FN Thomson Reuters Web of Science™ VR 1.0 PT J AU SCHWARTZ, RA ORWIG, LE DENNIS, BR LING, JC WHEATON, WA AF SCHWARTZ, RA ORWIG, LE DENNIS, BR LING, JC WHEATON, WA TI SMM/HXRBS OBSERVATIONS OF CYGNUS-X-1 FROM 1986 DECEMBER TO 1988 APRIL SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (CYGNUS-X-1); X-RAYS, BINARIES; X-RAYS, SPECTRA ID ANNIHILATION RADIATION; RAY; X-1; SPECTRUM; HARD AB We report on 30 hard X-ray measurements of Cygnus X-1 made with a Solar Maximum Mission (SMM) Hard X-Ray Burst Spectrometer (HXRBS); 24 offset points from solar pointing were made to view Cygnus X-1 from 1986 December 22 through 1987 April 3, and six additional observations from 1988 January 28 through March 8. This resulted in a data set broad in synoptic coverage (6 months spread over approximately 1.5 yr) but of limited duration (60-70 minutes) for each data point. Ling et al. had previously identified three levels of the 50-300 keV flux from Cygnus X-1 during observations made with HEAO 3 in 1979 and 1980. In order of increasing intensity they named these levels gamma-1, gamma-2, and gamma-3. During the observations reported here, the hard X-ray intensity lay between the gamma-2 and the gamma-3 levels with a range of fluctuations about the average intensity level similar to the range seen by both HEAO 1 and HEAO 3. There was a single observation on 1987 February 24 where the flux exceeded the gamma-3 level, although the flux was close to its average level for 1987 during both the preceding and following observations on 1987 February 19 and March 3. For both the observations in 1987 and 1988, the shape of the photon spectrum was found to be closest to that reported by Ling et al. during the time of the gamma-3 level emission, although the spectral shapes reported for the gamma-2 and gamma-1 levels could not be ruled out. C1 ST SYST CORP,LANHAM,MD. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SCHWARTZ, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,MAIL CODE 6026,GREENBELT,MD 20771, USA. RI Dennis, Brian/C-9511-2012 NR 30 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 JUL 20 PY 1991 VL 376 IS 1 BP 312 EP 321 DI 10.1086/170281 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX238 UT WOS:A1991FX23800033 ER PT J AU MILLER, JA AF MILLER, JA TI MAGNETOHYDRODYNAMIC TURBULENCE DISSIPATION AND STOCHASTIC PROTON ACCELERATION IN SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDROMAGNETICS; PARTICLE ACCELERATION; SUN, FLARES; SUN, PARTICLE EMISSIONS; WAVE MOTIONS ID 1982 JUNE 3; HARD X-RAY; ALFVEN WAVES; PARTICLE-ACCELERATION; FERMI ACCELERATION; TRANSITION REGION; CORONAL HOLES; COSMIC-RAYS; WIND; ENERGY AB Two MHD modes, Alfven and fast magnetosonic waves, are capable of stochastically accelerating protons from super-Alfvenic to ultrarelativistic energies in solar flares. Acceleration occurs through the Landau resonance for fast magnetosonic waves, and through the cyclotron resonance for Alfven waves. The Landau resonance, however, is also satisfied by thermal electrons in a flare plasma, resulting in most of the magnetosonic wave energy being dissipated on electron heating rather than on stochastic proton acceleration. In contrast, thermal electrons cannot satisfy the cyclotron resonance, leaving stochastic gyroresonant proton acceleration as the dominant linear wave-particle interaction for Alfven waves. Alfven waves are also subject to a nonlinear wave-particle interaction as well. Specifically, nonlinear Landau damping is an important dissipation process for Alfven waves under solar flare conditions. Moreover, nonlinear Landau damping efficiently and selectively heats the ambient protons and can thus essentially preaccelerate a significant number of them out of a low-temperature distribution to super-Alfvenic speeds, where they can be subsequently accelerated to ultrarelativistic energies by gyroresonant interactions. A spectrum of Alfven waves, therefore, can energize protons from low-temperature thermal to ultrarelativistic energies through a combination of nonlinear and linear wave-particle interactions. Furthermore, other dissipation processes are unimportant under solar flare conditions, leaving proton heating and acceleration as the dominant damping mechanisms for Alfven waves. RP MILLER, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 60 TC 55 Z9 55 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1991 VL 376 IS 1 BP 342 EP 354 DI 10.1086/170284 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX238 UT WOS:A1991FX23800036 ER PT J AU KAYE, JA DOUGLASS, AR JACKMAN, CH STOLARSKI, RS ZANDER, R ROLAND, G AF KAYE, JA DOUGLASS, AR JACKMAN, CH STOLARSKI, RS ZANDER, R ROLAND, G TI 2-DIMENSIONAL MODEL CALCULATION OF FLUORINE-CONTAINING RESERVOIR SPECIES IN THE STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SPECTROSCOPIC MEASUREMENTS; AIRBORNE MEASUREMENTS; TRACE GASES; HCL; HF; CONSTITUENTS; COF2; SPECTROMETRY; ANTARCTICA; ATMOSPHERE AB Two-dimensional model calculations have been carried out of the distributions of the fluorine-containing reservoir species HF, CF2O, and CFClO. HF constitutes the largest fluorine reservoir in the stratosphere, but CF2O also makes an important contribution to the inorganic fluorine budget. CFClO amounts are most important in the tropical lower stratosphere. HF amounts increase with altitude throughout the stratosphere, while those of CF2O and CFClO fall off above their mixing ratio peaks due to photolysis. The model is in good qualitative agreement with observed vertical profiles of HF and CF2O but tends to underestimate the total column of HF. The calculated CFClO distribution is in good agreement with the very limited data. The disagreement in the HF columns is likely due to small inaccuracies in the model's treatment of lower stratospheric photolysis of chlorofluorocarbons. The model results support the suggestion that CF2O may be heterogeneously converted to HF on the surface of polar stratospheric cloud particles. The model results also suggest that the quantum yield for photolysis of CF2O is near unity. C1 STATE UNIV LIEGE, B-4000 LIEGE, BELGIUM. RP KAYE, JA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Stolarski, Richard/B-8499-2013; Jackman, Charles/D-4699-2012 OI Stolarski, Richard/0000-0001-8722-4012; NR 39 TC 38 Z9 38 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 JUL 20 PY 1991 VL 96 IS D7 BP 12865 EP 12881 DI 10.1029/91JD01178 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100003 ER PT J AU ALLEN, M DELITSKY, ML AF ALLEN, M DELITSKY, ML TI A TEST OF ODD-OXYGEN PHOTOCHEMISTRY USING SPACELAB-3 ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION CROSS-SECTIONS; OZONE PHOTOCHEMISTRY; STRATOSPHERIC OZONE; HERZBERG CONTINUUM; LOWER THERMOSPHERE; SPECTRAL IRRADIANCE; INSITU MEASUREMENTS; MESOSPHERE; NM; DISSOCIATION AB The ozone profile calculated using a one-dimensional time-dependent photochemical model, with recommended absorption cross sections and reaction rate constants, is systematically less than Spacelab 3 (May 1985) Atmospheric Trace Molecule Spectroscopy (ATMOS) observations at sunset (chi = 90-degrees), 30-degrees-N latitude, throughout the upper stratosphere and mesosphere. Model results are approximately 9% smaller than the nominal ATMOS O3 value at 40 km and 50% less at 76 km. Given the uncertainties associated with the ATMOS profile, the model "deficit" may be as large as 15% at 36 km, increasing to approximately 70% at 76 km. A similar model O3 deficit exists at sunrise, 47-degrees-S latitude, in the stratosphere: nominal differences of less-than-or-equal-to 25%, increasing to less-than-or-equal-to 45% when the ATMOS uncertainties are considered. Model results closely approximate ATMOS observations in both the upper stratosphere and mesosphere upon enhancing odd-oxygen production by increasing the O2 Schumann-Runge band and Herzberg continuum cross section values used in the calculations. C1 CALTECH, DIV GEOL & PLANETARY SCI, PASADENA, CA 91109 USA. RP ALLEN, M (reprint author), CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, MAIL CODE 183-601, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 59 TC 22 Z9 22 U1 0 U2 3 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 JUL 20 PY 1991 VL 96 IS D7 BP 12883 EP 12891 DI 10.1029/91JD00230 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100004 ER PT J AU CUNNOLD, DM ZAWODNY, JM CHU, WP POMMEREAU, JP GOUTAIL, F LENOBLE, J MCCORMICK, MP VEIGA, RE MURCRAY, D IWAGAMI, N SHIBASAKI, K SIMON, PC PEETERMANS, W AF CUNNOLD, DM ZAWODNY, JM CHU, WP POMMEREAU, JP GOUTAIL, F LENOBLE, J MCCORMICK, MP VEIGA, RE MURCRAY, D IWAGAMI, N SHIBASAKI, K SIMON, PC PEETERMANS, W TI VALIDATION OF SAGE-II NO2 MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC NO2; NITROGEN-DIOXIDE AB Stratospheric aerosol and gas experiment (SAGE) II satellite-borne measurements of the stratospheric profiles of NO2 at sunset have been made since October 1984. The measurements are made by solar occultation and are derived from the difference between the absorptions in narrow bandwidth channels centered at 0.448 and 0.453-mu-m. The precision of the profiles is approximately 5% between an upper altitude of 36 km and a latitude-dependent lower altitude at which the mixing ratio is 4 ppbv (for example, approximately 25 km at mid-latitudes and 29 km in the tropics). At lower altitudes the precision is approximately 0.2 ppbv. The profiles are nominally smoothed over 1 km except at altitudes where the extinction is less than 2 x 10(-5)/km (approximately 38 km altitude), where 5 km smoothing is employed. The profile measurement noise has an autocorrelation distance of 3-5 km for 1 km smoothing and more than 10 km for 5 km smoothing. The absolute accuracy of the measurements is estimated to be 15% based on uncertainties in the absorption cross-sections and their temperature dependence. Comparisons against two sets of balloon profiles and atmospheric trace molecules spectroscopy experiment (ATMOS) measurements show agreement within approximately 10% over the altitude range of 23 to 37 km at mid-latitudes. SAGE II NO2 measurements are calculated to be approximately 20% smaller at the mixing ratio peak than average limb infrared monitor of the stratosphere (LIMS) measurements in the tropics in 1979. They show acceptable agreement with SAGE I sunset NO2 measurements in the tropics in 1979-1981 when the limited resolution and precision of the SAGE I measurements and the differences between the two measurement techniques are considered. C1 UNIV TOKYO, GEOPHYS RES LAB, TOKYO 113, JAPAN. UNIV LILLE 1, F-59655 VILLENEUVE DASCQ, FRANCE. UNIV DENVER, DEPT PHYS, DENVER, CO 80208 USA. KOKUGAKUIN UNIV, TOKYO 150, JAPAN. INST AERON SPATIALE BELGIQUE, BRUSSELS, BELGIUM. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. CNRS, SERV AERON, F-91371 VERRIERES LE BUISSON, FRANCE. RP CUNNOLD, DM (reprint author), GEORGIA INST TECHNOL, SCH EARTH & ATMOSPHER SCI, ATLANTA, GA 30332 USA. RI IWAGAMI, NAOMOTO/G-4878-2014 NR 23 TC 40 Z9 40 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 JUL 20 PY 1991 VL 96 IS D7 BP 12913 EP 12925 DI 10.1029/91JD01344 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100006 ER PT J AU RUSCH, DW THOMAS, GE JENSEN, EJ AF RUSCH, DW THOMAS, GE JENSEN, EJ TI PARTICLE-SIZE DISTRIBUTIONS IN POLAR MESOSPHERIC CLOUDS DERIVED FROM SOLAR MESOSPHERE EXPLORER MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NOCTILUCENT CLOUDS; CLIMATOLOGY; SCATTERING AB Data from the visible and ultraviolet spectrometers on the Solar Mesosphere Explorer are used to derive the color ratios of the reflectance at 265, 296, and 393 nm of light scattered from polar mesospheric cloud particles. This analysis extends the spectral coverage into the visible region of the spectrum. The data reduction technique compared the cloud brightness to the brightness scattered from the background atmosphere at the same wavelength. The ratios determined in this way are independent of systematic errors in instrument radiometric calibration. The data are analyzed using theoretical determinations of the color ratios from the Mie theory of small particle scattering, assuming a lognormal distribution for the particle size dispersion. By "size" we mean the average radius of the sphere having the same ice volume. The present results confirm earlier findings that the effective sizes of polar mesospheric cloud particles are less than 70 nm. Still, there exists a small number of measurements which result in particle sizes of the order of 80 nm. Even for these large particle sizes the required vertical column content of water vapor does not exceed limits imposed by the available atmospheric water vapor concentrations. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP RUSCH, DW (reprint author), UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, BOULDER, CO 80309 USA. NR 25 TC 40 Z9 40 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 JUL 20 PY 1991 VL 96 IS D7 BP 12933 EP 12939 DI 10.1029/91JD01227 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100008 ER PT J AU DEMOULIN, P FARMER, CB RINSLAND, CP ZANDER, R AF DEMOULIN, P FARMER, CB RINSLAND, CP ZANDER, R TI DETERMINATION OF ABSOLUTE STRENGTHS OF N-2 QUADRUPOLE LINES FROM HIGH-RESOLUTION GROUND-BASED IR SOLAR OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SPECTRUM AB High-resolution, high signal-to-noise ratio, solar absorption spectra recorded with a Fourier transform spectrometer at the International Scientific Station of the Jungfraujoch, Switzerland, have been analyzed to determine the strengths of several lines belonging to the S branch of the N2 (1-0) electric quadrupole vibration-rotation band centered at 2329.9168 cm-1. The method which was applied here was based on equivalent width measurements of lines observed over a broad range of air masses; extrapolation of these measurements to zero air mass gave the line strengths for the transitions S7 to S10, independent of half widths, an ambiguity unavoidable with the use of curve-fitting techniques. The resulting absolute accuracies of the line strengths derived here, estimated to be better than +/- 2.5% for S8, +/- 2.6% for S10, +/- 3.4% for S9, and +/- 5.1% for S7, are due largely to the high quality and quantity of the spectra retained in this analysis and the accuracy with which the observation conditions are known. An important application of the improved values for these N2 transitions, which have low initial ground state energies, is the direct determination of the line-of-sight atmospheric air masses associated with remotely sensed infrared spectroscopic observations. Positions of the N2 transitions studied here have further been redetermined with an absolute accuracy better than 0.0002 cm-1. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP DEMOULIN, P (reprint author), UNIV LIEGE, INST ASTROPHYS, 5 AVE COINTE, B-4000 LIEGE COINTE, BELGIUM. NR 17 TC 11 Z9 11 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 JUL 20 PY 1991 VL 96 IS D7 BP 13003 EP 13008 DI 10.1029/91JD01029 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100012 ER PT J AU FUNG, I JOHN, J LERNER, J MATTHEWS, E PRATHER, M STEELE, LP FRASER, PJ AF FUNG, I JOHN, J LERNER, J MATTHEWS, E PRATHER, M STEELE, LP FRASER, PJ TI 3-DIMENSIONAL MODEL SYNTHESIS OF THE GLOBAL METHANE CYCLE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC CARBON-MONOXIDE; GENERAL-CIRCULATION MODEL; TROPOSPHERIC METHANE; SOUTHERN-HEMISPHERE; SPECTROSCOPIC MEASUREMENTS; ISOTOPIC COMPOSITION; SEASONAL CYCLES; BOUNDARY-LAYER; RICE PADDIES; TRACER MODEL AB The geographic and seasonal emission distributions of the major sources and sinks of atmospheric methane were compiled using methane flux measurements and energy and agricultural statistics in conjunction with global digital data bases of land surface characteristics and anthropogenic activities. Chemical destruction of methane in the atmosphere was calculated using three-dimensional OH fields every 5 days taken from Spivakovsky et al. (1990a, b). The signatures of each of the sources and sinks in the atmosphere were simulated using a global three-dimensional tracer transport model. Candidate methane budget scenarios were constructed according to mass balance of methane and its carbon isotopes. The verisimilitude of the scenarios was tested by their ability to reproduce the meridional gradient and seasonal variations of methane observed in the atmosphere. Constraints imposed by all the atmospheric observations are satisfied simultaneously by several budget scenarios. A preferred budget comprises annual destruction rates of 450 Tg by OH oxidation and 10 Tg by soil absorption and annual emissions of 80 Tg from fossil sources, 80 Tg from domestic animals, and 35 Tg from wetlands and tundra poleward of 50-degrees-N. Emissions from landfills, tropical swamps, rice fields, biomass burning, and termites total 295 Tg; however, the individual contributions of these terms cannot be determined uniquely because of the lack of measurements of direct fluxes and of atmospheric methane variations in regions where these sources are concentrated. C1 STX CORP, NEW YORK, NY 10025 USA. CSIRO, DIV ATMOSPHER RES, MORDIALLOC, VIC 3195, AUSTRALIA. COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10027 USA. RP NASA, INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Steele, Paul/B-3185-2009; Fraser, Paul/D-1755-2012; John, Jasmin/F-8194-2012 OI Steele, Paul/0000-0002-8234-3730; John, Jasmin/0000-0003-2696-277X NR 153 TC 538 Z9 559 U1 6 U2 110 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 JUL 20 PY 1991 VL 96 IS D7 BP 13033 EP 13065 DI 10.1029/91JD01247 PG 33 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100015 ER PT J AU WHITING, GJ CHANTON, JP BARTLETT, DS HAPPELL, JD AF WHITING, GJ CHANTON, JP BARTLETT, DS HAPPELL, JD TI RELATIONSHIPS BETWEEN CH4 EMISSION, BIOMASS, AND CO2 EXCHANGE IN A SUBTROPICAL GRASSLAND SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID METHANE EMISSIONS; RICE PADDIES; GAS-TRANSPORT; TROPOSPHERIC METHANE; SEASONAL-VARIATION; AQUATIC PLANTS; FRESH-WATER; FLUX; SEDIMENTS; FLOODPLAIN AB Methane flux was linearly correlated with plant biomass (r = 0.97, n = 6 and r = 0.95, n = 8) at two locations in a Florida Everglades Cladium marsh. One location, which had bumed 4 months previously, exhibited a greater increase in methane flux as a function of biomass relative to sites at an unbumed location. However, methane flux data from both sites fit a single regression (r = 0.94, n = 14) when plotted against net CO2 exchange suggesting that either methanogenesis in Everglades marl sediments is fueled by belowground root exudation or else factors which enhance photosynthetic production and plant growth are also correlated with methane production and flux in this oligotrophic environment. These data are the first to show a direct relationship between spatial variability in plant biomass, net ecosystem production, and methane emission in a natural wetland. C1 FLORIDA STATE UNIV, DEPT OCEANOG, TALLAHASSEE, FL 32306 USA. UNIV NEW HAMPSHIRE, INST STUDY EARTH OCEANS & SPACE, DURHAM, NH 03824 USA. RP WHITING, GJ (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 483, HAMPTON, VA 23665 USA. NR 59 TC 84 Z9 90 U1 0 U2 16 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 JUL 20 PY 1991 VL 96 IS D7 BP 13067 EP 13071 DI 10.1029/91JD01248 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100016 ER PT J AU RICHARDSON, JL FISHMAN, J GREGORY, GL AF RICHARDSON, JL FISHMAN, J GREGORY, GL TI OZONE BUDGET OVER THE AMAZON - REGIONAL EFFECTS FROM BIOMASS-BURNING EMISSIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-MONOXIDE; BOUNDARY-LAYER; DRY SEASON; TROPOSPHERIC OZONE; GTE CITE-1; BASIN; NO; FOREST; PHOTOCHEMISTRY; HYDROCARBONS AB A one-dimensional, time-dependent, photochemical model is used in conjunction with data obtained during the dry-season portion of NASA's Global Tropospheric Experiment and Brazil's Instituto Nacional de Pesquisas Espaciais (INPE) (National Institute for Space Research) Amazon Boundary Layer Experiment (ABLE 2A) to simulate the chemistry of the dry-season Amazon troposphere. The background atmosphere, unperturbed by the presence of emissions from biomass burning, is simulated with inputs of surface sources and deposition of various species measured during ABLE 2A. The presence of haze layers over a region is simulated by the imposition of profiles of species characteristic of haze within the model for 12 hours. The inclusion of hydrocarbons within the modeled haze is found to approximately double the calculated in situ ozone production rate. The difference between the calculated total column ozone production rates in the haze simulation and the background simulation is the model-predicted enhancement of the in situ ozone production due to regionally transported haze layers (up to 1000 km transport distance). The predicted enhancement of ozone is between 0.3 and 2.9 x 10(11) molecules O3 cm-2 s-1, near the range of observed rates of ozone increase over the Amazon Basin during the dry season. This suggests that the regional transport of haze during the southern tropical burning season is an important factor in explaining the increase of ozone observed annually during this period. RP RICHARDSON, JL (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL STOP 401A, MAIL CODE 401A, HAMPTON, VA 23665 USA. NR 54 TC 11 Z9 11 U1 0 U2 5 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 JUL 20 PY 1991 VL 96 IS D7 BP 13073 EP 13087 DI 10.1029/91JD00993 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100017 ER PT J AU THOMPSON, AM STEWART, RW AF THOMPSON, AM STEWART, RW TI EFFECT OF CHEMICAL-KINETICS UNCERTAINTIES ON CALCULATED CONSTITUENTS IN A TROPOSPHERIC PHOTOCHEMICAL MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID REACTION HO2+NO->OH+NO2; CHLORINE PERTURBATIONS; OZONE PRODUCTION; RATE-CONSTANT; SENSITIVITY; PROPAGATION; OH AB The imprecision of photochemical reaction rates as measured in the laboratory introduces significant uncertainty into trace species concentration calculated in a photochemical model. We have evaluated uncertainties in tropospheric concentrations calculated with a one-dimensional photochemical model, using a Monte Carlo technique to introduce random uncertainty into the model rate coefficients. Correlations between rate coefficients and species and between species and species have been determined to answer the following questions. Which are the most critical kinetic processes in determining constituent distributions? Which are the strongest species-species correlations? The most critical reactions turn out to be the primary photodissociations of O3 and NO2, which initiate ozone destruction and formation, respectively. The reaction between OH and methane is critical, as is the rate of nitric acid formation, which removes both odd nitrogen (NO(x)) and odd hydrogen (HO(x)). Species-species correlations reveal anticorrelation between HO(x) and NO(x) and positive correlation between OH and peroxides, acids, and aldehydes. Particular attention is given to ozone and to the transient OH, which is difficult to measure and is therefore frequently calculated using photochemical models and observations of more stable trace gases. A set of Monte Carlo computations is performed for conditions simulating several distinct chemical environments because imprecision in computed species are nonlinear and depend strongly on mean chemical composition. For low NO(x), low hydrocarbon, low O3 levels, as in the remote troposphere, the 1-sigma imprecision in computed boundary layer OH may be as low as 20%, with that for HO2 at 15% and H2O2 at 25%. At higher NO(x) and O3 levels, the 1-sigma imprecision in boundary layer OH and HO2 is 70%, and H2O2 is 90%. The 1-sigma imprecision in computed O3 is approximately 15% (7-10 ppbv) in both cases. The implications of model computed OH imprecision for predictive and diagnostic calculations are explored. Averaging over the regionally differing results suggests that a typical estimate of global OH is approximately 25% uncertain due to kinetics imprecision. This limits the certainty with which lifetimes for numerous natural and anthropogenic trace gases can be calculated with a photochemical model. The imprecision in a given determination of computed OH can be cut to 20% or less with simultaneous high-precision measurements of O3, CO, CH4, and NO2. Several experimental strategies for optimizing the deduction of OH are described, including one based on measurement of the HO2 radical. RP THOMPSON, AM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, MAIL CODE 916, GREENBELT, MD 20771 USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 35 TC 93 Z9 93 U1 0 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 JUL 20 PY 1991 VL 96 IS D7 BP 13089 EP 13108 DI 10.1029/91JD01056 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FY191 UT WOS:A1991FY19100018 ER PT J AU TUCKER, CJ DREGNE, HE NEWCOMB, WW AF TUCKER, CJ DREGNE, HE NEWCOMB, WW TI EXPANSION AND CONTRACTION OF THE SAHARA DESERT FROM 1980 TO 1990 SO SCIENCE LA English DT Article ID CANOPY REFLECTANCE; SAHEL; PRODUCTIVITY; WHEAT AB Data from polar-orbiting meteorological satellites have been used to determine the extent of the Sahara Desert and to document its interannual variation from 1980 to 1990. The Sahara Desert ranged from 8,633,000 square kilometers in 1980 to 9,982,000 square kilometers in 1984. The greatest annual north-south latitudinal movement of the southern Saharan boundary was 110 kilometers from 1984 to 1985 and resulted in a decrease in desert area of 724,000 square kilometers. C1 TEXAS TECH UNIV,INT CTR ARID & SEMIARID LAND STUDIES,LUBBOCK,TX 79409. RP TUCKER, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 50 TC 369 Z9 415 U1 10 U2 45 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 19 PY 1991 VL 253 IS 5017 BP 299 EP 301 DI 10.1126/science.253.5017.299 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FX224 UT WOS:A1991FX22400034 PM 17794695 ER PT J AU POWELL, JA PETIT, JB EDGAR, JH JENKINS, IG MATUS, LG YANG, JW PIROUZ, P CHOYKE, WJ CLEMEN, L YOGANATHAN, M AF POWELL, JA PETIT, JB EDGAR, JH JENKINS, IG MATUS, LG YANG, JW PIROUZ, P CHOYKE, WJ CLEMEN, L YOGANATHAN, M TI CONTROLLED GROWTH OF 3C-SIC AND 6H-SIC FILMS ON LOW-TILT-ANGLE VICINAL (0001) 6H-SIC WAFERS SO APPLIED PHYSICS LETTERS LA English DT Article ID CHEMICAL VAPOR-DEPOSITION; THIN-FILMS AB We have found that, with proper pregrowth surface treatment, 6H-SiC single-crystal films can be grown by chemical vapor deposition (CVD) at 1450-degrees-C on vicinal (0001) 6H-SiC with tilt angles as small as 0.1-degrees. Previously, tilt angles of greater than 1.5-degrees were required to achieve 6H on 6H at this growth temperature. In addition, 3C-SiC could be induced to grow within selected regions on the 6H substrate. The 3C regions contained few (or zero) double-positioning boundaries and a low density of stacking faults. A new growth model is proposed to explain the control of SiC polytype in this epitaxial film growth process. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. RP POWELL, JA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 128 Z9 128 U1 5 U2 21 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 15 PY 1991 VL 59 IS 3 BP 333 EP 335 DI 10.1063/1.105587 PG 3 WC Physics, Applied SC Physics GA FW744 UT WOS:A1991FW74400028 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR ROSI, M AF BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR ROSI, M TI A THEORETICAL-STUDY OF THE LOW-LYING STATES OF TI2 AND ZR2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID TRANSITION-METAL ATOMS; GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; POSITIVE-IONS; ORBITALS; 1ST-ROW; ABINITIO; ENERGIES; CI(SD); DIMER AB The 1-SIGMA-g+, 3-DELTA-g, 3-SIGMA-u+, and 7-SIGMA-u+ states of Ti2 and Zr2 have been studied using a multireference configuration-interaction (MRCI) approach. Although our best calculation produces a 1-SIGMA-g+ ground state for Zr2, the 3-SIGMA-u+ and 3-DELTA-g states are found to be very low lying. Additional support for a 1-SIGMA-g+ ground state assignment comes from the fact that the resulting vertical excitation spectrum is consistent with the optical spectrum of Zr2 observed in noble gas matrices. For Ti2, it proved more difficult to make a definitive assignment of the ground state, because of the many low-lying states and the large effect of inner-shell (3s and 3p) correlation. With only valence correlation included, the ground state is predicted to be 7-SIGMA-u+ at both the MRCI and averaged coupled-pair functional (ACPF) levels of correlation treatment. However, inner-shell correlation effects, estimated based on modified coupled-pair functional (MCPF) and contracted configuration-interaction (CCI) calculations, preferentially lower the 1-SIGMA-g+ and 3-DELTA-g states, resulting in a 3-DELTA-g ground state and a very low-lying 1-SIGMA-g+ state. Since the 3-DELTA-g state lies below the 1-SIGMA-g+ state at all levels of correlation treatment and both states are derived from the same atomic asymptote, we prefer a 3-DELTA-g assignment for the ground state of Ti2. This is consistent with the failure to observe an electron-spin resonance (ESR) signal, but such an assignment requires an explanation for the absence of subcomponents on the lines observed in the resonance Raman spectrum of Ti2. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 30 TC 45 Z9 46 U1 0 U2 6 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 JUL 15 PY 1991 VL 95 IS 2 BP 1057 EP 1063 DI 10.1063/1.461133 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FV976 UT WOS:A1991FV97600040 ER PT J AU ONUCHIC, JN DEANDRADE, PCP BERATAN, DN AF ONUCHIC, JN DEANDRADE, PCP BERATAN, DN TI ELECTRON-TUNNELING PATHWAYS IN PROTEINS - A METHOD TO COMPUTE TUNNELING MATRIX-ELEMENTS IN VERY LARGE SYSTEMS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID REACTION DYNAMICS; MOLECULES; QUANTUM AB A tight-binding Hamiltonian and Dyson's equation method are described that allow the computation of the tunneling matrix elements between electron donor and acceptor sites in a protein. The method is exact and computationally tractable. The Green's function matrix elements of the bridge are computed using a strategy that builds up the bridge one orbital at a time, allowing inclusion of all orbitals on proposed tunneling pathways and elsewhere. The tunneling matrix element is determined directly from the bridge Green's function. A simple representation of a helical protein segment is used to illustrate the method and its ability to include contributions from high-order backscattering and multiple pathway interference in the donor-acceptor coupling. C1 UNIV SAO PAULO,INST FIS & QUIM,BR-13560 SAO CARLOS,SP,BRAZIL. CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91109. RP ONUCHIC, JN (reprint author), UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093, USA. RI Beratan, David/C-5098-2011 NR 43 TC 89 Z9 90 U1 0 U2 6 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 JUL 15 PY 1991 VL 95 IS 2 BP 1131 EP 1138 DI 10.1063/1.461142 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FV976 UT WOS:A1991FV97600049 ER PT J AU WRIGHT, RN KNIBLOE, JR NOEBE, RD AF WRIGHT, RN KNIBLOE, JR NOEBE, RD TI CONSOLIDATION OF NIAL POWDERS USING HOT ISOSTATIC PRESSING SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID DENSIFICATION; DIFFUSION; DIAGRAMS AB Consolidation of stoichiometric NiAl powder during hot isostatic pressing (HIP) and the rate controlling densification mechanisms were modeled through the development of HIP maps. Using the best available data for material behavior and diffusion characteristics from the literature and experiments, maps were developed which describe densification of monosized powders as a function of HIP time, temperature and pressure. There is good agreement between the final densities predicted from the model and those observed experimentally. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WRIGHT, RN (reprint author), EG&G IDAHO INC,IDAHO NATL ENGN LAB,IDAHO FALLS,ID 83415, USA. NR 20 TC 6 Z9 6 U1 1 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 JUL 15 PY 1991 VL 141 IS 1 BP 79 EP 83 DI 10.1016/0921-5093(91)90711-U PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA GC548 UT WOS:A1991GC54800010 ER PT J AU TEWARI, SN VIJAYAKUMAR, M LEE, JE CURRERI, PA AF TEWARI, SN VIJAYAKUMAR, M LEE, JE CURRERI, PA TI SOLUTAL PARTITION-COEFFICIENTS IN NICKEL-BASED SUPERALLOY PWA-1480 SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article AB Solutal profiles in dendritic single-crystal specimens of PWA-1480 nickel-base superalloy, which were directionally solidified and quenched, were examined on several transverse cross-sections to obtain the partition coefficients. Similar to their nickel-base binaries, the partition coefficients of tantalum, titanium, and aluminum were found to be less than unity; those of tungsten and cobalt were greater than unity. The partition coefficients were temperature independent in the range 1584-1608 K. The contribution of solid-state diffusion to microsegregation was observed to be negligible. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP TEWARI, SN (reprint author), CLEVELAND STATE UNIV,DEPT CHEM ENGN,CLEVELAND,OH 44115, USA. NR 10 TC 24 Z9 24 U1 0 U2 6 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 JUL 15 PY 1991 VL 141 IS 1 BP 97 EP 102 DI 10.1016/0921-5093(91)90713-W PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA GC548 UT WOS:A1991GC54800012 ER PT J AU NOEVER, DA AF NOEVER, DA TI STATISTICS OF PREMIXED FLAME CELLS SO PHYSICAL REVIEW A LA English DT Article ID DYNAMICS; ARRANGEMENT; MONOLAYERS; EVOLUTION; NETWORKS AB The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks-metal grains, soap foams, bioconvection, and Langmuir monolayers. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,ES-76,HUNTSVILLE,AL 35812, USA. NR 19 TC 8 Z9 8 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD JUL 15 PY 1991 VL 44 IS 2 BP 968 EP 974 DI 10.1103/PhysRevA.44.968 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA FY463 UT WOS:A1991FY46300024 ER PT J AU HUBERMAN, ML KSENDZOV, A LARSSON, A TERHUNE, R MASERJIAN, J AF HUBERMAN, ML KSENDZOV, A LARSSON, A TERHUNE, R MASERJIAN, J TI OPTICAL-ABSORPTION BY FREE HOLES IN HEAVILY DOPED GAAS SO PHYSICAL REVIEW B LA English DT Article AB Optical absorption in p-type GaAs with hole concentrations between 10(19) and 10(20) cm-3 has been measured for wavelengths between 2 and 20-mu-m and compared with results of theoretical calculations. In contrast to previous measurements at lower doping levels, the occupied hole states are far from the zone center, where the heavy- and light-hole bands become parallel. This gives rise to a large joint density of states for optical transitions. It is found that the overall magnitude of the observed absorption is explained correctly by the theory, with both free-carrier (indirect) and inter-valence-band (direct) transitions contributing significantly to the total absorption. The strength of the absorption (alpha almost-equal-to 20 000 cm -1 for N(A) = 5 X 10(19) cm-3) is attractive for long-wavelength infrared-detector applications. RP HUBERMAN, ML (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 11 TC 34 Z9 34 U1 1 U2 5 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUL 15 PY 1991 VL 44 IS 3 BP 1128 EP 1133 DI 10.1103/PhysRevB.44.1128 PG 6 WC Physics, Condensed Matter SC Physics GA FW105 UT WOS:A1991FW10500023 ER PT J AU FATHAUER, RW KSENDZOV, A IANNELLI, JM GEORGE, T AF FATHAUER, RW KSENDZOV, A IANNELLI, JM GEORGE, T TI CONTROLLABLE SURFACE-PLASMON RESONANCE IN ENGINEERED NANOMETER EPITAXIAL SILICIDE PARTICLES EMBEDDED IN SILICON SO PHYSICAL REVIEW B LA English DT Note ID MOLECULAR-BEAM EPITAXY; OPTICAL-PROPERTIES; INFRARED RESPONSE; COSI2; FILMS; SI(111); SILVER; MATRIX; SI AB Epitaxial CoSi2 particles in a single-crystal silicon matrix are grown by molecular-beam epitaxy using a technique that allows nanometer control over particle size in three dimensions. These composite layers exhibit resonant absorption predicted by effective-medium theory. Selection of the height and diameter of disklike particles through a choice of growth conditions allows tailoring of the depolarization factor and hence of the surface-plasmon resonance energy. Resonant absorption from 0.49 to 1.04 eV (2.5 to 1.2-mu-m) is demonstrated and shown to agree well with values predicted by the Garnett theory using the bulk dielectric constants for CoSi2 and Si. RP FATHAUER, RW (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 19 TC 8 Z9 8 U1 0 U2 3 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUL 15 PY 1991 VL 44 IS 3 BP 1345 EP 1348 DI 10.1103/PhysRevB.44.1345 PG 4 WC Physics, Condensed Matter SC Physics GA FW105 UT WOS:A1991FW10500052 ER PT J AU MANNHEIM, PD KAZANAS, D AF MANNHEIM, PD KAZANAS, D TI SOLUTIONS TO THE REISSNER-NORDSTROM, KERR, AND KERR-NEWMAN PROBLEMS IN 4TH-ORDER CONFORMAL WEYL GRAVITY SO PHYSICAL REVIEW D LA English DT Article AB We continue our study of the general structure of fourth-order conformal Weyl gravity which we are exploring as a possible theory of gravity, and in this paper we present three new exact solutions to the theory which we have found. First we present the complete and exact solution to the Reissner-Nordstrom problem associated with a static, spherically symmetric point electric and/or magnetic charge coupled to fourth-order conformal Weyl gravity. We find that, unlike the familiar second-order Einstein case where the modification to the Schwarzschild metric is in the form of a term which behaves like 1/r2, in the fourth-order case the modification is found to behave like 1/r, i.e., just like the Newtonian potential term itself. Additionally, we present two further exact solutions to the theory which we have found, namely, those associated with the fourth-order Kerr and Kerr-Newman problems in which a stationary, axially symmetric rotating system with or without electric and/or magnetic charge is coupled to gravity. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP MANNHEIM, PD (reprint author), UNIV CONNECTICUT,DEPT PHYS,STORRS,CT 06269, USA. NR 12 TC 42 Z9 42 U1 1 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUL 15 PY 1991 VL 44 IS 2 BP 417 EP 423 DI 10.1103/PhysRevD.44.417 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA FX272 UT WOS:A1991FX27200012 ER PT J AU SNYDER, EJ ANDERSON, MS TONG, WM WILLIAMS, RS ANZ, SJ ALVAREZ, MM RUBIN, Y DIEDERICH, FN WHETTEN, RL AF SNYDER, EJ ANDERSON, MS TONG, WM WILLIAMS, RS ANZ, SJ ALVAREZ, MM RUBIN, Y DIEDERICH, FN WHETTEN, RL TI ATOMIC FORCE MICROSCOPE STUDIES OF FULLERENE FILMS - HIGHLY STABLE C60 FCC(311) FREE SURFACES SO SCIENCE LA English DT Article ID CARBON; C-60 AB Atomic force microscopy and x-ray diffractometry were used to study 1500 angstrom-thick films of pure C60 grown by sublimation in ultrahigh vacuum onto a CaF2 (111) substrate. Topographs of the films did not reveal the expected close-packed structures, but they showed instead large regions that correspond to a face-centered cubic (311) surface and distortions of this surface. The open (311) structure may have a relatively low free energy because the low packing density contributes to a high entropy of the exposed surface. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV CALIF LOS ANGELES,CTR SOLID STATE SCI,LOS ANGELES,CA 90024. RP SNYDER, EJ (reprint author), UNIV CALIF LOS ANGELES,DEPT CHEM & BIOCHEM,LOS ANGELES,CA 90024, USA. RI Tong, William/D-2564-2010; Williams, R. Stanley/A-8281-2009 OI Williams, R. Stanley/0000-0003-0213-4259 NR 16 TC 56 Z9 57 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 JUL 12 PY 1991 VL 253 IS 5016 BP 171 EP 173 DI 10.1126/science.253.5016.171 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FW160 UT WOS:A1991FW16000028 PM 17779132 ER PT J AU KEYSER, LF MOORE, SB LEU, MT AF KEYSER, LF MOORE, SB LEU, MT TI SURFACE-REACTION AND PORE DIFFUSION IN FLOW-TUBE REACTORS SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID TORTUOSITY FACTOR; KINETICS; PHASE AB The interaction of gas diffusion with surface reaction in porous solids is discussed and applied specifically to heterogeneous rate measurements in flow-tube reactors. External diffusion to the outer surface of a reactive solid, internal diffusion within the pores, surface reaction, and laminar flow are considered. A procedure is developed to correct observed surface rate constants for the interaction of these processes. Measured surface areas and bulk densities are used to construct a semiempirical model for porous diffusion in vapor-formed HNO3-H2O ices which are used to simulate polar stratospheric cloud surfaces. The model is tested experimentally by varying the thickness of these ices from about 15 to 120-mu-m. The results are consistent with the model predictions and show that the HNO3-H2O ices used are highly porous, and the internal surface must be considered in calculating kinetic parameters from observed loss rates. The best fit of the data yields a tortuosity factor of 3.3 +/- 1.1 for the ice substrates. RP KEYSER, LF (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 31 TC 116 Z9 116 U1 2 U2 20 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 11 PY 1991 VL 95 IS 14 BP 5496 EP 5502 DI 10.1021/j100167a026 PG 7 WC Chemistry, Physical SC Chemistry GA FW477 UT WOS:A1991FW47700026 ER PT J AU JAUNCEY, DL REYNOLDS, JE TZIOUMIS, AK MUXLOW, TWB PERLEY, RA MURPHY, DW PRESTON, RA KING, EA PATNAIK, AR JONES, DL MEIER, DL BIRD, DJ BLAIR, DG BUNTON, JD CLAY, RW COSTA, ME DUNCAN, RA FERRIS, RH GOUGH, RG HAMILTON, PA HOARD, DW KEMBALL, A KESTEVEN, MJ LOBDELL, ET LUITEN, AN MCCULLOCH, PM MURRAY, JD NICOLSON, GD RAO, AP SAVAGE, A SINCLAIR, MW SKJERVE, L TAAFFE, L WARK, RM WHITE, GL AF JAUNCEY, DL REYNOLDS, JE TZIOUMIS, AK MUXLOW, TWB PERLEY, RA MURPHY, DW PRESTON, RA KING, EA PATNAIK, AR JONES, DL MEIER, DL BIRD, DJ BLAIR, DG BUNTON, JD CLAY, RW COSTA, ME DUNCAN, RA FERRIS, RH GOUGH, RG HAMILTON, PA HOARD, DW KEMBALL, A KESTEVEN, MJ LOBDELL, ET LUITEN, AN MCCULLOCH, PM MURRAY, JD NICOLSON, GD RAO, AP SAVAGE, A SINCLAIR, MW SKJERVE, L TAAFFE, L WARK, RM WHITE, GL TI AN UNUSUALLY STRONG EINSTEIN RING IN THE RADIO-SOURCE PKS1830-211 SO NATURE LA English DT Article AB RADIO observations of the strong, flat-spectrum radio source PKS1830-211 revealed a double structure, with a separation of 1 arcsec, suggesting that it might be a gravitationally lensed object 1. We have now obtained high-resolution radio images of PKS1830-211 from several interferometric radiotelescope networks, which show an unusual elliptical ring-like structure connecting the two brighter components. The presence of the ring, and the similarity of the two brighter spots, argue strongly that this is indeed a gravitationally lensed system, specifically an Einstein ring in which lens and lensed object are closely aligned. Although the source is close to the galactic plane, it seems that both the lens and background (lensed) object are extragalactic. This object is one hundred times brighter than either of the two previously discovered radio Einstein rings, and is among the six brightest flat-spectrum sources in the sky. Its brightness makes it a peculiar object: it must involve either a chance alignment of a lensing object with an unusually bright background source, or an alignment with a less bright object but amplified to an unusual degree. C1 MT STROMLO & SIDING SPRING OBSERV,CANBERRA,ACT 2611,AUSTRALIA. NUFFIELD RADIO ASTRON LAB,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. UNIV WESTERN AUSTRALIA,DEPT PHYS,NEDLANDS,WA 6009,AUSTRALIA. HARTEBEESTHOEK RADIO ASTRON OBSERV,JOHANNESBURG,SOUTH AFRICA. TATA INST FUNDAMENTAL RES,CTR RADIO ASTRON,UDHAGAMANDALAM 643001,INDIA. ANGLO AUSTRALIAN OBSERV,UK SCHMIDT TELESCOPE UNIT,COONABARABRAN,NSW 2857,AUSTRALIA. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV ADELAIDE,DEPT PHYS,ADELAIDE,SA 5001,AUSTRALIA. CSIRO,DIV RADIOPHYS,EPPING,NSW 2121,AUSTRALIA. RP JAUNCEY, DL (reprint author), CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. RI Bunton, John/A-4944-2008; Luiten, Andre/G-5737-2011; King, Edward/A-1473-2012; OI Luiten, Andre/0000-0001-5284-7244; King, Edward/0000-0002-6898-2130; Muxlow, Thomas/0000-0001-5797-8796 NR 17 TC 90 Z9 90 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUL 11 PY 1991 VL 352 IS 6331 BP 132 EP 134 DI 10.1038/352132a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FW097 UT WOS:A1991FW09700046 ER PT J AU BURTON, MG MINCHIN, NR HOUGH, JH ASPIN, C AXON, DJ BAILEY, JA AF BURTON, MG MINCHIN, NR HOUGH, JH ASPIN, C AXON, DJ BAILEY, JA TI MOLECULAR-HYDROGEN POLARIZATION IMAGES OF OMC-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, GRAINS; INTERSTELLAR, MAGNETIC FIELDS; INTERSTELLAR, MOLECULES; NEBULAE, ORION NEBULA; POLARIZATION ID ORION-NEBULA; STAR FORMATION; SUBMILLIMETER POLARIZATION; INFRARED POLARIZATION; IMAGING POLARIMETRY; REFLECTION NEBULA; DISKS; OBJECTS; CLOUDS; WINDS AB A polarization image, with 0."6 pixel scale, of the molecular hydrogen v = 1-0 S(1) line at 2.1218-mu-m in the core of the OMC-1, is presented. The line emission is highly clumped, with a prominent filamentary structure protruding to the NW, away from the source of the outflow. There are two main characteristics of the line polarization: a region of aligned vectors over the molecular outflow region of the source, and parallel to the outflow axis, surrounded by a centrosymmetric pattern of vectors, centered on the region of peak molecular hydrogen line emission ("peak 1"), characteristic of scattering. The outflow is thus surrounded by a molecular hydrogen reflection nebula. The aligned vectors arise from the passage of the line photons through a medium of aligned grains between us and the outflow, and the polarization vectors trace the magnetic field direction over the outflow region in the core of the cloud. The mean field direction in the core is parallel to the large-scale field direction as derived from far-IR continuum measurements (e.g., Hildebrand et al.). The filament to the NW is dichroically polarized, indicating that the line emission is intrinsic to it, and not simply arising from increased scattering. Near IRc2 there is a significant twist in the aligned vectors, with the magnetic field direction changing close to the source of the outflow. From measurements of the ratio of the 1-0 S(1) line at 2.12-mu-m and the 1-0 Q-branch at 2.4-mu-m in the reflection nebula, we conclude that the grain size there is typical of the diffuse interstellar medium. In contrast, the grains in the cloud core are larger (e.g., Minchin et al.), and thus it appears that the grain size decreases with distance from the cloud core. C1 JOINT ASTRON CTR,HILO,HI 96720. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV CALIF IRVINE,DEPT PHYS,IRVINE,CA 92717. HATFIELD POLYTECH,DIV PHYS SCI,HATFIELD AL10 9AB,HERTS,ENGLAND. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. OI Burton, Michael/0000-0001-7289-1998 NR 33 TC 17 Z9 17 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 JUL 10 PY 1991 VL 375 IS 2 BP 611 EP 617 DI 10.1086/170223 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV411 UT WOS:A1991FV41100021 ER PT J AU SCHOELKOPF, RJ KELLEY, RL AF SCHOELKOPF, RJ KELLEY, RL TI DETECTION OF COHERENT 7.6 HZ OSCILLATIONS DURING A BURST FROM AQUILA X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (AQL X-1); STARS, PULSATION; X-RAYS, BINARIES; X-RAY, BURSTS ID X-RAY SOURCES; QUASI-PERIODIC OSCILLATIONS; NEUTRON STARS; RAPID BURSTER; DISCOVERY; EMISSION; BINARIES AB We report the results of timing and spectral analysis of the X-ray source Aql X-1 (X1908 + 005) using data obtained with the Einstein SSS and MPC instruments. A classic type I burst was observed from Aql X-1 in both detectors, and a coherent modulation with a period of 131.66 +/- 0.02 ms (7.6 Hz) and a pulsed fraction of 10% was detected in the SSS data (0.64-4.5 keV) during the period of enhanced emission. The signal has a random occurrence probability of less than 5 x 10(-5). The sensitivity of the MPC for high-resolution timing during the burst is greatly reduced because of the low-duty cycle (< 10%) during the burst, and the modulation is not detected. There is no evidence for a loss of coherence during the approximately 80 s when it is observable, giving f/DELTA-f > 600. The 2 sigma upper limit on the rate of change of the pulse period is 5 x 10(-5) s/s-1. We argue that an asymmetrical burst occurring on a neutron star rotating at 7.6 Hz offers a plausible explanation for the oscillation. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP SCHOELKOPF, RJ (reprint author), CALTECH,DEPT PHYS,PASADENA,CA 91125, USA. RI Schoelkopf, Robert/J-8178-2012; Kelley, Richard/K-4474-2012 NR 25 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 JUL 10 PY 1991 VL 375 IS 2 BP 696 EP 700 DI 10.1086/170234 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV411 UT WOS:A1991FV41100032 ER PT J AU HOLBERG, JB ALI, B CARONE, TE POLIDAN, RS AF HOLBERG, JB ALI, B CARONE, TE POLIDAN, RS TI ABSOLUTE FAR-ULTRAVIOLET SPECTROPHOTOMETRY OF HOT SUBLUMINOUS STARS FROM VOYAGER SO ASTROPHYSICAL JOURNAL LA English DT Article DE SPECTROPHOTOMETRY; STARS, INDIVIDUAL (BD +28-DEGREES-4211, G191-B2B); ULTRAVIOLET, SPECTRA ID SPECTRAL ENERGY-DISTRIBUTIONS; HUBBLE SPACE TELESCOPE; WHITE-DWARFS; EFFECTIVE TEMPERATURES; MODEL ATMOSPHERES; O-STAR; CALIBRATION; FLUX; IUE; STANDARDS AB We present observations, obtained with the Voyager ultraviolet spectrometers, of absolute fluxes for two well-known hot subluminous stars: BD + 28-degrees-4211, an sdO, G191-B2B, a hot DA white dwarf. Voyager far-UV fluxes from 912 to 1200 angstrom are combined with absolute spectrophotometry at longer wavelengths to produce complete absolute energy distributions for these two stars, from the Lyman limit at 912 angstrom to 1-mu-m. For BD + 28-degrees-4211, a single power law closely represents the entire observed energy distribution. For G191-B2B, a pure hydrogen model atmosphere provides an excellent match to the entire absolute energy distribution. Hot subluminous stars, such as those discussed here, have numerous advantages as absolute flux standards. We discuss Voyager absolute fluxes in relation to those reported from various sounding rocket experiments, including a recent rocket observation of BD + 28-degrees-4211. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SPACE PHYS LAB,GREENBELT,MD 20771. RP HOLBERG, JB (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB W,TUCSON,AZ 85721, USA. NR 43 TC 36 Z9 36 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 JUL 10 PY 1991 VL 375 IS 2 BP 716 EP 721 DI 10.1086/170237 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV411 UT WOS:A1991FV41100035 ER PT J AU RUDEN, SP POLLACK, JB AF RUDEN, SP POLLACK, JB TI THE DYNAMIC EVOLUTION OF THE PROTOSOLAR NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; PLANETS, FORMATION; SOLAR SYSTEM, GENERAL; STARS, FORMATION ID T-TAURI STARS; PRIMORDIAL SOLAR NEBULA; ECCENTRIC GRAVITATIONAL INSTABILITIES; ACCRETION DISKS; TURBULENT CONVECTION; INFRARED-SPECTRA; VISCOUS DISKS; MASS; PROTOSTARS; GRAINS AB We calculate the global evolution of prostostellar nebulae for a variety of initial disk masses and angular momenta. Although we approximate the viscous stress by an "alpha" model, we calibrate the constant alpha in terms of the properties of turbulent thermal convection. As the evolution proceeds, the nebula viscously spreads and is partially accreted by the protostar. The consequent decrease of the surface density renders portions of the disk optically thin in the vertical direction. When the Rosseland mean optical depth decreases below a critical value of order unity, we assume that the disk is unable locally to sustain thermal convection and that the turbulent viscosity and energy dissipation cease. We further assume that once convection subsides, no other sources of turbulent stress take its place. We calculate the resulting disk evolutionary properties under these assumptions and make comparisons with the solar system. We find that (1) moderately viscous disks with alpha almost-equal-to 10(-2) evolve to marginally (Rosseland) optically thin conditions in approximately 6 x 10(5) yr; (2) the resulting disk radii are primarily sensitive to the initial nebular angular momentum and insensitive to the intial disk mass; (3) significant amounts of mass (approximately 0.1 M.) can remain behind in a nonturbulent disk if the initial disk angular momentum is high; and (4) the heating of the disk surface inside r less-than-or-similar-to 1 AU by protosolar illumination can halt thermal convection after approximately 5 x 10(5) yr. We speculate that the termination of convective turbulent viscosity in the outer solar system marks the inception of the giant planet-building epoch by allowing grains to coagulate and sediment to the nebular midplane. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP RUDEN, SP (reprint author), UNIV CALIF IRVINE,DEPT PHYS,IRVINE,CA 92717, USA. NR 57 TC 186 Z9 186 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 JUL 10 PY 1991 VL 375 IS 2 BP 740 EP 760 DI 10.1086/170239 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV411 UT WOS:A1991FV41100037 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW AF LANGHOFF, SR BAUSCHLICHER, CW TI THEORETICAL-STUDY OF THE SPECTROSCOPY OF FEH+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE MOLECULAR PROCESSES ID TRANSITION-METAL HYDRIDES; BOND-ENERGIES; 1ST-ROW; CAH+; FE+ AB High-level theoretical calculations are presented for selected triplet, quintet, and septet states of FeH+. The ordering of the quintet states arising from the 6D ground of Fe+ is definitively determined to be X5-DELTA, A 5-PI, and B5-SIGMA+, which is consistent with Hund's rules and mixing arguments. The A5-PI-X5-DELTA separation is approximately 600 cm-1, whereas the lowest triplet state (a3-SIGMA-) lies approximately 10,000 cm-1 above the ground state. The dissociation energy of FeH+ is determined to be 2.29 eV (52.8 kcal mole-1), in good agreement with previous theoretical studies and experiments The excited quintet states of Fe+ are repulsive in the Franck-Condon region of the X5 DELTA-state. Thus FeH+ is probably photodissociated in stellar atmospheres, which may explain why it has not been observed, despite having a high predicted abundance based on thermodynamic arguments. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 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 JUL 10 PY 1991 VL 375 IS 2 BP 843 EP 845 DI 10.1086/170248 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV411 UT WOS:A1991FV41100046 ER PT J AU ADAMS, JH GARCIAMUNOZ, M GRIGOROV, NL KLECKER, B KONDRATYEVA, MA MASON, GM MCGUIRE, RE MEWALDT, RA PANASYUK, MI TRETYAKOVA, CA TYLKA, AJ ZHURAVLEV, DA AF ADAMS, JH GARCIAMUNOZ, M GRIGOROV, NL KLECKER, B KONDRATYEVA, MA MASON, GM MCGUIRE, RE MEWALDT, RA PANASYUK, MI TRETYAKOVA, CA TYLKA, AJ ZHURAVLEV, DA TI THE CHARGE STATE OF THE ANOMALOUS COMPONENT OF COSMIC-RAYS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS ABUNDANCES; COSMIC RAYS GENERAL ID SOLAR ENERGETIC PARTICLES; OXYGEN AB The ionic charge state of anomalous cosmic-ray oxygen has been determined by comparing measurements obtained inside the magnetosphere on a series of Cosmos satellite flights with simultaneous observations outside the magnetosphere from IMP 8 and ICE. We find a mean charge state of 0.9(-0.2)+0.3 for approximately 10 MeV nucleon-1 anomalous oxygen, consistent with the model of Fisk, Kozlovsky, & Ramaty, in which the anomalous cosmic rays originate from the neutral component of the local interstellar medium. This same approach gives results consistent with a mean charge state of +7 for solar energetic oxygen ions. C1 USN,RES LAB,UNIV SPACE RES ASSOC,WASHINGTON,DC 20375. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. MV LOMONOSOV STATE UNIV,NUCL PHYS RES INST,MOSCOW 119899,USSR. MAX PLANCK INST PHYS & ASTROPHYS,INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CALTECH,DOWNS LAB 220-47,PASADENA,CA 91125. RP ADAMS, JH (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,CODE 4154,WASHINGTON,DC 20375, USA. RI Panasyuk, Mikhail/E-2005-2012; Tylka, Allan/G-9592-2014 NR 26 TC 53 Z9 53 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 JUL 10 PY 1991 VL 375 IS 2 BP L45 EP L48 DI 10.1086/186084 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV416 UT WOS:A1991FV41600002 ER PT J AU KRISHER, TP ANDERSON, JD MORABITO, DD ASMAR, SW BORUTZKI, SE DELITSKY, ML DENSMORE, AC ESHE, PM LEWIS, GD MAURER, MJ ROTH, DC SON, YH SPILKER, TR SWEETNAM, DN TAYLOR, AH TYLER, GL GRESH, DL ROSEN, PA AF KRISHER, TP ANDERSON, JD MORABITO, DD ASMAR, SW BORUTZKI, SE DELITSKY, ML DENSMORE, AC ESHE, PM LEWIS, GD MAURER, MJ ROTH, DC SON, YH SPILKER, TR SWEETNAM, DN TAYLOR, AH TYLER, GL GRESH, DL ROSEN, PA TI RADIO RANGE MEASUREMENTS OF CORONAL ELECTRON-DENSITIES AT 13-CENTIMETER AND 3.6-CENTIMETER WAVELENGTHS DURING THE 1988 SOLAR CONJUNCTION OF VOYAGER-2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERPLANETARY MEDIUM; RADAR ASTRONOMY; SUN CORONA; SUN SOLAR WIND AB We report on radio range measurements of total solar plasma delay obtained during the solar conjunction of the Voyager 2 spacecraft in 1988 December, which occurred near solar maximum activity in the 11 yr cycle. The radio range measurements were generated by the Deep Space Network (DSN) at two wavelengths on the downlink from the spacecraft: 3.6 and 13 cm. A direct measurement of the integrated electron density along the ray path between the Earth stations and the spacecraft was obtained by differencing the range at the two wavelengths. Coronal electron density profiles have been derived during ingress and egress of the ray path, which approached the Sun to within 5 R.. At 10 R., the derived density profiles yield 34079 +/- 611 cm-3 on ingress and 49688 +/- 983 cM-3 on egress. These density levels are significantly higher than observed near previous solar maxima. C1 STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305. RP KRISHER, TP (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 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 JUL 10 PY 1991 VL 375 IS 2 BP L57 EP L60 DI 10.1086/186087 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV416 UT WOS:A1991FV41600005 ER PT J AU HENDRICKS, JD PLESCIA, JB AF HENDRICKS, JD PLESCIA, JB TI A REVIEW OF THE REGIONAL GEOPHYSICS OF THE ARIZONA TRANSITION ZONE SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID WESTERN UNITED-STATES; METAMORPHIC CORE COMPLEXES; COLORADO PLATEAU; SEISMIC REFRACTION; CRUSTAL STRUCTURE; SOUTHEASTERN CALIFORNIA; NORTH-AMERICA; GREAT BASIN; HEAT-FLOW; RANGE AB A review of existing geophysical information and new data presented in this special section indicate that major changes in crustal properties between the Basin and Range and Colorado Plateau occur in, or directly adjacent to, the region defined as the Arizona Transition Zone. Although this region was designated on a physiographic basis, studies indicate that it is also the geophysical transition between adjoining provinces. The Transition Zone displays anomalous crustal and upper mantle seismic properties, shallow Curie isotherms, high heat flow, and steep down-to-the-plateau Bouguer gravity gradients. Seismic and gravity studies suggest that the change in crustal thickness, from thin crust in the Basin and Range to thick crust in the Colorado Plateau, may occur as a series of steps rather than a planar surface. Anomalous P wave velocities, high heat flow, shallow Curie isotherms, and results of gravity modeling suggest that the upper mantle is heterogeneous in this region. A relatively shallow asthenosphere beneath the Basin and Range and Transition Zone contrasted with a thick lithosphere beneath the Colorado Plateau would be one explanation that would satisfy these geophysical observations. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP HENDRICKS, JD (reprint author), US GEOL SURVEY,2255 N GEMINI DR,FLAGSTAFF,AZ 86001, USA. RI Plescia, Jeffrey/B-7738-2016 NR 112 TC 16 Z9 16 U1 1 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOLID PD JUL 10 PY 1991 VL 96 IS B7 BP 12351 EP 12373 DI 10.1029/90JB01781 PG 23 WC Geosciences, Multidisciplinary SC Geology GA FW819 UT WOS:A1991FW81900044 ER PT J AU BERATAN, KK AF BERATAN, KK TI MIOCENE SYNEXTENSION SEDIMENTATION PATTERNS, WHIPPLE MOUNTAINS, SOUTHEASTERN CALIFORNIA - IMPLICATIONS FOR THE GEOMETRY OF THE WHIPPLE DETACHMENT SYSTEM SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID PEACH SPRINGS TUFF; RIVER EXTENSIONAL CORRIDOR; METAMORPHIC CORE COMPLEXES; WESTERN ARIZONA; EVOLUTION; BASIN; RIFT; STRATA AB A sedimentary basin formed in the southern and eastern Whipple Mountains during early to middle Miocene detachment faulting. Stratigraphic relations and facies patterns indicate that the shape and size of the sedimentary basin was controlled both by fault activity and by sedimentary processes. High-angle normal faults formed the southwestern, and perhaps also the northeastern boundary of the half graben, whereas a transfer fault probably formed the southeastern boundary. The transfer fault influenced the earliest synextension sedimentation in the basin. The location of this fault and similar faults in the Mohave Mountains and Aubrey Hills of Arizona is inferred to have been controlled by the position of primary irregularities or corrugations of the detachment fault. Shifts in facies patterns, particularly a shift in the position of the basin depocenter, reflect changes in basin geometry. Comparison with adjacent areas is necessary to distinguish between tectonic and nontectonic causes. A shift in depocentral position parallel to regional transport direction in the Whipple Mountains basin is interpreted as resulting from a change in the location of the high-angle normal fault forming the southwestern margin of the basin, whereas a shift perpendicular to transport direction probably resulted from overtopping of topographic barriers within a fault block. The most active phase of faulting occurred prior to deposition of stratigraphic units younger than the 18.5 Ma Peach Springs Tuff. Relative uplift of the core of the Whipple Mountains, probably as a result of isostatic rebound following tectonic denudation, influenced sedimentation patterns after deposition of the Peach Springs Tuff. RP BERATAN, KK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 47 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-SOLID PD JUL 10 PY 1991 VL 96 IS B7 BP 12425 EP 12442 DI 10.1029/91JB00596 PG 18 WC Geosciences, Multidisciplinary SC Geology GA FW819 UT WOS:A1991FW81900048 ER PT J AU POWELL, JA PETIT, JB EDGAR, JH JENKINS, IG MATUS, LG CHOYKE, WJ CLEMEN, L YOGANATHAN, M YANG, JW PIROUZ, P AF POWELL, JA PETIT, JB EDGAR, JH JENKINS, IG MATUS, LG CHOYKE, WJ CLEMEN, L YOGANATHAN, M YANG, JW PIROUZ, P TI APPLICATION OF OXIDATION TO THE STRUCTURAL CHARACTERIZATION OF SIC EPITAXIAL-FILMS SO APPLIED PHYSICS LETTERS LA English DT Article ID CHEMICAL VAPOR-DEPOSITION; THIN-FILMS; GROWTH; TEMPERATURE AB Both 3C-SiC and 6H-SiC single-crystal films can be grown on vicinal (0001) 6H-SiC wafers. We have found that oxidation can be a powerful diagnostic process for (1) "color mapping" the 3C and 6H regions of these films, (2) decorating stacking faults in the films, (3) enhancing the decoration of double positioning boundaries, and (4) decorating polishing damage. Contrary to previously published oxidation results, proper oxidation conditions can yield interference colors that provide a definitive map of the polytype distribution for both the Si face and C face of SiC films. Defects were more effectively decorated by oxidation on the Si face than on the C face. C1 UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. CASE WESTERN RESERVE UNIV, DEPT MAT SCI & ENGN, CLEVELAND, OH 44106 USA. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 13 TC 51 Z9 51 U1 0 U2 7 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0003-6951 EI 1077-3118 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 8 PY 1991 VL 59 IS 2 BP 183 EP 185 DI 10.1063/1.105960 PG 3 WC Physics, Applied SC Physics GA FV763 UT WOS:A1991FV76300016 ER PT J AU MANION, SJ BELL, LD KAISER, WJ MAKER, PD MULLER, RE AF MANION, SJ BELL, LD KAISER, WJ MAKER, PD MULLER, RE TI LATERAL TUNNELING THROUGH VOLTAGE-CONTROLLED BARRIERS SO APPLIED PHYSICS LETTERS LA English DT Article ID DIMENSIONAL ELECTRON-GAS; BALLISTIC TRANSPORT; HETEROSTRUCTURES; EMISSION; SYSTEMS AB We report on a detailed experimental investigation of lateral tunneling between electrodes of a two-dimensional electron gas separated by the voltage-controlled barrier of a nanometer Schottky gate. The experimental data are modeled using the WKB method to calculate the tunneling probability of electrons through a barrier whose shape is determined from a solution of the two-dimensional Poisson equation. This model is in excellent agreement with the experimental data over a two order of magnitude range of current. RP MANION, SJ (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 10 TC 9 Z9 9 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 8 PY 1991 VL 59 IS 2 BP 213 EP 215 DI 10.1063/1.105969 PG 3 WC Physics, Applied SC Physics GA FV763 UT WOS:A1991FV76300026 ER PT J AU GLOERSEN, P CAMPBELL, WJ AF GLOERSEN, P CAMPBELL, WJ TI RECENT VARIATIONS IN ARCTIC AND ANTARCTIC SEA-ICE COVERS SO NATURE LA English DT Article ID CARBON-DIOXIDE; TEMPERATURE; VARIABILITY AB Variations in the extents of sea-ice cover at the poles and the areas of open water enclosed within them were observed every other day during the interval 1978-1987 by a satellite-borne scanning multispectral microwave radiometer. A band-limited regression technique shows that the trends in coverage of the Arctic and Antarctic sea-ice packs are not the same. During these nine years, there are significant decreases in ice extent and open-water areas within the ice cover in the Arctic, whereas in the Antarctic, there are no significant trends. C1 UNIV PUGET SOUND,US GEOL SURVEY,ICE & CLIMATE PROJECT,TACOMA,WA 98416. RP GLOERSEN, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,CODE 971,GREENBELT,MD 20771, USA. NR 23 TC 107 Z9 108 U1 2 U2 6 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD JUL 4 PY 1991 VL 352 IS 6330 BP 33 EP 36 DI 10.1038/352033a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FV178 UT WOS:A1991FV17800060 ER PT J AU NORUM, TD AF NORUM, TD TI SUPERSONIC RECTANGULAR JET IMPINGEMENT NOISE EXPERIMENTS SO AIAA JOURNAL LA English DT Article AB The discrete frequency sound produced by jets issuing from a convergent, rectangular nozzle of aspect ratio 4.24 was investigated. Experiments were performed both with the free jet and with the jet impinging on a hard ground surface. Fully expanded Mach numbers to 1.95 were attained. Measurements of both shock cell length and screech wavelength of the free jet show excellent agreement with theory. The impingement tones that dominate the impinging jet spectra show a definite staging behavior that appears to be biased toward the free jet screech frequency once the separation distance exceeds the region of substantial shock cell development. The frequency variation of the impingement tone stages fits the details of a feedback cycle if the disturbance convection velocity is chosen to be 20% higher than that necessary to satisfy the screech feedback loop. Phase locked optical records show a flapping mode of jet oscillation with tones at or near the screech frequency, with superimposed symmetric oscillations when a second dominant tone of unrelated frequency appears in the spectrum. RP NORUM, TD (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,MAIL STOP 461,HAMPTON,VA 23665, USA. NR 9 TC 10 Z9 12 U1 2 U2 5 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 JUL PY 1991 VL 29 IS 7 BP 1051 EP 1055 DI 10.2514/3.10703 PG 5 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200003 ER PT J AU ZAMAN, KBMQ MCKINZIE, DJ AF ZAMAN, KBMQ MCKINZIE, DJ TI CONTROL OF LAMINAR SEPARATION OVER AIRFOILS BY ACOUSTIC EXCITATION SO AIAA JOURNAL LA English DT Article ID FLOW AB The effect of acoustic excitation in reducing "laminar separation" over two-dimensional airfoils at low angles of attack is investigated experimentally. The separation involves a laminar unattached flow on the suction side, which is reattached effectively by even a small-amplitude excitation when the frequency is appropriate. Airfoils of two different cross sections, each with two different chord lengths, are studied in the chord Reynolds number range of 25,000 < R(c) < 100,000. While the amplitude of the excitation-induced velocity perturbation is kept constant at a reference point within the flowfield, it is found that the most effective excitation frequency scales as U(infinity)3/2. The parameter St/R(c)1/2 corresponding to the most effective frequency for all of the cases studied falls in the range of 0.02 to 0.03, with St being the Strouhal number based on the chord. RP ZAMAN, KBMQ (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,MAIL STOP 5-11,CLEVELAND,OH 44135, USA. NR 19 TC 26 Z9 27 U1 2 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1991 VL 29 IS 7 BP 1075 EP 1083 DI 10.2514/3.10706 PG 9 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200006 ER PT J AU STEINTHORSSON, E LI, Z SHIH, TIP NGUYEN, HL WILLIS, EA AF STEINTHORSSON, E LI, Z SHIH, TIP NGUYEN, HL WILLIS, EA TI FLUX-VECTOR SPLITTING ALGORITHM FOR CHAIN-RULE CONSERVATION-LAW FORM SO AIAA JOURNAL LA English DT Article ID NAVIER-STOKES EQUATIONS; FINITE-DIFFERENCE; IMPLICIT; FLOW AB A flux-vector splitting algorithm with Newton-Raphson iteration was developed for the "full compressible" Navier-Stokes equations cast in chain-rule conservation-law form. The algorithm is intended for problems with deforming spatial domains and for problems whose governing equations cannot be cast in strong conservation-law form. The usefulness of the algorithm for such problems was demonstrated by applying it to analyze the unsteady, two- and three-dimensional flows inside one combustion chamber of a Wankel engine under nonfiring conditions. Solutions were obtained to examine the algorithm in terms of conservation error, robustness, and ability to handle complex flows on time-dependent grid systems. C1 NASA,LEWIS RES CTR,DIV PROPULS SYST,CLEVELAND,OH 44135. RP STEINTHORSSON, E (reprint author), CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213, USA. NR 18 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1991 VL 29 IS 7 BP 1101 EP 1107 PG 7 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200009 ER PT J AU RUDY, DH THOMAS, JL KUMAR, A GNOFFO, PA CHAKRAVARTHY, SR AF RUDY, DH THOMAS, JL KUMAR, A GNOFFO, PA CHAKRAVARTHY, SR TI COMPUTATION OF LAMINAR HYPERSONIC COMPRESSION-CORNER FLOWS SO AIAA JOURNAL LA English DT Article AB A code validation study has been conducted using four different codes for solving the compressible Navier-Stokes equations. Computations for a series of nominally two-dimensional high-speed laminar separated flows were compared with detailed experimental shock-tunnel results. The shock-wave boundary-layer interactions considered were induced by a compression ramp. In general, good agreement was reached between two-dimensional grid-refined calculations and experiment for the incipient- and small-separation conditions. For the highly separated flow case, three-dimensional calculations, which included the finite-span effects of the experiment, were required in order to obtain agreement with the data. The finite-span effects were important in determining the extent of streamwise separation as well as the time required to establish the steady-now interaction. The results presented provide a resolution of discrepancies with the experimental data encountered in several recent computational studies. C1 NASA,LANGLEY RES CTR,FLOW PHYS BRANCH,HAMPTON,VA 23665. ROCKWELL INT CORP,CTR SCI,AEROTHERMODYNAM BRANCH,THOUSAND OAKS,CA 91360. RP RUDY, DH (reprint author), NASA,LANGLEY RES CTR,COMP AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 18 TC 25 Z9 26 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 JUL PY 1991 VL 29 IS 7 BP 1108 EP 1113 DI 10.2514/3.10710 PG 6 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200010 ER PT J AU RAMAN, G RICE, EJ AF RAMAN, G RICE, EJ TI AXISYMMETRICAL JET FORCED BY FUNDAMENTAL AND SUBHARMONIC TONES SO AIAA JOURNAL LA English DT Article ID INSTABILITY WAVES; MIXING LAYER; SHEAR-LAYER; ROUND JET; TURBULENCE AB A circular jet was excited simultaneously by two harmonically related tones. The results of this excitation on jet behavior are reported for three pairs of Strouhal numbers [St(D) = f*D/U(j) = 0.2 and 0.4, 0.3 and 0.6, 0.4 and 0.8]. For each case, the initial phase difference between the two tones was varied in steps of 45 deg for one full cycle, and the amplitude of the fundamental and subharmonic tones was varied independently over the range of 0.1-7.0% of the jet exit velocity. Several results of this study agreed with other published findings, such as a critical amplitude or the fundamental being required for subharmonic augmentation and the initial phase difference being critical in determining whether the subharmonic is augmented or suppressed. In addition, the detailed documentation or several aspects of this phenomenon, measured in the same experimental facility in a controlled manner, brought out two important points that had eluded previous researchers. First, at high levels of the fundamental and subharmonic forcing amplitudes, the subharmonic augmentation is independent of the initial phase difference. Second, two-frequency excitation is indeed more effective than single-frequency excitation in jet mixing enhancement. Higher spreading rates seem to go along with higher subharmonic levels. C1 NASA,LEWIS RES CTR,DUCTS NOZZLES FLOW PHYS BRANCH,CLEVELAND,OH 44135. RP RAMAN, G (reprint author), NASA,LEWIS RES CTR GRP,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 23 TC 23 Z9 24 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 JUL PY 1991 VL 29 IS 7 BP 1114 EP 1122 DI 10.2514/3.10711 PG 9 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200011 ER PT J AU BANDYOPADHYAY, PR AF BANDYOPADHYAY, PR TI INSTABILITIES AND LARGE STRUCTURES IN REATTACHING BOUNDARY-LAYERS SO AIAA JOURNAL LA English DT Article ID TURBULENT SHEAR-LAYER; MIXING LAYER; FLOW AB The underlying premise in this work is that large structures in turbulent shear flows are not universal and similar large structures in different flows owe their origins to basically similar instabilities. The turbulent boundary-layer flow over a backward-facing step and also the reattaching transitional boundary later behind a large spanwise rod have been studied experimentally in parallel primarily to understand the origin of the curious large structures observed in the far downstream region (after 39 step heights) of the former flowfield. Simultaneous now visualization and hot-wire anemometry and also plain-now visualization have been carried out. In the backward-facing step, the three-dimensional mixing layer developing after detachment persists even after reattachment. The flow does not recover fully back to a regular turbulent boundary layer even far downstream of reattachment. The turbulence-producing instability of a turbulent boundary layer continues to compete with the wall-bounded mixing layer instability, giving rise to the curious schismatic arrays of large structures. RP BANDYOPADHYAY, PR (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 170,HAMPTON,VA 23665, USA. NR 25 TC 9 Z9 9 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1991 VL 29 IS 7 BP 1149 EP 1155 DI 10.2514/3.10716 PG 7 WC Engineering, Aerospace SC Engineering GA FZ702 UT WOS:A1991FZ70200016 ER PT J AU CARTER, GA AF CARTER, GA TI PRIMARY AND SECONDARY EFFECTS OF WATER-CONTENT ON THE SPECTRAL REFLECTANCE OF LEAVES SO AMERICAN JOURNAL OF BOTANY LA English DT Article ID LEAF REFLECTANCE; LIGHT; PARAMETERS; ABSORPTION; DIFFUSE AB Leaves of six species selected to represent a broad range in internal structure were collected in the field and studied in the laboratory to determine primary and secondary effects of water content on leaf spectral reflectance. Primary effects were those that resulted solely from the radiative properties of water. Secondary effects were those that could not be explained solely by these properties. Decreased leaf water content generally increased reflectance throughout the 400-2,500-nm wavelength range. For the aquatics Eichhornia crassippes and Nuphar luteum, the broadleaved trees Liquidambar styraciflua and Magnolia grandiflora, and cane-grass Arundinaria tecta, and the needle-leaved Pinus taeda, the sensitivity of reflectance to water content was greatest in the water absorption bands near 1,450, 1,940, and 2,500 nm. Sensitivity maxima occurred also between 400 and 720 nm, indicating secondary effects that resulted from decreased absorption by pigments. Secondary effects of water content on reflectance that were largely wavelength-independent, together with any wavelength-independent effects of leaf internal structure, were far less significant than primary and secondary effects resulting from decreased absorption by water and pigments, respectively. RP CARTER, GA (reprint author), NATL AERONAUT & SPACE ADM,SCI & TECHNOL LAB,STENNIS SPACE CTR,MS 39529, USA. NR 33 TC 195 Z9 212 U1 3 U2 34 PU BOTANICAL SOC AMER INC PI COLUMBUS PA OHIO STATE UNIV-DEPT BOTANY 1735 NEIL AVE, COLUMBUS, OH 43210 SN 0002-9122 J9 AM J BOT JI Am. J. Bot. PD JUL PY 1991 VL 78 IS 7 BP 916 EP 924 DI 10.2307/2445170 PG 9 WC Plant Sciences SC Plant Sciences GA FX432 UT WOS:A1991FX43200005 ER PT J AU LEE, SC RATLIFF, M PETERSON, C LOLLAR, LF AF LEE, SC RATLIFF, M PETERSON, C LOLLAR, LF TI AMPERES - A REAL-TIME FAULT MONITORING AND DIAGNOSIS KNOWLEDGE-BASED SYSTEM FOR SPACE POWER-SYSTEMS SO APPLIED ARTIFICIAL INTELLIGENCE LA English DT Article AB A real-time fault monitoring and diagnosis knowledge-based system (KBS) has been developed for space power systems to save costly operational manpower and to achieve reliable space power system operation. The developed KBS, called AMPERES (autonomously managed power-system extendible real-time expert system), was developed using the autonomously managed power system (AMPS) test facility currently installed at NASA Marshall Space Flight Center (MSFC). The approaches taken for AMPERES are generic and should be applicable for other space power systems. A sensor value validation method based on causal relations (CRs) and their interrelations within the sensor redundancy graphs (SRG) has been developed and applied in AMPERES to increase the confidence in the validity of the sensor values and consequently in the results of the fault diagnosis. The validation results also yield essential information for fault diagnosis identifying the existence of a potential fault and the location or the extent of the fault. A disturbance interrelation analysis graph (DIAG) scheme has been developed to characterize the fault diagnosis problems clearly and to perform the fault monitoring and diagnosis tasks effectively by explicitly showing the diagnosis reasoning paths. The DIAG approach also enables the fault diagnosis KBS to describe a fault in several different abstraction levels and in different component granularities. C1 UNIV TENNESSEE,INST SPACE,DEPT COMPUT SCI,TULLAHOMA,TN 37388. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,INFORMAT & ELECTR SYST LAB,HUNTSVILLE,AL 35812. NR 24 TC 3 Z9 3 U1 1 U2 1 PU TAYLOR & FRANCIS PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 0883-9514 J9 APPL ARTIF INTELL JI Appl. Artif. Intell. PD JUL-SEP PY 1991 VL 5 IS 3 BP 281 EP 308 DI 10.1080/08839519108927930 PG 28 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GG119 UT WOS:A1991GG11900005 ER PT J AU SEKANINA, Z AF SEKANINA, Z TI COMPREHENSIVE MODEL FOR THE NUCLEUS OF PERIODIC COMET TEMPEL-2 AND ITS ACTIVITY SO ASTRONOMICAL JOURNAL LA English DT Article ID DUST-EMISSION PATTERN; SPIN VECTOR; P TEMPEL-2; HALLEY; ASTEROIDS; SPECTROPHOTOMETRY; LIGHTCURVES; P/TEMPEL-2; PHOTOMETRY; TOPOGRAPHY AB Observational data obtained primarily during 1988 are analyzed and synthesized to develop a comprehensive physical model for the nucleus of Periodic Comet Tempel 2, one of the best studied members of Jupiter's family of short-period comets. It is confirmed that a previous investigation (Sekanina 1987b) provided reliable information on the comet's spin-axis orientation, which implies an obliquity of 54-degrees of the orbit plane to the equatorial plane and which appears to have varied little-if at all-with time. This conclusion is critical for fitting a triaxial ellipsoid to approximate the figure of the nucleus. Its dimensions are found to be 16.4 X 9.8 X 7.0 km, if A'Hearn et al.'s (1989) visual geometric albedo of 0.022 is accepted. While the nucleus of P/Temple 2 is similar to that of P/Halley in volume and surface area, it is distinctly more flattened in the polar direction. Forced precession, caused by torques from outgassing, is shown to be negligible, but there may be an effect on the nucleus spin rate. If this effect was insignificant in the period of February-June 1988, the remarkable invariability of the comet's sidereal rotation period, derived to be 8h55m55.2s with a formal uncertainty of only +/- 0.2s, would indicate general correctness of the employed spin-vector positional determination. Temporal variations in the production of water cannot be fitted on the assumption of outgassing from a flat region (or regions). An appreciable depth is implied, leading to the conclusion that the source is probably a vent-like depression (or depressions). Assuming that outgassing is possible only from the depression's floor when it is sunlit and that there is no outgassing from the walls, the best match is found for an effective diameter-to-depth ratio of 1.6, a total floor area of 14 km2, and a slope angle of the walls of 81-degrees. The total loss rate of water is estimated at 10(13) g per revolution about the Sun. Deconvolution of the observed optical and thermal infrared diurnal light curves consistently reveals the existence of three isolated vents on the nucleus within about 30-degrees of the northern rotation pole. Modeling of a collimated flow of dust ejecta from a vent indicates the presence of disintegrating particles in the coma, whose typical lifetimes are 25-30 hr. The differential size distribution for large grains varies inversely as the cube of particle size, with a poorly defined cutoff radius of 1 mm. There is also some evidence for a population of very short-lived, perhaps water ice, grains. The dust production rate on 22-30 June is found to have amounted to 10(5) g/s, implying a dust-to-water production rate ratio of 0.7-1.0 by mass. The proposed model indicates that the calculated nucleus figure corresponds to one of the hydrostatic equilibrium configurations known as Jacobi ellipsoids. The derived sideral rotation period suggests an "equilibrium" nucleus density of 0.54 g/cm3 and implies that the comet's nucleus cannot be subjected to significant hydrostatic forces. To facilitate future testing of the nucleus model, predictions are provided for expected temporal variations (i) in the axial orientation of the fan-shaped coma, (ii) in the parameters of the optical and thermal infrared diurnal light curves of the nucleus, and (iii) in the water production rate. It is noted that the comet's return of 2005 is so extremely unfavorable to ground-based optical monitoring for several months on either side of perihelion that the choice of P/Tempel 2 as the target for a dedicated rendezvous mission at this return can only be described as an unfortunate decision. RP SEKANINA, Z (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 54 TC 27 Z9 27 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1991 VL 102 IS 1 BP 350 EP 388 DI 10.1086/115881 PG 39 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT833 UT WOS:A1991FT83300029 ER PT J AU FERRANDO, P LAL, N MCDONALD, FB WEBBER, WR AF FERRANDO, P LAL, N MCDONALD, FB WEBBER, WR TI STUDIES OF LOW-ENERGY GALACTIC COSMIC-RAY COMPOSITION AT 22-AU .1. SECONDARY PRIMARY RATIOS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COSMIC RAYS; ABUNDANCES; PROPAGATION ID FRAGMENTATION CROSS-SECTIONS; RELATIVISTIC NUCLEI; CARBON TARGETS; OUTER HELIOSPHERE; HYDROGEN; CHARGE; HELIUM; SOLAR; PROPAGATION; ABUNDANCES AB Data from the High Energy Telescope of the CRS experiment on Voyager 2 have been used to measure the intensity, spectra, and elemental abundances of Galactic cosmic rays from Be to Ni at approximately 100 Me V/n. The charge resolution of this telescope varies from sigma = 0.034 for oxygen to sigma = 0.11 for iron. The solar modulation deceleration parameter phi-relevant for these data is estimated to be around 300 MV (PHI = 150 Me V/n for particles with A/Z = 2), an unprecedently low level for such measurements. This low modulation parameter is a result of the measurements being made in the outer heliosphere at a heliocentric distance of 22 AU, and centered on the solar minimum period of cycle 21. The results on secondary/primary ratios are used to test the Leaky-Box model of cosmic ray propagation, using the most recent cross sections data in hydrogen and helium, and taking into account the effects of the ionized fraction of the interstellar medium. It is found that all the secondary/primary ratios up to P/S are completely consistent with an exponential pathlength distribution (PLD). This PLD shape also accounts for the Sc-V/Fe ratio. A truncation of the PLD, suggested by other measurements at low energy, is not excluded by our data on the Sc + Ti + V/Fe ratio, however. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV MARYLAND, INST PHYS SCI & TECHNOL, COLLEGE PK, MD 20742 USA. NEW MEXICO STATE UNIV, DEPT ASTRON, LAS CRUCES, NM 88003 USA. RP FERRANDO, P (reprint author), CENS, SERV ASTROPHYS, F-91191 GIF SUR YVETTE, FRANCE. NR 41 TC 42 Z9 42 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 JUL PY 1991 VL 247 IS 1 BP 163 EP 172 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX453 UT WOS:A1991FX45300028 ER PT J AU GEISS, J ALTWEGG, K ANDERS, E BALSIGER, H IP, WH MEIER, A NEUGEBAUER, M ROSENBAUER, H SHELLEY, EG AF GEISS, J ALTWEGG, K ANDERS, E BALSIGER, H IP, WH MEIER, A NEUGEBAUER, M ROSENBAUER, H SHELLEY, EG TI INTERPRETATION OF THE ION MASS-SPECTRA IN THE MASS PER CHARGE RANGE 25-35 AMU/E OBTAINED IN THE INNER COMA OF HALLEY COMET BY THE HIS-SENSOR OF THE GIOTTO IMS EXPERIMENT SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMETARY ATMOSPHERE; MASS SPECTROMETRY; ION SPECTRA; MOLECULAR PROCESSES ID GAS-PHASE CHEMISTRY; INTERSTELLAR CLOUDS; PLANETARY-ATMOSPHERES; P/HALLEY; IDENTIFICATION; RECOMBINATION; FORMALDEHYDE; MODEL; TIME AB The IMS-HIS double-focusing mass spectrometer that flew on the Giotto spacecraft covered the mass per charge range from 12 to 56 (amu/e). By comparing flight data, calibration data and results of model calculations of the ion population in the inner coma, the absolute mass scale is established, and ions in the mass range 25 to 35 are identified. Ions resulting from protonation of molecules with high proton affinity are relatively abundant, enabling us to estimate relative source strengths for H2CO, CH3OH, HCN, and H2S, providing for the first time a positive in situ measurement of methanol. Also upper limits for NO and some hydrocarbons are derived. C1 MAX PLANCK INST AERON, W-3411 KATHLENBURG LINDAU, GERMANY. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, PASADENA, CA 91125 USA. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. RP GEISS, J (reprint author), UNIV BERN, INST PHYS, CH-3012 BERN, SWITZERLAND. RI Anders, Edward/B-7980-2009 NR 47 TC 51 Z9 51 U1 0 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1991 VL 247 IS 1 BP 226 EP 234 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX453 UT WOS:A1991FX45300033 ER PT J AU JACOBSON, RA RIEDEL, JE TAYLOR, AH AF JACOBSON, RA RIEDEL, JE TAYLOR, AH TI THE ORBITS OF TRITON AND NEREID FROM SPACECRAFT AND EARTHBASED OBSERVATIONS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ASTROMETRY; CELESTIAL MECHANICS; NEREID; SATELLITES OF NEPTUNE; TRITON AB In this paper we discuss the determination of improved orbits for the Neptunian satellites Triton and Nereid. Our primary results are the final set of model parameters which generate orbits that best fit both the Earthbased satellite observations and data acquired by the Voyager spacecraft during the Neptune encounter. We assess the accuracy of the improved orbits and compare them with the orbits generated prior to the encounter. We also provide mean elements as a geometrical representation for the orbits. RP JACOBSON, RA (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 15 TC 48 Z9 50 U1 0 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1991 VL 247 IS 2 BP 565 EP 575 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ707 UT WOS:A1991FZ70700039 ER PT J AU DUTREY, A LANGER, WD BALLY, J DUVERT, G CASTETS, A WILSON, RW AF DUTREY, A LANGER, WD BALLY, J DUVERT, G CASTETS, A WILSON, RW TI PERIODICALLY SPACED FRAGMENTATION IN ORION-A SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE MOLECULAR CLOUDS; STAR FORMATION; INTERSTELLAR MAGNETIC FIELD ID MOLECULAR CLOUDS; DARK CLOUDS; TAURUS AB We have found evidence for periodic density structure in the highly fragmented interior of the Orion A molecular cloud from analysis of a large scale map of (CO)-O-18 J = 1 - 0 emission. The spatial wavelength is about 1 parsec and extends at least over 2 degrees along the main filament of Orion A and is also observed in other filamentary structures in Orion. We suggest that this periodicity in the clumps is a result of externally triggered and magnetically mediated cloud collapse and fragmentation. C1 AT&T BELL LABS, HOLMDEL, NJ 07733 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP DUTREY, A (reprint author), OBSERV GRENOBLE, BP 53X, F-38041 GRENOBLE, FRANCE. NR 20 TC 41 Z9 41 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 JUL PY 1991 VL 247 IS 1 BP L9 EP L12 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FX453 UT WOS:A1991FX45300003 ER PT J AU VERTER, F AF VERTER, F TI THE CO-LUMINOSITY FUNCTION OF GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INTERSTELLAR MATTER; LUMINOSITY FUNCTION ID ULTRALUMINOUS INFRARED GALAXIES; IRREGULAR GALAXIES; MOLECULAR GAS; SPIRAL GALAXIES; STAR FORMATION; VIRGO CLUSTER; IRAS OBSERVATIONS; CARBON-MONOXIDE; FIELD GALAXIES; SAMPLE AB The CO luminosity function that was originally derived by Verter is here reevaluated for a galaxy sample that is drawn from the published portion of the FCRAO Extragalactic CO Survey satisfying B(T)0 less-than-or-equal-to 12 mag. The derived CO luminosity function is approximately a power law [L(CO)]-alpha, with alpha almost-equal-to -1.3. This is consistent with previous galaxy luminosity functions in the blue and infrared, and with correlations between L(CO) and L(B) or L(IR). RP VERTER, F (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MC685,GREENBELT,MD 20771, USA. NR 51 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1991 VL 375 IS 1 BP 95 EP 104 DI 10.1086/170172 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600009 ER PT J AU FEDERMAN, SR ALLEN, M AF FEDERMAN, SR ALLEN, M TI FORMALDEHYDE IN ENVELOPES OF INTERSTELLAR DARK CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, GRAINS; INTERSTELLAR, MOLECULES; MOLECULAR PROCESSES ID INTER-STELLAR CLOUDS; GAS-PHASE CHEMISTRY; MOLECULAR CLOUD; STEADY-STATE; CARBON; MODELS; GRAINS; CORES; ABUNDANCES; STARS AB Observed formaldehyde column densities of 1 x 10(12)-3 x 10(13) cm-2 in cloud envelopes along lines of sight with A(V) = 1-4 mag cannot be explained with our current understanding of interstellar gas phase chemistry. However, these column densities can be reproduced by a simple time-dependent model in which H2CO is supplied to the gas phase by the erosion of icy grain mantles. The release of H2CO from the grain mantles must occur on time scales comparable to the time scales for mixing from the cloud interior to the cloud envelope (approximately 10(5) yr). Thus, in low-density regions of clouds, it appears that formaldehyde is the second molecule whose gas phase source is primarily ejection from grains. Our simple model suggests understanding gas phase steady state in clouds on macroscopic, rather than microscopic, spatial scales. C1 UNIV TOLEDO,DEPT PHYS & ASTRON,TOLEDO,OH 43606. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP FEDERMAN, SR (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 43 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 JUL 1 PY 1991 VL 375 IS 1 BP 157 EP 162 DI 10.1086/170177 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600014 ER PT J AU FERRIERE, KM MACLOW, MM ZWEIBEL, EG AF FERRIERE, KM MACLOW, MM ZWEIBEL, EG TI EXPANSION OF A SUPERBUBBLE IN A UNIFORM MAGNETIC-FIELD SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDROMAGNETICS; INTERSTELLAR, MATTER; SHOCK WAVES; STARS, SUPERNOVAE ID H-I SHELLS; SUPERNOVA-REMNANTS; THEORETICAL-MODELS; MASSIVE STARS; O-STARS; SUPERSHELLS; SHOCKS; ASSOCIATION; EXPLOSIONS; GALAXIES AB We investigate the effects of interstellar magnetic fields on the evolution and structure of superbubbles. We first derive the governing equations for propagation of a radiative shock, and solve them analytically in the limit of high expansion velocity. We then present a numerical code able to solve them in the general case and discuss the numerical results. We find that magnetic fields of the strength present in the Galactic disk do not significantly modify the overall shape and dimensions of a superbubble. They reduce the volume of the interior cavity by one-third on average during the expansion phase. The shell elongates slightly in the direction of the external field. Magnetic pressure dominates over gas pressure in most of the shell and forces it to thicken substantially. Finally, because of the transverse mass motions which take place from the magnetic poles to the equator, the column density at the poles is reduced by typically a factor of 10. C1 NASA,AMES RES CTR,THEORET STUDIES BRANCH,MOFFETT FIELD,CA 94035. UNIV COLORADO,NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80302. RP FERRIERE, KM (reprint author), UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,CAMPUS BOX 391,BOULDER,CO 80309, USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 47 TC 94 Z9 94 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 JUL 1 PY 1991 VL 375 IS 1 BP 239 EP 253 DI 10.1086/170185 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600022 ER PT J AU FEIBELMAN, WA AF FEIBELMAN, WA TI THE ULTRAVIOLET-SPECTRUM OF KX-TRIANGULI AUSTRALIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (KX-TRIANGULI AUSTRALIS); STARS, SYMBIOTIC; ULTRAVIOLET, SPECTRA ID SYMBIOTIC STARS; PLANETARY-NEBULAE; FE-II; IUE; CATALOG AB The symbiotic star KX TrA (= Cn 1-2) was observed with the IUE satellite in the low- and high-dispersion mode on 1990 May 7. The low-dispersion data show no significant changes from previous observations taken a decade ago. The high-dispersion spectra were used to determine electron densities from several diagnostic line ratios and show a range of log N(e) from 5.8 to 11.1 cm-3. No P Cygni-type features were observed. Resonantly excited high-excitation Fe II emission lines are seen in the UV spectrum of KX TrA, which strongly argues for the existence of a very hot (> 60,000 K) subdwarf or white dwarf in the system. As was previously noted, the S-type symbiotic KX TrA exhibits an UV spectrum that is nearly identical to that of the D-type symbiotic V1016 Cyg. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 42 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1991 VL 375 IS 1 BP 335 EP 341 DI 10.1086/170192 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600029 ER PT J AU WINGLEE, RM KIPLINGER, AL ZARRO, DM DULK, GA LEMEN, JR AF WINGLEE, RM KIPLINGER, AL ZARRO, DM DULK, GA LEMEN, JR TI INTERRELATION OF SOFT AND HARD X-RAY EMISSIONS DURING SOLAR-FLARES .1. OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PARTICLE ACCELERATION; RADIATION MECHANISMS; SUN, FLARES; SUN, X-RAYS ID LOOP RADIATIVE HYDRODYNAMICS; RETURN CURRENT SYSTEMS; CHROMOSPHERIC EVAPORATION; IMPULSIVE PHASE; RADIO SPIKES; PLASMA; ELECTRONS; MOTIONS; SPECTRA; BURSTS AB Simultaneous observations of hard X-rays and of soft X-ray line emissions at high time resolution (congruent-to 6 s) from the Solar Maximum Mission (SMM) are used to determine the interrelation between the acceleration and heating of electrons and ions during impulsive solar flares. The study involves five flares (three disk and two limb flares). It is shown that for all the flares, the hard X-rays have a power-law spectrum which breaks down during the rise phase and beginning of the decay phase, after which the spectrum changes to either a single power law or a power law which breaks up at high energies. The characteristics of the soft X-rays depend on the flare position. For the three disk flares, the line emissions show a blueshifted component (arising from upward acceleration of ions into the corona) with the maximum inferred velocity reaching its peak value during the decay phase in association with the disappearance of the (downward) break in the hard X-ray spectrum. For limb flares the soft X-ray line emissions show only a nonthermally broadened stationary component (arising from acceleration and heating perpendicular to the magnetic field); this broadening reaches a maximum at the hard (greater-than-or-similar-to 50 keV) X-ray peak rather than during the decay phase. These observations are not consistent with models where the chromospheric outflow is driven by explosive heating since both the blueshifts and broadening are predicted to have the same dependence on the hard X-ray flux. It is argued instead that small-scale quasi-static electric fields are important for determining the acceleration of the X-ray-producing electrons and the outflowing chromospheric ions. These electric fields provide bulk acceleration of energetic electrons into the chromosphere (with the electric potential being of the order of the break energy). At the same time, they accelerate ions across the field lines and out into the corona. The different behavior of the blueshifts and broadening relative to the hard X-ray emissions is attributed to differences in scale lengths parallel and perpendicular to the magnetic field. C1 UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,BOULDER,CO 80309. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NOAA,SPACE ENVIRONM LAB,BOULDER,CO 80303. LOCKHEED PALO ALTO RES LABS,DEPT 9130,PALO ALTO,CA 94304. APPL RES CORP,PALO ALTO,CA. NR 43 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 JUL 1 PY 1991 VL 375 IS 1 BP 366 EP 381 DI 10.1086/170196 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600033 ER PT J AU LINDSEY, CA ROELLIG, TL AF LINDSEY, CA ROELLIG, TL TI TELESCOPE BEAM-PROFILE DIAGNOSTICS AND THE SOLAR LIMB SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; SUN, LIMB DARKENING; SUN, RADIO RADIATION AB We describe the basic method for determining the solar limb brightness profile properly corrected for spurious limb darkening caused by the far wings of the resolving beams encountered in large far-infrared and radio telescopes. When the far wings of the beam can be independently measured, this problem is usually amenable to standard deconvolution procedures. In practice, however, the far wings of the beam are best determined using the solar limb itself. While we do not know a priori the solar brightness profile inside the limb, we may assume that the brightness profile outside the limb drops sharply to zero at submillimeter and millimeter wavelengths. We are thus interested in the problem of deconvolution where we do not initially know the convolving kernel but are partially informed of the source distribution. Under a broad range of well-defined cases, solutions to this deconvolution problem are unique to within the discrimination provided by the core of the beam profile. We apply the theory to solar limb scans made recently on the James Clerk Maxwell Telescope to show solar limb brightening in 850-mu-m radiation. C1 NASA,AMES RES CTR,ASTROPHYS BRANCH,MOFFETT FIELD,CA 94035. RP LINDSEY, CA (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. NR 16 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1991 VL 375 IS 1 BP 414 EP 422 DI 10.1086/170199 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600036 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI LINEAR AND CIRCULAR DIGITAL SPECTRAL-ANALYSIS OF SERIAL DATA SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUMERICAL METHODS; SUN, SUNSPOTS ID UNEQUALLY SPACED DATA; ALGORITHM; TIME AB Two methods of digital spectral analysis of unevenly sampled data are developed and illustrated here. One method uses a linear function of time (or space), the other uses circular functions. The circular method turns out to be essentially equivalent to a least-squares sine-wave analysis. The linear, anharmonic method uses only the field of real numbers and elementary algebraic operations, and hence it can be made computationally very fast and accurate. Both methods are very general, properly handling all kinds of time series ranging from simple series consisting only of the times of events to complicated series consisting of pulses with long duty cycles. The two methods are here applied to the analysis of annual mean relative sunspot numbers. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,GREENBELT,MD 20771, USA. NR 18 TC 5 Z9 5 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 JUL 1 PY 1991 VL 375 IS 1 BP 423 EP 426 DI 10.1086/170200 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT836 UT WOS:A1991FT83600037 ER PT J AU GEHRELS, N BARTHELMY, SD TEEGARDEN, BJ TUELLER, J LEVENTHAL, M MACCALLUM, CJ AF GEHRELS, N BARTHELMY, SD TEEGARDEN, BJ TUELLER, J LEVENTHAL, M MACCALLUM, CJ TI GRIS OBSERVATIONS OF POSITRON-ANNIHILATION RADIATION FROM THE GALACTIC-CENTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES THE GALAXY; GAMMA RAYS GENERAL ID GAMMA-RAY SPECTRUM; CENTER REGION; CENTER DIRECTION; LINE AB We report new observations of the Galactic center positron annihilation source in which, for the first time, the 511 keV line has been spectrally resolved and the Galactic plane and center components have been independently measured. High-resolution spectra were obtained of the Galactic center with the Gamma-Ray Imaging Spectrometer (GRIS) during May and October of 1988 balloon flights. The 511 keV line source was found to be turned on again in October of 1988, at a flux of (11.8 +/- 1.6) x 10(-4) photons cm-2 s-1, after being observed in a quiescent state since the early 1980s. There is evidence for variability between May and October. An observation of a point in the Galactic plane 25-degrees west of the center was made during the October flight. The 511 keV line flux for this pointing was significantly lower, less than 4.0 x 10(-4) photons cm-2 s-1 (2-sigma upper limit), than that for the center pointing, proving unambiguously that the center emission is concentrated near l(II) = 0-degrees. The GRIS data combined with that from other narrow-field observations in the 1980s support the two-component model of the positron annihilation source. The best fit to these data sets gives a flux of approximately 8 x 10(-4) photons cm-2 s-1 for the center point source component in its high state. A strong hard X-ray continuum was detected in the Galactic plane observation. This "diffuse" continuum component makes up the difference between the observed continuum in the GRIS Galactic center pointing and the known point source contributions, solving the long-standing mystery of why wide-field instruments have detected such high continuum emission from the Galactic center. C1 AT&T BELL LABS,PHYS RES LAB,MURRAY HILL,NJ 07974. UNIV NEW MEXICO,DEPT PHYS & ASTRON,ALBUQUERQUE,NM 87131. RP GEHRELS, N (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012; Barthelmy, Scott/D-2943-2012 NR 28 TC 59 Z9 59 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1991 VL 375 IS 1 BP L13 EP L16 DI 10.1086/186077 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT838 UT WOS:A1991FT83800004 ER PT J AU TEEGARDEN, BJ BARTHELMY, SD GEHRELS, N TUELLER, J LEVENTHAL, M MACCALLUM, CJ AF TEEGARDEN, BJ BARTHELMY, SD GEHRELS, N TUELLER, J LEVENTHAL, M MACCALLUM, CJ TI GRIS OBSERVATIONS OF AL-26 GAMMA-RAY LINE EMISSION FROM 2 POINTS IN THE GALACTIC PLANE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES THE GALAXY; GAMMA RAYS GENERAL ID RADIATION AB The GRIS (Gamma-Ray Imaging Spectrometer) experiment observed the Galactic center region during a balloon flight over Alice Springs, Australia, on 1988 October 28-30. Two observations of the Galactic plane were made at l = 0-degrees and 335-degrees, respectively. Al-26 gamma-ray line emission (1809 keV) was detected during both observations,although that in the latter was statistically marginal. For an assumed Galactic longitude distribution similar to high-energy gamma rays, the inferred fluxes at l = 0-degrees are 4.2 (+1.9, -1.7) x 10(-4) cm-1 s-1 rad-1 (2.5-sigma) and 5.4 (+2.9, -3.1) x 10(-4) cm-1 s-1 rad-1 (1.7-sigma) for the two observations. For the combined l = 0-degrees and 335-degrees data sets, we calculate a flux of 4.5 (+1.5, -1.6) x 10(-4) cm-1 s-1 rad-1 (2.8-sigma). These observations are consistent with the assumed high-energy gamma-ray distribution, but they are consistent with other distributions as well. The marginal statistics of the observations combined with the broad field of view (40-degrees effective FWHM) do not permit meaningful tests of the model distributions to be made. The data do, however, suggest that the Al-26 emission is distributed over Galactic longitude rather than confined to a point source. The GRIS data hint that the 1809 keV line is broadened. The measured FWHM of the 1809 keV line for the combined data set is 5.1 (+2.1, -2.3) keV, which differs from zero by 2.3-sigma. C1 AT&T BELL LABS,PHYS RES LAB,MURRAY HILL,NJ 07974. UNIV NEW MEXICO,DEPT PHYS & ASTRON,ALBUQUERQUE,NM 87131. RP TEEGARDEN, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012; Barthelmy, Scott/D-2943-2012 NR 17 TC 10 Z9 10 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 JUL 1 PY 1991 VL 375 IS 1 BP L9 EP L12 DI 10.1086/186076 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT838 UT WOS:A1991FT83800003 ER PT J AU GREEN, S AF GREEN, S TI COLLISIONAL EXCITATION OF FORMALDEHYDE IN HOT INTERSTELLAR MOLECULAR REGIONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE INTERSTELLAR, MOLECULES; MOLECULAR PROCESSES ID POTENTIAL-ENERGY SURFACE; RIGID ASYMMETRIC-TOP; ROTATIONAL-EXCITATION; RATE CONSTANTS; INELASTIC-SCATTERING; CROSS-SECTIONS; HE; TEMPERATURES; ORTHO-NH3; SPECTRUM AB Earlier calculations for rotational excitation of formaldehyde by collisions with He atoms are extended to include the lowest 81 rotational levels and kinetic temperatures to 300 K. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771, USA. NR 27 TC 67 Z9 67 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1991 VL 76 IS 3 BP 979 EP 983 DI 10.1086/191585 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR382 UT WOS:A1991FR38200004 ER PT J AU DUDLEY, GA TESCH, PA HARRIS, RT GOLDEN, CL BUCHANAN, P AF DUDLEY, GA TESCH, PA HARRIS, RT GOLDEN, CL BUCHANAN, P TI INFLUENCE OF ECCENTRIC ACTIONS ON THE METABOLIC COST OF RESISTANCE EXERCISE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID ENERGY-EXPENDITURE; MUSCLE; RESPONSES; WORK AB Maintenance of a low energy expenditure during exercise in space is important because of the confined environment of the space craft. Resistance exercise is receiving increased attention as an exercise countermeasure, and we have shown that training with concentric (con) and eccentric (ecc) muscle actions induces greater increases in strength than training with only con actions. This study determined if performance of both actions markedly increased the metabolic cost of resistance exercise. Seventeen middle-age males performed each repetition of a "warm-up" and four sets of the leg press exercise with only con (Group CON, n = 8) or with con and ecc (Group CON/ECC, n = 9) actions. Sets were separated by 3 min of rest and each was performed to failure by selecting a resistance that allowed performance of the prescribed number of repetitions (7 to 10). The net energy cost of exercise was estimated from oxygen consumption data that were obtained at rest before exercise, during exercise, and for 20 min of recovery. The total work performed during the con actions was about 290 J . kg-1 body weight for both groups. The energy cost for this work was about 3 x 10(-3) cal . J-1. The requirement for the CON/ECC group to also lower the load increased (p < 0.05) the energy cost 14%. These results indicate that con actions are mainly responsible for the metabolic cost of resistance exercise. Because ecc actions enhance the resistance training-induced increases in strength that are evident with only con actions with minimal additional energy cost, we suggest that they be considered in exercise prescriptions for use in space. C1 OHIO UNIV,DEPT ZOOL & BIOMED SCI,ATHENS,OH 45701. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL. KAROLINSKA INST,DEPT PHYSIOL,ENVIRONM PHYSIOL LAB,S-10401 STOCKHOLM 60,SWEDEN. RP DUDLEY, GA (reprint author), BIONET CORP,BIOMED & ENVIRONM LABS,MAIL CODE BIO-6,KENNEDY SPACE CTR,FL 32899, USA. NR 28 TC 57 Z9 57 U1 1 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUL PY 1991 VL 62 IS 7 BP 678 EP 682 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA FU023 UT WOS:A1991FU02300014 PM 1898305 ER PT J AU WOODS, KD FEIVESON, AH BOTKIN, DB AF WOODS, KD FEIVESON, AH BOTKIN, DB TI STATISTICAL ERROR ANALYSIS FOR BIOMASS DENSITY AND LEAF-AREA INDEX ESTIMATION SO CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE LA English DT Article ID NORTHERN AB Dimension analysis uses fitted allometric relationships to estimate whole-tree characteristics from dimensional measurements. Errors in dimension-analysis estimates of forest stand biomass and leaf area are often unreported and rarely analyzed. Errors may arise from measurement error, choice of model, fitting of parameters in models, and spatial variation within a sampled stand. Examination of these components separately will show how efficiency can be most effectively increased and balanced. We used dimension analysis to estimate biomass density and leaf area index for stands of trembling aspen (Populus tremuloides Michx.) and black spruce (Picea mariana (Mill.) B.S.P.) in the Superior National Forest, Minnesota, United States. Estimates had average coefficients of variation ranging from 11% (aspen biomass density) to 23% (spruce leaf area index). Partitioning of these errors showed that error sources varied with species, variable, and site conditions, but most error was due either to parameter estimation or to spatial variation; model inaccuracies contributed only trivially to total error. The most cost-effective means of increasing precision of estimation would be to sacrifice more trees (even with less precise measurements of individual trees) to fit the models, or sample larger areas in stands; more sophisticated models would have little effect on error. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV CALIF SANTA BARBARA,SANTA BARBARA,CA 93106. RP WOODS, KD (reprint author), BENNINGTON COLL,BENNINGTON,VT 05201, USA. NR 25 TC 31 Z9 34 U1 3 U2 6 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0045-5067 J9 CAN J FOREST RES JI Can. J. For. Res.-Rev. Can. Rech. For. PD JUL PY 1991 VL 21 IS 7 BP 974 EP 989 DI 10.1139/x91-135 PG 16 WC Forestry SC Forestry GA HX879 UT WOS:A1991HX87900004 ER PT J AU BRILL, RW BUSHNELL, PG AF BRILL, RW BUSHNELL, PG TI EFFECTS OF OPEN-SYSTEM AND CLOSED-SYSTEM TEMPERATURE-CHANGES ON BLOOD-OXYGEN DISSOCIATION CURVES OF SKIPJACK TUNA, KATSUWONUS-PELAMIS, AND YELLOWFIN TUNA, THUNNUS-ALBACARES SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID ACID-BASE REGULATION; FISH HEMOGLOBINS; SALMO-GAIRDNERI; AMBIENT OXYGEN; RAINBOW-TROUT; BLUEFIN TUNA; HEAT; THERMOREGULATION; RESPONSES; EXCHANGE AB Tunas often experience rapid temperature changes of 10-degrees-C or more during their daily vertical movements. Their blood is therefore subjected to open-system (i.e., constant O2 and CO2 partial pressure, variable O2 and CO2 content) temperature changes during passage through the gills. In addition, tunas possess vascular countercurrent heat exchangers and can have deep red muscle temperatures as much as 20-degrees-C above ambient. Their blood also experiences closed-system (i.e., constant O2 and CO2 content, variable O2 and CO2 partial pressure) temperature changes during passage through the heat exchangers. Temperature-independent blood O2 binding could be expected. We found blood oxygen dissociation curves of skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) to be temperature independent during open-system temperature changes. Although blood from both species showed unsually large Bohr effects (-0.986 and -0.865 DELTA-log P50 . DELTA-pH-1 for skipjack and yellowfin tuna, respectively) when subjected to CO2 partial pressure alterations in the open system, the oxygen dissociation curves of skipjack tuna blood were nearly temperature independent during closed-system temperature changes. In other words, blood from skipjack tuna showed a reduced Bohr effect when subjected to the inevitable CO2 partial pressure changes that accompany closed-system temperature shifts. Since skipjack tuna blood shows temperature-independent O2 binding during closed-system temperature changes whereas yellowfin tuna blood does not, this unusual feature is not obligatory in thermoconserving fishes. C1 UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. RP BRILL, RW (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 53 TC 26 Z9 26 U1 1 U2 6 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUL PY 1991 VL 69 IS 7 BP 1814 EP 1821 DI 10.1139/z91-250 PG 8 WC Zoology SC Zoology GA GP060 UT WOS:A1991GP06000011 ER PT J AU BRILL, RW BUSHNELL, PG AF BRILL, RW BUSHNELL, PG TI METABOLIC AND CARDIAC SCOPE OF HIGH-ENERGY DEMAND TELEOSTS, THE TUNAS SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article; Proceedings Paper CT SYMP ON CARDIAC SCOPE IN LOWER VERTEBRATES CY MAY 03, 1990 CL SIMON FRASER UNIV, BURNABY, CANADA HO SIMON FRASER UNIV ID TROUT SALMO-GAIRDNERI; MYOCARDIAL OXYGEN-CONSUMPTION; PACIFIC BLUE MARLIN; WARM-BODIED FISH; RAINBOW-TROUT; THUNNUS-ALALUNGA; SKIPJACK TUNA; KATSUWONUS-PELAMIS; VENTRICULAR MYOCARDIUM; ALBACORE TUNA AB The maximum aerobic metabolic rates of tunas are far above those of other fishes. In this review we attempt to define features of the cardiovascular system that may account for this extreme performance. Tuna hearts are much larger than those of most other fishes and are half the mass of those of similarly sized mammals; however, the ratio of compact to spongy myocardium is not (except for one tuna species) higher than in other active teleosts. Myocardial aerobic enzyme activity levels are not significantly elevated. The cardiac outputs of spinally blocked skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) are roughly 4 times those of other active teleosts. Ventral aortic blood pressures are the highest among all fishes (more than twice those of rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri), and appear to be due to a high resistance to blood flow in the gills, since dorsal aortic blood pressures are not exceptional. Heart rates, cardiac output, and ventilation volume are high, but gill ventilation and perfusion appear to be well matched (i.e., gill ventilation:perfusion conductance ratios of almost-equal-to 1). Blood hemoglobin concentrations of tunas are elevated, essentially identical with those of humans and twice those seen in other fishes. Because their blood oxygen carrying capacity is high and because skipjack and yellowfin tunas appear to be able to increase the minimum observed arterial to venous oxygen content differnces approximately 3 times, we predict that they need to increase cardiac output only about 2 times during maximum rates of oxygen uptake. This ratio is not very different from those of other teleosts. C1 UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. RP BRILL, RW (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 90 TC 54 Z9 54 U1 1 U2 11 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUL PY 1991 VL 69 IS 7 BP 2002 EP 2009 DI 10.1139/z91-279 PG 8 WC Zoology SC Zoology GA GP060 UT WOS:A1991GP06000040 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI THE STUDY OF MOLECULAR-SPECTROSCOPY BY ABINITIO METHODS SO CHEMICAL REVIEWS LA English DT Review ID DIPOLE-MOMENT FUNCTION; VIBRATIONAL TRANSITION INTENSITIES; SPIN FORBIDDEN TRANSITIONS; COUPLING MATRIX-ELEMENTS; BODY PERTURBATION-THEORY; HERMAN INFRARED SYSTEM; GAUSSIAN-BASIS SETS; RADIATIVE LIFETIME; GROUND-STATE; ELECTRON CORRELATION RP BAUSCHLICHER, CW (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 149 TC 37 Z9 37 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0009-2665 J9 CHEM REV JI Chem. Rev. PD JUL-AUG PY 1991 VL 91 IS 5 BP 701 EP 718 DI 10.1021/cr00005a004 PG 18 WC Chemistry, Multidisciplinary SC Chemistry GA GB059 UT WOS:A1991GB05900005 ER PT J AU ESTABROOK, FB AF ESTABROOK, FB TI LAGRANGIANS FOR RICCI-FLAT GEOMETRIES SO CLASSICAL AND QUANTUM GRAVITY LA English DT Letter ID ENERGY AB The new non-chiral Lagrangian density for the Einstein field equations, which leads to Nester's frames and Hamiltonian formulations in Ashtekar variables, is shown to arise naturally as a canonical 4-form on the second frame bundle, of pure grade 4 in m = 4 Clifford algebra. This insight allows such Lagrangians to be written as easily for higher dimensional theories. RP ESTABROOK, FB (reprint author), CALTECH,JET PROP LAB 169-327,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD JUL PY 1991 VL 8 IS 7 BP L151 EP L154 DI 10.1088/0264-9381/8/7/002 PG 4 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA FV494 UT WOS:A1991FV49400002 ER PT J AU VACCA, JR AF VACCA, JR TI METAVIEWS OPERATIONAL IMAGE MANAGEMENT-SYSTEM - A NEW OPPORTUNITY FOR THE INSURANCE AND BANKING INDUSTRIES SO DOCUMENT & IMAGE AUTOMATION LA English DT Article AB Metaview's Operational Image Management System provides banking and insurance industry users with the ability to scan, store, retrieve, display, print and distribute images of documents such as working documents, handwritten notes, engineering drawings and business forms. Through standard VGA monitors or larger high-resolution monitors, Metaview Cooperative Processing applications present windows that contain images, data and text. The number of windows, as well as the size, location and content, is controlled by the developer. The real power and productivity of Image Management comes when it is integrated with the data processing system into a single solution presented through a single workstation. This is precisely the power and productivity the Metaview system provides for the banking and insurance industry. RP VACCA, JR (reprint author), NASA,SPACE STN FREEDOM PROGRAM OFF,RESTON,VA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PHILIPS BUSINESS INFOR PI POTOMAC PA 1201 SEVEN LOCKS RD, POTOMAC, MD 20854 SN 1071-6130 J9 DOC IMAGE AUTOM PD JUL-AUG PY 1991 VL 11 IS 4 BP 196 EP 207 PG 12 WC Computer Science, Information Systems; Imaging Science & Photographic Technology SC Computer Science; Imaging Science & Photographic Technology GA GF415 UT WOS:A1991GF41500003 ER PT J AU JONES, JH WALKER, D AF JONES, JH WALKER, D TI PARTITIONING OF SIDEROPHILE ELEMENTS IN THE FE-NI-S SYSTEM - 1 BAR TO 80 KBAR SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID SULFUR; CORE AB Partition coefficients for Au, Ni, P and Ge between solid Fe-Ni metal and sulfur-bearing metallic liquids have been measured at 7, 27 and 80 kbar. To our knowledge, these are the only such data for Au, P and Ge at high pressure. Comparison of our partitioning results to those obtained at 1 bar indicate that only the 80 kbar Ge data differ significantly from the 1-bar experiments. Thus, many low-pressure partitioning experiments in the Fe-Ni-S-P system may have applicability to the greater portion of the Earth's upper mantle or, alternatively, the entire mantle of Mars. C1 COLUMBIA UNIV,DEPT GEOL SCI,PALISADES,NY 10964. COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. RP JONES, JH (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN2,HOUSTON,TX 77058, USA. NR 14 TC 35 Z9 35 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JUL PY 1991 VL 105 IS 1-3 BP 127 EP 133 DI 10.1016/0012-821X(91)90125-2 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA GD519 UT WOS:A1991GD51900010 ER PT J AU SMITH, MK KOSTLAN, E AF SMITH, MK KOSTLAN, E TI ESTIMATES OF AGE AND GROWTH OF EHU ETELIS-CARBUNCULUS IN 4 REGIONS OF THE PACIFIC FROM DENSITY OF DAILY INCREMENTS IN OTOLITHS SO FISHERY BULLETIN LA English DT Article ID PRISTIPOMOIDES-FILAMENTOSUS; HAWAIIAN SNAPPER; LARVAL; STOCKS; WATERS; FISH AB Growth of the deep slope snapper Etelis carbunculus was evaluated from the density of daily increments in sagittal otoliths collected from Hawaii, the Commonwealth of the Northern Marianas Islands (NMI), French Polynesia, and Vanuatu. The rate of otolith growth (mu-m/day) as a function of otolith radius was fit by regression to a modified Gompertz rate curve and the age of fish estimated by integrating the equation. There were slight regional differences between the estimated values of each of the three otolith growth rate parameters, which may be attributable in part to random sampling differences. However, integrated estimates of fish age versus otolith radius varied little between sites because of the compensatory relationship between two of the three estimated parameters which together determine the rate of dampening of the otolith growth function. There were significant regional differences in average otolith radius, and thus in estimated age, as a function of fish length. Fish from Vanuatu and NMI were younger at a given length than those from the other two regions. However, fish as large as those at Vanuatu are not found at NMI, suggesting there may be regional differences in mortality. Regional age-at-length data were fit to a von Bertalanffy growth curve, both unconstrained and held to a value of asymptotic length (L infinity) obtained from the literature. Estimates of natural mortality for each region are discussed, based on the regional values obtained for the von Bertalanffy growth constant (K). These results should be confirmed using data obtained from a wider range of fish sizes. C1 NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. UNIV HAWAII,DEPT MATH,HONOLULU,HI 96822. NR 47 TC 29 Z9 29 U1 0 U2 1 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 JUL PY 1991 VL 89 IS 3 BP 461 EP 472 PG 12 WC Fisheries SC Fisheries GA GE375 UT WOS:A1991GE37500010 ER PT J AU STEHLIK, LL MACKENZIE, CL MORSE, WW AF STEHLIK, LL MACKENZIE, CL MORSE, WW TI DISTRIBUTION AND ABUNDANCE OF 4 BRACHYURAN CRABS ON THE NORTHWEST ATLANTIC SHELF SO FISHERY BULLETIN LA English DT Article ID CANCER-IRRORATUS-SAY; ROCK CRAB; SEASONAL COMPOSITION; UNITED-STATES; BIOLOGY; BIGHT; REPRODUCTION; DECAPODA AB Seasonal distributions and relative abundances of the Atlantic rock crab Cancer irroratus, Jonah crab C. borealis, northern lady crab Ovalipes ocellatus, and coarsehand lady crab O. stephensoni were determined from fish trawl and clam dredge surveys on the continental shelf from Nova Scotia to Cape Hatteras, North Carolina during 1978-87. Rock crabs have the broadest distribution, which includes coastal waters of the Gulf of Maine and depths of 6-456 m from Georges Bank to Cape Hatteras. Jonah crabs are more widely distributed in the Gulf of Maine and on Georges Bank than rock crabs. They occur most frequently in the northern and offshore zones of the middle Atlantic from south of Georges Bank to off Delaware, at depths to over 400 m. Northern lady crabs occur primarily in the inner strata of the middle-Atlantic shelf in depths < 27 m, and on shallower portions of Georges Bank. Coarsehand lady crabs occur from southern New Jersey to Cape Hatteras, to over 200 m. Cancer spp. occur mainly at 3-18-degrees-C, while Ovalipes spp. occur mainly at 11-24-degrees-C. Sex ratios in rock and Jonah crab catches deviated from 1:1 by season and gear; males dominate in spring trawl surveys, females in summer dredge and fall trawl surveys. Trawl catches of all species were significantly larger at night or twilight than during the day, suggesting more nocturnal activity. Temperature, depth, and their interaction significantly affected the catches of these crabs. RP STEHLIK, LL (reprint author), NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 38 TC 28 Z9 30 U1 1 U2 6 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 JUL PY 1991 VL 89 IS 3 BP 473 EP 492 PG 20 WC Fisheries SC Fisheries GA GE375 UT WOS:A1991GE37500011 ER PT J AU YUAN, XQ WADE, CE AF YUAN, XQ WADE, CE TI NEUROENDOCRINE ABNORMALITIES IN PATIENTS WITH TRAUMATIC BRAIN INJURY SO FRONTIERS IN NEUROENDOCRINOLOGY LA English DT Review DE BRAIN TRAUMA; HEAD INJURIES; HYPOTHALAMUS; PITUITARY; HORMONES; NEUROENDOCRINOLOGY ID CORTICOTROPIN-RELEASING FACTOR; INSULIN-INDUCED HYPOGLYCEMIA; TRANSIENT HYPOGONADOTROPIC HYPOGONADISM; ANTIDIURETIC-HORMONE SECRETION; FOLLICLE-STIMULATING-HORMONE; ATRIAL-NATRIURETIC-PEPTIDE; PEDIATRIC HEAD-INJURY; GROWTH-HORMONE; DIABETES-INSIPIDUS; LUTEINIZING-HORMONE AB This article provides an overview of hypothalamic and pituitary alterations in brain trauma, including the incidence of hypothalamic-pituitary damage, injury mechanisms, features of the hypothalamic-pituitary defects, and major hypothalamic-pituitary disturbances in brain trauma. While hypothalamic-pituitary lesions have been commonly described at postmortem examination, only a limited number of clinical cases of traumatic hypothalamic-pituitary dysfunction have been reported, probably because head injury of sufficient severity to cause hypothalamic and pituitary damage usually leads to early death. With the improvement in rescue measures, an increasing number of severely head-injured patients with hypothalamic-pituitary dysfunction will survive to be seen by clinicians. Patterns of endocrine abnormalities following brain trauma vary depending on whether the injury site is in the hypothalamus, the anterior or posterior pituitary, or the upper or lower portion of the pituitary stalk. Injury predominantly to the hypothalamus can produce dissociated ACTH-cortisol levels with no response to insulin-induced hypoglycemia and a limited or failed metopirone test, hypothyroxinemia with a preserved thyroid-stimulating hormone response to thyrotropin-releasing hormone, low gonadotropin levels with a normal response to gonadotropin-releasing hormone, a variable growth hormone (GH) level with a paradoxical rise in GH after glucose loading, hyperprolactinemia, the syndrome of inappropriate ADH secretion (SIADH), temporary or permanent diabetes insipidus (DI), disturbed glucose metabolism, and loss of body temperature control. Severe damage to the lower pituitary stalk or anterior lobe can cause low basal levels of all anterior pituitary hormones and eliminate responses to their releasing factors. Only a few cases showed typical features of hypothalamic or pituitary dysfunction. Most severe injuries are sufficient to damage both structures and produce a mixed endocrine picture. Increased intracranial pressure, which releases vasopressin by altering normal hypothalamic anatomy, may represent a unique type of stress to neuroendocrine systems and may contribute to adrenal secretion by a mechanism that requires intact brainstem function. Endocrine function should be monitored in brain-injured patients with basilar skull fractures and protracted posttraumatic amnesia, and patients with SIADH or DI should be closely monitored for other endocrine abnormalities. C1 LETTERMAN ARMY INST RES,DIV MIL TRAUMA RES,PRESIDIO SAN FRANCISCO,SAN FRANCISCO,CA 94129. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 181 TC 50 Z9 57 U1 1 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0091-3022 J9 FRONT NEUROENDOCRIN JI Front. Neuroendocrinol. PD JUL PY 1991 VL 12 IS 3 BP 209 EP 230 PG 22 WC Endocrinology & Metabolism; Neurosciences SC Endocrinology & Metabolism; Neurosciences & Neurology GA GB852 UT WOS:A1991GB85200001 PM 11538874 ER PT J AU RAGHAVARAO, R WHARTON, LE SPENCER, NW MAYR, HG BRACE, LH AF RAGHAVARAO, R WHARTON, LE SPENCER, NW MAYR, HG BRACE, LH TI AN EQUATORIAL TEMPERATURE AND WIND ANOMALY (ETWA) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NEUTRAL WINDS AB Data obtained from the WATS (Wind and Temperature Spectrometer) and LP (Langmuir Probe) experiments on board DE-2 (Dynamic Explorer) during high solar activity show evidence of anomalous latitudinal variations in the zonal winds and temperature at low latitudes. The zonal winds exhibit a broad maximum centered around the dip equator, flanked by minima on either side around 25 degrees; while the temperature exhibits a pronounced bowl-shaped minimum at the dip equator which is flanked by maxima. The two minima in the zonal winds and the corresponding maxima in the temperature are nearly collocated with the crests of the well known Equatorial Ionization Anomaly (EIA). The maximum in the zonal winds and the minimum in the gas temperature are collocated with the trough of the EIA. The differences between the maxima and minima in temperature and zonal winds, on many occasions, are observed to exceed 100 K and 100 m/s, respectively. The characteristics of this new phenomenon have eluded present day empirical models of thermospheric temperature and winds. The connection among these variables can be understood from the ion-neutral drag effect on the motions of the neutrals that in turn affect their energy balance. RP RAGHAVARAO, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERE BRANCH,CODE 914,GREENBELT,MD 20771, USA. NR 15 TC 72 Z9 73 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 JUL PY 1991 VL 18 IS 7 BP 1193 EP 1196 DI 10.1029/91GL01561 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FW155 UT WOS:A1991FW15500006 ER PT J AU MLYNCZAK, MG SOLOMON, S AF MLYNCZAK, MG SOLOMON, S TI ON THE EFFICIENCY OF SOLAR HEATING IN THE MIDDLE ATMOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MESOSPHERE EXPLORER; LOWER THERMOSPHERE; OZONE; ABSORPTION; O2 AB We calculate the efficiency at which solar ultraviolet radiation absorbed in the Hartley band of ozone is directly converted to heat in the terrestrial mesosphere and lower thermosphere (50-110 km). The ozone molecule undergoes photolysis to yield the excited species O(1D) and O2(1-DELTA) with a quantum yield of about 0.9. Spontaneous emission from O2(1-DELTA) and from O2(1-SIGMA) (excited by energy transfer from O(1D)) significantly decreases the amount of energy available for heat. Similarly, we calculate the efficiency at which solar ultraviolet radiation absorbed by O2 in the Schumann-Runge continuum is directly converted to heat in the lower thermosphere (95-110 km). The O2 undergoes photolysis and the excited product O(1D) is generated. Spontaneous emission from O2(1-SIGMA) (excited by energy transfer from O(1D)) reduces the amount of energy available for heat in the lower thermosphere. The consideration of these energy transfer and loss processes results in significantly reduced heating rates as compared to those conventionally calculated in models of the middle atmosphere. 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 16 TC 24 Z9 24 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL PY 1991 VL 18 IS 7 BP 1201 EP 1204 DI 10.1029/91GL01525 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FW155 UT WOS:A1991FW15500008 ER PT J AU TOUMI, R PYLE, JA WEBSTER, CR MAY, RD AF TOUMI, R PYLE, JA WEBSTER, CR MAY, RD TI THEORETICAL INTERPRETATION OF N2O5 MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC N2O5; SPACELAB-3; O-3 AB Recent measurements by Webster et al. [1990] have confirmed quantitatively the chemistry controlling the night-time decay of NO2. Simple equations describing the night-time behaviour of NO2 and N2O5 are presented here. With measurements of the night-time ozone and NO2 concentrations, these equations can be used to predict the amount of N2O5 produced at any time during the night. In this way the N2O5 night-time emission measurement of Roscoe [1982], Kunde et al. [1988] and sunrise measurements of the ATMOS experiment [Rinsland et al., 1989] are all used to test theory. The measurements are found to be both self consistent and confirm our understanding of night-time NO2 conversion to N2O5. The variation of N2O5 by a factor of two between measurements is found to be consistent with theory. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TOUMI, R (reprint author), UNIV CAMBRIDGE,DEPT CHEM,LENSFIELD RD,CAMBRIDGE CB3 0ET,ENGLAND. NR 17 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL PY 1991 VL 18 IS 7 BP 1213 EP 1216 DI 10.1029/90GL01319 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FW155 UT WOS:A1991FW15500011 ER PT J AU GLAZE, LS SELF, S AF GLAZE, LS SELF, S TI ASHFALL DISPERSAL FOR THE 16 SEPTEMBER 1986, ERUPTION OF LASCAR, CHILE, CALCULATED BY A TURBULENT-DIFFUSION MODEL SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TEPHRA AB A two dimensional model for the dispersal of volcanic ash, modified from that of Suzuki [1983], is applied to the 16 September 1986, eruption of Lascar, in northern Chile. The result is an isopach map predicting ground concentrations of ash. The map shows two local maxima along distinct dispersal axes and predicts that the deposit was detached from the source. Predicted concentrations are in agreement with a single reported thickness measurement. C1 UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,DEPT GEOL & GEOPHYS,HONOLULU,HI 96822. RP GLAZE, LS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 183-501,PASADENA,CA 91109, USA. RI Glaze, Lori/D-1314-2012 NR 17 TC 37 Z9 38 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 JUL PY 1991 VL 18 IS 7 BP 1237 EP 1240 DI 10.1029/91GL01501 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FW155 UT WOS:A1991FW15500017 ER PT J AU TRALLI, DM AF TRALLI, DM TI SPECTRAL COMPARISON OF CONTINUOUS GLOBAL POSITIONING SYSTEM AND STRAINMETER MEASUREMENTS OF CRUSTAL DEFORMATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PHASE AMBIGUITY RESOLUTION; RADIO INTERFEROMETRY; GEODETIC BASELINES; CALIFORNIA AB Temporal power spectral density models of noise in continuous crustal deformation measurements obtained with the Global Positioning System (GPS) and high-quality strainmeters are compared. The crossover frequency at which GPS measurement noise is less than that of strainmeters is determined. Assuming GPS precision of 0.1 to 1 cm in horizontal components for baselines up to 100 km in length, local deformation monitoring with GPS may be preferable to strainmeters for observations of short-term deformation in under 6 months of continuous (at least daily) measurements. Short-period tropospheric path delays and multipath effects, which may obscure GPS-determined strain signals in local network measurements, also are discussed. RP TRALLI, DM (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 25 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 JUL PY 1991 VL 18 IS 7 BP 1285 EP 1288 DI 10.1029/91GL01184 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FW155 UT WOS:A1991FW15500029 ER PT J AU ROSSOW, WB AF ROSSOW, WB TI USE OF OPERATIONAL SATELLITE DATA FOR STUDY OF CLOUDS AND RADIATION IN CLIMATE SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE ID ISCCP AB A brief summary is given of early results from the analysis of operational satellite data for the International Satellite Cloud Climatology Project. These data appear useful for studying the role that clouds play in determining the climate and its variations. RP ROSSOW, WB (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI Rossow, William/F-3138-2015 NR 9 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 33 EP 39 PG 7 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900006 ER PT J AU CHESTERS, D NEUENDORFFER, A AF CHESTERS, D NEUENDORFFER, A TI COMPARISON BETWEEN TOMS, TOVS AND DOBSON OBSERVATIONS - SATELLITE AND SURFACE VIEWS OF TOTAL COLUMN OZONE SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE AB TOVS infrared and microwave observations are now being used to estimate total column ozone over the globe by employing a new physical retrieval algorithm. The TOVS archives from 1979 to the present have been reprocessed, and the results during the great Antarctic "ozone hole" of 1987 are compared with the corresponding TOMS and DOBSON ultraviolet observations of total ozone. The TOVS total ozone patterns appear to be reliable on the synoptic scale and provide a unique opportunity to track ozone variations during polar night. However, there are times and places where each of the three ozone datasets contains errors that are significantly larger than a few percent. C1 NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,NOAA,PHYS BRANCH,HILLCREST HTS,MD 20274. RP CHESTERS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GODDARD LAB ATMOSPHERES,GREENBELT,MD 20771, USA. NR 14 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 61 EP 67 PG 7 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900010 ER PT J AU CHANDRA, S MCPETERS, RD HUDSON, RD PLANET, W AF CHANDRA, S MCPETERS, RD HUDSON, RD PLANET, W TI OZONE MEASUREMENTS FROM THE NOAA-9 AND THE NIMBUS-7 SATELLITES - IMPLICATIONS OF SHORT AND LONG-TERM VARIABILITIES SO GLOBAL AND PLANETARY CHANGE LA English DT Meeting Abstract C1 NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,WASHINGTON,DC 20233. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Hudson, Robert/F-4506-2010; McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 0 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 73 EP 73 PG 1 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900012 ER PT J AU ADLER, RF NEGRI, AJ HAKKARINEN, IM AF ADLER, RF NEGRI, AJ HAKKARINEN, IM TI RAIN ESTIMATION FROM COMBINING GEOSYNCHRONOUS IR AND LOW-ORBIT MICROWAVE DATA SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE AB This paper describes a method to combine geosynchronous infrared (IR) and low-orbit microwave data to estimate rainfall, including mean monthly rainfall useful for climate studies. The IR data have the advantage of high time resolution (important for rapidly changing precipitation patterns and for the detection of diurnal signals), but lack a strong physical connection between the remotely sensed signal and the surface rainfall. The microwave data provide a stronger relation between the radiance and the rainfall, but provide poor sampling of the rainfall signal. Initially the estimates are computed separately using hourly IR data from the Japanese GMS geosynchronous satellite and microwave data from the SSM/I instrument on board the DMSP satellite. Calibration or adjustment factors are derived by dividing the microwave monthly estimate by a second IR estimate (made with the microwave sampling). The spatial array of coefficients are then multiplied by the original IR monthly estimates (produced from all the hourly data) to produce the merged IR/microwave monthly estimates. C1 GEN SCI CORP,LAUREL,MD 20707. RP ADLER, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 2 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 87 EP 92 PG 6 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900015 ER PT J AU SPENCER, RW CHRISTY, JR GRODY, NC AF SPENCER, RW CHRISTY, JR GRODY, NC TI PRECISION TROPOSPHERIC TEMPERATURE MONITORING 1979-1990 SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE AB The TIROS-N microwave sounding units (MSU's) have demonstrated an ability to measure globally averaged tropospheric brightness temperature anomalies to a precision of 0.01-degrees-C per month. This has been revealed by five separate overlap periods of concurrently operating morning and afternoon satellites. For MSU channel 2, comparisons to ten years of radiosonde data show that these anomalies are closely related to anomalies in 850-300 mbar thickness, with gridpoint correlations to radiosondes usually ranging between 0.85 and 0.95. The comparisons also suggest that there is no drift or bias in the MSU's (or US-controlled radiosonde system) between 1979-1988 to about 0.01-degrees-C when results are averaged over the Pacific or Caribbean. The non-trivial amount of lower stratospheric influence on MSU channel 2, combined with evidence for cooling in that layer during 1979-1990, suggests the need for removal of this effect from the measurements before interpretation in terms of a "tropospheric" temperature. Because the NOAA-6 MSU channel 3 was not usable for precision climate monitoring due to a sizeable drift, we have performed a retrieval on MSU channel 2 at different view angles to achieve stratospheric cancellation. We present global brightness temperature anomalies of both raw channel 2 and the tropospheric retrieval for the period 1979-1990. It appears that the MSU's (and presumably the advanced microwave sounding units as well) will provide a valuable resource for not only monitoring intraseasonal to interannual climate change, but also for long-term monitoring of potential global warming. C1 NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,WASHINGTON,DC 20233. UNIV ALABAMA,JOHNSON RES CTR,HUNTSVILLE,AL 35899. RP SPENCER, RW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES43,HUNTSVILLE,AL 35812, USA. NR 2 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 113 EP 120 PG 8 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900019 ER PT J AU CHAHINE, MT SUSSKIND, J AF CHAHINE, MT SUSSKIND, J TI DERIVATION OF LONG-TERM CLIMATE DATA SETS FROM NOAAS HIRS2 MSU SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE ID PARAMETERS AB Accurate long-term global data sets are essential for achieving better understanding of the Earth's climate system and for modelling its complex interactions and feedback mechanisms. The High Resolution Infrared Sounder and the Microwave Sounding Unit (HIRS2/MSU) observations readily offer a unique opportunity to establish a global self-consistent data set of more than ten climate parameters extending over a decade in time. Such a data set would add considerably to our current information. To this end, we have developed and tested a retrieval package to extract geophysical parameters from the combination of infrared and microwave data returned since December 1978 from the NOAA weather satellites. The retrieval algorithm is an interactive forecast-retrieval-assimilation system based on the relaxation method of solution of the radiative transfer equation. The first guess is obtained from the six-hour forecast field generated by the General Circulation Model (GCM) of the Goddard Laboratory for Atmospheres. At present we have applied the algorithm to analyze the first two years of HIRS2/MSU data. The resulting climate data sets include: atmospheric temperature profiles, atmospheric humidity profiles, ocean surface temperature, land surface temperature, infrared cloud cover, cloud-top height and temperature, snow and ice cover, outgoing long-wave radiation, total ozone distribution, and rainfall rate index. We have conducted several tests to check the accuracy, internal consistency and stability of the results. Additional tests will be made in the future with this set as well as when multi-year data are derived. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CHAHINE, MT (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 121 EP 125 PG 5 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900020 ER PT J AU SHENK, WE AF SHENK, WE TI SUGGESTIONS FOR IMPROVING THE DERIVATION OF WINDS FROM GEOSYNCHRONOUS SATELLITES SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE ID CLOUD AB For more than the past two decades and for the foreseeable future measurements from geosynchronous satellites will be a major contributor to the determination of winds, especially over oceanic areas. The winds can be determined from features (e.g. clouds) that closely follow the air motion, and from the thermal wind relationship poleward of the tropics. Major improvements in accuracy and coverage should be possible during the coming decades through the combination of better sensors and their operation and the increased use of interactive systems. These data could contribute significantly to a long-term wind data base associated with global change studies. RP SHENK, WE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SEVERE STORMS BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 165 EP 171 PG 7 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900026 ER PT J AU BREST, CL AF BREST, CL TI INDIRECT CALIBRATION OF VISIBLE CHANNEL DATA SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE ID ABSOLUTE CALIBRATION; IN-FLIGHT; SENSORS; AVHRR AB To provide quantitative measurements for Earth studies accurate and comprehensive calibration of satellite radiometers is critically needed. The recent increase in the use of satellite data for climate studies calls for the retrieval of physical parameters from the measured radiances and therefore for absolute calibrations that are known over long time periods. However, even the use of classification or "index" type analyses of satellite data to monitor changes in climate requires that the relative stability of the satellite radiometers be known for long-term data sets. Moreover, plans to collect global satellite data over decadal periods, to monitor changes in surface conditions and in climate, require a calibration standard that can be transferred from one satellite to another in a series. Although most instruments undergo a thorough calibration prior to their launch on a satellite, there appears to be no predictable relationship between these pre-launch calibrations and the post-launch performance. Thus, comprehensive, well-documented post-launch calibrations are needed. Because the solar channels used for imaging on most operational satellites do not have onboard calibration capabilities, a number of indirect approaches have been developed using the Earths surface as a target. A variety of earth targets have been used in calibration ranging from a single target (such as White Sands, NM) to multiple targets covering the entire globe. The use of such targets to monitor the relative calibration of satellite instruments over long time periods introduces a number of uncertainties such as diurnal and seasonal changes in the radiation from the target as seen by the satellite. These temporal changes arise from variations in viewing and illumination geometry, changes in the atmosphere, navigation errors, changes in the surface characteristics (such as soil moisture and vegetation), and cloud variations. Relative calibration methods require periodic absolute calibration checks. There is a demonstrated need for routine aircraft calibration flights to validate the various approaches. RP BREST, CL (reprint author), NASA,ST SYST CORP,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 21 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 271 EP 277 PG 7 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900044 ER PT J AU WILSON, GS HUNTRESS, WT AF WILSON, GS HUNTRESS, WT TI MISSION TO PLANET EARTH SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT CONF ON OPERATIONAL SATELLITES : SENTINELS FOR THE MONITORING OF CLIMATE AND GLOBAL CHANGE CY OCT 16-19, 1990 CL WASHINGTON, DC SP NATL OCEAN & ATMOSPHER ADMIN, US DEPT COMMERCE AB On July 20, 1989, the President of the United States presented his vision of NASA's future: the Earth, Moon, and Mars beckon as targets for understanding and future exploration. The goals have been set, but much remains to be done in setting priorities, budgets, and timetables. There are many demands on every Federal dollar, and tough choices will have to be made. The key to a dynamic space program is maintaining balance between today's concerns and tomorrow's dividends-a balance between budgetary limitations and the inherent human quest to move on, to grow, and to learn. There are advocates for manned and unmanned programs, exploration, and commercialization. The challenge is not to pick among them, but rather to construct a comprehensive long-term plan, and to devise missions contributing to a balanced program. A mission can serve several goals, and NASA's strength is enhanced by pursuing a variety of objectives. Supporting Earth science research is an intrinsic part of NASA's mandate, and is established within the Agency's authorizing legislation. That legislation directs NASA to carry out a broad range of environmental observations and scientific investigations to learn the physics, chemistry, and biology of this planet. The Administration's objectives for NASA include advancing Earth science research as one of the three fundamental goals of the U.S. Space Program, as stated below: (1) To advance U.S. scientific leadership and the world's scientific knowledge of the solar system and the universe. (2) To advance the role of man in space and preserve U.S. preeminence in critical aspects of manned space flight. (3) To advance scientific knowledge of the Earth and its environment so as to understand and eventually predict both natural and human-induced global change and, thus, provide continuing benefits to humanity. Milestones include - Establishing a set of observing platforms of various sizes and capabilities to study the Earth system from space on a global scale and on a continuing basis. - Developing plans and options, in coordination with other appropriate Federal agency members of the Committee on Earth Sciences, to implement..."Mission to Planet Earth." Mission to Planet Earth will produce the understanding needed to predict changes in the Earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic Earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the Earth and how it works as a system. Increased understanding of the Earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. The resulting technology and science will contribute to future solar system exploration as well. C1 NASA,DIV SOLAR SYST EXPLORAT,WASHINGTON,DC 20546. RP WILSON, GS (reprint author), NASA,DIV EARTH SCI & APPLICAT,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD JUL PY 1991 VL 90 IS 1-3 BP 317 EP 328 PG 12 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA GD079 UT WOS:A1991GD07900052 ER PT J AU SRIDHAR, B SUORSA, R AF SRIDHAR, B SUORSA, R TI COMPARISON OF MOTION AND STEREO METHODS IN PASSIVE RANGING SYSTEMS SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Letter RP SRIDHAR, B (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 6 TC 15 Z9 16 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1991 VL 27 IS 4 BP 741 EP 746 DI 10.1109/7.85049 PG 6 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GB874 UT WOS:A1991GB87400018 ER PT J AU ROCHBLATT, DJ RAHMATSAMII, Y AF ROCHBLATT, DJ RAHMATSAMII, Y TI EFFECTS OF MEASUREMENT ERRORS ON MICROWAVE ANTENNA HOLOGRAPHY SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID REFLECTOR AB The application of microwave holographic metrology has received much attention in recent years. The technique has been successfully used in improving the performance of many types of reflector and array antennas throughout the world. In order to properly assess the ultimate achievable holographic performance improvements, attention must be focused on detailed system error evaluation. In this paper, the effects of measurement errors appearing during the implementation of the microwave holographic technique are investigated and many representative results are presented based on computer simulations. The numerical results are tailored for cases applicable to the utilization of the holographic technique for the NASA's Deep Space Network (DSN) antennas, although the methodology of analysis is applicable to any antenna. Many important system measurement topics are presented and summarized. C1 UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024. RP ROCHBLATT, DJ (reprint author), CALTECH,JET PROP LAB,IMAGING TEAM,PASADENA,CA 91109, USA. NR 15 TC 6 Z9 6 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 JUL PY 1991 VL 39 IS 7 BP 933 EP 942 DI 10.1109/8.86912 PG 10 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FZ277 UT WOS:A1991FZ27700009 ER PT J AU GEARHART, SS LING, CC REBEIZ, GM AF GEARHART, SS LING, CC REBEIZ, GM TI INTEGRATED MILLIMETER-WAVE CORNER-CUBE ANTENNAS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID OPEN STRUCTURE MIXER AB An integrated corner-reflector antenna has been designed, fabricated and measured at millimeter-wave frequencies. The structure consists of a travelling-wave antenna integrated on a 1.2-mu-m dielectric membrane and suspended in a longitudinal cavity etched in a silicon wafer. A new traveling wave antenna design, the modified-bend antenna, with an antenna length of L = 1.2-lambda and spacing d = 0.96-lambda from the apex, results in a wide-band input impedance centered at 140 OMEGA and low cross-polarization levels. Measurements at 180-270 GHz show a well defined pattern with low sidelobe levels and a main-beam efficiency of 93 and 83% at 180 and 222 GHz, respectively. The monolithic approach allows the integration of a matching network and a Schottky-diode or SIS detector at the base of the antenna to yield a low-noise monolithic millimeter-wave receiver. RP GEARHART, SS (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 17 TC 5 Z9 5 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD JUL PY 1991 VL 39 IS 7 BP 1000 EP 1006 DI 10.1109/8.86921 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FZ277 UT WOS:A1991FZ27700018 ER PT J AU GALINDOISRAEL, V RENGARAJAN, SR IMBRIALE, WA MITTRA, R AF GALINDOISRAEL, V RENGARAJAN, SR IMBRIALE, WA MITTRA, R TI OFFSET DUAL-SHAPED REFLECTORS FOR DUAL CHAMBER COMPACT RANGES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID ANTENNAS AB The application of the theory of the synthesis of offset dual-shaped reflectors to the design of compact ranges is examined. The object of the compact range is to provide a uniform plane wave with minimum amplitude and phase ripple over as large a volume as possible for a given size reflector. Ripple can be lowered by reducing the edge diffraction from the reflector producing the plane wave. This has been done either by serrating or rolling the edge. An alternative approach is to use dual offset-shaped reflector synthesis techniques to produce a reflector aperture distribution that is uniform over most of the aperture but has a Gaussian taper near the edge. This approach can be used together with rolling and/or serration if desirable. The dual chamber method for reducing extraneous subreflector diffraction can be used and is examined herein. The amount of phase and amplitude ripple obtained with two different dual-shaped reflector designs is studied as a function of position in the plane wave zone and reflector size in wavelengths. The amount of both transverse and longitudinal (z-component) cross polarization is studied. The dual-shaped offset reflector design is found to be an excellent candidate for a compact range. C1 UNIV ILLINOIS,DEPT ELECT & COMP ENGN,ELECTROMAGNET COMMUN LAB,URBANA,IL 61801. CALIF STATE UNIV NORTHRIDGE,DEPT ELECT & COMP ENGN,NORTHRIDGE,CA 91330. RP GALINDOISRAEL, V (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 8 Z9 8 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 JUL PY 1991 VL 39 IS 7 BP 1007 EP 1013 DI 10.1109/74.107350 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FZ277 UT WOS:A1991FZ27700019 ER PT J AU HUANG, J DENSMORE, AC AF HUANG, J DENSMORE, AC TI MICROSTRIP YAGI ARRAY ANTENNA FOR MOBILE SATELLITE VEHICLE APPLICATION SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB A new antenna structure is formed by combining the Yagi-Uda array concept and the microstrip radiator technique. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction to provide optimum coverage for Continental U.S. users. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit, while still contributing to achieve the MSAT required antenna gain, the antenna becomes a very efficient radiating system. With the complete monopulse beam-forming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle's rooftop mounting, as well as a low manufacturing cost. Experimental results are presented to demonstrate the excellent performance of this microstrip Yagi antenna. RP HUANG, J (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 96 Z9 97 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD JUL PY 1991 VL 39 IS 7 BP 1024 EP 1030 DI 10.1109/8.86924 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FZ277 UT WOS:A1991FZ27700021 ER PT J AU ONYSZCHUK, IM AF ONYSZCHUK, IM TI TRUNCATION LENGTH FOR VITERBI DECODING SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Letter ID CONVOLUTIONAL-CODES AB A bound is derived and analyzed for the bit error rate (BER) of a Viterbi decoder with survivor truncation. Estimates of the SNR loss on the AWGN channel, due to truncation are obtained for convolutional codes. Larger truncation lengths are required than the smallest value that does not effectively decrease the code's free distance, especially at low E(b)/N0. RP ONYSZCHUK, IM (reprint author), CALTECH,JET PROP LAB,MS 238-420,PASADENA,CA 91109, USA. NR 7 TC 22 Z9 23 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD JUL PY 1991 VL 39 IS 7 BP 1023 EP 1026 DI 10.1109/26.87203 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA GC639 UT WOS:A1991GC63900001 ER PT J AU SMITH, JA LANG, RH AF SMITH, JA LANG, RH TI SPECIAL ISSUE ON THE 1990 INTERNATIONAL GEOSCIENCE AND REMOTE-SENSING SYMPOSIUM (IGARSS 90) - REMOTE-SENSING SCIENCE FOR THE NINETIES - FOREWORD SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article C1 GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052. RP SMITH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 0 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1991 VL 29 IS 4 BP 479 EP 480 PG 2 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA FX027 UT WOS:A1991FX02700001 ER PT J AU LUTZ, R WILHEIT, TT WANG, JR KAKAR, RK AF LUTZ, R WILHEIT, TT WANG, JR KAKAR, RK TI RETRIEVAL OF ATMOSPHERIC WATER-VAPOR PROFILES USING RADIOMETRIC MEASUREMENTS AT 183 AND 90 GHZ SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID MICROWAVE RADIOMETRY; MOISTURE PROFILES; CLEAR AB Some algorithms utilizing the strong 183.3-GHz water vapor absorption line have been developed for the retrieval of atmospheric water vapor profiles in the past decade [1]-[6]. The one developed by Wilheit [6] dealt with the retrieval of water vapor profiles from the microwave radiometric measurements, even in the presence of clouds. This algorithm was tested with the radiometric measurements near 90 and 183 GHz frequencies and the results are presented in this paper. It was shown that the retrieved water vapor profiles were in general agreement with those derived from the radiosonde data. In particular, the retrieval over both land and ocean surfaces generated clouds at locations that could be verified from satellite photographs. The algorithm did not perform well at places where there were surface fronts. These clouds possibly contained ice particles as well as precipitating snow which the algorithm was not expected to handle. The results of this study will be discussed in light of future satellite programs such as the AMSU (Advanced Microwave Sounding Unit). C1 TEXAS A&M UNIV SYST,TEXAS AGR EXPT STN,DEPT METEOROL,COLLEGE STN,TX 77843. NASA,WASHINGTON,DC 20546. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LUTZ, R (reprint author), ST SYST CORP,440 FORBES BLVD,LANHAM,MD 20706, USA. RI Wilheit, Thomas/G-9438-2012 NR 12 TC 15 Z9 15 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1991 VL 29 IS 4 BP 602 EP 609 DI 10.1109/36.135822 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA FX027 UT WOS:A1991FX02700014 ER PT J AU CHAUHAN, NS LANG, RH RANSON, KJ AF CHAUHAN, NS LANG, RH RANSON, KJ TI RADAR MODELING OF A BOREAL FOREST SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE FOREST; GROUND TRUTH AND CANOPY GEOMETRY DATA; MODEL BACKSCATTERING COEFFICIENT; SYNTHETIC APERTURE RADAR DATA ID L-BAND; ELECTROMAGNETIC SCATTERING; ATTENUATION OBSERVATIONS; MICROWAVE SCATTEROMETER; ANGLE DISTRIBUTIONS; FINITE LENGTH; BACKSCATTERING; VEGETATION; STANDS; PROPAGATION AB A mixed coniferous forest stand located near Howland, Maine, has been modeled at SAR frequencies (P-, L-, and C-bands). A NASA/JPL multiple-view angle, multiple-frequency SAR was flown aboard a DC-8 aircraft on September 2, 1989. The extensive measurements of ground truth and canopy geometry parameters were performed in a 200 m-square hemlock-dominated plot inside the forest. About 10% of the trees were sampled to determine a distribution of diameter at breast height (DBH). Four representative hemlock trees with a DBH equal to 6, 12, 21.9, and 30.2 cm were destructively sampled to obtain the tree architectural and biomass data of the forest. Hemlock trees in the forest are modeled by characterizing tree trunks, branches, and needles (leaves) with randomly oriented, lossy dielectric cylinders whose area and orientation distributions are prescribed. The distorted Born approximation is used to compute the backscatter at P-, L-, and C-SAR frequencies. The input parameters to the model are determined from the analysis of ground truth and tree architectural data gathered from the experiment site. Comparison of theory results with calibrated data show that the model values are lower than the data. The experiment and model results agree quite closely, however, when the ratio of VV to HH and HV to HH are compared. C1 NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RP CHAUHAN, NS (reprint author), GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052, USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 34 TC 106 Z9 109 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1991 VL 29 IS 4 BP 627 EP 638 DI 10.1109/36.135825 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA FX027 UT WOS:A1991FX02700017 ER PT J AU HALYO, N DIRESKENELI, H BARKSTROM, BR AF HALYO, N DIRESKENELI, H BARKSTROM, BR TI AN INFORMATION-THEORY APPROACH FOR EVALUATING EARTH RADIATION BUDGET (ERB) MEASUREMENTS - NONUNIFORM SAMPLING OF DIURNAL LONGWAVE FLUX VARIATIONS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB Current satellite measurements are subject to a wide range of uncertainties due to their temporal, spatial, and directional sampling characteristics. An information theory approach is suggested to examine the nonuniform temporal sampling of ERB (Earth Radiation Budget) measurements. The information (i.e., the entropy or uncertainty) before and after the measurements is determined and the information gain is defined as a reduction in the uncertainties involved. A stochastic model for the diurnal outgoing flux variations that affect the ERB is developed. Using Gaussian distributions for the a priori and measured radiant exitance fields, the information gain is obtained by computing the a posteriori covariance. The information gain for the monthly outgoing flux measurements is examined for different orbital parameters and orbital tracks. The EOS orbital parameters are used to provide specific examples. Variations in the information gain due to changes in the orbit's inclination angle and the initial ascending node local time are investigated. The results are also analyzed after normalizing by the number of measurements and for longer time averages. The information theory approach coupled with the stochastic diurnal model is found to be a useful tool for the objective evaluation of ERB measurement systems and can be applied to other nonuniformly sampled remote sensing measurements. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HALYO, N (reprint author), INFORMAT & CONTROL SYST INC,28 RES DR,HAMPTON,VA 23666, USA. NR 23 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1991 VL 29 IS 4 BP 665 EP 673 DI 10.1109/36.135829 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA FX027 UT WOS:A1991FX02700021 ER PT J AU BARAM, Y AF BARAM, Y TI ENCODING UNIQUE GLOBAL MINIMA IN NESTED NEURAL NETWORKS SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Letter DE NEURAL NETWORKS; NESTING; SPARSITY; CODING; GLOBAL MINIMA ID CAPACITY AB Nested neural networks are constructed from outer products of patterns over {-1,0,1}N, whose nonzero bits define subnetworks and the subcodes stored in them. The set of permissible words, which are network-size binary patterns composed of subcode words that agree in their common bits, is characterized and their number is derived. It is shown that if the bitwise products of the subcode words are linearly independent, the permissible words are the unique global minima of the Hamiltonian associated with the network. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BARAM, Y (reprint author), TECHNION ISRAEL INST TECHNOL,DEPT COMP SCI,IL-32000 HAIFA,ISRAEL. NR 8 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 0018-9448 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD JUL PY 1991 VL 37 IS 4 BP 1158 EP 1162 DI 10.1109/18.87008 PG 5 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FT065 UT WOS:A1991FT06500019 ER PT J AU PADIN, S ORTIZ, GG AF PADIN, S ORTIZ, GG TI A COOLED 1-2 GHZ BALANCED HEMT AMPLIFIER SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Note ID NOISE AB The design details and measurement results for a cooled L-band balanced HEMT amplifier are presented. The amplifier uses commercially available packaged HEMT devices (Fujitsu FHR02FH). At a physical temperature of 12 K the amplifier achieves noise temperatures between 3 and 6 K over the 1 to 2 GHz band. The associated gain is approximately 20 dB. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP PADIN, S (reprint author), CALTECH,OWENS VALLEY RADIO OBSERV,BIG PINE,CA 93513, USA. NR 9 TC 17 Z9 18 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUL PY 1991 VL 39 IS 7 BP 1239 EP 1243 DI 10.1109/22.85395 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA FP950 UT WOS:A1991FP95000025 ER PT J AU Krauthamer, S Gangal, M Das, R AF Krauthamer, Stan Gangal, Mukund Das, Radhe TI State-of-the Art of DC Components for Secondary Power Distribution of Space Station Freedom SO IEEE TRANSACTIONS ON POWER ELECTRONICS LA English DT Article AB The National Aeronautics and Space Administration has selected 120-Vdc secondary power distribution for Space Station Freedom. Although this high voltage level is new for space applications, it is well within the bounds for components and subsystems being developed and in some cases being used in aerospace, defense, and terrestrial applications. State-of-the-art components and subsystems for Space Station Freedom in terms of performance, size, and topology are examined. One objective is to inform the users of Space Station Freedom about what is available in power supplies and power control devices. The other objective is to stimulate the interest in the component industry so that more focused product development can be started. Based on results of this study, it is estimated that, with some redesign, modifications, and space qualification, many of these components may be applied to Space Station Freedom needs. C1 [Krauthamer, Stan; Gangal, Mukund; Das, Radhe] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RP Krauthamer, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. FU National Aeronautics and Space Administration FX This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology. Pasadena, under contract with the National Aeronautics and Space Administration. NR 66 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0885-8993 EI 1941-0107 J9 IEEE T POWER ELECTR JI IEEE Trans. Power Electron. PD JUL PY 1991 VL 6 IS 3 BP 548 EP 561 DI 10.1109/63.85889 PG 14 WC Engineering, Electrical & Electronic SC Engineering GA V43AE UT WOS:000209653500025 ER PT J AU ECKHARDT, DE CAGLAYAN, AK KNIGHT, JC LEE, LD MCALLISTER, DF VOUK, MA KELLY, JPJ AF ECKHARDT, DE CAGLAYAN, AK KNIGHT, JC LEE, LD MCALLISTER, DF VOUK, MA KELLY, JPJ TI AN EXPERIMENTAL EVALUATION OF SOFTWARE REDUNDANCY AS A STRATEGY FOR IMPROVING RELIABILITY SO IEEE TRANSACTIONS ON SOFTWARE ENGINEERING LA English DT Article DE FAULT-TOLERANT SOFTWARE; MULTIVERSION PROGRAMMING; N-VERSION PROGRAMMING; SOFTWARE RELIABILITY ID FAULT-TOLERANT SOFTWARE AB The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is suggested by the success of hardware redundancy for tolerating hardware failures. Although, as generally accepted, the independence of hardware failures resulting from physical wearout can lead to substantial increases in reliability for redundant hardware structures, a similar conclusion is not immediate for software. The degree to which design faults are manifested as independent failures determines the effectiveness of redundancy as a method for improving software reliability. Interest in multiversion software centers on whether it provides an adequate measure of increased reliability to warrant its use in critical applications. The effectiveness of multiversion software is studied by comparing estimates of the failure probabilities of these systems with the failure probabilities of single versions. The estimates are obtained under a model of dependent failures and compared with estimates obtained when failures are assumed to be independent. The experimental results are based on 20 versions of an aero-space application developed and independently validated by 60 programmers from 4 universities. Descriptions of the application and development process are given, together with an analysis of the 20 versions. C1 CHARLES RIVER ANALYT INC,CAMBRIDGE,MA 02138. UNIV VIRGINIA,DEPT COMP SCI,CHARLOTTESVILLE,VA 22903. OLD DOMINION UNIV,NORFOLK,VA 23508. N CAROLINA STATE UNIV,DEPT COMP SCI,RALEIGH,NC 27607. UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106. RP ECKHARDT, DE (reprint author), NASA,LANGLEY RES CTR,MS 478,HAMPTON,VA 23665, USA. NR 27 TC 61 Z9 61 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0098-5589 J9 IEEE T SOFTWARE ENG JI IEEE Trans. Softw. Eng. PD JUL PY 1991 VL 17 IS 7 BP 692 EP 702 DI 10.1109/32.83905 PG 11 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FZ283 UT WOS:A1991FZ28300005 ER PT J AU DEAR, RG SHERIF, YS AF DEAR, RG SHERIF, YS TI Z-BASIC ALGORITHM FOR COLLISION AVOIDANCE SYSTEM SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS LA English DT Letter AB A Z-Basic prediction algorithm for aircraft ground-based collision avoidance system is presented. This system searches for mutually overlapping prediction intervals that are influenced by aircrafts' maneuver capabilities and surveillance accuracy. Z-Basic provides a powerful, fast, interactive, simple to use and inexpensive Basic compiler. The algorithm is applied to a typical terminal airspace situation. The computer program was executed on a Macintosh+. The execution time is less than one minute. The program is easy to understand and implement. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP DEAR, RG (reprint author), CALIF STATE UNIV FULLERTON,DEPT MANAGEMENT SCI,FULLERTON,CA 92634, USA. NR 15 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 0018-9472 J9 IEEE T SYST MAN CYB JI IEEE Trans. Syst. Man Cybern. PD JUL-AUG PY 1991 VL 21 IS 4 BP 915 EP 921 DI 10.1109/21.108309 PG 7 WC Computer Science, Cybernetics; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GT940 UT WOS:A1991GT94000023 ER PT J AU ANTONIA, RA KIM, J AF ANTONIA, RA KIM, J TI TURBULENT PRANDTL NUMBER IN THE NEAR-WALL REGION OF A TURBULENT CHANNEL FLOW SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Note ID SCHMIDT NUMBERS; BOUNDARY-LAYER; TEMPERATURE; PREDICTION 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 15 TC 53 Z9 53 U1 1 U2 8 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 JUL PY 1991 VL 34 IS 7 BP 1905 EP 1908 DI 10.1016/0017-9310(91)90166-C PG 4 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA FT896 UT WOS:A1991FT89600030 ER PT J AU ROSS, HM YIP, LP PERKINS, JN VESS, RJ OWENS, DB AF ROSS, HM YIP, LP PERKINS, JN VESS, RJ OWENS, DB TI WING LEADING-EDGE DROOP SLOT MODIFICATION FOR STALL DEPARTURE RESISTANCE SO JOURNAL OF AIRCRAFT LA English DT Article AB Wind-tunnel and full-scale flight tests were performed on a general aviation configuration to investigate its high angle-of-attack aerodynamic characteristics. The tests were aimed at finding a wing leading-edge modification that would improve the stall departure characteristics. Test results indicated that a wing leading-edge modification was developed that greatly improved the stall characteristics of the configuration. This modification employed the use of an outboard wing leading-edge droop plus two chordwise leading-edge slots. On the wind-tunnel model, this modification was shown to produce almost no wing rock tendency when tested on a free-to-roll apparatus. When tested on the full-scale aircraft, the modification provided a gentle, very controllable stall with little or no penalty in cruise or climb performance. Lateral control of the aircraft was effective throughout the entire stall maneuver, which was performed with full elevator deflection. In general, the flight tests showed good agreement with the wind-tunnel results. RP ROSS, HM (reprint author), NASA,LANGLEY RES CTR,DIV FLIGHT APPLICAT,FLIGHT RES BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 1 Z9 1 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL PY 1991 VL 28 IS 7 BP 436 EP 442 DI 10.2514/3.46046 PG 7 WC Engineering, Aerospace SC Engineering GA FY432 UT WOS:A1991FY43200004 ER PT J AU STRAWA, AW CHAPMAN, GT CANNING, TN ARNOLD, JO AF STRAWA, AW CHAPMAN, GT CANNING, TN ARNOLD, JO TI BALLISTIC RANGE AND AEROTHERMODYNAMIC TESTING SO JOURNAL OF AIRCRAFT LA English DT Article AB Recent interest in hypervelocity vehicles requires an increase in our understanding of aerothermodynamic phenomena. Tests conducted in ground-based facilities will be used to better our understanding of the physics of hypervelocity flight and to verify computer models that will be used to predict vehicle performance in this environment. This paper reviews the requirements for aerothermodynamic testing and discusses the role of the aeroballistic range in accomplishing these requirements. Examples of the kinds of testing performed in typical high-performance aeroballistic ranges are described. Prospects for improving the capabilities of the aeroballistic range by using advanced instrumentation are discussed. Finally, recent developments in high-speed launch technology and their application to extend aeroballistic range capabilities are summarized. RP STRAWA, AW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 2 Z9 2 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL PY 1991 VL 28 IS 7 BP 443 EP 449 DI 10.2514/3.46047 PG 7 WC Engineering, Aerospace SC Engineering GA FY432 UT WOS:A1991FY43200005 ER PT J AU ADLER, RF YEH, HYM PRASAD, N TAO, WK SIMPSON, J AF ADLER, RF YEH, HYM PRASAD, N TAO, WK SIMPSON, J TI MICROWAVE SIMULATIONS OF A TROPICAL RAINFALL SYSTEM WITH A 3-DIMENSIONAL CLOUD MODEL SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID 183 GHZ; MESOSCALE PROCESSES; DEEP CONVECTION; ICE; WATER; SNOW; PARAMETERIZATION; PRECIPITATION; FREQUENCIES; SATELLITE AB A three-dimensional cloud model-microwave radiative transfer model combination is used to study the relations among the precipitation and other microphysical characteristics of a tropical oceanic squall line and the upwelling radiance at pertinent microwave frequencies. Complex brightness temperature-rain rate relations are evident at the full horizontal resolution (1.5 km) of the models, with spatial averaging producing smoother, shifted relations in most cases. Nonprecipitating cloud water is shown to be important in understanding the resulting distribution of brightness temperature. At the mature stage, convective portions of the cloud system are shown to produce different brightness temperature relations than the stratiform portion, primarily related to the distribution of cloud water. The evolution of the convective system from a small convective complex through its mature stage and the beginning of its dissipation also is shown to result in a variation of brightness temperature-rain relations, related to the distribution of cloud water and the evolution of ice in the precipitating system. The results of the study point to the need to take into account the evolution of nonprecipitating cloud water and precipitation-sized ice in the retrieval of rain from passive microwave space observations. This effect is evident for both the life cycle of individual convective elements and the life cycle of the convective system as a whole. C1 CAELUM RES CORP,SILVER SPRING,MD. GEN SCI CORP,LAUREL,MD. RP ADLER, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 973,GREENBELT,MD 20771, USA. NR 34 TC 106 Z9 111 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 JUL PY 1991 VL 30 IS 7 BP 924 EP 953 DI 10.1175/1520-0450-30.7.924 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX373 UT WOS:A1991FX37300002 ER PT J AU MCCUMBER, M TAO, WK SIMPSON, J PENC, R SOONG, ST AF MCCUMBER, M TAO, WK SIMPSON, J PENC, R SOONG, ST TI COMPARISON OF ICE-PHASE MICROPHYSICAL PARAMETERIZATION SCHEMES USING NUMERICAL SIMULATIONS OF TROPICAL CONVECTION SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SQUALL-LINE; BULK PARAMETERIZATION; MICROSCALE STRUCTURE; MESOSCALE PROCESSES; FRONTAL RAINBANDS; MODEL DESCRIPTION; DEEP CONVECTION; CLOUD CLUSTERS; CUMULUS CLOUDS; CYCLONE MODEL AB A numerical cloud model is used to evaluate the performance of several ice parameterizations. Results from simulations using these schemes are contrasted with each other, with an ice-free control simulation, and with observations to determine to what extent ice physics affect the realism of these results. Two different types of tropical convection are simulated. Tropical squall-type systems are simulated in two dimensions so that a large domain can be used to incorporate a complete anvil. Nonsquall-type convective lines are simulated in three dimensions owing to their smaller horizontal scale. The inclusion of ice processes enhances the agreement of the simulated convection with some features of observed convection, including the proportion of surface rainfall in the anvil region, and the intensity and structure of the radar brightband near the melting level in the anvil. In the context of our experimental design, the use of three ice classes produces better results than two ice classes or ice-free conditions, and for the tropical cumuli, the optimal mix of the bulk ice hydrometeors is cloud ice-snow-graupel. We infer from our modeling results that application of bulk ice microphysics in cloud models might be case specific, which is a significant limitation. This can have serious ramifications for microwave interpretation of cloud microphysical properties. Generalization of ice processes may require a larger number of ice categories than we have evaluated and/or the prediction of hydrometeor concentrations or particle-size spectra. C1 RES & DATA SYST INC,LANHAM,MD. UNIV CALIF DAVIS,DEPT LAND AIR & WATER RESOURCES,DAVIS,CA 95616. RP MCCUMBER, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,SEVERE STORMS BRANCH 973,GREENBELT,MD 20771, USA. NR 61 TC 154 Z9 160 U1 1 U2 6 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 JUL PY 1991 VL 30 IS 7 BP 985 EP 1004 DI 10.1175/1520-0450-30.7.985 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX373 UT WOS:A1991FX37300006 ER PT J AU FISHMAN, J AF FISHMAN, J TI COMMENT ON TROPICAL CYCLONE-UPPER-ATMOSPHERIC INTERACTION AS INFERRED FROM SATELLITE TOTAL OZONE OBSERVATIONS SO JOURNAL OF APPLIED METEOROLOGY LA English DT Note RP FISHMAN, J (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23665, USA. NR 4 TC 2 Z9 2 U1 0 U2 0 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 JUL PY 1991 VL 30 IS 7 BP 1047 EP 1048 DI 10.1175/1520-0450-30.7.1047 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX373 UT WOS:A1991FX37300013 ER PT J AU RODGERS, E STOUT, J STERANKA, J CHANG, S AF RODGERS, E STOUT, J STERANKA, J CHANG, S TI COMMENT ON TROPICAL CYCLONE-UPPER-ATMOSPHERIC INTERACTION AS INFERRED FROM SATELLITE TOTAL OZONE OBSERVATIONS - REPLY SO JOURNAL OF APPLIED METEOROLOGY LA English DT Note C1 GEN SCI CORP,LAUREL,MD. USN,RES LAB,WASHINGTON,DC 20375. RP RODGERS, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771, USA. NR 2 TC 3 Z9 3 U1 0 U2 0 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 JUL PY 1991 VL 30 IS 7 BP 1049 EP 1049 DI 10.1175/1520-0450-30.7.1049 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX373 UT WOS:A1991FX37300014 ER PT J AU SCHRYER, DR UPCHURCH, BT SIDNEY, BD BROWN, KG HOFLUND, GB HERZ, RK AF SCHRYER, DR UPCHURCH, BT SIDNEY, BD BROWN, KG HOFLUND, GB HERZ, RK TI A PROPOSED MECHANISM FOR PT/SNOX-CATALYZED CO OXIDATION SO JOURNAL OF CATALYSIS LA English DT Note ID PRETREATMENT; EXPOSURE C1 OLD DOMINION UNIV,DEPT CHEM SCI,NORFOLK,VA 23508. UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611. UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. RP SCHRYER, DR (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 12 TC 108 Z9 110 U1 0 U2 6 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9517 J9 J CATAL JI J. Catal. PD JUL PY 1991 VL 130 IS 1 BP 314 EP 317 DI 10.1016/0021-9517(91)90114-J PG 4 WC Chemistry, Physical; Engineering, Chemical SC Chemistry; Engineering GA FR445 UT WOS:A1991FR44500029 ER PT J AU HUO, WM RINNEN, KD ZARE, RN AF HUO, WM RINNEN, KD ZARE, RN TI ROTATIONAL AND VIBRATIONAL EFFECTS IN THE E 1-SIGMA-G+-X 1-SIGMA-G+ 2-PHOTON TRANSITIONS OF H2, HD, AND D2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID H+D2 REACTION; ABINITIO CALCULATION; STATE DISTRIBUTIONS; COLLISION ENERGIES; MATRIX-ELEMENTS; H-2 MOLECULE; HYDROGEN; GK; ABSORPTION AB A theoretical study is reported for the dependence of the E, F 1-SIGMA-g+-X 1-SIGMA-g+ (upsilon-E = 0, upsilon-X) Q-branch two-photon transitions on the initial vibrational and rotational quantum numbers upsilon-X and J for H-2, HD, and D2. The magnitude of the two-photon transition moment \M(fo)\ increases with upsilon-X between 0 and 2, then decreases rapidly at higher upsilon-X. This behavior is ascribed to (constructive and destructive) interference effects in the two-photon transition, which vary with the nodal behavior of the initial-state vibrational wave function. The J dependence of \M(fo)\ is most strongly affected by the changes in vibrational wave functions caused by centrifugal distortion of the vibrational potentials. At low to intermediate J, the Franck-Codon overlap improves, resulting in a slow, monotonic increase of \M(fo)\ with J. At higher J, resonant tunneling between the inner and outer wells of the E,F state introduces sharp variations in the \M(fo)\ structure. Near the top of the barrier, nonresonant tunneling in the E-state vibrational wave function causes a general decrease in \M(fo)\ with J. C1 STANFORD UNIV,DEPT CHEM,STANFORD,CA 94305. RP HUO, WM (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Zare, Richard/A-8410-2009 NR 22 TC 34 Z9 34 U1 0 U2 7 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 JUL 1 PY 1991 VL 95 IS 1 BP 205 EP 213 DI 10.1063/1.461477 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FT847 UT WOS:A1991FT84700022 ER PT J AU RINNEN, KD BUNTINE, MA KLINER, DAV ZARE, RN HUO, WM AF RINNEN, KD BUNTINE, MA KLINER, DAV ZARE, RN HUO, WM TI QUANTITATIVE-DETERMINATION OF H2, HD, AND D2 INTERNAL-STATE DISTRIBUTIONS BY (2+1) RESONANCE-ENHANCED MULTIPHOTON IONIZATION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID PRODUCT ROTATIONAL DISTRIBUTIONS; VIBRATIONALLY EXCITED H-2; HIGH COLLISION ENERGIES; MOLECULAR-HYDROGEN; H+D2 REACTION; RECOMBINATIVE DESORPTION; 2-PHOTON EXCITATION; CROSS-SECTIONS; PHOTOELECTRON-SPECTROSCOPY; DISSOCIATIVE RECOMBINATION AB The relationship between quantum-state populations and ion signals in (2 + 1) resonance-enhanced multiphoton ionization (REMPI) detection of H-2, HD, and D2 via the E,F 1-SIGMA-g+ (upsilon'-E = 0, J' = J")-X 1-SIGMA-g+ (upsilon",J") transition is determined by calibration against a thermal effusive source. Correction factors are obtained for 102 rovibrational levels for upsilon" = 0, 1, and 2 and J" ranging from 0 to 17. Within a given upsilon", rotational correction factors are nearly unity except for the highest J" levels. The vibrational correction factors vary with upsilon"; (2 + 1) REMPI detection is 2-3 times more sensitive to upsilon" = 1 and 2 than to upsilon" = 0. Experimental correction factors are compared with those derived from a theoretical calculation of the two-photon transition moments by Huo et al. [J. Chem. Phys. 95, 205 (1991)]. In general, the agreement is excellent, which suggests that theoretical correction factors may be used when experimental ones are unavailable. C1 STANFORD UNIV,DEPT CHEM,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Zare, Richard/A-8410-2009; Buntine, Mark/B-6878-2009 OI Buntine, Mark/0000-0003-0525-2795 NR 82 TC 73 Z9 73 U1 6 U2 27 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 JUL 1 PY 1991 VL 95 IS 1 BP 214 EP 225 DI 10.1063/1.461478 PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FT847 UT WOS:A1991FT84700023 ER PT J AU COHEN, J RIND, D AF COHEN, J RIND, D TI THE EFFECT OF SNOW COVER ON THE CLIMATE SO JOURNAL OF CLIMATE LA English DT Article AB Large-scale snow cover anomalies are thought to cause significant changes in the diabetic heating of the earth's surface in such a way as to produce substantial local cooling in the surface temperatures. This theory was tested using the GISS 3-D GCM (General Circulation Model). The results of the GCM experiment showed that snow cover caused only a short term local decrease in the surface temperature. In the surface energy budget, reduction in absorbed shortwave radiation and the increased latent heat sink of melting snow contributed to lower temperatures. However, all the remaining heating terms contribute to increasing the net heating over a snow covered surface. The results emphasize the negative feedback which limits the impact of snow cover anomalies over longer time scales. RP COHEN, J (reprint author), GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 0 TC 121 Z9 142 U1 2 U2 27 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUL PY 1991 VL 4 IS 7 BP 689 EP 706 DI 10.1175/1520-0442(1991)004<0689:TEOSCO>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FW328 UT WOS:A1991FW32800003 ER PT J AU HIEL, CC SUMICH, M CHAPPELL, DP AF HIEL, CC SUMICH, M CHAPPELL, DP TI A CURVED BEAM TEST SPECIMEN FOR DETERMINING THE INTERLAMINAR TENSILE-STRENGTH OF A LAMINATED COMPOSITE SO JOURNAL OF COMPOSITE MATERIALS LA English DT Article AB A curved beam type of test specimen is evaluated for use in determining the through-the-thickness strength of laminated composites. Two variations of a curved beam specimen configuration (semicircular and elliptical) were tested to failure using static and fatigue loads. The static failure load for the semicircular specimens was found to be highly sensitive to flaw content, with the specimens falling into two distinct groups. This result supports the use of proof testing for structural validation. Static design allowables are derived based on the Weibull distribution. Fatigue data indicates no measured increase in specimen compliance prior to final fracture. All static and fatigue failures at room temperature dry conditions occurred catastrophically. The elliptical specimens demonstrated unusually high failure strengths indicating the presence of phenomena requiring further study. Results are also included for specimens exposed to a wet environment showing a matrix strength degradation due to moisture content. Further testing is underway to evaluate a fatigue methodology for matrix dominated failures based on residual static strength (wearout). RP HIEL, CC (reprint author), NASA,AMES RES CTR,MAIL STOP 213-3,MOFFETT FIELD,CA 94035, USA. NR 10 TC 51 Z9 52 U1 0 U2 4 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 JUL PY 1991 VL 25 IS 7 BP 854 EP 868 PG 15 WC Materials Science, Composites SC Materials Science GA GC648 UT WOS:A1991GC64800005 ER PT J AU JACQMIN, D AF JACQMIN, D TI FRONTOGENESIS DRIVEN BY HORIZONTALLY QUADRATIC DISTRIBUTIONS OF DENSITY SO JOURNAL OF FLUID MECHANICS LA English DT Article AB Experiments by Simpson & Linden (1989) have shown that a horizontally nonlinear distribution of fluid density is necessary in order to produce frontogenesis. This paper considers the simplest case of such a nonlinear distribution, a quadratic density distribution in a channel. Two flow models are examined, porous media and Boussinesq. The evolution equations for both these flows can be reduced to one-dimensional systems. An exact solution is derived for porous-media flow with no molecular diffusion. Numerical solutions are shown for the other cases. The porous-media and inviscid/non-diffusive Boussinesq systems exhibit 'classic' frontogenesis behaviour: a rapid and intense steepening of the density gradient near the lower boundary while horizontal divergence reduces the upper-boundary density gradient to nearly zero. The viscous Boussinesq system exhibits a more complicated behaviour. In this system, boundary-layer effects force frontogenesis away from the lower boundary and at late times the steepest density gradients are close to mid-channel One feature of these model systems is that they can exhibit blow-up finite time. Proof of blow-up is given for the non-diffusive porous media and inviscid/nondiffusive Boussinesq cases. Numerical results indicate that blow-up also occurs for the diffusive porous-media case and that it may occur for the diffusive Boussinesq case. Despite the blow-up we believe that the model solutions can be applied to real situations. To support this a two-dimensional calculation has been made of Boussinesq frontogenesis in a long box. This calculation shows close agreement with the corresponding one-dimensional calculation up to times close to blow-up. RP JACQMIN, D (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 4 TC 6 Z9 6 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL PY 1991 VL 228 BP 1 EP 24 DI 10.1017/S0022112091002616 PG 24 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FZ151 UT WOS:A1991FZ15100001 ER PT J AU HENNINGSON, DS KIM, J AF HENNINGSON, DS KIM, J TI ON TURBULENT SPOTS IN PLANE POISEUILLE FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID LAMINAR BOUNDARY-LAYER; WAVE PACKET; SECONDARY INSTABILITY; SHEAR-FLOW; WALL; GROWTH; VISUALIZATION; TRANSITION; BREAKDOWN AB Turbulence characteristics inside a turbulent spot in plane Poiseuille flow are investigated by analysing a database obtained from a direct numerical simulation. The spot is found to consist of two distinct regions - a turbulent area and a wave area. The flow inside the turbulent area has a strong resemblance to that found in the fully developed turbulent channel. Suitable defined mean and r.m.s. fluctuations as well as the internal shear-layer structures are found to be similar to the turbulent counterpart. In the wave area the inflexional mean spanwise profiles cause a rapid growth of oblique waves, which break down to turbulence. The breakdown process of the oblique waves is reminiscent of the secondary instability observed during transition to turbulence in channel and boundary-layer flows. Other detailed characteristics associated with the Poiseuille spot are presented and are compared with experimental results. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HENNINGSON, DS (reprint author), MIT,DEPT MATH,CAMBRIDGE,MA 02139, USA. OI Kim, John/0000-0002-6369-9264 NR 37 TC 31 Z9 32 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL PY 1991 VL 228 BP 183 EP & DI 10.1017/S0022112091002677 PG 0 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FZ151 UT WOS:A1991FZ15100007 ER PT J AU SEIFF, A KIRK, DB AF SEIFF, A KIRK, DB TI WAVES IN VENUSS MIDDLE AND UPPER-ATMOSPHERE - IMPLICATIONS OF PIONEER VENUS PROBE DATA ABOVE THE CLOUDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID THERMOSPHERE TEMPERATURE STRUCTURE; RADIATIVE EQUILIBRIUM; MESOSPHERE; MODEL AB Probe data showing the presence of waves in Venus's middle and upper atmosphere [Seiff et al., 1980; Seiff and Kirk, 1982] am critically reevaluated and extended to 138 km, near the level of in-situ data taken by the Pioneer Venus orbiter. Uncertainties in temperature are determined. They are typically about 0.1 times amplitude, thus supporting the reality of large amplitude oscillations approaching 40 K at 120 km. Growth rates above 100 km follow approximately the inverse square root of density until "saturation" occurs (in the sense that lapse rates become adiabatic in the expanding segment of the wave). The waves then break at the 120 km level, providing a source for the "friction" required in models to match the observed day-night temperature contrast in Venus's lower thermosphere [Seiff, 1982; Bougher, 1984]. The data correlate to an unexpected degree with temperatures from the Pioneer Venus orbiter atmospheric drag (OAD) experiment taken at altitudes of 140 to 165 km, which, especially for the night probe, extend not only the mean temperature structure, but also the oscillation structure of the probe data at the same local Venus time. OAD temperatures depend on local Venus time and altitude, but, in the limited number of observations, appear independent of observing date over periods of up to 11 days, and correlate as described with probe data taken 65 to 137 days earlier. These observations lead to the suggestion that the thermospheric waves are solar-fixed, induced either by the major subsidence across the terminators or as continuations upward of waves in the middle atmosphere. The wave structure in the large probe sounding below 100 km is similar to, but does not quantitatively support the solar-tidal model of Pechmann and Ingersoll, which gives much larger amplitudes and different wave phases. C1 UNIV OREGON,DEPT PHYS,EUGENE,OR 97403. RP SEIFF, A (reprint author), NASA,AMES RES CTR,SAN JOSE STATE UNIV FDN,MAIL STOP 245-1,MOFFETT FIELD,CA 94035, USA. NR 22 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11021 EP 11032 DI 10.1029/91JA01101 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100002 ER PT J AU BORUCKI, WJ DYER, JW PHILLIPS, JR PHAM, P AF BORUCKI, WJ DYER, JW PHILLIPS, JR PHAM, P TI PIONEER VENUS ORBITER SEARCH FOR VENUSIAN LIGHTNING SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID IMPULSIVE ELECTRIC SIGNALS; RETURN STROKES; ELECTROSTATIC DISCHARGES; PLANETARY-ATMOSPHERES; NIGHT IONOSPHERE; TITAN; HCN; INTRACLOUD; JUPITER AB During 1988 and 1990, the star sensor aboard the Pioneer Venus orbiter (PVO) was used to search for optical pulses from lightning on the nightside of Venus. In our previous effort to use the star sensor for this purpose [Borucki et al., 1981], we reported an upper limit to the lightning activity, but we were unable to show that lightning was being detected because the signal rate was indistinguishable from the false alarm rate. Because the periapsis altitude has increased by nearly a factor of ten since 1979, the star scanner views a much larger area of Venus than it did previously. This increased viewing area should provide an increased signal rate because the amplitude of optical pulses should still be above the detection threshold of the sensor if the flashes are as bright as terrestrial flashes. Because the false alarm rate did not increase, the increased viewing area allows a more sensitive search for lightning activity. Useful data were obtained for 53 orbits in 1988 and 55 orbits in 1990. During this period, approximately 83 s of search time plus 7749 s of control data were obtained. Our results again find no optical evidence for lightning activity. Within the region that was observed during 1988, the results imply that the upper bound to short-duration flashes is 4x 10(-7) flashes/km2/s for flashes that are at least 50% as bright as typical terrestrial lightning. During 1990, when the 2-Hz filter was used, the results imply an upper bound of 1 x 10(-7) flashes/km2/s for long-duration flashes at least 1.6% as bright as typical terrestrial lightning flashes or 33% as bright as the pulses observed by the Venera 9. The upper bounds to the flash rates for the 1988 and 1990 searches are twice and one half the global terrestrial rate, respectively. These two searches covered the region from 60-degrees-N latitude to 30-degrees-S latitude, 250-degrees to 350-degrees longitude, and the region from 45-degrees-N latitude to 55-degrees-S latitude, 155-degrees to 300-degrees longitude. Both searches sampled much of the nightside region from the dawn terminator to within 4 hours of the dusk terminator. These searches covered a much larger latitude range than any previous search. Our results show that the Beta and Phoebe Regio areas previously identified by Russell et al. [1988] as areas with high rates of lightning activity were not active during the two seasons of our observations. When we assume that our upper bounds to the nightside flash rate are representative of the entire planet, the results imply that the global flash rate and energy dissipation rate derived by Krasnopol'sky [1983] from his observation of a single storm are too high. Experimental measurements carried out to determine the amount of scattering occurring in the star scanner optics indicate that our previously determined upper bound to lightning activity is too low. The present results supplant the past results. The apparent conflict between the radio data that indicate the presence of a large amount of lightning activity and the optical data that indicate no lightning on the nightside, can be resolved by noting that theoretical considerations indicate lightning activity is to be expected only on the dayside. C1 SETI INST,MT VIEW,CA 94043. RP BORUCKI, WJ (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 56 TC 22 Z9 22 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11033 EP 11043 DI 10.1029/91JA01097 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100003 ER PT J AU WHITTEN, RC BARNES, A MCCORMICK, PT AF WHITTEN, RC BARNES, A MCCORMICK, PT TI PLASMA MOTION IN THE VENUS IONOSPHERE - TRANSITION TO SUPERSONIC-FLOW SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID TWO-DIMENSIONAL MODEL; DYNAMICS AB A remarkable feature of the ionosphere of Venus is the presence of nightward supersonic flows at high altitude near the terminator. In general the steady flow of an ideal gas admits a subsonic-supersonic transition only in the presence of special conditions, such as a convergence of the flow followed by divergence, or external forces. In this paper we show that the relatively high pressure dayside plasma wells up slowly, and at high altitude it is accelerated horizontally through a relatively constricted region near the terminator toward the low-density nightside. In effect, the plasma flows through a "nozzle" that is first converging, then diverging, permitting the transition to supersonic flow. Analysis of results from previously published models of the plasma flow in the upper ionosphere of Venus shows how such a "nozzle" is formed. The model plasma does indeed accelerate to supersonic speeds, reaching sonic speed just behind the terminator. The computed speeds prove to be close to those observed by the Pioneer Venus orbiter, and the ion transport rates are sufficient to produce and maintain the nightside ionosphere. C1 UNIV SANTA CLARA,DEPT PHYS,SANTA CLARA,CA 95053. RP WHITTEN, RC (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 17 TC 13 Z9 13 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 JUL 1 PY 1991 VL 96 IS A7 BP 11057 EP 11064 DI 10.1029/91JA00318 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100005 ER PT J AU KLIORE, AJ LUHMANN, JG ZHANG, MHG AF KLIORE, AJ LUHMANN, JG ZHANG, MHG TI THE EFFECT OF THE SOLAR-CYCLE ON THE MAINTENANCE OF THE NIGHTSIDE IONOSPHERE OF VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID RADIO OCCULTATIONS; 1ST OBSERVATIONS; ION COMPOSITION; DAYSIDE; IONIZATION; FLOWS AB Pioneer Venus radio occultation measurements of the nightside ionosphere of Venus collected from 1979 to 1986 have made it possible to study its behavior at times of both solar maximum and solar minimum. Although some solar maximum measurements are similar in nature to those observed at solar minimum. which have an average peak density of about 7 x 10(3) cm-3, others show much higher peak densities, reaching values of about 4 x 10(4) cm-3. These elevated peak densities also occur at higher altitudes. The integrated electron column densities for these measurements are also much higher, indicating the presence of substantial ionization above the main peak. The magnitudes of both the peak density and the integrated content above the peak are anticorrelated with the solar wind dynamic pressure, leading to the interpretation that these enhancements during solar maximum are due to transterminator transport of O+ ions from the dayside when the solar wind dynamic pressure is low enough to permit a sufficiently high dayside ionopause. The resulting ionization peak can be many times the concentration produced by energetic electron fluxes impacting the neutral atmosphere on the nightside, which apparently form the remaining source of the nightside peak at such times during solar maximum, when transterminator flow is cut off by high solar wind pressure depressing the dayside ionopause, and during solar minimum, when the ionopause is always depressed. C1 UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY SCI,LOS ANGELES,CA 90024. AUSTRIAN ACAD SCI,SPACE RES INST,A-8010 GRAZ,AUSTRIA. RP KLIORE, AJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 32 TC 26 Z9 26 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 JUL 1 PY 1991 VL 96 IS A7 BP 11065 EP 11071 DI 10.1029/91JA00672 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100006 ER PT J AU WOO, R AF WOO, R TI MAGNETIZATION OF THE IONOSPHERES OF VENUS AND MARS - RESULTS FROM RADIO OCCULTATION MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID SOLAR-WIND INTERACTION; MULTISPECIES MAGNETOHYDRODYNAMIC MODEL; DAYSIDE IONOSPHERE; ELECTRON-TEMPERATURE; IONOPAUSE; MINIMUM; SCALE AB In situ measurements by the Pioneer Venus orbiting spacecraft, conducted during solar maximum only, have shown that magnetization (permeation of large-scale magnetic fields) of the ionosphere of Venus occurs under high solar wind dynamic pressure and that this takes place most frequently near the subsolar region. Magnetization is also revealed in electron density profiles by the presence of disturbed topside plasma and/or a ledge near the altitude of 200 km. In this paper we use remote sensing radio occultation measurements to study magnetization of the ionospheres of Venus and Mars based on these characteristics. For Venus we take advantage of the unique data set consisting of 148 electron density profiles deduced from Pioneer Venus radio occultation measurements. We demonstrate that radio occultation measurements yield results on frequency of occurrence of magnetization during solar maximum that are similar to those obtained from the Pioneer Venus in situ magnetic field measurements. During solar minimum, for which direct ionospheric measurements have never been made, we find that magnetization of the Venus ionosphere is more pervasive than at solar maximum. Magnetization extends to higher solar zenith angles (SZA) and appears stronger than at solar maximum. These results confirm that during solar minimum, the high solar wind dynamic pressure state is more prevalent at Venus because the ionospheric plasma pressure is weaker than at solar maximum. Comparison of a large number of electron density profiles of Mars (deduced from radio occultation measurements by the Viking 1 and 2 and Mariner 9 spacecraft for SZA > 46-degrees) with those of Venus shows an absence of the ledge and disturbed topside plasma observed in the Venus profiles. These results, however, do not constitute evidence against magnetization of the ionosphere of Mars, as Shinagawa and Cravens (1989) have shown in their one-dimensional MHD models that, even when the ionosphere of Mars is highly magnetized, the magnetic structure differs from that at Venus, and a ledge does not form in its electron density profiles. RP WOO, R (reprint author), CALTECH,JET PROP LAB,MS 238-737,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 24 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11073 EP 11081 DI 10.1029/91JA00313 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100007 ER PT J AU SHINAGAWA, H KIM, J NAGY, AF CRAVENS, TE AF SHINAGAWA, H KIM, J NAGY, AF CRAVENS, TE TI A COMPREHENSIVE MAGNETOHYDRODYNAMIC MODEL OF THE VENUS IONOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID SCALE MAGNETIC-FIELDS; SOLAR-WIND INTERACTION; TWO-DIMENSIONAL MODEL; PIONEER-VENUS; ELECTRON-TEMPERATURE; DAYSIDE IONOSPHERE; THERMAL STRUCTURE; ION ENERGETICS; PEAK; FLOW AB The MHD Venus ionospheric model developed by Shinagawa and Cravens (1988) has been improved by including the energy equations for ions and electrons in a self-consistent manner. This new model reproduces observed electron density and magnetic field profiles very well, and the basic MHD processes of the Venus ionosphere. as described by Shinagawa and Cravens (1988), remain virtually unchanged. The results indicate that including energetics does not significantly alter the density and magnetic field profiles. Under unmagnetized conditions, it is necessary to impose heat fluxes for both ions and electrons in order to reproduce the observed plasma temperature profiles, which are consistent with the studies by Cravens et al. (1979, 1980) and Kim et al. (1990). In the magnetized ionosphere, it is likely that a heat source for the ions is present at higher altitudes. On the other hand, the observed very high electron temperatures can be reproduced with a reduced conductivity or with a heat source at high altitudes. It is also found that heating processes do not play a significant role in the dynamics at low altitudes. Thus a nearly supersonic downward velocity layer in the lower ionosphere of Venus, proposed by Cloutier et al. (1987), is unlikely, suggesting that their flow/field model is not applicable to the solar wind-Venus interaction and other unmagnetized bodies in magnetized plasma flows. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. UNIV KANSAS,DEPT PHYS & ASTRON,LAWRENCE,KS 66045. NR 41 TC 19 Z9 19 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11083 EP 11095 DI 10.1029/90JA02505 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100008 ER PT J AU KASPRZAK, WT GREBOWSKY, JM NIEMANN, HB BRACE, LH AF KASPRZAK, WT GREBOWSKY, JM NIEMANN, HB BRACE, LH TI SUPERTHERMAL-GREATER-THAN-36-EV IONS OBSERVED IN THE NEAR-TAIL REGION OF VENUS BY THE PIONEER VENUS ORBITER NEUTRAL MASS-SPECTROMETER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID PLASMA OBSERVATIONS; IONOSPHERIC HOLES; ENERGETIC IONS; MAGNETIC-FIELD; SOLAR-WIND; NIGHTSIDE; ACCELERATION; MAGNETOTAIL; IONOTAIL; ESCAPE AB The Pioneer Venus orbiter neutral mass spectrometer (ONMS) has made measurements of > 36-eV ions in the altitude range 1300-3700 km for solar zenith angles greater than 120-degrees. The observations cover a time period from late 1982 to 1989. The superthermal ions form part of the near-tail region of Venus termed the ionotail. The ONMS superthermal ions represent only a small fraction (about 0.3%) of the plasma density in the ionotail region. The composition is mainly O+, but He+, N+, (CO+ + N2+), NO+, and O2+ have been identified. CO2+ is very rarely observed in this region, and H+ is not measured. The average O+ flux is about 10(5) cm-2 s-1, but higher fluxes from 10(6) to 10(8) cm-2 s-1 have been observed about 10% of the time. The directions of the apparent 0 + ion flow in the ecliptic plane show predominantly tailward components with a smaller number of nontailward components. Since the energy of the superthermal ions is sufficient for planetary escape, the > 36-eV O+ escape flux in the ionotail is estimated to be about 10(5) cm-2 s-1. Other species observed also have enough energy to escape. The O+ flux data show a factor of 2.5 increase from solar minimum to solar maximum implying a photoionization source for these ions. Neither the origin of the > 36-eV ions nor the acceleration mechanism is precisely known. The 0 + flux observations do not appear to be correlated with the direction of the "cross-tail" magnetic field as might be expected if the ions were due to the asymmetric pickup of newly ionized atmospheric neutrals above the ionopause. The composition of the superthermal ions in the ionotail suggests that their source is most likely the high-altitude nightside ionosphere where O+ and not O+ is the dominant ion. Transport of superthermal O+ across the terminator to the nightside has been observed, and measurements in the ionotail region at solar minimum near 2000 km show that O+ is mainly superthermal. Much further down the tail, very energetic (0-8 keV) O+ has been observed as it escapes Venus. Conditions in the lower nightside ionosphere have been shown to be consistent with an upward ion flow. Parallel electric fields or J x B forces associated with the convection of the interplanetary magnetic field through or above the ionosphere have been suggested as acceleration mechanisms in the ionotail. Similar mechanisms have been proposed for the tail region of Mars where energetic molecular ions such as O+ have also been observed and may also be appropriate for Titan if the 28-amu species observed is due to H2CN+. C1 UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP KASPRZAK, WT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Grebowsky, Joseph/I-7185-2013 NR 38 TC 22 Z9 22 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11175 EP 11187 DI 10.1029/91JA00677 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100015 ER PT J AU SLAVIN, JA SCHWINGENSCHUH, K RIEDLER, W YEROSHENKO, Y AF SLAVIN, JA SCHWINGENSCHUH, K RIEDLER, W YEROSHENKO, Y TI THE SOLAR-WIND INTERACTION WITH MARS - MARINER-4, MARS-2, MARS-3, MARS-5, AND PHOBOS-2 OBSERVATIONS OF BOW SHOCK POSITION AND SHAPE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article; Proceedings Paper CT CHAPMAN CONF ON VENUS AND MARS : ATMOSPHERES, IONOSPHERES AND SOLAR WIND INTERACTIONS CY JUN 04-08, 1990 CL BALATONFURED, HUNGARY SP AMER GEOPHYS UNION, ACAD SCI HUNGARY ID MAGNETIC-FIELD; TERRESTRIAL PLANETS; VENUS; MAGNETOSPHERE; MODEL; FLOW AB Observations taken by Mariner 4, Mars 2, Mars 3, Mars 5, and Phobos 2 are used to model the shape, position, and variability of the Martian bow shock for the purpose of better understanding the interaction of this planet with the solar wind. Emphasis is placed upon comparisons with the results of similar analyses at Venus, the only planet known to have no significant intrinsic magnetic field. Excellent agreement is found between Mars bow shock models derived from the earlier Mariner-Mars data set (24 crossings in 1964-1974) and the far more extensive observations recently returned by Phobos 2 (94 crossings in 1989). The best fit model to the aggregate data set locates the subsolar bow shock at a planetocentric distance of 1.56 +/- 0.04 R(M). Mapped into the terminator plane, the average distance to the Martian bow shock is 2.66 +/- 0.05 R(M). Compared with Venus, the bow wave at Mars is significantly more distant in the terminator plane, 2.7 R(M) versus 2.4 R(V), and over twice as variable in location with a standard deviation of 0.49 R(M) versus 0.21 R(V) at Venus. The Mars 2, 3, and 5 and Phobos 2 data also contain a small number of very distant dayside shock crossings with inferred subsolar obstacle radii derived from gasdynamic modeling of 2000 to 4000 km. Such distant bow shock occurrences do not appear to take place at Venus and may be associated with the expansion of a small Martian magnetosphere under the influence of unusually low solar wind pressure. Finally, the altitude of the Venus bow shock has a strong solar cycle dependence believed to be due to the effect of solar EUV on the neutral atmosphere and mass loading. Comparison of the Phobos 2 shock observations near solar maximum (R(z) = 141) with the Mariner-Mars measurements taken much farther from solar maximum (R(z) = 59) indicates that the Martian bow shock location is independent of solar cycle phase and, hence, solar EUV flux. These results are interpreted in terms of a hybrid solar wind interaction model in which this planet possesses a weak, but significant, intrinsic magnetic field. C1 INST WELTRAUMFORSCH,GRAZ,AUSTRIA. IZMIRAN,MOSCOW 142092,USSR. RP SLAVIN, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 39 TC 66 Z9 66 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11235 EP 11241 DI 10.1029/91JA00439 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100021 ER PT J AU GOLDSTEIN, R AF GOLDSTEIN, R TI ION-ACCELERATION AT THE CONTACT SURFACE OF COMET P/HALLEY - COMMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID P-HALLEY RP GOLDSTEIN, R (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1991 VL 96 IS A7 BP 11641 EP 11641 DI 10.1029/91JA01090 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FW171 UT WOS:A1991FW17100056 ER PT J AU SUNKEL, JW SHIEH, LS ZHANG, JL AF SUNKEL, JW SHIEH, LS ZHANG, JL TI DIGITAL REDESIGN OF AN OPTIMAL MOMENTUM MANAGEMENT CONTROLLER FOR THE SPACE STATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID REGULATORS AB A digital redesign technique is developed for determining the digital version of an optimal momentum management controller previously designed by the authors for the Space Station Freedom. The technique matches the continuous-time and discrete-time states at all sampling instants to find a pseudocontinuous-time quadratic regulator from a continuous-time quadratic regulator. It is shown that the redesigned digital states closely match the continuous-time optimal states. It is also shown that the digital redesigned state-feedback control law based on the bilinear transformation method is a class of the proposed control law. The digital redesign technique is then extended to find the digital version of the continuous-time optimal observer. It is shown that the states of the redesigned digital observer closely match those of the continuous-time optimal observer. C1 UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204. RP SUNKEL, JW (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 11 TC 22 Z9 25 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 JUL-AUG PY 1991 VL 14 IS 4 BP 712 EP 723 DI 10.2514/3.20704 PG 12 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FX916 UT WOS:A1991FX91600002 ER PT J AU WIE, B HORTA, L SULLA, J AF WIE, B HORTA, L SULLA, J TI CLASSICAL CONTROL-SYSTEM DESIGN AND EXPERIMENT FOR THE MINI-MAST TRUSS STRUCTURE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper describes control system design and experimental test results for the Mini-Mast truss structure located at the NASA Langley Research Center. Simple classical controllers and their ground test results are presented as a benchmark design for the Mini-Mast. The concepts of non-minimum-phase compensation and periodic disturbance rejection control are experimentally validated. The practicality of a sensor decoupling approach for the classical single-input and single-output control design is also demonstrated. The test results that clearly indicate the undesirable effect of phase lag caused by computational delay and prefiltering are discussed. C1 NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. RP WIE, B (reprint author), ARIZONA STATE UNIV,DEPT MECH & AEROSP ENGN,TEMPE,AZ 85287, USA. NR 13 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1991 VL 14 IS 4 BP 778 EP 784 DI 10.2514/3.20712 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FX916 UT WOS:A1991FX91600010 ER PT J AU MENON, PKA KIM, E CHENG, VHL AF MENON, PKA KIM, E CHENG, VHL TI OPTIMAL TRAJECTORY SYNTHESIS FOR TERRAIN-FOLLOWING FLIGHT SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A methodology for optimal trajectory planning useful for the nap-of-the-Earth guidance of helicopters is presented. This approach employs an adjoint-control transformation together with a one-dimensional search scheme for generating the time-terrain masking optimal trajectories. The trajectory planning problem bears a striking resemblance to the classical Zermelo's problem in the calculus of variations. In addition to being useful for helicopter nap-of-the-Earth guidance, the trajectory planning solution is of interest in several other contexts, such as robotic vehicle guidance and terrain-following guidance for cruise missiles and aircraft. A distinguishing feature of the present research is that the terrain constraint and threat envelopes are incorporated into the vehicle equations of motion. Second-order necessary conditions for this problem are examined. C1 NASA,AMES RES CTR,AIRCRAFT GUIDANCE & NAVIGAT BRANCH,MOFFETT FIELD,CA 94035. GEORGIA INST TECHNOL,SCH AEROSP ENGN,ATLANTA,GA 30332. RP MENON, PKA (reprint author), NASA,AMES RES CTR,MAIL STOP 210-9,MOFFETT FIELD,CA 94035, USA. NR 23 TC 23 Z9 37 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 JUL-AUG PY 1991 VL 14 IS 4 BP 807 EP 813 DI 10.2514/3.20716 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FX916 UT WOS:A1991FX91600014 ER PT J AU POWELL, RW SHAUGHNESSY, JD CRUZ, CI NAFTEL, JC AF POWELL, RW SHAUGHNESSY, JD CRUZ, CI NAFTEL, JC TI ASCENT PERFORMANCE OF AN AIR-BREATHING HORIZONTAL-TAKEOFF LAUNCH VEHICLE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Advanced manned launch systems studies underway at the NASA Langley Research Center are part of a broad effort examination of options for the next manned space transportation system to be developed by the United States. One promising concept that uses advanced technologies is a fully reusable, single-stage horizontal-takeoff vehicle that uses airbreathing propulsion. This paper discusses some potential ascent issues that could influence the design of this class of launch vehicles. Two issues are identified. The first issue is that the drag losses due to aerodynamic trim can require a significant fraction of the total energy required to achieve orbit. The second issue is the difficulty in achieving precision insertions with a vehicle that coasts unpowered from a high dynamic pressure to orbit. C1 NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,HAMPTON,VA 23665. RP POWELL, RW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 12 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1991 VL 14 IS 4 BP 834 EP 839 DI 10.2514/3.20719 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FX916 UT WOS:A1991FX91600017 ER PT J AU DAVIS, TJ ERZBERGER, H GREEN, SM NEDELL, W AF DAVIS, TJ ERZBERGER, H GREEN, SM NEDELL, W TI DESIGN AND EVALUATION OF AN AIR-TRAFFIC-CONTROL FINAL APPROACH SPACING TOOL SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper describes the design and simulator evaluation of an automation tool for assisting terminal radar approach controllers in sequencing and spacing traffic onto the final approach course. The automation tool, referred to as the Final Approach Spacing Tool (FAST), displays speed and heading advisories for arriving aircraft as well as sequencing information on the controller's radar display. The main functional elements of FAST are a scheduler that schedules and sequences the traffic, a four-dimensional trajectory synthesizer that generates the advisories, and a graphical interface that displays the information to the controller. FAST has been implemented on a high-performance workstation. It can be operated as a stand-alone in the terminal radar approach control facility or as an element of a system integrated with automation tools in the air route traffic control center. FAST was evaluated by experienced air traffic controllers in a real-time air traffic control simulation. Simulation results summarized in the paper show that the automation tools significantly reduced controller work load and demonstrated a potential for an increase in landing rate. C1 SAN JOSE STATE UNIV,DEPT METEOROL,SAN JOSE,CA 95106. RP DAVIS, TJ (reprint author), NASA,AMES RES CTR,AIRCRAFT GUIDANCE & NAVIGAT BRANCH,MAIL STOP 210-9,MOFFETT FIELD,CA 94035, USA. NR 12 TC 13 Z9 13 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1991 VL 14 IS 4 BP 848 EP 854 DI 10.2514/3.20721 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FX916 UT WOS:A1991FX91600019 ER PT J AU DISTEFANO, S RAMESHAM, R FITZGERALD, DJ AF DISTEFANO, S RAMESHAM, R FITZGERALD, DJ TI EFFECT OF CHROMIUM AND PHOSPHORUS ON THE PHYSICAL-PROPERTIES OF IRON AND TITANIUM-BASED AMORPHOUS METALLIC ALLOY-FILMS SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID CORROSION BEHAVIOR; RESISTANCE; CHLORIDE; GLASSES AB Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. We report some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique. The films were characterized using differential scanning calorimetry (DSC), stress analysis, scanning electron microscopy (SEM), x-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), electron microprobe, and potentiodynamic polarization technique. RP DISTEFANO, S (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 1 Z9 1 U1 1 U2 1 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 JUL PY 1991 VL 6 IS 7 BP 1477 EP 1483 DI 10.1557/JMR.1991.1477 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA FV269 UT WOS:A1991FV26900012 ER PT J AU RAJ, SV AF RAJ, SV TI CREEP-BEHAVIOR OF CU-30-PERCENT ZN AT INTERMEDIATE TEMPERATURES SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SOLID-SOLUTION ALLOYS; INSTANTANEOUS PLASTIC STRAIN; STEADY-STATE CREEP; 70-30 ALPHA-BRASS; VISCOUS GLIDE; STRESS; MECHANISM AB The creep properties of single-phase Cu-30% Zn alpha brass were investigated in the intermediate temperature range 573-823 K (0.48-0.70 T(m), where T(m) is the absolute melting point). Inverse, linear, and sigmoidal primary creep transients were usually observed above 573 K under stresses resulting in minimum creep rates between 10(-7) and 2 x 10(-4)s-1, while normal primary creep occurred under all other conditions. The creep stress exponent decreased from about 5.4 at 573 K to about 4.1 above 623 K, and the activation energy for creep varied between 170 and 180 kJ mol-1. A detailed analysis of the data, as well as a review of the literature, suggests that no clearly defined class M to class A to class M transition exists in this alloy, although the characteristics of both class A and class M behaviour are observed under nominally similar stresses and temperatures. It is concluded that Cu-30% Zn does not conform to the normally accepted characterization of class A or class M solid solution alloys. RP RAJ, SV (reprint author), NASA,LEWIS RES CTR,MS 49-1,BROOKPK RD,CLEVELAND,OH 44135, USA. NR 54 TC 7 Z9 7 U1 0 U2 1 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD JUL 1 PY 1991 VL 26 IS 13 BP 3533 EP 3543 DI 10.1007/BF00557142 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA FX071 UT WOS:A1991FX07100018 ER PT J AU CAI, LZ CHAO, TH AF CAI, LZ CHAO, TH TI ONE-STEP ENCODING TECHNIQUE FOR COLOR FILM STORAGE USING AN IMAGING GRATING INTERFEROMETER SO JOURNAL OF MODERN OPTICS LA English DT Article ID ARCHIVAL STORAGE; LIGHT AB A one-step encoding technique for colour image storage on monochrome film is introduced. The encoding of colour image is achieved in a noncontract single-exposure process with the use of a three-channel, two-grating imaging interferometer. A white light source is utilized in both the recording and retrieving. Experimental demonstration with a full-colour image is presented. The simplicity and low cost of this method make it particularly suited for large-scale film storage. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CAI, LZ (reprint author), SHANDONG UNIV,DEPT OPT,JINAN 250100,PEOPLES R CHINA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD JUL PY 1991 VL 38 IS 7 BP 1303 EP 1308 DI 10.1080/09500349114551471 PG 6 WC Optics SC Optics GA FW410 UT WOS:A1991FW41000010 ER PT J AU GIVER, LP CHACKERIAN, C AF GIVER, LP CHACKERIAN, C TI ROVIBRATIONAL INTENSITIES FOR THE (3110)IV[-(0000) BAND OF (CO2)-C-12-O-16 AT 4416 CM-1 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID MU-M; CARBON-DIOXIDE; ABSOLUTE; SPECTRA; REGION RP GIVER, LP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 12 TC 11 Z9 11 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1991 VL 148 IS 1 BP 80 EP 85 DI 10.1016/0022-2852(91)90036-A PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FR895 UT WOS:A1991FR89500008 ER PT J AU RINSLAND, CP ZANDER, R GOLDMAN, A MURCRAY, FJ MURCRAY, DG GUNSON, MR FARMER, CB AF RINSLAND, CP ZANDER, R GOLDMAN, A MURCRAY, FJ MURCRAY, DG GUNSON, MR FARMER, CB TI THE FUNDAMENTAL QUADRUPOLE BAND OF N-2(14) - LINE POSITIONS FROM HIGH-RESOLUTION STRATOSPHERIC SOLAR ABSORPTION-SPECTRA SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Note ID EMISSION-SPECTRUM; SPECTROSCOPY; CONSTITUENTS; ASSIGNMENTS; NITROGEN; N2O C1 UNIV LIEGE,INST ASTROPHYS,B-4200 LIEGE,BELGIUM. UNIV COLORADO,DEPT PHYS,DENVER,CO 80202. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23665, USA. NR 23 TC 13 Z9 13 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1991 VL 148 IS 1 BP 274 EP 279 DI 10.1016/0022-2852(91)90055-F PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FR895 UT WOS:A1991FR89500027 ER PT J AU DRUMMOND, CK AF DRUMMOND, CK TI TRANSIENT FLOW THRUST PREDICTION FOR AN EJECTOR PROPULSION CONCEPT 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, SOC AUTOMOT ENGINEERS, AMER SOC ENGN EDUC AB A new method for predicting transient thrust augmenting ejector characteristics is presented. The transient flow model blends a self-similar turbulent jet description, a mixing region control volume representation, and a primary-to-secondary energy exchange approximation. Since pressure is considered the forcing function in the inlet and diffuser, analysis of those regions is simplified by a quasi-steady flow assumption. The focus of the control volume analysis on the mixing region corresponds with the viscous-dominated phenomenon central to thrust augmentation. A discussion of important modeling assumptions and results from preliminary calculations is given. RP DRUMMOND, CK (reprint author), NASA,LEWIS RES CTR,SUPERSON & POWERED LIFT BRANCH,CLEVELAND,OH 44135, USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1991 VL 7 IS 4 BP 465 EP 466 DI 10.2514/3.23349 PG 2 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300001 ER PT J AU INGEBO, RD AF INGEBO, RD TI GAS PROPERTY EFFECTS ON DROPSIZE OF SIMULATED FUEL SPRAYS 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, SOC AUTOMOT ENGINEERS, AMER SOC ENGN EDUC ID SIZE AB Two-phase flow in pneumatic two-fluid fuel nozzles was experimentally investigated to determine the effect of gas properties on liquid-jet breakup in sonic-velocity gas flow. Dropsize data were obtained for the following atomizing gases: nitrogen, argon, carbon dioxide, and helium. The ratio of liquid-jet diameter to Sauter mean diameter (SMD) D0/D32 was correlated with aerodynamic and liquid-surface forces based on the product of the Weber and Reynolds number WeRe and gas-to-liquid density ratio with breakup forces produced by using different atomizing gases, a molecular-scale dimensionless group was derived, (rho-l)V3/g mu-g. As a result, a semiempirical correlating expression was obtained that can be used in the design of fuel injectors for gas turbine and rocket combustors. This expression for liquid-jet breakup in two-fluid atomizer shows that D32 approximately (rho-(g)V(c))-1.33, where (rho-g)V(c) is gas mass-flux at sonic velocity, and this agrees well with atomization theory for liquid-jet breakup in high velocity gas flow. Also, it was found that at the same gas mass-flux (rho-g)V(c), helium was considerably more effective than nitrogen in producing small droplet sprays with SMDs in the order of 5 mu-m. This was attributed to the high acoustic velocity of helium. RP INGEBO, RD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 2 Z9 2 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1991 VL 7 IS 4 BP 467 EP 472 DI 10.2514/3.23350 PG 6 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300002 ER PT J AU SOLA, FL AF SOLA, FL TI DEVELOPMENT OF THE EXPLORER SOLID ROCKET MOTOR SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The successful launching of Explorer I on an accelerated schedule was due in part to the extensive design and developmental testing effort accomplished in support of the U.S. Army's Sergeant missile system. The 1/5-scale solid rocket motor used in the missile developmental in conjunction with a modified Redstone rocket became the basis for the Jupiter-C launch vehicle, which launched the first U.S. satellite. A description of the solid rocket motor and its development for use as part of the upper stages of the Jupiter-C is presented. RP SOLA, FL (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1991 VL 7 IS 4 BP 513 EP 517 DI 10.2514/3.23356 PG 5 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300008 ER PT J AU MARTIN, JA MANSKI, D AF MARTIN, JA MANSKI, D TI VARIABLE-MIXTURE-RATIO AND OTHER ROCKET ENGINES FOR ADVANCED SHUTTLES SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Computer models of rocket engines and single-stage-to-orbit vehicles that were developed previously and recently combined have now been extended to include variable-mixture-ratio engines and two-stage vehicles. The variable-mixture-ratio engine is of interest because it offers the opportunity for reduced vehicle dry mass relative to single-mixture-ratio engines without the operational complexity of two fuels or two engine designs. Two-stage vehicles are of interest because the next generation of advanced launch vehicles probably will not use a sufficiently high level of technology to allow a single-stage vehicle to be a reasonable choice from the standpoint of technical risk and economics. Results are presented for vertical-takeoff, horizontal-landing, winged, manned, fully reusable vehicles with a payload of 13.6 Mg (30,000 lb) to low Earth orbit. Both single-stage and two-stage vehicles are included. Hydrogen, methane, and propane engines were studied with a staged-combustion cycle. Optimizations included the nozzle exit pressure, thrust split between the booster and orbiter, chamber pressure, and mixture ratio. C1 DLR GERMAN AEROSP RES ESTAB,INST CHEM PROPULS,W-7101 LAMPOLOSHAUSEN,GERMANY. RP MARTIN, JA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 365,HAMPTON,VA 23665, USA. NR 5 TC 4 Z9 5 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 JUL-AUG PY 1991 VL 7 IS 4 BP 549 EP 555 DI 10.2514/3.23361 PG 7 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300013 ER PT J AU HUNG, RJ LEE, CC LESLIE, FW AF HUNG, RJ LEE, CC LESLIE, FW TI RESPONSE OF GRAVITY LEVEL FLUCTUATIONS ON THE GRAVITY PROBE-B SPACECRAFT PROPELLANT SYSTEM SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID ROTATING BUBBLE; FILLED CYLINDER; SPIN-UP; ENVIRONMENT AB The dynamical behavior of fluids, in particular, the effect of surface tension on partially filled fluids in a rotating dewar under microgravity environment, has been investigated. Results show that there is a group of wave trains, both in longitudinal and transverse modes, with various frequencies and wavelengths of slosh waves generated by the restoring force field of gravity jitters and centrifugal forces in this study. The longest wave periods of slosh waves, either the longitudinal or transverse modes, are responsible for the production of wave modes with the highest ratio of maximum wave amplitude to wavelength. Also, the lower frequency slosh waves are the wave modes with higher wave energy than that of the higher frequency slosh waves. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812. RP HUNG, RJ (reprint author), UNIV ALABAMA,DEPT MECH ENGN,HUNTSVILLE,AL 35899, USA. NR 29 TC 19 Z9 19 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 JUL-AUG PY 1991 VL 7 IS 4 BP 556 EP 564 DI 10.2514/3.23362 PG 9 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300014 ER PT J AU KING, RA CREEL, TR BUSHNELL, DM AF KING, RA CREEL, TR BUSHNELL, DM TI EXPERIMENTAL TRANSITION INVESTIGATION OF A FREE-SHEAR LAYER ABOVE A CAVITY AT MACH 3.5 SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID TURBULENT AB The transition behavior of a free-shear layer above a cavity with high and low levels of freestream acoustic disturbances has been investigated at Mach 3.5. Optical, mean pitot pressure, and hot-wire techniques were used to detect transition locations. The transition Reynolds numbers obtained were between Re(Tr) = 363,000 and 530,000, in good agreement with previous (conventional, high noise facility) results. The study indicated that the effects of lowering freestream noise on Re(Tr) were minimal but, as expected, favorable (higher Re(Tr)). However, hot-wire anemometry indicated that the shear layer disturbance growth differed considerably for high and low noise levels. Also, the growth frequencies are considerably below expectations from linear stability theory. Correlations between hot-film sensors mounted on the cavity floor indicated the presence of disturbances, believed to be vorticity and/or entropy waves, convecting upstream at about 7.2-11.5% of the freestream velocity. Upstream convected disturbances (acoustic as well as the vorticity/entropy waves indicated herein) are believed to be at least partially responsible for the insensitivity of Re(Tr) to the freestream acoustic disturbance field. RP KING, RA (reprint author), NASA,LANGLEY RES CTR,DIV BRANCH FLUID,EXPTL FLOW PHYS,HAMPTON,VA 23665, USA. NR 35 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1991 VL 7 IS 4 BP 626 EP 634 DI 10.2514/3.23371 PG 9 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300023 ER PT J AU TOWNSEND, DP BAMBERGER, EN AF TOWNSEND, DP BAMBERGER, EN TI SURFACE FATIGUE LIFE OF M50NIL AND AISI 9310 GEARS AND ROLLING-CONTACT BARS 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, SOC AUTOMOT ENGINEERS, AMER SOC ENGN EDUC AB Spur gear endurance tests and rolling-element surface fatigue tests were conducted to investigate vacuum-induction-melted, vacuum-arc-remelted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling-contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 3.5 in. Gear test conditions were an inlet oil temperature of 116-degrees-F, an outlet oil temperature of 170-degrees-F, a maximum Hertz stress of 248 ksi, and a speed of 10,000 rpm. Bench rolling-element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 700 VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling-contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and to have fatigue life far superior to that of both VIM-VAR and VAR AISI 9310 gears and rolling-contact bars. C1 GE,BEARINGS & DRIVE UNIT,CINCINNATI,OH. RP TOWNSEND, DP (reprint author), NASA,LEWIS RES CTR,GEAR RES,CLEVELAND,OH 44135, USA. NR 9 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1991 VL 7 IS 4 BP 642 EP 649 DI 10.2514/3.23373 PG 8 WC Engineering, Aerospace SC Engineering GA FY513 UT WOS:A1991FY51300025 ER PT J AU BRAUN, RD POWELL, RW AF BRAUN, RD POWELL, RW TI AERODYNAMIC REQUIREMENTS OF A MANNED MARS AEROBRAKING TRANSFER VEHICLE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB In this investigation, entry corridor analyses are performed to identify the aerodynamic requirements of a manned Mars aerobraking transfer vehicle. The major emphasis is on identifying the required aerobrake hypersonic lift-to-drag ratio (L/D) to insure a successful aerocapture. Aerobraking entry requirements are also imposed on a set of interplanetary mission opportunities to demonstrate their effect on mission flexibility. The entry corridor analyses are performed with the use of an adaptive atmospheric guidance algorithm that utilizes bank-angle modulation to relieve the high deceleration loads characteristic of interplanetary aerocapture and maximize the width of the flyable entry corridor. Based on the requirements of a 1-deg corridor width, deceleration into a parking orbit with an apoapsis altitude of 33,640 km, and a 5-g deceleration limit, this analysis has shown that a manned Mars aerobrake characterized by an L/D of at least 1.5 is required for entry velocities as high as 10.0 km/s. If Mars entry is limited to velocities below 8.5 km/s, a minimum L/D of 0.5 is required; over a very limited entry velocity range, an aerobrake with L/D of 0.3 is feasible. Limiting the Mars entry velocity to values below 8.5 km/s is shown to induce a minor restriction on mission flexibility while alleviating aerothermodynamic and vehicle packaging concerns; hence, Mars entry velocities in the range of 6.0-8.5 km/s are suggested, and a manned Mars aerobrake characterized by an L/D between 0.3 and 0.5 is recommended. RP BRAUN, RD (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MS 365,HAMPTON,VA 23665, USA. NR 15 TC 9 Z9 10 U1 0 U2 3 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 JUL-AUG PY 1991 VL 28 IS 4 BP 361 EP 367 DI 10.2514/3.26255 PG 7 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200001 ER PT J AU BLANCHARD, RC AF BLANCHARD, RC TI RAREFIED-FLOW AERODYNAMICS MEASUREMENT EXPERIMENT ON THE AEROASSIST FLIGHT EXPERIMENT VEHICLE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ACCELEROMETER PACKAGE EXPERIMENT; SHUTTLE AB A flight experiment, called the Rarefield-Flow Aerodynamic Flight Experiment (RAME), is currently planned for the Aeroassist Flight Experiment (AFE) mission. This mission is a NASA sponsored precursor design tool for aeroassist orbital transfer vehicles. The RAME is one of 12 planned experiments on the AFE vehicle and will use flight measurements from accelerometers, rate gyros, and pressure transducers combined with knowledge of vehicle inflight mass properties and trajectory to achieve the primary objective of measuring aerodynamic forces and moments in the rarefied-flow environment, including transition into the hypersonic continuum. The experiment design utilizes preflight estimates of the aerodynamic measurements that are based on environment models, computer flowfield simulations, and ground test results. A secondary RAME objective is a postflight evaluation of the determination of vehicle mass properties from flight data. The experiment plan includes requirements for maneuvers that facilitate the determination of vehicle mass properties and aerodynamic characteristics. The aerodynamic maneuvers occur at several altitudes during flight. This provides an opportunity to examine gas-surface accommodation effects on aerodynamic coefficients in an environment of changing atmospheric composition. An overview is given on the RAME objectives, measurement domain, and anticipated results. RP BLANCHARD, RC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 366,HAMPTON,VA 23665, USA. NR 25 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 JUL-AUG PY 1991 VL 28 IS 4 BP 368 EP 375 DI 10.2514/3.26256 PG 8 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200002 ER PT J AU SHEBALIN, JV AF SHEBALIN, JV TI AEROBRAKE PLASMADYNAMICS - MACROSCOPIC EFFECTS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SPONTANEOUS MAGNETIC-FIELDS; LASER-PRODUCED PLASMAS; GENERATION; TURBULENCE AB The flow around an aerobraking spacecraft (such as the aeroassist flight experiment re-entry vehicle) will contain a region of partially ionized gas, that is, a plasma. It is shown here by numerical simulation that macroscopic plasmadynamic effects (which are not included in standard aerothermodynamic simulations) will have a noticeable effect on the re-entry flowfield. In particular, there are thermoelectric phenomena that can have a major influence in flow dynamics at the front of an ionizing bowshock. These thermoelectric phenomena arise because of the presence of large density and temperature gradients at the front of a re-entry bowshock, and they include strong local magnetic fields, electric currents, and ohmic heating. One important result is the dramatic increase in temperature (over the case where plasma effects are neglected) at a re-entry shock front. The implication is that macroscopic plasmadynamic effects can no longer be neglected in aerothermodynamic simulations of hypersonic re-entry flowfields. RP SHEBALIN, JV (reprint author), NASA,LANGLEY RES CTR,ANTENNA & MICROWAVE RES BRANCH,HAMPTON,VA 23665, USA. NR 24 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 JUL-AUG PY 1991 VL 28 IS 4 BP 394 EP 400 DI 10.2514/3.26258 PG 7 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200005 ER PT J AU KIM, SC VANOVERBEKE, TJ AF KIM, SC VANOVERBEKE, TJ TI PERFORMANCE AND FLOW CALCULATIONS FOR A GASEOUS H2/O2 THRUSTER SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Calculations were made for the gaseous H2/O2 thruster designed for the space station by using the RPLUS code that employs an implicit finite-volume, lower-upper symmetric successive over-relaxation scheme to solve the Navier-Stokes equations and the species equations in a coupled manner. The combustion processes of hydrogen and oxygen are modeled by an 8-species and 18-step reaction mechanism, and the turbulence is simulated by the Baldwin-Lomax turbulence model for the thruster wall boundary layer and the modified Prandtl's mixing length model for the reacting shear layer. Results are presented for different mixture ratios and fuel film-cooling percents and compared with the experimental data. The calculated performance predictions for the thruster agree well with the experimental data, and the results demonstrate that the RPLUS code can be used for analysis of thrusters and rockets. C1 NASA,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP KIM, SC (reprint author), SVERDRUP TECHNOL INC,MS 5-11,21000 BROOKPK RD,BROOK PK,OH 44142, USA. NR 15 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1991 VL 28 IS 4 BP 433 EP 438 DI 10.2514/3.26263 PG 6 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200010 ER PT J AU MIKULAS, MM COLLINS, TJ HEDGEPETH, JM AF MIKULAS, MM COLLINS, TJ HEDGEPETH, JM TI PRELIMINARY DESIGN CONSIDERATIONS FOR 10-40 METER-DIAMETER PRECISION TRUSS REFLECTORS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A simplified preliminary design capability for erectable precision segmented reflectors is presented. This design capability permits a rapid assessment of a wide range of reflector parameters as well as new structural concepts and materials. The preliminary design approach was applied to a range of precision reflectors from 10 to 100 m in diameter while considering standard design drivers. The design drivers considered were weight, fundamental frequency, launch packaging volume, part count, and on-orbit assembly time. For the range of parameters considered, on-orbit assembly time was identified as the major design driver. C1 ASTRO AEROSP CORP,CARPINTERIA,CA 93013. RP MIKULAS, MM (reprint author), NASA,LANGLEY RES CTR,STRUCT CONCEPTS BRANCH,MS 199,HAMPTON,VA 23665, USA. NR 16 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1991 VL 28 IS 4 BP 439 EP 447 DI 10.2514/3.26264 PG 9 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200011 ER PT J AU WALYUS, KD DALTON, C AF WALYUS, KD DALTON, C TI APPROACH AND LANDING SIMULATOR FOR SPACE-SHUTTLE ORBITER TOUCHDOWN CONDITIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This study describes a computer simulation that provides an accurate calculation of the touchdown conditions. The program is small enough to operate on a personal computer. The program simulates the Orbiter trajectory from an altitude of 10,000 ft to the Earth's surface. It assumes the Orbiter flies close to its reference altitude profile, with negligible crosswind effects. Flight data have proven both assumptions to be valid. By incorporating these assumptions with the Shuttle guidance logic, a quick approximation can be made of the touchdown speed and downrange distance to an accuracy within 400 ft of the mainframe prediction. C1 UNIV HOUSTON,DEPT MECH ENGN,HOUSTON,TX 77204. RP WALYUS, KD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 4 TC 3 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1991 VL 28 IS 4 BP 478 EP 485 DI 10.2514/3.26269 PG 8 WC Engineering, Aerospace SC Engineering GA GB522 UT WOS:A1991GB52200016 ER PT J AU DECOU, AB AF DECOU, AB TI ORBITAL STATION-KEEPING FOR MULTIPLE SPACECRAFT INTERFEROMETRY SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This paper presents a three-satellite station-keeping strategy that is applicable to very long (1-100 km) baseline optical interferometry in space using the "free-flyer" approach. The relative positions of the satellites in an arbitrarily oriented inertial coordinate system are described parametrically and the continuous thrust vectors required to follow the paths are derived. The paths, which are constrained to be in the U-V plane of an astronomical source (a plane perpendicular to the direction of the source), are always chosen to maximize the use of gravity gradient forces and minimize the use of thrusting which can easily be provided by ion thrusters. Two different thrust programs are presented. One allows the interferometer to take data over an elliptic-shaped area of the U-V plane of arbitrary size for astronomical sources in any direction except close to the orbit plane of the system. The second thrust program reorients the U-V plane from one arbitrary source direction to another. The maximum thrust and the total DELTA-V required to implement these strategies are found to be surprisingly low. They do not require refueling for a 10-year mission in geo-synchronous orbit. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP DECOU, AB (reprint author), NO ARIZONA UNIV,ENGN,FLAGSTAFF,AZ 86011, USA. NR 9 TC 30 Z9 31 U1 1 U2 1 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 JUL-SEP PY 1991 VL 39 IS 3 BP 283 EP 297 PG 15 WC Engineering, Aerospace SC Engineering GA GB885 UT WOS:A1991GB88500002 ER PT J AU STRIEPE, SA BRAUN, RD AF STRIEPE, SA BRAUN, RD TI EFFECTS OF A VENUS SWINGBY PERIAPSIS BURN DURING AN EARTH-MARS TRAJECTORY SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB Interplanetary missions were analyzed that utilize the gravity-assist orbital transfer technique to increase mission capabilities. Ordinarily, this swingby maneuver provides a non-propulsive change in the spacecraft heliocentric energy that can reduce the amount of propellant needed to complete an interplanetary mission. For certain planetary orientations, incorporating a single propulsive maneuver at the periapsis of the swingby trajectory can decrease the mission propellant requirement. This decrease results in a reduced initial vehicle mass in low-Earth orbit (from one- to 28- percent lower than for the unpowered swingby maneuvers in one-third of the cases investigated). This study analyzed the feasibility of using a powered swingby to reduce the initial vehicle size for an excursion class Mars mission during the 2010-2025 time frame. RP STRIEPE, SA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 8 TC 20 Z9 20 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 JUL-SEP PY 1991 VL 39 IS 3 BP 299 EP 312 PG 14 WC Engineering, Aerospace SC Engineering GA GB885 UT WOS:A1991GB88500003 ER PT J AU MARKLEY, FL AF MARKLEY, FL TI ATTITUDE DETERMINATION AND PARAMETER-ESTIMATION USING VECTOR OBSERVATIONS - APPLICATION SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB This paper presents tests of a new method for the simultaneous estimation of spacecraft attitude and sensor biases, based on a quaternion estimation algorithm minimizing Wahba's loss function. The new method is compared with a conventional batch least-squares differential correction algorithm. The estimates are based on data from strap-down gyros and star trackers, simulated with varying levels of Gaussian noise for both inertially-fixed and Earth-pointing attitudes. Both algorithms solve for the spacecraft attitude and the gyro drift rate biases. In the majority of tests performed, the two methods converge to the same estimates in approximately the same number of iterations, but the new algorithm requires about 60 percent more computational effort. Three cases were found in which the new method converges in fewer iterations than the differential correction, but neither method gave accurate estimates in two of these cases. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CONTROL SYST SOFTWARE & SIMULAT SECT,CODE 712-1,GREENBELT,MD 20771, USA. NR 13 TC 15 Z9 16 U1 0 U2 1 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 JUL-SEP PY 1991 VL 39 IS 3 BP 367 EP 381 PG 15 WC Engineering, Aerospace SC Engineering GA GB885 UT WOS:A1991GB88500007 ER PT J AU CHOU, MD AF CHOU, MD TI THE DERIVATION OF CLOUD PARAMETERS FROM SATELLITE-MEASURED RADIANCES FOR USE IN SURFACE RADIATION CALCULATIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID REFLECTED SOLAR-RADIATION; MARINE STRATOCUMULUS; ABSORPTION; FIELDS AB A simple scheme is developed to infer cloud amount, optical thickness, and height from satellite-measured radiances for use in surface radiation calculations. The essence of the cloud scheme is to specify a cloud reflectivity threshold for identifying pixels that are likely to be totally filled with clouds. Area-averaged values for the three cloud parameters are derived from the reflectivities of these cloudy pixels and the satellite-measured radiances in the visible and IR window channels. By applying the cloud scheme to the ISCCP (International Satellite Cloud Climatology Project) B3 radiance data and using a radiation routine, the surface radiative fluxes are computed for the tropical and subtropical western Pacific regions (30-degrees-S-30-degrees-N, 100-degrees-E-180-degrees). It is found that the three cloud parameters are quite sensitive to the cloud reflectivity threshold, but the surface radiation is rather insensitive to the set of cloud parameters inferred by a scheme that is directly dependent upon the satellite radiance measurements. Over a broad area in the tropical and subtropical western Pacific regions, the difference in the net surface radiative fluxes is < 2 W m-2 for the cloud reflectivity thresholds of 0.3 and 0.4. This study further strengthens the view of other investigators that the net solar flux at the surface can be linearly related to the net solar flux at the top of the atmosphere. For a given amount of solar radiation absorbed by the earth-atmosphere system, the partition of the absorption between the surface and the atmosphere is affected by the solar zenith angle. As a result, the solar zenith angle has a significant effect on the relationship between the fluxes at the surface and at the top of the atmosphere. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 19 TC 14 Z9 15 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 JUL 1 PY 1991 VL 48 IS 13 BP 1549 EP 1559 DI 10.1175/1520-0469(1991)048<1549:TDOCPF>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GB218 UT WOS:A1991GB21800004 ER PT J AU SUD, YC CHAO, WC WALKER, GK AF SUD, YC CHAO, WC WALKER, GK TI CONTRIBUTIONS TO THE IMPLEMENTATION OF THE ARAKAWA-SCHUBERT CUMULUS PARAMETERIZATION IN THE GLA GCM SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID LARGE-SCALE ENVIRONMENT; CLOUD ENSEMBLE AB Several integrations were made with a coarse (4-degrees X 5-degrees nine-sigma level) version of the GLA GCM, which has the Arakawa-Schubert cumulus parameterization, predicted fractional cloud cover, and a parameterization of evaporation of falling rainfall. All model simulation experiments started from the ECMWF analysis for 15 December 1982 and were integrated until 31 January 1983 using climatological boundary conditions. The first ten days of model integrations show that the model-simulated tropics dries and warms as a result of excessive precipitation. Three types of model development-cum-analysis studies were made with the cumulus scheme. First, the Critical Cloud Work Function (CCWF) dataset for different sigma layers were reworked using the Cloud Work Function (CWF) database of Lord et al. as representative of time-average CWF and not the actual CCWF values as in the Arakawa-Schubert implementation of cumulus convection. The experiments with the new CCWF dataset helped to delineate the influence of changing CCWF on model simulations. Larger values of CCWF partially alleviated the problem of excessive heating and drying during spinup and sharpened the tropical ITCZ (Intertropical Convergence Zone). Second, by comparing two simulations, one with and one without cumulus convection, the role of cumulus convection in maintaining the observed tropical rainfall and 850 mb easterly winds is clarified. Third, by using Simpson's relations between cloud radii and cumulus entrainment parameter, lambda, in the Arakawa-Schubert cumulus scheme, realistic upper and lower bounds on lambda were obtained. This improvement had a significant impact on the time evolution of tropical temperature and humidity simulation. It also significantly suppressed the excessive rainfall during spinup. Finally, by invoking lambda-min = 0.0002 m-1 (R(max) = 1.00 km) another simulation was made. In this simulation, not only the excessive initial rainfall was virtually eliminated, but a more realistic vertical distribution of specific humidity in the tropics was produced. Despite the conceptual simplicity of the latter, it has made some very significant improvement to the monthly simulation in the tropics. RP SUD, YC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GLOBAL MODELING & SIMULAT BRANCH,GREENBELT,MD 20771, USA. NR 22 TC 17 Z9 17 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 JUL 1 PY 1991 VL 48 IS 13 BP 1573 EP 1586 DI 10.1175/1520-0469(1991)048<1573:CTTIOT>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GB218 UT WOS:A1991GB21800006 ER PT J AU POKELA, PJ KOLAWA, E NICOLET, MA RUIZ, R AF POKELA, PJ KOLAWA, E NICOLET, MA RUIZ, R TI AMORPHOUS TERNARY TA-SI-N DIFFUSION BARRIER BETWEEN SI AND AU SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article AB Reactively sputtered Ta-Si-N films are investigated as diffusion barriers between silicon and Au layers. Analyses by backscattering spectrometry and electrical measurements on shallow n+p junction diodes reveal that an-amorphous Ta36Si14N50 thin film approximately 110 nm thick very effectively preserves the integrity of the metallization on shallow junctions up to 30 min annealing at 750-degrees-C in vacuum. (The Au-Si eutectic is at 360-degrees-C). At that temperature small openings appear in the Au overlayer which do not, however, affect the electrical characteristics of the diodes. Destructive metallurgical interactions occur at higher temperatures causing a shorting of the shallow junction diodes. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP POKELA, PJ (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 10 TC 13 Z9 13 U1 0 U2 0 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 JUL PY 1991 VL 138 IS 7 BP 2125 EP 2129 DI 10.1149/1.2085936 PG 5 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA FW341 UT WOS:A1991FW34100047 ER PT J AU Sharma, SP Gillespie, W AF Sharma, Surendra P. Gillespie, Walter TI Nonequilibrium and Equilibrium Shock Front Radiation Measurements SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The intensities of the radiation emitted behind a normal shock wave in nitrogen were measured in an electric-arc driven shock tube, at a shock velocity of 6.2 km/s. Both a time-resolved broadband radiation intensity measurement and a time-frozen spectral measurement were conducted. The time-frozen measurement was made by a 0.3-m spectrograph equipped with a 700-element linear diode array at the exit focal plane, which gave a spectral resolution of 0.3 angstrom per element. By analyzing the second positive system of N-2 in the 3153-3159-angstrom wavelength region, the rotational and vibrational temperatures are determined in both the equilibrium and the nonequilibrium regions. The results are compared with similar data obtained by the AVCO-Everett Research Laboratory during the 1960s. The relaxation times and the temperature in the equilibrium region obtained in the present experiment agree with those of AVCO, but the vibrational and rotational temperatures in the nonequilibrium region are greatly different from the AVCO results. The measured rotational temperature seems to be in nonequilibrium, contradicting the two-temperature assumption of Park, but the measured vibrational temperature agrees with Park's model. C1 [Sharma, Surendra P.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. [Gillespie, Walter] Stanford Univ, Dept Aeronaut & Astronaut, Stanford, CA 94305 USA. RP Sharma, SP (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 12 TC 37 Z9 37 U1 1 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 JUL-SEP PY 1991 VL 5 IS 3 BP 257 EP 265 DI 10.2514/3.259 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZW UT WOS:000208449300001 ER PT J AU Buelow, PE Tannehill, JC Ievalts, JO Lawrence, SL AF Buelow, Philip E. Tannehill, John C. Ievalts, John O. Lawrence, Scott L. TI Three-Dimensional, Upwind, Parabolized Navier-Stokes Code for Chemically Reacting Flows SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A new upwind, parabolized Navier-Stokes (PNS) code has been developed to compute the three-dimensional viscous flow of chemically reacting air around hypersonic vehicles. The code is a modification of the perfect gas, three-dimensional UPS code of Lawrence et al., which has been extended in the present study to permit the calculation of hypersonic, viscous flows in chemical nonequilibrium. The algorithm solves the PNS equations using a finite-volume, upwind total variation diminishing (TVD) method based on Roe's approximate Riemann solver that has been modified to account for "real gas" effects. The present code solves the fluid dynamic and specks continuity equations in a loosely coupled manner. The fluid medium is assumed to be a chemically reacting mixture of thermally perfect (but calorically imperfect) gases in thermal equilibrium. The code has been used to compute the hypersonic laminar flow of chemically reacting air over a cone at 0- and 10-deg angles of attack, and the results are compared with results from other existing upwind and central-difference, real gas PNS codes. In addition, the code has been used to compute the Mach 25 flow over a generic hypersonic vehicle. C1 [Tannehill, John C.; Ievalts, John O.] Engn Anal Inc, Ames, IA 50011 USA. [Lawrence, Scott L.] NASA, Ames Res Ctr, Appl Computat Fluid Dynam Branch, Moffett Field, CA 94035 USA. RP Buelow, PE (reprint author), Iowa State Univ, Dept Aerosp Engn & Engn Mech, Ames, IA 50011 USA. NR 32 TC 9 Z9 10 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 JUL-SEP PY 1991 VL 5 IS 3 BP 274 EP 283 DI 10.2514/3.261 PG 10 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZW UT WOS:000208449300003 ER PT J AU Wilmoth, RG AF Wilmoth, Richard G. TI Direct Simulation Monte Carlo Analysis of Rarefied Flows on Parallel Processors SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A method for executing a direct simulation Monte Carlo (DSMC) analysis using parallel processing is described. The method is based on using domain decomposition to distribute the work load among multiple processors, and the DSMC analysis is performed completely in parallel. Message passing is used to transfer molecules between processors and to provide the synchronization necessary for the correct physical simulation. Benchmark problems are described for testing the method, and results are presented that demonstrate the performance on two commercially available multicomputers. The results show that reasonable parallel speedup and efficiency can be obtained if the problem is sized properly to the number of processors. It is projected that, with a massively parallel system, performance exceeding that of current supercomputers is possible. C1 NASA, Langley Res Ctr, Div Space Syst, Aerothermodynam Branch, Hampton, VA 23665 USA. RP Wilmoth, RG (reprint author), NASA, Langley Res Ctr, Div Space Syst, Aerothermodynam Branch, Hampton, VA 23665 USA. NR 8 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 JUL-SEP PY 1991 VL 5 IS 3 BP 292 EP 300 DI 10.2514/3.263 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZW UT WOS:000208449300005 ER PT J AU Micol, JR AF Micol, John R. TI Experimental and Predicted Pressure and Heating Distributions for Aeroassist Flight Experiment Vehicle SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Pressure and laminar heat-transfer rate distributions measured over the forebody of 2.2% scale (3.67-in.-diam) models of the Aeroassist Flight Experiment vehicle in air at Mach 10 are presented for a range of angles of attack of from -10 to 10 deg. Two values of freestream Reynolds number based on model diameter in the symmetry plane of the base were tested, 1.63 and 6.48 X 10(5). Predictions from an inviscid flowfield code referred to as HALIS (High ALpha Inviscid Solution) and a Navier-Stokes solver referred to as LAURA (Langley Aerothermodynamic Upwind Relaxation Algorithm) were in good agreement with pressure measurements. Heat transfer rates predicted with the LAURA code were generally in good agreement with measurements over the cone and skirt sections but tended to underpredict measurements in the stagnation region. C1 NASA, Langley Res Ctr, Div Space Syst, Expt Hyperson Branch, Hampton, VA 23665 USA. RP Micol, JR (reprint author), NASA, Langley Res Ctr, Div Space Syst, Expt Hyperson Branch, Hampton, VA 23665 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 JUL-SEP PY 1991 VL 5 IS 3 BP 301 EP 307 DI 10.2514/3.264 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZW UT WOS:000208449300006 ER PT J AU Ramakrishnan, R Thornton, EA Wieting, AR AF Ramakrishnan, R. Thornton, E. A. Wieting, A. R. TI Adaptive Finite Element Analysis of Hypersonic Laminar Flows for Aerothermal Load Predictions SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The use of an adaptive mesh refinement procedure for analyzing hypersonic laminar flows with application to aerothermal load predictions is described. The adaptation procedure, which uses both quadrilateral and triangular elements, is implemented with the multistep Galerkin-Runge-Kutta scheme. Elements that lie in regions of strong gradients are refined based on indicators to obtain better definition of flow features. The effectiveness of the adaptive procedure is demonstrated by modeling Mach 11.7 flow over a 15-deg ramp. Numerical results are compared with predictions of strong interaction theories and experimental data. Surface quantities such as heating rates and pressure loads, critical for the effective design of high-speed vehicles, are found to be in good agreement with experimental values. C1 [Ramakrishnan, R.] Old Dominion Univ, Dept Mech & Aerosp Engn, Norfolk, VA 23508 USA. [Wieting, A. R.] NASA, Langley Res Ctr, Aerothermal Loads Branch, Struct Mech Div, Hampton, VA 23665 USA. RP Ramakrishnan, R (reprint author), Old Dominion Univ, Dept Mech & Aerosp Engn, Norfolk, VA 23508 USA. FU Aerothermal Loads Branch at NASA Langley Research Center [NSG-1321] FX The research of R. Ramakrishnan and E.A. Thornton was supported by research Grant NSG-1321 through the Aerothermal Loads Branch at NASA Langley Research Center. NR 24 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1991 VL 5 IS 3 BP 308 EP 317 DI 10.2514/3.265 PG 10 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZW UT WOS:000208449300007 ER PT J AU VIJAYARAGHAVAN, D KEITH, TG BREWE, DE AF VIJAYARAGHAVAN, D KEITH, TG BREWE, DE TI EXTENSION OF TRANSONIC FLOW COMPUTATIONAL CONCEPTS IN THE ANALYSIS OF CAVITATED BEARINGS SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article ID ALGORITHM AB In this paper, an analogy between the mathematical modeling of transonic potential flow and the flow in a cavitating bearing is described. Based on the similarities, characteristics of the cavitated region and jump conditions across the film reformation and rupture fronts are developed using the method of weak solutions. The mathematical analogy is extended by utilizing a few computational concepts of transonic flow to numerically model the cavitating bearing. Methods of shock fitting and shock capturing are discussed. Various procedures used in transonic flow computations are adapted to bearing cavitation applications, e.g., type differencing, grid transformation, an approximate factorization technique, and Newton's iteration method. These concepts have proved to be successful and have vastly improved the efficiency of numerical modeling of cavitated bearings. C1 UNIV TOLEDO,DEPT MECH ENGN,TOLEDO,OH 43606. NASA,LEWIS RES CTR,USA AVIAT RES & TECHNOL ACTIV,CLEVELAND,OH 44135. RP VIJAYARAGHAVAN, D (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 20 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 0742-4787 J9 J TRIBOL-T ASME JI J. Tribol.-Trans. ASME PD JUL PY 1991 VL 113 IS 3 BP 539 EP 546 DI 10.1115/1.2920657 PG 8 WC Engineering, Mechanical SC Engineering GA FY565 UT WOS:A1991FY56500018 ER PT J AU BOYLE, RJ AF BOYLE, RJ TI NAVIER-STOKES ANALYSIS OF TURBINE BLADE HEAT-TRANSFER 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 AB Comparisons with experimental heat transfer and surface pressures were made for seven turbine vane and blade geometries using a quasi-three-dimensional thin-layer Navier-Stokes analysis. Comparisons are made for cases with both separated and unseparated flow over a range of Reynolds numbers and free-stream turbulence intensities. The analysis used a modified Baldwin-Lomax turbulent eddy viscosity model. Modifications were made to account for the effects of: (1) free-stream turbulence on both transition and leading edge heat transfer; (2) strong favorable pressure gradients on relaminarizations; and (3) variable turbulent Prandtl number on heat transfer. In addition, the effect on heat transfer of the near-wall model of Deissler is compared with the Van Driest model. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 33 TC 21 Z9 21 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 JUL PY 1991 VL 113 IS 3 BP 392 EP 403 DI 10.1115/1.2927888 PG 12 WC Engineering, Mechanical SC Engineering GA HP740 UT WOS:A1991HP74000010 ER PT J AU CHIANG, CK MEI, C GRAY, CE AF CHIANG, CK MEI, C GRAY, CE TI FINITE-ELEMENT LARGE-AMPLITUDE FREE AND FORCED VIBRATIONS OF RECTANGULAR THIN COMPOSITE PLATES SO JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME LA English DT Article AB A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration responses of arbitrarily laminated anisotropic composite rectangular thin plates. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite rectangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The finite element results are compared with available approximate continuum solutions. The amplitude-frequency relations for convergence with gridwork refinement, different boundary conditions, aspect ratios, lamination angles, number of plies, and uniform versus concentrated loads are presented. RP CHIANG, CK (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,HAMPTON,VA 23665, USA. NR 0 TC 25 Z9 25 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 1048-9002 J9 J VIB ACOUST JI J. Vib. Acoust.-Trans. ASME PD JUL PY 1991 VL 113 IS 3 BP 309 EP 315 DI 10.1115/1.2930186 PG 7 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA HP729 UT WOS:A1991HP72900006 ER PT J AU BLODGET, HW TAYLOR, PT ROARK, JH AF BLODGET, HW TAYLOR, PT ROARK, JH TI SHORELINE CHANGES ALONG THE ROSETTA NILE PROMONTORY - MONITORING WITH SATELLITE-OBSERVATIONS SO MARINE GEOLOGY LA English DT Article ID DELTA; SUBSIDENCE AB A study to test the effectiveness of satellite data for monitoring shoreline change is reported, the rapidly changing Rosetta Promontory of the Nile Delta, Egypt, being selected as the study area. Landsat multispectral scanner (MSS) image data in the near infrared (0.8-1.1-mu-m, 80 m resolution) covering a 15 year period (1972-1987) at roughly 3 year intervals were complied. These were digitally overlain, registered and differenced relative to the initial 1972 shoreline, and composite changes (erosion and accretion) are mapped. The area studied is one undergoing both aggradation and degradation, depending on location, sediment supply and man-made barriers. It was found that the general trend of the regional processes can be monitored with Landsat imagery due to its repetitive coverage and good spectral contrast of land and sea. Improved satellite imagery with higher resolution should be a valuable tool for complementing traditional shoreline monitoring surveys in easily eroded, low-lying areas such as the Nile Delta. C1 UNIV MARYLAND,COLLEGE PK,MD 20742. RP BLODGET, HW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 29 TC 45 Z9 52 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0025-3227 J9 MAR GEOL JI Mar. Geol. PD JUL PY 1991 VL 99 IS 1-2 BP 67 EP 77 DI 10.1016/0025-3227(91)90083-G PG 11 WC Geosciences, Multidisciplinary; Oceanography SC Geology; Oceanography GA GD144 UT WOS:A1991GD14400005 ER PT J AU ROTH, DJ STANG, DB SWICKARD, SM DEGUIRE, MR DOLHERT, LE AF ROTH, DJ STANG, DB SWICKARD, SM DEGUIRE, MR DOLHERT, LE TI REVIEW, MODELING, AND STATISTICAL-ANALYSIS OF ULTRASONIC VELOCITY PORE FRACTION RELATIONS IN POLYCRYSTALLINE MATERIALS SO MATERIALS EVALUATION LA English DT Article DE ACOUSTICS; AEROSPACE; ATTENUATION; CERAMIC MATERIAL; COMPOSITE MATERIAL; MATERIAL CHARACTERIZATION; NONDESTRUCTIVE EVALUATION; POROSITY; STRESS WAVE; ULTRASONIC TESTING AB A review, model, and statistical analysis of ultrasonic velocity-pore fraction relations in polycrystalline materials is presented. First, a semiempirical model is developed showing the origin of the linear relationship between ultrasonic velocity and pore fraction. As examples, plots of velocity vs. percent porosity are shown for previously published data for Si3N4, steel, and YBa2Cu3O7-x. Linear regression analysis produced slope, intercept, correlation coefficient, level of significance, and confidence interval statistics for the data. Velocity values predicted from regression analysis for fully dense materials are in good agreement with those calculated from elastic properties. RP ROTH, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 29 Z9 29 U1 0 U2 1 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 JUL PY 1991 VL 49 IS 7 BP 883 EP 888 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA FW043 UT WOS:A1991FW04300006 ER PT J AU WHITTENBERGER, JD NATHAL, MV RAJ, SV PATHARE, VM AF WHITTENBERGER, JD NATHAL, MV RAJ, SV PATHARE, VM TI SLOW STRAIN RATE 1200-1400-K COMPRESSIVE PROPERTIES OF NIAL-1HF SO MATERIALS LETTERS LA English DT Article ID PLASTIC-FLOW PROPERTIES; GRAIN-SIZE; 1200-K; COMPOSITES; BEHAVIOR; 1300-K; CREEP AB Compression tests have been conducted on NiAl-1 Hf to assess the elevated temperature creep behavior of this precipitation hardened aluminide. While the strength is high under fast strain rates (> 10(-5) S-1), under slower conditions the alloy is weak. Thus it is unlikely that effective creep resistance can be obtained in NiAl through small Hf additions. C1 CPS SUPERCONDUCTOR CORP,MILFORD,MA 01757. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 18 Z9 19 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-577X J9 MATER LETT JI Mater. Lett. PD JUL PY 1991 VL 11 IS 8-9 BP 267 EP 272 DI 10.1016/0167-577X(91)90199-G PG 6 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA FX710 UT WOS:A1991FX71000008 ER PT J AU WHITTENBERGER, JD NOEBE, RD CULLERS, CL KUMAR, KS MANNAN, SK AF WHITTENBERGER, JD NOEBE, RD CULLERS, CL KUMAR, KS MANNAN, SK TI 1000-K TO 1200-K TIME-DEPENDENT COMPRESSIVE DEFORMATION OF SINGLE-CRYSTALLINE AND POLYCRYSTALLINE B2 NI-40AL SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID PLASTIC-FLOW PROPERTIES; GRAIN-SIZE; COMPOSITES; 1300-K; ALUMINIDES; BEHAVIOR; CREEP; COAL AB Single-crystalline and polycrystalline Ni-40Al have been compression tested at rates ranging from 0.1 to 10(-7) s-1 in air between 1000 and 1200 K. The [100] and [013] crystals were grown by a modified Bridgman technique, while the polycrystalline material was made by hot pressing XD synthesized powder. The as-pressed polycrystalline Ni-40Al had approximately 10-mu-m grains which were decorated with Al2O3 particles. This form also contained a small amount of-gamma' (Ni3Al), whereas neither single crystal showed evidence of this phase. In general, the stress-strain diagrams for the single crystals showed strain hardening over the first 1 pct of deformation, leading to diffuse yield points which existed over 0.5 to 1 pct strain. Following yielding, the single crystals strain soften and then, after about 3 pct deformation, begin to strain harden. As the test temperature increased or the strain rate decreased, the yield points tended to disappear, and the single crystals deformed under a more or less constant flow stress. Irrespective of the test temperature or strain rate, the polycrystalline Ni-40Al usually exhibited continued flow under a constant stress. While the [013] single crystals had higher yield strengths than the [100] variation, evaluation of the flow stress-strain rate data at 3 pct strain indicated that both forms had equivalent strength, but they were slightly weaker than the polycrystalline version. C1 INCO ALLOYS INT INC,HUNTINGTON,WV 25720. GEORGIA INST TECHNOL,SCH MAT ENGN,ATLANTA,GA 30332. MARTIN MARIETTA CORP LABS,BALTIMORE,MD 21227. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44133, USA. NR 46 TC 10 Z9 10 U1 0 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD JUL PY 1991 VL 22 IS 7 BP 1595 EP 1607 DI 10.1007/BF02667372 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA FV349 UT WOS:A1991FV34900012 ER PT J AU FOXRABINOVITZ, MS AF FOXRABINOVITZ, MS TI COMPUTATIONAL DISPERSION PROPERTIES OF HORIZONTAL STAGGERED GRIDS FOR ATMOSPHERIC AND OCEAN MODELS SO MONTHLY WEATHER REVIEW LA English DT Article ID FINITE-DIFFERENCE SCHEMES; NUMERICAL WEATHER PREDICTION AB The computational dispersion properties of horizontally and time-horizontally staggered grids using corresponding centered-difference schemes for approximation of the adjustment, or gravity wave equations are analyzed in terms of their group velocity characteristics. Results are obtained for atmospheric and oceanic models, the latter being characterized by a much smaller Rossby radius of deformation. Three best time-horizontally staggered grids have practically the same advantageous computational dispersion properties as the Arakawa C grid for both atmospheric and oceanic models-namely, the time-staggered D (or Eliassen) and time-staggered C (only with a semi-implicit scheme) grids-and to a certain extent the Lilly grid. Both, the Arakawa B and the time-staggered A grids for atmospheric and oceanic models, along with the Arakawa E and the time-staggered E grids only for atmospheric models (although having worse dispersion properties) also may be used as additional practical options. For all grids considered some additional filtering is needed to control and even eliminate waves with poor computational dispersion characteristics. Note that along with the B grid widely used in ocean models, the Arakawa C grid, the time-staggered A grid, and especially the time-staggered D (or Eliassen) and C (only with a semi-implicit scheme) grids can be recommended for practical use. The two latter grids have the best dispersion characteristics for ocean models among all staggered grids considered. Due to the staggering procedure, the grids have enhanced effective resolution that corresponds to the regular Arakawa A grid with half horizontal intervals. Approximate comparative estimates of computation time requirements for different staggered grids versus that of a regular grid are presented for advection and adjustment terms. Computational dispersion properties along with other computational characteristics and requirements provide some guidance for an optimal choice of an appropriate grid for an atmospheric or ocean model. RP FOXRABINOVITZ, MS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 19 TC 15 Z9 16 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUL PY 1991 VL 119 IS 7 BP 1624 EP 1639 DI 10.1175/1520-0493(1991)119<1624:CDPOHS>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX881 UT WOS:A1991FX88100009 ER PT J AU HAMMER, PD VALERO, FPJ KINNE, S AF HAMMER, PD VALERO, FPJ KINNE, S TI THE 27-28 OCTOBER 1986 FIRE CIRRUS CASE-STUDY - RETRIEVAL OF CLOUD PARTICLE SIZES AND OPTICAL DEPTHS FROM COMPARATIVE ANALYSES OF AIRCRAFT AND SATELLITE-BASED INFRARED MEASUREMENTS SO MONTHLY WEATHER REVIEW LA English DT Article ID THEMATIC MAPPER; WINDOW REGION; THIN CLOUDS; HIGH-LEVEL; EMISSIVITY; TEMPERATURE; CONSTANTS; RADIATION; WATER; ICE AB Infrared radiance measurements were acquired from a narrow-field nadir-viewing radiometer based on the NASA ER-2 aircraft during a coincident Landsat 5 overpass on 28 October 1986 as part of the FIRE Cirrus IFO in the vicinity of Lake Michigan. The spectral bandpasses are 9.90-10.87-mu-m for the ER-2-based radiometer and 10.40-12.50-mu-m for the Landsat thematic mapper band. After adjusting for spatial and temporal differences, a comparative study using data from these two instruments is undertaken in order to retrieve cirrus cloud ice-crystal sizes and optical depths. Retrieval is achieved by analysis of measurement correlations between the two spectral bands and comparison to multistream radiative transfer model calculations. The results indicate that the equivalent sphere radii of the cirrus ice crystals were typically less than 30-mu-m. Such particles were too small to be measured by the available in situ instrumentation. Cloud optical depths at a reference wavelength of 11.4-mu-m ranged from 0.3 to 2.0 for this case study. Supplemental results in support of this study are described using radiation measurements from the King Air aircraft, which was also in near coincidence with the Landsat overpass. RP HAMMER, PD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 37 TC 12 Z9 12 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUL PY 1991 VL 119 IS 7 BP 1673 EP 1692 DI 10.1175/1520-0493(1991)119<1673:TOFCCS>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FX881 UT WOS:A1991FX88100012 ER PT J AU GOLIN, RMA KEIL, LC GANONG, WF AF GOLIN, RMA KEIL, LC GANONG, WF TI EFFECT OF HEAD-UP TILT ON VASOPRESSIN SECRETION AND ARTERIAL-PRESSURE IN ANESTHETIZED RATS SO NEUROENDOCRINOLOGY LA English DT Article DE ARGININE VASOPRESSIN; RENIN-ANGIOTENSIN SYSTEM; SINOAORTIC DENERVATION; VAGOTOMY ID RENIN-ANGIOTENSIN SYSTEM; PLASMA VASOPRESSIN; BLOOD-PRESSURE; RELEASE; OSMOLALITY; HEMORRHAGE; ENDOCRINE; RESPONSES; INFUSION; VOLUME AB The effect of 45 or 60-degrees head-up tilt on plasma arginine vasopressin (AVP) concentration, mean arterial pressure, and heart rate was studied in inactin-anesthetized rats. In all rats, there was a fall in blood pressure that was maximal within about 20-40 s and then returned toward normal. After 45-degrees head-up tilt for 30 min, AVP was increased from 7.0 +/- 1.7 to 21.0 +/- 5.9 pg/ml. Sixty-degree head-up tilt increased AVP at 5, 15, and 30 min, respectively, from 10.6 +/- 2.9 to 22.1 +/- 4.8 pg/ml, from 10.6 +/- 2.5 to 28.5 +/- 5.3, and from 16.1 +/- 4.7 to 62.6 +/- 10.3 pg/ml. After bilateral cervical vagotomy, 60-degrees head-up tilt for 30 min increased AVP, but the change was significantly reduced compared to intact animals. Bilateral sinoaortic denervation increased basal values of AVP, and there was no further increase during tilt. Bilateral electrolytic lesions of the hypothalamic paraventricular nuclei caused only a moderate reduction in the AVP response to tilt. When the effect of endogenous angiotensin II was antagonized by saralasin or its production was blocked by enalapril, the AVP response to tilt was reduced. The mean arterial pressure fell during the 1st min, but recovered rapidly when rats treated with a V1 vasopressin receptor antagonist were tilted. The data indicate that head-up tilt increases AVP secretion in anesthetized rats, that the response is mediated by the vagus and particularly by the arterial baroreceptors, and that circulating angiotensin II contributes to the response. However, the increased circulating AVP is not necessary for the maintenance of arterial pressure. C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. FU NHLBI NIH HHS [HL29714] NR 32 TC 2 Z9 2 U1 0 U2 0 PU KARGER PI BASEL PA ALLSCHWILERSTRASSE 10, CH-4009 BASEL, SWITZERLAND SN 0028-3835 J9 NEUROENDOCRINOLOGY JI Neuroendocrinology PD JUL PY 1991 VL 54 IS 1 BP 42 EP 48 DI 10.1159/000125849 PG 7 WC Endocrinology & Metabolism; Neurosciences SC Endocrinology & Metabolism; Neurosciences & Neurology GA FU642 UT WOS:A1991FU64200007 PM 1922676 ER PT J AU JIANG, Y CHEN, CP TUCKER, PK AF JIANG, Y CHEN, CP TUCKER, PK TI MULTIGRID SOLUTION OF UNSTEADY NAVIER-STOKES EQUATIONS USING A PRESSURE METHOD SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID CIRCULAR-CYLINDER; FLOWS; WAKE AB A multigrid relaxation method is applied to a pressure-based implicit procedure to solve the unsteady, incompressible Navier-Stokes equations. The present multigrid method is a correction scheme according to Brandt. This method is used to solve the scalar matrices resulting from the finite-volume formulation and uses flux averaging as the restriction operator. The accuracy and computational efficiency are demonstrated with a steady-state driven cavity flow and an unsteady flow over a circular cylinder case. The results are compared with single-grid results using the OrthoMin conjugate gradient method and experimental data. C1 UNIV ALABAMA,DEPT MECH ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,COMPUTAT FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812. NR 24 TC 9 Z9 9 U1 1 U2 2 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 JUL-AUG PY 1991 VL 20 IS 1 BP 81 EP 93 DI 10.1080/10407789108944810 PG 13 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA FX921 UT WOS:A1991FX92100005 ER PT J AU THOMAS, LD AF THOMAS, LD TI COMMONALITY ANALYSIS USING CLUSTERING METHODS SO OPERATIONS RESEARCH LA English DT Note AB The application of commonality in a system represents an attempt to reduce costs by reducing the number of unique components. A formal method for conducting commonality analysis has not been established. This paper characterizes commonality analysis as a partitioning problem for which the solution may be approximated by the application of clustering methods. A clustering algorithm is developed and applied to a commonality analysis of Space Station water tanks. The success in applying a clustering method in this problem indicates a significant potential for application of clustering methods to commonality analysis. RP THOMAS, LD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 14 TC 8 Z9 8 U1 0 U2 0 PU OPERATIONS RES SOC AMER PI BALTIMORE PA 1314 GUILFORD AVENUE BUSINESS OFFICE, BALTIMORE, MD 21202 SN 0030-364X J9 OPER RES JI Oper. Res. PD JUL-AUG PY 1991 VL 39 IS 4 BP 677 EP 680 DI 10.1287/opre.39.4.677 PG 4 WC Management; Operations Research & Management Science SC Business & Economics; Operations Research & Management Science GA GC361 UT WOS:A1991GC36100014 ER PT J AU KUMAR, BVKV JUDAY, RD AF KUMAR, BVKV JUDAY, RD TI DESIGN OF PHASE-ONLY, BINARY PHASE-ONLY, AND COMPLEX TERNARY MATCHED-FILTERS WITH INCREASED SIGNAL-TO-NOISE RATIOS FOR COLORED NOISE SO OPTICS LETTERS LA English DT Article AB An algorithm is provided for treating nonwhite additive noise in determining regions of support for phase-only filters, binary phase-only filters, and complex ternary matched filters. It is analytically shown to be optimal in the signal-to-noise ratio sense. It extends earlier research that assumed white noise. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV TRACKING & COMMUN,HOUSTON,TX 77058. RP KUMAR, BVKV (reprint author), CARNEGIE MELLON UNIV,DEPT ELECT & COMP ENGN,PITTSBURGH,PA 15213, USA. NR 10 TC 15 Z9 15 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD JUL 1 PY 1991 VL 16 IS 13 BP 1025 EP 1027 DI 10.1364/OL.16.001025 PG 3 WC Optics SC Optics GA FU160 UT WOS:A1991FU16000017 PM 19776864 ER PT J AU LINDGREN, M AHLBERG, H LARSSON, A ENG, ST DANERUD, M AF LINDGREN, M AHLBERG, H LARSSON, A ENG, ST DANERUD, M TI ULTRAFAST IR DETECTOR RESPONSE IN HIGH-TC SUPERCONDUCTING THIN-FILMS SO PHYSICA SCRIPTA LA English DT Article AB The response from a high T(c) superconducting multielement optical detector made of a laser deposited Y-Ba-Cu-O thin film has been evaluated. Several microscopic and spectroscopic techniques were used to establish the presence of the correct phase of the thin film. We have used optical pulses from a laser diode at 830 nm and from a Q-switched CO2-laser at 10.6-mu-m. The detector responded to 50 ps (FWHM) pulses. A comparison between dR/dT of the film and the response amplitude as a function of temperature indicated a bolometric response. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,DEPT PHYS,S-41296 GOTHENBURG,SWEDEN. RP LINDGREN, M (reprint author), CHALMERS UNIV TECHNOL,DEPT OPTOELECTR & ELECT MEASUREMENTS,S-41296 GOTHENBURG,SWEDEN. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 5 TC 2 Z9 2 U1 0 U2 0 PU ROYAL SWEDISH ACAD SCIENCES PI STOCKHOLM PA PUBL DEPT BOX 50005, S-104 05 STOCKHOLM, SWEDEN SN 0281-1847 J9 PHYS SCRIPTA JI Phys. Scr. PD JUL PY 1991 VL 44 IS 1 BP 105 EP 107 DI 10.1088/0031-8949/44/1/016 PG 3 WC Physics, Multidisciplinary SC Physics GA FY017 UT WOS:A1991FY01700017 ER PT J AU TOWNSEND, LW WILSON, JW KHAN, F KHANDELWAL, GS AF TOWNSEND, LW WILSON, JW KHAN, F KHANDELWAL, GS TI MOMENTUM-TRANSFER IN RELATIVISTIC HEAVY-ION CHARGE-EXCHANGE REACTIONS SO PHYSICAL REVIEW C LA English DT Note ID FRAGMENTATION; NUCLEI; MODEL AB Relativistic heavy ion charge-exchange reactions yield fragments (DELTA-Z = + 1) whose longitudinal momentum distributions are downshifted by larger values than those associated with the remaining fragments (DELTA-Z = -1, -2,...). Kinematics alone cannot account for the observed downshifts; therefore, an additional contribution from collision dynamics must be included. In this work, an optical model description of collision momentum transfer is used to estimate the additional dynamical momentum downshift. Good agreement between theoretical estimates and experimental data is obtained. C1 OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529. RP TOWNSEND, LW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. FU NCPDCID CDC HHS [NCCI-42] NR 9 TC 5 Z9 5 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD JUL PY 1991 VL 44 IS 1 BP 540 EP 542 DI 10.1103/PhysRevC.44.540 PG 3 WC Physics, Nuclear SC Physics GA FV183 UT WOS:A1991FV18300068 PM 9967432 ER PT J AU KOLB, EW TURNER, MS AF KOLB, EW TURNER, MS TI ASTROPHYSICS AND COSMOLOGY CONFRONT THE 17-KEV NEUTRINO SO PHYSICAL REVIEW LETTERS LA English DT Article ID HEAVY-NEUTRINO; BETA-SPECTRUM; PRIMORDIAL NUCLEOSYNTHESIS; CONSTRAINTS; SEARCH; DECAY; S-35; SN1987A; AXIONS; PARTICLES AB Astrophysical and cosmological arguments constrain the properties of a 17-keV Dirac neutrino. it must have interactions beyond those of the standard electroweak theory to reduce its cosmic abundance by a factor of 200. A predicament arises because the additional helicity states of the neutrino necessary to construct a Dirac mass must have interactions strong enough to evade the astrophysical bound from SN 1987A, but weak enough to avoid violating the bound from primordial nucleosynthesis. 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,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 39 TC 45 Z9 45 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 1 PY 1991 VL 67 IS 1 BP 5 EP 8 DI 10.1103/PhysRevLett.67.5 PG 4 WC Physics, Multidisciplinary SC Physics GA FU343 UT WOS:A1991FU34300002 ER PT J AU SMITH, SJ MAN, KF MAWHORTER, RJ WILLIAMS, ID CHUTJIAN, A AF SMITH, SJ MAN, KF MAWHORTER, RJ WILLIAMS, ID CHUTJIAN, A TI ABSOLUTE, CASCADE-FREE CROSS-SECTIONS FOR THE 2S-]2P TRANSITION IN ZN+ USING ELECTRON-ENERGY-LOSS AND MERGED-BEAMS METHODS SO PHYSICAL REVIEW LETTERS LA English DT Article ID IMPACT EXCITATION; IONS AB Absolute, cascade-free excitation cross sections in an ion have been measured for the resonance 2S --> 2P transition in Zn+ using electron-energy-loss and merged electron-ion beams methods. Measurements were carried out at electron energies of below threshold to 6 times threshold. Comparisons are made with 2-, 5-, and 15-state close-coupling and distorted-wave theories. There is good agreement between experiment and the 15-state close-coupling cross sections over the energy range of the calculations. C1 POMONA COLL,DEPT PHYS & ASTRON,CLAREMONT,CA 91711. QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. RP SMITH, SJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 18 TC 29 Z9 30 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 1 PY 1991 VL 67 IS 1 BP 30 EP 33 DI 10.1103/PhysRevLett.67.30 PG 4 WC Physics, Multidisciplinary SC Physics GA FU343 UT WOS:A1991FU34300009 ER PT J AU GIRIMAJI, SS AF GIRIMAJI, SS TI ASYMPTOTIC-BEHAVIOR OF CURVATURE OF SURFACE ELEMENTS IN ISOTROPIC TURBULENCE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID NUMERICAL SIMULATIONS AB The asymptotic behavior of the curvature of material elements in turbulence is investigated using Lagrangian velocity-gradient time series obtained from direct numerical simulations of isotropic turbulence. Several material-element ensembles of different initial curvatures and shapes are studied. It is found that, at long times, the (first five) moments of the logarithm of characteristic curvature (C) and shape factor (S) asymptote to values that are independent of the initial curvature or shape. This evidence strongly suggests that the asymptotic pdf's of the curvature and shape of material elements are stationary and independent of initial conditions. Irrespective of initial curvature or shape, the asymptotic shape of a material surface is cylindrical with a high probability. RP GIRIMAJI, SS (reprint author), NASA,LANGLEY RES CTR,AS&M INC,HAMPTON,VA 23666, USA. NR 8 TC 7 Z9 7 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 JUL PY 1991 VL 3 IS 7 BP 1772 EP 1777 DI 10.1063/1.857957 PG 6 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA GM594 UT WOS:A1991GM59400012 ER PT J AU BALDWIN, R FREY, H AF BALDWIN, R FREY, H TI MAGSAT CRUSTAL ANOMALIES FOR AFRICA - DAWN AND DUSK DATA DIFFERENCES AND A COMBINED DATA SET SO PHYSICS OF THE EARTH AND PLANETARY INTERIORS LA English DT Article ID MAGNETIC-SUSCEPTIBILITY; FIELD; INVERSION; AUSTRALIA; MODEL; MAP AB A new crustal magnetic anomaly map of Africa using both local time (dawn and dusk) MAGSAT data sets is presented. MAGSAT data include the external field (magnetospheric field) and internal fields (main core field, crustal field, induction field, and ionospheric field). The crustal field is extracted by removing the undesired external and internal components with the least possible effect on the crustal signature. The effects of external and internal fields can be reduced by filtering along track, calculating a mean ionospheric field correction for both the equatorial electrojet and solar daily quiet variation (S(q)) currents, removing a thirteenth-degree and -order spherical harmonic model of the main field, and eliminating observations associated with large values of magnetic field indices (K(p), D(st), AE). An important consideration in selecting the appropriate long-wavelength cutoff for the along-track filter is how to minimize attenuation of the true crustal field. Power spectra, coincident passes, standard error maps, and differences in scalar anomalies for local time maps are examined to determine the best choice. After filtering each local time separately, dawn and dusk data can be averaged in 2-degrees equal-area bins to produce a combined average scalar map. Using the equivalent source method, the crustal anomalies are presented at a common altitude (400 km) and in reduced-to-pole representation. C1 NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. ST SYST CORP, LANHAM, MD 20706 USA. NR 27 TC 10 Z9 10 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-9201 EI 1872-7395 J9 PHYS EARTH PLANET IN JI Phys. Earth Planet. Inter. PD JUL PY 1991 VL 67 IS 3-4 BP 237 EP 250 DI 10.1016/0031-9201(91)90021-9 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FX911 UT WOS:A1991FX91100004 ER PT J AU GRAF, JC AF GRAF, JC TI THE IMPORTANCE OF RESOLUTION LIMITS TO THE INTERPRETATION OF FRACTAL DESCRIPTIONS OF FINE PARTICLES SO POWDER TECHNOLOGY LA English DT Article ID RUGGEDNESS; DIMENSION AB Fractals can be used to successfully quantify the ruggedness of a particle, but fractal information is highly sensitive to resolution limits, and fractal interpretations without consideration of resolution can be misleading. Awareness of scale can minimize confusion and avoid misinterpretation; better resolution can show new, potentially important textural elements. RP GRAF, JC (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058, USA. NR 15 TC 16 Z9 16 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0032-5910 J9 POWDER TECHNOL JI Powder Technol. PD JUL PY 1991 VL 67 IS 1 BP 83 EP 85 DI 10.1016/0032-5910(91)80029-I PG 3 WC Engineering, Chemical SC Engineering GA FZ933 UT WOS:A1991FZ93300011 ER PT J AU SMALE, AP AF SMALE, AP TI A 9.1-HOUR CANDIDATE ORBITAL PERIOD FOR X1556-605 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article DE X-RAY ASTRONOMY; BINARY STARS; PHOTOMETRY ID X-RAY; LOW-MASS; X-2 AB I present V-band photometry of the low-mass X-ray binary X1556-605 obtained in May 1988 in an attempt to determine the orbital period of the system. The source is seen to be variable by up to 0.6 magnitude on a time scale of hours. Combining my data with those obtained one month later by Schmidtke 1990, I use Fourier techniques and a recently improved version of the standard period-folding analysis to find a probable period of 0.3807 +/- 0.0003 day, with a semiamplitude of approximately 0.1 magnitude. Both methods indicate that the formal significance of this period detection is > 99.9%. While independent confirmation is advised before accepting this to be the definitive orbital period of the system, a period of this length would not be inconsistent with the X-ray properties of X1556-605 and would, in addition, suggest that the mass-donating companion may be beginning to evolve away from the main sequence. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. RP SMALE, AP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT RD,GREENBELT,MD 20771, USA. NR 27 TC 5 Z9 5 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 JUL PY 1991 VL 103 IS 665 BP 636 EP 641 DI 10.1086/132863 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ673 UT WOS:A1991FZ67300004 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI GLARE AND CELESTIAL VISIBILITY SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article DE VISIBILITY OF CELESTIAL SOURCES; SCATTERED-LIGHT MODELS ID SKY BRIGHTNESS AB Glare is when a bright source of light hides a nearby fainter source and is caused by scattering of light within the atmosphere, the telescope, and the eyeball. In this paper I develop a model of the effects of glare on the visibility of astronomical sources as viewed with the human eye whether unaided or through a telescope. This model is tested and found to closely reproduce observations of lunar appulses, Galilean satellites, the Martian moons, well-known double stars, and lunar occultations. Glare calculations are then applied to a wide variety of situations of historical and astronomical interest. (1) Ancient Chinese lunar appulse reports have been used to determine the acceleration of the Earth's rotation. However, a detailed analysis shows that the results depend critically on the adopted weighting scheme and that the ancient Chinese reports contain too many errors to allow for a meaningful conclusion. (2) The Crucifixion eclipse of A.D. 33 April 3 (or any other partial lunar eclipse with less than almost-equal-to 70% coverage by the umbra) would not have appeared "blood colored" because of the eclipse, since scattered white light from the penumbra will always mask the faint red light in the umbra. (3) Contrary to a statement by Aristotle, the visibility of stars from the bottom of deep wells or chimneys is worse than the visibility under an open sky. (4) Venus can be barely visible at inferior conjunction under optimal conditions with no optical aid. (5) An observing strategy is proposed which may lead to the discovery of several sungrazing comets per year by observations with small ground-based telescopes. (6) The effects of glare on the visibility of stars in loose open clusters is small. (7) The conditions for the detection of double stars are derived. (8) The model suggests various procedures for observers afflicted with glare, of which the most important is that the magnification should be pushed to the maximum usable power. (9) Various challenges are presented for observers, including the creation of a worldwide network to discover sungrazing comets. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 82 TC 12 Z9 12 U1 1 U2 2 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 JUL PY 1991 VL 103 IS 665 BP 645 EP 660 DI 10.1086/132865 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FZ673 UT WOS:A1991FZ67300006 ER PT J AU BENSON, RF DESCH, MD AF BENSON, RF DESCH, MD TI WIDE-BAND NOISE OBSERVED AT GROUND-LEVEL IN THE AURORAL REGION SO RADIO SCIENCE LA English DT Article ID HISS; FREQUENCY; ELECTRONS; ISIS-1; ORIGIN; WAVES AB A wideband noise event was detected at ground level from the Andoya Rocket Range in Norway in January 1989. The signals were observed on four commercial communication receivers (tuned to 159, 515, 905, and 1200 kHz), an ionosonde (200-kHz to 3.5-MHz interference-free observations) and a riometer (32.5 MHz). The event, which occurred during a period of magnetic disturbance near magnetic midnight, was the only one observed during nearly 3 weeks of operations. This low frequency-of-occurrence is attributed partly to high local noise levels. The ease with which this event was identified on the ionograms produced by the local ionosonde suggests that routine ionosonde recordings should be inspected in search for such events. Such an effort would enhance existing research directed toward developing techniques for identifying quiet communication channels and help to identify the origin and frequency-of-occurrence of high-latitude wideband noise events. RP BENSON, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 21 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD JUL-AUG PY 1991 VL 26 IS 4 BP 943 EP 948 DI 10.1029/91RS00450 PG 6 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA FZ016 UT WOS:A1991FZ01600014 ER PT J AU EVANS, DL SMITH, MO AF EVANS, DL SMITH, MO TI SEPARATION OF VEGETATION AND ROCK SIGNATURES IN THEMATIC MAPPER AND POLARIMETRIC SAR IMAGES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADAR POLARIMETRY; AREAS AB A technique for separating classes of surface roughness and vegetation in semiarid regions using polarimetric Synthetic Aperture Radar (SAR) and Thematic Mapper (TM) data has been developed. We conclude that polarimetric SAR data may be used to separate areas with < 10% vegetation cover where one suite of model inversions may be applicable for derivation of surface roughness. In more vegetated regions, visible/near-infrared (NIR) data will provide a mechanism for determining the relative contribution of vegetation to multiple scattering in the SAR data. Thus, the synergistic use of the two data sets provides a more complete characterization of surface units and cover. This result, while important for geologic interpretations, is even more critical when trying to monitor dielectric constant variations related to changes in moisture content of soil and vegetation cover in arid to semiarid regions. A strategy for automating a procedure for measurement of surface roughness is proposed. C1 UNIV WASHINGTON,DEPT GEOL SCI,SEATTLE,WA 98195. RP EVANS, DL (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 10 Z9 11 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 JUL PY 1991 VL 37 IS 1 BP 63 EP 75 DI 10.1016/0034-4257(91)90051-7 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GE607 UT WOS:A1991GE60700006 ER PT J AU KRAINSKY, IL AF KRAINSKY, IL TI INVERSE PHOTOELECTRON SPECTROMETER WITH MAGNETICALLY FOCUSED ELECTRON-GUN SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID PHOTOEMISSION; ULTRAVIOLET; SURFACE AB This article describes an inverse photoelectron spectrometer based on the novel design of a magnetically focused low energy electron gun. The article discusses results of the ray tracing procedure conducted for this gun and some of the advantages of the magnetic focusing. RP KRAINSKY, IL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD JUL PY 1991 VL 62 IS 7 BP 1746 EP 1748 DI 10.1063/1.1142416 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA FU522 UT WOS:A1991FU52200008 ER PT J AU SARAVANOS, DA CHAMIS, CC MOREL, M AF SARAVANOS, DA CHAMIS, CC MOREL, M TI CONCURRENT TAILORING OF FABRICATION PROCESS AND INTERPHASE LAYER TO REDUCE RESIDUAL-STRESSES IN METAL MATRIX COMPOSITES SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB A methodology is presented to reduce the residual matrix stresses in continuous fiber metal matrix composites (MMC) by optimizing the fabrication process and interphase layer characteristics. The response of the fabricated MMC was simulated based on nonlinear micromechanics. Application cases include fabrication tailoring, interphase tailoring, and concurrent fabrication-interphase optimization. Two composite systems, silicon carbide/titanium and graphite/copper, are considered. Results illustrate the merits of each approach, indicate that concurrent fabrication/interphase optimization produces significant reductions in the matrix residual stresses and demonstrate the strong coupling between fabrication and interphase tailoring. RP SARAVANOS, DA (reprint author), CASE WESTERN RESERVE UNIV,NASA,LEWIS RES CTR,CLEVELAND,OH 44106, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD JUL PY 1991 VL 22 IS 4 BP 36 EP 44 PG 9 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA FV453 UT WOS:A1991FV45300005 ER PT J AU STOTHERS, RB RAMPINO, MR AF STOTHERS, RB RAMPINO, MR TI TOO BIG A BANG SO SCIENCES-NEW YORK LA English DT Letter RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 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 SN 0036-861X J9 SCIENCES JI Sci.-New York PD JUL-AUG PY 1991 VL 31 IS 4 BP 55 EP 55 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FT268 UT WOS:A1991FT26800013 ER PT J AU LAWRENCE, JA SMITH, HE AF LAWRENCE, JA SMITH, HE TI THE ROLE OF JSC ENGINEERING SIMULATION IN THE APOLLO PROGRAM SO SIMULATION LA English DT Article DE SEI; APOLLO MISSION; LUNAR LANDING; REAL-TIME; SIMULATION AB Presently, the Space Exploration Initiative has captured the attention of the manned space community. The approach to the accomplishment of such a demanding mission causes recall of the development of the Apollo mission, the synergism with the SEI, and the role that JSC's Engineering Simulations took in the Lunar Landing systems definition and development. C1 LOCKHEED ENGN & SCI CO,DEPT SYST ENGN,ENGN & SCI PROGRAM,HOUSTON,TX 77058. RP LAWRENCE, JA (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU SIMULATION COUNCILS INC PI SAN DIEGO PA PO BOX 17900, SAN DIEGO, CA 92117 SN 0037-5497 J9 SIMULATION JI Simulation PD JUL PY 1991 VL 57 IS 1 BP 9 EP 16 DI 10.1177/003754979105700105 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering SC Computer Science GA FZ626 UT WOS:A1991FZ62600001 ER PT J AU YANG, YK KUO, YM AF YANG, YK KUO, YM TI A REAL-TIME SIMULATOR FOR THE SHUTTLE MANIPULATOR SYSTEM IN THE SYSTEM ENGINEERING LABORATORY SO SIMULATION LA English DT Article DE SHUTTLE REMOTE MANIPULATOR SYSTEM; REAL-TIME; D-AND-C SYSTEM; SYSTEMS ENGINEERING SIMULATOR C1 NASA,LYNDON B JOHNSON SPACE CTR,SYST ENGN SIMULATOR LAB,HOUSTON,TX 77058. RP YANG, YK (reprint author), LOCKHEED ENGN SCI CO,DEPT SIMULAT DEV,HOUSTON,TX 77058, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU SIMULATION COUNCILS INC PI SAN DIEGO PA PO BOX 17900, SAN DIEGO, CA 92117 SN 0037-5497 J9 SIMULATION JI Simulation PD JUL PY 1991 VL 57 IS 1 BP 48 EP 55 DI 10.1177/003754979105700111 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering SC Computer Science GA FZ626 UT WOS:A1991FZ62600006 ER PT J AU BROWN, CT AF BROWN, CT TI THE KENNEDY-SPACE-CENTER TELEVISION SYSTEM SO SMPTE JOURNAL LA English DT Article AB The television requirements for NASA at the Kennedy Space Center (KSC) provide a unique opportunity for systems design and development. Not only must the systems operate under extremely hostile environmental conditions, but they must also provide transmission and signal distribution over a wide geographical area, with minimal impact on the environment. The goal of the television plant at KSC is to provide to the various users - including the launch team, other NASA centers, and the media - an NTSC RS-170 television signal of the highest quality possible, to act as source material for image analysis, media programming, and launch commitment criteria decision making. The television and transmission systems, much like America's space program, have developed through an evolutionary process, with remnants of the 1960s' technology meshing efficiently with today's state-of-the-art systems and components. The future promises even greater challenges. This article describes the systems and philosophy for television at the Kennedy Space Center. RP BROWN, CT (reprint author), NATL AERONAUT & SPACE CTR,KENNEDY SPACE CTR,FL 32899, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC MOTION PICTURE TV ENG INC PI WHITE PLAINS PA 595 WEST HARTSDALE AVE, WHITE PLAINS, NY 10607 SN 0036-1682 J9 SMPTE J JI SMPTE J. PD JUL PY 1991 VL 100 IS 7 BP 528 EP 540 PG 13 WC Engineering, Electrical & Electronic; Instruments & Instrumentation; Imaging Science & Photographic Technology; Telecommunications SC Engineering; Instruments & Instrumentation; Imaging Science & Photographic Technology; Telecommunications GA FV625 UT WOS:A1991FV62500009 ER PT J AU JAWORSKE, DA PERRY, WD AF JAWORSKE, DA PERRY, WD TI VOID CONTROL IN THE CRYSTALLIZATION OF LITHIUM-FLUORIDE SO SOLAR ENERGY MATERIALS LA English DT Article AB The effect of tungsten-coated graphite fibers on the radiant heat transfer characteristics of salt-fiber composites was studied by measuring the onset of melting as a function of applied furnace power. As the fiber concentration was increased from 0 wt% to 5.40 wt% fiber, the furnace temperature required to melt the lithium fluoride also increased. Upon cooling, each of the crystalline salt-fiber composites were cut open with a diamond saw to expose the void. Optical photographs of the voids revealed a trend in void location and size, with the largest void, and the least change in the outer dimension of the boule upon cooling, occurring in the sample with the most fiber. C1 AUBURN UNIV,DEPT CHEM,AUBURN,AL 36849. RP JAWORSKE, DA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 9 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-1633 J9 SOL ENERG MATER PD JUL PY 1991 VL 22 IS 2-3 BP 243 EP 248 DI 10.1016/0165-1633(91)90022-D PG 6 WC Energy & Fuels; Materials Science, Multidisciplinary SC Energy & Fuels; Materials Science GA FY584 UT WOS:A1991FY58400013 ER PT J AU SODUPE, M BAUSCHLICHER, CW AF SODUPE, M BAUSCHLICHER, CW TI AL+-LIGAND BINDING-ENERGIES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; 2ND-ROW ATOMS; GAS-PHASE; ROW ATOMS; ABINITIO; CONTRACTION; COMPLEXES; CO AB Ab initio calculations are used to optimize the structure and determine the binding energies of Al+ to a series of ligands. For Al+-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al+ are compared with those previously reported for Mg+. RP SODUPE, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 21 TC 53 Z9 54 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 28 PY 1991 VL 181 IS 4 BP 321 EP 326 DI 10.1016/0009-2614(91)80079-D PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FW190 UT WOS:A1991FW19000009 ER PT J AU SEKI, MP MUNDY, BC AF SEKI, MP MUNDY, BC TI SOME NOTES ON THE EARLY LIFE STAGES OF THE PACIFIC POMFRET, BRAMA-JAPONICA, AND OTHER BRAMIDAE FROM THE CENTRAL NORTH PACIFIC-OCEAN SO JAPANESE JOURNAL OF ICHTHYOLOGY LA English DT Note ID FISHES RP SEKI, MP (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 19 TC 6 Z9 6 U1 0 U2 0 PU ICHTHYOLOGICAL SOC JAPAN PI TOKYO PA BUSINESS CENTER ACADEMIC SOC JAPAN, 5-16-9 HONKOMAGOME, BUNKYO-KU, TOKYO 113, JAPAN SN 0021-5090 J9 JPN J ICHTHYOL JI Jpn. J. Ichthyol. PD JUN 28 PY 1991 VL 38 IS 1 BP 63 EP 68 PG 6 WC Fisheries; Zoology SC Fisheries; Zoology GA FY967 UT WOS:A1991FY96700011 ER PT J AU ROWANROBINSON, M BROADHURST, T LAWRENCE, A MCMAHON, RG LONSDALE, CJ OLIVER, SJ TAYLOR, AN HACKING, PB CONROW, T SAUNDERS, W ELLIS, RS EFSTATHIOU, GP CONDON, JJ AF ROWANROBINSON, M BROADHURST, T LAWRENCE, A MCMAHON, RG LONSDALE, CJ OLIVER, SJ TAYLOR, AN HACKING, PB CONROW, T SAUNDERS, W ELLIS, RS EFSTATHIOU, GP CONDON, JJ TI A HIGH-REDSHIFT IRAS GALAXY WITH HUGE LUMINOSITY - HIDDEN QUASAR OR PROTOGALAXY SO NATURE LA English DT Article ID S5 0014+81; REMNANT AB DURING a survey intended to measure redshifts for 1,400 galaxies identified with faint sources detected by the Infrared Astronomy Satellite, we found an emission-line galaxy at a redshift of 2.286, and with the enormous far-infrared luminosity of 3 x 10(14) times that of the Sun (L.). The spectrum is very unusual, showing lines of high excitation but with very weak Lyman-alpha emission. A self-absorbed synchrotron model for the infrared energy distribution cannot be ruled out, but a thermal origin seems more plausible. A radio-quiet quasar embedded in a very dusty galaxy could account for the infrared emission, as might a starburst embedded in 1-10 x 10(9) M. of dust. The latter case demands so much dust that the object would probably be a massive galaxy in the. process of formation. In either case, this is a remarkable object, and the presence of a large amount of dust in an object of such high redshift implies the generation of heavy elements at an early cosmological epoch. C1 QUEEN MARY & WESTFIELD COLL, DEPT PHYS, LONDON E1 4NS, ENGLAND. UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. CALTECH, CTR INFRARED PROC & ANAL, PASADENA, CA 91125 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV OXFORD, DEPT ASTROPHYS, OXFORD OX1 3RH, ENGLAND. UNIV DURHAM, DEPT PHYS, DURHAM DH1 3LE, ENGLAND. NATL RADIO ASTRON OBSERV, CHARLOTTESVILLE, VA 22903 USA. RP ROWANROBINSON, M (reprint author), QUEEN MARY & WESTFIELD COLL, SCH MATH SCI, MILE END RD, LONDON E1 4NS, ENGLAND. NR 19 TC 236 Z9 236 U1 0 U2 1 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 27 PY 1991 VL 351 IS 6329 BP 719 EP 721 DI 10.1038/351719a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FU201 UT WOS:A1991FU20100054 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H AF BAUSCHLICHER, CW PARTRIDGE, H TI MG+ -LIGAND BINDING-ENERGIES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; ABINITIO CALCULATIONS; POSITIVE-IONS; 2ND-ROW ATOMS; CONTRACTION AB Ab initio calculations are used to optimize the structures and determine the binding energies of Mg+ to a series of ligands. Mg+ bonds electrostatically with benzene, acetone, H-2, CO, and NH3 and a self-consistent-field treatment gives a good description of the bonding. The bonding in MgCN+ and MgCH3+ is largely covalent and a correlated treatment is required. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 22 TC 89 Z9 89 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 21 PY 1991 VL 181 IS 2-3 BP 129 EP 133 DI 10.1016/0009-2614(91)90344-9 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FU295 UT WOS:A1991FU29500007 ER PT J AU FISHMAN, J FAKHRUZZAMAN, K CROS, B NGANGA, D AF FISHMAN, J FAKHRUZZAMAN, K CROS, B NGANGA, D TI IDENTIFICATION OF WIDESPREAD POLLUTION IN THE SOUTHERN-HEMISPHERE DEDUCED FROM SATELLITE ANALYSES SO SCIENCE LA English DT Article ID ATMOSPHERIC METHANE; CARBON-MONOXIDE; CAPE POINT; DRY SEASON; TRENDS; AFRICA; MODEL AB Vertical profiles of ozone obtained from ozonesondes in Brazzaville, Congo (4-degrees-S, 15-degrees-E), and Ascension Island (8-degrees-S, 15-degrees-W) show that large quantities of tropospheric ozone are present over southern Africa and the adjacent eastern tropical South Atlantic Ocean. The origin of this pollution is widespread biomass burning in Africa. These measurements support satellite-derived tropospheric ozone data that demonstrate that ozone originating from this region is transported throughout most of the Southern Hemisphere. Seasonally high levels of carbon monoxide and methane observed at middle- and high-latitude stations in Africa, Australia, and Antarctica likely reflect the effects of this distant biomass burning. These data suggest that even the most remote regions on this planet may be significantly more polluted than previously believed. C1 ST SYST CORP,HAMPTON,VA 23666. UNIV MAIEN NGOUABI,PHYS ATMOSPHERE LAB,BRAZZAVILLE,CONGO PEOPL REP. RP FISHMAN, J (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 401A,HAMPTON,VA 23665, USA. NR 27 TC 250 Z9 250 U1 1 U2 12 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUN 21 PY 1991 VL 252 IS 5013 BP 1693 EP 1696 DI 10.1126/science.252.5013.1693 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FT114 UT WOS:A1991FT11400042 PM 17751973 ER PT J AU GIOVANE, F EICHHORN, G MCKISSON, J WEINBERG, JL WEISENBERGER, A LAMY, P LLEBARIA, A DETAILLE, M LEVASSEURREGOURD, AC LEBLANC, JM AF GIOVANE, F EICHHORN, G MCKISSON, J WEINBERG, JL WEISENBERGER, A LAMY, P LLEBARIA, A DETAILLE, M LEVASSEURREGOURD, AC LEBLANC, JM TI PHOTOMULTIPLIER FOR OPTICALLY PROBING COMET HALLEY SO APPLIED OPTICS LA English DT Article AB A low mass eight-color channel photopolarimeter was developed for the Giotto spacecraft. Utilizing the spin of the spacecraft, a multichannel plate photomultiplier, and a unique optical design, the instrument required no moving parts to measure color and linear polarization. The photopolarimeter collected data as the spacecraft passed through the coma of Comet Halley on 13 and 14 Mar. 1986. This instrument's design, calibration, and reduction are discussed and some final results are presented. C1 NASA,DIV ASTROPHYS,WASHINGTON,DC 20546. SERV AERON,F-91371 VERRIERES BUISSON,FRANCE. TRAVERSE SIPHON,ASTRON SPATIALE LAB,F-13012 MARSEILLE,FRANCE. RP GIOVANE, F (reprint author), UNIV FLORIDA,SPACE ASTRON LAB,GAINESVILLE,FL 32609, USA. RI Eichhorn, Guenther/C-9480-2009 OI Eichhorn, Guenther/0000-0002-3032-1978 NR 8 TC 3 Z9 3 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 JUN 20 PY 1991 VL 30 IS 18 BP 2579 EP 2591 PG 13 WC Optics SC Optics GA FR740 UT WOS:A1991FR74000026 PM 20700247 ER PT J AU GRANT, WB BROWELL, EV HIGDON, NS ISMAIL, S AF GRANT, WB BROWELL, EV HIGDON, NS ISMAIL, S TI RAMAN SHIFTING OF KRF LASER-RADIATION FOR TROPOSPHERIC OZONE MEASUREMENTS SO APPLIED OPTICS LA English DT Article ID DIFFERENTIAL-ABSORPTION-LIDAR; STRATOSPHERIC OZONE; EXCIMER LASER; CONVERSION; STOKES; WAVELENGTHS; GENERATOR; PROFILES; HYDROGEN; REGIONS AB The differential absorption lidar (DIAL) measurement of tropospheric ozone requires use of high average power ultraviolet lasers operating at two appropriate DIAL wavelengths. Laboratory experiments have demonstrated that a KrF excimer laser can be used to generate several wavelengths with good energy conversion efficiencies by stimulated Raman shifting using hydrogen (H2) and deuterium (D2). Computer simulations for an airborne lidar have shown that these laser emissions can be used for the pecise (less than 5% random error) high resolution (200-m vertical, 3-km horizontal) measurement of ozone across the troposphere using the DIAL technique. In the region of strong ozone absorption, laser wavelengths of 277.0 and 291.7 nm were generated using H-2 and D2, respectively. In addition, a laser wavelength at 302.0 nm was generated using two cells in series, with the first containing D2 and the second containing H-2. The energy conversion efficiency for each wavelength was between 14 and 27%. RP GRANT, WB (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 37 TC 18 Z9 21 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 JUN 20 PY 1991 VL 30 IS 18 BP 2628 EP 2633 PG 6 WC Optics SC Optics GA FR740 UT WOS:A1991FR74000031 PM 20700252 ER PT J AU HAAS, MR HOLLENBACH, D ERICKSON, EF AF HAAS, MR HOLLENBACH, D ERICKSON, EF TI OBSERVATIONS OF [SI-II] (35-MU-M) AND [S-I] (25-MU-M) IN ORION - EVIDENCE FOR A WIND SHOCK NEAR IRC2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, ABUNDANCES; NEBULAE, ORION NEBULA; SHOCK WAVES ID FINE-STRUCTURE EXCITATION; STAR-FORMING REGION; PHOTODISSOCIATION REGIONS; MOLECULAR CLOUDS; LINE EMISSION; INTERSTELLAR SHOCKS; KL REGION; NEBULA; GAS; VELOCITY AB We have measured [Si II] (34.8-mu-m) and [S I] (25.2-mu-m) line emission from Orion's BN-KL region using a cryogenic grating spectrometer aboard NASA's Kuiper Airborne Observatory. The [Si II] observations were made with a 34" aperture and were spaced every 15" in a line through the shocked H-2 upsilon = 1-0 S(1) peaks 1 and 2. The bulk of the [Si II] emission in Orion is believed to originate in photodissociated gas at the interface between the H II region and its parent molecular cloud. However, there is a twofold enhancement in [Si II] near IRc2, which we attribute to a fast, dissociative J-shock where the wind from IRc2 impacts slower moving material. From model fits, we estimate the gas-phase depletion near IRc2 to be delta-Si approximately 0.3-1.0 relative to solar. The spatial distribution of the [Si II] emission has a centralized peak, unlike the H-2 and [O I] emission, which exhibit a double-lobed structure. A possible explanation is that the gas-phase silicon abundance is significantly larger near IRc2, where higher velocity shocks have destroyed more of the silicate grains. We have also measured the 25.2-mu-m line of S0 at two locations near H-2 peak 1 in a 29" aperture. This is the first unambiguous detection of the [S I] line in any source. Unlike the other far-infrared fine-structure lines and radio recombination lines observed to date, no appreciable contribution to the [S I] line is expected from the photodissociation region, where the sulfur is primarily S+. Hence this line is an important new diagnostic of shocked gas. The observed intensity is consistent with recent models of fast, dissociative J-shocks if H-2 reforms on grains in the postshock gas and the preshock density is approximately 10(5) cm-3. RP HAAS, MR (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 64 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 JUN 20 PY 1991 VL 374 IS 2 BP 555 EP 563 DI 10.1086/170144 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR742 UT WOS:A1991FR74200014 ER PT J AU RUBIN, RH SIMPSON, JP HAAS, MR ERICKSON, EF AF RUBIN, RH SIMPSON, JP HAAS, MR ERICKSON, EF TI AXISYMMETRICAL MODEL OF THE IONIZED-GAS IN THE ORION NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, ABUNDANCES; NEBULAE, ORION NEBULA; NEBULAE, STRUCTURE ID H-II-REGIONS; INFRARED LINE OBSERVATIONS; FORBIDDEN LINES; DIELECTRONIC RECOMBINATION; LOW-TEMPERATURES; GASEOUS NEBULAE; O-III; PHOTODISSOCIATION REGIONS; TRANSITION-PROBABILITIES; ELECTRON-EXCITATION AB Detailed ionization and thermal equilibrium models have been calculated for the ionized gas in the Orion Nebula with an axisymmetric two-dimensional "blister" geometry/density distribution viewed face-on in the foreground of OMC 1. Most of the physical detail of the microphysics and radiative transfer for our earlier spherical modeling is maintained, but the H II region is represented more realistically in view of the overall picture of the Orion Nebula. We compare the predicted surface brightnesses for a large set of lines with observations at different positions to determine the best-fitting physical parameters. Based on dynamical considerations, the plane-parallel density distribution is assumed exponential up to a maximum density and then level. The observed [O II] 3729/3726 angstrom line ratio near the Trapezium constrains this maximum to be 5000 cm-3. The 84 GHz continuum map of Gordon et al. is used with a chi-2 minimization technique to obtain a density at the exciting star of 163 cm-3, a scale height of 0.0483 pc, and the total number of ionizing photons s-1, N(Lyc) = 2.17 x 10(49) photons s-1. Approximately half the ionizing photons from the exciting source escape the nebula in density-bounded directions. As we found in our earlier spherical modeling, the best fit is obtained with a Kurucz stellar atmosphere with T(eff) = 37,000 K and log g = 4. Again, the noon ionization structure calls for a much hotter star. To simulate this, we increase the emergent stellar flux by a factor of 11 above 41 eV. The elemental abundances used in our best-fitting model are He/H = 0.1, C/H = 3.4 X 1O(-4), N/H = 6.8 x 10(-5), O/H = 4 x 10(-4), Ne/H = 8.1 x 10(-5), Si/H = 3.0 x 10(-6), S/H 8.5 x 10(-6), and Ar/H = 4.5 x 10(-6). 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], along lines of sight near the Trapezium. Our axisymmetric geometry results in roughly a hemisphere in front of the Trapezium that is density-bounded, while the area behind is ionization bounded, thus providing a natural mechanism by which to obtain higher densities in zones with singly ionized species. Strong lines in both singly and doubly ionized species (such as [O II] and [O III]) seen near the Trapezium are explained much more naturally with the present model than with a spherical model. RP RUBIN, RH (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 105 TC 154 Z9 154 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1991 VL 374 IS 2 BP 564 EP 579 DI 10.1086/170145 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR742 UT WOS:A1991FR74200015 ER PT J AU HARDING, AK DAUGHERTY, JK AF HARDING, AK DAUGHERTY, JK TI CYCLOTRON RESONANT SCATTERING AND ABSORPTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, BURSTS; LINE PROFILES; RADIATION MECHANISMS; RELATIVITY ID STRONG MAGNETIC-FIELDS; GAMMA-RAY BURSTS; COMPTON-SCATTERING; SPECTRA; LINES; ANNIHILATION; FEATURES; EMISSION AB We have made a detailed comparison of the relativistic cross sections for both first-order absorption and second-order scattering to determine the conditions under which the absorption cross section is a good approximation to the much more complex scattering cross section for purposes of modeling cyclotron lines in gamma-ray bursts. This requires a full treatment of the spin-dependent relativistic natural line widths as well as the derivation of the spin-dependent cross sections. Differences in both the cross sections and the line profiles will be presented for a range of field strengths, angles, and electron temperatures. Although the scattering and absorption cross sections are equal at the resonance energies (to second order in alpha), we find that their relative difference at one line width from resonance increases with field strength and harmonic number. The difference is also strongly dependent on the photon angle to the magnetic field and can be traced to the fact that resonant scattering does not have a standard Lorentz profile. For the field strength, 1.7 x 10(12); G, and angle inferred from the Ginga burst features, absorption is an excellent approximation for the profiles at the first and second harmonics. However, scattering cross sections should be used to model lines accurately at higher harmonics and higher field strengths. C1 UNIV N CAROLINA, DEPT COMP SCI, ASHEVILLE, NC 28804 USA. RP HARDING, AK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, CODE 665, GREENBELT, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 21 TC 73 Z9 73 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 JUN 20 PY 1991 VL 374 IS 2 BP 687 EP 699 DI 10.1086/170153 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR742 UT WOS:A1991FR74200023 ER PT J AU KO, YK KALLMAN, TR AF KO, YK KALLMAN, TR TI THE EFFECTS OF X-RAY ILLUMINATION ON ACCRETION DISK INTERIORS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACCRETION; X-RAYS, BINARIES ID ACTIVE GALACTIC NUCLEI; COMPTON-HEATED WINDS; VERTICAL STRUCTURE; CATACLYSMIC VARIABLES; DWARF NOVAE; BLACK-HOLES; MODELS; CORONAE; EMISSION; SPECTRA AB We investigate the structure of accretion disks illuminated by X-rays from a central compact object. At radii larger than a certain value, X-ray heating can dominate the viscous heating and determine the disk structure in a standard alpha-disk model. We calculate the disk structure resulting from X-ray illumination both analytically and numerically for low-mass X-ray binaries as well as for active galactic nuclei. We show that X-ray illumination does have important effects on the disk structures under a variety of circumstances and that instabilities may arise under significant X-ray heating. C1 UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. RP KO, YK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 51 TC 24 Z9 24 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 JUN 20 PY 1991 VL 374 IS 2 BP 721 EP 731 DI 10.1086/170156 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR742 UT WOS:A1991FR74200026 ER PT J AU KETO, E JERNIGAN, G BALL, R ARENS, J MEIXNER, M AF KETO, E JERNIGAN, G BALL, R ARENS, J MEIXNER, M TI HIGH ANGULAR RESOLUTION BROAD-BAND IMAGING IN THE MIDINFRARED - THE INFRARED BRIGHT GALAXY NGC-34 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, GENERAL; GALAXIES, INDIVIDUAL (NGC-34) ID IRAS AB We report on a high angular resolution (1") mid-IR image of the IR-bright galaxy NGC 34. The observation shows the mid-IR emission to be very compact, less-than-or-equal-to 2.3" x 1.7" (less-than-or-equal-to 870 x 640 pc, D = 78 Mpc, H0 = 75 km s-1 Mpc-1). This and previous observations indicate sizes smaller than predicted by starburst models for the emission. The achieved sensitivity, 15 mJy minutes-1/2 arcsec-2, (1-sigma NEFD DELTA-lambda = 5-mu-m) is the highest sensitivity ever obtained for any observation with a mid-IR array camera. C1 UNIV HAWAII,NASA INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP KETO, E (reprint author), UNIV ILLINOIS,ASTRON IMAGING LAB,1002 W GREEN ST,URBANA,IL 61801, USA. NR 7 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 JUN 20 PY 1991 VL 374 IS 2 BP L29 EP L31 DI 10.1086/186064 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FR745 UT WOS:A1991FR74500001 ER PT J AU SHIH, TIP BAILEY, RT NGUYEN, HL ROELKE, RJ AF SHIH, TIP BAILEY, RT NGUYEN, HL ROELKE, RJ TI ALGEBRAIC GRID GENERATION FOR COMPLEX GEOMETRIES SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE GRID GENERATION; SURFACE GENERATION ID FINITE-DIFFERENCE; COMPUTATIONS; EQUATIONS; CONFIGURATIONS; SYSTEMS AB An efficient computer programme called GRID2D/3D has been developed to generate single and composite grid systems within geometrically complex two- and three-dimensional (2D and 3D) spatial domains that can deform with time. GRID2D/3D generates single grid systems by using algebraic grid generation methods based on transfinite interpolation. The distribution of grid points within the spatial domain is controlled by stretching functions and grid lines can intersect boundaries of the spatial domain orthogonally. GRID2D/3D generates composite grid systems by patching together two or more single grid systems. The patching can be discontinuous or continuous. For 2D spatial domains the boundary curves are constructed by using either cubic or tension spline interpolation. For 3D spatial domains the boundary surfaces are constructed by using a new technique, developed in this study, referred to as 3D bidirectional Hermite interpolation. C1 UNIV FLORIDA,DEPT MECH ENGN,GAINESVILLE,FL 32611. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SHIH, TIP (reprint author), CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213, USA. NR 51 TC 29 Z9 31 U1 0 U2 3 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 JUN 20 PY 1991 VL 13 IS 1 BP 1 EP 31 DI 10.1002/fld.1650130102 PG 31 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA FW307 UT WOS:A1991FW30700001 ER PT J AU PARAMESWARAN, K ROSE, KO MURTHY, BVK OSBORN, MT MCMASTER, LR AF PARAMESWARAN, K ROSE, KO MURTHY, BVK OSBORN, MT MCMASTER, LR TI COMPARISON OF AEROSOL EXTINCTION PROFILES FROM LIDAR AND SAGE-II DATA AT A TROPICAL STATION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC AEROSOL; SIZE DISTRIBUTION AB Aerosol extinction profiles obtained from lidar data at Trivandrum (8.6-degrees-N, 77-degrees-E) are compared with corresponding Stratospheric Aerosol and Gas Experiment (SAGE) II extinction profiles. The agreement between the two is found to be satisfactory. The extinction profiles obtained by both the experiments showed a prominent peak at 23-24 km altitude in the stratosphere. The study revealed large variability in upper tropospheric extinction with location (latitude). C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. ST SYST CORP, HAMPTON, VA 23665 USA. RP PARAMESWARAN, K (reprint author), VIKRAM SARABHAI SPACE CTR, SPACE PHYS LAB AD6, TRIVANDRUM 695022, KERALA, INDIA. NR 19 TC 14 Z9 14 U1 2 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 JUN 20 PY 1991 VL 96 IS D6 BP 10861 EP 10866 DI 10.1029/91JD01044 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FV278 UT WOS:A1991FV27800005 ER PT J AU ABBAS, MM KUNDE, VG BRASUNAS, JC HERMAN, JR MASSIE, ST AF ABBAS, MM KUNDE, VG BRASUNAS, JC HERMAN, JR MASSIE, ST TI NIGHTTIME REACTIVE NITROGEN MEASUREMENTS FROM STRATOSPHERIC INFRARED THERMAL EMISSION OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CRYOGENIC FOURIER SPECTROMETER; SOLAR ABSORPTION-SPECTRA; CHLORINE NITRATE; OZONE; N2O; HNO3; CLONO2; PROFILES; OXIDE; O-3 AB Infrared thermal emission spectra of the Earth's atmosphere in the 700-2000 cm-1 region were obtained with a cryogenically cooled high-resolution interferometer spectrometer on a balloon flight from Palestine, Texas, on September 15-16. 1986. The observations exhibit spectral features of a number of stratospheric constituents, including important species of the reactive nitrogen family. In this paper we present an analysis of the observed data for simultaneously measured vertical distributions of O3, H2O, N2O, NO2, N2O5, HNO3, and CIONO2. These measurements permit the first direct determination of the nighttime total reactive nitrogen concentrations, and the partitioning of the important elements of the NO(x) family. Comparisons of the total reactive nitrogen budget are made with the measurements by the ATMOS experiment and with the predictions of one-dimensional and two-dimensional photochemical models. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP ABBAS, MM (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, ATOM PHYS BRANCH, MAIL CODE ES55, HUNTSVILLE, AL 35812 USA. RI brasunas, john/I-2798-2013 NR 31 TC 16 Z9 16 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 JUN 20 PY 1991 VL 96 IS D6 BP 10885 EP 10897 DI 10.1029/91JD00341 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FV278 UT WOS:A1991FV27800008 ER PT J AU KIRCHHOFF, VWJH BARNES, RA TORRES, AL AF KIRCHHOFF, VWJH BARNES, RA TORRES, AL TI OZONE CLIMATOLOGY AT NATAL, BRAZIL, FROM INSITU OZONESONDE DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONCENTRATION CELL OZONESONDE; TROPOSPHERIC OZONE; PROFILES AB Results are presented from analysis of a large ozone profile data set obtained from balloon ozonesonde soundings made at Natal, Brazil (6-degrees-S, 35-degrees-W) during the last 10 years (1978-1988). The measurements have been made through an Instituto Nacional de Pesquisas Espaciais (INPE)/NASA long-term collaboration program. The balloons were released by the Brazilian Air Force at the Natal rocket range. The data set is sufficiently large to provide useful climatology on the average ozone concentration behavior and its seasonal variation. The day-to-day ozone concentration variability in the troposphere is rather large, giving standard deviations of about 30-40% for seasonal averages. Maximum ozone concentrations occur during local spring, September-October, and minimum concentrations during late autumn, April-May. The seasonal variation in the troposphere is much larger than in the stratosphere. If there were no seasonal variation at all in the stratosphere, the seasonal variation observed in the troposphere alone would be strong enough to drive a total ozone column variation of about 5%, which is about one half the size of the variation observed in the Natal Dobson spectrophotometer data. The ozone concentration at Natal increases with height between the surface and about 500 mbar, almost linearly, from about 15 parts per billion by volume (ppbv) to about 38 ppbv, in autumn. For the spring average the ozone concentration increases from about 25 ppbv at the surface to about 66 ppbv at 500 mbar. The sonde data suggest that limitations in aneroid pressure sensors used until 1986 caused the Natal sondes to indicate too much ozone above 6 mbar. Because of the relative sparsity and uneven distribution in time of the ozone soundings, the data are not adequate to study ozone trends. The Dobson data time series shows no definitive ozone trend but displays a pronounced quasi-biennial oscillation in ozone. C1 CHEMAL INC, WALLOPS ISL, VA 23337 USA. NASA, GODDARD SPACE FLIGHT CTR, WALLOPS FLIGHT FACIL, WALLOPS ISL, VA 23337 USA. RP KIRCHHOFF, VWJH (reprint author), INST NACL PESQUISAS ESPACIAIS, SCT, CP 515, BR-12201 SAO JOSE CAMPOS, SP, BRAZIL. NR 27 TC 54 Z9 54 U1 1 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 JUN 20 PY 1991 VL 96 IS D6 BP 10899 EP 10909 DI 10.1029/91JD01212 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FV278 UT WOS:A1991FV27800009 ER PT J AU SRIVASTAVA, SK KRISHNAKUMAR, E SOUZA, ACDE AF SRIVASTAVA, SK KRISHNAKUMAR, E SOUZA, ACDE TI CROSS-SECTIONS FOR THE FORMATION OF NEGATIVE-IONS BY ELECTRON-IMPACT ON SILANE SO INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES LA English DT Article AB Cross-sections and appearance potentials for the production of various negative ion species by electron impact on SiH4 have been measured. They are compared with two previous measurements which widely differ with each other. Hess' law has been applied to predict the various possible channels of dissociation. RP SRIVASTAVA, SK (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1176 J9 INT J MASS SPECTROM JI Int. J. Mass Spectrom. Ion Process. PD JUN 15 PY 1991 VL 107 IS 1 BP 83 EP 89 DI 10.1016/0168-1176(91)85074-V PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FT943 UT WOS:A1991FT94300006 ER PT J AU WEIZER, VG FATEMI, NS AF WEIZER, VG FATEMI, NS TI THE INFLUENCE OF INTERSTITIAL GA AND INTERFACIAL AU2P3 ON THE ELECTRICAL AND METALLURGICAL BEHAVIOR OF AU-CONTACTED III-V-SEMICONDUCTORS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SCHOTTKY-BARRIER FORMATION; INDIUM-PHOSPHIDE; INP INTERACTION; GOLD CONTACTS; RESISTANCE; SYSTEM; FILMS AB The introduction of a very small amount of Ga into Au contact metallization on InP is shown to have a significant effect on both the metallurgical and electrical behavior of that contact system. Ga atoms in the interstices of the Au lattice are shown to be effective in preventing the solid-state reactions that normally take place between Au and InP during contact sintering. In addition to suppressing the metallurgical interaction, the presence of small amounts of Ga is shown to cause an order of magnitude reduction in the specific contact resistivity. Evidence is presented that the reactions of GaP and GaAs with Au contacts are also drastically affected by the presence of Ga. The sintering behavior of the Au-GaP and the Au-GaAs systems (as contrasted with that of the Au-InP system) is explained as due to the presence of interstitial Ga in the contact metallization. Finally the large, two-to-three order of magnitude drop in the contact resistance that occurs in the Au-InP system upon sintering at 400-degrees-C is shown to be a result of the formation of an Au2P3 layer at the metal-semiconductor interface. Contact resistivities in the 10(-6) OMEGA-cm2 range are obtained for as-deposited Au on InP when a thin (20 angstrom) layer of Au2P3 is introduced between the InP and the Au contacts. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP WEIZER, VG (reprint author), NASA,LEWIS RES CTR,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 26 TC 27 Z9 27 U1 1 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUN 15 PY 1991 VL 69 IS 12 BP 8253 EP 8260 DI 10.1063/1.347432 PG 8 WC Physics, Applied SC Physics GA FU812 UT WOS:A1991FU81200045 ER PT J AU LINDH, R RICE, JE LEE, TJ AF LINDH, R RICE, JE LEE, TJ TI THE ENERGY SEPARATION BETWEEN THE CLASSICAL AND NONCLASSICAL ISOMERS OF PROTONATED ACETYLENE - AN EXTENSIVE STUDY IN ONE-PARTICLE AND N-PARTICLE SPACE SATURATION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; COUPLED-CLUSTER; INFRARED-SPECTROSCOPY; WAVE-FUNCTIONS; CARBO-IONS; C2H3+; FREQUENCIES AB The energy separation between the classical and nonclassical forms of protonated acetylene has been reinvestigated in light of the recent experimentally deduced lower bound to this value of 6.0 kcal/mol. The objective of the present study is to use state-of-the-art ab initio quantum mechanical methods to establish this energy difference to within chemical accuracy (i.e., about 1 kcal/mol). The one-particle basis sets include up to g-type functions and the electron correlation methods include single and double excitation coupled-cluster (CCSD), the CCSD(T) extension, multireference configuration interaction, and the averaged coupled-pair functional methods. A correction for zero-point vibrational energies has also been included, yielding a best estimate for the energy difference between the classical and nonclassical forms of 3.7 +/- 1.3 kcal/mol. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP LINDH, R (reprint author), IBM CORP, DIV RES, ALMADEN RES CTR, 650 HARRY RD, SAN JOSE, CA 95120 USA. RI Lindh, Roland/F-3471-2012; Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Lindh, Roland/0000-0001-7567-8295; Rice, Julia/0000-0001-5059-5127; NR 32 TC 48 Z9 48 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 15 PY 1991 VL 94 IS 12 BP 8008 EP 8014 DI 10.1063/1.460134 PN 1 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FQ584 UT WOS:A1991FQ58400044 ER PT J AU YIN, FL FUNG, IY AF YIN, FL FUNG, IY TI NET DIFFUSIVITY IN OCEAN GENERAL-CIRCULATION MODELS WITH NONUNIFORM GRIDS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID WORLD OCEAN; RESOLUTION; DISTRIBUTIONS; SENSITIVITY; SIMULATIONS; RADIOCARBON; EDDIES AB The numerical vertical diffusivity K(num), embedded in a numerical ocean general circulation model with nonuniform vertical grid, is estimated. It is shown that in a downwelling region, K(num) is negative for a grid with grid size increasing with depth. When the grid size increment, or the downward vertical velocity, is large, K(num) may exceed the vertical diffusivity specified and may result in a negative effective vertical diffusivity. Therefore care needs to be taken to specify the vertical diffusivity in a numerical model with nonuniform grid, and a lower bound is generally imposed in order to avoid an unphysical negative value. Some possible effects of the negative effective diffusivity are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP YIN, FL (reprint author), UNIV WASHINGTON,JOINT INST STUDY ATMOSPHERE & OCEAN,GJ-40,SEATTLE,WA 98195, USA. NR 14 TC 26 Z9 26 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 JUN 15 PY 1991 VL 96 IS C6 BP 10773 EP 10776 DI 10.1029/91JC00883 PG 4 WC Oceanography SC Oceanography GA FT343 UT WOS:A1991FT34300025 ER PT J AU GROBSTEIN, TL SIVASHANKARAN, S WELSCH, G PANIGRAHI, N MCGERVEY, JD BLUE, JW AF GROBSTEIN, TL SIVASHANKARAN, S WELSCH, G PANIGRAHI, N MCGERVEY, JD BLUE, JW TI FATIGUE DAMAGE ACCUMULATION IN NICKEL PRIOR TO CRACK INITIATION SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID COPPER SINGLE-CRYSTALS; VACANCY CLUSTERS; METALS; STABILITY AB The accumulation of lattice defects during fatigue cycling of nickel was investigated by electrical resistivity measurements, positron annihilation lifetime spectroscopy and transmission electron microscopy. Dislocations and vacancy clusters were found to be the main defect types. During cycling of axial and flexural samples at constant load amplitude, the dislocations form a saturated structure early in the fatigue life. This saturated structure consists of a cellular dislocation matrix, in which persistent slip bands (PSBs) begin to operate after the saturation has been established. Vacancies and vancancy clusters are formed during fatigue as a consequence of repetitive dislocation glide in the PSB structure. When PSBs operate, the matrix is assumed to be dormant, allowing vacancies to accumulate preferentially in the PSBs. The increase in vacancy concentration then accounts for the monotonic accumulation of fatigue damage, which points to the importance of vacancy accumulation as a precursor to crack nucleation. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. RP GROBSTEIN, TL (reprint author), NASA,LEWIS RES CTR,CLEVELAND CLIN FDN,21000 BROOKPK RD,MS 49-2,CLEVELAND,OH 44135, USA. NR 34 TC 23 Z9 24 U1 2 U2 6 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 JUN 15 PY 1991 VL 138 IS 2 BP 191 EP 203 DI 10.1016/0921-5093(91)90688-J PG 13 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA FU710 UT WOS:A1991FU71000004 ER PT J AU ANDREWS, JR SCHUSTER, GL AF ANDREWS, JR SCHUSTER, GL TI HIGH-POWER AND HIGH-SPATIAL-COHERENCE BROAD-AREA POWER-AMPLIFIER SO OPTICS LETTERS LA English DT Article ID TRAVELING-WAVE AMPLIFIER; INJECTION LOCKING; DIODE-ARRAY; SEMICONDUCTOR-LASER; OPERATION AB A broad-area AlGaAs amplifier operating cw has delivered 425 mW of total power with 342 mW in a single lobe diverging at 1.02 x the diffraction limit (FWHM 0.483-degrees, 87.4-mu-m actual aperture) for a master oscillator input power of 70 mW. The spatial coherence of the amplifier output is 0.97, and the mutual spatial coherence between the oscillator and amplifier is 0.96. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP ANDREWS, JR (reprint author), XEROX CORP,WEBSTER RES CTR,800 PHILLIPS RD 0114-20D,WEBSTER,NY 14580, USA. NR 18 TC 19 Z9 19 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD JUN 15 PY 1991 VL 16 IS 12 BP 913 EP 915 DI 10.1364/OL.16.000913 PG 3 WC Optics SC Optics GA FQ939 UT WOS:A1991FQ93900011 PM 19776827 ER PT J AU VASQUEZ, RP OLSON, WL AF VASQUEZ, RP OLSON, WL TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF CHEMICALLY ETCHED TL2BA2CACU2O8+X THIN-FILM SURFACES SO PHYSICA C LA English DT Article ID SUPERCONDUCTORS; SPECTRA; TL; PHOTOEMISSION; YBA2CU3O7-X; RESISTANCE; CORE; XPS AB X-ray photoelectron spectroscopy (XPS) is used to characterize the surfaces of epitaxial c-axis oriented Tl2Ba2CaCu2O8 + x (TBCCO) thin films which have been chemically etched in a solution of Br2 in absolute ethanol. Comparison of the XPS core level spectra presented here with spectra in the literature obtained from single crystals cleaved in vacuum or polycrystalline pellets fractured or scraped in vacuum shows that the chemically etched thin films exhibit lower levels of nonsuperconducting surface species. Cation disorder is found to be restricted to the Ba sites. XPS valence band spectra show a clear Fermi edge, indicating that the room temperature conductivity near the surface is metallic. To the authors' knowledge, this is the first report of a clear Fermi edge detected on TBCCO. Exposure of the chemically etched films to air results in a significant surface degradation even for exposure times as short as 1 min. C1 SUPERCONDUCTOR TECHNOL INC,SANTA BARBARA,CA 93111. RP VASQUEZ, RP (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 20 TC 19 Z9 19 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD JUN 15 PY 1991 VL 177 IS 1-3 BP 223 EP 229 DI 10.1016/0921-4534(91)90321-O PG 7 WC Physics, Applied SC Physics GA FV360 UT WOS:A1991FV36000034 ER PT J AU KSENDZOV, A GRUNTHANER, FJ LIU, JK RICH, DH TERHUNE, RW WILSON, BA AF KSENDZOV, A GRUNTHANER, FJ LIU, JK RICH, DH TERHUNE, RW WILSON, BA TI ABSORPTION AND PHOTOLUMINESCENCE OF ULTRATHIN PSEUDOMORPHIC INAS/GAAS QUANTUM-WELLS SO PHYSICAL REVIEW B LA English DT Article ID OPTICAL-PROPERTIES; MOBILITY; EXCITONS AB We present absorption data for 2-4-monolayer InAs/GaAs single quantum wells obtained at 77 K using a polarization-based measurement technique. The spectral contribution of the optical loss features arising from bulk GaAs was minimized using the polarization selectivity of absorption in single quantum wells. Based on polarization properties and the results of an envelope-function calculation, the double structure observed in the spectra is attributed to transitions involving confined heavy holes and both confined and unconfined electron states. No evidence of transitions with the participation of confined light holes was found. Well-width fluctuations deduced from the absorption data are a fraction of one monolayer in our samples. The absorption lines were broadened, indicating interface roughness on a scale comparable to the exciton diameter. A single photoluminescence peak overlapping with the lower-energy portion of the fundamental absorption feature was observed in all the samples at 77 K. Although the absorption line of the undoped two-monolayer sample displayed the least broadening, the photoluminescence was red shifted by approximately 70 meV relative to the absorption feature. Presumably, this behavior indicates long-range diffusion of the excitations. Measurements of the temperature dependence and pump-power dependence of the red shift in this sample support this interpretation. RP KSENDZOV, A (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 23 TC 10 Z9 10 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUN 15 PY 1991 VL 43 IS 18 BP 14574 EP 14580 DI 10.1103/PhysRevB.43.14574 PG 7 WC Physics, Condensed Matter SC Physics GA FW755 UT WOS:A1991FW75500026 ER PT J AU HOLMAN, R KOLB, EW VADAS, SL WANG, Y AF HOLMAN, R KOLB, EW VADAS, SL WANG, Y TI SCALE-INVARIANT EXTENDED INFLATION SO PHYSICAL REVIEW D LA English DT Article ID FALSE-VACUUM DECAY; PHASE-TRANSITION; DENSITY PERTURBATIONS; UNIVERSE SCENARIO; SYMMETRY-BREAKING; COSMOLOGY; PRESCRIPTION; FLUCTUATIONS; BARYOGENESIS; GENERATION AB We propose a model of extended inflation which makes use of the nonlinear realization of scale invariance involving the dilaton coupled to an inflaton field whose potential admits a metastable ground state. The resulting theory resembles the Jordan-Brans-Dicke version of extended inflation. However, quantum effects, in the form of the conformal anomaly, generate a mass for the dilaton, thus allowing our model to evade the problems of the original version of extended inflation. We show that extended inflation can occur for a wide range of inflaton potentials with no fine-tuning of dimensionless parameters required. Furthermore, we also find that it is quite natural for the extended-inflation period to be followed by an epoch of slow-rollover inflation as the dilaton settles down to the minimum of its induced potential. C1 FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP HOLMAN, R (reprint author), CARNEGIE MELLON UNIV,DEPT PHYS,PITTSBURGH,PA 15213, USA. RI Wang, Yun/B-5724-2011 OI Wang, Yun/0000-0002-4749-2984 NR 42 TC 53 Z9 53 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 JUN 15 PY 1991 VL 43 IS 12 BP 3833 EP 3845 DI 10.1103/PhysRevD.43.3833 PG 13 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA FT074 UT WOS:A1991FT07400007 ER PT J AU YARWOOD, G NIKI, H MAKER, PD AF YARWOOD, G NIKI, H MAKER, PD TI KINETIC AND IR SPECTROSCOPIC STUDIES OF FORMYL BROMIDE (HCOBR) FORMED VIA THE REACTION HCO+BR2-]HCOBR+BR SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID CL ATOM; FTIR; FLUORIDE AB An FTIR spectroscopic study of the visible photolysis of Br2-HCHO-N2 mixtures has shown that the major carbon-containing product is HCOBr, formed via Br + HCHO --> HCO + HBr followed by HCO + Br2 --> HCOBr --> Br. HCOBr was found to be highly susceptible to heterogeneous decomposition to CO + HBr. This photochemical method has been used for the quantitative in situ preparation of HCOBr and IR spectra have been obtained of the v1-v4 and v6 bands of HCOBr, DCOBr, and H13COBr. The spectra observed are consistent with a planar structure. HCOBr was also detected in the photolysis of Br2-C2H2-O2 mixtures and the kinetic analysis of its yield as a function of the C2H2 conversion has shown the rate constant for the Br + HCOBr reaction to be < 4 x 10(-14) cm3 molecule-1 s-1. C1 YORK UNIV,CTR ATMOSPHER CHEM,4700 KEELE ST,N YORK M3J 1P3,ONTARIO,CANADA. YORK UNIV,DEPT CHEM,N YORK M3J 1P3,ONTARIO,CANADA. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 19 TC 21 Z9 21 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 JUN 13 PY 1991 VL 95 IS 12 BP 4773 EP 4777 DI 10.1021/j100165a033 PG 5 WC Chemistry, Physical SC Chemistry GA FR756 UT WOS:A1991FR75600033 ER PT J AU FICHTEL, CE OZEL, ME STONE, RG SREEKUMAR, P AF FICHTEL, CE OZEL, ME STONE, RG SREEKUMAR, P TI COSMIC-RAY DISTRIBUTION AND THE DYNAMIC BALANCE IN THE LARGE MAGELLANIC CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS, GENERAL; GALAXIES, MAGELLANIC CLOUDS; GAMMA RAYS, GENERAL; PARTICLE ACCELERATION ID RADIO-CONTINUUM SURVEY; MAGNETIC-FIELD; 1.4 GHZ; EMISSION; GALAXY; ENERGIES; GAS AB Observations of the Large Magellanic Cloud (LMC), particularly in the radio and high-energy gamma-ray range, offer the possibility of understanding the distribution of cosmic rays in a galaxy other than our own and determining the role that these quantities play in galactic dynamic balance. The LMC has the advantage of being our nearest galactic neighbor and of being observed at a not too large an angle to the normal to the plane. The cosmic-ray energy density distribution for the LMC is calculated quantitatively based on the concept of dynamic balance and a scale of coupling between the cosmic rays and matter in a range allowed by present observations. Based on the very slowly varying ratio of the cosmic-ray electron to nucleon energy density ratio with relevant local galactic conditions and the close similarities to our galaxy, the cosmic-ray nucleon density distribution in the LMC is also determined from the cosmic-ray electron density distribution deduced from synchrotron radiation measurements in a manner consistent with dynamic balance. It is seen that within uncertainties there is quantitative agreement between the two for a cosmic-ray, matter coupling scale of about 21/2 kiloparsecs both in terms of magnitude and distribution, thus supporting both the concept of dynamic balance and the galactic origin of the bulk of cosmic rays. Future gamma-ray astronomy measurement above approximately 10(2) MeV will be able to provide a test of this cosmic-ray density distribution for the LMC. C1 CUKUROVA UNIV,DEPT PHYS,ADANA 01330,TURKEY. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP FICHTEL, CE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 660,GREENBELT,MD 20771, USA. NR 42 TC 34 Z9 34 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 JUN 10 PY 1991 VL 374 IS 1 BP 134 EP 141 DI 10.1086/170103 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP765 UT WOS:A1991FP76500013 ER PT J AU MORIARTYSCHIEVEN, GH SNELL, RL HUGHES, VA AF MORIARTYSCHIEVEN, GH SNELL, RL HUGHES, VA TI PROBING THE CORE OF CEPHEUS-A - MILLIMETER AND SUBMILLIMETER OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, MOLECULES; NEBULAE, STRUCTURE; STARS, FORMATION ID OB3 MOLECULAR CLOUD; CEP-A; INFRARED OBSERVATIONS; OPTICAL-PROPERTIES; RADIO OBSERVATIONS; STAR FORMATION; MASS OUTFLOW; CONTINUUM; EMISSION; REGIONS AB We present moderate and high angular resolution (40"-7") maps of the core of the Cepheus A star-forming region using CS J = 3-2 and J = 7-6 emission, which traces the dense gas component of the cloud core, and using far-infrared (450 and 800-mu-m) continuum emission tracing the warm dust component. Three regimes in the core are traced by these observations: (1) a small (approximately 0.14 pc), nearly circular central core of high density (1-10 x 10(6) cm-3) and temperature (30-100 K) containing at least 25% of the mass and which contains the active early-type star formation, (2) an extended (0.5 x 0.25 pc), NE-SW oriented core of mass 200-300 M., temperature 30-40 K, and average density n(H2) approximately 10(5) cm-3 and which, together with the central core, contains 60%-80% of the total core mass, and (3) an extended core envelope of dimensions 0.5 x 0.85 pc oriented primarily north-south, and at a lower density (> 10(4) cm-3). The velocity structure of the core suggests that it is being disrupted by the high-velocity winds driving the molecular outflow and is not due to a rotating circumstellar disk. Although NH3 (J, K) = (1, 1) emission is more easily excited at lower densities than CS and HCN, the previously reported NH3 emitting region is considerably smaller than that traced by either of the other two molecules, indicating that the abundance of ammonia must be significantly lower than expected. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV MASSACHUSETTS,FIVE COLL RADIO ASTRON OBSERV,AMHERST,MA 01003. RP MORIARTYSCHIEVEN, GH (reprint author), QUEENS UNIV,DEPT PHYS,KINGSTON K7L 3N6,ONTARIO,CANADA. NR 33 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1991 VL 374 IS 1 BP 169 EP 176 DI 10.1086/170106 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP765 UT WOS:A1991FP76500016 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI BLUE LOOPS DURING CORE HELIUM BURNING AS THE CONSEQUENCE OF MODERATE CONVECTIVE ENVELOPE OVERSHOOTING IN STARS OF INTERMEDIATE TO HIGH MASS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EVOLUTION; STARS, INTERIORS; STARS, SUPERGIANTS ID MAIN-SEQUENCE; EVOLUTION AB New calculations of stellar evolutionary sequences without semiconvection in any phase have unexpectedly turned up, for stars in the mass range 3-30 M., an irregular pattern of blue loops on the H-R diagram during the core helium-burning phase. Blue loops occur for 3 and 10 M., but not for 5, 7, 15, and 30 M.. It is found, however, that the models near the bottom of the red supergiant branch are only marginally stable against small inward displacements of the former base of the outer convection zone when it was deepest, for the stellar mass range 5-15 M.. As a consequence, convective envelope overshooting need only penetrate a distance of approximately 0.3 of a local pressure scale height to promote a delayed blue loop in these particular sequences. In conformity with previous work, the triggering mechanism for the blue loop appears to be proximity of the hydrogen-burning shell to the hydrogen discontinuity at the former base of the outer convection zone. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 27 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 JUN 10 PY 1991 VL 374 IS 1 BP 288 EP 290 DI 10.1086/170117 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP765 UT WOS:A1991FP76500027 ER PT J AU NITTA, N WHITE, SM KUNDU, MR GOPALSWAMY, N HOLMAN, GD BROSIUS, JW SCHMELZ, JT SABA, JLR STRONG, KT AF NITTA, N WHITE, SM KUNDU, MR GOPALSWAMY, N HOLMAN, GD BROSIUS, JW SCHMELZ, JT SABA, JLR STRONG, KT TI CORONAL MAGNETIC-STRUCTURES OBSERVING CAMPAIGN .1. SIMULTANEOUS MICROWAVE AND SOFT-X-RAY OBSERVATIONS OF ACTIVE REGIONS AT THE SOLAR LIMB SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, MAGNETIC FIELDS; SUN, RADIO RADIATION; SUN, X-RAYS ID LOOPS; LINE AB Using simultaneous microwave and soft X-ray measurements made with the Very Large Array (VLA) at 6 and 20 cm and the X-ray Polychromator (XRP) aboard the Solar Maximum Mission (SMM), we have studied two active regions near the solar limb. These observations were taken as part of the Coronal Magnetic Structures Observing Campaign (CoMStOC), a collaboration designed to study the magnetic field in the solar corona. The images in soft X-rays and at 20 cm wavelength are similar: both show peaks above the active regions and extended bridge of emission 200,000 km long connecting the two regions. The brightness temperature of the 20 cm emission is lower than that predicted from the X-ray emitting material, however; it can be attributed to free-free emission in cooler (< 10(6) K) plasma not visible to XRP, with an optical depth approximately 1. The 6 cm emission is concentrated at lower altitudes and in a approximately 160,000 km long bundle of loops in the northern active region. Comparison of the 6 cm map with the potential magnetic field lines computed from photospheric magnetic fields (measured 2 days earlier) indicates that the 6 cm emission is associated with fields of less than approximately 200 G. Such fields would be too weak to attribute the observed 6 cm emission to gyroresonance radiation. Analysis of the 6 cm loop bundle indicates that it is strongly asymmetric, with the magnetic field in the northern leg approximately 2 times stronger than in the southern leg; the 6 cm emission most likely arises from a combination of hot (greater-than-or-equal-to 2 x 10(6) K) and cool plasmas, while the 20 cm emission becomes optically thick in the cooler (approximately 9 x 10(3) K) plasma. We estimate an Alfven speed approximately 7000 km s-1 and ratio of electron gyrofrequency to plasma frequency approximately 1.0 in the northern leg of the 6 cm loop. C1 APPL RES CORP,LOCKHEED,LANDOVER,MD. UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RI Holman, Gordon/C-9548-2012; Gopalswamy, Nat/D-3659-2012 NR 25 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1991 VL 374 IS 1 BP 374 EP 385 DI 10.1086/170128 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP765 UT WOS:A1991FP76500038 ER PT J AU TAMURA, M GATLEY, I WALLER, W WERNER, MW AF TAMURA, M GATLEY, I WALLER, W WERNER, MW TI 2 MICRON MORPHOLOGY OF CANDIDATE PROTOSTARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; NEBULAE, INDIVIDUAL (TAURUS DARK CLOUD); NEBULAE, INDIVIDUAL (L1489); NEBULAE, INDIVIDUAL (L1536); NEBULAE, INDIVIDUAL (L1551); NEBULAE, REFLECTION; STARS, FORMATION ID YOUNG STELLAR OBJECTS; T-TAURI STARS; VELOCITY MOLECULAR GAS; HERBIG-HARO OBJECTS; DARK CLOUDS; INFRARED POLARIMETRY; DENSE CORES; CO; RESOLUTION; EVOLUTION AB We have conducted a near-infrared imaging survey of low-luminosity cold IRAS sources in Taurus. The sample is color and flux limited, consisting of (1) 16 optically invisible sources, probably still deeply embedded in the Taurus dark clouds and believed to be low-mass protostar candidates, and (2) eight optical T Tauri-like stars. All 24 sources were identified with near-infrared counterparts; one is entirely nebulous without a point-like source, and the others generally have an unresolved peak with or without an extended component at 2.2-mu-m. Thirteen of 16 invisible sources appear to be associated with infrared nebulosity. Overall, 18 of the 24 sample sources are associated with infrared and/or optical nebulosity about 1000 to 10,000 AU in size. Seven of the invisible sources show a clear bipolar or monopolar morphology, suggestive of a close relation of the nebulosity with a bipolar mass outflow. The nebulosity is most likely due to scattering of radiation from the central source by the dust associated with the mass outflow extending to the poles of a circumstellar dust disk. C1 NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV WASHINGTON,SEATTLE,WA 98195. RP TAMURA, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 43 Z9 43 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 JUN 10 PY 1991 VL 374 IS 1 BP L25 EP & DI 10.1086/186063 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP766 UT WOS:A1991FP76600007 ER PT J AU PRESTAGE, JD WILLIAMS, A MALEKI, L DJOMEHRI, MJ HARABETIAN, E AF PRESTAGE, JD WILLIAMS, A MALEKI, L DJOMEHRI, MJ HARABETIAN, E TI DYNAMICS OF CHARGED-PARTICLES IN A PAUL RADIOFREQUENCY QUADRUPOLE TRAP SO PHYSICAL REVIEW LETTERS LA English DT Article ID ONE-COMPONENT PLASMA; LASER-COOLED IONS; ORDER-CHAOS TRANSITION; PHASE; CLOUDS AB We have carried out a molecular-dynamics simulation of hundreds of ions confined in a Paul trap. The simulation includes the trapped particles' micromotion and interparticle Coulomb interactions. We have implemented a random walk in velocity to bring the secular motion to a given temperature which we have numerically measured. When the coupling-GAMMA is large the ions form concentric shells which undergo a quadrupole oscillation at the rf frequency, while the ions within a shell form a 2D hexagonal lattice. Ion clouds at 5 mK show no rf heating for q(z) less-than-or-similar-to 0.6, whereas rapid heating is seen for q(z) = 0.8. RP PRESTAGE, JD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 20 TC 45 Z9 46 U1 1 U2 13 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 JUN 10 PY 1991 VL 66 IS 23 BP 2964 EP 2967 DI 10.1103/PhysRevLett.66.2964 PG 4 WC Physics, Multidisciplinary SC Physics GA FP871 UT WOS:A1991FP87100007 ER PT J AU TAYLOR, PT AF TAYLOR, PT TI INVESTIGATION OF PLATE BOUNDARIES IN THE EASTERN INDIAN-OCEAN USING MAGSAT DATA SO TECTONOPHYSICS LA English DT Article ID SATELLITE MAGNETIC-ANOMALIES; HEAT-FLOW; CONSTRAINTS; MODEL AB Plate boundaries are regions of significant tectonic activity. In the area between the Ninety East Ridge and Sumatra, seismicity and bathymetry suggest the presence of differing plate boundaries and other tectonic features (e.g. N-S trending fracture zones and the Southwest Asian continental margin). A Magsat anomaly map was made of this area in order to study the magnetic signature of these major plate boundaries at satellite altitude. Forty (16 descending and 24 ascending) low-altitude (340-360 km) Magsat orbits were selected over this region (90-degrees-105-degrees-E, 8-degrees-S-4-degrees-N). These profiles were chosen to ensure the most noise-free data. A magnetic anomaly map was derived from these data using the technique of minimizing orbital cross-over errors, and was contoured at 0.5 nT. The largest magnetic anomaly, a positive (3 nT), is located over the most conspicuous, younger volcanic complex of the southeastern half of Sumatra. Because these data are from the southern magnetic hemisphere (I = -25-degrees), a positive Magsat anomaly implies an aggregate reverse remanent magnetization. Further northwest along Sumatra, where the volcanic rocks are less prevalent, there are no distinct anomalies. The Ninety East Ridge has a small anomaly (-2 nT) which has been modeled as indicating normal magnetization. While several other positive bathymetric features exhibit satellite altitude anomaly signatures, however, the Sunda Trench does not present a distinct magnetic anomaly. In addition, the existence of a diffuse plate boundary across the Wharton Basin was not supported by these data. At an altitude of 350 km the presence of a continental-oceanic magnetic "edge effect" was not detectable. A much lower orbiting magnetometer bearing satellite will be required to delineate these smaller tectonic elements. RP TAYLOR, PT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Taylor, Patrick/D-4707-2012 OI Taylor, Patrick/0000-0002-1212-9384 NR 19 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD JUN 10 PY 1991 VL 192 IS 1-2 BP 153 EP 158 DI 10.1016/0040-1951(91)90253-O PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FT769 UT WOS:A1991FT76900013 ER PT J AU WASILEWSKI, P HOOD, P AF WASILEWSKI, P HOOD, P TI MAGNETIC-ANOMALIES LAND AND SEA - PREFACE SO TECTONOPHYSICS LA English DT Editorial Material C1 GEOL SURVEY CANADA,OTTAWA K1A 073,ONTARIO,CANADA. RP WASILEWSKI, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD JUN 10 PY 1991 VL 192 IS 1-2 BP R7 EP R7 DI 10.1016/0040-1951(91)90241-J PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FT769 UT WOS:A1991FT76900001 ER PT J AU OSTRO, SJ CAMPBELL, DB CHANDLER, JF HINE, AA HUDSON, RS ROSEMA, KD SHAPIRO, II AF OSTRO, SJ CAMPBELL, DB CHANDLER, JF HINE, AA HUDSON, RS ROSEMA, KD SHAPIRO, II TI ASTEROID-1986DA - RADAR EVIDENCE FOR A METALLIC COMPOSITION SO SCIENCE LA English DT Article ID OBJECTS; SPECTRA; IMAGES; VENUS AB Echoes from the near-Earth object 1986 DA show it to be significantly more reflective than other radar-detected asteroids. This result supports the hypothesis that 1986 DA is a piece of NiFe metal derived from the interior of a much larger object that melted, differentiated, cooled, and subsequently was disrupted in a catastrophic collision. This 2-kilometer asteroid, which appears smooth at centimeter to meter scales but extremely irregular at 10- to 100-meter scales, might be (or have been a part of) the parent body of some iron meteorites. C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. NATL ASTRON & IONOSPHERE CTR,ARECIBO,PR 00613. WASHINGTON STATE UNIV,DEPT ELECT & COMP ENGN,PULLMAN,WA 99164. CORNELL UNIV,NATL ASTRON & IONOSPHERE CTR,ITHACA,NY 14853. RP OSTRO, SJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 52 TC 65 Z9 65 U1 1 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 JUN 7 PY 1991 VL 252 IS 5011 BP 1399 EP 1404 DI 10.1126/science.252.5011.1399 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FP868 UT WOS:A1991FP86800026 PM 17772910 ER PT J AU GOLDBERG, BE WILEY, DR AF GOLDBERG, BE WILEY, DR TI HYBRIDS - BEST OF BOTH WORLDS SO AEROSPACE AMERICA LA English DT Article RP GOLDBERG, BE (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SOLID PROPULS BRANCH,HUNTSVILLE,AL 35812, 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 JUN PY 1991 VL 29 IS 6 BP 28 EP 31 PG 4 WC Engineering, Aerospace SC Engineering GA FP709 UT WOS:A1991FP70900008 ER PT J AU MYNENI, RB AF MYNENI, RB TI MODELING RADIATIVE-TRANSFER AND PHOTOSYNTHESIS IN 3-DIMENSIONAL VEGETATION CANOPIES SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article ID REFLECTANCE; LEAVES AB A methodology for simulating the three-dimensional radiation regime in laterally heterogeneous vegetation canopies is presented. The method is based on the radiative transfer equation which is a formal statement of radiative energy balance in the configuration space. The transfer equation can be parameterized with models of the leaf area density function, the probability density of leaf normal orientation and the leaf scattering phase function. The transfer equation is numerically solved by the discrete ordinates method - by discretizing the angular variable into a finite number of directions and by introducing finite difference schemes for the spatial derivatives. The method was validated with photosynthetically active radiation (PAR) collected in a poplar stand. A formalism for coupling the predictions of the radiation model with the leaf photosynthetic response function is also presented. The utility of the coupled radiation/photosynthesis model is shown through an investigation of the optimal tree density problem for a given set of canopy architecture data. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 30 TC 75 Z9 75 U1 1 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1923 J9 AGR FOREST METEOROL JI Agric. For. Meteorol. PD JUN PY 1991 VL 55 IS 3-4 BP 323 EP 344 DI 10.1016/0168-1923(91)90069-3 PG 22 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA FW954 UT WOS:A1991FW95400009 ER PT J AU HALL, RM OBARA, CJ CARRAWAY, DL JOHNSON, CB WRIGHT, RE COVELL, PF AZZAZY, M AF HALL, RM OBARA, CJ CARRAWAY, DL JOHNSON, CB WRIGHT, RE COVELL, PF AZZAZY, M TI COMPARISONS OF BOUNDARY-LAYER-TRANSITION MEASUREMENT TECHNIQUES AT SUPERSONIC MACH NUMBERS SO AIAA JOURNAL LA English DT Article AB Four different boundary - layer transition detection techniques-very thin hot films, liquid crystals, infrared imaging, and an optical interferometer - were compared using the same flat-plate model for the same tunnel conditions. The comparisons, conducted at the NASA Langley Research Center, involved not only their sensitivity to transition but also their ease of use. The thin films, as expected, gave excellent quantitative information and were used as the standard for evaluating the other techniques. Both the liquid crystals and infrared imaging were able to detect transition before the boundary-layer intermittency factor had reached 50%. The optical interferometer was unsuccessful. Conditions sampled included a range of Mach numbers from 1.5 to 2.5 and unit Reynolds numbers from 3.3 to 13.1 x 10(6)/m. C1 PLANNING RES CORP,HAMPTON,VA 23666. SPECTRON DEV LABS INC,COSTA MESA,CA 92626. RP HALL, RM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 15 TC 9 Z9 10 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 JUN PY 1991 VL 29 IS 6 BP 865 EP 871 DI 10.2514/3.10669 PG 7 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000001 ER PT J AU YOON, S KWAK, D AF YOON, S KWAK, D TI 3-DIMENSIONAL INCOMPRESSIBLE NAVIER-STOKES SOLVER USING LOWER-UPPER SYMMETRICAL-GAUSS-SEIDEL ALGORITHM SO AIAA JOURNAL LA English DT Article ID EQUATIONS; EULER AB A NUMERICAL method based on the pseudocompressibility concept is developed for solving the three-dimensional incompressible Navier-Stokes equations using the lower-upper symmetric-Gauss-Seidel implicit scheme. Very high efficiency is achieved in a new flow solver, INS3D-LU code, by accomplishing the complete vectorizability of the algorithm on oblique planes of sweep in three dimensions. RP YOON, S (reprint author), NASA,AMES RES CTR,MCAT INST,MOFFETT FIELD,CA 94035, USA. NR 8 TC 31 Z9 32 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 JUN PY 1991 VL 29 IS 6 BP 874 EP 875 DI 10.2514/3.10671 PG 2 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000003 ER PT J AU MAESTRELLO, L ELHADY, NM AF MAESTRELLO, L ELHADY, NM TI RADIATION AND CONTROL OF SOUND FROM EVOLVING WAVE PACKET ON A CONCAVE-CONVEX SURFACE SO AIAA JOURNAL LA English DT Article ID BOUNDARY-LAYER AB Active control of the acoustic pressure in the far field resulting from the growth and decay of a wave packet convecting in a boundary layer over a concave-convex surface is investigated numerically using direct computations of the Navier-Stokes equations. The resulting sound radiation is computed using the linearized Euler equations with the pressure from the Navier-Stokes solution as a time-dependent boundary condition. The acoustic far field exhibits a directivity type of behavior that points upstream to the flow direction. A fixed control algorithm is used where the attenuation signal is synthesized by a filter that actively adapts itself to the amplitude-time response of the outgoing acoustic wave. C1 ANALYT SERV & MAT INC,DIV FLUID MECH,HAMPTON,VA 23665. RP MAESTRELLO, L (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,HAMPTON,VA 23665, USA. NR 18 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1991 VL 29 IS 6 BP 880 EP 887 DI 10.2514/3.10674 PG 8 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000006 ER PT J AU SURESH, A LIOU, MS AF SURESH, A LIOU, MS TI OSHER SCHEME FOR REAL GASES SO AIAA JOURNAL LA English DT Article ID DIFFERENCE-SCHEMES; EQUATIONS AB An extension of Osher's approximate Riemann solver to include gases with an arbitrary equation of state is presented. By a judicious choice of thermodynamic variables, the Riemann invariants are reduced to quadratures that are then approximated numerically. The extension is rigorous and does not involve any further assumptions or approximations over the ideal-gas case. Numerical results are presented to demonstrate the feasibility and accuracy of the proposed method. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP SURESH, A (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 15 TC 9 Z9 9 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 JUN PY 1991 VL 29 IS 6 BP 920 EP 926 DI 10.2514/3.10679 PG 7 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000011 ER PT J AU UTKU, S RAMESH, AV DAS, SK WADA, BK CHEN, GS AF UTKU, S RAMESH, AV DAS, SK WADA, BK CHEN, GS TI CONTROL OF A SLOW-MOVING SPACE CRANE AS AN ADAPTIVE STRUCTURE SO AIAA JOURNAL LA English DT Article ID SHAPE CONTROL; ERRORS AB If we assume that the space crane is a statically determinate truss with length-adjustable bars and take as controls the length adjustments of these bars, the computation of the incremental controls corresponding to the motion of a payload along a trajectory is given in terms of the inverse-transpose of matrix B of the joint equilibrium equations Bs = p, where s lists the bar forces and p the nodal loads. An algorithm with O(n2) computational complexity and O(n) storage demand is used for obtaining the inverse of the nth-order sparse matrix B. The compensation of the controls for elastic deformations and support movements is shown. The crane is assumed to be moving sufficiently slowly so that no vibratory motion is created during its maneuver. To simplify the computations, a zero-acceleration field is assumed in the workspace of the space crane. It is shown that the computations may be done automatically and in real time by an attached processor once the characteristics of the crane's maneuver are keyed in. C1 DUKE UNIV,DEPT COMP SCI,DURHAM,NC 27706. CALTECH,JET PROP LAB,APPL TECHNOL SECT,PASADENA,CA 91109. CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109. RP UTKU, S (reprint author), DUKE UNIV,DEPT CIVIL ENGN,DURHAM,NC 27706, USA. NR 12 TC 10 Z9 10 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1991 VL 29 IS 6 BP 961 EP 967 DI 10.2514/3.10686 PG 7 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000018 ER PT J AU GRADY, JE LERCH, BA AF GRADY, JE LERCH, BA TI EVALUATION OF THERMOMECHANICAL DAMAGE IN SILICON-CARBIDE TITANIUM COMPOSITES SO AIAA JOURNAL LA English DT Article AB Composite specimens of Ti-15V-3A1-3Cr-3Sn matrix reinforced with continuous SCS-6 silicon carbide fibers were tested under a variety of thermal and mechanical loadings. A combined experimental/finite element approach was used to estimate the effective in situ modulus of the matrix material and to evaluate changes in modulus due to the applied loads. Several fiber orientations were tested. The results indicate that the effect of thermal loads on composite stiffness varies with fiber orientation. Applications of this method to test specimens damaged by uniaxial tension, thermal cycling, and isothermal fatigue loadings are used to illustrate that, by monitoring overall structural behavior, changes in stiffness caused by thermomechanical loading can be detected. RP GRADY, JE (reprint author), NASA,LEWIS RES CTR,M-S 49-8,2100 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1991 VL 29 IS 6 BP 992 EP 997 DI 10.2514/3.10690 PG 6 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000022 ER PT J AU KIM, KS LEE, Y SETTLES, GS AF KIM, KS LEE, Y SETTLES, GS TI LASER INTERFEROMETER PRESTON TUBE SKIN-FRICTION COMPARISON IN SHOCK BOUNDARY-LAYER INTERACTION SO AIAA JOURNAL LA English DT Note C1 PENN STATE UNIV,DEPT MECH ENGN,UNIVERSITY PK,PA 16802. PENN STATE UNIV,GAS DYNAM LAB,UNIVERSITY PK,PA 16802. RP KIM, KS (reprint author), NASA,AMES RES CTR,EXPTL FLUID DYNAM BRANCH,MAIL STOP 229-1,MOFFETT FIELD,CA 94035, USA. NR 16 TC 7 Z9 7 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 JUN PY 1991 VL 29 IS 6 BP 1007 EP 1009 DI 10.2514/3.10695 PG 3 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000027 ER PT J AU HUNG, CM AF HUNG, CM TI CRITIQUE OF TURBULENCE MODELS FOR SHOCK-INDUCED FLOW SEPARATION - COMMENT SO AIAA JOURNAL LA English DT Letter ID BOUNDARY-LAYER INTERACTION; WAVE RP HUNG, CM (reprint author), NASA,AMES RES CTR,COMPUTAT FLUID DYNAM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1991 VL 29 IS 6 BP 1021 EP 1023 DI 10.2514/3.10700 PG 3 WC Engineering, Aerospace SC Engineering GA FU410 UT WOS:A1991FU41000032 ER PT J AU ODONNELL, CP SCHEUER, DA KEIL, LC THRASHER, TN AF ODONNELL, CP SCHEUER, DA KEIL, LC THRASHER, TN TI CARDIAC NERVE BLOCKADE BY INFUSION OF PROCAINE INTO THE PERICARDIAL SPACE OF CONSCIOUS DOGS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE RENIN; PLASMA RENIN ACTIVITY; CORTISOL; ADRENOCORTICOTROPIC HORMONE; NOREPINEPHRINE; THIRST; DRINKING; BLOOD PRESSURE; BARORECEPTORS ID CARDIOPULMONARY REGION; ARGININE VASOPRESSIN; VAGAL AFFERENTS; RENIN RELEASE; INHIBITION; RECEPTORS AB A technique was developed to produce acute, reversible cardiac nerve blockade (CNB) in the conscious dog by infusion of 2% procaine into the pericardial (PC) space. During CNB, reflex changes in heart rate (HR) in response to intravenous bolus injections of phenylephrine (100-mu-g) and nitroglycerin (300-mu-g) and the reflex tachycardia and hypotension after a 50-mu-g bolus injection of veratridine into the left atrium were abolished. In response to CNB, HR increased from 79 +/- 10 to 142 +/- 10 beats/min and mean arterial pressure (MAP) increased from 101 +/- 5 to 117 +/- 6 mmHg. Baseline values for plasma arginine vasopressin (AVP), plasma renin activity (PRA), and plasma norepinephrine (NE) were unchanged by CNB, but there was a small increase in plasma cortisol levels (1.4 +/- 0.3 to 2.3 +/- 0.3-mu-g/dl) during CNB. There was no significant change in the baseline levels of any of these hormones during PC infusion of 0.9% saline. To control for the possibility that procaine leaked into the systemic circulation, identical amounts of procaine were infused intravenously. Systemic administration of procaine caused a rise in MAP but had no effect on HR and did not alter plasma levels of AVP, PRA, NE, or cortisol. The relationship between plasma osmolality and plasma AVP, as well as the drinking response to a 60-min infusion of hypertonic NaCl, was unaltered by CNB. We conclude that PC procaine infusion is an effective technique for producing acute, reversible blockade of the cardiac nerves in the conscious dog. C1 UNIV CALIF SAN FRANCISCO,SCH MED,DEPT PHYSIOL,BOX 0444,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 21 TC 16 Z9 16 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 JUN PY 1991 VL 260 IS 6 BP R1176 EP R1182 PN 2 PG 7 WC Physiology SC Physiology GA FU845 UT WOS:A1991FU84500058 ER PT J AU GROGAN, DW AF GROGAN, DW TI EVIDENCE THAT BETA-GALACTOSIDASE OF SULFOLOBUS-SOLFATARICUS IS ONLY ONE OF SEVERAL ACTIVITIES OF A THERMOSTABLE BETA-D-GLYCOSIDASE SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID ARCHAEBACTERIAL GENUS SULFOLOBUS; GLUCOSIDASE; PURIFICATION; SPECIFICITY; THERMOPHILE; INDUCTION; STABILITY; BACTERIA; PROTEINS AB A survey of Sulfolobus isolates showed all to contain thermostable enzyme activities hydrolyzing various glycosidic compounds. Of those not previously reported, the beta-glucosidase activity of Sulfolobus solfataricus isolate P2 was chosen for further study and found to have the same kinetics of inactivation, apparent molecular weight, and many (though not all) other biochemical properties of the beta-galactosidase also present in this strain. The two activities copurified approximately 850-fold to apparent homogeneity. The enzyme, whose subunit M(r) was estimated to be 60,000 by gel permeation chromatography of the active enzyme and 70,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the denatured form, hydrolyzed a variety of low-molecular-weight, beta-linked glycosides and could account for most of the corresponding activities found in crude extract. Kinetic analyses indicated that chromogenic beta-D-galactosides and beta-D-glucosides are hydrolyzed at a common active site and that beta-glucosides and beta-fucosides represent the preferred substrates. The liberation of aglycone form aryl beta-D-glucosides was stimulated by alcohols in a manner suggesting specific interaction between alcohol and enzyme. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 24 TC 62 Z9 62 U1 1 U2 1 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1325 MASSACHUSETTS AVENUE, NW, WASHINGTON, DC 20005-4171 SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD JUN PY 1991 VL 57 IS 6 BP 1644 EP 1649 PG 6 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA FP564 UT WOS:A1991FP56400011 ER PT J AU THOMAS, RJ KESKIKUHA, RAM NEUPERT, WM CONDOR, CE GUM, JS AF THOMAS, RJ KESKIKUHA, RAM NEUPERT, WM CONDOR, CE GUM, JS TI EXTREME ULTRAVIOLET PERFORMANCE OF A MULTILAYER COATED HIGH-DENSITY TOROIDAL GRATING SO APPLIED OPTICS LA English DT Article ID LAYERED SYNTHETIC MICROSTRUCTURES; SOFT-X-RAY; REFLECTANCE; REGION; OPTICS; EUV AB The performance of a multilayer coated diffraction grating has been evaluated at EUV wavelengths both in terms of absolute efficiency and spectral resolution. The application of a ten-layer Ir/Si multilayer coating to a 3600-lines/mm blazed toroidal replica grating produced a factor of 9 enhancement in peak efficiency near the design wavelength approximately 30 nm in first order, without degrading its excellent quasistigmatic spectral resolution. The measured EUV efficiency peaked at 3.3% and was improved over the full spectral range between 25 and 35 nm compared with the premultilayer replica which had a standard gold coating. In addition, the grating's spectral resolution of > 5000 was maintained. RP THOMAS, RJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 25 TC 21 Z9 21 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 JUN 1 PY 1991 VL 30 IS 16 BP 2245 EP 2251 PG 7 WC Optics SC Optics GA FP566 UT WOS:A1991FP56600025 PM 20700200 ER PT J AU HUTCHINGS, JB NEFF, SG AF HUTCHINGS, JB NEFF, SG TI OPTICAL IMAGING OF THE LOW REDSHIFT SUPERLUMINOUS QSO 1821+643 SO ASTRONOMICAL JOURNAL LA English DT Article AB We present optical imaging of the luminous, z = 0.3 QSO 1821 + 643, with resolution 1.0 and 0.4 arcsec. The host galaxy is resolved and seen to be large, featureless, and red, with slightly displaced outer isophotes. The nucleus is unusually red. There is a rich cluster of galaxies in the field which is probably at a much higher redshift, and extended nebulosity from a nearby star. We discuss these results and the IR properties in terms of a mature merger of a luminous galaxy in which there is still a considerable amount of central dust and molecular clouds. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HUTCHINGS, JB (reprint author), NATL RES COUNCIL CANADA,DOMINION ASTROPHYS OBSERV,5071 W SAANICH RD,VICTORIA V8X 4M6,BC,CANADA. NR 8 TC 31 Z9 31 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1991 VL 101 IS 6 BP 2001 EP 2003 DI 10.1086/115824 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FN636 UT WOS:A1991FN63600005 ER PT J AU ARENDT, RG AF ARENDT, RG TI IRAS 15099-5856 AND THE COMPOSITE SUPERNOVA REMNANT G320.4-1.2 SO ASTRONOMICAL JOURNAL LA English DT Article ID X-RAY PULSAR; INFRARED-EMISSION; NOVA REMNANT; CRAB-NEBULA; VELA PULSAR; MSH-15-52; REGIONS AB The supernova remnant (SNR) G320.4 - 1.2 is a composite SNR, containing both a shock-dominated shell, and a pulsar-dominated plerion. G320.4 - 1.2 is one of the few SNRs in which a pulsar has been detected. This paper reports on Infrared Astronomical Satellite (IRAS) observations of this SNR. A pointlike source (IRAS 15099 - 5856) near the position of the pulsar appears quite prominently at 25-mu-m. The region appears more complex at 60 and 100-mu-m. Three models that may account for the IR emission of IRAS 15099 - 5856 are examined; none of these is entirely satisfactory. Some IR emission is detected from the brightest portion of the shell of this SNR, but this emission is nearly hidden by other confusing sources. RP ARENDT, RG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. NR 39 TC 9 Z9 9 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1991 VL 101 IS 6 BP 2160 EP 2167 DI 10.1086/115838 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FN636 UT WOS:A1991FN63600019 ER PT J AU MOZURKEWICH, D JOHNSTON, KJ SIMON, RS BOWERS, PF GAUME, R HUTTER, DJ COLAVITA, MM SHAO, M PAN, XP AF MOZURKEWICH, D JOHNSTON, KJ SIMON, RS BOWERS, PF GAUME, R HUTTER, DJ COLAVITA, MM SHAO, M PAN, XP TI ANGULAR DIAMETER MEASUREMENTS OF STARS SO ASTRONOMICAL JOURNAL LA English DT Article ID ALPHA-ORIONIS; SPECKLE INTERFEROMETRY; GIANT AB Angular diameters determined with the Mark III Optical Interferometer are presented for 12 stars at wavelengths of 450 and 800 nm. The uniform disk diameters resulting from fits to the visibility observations have rms residuals of order 1% for the 800 nm measurements and less than 3% for the 450 nm measurements. The improvement over previous observations with this instrument is due to improved data analysis and the use of a wider range of baseline lengths. An analysis of the calibration systematics for the Mark III Optical Interferometer is included. There is good agreement between these measurements and previously published data. The changes in uniform disk diameter between wavelengths of 450 and 800 nm agree with models of stellar atmospheres. C1 USN OBSERV, DEPT ASTROMETRY, WASHINGTON, DC 20392 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, DEPT ASTRON, PASADENA, CA 91125 USA. RP USN, RES LAB, CTR ADV SPACE SENSING, CODE 4215, WASHINGTON, DC 20375 USA. NR 23 TC 155 Z9 155 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD JUN PY 1991 VL 101 IS 6 BP 2207 EP 2219 DI 10.1086/115843 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FN636 UT WOS:A1991FN63600024 ER PT J AU RUSSELL, JL JOHNSTON, KJ MA, C SHAFFER, D DEVEGT, C AF RUSSELL, JL JOHNSTON, KJ MA, C SHAFFER, D DEVEGT, C TI A RADIO OPTICAL REFERENCE FRAME .2. ADDITIONAL RADIO AND OPTICAL SOURCE POSITIONS IN THE NORTHERN-HEMISPHERE SO ASTRONOMICAL JOURNAL LA English DT Article ID ASTROMETRY; VLBI; EMISSION; CATALOG; SYSTEMS; STARS AB VLBI observations from 12 sessions have been made of a total of 103 sources north of - 2-degrees declination. These data give the first extension to the radio/optical reference frame catalog already defined by the data in the NASA Crustal Dynamics Project database prior to July 1988 [Ma et al., AJ, 90, 1284 (1990)]. The new observations add 53 new sources to the radio reference frame catalog, improve the positions of 29 from the previous version, and show another seven sources to be unsuitable reference frame objects. Observations of 14 calibration sources tie the new positions to the existing catalog. The formal mean errors for the radio positions of the additional sources are about 0.8 mas in each coordinate. Optical positions for eight sources have been measured in the FK5 system, bringing the total number of sources in the catalog with accurate positions for their optical counterparts to 36. The new optical positions have an accuracy of about 50 mas. C1 APPL RES CORP,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,CODE 9219,GREENBELT,MD 20771. INTERFEROMET INC,VIENNA,VA 22182. UNIV HAMBURG,HAMBURGER STERNWARTE,W-2000 HAMBURG 13,GERMANY. RP RUSSELL, JL (reprint author), USN,RES LAB,CODE 4200,WASHINGTON,DC 20375, USA. RI Ma, Chopo/D-4751-2012 NR 22 TC 21 Z9 21 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1991 VL 101 IS 6 BP 2266 EP 2273 DI 10.1086/115848 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FN636 UT WOS:A1991FN63600029 ER PT J AU ENCRENAZ, T LELLOUCH, E PAUBERT, G GULKIS, S AF ENCRENAZ, T LELLOUCH, E PAUBERT, G GULKIS, S TI 1ST DETECTION OF HDO IN THE ATMOSPHERE OF VENUS AT RADIO WAVELENGTHS - AN ESTIMATE OF THE H2O VERTICAL-DISTRIBUTION SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE PLANETS, ABUNDANCES, ATMOSPHERES; RADIO LINE, MOLECULAR ID WATER VAPOR; DEUTERIUM; HYDROGEN AB The 225.9 GHz line of HDO has been detected in absorption in the atmosphere of Venus, with the 30m IRAM antenna. This measurement gives information upon the vertical distributions of HDO, and thus H2O, in this planet. Our observations are consistent with an H2O vertical distribution strongly depleted by saturation at an altitude of 95 km, and, assuming a D/H enrichment of 120 with respect to the terrestrial value, with a mixing ratio of 3.5 (+/- 2.0) ppm in the range 65-95 km. C1 IRAM, GRANADA, SPAIN. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP ENCRENAZ, T (reprint author), OBSERV PARIS, CNRS, UA 264, DESPA, F-92195 MEUDON, FRANCE. NR 21 TC 24 Z9 24 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 JUN PY 1991 VL 246 IS 1 BP L63 EP L66 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FT464 UT WOS:A1991FT46400018 ER PT J AU ADELMAN, SJ CACCIARI, C LECKRONE, DS AF ADELMAN, SJ CACCIARI, C LECKRONE, DS TI A LINE IDENTIFICATION STUDY OF THE IUE SWP HIGH DISPERSION SPECTRUM OF THE UV-BRIGHT STAR BARNARD-29 OF MESSIER-13 SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE CLUSTERS; GLOBULAR; INTERSTELLAR MEDIUM; CLOUDS; GENERAL; SPECTROSCOPY; STARS; POPULATION-II; UV RADIATION ID GLOBULAR-CLUSTERS; STELLAR EVOLUTION; ABUNDANCES; VELOCITY; M13 AB We performed a line identification study of the coaddition of three SWP high dispersion IUE exposures of the UV-bright star Barnard 29 of Messier 13. One of these images took two IUE shifts. We extended the previous study by de Boer and Savage and found stellar lines of C I, C II, C III, C IV, N I, N III, O I, O III, O IV, Al III, Si II, Si III, Si IV, P III, S II, and S III and interstellar lines of C I, C II, C IV, N I, N III, N IV, N V, O I, Al II, Al III, Si II, Si IV, S II, and Fe II. These lines are the strongest expected lines in a hot Population II star. Apparent intensity minima corresponding to interstellar features are noted, especially those matching a high velocity cloud found by de Boer and Savage. C1 OSSERVATORIO ASTRON BOLOGNA,I-40126 BOLOGNA,ITALY. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP ADELMAN, SJ (reprint author), CITADEL,DEPT PHYS,CHARLESTON,SC 29409, USA. NR 32 TC 2 Z9 2 U1 0 U2 0 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD JUN PY 1991 VL 88 IS 3 BP 393 EP 398 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP767 UT WOS:A1991FP76700001 ER PT J AU BROWN, A DRAKE, SA VANSTEENBERG, ME LINSKY, JL AF BROWN, A DRAKE, SA VANSTEENBERG, ME LINSKY, JL TI X-RAY-EMISSION FROM HYBRID-CHROMOSPHERE STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS; CHROMOSPHERES; STARS; LATE-TYPE; STARS; X-RAYS ID ABSORPTION-LINES; INTERSTELLAR; ULTRAVIOLET; ATMOSPHERES; ABUNDANCE; MODELS; GIANT; ZINC AB The current evidence for the existence of hot (greater-than-or-equal-to 10(6) K) plasma around hybrid-chromosphere stars is examined. EXOSAT observations of the hybrid star alpha TrA provide the first X-ray detection of such a star. An X-ray differential emission measure locus is derived and used to demonstrate that the temperature of the X-ray-emitting plasma is unlikely to be lower than 10(6) K. Estimates are made of the interstellar hydrogen column densities toward hybrid stars using a variety of methods in order to allow interpretation of X-ray observations. The X-ray luminosity of alpha TrA is calculated to be approximately 5 x 10(29) ergs s-1 over the 1-300 angstrom spectral region and 7 x 10(28) ergs s-1 in the Einstein 0.2-4 keV (3-60 angstrom) energy range for N(H) = 5 x 10(19) cm-2 and a temperature of 10(6) K. X-ray nondetections of other hybrid stars from EXOSAT and Einstein satellite observations are consistent with their interstellar hydrogen column densities, if the ratio of their intrinsic X-ray to transition region emission line surface fluxes are the same as for alpha TrA. It now seems that the conceptual model of Linsky, in which the higher temperature plasma is magnetically confined and separated from the outflowing stellar wind, is most likely to correctly represent the physical structuring of hybrid star outer atmospheres. C1 NATL INST STAND & TECHNOLOGY,BOULDER,CO 80309. ST SYST CORP,LANHAM,MD 20706. NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,GREENBELT,MD 20771. UNIV COLORADO,DIV QUANTUM PHYS,BOULDER,CO 80309. RP BROWN, A (reprint author), UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309, USA. NR 41 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 JUN 1 PY 1991 VL 373 IS 2 BP 614 EP 619 DI 10.1086/170080 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM779 UT WOS:A1991FM77900027 ER PT J AU FEIBELMAN, WA BRUHWEILER, FC JOHANSSON, S AF FEIBELMAN, WA BRUHWEILER, FC JOHANSSON, S TI ULTRAVIOLET HIGH-EXCITATION FE-II FLUORESCENCE LINES EXCITED BY O-VI, C-IV, AND H-I RESONANCE EMISSION AS SEEN IN IUE SPECTRA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; NEBULAE; PLANETARY; STARS; EMISSION-LINE; ULTRAVIOLET; SPECTRA ID STAR AB The major goal of this study was to use archival high-dispersion spectra from the International Ultraviolet Explorer (IUE) in a search for Bowen emission lines of Fe II excited by the stronger transition (lambda-1032) of the O VI resonance doublet. We also explore the possibility of using these Fe II emission lines as a diagnostic of the strength of the far-UV emission of O VI at 1032 angstrom, which lies beyond the wavelength ranges of the Hubble Space Telescope (HST) and the highly successful IUE. We searched a large sample of IUE archival SWP high-dispersion spectra of central stars of planetary nebulae, symbiotic stars, pulsating degenerate (PG 1159-type) stars, novae, supernovae, and active galactic nuclei (AGNs) that may display the high-excitation fluorescence emission lines of Fe II, recently discovered by Johansson to be excited by Bowen mechanisms driven by resonance line radiation from O VI, C IV, and H I. We have searched for these Fe II lines at lambda-lambda-1360, 1776, 1869, 1881, 1884, and 1975 in about 40 objects of the types mentioned. These lines are quite strong in symbiotic stars, particularly the "symbiotic novae" which suggests that high-excitation, high-temperature, and high electron density are essential requirements, but these Fe II lines were not detected in the extragalactic AGNs, namely NGC 1068, NGC 4151, Fairall 9, 3C 273, AKN 120, and MKN 509. C1 COMP SCI CORP,ASTRON PROGRAM,SILVER SPRING,MD 20910. CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. UNIV LUND,DEPT PHYS,S-22362 LUND,SWEDEN. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 23 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1991 VL 373 IS 2 BP 649 EP 656 DI 10.1086/170084 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM779 UT WOS:A1991FM77900031 ER PT J AU KRISHER, TP ANDERSON, JD TAYLOR, AH AF KRISHER, TP ANDERSON, JD TAYLOR, AH TI VOYAGER-2 TEST OF THE RADAR TIME-DELAY EFFECT SO ASTROPHYSICAL JOURNAL LA English DT Article DE GRAVITATION; RADAR ASTRONOMY; RELATIVITY ID VIKING AB By analyzing radio range measurements generated during the solar conjunction of the Voyager 2 spacecraft in 1985, we have been able to test accurately the relativistic time-delay effect with a spacecraft at a distance of 3 x 10(9) km from the Earth. Because the range measurements were generated simultaneously at two frequencies on the downlink, it was possible to derive calibrations for the delay resulting from intervening solar plasma. In addition, a record of attitude thruster firings was used to model small accelerations of the spacecraft that could have produced a range error. It was thereby possible to determine the parameterized post-Newtonian (PPN) parameter-gamma to an accuracy of 3% with only a sparse amount of range data. We discuss how this result, and the results of other time-delay tests, could be of interest for constraining a possible spatial anisotropy in the relativistic time-delay which can occur in some theories of gravity. RP KRISHER, TP (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 7 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 JUN 1 PY 1991 VL 373 IS 2 BP 665 EP 670 DI 10.1086/170086 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM779 UT WOS:A1991FM77900033 ER PT J AU CANE, HV REAMES, DV VONROSENVINGE, TT AF CANE, HV REAMES, DV VONROSENVINGE, TT TI SOLAR PARTICLE ABUNDANCES AT ENERGIES OF GREATER THAN 1-MEV PER NUCLEON AND THE ROLE OF INTERPLANETARY SHOCKS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERPLANETARY MEDIUM; SHOCK WAVES; SUN; PARTICLE EMISSION ID ENERGETIC PARTICLES; EVENTS; FLARES AB We have examined the abundances of elements in large solar energetic particle events in the energy range 2-12 MeV per nucleon. There are large variations in abundances from event to event but the data show an organization. As found by previous workers, we find that the abundances relative to mean values vary approximately monotonically as a function of mass (A), except for He-4. Some events show a gradual depletion of heavy ions, whereas a smaller number show a gradual increase. In this paper we show for the first time a further organization of abundance data which depends on the longitude of the source region. The abundances as a function of longitude can be understood in terms of two particle sources, namely (1) particles originating out of flare-heated material and (2) particles accelerated at coronal and interplanetary shocks. The greatest depletions of heavy elements occur when source regions are near central meridian which is also where the strongest shocks originate. The depletions are matched by a steepening of the spectrum and can be understood in terms of diffusive shock acceleration. The greatest enhancements of heavy elements occur when source regions are near west 60-degrees. In this situation the observer can be magnetically connected to flaring regions and have access to flare-heated material which is enriched in heavy elements. C1 UNIV SPACE RES ASSOCIATES,GREENBELT,MD 20771. UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA. RP CANE, HV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 22 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 JUN 1 PY 1991 VL 373 IS 2 BP 675 EP 682 DI 10.1086/170088 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM779 UT WOS:A1991FM77900035 ER PT J AU KAZANAS, D MANNHEIM, PD AF KAZANAS, D MANNHEIM, PD TI GENERAL STRUCTURE OF THE GRAVITATIONAL EQUATIONS OF MOTION IN CONFORMAL WEYL GRAVITY SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE COSMOLOGY; GRAVITATION AB We present a general method for determining the structure of the gravitational equations of motion in the currently experimentally viable fourth-order theory of gravity based on local conformal Weyl invariance of the gravitational action and give the explicit structure for these equations in the case where the geometry is described by a time-dependent, spherically symmetric line element. C1 UNIV CONNECTICUT,DEPT PHYS,STORRS,CT 06269. RP KAZANAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 7 TC 31 Z9 31 U1 0 U2 2 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 JUN PY 1991 VL 76 IS 2 BP 431 EP 453 DI 10.1086/191573 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM468 UT WOS:A1991FM46800001 ER PT J AU GURZADYAN, GA PEREZ, M AF GURZADYAN, GA PEREZ, M TI DOUBLET 2800 MGII IN CLOSE BINARY-SYSTEMS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID FLARE AB It is shown that the emission ultraviolet doublet 2800 Mg II in radio stars, actually in close binary systems, do not have chromospheric origin, but is generated in the space between the components of the system, filled by clouds or streams of two types - emission (A) and absorption (B). It is shown also that the strongly deformed or distorted forms of short wavelength halfs of emission profiles k and h Mg II (Figures 1 and 4) are a result of the absorption in the intercomponent space, by clouds B. Both qualitative and quantitative criteriums are obtained for these clouds A and B, at which the observed forms of emission profils k and h Mg II may be explained. Particularly, the hydrogen atoms in absorption clouds B must be ionized not strongly or be with concentrations on three orders less than in emission clouds of type A. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE OBSERV,GREENBELT,MD 20771. RP GURZADYAN, GA (reprint author), ACAD SCI ARSSR,BYURAKAN ASTROPHYS OBSERV,BYURAKAN,ARMENIA,USSR. NR 5 TC 3 Z9 3 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD JUN PY 1991 VL 180 IS 1 BP 1 EP 17 DI 10.1007/BF00644225 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA GA687 UT WOS:A1991GA68700001 ER PT J AU DUDLEY, GA TESCH, PA MILLER, BJ BUCHANAN, P AF DUDLEY, GA TESCH, PA MILLER, BJ BUCHANAN, P TI IMPORTANCE OF ECCENTRIC ACTIONS IN PERFORMANCE ADAPTATIONS TO RESISTANCE TRAINING SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID HUMAN MOTOR UNITS; SKELETAL-MUSCLE; BED REST; MUSCULAR STRENGTH; EXERCISE; BEHAVIOR; FORCE AB The inability of the exercises presently used during space-flight to maintain muscle strength and mass may reflect the absence of eccentric (ecc) muscle actions. This study examined the importance of ecc actions in performance adaptations to resistance training. Middle-aged males performed 4-5 sets of 6-12 repetitions (rep) per set of the leg press and leg extension exercises 2 d each week for 19 weeks. Group CON/ECC (n = 9) performed each rep with concentric (con) and ecc actions, group CON (n = 8) with only con actions. Group CON/CON (n = 10) performed twice as many sets with only con actions. The resistance per set was selected to induce failure within the prescribed number of rep. Eight subjects did not train and served as controls. The increase in the three rep maximum (3RM) after training, in general, showed a hierarchy such that CON/ECC > CON/CON > CON. The differences (p < 0.05) were: leg press 3RM with con and ecc actions, CON/ECC > CON/CON > CON (26 > 15 > 8%); leg press 3RM with only con actions, CON/ECC or CON/CON > CON (22 or 18 > 14%); and leg extension 3RM with con and ecc actions, CON/ECC > CON (29 > 16%). These differences (p < 0.05) were still evident after 1 month of de-training. The results indicate that omission of ecc actions from resistance training compromises increases in strength, probably because intensity is not optimal. They suggest that exercise equipment and prescriptions for use during space-flight to maintain muscle strength and mass should be developed with incorporation of ecc actions. C1 BIONET CORP,ENVIRONM LAB,KENNEDY SPACE CTR,FL 32899. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL. KAROLINSKA INST,DEPT PHYSIOL,ENVIRONM PHYSIOL LAB,S-10401 STOCKHOLM 60,SWEDEN. RP DUDLEY, GA (reprint author), BIONET CORP,BIOMED LAB,MAIL CODE BIO-6,KENNEDY SPACE CTR,FL 32899, USA. NR 32 TC 183 Z9 186 U1 0 U2 9 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 JUN PY 1991 VL 62 IS 6 BP 543 EP 550 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA FP096 UT WOS:A1991FP09600007 PM 1859341 ER PT J AU ARKING, A AF ARKING, A TI THE RADIATIVE EFFECTS OF CLOUDS AND THEIR IMPACT ON CLIMATE SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID OPTICAL-THICKNESS FEEDBACKS; GENERAL-CIRCULATION MODEL; EARTH; CO2; SENSITIVITY; ALBEDO; BUDGET; PHYTOPLANKTON; ATMOSPHERE; POLLUTION AB Our knowledge of the direct role of clouds in long-term climate change is examined in an overview of key results published over the last 15 or 20 years, along with some relevant unpublished model studies. The focus is on 1) the impact of clouds on the incoming and outgoing radiation at the top of the atmosphere, and 2) the two-way interaction of clouds with other variables of the climate system-i.e., the cloud/climate feedback problem-as revealed by climate model simulations. A common framework is established for comparing results from different investigations. The total effect of clouds on radiative fluxes at the top of the atmosphere-specifically, the difference in flux between average conditions and cloud-free conditions, often called cloud forcing-has been derived from earth radiation budget measurements by several investigators using various data sources and methods. There is general agreement that the annual global mean effect of clouds is to cool the climate system, but there is significant disagreement on magnitude, with the two investigations based on recent satellite data indicating a range from 17 to 27 W/m2. Cloud sensitivity, which represents the differential response of top-of-the-atmosphere fluxes to changes in cloud cover parameters, is a critical factor in cloud feedback. The observational data at this point in time, however, are not sufficient to yield more than rough estimates. Two estimates, of the sensitivity to cloud amount, show wide discrepancies. To be useful, future studies of sensitivity will have to separate different cloud types. Sensitivity of clouds to cloud condensation nuclei raises the issue of a more direct role of clouds in climate change, where aerosols associated with SO2 emissions can ultimately lead to brighter clouds and a reduction in solar heating. On cloud feedback in climate simulations, there are wide discrepancies amongst models. Investigators find, in general, that the sign of cloud feedback is positive when one allows the spatial distribution of clouds to vary in response to climate change. When one additionally takes into account the effect of changes in cloud properties, that result is less certain. The conclusion is: 1) clouds may have a strong influence on climate change, but 2) we are far from knowing the magnitude, and even the sign, of this influence. RP ARKING, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 51 TC 141 Z9 146 U1 1 U2 10 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 JUN PY 1991 VL 72 IS 6 BP 795 EP 813 DI 10.1175/1520-0477(1991)072<0795:TREOCA>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FT231 UT WOS:A1991FT23100003 ER PT J AU FAEGRI, K BAUSCHLICHER, CW AF FAEGRI, K BAUSCHLICHER, CW TI HETERONUCLEAR TRANSITION-METAL DIATOMICS - THE BONDING AND ELECTRONIC-STRUCTURE OF SCNI, YNI, SCPD, AND YPD SO CHEMICAL PHYSICS LA English DT Article ID MOLECULAR CALCULATIONS; WAVE-FUNCTIONS; BASIS SET; ATOMS; ORBITALS; STATES; POTENTIALS AB High quality ab initio calculations show that ScNi, YNi, ScPd, and YPd all have 2-SIGMA+ ground states in agreement with electron spin resonance experiments. For ScNi and YNi, this is expected based on the lowest atomic asymptote. For ScPd and YPd, the lowest atomic asymptote would give the order of stability 2-DELTA > 2-PI almost-equal-to 2-SIGMA+, but the calculations show that mixing in of the excited asymptotes preferentially lowers the 2-SIGMA+ state. The calculations show that the quartet states are about 20-30 kcal/mol above the ground state, and therefore probably do not contribute significantly to the unexpected g perpendicular-to values found in experiment. Calculations of excited states for YPd reveal some strong transitions that should be amenable to spectroscopic studies. C1 UNIV OSLO,DEPT CHEM,N-0315 OSLO 3,NORWAY. RP FAEGRI, K (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 13 Z9 13 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD JUN 1 PY 1991 VL 153 IS 3 BP 399 EP 408 DI 10.1016/0301-0104(91)80053-K PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FR914 UT WOS:A1991FR91400007 ER PT J AU LI, CP AF LI, CP TI COMPUTATIONAL METHODS FOR SHOCK-WAVES IN 3-DIMENSIONAL SUPERSONIC-FLOW SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article; Proceedings Paper CT SYMP ON RECENT DEVELOPMENTS IN LARGE-SCALE COMPUTATIONAL FLUID DYNAMICS CY APR 23-24, 1990 CL MINNESOTA SUPERCOMP INST, MN SP MINNESOTA SUPERCOMP INST HO MINNESOTA SUPERCOMP INST ID DIFFERENCE AB A central artificial-viscosity and an upwind-biased difference method have been contrived to solve the Euler equations for the flowfield over typical spacecrafts. The spatial discretization is based on either nodal or cell vertex formulation in the domain extending from free stream to the end of the vehicle. The outer boundary is treated as a bow shock in the first method but is placed in the free stream in the second, which captures both bow and internal shocks using an approximate Riemann solver based on high-order extrapolation to the cell face. These methods were tested for the Shuttle and Hermes orbiters at wind-tunnel conditions and angles of attack ranging from 0 to 60-degrees. The artificial-viscosity method incorporated with a shock fitting procedure has shown smeared crossflow and wing shock positions and required 15% more CPU per node than the upwind method. Greater flexibility and robustness is demonstrated by the latter on a fixed grid for all cases considered. RP LI, CP (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 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 JUN PY 1991 VL 87 IS 2-3 BP 305 EP 327 DI 10.1016/0045-7825(91)90010-4 PG 23 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA FU643 UT WOS:A1991FU64300010 ER PT J AU MOIN, P AF MOIN, P TI TOWARDS LARGE EDDY AND DIRECT SIMULATION OF COMPLEX TURBULENT FLOWS SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article; Proceedings Paper CT SYMP ON RECENT DEVELOPMENTS IN LARGE-SCALE COMPUTATIONAL FLUID DYNAMICS CY APR 23-24, 1990 CL MINNESOTA SUPERCOMP INST, MN SP MINNESOTA SUPERCOMP INST HO MINNESOTA SUPERCOMP INST ID CHANNEL FLOW AB Recent advances in the methodology for direct numerical simulation of turbulent flows and some of the current applications are reviewed. It is argued that high-order finite difference schemes yield solutions with comparable accuracy to the spectral methods with the same number of degrees of freedom. The effects of random inflow conditions on the downstream evolution of turbulence are discussed. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MOIN, P (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 18 TC 2 Z9 2 U1 0 U2 0 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 JUN PY 1991 VL 87 IS 2-3 BP 329 EP 334 DI 10.1016/0045-7825(91)90011-T PG 6 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA FU643 UT WOS:A1991FU64300011 ER PT J AU BERRYMAN, H SALTZ, J SCROGGS, J AF BERRYMAN, H SALTZ, J SCROGGS, J TI EXECUTION TIME SUPPORT FOR ADAPTIVE SCIENTIFIC ALGORITHMS ON DISTRIBUTED MEMORY MACHINES SO CONCURRENCY-PRACTICE AND EXPERIENCE LA English DT Article AB We consider optimizations that are required for efficient execution of code segments that consist of loops over distributed data structures. The PARTI execution time primitives are designed to perform these optimizations and can be used to implement a wide range of scientific algorithms on distributed memory machines. These primitives allow the user to control array mappings in a way that gives an appearance of shared memory. Computations can be based on a global index set. Primitives are used to perform gather and scatter operations on distributed arrays. Communications patterns are derived at run time, and the appropriate send and receive messages are automatically generated. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23065. NR 16 TC 15 Z9 15 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1040-3108 J9 CONCURRENCY-PRACT EX JI Concurrency-Pract. Exp. PD JUN PY 1991 VL 3 IS 3 BP 159 EP 178 DI 10.1002/cpe.4330030303 PG 20 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA GH502 UT WOS:A1991GH50200002 ER PT J AU GOLDEN, DC STEWART, RB TILLMAN, RW WHITE, RE AF GOLDEN, DC STEWART, RB TILLMAN, RW WHITE, RE TI PARTIALLY ACIDULATED REACTIVE PHOSPHATE ROCK (PAPR) FERTILIZER AND ITS REACTIONS IN SOIL .2. MINERALOGY AND MORPHOLOGY OF THE REACTION-PRODUCTS SO FERTILIZER RESEARCH LA English DT Article DE PARTIALLY ACIDULATED PHOSPHATE ROCK; MINERALOGY; PHOSPHATE FERTILIZERS; EDS ANALYSIS AB The fertilizer reaction products formed during the dissolution of PAPR fertilizer applied to two soils of contrasting P retention were studied using electron microscopy and energy dispersive x-ray spectrum (EDS) analysis combined with common mineralogical analysis procedures. Monocalcium phosphate (MCP) and phosphate rock (PR) residue were the main components of the PAPR fertilizer at the time of application. Dissolution of MCP in PAPR led to the formation of dicalcium phosphate dihydrate (DCPD) which was morphologically distinct from the soil matrix and easily analyzed by the microprobe. The amount of DCPD at the granule site was greater in the soil of of low P retention than in the soil of high P retention, consistent with a greater transfer of fertilizer-P to the soil in latter case. The mean crystallite size of carbonate apatite in the fertilizer residue suggested a preferential dissolution of very fine crystallites at acidulations less than 50% during phosphoric acid acidulation. Electron microscopy showed dissolution of primary mineral grains (e.g. clinopyroxene) in soil adjacent to the fertilizer pellet during the dissolution of PAPR fertilizer. The precipitated products in the soil near the PAPR fertilizer pellet were complex compounds containing P, Ca, Al, Fe and Si. There was no evidence of pure phases such as variscite and strengite. These changes were analogous to those occurring in and around fully acidulated P fertilizers (TSP) in soil; however, in the case of PAPR, the reactive phosphate rock residue and DCPD at the site of application may provide a continuous source of P for plants over a long period. RP GOLDEN, DC (reprint author), LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 4 Z9 4 U1 1 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-1731 J9 FERT RES JI Fertil. Res. PD JUN PY 1991 VL 28 IS 3 BP 295 EP 304 DI 10.1007/BF01054330 PG 10 WC Soil Science SC Agriculture GA FX857 UT WOS:A1991FX85700005 ER PT J AU CALDEIRA, K RAMPINO, MR AF CALDEIRA, K RAMPINO, MR TI THE MIDCRETACEOUS SUPER PLUME, CARBON-DIOXIDE, AND GLOBAL WARMING SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TECTONIC EVENTS; CLIMATE; GREENHOUSE; BOUNDARY; CYCLE AB Carbon-dioxide releases associated with a mid-Cretaceous super plume and the emplacement of the Ontong-Java Plateau have been suggested as a principal cause of the mid-Cretaceous global warming. We developed a carbonate-silicate cycle model to quantify the possible climatic effects of these CO2 releases, utilizing four different formulations for the rate of silicate-rock weathering as a function of atmospheric CO2. We find that CO2 emissions resulting from super-plume tectonics could have produced atmospheric CO2 levels from 3.7 to 14.7 times the modern pre-industrial value of 285 ppm. Based on the temperature sensitivity to CO2 increases used in the weathering-rate formulations, this would cause a global warming of from 2.8 to 7.7-degrees-C over today's global mean temperature. Altered continental positions and higher sea level may have been contributed about 4.8-degrees-C to mid-Cretaceous warming. Thus, the combined effects of paleogeographic changes and super-plume related CO2 emissions could be in the range of 7.6 to 12.5-degrees-C, within the 6 to 14-degrees-C range previously estimated for mid-Cretaceous warming. CO2 releases from oceanic plateaus alone are unlikely to have been directly responsible for more than 20% of the mid-Cretaceous increase in atmospheric CO2. C1 PENN STATE UNIV,DEPT GEOSCI,UNIVERSITY PK,PA 16802. NYU,DEPT APPL SCI,EARTH SYST GRP,NEW YORK,NY 10003. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771. RP CALDEIRA, K (reprint author), PENN STATE UNIV,CTR EARTH SYST SCI,UNIVERSITY PK,PA 16802, USA. RI Caldeira, Ken/E-7914-2011 NR 21 TC 94 Z9 96 U1 3 U2 23 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 JUN PY 1991 VL 18 IS 6 BP 987 EP 990 DI 10.1029/91GL01237 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000001 PM 11539811 ER PT J AU STOLARSKI, RS BLOOMFIELD, P MCPETERS, RD HERMAN, JR AF STOLARSKI, RS BLOOMFIELD, P MCPETERS, RD HERMAN, JR TI TOTAL OZONE TRENDS DEDUCED FROM NIMBUS 7 TOMS DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Total Ozone Mapping Spectrometer (TOMS) on the Nimbus 7 satellite has been measuring the total column amount of ozone over the globe for more than 11 years. Recent improvements in the data analysis have led to a technique for determining and removing drift in the calibration such that the data at the end of the record are precise to +/- 1.3% (2-sigma) relative to the data at the beginning of the record. A statistical model, including terms for seasonal variation, linear trend, quasi-biennial oscillation, solar cycle and second-order autoregressive noise has been fit to the TOMS times series of total ozone data. The linear trend obtained when this statistical model is fit to the TOMS data averaged between 65N and 65S latitudes is -0.26 +/- 0.14 %/year or -3% over the 11.6 year time period from November, 1978 through May, 1990. The trend is near zero (0.0002 +/- 0.2 %/year) at the equator and increases towards both poles. At 50N the annually averaged trend is -0.5 +/- .21 %/year. The 50N trend over the 11.6 year time period shows a strong seasonal variation from more than -0.8 %/year in winter and early spring (February and March) to about -0.2 %/year in summer (July and August). C1 N CAROLINA STATE UNIV,DEPT STAT,RALEIGH,NC 27695. RP STOLARSKI, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,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; Herman, Jay/0000-0002-9146-1632 NR 15 TC 404 Z9 416 U1 0 U2 9 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 JUN PY 1991 VL 18 IS 6 BP 1015 EP 1018 DI 10.1029/91GL01302 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000008 ER PT J AU ZHANG, M BELCHER, JW RICHARDSON, JD VASYLIUNAS, VM LEPPING, RP NESS, NF SMITH, CW AF ZHANG, M BELCHER, JW RICHARDSON, JD VASYLIUNAS, VM LEPPING, RP NESS, NF SMITH, CW TI LOW-FREQUENCY WAVES IN THE SOLAR-WIND NEAR NEPTUNE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID UPSTREAM WAVES; BOW SHOCK; VOYAGER-2; PLASMA; MAGNETOSPHERE; PARTICLES AB Plasma and magnetic field observations from the Voyager 2 spacecraft when it was outbound from Neptune reveal low-frequency waves in the solar wind which are clearly associated with the planet. The waves have frequencies below the proton cyclotron frequency f(cp), which is about 10(-3) Hz during the periods waves are observed. The waves are present when the interplanetary magnetic field is oriented such that the spacecraft is connected to the bow shock by the magnetic field lines. We have identified the waves to be Alfvenic waves propagating at approximately 140-degrees to the ambient magnetic field and away from the bow shock. As at the other planets, these downstream waves are thought to be generated in the upstream region, where energetic protons created near the nose of the bow shock excite waves as they stream along solar wind magnetic field lines. C1 MIT,DEPT PHYS,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. RP ZHANG, M (reprint author), MIT,CTR SPACE RES,CAMBRIDGE,MA 02139, USA. NR 20 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 JUN PY 1991 VL 18 IS 6 BP 1071 EP 1074 DI 10.1029/91GL01050 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000022 ER PT J AU LINDQWISTER, UJ ZUMBERGE, JF WEBB, FH BLEWITT, G AF LINDQWISTER, UJ ZUMBERGE, JF WEBB, FH BLEWITT, G TI FEW MILLIMETER PRECISION FOR BASE-LINES IN THE CALIFORNIA PERMANENT GPS GEODETIC ARRAY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Geodetic measurements with Rogue Global Positioning System (GPS) receivers from sites in the California Permanent GPS Geodetic Array (PGGA) have been analyzed using the GIPSY orbit-determination and baseline-estimation software. Based on an unbiased selection of 23 daily measurements spanning 8 months, the low-frequency (greater-than-or-similar-to weeks) contributions to the long-term repeatabilities of baseline measurements are approximately 5, 3, and 8 mm for the east, north, and vertical components. Short-term contributions to the long-term repeatabilities were evaluated by examining data from the week of October 21, 1990, which showed the lowest short-term scatter. For this week, daily repeatabilities of 2-3 mm in the horizontal and 4 mm in the vertical have been achieved for the 172-km JPL-Pinyon baseline, consistent with carrier phase data noise of approximately 6 mm. High quality (less-than-or-similar-to 5 mm) repeatabilities have been achieved for all components of the other baselines as well. RP LINDQWISTER, UJ (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238625,PASADENA,CA 91109, USA. NR 9 TC 13 Z9 13 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 JUN PY 1991 VL 18 IS 6 BP 1135 EP 1138 DI 10.1029/91GL01289 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000038 ER PT J AU SHAHIDSALESS, B HELLINGS, RW ASHBY, N AF SHAHIDSALESS, B HELLINGS, RW ASHBY, N TI A PICOSECOND ACCURACY RELATIVISTIC VLBI MODEL VIA FERMI NORMAL COORDINATES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOCAL INERTIAL FRAMES; EARTH AB We use Fermi normal coordinates to construct transformations relating solar system barycentric coordinates to local inertial geocentric coordinates. We then calculate relativistic corrections to terrestrial VLBI measurements. We develop our formalism to include corrections needed for picosecond accuracy. We also include a calculation of photon time delay which includes effects arising from the motion of gravitational sources. C1 UNIV COLORADO,DEPT PHYS,BOULDER,CO 80309. RP SHAHIDSALESS, B (reprint author), CALTECH,JET PROP LAB,MAIL STOP 301150,PASADENA,CA 91109, USA. NR 8 TC 5 Z9 5 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN PY 1991 VL 18 IS 6 BP 1139 EP 1142 DI 10.1029/91GL01187 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000039 ER PT J AU SENSKE, DA HEAD, JW STOFAN, ER CAMPBELL, DB AF SENSKE, DA HEAD, JW STOFAN, ER CAMPBELL, DB TI GEOLOGY AND STRUCTURE OF BETA REGIO, VENUS - RESULTS FROM ARECIBO RADAR IMAGING SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VOLCANISM; CONVERGENCE; TESSERA; BELTS; TERRA AB Arecibo radar images of a portion of the equatorial region of Venus provide the first high resolution (1.5- to 2.0-km) synoptic coverage of Beta Regio. Within this area, tessera, a complex deformed terrain, is identified as a major geologic unit with the largest region corresponding to a plateau on the east flank of the highland. Three models are proposed to explain the origin and evolution of Beta Regio and are identified as Mantle Plume/Passive Crust, Mantle Plume/Active Crust, and Mantle Plume/Crustal Spreading. The Mantle Plume/Passive Crust model appears to be the most consistent with the geology in this region and suggests that a plume disrupts a preexisting region of tessera. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,NAIC,ITHACA,NY 14853. RP SENSKE, DA (reprint author), BROWN UNIV,DEPT GEOL SCI,BOX 1846,PROVIDENCE,RI 02912, USA. NR 22 TC 21 Z9 22 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 JUN PY 1991 VL 18 IS 6 BP 1159 EP 1162 DI 10.1029/91GL01001 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FR190 UT WOS:A1991FR19000044 ER PT J AU POLLACK, JB AF POLLACK, JB TI KUIPER PRIZE LECTURE - PRESENT AND PAST CLIMATES OF THE TERRESTRIAL PLANETS SO ICARUS LA English DT Article ID EARTHS EARLY ATMOSPHERE; GENERAL-CIRCULATION; MARTIAN ATMOSPHERE; PRIMORDIAL ATMOSPHERE; HYDRODYNAMIC ESCAPE; SUMMER TEMPERATURES; ASTRONOMICAL THEORY; MASS FRACTIONATION; RUNAWAY GREENHOUSE; CARBON-DIOXIDE RP POLLACK, JB (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 100 TC 20 Z9 20 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 JUN PY 1991 VL 91 IS 2 BP 173 EP 198 DI 10.1016/0019-1035(91)90017-N PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FQ205 UT WOS:A1991FQ20500001 ER PT J AU SAMUELSON, RE MAYO, LA AF SAMUELSON, RE MAYO, LA TI THERMAL INFRARED PROPERTIES OF TITANS STRATOSPHERIC AEROSOL SO ICARUS LA English DT Article ID ATMOSPHERE; MODEL; PHOTOCHEMISTRY; TEMPERATURE; SPECTRA; CLOUDS C1 NYMA INC,GREENBELT,MD 20770. RP SAMUELSON, RE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 6932,GREENBELT,MD 20771, USA. NR 28 TC 41 Z9 41 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1991 VL 91 IS 2 BP 207 EP 219 DI 10.1016/0019-1035(91)90019-P PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FQ205 UT WOS:A1991FQ20500003 ER PT J AU LARSON, HP HU, HY HSIEH, KC WEAVER, HA MUMMA, MJ AF LARSON, HP HU, HY HSIEH, KC WEAVER, HA MUMMA, MJ TI DESCRIPTIONS OF THE NEUTRAL GAS OUTFLOW IN COMETS P/HALLEY AND WILSON (1987-VII) FROM ANALYSES OF VELOCITY-RESOLVED H2O LINE-PROFILES SO ICARUS LA English DT Article ID HIGH SPECTRAL RESOLUTION; P-HALLEY; SPATIAL-DISTRIBUTION; EXPANSION VELOCITY; RADIO OBSERVATIONS; IUE OBSERVATIONS; INNER COMA; WATER; OH; AIRBORNE C1 UNIV ARIZONA,DEPT PHYS,TUCSON,AZ 85721. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RP LARSON, HP (reprint author), UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721, USA. RI mumma, michael/I-2764-2013; Weaver, Harold/D-9188-2016 NR 46 TC 6 Z9 6 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 JUN PY 1991 VL 91 IS 2 BP 251 EP 269 DI 10.1016/0019-1035(91)90023-M PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FQ205 UT WOS:A1991FQ20500007 ER PT J AU KOLAWA, E POKELA, PJ REID, JS CHEN, JS RUIZ, RP NICOLET, MA AF KOLAWA, E POKELA, PJ REID, JS CHEN, JS RUIZ, RP NICOLET, MA TI SPUTTERED TA-SI-N DIFFUSION-BARRIERS IN CU METALLIZATIONS FOR SI SO IEEE ELECTRON DEVICE LETTERS LA English DT Article ID SCALE INTEGRATION APPLICATIONS; GENERAL-ASPECTS; ALLOYS; ALUMINUM; LAYERS; SILICON; FILMS; AL AB Electrical measurements on shallow Si n+-p junction diodes with a 30-nm TiSi2 contacting layer demonstrate that an 80-nm-thick amorphous Ta36Si14N50 film prepared by reactive RF sputtering of a Ta5Si3 target in an Ar/N2 plasma very effectively prevents the interaction between the Si substrate with the TiSi2 contacting layer and a 500-nm Cu overlayer. The Ta36Si14N50 diffusion barrier maintains the integrity of the I-V characteristics up to 900-degrees-C for 30-min annealing in vacuum. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP KOLAWA, E (reprint author), CALTECH,PASADENA,CA 91125, USA. RI Chen, Jen-Sue/A-3298-2015 NR 15 TC 65 Z9 65 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD JUN PY 1991 VL 12 IS 6 BP 321 EP 323 DI 10.1109/55.82074 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA FN006 UT WOS:A1991FN00600022 ER PT J AU ALIAHMAD, WY REBEIZ, GM AF ALIAHMAD, WY REBEIZ, GM TI 92 GHZ DUAL-POLARIZED INTEGRATED HORN ANTENNAS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB A dual-polarized two-dimensional imaging array has been designed for millimeter-wave applications. The dual-polarized design consists of two dipoles perpendicular to each other and suspended on the same membrane inside a pyramidal cavity etched in silicon. The dual-polarized antenna is fully monolithic with plenty of room available for processing electronics. The IF or video signals are taken out through a novel bias feeding structure. The measured polarization isolation is better than 20 dB at 92 GHz, and the orthogonal channels show identical far-field patterns. The antenna is well suited for millimeter-wave polarimetric synthetic-aperture radars and high-efficiency balanced-mixer receivers. Additional application areas are dual-polarized antennas for plasma-diagnostics experiments and radio-astronomical measurements. RP ALIAHMAD, WY (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 11 TC 16 Z9 16 U1 2 U2 3 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 JUN PY 1991 VL 39 IS 6 BP 820 EP 825 DI 10.1109/8.86882 PG 6 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FV222 UT WOS:A1991FV22200016 ER PT J AU Whitaker, SR Canaris, JA Cameron, KB AF Whitaker, Sterling R. Canaris, John A. Cameron, Kelly B. TI Reed Solomon VLSI Codec For Advanced Television SO IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY LA English DT Article AB A VLSI Implementation of a Reed Solomon codec circuit is reported. The 1.6-mu m double metal CMOS chip is 8.2 mm by 8.4 mm, contains 200 000 transistors, operates at a sustained data rate of 80 Mbits/s and executes up to 1000 MOPS while consuming less than 500 mW of power. The 10-MHz sustained byte rate for the data is independent of the error pattern. The circuit has complete decoder and encoder functions and uses a single date/system clock. Block lengths of 255 bytes as well as shortened codes an supported with no external buffering. Erasure corrections as well as random error corrections are supported with selectable correction of up to ten symbol errors. Corrected data is output at a fixed latency. These features make this Reed Solomon processor suitable for use in advanced television systems. C1 [Whitaker, Sterling R.; Canaris, John A.; Cameron, Kelly B.] Univ Idaho, NASA, Space Engn Res Ctr VLSI Syst Design, Moscow, ID 83843 USA. RP Whitaker, SR (reprint author), Univ Idaho, NASA, Space Engn Res Ctr VLSI Syst Design, Moscow, ID 83843 USA. FU NASA Space Engineering Research Center [NAGW-1406] FX Manuscript received January 1, 1991; revised April 22, 1991. This research was sponsored in pan by NASA under the NASA Space Engineering Research Center Grant NAGW-1406. NR 19 TC 17 Z9 17 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855 USA SN 1051-8215 J9 IEEE T CIRC SYST VID JI IEEE Trans. Circuits Syst. Video Technol. PD JUN PY 1991 VL 1 IS 2 BP 230 EP 236 DI 10.1109/76.97978 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA V04SC UT WOS:000207077100007 ER PT J AU BRUCKER, GJ STASSINOPOULOS, EG AF BRUCKER, GJ STASSINOPOULOS, EG TI PREDICTION OF ERROR RATES IN DOSE-IMPRINTED MEMORIES ON BOARD CRRES BY 2 DIFFERENT METHODS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB An analysis of the expected space radiation effects on the single event upset (SEU) properties of CMOS/Bulk memories on board the Combined Release and Radiation Effects Satellite (CRRES) is presented. Dose-imprint data from ground test irradiations of identical devices are applied to the predictions of cosmic-ray-induced space upset rates in the memories on board the spacecraft. The calculations take into account the effect of total does on the SEU sensitivity of the devices as the dose accumulates in orbit. Estimates of error rates, which involved an arbitrary selection of a single pair of threshold linear energy transfer (LET) and asymptotic cross-section values, were compared to the results of an integration over the cross-section curves versus LET. The integration gave lower upset rates than the use of the selected values of the SEU parameters. Since the integration approach is more accurate and eliminates the need for an arbitrary definition of threshold LET and asymptotic cross section, it is recommended for all error rate predictions where experimental sigma versus LET curves are available. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BRUCKER, GJ (reprint author), GE,DIV ASTRO SPACE,PRINCETON,NJ 08543, USA. NR 22 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1991 VL 38 IS 3 BP 913 EP 922 DI 10.1109/23.81693 PG 10 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FM797 UT WOS:A1991FM79700005 ER PT J AU MANKBADI, RR MOBARK, A AF MANKBADI, RR MOBARK, A TI QUASI-STEADY TURBULENCE MODELING OF UNSTEADY FLOWS SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article DE TURBULENCE MODELING; UNSTEADY FLOWS; COMPUTATION OF WALL-BOUNDED FLOWS AB This article describes the results of numerical simulations of oscillating wall-bounded developing flows. The full phase-averaged Navier-Stokes equations are solved. The applications of quasi-steady turbulence modeling to unsteady flows is demonstrated using an unsteady version of the k-epsilon model. The effects of unsteadiness on the mean flow and turbulence are studied. Critical evaluation of the applicability of the quasi-steady approach to turbulence modeling is presented. Suggestions are given for future efforts in turbulence modeling of unsteady flows. RP MANKBADI, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 6 Z9 6 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD JUN PY 1991 VL 12 IS 2 BP 122 EP 129 DI 10.1016/0142-727X(91)90038-W PG 8 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA FV145 UT WOS:A1991FV14500004 ER PT J AU TUCKER, CJ NEWCOMB, WW LOS, SO PRINCE, SD AF TUCKER, CJ NEWCOMB, WW LOS, SO PRINCE, SD TI MEAN AND INTER-YEAR VARIATION OF GROWING-SEASON NORMALIZED DIFFERENCE VEGETATION INDEX FOR THE SAHEL 1981-1989 SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article C1 UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742. RP TUCKER, CJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. RI Los, Sietse/G-8985-2012; OI Los, Sietse/0000-0002-1325-3555 NR 8 TC 90 Z9 107 U1 0 U2 13 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 JUN PY 1991 VL 12 IS 6 BP 1133 EP 1135 PG 3 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400001 ER PT J AU HOLBEN, BN ECK, TF FRASER, RS AF HOLBEN, BN ECK, TF FRASER, RS TI TEMPORAL AND SPATIAL VARIABILITY OF AEROSOL OPTICAL DEPTH IN THE SAHEL REGION IN RELATION TO VEGETATION REMOTE-SENSING SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SOLAR-RADIATION; THICKNESS AB A network of Sun photometers was established in the Sahel region of Senegal, Mali and Niger in order to monitor the aerosol characteristics needed for atmospheric correction of remotely sensed data. The aerosol optical thickness tau-a computed from the spectral Sun photometer measurements exhibited very high day-to-day variability ranging from approximately 0.1 to greater than 2.0 at 875 nm for both the wet and dry seasons. A gradient of decreasing tau-a from north-to-south latitudes in the Sahel for the wet season, July-September, was observed, which may be caused jointly by increased washout owing to the gradient of increasing precipitation to the south and the location of source regions for dust in the north. The Angstrom wavelength exponent alpha-was found to vary with the magnitude of the aerosol optical thickness, with values as high as 0.75 for very low tau-a, and values of 0.25 to 0.0 for high tau-a conditions. Analysis of tau-a data from this observation network suggests that there is a high spatial variability of tau-a in the western Sahel region. Statistical analysis performed on the wet season data showed that at a 67 per cent confidence level the instantaneous values of tau-a can be extrapolated approximately 270-400 km with an error tolerance of 50 per cent. Spatial variability in the dry season was of a similar magnitude. The ranges of variations in the NDVI in the Sahel region owing to commonly observed fluctuations in the aerosol optical thickness and aerosol size distribution were shown to be approximately 0.02 and 0.01, respectively. C1 NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP HOLBEN, BN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,CODE 923,GREENBELT,MD 20771, USA. RI ECK, THOMAS/D-7407-2012 NR 25 TC 92 Z9 92 U1 0 U2 4 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 JUN PY 1991 VL 12 IS 6 BP 1147 EP 1163 PG 17 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400003 ER PT J AU JUSTICE, CO ECK, TF TANRE, D HOLBEN, BN AF JUSTICE, CO ECK, TF TANRE, D HOLBEN, BN TI THE EFFECT OF WATER-VAPOR ON THE NORMALIZED DIFFERENCE VEGETATION INDEX DERIVED FOR THE SAHELIAN REGION FROM NOAA AVHRR DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB The near-infrared channel of the NOAA advanced very high resolution radiometer (AVHRR) contains a water vapour absorption band that affects the determination of the normalized difference vegetation index (NDVI). Daily and seasonal variations in atmospheric water vapour within the Sahel are shown to affect the use of the NDVI for the estimation of primary production. This water vapour effect is quantified for the Sahel by radiative transfer modelling and empirically using observations made in Mali in 1986. In extreme cases, changes in water vapour are shown to result in a reduction of the NDVI by 0.1. Variations of the NDVI of 0.01 would result from typical low atmospheric water vapour days within the wet season. If these conditions were to persist throughout the season it would lead to an overestimate of production of 200 kg ha-1. The measurement of atmospheric water vapour using the AVHRR thermal channels, the high-resolution Infrared Sounder 2 (HIRS2), and the microwave sounding unit (MSU) sensors, which are all carried on the NOAA satellites, is discussed. A procedure for operational correction of the water vapour effect on the NDVI is suggested; however, additional studies over a wider range of Sahelian conditions are recommended. C1 NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,GREENBELT,MD 20771. UNIV LILLE 1,OPT ATMOSPHER LAB,F-59655 VILLENEUVE DASCQ,FRANCE. RP JUSTICE, CO (reprint author), UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742, USA. RI ECK, THOMAS/D-7407-2012 NR 35 TC 100 Z9 101 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUN PY 1991 VL 12 IS 6 BP 1165 EP 1187 PG 23 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400004 ER PT J AU SOUFFLET, V TANRE, D BEGUE, A PODAIRE, A DESCHAMPS, PY AF SOUFFLET, V TANRE, D BEGUE, A PODAIRE, A DESCHAMPS, PY TI ATMOSPHERIC EFFECTS ON NOAA AVHRR DATA OVER SAHELIAN REGIONS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID COVER TYPES; REFLECTANCE; AEROSOLS; SPACE; INDEX AB Variable atmospheric conditions have a significant impact on satellite monitoring of vegetation in the Sahelian zone of Africa. The effects of atmospheric O3, H2O and aerosols on spectral, directional reflectances and derived measures, such as the normalized difference vegetation index, are discussed using a sensitivity study. An atmospheric correction scheme is presented based on measurements of optical thickness from the ground and is applied to NOAA AVHRR data. The use of the reflectance of the ocean surface close to the terrestrial target to estimate atmospheric effects on terrestrial reflectance is also discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. CTR SPATIAL TOULOUSE,ETUDES & RECH TELEDETECT SPATIALE LAB,F-31055 TOULOUSE,FRANCE. RP SOUFFLET, V (reprint author), UNIV LILLE 1,OPT ATMOSPHER LAB,BAT P5,F-59655 VILLENEUVE DASCQ,FRANCE. RI begue, agnes/A-5718-2011 OI begue, agnes/0000-0002-9289-1052 NR 31 TC 34 Z9 34 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 JUN PY 1991 VL 12 IS 6 BP 1189 EP 1203 PG 15 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400005 ER PT J AU ECK, TF KALB, VL AF ECK, TF KALB, VL TI CLOUD-SCREENING FOR AFRICA USING A GEOGRAPHICALLY AND SEASONALLY VARIABLE INFRARED THRESHOLD SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID AVHRR DATA; CLEAR-SKY; SURFACE AB A spatially variable monthly, infrared cloud-threshold data base has been applied to screen cloud-contaminated observations from radiances measured by the NOAA-9 Advanced Very High Resolution Radiometer (AVHRR) over Africa. The infrared threshold for cloud identification was based on the method of Stowe et al. (1988) developed to retreive cloud amount and height from measurements made onboard the Nimbus-7 satellite, which uses surface air temperatures, with an empirical correction for water vapour attenuation, and adjustments for the spatial variance of surface temperature and water vapour. A comparison is made between this threshold and a constant threshold of 287 K for Africa for the purpose of cloud-screening in computing the normalized difference vegetation index (NDVI) from AVHRR data. Based on comparisons for a single day, a ten-day composite and a monthly composite for August 1985, the Nimbus-7 variable infrared (IR) threshold screens many cloud-contaminated measurements that the 287 K threshold does not remove. The variable IR threshold was found to be effective over persistently cloud-covered regions, such as the coastal region of the Gulf of Guinea, but may introduce some erroneous cloud identifications over mountains. C1 NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RP ECK, TF (reprint author), ST SYST CORP,4400 FORBES BLVD,LANHAM,MD 20706, USA. RI ECK, THOMAS/D-7407-2012; Kalb, Virginia/A-9971-2009 OI Kalb, Virginia/0000-0002-3107-9271 NR 19 TC 28 Z9 28 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 JUN PY 1991 VL 12 IS 6 BP 1205 EP 1221 PG 17 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400006 ER PT J AU HUETE, AR TUCKER, CJ AF HUETE, AR TUCKER, CJ TI INVESTIGATION OF SOIL INFLUENCES IN AVHRR RED AND NEAR-INFRARED VEGETATION INDEX IMAGERY SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SPECTRAL REFLECTANCE; CANOPY REFLECTANCE; PLANT CANOPY; RADIATION; PHOTOSYNTHESIS; SURFACE; SAHEL AB The effects of soil optical properties on vegetation index imagery are analysed with ground-based spectral measurements and both simulated and actual AVHRR data from the NOAA satellites. Soil effects on vegetation indices were divided into primary variations associated with the brightness of bare soils, secondary variations attributed to 'colour' differences among bare soils, and soil-vegetation spectral mixing. Primary variations were attributed to shifts in the soil line owing to atmosphere or soil composition. Secondary soil variance was responsible for the Saharan desert 'artefact' areas of increased vegetation index response in AVHRR imagery. The impact of soil effects is discussed with a transect of vegetation index data derived from NOAA data from desert to equatorial forest. C1 NASA,GODDARD SPACE FLIGHT CTR,EARTH RESOURCES BRANCH,GREENBELT,MD 20771. RP HUETE, AR (reprint author), UNIV ARIZONA,DEPT SOIL & WATER SCI,TUCSON,AZ 85721, USA. OI Huete, Alfredo/0000-0003-2809-2376 NR 32 TC 109 Z9 112 U1 0 U2 10 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 JUN PY 1991 VL 12 IS 6 BP 1223 EP 1242 PG 20 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FP314 UT WOS:A1991FP31400007 ER PT J AU YARROW, M MEHTA, UB AF YARROW, M MEHTA, UB TI MULTIPROCESSING ON SUPERCOMPUTERS FOR COMPUTATIONAL AERODYNAMICS SO INTERNATIONAL JOURNAL OF SUPERCOMPUTER APPLICATIONS AND HIGH PERFORMANCE COMPUTING LA English DT Article AB Little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPS or more) to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. We apply the concept of multiple instructions and multiple data (MIMD) through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor. C1 NATL AEROSP PLANE PROGRAM,JOINT PROGRAM OFF,WRIGHT PATTERSON AFB,OH. RP YARROW, M (reprint author), NASA,AMES RES CTR,STERLING FED SYST INC,STERLING SOFTWARE,MOFFETT FIELD,CA 94035, USA. NR 24 TC 1 Z9 1 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 SUM PY 1991 VL 5 IS 2 BP 46 EP 72 PG 27 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications SC Computer Science GA FR919 UT WOS:A1991FR91900004 ER PT J AU GHAFFARI, F LUCKRING, JM THOMAS, JL BATES, BL AF GHAFFARI, F LUCKRING, JM THOMAS, JL BATES, BL TI TRANSONIC NAVIER-STOKES SOLUTIONS ABOUT A GENERIC HYPERSONIC CONFIGURATION SO JOURNAL OF AIRCRAFT LA English DT Article AB Three-dimensional transonic viscous flow computations are presented for a generic high-speed accelerator model that includes wing, body, fillets, and a no-flow-through engine nacelle. Solutions are obtained from an algorithm for the compressible Navier-Stokes equations that incorporates an upwind-biased, flux-vector-splitting approach along with longitudinally patched grids. Results are presented for fully turbulent flow assumptions and include correlations with wind-tunnel data. A good quantitative agreement for the forebody surface pressure distribution is achieved between computations and the available wind-tunnel measurements at M infinity = 0.9. Furthermore, it is demonstrated that the flow is stagnating around the boattail region due to separation from the aft-engine cowl lip. RP GHAFFARI, F (reprint author), NASA,LANGLEY RES CTR,DIV AERODYNAM,TRANSON AERODYNAM BRANCH,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 JUN PY 1991 VL 28 IS 6 BP 381 EP 388 DI 10.2514/3.46038 PG 8 WC Engineering, Aerospace SC Engineering GA FX493 UT WOS:A1991FX49300005 ER PT J AU BATINA, JT AF BATINA, JT TI ACCURACY OF AN UNSTRUCTURED-GRID UPWIND-EULER ALGORITHM FOR THE ONERA M6 WING SO JOURNAL OF AIRCRAFT LA English DT Article AB Improved algorithms for the solution of the three-dimensional, time-dependent Euler equations are presented for aerodynamic analysis involving unstructured dynamic meshes. The improvements have been developed recently to the spatial and temporal discretizations used by unstructured-grid flow solvers. The spatial discretization involves a flux-split approach that is naturally dissipative and captures shock waves sharply with at most one grid point within the shock structure. The temporal discretization involves either an explicit time-integration scheme using a multistage Runge-Kutta procedure or an implicit time-integration scheme using a Gauss-Seidel relaxation procedure, which is computationally efficient for either steady or unsteady flow problems. With the implicit Gauss-Seidel procedure, very large time steps may be used for rapid convergence to steady state, and the step size for unsteady cases may be selected for temporal accuracy rather than for numerical stability. Steady flow results are presented for both the NACA 0012 airfoil and the Office National d'Etudes et de Recherches Aerospatiales M6 wing to demonstrate applications of the new Euler solvers. The paper presents a description of the Euler solvers along with results and comparisons that assess the capability. RP BATINA, JT (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,UNSTEADY AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUN PY 1991 VL 28 IS 6 BP 397 EP 402 DI 10.2514/3.46040 PG 6 WC Engineering, Aerospace SC Engineering GA FX493 UT WOS:A1991FX49300007 ER PT J AU FISCHER, B FREUND, R AF FISCHER, B FREUND, R TI CHEBYSHEV POLYNOMIALS ARE NOT ALWAYS OPTIMAL SO JOURNAL OF APPROXIMATION THEORY LA English DT Article C1 UNIV WURZBURG,INST ANGEW MATH & STAT,W-8700 WURZBURG,GERMANY. NASA,AMES RES CTR,RIACS,MOFFETT FIELD,CA 94035. RP FISCHER, B (reprint author), UNIV HAMBURG,INST ANGEW MATH,W-2000 HAMBURG 13,GERMANY. RI Fischer, Bernd/E-4301-2010 NR 13 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 0021-9045 J9 J APPROX THEORY JI J. Approx. Theory PD JUN PY 1991 VL 65 IS 3 BP 261 EP 272 DI 10.1016/0021-9045(91)90091-N PG 12 WC Mathematics SC Mathematics GA FR672 UT WOS:A1991FR67200002 ER PT J AU RAY, RD KOBLINSKY, CJ AF RAY, RD KOBLINSKY, CJ TI ON THE SEA-STATE BIAS OF THE GEOSAT ALTIMETER SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB The sea-state bias in a satellite altimeter's range measurement is caused by the influence of ocean waves on the radar return pulse; it results in an estimate of sea level too low according to some function of the wave height. We have estimated this bias for Geosat by correlating collinear differences of altimetric sea-surface heights with collinear differences of significant wave heights (H1/3). Corrections for satellite orbit error are estimated simultaneously with the sea-state bias. Based on twenty 17-day repeat cycles of the Geosat Exact Repeat Mission, the solution for the sea-state bias is 2.6 +/- 0.2% of H1/3. The least-squares residuals, however, show a correlation with wind speed U, so we have supplemented the traditional model of the bias with a second term: alpha-1H1/3 + alpha-2H1/3U. This second term produces a small, but statistically significant, reduction in variance of the residuals. Both systematic and random errors in H1/3 and U tend to bias the estimates of alpha-1 and alpha-2, which complicates comparisons of our results with ground-based measurements of the sea-state bias. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ST SYST CORP,CODE 926,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012 NR 0 TC 18 Z9 18 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD JUN PY 1991 VL 8 IS 3 BP 397 EP 408 DI 10.1175/1520-0426(1991)008<0397:OTSSBO>2.0.CO;2 PG 12 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA FQ925 UT WOS:A1991FQ92500009 ER PT J AU SALAMA, F ALLAMANDOLA, LJ AF SALAMA, F ALLAMANDOLA, LJ TI ELECTRONIC ABSORPTION-SPECTROSCOPY OF MATRIX-ISOLATED POLYCYCLIC AROMATIC HYDROCARBON CATIONS .1. THE NAPHTHALENE CATION (C10H8+) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID DIFFUSE INTERSTELLAR BANDS; PHOTO-IONIZATION; MOLECULAR-IONS; SOLID ARGON; RADICAL CATIONS; SPECTRA; 2-PHOTON; SINGLE; GLASS AB The ultraviolet, visible, and near infrared absorption spectra of naphthalene (C10H8) and its radical ion (C10H8+), formed by vacuum ultraviolet irradiation, were measured in argon and neon matrices at 4.2 K. The associated vibronic band systems and their spectroscopic assignments are discussed together with the physical and chemical conditions governing ion production in the solid phase. The absorption coefficients were calculated for the ion and found lower than previous values, presumably due to the low polarizability of the neon matrix. This study presents the first spectroscopic data for naphthalene trapped in a neon matrix, where the perturbation of the isolated by its environment is minimum; a condition crucial to astrophysical applications. RP SALAMA, F (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 66 TC 119 Z9 119 U1 0 U2 10 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 JUN 1 PY 1991 VL 94 IS 11 BP 6964 EP 6977 DI 10.1063/1.460230 PG 14 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FL837 UT WOS:A1991FL83700003 ER PT J AU LYNCH, GC HALVICK, P ZHAO, MS TRUHLAR, DG YU, CH KOURI, DJ SCHWENKE, DW AF LYNCH, GC HALVICK, P ZHAO, MS TRUHLAR, DG YU, CH KOURI, DJ SCHWENKE, DW TI CONVERGED 3-DIMENSIONAL QUANTUM-MECHANICAL REACTION PROBABILITIES FOR THE F+H-2 REACTION ON A POTENTIAL-ENERGY SURFACE WITH REALISTIC ENTRANCE AND EXIT CHANNELS AND COMPARISONS TO RESULTS FOR 3 OTHER SURFACES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID TRANSITION-STATE THEORY; SADDLE-POINT VICINITY; CROSS-SECTIONS; MOLECULAR-BEAM; ANGULAR-DISTRIBUTIONS; F+H-2->HF+H REACTION; VARIATIONAL-METHODS; RATE CONSTANTS; FH+H REACTION; REACTION-PATH AB Accurate three-dimensional quantum mechanical reaction probabilities are presented for the reaction F + H-2 --> HF + H on the new global potential energy surface 5SEC for total angular momentum J = 0 over a range of translational energies from 0.15 to 4.6 kcal/mol. We find that the upsilon' = 3 HF vibrational product state has a threshold as low as for upsilon' = 2. We also find considerable structure in the reaction probability and cumulative reaction probability curves which may be indicative of resonance structures. We compare these results to those for another potential energy surface 5SEC-W, which differs from surface 5SEC in the magnitude of the van der Waals well in the entrance channel, and to those for two previous potential energy surfaces. C1 UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA. UNIV HOUSTON, DEPT PHYS, HOUSTON, TX 77004 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV HOUSTON, DEPT CHEM, HOUSTON, TX 77204 USA. RP LYNCH, GC (reprint author), UNIV MINNESOTA, DEPT CHEM, MINNEAPOLIS, MN 55455 USA. RI schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Truhlar, Donald/0000-0002-7742-7294 NR 63 TC 57 Z9 57 U1 0 U2 2 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 JUN 1 PY 1991 VL 94 IS 11 BP 7150 EP 7158 DI 10.1063/1.460198 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FL837 UT WOS:A1991FL83700021 ER PT J AU KAUFMAN, YJ FRASER, RS MAHONEY, RL AF KAUFMAN, YJ FRASER, RS MAHONEY, RL TI FOSSIL-FUEL AND BIOMASS BURNING EFFECT ON CLIMATE - HEATING OR COOLING SO JOURNAL OF CLIMATE LA English DT Article AB Emission from burning of fossil fuels and biomass (associated with deforestation) generates a radiative forcing on the atmosphere and a possible climate change. Emitted trace gases heat the atmosphere through their greenhouse effect, while particulates formed from emitted SO2 cause cooling by increasing cloud albedos through alteration of droplet size distributions. This paper reviews the characteristics of the cooling effect and applies Twomey's theory to check whether the radiative balance favors heating or cooling for the cases of fossil fuel and biomass burning. It is also shown that although coal and oil emit 120 times as many CO2 molecules as SO2 molecules, each SO2 molecule is 50-1100 times more effective in cooling the atmosphere (through the effect of aerosol particles on cloud albedo) than a CO2 molecule is in heating it. Note that this ratio accounts for the large difference in the aerosol (3-10 days) and CO2 (7-100 years) lifetimes. It is concluded, that the cooling effect from coal and oil burning may presently range from 0.4 to 8 times the heating effect. Within this large uncertainty, it is presently more likely that fossil fuel burning causes cooling of the atmosphere rather than heating. Biomass burning associated with deforestation, on the other hand, is more likely to cause heating of the atmosphere than cooling since its aerosol cooling effect is only half that from fossil fuel burning and its heating effect is twice as large. Future increases in coal and oil burning, and the resultant increase in concentration of cloud condensation nuclei, may saturate the cooling effect, allowing the heating effect to dominate. For a doubling in the CO2 concentration due to fossil fuel burning, the cooling effect is expected to be 0.1 to 0.3 of the heating effect. RP KAUFMAN, YJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 613,GREENBELT,MD 20771, USA. NR 0 TC 68 Z9 70 U1 0 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUN PY 1991 VL 4 IS 6 BP 578 EP 588 DI 10.1175/1520-0442(1991)004<0578:FFABBE>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FU024 UT WOS:A1991FU02400002 ER PT J AU VASQUEZ, RP AF VASQUEZ, RP TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF SR AND BA COMPOUNDS SO JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA LA English DT Article ID ALKALINE-EARTH FLUORIDES; LEVEL BINDING-ENERGIES; HIGH-TC SUPERCONDUCTOR; CA-CU-O; ELECTRONIC-STRUCTURE; XPS SPECTRA; CONFIGURATION-INTERACTION; SATELLITE STRUCTURE; MADELUNG ENERGY; METAL HALIDES AB X-ray photoelectron spectroscopy (XPS) measurements of core level binding energies and kinetic energies of X-ray-induced Auger transitions for a comprehensive set of 25 Sr and Ba compounds are reported, including many for which there have been no previous XPS measurements. The majority of the Sr and Ba compounds measured here have cation core level binding energies which are lower than that of the metal, with the negative shifts largest for high temperature superconductors. These data are interpreted within a point charge model, which has previously been used to interpret XPS data from alkali halides and other ionic compounds. Data reported in the literature reveal that, rather than being anomalous, small or negative binding energy shifts are common to many ionic compounds. It is suggested that the large negative shifts observed for the high temperature superconductors are a consequence of large Madelung energies at the cation sites, and may be a measure of the hole distribution on the Cu-O planes. Measurements of the energy loss regions from the core levels of the Sr compounds are also reported. A peak which has previously been assigned as a configuration interaction satellite of the Sr4s peak is shown to be a plasmon loss from the Sr4p peak. RP VASQUEZ, RP (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 75 TC 144 Z9 145 U1 2 U2 22 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0368-2048 J9 J ELECTRON SPECTROSC JI J. Electron Spectrosc. Relat. Phenom. PD JUN PY 1991 VL 56 IS 3 BP 217 EP 240 DI 10.1016/0368-2048(91)85005-E PG 24 WC Spectroscopy SC Spectroscopy GA FQ119 UT WOS:A1991FQ11900005 ER PT J AU SPEZIALE, CG SARKAR, S GATSKI, TB AF SPEZIALE, CG SARKAR, S GATSKI, TB TI MODELING THE PRESSURE STRAIN CORRELATION OF TURBULENCE - AN INVARIANT DYNAMIC-SYSTEMS APPROACH SO JOURNAL OF FLUID MECHANICS LA English DT Article ID ROTATING FRAME; CLOSURE MODELS; SHEAR FLOWS; HOMOGENEOUS TURBULENCE; ISOTROPY; RETURN; FIELD AB The modelling of the pressure-strain correlation of turbulence is examined from a basic theoretical standpoint with a view toward developing improved second-order closure models. Invariance considerations along with elementary dynamical systems theory are used in the analysis of the standard hierarchy of closure models. In these commonly used models, the pressure-strain correlation is assumed to be a linear function of the mean velocity gradients with coefficients that depend algebraically on the anisotropy tensor. It is proven that for plane homogeneous turbulent flows the equilibrium structure of this hierarchy of models is encapsulated by a relatively simple model which is only quadratically nonlinear in the anisotropy tensor. This new quadratic model - the SSG model - appears to yield improved results over the Launder, Reece & Rodi model (as well as more recent models that have a considerably more complex nonlinear structure) in five independent homogeneous turbulent flows. However, some deficiencies still remain for the description of rotating turbulent shear flows that are intrinsic to this general hierarchy of models and, hence, cannot be overcome by the mere introduction of more complex nonlinearities. It is thus argued that the recent trend of adding substantially more complex nonlinear terms containing the anisotropy tensor may be of questionable value in the modelling of the pressure-strain correlation. Possible alternative approaches are discussed briefly. RP SPEZIALE, CG (reprint author), NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665, USA. NR 32 TC 738 Z9 759 U1 6 U2 38 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUN PY 1991 VL 227 BP 245 EP 272 DI 10.1017/S0022112091000101 PG 28 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FU275 UT WOS:A1991FU27500010 ER PT J AU SARKAR, S ERLEBACHER, G HUSSAINI, MY KREISS, HO AF SARKAR, S ERLEBACHER, G HUSSAINI, MY KREISS, HO TI THE ANALYSIS AND MODELING OF DILATATIONAL TERMS IN COMPRESSIBLE TURBULENCE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SHEAR-LAYER AB It is shown that the dilatational terms that need to be modelled in compressible turbulence include not only the pressure-dilatation term but also another term - the compressible dissipation. The nature of the compressible velocity field, which generates these dilatational terms, is explored by asymptotic analysis of the compressible Navier-Stokes equations in the case of homogeneous turbulence. The lowest-order equations for the compressible field are solved and explicit expressions for some of the associated one-point moments are obtained. For low Mach numbers, the compressible mode has a fast timescale relative to the incompressible mode. Therefore, it is proposed that, in moderate Mach number homogeneous turbulence, the compressible component of the turbulence is in quasi-equilibrium with respect to the incompressible turbulence. A non-dimensional parameter which characterizes this equilibrium structure of the compressible mode is identified. Direct numerical simulations (DNS) of isotropic, compressible turbulence are performed, and their results are found to be in agreement with the theoretical analysis. A model for the compressible dissipation is proposed; the model is based on the asymptotic analysis and the direct numerical simulations. This model is calibrated with reference to the DNS results regarding the influence of compressibility on the decay rate of isotropic turbulence. An application of the proposed model to the compressible mixing layer has shown that the model is able to predict the dramatically reduced growth rate of the compressible mixing layer. C1 UNIV CALIF LOS ANGELES,DEPT MATH,LOS ANGELES,CA 90024. RP SARKAR, S (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665, USA. NR 17 TC 287 Z9 301 U1 0 U2 17 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 JUN PY 1991 VL 227 BP 473 EP 493 DI 10.1017/S0022112091000204 PG 21 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FU275 UT WOS:A1991FU27500020 ER PT J AU NEUGEBAUER, M ALEXANDER, CJ AF NEUGEBAUER, M ALEXANDER, CJ TI SHUFFLING FOOT POINTS AND MAGNETOHYDRODYNAMIC DISCONTINUITIES IN THE SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ALFVEN-WAVES; CORONAL STREAMERS; MAGNETIC-FIELD; DIRECTIONAL DISCONTINUITIES; TANGENTIAL DISCONTINUITIES; INTERPLANETARY MEDIUM; HELIUM; ENHANCEMENTS; EVENTS; AU AB ISEE 3 field and plasma data are used to investigate the frequency of occurrence of isolated, large-amplitude rotational (RD) and tangential (TD) discontinuities in different types of solar wind flow. It is found that there are relatively more TDs in solar wind that originates in closed field regions and is ejected into interplanetary space by coronal transients than in the solar wind that originates in open field regions. An exception is the plasma in bidirectional electron streaming events which has very few discontinuities of any type. The speed of the wind from open field regions is approximately linearly related to the number of RDs per hour; such a relation does not exist for the wind associated with coronal mass ejections. These results are consistent with the hypothesis that the convection-driven shuffling of magnetic foot points at the solar surface leads to TDs, magnetic reconnection, and heating of the corona on closed field lines as suggested by Parker, while in the open field regions the disturbances created by the shuffling are carried off by waves which contribute to the acceleration of the solar wind. It is also demonstrated that when the proton beta is low, the plasma cannot support either type of discontinuity. C1 UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP NEUGEBAUER, M (reprint author), CALTECH,JET PROP LAB,MAIL STOP 169-506,PASADENA,CA 91109, USA. NR 39 TC 26 Z9 27 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9409 EP 9418 DI 10.1029/91JA00566 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100002 ER PT J AU KAHLER, SW REAMES, DV AF KAHLER, SW REAMES, DV TI PROBING THE MAGNETIC TOPOLOGIES OF MAGNETIC CLOUDS BY MEANS OF SOLAR ENERGETIC PARTICLES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; INTER-PLANETARY SHOCK; LOOP STRUCTURE; EVENTS; FIELDS; HELIOS; 1-AU AB Magnetic clouds are large (< 0.25 AU) interplanetary regions with topologies consistent with those of magnetic loops. They are of interest because they may be an interplanetary signature of coronal mass ejections. Clouds have been identified in solar wind data by their magnetic properties and by the presence of bidirectional particle fluxes. Two possible closed magnetic topologies have been considered for clouds: (1) an elongated bottle with field lines rooted at both ends in the Sun and (2) a detached magnetic bubble or plasmoid consisting of closed field lines. The inferred topologies are also consistent with open field lines that converge beyond 1 AU. We have used solar energetic particles (SEPs) as probes of the cloud topologies. The rapid access of SEPs to the interiors of many clouds indicates that the cloud field lines extend back to the Sun and hence are not plasmoids. The small modulation of galactic cosmic rays associated with clouds also suggests that the magnetic fields of clouds are not closed. C1 BOSTON COLL,INST SPACE RES,NEWTON,MA. NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771. NR 29 TC 82 Z9 83 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 JUN 1 PY 1991 VL 96 IS A6 BP 9419 EP 9424 DI 10.1029/91JA00659 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100003 ER PT J AU LEPPING, RP BURLAGA, LF TSURUTANI, BT OGILVIE, KW LAZARUS, AJ EVANS, DS KLEIN, LW AF LEPPING, RP BURLAGA, LF TSURUTANI, BT OGILVIE, KW LAZARUS, AJ EVANS, DS KLEIN, LW TI THE INTERACTION OF A VERY LARGE INTERPLANETARY MAGNETIC CLOUD WITH THE MAGNETOSPHERE AND WITH COSMIC-RAYS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; GEOMAGNETIC STORMS; SHOCK; 1-AU; TURBULENCE; VOYAGER; MAXIMUM; FIELDS AB A large interplanetary magnetic cloud has been observed in the mid-December 1982 data from ISEE 3. It is estimated to have a heliocentric radial extent of greater-than-or-similar-to 0.4 AU, making it one of the largest magnetic clouds yet observed at 1 AU. The magnetic field measured throughout the main portion of the cloud was fairly tightly confined to a plane as it changed direction by 174-degrees while varying only moderately in magnitude. Throughout nearly the entire duration of the cloud's passage, IMP 8 was located in the Earth's dawn magnetosheath providing observations of this cloud's interaction with the bow shock and magnetopause; the cloud is shown to maintain its solar wind characteristics during the interaction. Near the end of the cloud passage, at 0806 UT on December 17, ISEE 3 (and IMP 8 at nearly the same time) observed an oblique fast forward interplanetary shock closely coincident in time with a geomagnetic storm sudden commencement. The shock, moving much faster than the cloud (radial speeds of 700 and 390 km/s, respectively, on the average), was in the process of overtaking the cloud. The index Dst decreased monotonically by almost-equal-to 130 nT during the 2-day cloud passage by the Earth and was well correlated with the B(z) component of the interplanetary magnetic field. There was no significant decrease in the cosmic ray intensity recorded by ground-based neutron monitors at this time of rather strong, smoothly changing fields. However, a Forbush decrease did occur immediately after the interplanetary shock, during a period of significant field turbulence. Thus a large, smooth, interplanetary helical magnetic field configuration engulfing the Earth does not necessarily deflect cosmic rays sufficiently to cause a Forbush decrease, but there is a suggestion that such a decrease may be caused by particle scattering by turbulent magnetic fields. Finally, the field observations within the cloud are reasonably well described by a model developed by Burlaga (1988). C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. MIT, CTR SPACE RES, CAMBRIDGE, MA 02139 USA. LOCKHEED MISSILES & SPACE CO INC, RES & DEV, PALO ALTO, CA USA. APPL RES CORP, LANDOVER, MD 20785 USA. RP NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. NR 60 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9425 EP 9438 DI 10.1029/91JA00670 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100004 ER PT J AU LIEWER, PC DECYK, VK DAWSON, JM LEMBEGE, B AF LIEWER, PC DECYK, VK DAWSON, JM LEMBEGE, B TI NUMERICAL-STUDIES OF ELECTRON DYNAMICS IN OBLIQUE QUASI-PERPENDICULAR COLLISIONLESS SHOCK-WAVES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MACH NUMBER; BOW SHOCKS; SIMULATION; ION AB Linear and nonlinear electron damping of the whistler precursor wave train to low Mach number quasi-perpendicular oblique shocks is studied using a one-dimensional electromagnetic plasma simulation code with particle electrons and ions. In some parameter regimes, electrons are observed to trap along the magnetic field lines in the potential of the whistler precursor wave train. This trapping can lead to significant electron heating in front of the shock for low beta-e (approximately 10% or less). Use of the 64-processor Caltech/JPL Mark IIIfp hypercube concurrent computer has enabled us to make long runs using realistic mass ratios (m(i)/m(e) = 1600) in the full particle in-cell code and thus simulate shock parameter regimes and phenomena not previously studied numerically. C1 UNIV CALIF LOS ANGELES,DEPT PHYS,LOS ANGELES,CA 90024. CTR NATL ETUD TELECOMMUN,CTR RECH PHYS ENVIRONNEMENT,F-92131 ISSY MOULINEAUX,FRANCE. RP LIEWER, PC (reprint author), CALTECH,JET PROP LAB,MS 198-231,PASADENA,CA 91109, USA. NR 22 TC 32 Z9 32 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 JUN 1 PY 1991 VL 96 IS A6 BP 9455 EP 9465 DI 10.1029/91JA00655 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100006 ER PT J AU GOMBOSI, TI NEUGEBAUER, M JOHNSTONE, AD COATES, AJ HUDDLESTON, DE AF GOMBOSI, TI NEUGEBAUER, M JOHNSTONE, AD COATES, AJ HUDDLESTON, DE TI COMPARISON OF OBSERVED AND CALCULATED IMPLANTED ION DISTRIBUTIONS OUTSIDE COMET HALLEY BOW SHOCK SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WATER GROUP IONS; SOLAR-WIND; PICKUP IONS; ELECTROMAGNETIC INSTABILITIES; VELOCITY DISTRIBUTIONS; GIACOBINI-ZINNER; ACCELERATION; UPSTREAM; GIOTTO; TURBULENCE AB This paper compares calculated and measured energy spectra of implanted H+ and O+ ions on the assumption that the pickup geometry is quasi-parallel and about 1% of the waves generated by the cometary pickup process propagate backward (toward the comet). The model provides a good description of the implanted O+ and H+ energy distribution near the pickup energies. The thickness of the implanted ion velocity distribution shells was nearly constant between 2.50 x 10(6) km and 1.20 x 10(6) km (just outside the shock) along the inbound Giotto trajectory. The explanation is that the velocity diffusion coefficient and characteristic diffusion time vary approximately as 1/r and r, respectively, and therefore their product (which determines the velocity shell thickness) remains nearly constant. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UCL, MULLARD SPACE SCI LAB, DORKING RH5 6NT, SURREY, ENGLAND. RP GOMBOSI, TI (reprint author), UNIV MICHIGAN, DEPT ATMOSPHER OCEAN & SPACE SCI, SPACE PHYS RES LAB, 2455 HAYWARD, ANN ARBOR, MI 48109 USA. RI Coates, Andrew/C-2396-2008; Gombosi, Tamas/G-4238-2011 OI Coates, Andrew/0000-0002-6185-3125; Gombosi, Tamas/0000-0001-9360-4951 NR 43 TC 25 Z9 25 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 JUN 1 PY 1991 VL 96 IS A6 BP 9467 EP 9477 DI 10.1029/90JA02750 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100007 ER PT J AU KINTNER, PM SCALES, W VAGO, J YAU, A WHALEN, B ARNOLDY, R MOORE, T AF KINTNER, PM SCALES, W VAGO, J YAU, A WHALEN, B ARNOLDY, R MOORE, T TI HARMONIC H+ GYROFREQUENCY STRUCTURES IN AURORAL HISS OBSERVED BY HIGH-ALTITUDE AURORAL SOUNDING ROCKETS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOWER HYBRID WAVES; ELECTROSTATIC ION-CYCLOTRON; SUPRAURORAL REGION; BEAM INSTABILITIES; VIKING SATELLITE; PLASMA; ACCELERATION; ENVIRONMENT AB Two recent sounding rocket experiments have yielded VLF wave data with spectral structures ordered by the hydrogen gyrofrequency. The spectral structures occur near and above the lower hybrid frequency in association with auroral hiss. These structures are observed within and near regions of auroral electron precipitation and transverse ion acceleration. They are accompanied by auroral hiss but are anticorrelated with spectral peaks at the lower hybrid frequency. They are typically found above 500 km altitude, have no measurable magnetic component, and are at least occasionally short wavelength (k-rho-i-greater-than-or-equal-to 1). Because the spectral structures appear to be electrostatic, are ordered by the hydrogen gyrofrequency, and are short wavelength, we interpret the structures as modes which connect the lower hybrid mode with the hydrogen Bemstein modes. A study of the plasma wave mode structure in the vicinity of the lower hybrid frequency is presented to substantiate this interpretation. Our results imply that these waves are a common feature of the auroral zone ionosphere above 500 km altitude and exist any time that auroral hiss exists. The absence of previous satellite observations of this phenomenon can be explained by Doppler broadening. C1 USN,RES LAB,CODE 4780,WASHINGTON,DC 20375. UNIV NEW HAMPSHIRE,DEPT PHYS,DURHAM,NH 03824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,OTTAWA K1A 0R6,ONTARIO,CANADA. RP KINTNER, PM (reprint author), CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853, USA. RI Moore, Thomas/D-4675-2012; Yau, Andrew/E-7007-2013 OI Moore, Thomas/0000-0002-3150-1137; Yau, Andrew/0000-0002-8210-0392 NR 32 TC 22 Z9 22 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9627 EP 9638 DI 10.1029/91JA00563 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100019 ER PT J AU KELLEY, MC SWENSON, CM BRENNING, N BAKER, K PFAFF, R AF KELLEY, MC SWENSON, CM BRENNING, N BAKER, K PFAFF, R TI ELECTRIC AND MAGNETIC-FIELD MEASUREMENTS INSIDE A HIGH-VELOCITY NEUTRAL BEAM UNDERGOING IONIZATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DAYTIME EQUATORIAL ELECTROJET; PLASMA-DENSITY MEASUREMENTS; INSTABILITIES; WAVES; CONDOR; STAR AB Vector electric field measurements have been made inside two ionizing, high-velocity streams of barium atoms in the Earth's ionosphere. A variety of electrical phenomena were observed across the frequency spectrum and are presented in this paper, which emphasizes the experimental results. Comparisons with a theoretical model for the interactions of the stream with the magnetic field and the ionosphere are presented in a companion paper (Brenning et al., this issue (a)). A most startling result is that a very large quasi-dc electric field was detected antiparallel to the beam velocity. This by itself is not unreasonable since newly ionized barium ions with their large gyroradii are expected to create such a field. But since the beam had roughly a 45-degrees angle with the magnetic field, B(o), we find a very large (greater-than-or-similar-to 500 mV/m) component of E parallel to B(o). The fluctuating electric fields were also quite large, in fact, of the same order of magnitude as the quasi-dc pulse. The wave energy was found to maximize at frequencies below the barium lower hybrid frequency and included strong signatures of the oxygen cyclotron frequency. Measurements made on a subpayload separated across B(o) by several hundred meters and along B(o) by several kilometers do not show the large pulse, although a variety of wave emissions were seen. In addition, very large amplitude magnetic field fluctuations were detected in both bursts. Although we have no clear explanation, they appear to be a real phenomenon and worthy of future study. Finally, we note that even though the critical ionization velocity effect did not go into a discharge mode in this experiment, remarkable electromagnetic effects were seen in the neutral beam-plasma interaction. C1 ROYAL INST TECHNOL,S-10044 STOCKHOLM 70,SWEDEN. UTAH STATE UNIV,LOGAN,UT 84322. NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771. RP KELLEY, MC (reprint author), CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853, USA. RI Pfaff, Robert/F-5703-2012; Brenning, Nils/B-5965-2017 OI Pfaff, Robert/0000-0002-4881-9715; NR 25 TC 26 Z9 26 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 JUN 1 PY 1991 VL 96 IS A6 BP 9703 EP 9718 DI 10.1029/91JA00442 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100024 ER PT J AU BRENNING, N FALTHAMMAR, CG HAERENDEL, G KELLEY, MC MARKLUND, G PFAFF, R PROVIDAKES, J STENBAEKNIELSEN, HC SWENSON, C TORBERT, R WESCOTT, EM AF BRENNING, N FALTHAMMAR, CG HAERENDEL, G KELLEY, MC MARKLUND, G PFAFF, R PROVIDAKES, J STENBAEKNIELSEN, HC SWENSON, C TORBERT, R WESCOTT, EM TI INTERPRETATION OF THE ELECTRIC-FIELDS MEASURED IN AN IONOSPHERIC CRITICAL IONIZATION VELOCITY EXPERIMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SPACE AB This paper deals with the quasi-dc electric fields measured in the CRIT I ionospheric release experiment, which was launched from Wallops Island on May 13, 1986. The purpose of the experiment was to study the critical ionization velocity (CIV) mechanism in the ionosphere. Two identical barium shaped charges were fired from distances of 1.99 km and 4.34 km towards a main payload, which made full three-dimensional measurements of the electric field inside the streams. There was also a subpayload separated from the main payload by a couple of kilometers along the magnetic field. The relevance of earlier proposed mechanisms for electron heating in CIV is investigated in the light of the CRIT I results. It is concluded that both the "homogeneous" and the "ionizing front" models probably apply, but in different parts of the stream. It is also possible that electrons are directly accelerated by a magnetic-field-aligned component of the electric field; the quasi-dc electric field observed within the streams had a large magnetic-field-aligned component, persisting on the time scale of the passage of the streams. The coupling between the ambient ionosphere and the ionized barium stream in CRIT I was more complicated than is usually assumed in CIV theories, with strong magnetic-field-aligned electric fields and probably current limitation as important processes. One interpretation of the quasi-dc electric field data is that the internal electric fields of the streams were not greatly modified by magnetic-field-aligned currents, i.e., a state was established where the transverse currents were to a first approximation divergence-free. It is argued that this interpretation can explain both a reversal of the strong explosion-directed electric field in burst 1 and the absence of such a reversal in burst 2. C1 MAX PLANCK INST EXTRATERRESTR PHYS,W-8046 GARCHING,GERMANY. CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853. NASA,GODDARD SPACE FLIGHT CTR,CODE 696,GREENBELT,MD 20771. MITRE CORP,BEDFORD,MA 01730. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775. UNIV NEW HAMPSHIRE,CTR SPACE SCI,IEOS,DURHAM,NH 03824. RP BRENNING, N (reprint author), ROYAL INST TECHNOL,DEPT PLASMA PHYS,S-10044 STOCKHOLM 70,SWEDEN. RI Pfaff, Robert/F-5703-2012; Brenning, Nils/B-5965-2017 OI Pfaff, Robert/0000-0002-4881-9715; NR 28 TC 25 Z9 25 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9719 EP 9733 DI 10.1029/90JA00692 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100025 ER PT J AU WATANABE, S WHALEN, BA WALLIS, DD PFAFF, RF AF WATANABE, S WHALEN, BA WALLIS, DD PFAFF, RF TI OBSERVATIONS OF ION-NEUTRAL COLLISIONAL EFFECTS IN THE AURORAL E-REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INCOHERENT-SCATTER RADAR; VELOCITY DISTRIBUTIONS; RELAXATION MODEL; HIGH-LATITUDES; F-REGION; EISCAT; IONOSPHERE; FREQUENCY; WIND AB Thermal ion energy distribution functions and local electric and magnetic fields were directly measured for the first time in the ionospheric E region on board rockets which were launched as part of the E Region Rocket/Radar Instability Study (ERRRIS) from Esrange, Sweden, in 1988 and 1989 to investigate plasma instabilities in the auroral ionosphere. Measured ion distribution functions were fitted to shifted Maxwellian distributions, and their resulting ion drift velocities were compared with E x B/B2 velocities from the double-probe electric field observations. The results show that the ion drift direction rotates with respect to the local electric field direction and that the ratio of the magnitudes of the ion velocity to the E x B/B2 velocity decreases with decreasing altitudes. Using these observations, the quiet time ion-neutral collision frequencies and neutral wind velocities were estimated and found to be consistent with theoretical estimates. However, significant discrepancies between observations and theory are found in the disturbed E region near auroral particle precipitation regions. These data indicate that the auroral atmosphere is significantly perturbed due to Joule as well as particle heating effects. C1 NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,OTTAWA K1A 0R6,ONTARIO,CANADA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RI Watanabe, Shigeto/A-4305-2012; Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 24 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9761 EP 9771 DI 10.1029/91JA00561 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100029 ER PT J AU FOK, MC KOZYRA, JU WARREN, MF BRACE, LH AF FOK, MC KOZYRA, JU WARREN, MF BRACE, LH TI SEASONAL-VARIATIONS IN THE SUBAURORAL ELECTRON-TEMPERATURE ENHANCEMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AURORAL RED ARCS; MAGNETOSPHERIC ION COMPOSITION; SOLAR-ACTIVITY; F-REGION; PLASMASPHERE; IONOSPHERE; PLASMAPAUSE; SIGNATURES AB The subauroral nightside electron temperature peak is one of the phenomena showing the response of the subauroral ionosphere to the influx of magnetic storm energy in the vicinity of the plasmapause. A statistical study of the seasonal variations of the subauroral electron temperature enhancement was undertaken using data from the Langmuir probe experiment on the DE 2 satellite throughout most of the mission (1981-1982). In the winter hemisphere the nighttime background electron temperature is the highest and the magnitude of the peak T(e) responds most weakly to the geomagnetic activity. This behavior can be explained by seasonal trends in the nighttime downward heat flux due to conjugate photoelectrons. Moreover, model results indicate that a factor of approximately 3 increase in heat inflow during equinox relative to solstice is required to raise the electron temperature to a given level. This is a consequence of the higher electron densities at the T(e) peak near equinox. The T(e) peak occurs on field lines which thread the outer plasmasphere in the vicinity of the plasmapause and thus can be used as a tracer of the plasmapause position. Correlating the position of the T(e) peak with K(p)' (the highest value of 3-hour K(p) in the preceding 12 hours) indicates a trend toward a more expanded quiet time plasmasphere and one which is more easily compressed by magnetic storms at equinox than during the solstice period. C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,GREENBELT,MD 20771. RP FOK, MC (reprint author), UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,SPACE PHYS RES LAB,ANN ARBOR,MI 48109, USA. RI Fok, Mei-Ching/D-1626-2012 NR 34 TC 13 Z9 13 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1991 VL 96 IS A6 BP 9773 EP 9780 DI 10.1029/91JA00791 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FV651 UT WOS:A1991FV65100030 ER PT J AU RAMESHAM, R ROPPEL, T ELLIS, C JAWORSKE, DA BAUGH, W AF RAMESHAM, R ROPPEL, T ELLIS, C JAWORSKE, DA BAUGH, W TI SELECTIVE AND LOW-TEMPERATURE SYNTHESIS OF POLYCRYSTALLINE DIAMOND SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID MICROWAVE PLASMA; DEPOSITION; FILMS; GROWTH AB Polycrystalline diamond thin films have been deposited on single crystal silicon substrates at low temperatures (less-than-or-equal-to 600-degrees-C) using a mixture of hydrogen and methane gases by high pressure microwave plasma-assisted chemical vapor deposition. Low temperature deposition has been achieved by cooling the substrate holder with nitrogen gas. For deposition at reduced substrate temperature, it has been found that nucleation of diamond will not occur unless the methane/hydrogen ratio is increased significantly from its value at higher substrate temperature. Selective deposition of polycrystalline diamond thin films has been achieved at 600-degrees-C. Decrease in the diamond particle size and growth rate and an increase in surface smoothness have been observed with decreasing substrate temperature during the growth of thin films. As-deposited films are identified by Raman spectroscopy, and the morphology is analyzed by scanning electron microscopy. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAMESHAM, R (reprint author), AUBURN UNIV,ALABAMA MICROELECTR SCI & TECHNOL CTR,DEPT ELECT ENGN,AUBURN,AL 36849, USA. NR 20 TC 60 Z9 61 U1 0 U2 2 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 JUN PY 1991 VL 6 IS 6 BP 1278 EP 1286 DI 10.1557/JMR.1991.1278 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA FQ052 UT WOS:A1991FQ05200018 ER PT J AU NAIK, RA POLLOCK, WD JOHNSON, WS AF NAIK, RA POLLOCK, WD JOHNSON, WS TI EFFECT OF A HIGH-TEMPERATURE CYCLE ON THE MECHANICAL-PROPERTIES OF SILICON-CARBIDE TITANIUM METAL MATRIX COMPOSITES SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB The effect of fibre/matrix interface strength and thermal residual stresses on the mechanical properties of a silicon carbide/titanium composite were investigated. A 3-ply [0/90/0] composite was subjected to a simulated superplastic forming/diffusion bonding (SPF/DB) temperature cycle which changed fibre/matrix interfacial strength and thermal residual stresses in the composite. The [0/90/0] composite subjected to the SPF/DB process showed a 25% decrease in ultimate tensile strength (UTS) and a 30% decrease in failure strain compared to the as-fabricated (ASF) material. The fatigue life for the SPF/DB specimens was approximately 50% lower than the ASF specimens. The fracture surface of the ASF specimens was very irregular accompanied by substantial fibre pull-out as compared to the planar fracture surface of the SPF/DB cycled specimens that showed negligible fibre pull-out. The large changes in the tensile strength and fatigue life due to the SPF/DB cycle are explained by a difference in the failure mechanisms occurring as a result of the SPF/DB-induced changes in the strength of the fibre/matrix interface and higher thermal residual stresses. Unreinforced titanium was also tested to study the effect of the SPF/DB cycle on the matrix static properties. Fibres were etched from the composite and then individually tested for modulus and strength. Finally, a microscopic examination of the fibre/matrix interface was performed to study the effects of the SPF/DB cycle on the interface. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP NAIK, RA (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 9 TC 18 Z9 18 U1 1 U2 1 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD JUN 1 PY 1991 VL 26 IS 11 BP 2913 EP 2920 DI 10.1007/BF01124821 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA FQ934 UT WOS:A1991FQ93400012 ER PT J AU BENIDAR, A FARRENQ, R GUELACHVILI, G CHACKERIAN, C AF BENIDAR, A FARRENQ, R GUELACHVILI, G CHACKERIAN, C TI ANOMALOUS ROVIBRATIONAL INTENSITIES IN THE DELTA-V = 1-BANDS OF SH (CHI-2-PI) SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID SPECTROSCOPY; MOLECULES; SPECTRUM; BANDS C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV PARIS 11,INFRAROUGE LAB,F-91405 ORSAY,FRANCE. RI benidar, abdessamad/O-1624-2014 NR 19 TC 9 Z9 9 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUN PY 1991 VL 147 IS 2 BP 383 EP 391 DI 10.1016/0022-2852(91)90063-G PG 9 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FL581 UT WOS:A1991FL58100008 ER PT J AU PARK, K CHANCE, KV NOLT, IG RADOSTITZ, JV VANEK, MD JENNINGS, DA EVENSON, KM AF PARK, K CHANCE, KV NOLT, IG RADOSTITZ, JV VANEK, MD JENNINGS, DA EVENSON, KM TI PRESSURE BROADENING OF THE 2.5 THZ (HCL)-CL-35 ROTATIONAL LINE BY N2 AND O2 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID FAR-INFRARED SPECTROSCOPY; HCL; TEMPERATURE; WIDTHS; BAND C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NATL INST STANDARDS & TECHNOL,GAITHERSBURG,MD. RP PARK, K (reprint author), UNIV OREGON,DEPT PHYS,EUGENE,OR 97403, USA. OI Chance, Kelly/0000-0002-7339-7577 NR 9 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUN PY 1991 VL 147 IS 2 BP 521 EP 525 DI 10.1016/0022-2852(91)90075-L PG 5 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FL581 UT WOS:A1991FL58100020 ER PT J AU FU, LL VAZQUEZ, J PERIGAUD, C AF FU, LL VAZQUEZ, J PERIGAUD, C TI FITTING DYNAMIC-MODELS TO THE GEOSAT SEA-LEVEL OBSERVATIONS IN THE TROPICAL PACIFIC-OCEAN .1. A FREE WAVE MODEL SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID ALTIMETER DATA; ROSSBY WAVES AB Free, equatorially trapped sinusoidal wave solutions to a linear model on an equatorial beta plane are used to fit the Geosat altimetric sea level observations in the Tropical Pacific Ocean. The Kalman filter technique is used to estimate the wave amplitude and phase from the data. The estimation is performed at each time step by combining the model forecast with the observation in an optimal fashion utilizing the respective error covariances. The model error covariance is determined such that the performance of the model forecast is optimized. It is found that the dominant observed features can be described qualitatively by basin-scale Kelvin waves and the first meridional mode Rossby waves. Quantitatively, however, only 23% of the signal variance can be accounted for by this simple model. RP FU, LL (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 16 Z9 16 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUN PY 1991 VL 21 IS 6 BP 798 EP 809 DI 10.1175/1520-0485(1991)021<0798:FDMTTG>2.0.CO;2 PG 12 WC Oceanography SC Oceanography GA FQ336 UT WOS:A1991FQ33600004 ER PT J AU GROSSMANN, BE BROWELL, EV AF GROSSMANN, BE BROWELL, EV TI LINE-SHAPE ASYMMETRY OF WATER-VAPOR ABSORPTION-LINES IN THE 720-NM WAVELENGTH REGION SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID HIGH-RESOLUTION; ARGON; AIR; HF AB Spectral line-shape analyses were performed for water vapor lines broadened by argon, oxygen, and xenon in the 720-nm wavelength region. A line-shape asymmetry was observed, which is attributed to statistical dependence or correlation between velocity- and state-changing collisions. The generalized (asymmetric) Galatry profile, which results from the soft-collision profile and includes correlation between velocity- and state-changing collisions, was fitted to the observed line shapes and was found to compare favorably with the observed data. The most prominent asymmetries were observed with xenon as the buffer gas. C1 ST SYST CORP,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. NR 10 TC 19 Z9 20 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUN PY 1991 VL 45 IS 6 BP 339 EP 348 DI 10.1016/0022-4073(91)90069-3 PG 10 WC Optics; Spectroscopy SC Optics; Spectroscopy GA FL600 UT WOS:A1991FL60000002 ER PT J AU HUBBARD, HH SHEPHERD, KP AF HUBBARD, HH SHEPHERD, KP TI AEROACOUSTICS OF LARGE WIND TURBINES SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Review ID BROAD-BAND NOISE; PROPAGATION; PREDICTION; ROTORS AB This paper reviews published information on aerodynamically generated noise from large horizontal axis wind turbines operated for electric power generation. Methods are presented for predicting both the discrete frequency rotational noise components and the broadband noise components, and results are compared with measurements. Refraction effects that result in the formation of high-frequency shadow zones in the upwind direction and channeling effects for the low frequencies in the downwind direction are illustrated. Special topics such as distributed source effects in prediction and the role of building dynamics in perception are also included. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HUBBARD, HH (reprint author), LOCKHEED ENGN & SCI CO,144 RES DR,HAMPTON,VA 23666, USA. NR 51 TC 43 Z9 45 U1 2 U2 10 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 JUN PY 1991 VL 89 IS 6 BP 2495 EP 2508 DI 10.1121/1.401021 PG 14 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA FP536 UT WOS:A1991FP53600001 ER PT J AU BATTLES, AH KNAPKA, JT LEWIS, L LANG, MT GRUENDEL, DJ AF BATTLES, AH KNAPKA, JT LEWIS, L LANG, MT GRUENDEL, DJ TI HIGH-MOISTURE DIET FOR LABORATORY RATS - NUTRIENT ANALYSIS, GROWTH, AND ORGAN WEIGHTS SO LABORATORY ANIMAL SCIENCE LA English DT Article AB A diet (KSC-25) to be sterilized by irradiation was formulated to contain 66% moisture and to provide the required nutrients for growing rats. Analyses of the irradiated dry diet provided data to evaluate its nutrient content. The diet was evaluated for its ability to supply all nutrients, including water, required by immature rats. Sixteen Sprague-Dawley rats were fed the high-moisture diet with or without access to a water bottle. Rats (n = 16) fed an irradiated purified diet in a meal form with access to a water bottle were the control animals. Feed efficiency, food and water consumption, and growth rate data were collected during the 28-day study. Organ weights were collected on day 28. The test diet met or exceeded the National Research Council (NRC) estimated nutritional requirements for immature laboratory rats. The 66% moisture KSC-25 diet provided all nutrients, including water, required by weanling male Sprague-Dawley rats for growth equivalent to the established purified diet. C1 NIH,NATL CTR RES RESOURCES,VET RESOURCES PROGRAM,BETHESDA,MD 20892. RP BATTLES, AH (reprint author), BIONET CORP,NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMER ASSOC LABORATORY ANIMAL SCIENCE PI CORDOVA PA 70 TIMBERCREEK DR, SUITE 5, CORDOVA, TN 38018 SN 0023-6764 J9 LAB ANIM SCI JI Lab. Anim. Sci. PD JUN PY 1991 VL 41 IS 3 BP 237 EP 241 PG 5 WC Veterinary Sciences; Zoology SC Veterinary Sciences; Zoology GA GF778 UT WOS:A1991GF77800004 PM 1658461 ER PT J AU BATTLES, AH KNAPKA, JT STEVENS, BR LEWIS, L LANG, MT GRUENDEL, DJ AF BATTLES, AH KNAPKA, JT STEVENS, BR LEWIS, L LANG, MT GRUENDEL, DJ TI HIGH-MOISTURE DIET FOR LABORATORY RATS - COMPLETE BLOOD COUNTS, SERUM BIOCHEMICAL VALUES, AND INTESTINAL ENZYME-ACTIVITY SO LABORATORY ANIMAL SCIENCE LA English DT Article ID SUCRASE; LIVER AB Rats were fed an irradiated high-moisture diet (KSC-25) with or without access to a water bottle. Physiologic values were compared between these two groups and a group of rats fed a purified diet. Hematologic and serum biochemical values, urine specific gravity, and intestinal enzyme activities were determined from samples collected from the three groups of rats. Sprague Dawley rats (n = 32) fed the irradiated high-moisture diet with or without a water bottle were the test animals. Rats (n = 16) fed an irradiated purified diet and water provided via a water bottle were the control group. The purified diet formulation, modified AIN-76A, is a commonly used purified diet for laboratory rodents. All rats remained alert and healthy throughout the study. A comparison of the physiologic values of rats in this study with reported normal values indicated that all of the rats in the study were in good health. Significant differences (P < 0.05) of the physiologic values from each rat group are reported. C1 NIH,NATL CTR RES RESOURCES,VET RESOURCES PROGRAM,BETHESDA,MD 20892. UNIV FLORIDA,COLL MED,DEPT PHYSIOL,GAINESVILLE,FL 32610. RP BATTLES, AH (reprint author), BIONET CORP,NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899, USA. NR 18 TC 1 Z9 1 U1 0 U2 0 PU AMER ASSOC LABORATORY ANIMAL SCIENCE PI CORDOVA PA 70 TIMBERCREEK DR, SUITE 5, CORDOVA, TN 38018 SN 0023-6764 J9 LAB ANIM SCI JI Lab. Anim. Sci. PD JUN PY 1991 VL 41 IS 3 BP 242 EP 245 PG 4 WC Veterinary Sciences; Zoology SC Veterinary Sciences; Zoology GA GF778 UT WOS:A1991GF77800005 PM 1658462 ER PT J AU BAUER, JE HADDAD, RI DESMARAIS, DJ AF BAUER, JE HADDAD, RI DESMARAIS, DJ TI METHOD FOR DETERMINING STABLE ISOTOPE RATIOS OF DISSOLVED ORGANIC-CARBON IN INTERSTITIAL AND OTHER NATURAL MARINE WATERS SO MARINE CHEMISTRY LA English DT Article ID SEAWATER AB A procedure is described for the analysis of the stable carbon isotopic composition of dissolved organic carbon (DOC) in natural waters from marine and higher-salinity environments. Rapid (less than 5 min) and complete oxidation of DOC is achieved using a modification of previous photochemical oxidation techniques. The CO2 evolved from DOC oxidation can be collected in less than 10 min for isotopic analysis. The procedure is at present suitable for oxidation and collection of 1-5-mu-mol of carbon and has an associated blank of 0.1-0.2-mu-mol of carbon. Complete photochemical oxidation of DOC standards was demonstrated by quantitative recovery of CO2 as measured manometrically. Isotopic analyses of standards by photochemical and high-temperature sealed-tube combustion methods agreed to within 0.3 parts per thousand. Photochemical oxidation of DOC in a representative sediment pore-water sample was also quantitative, as shown by the excellent agreement between the photochemical and sealed-tube methods. The delta-C-13 values obtained for pore-water DOC using the two methods of oxidation were identical, suggesting that the modified photochemical method is adequate for the isotopically non-fractionated oxidation of pore-water DOC. The procedure was evaluated through an analysis of DOC in pond and pore waters from a hypersaline microbial mat environment. Concentrations of DOC in the water column over the mat displayed a diel pattern, but the isotopic composition of this DOC remained relatively constant (average delta-C-13 = -12.4 parts per thousand). Pore-water DOC exhibited a distinct concentration maximum in the mat surface layer, and delta-C-13 of pore-water DOC was nearly 8 parts per thousand lighter at 1.5-2.0-cm depth than in the mat surface layer (0-0.5-cm depth). These results demonstrate the effectiveness of the method in elucidating differences in DOC concentration and delta-C-13 over biogeochemically relevant spatial and temporal scales. Carbon isotopic analysis of DOC in natural waters, especially pore waters, should be a useful probe of biogeochemical processes in recent environments. C1 UNION OIL CO CALIF,DIV SCI & TECHNOL,BREA,CA 92621. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,DIV MARINE RES,LA JOLLA,CA 92093. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 22 TC 21 Z9 21 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-4203 J9 MAR CHEM JI Mar. Chem. PD JUN PY 1991 VL 33 IS 4 BP 335 EP 351 DI 10.1016/0304-4203(91)90076-9 PG 17 WC Chemistry, Multidisciplinary; Oceanography SC Chemistry; Oceanography GA FR870 UT WOS:A1991FR87000003 PM 11538651 ER PT J AU GOODING, JL WENTWORTH, SJ ZOLENSKY, ME AF GOODING, JL WENTWORTH, SJ ZOLENSKY, ME TI AQUEOUS ALTERATION OF THE NAKHLA METEORITE SO METEORITICS LA English DT Article ID SNC METEORITES; EVOLUTION; ORIGIN AB Interior samples of three different Nakhla specimens contain an iron-rich silicate "rust" (which includes a tentatively identified smectite), Ca-carbonate (probably calcite), Ca-sulfate (possibly gypsum or bassanite), Mg-sulfate (possibly epsomite or kieserite), and NaCl (halite); the total abundance of these phases is estimated as < 0.01 weight percent of the bulk meteorite. Rust veins are truncated and decrepitated by fusion crust and are preserved as faulted segments in partially healed olivine crystals, indicating that the rust is pre-terrestrial in origin. Because Ca-carbonate and Ca-sulfate are intergrown with the rust, they are also indicated to be of pre-terrestrial origin. Similar textural evidence regarding origins of the NaCl and Mg-sulfate is lacking. Impure and poorly crystallized sulfates and halides on the fusion crust of the meteorite suggest leaching of interior (pre-terrestrial) salts from the interior after Nakhla arrived on Earth but coincidental addition of these same salts by terrestrial contamination cannot be excluded. At least the clay-like silicate "rust," Ca-carbonate, and Ca-sulfate were formed by precipitation from water-based solutions on the Nakhla parent planet although temperature and pressure conditions of aqueous precipitation are unconstrained by currently available data. It is possible that aqueous alteration on the parent body was responsible for the previously observed disturbance of the Rb-Sr geochronometer in Nakhla at or near 1.3 Ga. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP GOODING, JL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH SN21,HOUSTON,TX 77058, USA. NR 21 TC 192 Z9 193 U1 0 U2 8 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUN PY 1991 VL 26 IS 2 BP 135 EP 143 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FU416 UT WOS:A1991FU41600007 ER PT J AU MACHIN, G ALLINGTONSMITH, J CALLANAN, PJ CHARLES, PA HASSALL, BJM MASON, KO MUKAI, K NAYLOR, T SMALE, AP VANPARADIJS, J AF MACHIN, G ALLINGTONSMITH, J CALLANAN, PJ CHARLES, PA HASSALL, BJM MASON, KO MUKAI, K NAYLOR, T SMALE, AP VANPARADIJS, J TI WHT OBSERVATIONS OF CATACLYSMIC VARIABLES IN GLOBULAR-CLUSTERS .3. V4 IN M30 DURING QUIESCENCE SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID X-RAY SOURCES; OPTIMAL EXTRACTION; BINARIES; SPECTRA; STARS AB We report the results of William Herschel telescope (WHT) observations of the candidate globular-cluster dward nova, V4 in M30. We find that, on the basis of its quiescent magnitude and colours, its outburst magnitude and its radial velocity, V4 is likely to be a foreground object in the field of M30. In addition, it is probably a short-period system near the period gap. C1 UNIV DURHAM, DEPT PHYS, DURHAM DH1 3LE, ENGLAND. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. UNIV OXFORD, DEPT ASTROPHYS, OXFORD OX1 3RH, ENGLAND. ROYAL GREENWICH OBSERV, E-38780 SANTA CRUZ PALMA, SPAIN. ROYAL GREENWICH OBSERV, CAMBRIDGE CB3 0EZ, ENGLAND. UCL, MULLARD SPACE SCI LAB, DORKING RH5 6NT, SURREY, ENGLAND. UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. UNIV AMSTERDAM, ASTRON INST ANTON PANNEKOEK, 1018 WB AMSTERDAM, NETHERLANDS. NATL INST NUCL PHYS & HIGH ENERGY PHYS, CTR HIGH ENERGY ASTROPHYS, AMSTERDAM, NETHERLANDS. RI Naylor, Tim /A-9465-2015 NR 29 TC 6 Z9 6 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN 1 PY 1991 VL 250 IS 3 BP 602 EP 606 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FP180 UT WOS:A1991FP18000014 ER PT J AU CHANG, JT WETZEL, PJ AF CHANG, JT WETZEL, PJ TI EFFECTS OF SPATIAL VARIATIONS OF SOIL-MOISTURE AND VEGETATION ON THE EVOLUTION OF A PRESTORM ENVIRONMENT - A NUMERICAL CASE-STUDY SO MONTHLY WEATHER REVIEW LA English DT Article ID PLANETARY BOUNDARY-LAYER; SEVERE-STORM ENVIRONMENT; MESOSCALE CIRCULATIONS; MIXED-LAYER; JET STREAK; MODEL; PRECIPITATION; SENSITIVITY; GENERATION; INCLUSION AB To study the effects of spatial variations of soil moisture and vegetation coverage on the evolution of a prestorm environment, the Goddard mesoscale model (GMASS) was modified to incorporate a simple evapotranspiration model that requires these two parameters. Soil moisture was estimated from an antecedent precipitation index. Relative fractional vegetation coverage was estimated from a normalized difference vegetation index (NDVI). The case study, 3-4 June 1980, is of particular interest because of the development of a tornado producing convective complex near Grand Island, Nebraska, during a period of relatively weak synoptic-scale forcing. Three model simulations are compared. The first had no spatial variations in either soil moisture or vegetation; the second had soil moisture variability but no vegetation; and in the third, the observed variabilities of both soil moisture and vegetation are simulated. The modeled effects of spatial variations of vegetation and soil moisture include the enhancement of a stationary front oriented northwest-southeast through Grand Island. Prior to sunset, the unstable boundary layer collapses over a zone of cool surface temperature aligned with the observed front and coincident with an observed dry/moist soil boundary. Following the boundary layer collapse, the evolution of the ageostrophic flow exhibits a horizontally differential acceleration that amplifies the isolated upward motion over the frontal boundary. It is shown that the observed stationary front was strongly enhanced by differential heating caused by observed gradients of soil moisture, as acted upon by the vegetation cover. Thus, the run with realistic vegetation and soil moisture produces the best forecast of storm precursor conditions. C1 NASA,GODDARD SPACE FLIGHT CTR,SEVERE STORMS BRANCH,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771. ST SYST CORP,LANHAM,MD. NR 25 TC 116 Z9 120 U1 1 U2 4 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 JUN PY 1991 VL 119 IS 6 BP 1368 EP 1390 DI 10.1175/1520-0493(1991)119<1368:EOSVOS>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FR466 UT WOS:A1991FR46600003 ER PT J AU KIM, SW AF KIM, SW TI NUMERICAL INVESTIGATION OF AN INTERNAL LAYER IN TURBULENT-FLOW OVER A CURVED HILL SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID ALGEBRAIC STRESS; BOUNDARY-LAYERS; MODEL; CURVATURE AB The development of an internal layer in a turbulent boundary layer flow over a curved hill is investigated numerically. The turbulent flow equations are solved by a control volume based, finite-difference method. The turbulence is described by a multiple-time-scale turbulence model. Computational results show that the internal layer is a strong turbulence field that develops beneath the external boundary layer and is located very close to the wall. The turbulence field of the boundary layer flow over the curved hill is compared with that of a turbulent flow over a symmetric airfoil (which has the same geometry as the curved hill except that the leading and trailing edge plates were removed) to study the influence of a strongly curved surface on the turbulence field. The turbulence structure in the near-wall region of the curved hill is almost the same as that of the airfoil in most of the curved region even though the approaching external flows are quite different. Results show that the development of the wall shearing stress and separation of the boundary layer at the rear of the curved hill depend mostly on the streamline curvature and are only slightly influenced by the external boundary layer flow. RP KIM, SW (reprint author), NASA,LEWIS RES CTR,INST COMP MECH PROPULS,CLEVELAND,OH 44135, USA. NR 22 TC 1 Z9 1 U1 0 U2 0 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 JUN PY 1991 VL 19 IS 4 BP 425 EP 444 DI 10.1080/10407789108944858 PG 20 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA FR854 UT WOS:A1991FR85400003 ER PT J AU MARDER, SR PERRY, JW TIEMANN, BG SCHAEFER, WP AF MARDER, SR PERRY, JW TIEMANN, BG SCHAEFER, WP TI ORGANOMETALLIC SALTS WITH LARGE 2ND-HARMONIC-GENERATION POWDER EFFICIENCIES - (E)-1-FERROCENYL-2-(1-METHYL-4-PYRIDINIUMYL)ETHYLENE SALTS SO ORGANOMETALLICS LA English DT Article ID 2ND-ORDER OPTICAL SUSCEPTIBILITIES; HYPERPOLARIZABILITIES; NONLINEARITIES; GENERATION; CRYSTALS; ORIGIN AB A series of salts of the form (E)-(eta-C5H5)Fe(eta-C5H4)CH = CH(4-C5H4N-1-CH3)+X- has been synthesized. Variation of the counterion leads to materials with second-harmonic-generation powder efficiencies at 1907-nm fundamental as large as 220 times that of a urea reference standard. This is the largest value reported for an organometallic compound. The crystal structure of the nitrate salt, which had a powder SHG efficiency 110 times that of urea, was determined: (FeC18H18N)+NO3-, monoclinic, Cc (No. 9), a = 17.618 (4) angstrom, b = 10.780 (3) angstrom, c = 12.528 (3) angstrom, beta = 133.18 (2)degrees, Z = 4. C1 CALTECH, DIV CHEM & CHEM ENGN, PASADENA, CA 91125 USA. RP MARDER, SR (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 25 TC 171 Z9 172 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0276-7333 EI 1520-6041 J9 ORGANOMETALLICS JI Organometallics PD JUN PY 1991 VL 10 IS 6 BP 1896 EP 1901 DI 10.1021/om00052a039 PG 6 WC Chemistry, Inorganic & Nuclear; Chemistry, Organic SC Chemistry GA FQ933 UT WOS:A1991FQ93300039 ER PT J AU Rau, GH Froelich, PN Takahashi, T Des Marais, DJ AF Rau, G. H. Froelich, P. N. Takahashi, T. Des Marais, D. J. TI DOES SEDIMENTARY ORGANIC s(13)C RECORD VARIATIONS IN QUATERNARY OCEAN [CO2 (aq)] ? SO PALEOCEANOGRAPHY LA English DT Article AB Ocean surface water [CO2(aq)] Variations based on glacial/interglacial changesin sediment s(13)C(org) are shown to compare favorably with reconstructions based on ice core [CO2]. In particular, an approximate 80 uatm increase in atmospheric pCO(2) during the last glacial-interglacial transition is calculated to correspond to a 3-4 umolar increase in ocean surface water [CO2(aq)] at atmospheric equilibrium. A widespread marine s(13)C(org) decrease of 1-2 o/oo accomorg panled this event and was not preceded by an equivalent isotopic change in surface water total dissolved inorganic carbon. These observations support the hypothesis that [CO2(aq)] influences photosynthetic isotope fractionation between marine inorganic and organic carbon pools, and therefore that plankton/sediment s(13)C(org) may serve as a proxy for surface water [CO2(aq)]. C1 [Rau, G. H.] Univ Calif Santa Cruz, Inst Marine Sci, Santa Cruz, CA 95064 USA. [Rau, G. H.; Des Marais, D. J.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. [Froelich, P. N.; Takahashi, T.] Lamont Doherty Geol Observ, Palisades, NY 10964 USA. RP Rau, GH (reprint author), Univ Calif Santa Cruz, Inst Marine Sci, Santa Cruz, CA 95064 USA. FU National Science Foundation [DPP 8613981, OCE 9012172, OCE 9017773] FX G. H. R. thanks M. R. Fontugne for helpful discussions, A. Tharpe for technical assistance, and the National Science Foundation for financial support (DPP 8613981, OCE 9012172, and OCE 9017773). Constructive reviews of this paper by S. Calvert, J. Hayes, and M. Arthur were greatly appreciated. NR 46 TC 112 Z9 117 U1 2 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0883-8305 J9 PALEOCEANOGRAPHY JI Paleoceanography PD JUN PY 1991 VL 6 IS 3 BP 335 EP 347 DI 10.1029/91PA00321 PG 13 WC Geosciences, Multidisciplinary; Oceanography; Paleontology SC Geology; Oceanography; Paleontology GA V23JU UT WOS:000208339900003 PM 11538490 ER PT J AU BEGAULT, DR AF BEGAULT, DR TI PREFERRED SOUND INTENSITY INCREASE FOR SENSATION OF HALF DISTANCE SO PERCEPTUAL AND MOTOR SKILLS LA English DT Article RP BEGAULT, DR (reprint author), NASA,AMES RES CTR,NATL RES COUNCIL,MS 262-2,MOFFETT FIELD,CA 94035, USA. NR 20 TC 5 Z9 6 U1 0 U2 1 PU PERCEPTUAL MOTOR SKILLS PI MISSOULA PA PO BOX 9229, MISSOULA, MT 59807 SN 0031-5125 J9 PERCEPT MOTOR SKILL JI Percept. Mot. Skills PD JUN PY 1991 VL 72 IS 3 BP 1019 EP 1029 DI 10.2466/PMS.72.3.1019-1029 PN 1 PG 11 WC Psychology, Experimental SC Psychology GA FV007 UT WOS:A1991FV00700053 PM 1891303 ER PT J AU DAVIS, FW QUATTROCHI, DA RIDD, MK LAM, NSN WALSH, SJ MICHAELSEN, JC FRANKLIN, J STOW, DA JOHANNSEN, CJ JOHNSTON, CA AF DAVIS, FW QUATTROCHI, DA RIDD, MK LAM, NSN WALSH, SJ MICHAELSEN, JC FRANKLIN, J STOW, DA JOHANNSEN, CJ JOHNSTON, CA TI ENVIRONMENTAL-ANALYSIS USING INTEGRATED GIS AND REMOTELY SENSED DATA - SOME RESEARCH NEEDS AND PRIORITIES SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID GEOGRAPHIC INFORMATION-SYSTEMS; SPATIAL VARIATION; MULTISCALE SOURCES; MODELS; IMAGES; LANDSCAPE; LANDSAT; SCALE; SOIL; CLASSIFICATION AB This paper discusses some basic scientific issues and research needs in the joint processing of remotely sensed and GIS data for environmental analysis. Two general topics are treated in detail: (1) scale dependence of geographic data and the analysis of multiscale remotely sensed and GIS data, and (2) data transformations and information flow during data processing. The discussion of scale dependence focuses on the theory and applications of spatial autocorrelation, geostatistics, and fractals for characterizing and modeling spatial variation. Research using these and related techniques is needed to identify characteristic space and time scales of surface variation, to help define the measurement scales of remotely sensed and GIS data, and to formulate strategies for acquiring and integrating multiscale geographic data to model Earth systems. Data transformations during processing are described within the larger framework of geographical analysis, encompassing sampling, cartography, remote sensing, and GIS. These transformations, which may introduce noise but may also involve more fundamental changes in the input data, have not been investigated in terms of overall processing flow and information development. Development of better user interfaces between image processing, GIS, database management, and statistical software is needed to expedite research on these and other impediments to integrated analysis of remotely sensed and GIS data. C1 NASA, JOHN C STENNIS SPACE CTR, SCI & TECHNOL LAB, STENNIS SPACE CTR, MS 39529 USA. UNIV UTAH, RES INST, CTR REMOTE SENSING & CARTOG, SALT LAKE CITY, UT 84108 USA. LOUISIANA STATE UNIV, DEPT GEOG & ANTHROPOL, BATON ROUGE, LA 70803 USA. UNIV N CAROLINA, DEPT GEOGR, CHAPEL HILL, NC 27599 USA. SAN DIEGO STATE UNIV, DEPT GEOG, SAN DIEGO, CA 92182 USA. PURDUE UNIV, APPLICAT REMOTE SENSING LAB, W LAFAYETTE, IN 47907 USA. UNIV MINNESOTA, NAT RESOURCES RES INST, DULUTH, MN 55811 USA. RP DAVIS, FW (reprint author), UNIV CALIF SANTA BARBARA, DEPT GEOG, SANTA BARBARA, CA 93106 USA. RI Davis, Frank/B-7010-2009; OI Davis, Frank/0000-0002-4643-5718; Johnston, Carol/0000-0002-9663-5048 NR 79 TC 59 Z9 63 U1 3 U2 9 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 JUN PY 1991 VL 57 IS 6 BP 689 EP 697 PG 9 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA FP856 UT WOS:A1991FP85600012 ER PT J AU SCHLOSSER, H FERRANTE, J AF SCHLOSSER, H FERRANTE, J TI PRESSURE-DEPENDENCE OF THE MELTING TEMPERATURE OF SOLIDS - RARE-GAS SOLIDS SO PHYSICAL REVIEW B LA English DT Article ID STATE; ARGON; EQUATION; KBAR AB Recently, we presented a method for analyzing experimental data for the pressure dependence of the melting temperature of metals. In this paper, we address the question of the applicability of this method to other types of solids, and demonstrate that it is indeed also applicable to rare-gas solids. We find that, as for metals, in the absence of phase transitions, plots of the logarithm of the reduced melting temperature T' (= T(m)/T(m0)X2) versus the logarithm of the reduced pressure P' (= 1 + beta-P) are straight lines with slope-GAMMA = 2-gamma-0/alpha, where T(m0) is the zero-pressure melting temperature, X = (V/V0)1/3, gamma-0 is the Gruneisen parameter at T(m0), V is the volume, V0 is the volume at zero pressure, beta = alpha/B0, B0 is the isothermal bulk modulus at T(m0), and alpha is a fitting parameter. In addition, we demonstrate that, to a very good approximation, all of the reduced melting temperature for Ar, Kr, and Xe fall on a single straight line. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SCHLOSSER, H (reprint author), CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115, USA. NR 27 TC 6 Z9 6 U1 0 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUN 1 PY 1991 VL 43 IS 16 BP 13305 EP 13308 DI 10.1103/PhysRevB.43.13305 PN B PG 4 WC Physics, Condensed Matter SC Physics GA FP632 UT WOS:A1991FP63200006 ER PT J AU CANUTO, VM CHENG, Y HARTKE, GJ SCHILLING, O AF CANUTO, VM CHENG, Y HARTKE, GJ SCHILLING, O TI SOURCE FUNCTION-APPROACH TO TURBULENCE BULK PROPERTIES SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID 2-DIMENSIONAL TURBULENCE; SHEAR FLOWS; MODEL; CONVECTION AB A turbulence model to compute bulk properties is presented in which a prescribed source function is used to provide the rate of energy input into the turbulent flow, and the EDQNM model is used to treat the nonlinear transfer in the Navier-Stokes equations. The predictions of the model are tested against (1) the measured Nusselt number versus Rayleigh number relation in turbulent laboratory convection, and (2) the measured bulk kinetic energies and dissipation rates in turbulent channel flow for Reynolds numbers Re = 12 300 and 30 800. In addition, a sensitivity study is performed with respect to the choice of Kolmogorov constant. Generally, the predictions of the model are in reasonable accord with the available experimental data. C1 COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027. RP CANUTO, VM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. OI Schilling, Oleg/0000-0002-0623-2940 NR 29 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD JUN PY 1991 VL 3 IS 6 BP 1633 EP 1644 DI 10.1063/1.857942 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FN767 UT WOS:A1991FN76700017 ER PT J AU DEZERN, JF GAUTREAUX, CR AF DEZERN, JF GAUTREAUX, CR TI SYNTHESIS AND CHARACTERIZATION OF POLYAMIDE-IMIDES SO POLYMER ENGINEERING AND SCIENCE LA English DT Article AB A series of thermally stable, tough, linear polyimides containing amide linkages was prepared. The new polyamide-imides were synthesized by reacting a group of isomers of diaminobenzanilide (DABA) with various dianhydrides, such as 4,4'-oxydiphthalic anhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The resulting polyamide-acids were thermally or chemically converted to the polyamide-imide (PAI). Twelve polyimides were synthesized from unsubstituted and N-methyl substituted amide diamines and their properties were compared with previously made polyamide-imides and the polyimide LARC-TPI. These polyimides exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films of which some showed good thermal stability and resistance to organic solvents. Overall, the mechanical properties of the PAI films were comparable to those of LARC-TPI with the 4.4'-systems exhibiting exceptional properties and crystallinity. These materials have potential as high temperature films, coatings and fibers, as well as molding and laminating resins. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. RP DEZERN, JF (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 TC 2 Z9 2 U1 1 U2 7 PU SOC PLASTICS ENG INC PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06804-0403 SN 0032-3888 J9 POLYM ENG SCI JI Polym. Eng. Sci. PD JUN PY 1991 VL 31 IS 12 BP 860 EP 866 DI 10.1002/pen.760311204 PG 7 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA FU259 UT WOS:A1991FU25900003 ER PT J AU LI, F RANEY, RK AF LI, F RANEY, RK TI PROLOG TO THE SPECIAL SECTION ON SPACEBORNE RADARS FOR EARTH AND PLANETARY OBSERVATIONS SO PROCEEDINGS OF THE IEEE LA English DT Editorial Material C1 CANADA CTR REMOTE SENSING,RADARSAT PROJ OFF,OTTAWA K1P 5M9,ONTARIO,CANADA. RP LI, F (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 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 JUN PY 1991 VL 79 IS 6 BP 773 EP 776 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900005 ER PT J AU JOHNSON, WTK AF JOHNSON, WTK TI MAGELLAN IMAGING RADAR MISSION TO VENUS SO PROCEEDINGS OF THE IEEE LA English DT Article ID VOLCANISM; ZONES AB The Magellan imaging radar mapping mission has collected and processed data from the spacecraft in an elliptical orbit around Venus. This multimode radar is the only science instrument on the mission and has the objectives of mapping at least 70% of the planet surface. It has three modes: synthetic aperture radar (SAR), altimetry, and passive radiometry. The radar system has produced maps of almost all of the Venusian surface with a resolution better than 600 m equivalent optical line pair and the best resolution obtained is equivalent to less than 300 m. The system design and operation required to produce the high resolution images from an elliptical orbit was complex and innovative. This paper describes the mission, the spacecraft, and the radar system design including the sensor in detail, the ground processing, and data products; lastly, some of the radar images are shown. RP JOHNSON, WTK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 25 Z9 25 U1 1 U2 14 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 JUN PY 1991 VL 79 IS 6 BP 777 EP 790 DI 10.1109/5.90157 PG 14 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900006 ER PT J AU ZIEGER, AR HANCOCK, DW HAYNE, GS PURDY, CL AF ZIEGER, AR HANCOCK, DW HAYNE, GS PURDY, CL TI NASA RADAR ALTIMETER FOR THE TOPEX POSEIDON PROJECT SO PROCEEDINGS OF THE IEEE LA English DT Article ID WIND-SPEED; SURFACE AB Over-ocean radar altimetry combines precision orbit determination (POD) and precise measurements from the sea surface to the satellite center-of-mass to infer the topography of the ocean surface under study. The radar altimeter provides one element of this measurement, i.e., the distance from the sea surface to the satellite. The NASA Radar Altimeter (NRA) is a fifth generation U.S. altimeter that will provide the primary measurement for the TOPEX/POSEIDON Project altimetric mission. We present the requirements, altimeter fundamentals, design description, integration and test program, primary elements of ground processing, and assessment for the dual frequency NASA Radar Altimeter. C1 GODDARD SPACE FLIGHT CTR,NASA,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. RP ZIEGER, AR (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 28 TC 48 Z9 49 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 JUN PY 1991 VL 79 IS 6 BP 810 EP 826 DI 10.1109/5.90160 PG 17 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900009 ER PT J AU JORDAN, RL HUNEYCUTT, BL WERNER, M AF JORDAN, RL HUNEYCUTT, BL WERNER, M TI THE SIR-C/X-SAR SYNTHETIC APERTURE RADAR SYSTEM SO PROCEEDINGS OF THE IEEE LA English DT Article AB The SIR-C/X-SAR Synthetic Aperture Radar is a three-frequency radar to be flown on the Space Shuttle in September 1993. The SIR-C system is a two-frequency radar and is the third of a series of imaging radars to be flown on the Shuttle. The SIR-C system operates at 1250 MHz (L-band) and 5300 MHz (C-band) and is designed to get four polarization radar imagery at multiple surface angles. The X-Band Synthetic Aperture Radar (X-SAR) system is an X-band imaging radar operating at 9600 MHz being developed under the joint sponsorship of the German and Italian governments. Both radars share a common antenna structure and operate in synchronism. C1 GERMAN AEROSP RES ESTAB,INST HOCHFREQUENZTECH,W-8031 OBERPFAFFENHOFEN,GERMANY. RP JORDAN, RL (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 25 Z9 28 U1 13 U2 13 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 JUN PY 1991 VL 79 IS 6 BP 827 EP 838 DI 10.1109/5.90161 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900010 ER PT J AU NADERI, FM FREILICH, MH LONG, DG AF NADERI, FM FREILICH, MH LONG, DG TI SPACEBORNE RADAR MEASUREMENT OF WIND VELOCITY OVER THE OCEAN - AN OVERVIEW OF THE NSCAT SCATTEROMETER SYSTEM SO PROCEEDINGS OF THE IEEE LA English DT Review ID A SATELLITE SCATTEROMETER; SEASAT SCATTEROMETER; MODEL; ALGORITHMS; SCATTERING; SPECTRA; FIELDS AB Satellite scatterometers are microwave radars capable of measuring near-surface vector winds (both speed and direction) over the oceans under all-weather conditions. Such data are required for most studies of upper ocean circulation, tropospheric dynamics, and air-sea interaction. In conjunction with an empirically determined relationship between radar cross section and wind velocity, scatterometry employs colocated measurements of the radar cross section of the ocean from multiple azimuth angles to estimate vector winds. The technique has been demonstrated with the flight of the Seasat scatterometer in 1978; additional satellite scatterometers will be orbited in the early 1990's by European and U.S. space agencies. This paper summarizes scatterometry and scatterometer design issues, with emphasis on the design of the NASA Scatterometer (NSCAT) to be flown on the Japanese ADEOS mission. Building on the Seasat experience, the NSCAT system includes several enhancements (such as three antenna azimuths in each of two swaths, and an on-board digital Doppler processor to allow backscatter measurements to be colocated everywhere within the orbit) that will greatly increase the quality of the NSCAT wind data. RP CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RI Long, David/K-4908-2015 OI Long, David/0000-0002-1852-3972 NR 37 TC 182 Z9 192 U1 3 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9219 EI 1558-2256 J9 P IEEE JI Proc. IEEE PD JUN PY 1991 VL 79 IS 6 BP 850 EP 866 DI 10.1109/5.90163 PG 17 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900012 ER PT J AU ELACHI, C IM, E ROTH, LE WERNER, CL AF ELACHI, C IM, E ROTH, LE WERNER, CL TI CASSINI TITAN RADAR MAPPER SO PROCEEDINGS OF THE IEEE LA English DT Article ID LOW-TEMPERATURES; SURFACE-TENSION; ATMOSPHERE; OCEAN; SAR AB Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission. The spacecraft is scheduled for launch in 1995 and is expected to arrive at Saturn and be inserted in orbit around Saturn in late 2003. The individual modes of Cassini Radar Mapper will allow surface imaging at few hundred meters resolution, and topographic mapping. The Mapper will be in operation during close flybys of Titan and will map approximately 30% of Titan's surface in the course of the nominal mission. RP ELACHI, C (reprint author), CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 32 TC 34 Z9 34 U1 2 U2 3 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 JUN PY 1991 VL 79 IS 6 BP 867 EP 880 DI 10.1109/5.90164 PG 14 WC Engineering, Electrical & Electronic SC Engineering GA GA449 UT WOS:A1991GA44900013 ER PT J AU BANKS, HT FITZPATRICK, BG AF BANKS, HT FITZPATRICK, BG TI ESTIMATION OF GROWTH-RATE DISTRIBUTIONS IN SIZE STRUCTURED POPULATION-MODEL SO QUARTERLY OF APPLIED MATHEMATICS LA English DT Article AB We propose models for size-structured populations which allow growth rates to vary with individuals (growth rate distribution across all possible individual growth rates). A theoretical framework for the estimation of the growth rate distribution from data of sized population densities is developed. Numerical examples are presented to demonstrate feasibility of the ideas. C1 UNIV TENNESSEE,KNOXVILLE,TN 37996. BROWN UNIV,DIV APPL MATH,CTR CONTROL SCI,PROVIDENCE,RI 02912. NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665. RP BANKS, HT (reprint author), UNIV SO CALIF,LOS ANGELES,CA 90089, USA. NR 13 TC 40 Z9 42 U1 0 U2 2 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0033-569X J9 Q APPL MATH JI Q. Appl. Math. PD JUN PY 1991 VL 49 IS 2 BP 215 EP 235 PG 21 WC Mathematics, Applied SC Mathematics GA FP205 UT WOS:A1991FP20500002 ER PT J AU CHAPPELLE, EW MCMURTREY, JE KIM, MS AF CHAPPELLE, EW MCMURTREY, JE KIM, MS TI IDENTIFICATION OF THE PIGMENT RESPONSIBLE FOR THE BLUE FLUORESCENCE BAND IN THE LASER-INDUCED FLUORESCENCE (LIF) SPECTRA OF GREEN PLANTS, AND THE POTENTIAL USE OF THIS BAND IN REMOTELY ESTIMATING RATES OF PHOTOSYNTHESIS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID PRIMARY-CELL WALL; PHENOLIC COMPONENTS AB The laser-induced fluorescence (LIF) of vegetation is being investigated in this laboratory for use as a technique for the remote detection of the effects of environmental stress upon vegetation, as well as for plant identification. The fluorescence band with a maximum at 440 nm, in conjunction with the chlorophyll bands with maxima at 685 and 740 nm, has been found to be a critical band in the development of algorithms for detecting stress, and identifying plant types. The identification of the plant constituent responsible for this band is vital to understanding the mechanism underlying its fluorescence changes in response to environmental and physiological changes. The identification was achieved as follows: The laser induced fluorescence (LIF) spectra of pure plant pigments were determined. Fluorescence bands with maxima at 420 nm, 440 nm, 490 nm, and 525 nm were observed for vitamin K1, reduced nicotinamide adenine dinucleotide (NADPH), beta-carotene, and riboflavin, respectively. The LIF spectra of water extracts and acetone extracts of clover leaves were also measured. It was found that the blue fluorescence band was associated with the water extract. NADPH which is a water-soluble compound, and the water extract of clover had no fluorescence after oxidation by potassium ferricyanide, while the fluorescence of water insoluble vitamin K1 was unchanged by the oxidizing agent. It was also found that the absorption maximum of NADPH was the same as the absorption maximum of the aqueous extract of clover. The above findings indicated that the compound responsible for the blue fluorescence at 440 nm is in the reduced state and is water-soluble. It was concluded that NADPH was responsible for the blue fluorescence at 440 nm. The strong linear relationship between the fluorescence at 440 nm and the rate of photosynthesis suggests the possible use of LIF measurements in the remote estimation of photosynthetic rates. C1 USDA ARS,BELTSVILLE AGR RES CTR,REMOTE SENSING RES LAB,BELTSVILLE,MD 20705. RP CHAPPELLE, EW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,CODE 923,GREENBELT,MD 20771, USA. NR 15 TC 75 Z9 75 U1 1 U2 8 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 JUN PY 1991 VL 36 IS 3 BP 213 EP 218 DI 10.1016/0034-4257(91)90058-E PG 6 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA GA805 UT WOS:A1991GA80500006 ER PT J AU PARMAR, DS AF PARMAR, DS TI A NOVEL TECHNIQUE FOR RESPONSE FUNCTION DETERMINATION OF SHEAR SENSITIVE CHOLESTERIC LIQUID-CRYSTALS FOR BOUNDARY-LAYER INVESTIGATIONS SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID HEAT-TRANSFER MEASUREMENTS; COMPOSITE; ELEMENT AB A description of the design and setup of an experimental technique for measurement of the response function in shear sensitive liquid crystals has been reported. Utilizing the selective reflection characteristics of cholesteric liquid crystals, the method is capable of measuring the delay, rise, and relaxation times in response to a given dynamic shear stress as a function of the wavelength of the incident light. Application of a step input shear stress results in a liquid crystal time response that can be described as consisting of an initial delay, a shear induced helix deformation, and a relaxation to the initial state through diffusion processes. The method has been used for quantitative calibration of a shear sensitive liquid crystal by observing the peak in reflected light intensity, at a given wavelength, as a function of the shear stress. The selective reflection wavelength (lambda-s) decreases linearly with an increase in shear stress (sigma) and has a slope d-lambda-s/d-sigma almost-equal-to 10 nm/psi. The results suggest that in order to obtain quantitative information on the flow parameters over a test surface, three reflection spectra are required: one from a white surface and the other two from the liquid crystal surface one before and one in the presence of shear stress respectively. Free energy calculations for the elastic deformation of the liquid crystal suggest a time response of the liquid crystal for a step input in shear stress. Transport of the broken helix swarms has been suggested as a means for the helix relaxation to zero shear state even in presence of shear. RP PARMAR, DS (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 30 TC 12 Z9 12 U1 1 U2 3 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 JUN PY 1991 VL 62 IS 6 BP 1596 EP 1608 DI 10.1063/1.1142438 PG 13 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA FP312 UT WOS:A1991FP31200037 ER PT J AU TOON, OB TURCO, RP AF TOON, OB TURCO, RP TI POLAR STRATOSPHERIC CLOUDS AND OZONE DEPLETION SO SCIENTIFIC AMERICAN LA English DT Article C1 UNIV CALIF LOS ANGELES,ATMOSPHER SCI,LOS ANGELES,CA 90024. RP TOON, OB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 3 TC 62 Z9 63 U1 0 U2 3 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 SN 0036-8733 J9 SCI AM JI Sci.Am. PD JUN PY 1991 VL 264 IS 6 BP 68 EP 74 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FM502 UT WOS:A1991FM50200013 ER PT J AU OHSAKA, K GATEWOOD, JR TRINH, EH AF OHSAKA, K GATEWOOD, JR TRINH, EH TI AN APPARATUS FOR THE SPECIFIC-HEAT MEASUREMENT OF UNDERCOOLED LIQUIDS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID CONTAINERLESS; METALS RP OHSAKA, K (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 6 Z9 7 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 JUN PY 1991 VL 25 IS 6 BP 1459 EP 1464 DI 10.1016/0956-716X(91)90433-2 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FP093 UT WOS:A1991FP09300042 ER PT J AU DIXON, TH IVINS, ER FRANKLIN, BJ AF DIXON, TH IVINS, ER FRANKLIN, BJ TI TOPOGRAPHIC AND VOLCANIC ASYMMETRY AROUND THE RED-SEA - CONSTRAINTS ON RIFT MODELS - REPLY SO TECTONICS LA English DT Note RP DIXON, TH (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0278-7407 J9 TECTONICS JI Tectonics PD JUN PY 1991 VL 10 IS 3 BP 653 EP 656 DI 10.1029/91TC00056 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FT424 UT WOS:A1991FT42400013 ER PT J AU SCHWENKE, DW MIELKE, SL TRUHLAR, DG AF SCHWENKE, DW MIELKE, SL TRUHLAR, DG TI VARIATIONAL REACTIVE SCATTERING CALCULATIONS - COMPUTATIONAL OPTIMIZATION STRATEGIES SO THEORETICA CHIMICA ACTA LA English DT Article DE CHEMICAL REACTIONS; QUANTUM DYNAMICS; MEMORY MANAGEMENT; FINITE DIFFERENCE BOUNDARY VALUE METHOD; OUTGOING WAVE VARIATIONAL PRINCIPLE ID MECHANICAL REACTION PROBABILITIES; CONTRACTED BASIS FUNCTIONS; POTENTIAL-ENERGY SURFACE; LOG DERIVATIVE VERSION; QUANTUM SCATTERING; CHEMICAL-REACTIONS; CROSS-SECTIONS; PRINCIPLE; MATRIX; CONVERGENCE AB We have developed efficient and accurate techniques for the calculation of quantum mechanical reaction probabilities of atom-diatom exchange reactions in the gas phase, and we have optimized a computer code employing these techniques and applied it sucessfully to several systems. In this paper we consider further strategies for improving the algorithm to allow even more demanding applications. In this context, improvement means that equivalent results can be obtained using fewer computational resources (computer time or storage) or that an equivalent expenditure of resources can yield higher accuracy. The new strategies discussed here lead to improvement in both of these areas. Two areas of special focus in the present paper are (i) the finite difference boundary value method used for calculating distorted wave Green's functions and regular solutions for scattering by the distortion potential and (ii) the choice of the distortion potential itself. Among other results included here is the first application of the outgoing wave or scattered wave variational principle to reactive scattering. C1 UNIV MINNESOTA, DEPT CHEM, CHEM PHYS PROGRAM, MINNEAPOLIS, MN 55455 USA. UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA. RP SCHWENKE, DW (reprint author), NASA, AMES RES CTR, MS 230-3, MOFFETT FIELD, CA 94035 USA. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 43 TC 39 Z9 39 U1 0 U2 1 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD JUN PY 1991 VL 79 IS 3-4 BP 241 EP 269 DI 10.1007/BF01113695 PG 29 WC Chemistry, Physical SC Chemistry GA FT417 UT WOS:A1991FT41700009 ER PT J AU KANE, DL HINZMAN, LD BENSON, CS LISTON, GE AF KANE, DL HINZMAN, LD BENSON, CS LISTON, GE TI SNOW HYDROLOGY OF A HEADWATER ARCTIC BASIN .1. PHYSICAL MEASUREMENTS AND PROCESS STUDIES SO WATER RESOURCES RESEARCH LA English DT Article AB The hydrologic cycle of an arctic watershed is dominated by such physical elements as snow, ice, permafrost, seasonally frozen soils, wide fluctuations in surface energy balance, and phase change of snow and ice to water. Hydrologic data collected over a 5-year period (1985-1989) from an arctic watershed in northern Alaska are presented. Processes related to snow accumulation, redistribution, ablation, evaporation and subsequent snowmelt-generated runoff are discussed. The total water content of the snowpack at the end of winter has comprised between 28 and 40% of the annual precipitation. Redistribution of snow on the ground by the wind is a major factor in increasing the snowmelt runoff. Much of the redistributed snow accumulates in the valley bottom along the stream and also along depressions on the hillslopes. These depressions are small surface drainage channels that are referred to as water tracks. Partitioning of the snowmelt into runoff, evaporation and increased soil water storage in the active layer was carried out on the plot and watershed scale. Over a 5-year period, the volume of snowmelt runoff varied from 50 to 66% of the average watershed snowpack, while evaporation varied from 20 to 34% and soil moisture storage increased between 10 and 19%. Much greater variation in these hydrologic components occurred at the plot scale. C1 UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KANE, DL (reprint author), UNIV ALASKA,INST NO ENGN,WATER RES CTR,FAIRBANKS,AK 99775, USA. RI Hinzman, Larry/B-3309-2013 OI Hinzman, Larry/0000-0002-5878-6814 NR 29 TC 54 Z9 58 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD JUN PY 1991 VL 27 IS 6 BP 1099 EP 1109 DI 10.1029/91WR00262 PG 11 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA FP651 UT WOS:A1991FP65100013 ER PT J AU SCHMALZER, PA HINKLE, CR MAILANDER, JL AF SCHMALZER, PA HINKLE, CR MAILANDER, JL TI CHANGES IN COMMUNITY COMPOSITION AND BIOMASS IN JUNCUS-ROEMERIANUS SCHEELE AND SPARTINA-BAKERI MERR MARSHES ONE YEAR AFTER A FIRE SO WETLANDS LA English DT Article DE BIOMASS; FIRE; JUNCUS-ROEMERIANUS; MARSHES; SPARTINA-BAKERI; SPECIES DIVERSITY; WETLANDS AB Fires occur naturally in many wetlands and are widely used for marsh management. We examined the responses to fire of Juncus roemerianus and Spartina bakeri marshes on Kennedy Space Center, Florida. In each marsh, we determined vegetation cover before burning on 5 permanent 15 m transects in the greater than 0.5 m and less than 0.5 m layers and sampled biomass on 25 plots (0.25 m2). One year after burning, we repeated the sampling. Species composition one year after burning was similar to that before the fire in both Juncus and Spartina marshes. Minor species tended to increase, but this was significant only in the less than 0.5 m layer. In mixed stands, fire appeared to favor Spartina bakeri. Total cover (sum of the cover values for each species) in both marshes reestablished by one year after burning. Biomass did not recover as rapidly. In the Juncus marsh one year after burning, live biomass was 47.2%, standing dead 18.7%, and total biomass 29.3% of that before burning. In the Spartina marsh, biomass one year after burning was live 42.3%, standing dead 21.4%, and total 30.7% of that before burning. Fire increased the ratio of live to dead biomass from 0.82 before burning to 1.85 one year after the fire in the Juncus marsh. In the Spartina marsh, the ratio of live to dead biomass increased from 0.80 before burning to 1.59 one year after burning. RP SCHMALZER, PA (reprint author), NASA,BIOMED OPERAT & RES OFF,BIONET CORP,MAIL CODE BIO-2,KENNEDY SPACE CTR,FL 32899, USA. OI Schmalzer, Paul/0000-0003-2214-0074 NR 0 TC 19 Z9 20 U1 0 U2 1 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 SN 0277-5212 J9 WETLANDS JI Wetlands PD JUN PY 1991 VL 11 IS 1 BP 67 EP 86 PG 20 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA FT723 UT WOS:A1991FT72300005 ER PT J AU BRUNE, WH ANDERSON, JG TOOHEY, DW FAHEY, DW KAWA, SR JONES, RL MCKENNA, DS POOLE, LR AF BRUNE, WH ANDERSON, JG TOOHEY, DW FAHEY, DW KAWA, SR JONES, RL MCKENNA, DS POOLE, LR TI THE POTENTIAL FOR OZONE DEPLETION IN THE ARCTIC POLAR STRATOSPHERE SO SCIENCE LA English DT Article ID TOTAL REACTIVE NITROGEN; ANTARCTIC STRATOSPHERE; INSITU MEASUREMENTS; AIRBORNE LIDAR; JANUARY 1989; WINTER; DENITRIFICATION; CLOUDS; VORTEX; EXPEDITION AB The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear. C1 HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. UK METEOROL OFF,ATMOSPHER CHEM GRP,BRACKNELL RG12 ZSZ,BERKS,ENGLAND. NOAA,AERON LAB,BOULDER,CO 80303. UNIV CAMBRIDGE,DEPT CHEM,CAMBRIDGE CB2 1EW,ENGLAND. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP BRUNE, WH (reprint author), PENN STATE UNIV,DEPT METEOROL,UNIVERSITY PK,PA 16802, USA. RI Toohey, Darin/A-4267-2008; Kawa, Stephan/E-9040-2012; McKenna, Daniel/E-7806-2014; Fahey, David/G-4499-2013 OI Toohey, Darin/0000-0003-2853-1068; McKenna, Daniel/0000-0002-4360-4782; Fahey, David/0000-0003-1720-0634 NR 52 TC 99 Z9 100 U1 1 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 MAY 31 PY 1991 VL 252 IS 5010 BP 1260 EP 1266 DI 10.1126/science.252.5010.1260 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FN857 UT WOS:A1991FN85700028 PM 17842951 ER PT J AU BERATAN, DN BETTS, JN ONUCHIC, JN AF BERATAN, DN BETTS, JN ONUCHIC, JN TI PROTEIN ELECTRON-TRANSFER RATES SET BY THE BRIDGING SECONDARY AND TERTIARY STRUCTURE SO SCIENCE LA English DT Article ID TUNNELING PATHWAYS; CYTOCHROME-C; MOLECULES AB The rate of long-distance electron transfer in proteins rapidly decreases with distance, which is indicative of an electron tunneling process. Calculations predict that the distance dependence of electron transfer in native proteins is controlled by the protein's structural motif. The helix and sheet content of a protein and the tertiary arrangement of these secondary structural units define the distance dependence of electronic coupling in that protein. The calculations use a tunneling pathway model applied previously with success to ruthenated proteins. The analysis ranks the average distance decay constant for electronic coupling in electron transfer proteins and identifies the amino acids that are coupled to the charge localization site more strongly or weakly than average for their distance. C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093. RP BERATAN, DN (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Beratan, David/C-5098-2011 NR 24 TC 589 Z9 595 U1 7 U2 53 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 31 PY 1991 VL 252 IS 5010 BP 1285 EP 1288 DI 10.1126/science.1656523 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FN857 UT WOS:A1991FN85700032 PM 1656523 ER PT J AU BELL, JF CRISP, D LUCEY, PG OZOROSKI, TA SINTON, WM WILLIS, SC CAMPBELL, BA AF BELL, JF CRISP, D LUCEY, PG OZOROSKI, TA SINTON, WM WILLIS, SC CAMPBELL, BA TI SPECTROSCOPIC OBSERVATIONS OF BRIGHT AND DARK EMISSION FEATURES ON THE NIGHT SIDE OF VENUS SO SCIENCE LA English DT Article ID INFRARED ACTIVE GASES; ABSORPTION PROPERTIES; HIGH-PRESSURES; ATMOSPHERE; SPECTRA AB Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 micrometers (mu-m) at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO2, CO, water vapor, and other gases. The bright feature (hot spot) emits more radiation than the dark feature (cold spot) throughout this spectral region, but the largest contrasts occur between 2.21 and 2.32-mu-m, where H2SO4 clouds and a weak CO2 band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34-mu-m, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops. C1 UNIV WASHINGTON,REMOTE SENSING LAB,SEATTLE,WA 98195. CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,PASADENA,CA 91109. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. UNIV HAWAII,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. RP BELL, JF (reprint author), UNIV HAWAII,DIV PLANETARY GEOSCI,HONOLULU,HI 96822, USA. NR 27 TC 24 Z9 24 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 MAY 31 PY 1991 VL 252 IS 5010 BP 1293 EP 1296 DI 10.1126/science.252.5010.1293 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FN857 UT WOS:A1991FN85700035 PM 17842954 ER PT J AU WHITTENBERGER, JD RAY, R JHA, SC DRAPER, S AF WHITTENBERGER, JD RAY, R JHA, SC DRAPER, S TI 1000-1300 K SLOW STRAIN RATE PROPERTIES OF NIAL CONTAINING DISPERSED TIB2 AND HFB2 SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID PLASTIC-FLOW PROPERTIES; HIGH-TEMPERATURE CREEP; ELEVATED-TEMPERATURE; GRAIN-SIZE; PARTICULATE COMPOSITES; 1300-K; 1200-K; DEFORMATION; BEHAVIOR; ALLOYS AB Rapid solidification technology was used to produce NiAl containing dispersions of fine TiB2 or HfB2 particles in an effort to improve the elevated temperature strength of this intermetallic. As-melt spun ribbons of NiAl-2TiB2 were pulverized, and the resulting powders were densified by extrusion at 1420 K with a 16:1 reduction ratio, while NiAl-2HfB2 was initially consolidated by hot isostatic pressing at 1505 K and 207 MPa for 4 h followed by forging 65% at 1535 K. Both materials were compression tested in air between 1000 and 1300 K under constant velocity conditions at nominal strain rates ranging from 2 X 10(-3) to 2 X 10(-7) s-1. NiAl-2HfB2 displayed steady state behavior under all test conditions while NiAl-2TiB2 exhibited diffuse yielding at 1000 K and generally slow, continuous work hardening at the higher temperatures. Analysis of the flow stress-strain rate data indicated that both materials behaved normally, and deformation could be described by temperature compensated power laws. HfB2 was found to be a more effective strengthening addition than TiB2. C1 MARKO MAT INC,N BILLERICA,MA 01882. TEXAS INSTRUMENTS INC,ATTLEBORO,MA 02703. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 32 TC 12 Z9 12 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 MAY 30 PY 1991 VL 138 IS 1 BP 83 EP 93 DI 10.1016/0921-5093(91)90678-G PG 11 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA FU709 UT WOS:A1991FU70900008 ER PT J AU LEE, CH YOON, SU AF LEE, CH YOON, SU TI EXISTENCE AND STABILITY OF GAUGED NONTOPOLOGICAL SOLITONS SO MODERN PHYSICS LETTERS A LA English DT Article AB Classical non-topological soliton configurations are considered in a theory with a local U(1) symmetry. Their existence, stability against dispersion into free particles are studied numerically. As in the case of Friedberg, Lee, and Sirlin with a global U(1) symmetry, also in this case there are two critical charges; Q(c) for the existence and Q(s) for the stability of the non-topological soliton configurations. Our numerical results show that the magnitudes of both Q(c) and Q(s) increase as the magnitude of the gauge coupling constant e is increased with the other parameters kept at fixed values. RP LEE, CH (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE SN 0217-7323 J9 MOD PHYS LETT A JI Mod. Phys. Lett. A PD MAY 30 PY 1991 VL 6 IS 16 BP 1479 EP 1486 DI 10.1142/S0217732391001597 PG 8 WC Physics, Nuclear; Physics, Particles & Fields; Physics, Mathematical SC Physics GA FT872 UT WOS:A1991FT87200006 ER PT J AU DELGENIO, AD LACIS, AA RUEDY, RA AF DELGENIO, AD LACIS, AA RUEDY, RA TI SIMULATIONS OF THE EFFECT OF A WARMER CLIMATE ON ATMOSPHERIC HUMIDITY SO NATURE LA English DT Article ID FEEDBACK; MODELS; CO2 AB THE increases in the concentration of water vapour constitute the single largest positive feedback in models of global climate warming caused by greenhouse gases 1,2. It has been suggested 3-5 that sinking air in the regions surrounding deep cumulus clouds will dry the upper troposphere and eliminate or reverse the direction of water vapour feedback. We have now tested this hypothesis by performing an idealized simulation of climate change with two different versions of a climate model. The versions differ in their parameterizations of moist convection and stratiform clouds, but both incorporate the drying due to subsidence of clear air. Despite increased drying of the upper troposphere by cumulus clouds, upper-level humidity increases in the warmer climate because of enhanced upward moisture transport by the general circulation and increased accumulation of water vapour and ice at cumulus cloud tops. The model behaviour is consistent with recent satellite estimates of the water vapour feedback 6,7. RP DELGENIO, AD (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI Del Genio, Anthony/D-4663-2012; Lacis, Andrew/D-4658-2012 OI Del Genio, Anthony/0000-0001-7450-1359; NR 20 TC 48 Z9 49 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 MAY 30 PY 1991 VL 351 IS 6325 BP 382 EP 385 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FN856 UT WOS:A1991FN85600050 ER PT J AU STECKER, FW DONE, C SALAMON, MH SOMMERS, P AF STECKER, FW DONE, C SALAMON, MH SOMMERS, P TI HIGH-ENERGY NEUTRINOS FROM ACTIVE GALACTIC NUCLEI SO PHYSICAL REVIEW LETTERS LA English DT Article ID TIME VARIABILITY; QUASARS; EMISSION; GALAXIES; DISTRIBUTIONS; CYGNUS-X-3; RADIATION; SPECTRUM; CONTINUA; ORIGIN AB We calculate the spectrum and high-energy nu-background flux from photomeson production in active galactic nuclei (AGN), using the recent UV and x-ray observations to define the photon fields and an accretion-disk shock-acceleration model for producing high-energy particles. Collectively, AGN produce the dominant isotropic nu-background between 10(4) and 10(10) GeV, detectable with current instruments. AGN nu's should produce a sphere of stellar disruption which may explain the "broad-line region" seen in AGN. C1 UNIV UTAH,DEPT PHYS,SALT LAKE CITY,UT 84112. RP STECKER, FW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Stecker, Floyd/D-3169-2012; done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 48 TC 281 Z9 282 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 MAY 27 PY 1991 VL 66 IS 21 BP 2697 EP 2700 DI 10.1103/PhysRevLett.66.2697 PG 4 WC Physics, Multidisciplinary SC Physics GA FN046 UT WOS:A1991FN04600003 ER PT J AU TARG, R KAVAYA, MJ HUFFAKER, RM BOWLES, RL AF TARG, R KAVAYA, MJ HUFFAKER, RM BOWLES, RL TI COHERENT LIDAR AIRBORNE WINDSHEAR SENSOR - PERFORMANCE EVALUATION SO APPLIED OPTICS LA English DT Article DE LIDAR; MICROBURST; WINDSHEAR; COHERENT DETECTION; COMPUTER SIMULATION ID ATMOSPHERIC AEROSOL BACKSCATTER; DOPPLER LIDAR; WIND SHEAR; WAVELENGTHS; EXTINCTION; RAIN; FOG AB National attention has focused on the critical problem of detecting and avoiding windshear since the crash on 2 Aug. 1985 of a Lockheed L-1011 at Dallas/Fort Worth International Airport. As part of the NASA/FAA National Integrated Windshear Program, we have defined a measurable windshear hazard index that can be remotely sensed from an aircraft, to give the pilot information about the wind conditions he will experience at some later time if he continues along the present flight path. A technology analysis and end-to-end performance simulation measuring signal-to-noise ratios and resulting wind velocity errors for competing coherent laser radar (lidar) systems have been carried out. The results show that a Ho:YAG lidar at a wavelength of 2.1-mu-m and a CO2 lidar at 10.6-mu-m can give the pilot information about the line-of-sight component of a windshear threat from his present position to a region extending 2-4 km in front of the aircraft. This constitutes a warning time of 20-40 s, even in conditions of moderately heavy precipitation. Using these results, a Coherent Lidar Airborne Shear Sensor (CLASS) that uses a Q-switched CO2 laser at 10.6-mu-m is being designed and developed for flight evaluation in the fall of 1991. C1 COHERENT TECHNOL INC,BOULDER,CO 80301. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP TARG, R (reprint author), LOCKHEED MISSILES & SPACE CO,3251 HANOVER ST,PALO ALTO,CA 94304, USA. NR 38 TC 63 Z9 66 U1 1 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 1991 VL 30 IS 15 BP 2013 EP 2026 PG 14 WC Optics SC Optics GA FN982 UT WOS:A1991FN98200019 PM 20700170 ER PT J AU DUVALL, TL HARVEY, JW JEFFERIES, SM POMERANTZ, MA AF DUVALL, TL HARVEY, JW JEFFERIES, SM POMERANTZ, MA TI MEASUREMENTS OF HIGH-FREQUENCY SOLAR OSCILLATION MODES SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, OSCILLATIONS; WAVE MOTIONS ID HELIOSEISMOLOGY; ROTATION AB The spatial-temporal spectrum of solar oscillations exhibits modelike structure at frequencies above the nominal photospheric acoustic cutoff of about 5.3 mHz. The line width and frequency of these features are measured as functions of degree from high-quality spectra obtained from observations made at the geographic South Pole. From 5.3 to 6.5 mHz the line widths are relatively constant with a value of about 70-mu-Hz, approximately one-half the frequency difference between modes of the same degree but successive values of radial order number. This width is larger than can be accounted for by simple considerations of the leakage of trapped acoustic waves. The frequencies of the high-frequency modes adhere to a simple dispersion law if one uses a substantially larger effective phase shift than applies at lower frequencies. The frequency variation of this phase shift changes markedly above the acoustic cutoff frequency. C1 NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19711. RP DUVALL, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL SOLAR OBSERV,ASTRON & SOLAR PHYS LAB,POB 26732,TUCSON,AZ 85726, USA. RI Duvall, Thomas/C-9998-2012 NR 28 TC 50 Z9 50 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1991 VL 373 IS 1 BP 308 EP 316 DI 10.1086/170052 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK917 UT WOS:A1991FK91700035 ER PT J AU MOORE, MH TANABE, T NUTH, JA AF MOORE, MH TANABE, T NUTH, JA TI THE SIH VIBRATIONAL STRETCH AS AN INDICATOR OF THE CHEMICAL-STATE OF INTERSTELLAR GRAINS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, GRAINS; LABORATORY SPECTRA; LINE IDENTIFICATIONS; MOLECULAR PROCESSES; STARS, CIRCUMSTELLAR SHELLS ID ABSORPTION FEATURES; MICRON ABSORPTION AB We have measured the infrared spectra of amorphous silicate grains and films formed in a variety of laboratory experiments. We have found that the frequency of the SiH fundamental stretch is extremely sensitive to the chemical environment of the grain in which the silicon is bound and varies from 2270 cm-1 in oxidized grains to 2110 cm-1 in a reducing environment. We propose that features previously observed in W33A could be due to -SiH groups in amorphous silica (2190 cm-1), partially reduced silica (2165 cm-1), silicon nitride (2140 cm-1) or slightly oxidized silicon carbide (approximately 2120 cm-1). We predict that observations at 2270 cm-1 will reveal a feature due to -SiH groups in highly oxidized interstellar and circumstellar grains. Such a feature might also appear in the spectra of comets. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,ASTROCHEM BRANCH,GREENBELT,MD 20771. RP MOORE, MH (reprint author), UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742, USA. RI Nuth, Joseph/E-7085-2012 NR 23 TC 20 Z9 20 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 MAY 20 PY 1991 VL 373 IS 1 BP L31 EP L34 DI 10.1086/186044 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK918 UT WOS:A1991FK91800008 ER PT J AU MORIARTYSCHIEVEN, GH WANNIER, PG AF MORIARTYSCHIEVEN, GH WANNIER, PG TI A 2ND OUTFLOW FROM L1551/IRS-5 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, MOLECULES; NEBULAE, INDIVIDUAL (L1551); NEBULAE, INTERNAL MOTIONS ID HIGH-RESOLUTION IMAGES; BIPOLAR OUTFLOW; MOLECULAR OUTFLOW; L1551; CO; ACCELERATION; OBJECTS; SHELL; WINDS; DISKS AB We report the detection of previously unreported high-velocity emission in the L1551 molecular cloud. This emission may represent high-velocity molecular gas deflected out of the IRS 5 outflow or may indeed represent another independent outflow whose origin is IRS 5 or L1551NE. This region is revealed to be far more complex than previously suspected. RP MORIARTYSCHIEVEN, GH (reprint author), CALTECH,JET PROP LAB,MS 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 20 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 MAY 20 PY 1991 VL 373 IS 1 BP L23 EP L26 DI 10.1086/186042 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK918 UT WOS:A1991FK91800006 ER PT J AU RIDGWAY, WL HARSHVARDHAN ARKING, A AF RIDGWAY, WL HARSHVARDHAN ARKING, A TI COMPUTATION OF ATMOSPHERIC COOLING RATES BY EXACT AND APPROXIMATE METHODS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LINE PARAMETERS COMPILATION; WATER-VAPOR; ABSORPTION; EDITION AB Infrared fluxes and cooling rates for several standard model atmospheres, with and without water vapor, carbon dioxide, and ozone, have been calculated using a line-by-line method at 0.01 cm-1 resolution. This study was conducted as part of the Intercomparison of Radiation Codes Used in Climate Models (ICRCCM) where line-by-line calculations are intended to serve as a benchmark for comparing practical codes used in climate models. The sensitivity of the results to the vertical integration scheme and to the model for water vapor continuum absorption is shown. Comparison with similar calculations performed at NOAA/GFDL shows agreement to within 0.5 W m-2 in fluxes at various levels and 0.05 K d-1 in cooling rates. Comparison with a fast, parameterized radiation code used in climate models reveals a worst case difference, when all gases are included, of 3.7 W m-2 in flux; cooling rate differences are 0.1 K d-1 or less when integrated over a substantial layer with point differences as large as 0.3 K d-1. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. APPL RES CORP, LANDOVER, MD USA. PURDUE UNIV, DEPT EARTH & ATMOSPHER SCI, W LAFAYETTE, IN 47907 USA. NR 20 TC 28 Z9 28 U1 1 U2 3 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 MAY 20 PY 1991 VL 96 IS D5 BP 8969 EP 8984 DI 10.1029/90JD01858 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900005 ER PT J AU CHOU, MD KOUVARIS, L AF CHOU, MD KOUVARIS, L TI CALCULATIONS OF TRANSMISSION FUNCTIONS IN THE INFRARED CO2 AND O3 BANDS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION; PARAMETERIZATION AB An efficient method for computing the transmission function in the 15-mu-m CO2 and the 9.6-mu-m O3 bands is presented. An inhomogeneous atmospheric path is treated as homogeneous by applying simple pressure and temperature scaling approximations. The transmission functions are then derived from small precomputed tables. Because the atmospheric cooling rate is primarily contributed from adjacent layers, the simple scaling approximations can be used to accurately compute transmission functions in both the middle and lower atmosphere. Applying the parameterization to vastly different atmospheric conditions, the difference with line-by-line calculations is small. In the region between 0.01 mbar and the Earth's surface, the cooling rate difference is < 0.3-degrees-C/d in the 15-mu-m CO2 band and < 0.1-degrees-C/d in the 9.6-mu-m O3 band. C1 APPL RES CORP, LANDOVER, MD USA. RP CHOU, MD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. NR 17 TC 32 Z9 34 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 MAY 20 PY 1991 VL 96 IS D5 BP 9003 EP 9012 DI 10.1029/89JD00992 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900007 ER PT J AU KRATZ, DP GAO, BC KIEHL, JT AF KRATZ, DP GAO, BC KIEHL, JT TI A STUDY OF THE RADIATIVE EFFECTS OF THE 9.4-MICRON AND 10.4-MICRON BANDS OF CARBON-DIOXIDE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION; CO2 AB The potential radiative impact of the relatively weak 9.4- and 10.4-mu-m bands of CO2 is investigated. Line-by-line calculations are employed as a standard against which to compare the accuracy of laboratory data, narrow-band models, and broadband models. A comparison of the line-by-line calculations to laboratory data demonstrates that the line-by-line procedure and laboratory data typically yield comparable results; however, there are cases of substantial disagreement between the line-by-line results and the laboratory data. It is observed that the Goody narrow-band model yields band absorptances in good agreement with the reference line-by-line calculations. For application to climate models, new broadband parameterizations, which are consistent with the band intensities found on the 1986 Air Force Geophysics Laboratory HITRAN data base, are presented for the 9.4- and 10.4-mu-m bands of CO2. Clear-sky flux calculations demonstrate that for projected increases of CO2 the impact of the 9.4- and 10.4-mu-m bands is comparable to that attributed to projected increases of tropospheric ozone. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. RP KRATZ, DP (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 613, GREENBELT, MD 20771 USA. NR 20 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1991 VL 96 IS D5 BP 9021 EP 9026 DI 10.1029/89JD01004 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900009 ER PT J AU LACIS, AA OINAS, V AF LACIS, AA OINAS, V TI A DESCRIPTION OF THE CORRELATED KAPPA-DISTRIBUTION METHOD FOR MODELING NONGRAY GASEOUS ABSORPTION, THERMAL EMISSION, AND MULTIPLE-SCATTERING IN VERTICALLY INHOMOGENEOUS ATMOSPHERES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION CALCULATIONS; EARTHS ATMOSPHERE; SOLAR-RADIATION; CLIMATE MODELS; COOLING RATES; WATER-VAPOR; TRACE GASES; PARAMETERIZATION; EFFICIENT AB We describe a radiative transfer method for treating nongray gaseous absorption and thermal emission in vertically inhomogeneous multiple scattering atmospheres. We derive probability density distributions of absorption coefficient strength from line-by-line calculations to construct line-by-line and band model based k distributions. The monotonic ordering of absorption coefficient strengths in these k distributions implicitly preserves the monochromatic structure of the atmosphere at different pressure levels, thus simulating monochromatic spectral integration at a fraction of the line-by-line computing cost. The k distribution approach also permits accurate modeling of overlapping absorption by different atmospheric gases and accurate treatment of nongray absorption in multiple scattering media. To help verify the accuracy of the correlated k distribution method, we compare radiative cooling rates by atmospheric water vapor, CO2, and ozone against line-by-line calculations. The results show the correlated k distribution method is capable of achieving numerical accuracy to within 1% of cooling rates obtained with line-by-line calculations throughout the troposphere and most of the stratosphere. C1 CUNY QUEENSBOROUGH COMMUNITY COLL, NEW YORK, NY 11364 USA. STX INC, NEW YORK, NY 10025 USA. RP LACIS, AA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Lacis, Andrew/D-4658-2012 NR 63 TC 541 Z9 558 U1 1 U2 8 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 MAY 20 PY 1991 VL 96 IS D5 BP 9027 EP 9063 DI 10.1029/90JD01945 PG 37 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900010 ER PT J AU ROSENFIELD, JE AF ROSENFIELD, JE TI A SIMPLE PARAMETERIZATION OF OZONE INFRARED-ABSORPTION FOR ATMOSPHERIC HEATING RATE CALCULATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TWO-DIMENSIONAL MODEL; RADIATIVE-TRANSFER; BAND; STRATOSPHERE; CIRCULATION; TROPOSPHERE; BALANCE AB A simple parameterization of ozone absorption in the 9.6-mu-m region which is suitable for two- and three-dimensional stratospheric and tropospheric models is presented. The band is divided into two parts, a band center region and a band wing region, grouping together regions for which the temperature dependence of absorption is similar. Each of the two regions is modeled with a function having the form of the Goody random model, with pressure and temperature dependent band parameters chosen by empirically fitting line-by-line equivalent widths for pressures between 0.25 and 1000 mbar and ozone absorber amounts between 1.0 x 10(-7) and 1.0 cm atm. The model has been applied to calculations of atmospheric heating rates using an absorber amount weighted mean pressure and temperature along the inhomogeneous paths necessary for flux computations. In the stratosphere, maximum errors in the heating rates relative to line-by-line calculations are 0.1 K/d, or 5% of the peak cooling at the stratopause. In the troposphere the errors are at most 0.005 K/d. RP ROSENFIELD, JE (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 616, GREENBELT, MD 20771 USA. NR 28 TC 23 Z9 23 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 MAY 20 PY 1991 VL 96 IS D5 BP 9065 EP 9074 DI 10.1029/89JD01635 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900011 ER PT J AU FELS, SB KIEHL, JT LACIS, AA SCHWARZKOPF, MD AF FELS, SB KIEHL, JT LACIS, AA SCHWARZKOPF, MD TI INFRARED COOLING RATE CALCULATIONS IN OPERATIONAL GENERAL-CIRCULATION MODELS - COMPARISONS WITH BENCHMARK COMPUTATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LINE PARAMETERS COMPILATION; LAST GLACIAL MAXIMUM; GLOBAL CLIMATE; CARBON-DIOXIDE; CONTINUUM ABSORPTION; CRETACEOUS CLIMATE; DYNAMICAL RESPONSE; RADIATIVE-TRANSFER; MIDDLE ATMOSPHERE; CO2 CONCENTRATION AB As part of the Intercomparison of Radiation Codes in Climate Models (ICRCCM) project, careful comparisons of the performance of a large number of radiation codes were carried out, and the results compared with those of benchmark calculations. In this paper, we document the performance of a number of parameterized models which have been heavily used in climate and numerical prediction research at three institutions: Geophysical Fluid Dynamics Laboratory (GFDL), National Center for Atmospheric Research (NCAR), and Goddard Institute for Space Studies (GISS). C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. NATL CTR ATMOSPHER RES, CLIMATE MODELING SECT, BOULDER, CO 80307 USA. RP FELS, SB (reprint author), PRINCETON UNIV, NOAA, GEOPHYS FLUID DYNAM LAB, POB 308, PRINCETON, NJ 08542 USA. RI Lacis, Andrew/D-4658-2012 NR 68 TC 14 Z9 14 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 MAY 20 PY 1991 VL 96 IS D5 BP 9105 EP 9120 DI 10.1029/91JD00516 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900014 ER PT J AU WU, MLC CHANG, LA AF WU, MLC CHANG, LA TI DIFFERENCES IN GLOBAL DATA SETS OF ATMOSPHERIC AND SURFACE PARAMETERS AND THEIR IMPACT ON OUTGOING LONGWAVE RADIATION AND SURFACE DOWNWARD FLUX CALCULATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SATELLITE; SOUNDINGS AB The effect of clouds on the computation of longwave radiation budget parameters is studied using two sets of cloud fields that are obtained from two different satellite systems using two different retrieval schemes: the High Resolution Infrared Sounder 2 (HIRS2)/Microwave Sounding Unit (MSU) retrievals at Goddard Laboratory for Atmospheres (GLA) and the International Satellite Cloud Climatology Project (ISCCP) products at Goddard Institute for Space Studies. The 60% global mean coverage from the ISCCP-produced cloud amount is much larger than the 43% global mean coverage from the HIRS2-retrieved cloud amount. Despite this fact, the ISCCP-derived outgoing longwave radiation (OLR) is very close to the HIRS2-derived OLR; the global mean OLR difference between the two data sources is -2.6 W m-2, with a standard deviation of 7 W m-2. The small difference is due to the higher cloud-top pressure obtained in the ISCCP data, which tends to counterbalance the differences in coverage between the ISCCP and HIRS2 data sets. However, the produced surface downward flux using the ISCCP-derived cloud fields is much larger than that produced from HIRS2 (the global mean difference is around 11.7 W m-2, with a standard deviation of 13 W m-2), reflecting the differences in cloud coverage of the two data sets. The effect of temperature-humidity fields on the computation of longwave radiation budget parameters is studied using five sets of temperature-humidity fields produced at different agencies which use different retrieval systems/asimilation systems (HIRS2 retrievals at GLA, TIROS Operational Vertical Sounder retrievals at the National Environmental Satellite Data Information Service, European Centre for Medium-range Weather Forecasts assimilation, National Meteorological Center assimilation, and GLA assimilation). Despite all differences found in the geophysical parameters, the derived OLR fields are close to each other. The global mean differences among these five OLRs vary from 0.28 to 4.4 W m-2 with a standard deviation ranging from 4.2 to 7 W m-2. However, large differences are found in the computation of surface downward flux. The global mean differences vary from 3.5 to 19.4 W m-2, with standard deviations ranging from 12.3 to 20.6 W m-2. Most discrepancies in the OLR fields using different cloud fields and geophysical parameters are less than 10 W m-2, which is within the accuracy of current satellite techniques. The discrepancies in the surface downward flux are much larger than 10 W m-2. C1 CENT FED SERV STAFF, ROCKVILLE, MD USA. RP WU, MLC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 911, GREENBELT, MD 20771 USA. NR 13 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 MAY 20 PY 1991 VL 96 IS D5 BP 9227 EP 9262 DI 10.1029/91JD00014 PG 36 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900022 ER PT J AU PARKER, JW BOWHILL, SA AF PARKER, JW BOWHILL, SA TI MESOSPHERIC KHI SIGNATURES IN RECONSTRUCTED BROAD-BAND ROCKET PROBE DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID VHF RADAR OBSERVATIONS; GRAVITY-WAVE; TURBULENCE; DYNAMICS AB In an accepted method of measuring D region electron density with a rocket-borne DC-mode Langmuir probe, the resulting fine-structure signal is modified by a high-pass filter. While this form of data has been successfully used for power spectral analysis, it fails to reveal important spatial domain features without further processing. We demonstrate that the broadband signal can be recovered by use of a digital filter that corrects for the on-board high-pass filter effects. The D region broadband structure so recovered for a daytime equatorial flight shows variations in electron density consistent with a model of Kelvin-Helmholtz billows, and not consistent with inertial range turbulence. The isolated regions of irregularity are approximately 100m thick near an altitude of 75km, imbedded in a region with a staircase-structure electron density profile with approximately 200-m steps. We show suggestive similarities to a numerical model of KHI and to undersea observations of KHI-caused microstructure. C1 UNIV LOWELL, DEPT ELECT ENGN, LOWELL, MA 01854 USA. RP PARKER, JW (reprint author), CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 24 TC 0 Z9 0 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 MAY 20 PY 1991 VL 96 IS D5 BP 9285 EP 9294 DI 10.1029/91JD00416 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900025 ER PT J AU NATARAJAN, M CALLIS, LB AF NATARAJAN, M CALLIS, LB TI STRATOSPHERIC PHOTOCHEMICAL STUDIES WITH ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY (ATMOS) MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONCENTRATION PROFILES; OZONE PHOTOCHEMISTRY; DIURNAL-VARIATION; BRANCHING RATIO; NIMBUS-7 DATA; SPACELAB-3; N2O5; CLO; INSTRUMENT; CHEMISTRY AB The photochemical partitioning of stratospheric odd nitrogen and odd chlorine is examined using diurnal model calculations and data from the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment. This experiment, conducted during April-May 1985, used a solar occultation technique to obtain vertical profiles of temperatures and various other trace constituents at 30-degrees-N and 48-degrees-S latitudes. The knowledge of total odd nitrogen and odd chlorine levels is a major advantage provided by this data set. We have conducted model calculations for different altitudes at 30-degrees-N to evaluate photochemical parameters of interest. Calculated NO2 and NO profiles at sunset are compared with the ATMOS observations. The calculated ratio NO2/NO at sunset is smaller than the observed value by about 27% at 40 km. This difference could be explained by uncertainties in the data and model parameters. The ATMOS data set confirms the presence of N2O5 in the stratosphere; however, the observed mixing ratios at sunset are more than a factor of 2 smaller than the calculated values. We have used recent information on the sticking coefficient for N2O5 on sulfuric acid aerosol surfaces and background aerosol surface area density distribution to estimate the lifetime of N2O5 against removal by heterogeneous reaction. It is shown that the conversion of N2O5 into HNO3 could take place in the presence of aerosol surface rapidly enough to affect the N2O5 mixing ratio below 30 km. The inclusion of the heterogeneous reaction brings the calculated N2O5 profile below 30 km into better agreement with the ATMOS data. The present calculations give lower HCl mixing ratios compared to the ATMOS data in the 30- to 43-km region. We have examined the effects of a secondary path for the reaction OH + ClO, leading to the production of HCl. With a branching ratio of 8% for this path we find that the discrepancy between the calculated and measured HCl is essentially removed. This modification reduces the chlorine-catalyzed destruction of odd oxygen and has the potential to significantly improve agreement between measured and modeled O3 in the middle stratosphere. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP NATARAJAN, M (reprint author), ST SYST CORP, 28 RES DR, HAMPTON, VA 23666 USA. NR 37 TC 34 Z9 34 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 MAY 20 PY 1991 VL 96 IS D5 BP 9361 EP 9370 DI 10.1029/91JD00290 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900032 ER PT J AU ZAWODNY, JM MCCORMICK, MP AF ZAWODNY, JM MCCORMICK, MP TI STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II MEASUREMENTS OF THE QUASI-BIENNIAL OSCILLATIONS IN OZONE AND NITROGEN-DIOXIDE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DIMENSIONAL MODEL; CYCLE AB The first measurements ever to show a quasi-biennial oscillation (QBO) in NO2 have been made by the Stratospheric Aerosol and Gas Experiment II (SAGE II) and are presented in this work along with observations of the well-known QBO in stratospheric ozone. The SAGE II instrument was launched aboard the Earth Radiation Budget satellite near the end of 1984. Measurements of ozone and nitrogen dioxide through early 1990 are analyzed for the presence of a quasi-biennial oscillation. The measurements show the global extent of both the O3 and NO2 QBO in the 25- to 40-km region of the stratosphere. The SAGE II QBO results for ozone compare favorably to theory and previous measurements. The QBO in NO2 is found to be consistent with the vertical and horizontal transport of NO(y). Both species exhibit a QBO at extratropical latitudes consistent with strong meridional transport into the winter hemisphere. RP ZAWODNY, JM (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, AEROSOL RES BRANCH, MAIL STOP 475, HAMPTON, VA 23665 USA. NR 27 TC 92 Z9 94 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 MAY 20 PY 1991 VL 96 IS D5 BP 9371 EP 9377 DI 10.1029/91JD00517 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900033 ER PT J AU RINSLAND, CP ZANDER, R DEMOULIN, P AF RINSLAND, CP ZANDER, R DEMOULIN, P TI GROUND-BASED INFRARED MEASUREMENTS OF HNO3 TOTAL COLUMN ABUNDANCES - LONG-TERM TREND AND VARIABILITY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC TRACE GASES; DIODE-LASER SPECTROMETER; BALLOON-BORNE; SOLAR SPECTRA; SPECTROSCOPIC MEASUREMENTS; AIRBORNE MEASUREMENTS; LATITUDINAL VARIATION; SECULAR INCREASE; CONSTITUENTS; HCL AB The long-term trend and variability of the total column amount of atmospheric nitric acid (HNO3) have been investigated based on time series of infrared solar absorption spectra recorded at two remote high-altitude sites, the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (altitude 3.6 km, latitude 46.5-degrees-N, longitude 8.0-degrees-E) and the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.1 km, latitude 31.9-degrees-N, longitude 111.6-degrees-W), southwest of Tucson, Arizona. The HNO3 nu-5 band Q branch at 879.1 cm-1 and three P branch manifolds near 869 cm-1 were analyzed using a nonlinear least squares spectral fitting technique and a consistent set of spectroscopic line parameters. The ISSJ measurements evaluated in the present work consist of two solar spectra recorded with a grating spectrometer in June 1951 and a set of observations obtained with a high-resolution Fourier transform spectrometer between June 1986 and June 1990. The modern ISSJ measurements show a approximately 20% peak-to-peak amplitude seasonal cycle with a winter maximum superimposed on significant variability and a summer minimum; the June results from 1986 to 1990 are both higher and lower than the two retrieved June 1951 HNO3 total column amounts. The fitted trend, (-0.16 +/- 0.50)% yr-1, 2-sigma, indicates that there has been no detectable change in the HNO3 total column over the last 4 decades. The Kitt Peak measurements, recorded with a high-resolution Fourier transform spectrometer between December 1980 and June 1990, also show marked variability in the HNO3 total column, but in contrast to the ISSJ measurements, no obvious seasonal cycle is observed. The deduced trend in the total column above Kitt Peak, (-0.8 +/- 1.6)% yr-1, 2-sigma, is consistent with the ISSJ time series of measurements, in that no significant HNO3 long-term trend has been found. The sets of measurements from the two sites are compared with each other and with previously published results, with emphasis on the reported variability of HNO3 and the changes in the HNO3 total column with season and latitude. C1 STATE UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. RP RINSLAND, CP (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL CODE 401A, HAMPTON, VA 23665 USA. NR 63 TC 46 Z9 46 U1 0 U2 3 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 MAY 20 PY 1991 VL 96 IS D5 BP 9379 EP 9389 DI 10.1029/91JD00609 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FN179 UT WOS:A1991FN17900034 ER PT J AU MCCAMMON, D CUI, W JUDA, M PLUCINSKY, P ZHANG, J KELLEY, RL HOLT, SS MADEJSKI, GM MOSELEY, SH SZYMKOWIAK, AE AF MCCAMMON, D CUI, W JUDA, M PLUCINSKY, P ZHANG, J KELLEY, RL HOLT, SS MADEJSKI, GM MOSELEY, SH SZYMKOWIAK, AE TI CRYOGENIC MICROCALORIMETERS FOR HIGH-RESOLUTION SPECTROSCOPY - CURRENT STATUS AND FUTURE-PROSPECTS SO NUCLEAR PHYSICS A LA English DT Article; Proceedings Paper CT 12TH INTERNATIONAL CONF ON PARTICLES AND NUCLEI ( PANIC XII ) CY JUN 25-29, 1990 CL MIT, CAMBRIDGE, MA SP ARGONNE NATL LAB, BROOKHAVEN NATL LAB, LAWRENCE BERKELEY LAB, LOS ALAMOS NATL LAB, OAK RIDGE NATL LAB HO MIT AB Small thermal calorimeters operated at temperatures below 1 K can detect single photon or particle events that deposit only a few eV in the device. Their energy resolution for soft X-rays is potentially better than 1 eV FWHM, maintaining the high efficiency and large angular acceptance of a Si(Li) solid state detector with a factor of about 100 improvement in resolution. The best performance obtained so far is 7.3 eV FWHM for 6 keV X-rays with a 1/4 mm x 1 mm device operated at 60 mK. Other unique properties of microcalorimetry include sensitivity to non-ionizing events and a high tolerance for the inclusion of many source materials within the detector. We discuss fundamental factors influencing resolution, limitations of the current approach, applicability considerations, and possible routes for future improvements. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MCCAMMON, D (reprint author), UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706, USA. RI Kelley, Richard/K-4474-2012 NR 11 TC 18 Z9 18 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9474 J9 NUCL PHYS A JI Nucl. Phys. A PD MAY 20 PY 1991 VL 527 BP C821 EP C824 PG 4 WC Physics, Nuclear SC Physics GA FQ927 UT WOS:A1991FQ92700104 ER PT J AU KILLEN, RM POTTER, AE MORGAN, TH AF KILLEN, RM POTTER, AE MORGAN, TH TI DETECTING POTASSIUM ON MERCURY SO SCIENCE LA English DT Article ID ATMOSPHERE; SODIUM C1 NASA,JOHNSON SPACE FLIGHT CTR,HOUSTON,TX 77058. NASA,WASHINGTON,DC 20546. RP KILLEN, RM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 6932,GREENBELT,MD 20771, USA. RI Morgan, Thomas/I-5943-2013 NR 6 TC 7 Z9 7 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 MAY 17 PY 1991 VL 252 IS 5008 BP 974 EP 975 DI 10.1126/science.252.5008.974 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FM040 UT WOS:A1991FM04000039 PM 17843230 ER PT J AU SPRAGUE, AL KOZLOWSKI, RWH HUNTEN, DM AF SPRAGUE, AL KOZLOWSKI, RWH HUNTEN, DM TI DETECTING POTASSIUM ON MERCURY - REPLY SO SCIENCE LA English DT Article C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP SPRAGUE, AL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94053, USA. NR 4 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 MAY 17 PY 1991 VL 252 IS 5008 BP 975 EP 975 DI 10.1126/science.252.5008.975 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FM040 UT WOS:A1991FM04000040 PM 17843231 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H AF BAUSCHLICHER, CW PARTRIDGE, H TI A DETERMINATION OF MG+-LIGAND BINDING-ENERGIES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; 2ND-ROW ATOMS; POSITIVE-IONS; CONTRACTION AB Theoretical calculations employing large basis sets and including correlation are carried out for Mg+ with methanol, water, and formaldehyde. For Mg+ with ethanol and acetaldehyde the trends in the binding energies are studied at the self-consistent-field level. Our predictions for the binding energy of Mg+ to methanol and water of 41 +/- 5 and 36 +/- 5 kcal/mol, respectively, are much less than the experimental upper bounds, of 61 +/- 5 and 60 +/- 5 kcal/mol, determined by using photodissociation techniques. The theoretical results are inconsistent with the onset of Mg+ production observed in the photodissociation experiments, as the smallest absorptions are calculated at about 80 kcal/mol for both Mg+-CH3OH and Mg+-H2O, and these transitions are to bound excited states. The binding energy for Mg+ with formaldehyde is predicted to be similar to Mg+-H2O. The relative binding energies are in reasonable agreement with experiment. The binding energy of a second water molecule to Mg+ is predicted to be similar to the first. This suggests that the reduced reaction rate observed for the second ligand is not a consequence of a significantly smaller binding energy, at least for the smaller ligands such as those considered in this work. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 20 TC 88 Z9 88 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 MAY 16 PY 1991 VL 95 IS 10 BP 3946 EP 3950 DI 10.1021/j100163a011 PG 5 WC Chemistry, Physical SC Chemistry GA FM513 UT WOS:A1991FM51300011 ER PT J AU SELZER, RH DUBOISBLOWERS, L DARNALL, CJ AZEN, SP BLANKENHORN, DH AF SELZER, RH DUBOISBLOWERS, L DARNALL, CJ AZEN, SP BLANKENHORN, DH TI FAT AND CHOLESTEROL INTAKE OF ATTENDEES AT 2 NATIONAL USA CARDIOVASCULAR ANNUAL-MEETINGS SO AMERICAN JOURNAL OF CARDIOLOGY LA English DT Article ID DENSITY-LIPOPROTEIN CHOLESTEROL; CALORIC REQUIREMENTS; BLOOD-PRESSURE; DIET; REAPPRAISAL; SYSTEM AB Using a 1-page bar-coded food frequency questionnaire, the food habits of 996 adults who participated in diet screening at the annual meetings of the American Heart Association (1989) and the American College of Cardiology (1990) were analyzed for sex, age and regional differences. Estimated nutrient intakes were also compared with those from the Department of Agriculture's 1985 and 1986 Continuing Survey of Food Intake of Individuals. The average diet reported in this study satisfied National Cholesterol Education Program guidelines for cholesterol intake, but was higher than that recommended for total and saturated fats. In addition, dietary fat intake was influenced by sex, age and geographic region. Reduction in total and saturated fat intake was confined to men > 35 years of age; intake of these nutrients was highest among young, Midwestern women. These results suggest the need for diet intervention programs, targeted specifically to young adults with additional consideration given to regional variation. Repeated surveys of cardiac care givers might be used as an early indicator of the nationwide effectiveness of dietary intervention programs. C1 UNIV SO CALIF,ATHEROSCLEROSIS RES INST,LOS ANGELES,CA 90089. UNIV SO CALIF,DEPT MED,LOS ANGELES,CA 90089. UNIV SO CALIF,DEPT PREVENT MED,LOS ANGELES,CA 90089. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 18 TC 1 Z9 1 U1 0 U2 0 PU EXCERPTA MEDICA INC PI NEW YORK PA 245 WEST 17TH STREET, NEW YORK, NY 10011 SN 0002-9149 J9 AM J CARDIOL JI Am. J. Cardiol. PD MAY 15 PY 1991 VL 67 IS 13 BP 1090 EP 1096 DI 10.1016/0002-9149(91)90871-H PG 7 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA FL100 UT WOS:A1991FL10000010 PM 2024599 ER PT J AU LANGHOFF, SR PARTRIDGE, H BAUSCHLICHER, CW AF LANGHOFF, SR PARTRIDGE, H BAUSCHLICHER, CW TI THEORETICAL-STUDY OF THE SPECTROSCOPY OF THE ALKALI OXIDES LIO, NAO, AND KO SO CHEMICAL PHYSICS LA English DT Article ID GTO BASIS-SETS; 2ND-ROW ATOMS; SPECTRA; STATES; EXPLANATION; MONOXIDES; 1ST-ROW; SYSTEM AB Theoretical calculations show that only three of the eleven doublet electronic states of LiO, NaO, and KO dissociating to the three lowest asymptotes are significantly bound. The only bound-bound transitions that occur in the visible and infrared spectral regions are from the C 2-PI state to the lowest two ionic states (2-PI and 2-SIGMA+). The emission is dominated by the C 2-PI-X 2-PI transition, which has a very large transition moment near r(e) (C 2-PI). Although chemiluminescence observed for these alkali oxides has been correctly assigned to this transition, the vibrational assignments are incorrect, as the strongest transitions from the lower vibrational levels of the C 2-PI state are into rather high vibrational levels of the X 2-PI state. The radiative lifetimes for the C 2-PI(upsilon = 0) level are 66.2, 90.7, and 315.5 ns for LiO, NaO, and KO, respectively: the C 2-PI-A 2-SIGMA+ channel contributes less than 1% to the radiative lifetimes. Emission spectra are presented for the C 2-PI-X 2-PI band systems of LiO, NaO, and KO. Except for very high vibrational temperatures, most of the emission occurs in the infrared region. The maxima in the spectra shift to longer wave-lengths for the heavier alkali oxides, paralleling the decrease in the T(e)(C 2-PI) values. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 27 TC 29 Z9 29 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD MAY 15 PY 1991 VL 153 IS 1-2 BP 1 EP 12 DI 10.1016/0301-0104(91)90001-A PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FM943 UT WOS:A1991FM94300001 ER PT J AU CARTWRIGHT, DC HAY, PJ TRAJMAR, S AF CARTWRIGHT, DC HAY, PJ TRAJMAR, S TI ESTIMATION OF THE INTEGRAL CROSS-SECTION FOR DISSOCIATIVE EXCITATION OF F2 BY ELECTRON-IMPACT SO CHEMICAL PHYSICS LA English DT Article ID INCIDENT ENERGIES; STATES; TRANSITIONS; N2; FLUORINE; MOLECULE; H-2 AB Integral cross sections for electron impact dissociation of F2 as a function of incident electron energy are very important for predicting the performance of electron-beam-pumped KrF lasers. Approximate scaling relationships from similar transitions in N2 are combined with the few available electron energy-loss spectra in F2 to obtain an estimate of the direct dissociation cross section of F2 by electron impact from threshold to 100 eV. A conservative estimate of the direct dissociation cross section obtained by this process is very large (1.6 angstrom-2 at 25 eV) and appears to have a large contribution from excitation of perturbed Rydberg states at 12.87 eV. This estimated magnitude and the prediction of F+ and F- fragment production below the F+ ionization threshold (15.7 eV) should be checked experimentally because of the important role these processes play in rare-gas fluoride lasers. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CARTWRIGHT, DC (reprint author), UNIV CALIF LOS ALAMOS SCI LAB,LOS ALAMOS,NM 87545, USA. NR 28 TC 6 Z9 6 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD MAY 15 PY 1991 VL 153 IS 1-2 BP 219 EP 231 DI 10.1016/0301-0104(91)90020-T PG 13 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FM943 UT WOS:A1991FM94300020 ER PT J AU LANGHOFF, SR PARTRIDGE, H BAUSCHLICHER, CW KOMORNICKI, A AF LANGHOFF, SR PARTRIDGE, H BAUSCHLICHER, CW KOMORNICKI, A TI THEORETICAL-STUDY OF THE NO BETA-SYSTEM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID FULL CONFIGURATION-INTERACTION; LIFETIMES; STATES AB Ab initio calculations including high levels of correlation treatment have been performed for the B2-PI-X2-PI-beta system of NO. The calculations are complicated by the fact that the B2-PI state gains considerable Rydberg character in the Franck-Condon region of this transition, as it approaches an avoided crossing with the C2-PI Rydberg state at shorter r values. The calculated lifetimes vary from 2.12 to 1.17-mu-s for v' = 0 to 6, as compared with the recent measurements using laser induced fluorescence that vary from 2.00 to 0.85-mu-s. Nearly exact agreement with the experimental lifetimes can be achieved by shifting the transition moment function to larger r values to simulate a more rapid onset of the Rydbergization of the B2-PI state. The calculated Einstein coefficients for v' = 6 to v" = 0-16 are in overall good agreement with experiment, but systematic differences remain that may be partially attributable to limitations in the calibration of the spectrometer. C1 POLYATOM RES INST,MT VIEW,CA 94043. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 14 TC 19 Z9 19 U1 0 U2 4 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 MAY 15 PY 1991 VL 94 IS 10 BP 6638 EP 6643 DI 10.1063/1.460291 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FL001 UT WOS:A1991FL00100029 ER PT J AU FRIEHE, CA SHAW, WJ ROGERS, DP DAVIDSON, KL LARGE, WG STAGE, SA CRESCENTI, GH KHALSA, SJS GREENHUT, GK LI, F AF FRIEHE, CA SHAW, WJ ROGERS, DP DAVIDSON, KL LARGE, WG STAGE, SA CRESCENTI, GH KHALSA, SJS GREENHUT, GK LI, F TI AIR-SEA FLUXES AND SURFACE-LAYER TURBULENCE AROUND A SEA-SURFACE TEMPERATURE FRONT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID CONVECTIVE BOUNDARY-LAYER; SIMULATIONS; DEPENDENCE; AIRCRAFT; FIELD AB The response of the lower marine atmospheric boundary layer to sharp changes in sea surface temperature was studied in the Frontal Air-Sea Interaction Experiment (FASINEX) with aircraft and ships measuring mean and turbulence quantities, sea surface temperature, and wave state. Changing synoptic weather on 3 successive days provided cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, both wind over cold-to-warm and warm-to-cold surface temperatures occurred. For the cold-to-warm case, the unstable boundary layer was observed to thicken, with increased convective activity on the warm side. For the warm-to-cold case, the surface layer buoyant stability changed from unstable to neutral or slightly stable, and the sea state and turbulence structure in the lower 100 m were immediately altered, with a large decrease in stress and slowing of the wind. Measurements for this case with two aircraft in formation at 30 and 100 m show a slightly increased stress divergence on the cold side. The turbulent velocity variances changed anisotropically across the front: the streamwise variance was practically unchanged, whereas the vertical and cross-stream variances decreased. Model results, consistent with the observations, suggest that an internal boundary layer forms at the sea surface temperature front. The ocean wave, swell, and microwave radar backscatter fields were measured from several aircraft which flew simultaneously with the low-level turbulence aircraft. Significant reductions in backscatter and wave height were observed on the cold side of the front. C1 USN,POSTGRAD SCH,DEPT METEOROL,MONTEREY,CA 93940. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. FLORIDA STATE UNIV,DEPT METEOROL,TALLAHASSEE,FL 32306. WOODS HOLE OCEANOG INST,WOODS HOLE,MA 02543. UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NOAA,ENVIRONM RES LAB,BOULDER,CO 80303. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP FRIEHE, CA (reprint author), UNIV CALIF IRVINE,DEPT MECH ENGN,IRVINE,CA 92717, USA. RI KHalsa, Siri Jodha/A-9338-2009 OI KHalsa, Siri Jodha/0000-0001-9217-5550 NR 33 TC 124 Z9 125 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 1991 VL 96 IS C5 BP 8593 EP 8609 DI 10.1029/90JC02062 PG 17 WC Oceanography SC Oceanography GA FM099 UT WOS:A1991FM09900006 ER PT J AU WADHAMS, P HOLT, B AF WADHAMS, P HOLT, B TI WAVES IN FRAZIL AND PANCAKE ICE AND THEIR DETECTION IN SEASAT SYNTHETIC APERTURE RADAR IMAGERY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEAN SURFACE-WAVES; SAR; SPECTRA; FIELD; WATER AB A theoretical model of waves propagating into an ice cover composed of frazil and pancake ice is developed and compared with measurements of wavelength and direction derived from synthetic aperture radar (SAR) imagery obtained from Seasat in October 1978. The theoretical model is based on the concept that ice of these types, which consists of small crystals or cakes, has only a mass-loading effect on the water surface. We derive the dispersion relation for phase and group velocities, finding that there is an upper frequency limit for propagation into the ice. From the reflection coefficient at the ice edge we derive the wave radiation pressure exerted on the ice, showing that it will cause a slick of frazil ice backed by thicker floes to become more dense or thick with increasing penetration. The implications for radar scattering enabling detection on SAR are that the Bragg resonant wavelength corresponds to waves above the frequency limit for propagation, so that a frazil slick appears dark on an SAR image. When the frazil ice becomes transformed into pancake ice, through slick compression or other means, the raised edges of the pancakes cause the ice to appear bright despite the fact that there are no waves present at the Bragg wavelength. These results are applied to a Seasat SAR image obtained from the Chuckchi Sea. The appearance of the ice in the image corresponds to what we expect for frazil ice gradually transforming itself into pancake ice, backed by thicker floes. We derive directional wave number spectra outside and inside the ice cover by digital Fourier analysis of image subscenes, and we find that the change of wavelength and angle of refraction of the dominant wave entering the ice field are both characteristic of the dispersion relation derived theoretically. Mean ice thicknesses extracted from the theory correspond to thicknesses expected for such slicks. The technique offers a possible means of extracting the thickness of fields of frazil and pancake ice from SAR imagery; this may be of considerable utility when ERS 1 SAR is used to study the advancing winter ice edge in the Antarctic, which consists of vast areas of these ice types. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WADHAMS, P (reprint author), UNIV CAMBRIDGE,SCOTT POLAR RES INST,CAMBRIDGE,ENGLAND. NR 33 TC 43 Z9 43 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 1991 VL 96 IS C5 BP 8835 EP 8852 DI 10.1029/91JC00457 PG 18 WC Oceanography SC Oceanography GA FM099 UT WOS:A1991FM09900023 ER PT J AU HECHT, MH AF HECHT, MH TI TIME-DEPENDENCE OF PHOTOVOLTAIC SHIFTS IN PHOTOELECTRON-SPECTROSCOPY OF SEMICONDUCTORS SO PHYSICAL REVIEW B LA English DT Note ID SCHOTTKY-BARRIER FORMATION; FERMI-LEVEL MOVEMENT; SYNCHROTRON-RADIATION; SURFACE PHOTOVOLTAGE; PHOTOEMISSION; INTERFACES; GAAS(110) AB Photovoltage-induced peaks shifts in photoelectron spectroscopy (PES) were recently shown to be important in studies of semiconductor interface formation [M. H. Hecht, Phys. Rev. B 41, 7918 (1990)]. In that process, the photons used to probe the sample were shown to cause a reduction in surface band bending, hence shifting the spectrum in energy. In this paper it is shown that the time dependence of the charging and discharging process can have an important influence on experimentally observable phenomena. Since the charging process is very fast, the effective photocurrent in a pulsed-synchrotron-radiation experiment may be orders of magnitude higher than previously assumed. Using a simple model of the discharge profile it is shown that the photovoltage persists on a time scale that is macroscopic under typical PES conditions. Finally, a noncontacting method for determining equilibrium surface band bending is proposed. RP HECHT, MH (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 23 Z9 23 U1 0 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD MAY 15 PY 1991 VL 43 IS 14 BP 12102 EP 12105 DI 10.1103/PhysRevB.43.12102 PG 4 WC Physics, Condensed Matter SC Physics GA FM463 UT WOS:A1991FM46300079 ER PT J AU SALOPEK, DS AF SALOPEK, DS TI NONLINEAR SOLUTIONS OF LONG-WAVELENGTH GRAVITATIONAL-RADIATION SO PHYSICAL REVIEW D LA English DT Article ID INFLATIONARY UNIVERSE; DENSITY; GRAVITY AB In a significant improvement over homogeneous minisuperspace models models, it is shown that the classical nonlinear evolution of inhomogeneous scalar fields and the metric is tractable when the wavelength of the fluctuations is larger than the Hubble radius. Neglecting second-order spatial gradients, one can solve the energy constraint as well as the evolution equations by invoking a transformation to new canonical variables. The Hamilton-Jacobi equation is separable and complete solutions are given for gravitational radiation and multiple scalar fields interacting through an exponential potential. Although the time parameter is arbitrary, the natural choice is the determinant of the three-metric. The momentum constraint may be simply expressed in terms of the new canonical variables which define the spatial coordinates. The long-wavelength analysis is essential for a proper formulation of stochastic inflation which enables one to model non-Gaussian primordial fluctuations for structure formation. RP SALOPEK, DS (reprint author), NASA,FERMILAB ASTROPHYS CTR,POB 500,MS-209,BATAVIA,IL 60510, USA. NR 30 TC 32 Z9 32 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 MAY 15 PY 1991 VL 43 IS 10 BP 3214 EP 3233 DI 10.1103/PhysRevD.43.3214 PG 20 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA FM345 UT WOS:A1991FM34500014 ER PT J AU WERNET, MP AF WERNET, MP TI 2-DIMENSIONAL PARTICLE DISPLACEMENT TRACKING IN PARTICLE IMAGING VELOCIMETRY SO APPLIED OPTICS LA English DT Article ID ALGORITHM; FLOWS AB A new particle imaging velocimetry data acquisition and analysis system, which is an order of magnitude faster than any previously proposed system, has been constructed and tested. The new particle displacement tracking (PDT) system is an all electronic technique employing a video camera and a large memory buffer frame-grabber board. Using a simple encoding scheme, a time sequence of single exposure images is time coded into a single image and then processed to track particle displacements and determine 2-D velocity vectors. Use of the PDT technique in a counterrotating vortex flow produced over 1100 velocity vectors in 110 s when processed on an 80386 PC. RP WERNET, MP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 9 Z9 9 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 MAY 10 PY 1991 VL 30 IS 14 BP 1839 EP 1846 PG 8 WC Optics SC Optics GA FM764 UT WOS:A1991FM76400011 PM 20700366 ER PT J AU HENRY, JP ARNAUD, KA AF HENRY, JP ARNAUD, KA TI A MEASUREMENT OF THE MASS FLUCTUATION SPECTRUM FROM THE CLUSTER X-RAY TEMPERATURE FUNCTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERING; GALAXIES, X-RAYS ID COLD DARK MATTER; LARGE-SCALE STRUCTURE; RICH CLUSTERS; COMA CLUSTER; GALAXIES; EVOLUTION; UNIVERSE; SAMPLE; COSMOLOGY AB We present a statistically complete sample of galaxy clusters which also has complete X-ray temperature information. Using this sample we derive the cluster bolometric luminosity and temperature functions. The temperature function constrains the shape and amplitude of the mass fluctuation power spectrum. For a power law, i.e., with the fluctuation power spectrum proportional to k(n), we find n = -(1.7(-0.35)+0.65), and an amplitude which implies that the rms value of delta-M/M is 0.59 +/- 0.02 on a scale of 8 h-1 Mpc at the present epoch. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. UNIV MARYLAND, ASTRON PROGRAM, COLLEGE PK, MD 20742 USA. RP UNIV HAWAII, INST ASTRON, 2680 WOODLAWN DR, HONOLULU, HI 96822 USA. NR 31 TC 318 Z9 319 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 MAY 10 PY 1991 VL 372 IS 2 BP 410 EP 418 DI 10.1086/169987 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100005 ER PT J AU FREEDMAN, WL WILSON, CD MADORE, BF AF FREEDMAN, WL WILSON, CD MADORE, BF TI NEW CEPHEID DISTANCES TO NEARBY GALAXIES BASED ON BVRI CCD PHOTOMETRY .2. THE LOCAL GROUP GALAXY M33 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, DISTANCES; GALAXIES, INDIVIDUAL (M33); GALAXIES, LOCAL GROUP; STARS, CEPHEIDS ID TULLY-FISHER RELATION; HUBBLE CONSTANT; EXTINCTION; VIRGO AB A true distance modulus to the nearby spiral galaxy M33 has been determined based on CCD photometry obtained at BVRI wavelengths. M33 is presently one of five nearby galaxies used in the calibration of the infrared Tully-Fisher relation and thereby in the determination of the Hubble constant. Using period-luminosity relations at several wavelengths offers the advantage that the distance moduli derived can be corrected for the effects of interstellar extinction. These data indicate that there is internal reddening affecting the Cepheid photometry in M33 which must be accounted for if a true distance modulus is to be obtained for this galaxy. Adopting a true distance modulus to the LMC of 18.5 mag, the new CCD data yield a true distance to M33 of 24.64 +/- 0.09 mag, corresponding to a linear distance of 840 kpc. A mean value of the total color excess (foreground and internal) for the Cepheids in M33 is estimated to be E(B-V) = 0.10 +/- 0.09 mag, assuming a value for the total mean LMC Cepheid color excess of 0.10 mag. C1 CALTECH,DIV PHYS MATH & ASTRON,ROBINSON LAB,PASADENA,CA 91125. CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,NASA IPAC EXTRAGALACT DATABASE,PASADENA,CA 91109. RP FREEDMAN, WL (reprint author), CARNEGIE INST WASHINGTON OBSERV,813 SANTA BARBARA ST,PASADENA,CA 91101, USA. NR 32 TC 212 Z9 213 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 MAY 10 PY 1991 VL 372 IS 2 BP 455 EP 470 DI 10.1086/169991 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100009 ER PT J AU TINTO, M ARMSTRONG, JW AF TINTO, M ARMSTRONG, JW TI COINCIDENCE PROBABILITIES FOR SPACECRAFT GRAVITATIONAL-WAVE EXPERIMENTS - MASSIVE COALESCING BINARIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GRAVITATION; RELATIVITY; STARS, BINARIES ID INTERFEROMETRIC DETECTORS; RADIATION; SEARCH; TRACKING AB Massive coalescing binary systems are candidate sources of gravitational radiation in the millihertz frequency band accessible to spacecraft Doppler tracking experiments. For part of their radiative lifetimes, the orbits will have circularized and the emitted gravitational wave signal will be sensibly sinusoidal. Near the end of their dynamical evolution, however, the frequency of the wave will increase with time as the system approaches coalescence. Sources in this phase are of particular astronomical interest because of the information that can be derived from measurements of instantaneous amplitude, frequency, and frequency derivative. In this paper we discuss signal processing and detection probability for waves from coalescing binaries in the regime where the signal frequency increases linearly with time, i.e., "chirp" signals. The general Doppler signature of a gravitational wave after dechirping is a triplet of Fourier components having amplitude, frequency, and frequency spacing that depend on wave angle of arrival, Earth spacecraft distance, and rate of change of the gravitational wave frequency. In the practical situation, we find that the frequency spacing of these three components will be small, and that they will be difficult to resolve as individual lines. The three Fourier components superpose within the Fourier resolution set by tracking duration to form a single line in a power spectrum of a dechirped time series. Using known noise statistics, we establish thresholds with given false alarm probabilities for one- and two-spacecraft experiments. Given the threshold, we calculate the detection probability as a function of gravitational wave amplitude for both one- and two-spacecraft experiments, assuming random polarization states and under various assumptions about wave directions. This allows quantitative statements about the detection efficiency of these experiments and the utility of coincidence experiments. In particular, we find that coincidence probabilities for two-spacecraft experiments are insensitive to the angle between the directions to the two spacecraft, indicating that near-optimal experiments can be done without constraints on spacecraft trajectories. RP TINTO, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1991 VL 372 IS 2 BP 545 EP 553 DI 10.1086/169999 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100017 ER PT J AU HALLAM, KL ALTNER, B ENDAL, AS AF HALLAM, KL ALTNER, B ENDAL, AS TI ROTATIONAL MODULATION IN IUE SPECTRA OF COOL DWARF CHROMOSPHERES .1. DATA-ANALYSIS AND PERIOD SEARCH TECHNIQUES SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, CHROMOSPHERES; STARS, LATE-TYPE; STARS, ROTATION; ULTRAVIOLET, SPECTRA ID MAIN-SEQUENCE STARS; MG-II EMISSION; STELLAR ROTATION; K DWARFS; ULTRAVIOLET AB Time-sequenced IUE spectra of a number of bright F-K dwarfs have been used to investigate rotational modulation in several important chromospheric and transition region emission lines. Stellingwerf's phase dispersion minimization (PDM) technique forms the basis of our time series analysis of these sparsely sampled, irregularly spaced observational sequences, which consist of no more than 13 spectra in any one season. In such highly sample-limited time series, the resultant PDM spectrum is greatly complicated by overlapping alias orders which invariably produce strong interference effects, but the deliberately irregular sampling has proven of value in our development of techniques to identify the intrinsic stellar flux modulation period. Two stars are selected to illustrate these new techniques in detail: epsilon Eri, a young, chromospherically active K2 dwarf; and alpha Cen A, an older G2 dwarf with an apparently more quiescent chromosphere. In epsilon Eri, we have found consistently strong indications for a modulation of the UV spectral flux with a period close to 2.8 days from two seasons of observations, with some evidence for persistence of the longitude distribution of active areas over several hundred modulation cycles. This period is 4 times smaller than that reported by the Mount Wilson Ca II monitoring program, and may well be a harmonic of the Mount Wilson period. A somewhat weaker determination is presented for a UV spectral flux modulation period near 29 days in alpha Cen A. C1 APPL RES CORP,LANDOVER,MD 20785. RP HALLAM, KL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 33 TC 24 Z9 24 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 MAY 10 PY 1991 VL 372 IS 2 BP 610 EP 632 DI 10.1086/170005 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100023 ER PT J AU WENTZEL, DG ASCHWANDEN, MJ AF WENTZEL, DG ASCHWANDEN, MJ TI SOLAR AND STELLAR RADIO SPIKES - LIMITS ON THE SATURATION OF THE ELECTRON-CYCLOTRON MASER SO ASTROPHYSICAL JOURNAL LA English DT Article DE MASERS; PLASMAS; STARS, RADIO RADIATION; SUN, RADIO RADIATION ID QUASI-LINEAR DIFFUSION; WAVE ACCELERATION; AD-LEONIS; LOSS-CONE; INSTABILITY; EMISSION; BURSTS; FLARE; RADIATION; STARS AB The solar millisecond radio "spikes" have been explained in terms of X-mode radiation generated by a maser near the electron gyrofrequency, acting on fast coronal electrons with a loss cone. This maser is a phenomenon described by quasi-linear theory. It is sensitive to the small first-relativistic correction to the gyrofrequency. Thus it might be disrupted rather easily by nonlinear effects. We discuss the maximum radiation density that can be reached before the radiation entrains (phase-locks) the electrons and saturates the maser. If the observed durations of solar radio spikes are a measure of the rate of scattering into the loss-cone, then the inferred energy density is at least two orders of magnitude less than the energy density at which entrainment sets in. Also maser emission from auroral kilometric radiation does not reach wave energies critical for electron entrainment. Maser emissions from flare stars, however, show 3-4 orders of magnitude higher radio fluxes and brightness temperatures than for the solar case and are likely to be saturated by entrainment. C1 NASA,GODDARD SPACE FLIGHT CTR,SOLAR PHYS & ASTRON LAB,GREENBELT,MD 20771. RP WENTZEL, DG (reprint author), UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742, USA. NR 19 TC 9 Z9 9 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 MAY 10 PY 1991 VL 372 IS 2 BP 688 EP 693 DI 10.1086/170011 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100029 ER PT J AU SCHATTEN, KH MAYR, HG AF SCHATTEN, KH MAYR, HG TI ON THE CONTRAST OF FACULAR HILLOCKS IN THE INFRARED SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, FACULAE ID SUNSPOTS AB Faculae appear increasingly bright toward the limb of the Sun. Recent observations also have shown that in the infrared these features appear dark at disk center. We demonstrate that our hillock model can describe the essential features of these observations. In light of this model, a simple explanation is given for the contrast behavior of faculae. The observations are discussed in the context of the alternative well model. RP SCHATTEN, KH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,SOLAR RADIAT OFF,GREENBELT,MD 20771, USA. NR 15 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1991 VL 372 IS 2 BP 728 EP 732 DI 10.1086/170016 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK241 UT WOS:A1991FK24100034 ER PT J AU BROOKE, TY TOKUNAGA, AT WEAVER, HA CHIN, G GEBALLE, TR AF BROOKE, TY TOKUNAGA, AT WEAVER, HA CHIN, G GEBALLE, TR TI A SENSITIVE UPPER LIMIT ON THE METHANE ABUNDANCE IN COMET LEVY (1990C) SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS; INFRARED, SPECTRA ID P/HALLEY; HALLEY; WATER AB We conducted a sensitive search for infrared fluorescent emission from CH4 at lambda approximately 3.3-mu-m in comet Levy (1990c). If CH4 is a parent molecule released directly from the nucleus, then the 3 sigma limit on its abundance is CH4/H2O < 0.0031, assuming that the kinetic temperature of the inner coma is approximately 50 K and that the CH4 spin species are equilibrated at a temperature of 50 K or above. This upper limit is similar to the abundance of CH4 in comet Halley estimated from lower resolution infrared spectra (Kawara et al.) and is significantly lower than the abundance derived from a possible detection of CH4 in comet Wilson (Larson et al.). Since CO/H2O approximately 0.03 in comet Levy, we find that CH4/CO less-than-or-similar-to 0.1. This upper limit is not sufficient to discriminate between a solar nebula and an interstellar origin for cometary volatiles. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,INFRARED & RADIO ASTRON BRANCH,GREENBELT,MD 20771. JOINT ASTRON CTR,HILO,HI 96720. RP BROOKE, TY (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. RI Chin, Gordon/E-1520-2012; Weaver, Harold/D-9188-2016 NR 29 TC 10 Z9 10 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 MAY 10 PY 1991 VL 372 IS 2 BP L113 EP L116 DI 10.1086/186036 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK238 UT WOS:A1991FK23800016 ER PT J AU ROSNER, R AN, CH MUSIELAK, ZE MOORE, RL SUESS, ST AF ROSNER, R AN, CH MUSIELAK, ZE MOORE, RL SUESS, ST TI MAGNETIC CONFINEMENT, ALFVEN-WAVE REFLECTION, AND THE ORIGINS OF X-RAY AND MASS-LOSS DIVIDING LINES FOR LATE-TYPE GIANTS AND SUPERGIANTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MAGNETIC FIELDS; STARS, CORONAE; STARS, MASS LOSS; STARS, WINDS; STARS, X-RAYS ID H-R DIAGRAM; OUTER ATMOSPHERES; STARS; EMISSION; CORONA; WINDS AB We discuss a simple qualitative model for the origin of the coronal and mass-loss dividing lines separating late-type giants and supergiants with and without hot, X-ray-emitting corona, and with and without significant mass loss. The basic physical effects we appeal to are the necessity of magnetic confinement for hot coronal material on the surface of such stars-which turns out to imply that any matter in "open" regions must be relatively cool-and the large reflection efficiency for Alfven waves in cool exponential atmospheres. Our model assumes that the magnetic field geometry of these stars changes across the observed "dividing lines" from being mostly closed on the high effective temperature side to being mostly open on the low effective temperature side. C1 UNIV CHICAGO, ENRICO FERMI INST, CHICAGO, IL 60637 USA. APPL RES INC, HUNTSVILLE, AL 35805 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RP UNIV CHICAGO, CTR ASTRON & ASTROPHYS, 5640 ELLIS AVE, CHICAGO, IL 60637 USA. NR 23 TC 37 Z9 37 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 MAY 10 PY 1991 VL 372 IS 2 BP L91 EP L94 DI 10.1086/186031 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK238 UT WOS:A1991FK23800011 ER PT J AU WOLSZCZAN, A CORDES, JM DEWEY, RJ AF WOLSZCZAN, A CORDES, JM DEWEY, RJ TI DISCOVERY OF A YOUNG, 267 MILLISECOND PULSAR IN THE SUPERNOVA REMNANT W44 SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, SUPERNOVA REMNANTS; PULSARS ID TIMING NOISE AB We report the discovery of a 267 ms pulsar, PSR 1853 + 01, in the supernova remnant W44 (G34.7 - 0.4). The pulsar is located south of the center of W44, well within its radio shell and at the southern edge of the X-ray emission region which fills the interior of the remnant. The period derivative P almost-equal-to 208 x 10(-15) s s-1 leads to a characteristic age of approximately 20,000 yr for the pulsar, which agrees well with the estimated age of W44 (greater-than-or-equal-to 10,000 yr). Similarly, the dispersion measure derived distance of the pulsar, approximately 3.2 kpc, is almost identical with the kinematic distance of the remnant, 3.1 kpc. As expected in the case of a young pulsar, PSR 1853 + 01 exhibits large timing activity. These data clearly indicate that the two objects are physically related and form the sixth known pulsar-supernova remnant association. We also discuss the possibility that PSR 1853 + 01 and a nearby older pulsar PSR 1854 + 00 may have a common origin in a binary system disrupted by the explosion that produced W44. C1 CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WOLSZCZAN, A (reprint author), ARECIBO OBSERV,NATL ASTRON & IONOSPHERE CTR,POB 995,ARECIBO,PR 00613, USA. NR 18 TC 66 Z9 66 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 MAY 10 PY 1991 VL 372 IS 2 BP L99 EP L102 DI 10.1086/186033 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FK238 UT WOS:A1991FK23800013 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW TAYLOR, PR AF LANGHOFF, SR BAUSCHLICHER, CW TAYLOR, PR TI THE COMPUTATION OF C-C AND N-N BOND-DISSOCIATION ENERGIES FOR SINGLY, DOUBLY, AND TRIPLY BONDED SYSTEMS SO CHEMICAL PHYSICS LETTERS LA English DT Article ID DIIMIDE; CI(SD) AB The bond dissociation energies (D(e)) of C2H2, C2H4, C2H6, N2, N2H2, and N2H4 are studied at various levels of correlation treatment. The convergence of D(e) with respect to the one-particle basis is studied at the single-reference modified coupled-pair-functional (MCPF) level. At all levels of correlation treatment, the errors in the bond dissociation energies increase with the degree of multiple bond character. The multireference configuration-interaction (MRCI) D(e) values, corrected for an estimate of higher excitations, are in excellent agreement with those determined using the size-extensive averaged-coupled-pair-functional (ACPF) method. We find that the full-valence complete-active-space self-consistent-field (CASSCF)/MRCI calculations are reproduced very well by MRCI calculations based on a CASSCF calculation that includes in the active space only those electrons involved in the C-C or N-N bonds. To achieve chemical accuracy (1 kcal/mol) for the D(e) values of the doubly bonded species C2H4 and N2H2 requires one-particle basis sets including up through h angular momentum functions (l = 5) and a multireference treatment of electron correlation: still higher levels of calculation are required to achieve chemical accuracy for the triply bonded species C2H2 and N2. C1 ELORET INST,PALO ALTO,CA 94303. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 33 Z9 33 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD MAY 10 PY 1991 VL 180 IS 1-2 BP 88 EP 94 DI 10.1016/0009-2614(91)87121-Q PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FQ214 UT WOS:A1991FQ21400016 ER PT J AU SIMONS, RN AF SIMONS, RN TI NEW CHANNELIZED COPLANAR WAVE-GUIDE TO RECTANGULAR WAVE-GUIDE POST AND SLOT COUPLERS SO ELECTRONICS LETTERS LA English DT Article DE WAVE-GUIDES; WAVE-GUIDE COMPONENTS; WAVE-GUIDE COUPLERS AB Two new coplanar waveguide to rectangular waveguide couplers with coupling through a post and a slot are experimentally demonstrated. The couplers operate over the K(u)-band transmission and X-band reception frequencies that are designated for satellite communications. The measured insertion loss and return loss are about 1 dB and 10 dB, respectively, for both couplers. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 2 TC 7 Z9 7 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD MAY 9 PY 1991 VL 27 IS 10 BP 856 EP 858 DI 10.1049/el:19910536 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA FP265 UT WOS:A1991FP26500043 ER PT J AU POPE, KO OCAMPO, AC DULLER, CE AF POPE, KO OCAMPO, AC DULLER, CE TI MEXICAN SITE FOR K/T IMPACT CRATER SO NATURE LA English DT Letter C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP POPE, KO (reprint author), GEO ECO ARC RES,2222 FOOTHILL BLVD,SUITE E-272,LA CANADA,CA 91011, USA. NR 11 TC 69 Z9 69 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 MAY 9 PY 1991 VL 351 IS 6322 BP 105 EP 105 DI 10.1038/351105a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FL035 UT WOS:A1991FL03500031 ER PT J AU LARSSON, A MASERJIAN, J AF LARSSON, A MASERJIAN, J TI OPTICALLY INDUCED ABSORPTION MODULATION IN A PERIODICALLY DELTA-DOPED INGAAS/GAAS MULTIPLE QUANTUM-WELL STRUCTURE SO APPLIED PHYSICS LETTERS LA English DT Article ID GAAS DOPING SUPERLATTICES AB Strong optically induced absorption modulation has been achieved in a periodically delta-doped InGaAs/GaAs multiple quantum well structure. The use of delta-doping has enabled efficient modulation in short-period structures using a low-power semiconductor laser. With an excitation intensity of 100 mW/cm2 we have measured an absolute quantum well absorption change of more than 9000 cm-1 corresponding to a differential absorption change as high as 58% at the excitonic resonance. RP LARSSON, A (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 13 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAY 6 PY 1991 VL 58 IS 18 BP 1946 EP 1948 DI 10.1063/1.105027 PG 3 WC Physics, Applied SC Physics GA FK188 UT WOS:A1991FK18800006 ER PT J AU GORMAN, CB GINSBURG, EJ SAILOR, MJ MOORE, JS JOZEFIAK, TH LEWIS, NS GRUBBS, RH MARDER, SR PERRY, JW AF GORMAN, CB GINSBURG, EJ SAILOR, MJ MOORE, JS JOZEFIAK, TH LEWIS, NS GRUBBS, RH MARDER, SR PERRY, JW TI SUBSTITUTED POLYACETYLENES THROUGH THE RING-OPENING METATHESIS POLYMERIZATION (ROMP) OF SUBSTITUTED CYCLOOCTATETRAENES - A ROUTE INTO SOLUBLE POLYACETYLENE SO SYNTHETIC METALS LA English DT Article; Proceedings Paper CT INTERNATIONAL CONF ON SCIENCE AND TECHNOLOGY OF SYNTHETIC METALS ( ICSM 90 ) CY SEP 02-07, 1990 CL TUBINGEN, FED REP GER ID POLY(3-ALKYLTHIENYLENES); POLYMERS AB Ring-opening metathesis polymerization (ROMP) of substituted cyclooctatetraenes (COT) produces polyacetylenes that are substituted, on the average, every eight carbon atoms. In several cases these polymers are soluble and highly conjugated. The effect of the side group on the optical, electrical and meterials properties of the polymer will be discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP GORMAN, CB (reprint author), CALTECH 1,PASADENA,CA 91125, USA. RI Gorman, Christopher/A-3463-2008; grubbs, robert/D-4293-2009; Perry, Joseph/B-7191-2011 OI Gorman, Christopher/0000-0001-7367-2965; grubbs, robert/0000-0002-0057-7817; Perry, Joseph/0000-0003-1101-7337 NR 15 TC 28 Z9 28 U1 0 U2 6 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6779 J9 SYNTHETIC MET JI Synth. Met. PD MAY 6 PY 1991 VL 41 IS 3 BP 1033 EP 1038 DI 10.1016/0379-6779(91)91550-T PG 6 WC Materials Science, Multidisciplinary; Physics, Condensed Matter; Polymer Science SC Materials Science; Physics; Polymer Science GA FV271 UT WOS:A1991FV27100055 ER PT J AU JUREWICZ, AJG MITTLEFEHLDT, DW JONES, JH AF JUREWICZ, AJG MITTLEFEHLDT, DW JONES, JH TI PARTIAL MELTING OF THE ALLENDE (CV3) METEORITE - IMPLICATIONS FOR ORIGINS OF BASALTIC METEORITES SO SCIENCE LA English DT Article ID UREILITES AB Eucrites and angrites are distinct types of basaltic meteorites whose origins are poorly known. Experiments in which samples of the Allende (CV3) carbonaceous chondrite were partially melted indicate that partial melts can resemble either eucrites or angrites, depending only on the oxygen fugacity (f(O2)). Melts are eucritic if the f(O2) is below that of the iron-wustite buffer or angritic if above the f(O2) of that buffer. With changing pressure, the graphite-oxygen redox reaction can produce oxygen fugacities that are above or below those of the iron-wustite buffer. Therefore, a single, homogeneous, carbonaceous planetoid > 110 kilometers in radius could produce melts of drastically different composition, depending on the depth of melting. C1 NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH SN2,HOUSTON,TX 77058. RP JUREWICZ, AJG (reprint author), LOCKHEED ENGN & SCI CO,MAIL CODE C23,HOUSTON,TX 77058, USA. NR 28 TC 42 Z9 42 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 MAY 3 PY 1991 VL 252 IS 5006 BP 695 EP 698 DI 10.1126/science.252.5006.695 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FK185 UT WOS:A1991FK18500045 PM 17746669 ER PT J AU WILLSON, RC HUDSON, HS AF WILLSON, RC HUDSON, HS TI THE SUNS LUMINOSITY OVER A COMPLETE SOLAR-CYCLE SO NATURE LA English DT Article ID IRRADIANCE AB THE Active Cavity Radiometer Irradiance Monitor (ACRIM I), an instrument carried on NASA's Solar Maximum Mission satellite, measured the Sun's luminosity (total power outflow) from early 1980 to late 1989 1-5. Here we present the first account of the complete ACRIM I data set, and give evidence confirming our previous suggestion that solar luminosity varies with the 11-year solar cycle 6. As previously reported, this slow variation closely follows statistical measures of the distribution of magnetic and photospheric features on the Sun's surface 4-8. But there was an exception to this correlation in the form of a remarkable irradiance excess during 1980, at about the time of the sunspot maximum of solar cycle 21. The linkage, over a whole cycle, of luminosity variation to photospheric activity suggests the existence of an unknown physical mechanism other than the thermal diffusion model that explains luminosity deficits due to sunspots. Luminosity models connecting total irradiance to global indicators of solar activity, such as the equivalent width of the 1,083-nm helium line, are consistent with the gross features of the variability, but fail to account for the 1980 irradiance excess. C1 UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. RP WILLSON, RC (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 232 Z9 232 U1 3 U2 14 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAY 2 PY 1991 VL 351 IS 6321 BP 42 EP 44 DI 10.1038/351042a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FK193 UT WOS:A1991FK19300051 ER PT J AU COHEN, A AF COHEN, A TI THE CASE FOR THE EVOLUTION OF THE SHUTTLE SYSTEM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 40TH CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION, LAUNCH SYSTEMS CY OCT 07-13, 1989 CL MALAGA, SPAIN SP INT ASTRONAUT FEDERAT AB Examining the expendable and reusable space transportation systems currently in use, it appears that the service life of a launch system, with periodic upgrades, can be 30-40 years. It is also evident that both reliability and performance increase with flight experience. With a life expectancy of at least 30 years, the Shuttle system is today only in the first third of its potential service life. This paper addresses the issues of why Shuttle evolution is warranted, how the evolutionary process is managed, and how that process can improve system performance and reduce costs. Specific examples of enhancements currently under consideration are presented and discussed in terms of their relationship to the achievement of greater inherent reliability in the Shuttle system. RP COHEN, A (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAY-JUN PY 1991 VL 25 IS 5-6 BP 301 EP 307 DI 10.1016/0094-5765(91)90084-I PG 7 WC Engineering, Aerospace SC Engineering GA FZ035 UT WOS:A1991FZ03500006 ER PT J AU GUNN, CR AF GUNN, CR TI UNITED-STATES ORBITAL TRANSFER VEHICLE PROGRAMS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 40TH CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION, LAUNCH SYSTEMS CY OCT 07-13, 1989 CL MALAGA, SPAIN SP INT ASTRONAUT FEDERAT AB The United States will rely on five orbital transfer vehicles to carry spacecraft to higher energy orbits than achievable by the Space Shuttle or various Expendable Launch Vehicles (ELV). These vehicles are the Payload Assist Module-Delta (PAM-D), an upgraded version designated PAM-DII, the Inertial Upper Stage (IUS), the Transfer Orbit Stage (TOS), and the Orbital Maneuvering Vehicle (OMV). Development of these vehicles have evolved through contrasting cultures of government and commercial management. The spectrum of their capabilities range from providing spacecraft with only a preprogrammed perigee velocity additions to man-in-the-loop remote controlled spacecraft rendezvous, docking, retrieval and return to a space base; either the Shuttle or the Space Station Freedom. The PAM-D, PAM-DII, and IUS are now nearing maturity. Their characteristics, flight record, costs, and projected future uses are defined. The TOS and OMV are currently in development with first uses scheduled in 1992 and 1993, respectively. The TOS is being commercially developed while the OMV is government developed. The TOS and OMV capabilities, constraints, and costs are reviewed. RP GUNN, CR (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAY-JUN PY 1991 VL 25 IS 5-6 BP 323 EP 330 DI 10.1016/0094-5765(91)90086-K PG 8 WC Engineering, Aerospace SC Engineering GA FZ035 UT WOS:A1991FZ03500008 ER PT J AU ZILLIAC, GG DEGANI, D TOBAK, M AF ZILLIAC, GG DEGANI, D TOBAK, M TI ASYMMETRIC VORTICES ON A SLENDER BODY OF REVOLUTION SO AIAA JOURNAL LA English DT Article ID OGIVE-CYLINDER AB The symmetric and asymmetric leeward-side flowfields on an inclined ogive cylinder have been investigated using a number of experimental techniques. Naturally occurring and perturbed flowfields were studied at a moderate Reynolds number and at many incidence angles. By close examination of the steady side-force behavior at different roll orientations of the tip, it has been established that microvariations in the tip geometry of the model have a large influence on the downstream development of the flowfield. Under certain conditions a bistable flowfield was observed. RP ZILLIAC, GG (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 14 TC 45 Z9 60 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 667 EP 675 DI 10.2514/3.59934 PG 9 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300002 ER PT J AU WALTERS, RW THOMAS, JL SWITZER, GF AF WALTERS, RW THOMAS, JL SWITZER, GF TI ASPECTS AND APPLICATIONS OF PATCHED GRID CALCULATIONS SO AIAA JOURNAL LA English DT Article AB PATCHED grid calculations within the framework of an implicit, flux vector split upwind/relaxation algorithm for the Euler equations are presented. Aspects of computing on patched grids are discussed including the effect of a metric-discontinuous interface on the convergence rate of the algorithm, and the effect of curvature along an interface. Applications to a converging-diverging nozzle including effects of choking and bypass slots in two dimensions are presented. C1 NASA,LANGLEY RES CTR,ANALYT METHODS BRANCH,DIV LOW SPEED AERODYNAM,HAMPTON,VA 23665. RP WALTERS, RW (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT AEROSP & OCEAN ENGN,BLACKSBURG,VA 24061, USA. NR 7 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 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 676 EP 677 DI 10.2514/3.10637 PG 2 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300003 ER PT J AU WOODSON, SH CAMPBELL, JF DEJARNETTE, FR AF WOODSON, SH CAMPBELL, JF DEJARNETTE, FR TI INTERACTIVE 3-DIMENSIONAL BOUNDARY-LAYER METHOD FOR TRANSONIC FLOW OVER SWEPT WINGS SO AIAA JOURNAL LA English DT Article AB A THREE-DIMENSIONAL, laminar and turbulent boundary-layer method has been coupled to the full-potential inviscid code, FL030, through a displacement surface interaction. Results of the present method are compared to those obtained with the integral viscous-inviscid interaction method, TAWFIVE, and with experimental data. C1 N CAROLINA STATE UNIV,MECH & AEROSP ENGN,RALEIGH,NC 27695. RP WOODSON, SH (reprint author), NASA,LANGLEY RES CTR,TRANSON AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 7 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 678 EP 679 DI 10.2514/3.10638 PG 2 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300004 ER PT J AU SWANSON, RC RADESPIEL, R AF SWANSON, RC RADESPIEL, R TI CELL CENTERED AND CELL VERTEX MULTIGRID SCHEMES FOR THE NAVIER-STOKES EQUATIONS SO AIAA JOURNAL LA English DT Article AB Two efficient and robust finite-volume multigrid schemes for solving the Navier-Stokes equations are investigated. These schemes employ either a cell centered or a cell vertex discretization technique. An explicit Runge-Kutta algorithm is used to advance the solution in time. Acceleration techniques are applied to obtain faster steady-state convergence. Accuracy and convergence of the schemes are examined. Computational results for transonic airfoil flows are essentially the same, even for a coarse mesh. Both schemes exhibit very good covergence rates for a broad range of artificial dissipation coefficients. C1 INST DESIGN AERODYNAM,DLR,AEROTHERMODYNAM SECT,BRAUNSCHWEIG,GERMANY. RP SWANSON, RC (reprint author), NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 12 TC 26 Z9 29 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 697 EP 703 DI 10.2514/3.10643 PG 7 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300010 ER PT J AU SARKAR, S LAKSHMANAN, B AF SARKAR, S LAKSHMANAN, B TI APPLICATION OF A REYNOLDS STRESS TURBULENCE MODEL TO THE COMPRESSIBLE SHEAR-LAYER SO AIAA JOURNAL LA English DT Article AB Theoretically based turbulence models have had success in predicting many features of incompressible, free shear layers. However, attempts to extend these models to the high-speed, compressible shear layer have been less effective. In the present work, the compressible shear layer was studied with a second-order turbulence closure, which initially used only variable density extensions of incompressible models for the Reynolds stress transport equation and the dissipation rate transport equation. The quasi-incompressible closure was unsuccessful; the predicted effect of the convective Mach number on the shear-layer growth rate was significantly smaller than that observed in experiments. Having thus confirmed that compressibility effects have to be explicitly considered, a new model for the compressible dissipation was introduced into the closure. This model was based on a low Mach number, asymptotic analysis of the Navier-Stokes equations, and on direct numerical simulations of compressible, isotropic turbulence. The use of the new model for the compressible dissipation led to good agreement of the computed growth rates with the experimental data. Both the computations and the experiments indicate a dramatic reduction in the growth rate when the convective Mach number is increased. Experimental data on the normalized maximum turbulence intensities and shear stress also show a reduction with increasing Mach number. The computed values are in accord with this trend. C1 OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23508. RP SARKAR, S (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,MAIL STOP 132C,HAMPTON,VA 23665, USA. NR 24 TC 55 Z9 59 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 MAY PY 1991 VL 29 IS 5 BP 743 EP 749 DI 10.2514/3.10649 PG 7 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300016 ER PT J AU JEGLEY, DC AF JEGLEY, DC TI STUDY OF THERMAL-EXPANSION-MOLDED, GRAPHITE-EPOXY HAT-STIFFENED SANDWICH PANELS SO AIAA JOURNAL LA English DT Article AB MINIMUM weight configurations for two types of graphite-epoxy, hat-stiffened, compression-loaded panels fabricated by the thermal-expansion-molding (TEM) manufacturing process were evaluated analytically and experimentally. Optimal structurally efficient TEM panels are compared to commericially available aluminum aircraft structures. RP JEGLEY, DC (reprint author), NASA,LANGLEY RES CTR,STRUCT MECH BRANCH,DIV STRUCT MECH,HAMPTON,VA 23665, USA. NR 5 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 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 778 EP 779 DI 10.2514/3.10654 PG 2 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300021 ER PT J AU PATNAIK, SN BERKE, L GALLAGHER, RH AF PATNAIK, SN BERKE, L GALLAGHER, RH TI COMPATIBILITY CONDITIONS OF STRUCTURAL MECHANICS FOR FINITE-ELEMENT ANALYSIS SO AIAA JOURNAL LA English DT Article ID INTEGRATED FORCE METHOD; CONSTRAINTS; BEHAVIOR AB The equilibrium equations and the compatibility conditions are fundamental to the analyses of structures. However, anyone who undertakes even a cursory generic study of the compatibility conditions can discover with little effort that, historically, this facet of structural mechanics has not been adequately researched by the profession. Now the compatibility conditions have been researched and understood to a great extent. For finite element discretizations, the compatibility conditions are banded and can be divided into three distinct categories: 1) the interface compatibility conditions, 2) the cluster, or field, compatibility conditions, and 3) the external compatibility conditions. The generation of the compatibility conditions requires the separating of a local region, next writing the deformation displacement relation for the region, and finally eliminating the displacements from those relations. The procedure to generate all three types of compatibility conditions is presented and illustrated through examples of finite element models. The uniqueness of the compatibility conditions thus generated is shown. The utilization of the compatibility conditions has resulted in the novel integrated force method. The solution that is obtained by the integrated force method converges with a significantly fewer number of elements, compared to the stiffness and the hybrid methods. C1 CLARKSON UNIV,POTSDAM,NY 13676. RP PATNAIK, SN (reprint author), NASA,LEWIS RES CTR,STRUCT MECH,CLEVELAND,OH 44135, USA. NR 25 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 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1991 VL 29 IS 5 BP 820 EP 829 DI 10.2514/3.10662 PG 10 WC Engineering, Aerospace SC Engineering GA FM533 UT WOS:A1991FM53300029 ER PT J AU MARTINEZ, DA VAILAS, AC GRINDELAND, RE AF MARTINEZ, DA VAILAS, AC GRINDELAND, RE TI CORTICAL BONE MATURATION IN YOUNG HYPOPHYSECTOMIZED RATS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE COLLAGEN; CROSS-LINKS; HYDROXYLYSYLPYRIDINOLINE; MINERAL; GROWTH ID GROWTH-HORMONE; CONNECTIVE TISSUES; COLLAGEN TURNOVER; MECHANISM; MATRIX AB Cortical bone growth and maturation were studied in young growing rats (62 days) that were hypophysectomized. After 10 days, femur bones were obtained for morphological and biochemical analysis of the middiaphysis. Hypophysectomy significantly decreased (42%) normal body growth demonstrated by reductions in body weight. Bone morphology data indicate that hypophysectomy significantly inhibits the circumferential growth of the middiaphysis as well as region-specific thickness compared with the control group. The effects of hypophysectomy on cortical bone mineral composition and density were significantly greater in the hypophysectomized rats. Bone density and total mineral density were significantly greater, 17% and 24%, respectively, in the hypophysectomized group compared with control animals. Bone collagen maturation, measured by the amount of the mature collagen cross-link hydroxylysylpyridinoline, in the hypophysectomized animals was significantly greater (130%). Also, collagen concentration and content per unit volume were significantly greater, 24% and 70%, respectively, in the hypopysectomized group. Our findings suggest that "normal" growth and maturation of cortical bone in rapidly growing animals is dependent upon the modulation of pituitary hormones. These data also suggest that an increased rate of mature collagen cross-link formation may be modified by the turnover rate of collagen and other matrix constituents. In addition, hormonal mechanisms associated with a suppression of bone growth may enhance the probability of mature collagen cross-link formation. C1 UNIV WISCONSIN,BIODYNAM LAB,2000 OBSERV DR,GYM UNIT 2,MADISON,WI 53706. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Martinez, Daniel/A-5825-2008 NR 34 TC 15 Z9 15 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 MAY PY 1991 VL 260 IS 5 BP E690 EP E694 PN 1 PG 5 WC Physiology SC Physiology GA FM776 UT WOS:A1991FM77600031 PM 2035625 ER PT J AU ROSS, MD CHEE, O CUTLER, L BLACK, S AF ROSS, MD CHEE, O CUTLER, L BLACK, S TI ULTRASTRUCTURAL AND CYTOCHEMICAL EVIDENCE FOR SINGLE IMPULSE INITIATION ZONES IN VESTIBULAR MACULAR NERVE-FIBERS OF RAT SO ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY LA English DT Article DE HEMINODAL ULTRASTRUCTURE; IMPULSE INITIATION ZONE; NERVE FIBER HETEROGENEITY; VESTIBULAR MACULA ID BURBOT LOTA-LOTA; CATION-BINDING; FERRIC ION; RANVIER; FERROCYANIDE; ORGAN; CELLS; NODES; SITES; FISH AB Cupric ion-ferricyanide labeling methods and related ferrocyanide-stained tissues were used to locate and characterize, at the ultrastructural level, presumptive impulse initiation zones in the three types of vestibular macular nerve fibers. Large-diameter, M-type vestibular nerve fibers terminate in a calyx at the heminode, and labeling is coextensive with the base of the calyx. Intermediate, M/U-type nerve fibers have short, unmyelinated preterminal segments that sometimes bifurcate intramacularly, and small-diameter, U-type nerve fibers have long, unmyelinated preterminal axons and up to three branches. Preterminals of these nerve fibers display ultrastructural heterogeneity that is correlated with labeling patterns for sodium channels and/or associated polyanionic sites. They have a nodelike ultrastructure and label heavily from near the heminode to the base of the macula. Their intramacular branches, less organized ultrastructurally, label only slightly. Results indicate that vestibular nerve fibers have one impulse initiation zone, located near the heminode, that varies in length according to nerve fiber type. Structural heterogeneity may favor impulse conduction in the central direction, and length of the impulse initiation zone could influence nerve discharge patterns. C1 SAN JOSE STATE UNIV,SAN JOSE STATE UNIV FDN,SAN JOSE,CA 95192. RP ROSS, MD (reprint author), NASA,AMES RES CTR,MS 261-2,MOFFETT FIELD,CA 94035, USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU ANNALS PUBL CO PI ST LOUIS PA 4507 LACLEDE AVE, ST LOUIS, MO 63108 SN 0003-4894 J9 ANN OTO RHINOL LARYN JI Ann. Otol. Rhinol. Laryngol. PD MAY PY 1991 VL 100 IS 5 BP 398 EP 406 PN 1 PG 9 WC Otorhinolaryngology SC Otorhinolaryngology GA FK926 UT WOS:A1991FK92600010 PM 1708955 ER PT J AU DALINS, I KARIMI, M ILA, D AF DALINS, I KARIMI, M ILA, D TI VIOLENT OXIDATION OF LITHIUM-CONTAINING ALUMINUM-ALLOYS IN LIQUID-OXYGEN SO APPLIED SURFACE SCIENCE LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL CONF ON SOLID FILMS AND SURFACES CY AUG 13-17, 1990 CL BROWN UNIV, PROVIDENCE, RI SP RHODE ISLAND CTR THIN FILM & INTERFACE RES & IND PARTNERSHIP, STATE RHODE ISLAND, DEPT ECON DEV, TECHNOL COUNCIL RHODE ISLAND HO BROWN UNIV ID SOLIDS; SURFACE; MODEL; ATOMS; H2O AB A strong exothermic and quite well known thermite reaction involving aluminum, oxygen and transition metals (Fe, Cr, Ni, etc.) has apparently been initiated during impact testing of Alcoa aluminum alloy #2090 in liquid oxygen at NASA-MSFC. In some instances, this reaction, essentially an oxidation process, has been so intense that the Inconel 718 cup containing the aluminum alloy disk and associated impacter has melted raising certain safety concerns in the use of this alloy. Reaction products as well as the test specimen surfaces have been studied with surface science techniques like XPS/ESCA, SIMS and AES. Typically, in order to initiate the thermite reaction a temperature of approximately 1000-degrees-C is necessary. The mechanism responsible for this oxidation is of great interest. The analysis of the reaction products together with a theoretical analysis, including digital modeling has been pursued. There is strong evidence that the large relaxation energy of the aluminum oxide coating, formed during the aluminum alloy cleaning process, is causing a highly localized energy release during fracture or lattice deformation which is enhancing the oxidation process to a runaway condition. The presence of alkali atoms (Li) enhances the likelihood and intensity of the oxidation reaction. The details of the surface studies will be discussed. C1 ALABAMA A&M UNIV,NORMAL,AL 35762. RP DALINS, I (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,EH-22,HUNTSVILLE,AL 35812, USA. NR 20 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-4332 J9 APPL SURF SCI JI Appl. Surf. Sci. PD MAY PY 1991 VL 48-9 BP 509 EP 516 DI 10.1016/0169-4332(91)90382-T PG 8 WC Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Chemistry; Materials Science; Physics GA FT442 UT WOS:A1991FT44200084 ER PT J AU COTE, P WELCH, DL MATEO, M FISCHER, P MADORE, BF AF COTE, P WELCH, DL MATEO, M FISCHER, P MADORE, BF TI BAADE-WESSELINK RADII FOR NGC 1866 CEPHEIDS SO ASTRONOMICAL JOURNAL LA English DT Article ID LARGE MAGELLANIC CLOUD; PERIOD SOUTHERN CEPHEIDS; LMC CLUSTER NGC-1866; H-R DIAGRAMS; CLASSICAL CEPHEIDS; VARIABLES; DISTANCE; VELOCITY; PHOTOMETRY; MASSES AB Radial velocities and CCD photometry suitable for a Baade-Wesselink analysis are now available for six short-period Cepheids (HV12198, HV12199, HV12202, HV12203, HV12204, and V4) in the LMC cluster NGC 1866. As a prerequisite for such an analysis, O - C diagrams have been constructed and examined for seven of the NGC 1866 Cepheids (HV12197, HV12198, HV12199, HV12200, HV12202 HV12203, and HV12204), yielding improved periods and estimates of the rate of period change in these coeval variables. One star, HV12198, shows possible evidence for period change, but the phase mismatch due to that change is small enough to have negligible effect on its Baade-Wesselink radius. The computed radii are in good agreement with the Baade-Wesselink, theoretical and cluster/association period-radius relations of Fernie [ApJ, 282, 641 (1984)] and the Galactic relation of Coulson & Caldwell [MNRAS, 240, 285 (1989)]. The Flower [A&A, 54, 31 (1977)] color-effective temperature relation and the Becker et al. (1977) mass-luminosity relation lead to mean masses of 4.9 +/- 0.5M. and 4.6 +/- 0.5 M. for the respective metallicities of (Y,Z) = (0.0273,0.0016) and (0.026,0.02). Pulsation constants are also computed for these stars. C1 MCMASTER UNIV,DEPT PHYS & ASTRON,HAMILTON L8S 4M1,ONTARIO,CANADA. CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. CALTECH,JET PROP LAB,CTR INFRARED PROC ANAL,PASADENA,CA 91125. OI Welch, Doug/0000-0002-2350-0898 NR 66 TC 18 Z9 18 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1991 VL 101 IS 5 BP 1681 EP 1692 DI 10.1086/115797 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH746 UT WOS:A1991FH74600010 ER PT J AU CORCORAN, MF SIAH, MJ GUINAN, EF AF CORCORAN, MF SIAH, MJ GUINAN, EF TI H-BETA PHOTOMETRY OF V1010 OPHIUCHI SO ASTRONOMICAL JOURNAL LA English DT Article ID CONTACT BINARIES AB We present an analysis of previously unpublished intermediate and narrow band H-beta light curves of the short period eclipsing binary V1010 Oph. These light curves are very similar to ones obtained earlier by Leung [AJ, 79, 852 (1974)] and by Guinan [BAAS, 12, 12 (1971)]. We determine the temperature of the primary directly by comparing the UV continuum with Kurucz model atmospheres and solve the broadband lightcurve using the Wilson-Devinney program. Our solution has the primary filling its Roche lobe while the secondary is detached from its lobe. An asymmetry in the light curve in which first quadrature (0.25 P) is brighter than the second quadrature (0.75 P) may be the result of local heating of the inner surface of the secondary by mass transfer from the primary. Our semidetached solution indicates that the system is probably evolved. C1 VILLANOVA UNIV,DEPT PHYS,VILLANOVA,PA 19085. VILLANOVA UNIV,DEPT ASTRON & ASTROPHYS,VILLANOVA,PA 19085. RP CORCORAN, MF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 28 TC 15 Z9 15 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1991 VL 101 IS 5 BP 1828 EP 1834 DI 10.1086/115810 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH746 UT WOS:A1991FH74600023 ER PT J AU YEOMANS, DK AF YEOMANS, DK TI A COMET AMONG THE NEAR-EARTH ASTEROIDS SO ASTRONOMICAL JOURNAL LA English DT Article ID METEORITES AB Using available optical and radar observations, orbital solutions have been computed for 12 near-Earth asteroids identified as possible extinct comets. For 10 of these objects, there is no evidence for the nongravitational effects that might indicate residual outgassing activity. For 1862 Apollo and 1566 Icarus, the inclusion of cometlike nongravitational effects in their equations of motion significantly reduces their RMS residuals and flattens their systematic residual trends. For Icarus in particular, the determined radial nongravitational parameter retains the same value when different datasets are employed and the predictive capability of the orbits is improved. While these results do not prove that 1566 Icarus is a comet masquerading as an asteroid, future apparitions of this object should be monitored for possible cometlike activity. RP YEOMANS, DK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 20 Z9 20 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1991 VL 101 IS 5 BP 1920 EP 1928 DI 10.1086/115817 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH746 UT WOS:A1991FH74600030 ER PT J AU BOUCHET, P PHILLIPS, MM SUNTZEFF, NB GOUIFFES, C HANUSCHIK, RW WOODEN, DH AF BOUCHET, P PHILLIPS, MM SUNTZEFF, NB GOUIFFES, C HANUSCHIK, RW WOODEN, DH TI THE BOLOMETRIC LIGHT-CURVE OF SN-1987-A .2. RESULTS FROM VISIBLE AND INFRARED SPECTROPHOTOMETRY SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INFRARED RADIATION; PHOTOMETRY; SPECTROPHOTOMETRY; SUPERNOVAE AND SUPERNOVA REMNANTS, SN 1987-A ID ULTRAVIOLET OBSERVATIONS; PHOTOMETRY; LMC; SPECTRUM; ATLAS AB We derive the ultraviolet-optical-infrared (uvoir) bolometric luminosity evolution of SN 1987 A for days 14-432 since outburst from the direct integration of optical and infrared spectrophotometry. For a given assumed distance modulus and reddening to SN 1987 A, this method is more accurate than estimates of the uvoir bolometric luminosity based on the integration of broad-band magnitudes. We show that between days 130-300, SN 1987 A declined exponentially with an e-folding time of 109.6 +/- 0.3 days, consistent with the thermalized energy released by the radioactive decay of Co-56. By day 300, the decline rate of the uvoir luminosity had increased significantly, consistent with model predictions of the growing transparency of the hydrogen envelope of SN 1987 A to the Co-56 gamma-rays. C1 NATL OPT ASTRON OBSERV, CERRO TOLOLO INTER AMER OBSERV, LA SERENA, CHILE. RUHR UNIV BOCHUM, INST ASTRON, W-4630 BOCHUM 1, GERMANY. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP BOUCHET, P (reprint author), EUROPEAN SO OBSERV, CASILLA 19001, SANTIAGO 19, CHILE. NR 29 TC 37 Z9 37 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 MAY PY 1991 VL 245 IS 2 BP 490 EP 498 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FQ886 UT WOS:A1991FQ88600015 ER PT J AU LAUREIJS, RJ CLARK, FO PRUSTI, T AF LAUREIJS, RJ CLARK, FO PRUSTI, T TI IRAS DETECTION OF VERY COLD DUST IN THE LYNDS-134 CLOUD COMPLEX SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; INTERSTELLAR, GRAINS; NEBULAE, INDIVIDUAL (LYNDS-134) ID DARK CLOUDS; INFRARED-EMISSION; INTERSTELLAR GRAINS; MOLECULAR-HYDROGEN; THERMAL EMISSION; DENSE CORES; ABSORPTION; GLOBULES; CIRRUS; TEMPERATURE AB We have analyzed IRAS maps at 60 and 100-mu-m of the complex of dark clouds containing L134, L183 and L1780. Regions were found that are bright at 100-mu-m but not detected at 60-mu-m. These regions exhibit high optical opacities and are associated with the dark clouds. The 60-mu-m surface brightness is observed to decline in a narrow transition layer surrounding the cloud centers. In the outer environs the ratio I60/I100 has a nearly constant value of 0.2. The absence of 60-mu-m emission yields an upper limit of 15 K for the temperature of the dust, assuming lambda-1 dust emissivity. We have mapped the 60-mu-m deficient regions using the quantity DELTA-I100 = I100 - I60/Kelvin, where Kelvin is the ratio I60/I100 in the outer diffuse regions. We have found a linear correlation between DELTA-I100 and both (CO)-C-13 column density and blue extinction. The analysis suggests that the diffuse component of the cloud has been subtracted when constructing DELTA-I100, and that DELTA-I100 is tightly correlated with molecular material with densities in excess of n(H-2) = 10(3). We have derived an upper limit for the mass absorption coefficient of dust at 100-mu-m of 4.8 g cm-2. This limit is consistent with earlier determinations. The sudden drop in the 60-mu-m emission can only be explained when assuming a separate grain component at 60-mu-m that undergoes a change in properties in a narrow transition region. We infer that condensation of a thin mantle on the grains in the transition layer can explain the observed infrared properties. C1 GEOPHYS LAB,BEDFORD,MA 01731. LAB SPACE RES,9700 AV GRONINGEN,NETHERLANDS. KAPTEYN ASTRON INST,9700 AV GRONINGEN,NETHERLANDS. RP LAUREIJS, RJ (reprint author), CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109, USA. NR 48 TC 81 Z9 81 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 MAY 1 PY 1991 VL 372 IS 1 BP 185 EP 193 DI 10.1086/169963 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH367 UT WOS:A1991FH36700016 ER PT J AU BUSS, RH TIELENS, AGGM SNOW, TP AF BUSS, RH TIELENS, AGGM SNOW, TP TI THE MIDINFRARED SPECTRUM OF THE CARBON STAR HD-38218 AND ITS POSSIBLE RELATION TO POLYCYCLIC AROMATIC-HYDROCARBONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, MOLECULES; STARS, CARBON; STARS, CIRCUMSTELLAR SHELLS; STARS, INDIVIDUAL (HD-38218) ID CIRCUMSTELLAR ENVELOPES; INTERSTELLAR DUST; EMISSION BANDS; IRAS SOURCES; GRAINS; MOLECULES AB We have studied the mid-infrared spectra of selected carbon giant stars with hot companions in order to search for infrared emission bands from polycyclic aromatic hydrocarbons (PAHs) in the envelopes of the C giants. One C giant with a hot companion, TU Tau = HD 38218, has a strong 8-mu-m emission band reminiscent of the interstellar 7.7 + 8.6-mu-m PAH band. Under the same analysis, similar single C giants do not exhibit this strong 8-mu-m emission feature, so it is likely that the binary A star companion excites the 8-mu-m feature of HD 38218. Another C giant plus hot star binary, CD -26-degrees-2983, lacks the 8-mu-m feature, but because the ultraviolet flux from its companion is probably much weaker than the HD 38218 companion UV flux, we do not detect a similar 8-mu-m emission above the CD -26-degrees-2983 spectral noise. If the 8-mu-m feature in HD 38218 arises from PAHs, they seem to be important constituents of the C giant shell. Moreover, because the circumstellar PAHs appear to absorb both visible and UV light, they might be large compared with some interstellar PAHs, though a quantitative assessment of the sizes and amounts of the circumstellar PAHs is difficult. HD 38218 is the first C giant observed to have strong emission probably from PAHs, yet the grain shell properties of HD 38218 resemble those of other C giants. Hence, other C giant shells are likely to harbor PAHs, as predicted by some models of carbon grain formation in cool star winds. Our probable detection of PAHs around a C giant suggests, then, that circumstellar carbonaceous grains might form from PAHs. C1 UNIV COLORADO,APAS,BOULDER,CO 80309. RP BUSS, RH (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 57 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 MAY 1 PY 1991 VL 372 IS 1 BP 281 EP 290 DI 10.1086/169974 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH367 UT WOS:A1991FH36700027 ER PT J AU NEUGEBAUER, M GOLDSTEIN, R GOLDSTEIN, BE FUSELIER, SA BALSIGER, H IP, WH AF NEUGEBAUER, M GOLDSTEIN, R GOLDSTEIN, BE FUSELIER, SA BALSIGER, H IP, WH TI DENSITIES AND ABUNDANCES OF HOT COMETARY IONS IN THE COMA OF P/HALLEY SO ASTROPHYSICAL JOURNAL LA English DT Article DE ABUNDANCES; COMETS; PLASMAS; SUN, SOLAR WIND ID SOLAR-WIND INTERACTION; INNER COMA; CHARGE-EXCHANGE; HALLEY; GIOTTO; PLASMA; DYNAMICS; VELOCITY; GAS; COMETOPAUSE AB On its flight by P/Halley, the Giotto spacecraft carried a high-energy range spectrometer (HERS) for measuring the properties of cometary ions picked up by the solar wind in the nearly collisionless regions of the coma. Preliminary estimates of the ion densities observed by HERS have now been reevaluated and extended; density profiles along the Giotto trajectory are presented for 13 values of ion mass per charge. Comparison with the physical-chemical model of the interaction of sunlight and the solar wind with the comet by Schmidt et al. reveals that, with the exception of protons and H-2+, all ion densities were at least an order of magnitude higher than predicted. The high ion densities cannot be explained on the basis of compression of the plasma, but require additional or stronger ionization mechanisms. Ratios of the densities of different ion species reveal an overabundance of carbonaceous material and an underabundance of H-2+ compared to the predictions of the Schmidt et al. model. While the densities of solar wind ions (H+ and He++) changed sharply across a magnetic discontinuity located 1.35 x 10(5) km from the comet, this feature, which has been called both the "cometopause" and the "magnetic pileup boundary," was barely distinguishable in the density profiles of hot cometary ions. This result is consistent with the interpretation that the magnetic pileup boundary detected by Giotto was caused by a discontinuity in the solar wind and is not an intrinsic feature of the interaction of the solar wind with an active comet. C1 LOCKHEED PALO ALTO RES LABS,DEPT 9120,PALO ALTO,CA 94304. UNIV BERN,INST PHYS,CH-3012 BERN,SWITZERLAND. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. RP NEUGEBAUER, M (reprint author), CALTECH,JET PROP LAB,MAIL STOP 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 41 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 MAY 1 PY 1991 VL 372 IS 1 BP 291 EP 300 DI 10.1086/169975 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH367 UT WOS:A1991FH36700028 ER PT J AU CHOU, DY LABONTE, BJ BRAUN, DC DUVALL, TL AF CHOU, DY LABONTE, BJ BRAUN, DC DUVALL, TL TI POWER SPECTRA OF SOLAR CONVECTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; SUN, ATMOSPHERIC MOTIONS; SUN, GRANULATION ID CALIBRATION; SUN AB We study the properties of convective motions on the Sun by using Kitt Peak Doppler images. We remove the nonconvective components of the velocity images due to magnetic fields and the p-mode oscillations and obtain power spectra of convection. The power peaks at a scale of about 29,000 km and drops off smoothly with wavenumber. There is no evidence of apparent energy excess at the scale of the mesogranulation proposed by other authors. The power spectra can be expressed by a power law, E(k) varies as k-alpha, where k is the wavenumber and the index-alpha is -0.66 for k < 1.05 rad Mm-1, and -2.67 for k > 1.05 rad Mm-1. By comparing power spectra at different heliocentric angles, we obtain the vertical and horizontal power for each wavenumber, from which we can calculate the vertical and horizontal velocities of the supergranulation. The amplitude of vertical and horizontal velocities of the supergranulation are 0.034 (+/- 0.002) km s-1 and 0.38 (+/- 0.01) km s-1, respectively. The corresponding rms values are 0.024 (+/- 0.002) km s-1 and 0.27 (+/- 0.01) km s-1, respectively. The corresponding rms values are 0.024 (+/- 0.002) km s-1 and 0.27 (+/- 0.01) km s-1. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP CHOU, DY (reprint author), TSING HUA UNIV,DEPT PHYS,HSINCHU 30043,TAIWAN. RI Duvall, Thomas/C-9998-2012 NR 25 TC 35 Z9 36 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 MAY 1 PY 1991 VL 372 IS 1 BP 314 EP 320 DI 10.1086/169977 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH367 UT WOS:A1991FH36700030 ER PT J AU TELESCO, CM KNACKE, RF AF TELESCO, CM KNACKE, RF TI DETECTION OF SILICATES IN THE BETA-PICTORIS DISK SO ASTROPHYSICAL JOURNAL LA English DT Article ID CIRCUMSTELLAR DISK; SPECTROPHOTOMETRY AB We have detected a broad 10-mu-m emission feature within 3" of the star beta Pic which is known to have a circumstellar, possibly protoplanetary, disk. The observations were made using four narrow-band filters (DELTA-lambda approximately-equal-to 1-mu-m) in the MSFC bolometer array at the IRTF. The emission feature closely resembles silicate features observed in comets Halley and Kohoutek and in a variety of Galactic sources. The feature is strong, with the total flux density emitted by dust at 10.3-mu-m being at least twice the estimated continuum at that wavelength, and must be emitted by particles with characteristic radii less than 10-mu-m. C1 SUNY STONY BROOK,DEPT EARTH & SPACE SCI,DIV ASTRON,STONY BROOK,NY 11794. RP TELESCO, CM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,E563,HUNTSVILLE,AL 35812, USA. NR 10 TC 86 Z9 86 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 MAY 1 PY 1991 VL 372 IS 1 BP L29 EP L31 DI 10.1086/186016 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH368 UT WOS:A1991FH36800008 ER PT J AU KOHL, RL CALKINS, DS ROBINSON, RE AF KOHL, RL CALKINS, DS ROBINSON, RE TI CONTROL OF NAUSEA AND AUTONOMIC DYSFUNCTION WITH TERFENADINE, A PERIPHERALLY ACTING ANTIHISTAMINE SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SPACE MOTION SICKNESS; PREVENTION; SUSCEPTIBILITY; MECHANISMS; DRUG AB Terfenadine (Seldane(R)) was administered to 14 male subjects in a randomized, double-blinded, and crossed-over design to assess the efficacy of this peripherally active antihistamine as an anti-motion sickness drug. Terfenadine possesses practically no central side effects. A Staircase Profile Test was administered 4 h following placebo or a single oral dose of terfenadine (300 mg). The study revealed a statistically significant therapeutic effect from terfenadine (p < 0.05). This led us to conclude that because the drug does not or only poorly crosses the blood-brain barrier, a selective peripheral antihistamine (H-1) action may be sufficient in the control of motion sickness induced through cross-coupled accelerative semicircular canal stimulation using a rotating chair. This finding implies that other peripherally acting agents might be found that possess even greater anti-motion sickness efficacy. The present research raises additional questions regarding current theories on the etiology of motion sickness, its associated autonomic system dysfunction, and the validity of assumptions that effective pharmacological agents must act centrally. C1 MERRELL DOW PHARMACEUT INC,MERRELL DOW RES INST,CINCINNATI,OH 45215. RP KOHL, RL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,UNIV SPACE RES ASSOC & KRUG LIFE SCI,HOUSTON,TX 77058, USA. NR 30 TC 8 Z9 8 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 MAY PY 1991 VL 62 IS 5 BP 392 EP 396 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA FJ997 UT WOS:A1991FJ99700002 PM 1675849 ER PT J AU CHOU, SH FERGUSON, MP AF CHOU, SH FERGUSON, MP TI HEAT FLUXES AND ROLL CIRCULATIONS OVER THE WESTERN GULF-STREAM DURING AN INTENSE COLD-AIR OUTBREAK SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID CONVECTIVE BOUNDARY-LAYER; TOP ENTRAINMENT INSTABILITY; TURBULENCE STRUCTURE; FAIR-WEATHER; MOISTURE; BUDGETS; MODEL; STRATOCUMULUS; TEMPERATURE; DYNAMICS AB Turbulence and heat fluxes in the marine atmospheric boundary layer (MABL) for the roll vortex regime, observed during the Genesis of Atlantic Lows Experiment (GALE) over the western Gulf Stream, have been studied. The spectral analysis suggests that cloud streets (roll vortices) are vertically organized convection in the MABL having the same roll scale for both the cloud layer and subcloud layer, and that the roll spacing is about three times the MABL depth. The roll circulations contribute significantly to the sensible (temperature) and latent heat (moisture) fluxes with importance increasing upward. Near the MABL top, these fluxes are primarily due to roll vortices which transfer both sensible heat and moisture upward in the lower half of the convective MABL. Near the MABL top, the roll circulations transfer sensible heat downward and moisture upward in the clear thermal-street region, but roll vortices influenced by evaporative cooling can transfer sensible heat upward and moisture downward in the cloud-street region. Near the cloud-top, the upward buoyancy flux due to evaporative cooling is highly related to the roll circulations near the inversion. For the lower half of the MABL, the normalized temperature flux decreases upward more rapidly than the humidity flux, which is mainly because potential temperature (theta) increases slightly upward while humidity (q) decreases slightly upward above the unstable surface layer. The gradient production (associated with the theta-gradient) is a source for the temperature flux in the unstable surface layer but changes to a sink in the mixed layer, while the gradient production (associated with the q gradient) acts as a source for the humidity flux in both the unstable surface and mixed layers. The results suggest that the entrainment at the MABL top might affect the budgets of temperature and humidity fluxes in the lower MABL, but not in the unstable surface layer. RP CHOU, SH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 45 TC 30 Z9 33 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD MAY PY 1991 VL 55 IS 3 BP 255 EP 281 DI 10.1007/BF00122580 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FQ526 UT WOS:A1991FQ52600003 ER PT J AU VANSNYDER, W AF VANSNYDER, W TI RECYCLING SOFTWARE SO BYTE LA English DT Letter RP VANSNYDER, W (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU BYTE PUBL INC PI PETERBOROUGH PA 70 MAIN ST, PETERBOROUGH, NH 03458 SN 0360-5280 J9 BYTE JI Byte PD MAY PY 1991 VL 16 IS 5 BP 26 EP & PG 0 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA FH593 UT WOS:A1991FH59300014 ER PT J AU SHAKIB, F HUGHES, TJR AF SHAKIB, F HUGHES, TJR TI A NEW FINITE-ELEMENT FORMULATION FOR COMPUTATIONAL FLUID-DYNAMICS .9. FOURIER-ANALYSIS OF SPACE-TIME GALERKIN LEAST-SQUARES ALGORITHMS SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID ADVECTIVE-DIFFUSIVE SYSTEMS; COMPRESSIBLE EULER; EQUATIONS AB A Fourier stability and accuracy analysis of the space-time Galerkin/least-squares method as applied to a time-dependent advective-diffusive model problem is presented. Two time discretizations are studied: a constant-in-time approximation and a linear-in-time approximation. Corresponding space-time predictor multi-corrector algorithms are also derived and studied. The behavior of the space-time algorithms is compared to algorithms based on semidiscrete formulations. C1 STANFORD UNIV,DIV APPL MECH,STANFORD,CA 94305. RP SHAKIB, F (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 83 Z9 83 U1 0 U2 6 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 MAY PY 1991 VL 87 IS 1 BP 35 EP 58 DI 10.1016/0045-7825(91)90145-V PG 24 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA FJ761 UT WOS:A1991FJ76100003 ER PT J AU ZOLENSKY, ME KOEBERL, C AF ZOLENSKY, ME KOEBERL, C TI WHY ARE BLUE ZHAMANSHINITES BLUE - LIQUID IMMISCIBILITY IN AN IMPACT MELT SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Letter ID SYSTEM K2O-AL2O3-FEO-SIO2; K2O-FEO-AL2O3-SIO2; CRATER; ORIGIN; USSR AB We report here a study of the cause of the coloration of blue zhamanshinites, which are glassy impact melt rocks from the Zhamanshin crater in the USSR. We find that the blue color results from Rayleigh scattering from spherical, 100 nm-diameter inclusions of a separate Ca-Fe-Mg-P-rich silicate glass. These observations can best be explained by the operation of liquid immiscibility in the zhamanshinite melt, and suggest that liquid immiscibility may have a more general role in impactite evolution. C1 UNIV VIENNA,INST GEOCHEM,A-1010 VIENNA,AUSTRIA. RP ZOLENSKY, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058, USA. NR 25 TC 12 Z9 13 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD MAY PY 1991 VL 55 IS 5 BP 1483 EP 1486 DI 10.1016/0016-7037(91)90322-V PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FM716 UT WOS:A1991FM71600021 ER PT J AU CATTANEO, MBB CATTANEO, P MORENO, G LEPPING, RP AF CATTANEO, MBB CATTANEO, P MORENO, G LEPPING, RP TI UPSTREAM WAVES IN SATURNS FORESHOCK SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOW-FREQUENCY; BOW SHOCK AB Waves in the foreshock of Saturn have been studied using data from the plasma and magnetic field experiments onboard Voyager 1. The appearance of the waves, in the plasma as well as in the magnetic field data, is related to magnetic connection of the spacecraft to the bow shock. Their relative amplitude DELTA-B/B lies between 0.3 and 0.8 and their period in the spacecraft frame is approximately 500 s. The waves are elliptically polarized and propagate at approximately 30-degrees to the average magnetic field direction. C1 UNIV LA SAPIENZA,DIPARTIMENTO FIS,I-00185 ROME,ITALY. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP CATTANEO, MBB (reprint author), CNR,IST FIS SPAZIO INTERPLANETARIO,CP 27,I-00044 FRASCATI,ITALY. NR 15 TC 5 Z9 5 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 MAY PY 1991 VL 18 IS 5 BP 797 EP 800 DI 10.1029/91GL00858 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FL206 UT WOS:A1991FL20600001 ER PT J AU CHANDRA, S AF CHANDRA, S TI THE SOLAR UV RELATED CHANGES IN TOTAL OZONE FROM A SOLAR ROTATION TO A SOLAR-CYCLE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; ULTRAVIOLET VARIATIONS; STRATOSPHERIC OZONE; TRENDS; MONITOR AB The Nimbus-7 TOMS version 6 data, corrected for the instrument degradation, are analyzed to delineate the solar UV related changes in total ozone(TOZ) against background signals of dynamical origin. It is shown that the solar UV related change in TOZ over a solar cycle is about 1.5 percent that may be attributed to about 6 percent change in the solar UV flux near 200 nm. This estimate is also consistent with the solar UV related changes in TOZ over a time scale of a solar rotation. In the solar rotation case, ozone lags the solar UV by 3-4 days and its sensitivity to solar UV change is a factor of 2-3 less than for the solar cycle case. Both these effects are attributed to chemical time constants in the lower stratosphere that are comparable to the period of a solar rotation. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 21 TC 41 Z9 43 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY PY 1991 VL 18 IS 5 BP 837 EP 840 DI 10.1029/91GL00850 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FL206 UT WOS:A1991FL20600011 ER PT J AU DIXON, TH GONZALEZ, G LICHTEN, SM TRALLI, DM NESS, GE DAUPHIN, JP AF DIXON, TH GONZALEZ, G LICHTEN, SM TRALLI, DM NESS, GE DAUPHIN, JP TI PRELIMINARY DETERMINATION OF PACIFIC-NORTH-AMERICA RELATIVE MOTION IN THE SOUTHERN GULF OF CALIFORNIA USING THE GLOBAL POSITIONING SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PHASE AMBIGUITY RESOLUTION; CRUSTAL DEFORMATION; GEODETIC BASELINES; PLATE BOUNDARY; FAULT; ZONE AB Global Positioning System (GPS) data from experiments conducted in 1985 and 1989 in the southern Gulf of California, Mexico, allow a determination of relative motion between the Pacific and North American plates. The data indicate motion of Cabo San Lucas on the Pacific plate relative to North America at a rate of 47 +/- 7 mm/yr and azimuth of 57 +/- 6-degrees west of north (1-sigma errors), equivalent within uncertainties to the NUVEL-1 global plate motion model. C1 OREGON STATE UNIV,COLL OCEANOG,CONMAR,CORVALLIS,OR 97330. RP DIXON, TH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 17 Z9 17 U1 0 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 MAY PY 1991 VL 18 IS 5 BP 861 EP 864 DI 10.1029/91GL01062 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FL206 UT WOS:A1991FL20600017 ER PT J AU PLESCIA, JB AF PLESCIA, JB TI WRINKLE RIDGES IN LUNAE PLANUM MARS - IMPLICATIONS FOR SHORTENING AND STRAIN SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TECTONICS; ORIGIN AB Photoclinometric data for Lunae Planum wrinkle ridges indicate average relief of approximately 130 m and distinct elevation discontinuities across the ridge of 55 m. Modelling ridges as the result of thrust faulting and associated upper-plate folding indicates shortening across individual ridges of approximately 131 m (90% faulting). Total shortening at 20-degrees-N across Lunae Planum is approximately 1840 m corresponding to a regional compressive strain of 0.29%. Strain appears uniform across Lunae Planum, although it is accommodated by larger and fewer structures in the west than in the east. RP PLESCIA, JB (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,MS 183-501,PASADENA,CA 91109, USA. RI Plescia, Jeffrey/B-7738-2016 NR 27 TC 26 Z9 26 U1 0 U2 4 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 MAY PY 1991 VL 18 IS 5 BP 913 EP 916 DI 10.1029/91GL01070 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FL206 UT WOS:A1991FL20600030 ER PT J AU KATZ, R CUCINOTTA, FA AF KATZ, R CUCINOTTA, FA TI RBE VS DOSE FOR LOW-DOSES OF HIGH-LET RADIATIONS SO HEALTH PHYSICS LA English DT Note ID RADIOSENSITIVITY PARAMETERS; CELLS AB According to track theory, the relative biological effectiveness (RBE) of high linear energy transfer (LET) radiations varies with cellular radiosensitivity parameters and the radiation environment. Of special interest is that the RBE varies as the dose of high-LET radiation to the power (1/m-1) where m is the "target number" parameter, which varies from 2-4 in different cell lines. This applies to neutrons as well as to heavy ions at sufficiently low doses such that cells are not activated in the gamma-kill mode; that is, the tracks of single heavy ions are sufficiently far apart so that there are few cases of inter-track inactivation. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP KATZ, R (reprint author), UNIV NEBRASKA, LINCOLN, NE 68588 USA. NR 9 TC 6 Z9 7 U1 0 U2 1 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 MAY PY 1991 VL 60 IS 5 BP 717 EP 718 DI 10.1097/00004032-199105000-00012 PG 2 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 FH807 UT WOS:A1991FH80700014 PM 2019506 ER PT J AU STERN, SA STOCKE, J WEISSMAN, PR AF STERN, SA STOCKE, J WEISSMAN, PR TI AN IRAS SEARCH FOR EXTRA-SOLAR OORT CLOUDS SO ICARUS LA English DT Article C1 UNIV COLORADO,CTR ASTROPHYS & SPACE ASTRON,BOULDER,CO 80309. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP STERN, SA (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. NR 20 TC 5 Z9 5 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1991 VL 91 IS 1 BP 65 EP 75 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300008 ER PT J AU BUNCH, TE SCHULTZ, P CASSEN, P BROWNLEE, D PODOLAK, M LISSAUER, J REYNOLDS, R CHANG, S AF BUNCH, TE SCHULTZ, P CASSEN, P BROWNLEE, D PODOLAK, M LISSAUER, J REYNOLDS, R CHANG, S TI ARE SOME CHONDRULE RIMS FORMED BY IMPACT PROCESSES - OBSERVATIONS AND EXPERIMENTS SO ICARUS LA English DT Article ID UNEQUILIBRATED ORDINARY CHONDRITES; TYPE-3 ORDINARY CHONDRITES; MATRICES; ORIGIN; SEMARKONA; METEORITE; RECORDS; OXYGEN; BODIES C1 BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. SUNY STONY BROOK,DEPT EARTH & SPACE SCI,ASTRON PROGRAM,STONY BROOK,NY 11794. RP BUNCH, TE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 39 TC 23 Z9 23 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 MAY PY 1991 VL 91 IS 1 BP 76 EP 92 DI 10.1016/0019-1035(91)90127-F PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300009 PM 11538105 ER PT J AU MCKAY, CP AF MCKAY, CP TI UREY PRIZE LECTURE - PLANETARY EVOLUTION AND THE ORIGIN OF LIFE SO ICARUS LA English DT Article ID EARLY EARTH; ANTARCTIC LAKE; CARBON; ATMOSPHERES; DEUTERIUM; NEBULA; BUDGET; DUST; MARS; ICE RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 59 TC 30 Z9 30 U1 0 U2 9 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1991 VL 91 IS 1 BP 93 EP 100 DI 10.1016/0019-1035(91)90128-G PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300010 PM 11538106 ER PT J AU KOUVARIS, LC FLASAR, FM AF KOUVARIS, LC FLASAR, FM TI PHASE-EQUILIBRIUM OF METHANE AND NITROGEN AT LOW-TEMPERATURES - APPLICATION TO TITAN SO ICARUS LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; HYPOTHESIZED OCEAN; ATMOSPHERE C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP KOUVARIS, LC (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. RI Flasar, F Michael/C-8509-2012 NR 35 TC 36 Z9 36 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 MAY PY 1991 VL 91 IS 1 BP 112 EP 124 DI 10.1016/0019-1035(91)90131-C PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300013 ER PT J AU SANDFORD, SA SALAMA, F ALLAMANDOLA, LJ TRAFTON, LM LESTER, DF RAMSEYER, TF AF SANDFORD, SA SALAMA, F ALLAMANDOLA, LJ TRAFTON, LM LESTER, DF RAMSEYER, TF TI LABORATORY STUDIES OF THE NEWLY DISCOVERED INFRARED BAND AT 4705.2 CM-1 (2.1253 MU-M) IN THE SPECTRUM OF IO - THE TENTATIVE IDENTIFICATION OF CO2 SO ICARUS LA English DT Article ID CARBON-DIOXIDE; SO2; SURFACE; MATRICES; SPECTROSCOPY; CLUSTERS; SULFUR; ARGON; H2O C1 UNIV TEXAS,DEPT CHEM ENGN,AUSTIN,TX 78712. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 50 TC 28 Z9 28 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1991 VL 91 IS 1 BP 125 EP 144 DI 10.1016/0019-1035(91)90132-D PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300014 PM 11538104 ER PT J AU KIM, SJ DROSSART, P CALDWELL, J MAILLARD, JP GOORVITCH, D MOORWOOD, A MONETI, A LECACHEUX, J AF KIM, SJ DROSSART, P CALDWELL, J MAILLARD, JP GOORVITCH, D MOORWOOD, A MONETI, A LECACHEUX, J TI THE 2-MU-M POLAR HAZE OF JUPITER SO ICARUS LA English DT Article ID FUNDAMENTAL-BAND; TEMPERATURES; HYDROGEN; H-3+; LINES; CM-1 C1 OBSERV PARIS,ASTROPHYS SECT,CNRS,UA 264,F-92195 MEUDON,FRANCE. YORK UNIV,DEPT PHYS,N YORK M3J 1P3,ONTARIO,CANADA. INST ASTROPHYS,F-75014 PARIS,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. EUROPEAN SO OBSERV,W-8046 GARCHING,GERMANY. EUROPEAN SO OBSERV,SANTIAGO 19,CHILE. RP KIM, SJ (reprint author), UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742, USA. RI Kim, Sang Joon/E-2383-2013 NR 29 TC 24 Z9 24 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 MAY PY 1991 VL 91 IS 1 BP 145 EP 153 DI 10.1016/0019-1035(91)90133-E PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300015 ER PT J AU SUN, ZP STOKER, CR SCHUBERT, G AF SUN, ZP STOKER, CR SCHUBERT, G TI THERMAL AND HUMIDITY WINDS IN OUTER PLANET ATMOSPHERES SO ICARUS LA English DT Article ID URANIAN SYSTEM; INFRARED OBSERVATIONS; MOIST CONVECTION; URANUS; VOYAGER-2; NEPTUNE C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. RP SUN, ZP (reprint author), UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024, USA. NR 15 TC 2 Z9 2 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 MAY PY 1991 VL 91 IS 1 BP 154 EP 160 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FM213 UT WOS:A1991FM21300016 ER PT J AU CHEW, W BAJUK, LJ COOLEY, TW FOOTE, MC HUNT, BD RASCOE, DL RILEY, AL AF CHEW, W BAJUK, LJ COOLEY, TW FOOTE, MC HUNT, BD RASCOE, DL RILEY, AL TI HIGH-TC SUPERCONDUCTOR COPLANAR WAVE-GUIDE FILTER SO IEEE ELECTRON DEVICE LETTERS LA English DT Article ID TRANSMISSION-LINE RESONATOR; YBA2CU3O7-X AB The practical application of high-temperature superconductors requires experimental prototyping and testing of complete components to identify problems and advantages. Coplanar waveguide (CPW) low-pass filters made of YBa2Cu3O7-delta (YBCO) on LaAlO3 substrates, with dimensions suited for integrated circuits, were fabricated and packaged. Measured insertion losses in liquid nitrogen were superior to the loss of a similar thin-film copper filter throughout the 0- to 9.5-GHz passband. These results demonstrate the performance of fully patterned YBCO in a practical CPW structure after sealing in a hermetic package. RP CHEW, W (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 9 TC 2 Z9 2 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD MAY PY 1991 VL 12 IS 5 BP 197 EP 199 DI 10.1109/55.79554 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA FJ400 UT WOS:A1991FJ40000002 ER PT J AU GALINDOISRAEL, V IMBRIALE, WA MITTRA, R SHOGEN, K AF GALINDOISRAEL, V IMBRIALE, WA MITTRA, R SHOGEN, K TI ON THE THEORY OF THE SYNTHESIS OF OFFSET DUAL-SHAPED REFLECTORS - CASE EXAMPLES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID ANTENNAS AB In an earlier paper, the geometrical optics (GO) principles, constraints, and requirements of the dual and single offset shaped reflector synthesis problem were collected and developed into a set of nonlinear first-order partial differential equations (PDE's). Methods of solving these PDE's numerically were illustrated as were certain problems that may arise. This paper presents an extension of the methods by which solutions to the PDE's can be obtained together with several case examples. These examples are then independently analyzed by GO and physical optics (PO) diffraction methods so that the potential users of this approach may gain confidence in the predictability of the synthesis methods. The initial or starting point for the integration over each reflector can be taken on the outer rim, the center, or at an intermediate point-the intermediate starting point being the more general case. In addition, the utility of the speed of this synthesis method is demonstrated. For example, the program utilized herein completes a synthesis in less than 45 s on a 386/20 personal computer and within a fraction of a second on a mainframe Cray. This makes practical the incorporation of the synthesis into a search algorithm that can optimize one or more parameters of the reflector system. For example, optimization of the mapping equations for low cross polarization is performed. An important objective of this paper is to demonstrate the validity and the utility of the synthesis method discussed in our earlier paper. C1 UNIV ILLINOIS,DEPT ELECT & COMP ENGN,ELECTROMAGNET COMMUN LAB,URBANA,IL 61801. NHK JAPAN BROADCASTING CORP,TOKYO,JAPAN. RP GALINDOISRAEL, V (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 6 TC 9 Z9 9 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 MAY PY 1991 VL 39 IS 5 BP 620 EP 626 DI 10.1109/8.81489 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FN883 UT WOS:A1991FN88300008 ER PT J AU LIU, KF BALANIS, CA BARBER, GC AF LIU, KF BALANIS, CA BARBER, GC TI EXACT MUTUAL IMPEDANCE BETWEEN SINUSOIDAL ELECTRIC AND MAGNETIC DIPOLES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB Analytic expressions are presented to provide an accurate and efficient computation of the mutual impedance between sinusoidal electric and magnetic dipoles. C1 NASA,LANGLEY RES CTR,AVRADA AVSCOM JOINT RES PROGRAMS OFF,HAMPTON,VA 23665. RP LIU, KF (reprint author), ARIZONA STATE UNIV,DEPT ELECT ENGN,TELECOMMUN RES CTR,TEMPE,AZ 85287, USA. NR 9 TC 5 Z9 5 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD MAY PY 1991 VL 39 IS 5 BP 684 EP 686 DI 10.1109/8.81503 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FN883 UT WOS:A1991FN88300022 ER PT J AU RENGARAJAN, SR GALINDOISRAEL, V IMBRIALE, WA AF RENGARAJAN, SR GALINDOISRAEL, V IMBRIALE, WA TI AMPLITUDE AND PHASE-SHAPING EFFECTS IN BEAMWAVEGUIDES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note AB In a geometrical optics (GO) design of a beamwaveguide antenna for operation at multiple frequency bands, it is found that the phase center location for the diffracted field pattern is not at the GO focal point at low frequencies. This results in some defocusing loss in the system if the mirror location is selected to optimize the performance at the high frequencies. Results are presented of an investigation on improvements that might be possible by changing the design of the lower frequency input pattern to the beamwaveguide. In particular, the effects of amplitude and phase shaping the input pattern have been studied with an aperture diffraction model. Accurate vector near-field computations were made rapidly by efficacious use of a spherical wave expansion of the input and scattered fields. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RENGARAJAN, SR (reprint author), CALIF STATE UNIV NORTHRIDGE,DEPT ELECT & COMP ENGN,NORTHRIDGE,CA 91330, USA. NR 9 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD MAY PY 1991 VL 39 IS 5 BP 687 EP 690 DI 10.1109/8.81504 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FN883 UT WOS:A1991FN88300023 ER PT J AU SALTZ, JH MIRCHANDANEY, R CROWLEY, K AF SALTZ, JH MIRCHANDANEY, R CROWLEY, K TI RUN-TIME PARALLELIZATION AND SCHEDULING OF LOOPS SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Article DE COMPILER; EXECUTOR; INSPECTOR; LEVEL SET; LOOP PARALLELIZATION; SHARED MEMORY; SPARSE TRIANGULAR SOLVE ID MULTIPROCESSORS AB In this paper, we study run-time methods to automatically parallelize and schedule iterations of a do loop in certain cases, where compile-time information is inadequate. The methods we present in this paper involve execution time preprocessing of the loop. At compile-time, these methods set up the framework for performing a loop dependency analysis. At run-time, wavefronts of concurrently executable loop iterations are identified. Using this wavefront information, loop iterations are reordered for increased parallelism. We utilize symbolic transformation rules to produce: 1) inspector procedures that perform execution time preprocessing and 2) executors or transformed versions of source code loop structures. These transformed loop structures carry out the calculations planned in the inspector procedures. We present performance results from experiments conducted on the Encore Multimax. These results illustrate that run-time reordering of loop indexes can have a significant impact on performance. Furthermore, the overheads associated with this type of reordering are amortized when the loop is executed several times with the same dependency structure. C1 YALE UNIV,DEPT COMP SCI,NEW HAVEN,CT 06520. RP SALTZ, JH (reprint author), NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665, USA. NR 25 TC 58 Z9 59 U1 0 U2 7 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9340 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD MAY PY 1991 VL 40 IS 5 BP 603 EP 612 DI 10.1109/12.88484 PG 10 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FR785 UT WOS:A1991FR78500004 ER PT J AU LIN, TL KSENDZOV, A DEJEWSKI, SM JONES, EW FATHAUER, RW KRABACH, TN MASERJIAN, J AF LIN, TL KSENDZOV, A DEJEWSKI, SM JONES, EW FATHAUER, RW KRABACH, TN MASERJIAN, J TI SIGE/SI HETEROJUNCTION INTERNAL PHOTOEMISSION LONG-WAVELENGTH INFRARED DETECTORS FABRICATED BY MOLECULAR-BEAM EPITAXY SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID GEXSI1-X/SI AB A new SiGe/Si heterojunction internal photoemission (HIP) long-wavelength infrared (LWIR) detector has been fabricated by molecular beam epitaxy (MBE). The detection mechanism of the SiGe/Si HIP detector is infrared absorption in the degenerately doped p+-SiGe layer followed by internal photoemission of photoexcited holes over a heterojunction barrier. By adjusting the Ge concentration in the SiGe layer, and consequently, the valence band offset between SiGe and Si, the cutoff wavelength of SiGe HIP detectors can be extended into the LWIR (8-17-mu-m) regime. Detectors were fabricated by growing p+-SiGe layers using MBE on patterned p-type Si substrates. The SiGe layers were boron-doped, with concentrations ranging from 10(19) cm-3 to 4 x 10(20) cm-3. Infrared absorption of 5-25% in a 30-nm-thick p+-SiGe layer was measured in the 3-20-mu-m range using a Fourier transform infrared spectrometer. Quantum efficiencies of 3-5% have been obtained from test devices in the 8-12-mu-m range. RP LIN, TL (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 10 TC 41 Z9 44 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD MAY PY 1991 VL 38 IS 5 BP 1141 EP 1144 DI 10.1109/16.78391 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA FK001 UT WOS:A1991FK00100030 ER PT J AU MADSEN, SN CHRISTENSEN, EL SKOU, N DALL, J AF MADSEN, SN CHRISTENSEN, EL SKOU, N DALL, J TI THE DANISH SAR SYSTEM - DESIGN AND INITIAL TESTS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE HIGH-RESOLUTION AIRBORNE SAR; SAR SYSTEM DESIGN; SAR CALIBRATION AB In January 1986 the design of a high-resolution airborne C-band Synthetic Aperture Radar (SAR) started at the Electromagnetics Institute of the Technical University of Denmark. The initial system test flight took place in November and December 1989. The purpose of this paper is to describe the design of the system, its implementation, and performance. The paper will show how digital technology has been utilized to realize a very flexible radar with variable resolution, swath-width, and imaging geometry. The motion-compensation algorithms implemented to obtain the high resolution will be outlined, as well as the special features built into the system to ensure proper internal calibration. The data processing system, developed for the image generation and quality assurance, will be sketched, with special emphasis on the flexibility of the system. Sample images and a preliminary performance evaluation will be presented, demonstrating that the design goals have been met. Finally, the on-going system upgrades and the planned scientific utilization of the C-band SAR will be described. C1 TECH UNIV DENMARK,INST ELECTROMAGNET,DK-2800 LYNGBY,DENMARK. RP MADSEN, SN (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE RIDGE,PASADENA,CA 91109, USA. OI Dall, Jorgen/0000-0002-3873-1074 NR 15 TC 24 Z9 26 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 MAY PY 1991 VL 29 IS 3 BP 417 EP 426 DI 10.1109/36.79432 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA FK385 UT WOS:A1991FK38500008 ER PT J AU DURDEN, SL KLEIN, JD ZEBKER, HA AF DURDEN, SL KLEIN, JD ZEBKER, HA TI POLARIMETRIC RADAR MEASUREMENTS OF A FORESTED AREA NEAR MT SHASTA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SCATTEROMETER; SCATTERING; VEGETATION; SIGNATURES; BIOMASS; LAYER; SAR AB We present the results of an experiment using the NASA/JPL DC-8 AIRSAR over a coniferous forest near Mt. Shasta (California) in 1989. Calibration devices were deployed in clearings and under the forest canopy and passes at 20-degrees, 40-degrees, and 55-degrees incidence angles were made with the AIRSAR. A total of eight images at differing incidence angles have been processed and calibrated. We have examined the multipolarization, multifrequency data and found that the C-band cross section averaged over like and cross polarizations is the best parameter for distinguishing between two stands with differing forest biomass. The average cross section at P- and L-bands is useful only for smaller incidence angles. Parameters describing the polarization behavior of the scattering were primarily useful in identifying the dominant scattering mechanisms for forest backscatter. We found that both branch scattering and ground/tree interactions are important at P-band. At L- and C-bands, the return is primarily from the canopy. Comparison with model calculations verified this conclusion. RP DURDEN, SL (reprint author), CALTECH,JET PROP LAB,RADAR SYST SCI & ENGN GRP,PASADENA,CA 91109, USA. NR 24 TC 31 Z9 31 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1991 VL 29 IS 3 BP 444 EP 450 DI 10.1109/36.79435 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 FK385 UT WOS:A1991FK38500011 ER PT J AU BARAM, Y AF BARAM, Y TI ON THE CAPACITY OF TERNARY HEBBIAN NETWORKS SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Article DE MEMORY CAPACITY; NEURAL NETWORKS; ASSOCIATIVE MEMORY; SPARSELY CONNECTED NETWORKS; TERNARY NEURONS; HEBBIAN NETWORKS; HOPFIELD NETWORKS; NEURAL CODING ID ASSOCIATIVE MEMORIES AB Networks of ternary neurons, storing random vectors over the set {-1,0,1} by the so-called Hebbian rule, are considered. It is shown that the maximal number of stored patterns that are equilibrium states of the network with probability tending to one as N tends to infinity is at least of the order of N2-1/alpha/K, where N is the number of neurons, K is the number of nonzero elements in a pattern and t = alpha-K, 1/2 < alpha < 1, is the threshold in the neuron function. While for small K this bound is similar to that obtained for fully connected binary networks, the number of interneural connections required in the ternary case can be considerably smaller. Similar bounds incorporating error probabilities are shown to guarantee, in the same probabilistic sense, the correction of errors in the nonzero elements and in the location of these elements. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BARAM, Y (reprint author), TECHNION ISRAEL INST TECHNOL,DEPT COMP SCI,IL-32000 HAIFA,ISRAEL. NR 7 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 0018-9448 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD MAY PY 1991 VL 37 IS 3 BP 528 EP 534 DI 10.1109/18.79908 PN 1 PG 7 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FJ206 UT WOS:A1991FJ20600008 ER PT J AU YBARRA, GA ARDALAN, SH HEARN, CP MARSHALL, RE NEECE, RT AF YBARRA, GA ARDALAN, SH HEARN, CP MARSHALL, RE NEECE, RT TI DETECTION OF TARGET DISTANCE IN THE PRESENCE OF AN INTERFERING REFLECTION USING A FREQUENCY-STEPPED DOUBLE SIDE-BAND SUPPRESSED CARRIER MICROWAVE RADAR SYSTEM SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB A technique for detecting the distance to a highly reflective target in the presence of an interfering reflection using a frequency-stepped double side-band suppressed carrier (DSBSC) microwave-millimeter-wave radar system is analytically derived. Although this system is being developed for measuring nonuniform electron plasma densities as a function of distance from a heat tile on a space reentry vehicle, the technique is quite general and could be applied to other short-range radar problems. The main result of the analysis shows that the measured group delays produced by the DSBSC system possess a periodicity inversely proportional to the difference between the time delays to the target and interferer, independent of the signal-to-interference ratio (SIR). Thus, if the distance to the interferer is known, then the periodicity of the measured group delays may be used to extract the target distance, independent of SIR. Simulation results are presented in the context of electron plasma density range estimation using a block diagram communications CAD tool. A unique and accurate plasma model is introduced. A high-resolution spectral estimation technique based on an autoregressive time series analysis is applied to the measured group delays, and it is shown that accurate target distance estimates may be obtained, independent of SIR. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RES TRIANGLE INST,RES TRIANGLE PK,NC 27709. RP YBARRA, GA (reprint author), N CAROLINA STATE UNIV,DEPT ELECT & COMP ENGN,BOX 7911,RALEIGH,NC 27695, USA. NR 14 TC 6 Z9 6 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 MAY PY 1991 VL 39 IS 5 BP 809 EP 818 DI 10.1109/22.79108 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA FG964 UT WOS:A1991FG96400009 ER PT J AU DIB, NI KATEHI, LPB PONCHAK, GE SIMONS, RN AF DIB, NI KATEHI, LPB PONCHAK, GE SIMONS, RN TI THEORETICAL AND EXPERIMENTAL CHARACTERIZATION OF COPLANAR WAVE-GUIDE DISCONTINUITIES FOR FILTER APPLICATIONS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID WAVE-GUIDE; CIRCUITS; DESIGN AB A full-wave analysis of shielded coplanar waveguide two-port discontinuities based on the solution of an appropriate surface integral equation in the space domain is presented. Using this method, frequency-dependent scattering parameters for open-end and short-end CPW stubs are computed. The numerically derived results are compared with measurements performed in the frequency range 5-25 GHz and show very good agreement. Equivalent circuit models and closed-form expressions to compute the circuit element values for these discontinuities are also presented. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. NASA,LEWIS RES CTR,DIV SPACE ELECTR,SOLID STATE TECHNOL BRANCH,CLEVELAND,OH 44135. RP DIB, NI (reprint author), UNIV MICHIGAN,RADIOL LAB,ANN ARBOR,MI 48109, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 22 TC 62 Z9 63 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1991 VL 39 IS 5 BP 873 EP 882 DI 10.1109/22.79116 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA FG964 UT WOS:A1991FG96400017 ER PT J AU HANNAFORD, B WOOD, L MCAFFEE, DA ZAK, H AF HANNAFORD, B WOOD, L MCAFFEE, DA ZAK, H TI PERFORMANCE EVALUATION OF A 6-AXIS GENERALIZED FORCE-REFLECTING TELEOPERATOR SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS LA English DT Article AB Recent work in real-time distributed computation and control has culminated in a prototype force-reflecting telemanipulation system having dissimilar master (cable-driven force-reflecting hand controller) and slave (PUMA 560 robot with custom controller), extremely high sampling rate (1000 Hz), and low loop computation delay (5 ms). In a series of experiments with this system and five trained test operators covering more than 100 h of teleoperation, performance in a series of generic and application-driven tasks with and without force feedback was measured, and with control shared between teleoperation and local sensor referenced control. Measurements defining task performance include 100-Hz recording of six-axis force-torque information, task completion time, and visual observation of predefined task errors. The tasks consisted of high precision peg-in-hole insertion, electrical connectors, velcro attach-detach, and a twist-lock multipin connector. Each task was repeated three times under several operating conditions: "normal" bilateral telemanipulation, forward position control without force feedback, and shared control. In shared control, orientation was locally servo-controlled to comply with applied torques, while translation was under operator control. All performance measures improved as capability was added along a spectrum of capabilities ranging from pure position control through force-reflecting teleoperation and shared control. Performance was maximal for the bare-handed operator. C1 CALTECH,JET PROP LAB,ROBOT HARDWARE & FLIGHT EXPT GRP,PASADENA,CA 91109. NR 23 TC 121 Z9 121 U1 0 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9472 J9 IEEE T SYST MAN CYB JI IEEE Trans. Syst. Man Cybern. PD MAY-JUN PY 1991 VL 21 IS 3 BP 620 EP 633 DI 10.1109/21.97455 PG 14 WC Computer Science, Cybernetics; Engineering, Electrical & Electronic SC Computer Science; Engineering GA GJ600 UT WOS:A1991GJ60000012 ER PT J AU DRUYAN, LM HASTENRATH, S AF DRUYAN, LM HASTENRATH, S TI MODELING THE DIFFERENTIAL IMPACT OF 1984 AND 1950 SEA-SURFACE TEMPERATURES ON SAHEL RAINFALL SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE SEA-SURFACE TEMPERATURE; SAHEL; GENERAL CIRCULATION MODEL ID CLIMATE AB Experiments with the GISS general circulation model are analysed to evaluate the differential impact of the contrastingly different 1984 and 1950 sea-surface temperature (SST) patterns on simulated precipitation over sub-Saharan Africa. Simulations yielded significantly lower August rainfall with 1984 SST as compared with 1950 SST. Differences in the moisture convergence into the Sahel responsible for the different resultant precipitation conditions are related to different evolutions of key circulation features. These are, in turn, consistent with some 1984 vs. 1950 SST differences in the Atlantic Ocean. In the model scenario, anomalously warm surface waters in July 1984 deepened the near-equatorial trough over the coastal waters adjacent to north-west Africa, promoting a circulation that eventually inhibited moisture advection from the Gulf of Guinea to the Sahel. This atmospheric evolution included a southward expansion of the West African Mid-tropospheric jet, which has been observed to occur during dry summers. The study suggests that this structure is a symptom of drought rather than a cause. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV WISCONSIN,DEPT METEOROL,MADISON,WI 53706. RP DRUYAN, LM (reprint author), COLUMBIA UNIV,NEW YORK,NY 10025, USA. NR 17 TC 11 Z9 11 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD MAY-JUN PY 1991 VL 11 IS 4 BP 367 EP 380 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FT558 UT WOS:A1991FT55800002 ER PT J AU ROTEM, A AF ROTEM, A TI THE FATIGUE BEHAVIOR OF ORTHOTROPIC LAMINATES UNDER TENSION COMPRESSION LOADING SO INTERNATIONAL JOURNAL OF FATIGUE LA English DT Article DE FATIGUE OF COMPOSITES; DELAMINATION; TENSION COMPRESSION FATIGUE; INTERLAMINAR FATIGUE AB The fatigue behaviour of orthotropic laminates, [0-degrees, +/- 45-degrees,0-degrees]2s and [90-degrees, +/- 45-degrees,90-degrees]2s, has been evaluated under alternating tension-compression loading. Even though the first laminate is much stronger than the second both started to fail by delamination. Visual damage started to show only at the very end of the fatigue life but measurement of the stiffness showed that degradation starts at about 80% of the fatigue life. The first laminate failed in compression after delamination between the 0-degrees and the 45-degrees laminae, while the second failed in tension after delamination between the +45-degrees and -45-degrees laminae. It is shown that the interlaminar fatigue strength of both laminate structures can be correlated to the applied fatigue load. With the aid of the fatigue failure envelope concept, the behaviour of the orthotropic laminate can be characterized. The experimental results for this laminate (in the two perpendicular directions) are shown here and a method to predict the fatigue behaviour under loading in any direction is formulated. C1 NASA,AMES RES CTR,TEST ENGN & ANAL BRANCH,MOFFETT FIELD,CA 94035. RP ROTEM, A (reprint author), TECHNION ISRAEL INST TECHNOL,FAC MECH ENGN,IL-32000 HAIFA,ISRAEL. NR 15 TC 7 Z9 8 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0142-1123 J9 INT J FATIGUE JI Int. J. Fatigue PD MAY PY 1991 VL 13 IS 3 BP 209 EP 215 DI 10.1016/0142-1123(91)90243-R PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA GD255 UT WOS:A1991GD25500003 ER PT J AU ALIAHMAD, WY REBEIZ, GM DAVE, H CHIN, G AF ALIAHMAD, WY REBEIZ, GM DAVE, H CHIN, G TI 802GHZ INTEGRATED HORN ANTENNAS IMAGING ARRAY SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RP ALIAHMAD, WY (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. RI Chin, Gordon/E-1520-2012 NR 5 TC 10 Z9 10 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 MAY PY 1991 VL 12 IS 5 BP 481 EP 486 DI 10.1007/BF01010881 PG 6 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA FM285 UT WOS:A1991FM28500003 ER PT J AU SEZE, G ROSSOW, WB AF SEZE, G ROSSOW, WB TI TIME-CUMULATED VISIBLE AND INFRARED RADIANCE HISTOGRAMS USED AS DESCRIPTORS OF SURFACE AND CLOUD VARIATIONS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID OUTGOING LONGWAVE RADIATION; CLIMATE-RESEARCH; COVER; IMAGERY; STATISTICS; ISCCP; VARIABILITY; PARAMETERS; METEOSAT; FIELDS AB The spatial and temporal stability of the distributions of satellite-measured visible and infrared radiances, caused by variations in clouds and surfaces, are investigated using bidimensional and monodimensional histograms and time-composite images. Similar analysis of the histograms of the original and time-composite images provides separation of the contributions of the space and time variations to the total variations. The variability of both the surfaces and clouds is found to be larger at scales much larger than the minimum resolved by satellite imagery. This study shows that the shapes of these histograms are distinctive characteristics of the different climate regimes and that particular attributes of these histograms can be related to several general, though not universal, properties of clouds and surface variations at regional and synoptic scales. There are also significant exceptions to these relationships in particular climate regimes. The characteristics of these radiance histograms provide a stable well defined descriptor of the cloud and surface properties. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP SEZE, G (reprint author), CNRS,METEOROL DYNAM LAB,F-91128 PALAISEAU,FRANCE. RI Rossow, William/F-3138-2015 NR 51 TC 32 Z9 37 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAY PY 1991 VL 12 IS 5 BP 877 EP 920 PG 44 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FM211 UT WOS:A1991FM21100004 ER PT J AU SEZE, G ROSSOW, WB AF SEZE, G ROSSOW, WB TI EFFECTS OF SATELLITE DATA RESOLUTION ON MEASURING THE SPACE-TIME VARIATIONS OF SURFACES AND CLOUDS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID CLIMATE-RESEARCH; IMAGERY; STATISTICS; RADIATION; ISCCP; VARIABILITY AB The correlated distributions of satellite-measured visible and infrared radiances, caused by spatial and temporal variations in clouds and surfaces, have been found to be characteristic of the major climate regimes and can be described by the attributes of bidimensional and monodimensional histograms and time-composite images. Most of the variability of both the surfaces and clouds is found to occur at scales larger than the minimum resolved by satellite imagery. Since satellite imaging data sets are difficult to analyse because of their large volumes, many studies reduce the volume by various sampling or averaging schemes. The effects of data resolution and sampling on the radiance histogram statistics and on the time-composite image characteristics are examined. In particular, the sampling strategy used by the International Satellite Cloud Climatology Project is tested. This sampling strategy is found to preserve the statistics of smaller cloud variations for most regions, with the exception of very rare events, if they are accumulated over large enough areas (at least 500 km in dimension) and long enough time periods (at least one month). C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP SEZE, G (reprint author), CNRS,METEOROL DYNAM LAB,F-91128 PALAISEAU,FRANCE. RI Rossow, William/F-3138-2015 NR 30 TC 42 Z9 43 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 MAY PY 1991 VL 12 IS 5 BP 921 EP 952 PG 32 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FM211 UT WOS:A1991FM21100005 ER PT J AU JUSTICE, CO TOWNSHEND, JRG KALB, VL AF JUSTICE, CO TOWNSHEND, JRG KALB, VL TI REPRESENTATION OF VEGETATION BY CONTINENTAL DATA SETS DERIVED FROM NOAA-AVHRR DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SIMPLE BIOSPHERE MODEL; SATELLITE DATA; INDEX; CLASSIFICATION; RESOLUTION; SCALE AB Coarse resolution satellite data provide a unique means by which to examine the spatial characteristics of surface phenomena at a wide range of spatial scales. In this study images of the Normalized Difference Vegetation Index (NDVI) with a resolution of 8 km derived from the National Oceanographic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) are studied at a variety of spatial scales ranging from 8 to 512 km. Scale variance analysis is used to examine the spatial characteristics of the NDVI up to the scale comparable with that used for global modelling. This technique identifies the scales at which spatial variation is taking place and the relative magnitude of the variation. Both annual and seasonal images of Africa from 1987 are examined. The analysis revealed substantial differences within the continent in the scale at which spatial variation takes place. Commonly, for the annual image there is an increase in spatial variation with coarsening spatial resolution, although certain areas of complex surface conditions show markedly different patterns. There are substantial changes in the spatial characteristics of the NDVI with time. Analysis of monthly maximum value composites for September and February revealed different responses in scale variance as a function of spatial resolution. These spatial differences were most marked for areas where vegetation possesses strong seasonality. Interpretation of these results leads us to believe that different factors appear to be controlling the spatial variation of the NDVI at different scales. Averaging at coarse grid cell sizes of 512 km as a means of representing surface conditions results in varied success in representing the NDVI. Averaging areas of transition and surface heterogeneity may result in a substantial over-simplification of surface conditions. Consideration needs to be given to the spatial characteristics of areas and their temporal variability if satellite-derived data are going to be validly applied to global models. C1 UNIV READING,DEPT GEOG,READING RG6 2AU,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771. RP JUSTICE, CO (reprint author), UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742, USA. RI Kalb, Virginia/A-9971-2009 OI Kalb, Virginia/0000-0002-3107-9271 NR 33 TC 32 Z9 36 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAY PY 1991 VL 12 IS 5 BP 999 EP 1021 PG 23 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FM211 UT WOS:A1991FM21100009 ER PT J AU SCHUTT, JB HOLBEN, BN MCMURTREY, JE AF SCHUTT, JB HOLBEN, BN MCMURTREY, JE TI A COMPARISON OF STOKES PARAMETERS FOR SKY AND A SOYBEAN CANOPY SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID POLARIZATION AB Polarization signatures derived from the four Strokes parameters were compared for the sky and a soybean canopy. For an azimuth of 80-degrees measured from the Sun, the signature for the sky under Rayleigh conditions was found to mimic closely that found in the principal plane of the canopy (Fresnel reflection). However, for azimuths of 90-degrees and 270-degrees the canopy polarization was distinct from those of the sky for all azimuths. Its response in those instances was essentially that which would be found by reflecting the sky polarization signatures across a plane passing through a phase angle of about 90-degrees and parallel to the polarization axis. The fourth Stokes parameter for the soybean canopy obtained in the principal plane on a clear day showed classical behaviour according to electromagnetic theory. It exhibited a change in handedness in the vicinity of Brewster's angle. This behaviour was not observed out of the principal plane. A comparison of sky polarization signatures with aerosol optical densities showed that only the third Stokes parameter was unambiguously affected. C1 REMOTE SENSING LAB, BELTSVILLE AGR RES CTR, BELTSVILLE, MD 20705 USA. RP SCHUTT, JB (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EARTH RESOURCES BRANCH, CODE 623, GREENBELT, MD 20771 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD MAY PY 1991 VL 12 IS 5 BP 1087 EP 1095 PG 9 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FM211 UT WOS:A1991FM21100014 ER PT J AU DAUGHTRY, CST RANSON, KJ BIEHL, LL AF DAUGHTRY, CST RANSON, KJ BIEHL, LL TI C-BAND BACKSCATTERING FROM CORN CANOPIES SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID VEGETATION CANOPIES; MICROWAVE EMISSION; SOIL-MOISTURE; SCATTEROMETER AB A frequency-modulated continuous-wave C-band (4.8 GHz) scatterometer was mounted on an aerial lift truck and backscatter coefficients of corn (Zea mays L.) were acquired as functions of polarizations, view angles and row directions. As phytomass and green-leaf area index increased, the backscatter also increased. Near anthesis, when the canopies were fully developed, the major scattering elements were located in the upper 1 m of the 2.8 m tall canopy and little backscatter was measured below that level for view angles of 30-degrees or greater. C-band backscatter data could provide information to monitor tillage operations at small view zenith angles and vegetation at large view zenith angles. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,EARTH RESOURCES BRANCH,GREENBELT,MD 20771. PURDUE UNIV,APPLICAT REMOTE SENSING LAB,W LAFAYETTE,IN 47907. RP DAUGHTRY, CST (reprint author), USDA ARS,BELTSVILLE AGR RES CTR,REMOTE SENSING RES LAB,BELTSVILLE,MD 20705, USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 16 TC 12 Z9 13 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 MAY PY 1991 VL 12 IS 5 BP 1097 EP 1109 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA FM211 UT WOS:A1991FM21100015 ER PT J AU MACKAY, RA BRINDLEY, PK FROES, FH AF MACKAY, RA BRINDLEY, PK FROES, FH TI CONTINUOUS FIBER-REINFORCED TITANIUM ALUMINIDE COMPOSITES SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article ID MATRIX COMPOSITES; REACTION ZONE AB Recent work on a lightweight, elevated-temperature intermetallic-matrix composite (SCS-6 SiC/alpha-2 Ti-14Al-21Nb), including investigations of fabrication techniques, microstructural characteristics and mechanical behavior, indicates that the material appears promising for a number of demanding applications. If successfully implemented, this material, or a derivative, will provide substantial weight savings in aerospace systems. To realize this potential, major challenges must be conquered-low-temperature ductility and environmental resistance must be improved, and the cost must be brought to competitive levels. C1 UNIV IDAHO, INST MAT & ADV PROC, MOSCOW, ID 83843 USA. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 62 TC 83 Z9 83 U1 0 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD MAY PY 1991 VL 43 IS 5 BP 23 EP 29 PG 7 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA FN937 UT WOS:A1991FN93700004 ER PT J AU FLEMING, EL CHANDRA, S AF FLEMING, EL CHANDRA, S TI A TIDAL WIND MODEL FOR 85-120 KM BASED ON CIRA-86 - A FEASIBILITY STUDY SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID INCOHERENT-SCATTER RADAR; UPPER MIDDLE ATMOSPHERE; LOWER THERMOSPHERE; SASKATOON 52-DEGREES-N; NUMERICAL-MODEL; TIDES; SOLAR; CIRCULATION; TEMPERATURE; MESOSPHERE AB This paper examines the feasibility of deriving a climatology of the diurnal variations of the wind in the 85-120 km region from the tidal components of temperature, density, and composition contained in the new COSPAR International Reference Atmosphere, CIRA-1986, Part I: Thermosphere Models [(1988), Adv. Space Res. 8,9]. To derive the wind field, we used the zonal and meridional momentum equations which have been modified from the characteristic scales of the tidal components observed in the 85-120 km region. The CIRA temperature and density model was used to derive the eastward (westerly) and northward (southerly) pressure gradient forces which serve as the forcing functions in the coupled momentum equations. Ground-based wind data from the Mesosphere-Lower Thermosphere (MLT) radar network is used as an independent data set to check the accuracy of the derived tidal wind model. At mid-latitudes, the model reproduces some of the general features observed in the radar tidal data, such as the dominant semidiurnal tide with increasing amplitude with height and clockwise (counterclockwise) rotation of the velocity vector observed in the northern (southern) hemisphere. The model overestimates the semidiurnal amplitudes observed by radar by 50-75% during most seasons with the best agreement found during the equinoctial months. The model exhibits little phase variation with height or season, whereas the radar data exhibit a downward phase progression during most seasons (other than summer) characteristic of upward propagating tidal waves, and large seasonal phase variations associated with seasonal changes in vertical wavelengths. The diurnal tidal amplitudes, which are generally 5-20 m s-1 at mid-latitude radar stations and are dominant over the semidiurnal amplitudes at lower latitudes, are less than 5 m s-1 at all latitudes in the model. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHER CHEM & DYNAM BRANCH,GREENBELT,MD 20771. RP FLEMING, EL (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. NR 40 TC 2 Z9 2 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD MAY PY 1991 VL 53 IS 5 BP 425 EP 445 DI 10.1016/0021-9169(91)90037-8 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA GE765 UT WOS:A1991GE76500007 ER PT J AU GARDNER, SD HOFLUND, GB UPCHURCH, BT SCHRYER, DR KIELIN, EJ SCHRYER, J AF GARDNER, SD HOFLUND, GB UPCHURCH, BT SCHRYER, DR KIELIN, EJ SCHRYER, J TI COMPARISON OF THE PERFORMANCE-CHARACTERISTICS OF PT/SNOX AND AU/MNOX CATALYSTS FOR LOW-TEMPERATURE CO OXIDATION SO JOURNAL OF CATALYSIS LA English DT Article ID CARBON-MONOXIDE; GOLD CATALYSTS C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP GARDNER, SD (reprint author), UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611, USA. NR 22 TC 172 Z9 176 U1 3 U2 9 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9517 J9 J CATAL JI J. Catal. PD MAY PY 1991 VL 129 IS 1 BP 114 EP 120 DI 10.1016/0021-9517(91)90015-V PG 7 WC Chemistry, Physical; Engineering, Chemical SC Chemistry; Engineering GA FG050 UT WOS:A1991FG05000014 ER PT J AU RENDELL, AP LEE, TJ AF RENDELL, AP LEE, TJ TI AN EFFICIENT FORMULATION AND IMPLEMENTATION OF THE ANALYTIC ENERGY GRADIENT-METHOD TO THE SINGLE AND DOUBLE EXCITATION COUPLED-CLUSTER WAVE-FUNCTION - APPLICATION TO CL2O2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN-BASIS SETS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; CHLORINE PEROXIDE; 2ND DERIVATIVES; 2ND-ROW ATOMS; HYDROGEN; CONTRACTION; CIO AB The analytic energy gradient for the single and double excitation coupled-cluster (CCSD) wave function has been reformulated and implemented in a new set of programs. The reformulated set of gradient equations have a smaller computational cost than any previously published. The iterative solution of the linear equations and the construction of the effective density matrices are fully vectorized, being based on matrix multiplications. The new method has been used to investigate the Cl2O2 molecule, which has recently been postulated as an important intermediate in the destruction of ozone in the stratosphere. In addition to reporting computational timings, the CCSD equilibrium geometries, harmonic vibrational frequencies, infrared intensities, and relative energetics of three isomers of Cl2O2 are presented. The relative energies of the three isomers are further investigated using large atomic natural orbital basis sets in conjunction with the CCSD(T) method, which includes a perturbational estimate of connected triple excitations. The peroxide form of Cl2O2 is predicted to be the lowest energy isomer with the ClClO2 form lying 5.1 +/- 3.5 kcal/mol higher in energy. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 43 TC 70 Z9 70 U1 0 U2 3 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 MAY 1 PY 1991 VL 94 IS 9 BP 6219 EP 6228 DI 10.1063/1.460410 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FH765 UT WOS:A1991FH76500053 ER PT J AU LEE, TJ RENDELL, AP AF LEE, TJ RENDELL, AP TI ANALYTIC GRADIENTS FOR COUPLED-CLUSTER ENERGIES THAT INCLUDE NONITERATIVE CONNECTED TRIPLE EXCITATIONS - APPLICATION TO CIS-HONO AND TRANS-HONO SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; MULTIREFERENCE CL GRADIENTS; BODY PERTURBATION-THEORY; MCSCF 2ND DERIVATIVES; GAUSSIAN-BASIS SETS; PHOTODISSOCIATION DYNAMICS; ANALYTICAL DIFFERENTIATION; MOLECULAR CALCULATIONS; NITROUS ACIDS; ATOMS AB An efficient formulation of the analytic energy gradient for the single and double excitation coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T), is presented. The formulation presented here has a smaller computational cost than any previous formulation, and the algebraic manipulations that lead to the additional savings may be applied generally to the analytic gradient of Moller-Plesset perturbation theory energies. The energy contribution from connected triple excitations scales as n-omicron-3n-upsilon-4, and the additional work needed for the gradient scales as 2n-omicron-3n-upsilon-4 + 2n-omicron-4n-upsilon-3, where n-omicron is the number of doubly occupied orbitals and n-upsilon is the number of unoccupied orbitals. The new formulation has been implemented in an efficient set of programs that utilize highly vectorized algorithms and has been used to investigate the equilibrium structures, harmonic vibrational frequencies, infrared intensities, and energy separation of cis-and trans-HONO. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 54 TC 161 Z9 161 U1 0 U2 8 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 MAY 1 PY 1991 VL 94 IS 9 BP 6229 EP 6236 DI 10.1063/1.460411 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FH765 UT WOS:A1991FH76500054 ER PT J AU STUART, CA MEEHAN, RT NEALE, LS CINTRON, NM FURLANETTO, RW AF STUART, CA MEEHAN, RT NEALE, LS CINTRON, NM FURLANETTO, RW TI INSULIN-LIKE GROWTH FACTOR-I BINDS SELECTIVELY TO HUMAN PERIPHERAL-BLOOD MONOCYTES AND LYMPHOCYTE-B SO JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM LA English DT Article ID SOMATOMEDIN RECEPTOR-SITES; MONONUCLEAR-CELLS; LIVER AB Insulin-like growth factor-I (IGF-I) is a potential modulator of responses to a variety of immunological challenges. Previous studies have suggested that specific IGF-I receptors are present on peripheral blood leukocytes, including polymorphonuclear leukocytes, lymphocytes, and monocytes. We sought to determine what type of IGF receptor was present on peripheral blood mononuclear cells and which types of cells possessed these receptors. Binding of [I-125]IGF-I to mononuclear cells was inhibited by both unlabeled IGF-I and insulin, insulin being 200-fold less potent than IGF-I. Covalent affinity labeling with [I-125]IGF-I, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography, revealed a specific binding species with an apparent mol wt of 130 kDa. Two color flow cytometric analysis of mononuclear cells stained with mouse monoclonal antibodies specific for the human IGF-I receptor, the human insulin receptor, and monoclonal antibodies directed against specific monocyte and lymphocyte subset cell surface antigens revealed that both IGF-I receptors and insulin receptors were present on nearly all monocytes and B-lymphocytes, but were present on only 2% of T-lymphocytes. We conclude from these data that among human peripheral blood nonactivated mononuclear cells, IGF-I binds to specific type I IGF receptors found predominately on monocytes and B-lymphocytes. C1 COLORADO HLTH SCI CTR, DEPT MED, DENVER, CO 80262 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. UNIV ROCHESTER, DEPT PEDIAT, ROCHESTER, NY 14642 USA. RP STUART, CA (reprint author), UNIV TEXAS, MED BRANCH, DEPT MED, ROOM OJSH 4-174, ROUTE E68, GALVESTON, TX 77550 USA. FU NCI NIH HHS [5R01-CA-38981]; NCRR NIH HHS [M01-RR-00073] NR 17 TC 108 Z9 108 U1 0 U2 1 PU ENDOCRINE SOC PI CHEVY CHASE PA 8401 CONNECTICUT AVE, SUITE 900, CHEVY CHASE, MD 20815-5817 USA SN 0021-972X J9 J CLIN ENDOCR METAB JI J. Clin. Endocrinol. Metab. PD MAY PY 1991 VL 72 IS 5 BP 1117 EP 1122 PG 6 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA FH996 UT WOS:A1991FH99600027 PM 1850753 ER PT J AU ROSENFELD, M KWAK, D VINOKUR, M AF ROSENFELD, M KWAK, D VINOKUR, M TI A FRACTIONAL STEP SOLUTION METHOD FOR THE UNSTEADY INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN GENERALIZED COORDINATE SYSTEMS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID STARTED CIRCULAR-CYLINDER; VISCOUS-FLOW; WAKE; PRESSURE C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STERLING SOFTWARE,PALO ALTO,CA. RP ROSENFELD, M (reprint author), MCAT INST,SAN JOSE,CA 95113, USA. NR 33 TC 169 Z9 171 U1 3 U2 12 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 MAY PY 1991 VL 94 IS 1 BP 102 EP 137 DI 10.1016/0021-9991(91)90139-C PG 36 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FK223 UT WOS:A1991FK22300005 ER PT J AU MYERS, MK AF MYERS, MK TI TRANSPORT OF ENERGY BY DISTURBANCES IN ARBITRARY STEADY FLOWS SO JOURNAL OF FLUID MECHANICS LA English DT Article AB An exact equation governing the transport of energy associated with disturbances in an arbitrary steady flow is derived. The result is a generalization of the familiar concept of acoustic energy and is suggested by a perturbation expansion of the general energy equation of fluid mechanics. A disturbance energy density and flux are defined and identified as exact fluid dynamic quantities whose leading-order regular perturbation representations reduce in various special cases to previously known results. The exact equation on disturbance energy is applied to a simple example of nonlinear wave propagation as an illustration of its general utility in situations where a linear description of the disturbance is inadequate. RP MYERS, MK (reprint author), GEORGE WASHINGTON UNIV,NASA LANGLEY RES CTR,JOINT INST ADV FLIGHT SCI,MAIL STOP 269,HAMPTON,VA 23665, USA. NR 14 TC 62 Z9 62 U1 0 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAY PY 1991 VL 226 BP 383 EP 400 DI 10.1017/S0022112091002434 PG 18 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FN166 UT WOS:A1991FN16600017 ER PT J AU RAVESI, EM KRZYNOWEK, J AF RAVESI, EM KRZYNOWEK, J TI VARIABILITY OF SALT ABSORPTION BY BRINE DIPPED FILLETS OF COD (GADUS-MORHUA), BLACKBACK FLOUNDER (PSEUDOPLEURONECTES-AMERICANUS), AND OCEAN PERCH (SEBASTES-MARINUS) SO JOURNAL OF FOOD SCIENCE LA English DT Article AB Major changes in sodium content of fillets of cod, blackback flounder, and ocean perch resulted from varying concentration of brine solution (5, 10, or 15%), duration of dip (30, 60 or 90 sec), fillet thickness, season of catch, and rinsing or skinning fillets before cooking. Post-mortem age (1-5 days) of fish, temperature of brine solution (6, 12, or 20-degrees-C), and cooking had minor effects on final sodium concentration. RP RAVESI, EM (reprint author), NATL MARINE FISHERIES SERV,NE FISHERIES CTR,30 EMERSON AVE,GLOUCESTER,MA 01930, USA. NR 29 TC 7 Z9 7 U1 0 U2 1 PU INST FOOD TECHNOLOGISTS PI CHICAGO PA SUITE 300 221 N LASALLE ST, CHICAGO, IL 60601-1291 SN 0022-1147 J9 J FOOD SCI JI J. Food Sci. PD MAY-JUN PY 1991 VL 56 IS 3 BP 648 EP 652 DI 10.1111/j.1365-2621.1991.tb05348.x PG 5 WC Food Science & Technology SC Food Science & Technology GA FY154 UT WOS:A1991FY15400014 ER PT J AU HEDIN, AE BIONDI, MA BURNSIDE, RG HERNANDEZ, G JOHNSON, RM KILLEEN, TL MAZAUDIER, C MERIWETHER, JW SALAH, JE SICA, RJ SMITH, RW SPENCER, NW WICKWAR, VB VIRDI, TS AF HEDIN, AE BIONDI, MA BURNSIDE, RG HERNANDEZ, G JOHNSON, RM KILLEEN, TL MAZAUDIER, C MERIWETHER, JW SALAH, JE SICA, RJ SMITH, RW SPENCER, NW WICKWAR, VB VIRDI, TS TI REVISED GLOBAL-MODEL OF THERMOSPHERE WINDS USING SATELLITE AND GROUND-BASED OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INCOHERENT-SCATTER RADAR; SEASONAL-VARIATIONS; NEUTRAL WIND; F-REGION; ARECIBO; TEMPERATURES; SONDRESTROM; AREQUIPA; DYNAMICS; PERU AB Thermospheric wind data obtained from the Atmosphere Explorer E andDynamics Explorer 2 satellites have been combined with wind data for the lower and upper thermosphere from ground-based incoherent scatter radar and Fabry-Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km. Comparison of the various data sets with the aid of the model shows in general remarkable agreement, particularly at mid and low latitudes. The ground-based data allow modeling of seasonal/diurnal variations, which are most distinct at mid latitudes. While solar activity variations are now included, they are found to be small and not always very clearly delineated by the current data. They are most obvious at the higher latitudes. The model describes the transition from predominately diurnal variations in the upper thermosphere to semidiurnal variations in the lower thermosphere and a transition from summer to winter flow above 140 km to winter to summer flow below. Significant altitude gradients in the wind are found to extend to 300 km at some local times and pose complications for interpretation of Fabry-Perot observations. C1 UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. ARECIBO OBSERV,ARECIBO,PR 00612. UNIV WASHINGTON,GRAD PROGRAM GEOPHYS,SEATTLE,WA 98195. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. USAF,GEOPHYS LAB,BEDFORD,MA 01731. MIT,HAYSTACK OBSERV,CAMBRIDGE,MA 02139. UNIV WESTERN ONTARIO,LONDON N6A 3K7,ONTARIO,CANADA. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99701. NASA,GODDARD SPACE FLIGHT CTR,UNIV RES FDN,GREENBELT,MD 20771. UTAH STATE UNIV,CTR ATMOSPHER & SPACE SCI,LOGAN,UT 84322. UNIV COLL ABERYSTWYTH,DEPT PHYS,ABERYSTWYTH SY23 1NE,DYFED,WALES. RP HEDIN, AE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,CODE 914,GREENBELT,MD 20771, USA. OI Hernandez, Gonzalo/0000-0003-4245-8696 NR 37 TC 524 Z9 527 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1991 VL 96 IS A5 BP 7657 EP 7688 DI 10.1029/91JA00251 PG 32 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FL029 UT WOS:A1991FL02900006 ER PT J AU RICHARDSON, IG CANE, HV VONROSENVINGE, TT AF RICHARDSON, IG CANE, HV VONROSENVINGE, TT TI PROMPT ARRIVAL OF SOLAR ENERGETIC PARTICLES FROM FAR-EASTERN EVENTS - THE ROLE OF LARGE-SCALE INTERPLANETARY MAGNETIC-FIELD STRUCTURE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTER-PLANETARY SHOCK; LOOP; CLOUDS AB Intensity-time profiles of solar energetic particle enhancements generally show an asymmetry with respect to the heliolongitude of the associated solar event. Particles arrive promptly from events to the west of an observer because of good magnetic connection whereas particle enhancements from poorly connected eastern source regions usually show much slower onsets. However, some 15% of eastern events do show prompt onsets. Two prompt particle enhancements associated with eastern solar events are studied using data from the Goddard Space Flight Center instruments on the ISEE 3 and IMP 8 spacecraft. In both events the prompt particle onset was observed when the spacecraft were in a postshock plasma region, apparently within a magnetic bottle. We suggest that the magnetic bottle extended back to the Sun and served as a channel for fast particle propagation to the spacecraft. Particles accelerated at an expanding coronal shock initiated by the eastern event could be injected onto field lines in the foot of the bottle. RP RICHARDSON, IG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 661,GREENBELT,MD 20771, USA. OI Richardson, Ian/0000-0002-3855-3634 NR 19 TC 42 Z9 42 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 MAY 1 PY 1991 VL 96 IS A5 BP 7853 EP 7860 DI 10.1029/91JA00379 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FL029 UT WOS:A1991FL02900019 ER PT J AU KAR, J PAUL, R KOHLI, R MAHAJAN, KK KASPRZAK, WT NIEMANN, HB AF KAR, J PAUL, R KOHLI, R MAHAJAN, KK KASPRZAK, WT NIEMANN, HB TI ON THE RESPONSE OF EXOSPHERIC TEMPERATURE ON VENUS TO SOLAR-WIND CONDITIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SCALE MAGNETIC-FIELDS; LANGMUIR PROBE; EUV FLUX; IONOSPHERE; ORBITER; MODEL AB Exospheric temperatures (T(ex)) inferred from in-situ measurements of neutral densities by the Pioneer Venus Orbiter have been analyzed to examine any possible dependence on solar wind dynamic pressure (P(sw)). We do not find any linear relationship between P(sw) and T(ex). However, on one occasion when P(sw) was unusually high for a prolonged period, an unmistakable temperature enhancement was observed. Minor enhancements of T(ex) were also observed in a few other cases, with sustained but moderately high P(sw). C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KAR, J (reprint author), NATL PHYS LAB,HILLSIDE RD,NEW DELHI 110012,INDIA. NR 19 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1991 VL 96 IS A5 BP 7901 EP 7904 DI 10.1029/90JA02381 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FL029 UT WOS:A1991FL02900024 ER PT J AU SUNKEL, JW SHIEH, LS AF SUNKEL, JW SHIEH, LS TI MULTISTAGE DESIGN OF AN OPTIMAL MOMENTUM MANAGEMENT CONTROLLER FOR THE SPACE STATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID QUADRATIC REGULATORS; STABLE ALGORITHMS; MODEL-REDUCTION; COMPLEX MATRIX; SIGN FUNCTION; PLACEMENT; REGION; ROOT AB This paper presents a multistage design scheme for determining an optimal control moment gyro momentum management and attitude control system for the Space Station Freedom. First, the space station equations of motion are linearized and then block decomposed into two block decoupled subsystems using the matrix sign algorithm. Next, a sequential design procedure is utilized for designing a linear quadratic regulator for each subsystem, which optimally places the eigenvalues of the closed-loop subsystem in the region of an open sector, bounded by lines inclined at +/- pi/2k (for k = 2 or 3) from the negative real axis and the left hand side of a line parallel to the imaginary axis in the s plane. Simulation results are presented to compare the resultant designs. C1 UNIV HOUSTON,DEPT ELECT ENGN,HOUSTON,TX 77204. RP SUNKEL, JW (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV AVION SYST,HOUSTON,TX 77058, USA. NR 17 TC 8 Z9 12 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 MAY-JUN PY 1991 VL 14 IS 3 BP 492 EP 502 DI 10.2514/3.20668 PG 11 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000002 ER PT J AU JAIN, A AF JAIN, A TI UNIFIED FORMULATION OF DYNAMICS FOR SERIAL RIGID MULTIBODY SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB There has been a growing interest in the development of new and efficient algorithms for multibody dynamics in recent years. Serial rigid multibody systems form the basic subcomponents of general multibody systems, and a variety of algorithms to solve the serial chain forward dynamics problem have been proposed. In this paper, the economy of representation and analysis tools provided by the spatial operator algebra are used to clarify the inherent structure of these algorithms, to identify those that are similar, and to study the relationships among the ones that are distinct. For the purposes of this study, the algorithms are categorized into three classes: algorithms that require the explicit computation of the mass matrix, algorithms that are completely recursive in nature, and algorithms of intermediate complexity. In addition, alternative factorizations for the mass matrix and closed form expressions for its inverse are derived. These results provide a unifying perspective, within which these diverse dynamics algorithms arise naturally as a consequence of a progressive exploitation of the structure of the mass matrix. RP JAIN, A (reprint author), CALTECH,JET PROP LAB,ROBOT & AUTOMAT SECT,MACHINE INTELLIGENCE APPLICAT GRP,TECH STAFF,PASADENA,CA 91109, USA. NR 24 TC 89 Z9 90 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 MAY-JUN PY 1991 VL 14 IS 3 BP 531 EP 542 DI 10.2514/3.20672 PG 12 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000006 ER PT J AU POLITES, ME AF POLITES, ME TI NEW METHOD FOR SCANNING SPACECRAFT AND BALLOON-BORNE SPACE-BASED EXPERIMENTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents a new method for scanning balloon-borne experiments, free-flying spacecraft, and gimballed experiments mounted to space platforms, like the Space Shuttle or the Space Station. It uses rotating-unbalanced-mass devices for generating circular, line, or raster scan patterns and an auxiliary control system for target acquisition, keeping the scan centered on the target, and producing complementary motion for raster scanning. It is ideal for applications where the only possible way to accomplish the required scan is to physically scan the entire experiment or spacecraft as in x-ray and gamma-ray experiments. In such cases, this new method should have advantages over prior methods in terms of either power, weight, cost, performance, stability, or some combination of these. RP POLITES, ME (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB,DIV CONTROL SYST,HUNTSVILLE,AL 35812, USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1991 VL 14 IS 3 BP 548 EP 553 DI 10.2514/3.20674 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000008 ER PT J AU KEEL, LH LIM, KB JUANG, JN AF KEEL, LH LIM, KB JUANG, JN TI ROBUST EIGENVALUE ASSIGNMENT WITH MAXIMUM TOLERANCE TO SYSTEM UNCERTAINTIES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SYLVESTER EQUATION AB For a linear time-invariant system with a feedback controller, the closed-loop eigenvalues perturb due to system uncertainties. Given an allowable tolerance for the closed-loop eigenvalue perturbation, an algorithm is developed to obtain a state feedback controller that maximizes the uncertainty tolerance of the open-loop system matrix. The design procedure is based on an existing eigenvalue assignment technique using Sylvester's equation. A robustness condition is derived to guarantee satisfaction of a specified closed-loop perturbation tolerance. Finally, an iterative algorithm is presented for easy numerical implementation to compute the robust controller, and a numerical example is given for illustration. C1 NASA,LANGLEY RES CTR,SPACECRAFT CONTROL BRANCH,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23665. RP KEEL, LH (reprint author), TENNESSEE STATE UNIV,CTR EXCELLENCE INFORMAT SYST,330 10TH AVE N,NASHVILLE,TN 37203, USA. NR 14 TC 10 Z9 10 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1991 VL 14 IS 3 BP 615 EP 620 DI 10.2514/3.20682 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000016 ER PT J AU JOSHI, SM AF JOSHI, SM TI GENERALIZED PROPORTIONAL-PLUS-DERIVATIVE COMPENSATORS FOR A CLASS OF UNCERTAIN PLANTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP JOSHI, SM (reprint author), NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,HAMPTON,VA 23665, 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1991 VL 14 IS 3 BP 677 EP 680 DI 10.2514/3.20693 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000026 ER PT J AU DESILVA, CW HANKINS, WW AF DESILVA, CW HANKINS, WW TI DYNAMIC EVALUATION OF THE NASA-ORNL TRACTION-DRIVE JOINT SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DESILVA, CW (reprint author), UNIV BRITISH COLUMBIA,DEPT MECH ENGN,VANCOUVER V6T 1W5,BC,CANADA. 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1991 VL 14 IS 3 BP 688 EP 692 DI 10.2514/3.20697 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000030 ER PT J AU GAWRONSKI, W AF GAWRONSKI, W TI MODEL-REDUCTION FOR FLEXIBLE STRUCTURES - TEST DATA APPROACH SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note ID LINEAR-SYSTEMS; COMPONENT RP GAWRONSKI, W (reprint author), CALTECH,JET PROP LAB,GROUND ANTENNAS & FACIL SECT,TECH STAFF,PASADENA,CA 91109, USA. NR 7 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1991 VL 14 IS 3 BP 692 EP 694 DI 10.2514/3.20698 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FQ230 UT WOS:A1991FQ23000031 ER PT J AU KWACK, EY BANKSTON, CP SHAKKOTTAI, P BACK, LH AF KWACK, EY BANKSTON, CP SHAKKOTTAI, P BACK, LH TI ON THE REVERSE FLOW CEILING JET IN POOL FIRE-VENTILATION CROSS-FLOW INTERACTIONS IN A SIMULATED AIRCRAFT CABIN INTERIOR SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article AB The behavior of the reverse flow ceiling jet against the ventilation flow from 0.58 to 0.87 m/s was investigated in a 1/3 scale model of a wide body aircraft interior. For all tests, strong reverse flow ceiling jets of hot gases were detected well upstream of the fire. The penetration lengths of the reverse flow ceiling jet for the tests agree fairly well with the relation, l(r)/H = 0.6 [F-5] where F is the fire-crossflow parameter, F = 2gHQ/rho-cT(s)Au(a)3. Both the thicknesses of the reverse flow ceiling jet and the smoke layer increased with the fire-crossflow parameter. The thickness of the smoke layer where the smoke flows along the main flow below the reverse flow ceiling jet was almost twice that of the reverse flow ceiling jet. Detailed spatial and time-varying temperatures of the gas in the test section were measured and velocity profiles were also measured using a temperature-compensated hot film. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 7 TC 0 Z9 0 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD MAY PY 1991 VL 113 IS 2 BP 446 EP 450 DI 10.1115/1.2910581 PG 5 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA HP759 UT WOS:A1991HP75900024 ER PT J AU MARQUESBONHAM, S AF MARQUESBONHAM, S TI THE DIRAC-EQUATION IN A NON-RIEMANNIAN MANIFOLD III - AN ANALYSIS USING THE ALGEBRA OF QUATERNIONS AND OCTONIONS SO JOURNAL OF MATHEMATICAL PHYSICS LA English DT Article AB The geometrical properties of a flat tangent space-time local to the manifold of the Einstein-Schrodinger nonsymmetric theory to which an internal octonionic space is attached, is developed here. As an application of the theroy, an octonionic Dirac equation for a spin-1/2 particle is also obtained, where is now used an octonionic-like gauge field. It is shown that the (quaternionic) nonsymmetric Yang-Mills theory can be easily recovered and from there, the usual gauge theory on a curved space. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. CTR BRASILEIRO PESQUISAS FIS,DEPT CAMPOS & PARTICULAS,BR-22290 RIO DE JANEIRO,RJ,BRAZIL. NR 18 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0022-2488 J9 J MATH PHYS JI J. Math. Phys. PD MAY PY 1991 VL 32 IS 5 BP 1383 EP 1394 DI 10.1063/1.529291 PG 12 WC Physics, Mathematical SC Physics GA FJ277 UT WOS:A1991FJ27700038 ER PT J AU SMITH, MAH RINSLAND, CP DEVI, VM AF SMITH, MAH RINSLAND, CP DEVI, VM TI MEASUREMENTS OF SELF-BROADENING OF INFRARED-ABSORPTION LINES OF OZONE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID MILLIMETER-WAVE SPECTRUM; INTENSITIES; POSITIONS; O-16(3); NU-1; COEFFICIENTS; HALFWIDTHS C1 COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. RP SMITH, MAH (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 15 TC 26 Z9 26 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD MAY PY 1991 VL 147 IS 1 BP 142 EP 154 DI 10.1016/0022-2852(91)90175-A PG 13 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FH196 UT WOS:A1991FH19600013 ER PT J AU PAIGE, GD TOMKO, DL AF PAIGE, GD TOMKO, DL TI EYE-MOVEMENT RESPONSES TO LINEAR HEAD MOTION IN THE SQUIRREL-MONKEY .1. BASIC CHARACTERISTICS SO JOURNAL OF NEUROPHYSIOLOGY LA English DT Article ID VESTIBULO-OCULAR REFLEX; INNERVATING OTOLITH ORGANS; VERTICAL AXIS ROTATION; EARTH-HORIZONTAL AXIS; CAT; STIMULATION; NYSTAGMUS; FREQUENCY; ACCELERATION; NEURONS AB 1. The purpose of this study was to quantify the response characteristics of eye movements produced by linear head oscillations in the dark (the linear vestibuloocular reflex, or LVOR). Horizontal, vertical, and torsional eye movements were measured in adult squirrel monkeys by the use of a dual scleral search-coil technique during linear oscillations (0.5, 1.5, and 5.0 Hz, 0.36 g peak acceleration) along the animals' interaural (IA), dorsoventral (DV), and nasooccipital (NO) axes. 2. Two LVOR responses, horizontal eye movements during IA-axis translation and vertical eye movements during DV-axis motion, were in a compensatory direction for head translation. Response amplitudes increased as frequency increased, whereas phase typically showed a lead. 3. Two other LVORs, torsional responses during IA-axis translation (all frequencies) and vertical responses during NO-axis oscillations (0.5 Hz), behaved differently. These two LVORs cannot be functionally compensatory for head translation because they degrade fixation on targets, and therefore image stability, by rotating the eyes off target (NO-vertical) or torting the eyes relative to the visual world (IA-torsional). Responses to NO-axis motion at frequencies > 0.5 Hz depended on initial eye position and fixation distance and are described in the companion paper. 4. The effect of head orientation on the LVOR was assessed by testing four head positions in 90-degrees steps around the axis of head motion for each of the three axes of translation. This was done, first, to determine whether the LVORs are responses to the ''swinging vector'' of gravitoinertial force during linear head motion or to head translation; and second, to quantify potential effects of static head (otolith) orientation on the LVORs. Results showed no systematic effects of head orientation on LVOR responses in the frequency bandwidth studied. This indicates that the LVORs are dependent on the direction of linear motion relative to the head (and otolith organs) but not on the swinging vector of gravitoinertial force, and that the LVORs are uninfluenced by static orientation of the head and reloading of the otoliths. C1 NASA,AMES RES CTR,VESTIBULAR RES FACIL,MOFFETT FIELD,CA 94035. RP PAIGE, GD (reprint author), UNIV ROCHESTER,DEPT NEUROL,BOX 605,601 ELMWOOD AVE,ROCHESTER,NY 14642, USA. NR 64 TC 221 Z9 221 U1 1 U2 4 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0022-3077 J9 J NEUROPHYSIOL JI J. Neurophysiol. PD MAY PY 1991 VL 65 IS 5 BP 1170 EP 1182 PG 13 WC Neurosciences; Physiology SC Neurosciences & Neurology; Physiology GA FL746 UT WOS:A1991FL74600014 PM 1869911 ER PT J AU PAIGE, GD TOMKO, DL AF PAIGE, GD TOMKO, DL TI EYE-MOVEMENT RESPONSES TO LINEAR HEAD MOTION IN THE SQUIRREL-MONKEY .2. VISUAL-VESTIBULAR INTERACTIONS AND KINEMATIC CONSIDERATIONS SO JOURNAL OF NEUROPHYSIOLOGY LA English DT Article ID VESTIBULOOCULAR REFLEX; OCULOMOTOR SYSTEM; TARGET DISTANCE; VERGENCE; ACCOMMODATION; ACCELERATION; MIDBRAIN; NEURONS; IDENTIFICATION; CONVERGENCE AB 1. Horizontal, vertical, and torsional eye movements were recorded (search coil technique) from five squirrel monkeys during horizontal linear oscillations at 0.5, 1.5, and 5.0 Hz, 0.36 g peak acceleration. Monkeys were positioned to produce linear motion in their nasooccipital (NO), interaural (IA), and dorsoventral (DV) axes. Responses of the linear vestibuloocular reflex (LVOR) were recorded in darkness and in the light with the subjects viewing a head-fixed field 22 or 9.2 cm from the eye. The latter condition provided a measure of ''visual suppression'' of the LVOR (VSLVOR). Responses were also recorded while monkeys viewed earth-fixed targets, which allowed visual enhancement of the LVOR (VLVOR). Vergence angle was recorded in two monkeys to assess directly the point of binocular fixation in space during linear motion. 2. Two LVOR response types, vertical responses during 0.5-Hz NO-axis translation (NO-vertical) and torsional responses at all frequencies during IA-axis oscillation (IA-torsional) could not be compensatory reflexes for head translation because they either move the eye off target (NO-vertical) or tort the eye relative to the visual world (IA-torsional), thereby degrading visual image stability. 3. Other response types are considered compensatory because they help maintain ocular fixation in space during linear head translation. These include horizontal responses to IA-axis motion (IA-horizontal), vertical responses to DV-axis translation (DV-vertical), and both horizontal and vertical responses to NO-axis oscillation (1.5 and 5 Hz). Observations focus on responses to 5-Hz oscillations, in which visual inputs are essentially ineffective in modifying the LVOR. 4. The kinematics of perfect ocular compensation during head translation indicate that the ideal ocular response is governed by the motion of the eye relative to target position. Relevant variables include target distance, which is crucial for all axes of motion, and target eccentricity, which is important only for head motion roughly parallel to the target (NO-axis translation). Findings are compatible with predictions based on ideal kinematics. However, it is the point of binocular fixation in space, not actual target position, that governs LVOR behavior. 5. The IA-horizontal and DV-vertical LVOR is in response to head motion roughly orthogonal to the line of sight. Responses under all stimulus conditions (LVOR, VSLVOR, and VLVOR) behaved similarly at 5 Hz, and were modulated linearly with vergence [in meter angles (MA), the reciprocal of binocular fixation distance]. Regression of pooled data yielded a slope of 0.22-degrees.cm-1.MA-1 and intercept (response at O MA) of 0.45-degrees.cm, compared with the ideal slope of 0.57-degrees.cm-1.MA-1 and intercept of zero. The positive intercept may be useful by providing better response compensation at modest vergence angles than if the intercept were zero. 6. The NO-LVOR entails head motion roughly parallel to the line of sight. Horizontal and vertical responses were observed that were modulated independently with fixation characteristics. LVOR, VSLVOR, and VLVOR responses at 5 Hz were nearly absent when gaze was parallel to the NO axis but increased in amplitude independently with gaze eccentricity and vergence. The direction of response depended on the direction of gaze; during forward head motion the eyes moved upward during up-gaze, downward during down-gaze, rightward during right-gaze, and leftward during left-gaze. The LVOR during 5 Hz NO-axis head motion also included a vergence LVOR. Its amplitude was appropriately modulated with ambient vergence angle. This implies a form of response dissociation between the two eyes. When binocular fixation converged between the eyes, right and left horizontal LVOR responses opposed each other. 7. The IA-horizontal, DV-vertical, and NO-axis LVORs show characteristics consistent with the kinematics of ideal compensatory eye movements. Important attributes of compensatory LVORs include 1) responses are properly directed and temporally synchronized relative to head translation, 2) response amplitudes rise as binocular fixation distance shortens, and 3) responses to high-frequency NO-axis oscillation are modulated in amplitude and sign depending on gaze angle as well as by fixation distance. Evidence supports the notion that the point of binocular fixation is determined internally by signals proportional to gaze and vergence angles (although a role for accommodation is not ruled out) and that these signals in turn modulate the VOR commensurate with kinematic requirements. Actual target (visual) input is not directly relevant at high frequencies (e.g., 5 Hz), but is presumably used to guide the point of binocular fixation to coincide with target position under most natural conditions. C1 NASA,AMES RES CTR,VESTIBULAR RES FACIL,MOFFETT FIELD,CA 94035. RP PAIGE, GD (reprint author), UNIV ROCHESTER,DEPT NEUROL,BOX 605,601 ELMWOOD AVE,ROCHESTER,NY 14642, USA. NR 36 TC 166 Z9 167 U1 3 U2 7 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0022-3077 J9 J NEUROPHYSIOL JI J. Neurophysiol. PD MAY PY 1991 VL 65 IS 5 BP 1183 EP 1196 PG 14 WC Neurosciences; Physiology SC Neurosciences & Neurology; Physiology GA FL746 UT WOS:A1991FL74600015 PM 1869912 ER PT J AU MIELE, A WANG, T DEATON, AW AF MIELE, A WANG, T DEATON, AW TI DECOMPOSITION TECHNIQUE AND OPTIMAL TRAJECTORIES FOR THE AEROASSISTED FLIGHT EXPERIMENT SO JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS LA English DT Article ID GRADIENT-RESTORATION ALGORITHMS; ORBITAL TRANSFER AB The aeroassisted flight experiment (AFE) refers to a spacecraft to be launched and then recovered by the space shuttle in 1994. It simulates a transfer from a geosynchronous Earth orbit (GEO) to a low Earth orbit (LEO). Specifically, the AFE spacecraft is released from the space shuttle and is accelerated by means of a solid rocket motor toward Earth, so as to achieve atmospheric entry conditions close to those of a spacecraft returning from GEO. Following the atmospheric pass, the AFE spacecraft ascends to the specified LEO via an intermediate parking Earth orbit (PEO). The final maneuver includes the rendezvous with and the capture by the space shuttle. The entry and exit orbital planes of the AFE spacecraft are identical with the orbital plane of the space shuttle. In this paper, with reference to the AFE spacecraft, an actual GEO-to-LEO transfer is considered and optimal trajectories are determined by minimizing the total characteristic velocity. The optimization is performed with respect to the time history of the controls (angle of attack and angle of bank), the entry path inclination and the flight time being free. Two transfer maneuvers are considered: (DA) direct ascent to LEO; (IA) indirect ascent to LEO via PEO. While the motion of the AFE spacecraft in a 3D-space is described by a system of six ODEs, substantial simplifications are possible if one exploits these facts: (i) the instantaneous orbital plane is nearly identical with the initial orbital plane; (ii) the bank angle is small; and (iii) the Earth's angular velocity is relatively small. Under these assumptions, the complete system can be decoupled into two subsystems, one describing the longitudinal motion and one describing the lateral motion. The angle of attack history, the entry path inclination, and the flight time are determined via the longitudinal motion subsystem; in this subsystem, the total characteristic velocity is minimized subject to the specified LEO requirement. The angle of bank history is determined via the lateral motion subsystem; in this subsystem, the difference between the instantaneous bank angle and a constant bank angle is minimized in the least square sense subject to the specified orbital inclination requirement. It is shown that both the angle of attack and the angle of bank are constant. This result has considerable importance in the design of nominal trajectories to be used in the guidance of AFE and AOT vehicles. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SYST ANAL & INTEGRAT LAB,FLIGHT MECH BRANCH,HUNTSVILLE,AL 35812. RP MIELE, A (reprint author), RICE UNIV,AEROASTRONAUT GRP,HOUSTON,TX 77251, USA. NR 21 TC 5 Z9 5 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-3239 J9 J OPTIMIZ THEORY APP JI J. Optim. Theory Appl. PD MAY PY 1991 VL 69 IS 2 BP 201 EP 234 DI 10.1007/BF00940640 PG 34 WC Operations Research & Management Science; Mathematics, Applied SC Operations Research & Management Science; Mathematics GA FN772 UT WOS:A1991FN77200001 ER PT J AU TONG, C SWARZTRAUBER, PN AF TONG, C SWARZTRAUBER, PN TI ORDERED FAST FOURIER-TRANSFORMS ON A MASSIVELY PARALLEL HYPERCUBE MULTIPROCESSOR SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article ID COMMUNICATION; ARCHITECTURES; ALGORITHMS; COMPUTERS C1 NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035. UNIV CALIF LOS ANGELES,DEPT MATH,LOS ANGELES,CA 90024. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. UNIV COLORADO,DEPT COMP SCI,BOULDER,CO 80309. RP TONG, C (reprint author), SANDIA NATL LABS,LIVERMORE,CA 94551, USA. NR 20 TC 12 Z9 15 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD MAY PY 1991 VL 12 IS 1 BP 50 EP 59 DI 10.1016/0743-7315(91)90028-8 PG 10 WC Computer Science, Theory & Methods SC Computer Science GA FL188 UT WOS:A1991FL18800005 ER PT J AU RAMSEY, JK AF RAMSEY, JK TI INFLUENCE OF THICKNESS AND CAMBER ON THE AEROELASTIC STABILITY OF SUPERSONIC THROUGHFLOW FANS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB An engineering approach was used to include the nonlinear effects of thickness and camber in an analysis of cascades in supersonic axial flow (supersonic leading-edge locus). A hybrid code using Lighthill's nonlinear piston theory and Lane's linear potential theory was developed to include these nonlinear effects. Lighthill's theory was used to calculate the unsteady pressures on the noninterference surface regions of the airfoils in cascade. Lane's theory was used to calculate the unsteady pressure on the remaining interference surface regions. Two airfoil profiles were investigated: a supersonic throughflow fan design and a NACA 66-206 airfoil with a sharp leading edge. Results show that compared with predictions of Lane's potential theory for flat plates, the inclusion of thickness (with or without camber) may increase or decrease the aeroelastic stability depending on the airfoil geometry and operating conditions. When thickness effects are included in the aeroelastic analysis, inclusion of camber will influence the predicted stability in proportion to the magnitude of the added camber. The critical interblade phase angle, depending on the airfoil profile and operating conditions, may also be influenced by thickness and camber. RP RAMSEY, JK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 40 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1991 VL 7 IS 3 BP 404 EP 411 DI 10.2514/3.23341 PG 8 WC Engineering, Aerospace SC Engineering GA FU462 UT WOS:A1991FU46200014 ER PT J AU NALLASAMY, N YAMAMOTO, O WARSI, S AF NALLASAMY, N YAMAMOTO, O WARSI, S TI LARGE-SCALE ADVANCED PROPELLER BLADE PRESSURE DISTRIBUTIONS - PREDICTION AND DATA 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 SOC AUTOMOT ENGINEERS, AMER INST AERONAUT & ASTRONAUT, AMER SOC MECH ENGINEERS, AMER ENGN EDUC ID LEADING-EDGE VORTEX; EULER ANALYSIS; FLOWS AB Two Euler analysis techniques, finite difference and finite volume, were employed to predict the blade surface pressure distributions of a large-scale advanced propeller. The predicted pressure distributions were compared with wind-tunnel data. Both techniques produced blade pressure distributions that were in fairly good agreement with the data over the range of test Mach numbers of 0.2-0.78. However, the numerical simulations failed to predict correctly the measured pressure distributions for the low Mach number, high-power case. The data indicate the presence of a leading-edge vortex for this case. A discussion of the compressibility effects is also presented. C1 NASA,DIV PROP SYST,TURBOMACHINERY TECHNOL BRANCH,CLEVELAND,OH 44135. RP NALLASAMY, N (reprint author), SVERDRUP TECHNOL INC,DEPT AEROMECH,BROOK PK,OH 44142, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1991 VL 7 IS 3 BP 452 EP 461 DI 10.2514/3.23347 PG 10 WC Engineering, Aerospace SC Engineering GA FU462 UT WOS:A1991FU46200020 ER PT J AU CHANDRASEKHARA, MS KROTHAPALLI, A BAGANOFF, D AF CHANDRASEKHARA, MS KROTHAPALLI, A BAGANOFF, D TI PERFORMANCE-CHARACTERISTICS OF AN UNDEREXPANDED MULTIPLE JET EJECTOR SO JOURNAL OF PROPULSION AND POWER LA English DT Note C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. FLORIDA A&M UNIV FLORIDA STATE UNIV,COLL ENGN,DEPT MECH ENGN,TALLAHASSEE,FL 32307. USN,NASA,JOINT INST AERONAUT,AMES RES CTR,DEPT AERONAUT & ASTRONAUT,MOFFETT FIELD,CA 94035. RP CHANDRASEKHARA, MS (reprint author), USN,POSTGRAD SCH,MONTEREY,CA 93943, USA. NR 12 TC 5 Z9 5 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 MAY-JUN PY 1991 VL 7 IS 3 BP 462 EP 464 DI 10.2514/3.23348 PG 3 WC Engineering, Aerospace SC Engineering GA FU462 UT WOS:A1991FU46200021 ER PT J AU MAY, RD AF MAY, RD TI ABSOLUTE LINESTRENGTHS IN THE H2O2 NU-6 BAND SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID STRATOSPHERIC HYDROGEN-PEROXIDE; LINE PARAMETER LIST; PLANETARY-ATMOSPHERES; INFRARED INTENSITIES; SPECTRA; J'=25 AB Absolute linestrengths at 295 K have been measured for selected lines in the V6 band of H2O2 using a tunable diode-laser spectrometer. H2O2 concentrations in a flowing gas mixture were determined by ultraviolet (u.v.) absorption at 254 nm using a collinear infrared (i.r.) and u.v. optical arrangement. The measured linestrengths are approx. 60% larger than previously reported values when absorption by hot bands in H2O2 is taken into account. RP MAY, RD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 8 Z9 8 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAY PY 1991 VL 45 IS 5 BP 267 EP 272 DI 10.1016/0022-4073(91)90010-N PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA FF807 UT WOS:A1991FF80700003 ER PT J AU SARAVANOS, DA CHAMIS, CC AF SARAVANOS, DA CHAMIS, CC TI COMPUTATIONAL SIMULATION OF DAMPING IN COMPOSITE STRUCTURES SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB A computational methodology is developed for the prediction of passive damping in composite structures. The method involves multiple levels of damping modelling by integrating micromechanics, laminate, and structural damping theories. The effects of temperature and moisture on structural damping are included. The simulation of damping in the structural level is accomplished with finite-element discretization. Applications are performed on graphite/epoxy composite beams, plates, and shells to illustrate the methodology. Additional parametric studies demonstrate the variation of structural modal damping with respect to ply angles, fiber volume ratio, and temperature. RP SARAVANOS, DA (reprint author), NASA,LEWIS RES CTR,DIV STRUCT,MS 49-8,CLEVELAND,OH 44135, USA. NR 0 TC 18 Z9 20 U1 0 U2 4 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 MAY PY 1991 VL 10 IS 3 BP 256 EP 278 DI 10.1177/073168449101000302 PG 23 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA FK021 UT WOS:A1991FK02100002 ER PT J AU POE, CC AF POE, CC TI SIMULATED IMPACT DAMAGE IN A THICK GRAPHITE EPOXY LAMINATE USING SPHERICAL INDENTERS SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB The extent of fiber damage due to low-velocity impacts was determined for a 36-mm(1.4-in.)-thick graphite/epoxy laminate. The impacts were simulated by quasistatically pressing spherical indenters against the laminates. Indenters of several diameters were used. The laminates were cut into smaller specimens, each containing a test site. The specimens were pyrolyzed to remove the epoxy, and the plies were separated and examined to determine the extent of fiber damage. Broken fibers were found in the outermost layers directly beneath the contact site. The locus of broken fibers resembled cracks. The cracks, which were more or less oriented in the direction of the fibers in the neighboring layers, initiated when the contact pressure exceeded a critical value. However, damage did not become visible on the surface until the pressure exceeded an even higher level. The maximum length and depth of the cracks increased with increasing contact pressure and indenter diameter. The length and depth of the cracks were predicted using theory of elasticity and maximum stress criteria. The predictions and measurements were in good agreement. RP POE, CC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 14 Z9 14 U1 0 U2 3 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 MAY PY 1991 VL 10 IS 3 BP 293 EP 307 DI 10.1177/073168449101000304 PG 15 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA FK021 UT WOS:A1991FK02100004 ER PT J AU STEINER, B DOBBYN, RC BLACK, D BURDETTE, H KURIYAMA, M SPAL, R VANDENBERG, L FRIPP, A SIMCHICK, R LAL, RB BATRA, A MATTHIESEN, D DITCHEK, B AF STEINER, B DOBBYN, RC BLACK, D BURDETTE, H KURIYAMA, M SPAL, R VANDENBERG, L FRIPP, A SIMCHICK, R LAL, RB BATRA, A MATTHIESEN, D DITCHEK, B TI HIGH-RESOLUTION SYNCHROTRON X-RADIATION DIFFRACTION IMAGING OF CRYSTALS GROWN IN MICROGRAVITY AND CLOSELY RELATED TERRESTRIAL CRYSTALS SO JOURNAL OF RESEARCH OF THE NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY LA English DT Article DE CRYSTAL GROWTH; DIFFRACTION; GALLIUM ARSENIDE; HIGH RESOLUTION; LEAD TIN TELLURIDE; MERCURIC IODIDE; MICROGRAVITY; SYNCHROTRON; TOPOGRAPHY; TRIGLYCINE SULFATE ID TOPOGRAPHY; SPACE AB Irregularities in three crystals grown in space and in four terrestrial crystals grown under otherwise comparable conditions have been observed in high resolution diffraction imaging. The images provide important new clues to the nature and origins of irregularities in each crystal. For two of the materials, mercuric iodide and lead tin telluride, more than one phase (an array of non diffracting inclusions) was observed in terrestrial samples; but the formation of these multiple phases appears to have been suppressed in directly comparable crystals grown in microgravity. The terrestrial seed crystal of triglycine sulfate displayed an unexpected layered structure, which propagated during directly comparable space growth. Terrestrial Bridgman regrowth of gallium arsenide revealed a mesoscopic structure substantially different from that of the original Czochralski material. A directly comparable crystal is to be grown shortly in space. C1 EG&G ENERGY MEASUREMENTS INC, GOLETA, CA 93116 USA. ALABAMA A&M UNIV, HUNTSVILLE, AL 35762 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. GTE LABS INC, WALTHAM, MA 02254 USA. LOCKHEED ENGN & SCI CO, HAMPTON, VA USA. RP STEINER, B (reprint author), NATL INST STAND & TECHNOL, MAT SCI & ENGN & LAB, GAITHERSBURG, MD 20899 USA. NR 12 TC 2 Z9 2 U1 0 U2 1 PU US GOVERNMENT PRINTING OFFICE PI WASHINGTON PA SUPERINTENDENT DOCUMENTS,, WASHINGTON, DC 20402-9325 USA SN 1044-677X J9 J RES NATL INST STAN JI J. Res. Natl. Inst. Stand. Technol. PD MAY-JUN PY 1991 VL 96 IS 3 BP 305 EP 331 DI 10.6028/jres.096.017 PG 27 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA FV282 UT WOS:A1991FV28200004 PM 28184117 ER PT J AU CERNY, LC CERNY, EL SUTTER, JK CZERNIAWSKI, D AF CERNY, LC CERNY, EL SUTTER, JK CZERNIAWSKI, D TI VISCOSITY OF CRITICAL MIXTURES - ISOPYCNIC POLYMER BLENDS SO JOURNAL OF RHEOLOGY LA English DT Article ID PHASE-SEPARATION; KINETICS AB In many multicomponent systems, a transition from a single phase of uniform composition to a multiphase state with separated regions of different composition can be induced by changes in temperature and shear. The density difference between the phase and thermal and/or shear gradients within the system results in buoyancy driven convection. These differences affect kinetics of the phase separation if the system has a sufficiently low viscosity. This investigation presents more preliminary developments of a theoretical model in order to describe effects of the buoyancy-driven convection in phase separation kinetics. Polymer solutions were employed as model systems because of the ease with which density differences can be systematically varied and because of the importance of phase separation in the processing and properties of polymeric materials. Isopycnic polymer solutions were used to determine the viscosity and density difference limits for polymer phase separation. From these methods, it was possible to examine polymer-polymer interactions in a theta solvent. The rheological measurements were extended to detect the phase separation and to define the critical temperature. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. PENN STATE UNIV,UNIVERSITY PK,PA 16802. RP CERNY, LC (reprint author), SYRACUSE UNIV,UTICA COLL,UTICA,NY 13502, USA. NR 25 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 0148-6055 J9 J RHEOL JI J. Rheol. PD MAY PY 1991 VL 35 IS 4 BP 525 EP 537 DI 10.1122/1.550179 PG 13 WC Mechanics SC Mechanics GA FL011 UT WOS:A1991FL01100004 ER PT J AU SEIFF, A AF SEIFF, A TI ATMOSPHERES OF EARTH, MARS, AND VENUS, AS DEFINED BY ENTRY PROBE EXPERIMENTS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCES MEETING CY JAN 09-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB In 1963, it was proposed that small spacecraft be sent to Mars and Venus to define the structure of their atmospheres. The capabilities of such atmospheric probes were demonstrated by the Planetary Atmosphere Experiments Test in the Earth's atmosphere in 1971. The techniques developed were subsequently applied in experiments on the Viking Landers at Mars in 1976 and at Venus on the four Pioneer Venus Probes in 1978. The Mars and Venus results made major contributions to the current working definition of these atmospheres. They yielded not only the first-order parameters of atmospheric structure, i.e., the profiles of temperature, pressure, and density with altitude, but also insights into some basic meteorological conditions in those atmospheres, such as atmospheric stability, the presence of waves and turbulence, and the evaluation of thermal contrasts on a global scale. This paper reviews the results obtained from these experiments and outlines the concepts and approaches employed. RP SEIFF, A (reprint author), NASA,AMES RES CTR,SAN JOSE STATE UNIV,DEPT METEOROL,MAIL STOP 245-1,MOFFETT FIELD,CA 94035, USA. NR 31 TC 7 Z9 7 U1 0 U2 5 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 MAY-JUN PY 1991 VL 28 IS 3 BP 265 EP 275 DI 10.2514/3.26240 PG 11 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600001 ER PT J AU KOONTZ, SL ALBYN, K LEGER, LJ AF KOONTZ, SL ALBYN, K LEGER, LJ TI ATOMIC OXYGEN TESTING WITH THERMAL ATOM SYSTEMS - A CRITICAL-EVALUATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SPACE STATION AB The use of thermal atom (kinetic energy near 0.04 eV) test method as a materials selection and screening technique for low-Earth-orbit (LEO) spacecraft is critically evaluated in this paper. The physics and chemistry of the thermal atom environments are shown to produce specific mass loss rate (mg cm-2 min-1) and reaction efficiencies (Re) radically different from those produced in the LEO environment. A response surface study shows that specific mass loss rates change rapidly with plasma-asher parameters and seldom agree with flight data. FEP Teflon is shown to react by a different mechanism than Kapton, polyethylene, or graphite. The Re (Re = volume of material removed per oxygen atom) of Kapton, polyethylene, Mylar, Tedlar, FEP Teflon, and graphite measured in a flowing afterglow apparatus are 10(-3) to 10(-4) those measured with high-energy atoms (kinetic energy 1.5 eV or greater) in beam systems or in LEO. The effect of sample temperature and atom impact energy on Re is discussed. A simple kinetic model describing the reaction of atomic oxygen with polymer surfaces is developed. Guidelines and recommendations for thermal atom testing and interpretation of test results are presented. RP KOONTZ, SL (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,MAT BRANCH,HOUSTON,TX 77058, USA. NR 81 TC 89 Z9 90 U1 0 U2 7 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 MAY-JUN PY 1991 VL 28 IS 3 BP 315 EP 323 DI 10.2514/3.26246 PG 9 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600007 ER PT J AU DAUGHTRIDGE, S GARRETT, HB WHITTLESEY, A AF DAUGHTRIDGE, S GARRETT, HB WHITTLESEY, A TI ENVIRONMENT-INDUCED ANOMALIES ON THE TDRS AND THE ROLE OF SPACECRAFT CHARGING SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCES MEETING CY JAN 09-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB The Tracking and Data Relay Satellites TDRS-A (F-1), TDRS-C (F-3), and TDRS-D (F-4) have all experienced environment-induced anomalies. These anomalies were determined to be related to spacecraft charging based on their occurrence frequency, distribution in local time, and the environment at the time of the anomalies. One type of anomaly occurring in F-1 is believed to be the result of buried charging with shadowing from the spacecraft's antennas being the discharge trigger mechanism. The circuitry in the F-3 and F-4 spacecraft were modified to make them immune to this type of anomaly. However, F-3 and then F-4 both suffered a second type of anomaly also attributed to buried charging effects. In addition, F-1 and F-3 have experienced a third type of anomaly that appears to be associated with surface charging. These anomalies, the local plasma environment, and their relationship to spacecraft charging are discussed. C1 CONTEL FED SYST,CHANTILLY,VA 22021. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 20 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 MAY-JUN PY 1991 VL 28 IS 3 BP 324 EP 329 DI 10.2514/3.26247 PG 6 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600008 ER PT J AU KESSLER, DJ AF KESSLER, DJ TI ORBITAL DEBRIS ENVIRONMENT FOR SPACECRAFT IN LOW EARTH ORBIT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID COLLISION AB The results of measurements and modeling have been combined to describe an orbital debris environment model that can be used to evaluate spacecraft reliability vs shielding issues. Recent measurements by ground radars and telescopes, combined with analysis of recovered spacecraft surfaces, have provided some measurements of the environment over most of the size spectrum from micron size to the size of spacecraft. These measurements are consistent with models that assumed that smaller debris resulted from the breakup of satellites. Recent efforts to minimize satellite breakups will reduce the projected environment and delay the time period when satellite breakups from random collisions become important. However, there still remains a significant uncertainty in the current environment, and an even larger uncertainty in the projected environment. Uncertainties in the current environment will be reduced as a result of planned measurements. The future environment will mostly depend on future debris control measures taken and, to a lesser extent, on the amount of traffic to orbit. RP KESSLER, DJ (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,ORBITAL DEBRIS RES,HOUSTON,TX 77058, USA. NR 19 TC 10 Z9 14 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 MAY-JUN PY 1991 VL 28 IS 3 BP 347 EP 351 DI 10.2514/3.26250 PG 5 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600011 ER PT J AU MARTIN, JA AF MARTIN, JA TI TITAN IMPROVEMENT STUDY - HYDROGEN CORE STAGES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note RP MARTIN, JA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1991 VL 28 IS 3 BP 356 EP 358 DI 10.2514/3.26253 PG 3 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600014 ER PT J AU ZOBY, EV LEE, KP GUPTA, RN AF ZOBY, EV LEE, KP GUPTA, RN TI HYPERSONIC NONEQUILIBRIUM VISCOUS SOLUTIONS OVER SLENDER BODIES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 VIGYAN RES ASSOCIATES INC,HAMPTON,VA 23666. RP ZOBY, EV (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 5 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 MAY-JUN PY 1991 VL 28 IS 3 BP 358 EP 360 DI 10.2514/3.26254 PG 3 WC Engineering, Aerospace SC Engineering GA FY766 UT WOS:A1991FY76600015 ER PT J AU BOWDEN, CM POSTAN, A INGUVA, R AF BOWDEN, CM POSTAN, A INGUVA, R TI INVARIANT PULSE-PROPAGATION AND SELF-PHASE MODULATION IN DENSE MEDIA SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID MIRRORLESS OPTICAL BISTABILITY; LOCAL-FIELD CORRECTION; 2-LEVEL ATOMS; INDUCED TRANSPARENCY; TRANSITION; SUPERFLUORESCENCE; SYSTEM AB Analytical solutions for the slowly varying phase as well as the field amplitude are obtained for invariant pulse propagation in resonant absorbing media consisting of interacting two-level atoms. Such media, having many atoms within a cubic wavelength, have been shown to exhibit large frequency chirps in pulse propagation owing to near-dipole-dipole interactions. Departures from hyperbolic-secant pulse envelopes and pulse areas other than 2-pi have been shown to occur in invariant pulse propagation. We show that self-phase modulation results from the near-dipole-dipole interactions and can cause strong modification of pulse shapes, including temporal narrowing and multipulse behavior. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP BOWDEN, CM (reprint author), USA,MISSILE COMMAND,CTR RES DEV & ENGN,AMSMI RD WS,WEAPONS SCI DIRECTORATE,REDSTONE ARSENAL,AL 35898, USA. NR 15 TC 41 Z9 42 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD MAY PY 1991 VL 8 IS 5 BP 1081 EP 1084 DI 10.1364/JOSAB.8.001081 PG 4 WC Optics SC Optics GA FL116 UT WOS:A1991FL11600024 ER PT J AU LEVENSON, LL STAN, M BHASIN, KB AF LEVENSON, LL STAN, M BHASIN, KB TI PROPERTIES OF LARGE AREA ERBA2CU3O7-X THIN-FILMS DEPOSITED BY IONIZED CLUSTER BEAMS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 37TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY OCT 08-12, 1990 CL TORONTO, CANADA SP AMER VACUUM SOC ID EPITAXIAL-GROWTH; TEMPERATURE; SUBSTRATE AB ErBa2Cu3O7-x films have been produced by simultaneous deposition of Er, Ba, and Cu from three ionized cluster beam (ICB) sources at acceleration voltages of 0.3-0.5 kV. Combining ozone oxidation with ICB deposition at 650-degrees-C eliminated any need of post anneal processing. The substates were rotated at 10 rotations per minute during the deposition which took place at a rate of about 3 to 4 nm. ErBa2Cu3O7-x films with areas up to 70 mm in diameter have been made by ICB deposition. These films, 100-nm thick, were deposited on SrTiO3 (100) substrates at 650-degrees-C in a mixture of 6 at. % O3 in O2 at a total pressure of 4 X 10(-4) Torr. They had T(c) ranging from 84.3 to 86.8 K over a 70 mm diameter and J(c) above 10(6) A/cm2 at 77 K. Another set of three samples, deposited within a 50 mm diameter, was examined by magnetization measurements. These samples had J(c) ranging from 8.2 X 10(6) to 1.1 X 10(7) A/cm2 at 4.2 K and from 2.4 X 10(5) to 5.1 X 10(5) A/cm2 at 70 K. X-ray diffraction measurements of the three samples showed preferential c-axis orientation normal to the substrate surface. Rocking curves showed small variation in grain misorientation with sample position relative to the center of the substrate holder. Scanning electron micrographs (SEM) of the three samples also show some texture dependence on sample position. For the three samples, there is a correlation between SEM texture, full width at half-maximum of rocking curves and J(c) versus temperature curves. C1 NASA,LEWIS RES CTR,NATL AERONAUT & SPACE ADM,CLEVELAND,OH 44135. RP LEVENSON, LL (reprint author), UNIV COLORADO,DEPT PHYS & ENERGY SCI,COLORADO SPRINGS,CO 80933, USA. NR 12 TC 3 Z9 3 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1991 VL 9 IS 3 BP 405 EP 408 DI 10.1116/1.577422 PN 1 PG 4 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA FR761 UT WOS:A1991FR76100006 ER PT J AU VASQUEZ, RP FOOTE, MC HUNT, BD BAJUK, L AF VASQUEZ, RP FOOTE, MC HUNT, BD BAJUK, L TI CHEMICAL NATURE OF THE BARRIER IN PB/YBA2 CU3 O7-X TUNNELING STRUCTURES SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 37TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY OCT 08-12, 1990 CL TORONTO, CANADA SP AMER VACUUM SOC ID SINGLE-CRYSTALS; THIN-FILMS; SUPERCONDUCTING YBA2CU3O7; JUNCTIONS; SURFACES; Y1BA2CU3O7; PLANES; OXYGEN; WATER AB Several reports of reproducible tunneling measurements on YBa2Cu3O7-x thin films or single crystals with a Pb counterelectrode have recently appeared. The nature of the tunnel barrier, formed by air exposure, in these structures has been unknown. In the present work, the chemical nature of the tunnel barrier is studied with x-ray photoelectron spectroscopy (XPS). Laser-ablated films grown on LaAlO3 which have been chemically etched and heated in air are found to form nonsuperconducting surface Ba species, evident in an increase of the high binding energy Ba 3d and O 1s signals. A deposited Pb film approximately 10 angstrom thick is found to be oxidized, and Cu + 2 is partially reduced to Cu+1. The tunneling barrier thus appears to consist of species resulting from a combination of the air exposure and a reaction between the superconductor and the deposited Pb counterelectrode. RP VASQUEZ, RP (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 21 TC 11 Z9 11 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1991 VL 9 IS 3 BP 570 EP 573 DI 10.1116/1.577411 PN 1 PG 4 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA FR761 UT WOS:A1991FR76100039 ER PT J AU DAVIDSON, MR HOFLUND, GB OUTLAW, RA AF DAVIDSON, MR HOFLUND, GB OUTLAW, RA TI NONDESTRUCTIVE DEPTH PROFILE STUDY OF OXYGEN-EXPOSED LARGE-GRAIN SILVER USING ANGLE-RESOLVED AUGER-ELECTRON SPECTROSCOPY AND ION-SCATTERING SPECTROSCOPY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 37TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY OCT 08-12, 1990 CL TORONTO, CANADA SP AMER VACUUM SOC ID AG(110); SURFACE; CO2; AG AB The adsorption of oxygen on polycrystalline Ag during exposure to 75 Torr of O2 for 1 h at temperatures ranging from 75 to 250-degrees-C has been examined using ion scattering spectroscopy (ISS) and angle-resolved Auger electron spectroscopy (ARAES). Quantification of these data provide the profile of the O concentration in the near-surface region of the Ag as a function of exposure temperature. The O concentration in the outermost atomic layer increases from 0% according to forward-scattered ISS for the cleaned surface to a maximum value of about 50 at.% for the 250-degrees-C exposure. A very small amount of subsurface O remains on the cleaned Ag surface after prolonged ion sputtering and annealing treatments. The total amount of subsurface O also increases monotonically with dosing temperature and reaches a uniform concentration level of 14 at.% over the region probed by Auger electron spectroscopy (AES). Exposures at higher temperatures (up to 600-degrees-C) results in the same near-surface O concentration profile as the 250-degrees-C exposure. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DAVIDSON, MR (reprint author), UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611, USA. RI Davidson, Mark/C-1135-2009 NR 18 TC 25 Z9 26 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1991 VL 9 IS 3 BP 1344 EP 1350 DI 10.1116/1.577624 PN 2 PG 7 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA FR763 UT WOS:A1991FR76300022 ER PT J AU JAYNE, DT FATEMI, NS WEIZER, VG AF JAYNE, DT FATEMI, NS WEIZER, VG TI AN X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF AUXINY ALLOYS SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 37TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY OCT 08-12, 1990 CL TORONTO, CANADA SP AMER VACUUM SOC ID SENSITIVITY FACTORS; SURFACES AB Four gold-indium alloys have been studied by x-ray photoelectron spectroscopy. The binding energies and intensity ratios of the Au 4f7/2 and In 3d5/2 core levels were determined for the bulk alloy compositions of Au(10% In), Au3In, AuIn, and AuIn2. These values were determined for the native oxides on the materials, for the surfaces prepared by ion bombardment to remove the oxide and for surfaces scraped in situ with a ceramic tool to expose the bulk composition. These results furnish calibration values that allow determination of the composition of thin films of this alloy system. In addition the binding energies add to the data base for understanding the effect of alloying on core level binding energies. As an illustration, these results are used to determine the composition of a series of alloy films formed by incongruent evaporation of an alloy charge. C1 CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOK PK,OH 44142. RP JAYNE, DT (reprint author), NASA,LEWIS RES CTR,MS 23-2,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 19 TC 10 Z9 11 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1991 VL 9 IS 3 BP 1410 EP 1415 DI 10.1116/1.577637 PN 2 PG 6 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA FR763 UT WOS:A1991FR76300035 ER PT J AU TIBBITS, P KARIMI, M IIA, D DALINS, I VIDALI, G AF TIBBITS, P KARIMI, M IIA, D DALINS, I VIDALI, G TI SURFACE DISORDERING OF PB(110) SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article; Proceedings Paper CT 37TH NATIONAL SYMP OF THE AMERICAN VACUUM SOC CY OCT 08-12, 1990 CL TORONTO, CANADA SP AMER VACUUM SOC ID ROUGHENING TRANSITION; DIFFRACTION AB A molecular dynamics simulation of Pb(110), using embedded atom method energy functional and two-body potential derived for the purpose, shows that near 400 K the three surface layers begin to disorder well before the bulk (interior) layers. Transfer of atoms from the first subsurface layer to the surface layer occurs. Disordering propagates beyond the top three layers above 550 K, accompanied by formation of an adlayer and vacancies in the top three layers. Behavior of the two dimensional layer structure factors indicates that disordering is anisotropic. Simulation results are consistent with experimental observations of surface roughening near 400 K and more extensive surface ordering above 525 K. Results are consistent with simulations for Ni and Al. C1 NASA,MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35762. SYRACUSE UNIV,DEPT PHYS,SYRACUSE,NY 13244. RP TIBBITS, P (reprint author), ALABAMA STATE UNIV,CTR IRRADIATION MAT,MONTGOMERY,AL 36195, USA. NR 13 TC 8 Z9 8 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1991 VL 9 IS 3 BP 1937 EP 1941 DI 10.1116/1.577548 PN 2 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA FR763 UT WOS:A1991FR76300129 ER PT J AU GOLUB, MA WYDEVEN, T CORMIA, RD AF GOLUB, MA WYDEVEN, T CORMIA, RD TI ESCA STUDY OF THE EFFECT OF HYDROCARBON CONTAMINATION ON POLY(TETRAFLUORETHYLENE) EXPOSED TO ATOMIC OXYGEN PLASMA SO LANGMUIR LA English DT Note C1 SURFACE SCI LABS,MT VIEW,CA 94043. RP GOLUB, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 3 TC 26 Z9 26 U1 1 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD MAY PY 1991 VL 7 IS 5 BP 1026 EP 1028 DI 10.1021/la00053a034 PG 3 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA FM784 UT WOS:A1991FM78400035 ER PT J AU VARY, A AF VARY, A TI ACOUSTO-ULTRASONICS - RETROSPECTIVE EXHORTATION WITH BIBLIOGRAPHY SO MATERIALS EVALUATION LA English DT Article RP VARY, A (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 22 Z9 23 U1 1 U2 1 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 MAY PY 1991 VL 49 IS 5 BP 581 EP & PG 0 WC Materials Science, Characterization & Testing SC Materials Science GA FL296 UT WOS:A1991FL29600003 ER PT J AU KAUTZ, HE LERCH, BA AF KAUTZ, HE LERCH, BA TI PRELIMINARY INVESTIGATION OF ACOUSTOULTRASONIC EVALUATION OF METAL-MATRIX COMPOSITE SPECIMENS SO MATERIALS EVALUATION LA English DT Article DE ACOUSTO-ULTRASONICS; AEROSPACE; COMPOSITE MATERIAL; INSPECTION; MATERIAL CHARACTERIZATION; NONDESTRUCTIVE EVALUATION; SENSOR; SIGNAL PROCESSING; STIFFNESS; STRESS WAVE; TENSILE PROPERTY; ULTRASONIC TESTING AB Acousto-ultrasonic (AU) measurements were performed on a series of [0]8, [90]8, [+/-30]2s, ]+/-45]2s, [+/-60]2s, [0/90]2s, and [90/0]2s tensile specimens composed of eight laminated layers of continuous, SiC-fiber-reinforced Ti-15-3 matrix. The frequency spectrum was dominated by frequencies of longitudinal wave resonance through the thickness of the specimen at the sending transducer; signal propagation from the sender to the receiver was by shear waves. The magnitude of the frequency spectrum of the AU signal was used for calculating a stress-wave factor (SWF) based upon integrating the spectral distribution function. The SWF was sensitive to fiber-matrix debonding caused by mechanical strain and also to unconstrained thermal cycling. Damage in this metal-matrix composite (MMC) structure due to tensile loading or thermal cycling was detected by this change in the magnitude of the frequency spectrum. A measure of the speed of the AU pulse between the sending transducer and the receiver was obtained by calculating mean time, or first moment, in the time-domain signal. This parameter shows some sensitivity to the stiffness of the tensile specimens. This sensitivity to stiffness needs further study. RP KAUTZ, HE (reprint author), NASA,LEWIS RES CTR,DIV STRUCT,STRUCT INTEGR BRANCH,CLEVELAND,OH 44135, USA. NR 0 TC 14 Z9 15 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 MAY PY 1991 VL 49 IS 5 BP 607 EP 612 PG 6 WC Materials Science, Characterization & Testing SC Materials Science GA FL296 UT WOS:A1991FL29600007 ER PT J AU HALES, SJ MCNELLEY, TR MCQUEEN, HJ AF HALES, SJ MCNELLEY, TR MCQUEEN, HJ TI RECRYSTALLIZATION AND SUPERPLASTICITY AT 300-DEGREES-C IN AN ALUMINUM-MAGNESIUM ALLOY SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID AL-MG ALLOY; MICROSTRUCTURE; EVOLUTION; RECOVERY; STEEL AB Variations in thermomechanical processing (TMP) which regulate the microstructural characteristics and superplastic response of an Al-10Mg-0.1Zr alloy at 300-degrees-C were evaluated. Mechanical property data revealed that the superplastic ductility can be enhanced by simultaneously increasing the total rolling strain, the reduction per pass, and the duration of reheating intervals between passes during isothermal rolling. Texture and microscopy data were consistent with the development of a refined microstructure by recovery-dominated processes, i.e., continuous recrystallization, during the processing. The mechanisms by which a refined substructure can be progressively converted into a fine-grained structure during repeated cycles of deformation and annealing are addressed. A qualitative description of the complex sequence of developments leading to a microstructure better suited to support superplastic response is presented. RP HALES, SJ (reprint author), NASA,LANGLEY RES CTR,ANALYT SERV & MAT INC,HAMPTON,VA 23665, USA. NR 39 TC 89 Z9 89 U1 3 U2 5 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD MAY PY 1991 VL 22 IS 5 BP 1037 EP 1047 DI 10.1007/BF02661097 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA FK357 UT WOS:A1991FK35700008 ER PT J AU THATCHER, JD ROBINSON, RD REES, DE AF THATCHER, JD ROBINSON, RD REES, DE TI THE CHROMOSPHERES OF LATE-TYPE STARS .1. EPSILON ERIDANI AS A TEST CASE OF MULTILINE MODELING SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID MAIN-SEQUENCE STARS; RADIATIVE-TRANSFER PROBLEMS; SODIUM LINE FORMATION; PARTIAL REDISTRIBUTION; STELLAR CHROMOSPHERES; PHYSICAL-PROPERTIES; SOLAR CHROMOSPHERE; COOL STARS; H-ALPHA; PROFILES AB We derive a new model of the lower chromosphere of the dwarf K2 star epsilon Eridani by matching flux profiles of the Ca IR triplet lines lambda-lambda-8498 and 8542, H-alpha and H-beta lines and the Na D lines (all observed simultaneously at the AAT), and the CA II K line (observed by Zarro & Rogers). The coupled non-LTE equations of statistical equilibrium and radiative transfer are solved under the constraint of hydrostatic equilibrium using the Carlsson (1986) code. The extra constraints imposed by data from a large number of lines originating from different but overlapping atmospheric depths imply that previous models need to be changed in the photosphere, in the temperature minimum by raising it and placing it further out in the atmosphere, and by placing the base of the transition zone at log m = - 4.54. Within the framework of the model we find that the Na D lines are an important photospheric diagnostic and that the Ca IR triplet lines can be used to locate the temperature minimum. The computed H-alpha and H-beta depths are highly sensitive constraints on the transition zone gradients and base pressures allowing us to derive a pressure at the base of the transition zone of 0.9 dyn cm-2. C1 COMP SCI CORP, GODDARD SPACE FLIGHT CTR, ASTRON PROGRAM, GREENBELT, MD 20771 USA. CSIRO, DIV RADIO PHYS, EPPING, NSW 2121, AUSTRALIA. RP UNIV SYDNEY, DEPT APPL MATH, SYDNEY, NSW 2006, AUSTRALIA. NR 45 TC 24 Z9 24 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY 1 PY 1991 VL 250 IS 1 BP 14 EP 23 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FJ872 UT WOS:A1991FJ87200003 ER PT J AU BOERS, R MELFI, SH PALM, SP AF BOERS, R MELFI, SH PALM, SP TI COLD-AIR OUTBREAK DURING GALE - LIDAR OBSERVATIONS AND MODELING OF BOUNDARY-LAYER DYNAMICS SO MONTHLY WEATHER REVIEW LA English DT Article ID THERMODYNAMIC STRUCTURE; SEA INTERACTION; ENTRAINMENT; SENSITIVITY; CONVECTION; INVERSION; CLOUDS; TESTS; OCEAN AB Two cold-air outbreaks were studied during the Genesis of Atlantic Lows Experiment. A lidar system was operated to observe the boundary layer evolution and the development of clouds. On the first day (30 January 1986) boundary layer rise was less than 50% of the value for the second day (2 March 1986). On the first day only a thin broken cloud cover formed, while on the second day a thick solid cloud deck formed-although the average moisture content was 60% of that on the first day. A trajectory slab model was employed to simulate the evolution of the layer over the ocean near the east Atlantic shore. The model allows for vertical gradients in conservative variables under neutrally buoyant conditions. The primary effect of these assumptions, which are based on observed thermodynamic profiles, is to reduce cloudiness to be more in line with observations. Boundary layer depth was reasonably well predicted as was sensible and latent heat flux. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 32 TC 9 Z9 9 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 1991 VL 119 IS 5 BP 1132 EP 1150 DI 10.1175/1520-0493(1991)119<1132:CAODGL>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FM548 UT WOS:A1991FM54800002 ER PT J AU DUNBAR, BJ AF DUNBAR, BJ TI A MATERIALS SCIENTIST IN SPACE - 1990 MRS FALL MEETING PLENARY ADDRESS SO MRS BULLETIN LA English DT Article RP DUNBAR, BJ (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 1 Z9 1 U1 1 U2 1 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0883-7694 J9 MRS BULL JI MRS Bull. PD MAY PY 1991 VL 16 IS 5 BP 36 EP 41 PG 6 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA FL295 UT WOS:A1991FL29500004 ER PT J AU THIEBERGER, P STASSINOPOULOS, EG VANGUNTEN, O ZAJIC, V AF THIEBERGER, P STASSINOPOULOS, EG VANGUNTEN, O ZAJIC, V TI HEAVY-ION BEAMS FOR SINGLE-EVENT RESEARCH AT BROOKHAVEN - PRESENT AND FUTURE SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article; Proceedings Paper CT 11TH INTERNATIONAL CONF ON THE APPLICATION OF ACCELERATORS IN RESEARCH AND INDUSTRY CY NOV 05-08, 1990 CL DENTON, TX ID FACILITY AB Since low energy nuclear physics research was discontinued at Brookhaven and replaced by a relativistic heavy ion program, large blocks of time became available at the tandem Van de Graaff facility for technological applications and for research in other areas. The main technological application has been the single event upset (SEU) testing of microelectronic devices, and this activity has been steadily increasing over the last few years. The ion beam requirements for this type of work are discussed and a description is given of methods used for satisfying these requirements at the Brookhaven facility. Available ion species, energies, ranges, LETs and beam intensities, purity and uniformity are discussed. Characteristics are summarized of a sophisticated and extremely user friendly test chamber and associated hardware and software installed at Brookhaven by a coalition of government agencies and made available for general use. The possibility is mentioned of extending SEU testing to higher energies by using heavy ion beams from a booster synchrotron now under construction and from the existing large alternating gradient synchrotron (AGS). Finally a brief discussion is given of compatibility with other programs and of future availability of low and high energy heavy ions for SEU testing at Brookhaven. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LAB PHYS SCI,COLLEGE PK,MD. RP THIEBERGER, P (reprint author), BROOKHAVEN NATL LAB,UPTON,NY 11973, USA. NR 13 TC 6 Z9 7 U1 0 U2 0 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 MAY PY 1991 VL 56-7 BP 1251 EP 1255 DI 10.1016/0168-583X(91)95144-3 PN 2 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA FQ890 UT WOS:A1991FQ89000144 ER PT J AU LIU, DTH CHENG, LJ AF LIU, DTH CHENG, LJ TI RESOLUTION OF A TARGET-TRACKING OPTICAL NOVELTY FILTER SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL NOVELTY FILTERS; PHASE-CONJUGATE INTERFEROMETERS; PHOTOREFRACTIVE EFFECT; SPACE-BANDWIDTH PRODUCT ID GAAS; INTERFEROMETER; CRYSTALS AB The resolution of a target-tracking optical novelty filter is discussed in terms of the response time of the nonlinear medium, the speed of the target, and the resolution of the input device. Optical novelty filters using a faster nonlinear medium may have a higher output resolution. This is particularly true in the case of tracking high-speed targets. The potential of implementing high-resolution optical novelty filters using photorefractive GaAs is investigated experimentally. RP LIU, DTH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 8 Z9 8 U1 0 U2 1 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAY PY 1991 VL 30 IS 5 BP 571 EP 576 DI 10.1117/12.55844 PG 6 WC Optics SC Optics GA FK496 UT WOS:A1991FK49600010 ER PT J AU SCHOLL, MS WANG, Y RANDOLPH, JE AYON, JA AF SCHOLL, MS WANG, Y RANDOLPH, JE AYON, JA TI SITE-CERTIFICATION IMAGING SENSOR FOR THE EXPLORATION OF MARS SO OPTICAL ENGINEERING LA English DT Article DE HIGH-RESOLUTION IMAGING; REMOTE SENSING; LANDING SITE CERTIFICATION AB A "time dilation" push-broom imaging charge-coupled device (CCD) sensor is being considered for certification of landing and roving sites for the exploration of Mars. It will be used to certify several 10 x 10 km candidate sites and to identify rocks and holes of 1 m or larger at those sites, using an optical sensor with 0.25 m resolution. This will require a high-resolution large-aperture camera and a camera-pointing system designed for high accuracy and stability. To reduce the data rate and increase the exposure time, the imaging time will be stretched out by a factor of eight over the time required to fly directly over the imaged site. Six parallel data storage strings will be used to reduce the data acquisition rate, allowing each string to process a manageable 25 Mb/s. RP SCHOLL, MS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 20 TC 15 Z9 15 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 MAY PY 1991 VL 30 IS 5 BP 590 EP 597 PG 8 WC Optics SC Optics GA FK496 UT WOS:A1991FK49600012 ER PT J AU TOWNSEND, LW NORBURY, JW KHAN, F AF TOWNSEND, LW NORBURY, JW KHAN, F TI CALCULATIONS OF HADRONIC DISSOCIATION OF SI-28 PROJECTILES AT 1496A GEV BY NUCLEON EMISSION SO PHYSICAL REVIEW C LA English DT Note ID HEAVY-ION FRAGMENTATION; CROSS-SECTIONS; ELECTROMAGNETIC DISSOCIATION; MODEL; COLLISIONS AB An optical potential abrasion-ablation collision model is used to calculate hadronic dissociation cross sections for one, two, and three nucleon removal for the first time for a 14.6A GeV Si-28 beam fragmenting in aluminum, tin, and lead targets. These estimates are compared with recent semi-inclusive measurements. Significant differences between some calculated and measured semi-inclusive cross sections exist which cannot be resolved without measurements of the exclusive channel hadronic cross sections. Calculations for each exclusive reaction channel contributing to the semi-inclusive cross sections are presented and discussed. C1 RIDER COLL,DEPT PHYS,LAWRENCEVILLE,NJ 08648. OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529. RP TOWNSEND, LW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 23 TC 4 Z9 4 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD MAY PY 1991 VL 43 IS 5 BP R2045 EP R2048 PG 4 WC Physics, Nuclear SC Physics GA FL895 UT WOS:A1991FL89500005 ER PT J AU MALIK, MR ANDERSON, EC AF MALIK, MR ANDERSON, EC TI REAL-GAS EFFECTS ON HYPERSONIC BOUNDARY-LAYER STABILITY SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID TRANSITION; VORTICES AB High-temperature effects alter the physical and transport properties of a gas, air in particular, due to vibrational excitation and gas dissociation, and thus the chemical reactions have to be considered in order to compute the flow field. Linear stability of high-temperature boundary layers is investigated under the assumption of chemical equilibrium and this gas model is labeled here as "real gas model." In this model, the system of stability equations remains of the same order as for the perfect gas and the effect of chemical reactions is introduced only through mean flow and gas property variations. Calculations are performed for Mach 10 and 15 boundary layers and the results indicate that real gas effects cause the first mode instability to stabilize while the second mode is more unstable. It is also found that the second mode instability shifts to lower frequencies. There is a slight destabilizing influence of real gas on the Goertler instability as compared to the perfect gas results. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP MALIK, MR (reprint author), HIGH TECHNOL CORP,POB 7262,HAMPTON,VA 23666, USA. NR 35 TC 35 Z9 37 U1 0 U2 13 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 MAY PY 1991 VL 3 IS 5 BP 803 EP 821 DI 10.1063/1.858012 PN 1 PG 19 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FL370 UT WOS:A1991FL37000009 ER PT J AU ANTONIA, RA KIM, J AF ANTONIA, RA KIM, J TI SIMILARITY BETWEEN TURBULENT KINETIC-ENERGY AND TEMPERATURE SPECTRA IN THE NEAR-WALL REGION SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Note ID VELOCITY FLUCTUATIONS; BOUNDARY-LAYER; ANALOGY; FLOWS AB The similarity between turbulent kinetic energy and temperature spectra, previously confirmed using experimental data in various turbulent shear flows, is validated in the near-wall region using direct numerical simulation data in a fully developed turbulent channel flow. The dependence of this similarity on the molecular Prandtl number is also examined. 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 15 TC 2 Z9 2 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 MAY PY 1991 VL 3 IS 5 BP 989 EP 991 DI 10.1063/1.857978 PN 1 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FL370 UT WOS:A1991FL37000029 ER PT J AU MOSER, RD ROGERS, MM AF MOSER, RD ROGERS, MM TI MIXING TRANSITION AND THE CASCADE TO SMALL SCALES IN A PLANE MIXING LAYER SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID PERIODIC SHEAR-LAYER; 3-DIMENSIONAL INSTABILITIES; DETERMINISTIC MODELS; STREAMWISE VORTICES; TURBULENT-FLOW AB Direct numerical simulations of time-developing plane mixing layers have been performed using a variety of initial conditions. Up to two pairings of the dominant spanwise rollers have been simulated. When the flow is sufficiently three dimensional, a pairing can cause the mixing layer to undergo a transition to small-scale turbulence. This small-scale transition is accompanied by increased mixing of a passive scalar, similar to observations of the mixing transition in experiments. As part of the transition process, thin vortex sheets are generated by vortex stretching and roll up as in a two-dimensional mixing layer. This higher-order rollup is part of the cascade to small-scale turbulence. Estimates are obtained for the degree of three-dimensionality required for the pairing to initiate the transition. RP MOSER, RD (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 20 TC 94 Z9 96 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAY PY 1991 VL 3 IS 5 BP 1128 EP 1134 DI 10.1063/1.858094 PN 2 PG 7 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FL372 UT WOS:A1991FL37200016 ER EF