. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093. UNIV READING,READING RG6 2AU,ENGLAND. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. PRINCETON UNIV,NOAA,GEOPHYS FLUID DYNAM LAB,PRINCETON,NJ 08544. METEOROL RES INST,TSUKUBA,IBARAKI 305,JAPAN. RP CESS, RD (reprint author), SUNY STONY BROOK,INST TERR & PLANETARY ATMOSPHERES,STONY BROOK,NY 11794, USA. RI Taylor, Karl/F-7290-2011; Del Genio, Anthony/D-4663-2012; Lacis, Andrew/D-4658-2012; Randall, David/E-6113-2011; Norris, Peter/H-2008-2012 OI Taylor, Karl/0000-0002-6491-2135; Del Genio, Anthony/0000-0001-7450-1359; Randall, David/0000-0001-6935-4112; Norris, Peter/0000-0001-6807-9884 NR 7 TC 121 Z9 126 U1 4 U2 19 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 23 PY 1991 VL 253 IS 5022 BP 888 EP 892 DI 10.1126/science.253.5022.888 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GC152 UT WOS:A1991GC15200040 PM 17751825 ER PT J AU CHERCHNEFF, I BARKER, JR TIELENS, AGGM AF CHERCHNEFF, I BARKER, JR TIELENS, AGGM TI POLYCYCLIC AROMATIC HYDROCARBON OPTICAL-PROPERTIES AND CONTRIBUTION TO THE ACCELERATION OF STELLAR OUTFLOWS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, MOLECULES; STARS, CIRCUMSTELLAR SHELLS ID DIFFUSE INTERSTELLAR BANDS; CARBON STARS; CONDENSED AROMATICS; INFRARED-EMISSION; AMORPHOUS-CARBON; MASS-LOSS; DUST; VIBRATIONS; ENVELOPES; GRAINS AB The optical constants of four polycyclic aromatic hydrocarbon (PAH) molecules (benzene, pyrene, pentacene, and coronene) are determined from their measured laboratory absorption spectra. The Planck mean of the radiation pressure cross section is computed for each molecule and for amorphous carbon (AC) grains, and semiempirically estimated for large PAH molecules up to 400 carbon atoms. Assuming that PAHs are present in carbon-rich stellar outflows, the radiation pressure forces acting on them are calculated and compared with the radiation forces on AC particles. The results show that PAHs possess very different optical properties from AC grains. Small PAHs may experience an "inverse greenhouse" effect in the inner part of the envelope, as they decouple from the gas close to the photosphere. The radiation pressure force on PAHs is always much less than the force at work on AC grains, and PAH molecules do not affect significantly the dynamics of the outflow. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP CHERCHNEFF, I (reprint author), UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,SPACE PHYS RES LAB,ANN ARBOR,MI 48109, USA. RI Barker, John/F-5904-2012 OI Barker, John/0000-0001-9248-2470 NR 55 TC 32 Z9 32 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 AUG 20 PY 1991 VL 377 IS 2 BP 541 EP 552 DI 10.1086/170383 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA594 UT WOS:A1991GA59400019 ER PT J AU LOWENTHAL, JD HOGAN, CJ GREEN, RF CAULET, A WOODGATE, BE BROWN, L FOLTZ, CB AF LOWENTHAL, JD HOGAN, CJ GREEN, RF CAULET, A WOODGATE, BE BROWN, L FOLTZ, CB TI DISCOVERY OF A LY-ALPHA GALAXY NEAR A DAMPED LY-ALPHA ABSORBER AT Z = 2.3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; GALAXIES, FORMATION; QUASARS ID HIGH-REDSHIFT GALAXIES; STAR FORMATION; ABSORPTION SYSTEMS; METAL ENRICHMENT; DISK GALAXIES; PRIMEVAL GALAXIES; EMISSION; PHL-957; LIMITS; QSOS AB We report the detection of a galaxy associated with the damped Ly-alpha absorbing cloud seen at z = 2.309 toward the QSO PHL 957 (z(em) = 2.681). The galaxy was discovered in deep Fabry-Perot narrow-band CCD frames and was subsequently imaged spectroscopically. In addition to a strong but narrow Ly-alpha emission line (F(Ly-alpha) = 5.6 x 10(-16) ergs s-1 cm-2, FWHM approximately 700 km s-1) and weaker C IV and He II lines, the object shows continuum at V approximately 24, with a slope (in F-nu) rising slightly toward the red, similar to what is seen in high-redshift radio galaxies; however, the galaxy does not correspond to any known radio source in the literature. The detected emission lines and continuum are most easily interpreted as light from hot, recently formed stars, implying not only a sizable star formation rate (SFR greater-than-or-equal-to 5 M . yr-1) but also a scarcity of dust, which readily quenches Ly-alpha photons. The emission region appears to be marginally resolved spatially and is located 48" to the NW of the QSO, corresponding to a projected distance of 270h-1 kpc (for q0 = 0.1); the velocity difference with respect to the damped Ly-alpha cloud is approximately 350 km s-1. The spatial correlation of the absorbing cloud and the companion galaxy supports the interpretation of damped Ly-alpha clouds as objects fundamentally different from the lower column density Ly-alpha forest clouds, which show weak or no clustering. The absorption trough itself shows no Ly-alpha emission, extended or unresolved, in either the Fabry-Perot frames or in deep, moderate resolution (approximately 3 angstrom FWHM), two-dimensional spectra, down to a limiting flux (3-sigma) for an unresolved line of 2 x 10(-17) ergs s-1 cm-2, approximately 30 times fainter than the Ly-alpha flux detected from the companion galaxy. The lack of strong Ly-alpha emission from the absorbing cloud can be interpreted as evidence either for a low SFR or for heavy dust obscuration. C1 KITT PEAK NATL OBSERV,TUCSON,AZ 85726. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV ARIZONA,MULTIPLE MIRROR TELESCOPE OBSERV,TUCSON,AZ 85721. RP LOWENTHAL, JD (reprint author), UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721, USA. RI Woodgate, Bruce/D-2970-2012 NR 44 TC 68 Z9 68 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 AUG 20 PY 1991 VL 377 IS 2 BP L73 EP & DI 10.1086/186120 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA595 UT WOS:A1991GA59500003 ER PT J AU LOPEZ, RE PASSI, RM AF LOPEZ, RE PASSI, RM TI SIMULATIONS IN SITE ERROR ESTIMATION FOR DIRECTION FINDERS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The performance of an algorithm for the recovery of site-specific errors of direction finder (DF) networks is tested under controlled simulated conditions. The simulations show that the algorithm has some inherent shortcomings for the recovery of site errors from the measured azimuth data. These limitations are fundamental to the problem of site error estimation using azimuth information. Several ways for resolving or ameliorating these basic complications are tested by means of simulations. From these it appears that for the effective implementation of the site error determination algorithm, one should design the networks with at least four DFs, improve the alignment of the antennas, and increase the gain of the DFs as much as it is compatible with other operational requirements. The use of a nonzero initial estimate of the site errors when working with data from networks of four or more DFs also improves the accuracy of the site error recovery. Even for networks of three DFs, reasonable site error corrections could be obtained if the antennas could be well aligned. C1 STENNIS SPACE CTR, INST NAVAL OCEANOG, BAY ST LOUIS, MS USA. RP LOPEZ, RE (reprint author), NOAA, NATL SEVERE STORMS LAB, 325 BROADWAY, BOULDER, CO 80303 USA. NR 9 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1991 VL 96 IS D8 BP 15287 EP 15296 DI 10.1029/91JD01398 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GC314 UT WOS:A1991GC31400004 ER PT J AU KANAKIDOU, M SINGH, HB VALENTIN, KM CRUTZEN, PJ AF KANAKIDOU, M SINGH, HB VALENTIN, KM CRUTZEN, PJ TI A 2-DIMENSIONAL STUDY OF ETHANE AND PROPANE OXIDATION IN THE TROPOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PEROXYACETYL NITRATE PAN; NON-METHANE HYDROCARBONS; NONMETHANE HYDROCARBONS; ATMOSPHERIC CHEMISTRY; NITROGEN-OXIDES; C2-C5 HYDROCARBONS; REACTIVE NITROGEN; ORGANIC NITRATES; OZONE PRODUCTION; QUANTUM YIELDS AB The oxidation chemistry of ethane (C2H6) and propane (C3H8) in the troposphere was studied using a global two-dimensional model, adopting observed surface volume mixing ratios of C2H6 and C3H8 as a function of latitude and season. From the calculated distribution of OH, C2H6, and C3H8 the source strengths, which compensate the chemical loss of these hydrocarbons in the atmosphere, are estimated at 16 Tg C2H6/a and 23 Tg C3H8/a. Uncertainties involved in the calculations are discussed. The resulting seasonal and latitudinal distribution of various organic compounds, such as acetaldehyde, acetone, peroxyacetyl nitrate (PAN), peroxypropyl nitrate (PPN), and alkyl nitrates were derived. The contribution of various nitrogen species to the unidentified NO(y) observed during measurement campaigns was examined. C2 - C3 alkyl nitrates and HNO4 formed at mixing ratios of a few tens of pptv could account only for some of the unidentified NO(y). PAN is calculated to be the most abundant organic nitrate, with mixing ratios exceeding 100 pptv at mid-latitudes to high latitudes in spring in the northern hemisphere. These values are low compared to observations, however. Regionally, up to 10 times more odd nitrogen may be transported in the form of PAN than NO(x). The influence of C2H6 and C3H8 chemistry on calculated mean tropospheric NO(x) mixing ratios and, subsequently, on O3 and OH concentrations is limited. Therefore major effects on global O3 and OH concentrations must be due to PAN formation in the low troposphere from NO(x) and reactive hydrocarbons other than C2H6 and C3H8. Such hydrocarbons are required to explain the observed high PAN mixing ratios. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP KANAKIDOU, M (reprint author), MAX PLANCK INST CHEM, DIV ATMOSPHER CHEM, POB 3060, W-6500 MAINZ, GERMANY. RI Kanakidou, Maria/D-7882-2012; Crutzen, Paul/F-6044-2012 OI Kanakidou, Maria/0000-0002-1724-9692; NR 102 TC 107 Z9 108 U1 1 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1991 VL 96 IS D8 BP 15395 EP 15413 DI 10.1029/91JD01345 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GC314 UT WOS:A1991GC31400012 ER PT J AU DAVIDSON, EA VITOUSEK, PM MATSON, PA RILEY, R GARCIAMENDEZ, G MAASS, JM AF DAVIDSON, EA VITOUSEK, PM MATSON, PA RILEY, R GARCIAMENDEZ, G MAASS, JM TI SOIL EMISSIONS OF NITRIC-OXIDE IN A SEASONALLY DRY TROPICAL FOREST OF MEXICO SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NO; TROPOSPHERE; CHEMISTRY; JALISCO; TRENDS AB Soil emissions of NO were measured at the Chamela Biological Station, Mexico, using soil covers and a field apparatus for NO detection based on CrO3 conversion of NO to NO2 and detection of NO2 by chemiluminescence with Luminol. Mean NO fluxes from forest soils ranged from 0.14 to 0.52 ng NO-N cm-2 hr-1 during the dry season and from 0.73 to 1.27 ng NO-N cm-2 hr-1 during the wet season. A fertilized floodplain pasture exhibited higher fluxes, but an unfertilized upland pasture, which represents the fastest growing land use in the region, had flux rates similar to the forest sites. Wetting experiments at the end of the dry season caused large pulses of NO flux, equaling 10% to 20% of the estimated annual NO emissions of 0.5-1.0 kg N ha-1 from the forest sites. Absence of a forest canopy during the dry season and the first wet season rain probably results in substantial NO(x) export from the forest system that may be important to regional atmospheric chemical processes. Wetting experiments during the wet season and a natural rain event had little or no stimulatory effect on NO flux rates. C1 NASA, AMES RES CTR, ECOSYST SCI & TECHNOL BRANCH, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, DEPT BIOL, STANFORD, CA 94305 USA. NATL AUTONOMOUS UNIV MEXICO, CTR ECOL, MEXICO CITY 04510, DF, MEXICO. RI Davidson, Eric/K-4984-2013 OI Davidson, Eric/0000-0002-8525-8697 NR 25 TC 115 Z9 116 U1 1 U2 13 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1991 VL 96 IS D8 BP 15439 EP 15445 DI 10.1029/91JD01476 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GC314 UT WOS:A1991GC31400015 ER PT J AU ZANDER, R RINSLAND, CP DEMOULIN, P AF ZANDER, R RINSLAND, CP DEMOULIN, P TI INFRARED SPECTROSCOPIC MEASUREMENTS OF THE VERTICAL COLUMN ABUNDANCE OF SULFUR-HEXAFLUORIDE, SF6, FROM THE GROUND SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LOWER STRATOSPHERE; LINE PARAMETERS; CONSTANTS; SPECTRA; TRENDS; GASES; SINKS; BAND AB The unresolved upsilon-3 band Q branch of sulfur hexafluoride, SF6, at 947.9 cm-1 has been identified and quantitatively analyzed in series of high-quality infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, and at the National Solar Observatory facility on Kitt Peak in Arizona. Series of monthly mean total vertical column abundances of SF6 above both stations, deduced from that feature with line-by-line nonlinear least squares fitting methods, are reported over the time intervals from June 1986 to June 1990 for the Jungfraujoch and from March 1981 to June 1990 for Kitt Peak. Assuming an exponential growth model for fitting these series of measurements, it is found that the vertical column abundances have increased at mean rates of 6.9 +/- 2.8%/yr above the Jungfraujoch (calculated columns of 2.99 x 10(13) molecules/cm2 in June 1986 and 3.94 x 10(13) molecules/cm2 in June 1990) and 6.6 +/- 7.2%/yr above Kitt Peak (calculated columns equal to 2.97 x 10(13) molecules/cm2 in June 1981 and 5.38 x 10(13) molecules/cm2 in June 1990), the uncertainties corresponding to 2 sigma confidence levels. These results are further discussed within the context of variability and compared with previously published measurements. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. CALTECH, JET PROP LAB, ATMOS COMP FACIL, PASADENA, CA 91109 USA. RP ZANDER, R (reprint author), STATE UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. NR 33 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1991 VL 96 IS D8 BP 15447 EP 15454 DI 10.1029/91JD01214 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GC314 UT WOS:A1991GC31400016 ER PT J AU RINSLAND, CP LEVINE, JS GOLDMAN, A SZE, ND KO, MKW JOHNSON, DW AF RINSLAND, CP LEVINE, JS GOLDMAN, A SZE, ND KO, MKW JOHNSON, DW TI INFRARED MEASUREMENTS OF HF AND HCL TOTAL COLUMN ABUNDANCES ABOVE KITT PEAK, 1977-1990 - SEASONAL CYCLES, LONG-TERM INCREASES, AND COMPARISONS WITH MODEL-CALCULATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIMULTANEOUS SPECTROSCOPIC MEASUREMENTS; STRATOSPHERIC HYDROGEN-CHLORIDE; FOURIER-TRANSFORM SPECTROSCOPY; TWO-DIMENSIONAL MODEL; TRACE GASES; SOLAR SPECTRA; AIRBORNE MEASUREMENTS; VERTICAL DISTRIBUTION; JUNGFRAUJOCH STATION; METHYL-CHLORIDE AB Series of high-resolution (approximately 0.01 cm-1) solar absorption spectra recorded with the McMath Fourier transform spectrometer on Kitt Peak (altitude 2.09 km, 31.9-degrees-N, 111.6-degrees-W) have been analyzed to deduce total column amounts of HF on 93 different days and HCl on 35 different days between May 1977 and June 1990. The results are based on the analysis of the HF and H Cl-35 (1-0) vibration-rotation band R(1) lines which are located at 4038.9625 and 2925.8970 cm-1, respectively. All of the data were analyzed using a multilayer, nonlinear least squares spectral fitting procedure and a consistent set of spectroscopic line parameters. The results indicate a rapid increase in total HF and a more gradual increase in total HCl with both trends superimposed on short-term variability. In addition, the total columns of both gases undergo a seasonal cycle with an early spring maximum and an early fall minimum, with peak-to-peak amplitudes equal to 25% for HF and 13% for HCl. In the case of HF, the changes over the 13 years of measurement are sufficiently large to determine that a better fit is obtained assuming a linear rather than an exponential increase with time. For HCl, linear and exponential models fit the data equally well. Referenced to calendar year 1981.0 and assuming a sinusoidal seasonal cycle superimposed on a linear total column increase with time, HF and HCl increase rates of (10.9 +/- 1.1)% yr-1 and (5.1 +/- 0.7)% yr-1 and total columns of (3.17 +/- 0.11) x 10(14) and (1.92 +/- 0.06) x 10(15) molecules cm-2 (2 sigma) are derived, respectively; the corresponding best fit mean exponential increase rates are equal to (7.6 +/- 0.6)% yr-1 and (4.2 +/- 0.5)% yr-1 (2 sigma). Over the 13-year observing period, the HF and HCl total columns increased by factors of 3.2 and 1.8, respectively. Based on HF and HCl total columns deduced from measurements on the same day, the HF/HCl total columns ratio increased from 0.14 in May 1977 to 0.23 in June 1990. Short-term temporal variations in the HF and HCl total columns are highly correlated; these fluctuations are believed to be caused by dynamical variability in the lower stratosphere. The results of this investigation are compared with previously reported measurements and with time-dependent, two-dimensional model calculations of HF and HCl total columns based on emission histories and photo-oxidation rates for the source molecules. C1 UNIV DENVER, DEPT PHYS, DENVER, CO 80210 USA. AER INC, CAMBRIDGE, MA USA. RP RINSLAND, CP (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL STOP 401A, HAMPTON, VA 23665 USA. NR 85 TC 62 Z9 62 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1991 VL 96 IS D8 BP 15523 EP 15540 DI 10.1029/91JD01249 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GC314 UT WOS:A1991GC31400022 PM 11538646 ER PT J AU HUNT, BD FOOTE, MC BAJUK, LJ AF HUNT, BD FOOTE, MC BAJUK, LJ TI ALL HIGH-TC EDGE-GEOMETRY WEAK LINKS UTILIZING Y-BA-CU-O BARRIER LAYERS SO APPLIED PHYSICS LETTERS LA English DT Article ID YBA2CU3O7-DELTA; FABRICATION; JUNCTIONS AB High quality YBa2Cu3O7-x/normal-metal/YBa2Cu3O7-x edge-geometry weak links have been fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25-100 angstrom thick barrier layers exhibit current-voltage characteristics consistent with the resistively shunted junction model, with strong microwave and magnetic field response at temperatures up to 85 K. The critical currents vary exponentially with barrier thickness, and the resistances scale linearly with Y-Ba-Cu-O interlayer thickness and device area, indicating good barrier uniformity, with an effective normal metal coherence length of 20 angstrom. RP HUNT, BD (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 19 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 AUG 19 PY 1991 VL 59 IS 8 BP 982 EP 984 DI 10.1063/1.106321 PG 3 WC Physics, Applied SC Physics GA GB296 UT WOS:A1991GB29600034 ER PT J AU THROWER, FP SHORT, JW AF THROWER, FP SHORT, JW TI ACCUMULATION AND PERSISTENCE OF TRI-NORMAL-BUTYLTIN IN PINK AND CHUM SALMON FRY CULTURED IN MARINE NET-PENS SO AQUACULTURE LA English DT Article ID CHINOOK SALMON AB Pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta) fry cultured in tri-n-butyltin (TBT) treated marine net-pens for 20-68 days were tested just prior to release into the ocean to determine whether TBT contamination had occurred and, if so, to what extent. Exposed fry contained 0.2-7.3-mu-g TBT/g fish at the time of release; TBT concentrations varied substantially among the net-pen populations. Unusually high mortalities or poor growth rates were not observed. TBT was not detected in the returning adults. RP THROWER, FP (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 7 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0044-8486 J9 AQUACULTURE JI Aquaculture PD AUG 15 PY 1991 VL 96 IS 3-4 BP 233 EP 239 DI 10.1016/0044-8486(91)90153-X PG 7 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA GC371 UT WOS:A1991GC37100004 ER PT J AU NANCE, JM AF NANCE, JM TI EFFECTS OF OIL GAS-FIELD PRODUCED WATER ON THE MACROBENTHIC COMMUNITY IN A SMALL GRADIENT ESTUARY SO HYDROBIOLOGIA LA English DT Article DE PRODUCED WATER; HYDROCARBONS; OIL POLLUTION; MACROBENTHOS; ESTUARINE ID BUCCANEER OILFIELD; SEDIMENTS; ALKANES AB Little is known about how climatic events (i.e., drought) inhibit or enhance movement of petroleum hydrocarbon laden sediments in estuarine systems and how this in turn effects the macrobenthic populations exposed to these sediments. Seventeen collection stations were established and monitored at New Bayou, Texas, a small gradient estuary which receives petroleum products via oil/gas field produced water discharge. Hydrographic, geologic and biotic samples were taken monthly from each station during a period of reduced rainfall. Both temperature and dissolved oxygen data taken during the study followed patterns typical for the area. Salinity values increased into the polyhaline range at near-bay stations during the reduced rain period, while upper bayou stations remained within the oligohaline range. Sediment grain sizes along the bayou were generally in the silty-clay range. Sediment hydrocarbon concentrations were highest (11.4 mg g-1 dry sediment) around the produced water discharge site and lowest at near-bay stations (0.2 mg g-1 dry sediment). Ninety-six macrobenthic species were collected during the study. General effects from produced water discharge on macrobenthic populations followed the classical pattern outlined by other research in shallow bay systems. A sediment hydrocarbon concentration of 2.5 mg g-1 dry sediment was found to reflect the average value needed to depress population abundances. Both abundance and diversity values were lowest at central stations near the discharge site. This zone of depressed macrobenthic populations extended from the discharge site at least 107 m downstream and 46 m upstream. The zone of stimulated macrobenthic populations occurred 1486 m downstream and 381 m upstream from the discharge site. RP NANCE, JM (reprint author), NATL MARINE FISHERIES SERV,SE FISHERIES CTR,GALVESTON LAB,4700 AVE U,GALVESTON,TX 77551, USA. NR 55 TC 7 Z9 7 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0018-8158 J9 HYDROBIOLOGIA JI Hydrobiologia PD AUG 15 PY 1991 VL 220 IS 3 BP 189 EP 204 DI 10.1007/BF00006575 PG 16 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA GK310 UT WOS:A1991GK31000002 ER PT J AU CODY, RJ MORALEJO, C ALLEN, JE AF CODY, RJ MORALEJO, C ALLEN, JE TI PHOTODISSOCIATION OF THE HYDROXYL RADICAL (OH) AT 157 NM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID RADIATIVE LIFETIMES; PHOTO-DISSOCIATION; STATES; COMETS; OD AB The photodissociation of the OH radical was studied at 157 nm via the detection of the product H atoms with the resonance fluorescence technique. OH radicals were produced in a fast flow cell from the reaction between H and NO2 and subsequently photodissociated by an excimer laser operating on the F2 emission. The quantum yield for photodissociation of OH was measured to be 1.10 +/- 0.28. The photodissociation cross section was calculated to be 6.6 x 10(-18) cm2 (+/- 25%) which is in good agreement with the work of Nee and Lee (Ref. 8). RP CODY, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,GREENBELT,MD 20771, USA. RI Cody, Regina/D-5996-2013 NR 21 TC 6 Z9 6 U1 0 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 AUG 15 PY 1991 VL 95 IS 4 BP 2491 EP 2496 DI 10.1063/1.460953 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA GA108 UT WOS:A1991GA10800028 ER PT J AU DYALL, KG TAYLOR, PR FAEGRI, K PARTRIDGE, H AF DYALL, KG TAYLOR, PR FAEGRI, K PARTRIDGE, H TI ALL-ELECTRON MOLECULAR DIRAC-HARTREE-FOCK CALCULATIONS - THE GROUP-IV TETRAHYDRIDES CH4, SIH4, GEH4, SNH4, AND PBH4 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SELF-CONSISTENT-FIELD; EFFECTIVE CORE POTENTIALS; RELATIVISTIC EFFECTIVE POTENTIALS; SPIN-ORBIT OPERATORS; GAUSSIAN-BASIS SETS; MAIN-GROUP ELEMENTS; RAMAN GAS SPECTRA; MINIMUM BASIS SET; ALGEBRAIC-APPROXIMATION; BREIT INTERACTION AB We describe a basis-set-expansion Dirac-Hartree-Fock program for molecules. Bond lengths and harmonic frequencies are presented for the ground states of the group IV tetrahydrides CH4, SiH4, GeH4, SnH4, and PbH4. The results are compared with relativistic effective core potential (RECP) calculations, first-order perturbation theory (PT) calculations and with experimental data. The bond lengths are well predicted by first-order perturbation theory for all molecules, but none of the sets of RECPs considered provides a consistent prediction. Perturbation theory overestimates the relativistic correction to the harmonic frequencies; the RECP calculations underestimate the correction. C1 ELORET INST, PALO ALTO, CA 94303 USA. UNIV OSLO, DEPT CHEM, N-0315 OSLO 3, NORWAY. RP NASA, AMES RES CTR, MS RTC 230-3, MOFFETT FIELD, CA 94035 USA. NR 103 TC 157 Z9 157 U1 0 U2 8 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD AUG 15 PY 1991 VL 95 IS 4 BP 2583 EP 2594 DI 10.1063/1.460911 PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA GA108 UT WOS:A1991GA10800039 ER PT J AU RAMP, SR GARWOOD, RW DAVIS, CO SNOW, RL AF RAMP, SR GARWOOD, RW DAVIS, CO SNOW, RL TI SURFACE HEATING AND PATCHINESS IN THE COASTAL OCEAN OFF CENTRAL CALIFORNIA DURING A WIND RELAXATION EVENT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TURBULENCE CLOSURE MODELS; PLANETARY BOUNDARY-LAYERS; MIXED LAYER; IRRADIANCE; HIERARCHY; SEA AB The difference between the temperature of the ocean at 4-cm and 2-m depth was continuously monitored during a cruise to the coastal transition zone off Point Arena, California (38-degrees-58'N, 123-degrees-45'W), during June 1987. The two temperatures were coincident most of the time but diverged during one nearshore leg of the cruise where large temperature differences (DELTA-T) of up to 4.7-degrees-C were observed between the 4-cm and 2-m sensors, in areas which were separated by regions where the two temperatures were coincident as usual. The spatial scale of this "patchy" thermal structure was about 5-10 km. The Naval Postgraduate School mixed layer model (Garwood, 1977) was used to simulate the near surface stratification when forced by the observed wind stress, surface heating, and optical clarity of the water. The model produced a thin strongly stratified surface layer at stations where exceptionally high turbidity was observed but did not produce such features otherwise. This simple model could not explain the horizontal patchiness in the thermal structure, which was likely due to patchiness in the near-surface chlorophyll distributions or to submesoscale variability of the surface wind stress. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RAMP, SR (reprint author), NAVAL POST GRAD SCH,DEPT OCEANOG,MONTEREY,CA 93943, USA. NR 26 TC 18 Z9 19 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 AUG 15 PY 1991 VL 96 IS C8 BP 14947 EP 14957 DI 10.1029/91JC01140 PG 11 WC Oceanography SC Oceanography GA GB337 UT WOS:A1991GB33700018 ER PT J AU RIENECKER, MM MILLER, RN AF RIENECKER, MM MILLER, RN TI OCEAN DATA ASSIMILATION USING OPTIMAL INTERPOLATION WITH A QUASI-GEOSTROPHIC MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ALTIMETER EDDY FIELDS; SEA-LEVEL; DYNAMICAL INTERPOLATION; CALIFORNIA CURRENT; KALMAN FILTER; PREDICTABILITY; CIRCULATION; RESOLUTION; ATLANTIC; WINDS AB Optimal interpolation (OI) has been used to produce analyses of quasi-geostrophic (QG) stream function over a 59-day period in a 150-km-square domain off northern California. Hydrographic observations acquired over five surveys, each of about 6 days' duration, were assimilated into a QG open boundary ocean model. Since the true forecast error covariance function required for the OI is unknown, assimilation experiments were conducted separately for individual surveys to investigate the sensitivity of the OI analyses to parameters defining the decorrelation scale of an assumed error covariance function. The analyses were intercompared through dynamical hindcasts between surveys, since there were too few independent data for other verification of the various analyses. For the hindcasts, the QG model was initialized with an analysis for one survey and then integrated according to boundary data supplied by the corresponding analysis for the next survey. Two sets of such hindcasts were conducted, since there were only three statistically independent realizations of the stream function field for the entire observing period. For the irregular sampling strategy of the first half of the observing period, the best hindcast was obtained using the smooth analyses produced with assumed error decorrelation scales identical to those of the observed stream function (about 80 km): the root mean square difference between the hindcast stream function and the final analysis was only 23% of the observation standard deviation. The best hindcast (with a 31% error) for the second half of the observing period was obtained using an initial analysis based on an 80-km decorrelation scale and a final analysis based on a 40-km decorrelation scale. The change in decorrelation scale was apparently associated with a change in sampling strategy and the importance of the resolution of small-scale vorticity input across the open boundary. The last survey used a regular sampling scheme with good coverage (about 20-km resolution) of the entire domain so that smaller-scale features were resolved by the data. The earlier surveys used a coarser (about 75 km) sampling resolution, and smaller-scale features that were not well-resolved could not be inferred correctly even with short error covariance scales. During the hindcast integrations, the dynamical model effectively filtered the stream function fields to reduce differences between the various initial fields. Differences between the analyses near inflow boundary points ultimately dominated the differences between dynamical hindcasts. Analyses for the entire 59-day observing period of the five independent surveys were produced using continuous assimilation. A modified form of OI in which the forecast error variances were updated according to the analysis error variances and an assumed model error growth rate was also used, allowing the OI to retain information about prior assimilation. The analyses using the updated variances were spatially smoother and often in better agreement with the observations than the OI analyses using constant variances. The two sets of OI analyses were temporally smoother than the fields from statistical objective analysis (OA) and in good agreement with the only independent data available for comparison. Unfortunately, the limiting factor in the validation of the assimilation methodology remains the paucity of observations. C1 OREGON STATE UNIV,COLL OCEANOG,CORVALLIS,OR 97331. RP RIENECKER, MM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771, USA. NR 29 TC 12 Z9 12 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 AUG 15 PY 1991 VL 96 IS C8 BP 15093 EP 15103 DI 10.1029/91JC01530 PG 11 WC Oceanography SC Oceanography GA GB337 UT WOS:A1991GB33700026 ER PT J AU WEATHERLY, JW WALSH, JE ZWALLY, HJ AF WEATHERLY, JW WALSH, JE ZWALLY, HJ TI ANTARCTIC SEA ICE VARIATIONS AND SEASONAL AIR-TEMPERATURE RELATIONSHIPS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TRENDS AB Monthly Antarctic station temperatures are used in conjunction with grids of sea ice coverage in order to evaluate the temporal trends and the strength of associations between the two variables at lags of up to several seasons. Over the 30-year period 1958-1987 the trends of temperature are positive in all seasons. However, for the 15 years (1973-1987) for which ice data are available, the trends of temperature are predominantly positive only in winter and summer. The trends are most strongly positive over the Antarctic Peninsula. The spatially aggregated trend of temperature for this latter period is small but positive, while the corresponding trend of ice coverage is small but negative. Regional trends of both variables are larger. Cross correlations between concurrent anomalies of the two variables are negative over most of the continent and are strongest over the Antarctic Peninsula, especially in winter. Lag correlations between seasonal anomalies of the two variables are generally stronger with ice lagging the summer temperatures and with ice leading the winter temperatures. The implication is that summer temperatures predispose the near-surface waters to above- or below-normal ice coverage in the following autumn and winter. The conclusions show little dependence on the choice of the sea ice data source or of the measure of sea ice (extent or areal coverage), but they do depend considerably on the method by which the data are geographically aggregated. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. RP WEATHERLY, JW (reprint author), UNIV ILLINOIS,DEPT ATMOSPHER SCI,105 S GREGORY AVE,URBANA,IL 61801, USA. NR 14 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-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 1991 VL 96 IS C8 BP 15119 EP 15130 DI 10.1029/91JC01432 PG 12 WC Oceanography SC Oceanography GA GB337 UT WOS:A1991GB33700028 ER PT J AU RAU, GH TAKAHASHI, T DESMARAIS, DJ SULLIVAN, CW AF RAU, GH TAKAHASHI, T DESMARAIS, DJ SULLIVAN, CW TI PARTICULATE ORGANIC-MATTER DELTA-C-13 VARIATIONS ACROSS THE DRAKE PASSAGE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID PHYTOPLANKTON DISTRIBUTION; MARINE-PHYTOPLANKTON; CARBON; PLANKTON; OCEANS; C-13; FRACTIONATION; PRODUCTIVITY; SECTOR; CO2 AB A 7 parts per thousand gradient in the delta-C-13 of suspended particulate organic matter (POM) was observed in samples taken during two transects across the Drake Passage during March 1986. This POM delta-C-13 transition from -23.2 parts per thousand at 53.3-degrees-S to values as low as -30.3 parts per thousand at > 62-degrees-S does not track previously reported abrupt changes in water chemistry and plankton species composition associated with the Polar Front Zone that resides at approximately 58-degrees-S in this region. Also, the north-south isotopic trend is not accompanied by significant changes in POM carbon or nitrogen concentrations, or in POM C/N. Differences in plankton standing crop or biochemistry (e.g., lipid content) therefore do not appear responsible for the isotopic trends observed. The latitudinal change in POM delta-C-13 is, however, highly correlated with water temperature and with the calculated concentration of CO2(aq) at equilibrium with atmospheric CO2. These observations are consistent with the hypothesis that [CO2(aq)] significantly influences POM delta-C-13 in ocean surface waters. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV SO CALIF,DEPT GEOL SCI,LOS ANGELES,CA 90089. COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. RP RAU, GH (reprint author), UNIV CALIF SANTA CRUZ,INST MARINE SCI,SANTA CRUZ,CA 95064, USA. FU NCCDPHP CDC HHS [DPP 8613981]; NCIPC CDC HHS [OCE 9017773, OCE 9012172] NR 21 TC 52 Z9 53 U1 0 U2 10 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 AUG 15 PY 1991 VL 96 IS C8 BP 15131 EP 15135 DI 10.1029/91JC01253 PG 5 WC Oceanography SC Oceanography GA GB337 UT WOS:A1991GB33700029 PM 11538489 ER PT J AU GOLDEN, RL GRIMANI, C HULL, R KIMBELL, BL PARK, R STEPHENS, SA STOCHAJ, S WEBBER, WR BASINI, G BONAVIRI, E BRANCACCIO, FM RICCI, M ORMES, JF SEO, ES STREITMATTER, RE CELLETTI, F SPILLANTINI, P CODINO, A MENICHELLI, M SALVATORI, I BONGIORNO, F BIDOLI, V BUCCHERI, A DEPASCALE, MP MORSELLI, A PICOZZA, P AF GOLDEN, RL GRIMANI, C HULL, R KIMBELL, BL PARK, R STEPHENS, SA STOCHAJ, S WEBBER, WR BASINI, G BONAVIRI, E BRANCACCIO, FM RICCI, M ORMES, JF SEO, ES STREITMATTER, RE CELLETTI, F SPILLANTINI, P CODINO, A MENICHELLI, M SALVATORI, I BONGIORNO, F BIDOLI, V BUCCHERI, A DEPASCALE, MP MORSELLI, A PICOZZA, P TI PERFORMANCE OF A BALLOON-BORNE MAGNET SPECTROMETER FOR COSMIC-RAY STUDIES SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article AB This paper summarizes the performance characteristics of the balloon-borne magnet spectrometer operated by New Mexico State University's Particle Astrophysics Laboratory. Particular emphasis has been placed on the rigidity resolution, including both random and systematic errors of the magnetic spectrometer system. Measurement of the performance characteristics has been greatly enhanced through the use of an imaging calorimeter as an independent aid in the identification of cosmic rays. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV FLORENCE,I-50121 FLORENCE,ITALY. UNIV PERUGIA,I-06100 PERUGIA,ITALY. UNIV ROMA LA SAPIENZA 1,ROME,ITALY. UNIV TOR VERGATA,ROME,ITALY. RP GOLDEN, RL (reprint author), NEW MEXICO STATE UNIV,PARTICLE ASTROPHYS LAB,LAS CRUCES,NM 88003, USA. RI Morselli, Aldo/G-6769-2011; OI Morselli, Aldo/0000-0002-7704-9553; Picozza, Piergiorgio/0000-0002-7986-3321; Seo, Eun-Suk/0000-0001-8682-805X NR 15 TC 47 Z9 47 U1 0 U2 0 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 AUG 15 PY 1991 VL 306 IS 1-2 BP 366 EP 377 DI 10.1016/0168-9002(91)90343-O PG 12 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA GC017 UT WOS:A1991GC01700049 ER PT J AU ZANG, TA AF ZANG, TA TI NUMERICAL-SIMULATION OF THE DYNAMICS OF TURBULENT BOUNDARY-LAYERS - PERSPECTIVES OF A TRANSITION SIMULATOR SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article ID CHANNEL FLOW; 3-DIMENSIONAL DEVELOPMENT; WAVES AB The current and prospective capabilities of numerical simulations of turbulent boundary layers are discussed. The stringent resolution requirements for resolving instantaneous structures and dynamics (rather than just for producing statistics) are emphasized. Improvements and alternatives to the prevailing simulation methodology are proposed. RP ZANG, TA (reprint author), NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 35 TC 25 Z9 26 U1 1 U2 1 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON, ENGLAND SW1Y 5AG J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD AUG 15 PY 1991 VL 336 IS 1641 BP 95 EP 102 DI 10.1098/rsta.1991.0068 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GB617 UT WOS:A1991GB61700002 ER PT J AU SASAKI, M YOKOYAMA, J AF SASAKI, M YOKOYAMA, J TI INITIAL CONDITION FOR THE MINIMAL ISOCURVATURE SCENARIO SO PHYSICAL REVIEW D LA English DT Article ID COLD DARK MATTER; LARGE-SCALE STRUCTURE; POWER-LAW INFLATION; PRIMORDIAL NUCLEOSYNTHESIS; PHASE-TRANSITION; UNIVERSE; FLUCTUATIONS; PERTURBATIONS; COSMOLOGY; DENSITY AB We derive a proper expression for the power spectrum of baryon-number fluctuations arising from decay of a heavy Majorana lepton with space-dependent CP violation due to a spatially varying Majoron field. The spectrum is explicitly calculated in a power-law inflation model and found to be almost scale invariant on small scales and white noise on large scales. Under reasonable assumptions, we present a natural particle-physics model which provides an appropriate initial condition for the minimal isocurvature scenario of large-scale structure formation. C1 UNIV TOKYO,FAC SCI,DEPT PHYS,TOKYO 113,JAPAN. FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP SASAKI, M (reprint author), KYOTO UNIV,UJI RES CTR,YUKAWA INST THEORET PHYS,UJI,KYOTO 611,JAPAN. OI Sasaki, Misao/0000-0001-5924-0664 NR 57 TC 17 Z9 17 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 AUG 15 PY 1991 VL 44 IS 4 BP 970 EP 979 DI 10.1103/PhysRevD.44.970 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA GB377 UT WOS:A1991GB37700007 ER PT J AU ROULET, E AF ROULET, E TI MIKHEYEV-SMIRNOV-WOLFENSTEIN EFFECT WITH FLAVOR-CHANGING NEUTRINO INTERACTIONS SO PHYSICAL REVIEW D LA English DT Note ID R-PARITY; STANDARD MODEL; OSCILLATIONS; SUPERSYMMETRY; MATTER; ENHANCEMENT; PHYSICS AB We consider the effect that flavor-nondiagonal neutrino interactions with matter have on the resonant v oscillations. It is shown that, even in the absence of v mixing in a vacuum, an efficient conversion of the electron neutrinos from the Sun to another v flavor can result if the strength of this interaction is approximately 10(-2)G(F). We show how this can be implemented in the minimal supersymmetric standard model with R-parity breaking. Here, the L-violating couplings induce neutrino masses, mixings, and the flavor-nondiagonal neutrino interactions that can provide a Mikheyev-Smirnov-Wolfenstein-like solution to the solar-neutrino problem even for negligible vacuum mixings. RP ROULET, E (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,POB 500,BATAVIA,IL 60510, USA. NR 25 TC 101 Z9 101 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 AUG 15 PY 1991 VL 44 IS 4 BP R935 EP R938 DI 10.1103/PhysRevD.44.R935 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA GB377 UT WOS:A1991GB37700001 ER PT J AU OLIVE, KA SCHRAMM, DN THOMAS, D WALKER, TP AF OLIVE, KA SCHRAMM, DN THOMAS, D WALKER, TP TI NEUTRINO DEGENERACY AND COSMOLOGICAL NUCLEOSYNTHESIS, REVISITED SO PHYSICS LETTERS B LA English DT Article ID BIG-BANG NUCLEOSYNTHESIS; PRIMORDIAL NUCLEOSYNTHESIS; LEPTON; ASYMMETRY; UNIVERSE; RATES AB A reexamination of the effects of non-zero neutrino degeneracies on big bang nucleosynthesis is made. As previously noted, non-trivial alterations of the standard model conclusions can only be induced if excess lepton numbers L(i), comparable to photon number densities n-gamma, are assumed (where n-gamma approximately 3 x 10(9)n(b)). Furthermore, the required lepton number densities (L(i)n-gamma) must be different for nu-e than for nu-mu and nu-tau. It is shown that this loophole in the standard model of nucleosynthesis is robust and will not vanish as abundance and reaction rate determinations improve. However, it is also argued that theoretically \L(e)\ approximately \L-mu\ approximately \L-tau\ approximately n(b) << n-gamma which would preclude this loophole in standard unified models. C1 UNIV CHICAGO,CHICAGO,IL 60637. NASA,FERMI NATL ACCELERATOR LAB,FERMILAB ASTROPHYS GRP,BATAVIA,IL 60510. OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210. RP OLIVE, KA (reprint author), UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455, USA. NR 24 TC 50 Z9 50 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD AUG 15 PY 1991 VL 265 IS 3-4 BP 239 EP 244 DI 10.1016/0370-2693(91)90048-U PG 6 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA GD837 UT WOS:A1991GD83700008 ER PT J AU KAZANAS, D AF KAZANAS, D TI ASTROPHYSICAL ASPECTS OF WEYL GRAVITY SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID RENORMALIZATION; GALAXIES; UNIVERSE RP NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 USA SN 0077-8923 J9 ANN NY ACAD SCI JI Ann.NY Acad.Sci. PD AUG 10 PY 1991 VL 631 BP 212 EP 224 PG 13 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GC956 UT WOS:A1991GC95600020 ER PT J AU WANNIER, PG PAGANI, L KUIPER, TBH FRERKING, MA GULKIS, S ENCRENAZ, P PICKETT, HM LECACHEUX, A WILSON, WJ AF WANNIER, PG PAGANI, L KUIPER, TBH FRERKING, MA GULKIS, S ENCRENAZ, P PICKETT, HM LECACHEUX, A WILSON, WJ TI WATER IN DENSE MOLECULAR CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, ABUNDANCES; INTERSTELLAR, MOLECULES ID INTER-STELLAR CLOUDS; GAS-PHASE CHEMISTRY; SHOCKED INTERSTELLAR CLOUDS; DISSOCIATIVE RECOMBINATION; RADIATIVE-TRANSFER; COMPLEX-MOLECULES; OXYGEN CHEMISTRY; DEUTERATED WATER; STAR FORMATION; ATOMIC CARBON AB We have used the G.P. Kuiper Airborne Observatory (KAO) to make initial observations of the half-millimeter ground-state transition of water in seven giant molecular clouds and in two late-type stars. No significant detections (> 3-sigma) were made, and the resulting upper limits are significantly below those expected from other, indirect observations and from several theoretical models. The implied interstellar H2O/CO abundance is less than 0.003 (3-sigma) in the cores of three giant molecular clouds. This value is less than expected from cloud chemistry models and also than estimates based on HDO and H3O+ observations. The limits are derived on the basis of a radiative transfer model incorporating LVG analysis for the low-opacity cloud exterior. Possible explanations for the low implied interstellar H2O abundance are (1) that fragmentation in dense clouds may cause unexpectedly large levels of ionizing UV radiation, (2) that water may be effectively frozen onto grains, or (3) that the cloud exterior effectively diffuses the emergent radiation. C1 OBSERV PARIS, F-92190 MEUDON, FRANCE. ECOLE NORM SUPER, F-75231 PARIS 05, FRANCE. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 75 TC 33 Z9 33 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 AUG 10 PY 1991 VL 377 IS 1 BP 171 EP 186 DI 10.1086/170345 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ463 UT WOS:A1991FZ46300016 ER PT J AU HOLLENBACH, DJ TAKAHASHI, T TIELENS, AGGM AF HOLLENBACH, DJ TAKAHASHI, T TIELENS, AGGM TI LOW-DENSITY PHOTODISSOCIATION REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, MOLECULES; RADIATIVE TRANSFER ID INFRARED-EMISSION BANDS; POLYCYCLIC AROMATIC-HYDROCARBONS; IONIZATION FRONT REGION; MOLECULAR CLOUDS; ORION NEBULA; INTERSTELLAR CLOUDS; MICRON EMISSION; 158 MICRON; CO; EXTINCTION AB We present results of one-dimensional theoretical models of photodissociation regions (PDRs), the predominantly neutral outer layers of molecular clouds exposed to an external far-ultraviolet (FUV) (6 eV < hv < 13.6 eV) radiation field. The models solve the chemical and thermal balance in the gas, and predict the emission from these regions primarily as a function of the incident FUV flux G0 (measured in units of 1.6 x 10(-3) ergs cm-2 s-1) and of the density n0 of the cloud. This paper extends previous work by Tielens and Hollenbach to lower densities and lower FUV fluxes by examining the parameter space 10(2) cm-3 < n0 less-than-or-equal-to 10(5) cm-3 and 1 less-than-or-equal-to G0 less-than-or-equal-to 10(4), relevant to molecular clouds in the ambient interstellar radiation field, reflection nebulae, and bright-rimmed clouds. This range is also relevant to observations of galaxies, where large ensembles of clouds 146-mu-m, [C I] 370 and 609-mu-m, [Si II] 35-mu-m, and [Fe II] 26 and 35-mu-m; the molecular rotational transitions (CO)-C-12 J = 1-0 and H-2 0-0 S(0); and the dust continuum intensities at 60 and 100-mu-m. In addition, we estimate the column density of FUV-pumped vibrationally excited H-2. The structure of a standard PDR (n0 = 10(3) cm-3, G0 = 10(3) cm-3) has a surface layer of A(nu) less-than-or-similar-to 1-2 mag of H, O, and C+ with a transition to H-2 and to C at A(v) greater-than-or-similar-to 1-2. Carbon is mostly CO at A(nu) greater-than-or-similar-to 4-6, and the oxygen not tied up in CO remains atomic to A(nu) approximately 10. The column density of atomic carbon, N(C), is of order 10(18) cm-2, relatively independent of n0 and G0. Hence, the intensities of the [C I] 370 and 609-mu-m lines are relatively insensitive to the physical parameters, and we ascribe their observed emission as arising from the PDR gas. Photoelectric heating dominates for A(nu) less-than-or-similar-to 6, and the cooling mostly emerges as [C II] 158-mu-m, with [O I] 63-mu-m also quite strong. Typically, the luminosity in [C II] 158-mu-m + [O I] 63-mu-m is of order 10(-3) to 10(-2) of the grain IR luminosity, a fraction which represents the efficiency of the photoelectric heating mechanism. We discuss the contribution of polycyclic aromatic hydrocarbons to photoelectric heating and conclude that the contribution is probably minor relative to the larger grains. We plot the ratio of the (CO)-C-12 J = 1-0 emission to the grain 100-mu-m intensity as a function of n0 and G0 and show that the ratio is sensitive to the FUV flux for G0 greater-than-or-similar-to 10. C1 ST NORBERT COLL,DEPT PHYS,DE PERE,WI 54115. RP HOLLENBACH, DJ (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 73 TC 298 Z9 298 U1 0 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1991 VL 377 IS 1 BP 192 EP 209 DI 10.1086/170347 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ463 UT WOS:A1991FZ46300018 ER PT J AU HOLLIS, JM OLIVERSEN, RJ KAFATOS, M MICHALITSIANOS, AG WAGNER, RM AF HOLLIS, JM OLIVERSEN, RJ KAFATOS, M MICHALITSIANOS, AG WAGNER, RM TI ULTRAVIOLET AND OPTICAL SPECTROSCOPY OF THE R-AQUARII SYMMETRICAL JET SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, H-II REGIONS; NEBULAE, INDIVIDUAL (R-AQUARII); NEBULAE, STRUCTURE; STARS, INDIVIDUAL (R-AQUARII); ULTRAVIOLET, SPECTRA ID COSMIC GAS; NEBULA; EMISSION; SHOCKS; SYSTEM; SPECTRUM; HOT AB The first ultraviolet spectrum of the southwest (SW) component of the symmetrical jet in, the R Aquarii binary system has been obtained in the range 1200-2000 angstrom with the International Ultraviolet Explorer (IUE). These results are compared to more encompassing spectra (1200-3200 angstrom) of the central H II region taken at the same time and also similar spectra of the northeast (NE) jet component obtained 6 months earlier. Moreover, optical spectra of both the NE and SW jet components in the range 3400-9800 angstrom were obtained within approximately 6 months and approximately 1 month, respectively, of the ultraviolet spectra. These highly complementary observations argue that excitation of the symmetrical jet may be due to shock excitation as the jet components overtake and impact the previously ionized material associated with the expanding inner nebulosity. We discuss the problems with this shock model as well as problems with competing photoionization models. We suggest that the jet components were ejected less than 90 years ago. C1 OHIO STATE UNIV,LOWELL OBSERV,DEPT ASTRON,FLAGSTAFF,AZ 86001. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. GEORGE MASON UNIV,DEPT PHYS,FAIRFAX,VA 22030. RP HOLLIS, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,CODE 930,GREENBELT,MD 20771, USA. NR 28 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1991 VL 377 IS 1 BP 227 EP 234 DI 10.1086/170349 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ463 UT WOS:A1991FZ46300020 ER PT J AU CHENG, KP FEIBELMAN, WA BRUHWEILER, FC AF CHENG, KP FEIBELMAN, WA BRUHWEILER, FC TI ULTRAVIOLET FE-VII ABSORPTION AND FE-II EMISSION-LINES OF CENTRAL STARS OF PLANETARY-NEBULAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, PLANETARY; STARS, EMISSION-LINE; ULTRAVIOLET, SPECTRA ID NUCLEI AB We used the SWP camera of the IUE satellite in the high-dispersion mode to search for Fe VII absorption and Fe II high-excitation emission lines in five additional very hot central stars of planetary nebulae. The objects were previously observed only in the low-dispersion mode and, because of their high effective temperatures (> 60,000 K), were likely to yield positive detections of the four strong Fe VII absorption and six Fe II emission lines in the IUE range, based on their short exposures in the low-dispersion mode. We detected some of the Fe VII lines at lambda-lambda-1208, 1239, and 1332 in all the objects of this program, LT 5, NGC 6058, NGC 7094, A43, and Lo 1 (= K1-26), as well as some of the Fe II emission lines at lambda-lambda-1360, 1776, 1869, 1881, 1884, and 1975. Two additional objects, NGC 2867 and He 2-131, were obtained from the IUE archive and were evaluated. The present study probably exhausts the list of candidates that are sufficiently bright and hot to be reached with the high-dispersion mode of the IUE. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. COMP SCI CORP,ASTRON PROGRAM,LOS ANGELES,CA 90045. RP CHENG, KP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,ASTRON & SOLAR PHYS LAB,POSTDOCTORAL FELLOW,GREENBELT,MD 20771, USA. NR 17 TC 4 Z9 4 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 AUG 10 PY 1991 VL 377 IS 1 BP 235 EP 239 DI 10.1086/170350 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ463 UT WOS:A1991FZ46300021 ER PT J AU JEFFERIES, SM DUVALL, TL HARVEY, JW OSAKI, Y POMERANTZ, MA AF JEFFERIES, SM DUVALL, TL HARVEY, JW OSAKI, Y POMERANTZ, MA TI CHARACTERISTICS OF INTERMEDIATE-DEGREE SOLAR P-MODE LINE WIDTHS SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE PROFILES; SUN, SPECTRA OSCILLATIONS; SUN, SPECTRA ID FULL-DISK OBSERVATIONS; GEOGRAPHIC SOUTH-POLE; OSCILLATIONS; LINEWIDTHS; ROTATION AB We present measurements of the p-mode line widths over the frequency range (1.87 < nu < 4.93 mHz) and degree range (1 less-than-or-equal-to 1 less-than-or-equal-to 150). These results are based on high-quality spectra obtained from intensity observations made at South Pole at a time of low solar activity (1987.9). The line width is observed to vary with mode frequency and degree. The variation with frequency is consistent with the observations of Libbrecht although our measurements are systematically narrower. The frequency variation has been explained in terms of radiative and convective damping of the modes. The observed variation with degree (at constant v) resolves previous contradictory results and is shown to exceed the S-1 variation that is expected on theoretical grounds. Here S is the travel time of a mode from its lower turning point in the solar interior, to its reflection at the solar surface. The deviations from an S-1 variation prompt us to suggest that there are two possible damping mechanisms, in addition to radiative and convective damping, that affect the modes. One of these mechanisms affects modes with 1 less-than-or-similar-to 40 while the other affects modes with 1 greater-than-or-similar-to 25. We suggest that (1) the extra damping for the high l-modes may be due to the absorption of mode power by active regions, and (2) the extra damping for the low l-modes may be caused by an increased leakage of wave energy into the corona by modes that tunnel through the temperature minimum region. C1 NASA,GODDARD SPACE FLIGHT CTR,NATL SOLAR OBSERV,ASTRON & SOLAR PHYS LAB,TUCSON,AZ 85726. NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. UNIV TOKYO,FAC SCI,DEPT ASTRON,TOKYO 113,JAPAN. RP JEFFERIES, SM (reprint author), UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716, USA. RI Duvall, Thomas/C-9998-2012 NR 28 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 AUG 10 PY 1991 VL 377 IS 1 BP 330 EP 336 DI 10.1086/170362 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ463 UT WOS:A1991FZ46300033 ER PT J AU BOGGESS, A BRUHWEILER, FC GRADY, CA EBBETS, DC KONDO, Y TRAFTON, LM BRANDT, JC HEAP, SR AF BOGGESS, A BRUHWEILER, FC GRADY, CA EBBETS, DC KONDO, Y TRAFTON, LM BRANDT, JC HEAP, SR TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - RESOLVED VELOCITY AND DENSITY STRUCTURE IN THE BETA-PICTORIS CIRCUMSTELLAR GAS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, MATTER; STARS, CIRCUMSTELLAR SHELLS; STARS, INDIVIDUAL (HD-39060); ULTRAVIOLET, SPECTRA ID DISK; SHELL AB We present the first HST Goddard High-Resolution Spectrograph (GHRS) observations of circumstellar (CS) gas around beta-Pictoris, providing the first evidence for resolved velocity and density structure in the CS gas. Two low-density features are visible in both observations. Comparison with IUE spectra suggests that at least one component may vary on time scales longer than the 23 day interval between the HST observations, implying that some of the low-density gas is CS. The high-density, infalling gas shows considerable velocity structure which varied dramatically between the two HST observations. The HST and IUE data are consistent with 2-3 infalling clumps of material per week. We infer an infall rate of 100-150 events yr-1, a rate which is broadly consistent with, but higher than, previously inferred infall rates. Collectively the GHRS data imply the presence of a more complex and dynamically active gaseous envelope than previously anticipated. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. BALL AEROSP SYST GRP,BOULDER,CO 80306. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. RP BOGGESS, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 440,GREENBELT,MD 20771, USA. RI heap, sara/E-2237-2012 NR 19 TC 39 Z9 39 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 AUG 10 PY 1991 VL 377 IS 1 BP L49 EP L52 DI 10.1086/186114 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400014 ER PT J AU CARDELLI, JA SAVAGE, BD BRUHWEILER, FC SMITH, AM EBBETS, DC SEMBACH, KR SOFIA, UJ AF CARDELLI, JA SAVAGE, BD BRUHWEILER, FC SMITH, AM EBBETS, DC SEMBACH, KR SOFIA, UJ TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - ELEMENTAL ABUNDANCES IN THE DIFFUSE CLOUDS TOWARD ZETA-PERSEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, ABUNDANCES; INTERSTELLAR, MATTER; ULTRAVIOLET, SPECTRA; STARS, INDIVIDUAL (ZETA-PERSEI) ID STELLAR AB We present an analysis of high-resolution (3.5 km s-1) observations of ultraviolet interstellar absorption lines of dominant ion stages arising in the diffuse clouds (5 less-than-or-equal-to upsilon. less-than-or-equal-to 20 km s-1) toward zeta-Per (HD 24912; O7 IIInf) obtained with the Goddard High-Resolution Spectrograph (GHRS). We report a detection of the weak intersystem line of C II] lambda-2325 (W-lambda = 1.42 +/- 0.41 m angstrom). For C, O, and Mg we are able to derive column densities from both weak lines and the damping wings of strongly saturated lines. For Mg, the derived column densities differ by a factor 3. The UV absorption-line measurements have become so accurate that the interpretations are now limited by inaccuracies in atomic f-values and our knowledge of solar abundances. Comparison of apparent column densities profiles, N(a)(upsilon), between lightly depleted (e.g., O I, Zn II) and heavily depleted (e.g., Cr II, Fe II) species indicates a transition from substantial depletions at upsilon. almost-equal-to 7.5 km s-1 to a decrease in depletion of a factor 2 or more for 7.5 < upsilon. less-than-or-equal-to 20 km s-1. This processing may be related to the proximity of the cloud(s) to the H II region surrounding zeta-Per. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. BALL AEROSP SYST,BOULDER,CO 80306. RP CARDELLI, JA (reprint author), UNIV WISCONSIN,WASHBURN OBSERV,475 N CHARTER ST,MADISON,WI 53706, USA. NR 19 TC 78 Z9 78 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 AUG 10 PY 1991 VL 377 IS 1 BP L57 EP L60 DI 10.1086/186116 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400016 ER PT J AU CARPENTER, KG ROBINSON, RD WAHLGREN, GM AKE, TB EBBETS, DC LINSKY, JL BROWN, A WALTER, FM AF CARPENTER, KG ROBINSON, RD WAHLGREN, GM AKE, TB EBBETS, DC LINSKY, JL BROWN, A WALTER, FM TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - THE CHROMOSPHERE OF ALPHA-TAURI SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, CHROMOSPHERES; STARS, INDIVIDUAL (ALPHA-TAU); STARS, LATE-TYPE; ULTRAVIOLET, SPECTRA ID EMISSION-LINES; STARS AB The K5 III star-alpha-Tau was observed with the Goddard High Resolution Spectrograph on 1990 November 27 as part of the Science Assessment Program for the Hubble Space Telescope. The observations include spectra in both the Large and Small Science Apertures in modes G270M at 2345 angstrom and echelle B at 2325 angstrom. The spectra show intersystem and permitted chromospheric emission lines of C II], Si II], Fe II, Fe I, Ni II, and Co II. Resolved profiles of the C II] lines indicate a complex chromospheric turbulent velocity distribution with mean value of almost-equal-to 24 km s-1, while their observed wavelengths indicate a 4 km s-1 downflow of the C II] plasma. Twenty-five new emission lines have been found in the 2320-2370 angstrom region, 17 of which have been identified with the aid of Skylab data obtained above the solar limb, including four lines from Co II (UV 8) and an Fe I (UV 12) line. The Co II lines confirm the earlier identification of the 2330 angstrom line as a Co II (UV 8) fluorescent feature, and the Fe I line represents a third product of the Mg II kappa-Fe I pumping which produces the Fe I (UV 44) lines near 2823 and 2844 angstrom. The Skylab spectrum shows different line strengths due to the higher density and lower optical depths of the solar chromosphere above the visible limb. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAM,GREENBELT,MD 20771. BALL AEROSP SYST GRP,GHRS PROJECT,BOULDER,CO 80306. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. NATL INST STAND & TECHNOL,BOULDER,CO 80309. SUNY STONY BROOK,STONY BROOK,NY 11794. RP CARPENTER, KG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. RI Carpenter, Kenneth/D-4740-2012 NR 15 TC 35 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1991 VL 377 IS 1 BP L45 EP L48 DI 10.1086/186113 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400013 ER PT J AU HEAP, SR ALTNER, B EBBETS, D HUBENY, I HUTCHINGS, JB KUDRITZKI, RP VOELS, SA HASER, S PAULDRACH, A PULS, J BUTLER, K AF HEAP, SR ALTNER, B EBBETS, D HUBENY, I HUTCHINGS, JB KUDRITZKI, RP VOELS, SA HASER, S PAULDRACH, A PULS, J BUTLER, K TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - SPECTROSCOPIC DETERMINATION OF STELLAR PARAMETERS OF MELNICK 42, AN O3F STAR IN THE LARGE MAGELLANIC CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, MAGELLANIC CLOUDS; STARS, INDIVIDUAL (MELNICK 42); STARS, MASSIVE; STARS, OF-TYPE; STARS, WINDS; ULTRAVIOLET, SPECTRA ID RADIATION-DRIVEN WINDS; HOT STARS; EXTINCTION; EVOLUTION AB GHRS and optical (ESO 3.6 m) observations of the O3f star Melnick 42 in the 30 Doradus complex are reported. A first analysis reveals that with a luminosity of 2.3 x 10(6) L. and a present mass of 100 M., Melnick 42 is one of the most luminous and massive stars known. An estimate of abundances indicates that iron and oxygen are very likely reduced by a factor of 4 relative to the Sun, whereas carbon is more strongly depleted and nitrogen is approximately solar. The terminal velocity of the stellar wind is 3000 km s-1. The mass-loss rate is 4 x 10(-6) M. yr-1, with a large uncertainty. The excellent quality GHRS spectrum taken in a crowded region of the LMC demonstrates the superiority of the HST for quantitative ultraviolet spectroscopy of hot stars in other galaxies. C1 BALL AEROSP,BOULDER,CO 80306. DOMINION ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. UNIV MUNICH,INST ASTRON & ASTROPHYS,W-8000 MUNICH 80,GERMANY. MAX PLANCK INST ASTROPHYS,GARCHING,GERMANY. RP HEAP, SR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771, USA. RI heap, sara/E-2237-2012 NR 17 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1991 VL 377 IS 1 BP L29 EP L32 DI 10.1086/186109 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400009 ER PT J AU HUBENY, I HEAP, SR ALTNER, B AF HUBENY, I HEAP, SR ALTNER, B TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - EVIDENCE FOR PHOTOSPHERIC MICROTURBULENCE IN EARLY O-STARS - ARE SURFACE GRAVITIES SYSTEMATICALLY UNDERESTIMATED SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EARLY-TYPE; STARS, INDIVIDUAL (MELNICK 42, BD + 75-DEGREES-325); STARS, MASSIVE; STARS, SUBDWARFS; STARS, WINDS; TURBULENCE; ULTRAVIOLET, SPECTRA ID PLANETARY-NEBULAE; SPECTROSCOPY AB GHRS spectra of two very hot stars (BD + 75-degrees 325 and Melnick 42) provide evidence for the presence of microturbulence in their photospheres. In attempting to reproduce the observed spectra, we have built theoretical models in which the microturbulence is allowed to modify not only the Doppler line widths (classical "spectroscopic" microturbulence), but also the turbulent pressure (thus mimicking a "physical" turbulence). We find that a corresponding modification of the temperature-pressure stratification influences the hydrogen and helium line profiles to the extent that the surface gravities of early O stars determined without considering microturbulence are too low by 0.1-0.15 dex. Thus, including microturbulence would reduce, or resolve completely, a long-standing discrepancy between evolutionary and spectroscopic stellar masses. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. COMP SCI CORP,ASTRON PROGRAM,GREENBELT,MD 20771. RP HUBENY, I (reprint author), UNIV SPACE RES ASSOC,CODE 681,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI heap, sara/E-2237-2012 NR 14 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 AUG 10 PY 1991 VL 377 IS 1 BP L33 EP L36 DI 10.1086/186110 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400010 ER PT J AU HUTCHINGS, JB BRUHWEILER, F BOGGESS, A HEAP, SR EBBETS, D BEAVER, E ROSENBLATT, E TRUONG, KQ PEREZ, M WESTMACOTT, R AF HUTCHINGS, JB BRUHWEILER, F BOGGESS, A HEAP, SR EBBETS, D BEAVER, E ROSENBLATT, E TRUONG, KQ PEREZ, M WESTMACOTT, R TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - ULTRAVIOLET-SPECTRA OF A STARBURST KNOT IN NGC-1068 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INTERGALACTIC MEDIUM; GALAXIES, SEYFERT; GALAXIES, STELLAR CONTENT ID MAGELLANIC CLOUDS; IUE OBSERVATIONS; MODELS; GALAXIES AB We present UV spectroscopy of a circumnuclear starburst knot in the Seyfert 2 galaxy NGC 1068. The spectrum shows the presence of several thousand 0 and B stars which appear to have formed about 3 million years ago. We also discuss the extinction and interstellar medium in the line of sight. C1 CATHOLIC UNIV AMER,ASTROPHYS PROGRAM,WASHINGTON,DC 20064. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. BALL AEROSP,BOULDER,CO 80306. UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. RP HUTCHINGS, JB (reprint author), DOMINION ASTROPHYS OBSERV,5071 W SAANICH RD,VICTORIA V8X 4M6,BC,CANADA. RI heap, sara/E-2237-2012 NR 19 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 AUG 10 PY 1991 VL 377 IS 1 BP L25 EP L28 DI 10.1086/186108 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400008 ER PT J AU LECKRONE, DS WAHLGREN, GM JOHANSSON, SG AF LECKRONE, DS WAHLGREN, GM JOHANSSON, SG TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - HIGH-RESOLUTION OBSERVATIONS OF THE 1942-A RESONANCE LINE OF HG-II IN THE CHEMICALLY PECULIAR B-STAR, CHI-LUPI SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; DIFFUSION; LINE PROFILES; STARS, ABUNDANCES; STARS, INDIVIDUAL (CHI-LUPI); STARS, PECULIAR-A; ULTRAVIOLET, SPECTRA ID SPECTRA AB We have used the Goddard High-Resolution Spectrograph on the Hubble Space Telescope to obtain high S/N observations of the sharp-lined, Hg- and Pt-rich B-type star, chi-Lupi, with a resolving power of 87,000. The observations reveal a level of spectroscopic detail never before observed at ultraviolet wavelengths for any star other than the Sun. This Letter concentrates on the region around the resonance line of Hg II at 1942 angstrom. The profile and central position of this line confirms beyond doubt that the Hg isotope anomaly in chi-Lupi is real and extreme, with Hg being heavily concentrated in the form of Hg-204. We emphasize the problems in atomic physics which impair the accurate analysis of spectra of this quality. C1 NASA,GODDARD SPACE FLIGHT CTR,NASA,GODDARD SPACE FLIGHT CTR,ASTRON PROGRAM,GREENBELT,MD 20771. UNIV LUND,DEPT PHYS,S-22362 LUND,SWEDEN. RP LECKRONE, DS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 23 TC 50 Z9 51 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 AUG 10 PY 1991 VL 377 IS 1 BP L37 EP L40 DI 10.1086/186111 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400011 ER PT J AU SAVAGE, BD CARDELLI, JA BRUHWEILER, FC SMITH, AM EBBETS, DC SEMBACH, KR AF SAVAGE, BD CARDELLI, JA BRUHWEILER, FC SMITH, AM EBBETS, DC SEMBACH, KR TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - ELEMENT ABUNDANCES AS A FUNCTION OF VELOCITY IN THE NEUTRAL GAS TOWARD ZETA-PERSEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, ABUNDANCES; INTERSTELLAR, MATTER; STARS, INDIVIDUAL (ZETA-PERSEI); ULTRAVIOLET, SPECTRA AB Observations of ultraviolet interstellar absorption lines toward zeta-Persei (HD 24912) obtained with the echelle mode of the Goddard High-Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope at a resolution of 3.5 km s-1 are presented. The data for O I, C II, Mg II, S II, Fe II, Si II, Mn II, and Zn II are converted into representations of apparent column density per unit velocity, N(a)(epsilon), over the velocity range from -30 to +40 km s-1. The profiles for ions that are the dominant state of ionization in neutral clouds permit a study of the variation of element abundance with velocity caused by changes in the gas phase depletion in the different absorbing regions situated toward zeta-Per. In the denser portions of the diffuse clouds with upsilon approximately +5 to 15 km s-1, heavy element depletions are very large. However, in absorbing components near -5 and +25 km s-1, the depletions are less severe, with a nearly solar gas phase abundance ratio being found for the gas in the +25 km s-1 component. The measurements confirm that the GHRS is well suited for diagnostic spectroscopy of interstellar gas. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. BALL AEROSP SYST,BOULDER,CO 80306. RP SAVAGE, BD (reprint author), UNIV WISCONSIN,WASHBURN OBSERV,475 N CHARTER ST,MADISON,WI 53706, USA. NR 12 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 AUG 10 PY 1991 VL 377 IS 1 BP L53 EP L56 DI 10.1086/186115 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400015 ER PT J AU SMITH, AM BRUHWEILER, FC LAMBERT, DL SAVAGE, BD CARDELLI, JA EBBETS, DC LYU, CH SHEFFER, Y AF SMITH, AM BRUHWEILER, FC LAMBERT, DL SAVAGE, BD CARDELLI, JA EBBETS, DC LYU, CH SHEFFER, Y TI 1ST RESULTS FROM GODDARD HIGH-RESOLUTION SPECTROGRAPH - C-I, S-I, AND CO TOWARD ZETA-PERSEI AND THE PHYSICAL CONDITIONS IN DIFFUSE CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, MATTER; INTERSTELLAR, MOLECULES; ULTRAVIOLET, SPECTRA ID INTERSTELLAR CLOUDS; ABUNDANCES AB Observations made by the Goddard High Resolution Spectrograph of the cool, neutral interstellar gas in the line of sight to zeta-Per are reported. Heliocentric velocities and equivalent widths were measured for absorption lines of C I and S I. Synthetic spectra were computed and fitted to the observed CO (2-0) and (3-0) bands in the A 1-PI-X 1-SIGMA+ system. Derived populations of the C I ground-state fine-structure levels and the CO ground-state rotational levels were used to derive densities of two of the three, and possibly four, detected cloud components. The velocity component displaying the strongest C I absorption reveals extraordinarily high pressure (P/k > 4.3 x 10(4) cm-3 K). C1 CATHOLIC UNIV AMER,CSC,DEPT PHYS,WASHINGTON,DC 20064. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. BALL AEROSP,BOULDER,CO 80306. RP SMITH, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771, USA. NR 17 TC 32 Z9 32 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 AUG 10 PY 1991 VL 377 IS 1 BP L61 EP L64 DI 10.1086/186117 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400017 ER PT J AU WAHLGREN, GM LECKRONE, DS SHORE, SN LINDLER, DJ GILLILAND, RL EBBETS, DC AF WAHLGREN, GM LECKRONE, DS SHORE, SN LINDLER, DJ GILLILAND, RL EBBETS, DC TI 1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - A DEMONSTRATION OF SPECTRAL RESOLUTION AND EXPERIMENTS WITH DECONVOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE INSTRUMENTS; NUMERICAL METHODS; STARS, INDIVIDUAL (CHI-LUPI); ULTRAVIOLET, SPECTRA AB High-quality spectra of the sharp-lined star chi-Lupi were obtained with the Goddard High Resolution Spectrograph (GHRS). We display spectra for the various resolving powers achievable with the echelle and G160M gratings. The effect of spherical aberration upon the spectral resolution is found to be negligible when using the small science aperture. The resolution of the large science aperture spectra is degraded by less than a factor of 2. Our efforts with spectral deconvolution using several techniques show that it is possible to regain much of the spectral resolution lost in the large science aperture if high signal-to-noise spectra are obtained. RP WAHLGREN, GM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 10 TC 8 Z9 8 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1991 VL 377 IS 1 BP L41 EP L44 DI 10.1086/186112 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ464 UT WOS:A1991FZ46400012 ER PT J AU BENNETT, C AF BENNETT, C TI MAPPING THE COLD GLOW OF THE BIG-BANG SO NEW SCIENTIST LA English DT Article RP BENNETT, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,COBE SCI WORKING GRP,GREENBELT,MD 20771, USA. NR 0 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 AUG 10 PY 1991 VL 131 IS 1781 BP 35 EP 39 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GA480 UT WOS:A1991GA48000037 ER PT J AU HIDE, R DICKEY, JO AF HIDE, R DICKEY, JO TI EARTHS VARIABLE ROTATION SO SCIENCE LA English DT Article ID ATMOSPHERIC ANGULAR-MOMENTUM; OF-DAY CHANGES; EL-NINO; SOUTHERN OSCILLATION; RADIO INTERFEROMETRY; FORCED NUTATIONS; MOUNTAIN-TORQUE; LENGTH; FLUCTUATIONS; MANTLE AB Recent improvements in geodetic data and practical meteorology have advanced research on fluctuations in the Earth's rotation. The interpretation of these fluctuations is inextricably linked with studies of the dynamics of the Earth-moon system and dynamical processes in the liquid metallic core of the Earth (where the geomagnetic field originates), other parts of the Earth's interior, and the hydrosphere and atmosphere. Fluctuations in the length of the day occurring on decadal time scales have implications for the topography of the core-mantle boundary and the electrical, magnetic, and other properties of the core and lower mantle. Investigations of more rapid fluctuations bear on meteorological studies of interannual, seasonal, and intraseasonal variations in the general circulation of the atmosphere and the response of the oceans to such variations. C1 CALTECH,JET PROP LAB,MAIL STOP 238-332,PASADENA,CA 91109. ROBERT HOOKE INST,THE OBSERV,CLARENDON LAB,OXFORD OX1 3PU,ENGLAND. NR 101 TC 149 Z9 153 U1 1 U2 13 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 9 PY 1991 VL 253 IS 5020 BP 629 EP 637 DI 10.1126/science.253.5020.629 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GA304 UT WOS:A1991GA30400031 PM 17772366 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H AF BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H TI THEORETICAL-STUDY OF THE BONDING OF NB2+ TO CH2, C2H2, AND C2H4 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAS-PHASE; PERIODIC TRENDS; IONS; ENERGIES; STRENGTHS; ORBITALS; ALKANES; 1ST-ROW; CI(SD) AB The bonding of Nb2+ with CH2, C2H2, and C2H4 is studied by using electronic structure calculations that include high levels of electron correlation. The binding energy for NbCH2(2+) is in good agreement with the lower bound determined from the reaction with CH4 but is significantly smaller than the value determined from the binding energy and ionization potential of NbCH2+. The calculations and a new interpretation of the experiment indicate that the larger value is in error primarily because the ionization potential of NbCH2+ determined from bracketing charge-exchange reactions is too small. The computed binding energy of NbC2H2(2+) is in good agreement with experiment. The calculations show that the bonding is predominantly covalent in character for both NbCH2(2+) and NbC2H2(2+), whereas for NbC2H4(2+) the electronic states that are predominantly ionic and covalent are nearly degenerate. The trend in binding energies, CH2 > C2H2 > C2H4, is consistent with the energy required to prepare the ligands for bonding. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 34 TC 15 Z9 15 U1 0 U2 0 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 AUG 8 PY 1991 VL 95 IS 16 BP 6191 EP 6194 DI 10.1021/j100169a027 PG 4 WC Chemistry, Physical SC Chemistry GA GA417 UT WOS:A1991GA41700027 ER PT J AU MCKAY, CP TOON, OB KASTING, JF AF MCKAY, CP TOON, OB KASTING, JF TI MAKING MARS HABITABLE SO NATURE LA English DT Review ID ATMOSPHERIC CARBON-DIOXIDE; CLIMATIC-CHANGE; MARTIAN PALEOCLIMATE; TERRESTRIAL PLANETS; NOBLE-GASES; RICH PLANET; CO2; EARTH; WATER; ABUNDANCE AB Mars is believed to be lifeless, but it may be possible to transform it into a planet suitable for habitation by plants, and conceivably humans. The success of such an enterprise would depend on the abundance, distribution and form of materials on the planet that could provide carbon dioxide, water and nitrogen. C1 NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. PENN STATE UNIV,DEPT GEOSCI,UNIVERSITY PK,PA 16802. RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 85 TC 81 Z9 82 U1 4 U2 40 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD AUG 8 PY 1991 VL 352 IS 6335 BP 489 EP 496 DI 10.1038/352489a0 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA GA226 UT WOS:A1991GA22600051 PM 11538095 ER PT J AU BARNER, JB ROGERS, CT INAM, A RAMESH, R BERSEY, S AF BARNER, JB ROGERS, CT INAM, A RAMESH, R BERSEY, S TI ALL A-AXIS ORIENTED YBA2CU3O7-Y-PRBA2CU3O7-Z-YBA2CU3O7-Y JOSEPHSON DEVICES OPERATING AT 80-K SO APPLIED PHYSICS LETTERS LA English DT Article ID YBA2CU3O7-DELTA AB We have demonstrated the controllable, reproducible fabrication of nonhysteretic Josephson devices with excess-current weak-link characteristics at temperatures up to 80 K. The devices are patterned from in situ deposited alpha-axis oriented YBa2Cu3O7-y-PrBa2Cu3O7 YBa2Cu3O7-y trilayers grown on SrTiO3(001) substrates. Control of the critical current density and resistance is achieved by varying the thickness of the PrBa2Cu3O7 barrier layer. Critical current densities in excess of 10(4) A/cm 2 have been reproducibly measured; good uniformity across the wafer is obtained with device parameters scaling with device area. Strong constant-voltage current steps are observed under 11.2 GHz microwave radiation at temperatures up to and above 80 K. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP BARNER, JB (reprint author), BELLCORE,RED BANK,NJ 07701, USA. NR 8 TC 140 Z9 140 U1 0 U2 3 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 AUG 5 PY 1991 VL 59 IS 6 BP 742 EP 744 DI 10.1063/1.105330 PG 3 WC Physics, Applied SC Physics GA FZ350 UT WOS:A1991FZ35000042 ER PT J AU DOROGY, WE STCLAIR, AK AF DOROGY, WE STCLAIR, AK TI WET SPINNING OF SOLID POLYAMIC ACID FIBERS SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article AB Recent research at the NASA Langley Research Center has involved the production of polyamic acid fibers from resins derived from the reaction of 3,3,'4,4'-benzophenonetetra-carboxylic dianhydride and 3,3'-diaminobenzophenone or 4,4'-oxydianiline in N,N-dimethylacetamide. Resins were extruded into aqueous solutions of ethylene glycol, ethanol, or N,N-dimethylacetamide in order to induce filament formation. These filaments were then washed in water and dried using air or vacuum ovens. Fractured fiber ends were examined using an optical or scanning electron microscope for the presence of macropores, termed voids. Coagulation bath concentration and composition, resin inherent viscosity, resin % solids, and filament diameter were studied to determine their effect on the production of solid core fibers. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 15 TC 23 Z9 23 U1 1 U2 9 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD AUG 5 PY 1991 VL 43 IS 3 BP 501 EP 519 DI 10.1002/app.1991.070430311 PG 19 WC Polymer Science SC Polymer Science GA FX315 UT WOS:A1991FX31500011 ER PT J AU MORELLI, JJ FRY, CG GRAYSON, MA LIND, AC WOLF, CJ AF MORELLI, JJ FRY, CG GRAYSON, MA LIND, AC WOLF, CJ TI THE THERMAL OXIDATIVE-DEGRADATION OF AN ETHYLENE TETRAFLUOROETHYLENE-COPOLYMER-BASED ELECTRICAL WIRE INSULATION SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article ID POLYMERS AB A multidisciplinary spectroscopic evaluation of a commerical wire insulation based on a cross-linked copolymer of ethylene and tetrafluoroethylene (X-ETFE) was conducted to determine the chemical changes taking place during thermal aging. These studies provided insight into the roles of the various additives, such as triallylisocyanurate (TAIC) and antimony oxide, in the formulated X-ETFE insulation. During irradiation processing, a large fraction of the TAIC is converted to a cross-linked isocyanurate moiety; the unconverted TAIC is released during aging. Thermal aging of the X-ETFE wire insulations was performed in air at 200-degrees-C for up to 5 months and resulted in oxidation of the base ETFE, loss of unreacted TAIC, and a small amount of dehydrofluorination. The antimony oxide serves the multiple roles of flame retardant and scavenger for the pyrolytically generated hydrogen fluoride. C1 MCDONNELL DOUGLAS CORP,RES LABS,ST LOUIS,MO 63166. RP MORELLI, JJ (reprint author), LOCKHEED ESC,NASA,WSTF,PO DRAWER MM,LAS CRUCES,NM 88004, USA. NR 36 TC 6 Z9 6 U1 2 U2 12 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD AUG 5 PY 1991 VL 43 IS 3 BP 601 EP 611 DI 10.1002/app.1991.070430322 PG 11 WC Polymer Science SC Polymer Science GA FX315 UT WOS:A1991FX31500022 ER PT J AU CARRERE, V LANG, HR CRAWFORD, MF AF CARRERE, V LANG, HR CRAWFORD, MF TI MAPPING SURFACE ALTERATION EFFECTS ASSOCIATED WITH HYDROCARBON RESERVOIRS AT GYPSUM PLAIN, TEXAS, AND CEMENT, OKLAHOMA, USING MULTISPECTRAL INFORMATION SO AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS LA English DT Meeting Abstract C1 JET PROPULS LAB,PASADENA,CA. ARCO OIL & GAS CO,PLANO,TX. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSN PETROL GEOLOGISTS PI TULSA PA 1444 S BOULDER AVE PO BOX 979, TULSA, OK 74101 SN 0149-1423 J9 AAPG BULL JI AAPG Bull.-Am. Assoc. Petr. Geol. PD AUG PY 1991 VL 75 IS 8 BP 1408 EP 1408 PG 1 WC Energy & Fuels; Engineering, Petroleum; Geosciences, Multidisciplinary SC Energy & Fuels; Engineering; Geology GA GA885 UT WOS:A1991GA88500132 ER PT J AU RAJ, SV LANGDON, TG AF RAJ, SV LANGDON, TG TI CREEP-BEHAVIOR OF COPPER AT INTERMEDIATE TEMPERATURES .2. SURFACE MICROSTRUCTURAL OBSERVATIONS SO ACTA METALLURGICA ET MATERIALIA LA English DT Article ID TIN SINGLE-CRYSTALS; X-RAY-DIFFRACTION; STEADY-STATE; DISLOCATION CREEP; ALUMINUM; MISORIENTATION; MODEL; GLIDE AB Detailed microstructural observations reveal the formation of three types of slip features during creep of copper at intermediate temperatures between 0.46-0.72 T(m), where T(m) is the absolute melting point. Single slip occurs at the higher temperatures and lower stresses with the slip lines being inhomogeneously distributed among the grains at the lower strains. Complex wavy slip features are observed at the higher temperatures, higher stresses and with increasing strains, thereby suggesting that cross-slip mechanisms may be important under these conditions. The absence of these slip patterns at the lower temperatures and higher stresses, when mainly multiple slip morphologies are observed, suggests that cross-slip mechanisms are likely to control the creep of polycrystalline copper only in a limited range of stresses and temperatures. C1 UNIV SO CALIF, DEPT MAT SCI, LOS ANGELES, CA 90089 USA. UNIV SO CALIF, DEPT MECH ENGN, LOS ANGELES, CA 90089 USA. RP RAJ, SV (reprint author), NASA, LEWIS RES CTR, MS 49-1, 21000 BROOKPARK RD, CLEVELAND, OH 44135 USA. RI Langdon, Terence/B-1487-2008 NR 35 TC 17 Z9 17 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-7151 J9 ACTA METALL MATER JI Acta Metall. Mater. PD AUG PY 1991 VL 39 IS 8 BP 1817 EP 1822 DI 10.1016/0956-7151(91)90150-Y PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FY829 UT WOS:A1991FY82900010 ER PT J AU RAJ, SV LANGDON, TG AF RAJ, SV LANGDON, TG TI CREEP-BEHAVIOR OF COPPER AT INTERMEDIATE TEMPERATURES .3. A COMPARISON WITH THEORY SO ACTA METALLURGICA ET MATERIALIA LA English DT Article ID STACKING-FAULT ENERGY; SINGLE-CRYSTALS; STEADY-STATE; POWER-LAW; SUBSTRUCTURE FORMATION; DISLOCATION-STRUCTURE; STRESS REDUCTIONS; ALPHA-IRON; DEFORMATION; METALS AB A detailed analysis of the creep behavior of copper in the intermediate temperature regime between 0.46-0.72 T(m) of the absolute melting point is presented. Several possible creep mechanisms are considered, and it is concluded that high temperature climb is dominant in the power-law creep region, while obstacle-controlled glide occurring within the cell interiors is rate-controlling in the exponential creep regime. A phenomenological model is proposed which assumes that cell boundaries within subgrains act as sources and obstacles to gliding dislocations. Dislocation annihilation is assumed to occur at the cell boundaries by climb and cross-slip. The implications of these results on the transition from power-law to exponential creep are examined. C1 UNIV SO CALIF, DEPT MAT SCI, LOS ANGELES, CA 90089 USA. UNIV SO CALIF, DEPT MECH ENGN, LOS ANGELES, CA 90089 USA. RP RAJ, SV (reprint author), NASA, LEWIS RES CTR, MS 49-1, 21000 BROOKPARK RD, CLEVELAND, OH 44135 USA. RI Langdon, Terence/B-1487-2008 NR 63 TC 24 Z9 24 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-7151 J9 ACTA METALL MATER JI Acta Metall. Mater. PD AUG PY 1991 VL 39 IS 8 BP 1823 EP 1832 DI 10.1016/0956-7151(91)90151-P PG 10 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FY829 UT WOS:A1991FY82900011 ER PT J AU CHEUNG, S FLORES, J AF CHEUNG, S FLORES, J TI CONVERGENCE ACCELERATION OF VISCOUS AND INVISCID HYPERSONIC FLOW CALCULATIONS SO AIAA JOURNAL LA English DT Article AB The convergence of inviscid and viscous hypersonic flow calculations using a two-dimensional flux-vector-splitting code is accelerated by applying a Richardson-type overrelaxation method. Successful results are presented for various cases, and a 50% savings in computer time (convergence rate is increased by a factor of 2) is usually achieved. An analytical formula for the overrelaxation factor is derived, and the performance of this scheme is confirmed numerically. Moreover, application of this overrelaxation scheme produces a favorable preconditioning for Wynne's epsilon-algorithm. Both techniques have been extended to viscous three-dimensional flows and applied to accelerate the convergence of the compressible Navier-Stokes code. A savings of 40% in computer time is achieved in this case. C1 UNIV CALIF DAVIS,DEPT MATH,DAVIS,CA 95616. UNIV CALIF DAVIS,DEPT MECH,DAVIS,CA 95616. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CHEUNG, S (reprint author), MARITIME CENT ANAL TEAM INST,3933 BLUE GUM DR,SAN JOSE,CA 95127, USA. NR 28 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1991 VL 29 IS 8 BP 1214 EP 1222 DI 10.2514/3.10725 PG 9 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100003 ER PT J AU COIRIER, WJ AF COIRIER, WJ TI EFFICIENT REAL-GAS UPWINDED NAVIER-STOKES COMPUTATIONS OF HIGH-SPEED FLOWS SO AIAA JOURNAL LA English DT Article ID IMPLICIT AB An efficient method to account for the chemically frozen thermodynamic and transport properties of air in three-dimensional Navier-Stokes calculations has been demonstrated. This approach uses an explicitly specified equation of state (EOS) so that the fluid pressure, temperature, and transport properties are directly related to the flow variables. The method is efficient since no subiterations are required to deduce the pressure and temperature from the flux variables and is modular by allowing different equations of state to be easily supplied to the code. The flexibility of the EOS approach is shown by its implementation into a high-order total variation diminishing upwinding scheme as well as a standard central-differencing scheme. The EOS approach is then demonstrated by computing the hypersonic flow through the corner region of two mutually perpendicular flat plates using both the upwind and central-differencing schemes. RP COIRIER, WJ (reprint author), NASA,LEWIS RES CTR,COMPUTAT ACID DYNAM BRANCH,CLEVELAND,OH 44135, USA. NR 29 TC 2 Z9 2 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 AUG PY 1991 VL 29 IS 8 BP 1223 EP 1231 DI 10.2514/3.10726 PG 9 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100004 ER PT J AU HARVEY, AD ACHARYA, S LAWRENCE, SL CHEUNG, S AF HARVEY, AD ACHARYA, S LAWRENCE, SL CHEUNG, S TI SOLUTION-ADAPTIVE GRID PROCEDURE FOR HIGH-SPEED PARABOLIC FLOW SOLVERS SO AIAA JOURNAL LA English DT Article ID EQUATIONS AB A solution-adaptive grid procedure based on an error equidistribution scheme is developed and applied to a parabolized Navier-Stokes solver. An improved method of selecting weighting functions is introduced that involves normalizing a combination of flowfield gradients and curvature of a number of dependent variables and then selecting the largest at each point. The scheme redistributes grid points line by line with grid point motion controlled by forces analogous to tensional and torsional spring forces with the spring constants set equal to the weighting functions. Torsional terms are functions of the grid point positions along neighboring grid lines and provide grid smoothness and stability. A grid-fitting scheme is introduced for external flows in which the number of grid points in the freestream are reduced to a minimum. Results for several problems are presented to demonstrate the improvements obtainable with the solution-adaptive grid procedure. C1 NASA,AMES RES CTR,MECH ENGN,MOFFETT FIELD,CA 94035. MARITIME CENT ANAL TEAM,MOFFETT FIELD,CA 94035. RP HARVEY, AD (reprint author), LOUISIANA STATE UNIV,MECH ENGN,BATON ROUGE,LA 70803, USA. NR 17 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 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1991 VL 29 IS 8 BP 1232 EP 1240 DI 10.2514/3.10727 PG 9 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100005 ER PT J AU DOGRA, VK MOSS, JN AF DOGRA, VK MOSS, JN TI HYPERSONIC RAREFIED FLOW ABOUT PLATES AT INCIDENCE SO AIAA JOURNAL LA English DT Article AB Results of a numerical study using the direct simulation Monte Carlo (DSMC) method are presented for the transitional flow about two plate configurations at incidence. Both plates are 12 m in length. One has zero thickness, and the other has a thickness of 0.5 m with a nose radius of 0.5 m. The flow conditions simulated are those experienced by the Space Shuttle Orbiter during re-entry at 7.5 km/s. The altitude range considered is that from 200 to 100 km, which encompasses most of the transitional flow regime for the Space Shuttle Orbiter. The DSMC simulations show that transitional effects are evident when compared with free-molecular results for all cases considered. These results demonstrate clearly that the transitional effects are significant even at those altitudes where the flow about a typical space vehicle has often been considered as free molecular. Therefore, it becomes very important to identify these transitional flow effects when making aerodynamic flight measurements of space vehicles as are currently being made with the Space Shuttle Orbiter vehicles. In the absence of calculations, previous flight data analyses have relied exclusively on the adjustments in the gas-surface interaction models without accounting for the transitional effects, which can be comparable in magnitude. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DOGRA, VK (reprint author), VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666, USA. NR 21 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 0001-1452 J9 AIAA J JI AIAA J. PD AUG PY 1991 VL 29 IS 8 BP 1250 EP 1258 DI 10.2514/3.10729 PG 9 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100007 ER PT J AU ERWIN, DA PHAMVANDIEP, GC DEININGER, WD AF ERWIN, DA PHAMVANDIEP, GC DEININGER, WD TI LASER-INDUCED FLUORESCENCE MEASUREMENTS OF FLOW VELOCITY IN HIGH-POWER ARCJET THRUSTER PLUMES SO AIAA JOURNAL LA English DT Article ID HYDROGEN; PLASMA; LINE AB The flow velocity of atomic hydrogen in the plume of an ammonia-propelled arcjet thruster was measured using laser-induced fluorescence (LIF). The velocity was obtained by the Doppler shift of the absorption peak of the Balmer alpha-spectral line. Measurements were made at the nozzle exit, varying the distance from the plume centerline. Results are presented for arcjet operating conditions 13, 20, and 27 kW with a mass flow of 0.31 g/s. The on-axis H flow velocity varies from 14 to 28 km/s over this range of input power. The axial velocity as a function of the distance from the axis is sharply peaked, dropping to almost zero at a radius of less than 5 mm. C1 CALTECH,JET PROP LAB,ELECT PROPALS & PLASMA TECHNOL GRP,PASADENA,CA 91109. RP ERWIN, DA (reprint author), UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089, USA. NR 24 TC 8 Z9 8 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 AUG PY 1991 VL 29 IS 8 BP 1298 EP 1303 DI 10.2514/3.10735 PG 6 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100013 ER PT J AU CHEN, GS BRUNO, RJ SALAMA, M AF CHEN, GS BRUNO, RJ SALAMA, M TI OPTIMAL PLACEMENT OF ACTIVE PASSIVE MEMBERS IN TRUSS STRUCTURES USING SIMULATED ANNEALING SO AIAA JOURNAL LA English DT Article ID OPTIMIZATION; DESIGN; SYSTEMS AB Active structural members with built-in sensing, feedback control, and actuation functions are used herein, along with passively damped members, to augment the inherent damping in truss structures. The effective use of such members makes it desirable to distribute them optimally throughout the structure. For simple structural systems, it is possible to place these members with some degree of optimality on the basis of engineering judgment. However, for more complex systems, the number of possible choices is so large that one may have to rely on a more formal optimization technique. This paper deals with the optimal placement of active and passive members in complex truss structures. The problem falls in the class of combinatorial optimization, for which the solution becomes exceedingly intractable as the problem size increases. This difficulty is overcome herein by use of the simulated annealing technique. We adopt the maximization of the cumulative energy dissipated over a finite time interval as the measure of optimality. The selection of nearly optimal locations for both passive and active members is consistently treated through the use of the finite-time energy dissipation criterion within the framework of the simulated annealing algorithm. Numerical examples are used to illustrate the effectiveness of this methodology. RP CHEN, GS (reprint author), CALTECH,JET PROP LAB,APPL TECHNOL SECT,PASADENA,CA 91109, USA. NR 24 TC 78 Z9 98 U1 0 U2 6 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 AUG PY 1991 VL 29 IS 8 BP 1327 EP 1334 DI 10.2514/3.10739 PG 8 WC Engineering, Aerospace SC Engineering GA FZ251 UT WOS:A1991FZ25100017 ER PT J AU MAYER, EA BALDI, JP AF MAYER, EA BALDI, JP TI CAN REGULATORY PEPTIDES BE REGARDED AS WORDS OF A BIOLOGICAL LANGUAGE SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE INFORMATION THEORY; PLURICHEMICAL TRANSMISSION; TRANSDUCTION NETWORKS; REGULATORY PEPTIDES ID VASOACTIVE INTESTINAL POLYPEPTIDE; MOUSE VAS-DEFERENS; SUBSTANCE-P; GROWTH-FACTOR; ADENOSINE 5'-TRIPHOSPHATE; GUINEA-PIG; INTERCELLULAR COMMUNICATION; SYMPATHETIC-GANGLIA; MITOGENIC RESPONSE; NERVOUS-SYSTEM AB Despite the complexities of individual systems, neurocrine, endocrine, and growth factor-mediated signaling systems show striking similarities in the molecules they use for communication and in their signal-transduction mechanisms. In contrast to the traditional view in cell biology, which has focused on the regulatory aspects of neurocrine and endocrine messengers and growth factors, an analysis of various aspects of peptidergic cell-to-cell communication on the basis of information theory is suggested. According to theorems for efficient and error-free encoding, the differences in rate and distance of information transfer and in noise interference between neurocrine, endocrine, and growth factor-mediated messages require different encoding strategies. These differences are reflected in the use of plurichemical transmission (to increase information content) or in the number and sequence of amino acids within peptide molecules (to protect against noise interference). In contrast to the quantitative information content, the qualitative information of the message is not transmitted but is retrieved when the message interacts with transduction networks at the receiver cell. The semantic information is contained within the rules specifying the conditional co-occurrences of signals. The suggested analysis provides a framework for the understanding of various aspects of cell-to-cell communication, such as structure-function relationship of regulatory peptides, multiple receptor subtypes, plurichemical transmission, and transduction networks. The data discussed are consistent with the role of regulatory peptides as signals in a universal structured code for biological communication. C1 CALTECH,JET PROPULS LAB,PASADENA,CA 91125. UNIV CALIF LOS ANGELES,DEPT PHYSIOL,LOS ANGELES,CA 90024. CALTECH,DIV BIOL,PASADENA,CA 91125. RP MAYER, EA (reprint author), UNIV CALIF LOS ANGELES,DEPT MED,CTR ULCER RES & EDUC,LOS ANGELES,CA 90024, USA. FU NIDDK NIH HHS [DK-40919] NR 89 TC 19 Z9 19 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD AUG PY 1991 VL 261 IS 2 BP G171 EP G184 PN 1 PG 14 WC Physiology SC Physiology GA GC251 UT WOS:A1991GC25100045 PM 1872391 ER PT J AU YAMAMOTO, A KEIL, LC REID, IA AF YAMAMOTO, A KEIL, LC REID, IA TI ACTIVATION OF RENAL MECHANORECEPTORS INCREASES VASOPRESSIN RELEASE IN RABBITS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE AFFERENT RENAL NERVES; RENAL PELVIS; INTRAPELVIC PRESSURE; PELVIC PERFUSION; PLASMA VASOPRESSIN CONCENTRATION; RENAL DENERVATION; CHEMORECEPTORS ID ARTERIAL MECHANORECEPTORS; PLASMA VASOPRESSIN; RENORENAL REFLEXES; SENSORY RECEPTORS; RENIN RELEASE; NERVES; RAT; STIMULATION; KIDNEY; MECHANISMS AB Electrical stimulation of afferent renal nerves increases plasma vasopressin (AVP) concentration, but the role of these nerves in the control of AVP release is not known. The aim of the present study was to investigate the effect of activation of renal mechanoreceptors and chemoreceptors on plasma AVP concentration in anesthetized rabbits. Intrapelvic pressure was increased to activate renal mechanoreceptors, and the renal pelvis was perfused with 1.0 M NaCl, 0.1 M KCl, and 1.0 M mannitol solutions to activate R2 chemoreceptors. With increased pelvic pressure, plasma AVP concentration increased from 12.4 +/- 3.8 to 36.2 +/- 16.1 pg/ml at 5 min and to 37.4 +/- 16.1 pg/ml at 10 min (P < 0.01). Plasma renin activity increased from 15.7 +/- 4.0 to 22.1 +/- 3.3 ng.ml-1.2 h-1 (P < 0.05), but blood pressure and heart rate did not change significantly. Similar increases in plasma AVP concentration occurred during perfusion of the renal pelvis with 1.0 M NaCl (17.6 +/- 8.1 to 53.7 +/- 24.0 pg/ml), 0.1 M KCl (9.2 +/- 2.1 to 39.7 +/- 17.3 pg/ml), and 1.0 M mannitol (27.5 +/- 10.9 to 77.5 +/- 30.8 pg/ml) solutions. However, because pelvic pressure increased by 40-50 mmHg during the perfusions, the experiments were repeated with use of a different perfusion method in which pelvic pressure increased by < 5 mmHg. Under these conditions, plasma AVP concentration did not change significantly during perfusion with any of the solutions. To determine whether the mechanoreceptor-induced increase in AVP release is mediated by the renal nerves, pelvic pressure was increased in another group of rabbits after renal denervation. Renal denervation markedly reduced the increase in plasma AVP concentration (2.2 +/- 0.5 to 3.2 +/- 0.6 pg/ml, P < 0.05) but did not prevent the increase in plasma renin activity (8.2 +/- 1.6 to 11.8 +/- 1.8 ng.ml-1.2 h-1, P < 0.01). These results indicate that activation of renal mechanoreceptors stimulates AVP release and suggest that this response is mediated by afferent renal nerves rather than by the renin-angiotensin system. C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,BOX 0444,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. FU NHLBI NIH HHS [HL-29714] NR 39 TC 11 Z9 11 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD AUG PY 1991 VL 261 IS 2 BP R484 EP R490 PN 2 PG 7 WC Physiology SC Physiology GA GC252 UT WOS:A1991GC25200076 PM 1877705 ER PT J AU ROGERS, SE KWAK, D AF ROGERS, SE KWAK, D TI AN UPWIND DIFFERENCING SCHEME FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS SO APPLIED NUMERICAL MATHEMATICS LA English DT Article ID CIRCULAR-CYLINDER; PRIMITIVE VARIABLES; NUMERICAL-SOLUTIONS; STEADY FLOW; PSEUDOCOMPRESSIBILITY; CAVITY; WAKE; RE AB The steady-state incompressible Navier-Stokes equations in two dimensions are solved numerically using the artificial compressibility formulation. The convective terms are upwind differenced using a flux-difference split approach that has uniformly high accuracy throughout the interior grid points. The viscous fluxes are differenced using second-order accurate central differences. The numerical system of equations is solved using an implicit line relaxation scheme. The scheme is applicable to both steady-state and unsteady flow computations. In the current work steady-state applications are emphasized. Characteristic boundary conditions are formulated and used in the solution procedure. The overall scheme is capable of being run at extremely large pseudo-time steps, leading to fast convergence. Three test cases are presented to demonstrate the accuracy and robustness of the code. These are the flow in a square driven cavity, flow over a backward facing step, and flow around a two-dimensional circular cylinder. RP ROGERS, SE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 28 TC 57 Z9 68 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD AUG PY 1991 VL 8 IS 1 BP 43 EP 64 DI 10.1016/0168-9274(91)90097-J PG 22 WC Mathematics, Applied SC Mathematics GA GJ531 UT WOS:A1991GJ53100004 ER PT J AU WATSON, SM MILLS, JP GAISER, SL DINER, DJ AF WATSON, SM MILLS, JP GAISER, SL DINER, DJ TI DIRECT IMAGING OF NONSOLAR PLANETS WITH INFRARED TELESCOPES USING APODIZED CORONAGRAPHS SO APPLIED OPTICS LA English DT Article ID SYSTEMS; ARRAY AB This research examines the use of modified Lyot coronagraphs with monolithic and segmented infrared telescopic systems for imaging nonsolar planets. These systems are investigated with the aim of reducing the effects of stellar diffracted energy on the planet image in the final image plane. A square telescope objective is best for this purpose. The associated coronagraph is composed of a cross-shaped apodizer in the first focal plane and either a square Lyot stop or circular corner Lyot stops in the corners of the pupil plane. We examine the consequences of segmenting the aperture and the effects of various segment spacings and random piston and tilt errors of the individual segments. A system to correct for the misalignments is proposed. C1 CALTECH,JET PROP LAB,ATMOSPHER & COMETARY SCI SECT,PASADENA,CA 91109. RP WATSON, SM (reprint author), 4950TH TEST WING,4950TW-FFCE,WRIGHT PATTERSON AFB,OH 45433, USA. NR 17 TC 20 Z9 20 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 1 PY 1991 VL 30 IS 22 BP 3253 EP 3262 PG 10 WC Optics SC Optics GA FY055 UT WOS:A1991FY05500028 PM 20706384 ER PT J AU HOCHSTEIN, LI LANG, F AF HOCHSTEIN, LI LANG, F TI PURIFICATION AND PROPERTIES OF A DISSIMILATORY NITRATE REDUCTASE FROM HALOFERAX-DENITRIFICANS SO ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS LA English DT Article ID EXTREMELY HALOPHILIC BACTERIA; ESCHERICHIA-COLI; PARACOCCUS-DENITRIFICANS; KLEBSIELLA-AEROGENES; DEAD-SEA; SP-NOV; HALOBACTERIUM; ENZYME; SOLUBILIZATION; DEHYDROGENASE C1 UNIV SANTA CLARA,DEPT BIOL,SANTA CLARA,CA 95053. RP HOCHSTEIN, LI (reprint author), NASA,AMES RES CTR,PLANETARY BIOL BRANCH 2394,MOFFETT FIELD,CA 94035, USA. NR 46 TC 26 Z9 27 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 0003-9861 J9 ARCH BIOCHEM BIOPHYS JI Arch. Biochem. Biophys. PD AUG 1 PY 1991 VL 288 IS 2 BP 380 EP 385 DI 10.1016/0003-9861(91)90210-A PG 6 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA FV096 UT WOS:A1991FV09600011 PM 1654831 ER PT J AU KURTHS, J BENZ, AO ASCHWANDEN, MJ AF KURTHS, J BENZ, AO ASCHWANDEN, MJ TI THE ATTRACTOR DIMENSION OF SOLAR DECIMETRIC RADIO PULSATIONS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE SOLAR RADIO EMISSION; DECIMETRIC PULSATIONS; DETERMINISTIC CHAOS; CORRELATION DIMENSION; PLASMAS; SUN, X-RAYS; SOLAR FLARES ID SMALL DATA SETS; STRANGE ATTRACTORS; SYSTEMS; SPECTRA; BURSTS; CHAOS; FLARE AB We have analyzed the temporal characteristics of decimetric pulsations and related radio emissions during solar flares. Since the flux variations in general are not periodic, we make use of the statistical methods recently developed for nonlinear, dynamic systems. The quantitative characterization of 20 pulsation events gives good evidence that they typically have their origin in deterministic chaos corresponding to motion on a strange attractor of low dimensionality. The correlation dimension in general turned out to be a useful way to quantify the regularity and hidden order of the irregular or quasi-periodic pulsations. To judge the reliability of its estimate even from rather small data samples, we have studied an optimum choice of the algorithmic parameters as well as experimented with known models. The correlation dimension has generally been found to be in the range 2.5-3.5. A metric periodic oscillation and an extraordinarily regular event of "sudden reductions" have yielded a dimension of 2, and modulations on two type IV continua exhibited dimension around 4. These findings suggest that the source of pulsating emissions in the simplest case can be described by the orbit of a point in a three dimensional phase space. In more complicated events, coinciding in general with more powerful energy release, four up to eight free parameters characterize the source. C1 SWISS FED INST TECHNOL, INST ASTRON, CH-8092 ZURICH, SWITZERLAND. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP KURTHS, J (reprint author), ZENT INST ASTROPHYS, O-1501 TREMSDORF, GERMANY. NR 31 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 AUG PY 1991 VL 248 IS 1 BP 270 EP 276 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GC358 UT WOS:A1991GC35800041 ER PT J AU HELOU, G RYTER, C SOIFER, BT AF HELOU, G RYTER, C SOIFER, BT TI VERY SMALL GRAINS AND THE INFRARED COLORS OF GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article ID VIRGO CLUSTER AREA; INTERSTELLAR DUST; AROMATIC-MOLECULES; IRAS OBSERVATIONS; MICRON SPECTRUM; EMISSION; PARTICLES; CLOUDS; SAMPLE; M82 AB We use IRAS data to study the contribution of very small grains with fluctuating temperature to the infrared emission of disk galaxies and to estimate the variation among galaxies of the abundance of these small grains relative to the larger "classical," thermally stable grains. We argue that the 12-mu-m emission from spiral galaxies originates in their interstellar medium and compare the integrated IRAS colors of galaxies to the IRAS colors of local emission with Galactic nebulae. GAMMA = nu-f-nu-(12-mu-m)/F(40-120-mu-m) is advanced as an estimator of the small-to-large grain ratio, and the interpretation of its statistical behavior in samples of galaxies is discussed. In a color-color diagram of the emission from Galactic nebulae, GAMMA-depends only on THETA = f-nu-(60-mu-m)/f-nu-(100-mu-m), decreasing slowly as THETA-increases. The same trend is observed for the integrated colors of galaxies and is seen in three different samples: optically selected "normal" spirals in the Virgo cluster, infrared-luminous galaxies from the IRAS bright galaxy sample and "cold" galaxies selected for their low ratios of f-nu-(60-mu-m) to f-nu-(100-mu-m). The dispersion on GAMMA is small (rms congruent-to 40%) for THETA < 1/3, and increases to about a factor of 2 at THETA congruent-to 1. We argue that the low dispersion in the "cold" galaxies represents the true dispersion in the small-to-large grain abundance ratio among galaxies, while the larger dispersion among warmer galaxies is a result of increasing effects of optical depth heating of dust by active galactic nuclei, and destruction of small dust grains at high radiative energy densities. The small-to-large grain ratio is found to be roughly constant among normal galaxies with similar metallicities, with a rms dispersion of 40% or less. C1 CENS,SERV ASTROPHYS,F-91190 GIF SUR YVETTE,FRANCE. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. CALTECH,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. RP HELOU, G (reprint author), CALTECH,JET PROP LAB,INFRARED PROC & ANAL CTR,PASADENA,CA 91109, USA. NR 52 TC 35 Z9 35 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1991 VL 376 IS 2 BP 505 EP 513 DI 10.1086/170299 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FY359 UT WOS:A1991FY35900012 ER PT J AU SANDFORD, SA AF SANDFORD, SA TI THE SPECTRUM OF NGC-7027 FROM 3080 TO 2630 WAVE-NUMBERS (3.25-3.80 MICRONS) - DETECTION OF NEW ATOMIC AND MOLECULAR-HYDROGEN LINES AND NEW CONSTRAINTS ON THE CHEMICAL SIDEGROUPS ON POLYCYCLIC AROMATIC-HYDROCARBONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, GRAINS; LINE IDENTIFICATIONS; NEBULAE, INDIVIDUAL (NGC-7027); NEBULAE, PLANETARY ID EMISSION FEATURES; IRAS SOURCES; NGC 7027; SPECTROSCOPY; BENZENE; REGION; DUST AB An infrared spectrum of NGC 7027, with a resolving power of 890-930 over the 2790-2690 cm-1 (3.58-3.72-mu-m) range, is presented which shows several emission lines due to atomic and molecular hydrogen. Three of the lines fall near 2773, 2743, and 2710 cm-1 (3.606, 3.645, and 3.690-mu-m) and are identified with the (20 --> 6), (19 --> 6), and (18 --> 6) Humphreys series transitions of atomic hydrogen, respectively. The strengths of these lines are consistent with those expected from the observed intensity of the Pfund-gamma (8 --> 5) line in this object. The fourth line falls near 2760 cm-1 (3.623-mu-m) and is tentatively identified with the (0 --> 0) S(15) transition of molecular hydrogen. It is not presently clear whether the strength of the newly observed (0 --> 0) S(15) H-2 line relative to the previously detected H-2 lines in this object is consistent with shock excitation or fluorescence from clumpy photodissociation regions. It is difficult to reconcile the relative strengths of the 3040, 2940, 2890, and 2850 cm-1 (3.29, 3.40, 3.46, and 3.51-mu-m) emission features in the spectrum of NGC 7027 with an origin in aliphatic sidegroups on polycyclic aromatic hydrocarbons (PAHs). The inconsistencies in the sidegroup model are minimized (but not eliminated) if the sidegroups are assumed to consist predominantly of methyl (-CH3) groups. The absence of an emission feature centered near 2740 cm-1 (3.65-mu-m), which is characteristic of methyl groups attached to aromatics, places a severe upper limit on the number of methyl sidegroups that can be present in this object. If methyl groups are present at all, this upper limit implies that the PAH population in NGC 7027 must contain at least 400 peripheral aromatic C-H bonds for every peripheral methyl group. This -CH3 abundance is a factor of 2-12 times too low to explain the strengths of the 2940, 2890, and 2850 cm-1 (3.40, 3.46, and 3.51-mu-m) features in the context of aliphatic sidegroups. Together these inconsistencies strongly indicate that the 2940, 2890, and 2850 cm-1 (3.40, 3.46, and 3.51-mu-m) interstellar emission features are not predominantly due to aliphatic sidegroups on PAHs. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 36 TC 19 Z9 19 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 AUG 1 PY 1991 VL 376 IS 2 BP 599 EP 607 DI 10.1086/170307 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FY359 UT WOS:A1991FY35900020 ER PT J AU ANDRE, P PHILLIPS, RB LESTRADE, JF KLEIN, KL AF ANDRE, P PHILLIPS, RB LESTRADE, JF KLEIN, KL TI DIRECT VLBI DETECTION OF THE MAGNETOSPHERE SURROUNDING THE YOUNG STAR-S1 IN RHO-OPHIUCHI SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, INDIVIDUAL (RHO-OPHIUCHI); POLARIZATION; STARS, PRE-MAIN SEQUENCE; STARS, RADIO RADIATION ID DARK-CLOUD; RADIO-EMISSION; ELECTRONS AB We have used the US VLBI network to investigate the circularly polarized radio core previously identified around the young B3 star S1 in rho Ophiuchi. Our 6 cm VLBI data indicate that the source is clearly detected and very likely resolved. The measured angular diameter (1.6(-0.6)+0.4 mas, equivalent to 12.8(-4.8)+2.4 stellar radii) and brightness temperature (1.5(+2.4)-0.4 x 10(8) K) are consistent with the emission being gyrosynchrotron radiation from mildly relativistic electrons. This is the first VLBI detection of a young stellar object still embedded in a star-forming region. The presence of a large-scale, organized magnetosphere around S1, several stellar radii in size, which was predicted in our previous paper (Andre et al.) by analogy with chemically peculiar magnetic stars, is now directly established. The present observations, together with previous VLBI observations of the Bp star sigma Ori E (Phillips & Lestrade), improve our knowledge on the structure of the magnetospheres around magnetic stars. A simple model, based on a pole-on dipolar magnetic field of approximately 2 kG at the stellar surface, appears to be consistent with the main observed characteristics of the S1 magnetosphere (radio size and spectrum, and X-ray emission). An important feature of this model is that it takes into account the influence of the X-ray emitting plasma on the radio emission. As other young radio stars, of lower mass but sharing several properties of S1, have been found in rho Oph, we suggest that S1 may be representative of a new type of young stellar object characterized by very extended magnetic fields. C1 MIT,HAYSTACK OBSERV,WESTFORD,MA 01886. CALTECH,JET PROP LAB,PASADENA,CA 91109. OBSERV PARIS,F-92195 MEUDON,FRANCE. RP ANDRE, P (reprint author), NATL RADIO ASTRON OBSERV,CAMPUS BLDG 65,949 N CHERRY AVE,TUCSON,AZ 85721, USA. NR 25 TC 28 Z9 28 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 AUG 1 PY 1991 VL 376 IS 2 BP 630 EP 635 DI 10.1086/170311 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FY359 UT WOS:A1991FY35900024 ER PT J AU LYNCH, JP KAFATOS, M AF LYNCH, JP KAFATOS, M TI FORBIDDEN LINES OF NPQ IONS .2. LINE-INTENSITIES SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ATOMIC PROCESSES ID COSMIC GAS; EMISSION; SPECTRUM; HOT AB Ground state forbidden transitions of np(q) ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV, visible, and near- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include those used to calculate the line ratios as well as other strong lines of the ions in the ground state terms in the same temperature and density ranges treated previously. These data can be used for calculations of the absolute line intensities if the ionic abundances are known. We have also graphed 25 of the most interesting cases. These calculations are important for studies of the solar transition region, ionized nebulae, circumstellar nebulae such as found in symbiotic stars, supernova remnants, interstellar bubbles produced by stellar winds, and emission regions in active galactic nuclei. C1 GEORGE MASON UNIV,INST COMPUTAT SCI & INFORMAT,FAIRFAX,VA 22030. GEORGE MASON UNIV,DEPT PHYS,FAIRFAX,VA 22030. RP LYNCH, JP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV FLIGHT DYNAM,CODE 5531,GREENBELT,MD 20771, USA. NR 18 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1991 VL 76 IS 4 BP 1169 EP 1191 DI 10.1086/191595 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ247 UT WOS:A1991FZ24700007 ER PT J AU CONNORS, VS CAHOON, DR REICHLE, HG SCHEEL, HE AF CONNORS, VS CAHOON, DR REICHLE, HG SCHEEL, HE TI COMPARISON BETWEEN CARBON-MONOXIDE MEASUREMENTS FROM SPACEBORNE AND AIRBORNE PLATFORMS SO CANADIAN JOURNAL OF PHYSICS LA English DT Article ID CHEMISTRY AB The measurement of air pollution from satellites (MAPS) experiment measured the distribution of middle tropospheric carbon monoxide (CO) from the space shuttle during October 1984. A critical area of the experiment is the assessment of experimental error of the MAPS data. This error is determined by the comparison between the space-based CO data and concurrent, direct CO measurements taken aboard aircraft. Because of the variability in the CO measurements near land sources, a strategy for comparing the tropospheric CO measurements over the remote oceans is presented. C1 FRAUNHOFER INST ATMOSPHAR UMWELTFORSCH,W-8100 GARMISCH PARTENKIR,GERMANY. RP CONNORS, VS (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. RI Garmisch-Pa, Ifu/H-9902-2014 NR 13 TC 11 Z9 11 U1 0 U2 0 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4204 J9 CAN J PHYS JI Can. J. Phys. PD AUG-SEP PY 1991 VL 69 IS 8-9 BP 1128 EP 1137 PG 10 WC Physics, Multidisciplinary SC Physics GA GR975 UT WOS:A1991GR97500029 ER PT J AU MURPHY, SC GUNNINGBERG, P KELLY, JPJ AF MURPHY, SC GUNNINGBERG, P KELLY, JPJ TI EXPERIENCES WITH ESTELLE, LOTOS AND SDL - A PROTOCOL IMPLEMENTATION EXPERIM ENT SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article DE FORMAL PROTOCOL SPECIFICATION; PROTOCOL IMPLEMENTATION; FAULT-TOLERANCE; TESTING; ADA ID DESIGN DIVERSITY AB A controlled experiment was conducted in which six protocol implementations were developed. They were derived by integrating two protocols specified with the ISO and CCITT Formal Description Techniques (FDTs) Estelle, LOTOS, and SDL. The implementations were written in the Ada programming language by six independent programming teams (two teams worked from each FDT). Experience with the specifications is presented: in particular, how readable and precise the teams found their specifications and how they mapped the specifications into Ada constructs. Results are also presented concerning the number and classification of implementation faults. Experience using Ada, particularly its concurrency features and the efficiency of the implementation, is also included. C1 SWEDISH INST COMP SCI,COMP ARCHITECTURES COMMUN RES GRP,STOCKHOLM,SWEDEN. UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106. CALTECH,JET PROP LAB,DIV MISSION OPERAT,TECH STATE,PASADENA,CA 91109. NR 16 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD AUG PY 1991 VL 22 IS 1 BP 51 EP 59 DI 10.1016/0169-7552(91)90081-M PG 9 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA GJ727 UT WOS:A1991GJ72700004 ER PT J AU GORDON, DM MATSON, PA AF GORDON, DM MATSON, PA TI INTERACTIONS OF BEHAVIORAL AND EVOLUTIONARY ECOLOGY IN CHANGING ENVIRONMENTS - SPECIAL FEATURE SO ECOLOGY LA English DT Editorial Material DE ALTERNATIVE TACTICS; CHANGING ENVIRONMENTS; COHO SALMON; CONDITIONAL STRATEGY; DENSITY DEPENDENCE; FORAGING; FREQUENCY DEPENDENCE; FUNCTIONAL RESPONSE; HANDLING TIMES; HABITAT SELECTION; LIFE-HISTORY TACTICS; NONLINEARITY; PHENOTYPIC PLASTICITY; SEED-EATING ANTS; TEMPORAL HETEROGENEITY; TIME-DEPENDENT BEHAVIOR C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL,CTR POPULAT BIOL,ASCOT SL5 7PY,BERKS,ENGLAND. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 2 Z9 2 U1 0 U2 2 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE, NW, STE 400, WASHINGTON, DC 20036 SN 0012-9658 J9 ECOLOGY JI Ecology PD AUG PY 1991 VL 72 IS 4 BP 1179 EP 1179 DI 10.2307/1941090 PG 1 WC Ecology SC Environmental Sciences & Ecology GA GB185 UT WOS:A1991GB18500001 ER PT J AU RYER, CH OLLA, BL AF RYER, CH OLLA, BL TI AGONISTIC BEHAVIOR IN A SCHOOLING FISH - FORM, FUNCTION AND ONTOGENY SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE AGGRESSION; DOMINANCE; FEEDING BEHAVIOR; SCHOOLING; ONCORHYNCHUS-KETA ID SALMON ONCORHYNCHUS-KETA; SALVELINUS-ALPINUS L; ARCTIC CHARR; GROWTH; SEAWATER; ECOLOGY; ESTUARY AB Although juvenile chum salmon, Oncorhynchus keta, are generally regarded as a schooling fish, when presented with a defensible point-source of food, some individuals abandon schooling, aggressively subordinate competitors, and monopolize food. When food is removed, fish gradually abandon solitary agonistic behaviors and return to schooling behavior. Agonism increases in frequency and intensity as juveniles age. The ability to alternate facultatively between schooling and solitary agonistic behavior may enable juvenile chum to respond to local patterns of food distribution and predation risk. The ontogenetic increase in agonism may result in school dispersal as fish move from the estuary into coastal waters, and may well reflect a shift in the costs versus the benefits of schooling as fish mature and become less vulnerable to predation. C1 NOAA,NATL MARINE FISHERIES SERV,COOPERAT INST MARINE RES STUDIES,ALASKA FISHERIES SCI CTR,NEWPORT,OR 97365. RP RYER, CH (reprint author), OREGON STATE UNIV,HATFIELD MARINE SCI CTR,NEWPORT,OR 97365, USA. NR 25 TC 37 Z9 37 U1 1 U2 7 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD AUG PY 1991 VL 31 IS 4 BP 355 EP 363 DI 10.1007/BF00002360 PG 9 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA FZ063 UT WOS:A1991FZ06300005 ER PT J AU HEIFETZ, J FUJIOKA, JT AF HEIFETZ, J FUJIOKA, JT TI MOVEMENT DYNAMICS OF TAGGED SABLEFISH IN THE NORTHEASTERN PACIFIC SO FISHERIES RESEARCH LA English DT Article; Proceedings Paper CT SYMP AT THE 119TH ANNUAL MEETING OF THE AMERICAN FISHERIES SOC - FISH POPULATION DYNAMICS - SOLVING FISHERY MANAGEMENT PROBLEMS CY SEP, 1989 CL ANCHORAGE, AK SP AMER FISHERIES SOC AB We used a Markov model to quantify movement rates of tagged sablefish (Anoplopoma fimbria) among regulatory areas of the North Pacific Fishery Management Council during 1979-1987. The model included natural and fishing mortality, tag reporting and shedding rates, and movement probabilities. Maximum likelihood was used to estimate the parameters of the model. Estimated annual movement rates out of an area were in the range 19-69% for small (less than 57 cm fork length (FL)), 25-72% for medium (57-66 cm FL), and 27-71% for large (more than 66 cm FL) sablefish. The predominant direction of movement along the continental slope was eastward for large sablefish and westward for small sablefish. Most estimates of movement rates were precise, unconfounded, and robust to perturbations of input constants (natural and fishing mortality, and tag reporting rates), except for some imprecise estimates of large sablefish. The results indicate that movement plays an important role in determining the amount of sablefish available for harvest in an area. To account for the interactions among fisheries in different areas, the movement dynamics of sablefish should be incorporated into a stock assessment based on size or age-structure. RP HEIFETZ, J (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 0 TC 28 Z9 29 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-7836 J9 FISH RES JI Fish Res. PD AUG PY 1991 VL 11 IS 3-4 BP 355 EP 374 DI 10.1016/0165-7836(91)90009-5 PG 20 WC Fisheries SC Fisheries GA GD734 UT WOS:A1991GD73400009 ER PT J AU HERRERO, FA BAKER, DN GOLDBERG, RA AF HERRERO, FA BAKER, DN GOLDBERG, RA TI ROCKET MEASUREMENTS OF RELATIVISTIC ELECTRONS - NEW FEATURES IN FLUXES, SPECTRA AND PITCH ANGLE DISTRIBUTIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; MAGNETOSPHERE AB We report new features of precipitating relativistic electron fluxes measured on a spinning sounding rocket payload at midday between altitudes of 70 and 130 km in the auroral region (Poker Flat, Alaska, 65.1-degrees-N, 147.5-degrees-W, and L = 5.5). The sounding rocket (NASA 33.059) was launched at 21:29 UT on May 13, 1990 during a relativistic electron enhancement event of modest intensity. Electron fluxes were measured for a total of about 210 seconds at energies from 0.1 to 3.8 MeV, while pitch angle was sampled from 0-degrees to 90-degrees every spin cycle. Flux levels during the initial 90 seconds were about 5 to 8 times higher than in the next 120 seconds, revealing a time scale of more than 100 seconds for large amplitude intensity variations. A shorter time scale appeared for downward electron bursts lasting 10 to 20 seconds. Electrons with energies below about 0.2 MeV showed isotropic pitch angle distributions during most of the first 90 seconds of data, while at higher energies the electrons had highest fluxes near the mirroring angle (90-degrees); when they occurred, the noted downward bursts were seen at all energies. Data obtained during the second half of the flight showed little variation in the shape of the pitch angle distribution for energies greater than 0.5 MeV; the flux at 90-degrees was about 100 times the flux at 0-degrees. We have compared the low altitude fluxes with those measured at geostationary orbit (L = 6.6), and find that the low altitude fluxes are much higher than expected from a simple mapping of a pancake distribution at high altitudes (at the equator). Energy deposition of this modest event is estimated to increase rapidly above 45 km, already exceeding the cosmic ray background at 45 km. RP HERRERO, FA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Goldberg, Richard /E-1881-2012 NR 11 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 AUG PY 1991 VL 18 IS 8 BP 1481 EP 1484 DI 10.1029/91GL01300 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000028 ER PT J AU DELCOURT, DC MOORE, TE SAUVAUD, JA AF DELCOURT, DC MOORE, TE SAUVAUD, JA TI GYRO-PHASE EFFECTS NEAR THE STORM-TIME BOUNDARY OF ENERGETIC PLASMA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The non-adiabatic acceleration of plasma sheet ions during the expansion phase of substorms is examined by means of single-particle codes. It is shown that, in the near-Earth plasma sheet, the gyration phase at substorm onset controls the net ion energization, as the gyro-period is locally comparable to the field variation time scale. This can yield a particularly significant decrease of the particle magnetic moment. It is accordingly argued that, via adiabatic invariant violation, the dipolarization of magnetospheric field lines can induce a "de-trapping" of inner plasma sheet populations and, hence, give rise to short-lived precipitation enhancements over the auroral zone. As this effect depends upon cyclotron frequency, it is expected to occur at distinct latitudes for different ion species. This contrasts with non-adiabatic ion behavior further out into the geotail, which is characterized by intense perpendicular heating and a likely collective trapping. C1 CESR,CNRS,TOULOUSE,FRANCE. RP DELCOURT, DC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 9 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 AUG PY 1991 VL 18 IS 8 BP 1485 EP 1488 DI 10.1029/91GL01526 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000029 ER PT J AU GOLDSTEIN, ML ROBERTS, DA FITCH, CA AF GOLDSTEIN, ML ROBERTS, DA FITCH, CA TI THE STRUCTURE OF HELICAL INTERPLANETARY MAGNETIC-FIELDS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AMPLITUDE ALFVEN WAVES; SOLAR-WIND; TURBULENCE AB The interplanetary magnetic field is known to be highly helical. Although the detailed spatial structure of the fields has yet to be elucidated, the helicity spectrum has been conjectured to result from a random walk in direction of a constant magnitude magnetic field vector. We demonstrate that a model using three-dimensional fluctuations with variations in \B\ gives a good fit to the helicity spectrum as well as to other properties of the interplanetary magnetic field. RP GOLDSTEIN, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008 NR 22 TC 12 Z9 12 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 AUG PY 1991 VL 18 IS 8 BP 1505 EP 1508 DI 10.1029/91GL01608 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000034 ER PT J AU ASHOURABDALLA, M BAKER, DN AF ASHOURABDALLA, M BAKER, DN TI CHAOS AND STOCHASTICITY IN SPACE PLASMAS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ASHOURABDALLA, M (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024, USA. NR 0 TC 5 Z9 5 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 AUG PY 1991 VL 18 IS 8 BP 1573 EP 1574 DI 10.1029/91GL01904 PG 2 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000051 ER PT J AU BAKER, DN KLIMAS, AJ ROBERTS, DA AF BAKER, DN KLIMAS, AJ ROBERTS, DA TI EXAMINATION OF TIME-VARIABLE INPUT EFFECTS IN A NONLINEAR ANALOG MAGNETOSPHERE MODEL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GEOMAGNETIC-ACTIVITY; SOLAR-WIND; SUBSTORMS; ENERGY AB Our previously developed nonlinear dynamical models of the magnetosphere exhibit deterministic chaotic behavior as the solar wind input which drives the systems increases from low to high levels. In this paper we employ the plasma physical analogue model (an extention of the damped, harmonic-oscillator dripping faucet model) to consider explicitly the effect of time-varying the inputs. This work is equivalent to considering the effects of northward and southward turnings of the interplanetary magnetic field for various periods of time. We find that relatively extended episodes (greater-than-or-equal-to 2 hours) of turned on input with shorter (approximately 1 hour) periods of turned off input lead to model behavior much like the continuously driven case. However, going to short input intervals with longer periods of zero input leads to highly irregular and dramatically fluctuating episodes of magnetotail unloading. These results give us insight into the diversity of apparent magnetospheric responses during relatively isolated substorm conditions. This work shows the absolutely critical interdependence (in a nonlinear dynamical system) of input phasing and internal magnetospheric response cycles. RP BAKER, DN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 8 TC 11 Z9 11 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG PY 1991 VL 18 IS 8 BP 1631 EP 1634 DI 10.1029/91GL01048 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000066 ER PT J AU KLIMAS, AJ BAKER, DN ROBERTS, DA AF KLIMAS, AJ BAKER, DN ROBERTS, DA TI LINEAR PREDICTION FILTERS FOR LINEAR AND NONLINEAR MODELED GEOMAGNETIC-ACTIVITY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SUBSTORMS; CHAOS; AE AB It is shown that the Faraday loop analogue model of geomagnetic activity exhibits both the directly driven and loading-unloading magnetospheric responses to solar wind input. It is further shown that the directly driven component is a linear response to loading while the loading-unloading response is nonlinear. Linear prediction filters which relate model input to output are discussed. By either allowing or suppressing the loading-unloading model response, filters that relate to nonlinear or linear dynamics, respectively, have been computed. Filters that describe the directly driven response are finite ranged; they asymptote to zero with increasing lag on a time scale that is fixed by the dissipation rate of the model. Filters that describe the nonlinear total response are infinite ranged; they asymptote with increasing lag to large amplitude periodic oscillations. Some implications of these infinite ranged filters are discussed. RP KLIMAS, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 13 TC 12 Z9 12 U1 1 U2 3 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 AUG PY 1991 VL 18 IS 8 BP 1635 EP 1638 DI 10.1029/91GL01148 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000067 ER PT J AU BURLAGA, LF AF BURLAGA, LF TI MULTIFRACTAL STRUCTURE OF SPEED FLUCTUATIONS IN RECURRENT STREAMS AT 1-AU AND NEAR 6-AU SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB This paper demonstrates the existence of multifractal structure in the velocity fluctuations associated with recurrent streams at 1 AU and near 6 AU. There is a significant evolution of the multifractal spectrum from 1 AU to 6 AU. At 1 AU the fluctuations on all scales in the indicated range are related to the local speed gradients associated with the stream structure. Near 6 AU the multifractal structure of the speed fluctuations approaches the universal form for intermittent turbulence for moments q > 5, and it has approximately the value expected for a set of discontinuities for q = 2. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 17 TC 56 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 AUG PY 1991 VL 18 IS 8 BP 1651 EP 1654 DI 10.1029/91GL01221 PG 4 WC Geosciences, Multidisciplinary SC Geology GA GB150 UT WOS:A1991GB15000071 ER PT J AU KORYCANSKY, DG BODENHEIMER, P POLLACK, JB AF KORYCANSKY, DG BODENHEIMER, P POLLACK, JB TI NUMERICAL-MODELS OF GIANT PLANET FORMATION WITH ROTATION SO ICARUS LA English DT Article ID SOLAR NEBULA; EVOLUTION; JUPITER; ACCRETION; FLOW C1 UNIV CALIF OBSERV,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. RP KORYCANSKY, DG (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 27 TC 22 Z9 22 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1991 VL 92 IS 2 BP 234 EP 251 DI 10.1016/0019-1035(91)90048-X PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA979 UT WOS:A1991GA97900005 ER PT J AU ESPENAK, F MUMMA, MJ KOSTIUK, T ZIPOY, D AF ESPENAK, F MUMMA, MJ KOSTIUK, T ZIPOY, D TI GROUND-BASED INFRARED MEASUREMENTS OF THE GLOBAL DISTRIBUTION OF OZONE IN THE ATMOSPHERE OF MARS SO ICARUS LA English DT Article ID ULTRAVIOLET SPECTROMETER EXPERIMENT; MARTIAN ATMOSPHERE; HETERODYNE SPECTROSCOPY; SEASONAL-VARIATION; NATURAL LASER; O-2 DAYGLOW; DUST; STABILITY; MARINER-9; ABUNDANCE C1 UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. RP ESPENAK, F (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,PLANETARY SYST BRANCH,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013; Kostiuk, Theodor/A-3077-2014 NR 42 TC 42 Z9 42 U1 2 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 AUG PY 1991 VL 92 IS 2 BP 252 EP 262 DI 10.1016/0019-1035(91)90049-Y PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA979 UT WOS:A1991GA97900006 ER PT J AU BURATTI, BJ AF BURATTI, BJ TI GANYMEDE AND CALLISTO - SURFACE TEXTURAL DICHOTOMIES AND PHOTOMETRIC ANALYSIS SO ICARUS LA English DT Article ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; DISK-INTEGRATED PHOTOMETRY; GALILEAN SATELLITES; VOYAGER PHOTOMETRY; RADIATIVE-TRANSFER; ICY SATELLITES; EUROPA; ALBEDO; IO; POLARIMETRY RP BURATTI, BJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 68 TC 42 Z9 42 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1991 VL 92 IS 2 BP 312 EP 323 DI 10.1016/0019-1035(91)90054-W PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA979 UT WOS:A1991GA97900011 ER PT J AU ZAK, M AF ZAK, M TI AN UNPREDICTABLE-DYNAMICS APPROACH TO NEURAL INTELLIGENCE SO IEEE EXPERT-INTELLIGENT SYSTEMS & THEIR APPLICATIONS LA English DT Article ID TERMINAL ATTRACTORS; NETWORKS RP ZAK, M (reprint author), CALTECH,JET PROP LAB,CTR MICROELECTR TECHNOL,NEURAL COMPUTAT & NONLINEAR SCI GRP,PASADENA,CA 91109, USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0885-9000 J9 IEEE EXPERT JI IEEE Expert-Intell. Syst. Appl. PD AUG PY 1991 VL 6 IS 4 BP 4 EP 10 DI 10.1109/64.85916 PG 7 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GB778 UT WOS:A1991GB77800002 ER PT J AU WHITAKER, SR MANJUNATH, SK MAKI, GK AF WHITAKER, SR MANJUNATH, SK MAKI, GK TI SEQUENCE-INVARIANT STATE MACHINES SO IEEE JOURNAL OF SOLID-STATE CIRCUITS LA English DT Article AB A synthesis method and an MOS VLSI architecture are presented to realize sequential circuits that have the ability to implement any state machine having N states and m inputs, regardless of the acutal sequence specified in the flow table. The design method utilizes binary tree structured (BTS) logic to implement regular and dense circuits. The desired state sequence can be hardwired with power supply connections or can be dynamically reallocated if stored in a register. This allows programmable VLSI controllers to be designed with a compact size and performance approaching that of dedicated logic. Results of IC implementations are reported and an example sequence-invariant state machine is contrasted with implementations based on traditional methods. RP WHITAKER, SR (reprint author), UNIV IDAHO,NASA,SPACE ENGN RES CTR VLSI SYST DESIGN,MOSCOW,ID 83843, USA. NR 11 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 0018-9200 J9 IEEE J SOLID-ST CIRC JI IEEE J. Solid-State Circuit PD AUG PY 1991 VL 26 IS 8 BP 1145 EP 1151 DI 10.1109/4.90067 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA FW510 UT WOS:A1991FW51000010 ER PT J AU MANSHADI, F AF MANSHADI, F TI END-LOADED CROSSED-SLOT RADIATING ELEMENTS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB Three cavity-backed crossed-slot antenna configurations are described that offer simple design, easy frequency tuning, and are lightweight, low lost, and low cost. These antennas are designed for mobile satellite (MSAT) vehicle phased-array applications. The slots in these antennas are end-loaded. The end loading makes the slots effectively longer, and hence reduces their resonant frequency. Therefore, relatively small radiating elements can be achieved for large-angle-scanning phased-array antennas. These antennas have good RF characteristics and provide a relatively wide bandwidth without needing external tuning circuits for impedance matching. Measurements for the return loss and the far-field pattern of these antennas are presented. RP MANSHADI, F (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 11 Z9 11 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 1991 VL 39 IS 8 BP 1237 EP 1240 DI 10.1109/8.97363 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GJ761 UT WOS:A1991GJ76100026 ER PT J AU MOOK, DJ LEW, JS AF MOOK, DJ LEW, JS TI MULTIPLE SHOOTING ALGORITHMS FOR JUMP-DISCONTINUOUS PROBLEMS IN OPTIMAL-CONTROL AND ESTIMATION SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note ID IDENTIFICATION AB Multiple shooting algorithms are developed for jump-discontinuous two-point boundary value problems arising in optimal control and optimal estimation. Examples illustrating the origin of such problems are given to motivate the development of the solution algorithms. The algorithms convert the necessary conditions, comprised of differential equations and transversality conditions, into algebraic equations. The solution of the algebraic equations provides exact solutions for linear problems. The existence and uniqueness of the solution is proven. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP MOOK, DJ (reprint author), SUNY BUFFALO,DEPT MECH & AEROSP ENGN,BUFFALO,NY 14260, USA. NR 14 TC 9 Z9 9 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 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD AUG PY 1991 VL 36 IS 8 BP 979 EP 983 DI 10.1109/9.133193 PG 5 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA FY321 UT WOS:A1991FY32100010 ER PT J AU NGUYEN, TM AF NGUYEN, TM TI SPACE TELEMETRY DEGRADATION DUE TO MANCHESTER DATA ASYMMETRY INDUCED CARRIER TRACKING PHASE ERROR SO IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY LA English DT Article AB This paper presents the analytical models and associated analysis of the deleterious effects that the Manchester (or Bi-phi) data asymmetry has on the performance of phase-modulated residual carrier communication systems. Expressions for the power spectral density of an asymmetric Manchester data stream, an interference-to-carrier signal power ratio (I/C), and an error probability performance are derived. Since data asymmetry can cause undesired spectral components at the carrier frequency, the ratio I/C is given as a function of both the data asymmetry and the telemetry modulation index. Further, the data asymmetry and asymmetry-induced carrier tracking phase error effects on error probability are investigated. Numerical results that indicate the sensitivity of the carrier tracking loop and the system bit-error rate to various parameters of the models are presented. RP NGUYEN, TM (reprint author), CALTECH,JET PROP LAB,SYST RES SECT,DIGITAL SIGNAL PROC RES GRP,PASADENA,CA 91109, USA. NR 9 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 0018-9375 J9 IEEE T ELECTROMAGN C JI IEEE Trans. Electromagn. Compat. PD AUG PY 1991 VL 33 IS 3 BP 262 EP 268 DI 10.1109/15.85140 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FW970 UT WOS:A1991FW97000013 ER PT J AU KANTAK, AV AF KANTAK, AV TI A METHOD OF OBTAINING SIGNAL COMPONENTS AND THEIR POWER CONTENT OF A RESIDUAL CARRIER SIGNAL SO IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY LA English DT Note 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. RP KANTAK, AV (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 2 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 0018-9375 J9 IEEE T ELECTROMAGN C JI IEEE Trans. Electromagn. Compat. PD AUG PY 1991 VL 33 IS 3 BP 269 EP 270 DI 10.1109/15.85141 PG 2 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FW970 UT WOS:A1991FW97000014 ER PT J AU KINMAN, PW HINEDI, SM LABELLE, RC BEVAN, RP DELCASTILLO, HM CHONG, DC AF KINMAN, PW HINEDI, SM LABELLE, RC BEVAN, RP DELCASTILLO, HM CHONG, DC TI DIGITAL DOPPLER MEASUREMENT WITH SPACECRAFT SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB A digital and an analog phase-locked loop receiver were operated in parallel, each tracking the residual carrier from a spacecraft. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver, and this was due to its smaller noise bandwidth. RP KINMAN, PW (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 4 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 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD AUG PY 1991 VL 40 IS 4 BP 727 EP 731 DI 10.1109/19.85342 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA GB246 UT WOS:A1991GB24600011 ER PT J AU BIEDENBENDER, MD KAPOOR, VJ SHALKHAUSER, KA MESSICK, LJ NGUYEN, R SCHMITZ, D JURGENSEN, H AF BIEDENBENDER, MD KAPOOR, VJ SHALKHAUSER, KA MESSICK, LJ NGUYEN, R SCHMITZ, D JURGENSEN, H TI SUBMICRON-GATE INP POWER MISFETS WITH IMPROVED OUTPUT POWER-DENSITY AT 18 AND 20 GHZ SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID MICROWAVE; MESFETS; MM AB Presented here are the microwave characteristics at 18 and 20 GHz of submicron-gate indium phosphide (InP) metal-insulator-semiconductor field-effect transistors (MISFET's) for high output power density applications. InP power MISFET's were fabricated with 0.7-mu-m gate lengths, 0.2 mm gate widths, and drain-source spacings of 2, 3, and 5-mu-m. The output power density was investigated as a function of drain-source spacing. The best output power density and gain were obtained for drain-source spacings of 3-mu-m. At 18 GHz output power densities of 1.59 W/mm with a gain of 3.47 dB and a power-added efficiency of 20.0% were obtained for a drain-source spacing of 3-mu-m. At 20 GHz output power densities of 1.20 W/mm with a gain of 3.17 dB and a power-added efficiency of 13.6% were obtained for a drain-source spacing of 3-mu-m. The output power density is 2.7 times greater than has previously been measured for InP MISFET's at 18 and 20 GHz, and the power-added efficiency has also been increased. The output power density is also 50% better than recently reported for comparable gate width pseudomorphic HEMT's at 20 GHz. The power gain was stable to within 3.0% over 12 h, and the drain current variation during the same time was less than 5%. C1 AIXTRON CORP, AACHEN, GERMANY. NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. USN, CTR OCEAN SYST, SAN DIEGO, CA 92152 USA. RP UNIV CINCINNATI, DEPT ELECT & COMP ENGN, CINCINNATI, OH 45221 USA. NR 24 TC 6 Z9 6 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9480 EI 1557-9670 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD AUG PY 1991 VL 39 IS 8 BP 1368 EP 1375 DI 10.1109/22.85412 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA FV890 UT WOS:A1991FV89000015 ER PT J AU SUICH, RC PATTERSON, RL AF SUICH, RC PATTERSON, RL TI K-OUT-OF-N-G SYSTEMS - SOME COST CONSIDERATIONS SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE K-OUT-OF-N SYSTEM; MINIMIZING COST; REDUNDANCY; COST ANALYSIS AB How does an engineer designing a subsystem decide between one subsystem and a more reliable but more costly one? This paper provides a tool for the engineer to help make that choice. It provides methods for selecting redundancy levels in k-out-of-n:G systems in order to minimize particular cost considerations where the k-out-of-n:G system is a subsystem of a major system. The n and k are chosen to minimize the total cost of the subsystem plus the average loss due to subsystem failure. A BASIC program is available to determine the n and k which find this minimum. Five loss functions are considered, and illustrations are given. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SUICH, RC (reprint author), CALIF STATE UNIV FULLERTON,FULLERTON,CA 92634, USA. NR 2 TC 15 Z9 15 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 0018-9529 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD AUG PY 1991 VL 40 IS 3 BP 259 EP 263 DI 10.1109/24.85433 PG 5 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FZ972 UT WOS:A1991FZ97200004 ER PT J AU CHULYA, A WALKER, KP AF CHULYA, A WALKER, KP TI A NEW UNIFORMLY VALID ASYMPTOTIC INTEGRATION ALGORITHM FOR ELASTOPLASTIC CREEP AND UNIFIED VISCOPLASTIC THEORIES INCLUDING CONTINUUM DAMAGE SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID EQUATIONS AB A new scheme to integrate a system of stiff differential equations for both the elasto-plastic-creep and the unified viscoplastic theories is presented. The method has high stability, allows large time increments, and is implicit and iterative. It is suitable for use with continuum damage theories. The scheme was incorporated into MARC, a commercial finite element code, through a user subroutine called HYPELA. Results from numerical problems under complex loading histories are presented for both small and large scale analysis. To demonstrate the scheme's accuracy and efficiency, comparisons to a self-adaptive forward Euler method are made. C1 ENGN SCI SOFTWARE INC,SMITHFIELD,RI. RP CHULYA, A (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135, USA. NR 29 TC 8 Z9 9 U1 1 U2 2 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 AUG PY 1991 VL 32 IS 2 BP 385 EP 418 DI 10.1002/nme.1620320210 PG 34 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA FY863 UT WOS:A1991FY86300009 ER PT J AU ANTONIA, RA KIM, J AF ANTONIA, RA KIM, J TI REYNOLDS SHEAR-STRESS AND HEAT-FLUX CALCULATIONS IN A FULLY-DEVELOPED TURBULENT DUCT FLOW SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID BOUNDARY-LAYERS; CHANNEL FLOW; PRESSURE-GRADIENTS; SCHMIDT NUMBERS; WALL; PREDICTION; FORMULA; PRANDTL AB The use of a modified form of the Van Driest mixing length for a fully developed turbulent channel flow leads to mean velocity and Reynolds stress distributions that are in close agreement with data obtained either from experiments or direct numerical simulations. The calculations are then extended to a non-isothermal flow by assuming a constant turbulent Prandtl number, the value of which depends on the molecular Prandtl number. Calculated distributions of mean temperature and lateral heat flux are in reasonable agreement with the simulations. The extension of the calculations to higher Reynolds numbers provides some idea of the Reynolds number required for scaling on wall variables to apply in the inner region of the flow. C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. RP ANTONIA, RA (reprint author), UNIV NEWCASTLE,DEPT MECH ENGN,NEWCASTLE,NSW 2308,AUSTRALIA. NR 21 TC 4 Z9 4 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD AUG PY 1991 VL 34 IS 8 BP 2013 EP 2018 DI 10.1016/0017-9310(91)90212-W PG 6 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA GB171 UT WOS:A1991GB17100011 ER PT J AU GIBERSON, WE AF GIBERSON, WE TI SEASAT-A - A RETROSPECTIVE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB This paper traces the highlights of the Seasat-A project from its earliest conceptual phases through the orbital operations phase. The primary objective of the project was to demonstrate the feasibility of remotely sensing fundamental oceanographic phenomena on a global, accurate, reliable and timely basis from an Earth-orbiting platform. The project successfully achieved its primary objective, in spite of a premature spacecraft failure, and thus provided a firm basis for the development of sensors for future ocean-observing space missions. RP GIBERSON, WE (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE AVE,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 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 AUG PY 1991 VL 12 IS 8 BP 1613 EP 1617 PG 5 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA GD327 UT WOS:A1991GD32700002 ER PT J AU RODRIGUEZ, G JAIN, A KREUTZDELGADO, K AF RODRIGUEZ, G JAIN, A KREUTZDELGADO, K TI A SPATIAL OPERATOR ALGEBRA FOR MANIPULATOR MODELING AND CONTROL SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article ID ROBOT DYNAMICS AB A recently developed spatial operator algebra for manipulator modeling, control, and trajectory design is discussed. The elements of this algebra are linear operators whose domain and range spaces consist of forces, moments, velocities, and accelerations. The effect of these operators is equivalent to a spatial recursion along the span of a manipulator. Inversion of operators can be efficiently obtained via techniques of recursive filtering and smoothing. The operator algebra provides a high-level framework for describing the dynamic and kinematic behavior of a manipulator and for control and trajectory design algorithms. The interpretation of expressions within the algebraic framework leads to enhanced conceptual and physical understanding of manipulator dynamics and kinematics. Furthermore, implementable recursive algorithms can be immediately derived from the abstract operator expressions by inspection. Thus the transition from an abstract problem formulation and solution to the detailed mechanization of specific algorithms is greatly simplified. C1 UNIV CALIF SAN DIEGO,DEPT AMES,LA JOLLA,CA 92093. RP RODRIGUEZ, G (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 29 TC 119 Z9 124 U1 0 U2 9 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 0278-3649 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD AUG PY 1991 VL 10 IS 4 BP 371 EP 381 DI 10.1177/027836499101000406 PG 11 WC Robotics SC Robotics GA GA433 UT WOS:A1991GA43300006 ER PT J AU SHIEH, LG LIU, Z SUNKEL, JW AF SHIEH, LG LIU, Z SUNKEL, JW TI OPTIMAL UNIFORM-DAMPING RATIO CONTROLLER FOR SEQUENTIAL DESIGN OF MULTIVARIABLE SYSTEMS SO INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE LA English DT Article ID QUADRATIC REGULATORS; SPECIFIED REGION; PLACEMENT AB An optimal uniform-damping ratio controller is developed for the sequential design of a multivariable control system so that the designed closed-loop poles of the respective multivariable system and reduced-order observer are exactly placed on the negative real axis and/or the boundaries of desired sectors with constant-damping ratios. The functions in the quadratic performance index to be minimized are chosen as a combination of the weighted outputs, reduced states and inputs. Also, the optimal uniform-damping ratio controller is a combination of optimal output-feedback and optimal reduced-order state-feedback controllers. A numerical example is given to demonstrate the design procedure. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SHIEH, LG (reprint author), UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204, USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0020-7721 J9 INT J SYST SCI JI Int. J. Syst. Sci. PD AUG PY 1991 VL 22 IS 8 BP 1371 EP 1389 DI 10.1080/00207729108910715 PG 19 WC Automation & Control Systems; Computer Science, Theory & Methods; Operations Research & Management Science SC Automation & Control Systems; Computer Science; Operations Research & Management Science GA FY977 UT WOS:A1991FY97700003 ER PT J AU POWERS, SG AF POWERS, SG TI FLIGHT TESTS OF EXTERNAL MODIFICATIONS USED TO REDUCE BLUNT BASE DRAG SO JOURNAL OF AIRCRAFT LA English DT Article AB The effectiveness of a trailing disk (the trapped vortex concept) in reducing the blunt base drag of an 8-in. diameter body of revolution was studied from measurements made both in flight and in full-scale wind-tunnel tests. The experiment demonstrated the significant base drag reduction capability of the trailing disk to Mach 0.93. The maximum base drag reduction obtained from a cavity tested on the flight body of revolution was not significant. The effectiveness of a splitter plate and a vented-wall cavity in reducing the base drag of a quasi-two-dimensional fuselage closure was studied from base pressure measurements made in flight. The fuselage closure was between the two engines of the F-111 airplane, and, thus, the base pressures were in the presence of jet engine exhaust. For Mach numbers from 1.10 to 1.51, significant base drag reduction was provided by the vented-wall cavity configuration. The splitter plate was not considered effective in reducing base drag at any Mach number tested. RP POWERS, SG (reprint author), NASA,AMES RES CTR,DRYDEN FLIGHT RES FACIL,MAIL STOP XRP,POB 273,EDWARDS AFB,CA 93523, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD AUG PY 1991 VL 28 IS 8 BP 517 EP 525 DI 10.2514/3.46057 PG 9 WC Engineering, Aerospace SC Engineering GA GB035 UT WOS:A1991GB03500006 ER PT J AU RODGERS, EB CHANG, SW STOUT, J STERANKA, J SHI, JJ AF RODGERS, EB CHANG, SW STOUT, J STERANKA, J SHI, JJ TI SATELLITE-OBSERVATIONS OF VARIATIONS IN TROPICAL CYCLONE CONVECTION CAUSED BY UPPER-TROPOSPHERIC TROUGHS SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID ATLANTIC HURRICANE SEASON; ANGULAR-MOMENTUM; OUTFLOW LAYER; INTENSITY; INTENSIFICATION; ENVIRONMENT; FLUXES; MODEL AB The mutual adjustment between upper-tropospheric troughs and the structure of western Atlantic Tropical Cyclones Florence (1988) and Irene (1981) are analyzed using satellite and in situ data. Satellite-observed tracers (e.g., cirrus clouds, water vapor, and ozone) are used to monitor the circulation within the tropical cyclones' environment. The tropical cyclones' convection is inferred from satellite flown passive microwave and infrared sensors. In addition, numerical model simulations are used to analyze and interpret these satellite observations. The study suggests that the initiation and maintenance of intense convective outbreaks in these tropical cyclones during their mature stage are related to the channeling and strengthening of their outflow by upper-tropospheric troughs. The convection can be enhanced in response to the outflow jet-induced import of eddy relative angular momentum and ascending motion associated with the thermally direct circulation. The channeling and strengthening of the outflow occurs when the upper-tropospheric troughs are located in a favorable position relative to the tropical cyclones. Both Florence and Irene intensify after the onset of these intense convective episodes. Satellite observations also suggest that the cessation in the convection of the two tropical cyclones occurs when the upper-tropospheric troughs move near or over the tropical cyclones, resulting in the weakening of their outflow and the entrainment of dry upper-tropospheric air into their inner core. C1 USN,RES LAB,WASHINGTON,DC 20375. GEN SCI CORP,LAUREL,MD. N CAROLINA STATE UNIV,DEPT MARINE EARTH & ATMOSPHER SCI,RALEIGH,NC 27695. RP RODGERS, EB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,SEVERE STORMS BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 52 TC 25 Z9 26 U1 0 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1163 EP 1184 DI 10.1175/1520-0450(1991)030<1163:SOOVIT>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GB987 UT WOS:A1991GB98700010 ER PT J AU TIMMER, C SRIVASTAVA, SK HALL, TE FUCALORO, AF AF TIMMER, C SRIVASTAVA, SK HALL, TE FUCALORO, AF TI ENHANCED LINE EMISSION FROM LASER-PRODUCED PLASMAS SO JOURNAL OF APPLIED PHYSICS LA English DT Note ID ELECTRON-IMPACT; CROSS-SECTIONS; SPECTROSCOPY; IONIZATION; ATOMS AB This communication reports the first systematic study on background gas-induced, spectral line emission enhancement from laser-produced plasmas. Line emission from aluminum plasmas was enhanced by factors of up to 35 by the introduction of He, Ne, Xe, or N2. The enhancement has been attributed to three-body recombination. C1 CLAREMONT COLL,DEPT JOINT SCI,CLAREMONT,CA 91711. RP TIMMER, C (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 21 Z9 25 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 AUG 1 PY 1991 VL 70 IS 3 BP 1888 EP 1890 DI 10.1063/1.349466 PG 3 WC Physics, Applied SC Physics GA GA100 UT WOS:A1991GA10000124 ER PT J AU PFAFF, RF AF PFAFF, RF TI ROCKET OBSERVATIONS IN THE EQUATORIAL ELECTROJET - CURRENT STATUS AND CRITICAL PROBLEMS SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID WAVELENGTH PLASMA INSTABILITIES; GRADIENT DRIFT INSTABILITY; CROSS-FIELD INSTABILITY; POLAR E-REGION; RADAR OBSERVATIONS; 2-DIMENSIONAL TURBULENCE; THEORETICAL IMPLICATIONS; DENSITY IRREGULARITIES; INSITU MEASUREMENTS; COUNTER-ELECTROJET AB The current status of in-situ investigations in the equatorial electrojet is reviewed, including observations of zero-order electrodynamic and plasma parameters as well as measurements of plasma instabilities and 'turbulent-like' irregularities. Several key outstanding questions are discussed from the point of view of what future rocket-borne observations might help resolve. These include: (1) the relation of the vertical polarization field to the electrojet current and the electron number density; (2) investigation of the puzzling square shapes of the large amplitude kilometer-scale horizontal electric field structures and their modulation (limitation?) of the driving polarization electric field; (3) measurements of the complete (including lambda < 1 m) delta-E and delta-n primary two-stream wave spectrum (including phase velocity vs k) as a function of the driving d.c. electric field; (4) investigation of the intense vertical, meter-scale waves observed on the topside of the electrojet associated with horizontal laminar-like primary two-stream waves; (5) measurments of upgoing and downgoing secondary two-stream and gradient drift wave packets driven by delta-E x B drifts; (6) investigation of the non-linear meter-scale 'turbulence' with small mean phase velocities observed by radars at altitudes outside the regions of high Cowling conductivity (e.g. in the bottomside electrojet); and (7) investigation of wave-particle heating by the plasma instabilities. Future in-situ experiments are discussed that include new electric field probe arrangements and geometries designed to address these critical problem areas. Experiments such as these should be conducted in conjunction with ground-based radar backscatter measurements, both to ensure the desired launch conditions and to provide vital observations needed to successfully interpret the in-situ data. RP NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, CODE 696, GREENBELT, MD 20771 USA. RI Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 86 TC 17 Z9 17 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD AUG PY 1991 VL 53 IS 8 BP 709 EP 728 DI 10.1016/0021-9169(91)90123-O PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GR865 UT WOS:A1991GR86500005 ER PT J AU BUELL, JC AF BUELL, JC TI A HYBRID NUMERICAL-METHOD FOR 3-DIMENSIONAL SPATIALLY-DEVELOPING FREE-SHEAR FLOWS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID FAST FOURIER-TRANSFORM; MIXING LAYER; INSTABILITIES; CONVECTION RP BUELL, JC (reprint author), NASA,AMES RES CTR,CTR TURBULENCE RES,MS202A-1,MOFFETT FIELD,CA 94035, USA. NR 26 TC 22 Z9 22 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1991 VL 95 IS 2 BP 313 EP 338 DI 10.1016/0021-9991(91)90279-T PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FX297 UT WOS:A1991FX29700004 ER PT J AU ROBERTS, GO KORNFELD, DM FOWLIS, WW AF ROBERTS, GO KORNFELD, DM FOWLIS, WW TI PARTICLE ORBITS IN A ROTATING LIQUID SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BROWNIAN PARTICLES; FLOW AB Monodisperse latex microspheres ranging in size from submicrometer to several micrometers in diameter can be prepared in the laboratory. The uniformity of diameter is important for instrument calibration and other applications. However it has proved very difficult to manufacture commercial quantities of monodisperse latex microspheres with diameters larger than about 3 micrometers owing to buoyancy and sedimentation effects. In an attempt to eliminate these effects NASA sponsored a Space Shuttle experiment called the Monodisperse Latex Reactor (MLR) to produce these monodisperse microspheres in larger sizes in microgravity. Results have been highly successful. Using technology gained from this space experiment, a ground-based rotating latex reactor has been fabricated in an attempt to minimize sedimentation without using microgravity. The entire reactor cylinder is rotated about a horizontal axis to keep the particles in suspension. In this paper we determine the motion of small spherical particles under gravity, in a viscous fluid rotating uniformly about a horizontal axis. The particle orbits are approximately circles, with centres displaced horizontally from the axis of rotation. Owing to net centrifugal buoyancy, the radius of the circles increases (for heavy particles) or decreases (for light particles) with time, so that the particles gradually spiral inward or outward. For a large rotation rate, the particles spiral outwards or inwards too fast, while for a small rotation rate, the displacement of the orbit centre from the rotation axis is excessive in relation to the reactor radius. We determine the rotation rate that maximizes the fraction of the reactor cross-section area that contains particles that will not spiral out to the wall in the experimental time (for heavy particles), or that have spiralled in without hitting the wall (for light particles). Typically, the rate is close to 1 r.p.m., and design rotation rate ranges should span this value. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP ROBERTS, GO (reprint author), ROBERTS ASSOCIATES INC,11794 GREAT OWL CIRCLE,RESTON,VA 22094, USA. NR 12 TC 22 Z9 22 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 AUG PY 1991 VL 229 BP 555 EP 567 DI 10.1017/S0022112091003166 PG 13 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GC067 UT WOS:A1991GC06700026 ER PT J AU GOLDSTEIN, R GOLDSTEIN, BE BALSIGER, H COATES, AJ CURDT, W KELLER, HU NEUBAUER, FM PERRY, C ZARNECKI, J AF GOLDSTEIN, R GOLDSTEIN, BE BALSIGER, H COATES, AJ CURDT, W KELLER, HU NEUBAUER, FM PERRY, C ZARNECKI, J TI THE COMPOSITION AND PLASMA SIGNATURE OF A LARGE DUST IMPACT ON THE GIOTTO SPACECRAFT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WAVE INSTRUMENT; COMET P/HALLEY; PARTICLES; HALLEY; GAS AB At about 14,800 km from the comet Halley nucleus, on the inbound leg, at least six of the sensors onboard the Giotto spacecraft observed an unusual, brief (approximately 30 to 500 ms) event: The ion mass spectrometer data show a brief flow of energetic (up to several hundred electron volts) plasma consisting of protons, water group, and heavier ions. The Johnstone plasma analyzer data show a short burst of plasma, while the dust impact detector system data show an impact event in four of its detectors. The magnetometer signature of the event shows two brief dips in the field. The sudden change in the spacecraft attitude and spin rate observed by the camera at that same time has been interpreted as the result of a large (greater-than-or-equal-to 5 mg) dust particle impact on the front bumper shield of the spacecraft. In addition, at about the same time the spacecraft star-tracker suffered damage. Here we give the first report combining direct measurements of the composition and dynamics of a dust impact plasma cloud, the dust particle mass and the location of the impact on the spacecraft. Analysis of the data indicate that the impacting particle was water or ice-bearing, possibly loosely compacted, and was composed of one or more of: carbon, nitrogen, and silicon. C1 UNIV BERN, INST PHYS, CH-3012 BERN, SWITZERLAND. UCL, MULLARD SPACE SCI LAB, ST MARYS RH5 6NT, ENGLAND. UNIV KENT, CANTERBURY CT2 7NR, KENT, ENGLAND. RUTHERFORD APPLETON LAB, DIDCOT OX11 0QX, OXON, ENGLAND. MAX PLANCK INST AERON, W-3411 KATLENBURG DUHM, GERMANY. UNIV COLOGNE, INST GEOPHYS & METEOROL, W-5000 COLOGNE 41, GERMANY. RP GOLDSTEIN, R (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RI Coates, Andrew/C-2396-2008 OI Coates, Andrew/0000-0002-6185-3125 NR 20 TC 6 Z9 6 U1 0 U2 0 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 AUG 1 PY 1991 VL 96 IS A8 BP 13739 EP 13747 DI 10.1029/91JA01013 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ834 UT WOS:A1991FZ83400001 ER PT J AU BENSON, RF FAINBERG, J AF BENSON, RF FAINBERG, J TI MAXIMUM POWER FLUX OF AURORAL KILOMETRIC RADIATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CYCLOTRON MASER EMISSION; RADIO EMISSIONS; PLASMA-WAVE; DYNAMICS EXPLORER-1; VIKING OBSERVATIONS; ISIS-1 OBSERVATIONS; SOUNDER EXPERIMENTS; SOURCE REGION; Z-MODE; SATELLITE AB The maximum auroral kilometric radiation (AKR) power flux observed by distant satellites has been increased by more than a factor of 10 from previously reported values. This increase has been achieved by a new data selection criterion and a new analysis of antenna spin modulated signals received by the radio astronomy instrument on ISEE 3. The method relies on selecting AKR events containing signals in the highest-frequency channel (1980, kHz), followed by a careful analysis that effectively increased the instrumental dynamic range by more than 20 dB by making use of the spacecraft antenna gain diagram during a spacecraft rotation. This analysis has allowed the separation of real signals from those created in the receiver by overloading. Many signals having the appearance of AKR harmonic signals were shown to be of spurious origin. During one event, however, real second harmonic AKR signals were detected even though the spacecraft was at a great distance (17 R(E)) from Earth. During another event, when the spacecraft was at the orbital distance of the Moon and on the morning side of Earth, the power flux of fundamental AKR was greater than 3 x 10(-13) W m-2 Hz-1 at 360 kHz normalized to a radial distance r of 25 R(E) assuming the power falls off as r-2. A comparison of these intense signal levels with the most intense source region values (obtained by ISIS 1 and Viking) suggests that multiple sources were observed by ISEE 3. RP BENSON, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 54 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 JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1991 VL 96 IS A8 BP 13749 EP 13762 DI 10.1029/91JA01172 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ834 UT WOS:A1991FZ83400002 ER PT J AU SCHUBERT, G WALTERSCHEID, RL HICKEY, MP AF SCHUBERT, G WALTERSCHEID, RL HICKEY, MP TI GRAVITY WAVE-DRIVEN FLUCTUATIONS IN OH NIGHTGLOW FROM AN EXTENDED, DISSIPATIVE EMISSION REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DYNAMICAL-CHEMICAL MODEL; AIRGLOW; ATMOSPHERE AB The theory of gravity wave-driven fluctuations in the OH nightglow from an extended source region is generalized to account for effects of eddy kinematic viscosity nu and eddy thermal diffusivity kappa. In the nondiffusive case, the amplitudes and phases of vertically integrated normalized intensity / and temperature / perturbations and vertically integrated Krassovsky's ratio as functions of period are influenced by the upper limit of vertical integration of the extended source, especially at long periods when vertical wavelengths lambda-v are small. The effects, which include oscillations in /, /, and , particularly at long periods, are due to constructive and destructive interference of nightglow signals from vertically separated levels of the OH emitting region that occur when lambda-v is comparable to or smaller than the thickness of the main emission region. The sensitivity of these ratios to the upper limit of vertical integration occurs because of the relatively small rate of decay of the intensity of OH emission with height above the peak emission level and the exponential growth with altitude of nondissipative gravity waves. Because eddy diffusion increases lambda-v, especially at long periods, and reduces wave growth with height compared with the case nu = kappa = 0, inclusion of eddy diffusion removes the sensitivity of and the other ratios to the maximum height of vertical integration. It is essential to account for both eddy diffusion and emission from the entire vertically extended emission region to correctly predict , /, and / at long gravity wave periods. Observations of Krassovsky's ratio are consistent with theoretical predictions of for horizontal wavelengths larger than about 500 km, provided diffusion and emission from an extended region are both taken into account. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812. RP SCHUBERT, G (reprint author), AEROSPACE CORP,SPACE SCI LAB,LOS ANGELES,CA 90009, USA. NR 18 TC 55 Z9 55 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 AUG 1 PY 1991 VL 96 IS A8 BP 13869 EP 13880 DI 10.1029/91JA00562 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ834 UT WOS:A1991FZ83400012 ER PT J AU TSUTSUI, M STRANGEWAY, RJ TSURUTANI, BT MATSUMOTO, H PHILLIPS, JL ASHOURABDALLA, M AF TSUTSUI, M STRANGEWAY, RJ TSURUTANI, BT MATSUMOTO, H PHILLIPS, JL ASHOURABDALLA, M TI WAVE MODE-IDENTIFICATION OF ELECTROSTATIC NOISE OBSERVED WITH ISEE-3 IN THE DEEP TAIL BOUNDARY-LAYER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DISTANT GEOMAGNETIC TAIL; PLASMA-WAVES; MAGNETOTAIL; DYNAMICS; SHOCKS AB Characteristics of VLF electrostatic noise observed with ISEE 3 in the low-latitude boundary layer of distant geomagnetic tail (approximately 210R(e)) have been examined in detail. Gray tone dynamic spectra with high time resolution of 16 frequency channels of electric field exhibit successive spiky bursts with duration less than the wave sampling period (0.5 s) and with a wide frequency extent. A set of noise parameters wuch as peak amplitude, its frequency, and bandwidth has been determined from a Gaussian distribution function derived for each spiky noise spectrum by using a least squares fitting routine. In order to find a possible energy source for the noise generation, available correlations between the noise parameters and plasma electron parameters have been examined for a 2-hour data interval when ISEE 3 was in the low-latitude boundary layer. The analysis has been conducted on the basis of a hypothesis that the wide frequency extent of the noise spectra is composed of Doppler effects of waves propagating nearly omnidirectionally within the plasma rest frame, which is moving with the electron bulk speed. On the basis of the hypothesis the wavelength of the observed waves has been determined from the width of the frequency extent and the measured electron bulk speed. Although no obvious free energy source has been found from the analysis, the obtained dispersion relation for the electrostatic noise has demonstrated the validity of the hypothesis. The obtained dispersion relation is consistent with theoretical ion acoustic dispersions for the measured electron parameters. The result shows that the wavelength ranges from 2 to 8 times the plasma Debye length. The dispersion also indicates that the ion temperature is in a range from 1 to 4 times the electron temperature. C1 KYOTO UNIV,CTR RADIO ATMOSPHER SCI,UJI,KYOTO 611,JAPAN. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TSUTSUI, M (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024, USA. NR 15 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 AUG 1 PY 1991 VL 96 IS A8 BP 14065 EP 14073 DI 10.1029/91JA00925 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ834 UT WOS:A1991FZ83400029 ER PT J AU HUANG, TS HILL, TW AF HUANG, TS HILL, TW TI DRIFT WAVE INSTABILITY IN THE IO PLASMA TORUS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COROTATING MAGNETOSPHERIC CONVECTION; JOVIAN MAGNETOSPHERE; INTERCHANGE INSTABILITY; TRANSPORT; STABILITY; DIFFUSION; MOTIONS AB We present a linear normal-mode analysis of low-frequency electrostatic drift waves in the Io plasma torus, providing a kinetic description of the centrifugal interchange instability of the torus regulated by coupling to Jupiter's ionosphere. We assume a periodic potential perturbation with azimuthal wavenumber m >> 1 and solve a boundary value problem to obtain the wave dispersion relation and radial eigenfunction. For given m the growing mode is a standing wave in the corotating reference frame. If the outer torus boundary is taken as a discontinuity, the growth rate is proportional to m times the torus flux tube content times the ion drift frequency, divided by the Pedersen conductivity of Jupiter's ionosphere. The inner torus boundary has a modest stabilizing effect for azimuthal wavelengths greater than the radial thickness of the torus. The finite slope of the outer torus density profile has a more pronounced stabilizing effect, reducing the growth rate by the factor 2-beta/m, where beta approximately 2 is the exponent of the assumed power law decline of flux tube content with distance. Even so, the e-folding time is of the order of 1 hour, much less than the inferred residence time of torus ions. The growth rate can be further reduced dramatically by the stabilizing effect of an as-yet unobserved ring current distribution, the "impoundment" effect proposed by Siscoe et al. (1981). Various theoretical models of global radial transport in Jupiter's magnetosphere, including corotating convection, interchange diffusion, and transient flux tube convection, can be understood as plausible nonlinear evolutions of electrostatic drift waves. Further observations and/or numerical simulations are needed to ascertain the relative importance of these transport mechanisms. C1 RICE UNIV,CTR SPACE PHYS,HOUSTON,TX 77251. RP HUANG, TS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 30 TC 23 Z9 23 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1991 VL 96 IS A8 BP 14075 EP 14083 DI 10.1029/91JA01170 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ834 UT WOS:A1991FZ83400030 ER PT J AU BHATTACHARJEE, S ALTENKIRCH, RA OLSON, SL SOTOS, RG AF BHATTACHARJEE, S ALTENKIRCH, RA OLSON, SL SOTOS, RG TI HEAT-TRANSFER TO A THIN SOLID COMBUSTIBLE IN FLAME SPREADING AT MICROGRAVITY SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article DE COMBUSTION; FIRE FLAMES; MICROGRAVITY HEAT TRANSFER AB The heat transfer rate to a thin solid combustible from an attached diffusion flame, spreading across the surface of the combustible in a quiescent, microgravity environment, was determined from measurements made in the drop tower facility at NASA-Lewis Research Center. With first-order Arrhenius pyrolysis kinetics, the solid-phase mass and energy equations along with the measured spread rate and surface temperature profiles were used to calculate the net heat flux to the surface. Results of the measurements are compared to numerical solution of the complete set of coupled differential equations that describes the temperature, species, and velocity fields in the gas and solid phases. The theory and experiment agree on the major qualitative features of the heat transfer. Some fundamental differences are attributed to the neglect of radiation in the theoretical model. A scale analysis is developed that makes use of the experimental data at different ambient conditions to support the notion that radiation is important and to investigate the effect of pressure on the spread rate. C1 SAN DIEGO STATE UNIV,DEPT MECH ENGN,SAN DIEGO,CA 92182. MISSISSIPPI STATE UNIV,DEPT MECH & NUCL ENGN,MISSISSIPPI STATE,MS 39762. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 15 TC 8 Z9 11 U1 0 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1991 VL 113 IS 3 BP 670 EP 676 DI 10.1115/1.2910617 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA HP760 UT WOS:A1991HP76000024 ER PT J AU BERRY, WD MURPHY, JD SMITH, BA TAYLOR, GR SONNENFELD, G AF BERRY, WD MURPHY, JD SMITH, BA TAYLOR, GR SONNENFELD, G TI EFFECT OF MICROGRAVITY MODELING ON INTERFERON AND INTERLEUKIN RESPONSES IN THE RAT SO JOURNAL OF INTERFERON RESEARCH LA English DT Article ID EXPERIMENT PROGRAM INTERFERON; SPACE-FLIGHT; ANTIORTHOSTATIC SUSPENSION; MOUSE; ASSAY; HORMONES; SHUTTLE; GROWTH AB Rats were placed in whole-body harness suspension in three configurations: antiorthostatic hypokinetic/hypodynamic suspension (AAH) to induce headward body fluid redistribution and unload the limbs, orthostatic hypokinetic/hypodynamic suspension (OHH) to unload the limbs without fluid redistribution, and harness restraint (HR) to produce the restraint stress of the model without fluid redistribution or musculoskeletal disuse. AHH and OHH suspension transiently increased interferon-gamma (IFN-gamma) production in response to the mitogen conconavalin A. Harness restraint alone did not affect IFN-gamma response. However, both suspension modeling and harness restraint caused a transient reduction in interleukin-1 (IL-1) and IL-2 responses to mitogen. This suggests that factors associated with musculoskeletal unloading affected IFN-gamma responses, while IL-1 and IL-2 responses were affected by the physiological stress of restraint. C1 UNIV LOUISVILLE,SCH MED,DEPT MICROBIOL & IMMUNOL,LOUISVILLE,KY 40292. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 34 TC 34 Z9 34 U1 0 U2 0 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 SN 0197-8357 J9 J INTERFERON RES JI J. Interferon Res. PD AUG PY 1991 VL 11 IS 4 BP 243 EP 249 DI 10.1089/jir.1991.11.243 PG 7 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA GA415 UT WOS:A1991GA41500007 PM 1717616 ER PT J AU MISRA, AK AF MISRA, AK TI REACTION OF BETA-PHASE NI-AL ALLOYS WITH CRB2 SO JOURNAL OF MATERIALS RESEARCH LA English DT Article AB Reaction of Ni-Al alloys within the beta-NiAl phase with CrB2 was studied at 1473 K as a function of Al concentration in the alloy. Reaction of 49-50 at. % Al alloys with CrB2 occurred by interdiffusion of Ni into CrB2 and Cr into the alloy without forming a new product phase. On the other hand, a new product phase, rich in Ni and B, formed by the reaction of alloys having Al concentrations 48 at. % or lower with CrB2. The reaction product was observed both at the CrB2/alloy interface and along the alloy grain boundaries. RP MISRA, AK (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD AUG PY 1991 VL 6 IS 8 BP 1664 EP 1672 DI 10.1557/JMR.1991.1664 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA GA521 UT WOS:A1991GA52100009 ER PT J AU PICKETT, HM AF PICKETT, HM TI THE FITTING AND PREDICTION OF VIBRATION-ROTATION SPECTRA WITH SPIN INTERACTIONS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article RP PICKETT, HM (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 1341 Z9 1342 U1 4 U2 39 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD AUG PY 1991 VL 148 IS 2 BP 371 EP 377 DI 10.1016/0022-2852(91)90393-O PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FX630 UT WOS:A1991FX63000008 ER PT J AU COHEN, EA LEWISBEVAN, W AF COHEN, EA LEWISBEVAN, W TI FURTHER MEASUREMENTS OF THE ROTATIONAL SPECTRUM OF COF2 - IMPROVED MOLECULAR-CONSTANTS FOR THE GROUND AND NU-2 STATES SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID CENTRIFUGAL-DISTORTION CONSTANTS; CARBONYL FLUORIDE; PLANARITY RELATION C1 SO ILLINOIS UNIV,DEPT CHEM & BIOCHEM,CARBONDALE,IL 62901. RP COHEN, EA (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 12 Z9 12 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD AUG PY 1991 VL 148 IS 2 BP 378 EP 384 DI 10.1016/0022-2852(91)90394-P PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FX630 UT WOS:A1991FX63000009 ER PT J AU HIRANANDANI, S SALTZ, J MEHROTRA, P BERRYMAN, H AF HIRANANDANI, S SALTZ, J MEHROTRA, P BERRYMAN, H TI PERFORMANCE OF HASHED CACHE DATA MIGRATION SCHEMES ON MULTICOMPUTERS SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665. RP HIRANANDANI, S (reprint author), RICE UNIV,INST COMP INFORMAT & TECHNOL,HOUSTON,TX 77251, USA. NR 19 TC 5 Z9 5 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 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD AUG PY 1991 VL 12 IS 4 BP 415 EP 422 DI 10.1016/0743-7315(91)90010-7 PG 8 WC Computer Science, Theory & Methods SC Computer Science GA GA408 UT WOS:A1991GA40800010 ER PT J AU VINAS, AF GOLDSTEIN, ML AF VINAS, AF GOLDSTEIN, ML TI PARAMETRIC-INSTABILITIES OF CIRCULARLY POLARIZED LARGE-AMPLITUDE DISPERSIVE ALFVEN WAVES - EXCITATION OF PARALLEL-PROPAGATING ELECTROMAGNETIC DAUGHTER WAVES SO JOURNAL OF PLASMA PHYSICS LA English DT Article ID FINITE-BETA PLASMA; MODULATIONAL INSTABILITY; SOLAR-WIND; MHD WAVES; SOLITONS; DECAY AB We investigate the parametric decay and modulational instabilities of a large-amplitude circularly polarized dispersive Alfven wave. Our treatment is more general than that of previous derivations based on the two-fluid equations in that we allow for propagation of the unstable daughter waves at arbitrary angles to the background magnetic field, although our main concern in this paper is the exploration of new aspects of propagation parallel to the DC magnetic field. In addition to the well-known coupling of pump waves to electrostatic daughter waves, we find a new parametric channel where the pump wave couples directly to electromagnetic daughter waves. Excitation of the electromagnetic instability occurs only for modulation (k/k0 less-than-or-equal-to 1) and not for decay (k/k0 > 1). ln contrast with the modulational instability excited by the electrostatic coupling, the electromagnetic modulational instability exists for both left-hand (kappa > 0) and right-hand (kappa < 0) polarization. For large k/k0, the electromagnetic channel dominates, while at lower values the electrostatic channel has a larger growth rate for modest values of dispersion, pump-wave amplitude and plasma-beta. Unlike the electrostatic modulational instability, the growth rate of the electromagnetic instability increases monotonically with increasing pump wave amplitude. This analysis confirms that, for decay, the dominant process is coupling to electrostatic daughter waves, at least for parallel propagation. For modulation, the coupling to electromagnetic daughter waves usually dominates, suggesting that the parametric modulational instability is really an electromagnetic phenomenon. RP VINAS, AF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 35 TC 48 Z9 48 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-3778 J9 J PLASMA PHYS JI J. Plasma Phys. PD AUG PY 1991 VL 46 BP 107 EP 127 PN 1 PG 21 WC Physics, Fluids & Plasmas SC Physics GA GM851 UT WOS:A1991GM85100009 ER PT J AU VINAS, AF GOLDSTEIN, ML AF VINAS, AF GOLDSTEIN, ML TI PARAMETRIC-INSTABILITIES OF CIRCULARLY POLARIZED LARGE-AMPLITUDE DISPERSIVE ALFVEN WAVES - EXCITATION OF OBLIQUELY-PROPAGATING DAUGHTER AND SIDE-BAND WAVES SO JOURNAL OF PLASMA PHYSICS LA English DT Article ID FINITE-AMPLITUDE; FILAMENTATION INSTABILITY; MODULATIONAL INSTABILITY AB We investigate the parametric instabilities of a large-amplitude circularly polarized dispersive parallel-propagating Alfven wave. Our treatment is more general than that of previous derivations based on the two-fluid equations in that we allow for propagation of the unstable daughter and side-band waves at arbitrary angles to the background (DC) magnetic field. We present the characteristics of the decay and modulational instabilities as functions of propagation angle. We find, in addition to the well-known decay and modulational instabilities, that at oblique and perpendicular propagation there is another parametric instability, namely the filamentation instability, which is characterized by a broad band-width in wavenumber and which satisfies the condition Re (omega) much less than-gamma. A second parametric process at oblique and perpendicular angles of propagation, which has not been reported before is also investigated, namely the parametric magneto-acoustic instability. This instability is distinct from the filamentation instability in that it is characterized by density perturbations with large real frequencies that satisfy the condition Re (omega) much greater than-gamma. Unlike the filamentation instability, the magneto-acoustic instability extends over a broad angular range, but has a very narrow band-width in wavenumber. We report the dispersive characteristics of the filamentation and magneto-acoustic instabilities as functions of plasma-beta, dispersion-kappa and pump amplitude-eta for arbitrary propagation angles. RP VINAS, AF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 26 TC 70 Z9 70 U1 0 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-3778 J9 J PLASMA PHYS JI J. Plasma Phys. PD AUG PY 1991 VL 46 BP 129 EP 152 PN 1 PG 24 WC Physics, Fluids & Plasmas SC Physics GA GM851 UT WOS:A1991GM85100010 ER PT J AU ISHIDA, H SHICK, R HURWITZ, F AF ISHIDA, H SHICK, R HURWITZ, F TI THE REACTION OF PHENYLPROPYLSILSESQUIOXANE IN THE FIBER SPINNING REGIME SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Article ID SILICON-CARBIDE FIBERS; COMPOSITE-MATERIALS; CONDENSATION; HYDROLYSIS; STRENGTH; GELS AB A potential ceramic precursor, a phenylpropylsilsesquioxane co-oligomer from Petrarch Systems (Petpps), was studied under conditions where fiber spinning is performed. The reaction kinetics of residual silanols of Petpps are studied using Fourier transform infrared spectroscopy in the temperature range 100-150-degrees-C. The activation energy and the reaction order of the silanol condensation reaction in the molten Petpps are determined. A combination of gel permeation chromatography, liquid chromatography, and nuclear magnetic resonance spectroscopy is used to study the possibility of copolymerization between the phenyl and propyl silane moieties. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP ISHIDA, H (reprint author), CASE WESTERN RESERVE UNIV,DEPT MACROMOLEC SCI,CLEVELAND,OH 44106, USA. RI Ishida, Hatsuo/P-3603-2015 NR 21 TC 2 Z9 2 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 AUG PY 1991 VL 29 IS 9 BP 1095 EP 1106 DI 10.1002/polb.1991.090290908 PG 12 WC Polymer Science SC Polymer Science GA FX286 UT WOS:A1991FX28600008 ER PT J AU FLANNERY, C KLAASSEN, JJ GOJER, M STEINFELD, JI SPENCER, M CHACKERIAN, C AF FLANNERY, C KLAASSEN, JJ GOJER, M STEINFELD, JI SPENCER, M CHACKERIAN, C TI MEASUREMENT OF SELF-BROADENING OF THE OZONE NU-3 TRANSITIONS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID MILLIMETER-WAVE SPECTRUM; TEMPERATURE-DEPENDENCE; 3-MU-M REGIONS; MU-M; AIR; COEFFICIENTS; PARAMETERS; O-3; INTENSITIES; HALFWIDTHS AB Self-broadening coefficients have been measured for a number of rovibrational lines in the nu-3 band of ozone, in the frequency range 1015-1058 cm-1, with J values between 0 and 27, and over a range of K(a) values. A multiparameter non-linear least-squares fitting procedure is used to reduce the data, and the sensitivity of the procedure to instrument line width, weak satellite features, and absolute intensity has been examined. The retrieved coefficients are compared with millimeter-wave broadening coefficients, directly measured rotational relaxation times, and recently suggested empirical representations. C1 MIT,DEPT CHEM,CAMBRIDGE,MA 02139. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 28 TC 16 Z9 16 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1991 VL 46 IS 2 BP 73 EP 80 DI 10.1016/0022-4073(91)90083-3 PG 8 WC Optics; Spectroscopy SC Optics; Spectroscopy GA FP824 UT WOS:A1991FP82400002 ER PT J AU ZUCKERWAR, AJ AF ZUCKERWAR, AJ TI MEASUREMENT OF PRESSURE-FLUCTUATIONS IN TURBULENT BOUNDARY-LAYERS - INTRODUCTION SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Editorial Material RP ZUCKERWAR, AJ (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 238,HAMPTON,VA 23665, USA. NR 1 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 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD AUG PY 1991 VL 90 IS 2 BP 1019 EP 1019 DI 10.1121/1.402289 PN 1 PG 1 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA FZ779 UT WOS:A1991FZ77900036 ER PT J AU HARDIN, JC AF HARDIN, JC TI ACOUSTIC SOURCES IN THE LOW MACH NUMBER TURBULENT BOUNDARY-LAYER SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID NOISE; SOUND; FIELD; WAVE AB The sources of sound production in a low Mach number turbulent boundary layer are examined. The sources are shown to be quadrupole in nature and to result from supersonically convecting wave-number components of the fluctuating Reynolds' normal stresses. The primary Tollmien-Schlichting instability of the boundary layer is found to radiate no sound. Analysis of various vortical phenomena suggests that the primary source is the process of formation of horseshoe vortices, with viscous sublayer bursts a possible secondary source. RP HARDIN, JC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 25 TC 3 Z9 4 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD AUG PY 1991 VL 90 IS 2 BP 1020 EP 1031 DI 10.1121/1.402290 PN 1 PG 12 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA FZ779 UT WOS:A1991FZ77900037 ER PT J AU MANNEY, GL AF MANNEY, GL TI THE STRATOSPHERIC 4-DAY WAVE IN NMC DATA SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID BAROTROPIC INSTABILITY; PLANETARY-WAVES; HEMISPHERE AB The observed characteristics of the 4-day eastward-moving wave 1 in the Southern Hemisphere polar winter stratosphere are surveyed using ten years of National Meteorological Center (NMC) geopotential height data. The 4-day wave is shown to be a ubiquitous feature in the Southern Hemisphere polar winter stratosphere and is usually prominent during July and August. Growth of the 4-day wave is characterized by two types of structures. Some episodes exhibit NW to SE phase tilts and a single high-latitude maximum. Others show NE to SW phase tilts during growth and a high-latitude maximum out of phase with a secondary lower-latitude maximum. Stability analyses show that all characteristics of the first type of episode are consistent with barotropic instability of the stratospheric polar night jet. Analyses of climatological fields suggest that characteristics of the second type of episode may be consistent with barotropic instability of the double-peaked mesospheric jet. RP MANNEY, GL (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 16 Z9 16 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 AUG 1 PY 1991 VL 48 IS 15 BP 1798 EP 1811 DI 10.1175/1520-0469(1991)048<1798:TSDWIN>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GG358 UT WOS:A1991GG35800008 ER PT J AU NARAYANAN, SR SURAMPUDI, S ATTIA, AI BANKSTON, CP AF NARAYANAN, SR SURAMPUDI, S ATTIA, AI BANKSTON, CP TI ANALYSIS OF REDOX ADDITIVE-BASED OVERCHARGE PROTECTION FOR RECHARGEABLE LITHIUM BATTERIES SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article AB The overcharge condition in secondary lithium batteries employing redox additives for overcharge protection, has been theoretically analyzed in terms of a finite linear diffusion model. The analysis leads to expressions relating the steady-state overcharge current density and cell voltage to the concentration, diffusion coefficient, standard reduction potential of the redox couple, and interelectrode distance. The model permits the estimation of the maximum permissible overcharge rate for any chosen set of system conditions. Digital simulation of the overcharge experiment leads to numerical representation of the potential transients, and estimate of the influence of diffusion coefficient and interelectrode distance on the transient attainment of the steady state during overcharge. The model has been experimentally verified using 1,1'-dimethylferrocene as a redox additive. The analysis of the experimental results in terms of the theory allows the calculation of the diffusion coefficient and the formal potential of the redox couple. The model and the theoretical results may be exploited in the design and optimization of overcharge protection by the redox additive approach. RP NARAYANAN, SR (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 10 TC 52 Z9 53 U1 1 U2 11 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 AUG PY 1991 VL 138 IS 8 BP 2224 EP 2229 DI 10.1149/1.2085954 PG 6 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA FZ323 UT WOS:A1991FZ32300012 ER PT J AU COYNE, L MARINER, R RICE, A AF COYNE, L MARINER, R RICE, A TI AIR OXIDATION OF HYDRAZINE .1. REACTION-KINETICS ON NATURAL KAOLINITES, HALLOYSITES, AND MODEL SUBSTITUENT LAYERS WITH VARYING IRON AND TITANIUM-OXIDE AND O-CENTER CONTENTS SO LANGMUIR LA English DT Article ID ELECTRON-SPIN RESONANCE; DOPED SYNTHETIC KAOLINITE; PARAMAGNETIC RESONANCE; LUMINESCENCE; SPECTRA; SURFACE; SPECTROSCOPY; MOSSBAUER AB Air oxidation of hydrazine was studied by using a group of kaolinites, halloysites, and substituent oxides as models for the tetrahedral and octahedral sheets. The rate was found to be linear with oxygen. The stoichiometry showed that oxygen was the primary oxidant and that dinitrogen was the only important nitrogen-containing product. The rates on kaolinites were strongly inhibited by water. Those on three-dimensional silica and gibbsite appeared not to be. That on a supposedly layered silica formed from a natural kaolinite by acid leaching showed transitional behavior - slowed relative to that expected from a second-order reaction relative to that on the gibbsite and silica but faster than those on the kaolinites. The most striking result of the reaction was the marked increase in the rate of reaction of a constant amount of hydrazine as the amount of clay was increased. This increase was apparent (in spite of the water inhibition at high conversions) over a 2 order of magnitude variation of the clay weight. The weight dependence was taken to indicate that the role of the clay is very important, that the number of reactive centers is very small, or that they may be deactivated over the course of the reaction. In contrast to the strong dependence on overall amount of clay, the variation of amounts of putative oxidizing centers, such as structural Fe(III), admixed TiO2 or Fe2O3, or O- centers, did not result in alteration of the rate commensurate with the degree of variation of the entity in question. Surface iron does play some role, however, as samples that were pretreated with a reducing agent were less active as catalysts than the parent material. These results were taken to indicate either that the various centers interact to such a degree that they cannot be considered independently or that the reaction might proceed by way of surface complexation, rather than single electron transfers. C1 SAN JOSE STATE UNIV, DEPT CHEM, SAN JOSE, CA 95192 USA. ENGLISH CHINA CLAYS INT, SANDERSVILLE, GA 31082 USA. RP COYNE, L (reprint author), NASA, AMES RES CTR, MAIL STOP 239-4, MOFFETT FIELD, CA 94035 USA. NR 42 TC 3 Z9 3 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD AUG PY 1991 VL 7 IS 8 BP 1660 EP 1674 DI 10.1021/la00056a019 PG 15 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA GC040 UT WOS:A1991GC04000019 PM 11538370 ER PT J AU COYNE, LM SUMMERS, DP AF COYNE, LM SUMMERS, DP TI SURFACE ACTIVATION OF AIR OXIDATION OF HYDRAZINE ON KAOLINITE .2. CONSIDERATION OF OXIDIZING REDUCING ENTITIES IN RELATIONSHIP TO OTHER COMPOSITIONAL, STRUCTURAL, AND ENERGETIC FACTORS SO LANGMUIR LA English DT Article ID CLAY-MINERALS; LUMINESCENCE; OXIDE; IRON; DEHYDRATION; RESONANCE; CATALYSTS; SPECTRA; CENTERS AB The rates (previously reported) for the air oxidation of hydrazine on kaolinite and substituent oxides of kaolinite showed a complex dependence on the relative amounts of several structural oxidizing/reducing entities within the reaction-promoting solids. The rates indicated an important role of the clay but no dominant role of any one of the oxidizing/reducing entities. In this paper we review (a) the reaction-promoting activity of these centers as studied in other systems, (b) various spectroscopic results showing interaction between these entities in clays and (c) reported spectroscopic studies ot the complexation between hydrazine and aluminosilicate surfaces as a whole, in an effort to propose a mechanism for the reaction. Whereas some uncertainties remain, the present synthesis concludes that a mechanism operating through single electron/hole transfers and hydrogen atom transfers by discrete centers is adequate to explain the observed rate behaviors including the observed second order dependence of the oxidation rate on catalyst amount. The effects of these operations on the catalyst can result in no alteration of, or complete or partial electronic relaxation of its contingent of trapped separated charge pairs. The degree to which surface complexation as a whole, intercalation, or luminescent processes may also be associated with the reaction cannot be adequately assessed with the information in hand. C1 SAN JOSE STATE UNIV, DEPT CHEM, SAN JOSE, CA 95192 USA. RP COYNE, LM (reprint author), NASA, AMES RES CTR, PLANETARY BIOL BRANCH, MAIL STOP 239-4, MOFFETT FIELD, CA 94035 USA. NR 51 TC 3 Z9 3 U1 2 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD AUG PY 1991 VL 7 IS 8 BP 1675 EP 1688 DI 10.1021/la00056a020 PG 14 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA GC040 UT WOS:A1991GC04000020 PM 11538371 ER PT J AU FREUND, R AF FREUND, R TI ON POLYNOMIAL PRECONDITIONING AND ASYMPTOTIC CONVERGENCE FACTORS FOR INDEFINITE HERMITIAN MATRICES SO LINEAR ALGEBRA AND ITS APPLICATIONS LA English DT Article ID SEMI-ITERATIVE METHODS; LINEAR-EQUATIONS; SYSTEMS AB We are concerned with the minimal residual method combined with polynomial preconditioning for solving large linear systems Ax = b with indefinite Hermitan coefficient matrices A. The standard approach for choosing the polynomial preconditioner leads to preconditioned systems which are positive definite. Here, we investigate a different strategy which leaves the preconditioned coefficient matrix indefinite. More precisely, the polynomial preconditioner is designed to cluster the positive (negative) eigenvalues of A around 1 (around some negative constant). In particular, it is shown that such indefinite polynomial preconditioners can be obtained as the optimal solutions of a certain two-parameter family of Chebyshev approximation problems. The problem of selecting the parameters so that the resulting indefinite polynomial preconditioner speeds up the convergence of the minimal residual method optimally is also addressed. For this task, we propose an approach based on the concept of asymptotic convergence factors. Finally, some numerical examples of indefinite polynomial preconditioners are given. C1 UNIV WURZBURG,INST ANGEW MATH & STAT,W-8700 WURZBURG,GERMANY. RP FREUND, R (reprint author), NASA,AMES RES CTR,RIACS,MAIL STOP 230-5,MOFFETT FIELD,CA 94035, USA. NR 27 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0024-3795 J9 LINEAR ALGEBRA APPL JI Linear Alg. Appl. PD AUG-OCT PY 1991 VL 154 BP 259 EP 288 DI 10.1016/0024-3795(91)90380-F PG 30 WC Mathematics, Applied; Mathematics SC Mathematics GA FV961 UT WOS:A1991FV96100012 ER PT J AU REYNOLDS, AP STONER, GE AF REYNOLDS, AP STONER, GE TI CLEAVAGE CRYSTALLOGRAPHY OF LIQUID-METAL EMBRITTLED ALUMINUM-ALLOYS SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID ENVIRONMENTALLY ASSISTED CRACKING; HYDROGEN EMBRITTLEMENT; MERCURY EMBRITTLEMENT; FRACTURE; NICKEL; SUPERALLOYS; MONEL-400; BEHAVIOR; GROWTH; STEEL AB Failure in aluminum alloys subjected to liquid metal embrittlement (LME) typically occurs by either intergranular (IG) fracture or transgranular (TG) cleavage. In this study, the crystallography of liquid metal-induced TG cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was {100} in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surfaces indicated that there was not a unique direction of crack propagation. In addition, the existence of {100} cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys. C1 UNIV VIRGINIA,DEPT MAT SCI,CHARLOTTESVILLE,VA 22901. RP REYNOLDS, AP (reprint author), NASA,LANGLEY RES CTR,MECH MAT BRANCH,HAMPTON,VA 23665, USA. RI Reynolds, Anthony/F-2585-2010 NR 33 TC 19 Z9 19 U1 1 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD AUG PY 1991 VL 22 IS 8 BP 1849 EP 1855 DI 10.1007/BF02646509 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA GA563 UT WOS:A1991GA56300017 ER PT J AU HAYHURST, KJ SHIER, DR AF HAYHURST, KJ SHIER, DR TI A FACTORING APPROACH FOR THE STOCHASTIC SHORTEST-PATH PROBLEM SO OPERATIONS RESEARCH LETTERS LA English DT Article DE PERT; RELIABILITY; SHORTEST PATH; STOCHASTIC NETWORKS ID RELIABILITY COMPUTATIONS; BOUNDING DISTRIBUTIONS; PERT NETWORK; COMPLEXITY AB This paper studies the problem of determining the exact distribution of shortest path length in directed stochastic networks. Our approach is based on the concept of structural factoring, in which a stochastic network is decomposed into an equivalent set of smaller, generally less complex subnetworks. Several network constructs are identified and exploited to reduce significantly the computational effort required to solve a problem relative to complete enumeration. This algorithm can be applied to two important classes of stochastic network problems: determining the critical path length distribution for acyclic networks and the two-terminal reliability for probabilistic networks. Computational experience with the algorithm has been encouraging and has allowed the exact solution of networks previously analyzed only by approximation techniques. C1 COLL WILLIAM & MARY,DEPT MATH,WILLIAMSBURG,VA 23185. RP HAYHURST, KJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 14 TC 5 Z9 5 U1 2 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-6377 J9 OPER RES LETT JI Oper. Res. Lett. PD AUG PY 1991 VL 10 IS 6 BP 329 EP 334 DI 10.1016/0167-6377(91)90005-A PG 6 WC Operations Research & Management Science SC Operations Research & Management Science GA GF557 UT WOS:A1991GF55700005 ER PT J AU HOOVER, RB AF HOOVER, RB TI X-RAY EUV OPTICS SO OPTICAL ENGINEERING LA English DT Editorial Material RP HOOVER, RB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES52,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 1 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 AUG PY 1991 VL 30 IS 8 BP 1047 EP 1048 DI 10.1117/12.55906 PG 2 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200001 ER PT J AU BARBEE, TW WEED, JW HOOVER, RB ALLEN, MJ LINDBLOM, JF ONEAL, RH KANKELBORG, CC DEFOREST, CE PARIS, ES WALKER, ABC WILLIS, TD GLUSKIN, E PIANETTA, P BAKER, PC AF BARBEE, TW WEED, JW HOOVER, RB ALLEN, MJ LINDBLOM, JF ONEAL, RH KANKELBORG, CC DEFOREST, CE PARIS, ES WALKER, ABC WILLIS, TD GLUSKIN, E PIANETTA, P BAKER, PC TI MULTISPECTRAL SOLAR TELESCOPE ARRAY .2. SOFT-X-RAY EUV REFLECTIVITY OF THE MULTILAYER MIRRORS SO OPTICAL ENGINEERING LA English DT Article DE X-RAY EUV OPTICS; MULTILAYER MIRRORS; X-RAY TELESCOPES; NORMAL INCIDENCE X-RAY OPTICS; TELESCOPE CALIBRATION ID PERFORMANCE; RAY/EUV; OPTICS AB We have developed seven compact soft x-ray/EUV (XUV) multilayer-coated and two compact FUV interference-film-coated Cassegrain and Ritchey-Chretien telescopes for a rocket-borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,CTR SPACE SCI,HUNTSVILLE,AL 35812. STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305. ARGONNE NATL LAB,ARGONNE,IL 60439. STANFORD UNIV,STANFORD SYNCHROTRON RADIAT LAB,STANFORD,CA 94305. BAKER CONSULTING,WALNUT CREEK,CA 94596. RP BARBEE, TW (reprint author), UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550, USA. NR 28 TC 13 Z9 14 U1 1 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1067 EP 1075 PG 9 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200004 ER PT J AU HOOVER, RB SHEALY, DL BRINKLEY, BR BAKER, PC BARBEE, TW WALKER, ABC AF HOOVER, RB SHEALY, DL BRINKLEY, BR BAKER, PC BARBEE, TW WALKER, ABC TI DEVELOPMENT OF THE WATER WINDOW IMAGING X-RAY MICROSCOPE UTILIZING NORMAL-INCIDENCE MULTILAYER OPTICS SO OPTICAL ENGINEERING LA English DT Article DE X-RAY EUV OPTICS; WATER WINDOW IMAGING; MULTILAYER X-RAY OPTICS; NORMAL-INCIDENCE MIRRORS; SCHWARZSCHILD OPTICS ID TELESCOPE AB We describe the development of the water window imaging x-ray microscope based on normal-incidence multilayer x-ray mirrors. The narrow bandpass response inherent in multilayer x-ray optics is accurately tuned to wavelengths within the "water window." Similar doubly-reflecting multilayer optical systems have been fabricated for our astronomical rocket-borne x-ray/EUV telescopes. Previous theoretical studies performed during the MSFC X-Ray Microscope Development Program established that high-resolution multilayer x-ray imaging microscopes are possible by using either spherical (Schwarzschild configuration) optics or aspherical configurations. These microscopes require ultrasmooth mirror substrates, which have been fabricated using advanced flow polishing methods. Hemlite-grade sapphire microscope optic substrates have been accurately figured and polished to a smoothness of 0.5-angstrom rms, as measured by the Zygo profilometer. We describe the current status of fabrication and testing of the optical and mechanical subsystems for the water window imaging x-ray microscope. This new instrument should yield images of carbon-based microstructures within living cells of unprecedented spatial resolution and contrast, without need for fixatives, dyes, and chemical additives. C1 UNIV ALABAMA,DEPT PHYS,BIRMINGHAM,AL 35294. UNIV ALABAMA,DEPT CELL BIOL & ANAT,BIRMINGHAM,AL 35294. BAKER CONSULTING,WALNUT CREEK,CA 94596. UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305. RP HOOVER, RB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. RI Shealy, David/A-5299-2008 NR 25 TC 14 Z9 14 U1 0 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1086 EP 1093 DI 10.1117/12.55924 PG 8 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200007 ER PT J AU SHEALY, DL JIANG, W HOOVER, RB AF SHEALY, DL JIANG, W HOOVER, RB TI DESIGN AND ANALYSIS OF ASPHERICAL MULTILAYER IMAGING X-RAY MICROSCOPE SO OPTICAL ENGINEERING LA English DT Article DE X-RAY EUV OPTICS; X-RAY MICROSCOPES; MULTILAYERS; SCHWARZSCHILD OBJECTIVE ID PROJECTION LITHOGRAPHY; TELESCOPES; REDUCTION AB Considerable effort has been devoted recently to the design, analysis, fabrication, and testing of spherical Schwarzschild microscopes for soft x-ray applications in microscopy and projection lithography. The spherical Schwarzschild microscope consists of two concentric spherical mirrors configured such that the third-order spherical aberration and coma are zero. Because multilayers are used on the mirror substrates for soft x-ray applications, it is desirable to have a small number of reflecting surfaces in the microscope. In order to reduce the microscope aberrations and increase the field of view, generalized mirror surface profiles have been considered in this study for a two-mirror microscope. Based on incoherent, sine wave modulation transfer function (MTF) calculations, the object plane resolution of a 20x microscope has been analyzed as a function of the object height and numerical aperture (NA) of the primary for several spherical Schwarzschild, conic, and aspherical reflecting two-mirror microscope configurations. The ultimate resolution of an aspherical, two-mirror microscope appears to be about 200 angstrom when using 100-angstrom radiation. Better resolution can be achieved when shorter wavelength radiation is used. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP SHEALY, DL (reprint author), UNIV ALABAMA,DEPT PHYS,BIRMINGHAM,AL 35294, USA. RI Shealy, David/A-5299-2008 NR 18 TC 7 Z9 7 U1 1 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1094 EP 1099 DI 10.1117/12.55913 PG 6 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200008 ER PT J AU HOOVER, RB WALKER, ABC DEFOREST, CE ALLEN, MJ LINDBLOM, JF AF HOOVER, RB WALKER, ABC DEFOREST, CE ALLEN, MJ LINDBLOM, JF TI EUV FUV RESPONSE CHARACTERISTICS OF PHOTOGRAPHIC FILMS FOR THE MULTISPECTRAL SOLAR TELESCOPE ARRAY SO OPTICAL ENGINEERING LA English DT Article; Proceedings Paper CT CONF ON X-RAY/EUV OPTICS FOR ASTRONOMY, MICROSCOPY, POLARIMETRY, AND PROJECTION LITHOGRAPHY CY JUL, 1990 CL SAN DIEGO, CA SP SOC PHOTO OPT INSTRUMENTAT ENGINEERS DE X-RAY EUV OPTICS; X-RAY FILMS; SCHUMANN EMULSIONS; MULTILAYER X-RAY TELESCOPES; EUV FUV PHOTOGRAPHIC FILMS ID CORONA; SKYLAB AB The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne observatory designed to produce ultrahigh-resolution full-disk images of the sun. The MSSTA utilizes an array of Ritchey-Chretien, Cassegrain, and Herschelian normal incidence telescopes operating in the soft x-ray (44- to 100-angstrom), the extreme ultraviolet (EUV: lambda-lambda approximately 100 to 1000 angstrom), and the far ultraviolet (FUV: lambda-lambda approximately 1000 to 2000 angstrom) portions of the electromagnetic spectrum. These normal incidence multilayer and thin film interference coated optical systems are designed to produce narrow band solar images at selected wavelengths within this very broad spectral regime. The MSSTA mission places extremely strenuous requirements upon the imaging detector. The desire for ultrahigh-resolution (approximately 0.1 to 0.3 arcsec) images of the solar disk and corona out to 1.5 R. demands an information storage capacity that at the present time can be met only by the highest quality photographic emulsions. Because a tremendous range exists in the intensity levels and contrast characteristics of solar x-ray/EUV/FUV emission features, the MSSTA photographic films must have a wide latitude to allow extremely bright, high-contrast features associated with flares and active regions to be recorded without saturation, while maintaining the ability to capture the faint, low-contrast structures in coronal holes, polar coronal plumes, network structures, and coronal loops. The MSSTA flight films must have high to ultrahigh-resolution and be sensitive over this very broad and difficult portion of the electromagnetic spectrum. The gelatin overcoat of the film must be maintained at a minimum, while the 70-mm film must retain the ability to be transported through conventional Pentax 645 cameras with minimum degradation due to scratches in the delicate emulsion. Furthermore, because the payload must be evacuated to prevent the delicate EUV and soft x-ray filters from failing due to acoustic vibrational stresses during launch, the MSSTA flight films must also have low-outgassing rates. These films must also be provided with antistatic backing to prevent electrostatic sparks from degrading the images as the dry film is unspooled through the cameras. We describe the performance and characteristics required of the MSSTA photographic films for solar observations in the soft x-ray/EUV and FUV wavelength regimes. We discuss the properties of the important new emulsions selected for flight and present data on the response characteristics of a tabular grain Experimental XUV 100 film and an uncoated Experimental Spectroscopic 649 emulsion. C1 STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305. RP HOOVER, RB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 12 TC 7 Z9 7 U1 0 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1116 EP 1124 DI 10.1117/12.55916 PG 9 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200011 ER PT J AU DEFOREST, CE KANKELBORG, CC ALLEN, MJ PARIS, ES WILLIS, TD LINDBLOM, JF ONEAL, RH WALKER, ABC BARBEE, TW HOOVER, RB BARBEE, TW AF DEFOREST, CE KANKELBORG, CC ALLEN, MJ PARIS, ES WILLIS, TD LINDBLOM, JF ONEAL, RH WALKER, ABC BARBEE, TW HOOVER, RB BARBEE, TW TI MULTISPECTRAL SOLAR TELESCOPE ARRAY .5. TEMPERATURE DIAGNOSTIC RESPONSE TO THE OPTICALLY THIN SOLAR PLASMA SO OPTICAL ENGINEERING LA English DT Article DE X-RAY EUV OPTICS; MULTILAYER OPTICS; SOLAR CORONA; SOLAR PLASMA DIAGNOSTICS AB We have developed compact soft x-ray, extreme ultraviolet (EUV), and far-ultraviolet (FUV) multilayer coated telescopes for the study of the solar chromosphere, corona, and corona/solar wind interface. Because these systems operate at short wavelengths (approximately 40 angstrom < lambda < 1550 angstrom), the modest apertures of 40 to 127 mm allow observations at very high angular resolution (0.1 to 0.7 arcsec). In addition to permitting traditional normal incidence optical configurations (such as Cassegrain, Ritchey-Chretien, and Herschelian configurations) to be used at soft x-ray/EUV wavelengths, multilayer coatings also allow a narrow wavelength band (lambda/DELTA-lambda approximately 15-100) to be selected for imaging. The resulting telescopes provide a very powerful and flexible diagnostic instrument for the study of both the fine-scale structure of the chromosphere/corona interface and the large-scale structure of the corona and corona/solar wind interface. In previous papers, we have described a new solar rocket payload, the Multi-Spectral Solar Telescope Array (MSSTA), which is composed of 17 of these compact telescopes. In the present paper, we report on the ability of the MSSTA payload to obtain temperature diagnostic information about the optically thin solar plasma. We also discuss applications of this information to studies of coronal structure. C1 UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV CALIF BERKELEY,BERKELEY,CA 94720. RP DEFOREST, CE (reprint author), STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305, USA. NR 12 TC 10 Z9 10 U1 0 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1125 EP 1133 DI 10.1117/12.55911 PG 9 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200012 ER PT J AU LINDBLOM, JF ONEAL, RH WALKER, ABC POWELL, FR BARBEE, TW HOOVER, RB POWELL, SF AF LINDBLOM, JF ONEAL, RH WALKER, ABC POWELL, FR BARBEE, TW HOOVER, RB POWELL, SF TI MULTISPECTRAL SOLAR TELESCOPE ARRAY .4. THE SOFT-X-RAY AND EXTREME ULTRAVIOLET FILTERS SO OPTICAL ENGINEERING LA English DT Article; Proceedings Paper CT CONF ON X-RAY/EUV OPTICS FOR ASTRONOMY, MICROSCOPY, POLARIMETRY, AND PROJECTION LITHOGRAPHY CY JUL, 1990 CL SAN DIEGO, CA SP SOC PHOTO OPT INSTRUMENTAT ENGINEERS DE X-RAY EUV OPTICS; X-RAY FILTERS; X-RAY WINDOWS; THIN METAL FOILS AB The multilayer mirrors used in the normal-incidence optical systems of the Multi-Spectral Solar Telescope Array (MSSTA) are efficient reflectors for soft x-ray/extreme ultraviolet (EUV) radiation at wavelengths that satisfy the Bragg condition, thus allowing a narrow band of the soft x-ray/EUV spectrum to be isolated. However, these same mirrors are also excellent reflectors in the visible, ultraviolet, and far-ultraviolet (FUV) part of the spectrum, where normal incidence reflectivities can exceed 50%. Furthermore, the sun emits far more radiation in the ultraviolet and visible part of the spectrum than it does in the soft x-ray/EUV. For this reason, thin foil filters are employed to eliminate the unwanted longer wavelength solar emission. With the proper choice of filter materials, the filters can also be used to eliminate EUV radiation at longer wavelengths, where the increasing specular reflectivity of multilayer mirrors and the high intensity of solar emissions can cause "contamination" of the image in the narrow band defined by the Bragg condition. In addition, filters can eliminate higher order multilayer reflections. Finally, filter absorption edges can sometimes be utilized to reduce the width of the primary bandpass. The MSSTA instrument uses various combinations of thin foil filters composed of aluminum, carbon, tellurium, potassium bromide, beryllium, molybdenum, rhodium, and phthalocyanine to achieve the desired radiation rejection characteristics. We discuss issues concerning the design, manufacture, and predicted performance of MSSTA filters. C1 LUXEL CORP,FRIDAY HARBOR,WA 98250. UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. STANFORD UNIV,DEPT MAT SCI & ENGN,STANFORD,CA 94305. RP LINDBLOM, JF (reprint author), STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305, USA. NR 14 TC 6 Z9 6 U1 1 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1134 EP 1141 DI 10.1117/12.55912 PG 8 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200013 ER PT J AU FINESCHI, S HOOVER, RB FONTENLA, JM WALKER, ABC AF FINESCHI, S HOOVER, RB FONTENLA, JM WALKER, ABC TI POLARIMETRY OF EXTREME ULTRAVIOLET LINES IN SOLAR ASTRONOMY SO OPTICAL ENGINEERING LA English DT Article; Proceedings Paper CT CONF ON X-RAY/EUV OPTICS FOR ASTRONOMY, MICROSCOPY, POLARIMETRY, AND PROJECTION LITHOGRAPHY CY JUL, 1990 CL SAN DIEGO, CA SP SOC PHOTO OPT INSTRUMENTAT ENGINEERS DE X-RAY EUV OPTICS; SOLAR PHYSICS; X-RAY POLARIMETRY; EUV POLARIMETRY; SOLAR CORONA; CORONAGRAPHS; MULTILAYER OPTICS; VECTOR MAGNETIC FIELDS ID MAGNETIC-FIELDS; POLARIZATION; SCATTERING; ALPHA AB Several mechanisms can induce a detectable amount of linear polarization (greater-than-or-equal-to 1%) in spectral lines emitted by the outer solar atmosphere at EUV/FUV wavelengths (i.e., 100 angstrom less-than-or-equal-to lambda less-than-or-equal-to 1500 angstrom): (1) Polarization in FUV lines (up to 20%) can be originated by resonance scattering of radiation anisotropically illuminating the emitting atoms. Modifications of this polarization can then result from the presence of a magnetic field (Hanle effect). (2) Impact line polarization can arise from anisotropic collisional excitation of the EUV-emitting atoms by particles (electrons, protons) with non-Maxwellian velocity distributions. We suggest how new technological developments in the production of ultrasmooth, low-scatter flow-polished mirror substrates and high-quality- multilayer and interference film coatings can make possible some new optical instruments for the observation of these polarization effects. We give the relevant observational parameters for all-reflective FUV/EUV imaging polarimeters. A coronagraph/polarimeter, operating at hydrogen Lyman-alpha, could provide, via the Hanle effect, the first direct measurement of coronal vector magnetic fields. An EUV polarimeter, operating at EUV helium lines (e.g., 304 angstrom, 584 angstrom), could observe impact polarization phenomena occurring in solar flares. The reflecting polarization analyzers for these instruments will operate at the Brewster angle and will be coated with thin-film interference coatings or multilayer coatings. We describe several FUV/EUV polarimeter designs based on these polarization optics. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305. RP FINESCHI, S (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 31 TC 12 Z9 12 U1 0 U2 2 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 AUG PY 1991 VL 30 IS 8 BP 1161 EP 1168 DI 10.1117/12.55922 PG 8 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200017 ER PT J AU HOOVER, RB FINESCHI, S FONTENLA, JM WALKER, ABC AF HOOVER, RB FINESCHI, S FONTENLA, JM WALKER, ABC TI IMAGING POLARIMETERS FOR SOLAR EXTREME ULTRAVIOLET ASTRONOMY SO OPTICAL ENGINEERING LA English DT Article DE X-RAY EUV OPTICS; EUV FUV NORMAL INCIDENCE OPTICS; SOLAR CORONA; POLARIMETRY; CORONAGRAPHS; MULTILAYER OPTICS ID LYMAN-ALPHA; LINE; POLARIZATION; TELESCOPE; CORONA; FIELD AB We describe new EUV/FUV (100 angstrom less-than-or-equal-to-lambda-less-than-or-equal-to 1500 angstrom) polarimeter instrument concepts for solar research. These instruments are designed to observe linear polarization in EUV/FUV spectral lines originating in the outer solar atmosphere, specifically: (1) a new coronagraph/polarimeter operating at 1215.7 angstrom (neutral hydrogen Lyman-alpha), which could observe this line in the near solar corona and lead to the first direct measurements of both strength and direction of coronal magnetic fields and (2) a new multilayer EUV imaging polarimeter, operating at wavelengths of strong helium emission lines (e.g., 304 angstrom, 584 angstrom), which could observe impact polarization phenomena and provide information concerning the relative importance of thermal and nonthermal processes in solar flares. The emission mechanisms we will address with these instruments include resonance scattering and impact polarization. Resonance scattering of chromospheric radiation anisotropically illuminating the emitting atoms in the corona can produce up to 20% linear polarization in FUV coronal lines. Modifications, via the Hanle effect, of this polarization would result from the presence of a magnetic field. In the EUV, detectable polarization may be produced by impact polarization, which results from anisotropic collisional excitation of the emitting atoms by particles (electrons, protons) with non-Maxwellian velocity distributions produced during flares. These coronagraph/polarimeter instruments employ all-reflective optical systems utilizing ultrasmooth, low-scatter normal incidence mirrors and reflective polarization analyzers comprised of advanced flow-polished substrates with state-of-the-art thin film FUV interference and EUV multilayer coatings. The reflecting polarization analyzers operate at the Brewster angle. We discuss several instrument configurations and provide theoretical calculations and performance predictions for coronagraph/polarimeter instruments utilizing an optical design similar to the Ritchey-Chretien EUV/FUV telescopes developed for flight on the Stanford/MSFC/LLNL Multi-Spectral Solar Telescope Array (MSSTA). C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,STANFORD,CA 94305. RP HOOVER, RB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES52,HUNTSVILLE,AL 35812, USA. NR 23 TC 3 Z9 3 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 AUG PY 1991 VL 30 IS 8 BP 1169 EP 1176 DI 10.1117/12.55923 PG 8 WC Optics SC Optics GA FZ612 UT WOS:A1991FZ61200018 ER PT J AU LOWELL, CE BARRETT, CA PALMER, RW AUPING, JV PROBST, HB AF LOWELL, CE BARRETT, CA PALMER, RW AUPING, JV PROBST, HB TI COSP - A COMPUTER-MODEL OF CYCLIC OXIDATION SO OXIDATION OF METALS LA English DT Article DE CYCLIC OXIDATION; MODEL; HIGH TEMPERATURE; ALLOYS; COATINGS ID HIGH-TEMPERATURE OXIDATION; ALLOYS; RESISTANCE; ZIRCONIUM; ADHERENCE AB A computer model useful in predicting the cyclic oxidation behavior of alloys is presented. The model considers the oxygen uptake due to scale formation during the heating cycle and the loss of oxide due to spalling during the cooling cycle. The balance between scale formation and scale loss is modeled and used to predict weight change and metal loss kinetics. A simple uniform spalling model is compared to a more complex random spall site model. In nearly all cases, the simpler uniform spall model gave predictions as accurate as the more complex model. The model has been applied to several nickel-base alloys which, depending upon composition, form Al2O3 or Cr2O3 during oxidation. The model has been validated by several experimental approaches. Versions of the model that run on a personal computer are available. RP LOWELL, CE (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 35 TC 88 Z9 90 U1 3 U2 6 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD AUG PY 1991 VL 36 IS 1-2 BP 81 EP 112 DI 10.1007/BF00938457 PG 32 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA FY235 UT WOS:A1991FY23500005 ER PT J AU DOYCHAK, J HEBSUR, MG AF DOYCHAK, J HEBSUR, MG TI PROTECTIVE AL2O3 SCALE FORMATION ON NBAL3-BASE ALLOYS SO OXIDATION OF METALS LA English DT Article DE OXIDATION; ALUMINIDE INTERMETALLICS; NIOBIUM ALUMINUM CHROMIUM ALLOYS; REACTIVE ELEMENT EFFECT; ALUMINUM OXIDE SCALES ID TRANSIENT OXIDATION AB The oxidation of NbA13 with additions of Cr and Y was studied to determine the mechanisms of the beneficial effects of these elements upon oxidation. Cr additions to the binary NbA13 alloy of up to 6.8 at. % reduced the scale growth rates and promoted alpha-Al2O3 formation over much longer times relative to binary NbAl3. A major effect of Cr is to form a layer of AlNbCr at the metal/scale interface, which is inherently more oxidation-resistant than the matrix alloy in the long term. Yttrium additions to a Cr-containing alloy improved the scale growth rate and adherence, and changed the scale microstructure to mimic that of a typical protective Al2O3 scale. C1 SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR GRP,BROOK PK,OH 44142. NR 13 TC 35 Z9 36 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD AUG PY 1991 VL 36 IS 1-2 BP 113 EP 141 DI 10.1007/BF00938458 PG 29 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA FY235 UT WOS:A1991FY23500006 ER PT J AU RIGNOT, EJM KOWK, R CURLANDER, JC PANG, SS AF RIGNOT, EJM KOWK, R CURLANDER, JC PANG, SS TI AUTOMATED MULTISENSOR REGISTRATION - REQUIREMENTS AND TECHNIQUES SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID EDGE-DETECTION; RECTIFICATION; IMAGERY AB The synergistic utilization of data from a suite of remote sensors requires multi-dimensional analysis of the data. Prior to this analysis, processing is required to correct for the systematic geometric distortions characteristic of each sensor, followed by a registration operation to remove any residual offsets. Furthermore, to handle a large volume of data and high data rates, the registration process must be fully automated. A conceptual approach is presented that integrates a variety of registration techniques and selects the candidate algorithm based on certain performance criteria. The performance requirements for an operational algorithm are formulated given the spatially, temporally, and spectrally varying factors that influence the image characteristics and the science requirements of various applications. Several computational techniques are tested and their performance evaluated using a multisensor test data set assembled from the Landsat TM, Seasat, SIR-B, TIMS, and SPOT sensors. The results are discussed and recommendations for future RP RIGNOT, EJM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 25 TC 44 Z9 46 U1 0 U2 2 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 AUG PY 1991 VL 57 IS 8 BP 1029 EP 1038 PG 10 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA FZ434 UT WOS:A1991FZ43400002 ER PT J AU WALL, SD FARR, TG MULLER, JP LEWIS, P LEBERL, FW AF WALL, SD FARR, TG MULLER, JP LEWIS, P LEBERL, FW TI MEASUREMENT OF SURFACE MICROTOPOGRAPHY SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID ROUGHNESS AB Acquisition of ground truth data for use in microwave interaction modeling requires measurement of surface roughness sampled at intervals comparable to a fraction of the microwave wavelength and extensive enough to adequately represent the statistics of a surface unit. Sub-centimetric measurement accuracy is thus required over large areas, and existing techniques are usually inadequate. A technique is discussed for acquiring the necessary photogrammetric data using twin film cameras mounted on a helicopter. In an attempt to eliminate tedious data reduction, an automated technique was applied to the helicopter photographs, and results were compared to those produced by conventional stereogrammetry. Derived root-mean-square (RMS) roughness for the same stereo-pair was 7.5 cm for the automated technique versus 6.5 cm for the manual method. The principal source of error is probably due to vegetation in the scene, which affects the automated technique but is ignored by a human operator. C1 UNIV LONDON UNIV COLL,DEPT PHOTOGRAMMETRY & SURVEYING,LONDON WC1E 6BT,ENGLAND. VEXCEL CORP,BOULDER,CO 80301. RP WALL, SD (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Lewis, Philip/C-1588-2008; OI Lewis, Philip/0000-0002-8562-0633; Farr, Thomas/0000-0001-5406-2096 NR 24 TC 8 Z9 9 U1 0 U2 0 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 AUG PY 1991 VL 57 IS 8 BP 1075 EP 1078 PG 4 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA FZ434 UT WOS:A1991FZ43400007 ER PT J AU KROK, PC ELMER, P KRUEGER, A AF KROK, PC ELMER, P KRUEGER, A TI OZONE, VOLCANIC ASH MONITORED FROM SPACE SO PHOTONICS SPECTRA LA English DT Article RP KROK, PC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAURIN PUBL CO INC PI PITTSFIELD PA BERKSHIRE COMMON PO BOX 1146, PITTSFIELD, MA 01202 SN 0731-1230 J9 PHOTON SPECTRA JI Photon. Spect. PD AUG PY 1991 VL 25 IS 8 BP 80 EP 81 PG 2 WC Optics SC Optics GA FZ430 UT WOS:A1991FZ43000014 ER PT J AU GREEN, R AF GREEN, R TI REMOTE-SENSING SOARS TO NEW HEIGHTS SO PHOTONICS SPECTRA LA English DT Article RP GREEN, R (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAURIN PUBL CO INC PI PITTSFIELD PA BERKSHIRE COMMON PO BOX 1146, PITTSFIELD, MA 01202 SN 0731-1230 J9 PHOTON SPECTRA JI Photon. Spect. PD AUG PY 1991 VL 25 IS 8 BP 81 EP 81 PG 1 WC Optics SC Optics GA FZ430 UT WOS:A1991FZ43000015 ER PT J AU SHEN, HH AF SHEN, HH TI NONCONSERVATIVE DYNAMICS OF VORTICAL STRUCTURES - A STATISTICAL-MECHANICAL PERSPECTIVE SO PHYSICA D LA English DT Article; Proceedings Paper CT 10TH ANNUAL INTERNATIONAL CONF OF THE CENTER FOR NONLINEAR STUDIES - NONLINEAR SCIENCE : THE NEXT DECADE CY MAY 21-25, 1990 CL LOS ALAMOS, NM SP CTR NONLINEAR STUDIES ID TURBULENT-FLOW; FLUID AB Of great interest currently in turbulent fluids are processes which do not conserve local vorticity, such as viscous decay and production and cut-and-reconnection of vortex lines. Here we examine these processes from two complementary, novel points of view. Both involve the discretization of vortex lines as well as explicit description of the inherent stochasticity. The first is a quantized or particle approach and focusses on the crucial role played by viscous decay and production in determining flow statistics. The second is a continuum or field approach and goes further to elucidate the real-space structures and instabilities in the flow. In both approaches, statistical-mechanical treatment of a nonlinear system enables us to offer some insight into these nonconservative processes. RP SHEN, HH (reprint author), NASA,AMES RES CTR,CTR TURBULENCE RES,MS 202A-1,MOFFETT FIELD,CA 94035, USA. NR 37 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2789 J9 PHYSICA D JI Physica D PD AUG PY 1991 VL 51 IS 1-3 BP 555 EP 566 DI 10.1016/0167-2789(91)90262-8 PG 12 WC Mathematics, Applied; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA GH639 UT WOS:A1991GH63900046 ER PT J AU CHOI, HC MOIN, P KIM, J AF CHOI, HC MOIN, P KIM, J TI ON THE EFFECT OF RIBLETS IN FULLY-DEVELOPED LAMINAR CHANNEL FLOWS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID DRAG REDUCTION AB The effect of longitudinal riblet surfaces on viscous drag in fully developed laminar channel flows was investigated. Unlike turbulent flows, drag reduction was not obtained in the laminar flows. Results were independent of Reynolds number. Wall-shear rates on most regions of the cross-sectional perimeter of riblets were smaller than that of corresponding plane channel flow even though the net drag was increased. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CHOI, HC (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI Choi, Haecheon/D-1016-2011 OI Choi, Haecheon/0000-0003-0696-847X NR 7 TC 29 Z9 30 U1 2 U2 12 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 AUG PY 1991 VL 3 IS 8 BP 1892 EP 1896 DI 10.1063/1.857918 PG 5 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FY795 UT WOS:A1991FY79500007 ER PT J AU SAMIMY, M LELE, SK AF SAMIMY, M LELE, SK TI MOTION OF PARTICLES WITH INERTIA IN A COMPRESSIBLE FREE SHEAR-LAYER SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID TURBULENT; SIMULATIONS; DISPERSION; FLOW; JET AB The effects of inertia of a particle on its flow tracking accuracy and particle dispersion are studied using direct numerical simulations of two-dimensional compressible free shear layers in convective Mach number (M(c)) range of 0.2 to 0.6. The results show that particle response is well characterized by tau, the ratio of particle response time to the flow time scale (Stokes' number). The slip between particle and fluid imposes a fundamental limit on the accuracy of optical measurements such as LDV and PIV. The error is found to grow like tau up to tau = 1 and taper off at higher tau. For tau = 0.2 the error is about 2%. In the flow visualizations based on Mie scattering, particles with tau > 0.05 are found to grossly misrepresent the flow features. These errors are quantified by calculating the dispersion of particles relative to the fluid. The trend in lateral dispersion of particles is similar to that of incompressible flows reported by previous investigators. Overall, the effect of compressibility does not seem to be significant on the motion of particles in the range of M(c) considered here. C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. RP SAMIMY, M (reprint author), OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210, USA. NR 25 TC 157 Z9 161 U1 1 U2 9 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 AUG PY 1991 VL 3 IS 8 BP 1915 EP 1923 DI 10.1063/1.857921 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FY795 UT WOS:A1991FY79500010 ER PT J AU LASSEIGNE, DG JACKSON, TL AF LASSEIGNE, DG JACKSON, TL TI NONLINEAR-INTERACTION OF A DETONATION VORTICITY WAVE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article AB The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multidomain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results whenever obtained in this study agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient encounter with a disturbance, the effects of exothermicity are more pronounced than predicted by linear theory. Finally, it is found that linear theory correctly determines the critical angle. 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 8 TC 10 Z9 10 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 AUG PY 1991 VL 3 IS 8 BP 1972 EP 1979 DI 10.1063/1.857928 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FY795 UT WOS:A1991FY79500017 ER PT J AU SHEBALIN, JV AF SHEBALIN, JV TI THERMOELECTRIC EFFECTS IN DECAYING HOMOGENEOUS MAGNETO-GAS TURBULENCE SO PHYSICS OF FLUIDS B-PLASMA PHYSICS LA English DT Article ID LASER-PRODUCED PLASMAS; FIELD GENERATION; SIMULATION AB In the formulation of compressible magnetohydrodynamics (MHD) (i.e., magneto-gas dynamics), a "generalized Ohm's law" is required. In particular, an electron pressure term and a "Hall effect" term may appear as non-negligible additions to the Ohm's law that is conventionally used for incompressible MHD. In "high-beta" (i.e., relatively low magnetic energy) situations, the Hall term may be neglected (at least initially) but, as it turns out, the electron pressure term cannot be neglected. Here, three-dimensional, high-beta, homogeneous, decaying, magneto-gas turbulence is examined with regard to this additional term. Through numerical simulation, it is found that "thermoelectric effects" are produced that significantly alter the evolution of the magnetic field and electric current strengths. RP SHEBALIN, JV (reprint author), NATL AERONAUT & SPACE ADM,LANGLEY RES CTR,MAIL STOP 490,HAMPTON,VA 23665, USA. NR 30 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 0899-8221 J9 PHYS FLUIDS B-PLASMA PD AUG PY 1991 VL 3 IS 8 BP 1990 EP 1993 DI 10.1063/1.859667 PN 1 PG 4 WC Physics, Fluids & Plasmas SC Physics GA FY448 UT WOS:A1991FY44800021 ER PT J AU HARDING, AK AF HARDING, AK TI THE PHYSICS OF GAMMA-RAY BURSTS SO PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS LA English DT Review ID STRONG MAGNETIC-FIELDS; MAGNETOSPHERIC PLASMA-OSCILLATIONS; NONTHERMAL SYNCHROTRON RADIATION; CYCLOTRON RESONANT SCATTERING; 2-PHOTON ANNIHILATION LINES; ACCRETING NEUTRON-STARS; RELATIVISTIC PLASMAS; COMPTON-SCATTERING; 5 MARCH; PAIR ANNIHILATION AB Cosmic gamma-ray bursts, transient sources that radiate most of their observable emission in gamma-rays above 10 keV, have been an enigma for two decades. Although a remarkably diverse range of models has been proposed, there is no consensus on the energy source or radiation mechanism of the bursts. This article will review the growing body of evidence that gamma-ray bursts may be galactic neutron stars, as well as the most recent models involving neutron-star origin. RP HARDING, AK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 283 TC 67 Z9 69 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-1573 EI 1873-6270 J9 PHYS REP JI Phys. Rep.-Rev. Sec. Phys. Lett. PD AUG PY 1991 VL 206 IS 6 BP 327 EP 391 DI 10.1016/0370-1573(91)90055-Q PG 65 WC Physics, Multidisciplinary SC Physics GA GD633 UT WOS:A1991GD63300001 ER PT J AU CALVO, SC AF CALVO, SC TI A SHORT EXPOSURE TO DOC EDGERTON SO PHYSICS TODAY LA English DT Letter RP CALVO, SC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, 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 0031-9228 J9 PHYS TODAY JI Phys. Today PD AUG PY 1991 VL 44 IS 8 BP 15 EP 15 DI 10.1063/1.2810201 PN 1 PG 1 WC Physics, Multidisciplinary SC Physics GA GB380 UT WOS:A1991GB38000006 ER PT J AU RUBIN, RH SIMPSON, JP HAAS, MR ERICKSON, EF AF RUBIN, RH SIMPSON, JP HAAS, MR ERICKSON, EF TI MODELING THE ORION NEBULA AS AN AXISYMMETRICAL BLISTER SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article; Proceedings Paper CT TEXAS-MEXICO CONF ON ASTROPHYSICS CY FEB 14-15, 1991 CL RICE UNIV, HOUSTON, TX HO RICE UNIV DE NEBULAE ORION NEBULA; ABUNDANCES; GEOMETRY ID H-II REGIONS; IONS; IRON; IONIZATION; STAR AB We have computed axisymmetric models for the ionized gas in the Orion nebula that treat most of the physical detail of our earlier spherical modeling (Simpson et al. 1986). This "blister" representation is clearly more realistic in light of the spatiokinematic data available from the ionized, neutral, and molecular regions. Based on dynamical considerations, we assume that the density is plane-parallel and increases exponentially away from the observer, up to a maximum value, and then stays constant until the boundary with OMC 1. It is assumed that Orion is viewed face on; hence, our determination of best-fitting model parameters is made by comparing with a large set of observations throughout the nebula assuming a radial dependence from the Trapezium with an azimuthal symmetry in the plane of the sky. Nonsymmetrical features such as the "SE bar" are not addressed by this model. Values derived for the elemental abundances and stellar properties are presented. Similarities and differences between these parameters and those inferred from our earlier spherical model are enumerated. A significant accomplishment of the present model over earlier work is the ability to explain the strong, singly ionized line emission, such as [O II] 3727 angstrom, along lines of sight near the Trapezium. This emission arises in the denser zone on the far side from the Trapezium, where the nebula is ionization bounded. The iron ionization equilibrium has been added to the model. We calculate that Fe IV and Fe III are the dominant species. C1 STANFORD UNIV,DEPT APPL PHYS,STANFORD,CA 94305. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP RUBIN, RH (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 18 TC 27 Z9 27 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 AUG PY 1991 VL 103 IS 666 BP 834 EP 837 DI 10.1086/132889 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GD537 UT WOS:A1991GD53700018 ER PT J AU HECHT, MH BELL, LD KAISER, WJ AF HECHT, MH BELL, LD KAISER, WJ TI BEEM TAKES STM IMAGING BELOW THE SURFACE SO R&D MAGAZINE LA English DT Article RP HECHT, MH (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 2 PU CAHNERS-DENVER PUBLISHING CO PI HIGHLANDS RANCH PA 8773 S RIDGELINE BLVD, HIGHLANDS RANCH, CO 80126-2329 SN 0746-9179 J9 R&D MAG JI R D Mag. PD AUG PY 1991 VL 33 IS 9 BP 63 EP 64 PG 2 WC Engineering, Industrial; Multidisciplinary Sciences SC Engineering; Science & Technology - Other Topics GA GA491 UT WOS:A1991GA49100017 ER PT J AU CUCINOTTA, FA KATZ, R WILSON, JW TOWNSEND, LW SHINN, J HAJNAL, F AF CUCINOTTA, FA KATZ, R WILSON, JW TOWNSEND, LW SHINN, J HAJNAL, F TI BIOLOGICAL EFFECTIVENESS OF HIGH-ENERGY PROTONS - TARGET FRAGMENTATION SO RADIATION RESEARCH LA English DT Article ID RADIATION; BEAM; CELLS C1 UNIV NEBRASKA,LINCOLN,NE 68588. ROCKWELL INT CORP,DIV SPACE TRANSPORTAT SYST,HOUSTON,TX 77058. US DOE,NEW YORK,NY 10014. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 30 TC 28 Z9 28 U1 2 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 AUG PY 1991 VL 127 IS 2 BP 130 EP 137 DI 10.2307/3577956 PG 8 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA GA110 UT WOS:A1991GA11000002 PM 1658843 ER PT J AU FOSTER, JL HALL, DK AF FOSTER, JL HALL, DK TI OBSERVATIONS OF SNOW AND ICE FEATURES DURING THE POLAR WINTER USING MOONLIGHT AS A SOURCE OF ILLUMINATION SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB Sunlight reflected off the surface of the moon provides sufficient illumination for nighttime imaging of the earth from those spacecraft on which the instruments are sensitive to low light levels. The Defense Meteorological Satellite Program (DMSP) series of satellites are at present the only systems capable of furnishing visible nocturnal images of the earth from space. Features having a high albedo in the visible wavelengths, such as snow and ice, can easily be identified on moonlit nights when the moon is in the gibbous or full phases. Little information exists about the distribution of leads, fractures, and polynya on a basin-wide scale in the winter pack ice, and knowledge of oceanic and atmospheric fluxes is hindered by the limited data available in winter. The DMSP data is a relatively untapped source for observing polar regions during the winter. Using nighttime imagery is a novel way to explore polar areas during the winter months when the sun is below the horizon for much of the time. RP FOSTER, JL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Hall, Dorothy/D-5562-2012 NR 23 TC 6 Z9 6 U1 1 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 AUG PY 1991 VL 37 IS 2 BP 77 EP 88 DI 10.1016/0034-4257(91)90020-7 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GF904 UT WOS:A1991GF90400001 ER PT J AU COTTON, JD KAUFMAN, MJ NOEBE, RD AF COTTON, JD KAUFMAN, MJ NOEBE, RD TI CONSTITUTION OF PSEUDOBINARY HYPOEUTECTIC BETA-NIAL + ALPHA-V ALLOYS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP COTTON, JD (reprint author), UNIV FLORIDA,DEPT MAT SCI & ENGN,GAINESVILLE,FL 32611, USA. RI Kaufman, Michael/A-7737-2012 NR 9 TC 20 Z9 20 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD AUG PY 1991 VL 25 IS 8 BP 1827 EP 1832 DI 10.1016/0956-716X(91)90312-O PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FZ561 UT WOS:A1991FZ56100013 ER PT J AU BOZZOLO, G FERRANTE, J SMITH, JR AF BOZZOLO, G FERRANTE, J SMITH, JR TI UNIVERSAL BEHAVIOR IN IDEAL SLIP SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID ENERGY C1 ANALEX CORP,FAIRVIEW PK,OH 44126. GM CORP,RES LABS,DEPT PHYS,WARREN,MI 48090. RP BOZZOLO, G (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 21 Z9 21 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD AUG PY 1991 VL 25 IS 8 BP 1927 EP 1931 DI 10.1016/0956-716X(91)90330-4 PG 5 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FZ561 UT WOS:A1991FZ56100031 ER PT J AU TADMOR, E AF TADMOR, E TI LOCAL ERROR-ESTIMATES FOR DISCONTINUOUS SOLUTIONS OF NONLINEAR HYPERBOLIC-EQUATIONS SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE CONSERVATION LAWS; VISCOSITY APPROXIMATION; ONE-SIDED LIPSCHITZ CONTINUITY; POST-PROCESSING; ERROR ESTIMATES ID SCALAR CONSERVATION-LAWS; CONVERGENCE; SCHEMES AB Let u(x, t) be the possibly discontinuous entropy solution of a nonlinear scalar conservation law with smooth initial data. Suppose u-epsilon(x, t) is the solution of an approximate viscosity regularization, where epsilon > 0 is the small viscosity amplitude. It is shown that by post-processing the small viscosity approximation u-epsilon, pointwise values of u and its derivatives with an error as close to epsilon as desired can be recovered. The analysis relies on the adjoint problem of the forward error equation, which in this case amounts to a backward linear transport equation with discontinuous coefficients. The novelty of our approach is to use a (generalized) E-condition of the forward problem in order to deduce a W1, infinity-energy estimate for the discontinuous backward transport equation; this, in turn, leads to epsilon-uniform estimate on moments of the error u-epsilon - u. The approach presented does not "follow the characteristics" and, therefore, applies mutatis mutandis to other approximate solutions such as E-difference schemes. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP TADMOR, E (reprint author), TEL AVIV UNIV,SCH MATH SCI,IL-69978 TEL AVIV,ISRAEL. OI Tadmor, Eitan/0000-0001-7424-6327 NR 18 TC 95 Z9 97 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0036-1429 J9 SIAM J NUMER ANAL JI SIAM J. Numer. Anal. PD AUG PY 1991 VL 28 IS 4 BP 891 EP 906 DI 10.1137/0728048 PG 16 WC Mathematics, Applied SC Mathematics GA FY957 UT WOS:A1991FY95700001 ER PT J AU BARNES, RJH AF BARNES, RJH TI CHANGING PATTERNS OF INTERNATIONAL SPACE COOPERATION - JOHNSONFREESE,J SO SPACE POLICY LA English DT Book Review RP BARNES, RJH (reprint author), NASAS INT AFFAIRS OFF & INT SPACE CONSULTANT,1503 DUMBARTON ROCK CT NW,WASHINGTON,DC 20007, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0265-9646 J9 SPACE POLICY JI Space Policy PD AUG PY 1991 VL 7 IS 3 BP 273 EP 274 DI 10.1016/0265-9646(91)90012-7 PG 2 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA GF019 UT WOS:A1991GF01900011 ER PT J AU VANDERSANDE, JW ZOLTAN, LD AF VANDERSANDE, JW ZOLTAN, LD TI HIGH-TEMPERATURE ELECTRICAL-CONDUCTIVITY MEASUREMENTS OF NATURAL DIAMOND AND DIAMOND FILMS SO SURFACE & COATINGS TECHNOLOGY LA English DT Article; Proceedings Paper CT 1ST EUROPEAN CONF ON DIAMOND AND DIAMOND-LIKE CARBON COATINGS CY SEP 17-19, 1990 CL CRANS-MONTANA, SWITZERLAND SP COMMISS EUROPEAN COMMUNITIES, ATOM ENERGY AUTHORITY TECHNOL, HARWELL LAB AB The electrical conductivity of diamond films and diamond-like carbon films were measured from room temperature to 1200-degrees-C. These results are the first known measurements for diamond films in this temperature range. The measurements were compared with the conductivity of two natural type IIa diamonds measured with the same apparatus. The activation energy for the two natural type IIa diamonds was found to be 1.4 eV, in agreement with earlier measurements on type I diamonds. The room temperature conductivities of the two diamond films were found to be higher than that of natural IIa diamond, but were found to approach or even just fall below that of natural IIa diamond at elevated temperatures. This difference, and the difference in slope of the conductivities of the various samples, are indicative of the difference in type and number of impurity and structural defects accounting for conductivity in the different samples. These results offer promise that diamond films could be fabricated which have an electrical resistivity exceeding that of natural IIa diamond. RP VANDERSANDE, JW (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 14 Z9 14 U1 1 U2 4 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD AUG PY 1991 VL 47 IS 1-3 BP 392 EP 400 DI 10.1016/0257-8972(91)90305-G PG 9 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA GD453 UT WOS:A1991GD45300045 ER PT J AU KOLB, EW TURNER, MS CHAKRAVORTY, A SCHRAMM, DN AF KOLB, EW TURNER, MS CHAKRAVORTY, A SCHRAMM, DN TI CONSTRAINTS FROM PRIMORDIAL NUCLEOSYNTHESIS ON THE MASS OF THE TAU NEUTRINO SO PHYSICAL REVIEW LETTERS LA English DT Article ID BIG-BANG NUCLEOSYNTHESIS; THERMONUCLEAR REACTION-RATES; COSMOLOGICAL CONSTRAINTS; PARTICLES; SYMMETRY AB The familiar nucleosynthesis constraint on the number of neutrino species, N(v) less-than-or-equal-to 3.4, applies to massless neutrino species. An MeV-mass neutrino can have even greater impact, and we show that primordial nucleosynthesis excludes a tau-neutrino mass from 0.3 to 25 MeV (Dirac) and 0.5 to 25 MeV (Majorana) provided that its lifetime tau-v greater-than-or-similar-to sec, and from 0.3 to 30 MeV (Dirac) and 0.5 to 32 MeV (Majorana) for tau-v greater-than-or-similar-to 10(3) sec. A modest improvement in the laboratory mass limit - from 35 to 25 MeV - would imply that the tau-neutrino mass must be less than 0.5 MeV (provided tau-v greater-than-or-similar-to 1 sec). C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. RP KOLB, EW (reprint author), FERMI NATL ACCELERATOR LAB,NASA,CTR ASTROPHYS,BATAVIA,IL 60510, USA. NR 32 TC 71 Z9 71 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 JUL 29 PY 1991 VL 67 IS 5 BP 533 EP 536 DI 10.1103/PhysRevLett.67.533 PG 4 WC Physics, Multidisciplinary SC Physics GA FY505 UT WOS:A1991FY50500002 ER PT J AU MOORE, CE CARDELINO, BH AF MOORE, CE CARDELINO, BH TI STATIC 2ND-ORDER POLARIZABILITIES OF AMINOBENZOPHENONES AND NITROBENZOPHENONES SO THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE LA English DT Article ID SUBSTITUTED CONJUGATED MOLECULES; POLYSTYRENE MATRICES; HYPERPOLARIZABILITIES; BENZOPHENONE; PHOSPHORESCENCE; PHOTOCHEMISTRY; MNDO AB Static-field theoretical studies on molecular second-order polarizabilities (beta) of benzophenone derivatives were performed. Calculations were based on the use of shaped electric fields and semi-empirical Hamiltonians. Either an electron-donating (amine) or an electron-withdrawing (nitro) substituent was incorporated into a phenyl ring of benzophenone; the phenyl rings of benzophenone were oriented either coplanar or perpendicular to the carbonyl. The change in charge transfer with respect to the electrophilic character of the carbonyl group was monitored to determine its effect on the molecular second-order polarizability. Calculations were performed for all constitutional isomers of the two benzophenone derivatives. C1 ATLANTA UNIV CTR,SPELMAN COLL,DOLPHUS E MILLIGAN SCI RES INST,ATLANTA,GA 30360. RP MOORE, CE (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 31 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-1280 J9 THEOCHEM-J MOL STRUC JI Theochem-J. Mol. Struct. PD JUL 26 PY 1991 VL 78 BP 79 EP 96 PG 18 WC Chemistry, Physical SC Chemistry GA GC397 UT WOS:A1991GC39700008 ER PT J AU SMITH, RH LEU, MT KEYSER, LF AF SMITH, RH LEU, MT KEYSER, LF TI INFRARED-SPECTRA OF SOLID FILMS FORMED FROM VAPORS CONTAINING WATER AND NITRIC-ACID SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POLAR STRATOSPHERIC CLOUD; HETEROGENEOUS REACTIONS; HYDROGEN-BOND; OZONE HOLE; TRIHYDRATE; ION; CONDENSATION; HNO3; ICE AB Infrared spectra have been recorded at 188 K for crystalline mono- and trihydrates of nitric acid formed by vapor deposition. In addition, spectra of fully deuterated forms of these same compounds have been obtained. These spectra have been interpreted in terms of the known ionic structures of the hydrates and the known spectra of oxonium and nitrate ions. Two other less stable solids were formed, a molecular hydrogen-bonded HNO3.H2O complex, stable only at temperatures below 120 or 150 K, and a substance thought to be a crystalline mixture of trihydrate and ice which sometimes formed from water-rich vapors and which upon pumping and/or warming could be converted into crystalline trihydrate. While these four substances appear to be the four species recently reported by Ritzhaupt and Devlin, we disagree with their allocation of structures to two of them. In particular, we disagree with their claims that a stable dihydrate exists. The relevance of the results to the stratospheric "ozone hole" problem is discussed. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. NR 26 TC 41 Z9 41 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 JUL 25 PY 1991 VL 95 IS 15 BP 5924 EP 5930 DI 10.1021/j100168a040 PG 7 WC Chemistry, Physical SC Chemistry GA FY388 UT WOS:A1991FY38800040 ER PT J AU THOMPSON, AM AF THOMPSON, AM TI NEW OZONE HOLE PHENOMENON SO NATURE LA English DT Editorial Material ID TROPOSPHERIC OZONE; ANTARCTICA RP THOMPSON, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 10 TC 13 Z9 13 U1 0 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUL 25 PY 1991 VL 352 IS 6333 BP 282 EP 283 DI 10.1038/352282a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FY289 UT WOS:A1991FY28900034 ER PT J AU REDD, C ZOLENSKY, M AF REDD, C ZOLENSKY, M TI TOO EXPOSED SO NATURE LA English DT Letter C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP REDD, C (reprint author), UNIV HOUSTON CLEAR LAKE, HOUSTON, TX 77058 USA. NR 1 TC 0 Z9 0 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 JUL 25 PY 1991 VL 352 IS 6333 BP 289 EP 289 DI 10.1038/352289a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FY289 UT WOS:A1991FY28900045 ER PT J AU HUNTRESS, WT ALLEN, M DELITSKY, M AF HUNTRESS, WT ALLEN, M DELITSKY, M TI CARBON SUBOXIDE IN COMET HALLEY SO NATURE LA English DT Article ID ELECTRON-IMPACT IONIZATION; INDUCED CHEMICAL-REACTIONS; HYDROGEN MIXTURE; ION COMPOSITION; DUST PARTICLES; P/HALLEY; GIOTTO; EMISSION; MONOXIDE; GAS AB OBSERVATIONAL data acquired during the recent appearance of comet Halley pose a puzzle about the nature and distribution of elemental carbon and carbonaceous material in its nucleus and coma. The nucleus is darker even than coal (albedo < 4%) 1, suggesting that its volatile ices contain a few per cent of carbonaceous material in the form of graphitic or amorphous carbon. The very high abundance of light elements in the coma dust 2,3, particularly H, C, N and O, suggests the presence of a significant organic component. The emission feature near 3.4-mu-m also implies the presence of organic material in the dust 4-6. But the parent species for the primary carbon-containing material that have been identified so far (such as CO, CO2 and CH4) are not present in sufficient quantities to account for all of it. Here we propose that an additional contribution from carbon suboxide (C3O2) in the coma dust and the nucleus material is consistent with the observational data. A production rate in the coma for C3O2 of about 0.03-0.04 times that of water would provide the distributed source of elemental carbon and CO within 10(4) km of the nucleus that is required to explain the data from the Giotto spacecraft and from ground-based observations. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,4800 OAK GROVE DR,PASADENA,CA 91109. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. NASA,DIV SOLAR SYST EXPLORAT,WASHINGTON,DC 20546. NR 46 TC 43 Z9 43 U1 1 U2 7 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUL 25 PY 1991 VL 352 IS 6333 BP 316 EP 318 DI 10.1038/352316a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FY289 UT WOS:A1991FY28900063 ER PT J AU VITTA, S AF VITTA, S TI RAPID SOLIDIFICATION OF POLYMORPHIC TRANSITION-METALS INDUCED BY NANOSECOND LASER-PULSES SO APPLIED PHYSICS LETTERS LA English DT Article AB A Nd-YAG laser giving 5 ns, 266 nm pulses was used to melt and subsequently quench thin, pure metallic films on a liquid Al/Al2O3 substrate at 10(10)-10(12) K s-1. Transmission electron microscopy together with electron diffraction was used to study the competitive nucleation and growth behavior of the crystals from the undercooled melt. In the case of Fe and Co the high-temperature bcc and fcc structures were retained after laser quenching. Ti and Zr in spite of the structural similarities exhibit different preferences for nucleation from the undercooled melt. In all the metals the solid-state transformations were completely suppressed and the crystal growth was found to be limited by the collisional frequency of the atoms onto the growing Interface. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RI Vitta, Satish/K-7336-2015 OI Vitta, Satish/0000-0003-4138-0022 NR 11 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 22 PY 1991 VL 59 IS 4 BP 411 EP 413 DI 10.1063/1.105447 PG 3 WC Physics, Applied SC Physics GA FX626 UT WOS:A1991FX62600011 ER PT J AU MARGOLIS, JS POYNTER, RL AF MARGOLIS, JS POYNTER, RL TI LOW-TEMPERATURE HYDROGEN BROADENED LINEWIDTHS OF AMMONIA IN THE (0,1,0,0)[-(0,0,0,0) BAND AT 200-K SO APPLIED OPTICS LA English DT Article ID GROUND-STATE; DIODE-LASER; NU-2 BAND; LINES; NH3; SPECTROSCOPY; PARAMETERS; (NH3)-N-14; LINESTRENGTHS; TRANSITIONS AB Fourier transform spectra of the (0,1,0,0) <-- (0,0,0,0) band of ammonia have been measured for values of the hydrogen broadened linewidth parameters at a temperature of 200 K. The halfwidths for > 200 lines have been determined with an average RMS of 5% in the interval between 750 and 1250 cm-1. No measurements of the widths in the (s)R branch, and only 12 widths in the (s)Q branch, were obtained because of severe blending of the J-K manifolds. The broadening coefficients vary between 0.06 and 0.14 cm-1/atm. for (J,K) < (12,12). RP MARGOLIS, JS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 26 TC 16 Z9 16 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1991 VL 30 IS 21 BP 3023 EP 3028 PG 6 WC Optics SC Optics GA FX920 UT WOS:A1991FX92000021 PM 20706350 ER PT J AU JOSEPH, JH KAUFMAN, YJ MEKLER, Y AF JOSEPH, JH KAUFMAN, YJ MEKLER, Y TI URBAN LIGHT POLLUTION - THE EFFECT OF ATMOSPHERIC AEROSOLS ON ASTRONOMICAL OBSERVATIONS AT NIGHT SO APPLIED OPTICS LA English DT Article DE AEROSOLS; ASTRONOMY; LIGHT POLLUTION; RADIATIVE TRANSFER SIGNAL-TO-NOISE RATIO AB The transfer of diffuse city light from a localized source through a dust-laden atmosphere with optical depth < 0.5 has been analyzed in the source-observer plane on the basis of an approximate treatment. The effect on several types of astronomical observation at night has been studied, considering different size distributions and amounts as well as particle shapes of the aerosols. The analysis is made not as a function of the absolute aerosol amount but in terms of the signal-to-noise ratios for a given amount of aerosol. The model is applied to conditions at the Wise Astronomical Observatory in the Negev desert and limiting backgrounds for spectroscopy, photometry, and photography of stars and extended objects have been calculated for a variety of signal-to-noise ratios. Applications to observations with different equipment at various distances from an urban area of any size are possible. Due to the use of signal-to-noise ratios, the conclusions are different for the different experimental techniques used in astronomy. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP JOSEPH, JH (reprint author), TEL AVIV UNIV,DEPT GEOPHYS & PLANETARY SCI,IL-69978 TEL AVIV,ISRAEL. NR 11 TC 11 Z9 11 U1 1 U2 7 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1991 VL 30 IS 21 BP 3047 EP 3058 PG 12 WC Optics SC Optics GA FX920 UT WOS:A1991FX92000025 PM 20706354 ER PT J AU WALKER, TP STEIGMAN, G SCHRAMM, DN OLIVE, KA KANG, HS AF WALKER, TP STEIGMAN, G SCHRAMM, DN OLIVE, KA KANG, HS TI PRIMORDIAL NUCLEOSYNTHESIS REDUX SO ASTROPHYSICAL JOURNAL LA English DT Article DE ABUNDANCES; EARLY UNIVERSE; ELEMENTARY PARTICLES; NUCLEOSYNTHESIS ID BIG-BANG NUCLEOSYNTHESIS; H-II REGIONS; THERMONUCLEAR REACTION-RATES; NEUTRON-LIFETIME MEASUREMENT; COSMIC-BACKGROUND-RADIATION; HELIUM ABUNDANCE; HALO DWARFS; LITHIUM ABUNDANCE; EARLY UNIVERSE; COSMOLOGICAL CONSTRAINTS AB The latest nuclear reaction cross sections (including the most recent determinations of the neutron lifetime) are used to recalculate the abundances of deuterium, He-3, He-4, and Li-7 within the framework of primordial nucleosynthesis in the standard (homogeneous and isotropic) hot, big bang model. The observational data leading to estimates of (or bounds to) the primordial abundances of the light elements is reviewed with an emphasis on Li-7 and He-4. A comparison between theory and observation reveals the consistency of the predictions of the standard model and leads to bounds to the nucleon-to-photon ratio, 2.8 less-than-or-equal-to eta-10 less-than-or-equal-to 4.0 (eta-10 = 10(10)n(B)/n-gamma), which constrains the baryon density parameter, OMEGA-B h50(2) = 0.05 +/- 0.01 (the Hubble parameter is H0 = 50h50 km s-1 Mpc-1). These bounds imply that the bulk of the baryons in the universe are dark if OMEGA-TOT = 1 and would require that the universe be dominated by nonbaryonic matter. An upper bound to the primordial mass fraction of He-4, Y(p) less-than-or-equal-to 0.240, constrains the number of light (equivalent) neutrinos to N-nu less-than-or-equal-to 3.3, in excellent agreement with the LEP and SLC collider results. Alternatively, for N-nu = 3, we bound the predicted primordial abundance of He-4: 0.236 less-than-or-equal-to Y(p) less-than-or-equal-to 0.243 (for 882 less-than-or-equal-to tau-n less-than-or-equal-to 896 s). C1 OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. UNIV CHICAGO,CHICAGO,IL 60637. NASA,FERMILAB ASTROPHYS GRP,FNAL,BATAVIA,IL 60510. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. LAB ANNECY LE VIEUX PHYS PARTICULES,ANNECY LE VIEUX,FRANCE. RP WALKER, TP (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138, USA. NR 140 TC 898 Z9 900 U1 1 U2 13 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1991 VL 376 IS 1 BP 51 EP 69 DI 10.1086/170255 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX238 UT WOS:A1991FX23800007 ER PT J AU LOCHNER, JC SWANK, JH SZYMKOWIAK, AE AF LOCHNER, JC SWANK, JH SZYMKOWIAK, AE TI SHOT MODEL PARAMETERS FOR CYGNUS-X-1 THROUGH PHASE PORTRAIT FITTING SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUMERICAL METHODS; STARS, INDIVIDUAL (CYGNUS-X-1); STARS, VARIABLES; X-RAYS, SOURCES ID TURBULENT ACCRETION DISKS; RAPID VARIABILITY; DYNAMO ACTION; BLACK-HOLES; X-RAYS; X-1 AB We have developed shot models for systems having a approximately 1/f power density spectrum by utilizing a distribution of shot durations. Parameters of the distribution are determined by fitting the power spectrum either with analytic forms for the spectrum of a shot model with a given shot profile, or with the spectrum derived from numerical realizations of trial shot models. The shot fraction is specified by fitting the phase portrait, which is a plot of intensity at a given time versus intensity at a delayed time and in principle is sensitive to different shot profiles. We have applied these techniques extensively to the X-ray variability of Cygnus X-1, using a HEAO 1 A-2 and an EXOSAT ME observation. We have found that the power spectra suggest models having characteristic shot durations lasting from milliseconds to a few seconds, while the phase portrait fits give shot fractions of approximately 50%. Best fits to the portraits are obtained if we let the amplitude of the shot be a power-law function of the duration of the shot. These fits prefer shots having a symmetric exponential rise and decay. We interpret our result in terms of a distribution of magnetic flares in the accretion disk. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, CODE 6660, GREENBELT, MD 20771 USA. UNIV MARYLAND, DEPT PHYS & ASTRON, COLLEGE PK, MD 20742 USA. RI Swank, Jean/F-2693-2012 NR 30 TC 57 Z9 59 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 JUL 20 PY 1991 VL 376 IS 1 BP 295 EP 311 DI 10.1086/170280 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX238 UT WOS:A1991FX23800032 ER EF