FN Thomson Reuters Web of Science™ VR 1.0 PT J AU LANGER, WD VELUSAMY, T KUIPER, TBH LEVIN, S OLSEN, E MIGENES, V AF LANGER, WD VELUSAMY, T KUIPER, TBH LEVIN, S OLSEN, E MIGENES, V TI STUDY OF STRUCTURE AND SMALL-SCALE FRAGMENTATION IN TMC-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, CLOUDS; ISM, INDIVIDUAL (TAURUS MOLECULAR CLOUD); ISM, MOLECULES; STARS, FORMATION; RADIO LINES, ISM ID MOLECULAR CLOUD-1 TMC-1; INTER-STELLAR CLOUDS; DARK CLOUDS; DENSE CORES; CARBON-MONOXIDE; STAR FORMATION; TAURUS; TURBULENCE; LINE; NH3 AB Large-scale (CO)-O-18 maps show that the Taurus molecular cloud 1 (TMC-1) has numerous cores located along a ridge which extends about 12' by at least 35'. The cores traced by (CO)-O-18 are about a few arcminutes (0.1-0.2 pc) in extent, typically contain about 0.5-3 M., and are probably gravitationally bound. We present a detailed study of the small-scale fragmentary structure of one of these cores, called core D, within TMC-1 using very high spectral and spatial resolution maps of CCS and CS. The CCS lines are excellent tracers for investigating the density, temperature, and velocity structure in dense cores. The high spectral resolution, 0.008 km s(-1), data consist mainly of single-dish, Nyquist-sampled maps of CCS at 22 GHz with 45 '' spatial resolution taken with NASA's 70 m DSN antenna at Goldstone. The high spatial resolution spectral line maps were made with the Very Large Array (9 '' resolution) at 22 GHz and with the OVRO millimeter array in CCS and CS at 93 GHz and 98 GHz, respectively, with 6 '' resolution. These maps are supplemented with single-dish observations of CCS and (CCS)-S-34 spectra at 33 GHz using a NASA 34 m DSN antenna, CCS 93 GHz, (CS)-S-34 (2-1), and (CO)-O-18 (1-0) single-dish observations made with the AT&T Bell Laboratories 7 m antenna. Our high spectral and spatial CCS and CS maps show that core D is highly fragmented. The single-dish CCS observations map out several clumps which range in size from similar to 45 '' to 90 '' (0.03-0.06 pc). These clumps have very narrow intrinsic line widths, 0.11-0.25 km s(-1), slightly larger than the thermal line width for CCS at 10 K, and masses about 0.03-0.2 M.. Interferometer observations of some of these clumps show that they have considerable additional internal structure, consisting of several condensations ranging in size from similar to 10 ''-30 '' (0.007-0.021 pc), also with narrow line widths. The mass of these smallest fragments is of order 0.01 M.. These small-scale structures traced by CCS appear to be gravitationally unbound by a large factor. Most of these objects have masses that fall below those of the putative proto-brown dwarfs (less than or similar to 0.1 M.). The presence of many small gravitationally unbound clumps suggests that fragmentation mechanisms other than a purely Jeans gravitational instability may be important for the dynamics of these cold dense cores. C1 CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. TATA INST FUNDAMENTAL RES,BOMBAY 400005,MAHARASHTRA,INDIA. RP LANGER, WD (reprint author), CALTECH,JET PROP LAB,MS 169-506,PASADENA,CA 91109, USA. RI Migenes, Victor/F-3157-2015 OI Migenes, Victor/0000-0002-7990-2191 NR 51 TC 91 Z9 91 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 NOV 1 PY 1995 VL 453 IS 1 BP 293 EP 307 DI 10.1086/176389 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300027 ER PT J AU CURIEL, S RAYMOND, JC WOLFIRE, M HARTIGAN, P MORSE, J SCHWARTZ, RD NISENSON, P AF CURIEL, S RAYMOND, JC WOLFIRE, M HARTIGAN, P MORSE, J SCHWARTZ, RD NISENSON, P TI MOLECULAR H-2 EMISSION IN HH 47A - HUBBLE-SPACE-TELESCOPE GHRS AND FOC OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (HH 47); ISM, JETS AND OUTFLOWS; MOLECULAR PROCESSES; SHOCK WAVES; STARS, PRE-MAIN-SEQUENCE ID HERBIG-HARO OBJECTS; ULTRAVIOLET CONTINUUM; INFRARED-EMISSION; HYDROGEN EMISSION; HIGH-RESOLUTION; LINE EMISSION; SHOCK-MODELS; H2 EMISSION; CLOUDS; JET AB We present Hubble Space Telescope ultraviolet observations of the bow shock at the end of the HH 47 stellar jet obtained with the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Camera (FOG). The GHRS spectrum shows three prominent emission lines of H-2 which are produced by Ly alpha fluorescence and one line that we cannot identify. Fluorescence from Ly alpha generated in the bow shock and Mach disk of HH 47A can account for the observed H-2 line fluxes provided that the H, absorbs about one-third of these Ly alpha photons. We find that our FOC image of HH 47A is made up of about 70% hydrogen two-photon continuum and about 30% fluorescent H-2 emission. This image closely resembles optical [S II] and H alpha images of HH 47A but differs significantly from H, images of the region taken at near-infrared wavelengths. This is because the two-photon continuum and the Ly alpha photons which drive H-2 fluorescence both originate in the Hat-emitting gas, and the Ly alpha mean free path is small. The presence of molecular hydrogen in HH 47A is difficult to understand. If the H-2 forms in a dense region between the bow shock and the Mach disk, then the emission should be significantly more blueshifted than observed. Models that excite H-2 using C-shocks or magnetic precursors assume that molecular hydrogen exists in the preshock gas of HH 47A. However, this gas lies within the wake of a previous high-velocity ejection from the star and is exposed to ionizing radiation from the Gum Nebula, so we would not expect to find any H-2 in this region. Numerical calculations indicate that the UV H-2 line emission may be produced by either reformed H-2 molecules in the region between the bow shock and the Mach disk or from a C-shock or magnetic precursor, while the near-infrared H-2 emission observed in HH 47A arises mainly from C-shock or magnetic precursor along the wings of the bow shock. We propose that the scenario that best explains the current results is one in which the HH 47A bow shock is running into a clump of molecular gas which could be either comoving with the preshock gas or nearly stationary with respect to the ambient cloud, primary on its more distant face. C1 HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RICE UNIV, HOUSTON, TX 77251 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. UNIV MISSOURI, DEPT PHYS & ASTRON, ST LOUIS, MO 63121 USA. NR 30 TC 32 Z9 32 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 NOV 1 PY 1995 VL 453 IS 1 BP 322 EP 331 DI 10.1086/176392 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300030 ER PT J AU KASPI, VM TAVANI, M NAGASE, F HIRAYAMA, M HOSHINO, M AOKI, T KAWAI, N ARONS, J AF KASPI, VM TAVANI, M NAGASE, F HIRAYAMA, M HOSHINO, M AOKI, T KAWAI, N ARONS, J TI X-RAY-DETECTION OF PSR B1259-63 AT PERIASTRON SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, ECLIPSING; PULSARS, INDIVIDUAL (PSR B1259-63); STARS, EMISSION-LINE, BE; STARS, NEUTRON; X-RAYS, STARS ID RADIO PULSAR; EMISSION; STARS; SHOCK; WINDS; CONFINEMENT; COMPANION; REMNANT; NEBULA; OB AB We report on results of X-ray observations of the unique radio pulsar/Be star binary PSR B1259-63, obtained using the ASCA satellite 2 weeks before, during, and 2 weeks after the pulsar's most recent periastron passage on 1994 January 9. The source was detected at all three epochs, with an X-ray luminosity in the 1-10 keV band of similar to 1 x 10(34)(d/2 kpc)(2) ergs s(-1) at the pre- and postperiastron epochs, and a factor of similar to 2 smaller at periastron. The X-ray emission can be characterized by power-law spectra with a photon index in the range 1.5-1.9, with evidence for spectral softening at periastron. The photoelectric absorption, N-H similar to 5 x 10(21) cm(-2), was constant for the three observations within measurement uncertainties and is consistent with the Galactic contribution. We detect no pulsations and derive an upper limit on periodicities close to the PSR B1259-63 spin period of similar to 7% of the total observed flux, conservatively assuming a sine wave profile. We argue that accretion of gaseous material onto the surface of the neutron star is an unlikely origin for the observed X-rays. The characteristics of the X-ray emission from the PSR B1259-63 system are in good qualitative agreement with models of nonthermal acceleration of relativistic particles from the pulsar wind in a shock at the location at which the pulsar and Be star wind pressures balance. Assuming reasonable Be star equatorial outflow and pulsar wind pressures, we find that the mass-loss rate M and surface velocity v are constrained by the relation 100 less than or similar to (v/10 km s(-1))(M/10(-8) M. yr(-1)) less than or similar to 10(4). C1 COLUMBIA UNIV,ASTROPHYS LAB,NEW YORK,NY 10027. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. INST PHYS & CHEM RES,WAKO,SAITAMA 35101,JAPAN. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. RP KASPI, VM (reprint author), CALTECH,JET PROP LAB,IPAC,4800 OAK GROVE DR,PASADENA,CA 91125, USA. OI Tavani, Marco/0000-0003-2893-1459 NR 55 TC 52 Z9 52 U1 2 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1995 VL 453 IS 1 BP 424 EP 432 DI 10.1086/176403 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300041 ER PT J AU HOWELL, SB SZKODY, P SONNEBORN, G FRIED, R MATTEI, J OLIVERSEN, RJ INGRAM, D HURST, GM AF HOWELL, SB SZKODY, P SONNEBORN, G FRIED, R MATTEI, J OLIVERSEN, RJ INGRAM, D HURST, GM TI ULTRAVIOLET OBSERVATIONS OF SW-URSAE-MAJORIS, BC-URSAE-MAJORIS, AND TV-CORVI (1217-18) - IUE SPECTROSCOPY AND OUTBURST LIGHT CURVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (SW URSAE MAJORIS, BC URSAE MAJORIS, TV CORVI) ID QUASI-PERIODIC OSCILLATIONS; CATACLYSMIC VARIABLES; DWARF; SUPEROUTBURST; PHOTOMETRY; DISCOVERY; BEHAVIOR AB We present IUE superoutburst observations of three tremendous outburst amplitude dwarf novae. Limited ground-based optical photometry was also obtained contemporaneously. This is the first such ultraviolet spectroscopy of these systems, and we compare our results with other well-studied dwarf novae of similar orbital periods. We find that the slope of the ultraviolet spectra are similar to that for typical dwarf novae during normal outburst but are slightly bluer than other short-period systems at superoutburst. Complex line profiles exist and show large wind velocities which exceed the white dwarf escape velocity and are at or above the largest velocities seen in normal dwarf novae. We also present an observational summary of the outburst lightcurves of SW UMa and how these may be related to other large outburst dwarf novae. C1 UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. BRAESIDE OBSERV,FLAGSTAFF,AZ 86002. AMER ASSOC VARIABLE STAR OBSERVERS,CAMBRIDGE,MA 02138. ASTRON GRP,BASINGSTOKE RG22 4PP,HANTS,ENGLAND. RP HOWELL, SB (reprint author), PLANETARY SCI INST,ASTROPHYS GRP,620 N 6TH AVE,TUCSON,AZ 85705, USA. NR 33 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1995 VL 453 IS 1 BP 454 EP 463 DI 10.1086/176407 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300045 ER PT J AU WANG, H GARY, DE ZIRIN, H SCHWARTZ, RA SAKAO, T KOSUGI, T SHIBATA, K AF WANG, H GARY, DE ZIRIN, H SCHWARTZ, RA SAKAO, T KOSUGI, T SHIBATA, K TI COORDINATED OVRO, BATSE, YOHKOH, AND BBSO OBSERVATIONS OF THE 1992 JUNE 25 M1.4 FLARE SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, FLARES; SUN, MAGNETIC FIELDS; SUN, RADIO RADIATION; SUN, X-RAYS, GAMMA RAYS ID X-RAY OBSERVATIONS; SOLAR-A MISSION; ELECTRONS; TELESCOPE; EMISSION AB We compare 1-14 GHz microwave images observed at the Owens Valley Radio Observatory (OVRO), 16-and 256-channel hard X-ray spectra obtained by the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO), soft and and hard X-ray images obtained by Yohkoh, and Ha images and magnetograms observed at the Big Bear Solar Observatory (BBSO) for the 1992 June 25 M1.4 flare. We find the following unique properties for this hare: (1) Soft X-ray emissions connect two footpoints, the primary microwave source is located at one footpoint, and hard X-ray emissions are concentrated in the other footpoint. The radio footpoint is associated with an umbra and may have stronger magnetic field. (2) During the period that 256-channel BATSE data are available, the hard X-ray photon spectrum consists of two components: a superhot component with a temperature of 8.4 x 10(7) K and emission measure of 2.5 x 10(46) cm(-3) and a power-law component with a photon index of 4.2. This is the first time that such a high temperature is reported for the hard X-ray thermal components. It is even more interesting that such a superhot component is identified before the peak of the hare. The microwave brightness temperature spectra during the same period also demonstrate two components.: a thermal component near the loop top and a nonthermal component at the footpoint of the loop. The microwave thermal component has the similar temperature as that of the hard X-ray superhot component. These measurements are consistent with the theory that the microwaves and hard X-rays are due to the same group of electrons, despite the fact that they are separated by 35,000 km. (3) The soft X-ray emissions brighten the existing loops and co-align with H alpha emissions throughout the entire duration of the flare. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NATL ASTRON OBSERV, MITAKA, TOKYO 181, JAPAN. RP WANG, H (reprint author), CALTECH, BIG BEAR SOLAR OBSERV, PASADENA, CA 91125 USA. OI Gary, Dale/0000-0003-2520-8396 NR 19 TC 32 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 1995 VL 453 IS 1 BP 505 EP + DI 10.1086/176411 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300049 ER PT J AU TREUHAFT, RN LOWE, ST BESTER, M DANCHI, WC TOWNES, CH AF TREUHAFT, RN LOWE, ST BESTER, M DANCHI, WC TOWNES, CH TI VERTICAL SCALES OF TURBULENCE AT THE MOUNT-WILSON-OBSERVATORY SO ASTROPHYSICAL JOURNAL LA English DT Article DE EARTH; TECHNIQUES, INTERFEROMETRIC; TURBULENCE AB The vertical scales of turbulence at the Mount Wilson Observatory are inferred from data from the University of California at Berkeley Infrared Spatial Interferometer (ISI), by modeling path length fluctuations observed in the interferometric paths to celestial objects and those in instrumental ground-based paths. The correlations between the stellar and ground-based path length fluctuations and the temporal statistics of those fluctuations are modeled on various timescales to constrain the vertical scales. A Kolmogorov-Taylor turbulence model with a finite outer scale was used to simulate ISI data. The simulation also included the white instrumental noise of the interferometer, aperture-filtering effects, and the data analysis algorithms. The simulations suggest that the path delay fluctuations observed in the 1992-1993 ISI data are largely consistent with being generated by refractivity fluctuations at two characteristic vertical scales: one extending to a height of 45 m above the ground, with a wind speed of about 1 m s(-1), and another at a much higher altitude, with a wind speed of about 10 m s(-1). The height of the lower layer is of the order of the dimensions of trees and other structures near the interferometer, which suggests that these objects, including elements of the interferometer, may play a role in generating the lower layer of turbulence. The modeling indicates that the high-altitude component contributes primarily to short-period (less than 10 s) fluctuations, while the lower component dominates the long-period (up to a few minutes) fluctuations. The lower component turbulent height, along with outer scales of the order of 10 m, suggest that the baseline dependence of long-term interferometric, atmospheric fluctuations should weaken for baselines greater than a few tens of meters. Simulations further show that there is the potential for improving the seeing or astrometric accuracy by about 30%-50% on average, if the path length fluctuations in the lower component are directly calibrated. Statistical and systematic effects induce an error of about 15 m in the estimate of the lower component turbulent altitude. C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. RP TREUHAFT, RN (reprint author), CALTECH,JET PROP LAB,MS 300-235,PASADENA,CA 91109, USA. NR 5 TC 7 Z9 7 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 NOV 1 PY 1995 VL 453 IS 1 BP 522 EP & DI 10.1086/176414 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB033 UT WOS:A1995TB03300052 ER PT J AU MUSIELAK, ZE PORTER, JG DAVIS, JM AF MUSIELAK, ZE PORTER, JG DAVIS, JM TI ROSAT POINTED OBSERVATIONS OF COOL MAGNETIC WHITE-DWARFS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, CORONAE; WHITE DWARFS; X-RAYS, STARS ID X-RAY-EMISSION; SIRIUS-B; DA; ATMOSPHERES; STARS; DB AB Observational evidence for the existence of a chromosphere on the cool magnetic white dwarf GD 356 has been reported. In addition, there have been theoretical speculations that cool magnetic white dwarfs may be sources of coronal X-ray emission. This emission, if it exists, would be distinct from the two types of X-ray emission (deep photospheric and shocked wind) that have already been observed from hot white dwarfs. We have used the PSPC instrument on ROSAT to observe three of the most prominent DA white dwarf candidates for coronal X-ray emission: GD 356, KUV 2316+123, and GD 90. The data show no significant emission for these stars. The derived upper limits for the X-ray luminosities provide constraints for a revision of current theories of the generation of nonradiative energy in white dwarfs. C1 UNIV ALABAMA,DEPT MECH & AEROSP ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP MUSIELAK, ZE (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 29 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 NOV 1 PY 1995 VL 453 IS 1 BP L33 EP & PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TB043 UT WOS:A1995TB04300009 ER PT J AU LAUREIJS, RJ FUKUI, Y HELOU, G MIZUNO, A IMAOKA, K CLARK, FO AF LAUREIJS, RJ FUKUI, Y HELOU, G MIZUNO, A IMAOKA, K CLARK, FO TI MODERATE-DENSITY REGIONS IN THE LYNDS-134 CLOUD COMPLEX SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE INFRARED, ISM, CONTINUUM; ISM, CLOUDS; ISM, INDIVIDUAL (LYNDS 134); ISM, MOLECULES ID L134N MOLECULAR CORE; STELLAR DARK CLOUDS; INTERSTELLAR GRAINS; OPTICAL EXTINCTION; CARBON-MONOXIDE; DUST; OPHIUCHUS; EMISSION; (CO)-C-13; LUMINOSITY AB IRAS images, carbon monoxide observations at 2.7 mm (CO, (CO)-C-13, and (CO)-O-18), and blue extinction from star counts have been used for a large-scale study of the L134 complex of high-latitude clouds. We have correlated the different tracers in order to investigate the range of physical conditions for which these tracers apply. We find tight linear correlations between (CO)-C-13 and A(B) and between (CO)-C-13 and Delta I-100. The quantity Delta I-100 is the infrared emission of inner cloud regions obtained from the relationship Delta I-100 = I-60/Theta, where Theta is the value for I-60/I-100 in the outer regions of the clouds. We find that Delta I-100 probes the same regions as (CO)-C-13 and can therefore be used to predict the (CO)-C-13 emission. From the correlation between (CO)-C-13 and A(B) and the CO measurements we determine an average (CO)-C-13 abundance in the complex which does not differ significantly from other studies. However, the abundance in the translucent cloud L1780 is about a factor of 4 lower than in the opaque clouds L134, L183, and L169. Using the (CO)-C-13 observations we have compiled the properties of 18 clumps in the complex. The clumps follow clear luminosity-size and size-line width relationships. The size-line width relationship is consistent with a power law with exponent 0.5. The derived ambient pressure acting on the clumps is of order p/k = 2 x 10(4) K cm(-3). Both molecular and infrared data show that the UV radiation held in the complex is anisotropic. This is consistent with the presence of the nearby UV sources zeta Oph and the Upper Scorpius OB association. The densest regions in the complex as delineated by the ammonia cores can be found close to the few-illumination edges of the clouds. In addition, a higher density contrast on the shadow side can be observed. These observations support the view that the anisotropic UV field affects the density distribution in the clouds and that the increased strength of the UV field causes a bigger halo on the illuminated side. The influence of the UV field on the appearance of clouds is most evident in the outer layers of a cloud. The inner, denser, and well-shielded parts seem much more similar, judging by the uniform behavior of most tracers. However, the displacement of the ammonia cores with respect to the cloud centers suggests the effects of the anisotropy extend down to the densest layers of the clouds. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NAGOYA UNIV,DEPT ASTROPHYS,RADIOASTRON LAB,CHIKUSA KU,NAGOYA,AICHI 46401,JAPAN. PHILLIPS LAB,GEOPHYS DIRECTORATE,BEDFORD,MA 01731. RP LAUREIJS, RJ (reprint author), EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,POB 299,2200 AG NOORDWIJK,NETHERLANDS. NR 57 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 1995 VL 101 IS 1 BP 87 EP 115 DI 10.1086/192234 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RZ600 UT WOS:A1995RZ60000004 ER PT J AU NoriegaCrespo, A Garnavich, PM AF NoriegaCrespo, A Garnavich, PM TI Nir spectroscopy and molecular shocks in Herbig-Haro 1 SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Shocks in Astrophysics CY JAN 09-12, 1995 CL UMIST, MANCHESTER, ENGLAND HO UMIST ID EXTINCTION AB Near Infrared spectroscopic observations (1.2 - 2.4 mu m) of two condensations (HH 1A & HH 1G) of Herbig-Haro object 1 are used to explore the nature of its molecular shocks and extinction. The H-2 emission lines display a more complex behaviour than that accounted for C or J type shock models. The extinction, determined from the ratio of [Fe II] 1.257 & 1.644 mu m, is higher than what is expected from optical [S II] measurements, and it may indicate real discrepancies between the optical and IR regions of the ISM extinction curve. C1 CALTECH,CTR ASTROPHYS,PASADENA,CA 91125. RP NoriegaCrespo, A (reprint author), CALTECH,JET PROP LAB,IPAC,4800 OAK GROVE DR,PASADENA,CA 91125, USA. NR 14 TC 1 Z9 1 U1 1 U2 1 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 NOV PY 1995 VL 233 IS 1-2 BP 63 EP 66 DI 10.1007/BF00627333 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TQ921 UT WOS:A1995TQ92100010 ER PT J AU Schultz, ASB Rank, D Temi, P Harker, D AF Schultz, ASB Rank, D Temi, P Harker, D TI Shocked molecular hydrogen in the LKH alpha 234 region SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Shocks in Astrophysics CY JAN 09-12, 1995 CL UMIST, MANCHESTER, ENGLAND HO UMIST ID HERBIG-HARO OBJECTS; STARS AB We present near-IR images of the shocked gas in in HH 167 (the LkH alpha 234 jet) and HH 103. The H-2 1-0 S(1) (2.122 mu m) and the 1.644 mu m [FeII] lines were observed. The relative spatial distribution of these two Lines provides some insight into the nature of the shocks producing the objects. C1 UNIV CALIF SANTA CRUZ,SANTA CRUZ,CA 95064. RP Schultz, ASB (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. OI Harker, David/0000-0001-6397-9082 NR 3 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 NOV PY 1995 VL 233 IS 1-2 BP 71 EP 74 DI 10.1007/BF00627335 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TQ921 UT WOS:A1995TQ92100012 ER PT J AU Dominik, C Jones, AP Tielens, AGGM AF Dominik, C Jones, AP Tielens, AGGM TI Disintegration of dust aggregates in interstellar shocks and the lifetime of dust grains in the ISM SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Shocks in Astrophysics CY JAN 09-12, 1995 CL UMIST, MANCHESTER, ENGLAND HO UMIST DE dust aggregates; dust destruction; porons grains AB We have studied to influence of grain porosity on the dust destruction mechanism in interstellar shocks. Our results show, that fluffy aggregates of dust grains can be broken up easily in shocks. C1 UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA USA. RP Dominik, C (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD NOV PY 1995 VL 233 IS 1-2 BP 155 EP 159 DI 10.1007/BF00627343 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TQ921 UT WOS:A1995TQ92100020 ER PT J AU MONSON, RK LERDAU, MT SHARKEY, TD SCHIMEL, DS FALL, R AF MONSON, RK LERDAU, MT SHARKEY, TD SCHIMEL, DS FALL, R TI BIOLOGICAL ASPECTS OF CONSTRUCTING VOLATILE ORGANIC-COMPOUND EMISSION INVENTORIES SO ATMOSPHERIC ENVIRONMENT LA English DT Article; Proceedings Paper CT International Specialty Conference on Regional Photochemical Measurement and Modeling Studies CY NOV 08-12, 1993 CL SAN DIEGO, CA SP Air & Waste Management Assoc, Amer Meteorol Soc, Amer Geophys Union, Amer Chem Soc, Div Environm Chem, Amer Assoc Aerosol Res DE MONOTERPENES; ISOPRENE; ECOSYSTEM MODELS; NMHC; VEGETATION; HYDROCARBON EMISSION; PLANT CARBON BALANCE; BIOCHEMISTRY; PHYSIOLOGY; ECOLOGY ID BIOGENIC HYDROCARBON EMISSIONS; ISOPRENE EMISSION; MONOTERPENE VOLATILIZATION; TERRESTRIAL ECOSYSTEMS; CARBON ALLOCATION; RATE VARIABILITY; WATER-STRESS; ATMOSPHERE; LEAVES; PHOTOSYNTHESIS AB The emission of volatile organic compounds (VOCs) from vegetation is subject to numerous biological controls. Past inventories have relied heavily on empirical models which are limited in their ability to simulate the response of organisms to short- and long-term changes in their growth environment. In this review we consider the principal biochemical, physiological and ecological controls over VOC emission with specific reference to how such controls can be included in ecosystem-level inventories. A distinction is made between longer-term biological controls over basal VOC emission rates (rates determined under a standard set of environmental conditions) and instantaneous biological and environmental controls over instantaneous VOC emission rates (rates determined at the prevailing, instantaneous set of environmental conditions). Emphasis is placed on the emission of isoprene and monoterpenes. Isoprene emission occurs essentially without a leaf reservoir and is tightly linked to instantaneous photosynthetic metabolism and the activity of isoprene synthase, the enzyme that underlies isoprene production. At present, there are still large uncertainties about which of these controls dominates isoprene emission rate. Ecosystem-level inventories of isoprene emission would be best handled through consideration of (1) the early season induction of isoprene emission, (2) seasonal and spatial variability in light, nitrogen and water availability and their influences on the basal emission rate, and (3) the influence of instantaneous changes in light and temperature on the basal emission rate. Monoterpene emission occurs from a large leaf reservoir, is uncoupled from instantaneous controls over biosynthesis, and is likely linked to whole-plant carbon allocation patterns. Because of the well-defined role of monoterpenes as herbivore deterrents and their linkage to plant carbon balance, there is promise for ecosystem-level inventories based on biological resource allocation models and evolutionary cost-benefit models. Biological sources for several other VOCs have been identified, including methanol, methylbutenol, hexenol, acetone, and formic and acetic acids. However, the controls over these emissions have yet to be determined, and there is no current basis for mechanistic inventory development. From the studies reviewed here we conclude that the incorporation of mechanistic biological controls in future VOC inventories will improve their capacity to predict emissions across complex ecological gradients. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94301. UNIV WISCONSIN,DEPT BOT,MADISON,WI 53706. UNIV CORP ATMOSPHER RES,CLIMATE SYST MODELING PROGRAM,BOULDER,CO 80307. UNIV COLORADO,DEPT CHEM & BIOCHEM,BOULDER,CO 80309. UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. RP MONSON, RK (reprint author), UNIV COLORADO,DEPT ENVIRONM POPULAT & ORGANISM BIOL,BOULDER,CO 80309, USA. RI Lerdau, Manuel/E-7320-2011; Sharkey, Thomas/B-4032-2009 OI Lerdau, Manuel/0000-0003-1864-0834; Sharkey, Thomas/0000-0002-4423-3223 NR 85 TC 90 Z9 94 U1 1 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD NOV PY 1995 VL 29 IS 21 BP 2989 EP 3002 DI 10.1016/1352-2310(94)00360-W PG 14 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA TE894 UT WOS:A1995TE89400009 ER PT J AU PEDERSON, JR MASSMAN, WJ MAHRT, L DELANY, A ONCLEY, S DENHARTOG, G NEUMANN, HH MICKLE, RE SHAW, RH PAW, KT GRANTZ, DA MACPHERSON, JI DESJARDINS, R SCHUEPP, PH PEARSON, R ARCADO, TE AF PEDERSON, JR MASSMAN, WJ MAHRT, L DELANY, A ONCLEY, S DENHARTOG, G NEUMANN, HH MICKLE, RE SHAW, RH PAW, KT GRANTZ, DA MACPHERSON, JI DESJARDINS, R SCHUEPP, PH PEARSON, R ARCADO, TE TI CALIFORNIA OZONE DEPOSITION EXPERIMENT - METHODS, RESULTS, AND OPPORTUNITIES SO ATMOSPHERIC ENVIRONMENT LA English DT Article; Proceedings Paper CT International Specialty Conference on Regional Photochemical Measurement and Modeling Studies CY NOV 08-12, 1993 CL SAN DIEGO, CA SP Air & Waste Management Assoc, Amer Meteorol Soc, Amer Geophys Union, Amer Chem Soc, Div Environm Chem, Amer Assoc Aerosol Res DE OZONE DEPOSITION; AIRCRAFT REMOTE SENSING; EDDY COVARIANCE ID FLUX; FLUCTUATIONS; FIFE AB The California Ozone Deposition Experiment (CODE) is a program of observations and modeling to improve estimates of the rate of removal of tropospheric ozone at the earth's surface used in grid-based photochemical models of ozone production, transport, and removal. The purpose of CODE is to test, diagnose and improve treatment of dry deposition of ozone and other gaseous species. CODE supports a larger air quality measurement and modeling effort comprised of the San Joaquin Valley Air Quality Study (SJVAQS) and Atmospheric-Utilities Signatures: Predictions and Experiments (AUSPEX) joined as SJVAQS/AUSPEX Regional Model Adaptation Project (SARMAP). However, the CODE data are also applicable to a variety of boundary layer and turbulence problems. This paper describes the field methods and data collected during summer (10 July through 6 August) of 1991 in the San Joaquin Valley (SJV) of California and introduces several related papers. General comparisons and conclusions from all the participants are summarized. The core elements of the CODE field effort consisted of a research aircraft for spatial coverage and three ground sites located in a cotton field, grape vineyard, and very dry (senescent) annual grassland. A major portion of the SJV is represented by these three vegetation types. The eddy covariance method is used to compute the vertical fluxes of ozone, carbon dioxide, water vapor, sensible heat and momentum. For the first half of the study period, flights were made mainly for comparison with tower-based fluxes. Subsequent flights were over other vegetation types and to conduct special studies. In addition to the vertical fluxes, the ground-site data include individual leaf measurements of stomatal conductance, radiative leaf temperature, wetness of surrogate leaves, soil temperature profiles and heat flux, soil composition and water content, mean nitrogen oxide and ozone concentrations, solar and net radiation, photosynthetically active radiation, and vertical profiles of wind, temperature, ozone and water vapor. Aircraft data also include reflected short-wave radiation, surface greenness index and radiative surface temperature. Several factors simplify analyses: a nearly constant synoptic situation, lack of cloud cover, low-level (30 m) flights and land use characterized by extensive homogeneous areas with well defined interfaces. Repeated five-km aircraft runs, necessary for a representative flux calculation, were commonly made over a single crop type. In addition, a partial (60%) solar eclipse on 11 July provides an opportunity to examine the influence of light intensity upon the plant-atmosphere exchange of carbon dioxide and ozone via stomatal activity. C1 US FOREST SERV,FT COLLINS,CO 80526. OREGON STATE UNIV,DEPT ATMOSPHER SCI,CORVALLIS,OR 97331. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. ATMOSPHER ENVIRONM SERV,DOWNSVIEW,ON M3H 5T4,CANADA. UNIV CALIF DAVIS,DEPT LAND AIR & WATER RESOURCES,DAVIS,CA 95616. UNIV CALIF RIVERSIDE,KEARNEY AGR CTR,PARLIER,CA 93648. NATL RES COUNCIL CANADA,FLIGHT RES LAB,OTTAWA,ON K1A 0R6,CANADA. AGR CANADA,LAND RESOURCE RES CTR,OTTAWA,ON K1A 0C6,CANADA. MCGILL UNIV,DEPT RENEWABLE RESOURCES,ST ANNE BELLEVUE,PQ H9X 3V9,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. PACIFIC GAS & ELECT CO,TECH SERV,SAN RAMON,CA 94583. PACIFIC GAS & ELECT CO,ECOL SERV,SAN RAMON,CA 94583. RP PEDERSON, JR (reprint author), CALIF AIR RESOURCES BOARD,DIV TECH SUPPORT,MODELING SUPPORT SECT,POB 2815,SACRAMENTO,CA 95812, USA. NR 55 TC 32 Z9 35 U1 0 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD NOV PY 1995 VL 29 IS 21 BP 3115 EP 3132 DI 10.1016/1352-2310(95)00136-M PG 18 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA TE894 UT WOS:A1995TE89400018 ER PT J AU MACPHERSON, JI DESJARDINS, RL SCHUEPP, PH PEARSON, R AF MACPHERSON, JI DESJARDINS, RL SCHUEPP, PH PEARSON, R TI AIRCRAFT-MEASURED OZONE DEPOSITION IN THE SAN-JOAQUIN VALLEY OF CALIFORNIA SO ATMOSPHERIC ENVIRONMENT LA English DT Article; Proceedings Paper CT International Specialty Conference on Regional Photochemical Measurement and Modeling Studies CY NOV 08-12, 1993 CL SAN DIEGO, CA SP Air & Waste Management Assoc, Amer Meteorol Soc, Amer Geophys Union, Amer Chem Soc, Div Environm Chem, Amer Assoc Aerosol Res DE OZONE; CALIFORNIA; AIRCRAFT ID FLUX AB In the summer of 1991 the San Joaquin Valley Air Pollution Study Agency organized a four-week international field experiment to measure ozone concentrations and fluxes in the San Joaquin Valley of California. The field data are being used to improve the understanding of the exchange processes occurring between the atmosphere and various types of vegetation, and to develop a comprehensive computer model for ozone transport and deposition in the valley. The National Research Council of Canada (NRC) Twin Otter atmospheric research aircraft flew 24 flights in this program, measuring fluxes and deposition velocities adjacent to three highly instrumented tower facilities, each situated over a vegetation type significant to the area, i.e. cotton, grapes, and natural grassland. Having established a correlation between aircraft- and tower-measured fluxes at these reference locations, the aircraft was then used to measure fluxes at regional scales over several additional types of vegetation throughout the San Joaquin Valley. The paper will describe the instrumentation and flight procedures used to make these airborne flux measurements, with emphasis on ozone. Summary data will be presented on the correlation between ozone deposition velocity and the greenness index, the ratio of reflected infrared to red radiation which is an indication of the density of green vegetation beneath the aircraft. Sample results from several special studies will also be presented; these include repeated runs on a regional scale, a grid study, an overflight of the City of Fresno, runs made adjacent to Interstate-5, and repeated passes over the cotton site during the solar eclipse on 11 July 1991. More detailed results from the Twin Otter operations in this experiment are presented in a series of companion papers. C1 NATL RES COUNCIL CANADA,INST AEROSP RES,FLIGHT RES LAB,OTTAWA,ON K1A 0R6,CANADA. AGR CANADA,CTR LAND & BIOL RESORUCES RES,OTTAWA,ON K1A 0C6,CANADA. MCGILL UNIV,DEPT NAT RESOURCES SCI,ST ANNE BELLEVUE,PQ H9X 3V9,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 21 TC 9 Z9 9 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD NOV PY 1995 VL 29 IS 21 BP 3133 EP 3145 PG 13 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA TE894 UT WOS:A1995TE89400019 ER PT J AU MASSMAN, WJ MACPHERSON, JI DELANY, A DENHARTOG, G NEUMANN, HH ONCLEY, SP PEARSON, R PEDERSON, J SHAW, RH AF MASSMAN, WJ MACPHERSON, JI DELANY, A DENHARTOG, G NEUMANN, HH ONCLEY, SP PEARSON, R PEDERSON, J SHAW, RH TI SURFACE CONDUCTANCES FOR OZONE UPTAKE DERIVED FROM AIRCRAFT EDDY-CORRELATION DATA SO ATMOSPHERIC ENVIRONMENT LA English DT Article; Proceedings Paper CT International Specialty Conference on Regional Photochemical Measurement and Modeling Studies CY NOV 08-12, 1993 CL SAN DIEGO, CA SP Air & Waste Management Assoc, Amer Meteorol Soc, Amer Geophys Union, Amer Chem Soc, Div Environm Chem, Amer Assoc Aerosol Res DE OZONE DRY DEPOSITION; SAN JOAQUIN VALLEY; AIRCRAFT AND TOWER EDDY COVARIANCE FLUXES; OZONE SURFACE CONDUCTANCES ID FLUX MEASUREMENTS; BOUNDARY-LAYER; VERTICAL FLUX; CHEMISTRY; NO2; DEPOSITION; DYNAMICS; FOREST; BUDGET; HEAT AB Plants and soils act as major sinks for tropospheric ozone, especially during daylight hours when plant stomata are thought to provide the dominant pathway for ozone uptake. The present study, as part of the larger California Ozone Deposition Experiment, uses aircraft eddy covariance measurements taken during the summer of 1991 in the San Joaquin Valley of California to estimate the surface conductance for ozone uptake. To explore for possible sources of discrepancies between the aircraft-derived and tower-based surface conductances a comparison is first made between tower-based fluxes and aircraft fluxes at three tower-based sites. On the average the momentum and surface energy fluxes (sensible and latent heat) observed between 30 and 33 m altitude with an aircraft agreed to within +/- 10% with simultaneously measured tower-based fluxes (observed between 4 and 10 m at a vineyard, a cotton and a grassland site). However, comparisons of the aircraft- and tower-based ozone fluxes indicate that between about 4 and 33 m there is an average loss of ozone flux with height of about 18%. It is suggested that either (or both) soil NO emissions or entrainment of ozone free air at the top of the mixed layer may be responsible for this relatively larger discrepancy in the ozone fluxes. Nevertheless, in spite of any relatively larger uncertainties associated with the ozone flux, the tower-based and aircraft-based conductances are in good agreement. The aircraft-derived conductances display a similar magnitude and range of variation as the tower-based conductances and the regression coefficient between the two sets of conductances is 0.9 +/- 0.08. Therefore, results from this study suggest that the aircraft can be used to estimate surface conductances of ozone deposition; however, these conductances are subject to large uncertainties. C1 NATL RES COUNCIL CANADA,INST AEROSP RES,OTTAWA,ON K1A 0R6,CANADA. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. ATMOSPHER ENVIRONM SERV,DOWNSVIEW,ON M3H 5T4,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CALIFORNIA AIR RESOURCES BOARD,SACRAMENTO,CA 95812. UNIV CALIF DAVIS,DEPT LAND AIR & WATER RESOURCES,DAVIS,CA 95616. RP MASSMAN, WJ (reprint author), US FOREST SERV,240 W PROSPECT,FT COLLINS,CO 80526, USA. NR 35 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1352-2310 J9 ATMOS ENVIRON JI Atmos. Environ. PD NOV PY 1995 VL 29 IS 21 BP 3181 EP 3188 DI 10.1016/1352-2310(94)00330-N PG 8 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA TE894 UT WOS:A1995TE89400023 ER PT J AU FERRARO, JS SULZMAN, FM DORSETT, JA AF FERRARO, JS SULZMAN, FM DORSETT, JA TI ALTERATIONS IN GROWTH-RATE ASSOCIATED WITH A NORMALLY PERSISTING CIRCADIAN-RHYTHM DURING SPACEFLIGHT SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID NEUROSPORA-CRASSA; CLOCK; LIGHT AB Background: Biological clocks time many physiological parameters with periodicities close to 24 h; those which persist in the absence of environmental cues are circadian. An earlier shuttle experiment (STS-9) examined circadian pacemaker function and growth rate of Neurospora crassa and demonstrated damped rhythm amplitudes, increased variability in period lengths and altered growth rates. Hypothesis: Postflight studies suggested that accelerative forces of launch could have induced rhythm alterations. Differences in growth rate may have been due to an alteration of metabolic rate. Methods: Race tubes inoculated with bd or csp strains were flown aboard STS-32, exposed to ambient mid-deck temperatures throughout flight, and exposed to light only during marking procedures. Period, rhythm amplitude, and growth rate were determined and compared to orbital environmental controls (OES) and 25 degrees C ground controls (GC). Results: Unlike the previous flight experiment, the rhythm persisted quite normally. bd flight and OES cultures each displayed lengthened periods of a similar magnitude when compared to GC. The lengthened periods of csp flight cultures while longer than GC, were shorter than OES. Shuttle temperatures were relatively warm, however the increased period length in space was greater than predicted by the known Q(10). Growth rates also increased substantially during flight, which could not be accounted for by thermal mechanisms alone. Conclusion: It is likely that some of the cultures may have entrained to the unexpected diurnal temperature variations; however, other cultures did not entrain, yet retained rhythmicity with increased periods. The results also suggest an increased metabolic rate during spaceflight. C1 NASA,DIV LIFE SCI,WASHINGTON,DC 20546. RP FERRARO, JS (reprint author), SO ILLINOIS UNIV,SCH MED,DEPT PHYSIOL,CARBONDALE,IL 62901, USA. NR 21 TC 4 Z9 4 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 1995 VL 66 IS 11 BP 1079 EP 1085 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA TB335 UT WOS:A1995TB33500009 PM 8588798 ER PT J AU Banerjee, RK Back, LH Cho, YI AF Banerjee, RK Back, LH Cho, YI TI Flow-pressure drop measurement and calculation in a tapered femoral artery of a dog SO BIORHEOLOGY LA English DT Article DE in vivo; non-Newtonian viscosity; velocity profile; shear rate; shear stress; pressure drop ID MODELS; BLOOD; CURVATURE; FLUIDS AB This study describes the in vivo measurement of pressure drop and flow during the cardiac cycle in the femoral artery of a dog, and the computer simulation of the experiment based on the use of the measured flow, vessel dimensions and blood viscosity. In view of the experimental uncertainty in obtaining the accurate velocity profile at the wall region, the velocity pulse at the center was measured and numerical calculations were performed for the center line instantaneous velocity and within the two Limits of spatial distribution of inlet flow conditions: uniform and parabolic. Temporal and spatial variations of flow parameters, i.e., velocity profile, shear rate, non-Newtonian viscosity, wall shear stress, and pressure drop were calculated, There existed both positive and negative shear rates during a pulse cycle, i.e., the arterial wall experiences zero shear three times during a cardiac cycle. For the parabolic inlet condition, the taper of the artery not only increased the magnitude of the positive and negative shear rates, but caused a steep gradient in shear rate, a phenomenon which in turn affects wall shear stress and pressure. In contrast, for the uniform inlet condition, the flow through the tapered artery was predominantly the developing type, which resulted in reduction in magnitude of wall shear rate along the axial direction. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Banerjee, RK (reprint author), DREXEL UNIV,DEPT MECH ENGN & MECH,PHILADELPHIA,PA 19104, USA. NR 18 TC 4 Z9 4 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0006-355X J9 BIORHEOLOGY JI Biorheology PD NOV-DEC PY 1995 VL 32 IS 6 BP 655 EP 684 DI 10.1016/0006-355X(95)00044-A PG 30 WC Biophysics; Engineering, Biomedical; Hematology SC Biophysics; Engineering; Hematology GA TM875 UT WOS:A1995TM87500007 PM 8857355 ER PT J AU WARING, RH WAY, JB HUNT, ER MORRISSEY, L RANSON, KJ WEISHAMPEL, JF OREN, R FRANKLIN, SE AF WARING, RH WAY, JB HUNT, ER MORRISSEY, L RANSON, KJ WEISHAMPEL, JF OREN, R FRANKLIN, SE TI BIOLOGISTS TOOLBOX - IMAGING RADAR FOR ECOSYSTEM STUDIES SO BIOSCIENCE LA English DT Article ID SYNTHETIC APERTURE RADAR; FOREST BIOMASS; BACKSCATTER; VEGETATION; MODEL; SAR; SATELLITE; RESOURCES; MOISTURE; IMAGERY C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV MONTANA,SCH FORESTRY,MISSOULA,MT 59812. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CENT FLORIDA,DEPT BIOL,ORLANDO,FL 32816. DUKE UNIV,SCH ENVIRONM,DURHAM,NC 27706. UNIV CALGARY,DEPT GEOG,CALGARY,AB T2N 1N4,CANADA. RP WARING, RH (reprint author), OREGON STATE UNIV,COLL FORESTRY,CORVALLIS,OR 97331, USA. RI Ranson, Kenneth/G-2446-2012; Waring, Richared/C-4796-2014 OI Ranson, Kenneth/0000-0003-3806-7270; Waring, Richared/0000-0003-2533-3664 NR 66 TC 76 Z9 79 U1 0 U2 4 PU AMER INST BIOL SCI PI WASHINGTON PA 730 11TH STREET, NW, WASHINGTON, DC 20001-4521 SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD NOV PY 1995 VL 45 IS 10 BP 715 EP 723 DI 10.2307/1312677 PG 9 WC Biology SC Life Sciences & Biomedicine - Other Topics GA TB495 UT WOS:A1995TB49500011 ER PT J AU Rabalais, NN Burditt, FR Coen, LD Cole, BE Eleuterius, C Heck, KL McTigue, TA Morgan, SG Perry, HM Truesdale, FM ZimmerFaust, RK Zimmerman, RJ AF Rabalais, NN Burditt, FR Coen, LD Cole, BE Eleuterius, C Heck, KL McTigue, TA Morgan, SG Perry, HM Truesdale, FM ZimmerFaust, RK Zimmerman, RJ TI Settlement of Callinectes sapidus megalopae on artificial collectors in four Gulf of Mexico estuaries SO BULLETIN OF MARINE SCIENCE LA English DT Article; Proceedings Paper CT Symposium on Blue Crab Recruitment - Environmental Control and Population Regulation, at the Estuarine-Research-Federation Conference CY NOV 16, 1993 CL HILTON HEAD ISL, SC SP Estuarine Res Federat ID PLANKTONIC AVAILABILITY; CONTINENTAL-SHELF; DELAWARE BAY; LOOP CURRENT; YORK RIVER; CRAB; RECRUITMENT; DISPERSAL; MECHANISM; VIRGINIA AB Standardized artificial collectors were used to document trends in settlement of blue crab (Callinectes sapidus) megalopae in four Gulf of Mexico estuaries. Blue crab megalopal settlement was generally episodic within an estuary and asynchronous among coastwide sites. Daily settlement of megalopae at a given site and rankings of total numbers among sites varied greatly from year-to-year. Although spawning is protracted and megalopae are available in offshore waters throughout most of the year, most megalopae were collected during August-October. Limited settlement of megalopae in late spring and early summer occurred in the two estuaries (Galveston Bay in 1992 and Terrebonne Bay in 1991) for which sampling was conducted during this period Within several estuaries, there were no clear environmental variables that corresponded most closely to peak events of megalopal settlement. Combinations of equatorial tides and onshore winds (when present) were the most apparent environmental variables correlated with high daily settlement at Mobile Bay mouth. The majority of high settlement events for Mississippi Sound were associated with tropic tides coupled with onshore winds. The relative importance of environmental variables affecting settlement varied from year-to-year in several of the estuaries. Limited coherence between gulf sites was not supported by plausible mechanisms for transport, with the exception of a 2- to 3-d lag from the mouth of Mobile Bay to a mid-estuary site. Inter-regional comparisons of monthly settlement means during peak settlement months were robust and consistent with regional climatic controls (temperature and salinity) and long-term water level patterns (lunar periodicity and meteorology). Large numbers of blue crab megalopae recruited to gulf estuaries. Numbers of settling blue crab megalopae declined with distance from the Gulf of Mexico, but still recruited in fairly large numbers well into the two estuaries where such data were available. C1 NATL MARINE FISHERIES SERV,GALVESTON,TX 77551. MRRI,CHARLESTON,SC 29422. MARINE ENVIRONM SCI CONSORTIUM,DAUPHIN ISL,AL 36528. UNIV SW LOUISIANA,NMFS,LAFAYETTE,LA 70504. SUNY STONY BROOK,MARINE SCI RES CTR,STONY BROOK,NY 11794. GULF COAST RES LAB,OCEAN SPRINGS,MS 39564. LOUISIANA STATE UNIV,BATON ROUGE,LA 70803. UNIV S CAROLINA,DEPT BIOL SCI,COLUMBIA,SC 29208. UNIV S CAROLINA,MARINE SCI PROGRAM,COLUMBIA,SC 29208. RP Rabalais, NN (reprint author), LOUISIANA UNIV MARINE CONSORTIUM,8124 HWY 56,CHAUVIN,LA 70344, USA. NR 41 TC 68 Z9 68 U1 0 U2 7 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD NOV PY 1995 VL 57 IS 3 BP 855 EP 876 PG 22 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA TN246 UT WOS:A1995TN24600024 ER PT J AU WIELICKI, BA CESS, RD KING, MD RANDALL, DA HARRISON, EF AF WIELICKI, BA CESS, RD KING, MD RANDALL, DA HARRISON, EF TI MISSION TO PLANET EARTH - ROLE OF CLOUDS AND RADIATION IN CLIMATE SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Review ID REFLECTED SOLAR-RADIATION; GENERAL-CIRCULATION MODELS; EFFECTIVE PARTICLE RADIUS; MARINE STRATIFORM CLOUDS; BUDGET EXPERIMENT; AVHRR DATA; LIGHT-SCATTERING; SATELLITE DATA; CIRRUS CLOUDS; CLEAR-SKY AB The role of clouds in modifying the earth's radiation balance is well recognized as a key uncertainty in predicting any potential future climate change. This statement is true whether the climate change of interest is caused by changing emissions of greenhouse gases and sulfates, deforestation, ozone depletion, volcanic eruptions, or changes in the solar constant. This paper presents an overview of the role of the National Aeronautics and Space Administration's Earth Observing System (EOS) satellite data in understanding the role of clouds in the global climate system. The paper gives a brief summary of the cloud/radiation problem, and discusses the critical observations needed to support further investigations. The planned EOS data products are summarized, including the critical advances over current satellite cloud and radiation budget data. Key advances include simultaneous observation of radiation budget and cloud properties, additional information on cloud particle size and phase, improved detection of thin clouds and multilayer cloud systems, greatly reduced ambiguity in partially cloud-filled satellite fields of view, improved calibration and stability of satellite-observed radiances, and improved estimates of radiative fluxes at the top of the atmosphere, at the surface, and at levels within the atmosphere. Outstanding sampling and remote sensing issues that affect data quality are also discussed. Finally, the EOS data are placed in the context of other satellite observations as well as the critical surface, field experiment, and laboratory data needed to address the role of clouds in the climate system. It is concluded that the EOS data are a necessary but insufficient condition for solution of the scientific cloud/radiation issues. A balanced approach of satellite, field, and laboratory data will be required. These combined data can span the necessary spatial scales of global, regional, cloud cell, and cloud particle physics (i.e., from 10(8) to 10(-7) m). C1 SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. NASA, GODDARD SPACE FLIGHT CTR, EARTH SCI DIRECTORATE, GREENBELT, MD 20771 USA. COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80523 USA. RP WIELICKI, BA (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, RADIAT SCI BRANCH, MAIL STOP 420, HAMPTON, VA 23681 USA. RI King, Michael/C-7153-2011; Randall, David/E-6113-2011 OI King, Michael/0000-0003-2645-7298; Randall, David/0000-0001-6935-4112 NR 137 TC 246 Z9 252 U1 5 U2 32 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD NOV PY 1995 VL 76 IS 11 BP 2125 EP 2153 DI 10.1175/1520-0477(1995)076<2125:MTPERO>2.0.CO;2 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TH343 UT WOS:A1995TH34300001 ER PT J AU SOUTHWARD, RE THOMPSON, DS THOMPSON, DW CAPLAN, ML STCLAIR, AK AF SOUTHWARD, RE THOMPSON, DS THOMPSON, DW CAPLAN, ML STCLAIR, AK TI SYNTHESIS OF REFLECTIVE POLYIMIDE FILMS VIA IN-SITU SILVER(I) REDUCTION SO CHEMISTRY OF MATERIALS LA English DT Article ID COMPLEXES; PHOTOEMISSION; SURFACES; AG(110); OXYGEN; SPECTROSCOPY; INTERFACES; CHEMISTRY; ADHESION AB Optically reflective polyimide films have been prepared by the incorporation of silver(I) acetate and hexafluoroacetylacetone into a dimethylacetamide solution of the poly(amic acid) formed from 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4'-oxydianiline (4,4'-ODA). Thermal curing of the silver(I)-containing poly(amic acid) leads to imidization with concomitant silver(I) reduction, yielding a reflective silver surface. The metallized BTDA/4,4'-ODA films retain the essential mechanical properties of undoped films and have good thermal stability particularly in nitrogen atmospheres. The surface and bulk are not electrically conducting. Several additional soluble silver(I) additive systems were examined, all of which underwent thermal reduction to metallic silver but gave widely varying degrees of reflectivity. C1 COLL WILLIAM & MARY,DEPT APPL SCI,WILLIAMSBURG,VA 23185. NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23681. RP SOUTHWARD, RE (reprint author), COLL WILLIAM & MARY,DEPT CHEM,WILLIAMSBURG,VA 23185, USA. NR 55 TC 24 Z9 27 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD NOV PY 1995 VL 7 IS 11 BP 2171 EP 2180 DI 10.1021/cm00059a027 PG 10 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA TF115 UT WOS:A1995TF11500027 ER PT J AU SHIRCORE, AM MACK, WJ SELZER, RH LEE, PL AZEN, SP ALAUPOVIC, P HODIS, HN AF SHIRCORE, AM MACK, WJ SELZER, RH LEE, PL AZEN, SP ALAUPOVIC, P HODIS, HN TI COMPENSATORY VASCULAR CHANGES OF REMOTE CORONARY SEGMENTS IN RESPONSE TO LESION PROGRESSION AS OBSERVED BY SEQUENTIAL ANGIOGRAPHY FROM A CONTROLLED CLINICAL-TRIAL SO CIRCULATION LA English DT Article DE CORONARY DISEASE; APOLIPOPROTEINS; ANGIOGRAPHY; CHOLESTEROL; LIPOPROTEINS; REMODELING ID MEDIATED DILATION; CONSCIOUS DOGS; ENDOTHELIUM; FLOW; ARTERIES; ATHEROSCLEROSIS; HUMANS; ACETYLCHOLINE; MECHANISM AB Background Local coronary artery enlargement to compensate for atherosclerotic plaques preserves the vessel lumen. The extent to which coronary segments remote from progressing lesions enlarge is unknown. This is clinically relevant since compensatory enlargement may be important in determining whether clinical complications result from progression of coronary artery disease (CAD). Additionally, compensatory change has implications for quantitative coronary angiographic (QCA) trials, since the effect of progression on diameter means may be mitigated by compensatory changes in remote coronary segments when QCA change is averaged over all lesions. Methods and Results Serial QCA data from 78 subjects in the Monitored Atherosclerosis Regression Study were used to demonstrate compensatory changes in coronary segments remote from progressing or regressing lesions. Coronary segments were first classified as progressing (regressing) if percent diameter stenosis (PS) increased or decreased by >10 with a concurrent decrease or increase in minimum lumen diameter (MLD) of either >0.32 mm or >10% of the normal baseline reference diameter (DNORM). Segments not meeting these criteria were labeled stenosis stable. Stenosis-stable segments opposite progressing lesions showed increases in MLD (P=.0006), DNORM (P=.001), and average diameter (P=.001). On-trial apolipoprotein (ape) B, apo C-III, and blood pressure levels inversely correlated with these compensatory changes. Conclusions Lesion progression in one coronary segment is associated with significant increases in segmental diameter of remote parts of the coronary tree. We hypothesize these increases to be vascular compensatory changes in response to progression of CAD. Vascular compensatory change is enhanced by LDL cholesterol and triglyceride-rich lipoprotein reduction and appears to be part of the treatment effect itself. C1 UNIV SO CALIF, SCH MED, DIV CARDIOL, ATHEROSCLEROSIS RES UNIT, LOS ANGELES, CA 90033 USA. UNIV SO CALIF, SCH MED, DEPT MED, STAT CONSULTAT RES CTR, LOS ANGELES, CA 90033 USA. UNIV SO CALIF, SCH MED, DEPT PREVENT MED, LOS ANGELES, CA 90033 USA. JET PROPULS LAB, PASADENA, CA USA. OKLAHOMA MED RES FDN, OKLAHOMA CITY, OK 73104 USA. FU NHLBI NIH HHS [R01-HL-45005, R03-HL-48399, R01-HL-49885] NR 27 TC 13 Z9 13 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0009-7322 J9 CIRCULATION JI Circulation PD NOV 1 PY 1995 VL 92 IS 9 BP 2411 EP 2418 PG 8 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA TC796 UT WOS:A1995TC79600010 PM 7586339 ER PT J AU PANCAKE, CM SIMMONS, ML YAN, JC AF PANCAKE, CM SIMMONS, ML YAN, JC TI PERFORMANCE EVALUATION TOOLS FOR PARALLEL AND DISTRIBUTED SYSTEMS SO COMPUTER LA English DT Editorial Material C1 LOS ALAMOS NATL LAB,COMP RES & APPLICAT GRP,LOS ALAMOS,NM 87545. NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT SYST,MOFFETT FIELD,CA 94035. RP PANCAKE, CM (reprint author), OREGON STATE UNIV,CORVALLIS,OR 97331, USA. NR 10 TC 22 Z9 22 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9162 J9 COMPUTER JI Computer PD NOV PY 1995 VL 28 IS 11 BP 16 EP 19 PG 4 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA TC583 UT WOS:A1995TC58300012 ER PT J AU JOHNSON, AR QUIGLEY, CJ FREESE, CE AF JOHNSON, AR QUIGLEY, CJ FREESE, CE TI A VISCOHYPERELASTIC FINITE-ELEMENT MODEL FOR RUBBER SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID VISCOELASTICITY; COMPUTATION; FORMULATION AB A recently developed finite deformation internal solid theory for viscoelastic deformations of rubber is reviewed and an axisymmetric finite element implementation of the theory is presented. The theoretical model is a three-dimensional, total Lagrangian, finite deformation generalization of the Maxwell internal solid theory for viscoelasticity. It utilizes time dependent reference shapes for internal hyperelastic solids to approximate the viscous effects found in rubber and is called a viscohyperelastic model. The material constants for the sum of the internal solids' hyperelastic energy functions can be found by performing the classical tensile, biaxial and shear tests as step-strain tests. A nearly incompressible finite element version of the theory is presented. The viscous equations of motion are solved with a predictor-corrector integration scheme. Time dependent pressure loads are applied to the interior of both a thick walled rubber cylinder and sphere to numerically demonstrate the viscohyperelastic finite element algorithm. C1 AMSRL,MA,PC,MAT DIRECTORATE,DIV POLYMERS & MECH,WATERTOWN,MA 02172. RP JOHNSON, AR (reprint author), NASA,LANGLEY RES CTR,VEHICLE STRUCT DIRECTORATE,COMPUTAT STRUCT BRANCH,MS240,HAMPTON,VA 23681, USA. NR 28 TC 37 Z9 40 U1 2 U2 12 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. Methods Appl. Mech. Eng. PD NOV PY 1995 VL 127 IS 1-4 BP 163 EP 180 DI 10.1016/0045-7825(95)00833-4 PG 18 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA TJ544 UT WOS:A1995TJ54400010 ER PT J AU SMITH, JP AF SMITH, JP TI BUCKLING OF SHEAR-DEFORMABLE PLATES USING THE P-VERSION OF THE FINITE-ELEMENT METHOD SO COMPUTERS & STRUCTURES LA English DT Article AB In this paper, the p-version of the finite element method is introduced for problems of plate buckling with the inclusion of shear deformations. For thick plates, the thickness of the plate comes into consideration as the plate deforms. Classical Kirchoff plate bending formulations neglect the effect of thickness in the deformation. Reissner-Mindlin plate theory is used to develop the appropriate expressions governing shear deformable plates. It will be shown numerically that the p-version finite element method is an effective tool-for this class of problems. Numerical examples will be provided, including square and rectangular plates to provide a means through which validation is satisfied. RP SMITH, JP (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,STRUCT ANAL SECT,HOUSTON,TX 77058, USA. NR 8 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD NOV PY 1995 VL 57 IS 3 BP 527 EP 532 DI 10.1016/0045-7949(94)00627-F PG 6 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA RQ159 UT WOS:A1995RQ15900018 ER PT J AU PERALTA, F FLANAGAN, S AF PERALTA, F FLANAGAN, S TI CASSINI INTERPLANETARY TRAJECTORY DESIGN SO CONTROL ENGINEERING PRACTICE LA English DT Article DE CASSINI; INTERPLANETARY TRAJECTORY AB The Cassini mission to Saturn will start a second phase in the exploration of the Saturnian system, after the historical Voyager flybys of Saturn in 1980 and 1981. The Cassini primary mission is scheduled to be launched in October 1997 by the Titan IV/Centaur. Cassini uses four planetary gravity-assist flybys to gain the energy necessary to reach Saturn in July 2004. This arrival date at Saturn provides a unique opportunity for a flyby of Saturn's outer satellite Phoebe on the final approach. This paper provides an overview of the processes involved in the interplanetary trajectory design and analysis of the Cassini mission to Saturn. RP PERALTA, F (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91125, USA. NR 2 TC 19 Z9 20 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0661 J9 CONTROL ENG PRACT JI Control Eng. Practice PD NOV PY 1995 VL 3 IS 11 BP 1603 EP 1610 DI 10.1016/0967-0661(95)00171-P PG 8 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA TB053 UT WOS:A1995TB05300010 ER PT J AU WOLF, AA SMITH, JC AF WOLF, AA SMITH, JC TI DESIGN OF THE CASSINI TOUR TRAJECTORY IN THE SATURNIAN SYSTEM SO CONTROL ENGINEERING PRACTICE LA English DT Article DE NAVIGATION SYSTEMS; SYSTEMS ENGINEERING; TRAJECTORY; TRAJECTORY PLANNING AB The Cassini mission to Saturn employs a Saturn orbiter and a Titan probe to conduct an intensive investigation of the Saturnian system. The Cassini orbiter flies series of orbits incorporating flybys of the Saturnian satellites called the ''satellite tour''. During the tour, the gravitational fields of the satellites are used to modify and control the orbit, targeting from one satellite flyby to the next. The tour trajectory must also be designed to maximize opportunites for science observations, subject to mission-imposed constraints. Tour design studies have been conducted for Cassini to identify trades and strategies for achieving these sometimes conflicting goals. Concepts, strategies, and techniques previously developed for the Galileo mission to Jupiter have been modified, and new ones have been developed, to meet the requirements of the Cassini mission. RP WOLF, AA (reprint author), CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 5 TC 15 Z9 15 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0661 J9 CONTROL ENG PRACT JI Control Eng. Practice PD NOV PY 1995 VL 3 IS 11 BP 1611 EP 1619 DI 10.1016/0967-0661(95)00172-Q PG 9 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA TB053 UT WOS:A1995TB05300011 ER PT J AU SOLLAZZO, C RAKIEWICZ, J WILLS, RD AF SOLLAZZO, C RAKIEWICZ, J WILLS, RD TI CASSINI-HUYGENS - MISSION OPERATIONS SO CONTROL ENGINEERING PRACTICE LA English DT Article DE INTERPLANETARY SPACECRAFT; SPACECRAFT OPERATIONS; SPACECRAFT AUTONOMY AB Operations of the Cassini-Huygens missions will be carried out from two centres working in close liaison. The NASA Cassini Saturn orbiter will be operated from JPL in Pasadena, USA, while the ESA Huygens Than probe will be operated from ESOC in Darmstadt, Germany, but with uplink and downlink through JPL and the Orbiter. Both spacecraft will be largely operated through pre-programmed time-driven command sequences, either uplinked from the ground or driven by on-board software. The Huygens probe in particular has, after separation from Cassini, no telecommand capability during its mission descent through Titan's atmosphere and the operation of its scientific instruments is then entirely automatic. To ensure the success of the mission all Probe systems are hot redundant and their performances are checked out, up to Probe release, at regular intervals throughout the 7-year cruise to Saturn. The overall Cassini Ground System is designed to meet all the requirements of operating the combined mission with a minimum reaction time of about 160 min (round-trip light-time at Cassini-Probe separation), with high reliability and within critical resource budgets over a period of more than ten years. C1 CALTECH,JET PROP LAB,PASADENA,CA. EUROPEAN SPACE AGCY,EUROPEAN SPACE RES & TECHNOL CTR,2200 AG NOORDWIJK,NETHERLANDS. RP SOLLAZZO, C (reprint author), EUROPEAN SPACE AGCY,EUROPEAN SPACE OPERAT CTR,DARMSTADT,GERMANY. NR 8 TC 0 Z9 0 U1 7 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0661 J9 CONTROL ENG PRACT JI Control Eng. Practice PD NOV PY 1995 VL 3 IS 11 BP 1631 EP 1640 DI 10.1016/0967-0661(95)00174-S PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA TB053 UT WOS:A1995TB05300013 ER PT J AU VOLK, GM MITCHELL, CA AF VOLK, GM MITCHELL, CA TI PHOTOPERIOD SHIFT EFFECTS ON YIELD CHARACTERISTICS OF RICE SO CROP SCIENCE LA English DT Article ID NITROGEN AB Edible yield must be maximized for each crop species selected for inclusion in the Controlled Ecological Life-Support System (CELSS) proposed by NASA to support long-term manned space missions. In a greenhouse study aimed at increasing biomass partitioning to rice (Oryza sativa L.) grain, plants of the high yielding semi-dwarf rice cultivar Ai-Nan-Tsao were started in pots under 8-h photoperiods at a density of 212 plants m(-2). After different periods of time under 8-h photoperiods, pots were switched to continuous Light for the remainder of the cropping cycle. Continuous Light did not delay time to first panicle emergence (60 d) or time to harvest (83 d). There was a positive correlation between the length of continuous Light treatments and nongrain biomass. Grain yield (1.6 +/- 0.2 g plant(-1)) did not increase in continuous light. Yield-efficiency rate (grain weight per length of cropping cycle, canopy volume, and weight of nongrain shoot biomass) was used to compare treatments. Small Ai-Nan-Tsao rice canopies grown under 8-h photoperiods were more efficient producers of grain than canopies grown under continuous light for a portion of the rice cropping cycle. C1 PURDUE UNIV,NASA,SPECIALIZED CTR RES & TRAINING BIOREGENERAT LIFE,W LAFAYETTE,IN 47907. CORNELL UNIV,PLANT BIOL SECT,ITHACA,NY 14853. NR 18 TC 3 Z9 3 U1 0 U2 4 PU CROP SCIENCE SOC AMER PI MADISON PA 677 S SEGOE ROAD, MADISON, WI 53711 SN 0011-183X J9 CROP SCI JI Crop Sci. PD NOV-DEC PY 1995 VL 35 IS 6 BP 1631 EP 1635 PG 5 WC Agronomy SC Agriculture GA TD279 UT WOS:A1995TD27900019 PM 11540306 ER PT J AU Schneider, J Doyle, LR AF Schneider, J Doyle, LR TI Ground-based detection of terrestrial extrasolar planets by photometry: The case for CM Draconis SO EARTH MOON AND PLANETS LA English DT Article ID SYSTEMS; STARS; BINARIES; CRITERIA; SEARCH AB The detection of extrasolar planets by measuring a photometric drop in the stellar brightness due to a planetary transit can be statistically improved by observing eclipsing binary systems and photometrically improved by observing small component systems, In particular the system CM Draconis, with two dM4 components, would allow the detection of extrasolar planets in the size range of Earth-to-Neptune requiring a ground-based photometric precision of about 0.08% to 1.1% (photometric precision of about 0.3% is routinely achievable with 1-meter class telescopes at the magnitude of CM Draconis, 11.07 in R-filter). In addition, the transit of extrasolar planets in a binary star system provides a unique, quasi-periodic signal that can be cross-correlated with the observational data to detect sub-noise signals. We examine the importance of making such observations to an understanding of the formation and evolution of terrestrial-type planets in main-sequence star systems. Terrestrial planets could have formed with substancially shorter periods in this lower luminosity system, for example, and might be expected to have accreted essentially in the binary orbital plane (however, non-coplanar planets may also eventually be detectable due to precession). We also report on a network of medium-sized telescopes at varying longitudes that have been organized to provide such constraints on terrestrial-planet formation processes and discuss the extention of near-term observations to other possible binary systems, as well. Finally, we discuss a more speculative, future observation that could be performed on the CM Draconis system that would be of exobiological as well as astrophysical interest. C1 NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. RP Schneider, J (reprint author), OBSERV PARIS,CNRS,F-92195 MEUDON,FRANCE. NR 60 TC 24 Z9 24 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-9295 J9 EARTH MOON PLANETS JI Earth Moon Planets PD NOV PY 1995 VL 71 IS 1-2 BP 153 EP 173 DI 10.1007/BF00612875 PG 21 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Geology GA TU197 UT WOS:A1995TU19700011 ER PT J AU HALL, FG SHIMABUKURO, YE HUEMMRICH, KF AF HALL, FG SHIMABUKURO, YE HUEMMRICH, KF TI REMOTE-SENSING OF FOREST BIOPHYSICAL STRUCTURE USING MIXTURE DECOMPOSITION AND GEOMETRIC REFLECTANCE MODELS SO ECOLOGICAL APPLICATIONS LA English DT Article DE BIOMASS; BIOPHYSICAL CHARACTERISTICS; BOREAL CONIFERS; GEOMETRIC REFLECTANCE MODELS; LEAF AREA INDEX; MIXTURE DECOMPOSITION; PHOTOSYNTHETICALLY ACTIVE RADIATION; PICEA MARIANA; REMOTE SENSING ID LEAF-AREA INDEX; RED-INFRARED SCATTERGRAMS; CANOPY REFLECTANCE; VEGETATION; PARAMETERS; LEAVES AB Using geometric shadow and linear mixture models we develop and evaluate an algorithm to infer several important structural parameters of stands of black spruce (Picea mariana), the most common boreal forest dominant. We show, first, that stand reflectances for this species can be represented as linear combinations of the reflectances of more elemental radiometric components: sunlit crowns, sunlit background, and shadow. Secondly, using a geometric model, we calculate how the fractions of these radiometric elements covary with each other. Then, using hand-held measurements of the reflectances of the sunlit background, sphagnum moss (Sphagnum spp.), and assuming shadow reflectance to be that of deep, clear lakes, we infer the reflectance of sunlit crowns from the geometric shadow model and low-altitude reflectance measurements acquired by a helicopter-mounted radiometer. Next, we assume that the reflectance for all black spruce stands is simply a linear combination of shadow, sunlit crown, and sunlit background reflectance, weighted in proportion to the relative areal fractions of these pixel elements. We then solve a set of Linear equations for the areal fractions of these elements using as input helicopter observations of total stand reflectance. Using this algorithm, we infer the values for the areal proportions of sunlit canopy, sunlit background, and shadow for 31 black spruce stands of varying biomass density, net primary productivity, etc. We show empirically and theoretically that the areal proportions of these radiometric elements are related to a number of stand biophysical characteristics. Specifically, the shadow fraction is increasing with increasing biomass density, average diameter at breast height, leaf area index (LAI), and aboveground net primary productivity (NPP), while sunlit background fraction is decreasing. We show that the end member fractions can be used to estimate biomass with a standard error of approximate to 2 kg/m(2), LAT with a standard error of 0.58, dbh with a standard error of approximate to 2 cm, and aboveground NPP with a standard error of 0.07 kg . m(-2). yr(-1). We. also show that the fraction of sunlit canopy is only weakly correlated with the biophysical variables and are thus able to show why a popular vegetation index, Normalized Difference Vegetation Index (NDVI), does not provide a useful measure of these biophysical characteristics. We do show, however, that NDVI should be related to the fraction of photosynthetically active radiation incident upon and absorbed by the canopy. This work has convinced us that a paradigm shift in the remote sensing of biophysical characteristics is in order-a shift away from direct inference of biophysical characteristics from vegetation indices and toward a two-step process, in which (1) stand-level reflectance is approximated in terms of linear combinations of reflectance-invariant, spectrally distinct components (spectral end members) and mixture decomposition used to infer the areal fractions of these components, e.g., shadow, sunlit crown, and sunlit background, followed by (2) the use of radiative transfer models to compute biophysical characteristic values as a function of the end member fractions. C1 INST NACL PESQUISAS ESPACIAIS,S JOSE CAMPOS,SP,BRAZIL. HUGHES STX,GREENBELT,MD 20771. RP HALL, FG (reprint author), GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 35 TC 173 Z9 182 U1 1 U2 20 PU ECOLOGICAL SOC AMER PI TEMPE PA ARIZONA STATE UNIV CENTER ENVIRONMENTAL STUDIES, TEMPE, AZ 85287 SN 1051-0761 J9 ECOL APPL JI Ecol. Appl. PD NOV PY 1995 VL 5 IS 4 BP 993 EP 1013 DI 10.2307/2269350 PG 21 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA TF375 UT WOS:A1995TF37500015 ER PT J AU BURT, JL BARTOLOME, DS BURDETTE, DW COMSTOCK, JR AF BURT, JL BARTOLOME, DS BURDETTE, DW COMSTOCK, JR TI A PSYCHOPHYSIOLOGICAL EVALUATION OF THE PERCEIVED URGENCY OF AUDITORY WARNING SIGNALS SO ERGONOMICS LA English DT Article DE AUDITORY WARNINGS; PERCEIVED URGENCY; SITUATIONAL URGENCY; REACTION TIME; PSYCHOPHYSIOLOGY; ELECTROENCEPHALOGRAM (EEG); EVENT-RELATED BRAIN POTENTIALS (ERPS) AB One significant concern that pilots have about cockpit auditory warnings is that the signals presently used lack a sense of priority. The relationship between auditory warning sound parameters and perceived urgency is, therefore, an important topic of enquiry in aviation psychology. The present investigation examined the relationship among subjective assessments of urgency, reaction time, and brainwave activity with three auditory warning signals. Subjects performed a tracking task involving automated and manual conditions, and were presented with auditory warnings having various levels of perceived and situational urgency. Subjective assessments revealed that subjects were able to rank warnings on an urgency scale, but rankings were altered after warnings were mapped to a situational urgency scale. Reaction times differed between automated and manual tracking task conditions, and physiological data showed attentional differences in response to perceived and situational warning urgency levels. This study shows that the use of physiological measures sensitive to attention and arousal, in conjunction with behavioural and subjective measures, may lead to the design of auditory warnings that produce a sense of urgency in an operator that matches the urgency of the situation. C1 LOCKHEED MARTIN ENGN & SCI CO,HAMPTON,VA 23666. RP BURT, JL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 38 TC 34 Z9 34 U1 0 U2 9 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0014-0139 J9 ERGONOMICS JI Ergonomics PD NOV PY 1995 VL 38 IS 11 BP 2327 EP 2340 DI 10.1080/00140139508925271 PG 14 WC Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Engineering; Psychology GA TE257 UT WOS:A1995TE25700014 PM 7498191 ER PT J AU Worrall, W Muhonen, D Menrad, R Berner, C AF Worrall, W Muhonen, D Menrad, R Berner, C TI The SOHO ground segment and operations SO ESA BULLETIN-EUROPEAN SPACE AGENCY LA English DT Article RP Worrall, W (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI NOORDWIJK PA ESTEC, PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0376-4265 J9 ESA BULL-EUR SPACE JI ESA Bull.-Eur. Space Agency PD NOV PY 1995 IS 84 BP 104 EP 110 PG 7 WC Engineering, Aerospace SC Engineering GA UD598 UT WOS:A1995UD59800012 ER PT J AU KRAUSS, LM TURNER, MS AF KRAUSS, LM TURNER, MS TI THE COSMOLOGICAL CONSTANT IS BACK SO GENERAL RELATIVITY AND GRAVITATION LA English DT Article ID UNIVERSE; CLUSTERS; SCALE; AGE AB A diverse set of observations now compellingly suggest that the universe possesses a nonzero cosmological constant. In the context of quantum-field theory a cosmological constant corresponds to the energy density of the vacuum, and the favored value for the cosmological constant corresponds to a very tiny vacuum energy density. We discuss future observational tests for a cosmological constant as well as the fundamental theoretical challenges - and opportunities - that this poses for particle physics and for extending our understanding of the evolution of the universe back to the earliest moments. C1 CASE WESTERN RESERVE UNIV,DEPT ASTRON,CLEVELAND,OH 44106. UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTROPHYS,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP KRAUSS, LM (reprint author), CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106, USA. NR 29 TC 260 Z9 263 U1 2 U2 13 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0001-7701 J9 GEN RELAT GRAVIT JI Gen. Relativ. Gravit. PD NOV PY 1995 VL 27 IS 11 BP 1137 EP 1144 DI 10.1007/BF02108229 PG 8 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA TE089 UT WOS:A1995TE08900002 ER PT J AU ZOLENSKY, ME THOMAS, KL AF ZOLENSKY, ME THOMAS, KL TI IRON AND IRON-NICKEL SULFIDES IN CHONDRITIC INTERPLANETARY DUST PARTICLES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID CARBONACEOUS CHONDRITES; MINERALOGY; ELEMENTS; MATRIX AB We report the results of a study of iron and iron-nickel sulfides in chondritic anhydrous and hydrated interplanetary dust particles (IDPs). The IDPs were characterized using chemical and mineralogical techniques including energy dispersive X-ray analyses and transmission electron microscopy. It is widely believed that the first sulfur-containing mineral to form in the early solar nebula should have been stoichiometric FeS (troilite), and that pyrrhotite is of secondary origin. All examined interplanetary dust particles, both anhydrous and hydrous types, contain more pyrrhotite than troilite, suggesting that the former was a common, possibly predominant nebular condensate phase. Pyrrhotite could form from sulfidation of troilite, after the latter had exfoliated from substrate metal grains. In contrast to anhydrous IDPs, hydrated ones contain Ni-rich sulfides, including pentlandite, which are probably of secondary origin. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP ZOLENSKY, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN2,HOUSTON,TX 77058, USA. NR 40 TC 51 Z9 51 U1 0 U2 3 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 NOV PY 1995 VL 59 IS 22 BP 4707 EP 4712 DI 10.1016/0016-7037(95)00329-0 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TH383 UT WOS:A1995TH38300012 ER PT J AU ESHET, Y RAMPINO, MR VISSCHER, H AF ESHET, Y RAMPINO, MR VISSCHER, H TI FUNGAL EVENT AND PALYNOLOGICAL RECORD OF ECOLOGICAL CRISIS AND RECOVERY ACROSS THE PERMIAN-TRIASSIC BOUNDARY SO GEOLOGY LA English DT Article ID TERTIARY BOUNDARY; ASSEMBLAGES; ISRAEL AB The end of the Permian Period was marked by the most severe mass extinction in the geologic record. Detailed quantitative study of pollen and spores from shallow-marine deposits spanning the Permian-Triassic (P-Tr) boundary in Israel reveals a sequence of palynological-ecological stages reflecting a major crisis among land plants. The disappearance of the gymnosperm-dominated palynoflora of the Late Permian Lueckisporites virkkiae Zone is recorded at a claystone horizon containing almost exclusively abundant fungal remains and carbonized terrestrial plant debris. This ''fungal spike'' is followed by a zone dominated by marine acritarchs and a succession showing ecological recovery with abundant lycopod spores and eventual reappearance of bisaccate gymnosperm pollen in the Early Triassic The latest Permian proliferation of fungi is recognizable worldwide and can be correlated with other paleontological and geochemical markers of a global ecological disaster. C1 NYU,DEPT BIOL,EARTH SYST GRP,NEW YORK,NY 10003. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV UTRECHT,PALAEOBOT & PALYNOL LAB,3584 CS UTRECHT,NETHERLANDS. RP ESHET, Y (reprint author), GEOL SURVEY ISRAEL,IL-95501 JERUSALEM,ISRAEL. NR 41 TC 99 Z9 112 U1 2 U2 9 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD NOV PY 1995 VL 23 IS 11 BP 967 EP 970 DI 10.1130/0091-7613(1995)023<0967:FEAPRO>2.3.CO;2 PG 4 WC Geology SC Geology GA TD518 UT WOS:A1995TD51800002 ER PT J AU IVINS, ER SAMMIS, CG AF IVINS, ER SAMMIS, CG TI ON LATERAL VISCOSITY CONTRAST IN THE MANTLE AND THE RHEOLOGY OF LOW-FREQUENCY GEODYNAMICS SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE CONSTITUTIVE THEORY; HETEROGENEITY; LONG-PERIOD TIDES; MANTLE VISCOSITY; Q; SHEAR MODULUS DISPERSION ID HIGH-TEMPERATURE CREEP; SEISMIC TOMOGRAPHY; CHANDLER-WOBBLE; SOUND VELOCITIES; PLATE VELOCITIES; SHEAR PROPERTIES; SINGLE-CRYSTALS; EARTHS MANTLE; HIGH-PRESSURE; WAVE AB Mantle-wide heterogeneity is largely controlled by deeply penetrating thermal convective currents. These thermal currents are likely to produce significant lateral variation in theology, and this can profoundly influence overall material behaviour. How thermally related lateral viscosity variations impact models of glacio-isostatic and tidal deformation is largely unknown. An important step towards model improvement is to quantify, or bound, the actual viscosity variations that characterize the mantle. Simple scaling of viscosity to shear-wave velocity fluctuations yields map-views of long-wavelength viscosity variation. These give a general quantitative description and aid in estimating the depth dependence of theological heterogeneity throughout the mantle. The upper mantle is probably characterized by two to four orders of magnitude variation (peak-to-peak). Discrepant time-scales for rebounding Holocene shorelines of Hudson Bay and southern Iceland are consistent with this characterization. Results are given in terms of a local average viscosity ratio, Delta ($) over bar eta(i), of volumetric concentration, phi(i). For the upper mantle deeper than 340km the following reasonable limits are estimated for Delta ($) over bar eta approximate to 10(-2): 0.01 less than or equal to phi less than or equal to 0.15. A spectrum of ratios Delta ($) over bar eta(i) < 0.1 at concentration level phi(i) approximate to 10(-6)-10(-1) in the lower mantle implies a spectrum of shorter time-scale deformational response modes for second-degree spherical harmonic deformations of the Earth. Although highly uncertain, this spectrum of spatial variation allows a purely Maxwellian viscoelastic theology simultaneously to explain all solid tidal dispersion phenomena and long-term rebound-related mantle viscosity. Composite theory of multiphase viscoelastic media is used to demonstrate this effect. C1 CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, PASADENA, CA 91109 USA. RP IVINS, ER (reprint author), UNIV SO CALIF, DEPT EARTH SCI, LOS ANGELES, CA 90089 USA. NR 84 TC 48 Z9 49 U1 0 U2 1 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD NOV PY 1995 VL 123 IS 2 BP 305 EP 322 DI 10.1111/j.1365-246X.1995.tb06856.x PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD778 UT WOS:A1995TD77800001 ER PT J AU YUE, GK THOMASON, LW POOLE, LR WANG, PH BAUMGARDNER, D DYE, JE AF YUE, GK THOMASON, LW POOLE, LR WANG, PH BAUMGARDNER, D DYE, JE TI AEROSOL SURFACE-AREAS DEDUCED FROM EARLY 1993 SAGE-II DATA AND COMPARISONS WITH STRATOSPHERIC PHOTOCHEMISTRY, AEROSOLS, AND DYNAMICS EXPEDITION MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EL-CHICHON; EXTINCTION; ERUPTION; PINATUBO; OZONE AB Stratospheric Aerosol and Gas Experiment II (SAGE II) multi-wavelength stratospheric aerosol extinction measurements are used to estimate near-global distributions of aerosol surface area density for early months of 1993. A comparison of monthly contour plots shows that the aerosol surface area density above the tropopause gradually decreased from about 15 mu m(2)cm(-3) in January 1993 to about 10 mu m(2)cm(-3) in May 1993. Aerosol surface area density profiles measured by the Forward Scattering Spectrometer Probe (FSSP-300) during the Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE) campaign in May 1993 are compared with estimated SAGE II surface area density profiles obtained at nearby locations. FSSP measurements are in general, slightly lower than the SAGE II measurements. The possible sources of this discrepancy are discussed. When 4-day average FSSP measurements are compared with the SAGE II zonal mean profile for May 1993 and 35 degrees N-40 degrees N at altitudes above 16 km, the agreement is good. In addition, SAGE II aerosol surface area density profiles calculated by assuming a lognormal size distribution and by using principal component analysis are compared, good agreement is shown at high altitudes. However, at low altitudes their differences may be as high as 25%. C1 SCI & TECHNOL CORP,HAMPTON,VA 23666. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP YUE, GK (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. OI Thomason, Larry/0000-0002-1902-0840 NR 14 TC 16 Z9 16 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 NOV 1 PY 1995 VL 22 IS 21 BP 2933 EP 2936 DI 10.1029/95GL02941 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800013 ER PT J AU GELLER, MA YUDIN, V DOUGLASS, AR WATERS, JW ELSON, LS ROCHE, AE RUSSELL, JM AF GELLER, MA YUDIN, V DOUGLASS, AR WATERS, JW ELSON, LS ROCHE, AE RUSSELL, JM TI UARS PSC, CLONO2, HCL, AND CLO MEASUREMENTS IN EARLY WINTER - ADDITIONAL VERIFICATION OF THE PARADIGM FOR CHLORINE ACTIVATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; STRATOSPHERE; OZONE; VORTEX AB We present an example of observations within a single air mass of ClO, ClONO2, and HCl from the instruments on the UARS spacecraft. A three-dimensional chemistry-transport calculation for HCl is used to show that this air mass has been transported through regions cold enough for polar stratospheric cloud formation and chlorine activation through heterogeneous chemical reactions. These data, together with modeling of HCl with and without heterogeneous loss as a qualitative measure of polar processing, indicate directly the transformation of the reservoirs HCl and ClONO2 to reactive chlorine species. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP GELLER, MA (reprint author), SUNY STONY BROOK,INST TERR & PLANETARY ATMOSPHERES,STONY BROOK,NY 11794, USA. RI Douglass, Anne/D-4655-2012 NR 16 TC 11 Z9 11 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 1995 VL 22 IS 21 BP 2937 EP 2940 DI 10.1029/95GL01661 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800014 ER PT J AU MANNEY, GL ZUREK, RW FROIDEVAUX, L WATERS, JW AF MANNEY, GL ZUREK, RW FROIDEVAUX, L WATERS, JW TI EVIDENCE FOR ARCTIC OZONE DEPLETION IN LATE FEBRUARY AND EARLY MARCH 1994 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX; WINTER; TRENDS AB Significant chemical ozone (O-3) loss in the 1993-94 Arctic winter occurred mainly during an unusually late cold spell of similar to 10 days in late Feb/early Mar. Over the 30 d period studied (including the cold spell), observed vortex-averaged O-3 at 465 K (similar to 40 hPa) decreased by similar to 10. New three-dimensional, diabatic trajectory calculations show that this observed decrease represents only about half of the net chemical. loss (similar to 20%) during the 30 day period. The resupply of lower stratospheric O-3 by transport in Feb 1994 was considerably greater than in 1993, when transport masked only about a quarter of the chemical loss in Feb/Mar. The net estimated chemical loss over 30 days in 1994 was comparable to that over the same 30 days in 1993, but mainly occurred at a faster rate during the brief cold spell. These results highlight the impact of Arctic interannual variability on the relative roles of chemistry and dynamics in O-3 evolution during recent Arctic winters. RP MANNEY, GL (reprint author), CALTECH,JET PROP LAB,MAIL STOP 183-701,PASADENA,CA 91109, USA. NR 14 TC 29 Z9 29 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 NOV 1 PY 1995 VL 22 IS 21 BP 2941 EP 2944 DI 10.1029/95GL02229 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800015 ER PT J AU ALLISON, M DELGENIO, AD ZHOU, W AF ALLISON, M DELGENIO, AD ZHOU, W TI RICHARDSON-NUMBER CONSTRAINTS FOR THE JUPITER AND OUTER PLANET WIND REGIME SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE; VENUS; PROBE; WAVES AB Present theories of the dynamics of the outer planet atmospheres are limited by the absence of direct observations of the wind and temperature layering below their visible cloud decks. We show that if the potential vorticity is assumed to be small at low latitudes. then cloud-tracked wind measurements of the equatorial flow on Jupiter, Saturn, Uranus, and Neptune can be used to constrain their vertical stratification at deeper levels. A Richardson number between 1.2 and 4 is indicated for all the giant planets, which at their rapid rotation implies a much more vertical isentropic structure at these levels than is realized in the terrestrial atmospheres. These conditions signify the likely presence of a unique but as yet unstudied regime for the jovian meteorology, illustrated by a new ''Richardson-Rossby'' diagram for comparative planetary circulations. The Jupiter case will be directly tested by the Galileo atmospheric entry probe. C1 SCI SYST & APPLICAT INC,INST SPACE STUDIES,NEW YORK,NY 10025. RP ALLISON, M (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 27 TC 21 Z9 21 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 NOV 1 PY 1995 VL 22 IS 21 BP 2957 EP 2960 DI 10.1029/95GL02818 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800019 ER PT J AU HO, CM TSURUTANI, BT AF HO, CM TSURUTANI, BT TI DISTANT TAIL PLASMA JETTING AND B-Z PROPERTIES AT SLOW-MODE SHOCKS - A MODEL OF RECONNECTION DURING NORTHWARD IMFS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ISEE-3; MAGNETOTAIL AB Previous distant geotail studies find a difference in the locations where the plasma flow reverses direction (x approximate to -120 R(e)) and where the magnetic field B-Z reverses (x approximate to -200 R(e)). These results raise some questions about the standard Petchek reconnection model and its applicability. In this study, we use 66 slow-mode shock events to study the flow properties both earthward and tailward of the x-type neutral line. The location of the neutral line relative to the spacecraft is determined by: a) use of the measured slow-mode shock orientation, and b) the magnetic B-Z polarity. We find that plasmasheet flow speeds downstream of slow shocks are similar, using either of the above two methods. On average, for events tailward of the neutral line, the tailward flow speed is statistically higher than for earthward cases by similar to 100 - 150 km/s. This is consistent with magnetic reconnection where jetting plasma flows of 50 - 75 km/s are superposed on top of a more-or-less continuous high speed tailward convection flow of similar to 600 km/s. By examining the relationship between these slow shock events in the distant tail and upstream IMF orientations, we also find that a significant amount (40%) of slow shock events occurs during northward IMFs. Thus, we propose a distant tail model of reconnection during northward IMF periods. Using this model and the standard substorm reconnection model (southward IMF cases), we believe we can explain all observations in this paper. RP HO, CM (reprint author), CALTECH,JET PROP LAB,MS 169-506,PASADENA,CA 91109, USA. NR 16 TC 3 Z9 3 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 1995 VL 22 IS 21 BP 2977 EP 2980 DI 10.1029/95GL02794 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800024 ER PT J AU PAULARENA, KI SZABO, A RICHARDSON, JD AF PAULARENA, KI SZABO, A RICHARDSON, JD TI COINCIDENT 1.3-YEAR PERIODICITIES IN THE AP GEOMAGNETIC INDEX AND THE SOLAR-WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LONG-TERM AVERAGES; SPECTRAL-ANALYSIS; MAGNETIC-FIELD; MAGNETOSPHERE; SPEED AB Recent observations show an approximately 1.3-year period in the speed of the solar wind detected by the IMP 8 and Voyager 2 spacecraft. A similar period is also seen in the north-south (GSE) component of the magnetic field observed by IMP 8. Since both parameters are commonly used as input to models of geomagnetic activity, the csp index (a measure of geomagnetic disturbance) is examined to look for this periodicity. The Lomb-Scargle periodogram method is used on the ap, plasma, and magnetic field data during the 1973-1994 time range. A dynamic FFT periodogram method is also used to analyze the ap data during this time, as well as to look for periods present between 1932 and 1972. A clear 1.3-year periodicity is present in the post-1986 data when the same period is observed in the plasma and field data. The V-2 B-zsm and V-2 B-s proxies for geomagnetic activity also show this periodicity. However, the southward (GSM) component of the magnetic field does not have a 1.3-year period, and neither do solar wind or ap data from 1973-1985. This, demonstrates that the ap geomagnetic index can act as a proxy for solar wind periodicities at this time scale. Historic ap data are examined, and show that a similar periodicity in ap exists around 1942. Since auroral data show a 1.4-year periodicity, all these similar periods may result from a common underlying solar mechanism. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP MIT, CTR SPACE RES, CAMBRIDGE, MA 02139 USA. NR 24 TC 60 Z9 61 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 1995 VL 22 IS 21 BP 3001 EP 3004 DI 10.1029/95GL02802 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800030 ER PT J AU BENSON, RF AF BENSON, RF TI THE AURORAL RADIATING PLASMA CAVITIES - COMMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HIGH-FREQUENCY LIMIT; KILOMETRIC RADIATION; SOURCE REGION; CYCLOTRON; WAVE; INSTABILITY; GENERATION; HARMONICS; PARTICLE; EMISSION RP BENSON, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 20 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 1995 VL 22 IS 21 BP 3005 EP 3007 DI 10.1029/95GL02621 PG 3 WC Geosciences, Multidisciplinary SC Geology GA TE108 UT WOS:A1995TE10800031 ER PT J AU RIZK, B HABERLE, RM HUNTEN, DM POLLACK, JB AF RIZK, B HABERLE, RM HUNTEN, DM POLLACK, JB TI MERIDIONAL TRANSPORT AND WATER RESERVOIRS IN SOUTHERN MARS DURING 1988-1989 SO ICARUS LA English DT Article ID POLAR-CAP; SEASONAL RECESSION; VAPOR OBSERVATIONS; VIKING; CYCLE; CIRCULATION; VARIABILITY; ATMOSPHERE AB Latitudinally resolved measurements of water-vapor column abundance in the martian atmosphere, obtained on four occasions in 1988-1989, are analyzed by a two-dimensional (2D) zonally symmetric water transport model. It predicted no substantial meridional water-vapor transport during the period covered by the observations. If the fundamental assumption of the model holds-that the mean meridional (overturning cell) and CO2 condensation/sublimation flows transport most of the water during this time of the martian year-then the southern midlatitudes are strongly indicated as the sink for the water that disappeared during this period. The model predicts the chances of the southern residual cap being the source of large amounts of water vapor during southern summer to be low. It also predicts that a very dusty atmosphere would have enhanced the transport of water vapor to the north during this season. (C) 1995 Academic Press, Inc. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP RIZK, B (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. NR 20 TC 6 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1995 VL 118 IS 1 BP 39 EP 50 DI 10.1006/icar.1995.1176 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TK354 UT WOS:A1995TK35400003 ER PT J AU BELL, JF HAWKE, BR AF BELL, JF HAWKE, BR TI COMPOSITIONAL VARIABILITY OF THE SERENITATIS TRANQUILLITATIS REGION OF THE MOON FROM TELESCOPIC MULTISPECTRAL IMAGING AND SPECTROSCOPY SO ICARUS LA English DT Article ID REFLECTANCE SPECTROSCOPY; SPECTRAL REFLECTANCE; LUNAR; COPERNICUS; RATIOS AB We present results from a combined CCD multispectral imaging and near-IR spectroscopic study of a region near the border between the Mare Serenitatis and Mare Tranquillitatis lunar impact basins. We have detected and spatially mapped variations in mare TiO2 abundance, in the degree of spectral maturity of impact craters and their ejecta blankets, and in the level of fresh highlands contamination within mare units. Techniques employed include color ratio images, image-oriented linear mixing models, and spectral band analyses. Specific findings include the detection of relatively fresh highlands materials in the craters Tacquet and Sulpicius Gallus and in the central peak and floor of the crater Plinius, the detection of low-TiO2 Serenitatis-like mare materials in a confined region of the ejecta from the crater Dawes, and the determination of immaturity rather than composition as the origin of the high albedo in the rectangular deposit surrounding Dawes. The combination of high spatial resolution imaging and high spectral resolution spectroscopy and the use of synthesizing techniques such as mixture modeling will provide valuable tools to optimize the scientific return from telescopic, Galileo, Clementine, and other future lunar data sets. (C) 1995 Academic Press, Inc C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV HAWAII,SCH OCEAN EARTH & ATMOSPHER SCI,HAWAII INST GEOL & PLANETOL,HONOLULU,HI 96822. NR 46 TC 14 Z9 14 U1 1 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1995 VL 118 IS 1 BP 51 EP 68 DI 10.1006/icar.1995.1177 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TK354 UT WOS:A1995TK35400004 ER PT J AU COUSTENIS, A LELLOUCH, E MAILLARD, JP MCKAY, CP AF COUSTENIS, A LELLOUCH, E MAILLARD, JP MCKAY, CP TI TITANS SURFACE - COMPOSITION AND VARIABILITY FROM THE NEAR-INFRARED ALBEDO SO ICARUS LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; HYPOTHESIZED OCEAN; OPTICAL-CONSTANTS; ATMOSPHERE; SPECTRA; TEMPERATURE; MICROWAVE; METHANE; MODEL; ICE AB We report observations of Titan covering the 1.075-, 1.28-, 1.6-, and 2.0-mu m windows which show variations with the orbital phase, implying variability of the satellite's geometric albedo, as found earlier by other authors. The observations cover the region 4400 to 9600 cm(-1) and were taken in June 1991, August 1993, and September 1994, using the Fourier transform spectrometer at the CFH Telescope (Hawaii). The resolving power was 10000, 1000, and 300 for the 1991, 1993, and 1994 spectra, respectively. The data sets cover Titan's Greatest Western Elongation and opposite Conjunctions. We find Than's geometric albedo to be about the same (0.29) at 1.28 and 1.075 mu m. (On the other hand, our observations of Uranus show the 1.28-mu m albedo to be lower by 30% than that in the 1.075-mu m window.) The geometric albedos in the 1.6- and 2.0-mu m methane windows on Than are clearly lower (0.20 and 0.16, respectively). At the four wavelengths, a noticeable decrease in geometric albedo is observed near Greatest Western Elongation with respect to Inferior and Superior Conjunctions. The sum of the existing Titan data point to a bright leading side and a darker trailing one, with a maximum brightness near 120 degrees (+/-20 degrees) orbital longitude and a minimum near 230 degrees (+/-20 degrees. Despite important uncertainties in the value of the CH4 absorption coefficients in the window regions, modeling Titan's observed albedos strongly suggests the existence of a surface material with a comparable albedo at 1.075 and 1.28 mu m (0.4-0.5) but much darker at 1.6 and 2.0 mu m (about 0.2). Titan's surface spectrum appears consistent with that of Hyperion and we suggest that this behavior may be due to the dominant presence of water ice on Than's surface. The inhomogeneity of the surface implies that some other material(e.g., hydrocarbon lakes) is mixed with water ice in variable proportions. (C) 1995 Academic Press, Inc. C1 INST ASTROPHYS,F-75014 PARIS,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP COUSTENIS, A (reprint author), OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NR 37 TC 84 Z9 84 U1 0 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1995 VL 118 IS 1 BP 87 EP 104 DI 10.1006/icar.1995.1179 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TK354 UT WOS:A1995TK35400006 ER PT J AU MITCHELL, DL OSTRO, SJ ROSEMA, KD HUDSON, RS CAMPBELL, DB CHANDLER, JF SHAPIRO, II AF MITCHELL, DL OSTRO, SJ ROSEMA, KD HUDSON, RS CAMPBELL, DB CHANDLER, JF SHAPIRO, II TI RADAR OBSERVATIONS OF ASTEROIDS 7-IRIS, 9-METIS, 12-VICTORIA, 216-KLEOPATRA, AND 654-ZELINDA SO ICARUS LA English DT Article ID GALILEO PHYSICAL MODEL; IMPACT EXPERIMENTS; ROTATION AXES; SURFACE; OBJECTS; SHAPE; SPIN; FRAGMENTATION; VELOCITY; VENUS AB We report 13-cm wavelength radar observations of the main-belt asteroids 7 Iris, 9 Metis, 12 Victoria, 216 Kleopatra, and 654 Zelinda obtained at Arecibo between 1980 and 1989. The echoes are highly polarized yet broadly distributed in Doppler frequency, indicating that our targets are smooth on decimeter scales but very rough on some scale(s) larger than about 1 m. The echo spectra are generally consistent with existing size, shape, and spin information based on radiometric, lightcurve, and occultation data. All of our targets possess distinctive radar signatures that reveal large-scale topography. Reflectivity spikes within narrow ranges of rotation phase suggest large flat regions on Iris, Metis, and Zelinda, while bimodal spectra imply nonconvex, possibly bifurcated shapes for Kleopatra and Victoria. Kleopatra has the highest radar albedo yet measured for a main-belt asteroid, indicating a high metal concentration and making Kleopatra the best main-belt candidate for a core remnant of a differentiated and subsequently disrupted parent body. Upon completion of the Arecibo telescope upgrade, there will be several opportunities per year to resolve main-belt asteroids with hundreds of delay-Doppler cells, which can be inverted to provide estimates of both three-dimensional shape and radar scattering properties. (C) 1995 Academic Press, Inc. C1 WASHINGTON STATE UNIV,DEPT ELECT ENGN,PULLMAN,WA 99164. CORNELL UNIV,NATL ASTRON & IONOSPHERE CTR,ITHACA,NY 14853. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP MITCHELL, DL (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 69 TC 43 Z9 43 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 1995 VL 118 IS 1 BP 105 EP 131 DI 10.1006/icar.1995.1180 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TK354 UT WOS:A1995TK35400007 ER PT J AU DOBROVOLSKIS, AR AF DOBROVOLSKIS, AR TI CHAOTIC ROTATION OF NEREID SO ICARUS LA English DT Article ID NATURAL SATELLITES; NEPTUNE; HYPERION; DYNAMICS; ELEMENTS; PLUTO AB The shape and spin of Neptune's outermost satellite Nereid are still unknown. Ground-based photometry indicates large brightness variations, but different observers report very different lightcurve amplitudes and periods. On the contrary, Voyager 2 images spanning 12 days show no evidence of variations greater than 10%. The latter suggest either that Nereid is nearly spherical, or that it is rotating slowly. We propose that tides have already despun Nereid's rotation to a period of a few weeks, during the time before the capture of Triton when Nereid was closer to Neptune. Since Nereid reached its present 360-day orbit, tides have further despun Nereid to a period on the order of a month. For Nereid's orbital eccentricity of 0.75, tidal evolution ceases when the spin period is still similar to 1/8 of the orbital period. Furthermore, the synchronous resonance becomes quite weak for such high eccentricities, along with other low-order spin-orbit commensurabilities. In contrast, high-order resonances become very strong, particularly the 6:1, 6.5:1, 7:1, 7.5:1, and 8:1 spin states. If Nereid departs by more than similar to 1% from a sphere, however, these resonances overlap, generating chaos. Our simulations show that Nereid is likely to be in chaotic rotation for any spin period longer than about 2 weeks, with period and obliquity varying from year to year. (C) 1995 Academic Press, Inc. RP DOBROVOLSKIS, AR (reprint author), UNIV CALIF SANTA CRUZ, NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 37 TC 24 Z9 25 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 EI 1090-2643 J9 ICARUS JI Icarus PD NOV PY 1995 VL 118 IS 1 BP 181 EP 198 DI 10.1006/icar.1995.1184 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TK354 UT WOS:A1995TK35400011 ER PT J AU ELBULUK, ME AF ELBULUK, ME TI MOTOR BRIVE TECHNOLOGIES FOR THE POWER-BY-WIRE (PBW) PROGRAM - OPTIONS, TRENDS AND TRADEOFFS .1. MOTORS AND CONTROLLERS SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article ID SENSOR; DRIVES; POSITION AB The Power-By-Wire (PEW) program involves the replacement of hydraulic and pneumatic systems currently used in aircraft with an all-electric secondary power system. One of the largest loads of the all-electric secondary power system will be the motor loads which include pumps, compressors and Electrical Actuators (EAs). Issues of improved reliability, reduced maintenance and efficiency, among other advantages, are the motivation for replacing the existing aircraft actuators with electrical actuators. The EA system contains the motor, the power electronic converters, the actuator and the control system, including the sensors. This paper and a companion paper [1] give a comparative literature review in motor drive technologies, with a focus on the trends and tradeoffs involved in the selection of a particular motor drive technology. The reported research comprises the induction motor (IM), the brushless de motor (BLDCM) and the switched reluctance motor (SRM) drive technologies. Each of the three drives has the potential for application in the PEW program. Many issues remain to be investigated and compared between the three motor drives, using actual mechanical loads expected in the PEW program. C1 NASA, LEWIS RES CTR, DIV POWER TECHNOL, CLEVELAND, OH 44135 USA. RP UNIV AKRON, DEPT ELECT ENGN, AKRON, OH 44325 USA. NR 33 TC 10 Z9 10 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0885-8985 EI 1557-959X J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD NOV PY 1995 VL 10 IS 11 BP 37 EP 42 DI 10.1109/62.473411 PG 6 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA TD998 UT WOS:A1995TD99800009 ER PT J AU DEGNAN, JJ AF DEGNAN, JJ TI OPTIMIZATION OF PASSIVELY Q-SWITCHED LASERS SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article AB In optimizing passively Q-switched lasers, there is a unique choice of output coupler and unsaturated absorber transmission which maximizes the laser output energy and efficiency for each three-way combination of laser gain medium, absorber medium, and pump intensity (i.e., inversion density), In the present paper, we generalize and solve the three coupled differential equations which describe the passively Q-switched laser to obtain closed form solutions for key laser parameters such as the output energy and pulsewidth. We then apply the Lagrange multiplier technique to determine the optimum mirror reflectivities and unsaturated absorber transmissions as a function of two dimensionless variables. The first variable, z, corresponds to the ratio of the logarithmic round-trip small signal gain to the round-trip dissipative (nonuseful) optical loss and is identical to that which was used in previous treatments to optimize the rapidly Q-switched laser, The second variable, alpha, is unique to the passively Q-switched laser and is equal to the saturation energy density of the amplifying medium divided by the saturation energy density of the absorber, It is largely determined by the ration of the absorber to stimulated emission cross sections, but also depends on the speed of relaxation mechanisms in the amplifying and absorbing media relative to the resonator photon decay time, Several design curves, valid for all four level amplifying and absorbing media, are then generated. These permit the design of an optimum passively Q-switched laser and an estimate of its key performance parameters to be obtained quickly with the aid of a simple hand calculator. In the limit of large a (>10), the design curves are virtually indistinguishable from the rapidly Q-switched case, The curves can also be used to perform rapid tradeoff studies of different absorbing materials, The theory can also be applied to CW-pumped, repetitively Q-switched systems through a simple multiplicative factor for the laser gain, The theory is applied to the analysis of a passively Q-switched Nd:YAG laser previously reported in the literature and shown to give excellent agreement with the experimental results. RP DEGNAN, JJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 26 TC 292 Z9 310 U1 2 U2 42 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD NOV PY 1995 VL 31 IS 11 BP 1890 EP 1901 DI 10.1109/3.469267 PG 12 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA TC635 UT WOS:A1995TC63500003 ER PT J AU BASILI, V ZELKOWITZ, M MCGARRY, F PAGE, J WALIGORA, S PAJERSKI, R AF BASILI, V ZELKOWITZ, M MCGARRY, F PAGE, J WALIGORA, S PAJERSKI, R TI SELS SOFTWARE PROCESS-IMPROVEMENT PROGRAM SO IEEE SOFTWARE LA English DT Article C1 COMP SCI CORP,HOUSTON,TX. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BASILI, V (reprint author), UNIV MARYLAND,DEPT COMP SCI,4121 AV WILLIAMS,COLLEGE PK,MD 20742, USA. NR 6 TC 25 Z9 25 U1 1 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD NOV PY 1995 VL 12 IS 6 BP 83 EP 87 DI 10.1109/52.469763 PG 5 WC Computer Science, Software Engineering SC Computer Science GA TB597 UT WOS:A1995TB59700014 ER PT J AU WILSON, JD KORY, CL AF WILSON, JD KORY, CL TI SIMULATION OF COLD-TEST PARAMETERS AND RF OUTPUT POWER FOR A COUPLED-CAVITY TRAVELING-WAVE TUBE SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article ID TAPER AB Procedures have been developed which enable the accurate computation of the cold-test (absence of an electron beam) parameters and RF output power for the slow-wave circuits of coupled-cavity traveling-wave tubes (TWT's). The cold-test parameters, which consist of RF phase shift per cavity, impedance, and attenuation, are computed with the three-dimensional electromagnetic simulation code MAFIA and compared to experimental data for an existing V-band (59-64 GHz) coupled-cavity TWT. When simulated in cylindrical coordinates, the absolute average differences from experiment are only 0.3% for phase shift and 2.4% for impedance. Using the cold-test parameters calculated with MAFIA as input, the NASA Coupled-Cavity TWT Code is used to simulate the saturated RF output power of the TWT across the V-band frequency range, Taking into account the output window and coupler loss, the agreement with experiment is very good from 60-64 GHz, with the average absolute percentage difference between simulated and measured power only 3.8%. This demonstrates that the saturated RF output power of a coupled-cavity TWT can be accurately simulated using cold-test parameters determined with a three-dimensional electromagnetic simulation code. RP WILSON, JD (reprint author), NASA,LEWIS RES CTR,ANALEX CORP,CLEVELAND,OH 44135, USA. NR 22 TC 22 Z9 30 U1 2 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD NOV PY 1995 VL 42 IS 11 BP 2015 EP 2020 DI 10.1109/16.469412 PG 6 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA TB579 UT WOS:A1995TB57900022 ER PT J AU Hooker, SB Brown, JW Kirwan, AD AF Hooker, SB Brown, JW Kirwan, AD TI Detecting ''dipole ring'' separatrices with zebra palettes SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID WARM-CORE RING; STREAM AB Two new analysis methods applicable to remote sensing of the sea surface are described, The first is a zebra false-color palette that combines a slowly varying rainbow with a rapid gray-scale sinusoid, and the other is a routine that tracks the thermal separatrix, or dividing line, between two (or more) circulation regimes, Used together, a significant increase in data retention is achieved compared to traditional algorithms based on frontal digitizations. These two methods are applied to historical infrared data of Gulf Stream rings from the western North Atlantic. The rings data indicate anticyclonic rings usually have at least one clyclonic companion and are more appropriately modeled as dipoles, Several examples of cyclonic rings in the Sargasso Sea are seen with anticyclonic companions and are also believed to be dipoles, The separatrix method is shown to provide reliable rotation rates for these vortex systems. C1 NOAA,MPO,RSMAS,MIAMI,FL 33149. OLD DOMINION UNIV,NORFOLK,VA 23508. RP Hooker, SB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,OCEANS & ICE BRANCH,GREENBELT,MD 20771, USA. RI Hooker, Stanford/E-2162-2012 NR 11 TC 10 Z9 10 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1995 VL 33 IS 6 BP 1306 EP 1312 DI 10.1109/36.476345 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 TK448 UT WOS:A1995TK44800001 ER PT J AU Dubois, PC vanZyl, J Engman, T AF Dubois, PC vanZyl, J Engman, T TI Measuring soil moisture with imaging radars (vol 33, pg 915, 1995) SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Correction, Addition C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Dubois, PC (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 15 Z9 15 U1 2 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 1995 VL 33 IS 6 BP 1340 EP 1340 DI 10.1109/TGRS.1995.477194 PG 1 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA TK448 UT WOS:A1995TK44800011 ER PT J AU KATTI, RR AF KATTI, RR TI THE 1995 IEEE INTERNATIONAL MAGNETICS CONFERENCE - INTERMAG95 - MARRIOTT-RIVERCENTER-HOTEL - SAN-ANTONIO, TEXAS - APRIL 18-21, 1995 - INTRODUCTION SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Editorial Material RP KATTI, RR (reprint author), CALTECH,JET PROPULS LAB,PASADENA,CA 91109, 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD NOV PY 1995 VL 31 IS 6 BP U5 EP U5 PN 1 PG 1 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA TD556 UT WOS:A1995TD55600002 ER PT J AU WATKINS, SS CHAU, PM TAWEL, R LAMBRIGTSEN, B AF WATKINS, SS CHAU, PM TAWEL, R LAMBRIGTSEN, B TI EXECUTION OF A REMOTE-SENSING APPLICATION ON A CUSTOM NEUROCOMPUTER SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article AB A radial basis function neural network was successfully applied to an area which is relatively new for neural networks: a remote sensing application that provides estimates of water vapor content, an important parameter for climate modeling. The neural network provided results which are up to 32% better than had been previously obtained using conventional statistical methods on the same data These results have implications for improved short-term weather forecasting and for long-term global climate modeling. The neural network approach is compared with the past and present operating algorithms at the National Oceanic and Atmospheric Administration, The radial basis function network's performance is compared with sigmoidal backpropagation network. Low-power electronic implementations of the neural methodology were explored to demonstrate the feasibility of placing the network on a remote sensing platform, This would permit processing the ram sensor data into information on the platform, eliminating the need to store the raw data, and helping to contain the expected explosion of climate data. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WATKINS, SS (reprint author), UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093, USA. NR 50 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 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD NOV PY 1995 VL 6 IS 6 BP 1505 EP 1515 DI 10.1109/72.471359 PG 11 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA TC776 UT WOS:A1995TC77600020 PM 18263443 ER PT J AU HADDAD, ZS SIMANCA, SR AF HADDAD, ZS SIMANCA, SR TI FILTERING IMAGE RECORDS USING WAVELETS AND THE ZAKAI EQUATION SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE IMAGE FILTERING; ZAKAI EQUATION; WAVELETS; STOCHASTIC FILTER; TRACKING; IMAGE REPRESENTATION; NOISE; BROWNIAN MODEL; POISSON MODEL AB Consider the problem of detecting and localizing a faint object moving in an ''essentially stationary'' background, using a sequence of two-dimensional low-SNR images of the scene. A natural approach consists of ''digitizing'' each snapshot into a discrete set of observations, sufficiently (perhaps not exactly) matched to the object in question, then tracking the object using an appropriate stochastic filter. The tracking would be expected to make up for the low signal-to-noise ratio, thus allowing one to ''coherently'' process successive images in order to beat down the noise and localize the object. Thus, ''tracking'' here does not refer to the ususal notion of detecting then tracking: rather, we track in order to detect. The problem then becomes one of choosing the appropriate image representation as well as the optimal (and necessarily nonlinear) filter. We propose exact and approximate solutions using wavelets and the Zakai equation. The smoothness of the wavelets used is required in the derivation of the evolution equation for the conditional density giving the filter, and their orthogonality makes it possible to carry out actual computations of the Ito- and change-of-gauge-terms in the algorithm effectively. C1 SUNY STONY BROOK,DEPT MATH,STONY BROOK,NY 11794. RP HADDAD, ZS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE BLVD,PASADENA,CA 91100, USA. NR 13 TC 9 Z9 9 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0162-8828 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD NOV PY 1995 VL 17 IS 11 BP 1069 EP 1078 DI 10.1109/34.473232 PG 10 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA TD854 UT WOS:A1995TD85400005 ER PT J AU Woodard, SE Garg, DP Tyan, CY Wang, PP AF Woodard, SE Garg, DP Tyan, CY Wang, PP TI An application of fuzzy logic control to a gimballed payload on a space platform SO INFORMATION SCIENCES-APPLICATIONS LA English DT Article AB This paper will present results of applying two autonomous fuzzy controllers to a dynamically coupled system. The system consists of a space platform and a gimballed payload. The controllers are developed with the systems decoupled. Parametric studies are performed on the support limits for the error, change-in-error, and control. These parametric variations provide insight into satisfactorily tuning the controllers. The controllers were compared to controllers developed using Linear Quadratic Regulator (LQR) control design. The controllers are used to perform slew maneuvers and disturbance rejection. A design procedure using constraints due to hardware or software specification is also examined. When error and control support limits are specified, tuning the fuzzy controller is made relatively easy. The systems were coupled and the response of the payload and platform were examined for commanded payload trajectories and impulses applied to the platform. The fuzzy controllers performed very well in all cases. C1 DUKE UNIV,DEPT MECH ENGN & MAT SCI,DURHAM,NC 27706. DUKE UNIV,DEPT ELECT ENGN,DURHAM,NC 27706. RP Woodard, SE (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 15 TC 2 Z9 3 U1 1 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 1069-0115 J9 INFORM SCI-APPL JI Inf. Sci.-Appl. PD NOV PY 1995 VL 4 IS 3 BP 143 EP 166 PG 24 WC Computer Science, Information Systems SC Computer Science GA TP907 UT WOS:A1995TP90700001 ER PT J AU TESSLER, A TSUI, T SAETHER, E AF TESSLER, A TSUI, T SAETHER, E TI A (1,2)-ORDER THEORY FOR ELASTODYNAMIC ANALYSIS OF THICK ORTHOTROPIC SHELLS SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article ID SHEAR-DEFORMATION-THEORY; HIGHER-ORDER THEORY; ANISOTROPIC SHELLS; CYLINDRICAL-SHELLS; PLATE-THEORY AB A higher-order shell theory is developed for elastodynamic analysis of orthotropic shells. The theory accounts for all basic deformations including transverse shear and transverse normal strains and stresses. The theory is developed in orthogonal curvilinear coordinates in which the reference surface components of the displacement vector vary linearly through the thickness while the transverse displacement is parabolic. Transverse shear and transverse normal strains are formulated to satisfy physical traction conditions at the top and bottom shell surfaces, and are also made least-squares compatible with the corresponding strains that are derived directly from the strain-displacement relations of three-dimensional elasticity. In these variational statements of strain compatibility, transverse shear and transverse normal correction factors are introduced, and are determined from dynamic considerations in the manner originally proposed by Mindlin. Equations of motion and associated engineering (Poisson) boundary conditions are derived from a three-dimensional variational principle. An important feature of the present theory is the requirement of only simple C-0 and C-1 continuity for the shell kinematic variables. This aspect makes the theory particularly attractive for the development of efficient shell finite elements suitable for general purpose finite element analysis of thick shell structures. Analytical solutions for the free vibration of isotropic and orthotropic cylindrical shells are obtained for a wide range of thickness/radius and thickness/wavelength ratios and found to be in close agreement with the exact elasticity solutions. C1 USA, RES LAB, MAT DIRECTORATE, WATERTOWN, MA 02172 USA. RP TESSLER, A (reprint author), NASA, LANGLEY RES CTR, COMPUTAT STRUCT BRANCH, MAIL STOP 240, HAMPTON, VA 23681 USA. RI Tessler, Alexander/A-4729-2009 NR 38 TC 5 Z9 5 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 EI 1879-2146 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD NOV PY 1995 VL 32 IS 22 BP 3237 EP 3260 DI 10.1016/0020-7683(94)00312-K PG 24 WC Mechanics SC Mechanics GA RQ933 UT WOS:A1995RQ93300001 ER PT J AU Obayashi, S Chiu, IT Guruswamy, GP AF Obayashi, S Chiu, IT Guruswamy, GP TI Navier-Stokes computations on full wing-body configuration with oscillating control surfaces SO JOURNAL OF AIRCRAFT LA English DT Article AB Unsteady Navier-Stokes simulations have been performed for vortical flows over an ''arrow-wing'' configuration of a supersonic transport in the transonic regime. Computed steady pressures and integrated force coefficients with and without control surface deflection at a moderate angle of attack are compared with experiment. For unsteady cases, oscillating trailing-edge control surfaces are modeled by using moving grids. Response characteristics between symmetric and antisymmetric oscillatory motions of the control surfaces on the left and right wings are studied. The antisymmetric case produces higher lift than the steady case with no deflection and the unsteady symmetric case produces higher lift than the antisymmetric case. The detailed analysis of the wake structure revealed a strong interaction between the primary vortex and the wake vortex sheet from the nap region when the flap is deflected up. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1227 EP 1233 DI 10.2514/3.46868 PG 7 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900009 ER PT J AU Huebner, LD AF Huebner, LD TI Computational inlet-fairing effects and plume characterization on a hypersonic powered model SO JOURNAL OF AIRCRAFT LA English DT Article AB A three-dimensional computational study has been performed addressing issues related to the wind-tunnel testing of a hypersonic powered-simulation model. The study consisted of two related objectives. The first objective was to determine the three-dimensional flow effects on the aftbody created by fairing over the inlet; this was accomplished by comparing the computational fluid dynamics solutions of two closed-inlet powered configurations with a flowing-inlet powered configuration. Results at four freestream Mach numbers indicate that the exhaust plume tends to isolate the aftbody surface from most forebody flowfield differences, a smooth inlet fairing provides the least aftbody force and moment variation compared to a flowing inlet. The second objective was to predict and understand the three-dimensional characteristics of exhaust plume development at selected points on a representative flight path of a single-stage-to-orbit vehicle. Results showed a dramatic effect of plume expansion onto the wings as the freestream Mach number and corresponding nozzle pressure ratio are increased. RP Huebner, LD (reprint author), NASA,LANGLEY RES CTR,DIV GAS DYNAM,HYPERSON AIRBREATHING PROP,M-S 168,HAMPTON,VA 23681, USA. NR 0 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1240 EP 1245 DI 10.2514/3.46870 PG 6 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900011 ER PT J AU Anderson, WK Bonhaus, DL McGhee, RJ Walker, BS AF Anderson, WK Bonhaus, DL McGhee, RJ Walker, BS TI Navier-Stokes computations and experimental comparisons for multielement airfoil configurations SO JOURNAL OF AIRCRAFT LA English DT Article AB A two-dimensional unstructured Navier-Stokes code is utilized for computing the flow around multielement airfoil configurations. Comparisons are shown for a landing configuration with an advanced-technology flap. Grid convergence studies are conducted to assess inaccuracies caused by inadequate grid resolution, Although adequate resolution is obtained for determining the pressure distributions, further refinement is needed to sufficiently resolve the velocity profiles at high angles of attack. For the advanced flap configuration, comparisons of pressure distributions and lift are made with experimental data. Here, two flap riggings and two Reynolds numbers are considered. In general, the trends caused by variations in these quantities are well predicted by the computations, although the angle of attack for maximum lift is overpredicted. RP Anderson, WK (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,HAMPTON,VA 23681, USA. NR 0 TC 16 Z9 16 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1246 EP 1253 DI 10.2514/3.46871 PG 8 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900012 ER PT J AU Rossow, VJ AF Rossow, VJ TI Validation of vortex-lattice method for loads on wings in lift-generated wakes SO JOURNAL OF AIRCRAFT LA English DT Article AB A study is described that evaluates the accuracy of vortex-lattice methods when they are used to compute the loads induced on aircraft as they encounter lift-generated wakes. The evaluation is accomplished by the use of measurements made in the 80 by 120 ft Wind Tunnel of the lift, rolling moment, and downwash in the wake of three configurations of a model of a subsonic transport aircraft. The downwash measurements are used as input for a vortex-lattice code in order to compute the lift and rolling moment induced on wings that have a span of 0.186, 0.510, or 1.022 times the span of the wake-generating model. Comparison of the computed results with the measured lift and rolling-moment distributions the vortex-lattice method is very reliable as long as the span of the encountering or following wing is less than about 0.2 of the generator span. As the span of the following wing increases above 0.2, the vortex-lattice method continues to correctly predict the trends and nature of the induced loads, but it overpredicts the magnitude of the loads by increasing amounts. RP Rossow, VJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1254 EP 1262 DI 10.2514/3.46872 PG 9 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900013 ER PT J AU Goodrich, KH McManus, JW Chappell, AR AF Goodrich, KH McManus, JW Chappell, AR TI Batch simulation environment for integrated batch and piloted air combat analysis SO JOURNAL OF AIRCRAFT LA English DT Article AB A batch air combat simulation environment known as the tactical maneuvering simulator (TMS) is presented. The TMS serves as a tool for developing and evaluating tactical maneuvering logics. The environment can also be used to evaluate the tactical implications of perturbations to aircraft performance or supporting systems. The TMS is capable of simulating air combat between any number of engagement participants, with practical limits imposed by computer memory and processing power. Aircraft are modeled using equations of motion, control laws, aerodynamics, and propulsive characteristics equivalent to those used in high-fidelity piloted simulation. Databases representative of a modern high-performance aircraft with and without thrust-vectoring capability are included. To simplify the task of developing and implementing maneuvering logics in the TMS, an outer-loop control system known as the tactical autopilot (TA) is implemented in the aircraft simulation model. The TA converts guidance commands issued by computerized maneuvering logics in the form of desired angle of attack and wind axis-bank angle into inputs to the inner-loop control augmentation system of the aircraft. This article describes the capabilities and operation of the TMS. RP Goodrich, KH (reprint author), NASA,LANGLEY RES CTR,AIRCRAFT GUIDANCE & CONTROLS BRANCH,M-S 489,HAMPTON,VA 23681, USA. OI Chappell, Alan/0000-0003-0479-3223 NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1263 EP 1268 DI 10.2514/3.46873 PG 6 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900014 ER PT J AU Ambur, DR Cerro, JA Dickson, J AF Ambur, DR Cerro, JA Dickson, J TI D-box fixture for testing stiffened panels in compression and pressure SO JOURNAL OF AIRCRAFT LA English DT Article AB A combined loads test machine used to test aircraft primary structures such as fuselage and wing sections is described. The design features of a D-box test fixture that provides a simple test setup with the flexibility to accommodate curved stiffened panels of different radii are presented. Linear finite element analysis results from studies performed to evaluate and to address problems associated with load introduction into a curved panel when tested in the D-box test fixture with compression and internal pressure loading are also presented and discussed. From the analysis results it is determined that by providing cross bars with adjustable lengths in the D-box test fixture, appropriate boundary conditions and the proper load distributions can be simulated for undamaged and damaged curved panels with different frame spacing subjected to internal pressure and axial compression, Nonlinear shell analysis results for both the internal pressure and combined internal pressure and axial compression cases suggest that the deflection and stress states in the panel for these load cases are much larger than those obtained from linear analysis. RP Ambur, DR (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23681, USA. NR 0 TC 2 Z9 2 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 1995 VL 32 IS 6 BP 1382 EP 1389 PG 8 WC Engineering, Aerospace SC Engineering GA TK779 UT WOS:A1995TK77900030 ER PT J AU ATLAS, D MATROSOV, SY HEYMSFIELD, AJ CHOU, MD WOLFF, DB AF ATLAS, D MATROSOV, SY HEYMSFIELD, AJ CHOU, MD WOLFF, DB TI RADAR AND RADIATION PROPERTIES OF ICE CLOUDS SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CIRRUS; PARAMETERIZATION; REFLECTIVITY; CLIMATE AB The authors derive relations of the equivalent radar reflectivity Z(e) and extinction coefficient alpha of ice clouds and confirm the theory by in situ aircraft observations during the First International Satellite Cloud Climatology Project Regional Experiment. Equivalent radar reflectivity Z(e) is a function of ice water content W and a moment of the size distribution such as the median volume diameter D-0. Stratification of the data by Do provides a set of W-Z(e) relations from which one may deduce the dependence of particle density on size. This relation is close to that of Brown and Francis and provides confidence in the methodology of estimating particle size and mass. The authors find that there is no universal W-Z(e) relation, due both to large scatter and systematic shifts in particle size from day to day and cloud to cloud. These variations manifest the normal changes in ice crystal growth. The result is that, with the exception of temperatures less than -40 degrees C, temperature cannot be used to reliably parameterize the particle size as has been previously suggested. To do so is to risk large possible systematic errors in retrievals. Even if one could measure monthly averages of ice water content, this is inadequate to estimate the monthly radiative effect because of the nonlinearity between the two. The authors show that a sizable fraction of radiatively significant clouds would be missed at a radar threshold of -30 dBZ, the value proposed for a spaceborne cloud-profiling radar. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,ETL,BOULDER,CO 80309. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. APPL RES CORP,LANDOVER,MD 20785. RI Heymsfield, Andrew/E-7340-2011 NR 47 TC 91 Z9 93 U1 1 U2 4 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 NOV PY 1995 VL 34 IS 11 BP 2329 EP 2345 DI 10.1175/1520-0450(1995)034<2329:RARPOI>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TC123 UT WOS:A1995TC12300001 ER PT J AU RODGERS, EB PIERCE, HF AF RODGERS, EB PIERCE, HF TI ENVIRONMENTAL INFLUENCE ON TYPHOON-BOBBIE PRECIPITATION DISTRIBUTION SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID ANGULAR-MOMENTUM FLUXES; TROPICAL CYCLONE; SATELLITE-OBSERVATIONS; OUTFLOW LAYER; INTENSIFICATION; CONVECTION; INTENSITY; EVOLUTION; SYSTEM; MODEL AB The distribution and intensity of tropical cyclone precipitation has been known to have a large influence on the intensification and maintenance of the system. Therefore, monitoring the tropical cyclone convective rainband cycle and the large-scale environmental forcing mechanisms that initiate and maintain the tropical cyclone convective rainbands may aid in better understanding and predicting tropical cyclone intensification. To demonstrate how the evolution of the tropical cyclone precipitation can be monitored, the frequent Special Sensor Microwave/Imager (SSM/I) observations of precipitation from Typhoon Bobbie (June 1992) were used to help better delineate Bobbie's convective rainband cycle. Bobbie's SSM/I-observed convective rainband cycle was then related to the tropical cyclone's intensity change. To obtain a better understanding of how Bobbie's convective rainbands were initiated and maintained, total precipitable water (TPW) over the ocean regions, mean monthly sea surface temperatures (SSTs), and analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) model were examined. The SSM/I TPW helped to substantiate the ECMWF-analyzed regions of dry and moist air that were interacting with the system's circulation, while the mean monthly SSTs were used to determine whether the western North Pacific, where Bobbie traversed, was warm enough to allow for sufficient energy flux to support convection. The ECMWF model was employed to examine the environmental forcing mechanisms that may have initiated and maintained Bobbie's convective rainbands, such as mean vertical wind shear, environmental tropospheric water vapor nux and divergence, and upper-tropospheric eddy relative angular momentum flux convergence. Results from the analyses of Typhoon Bobbie suggested the following: 1) The SSM/I observations bf Bobbie's precipitation were able to detect and monitor convective rainband cycles that were similar to those observed with land-based and aircraft radar, in situ measurements, and SSM/I observations of western North Atlantic tropical cyclones. 2) The evolution of Bobbie's intensity coincided with the SSM/I-observed convective rainband cycles. 3) The SSM/I observations of the TPW over nonraining ocean regions were able to substantiate the ECMWF-analyzed moist and dry regions that were interacting with Bobbie's circulation. 4) In regions of warm SSTs and weak vertical wind shear, the enhancement of the precipitation in Bobbie's inner-core convective rainbands coincided with the inward convergence of upper-tropospheric eddy relative angular momentum, while the initialization of Bobbie's outer-core convective rainbands appeared to coincide with the large horizontal convergence of moisture, 5) The dissipation of rain in the inner-core convective rainbands appeared to be associated with inward propagation of newly formed outer convective rainbands, strong vertical wind shear(above 10 m s(-1)), and cool SSTs (below 26 degrees C). C1 SCI SYST & APPLICAT INC,LANHAM,MD. RP RODGERS, EB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MESOSCALE DYNAM & PRECIPITAT BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 39 TC 6 Z9 9 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 NOV PY 1995 VL 34 IS 11 BP 2513 EP 2532 DI 10.1175/1520-0450(1995)034<2513:EIOTBP>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TC123 UT WOS:A1995TC12300016 ER PT J AU SICONOLFI, SF GRETEBECK, RJ WONG, WW AF SICONOLFI, SF GRETEBECK, RJ WONG, WW TI ASSESSING TOTAL-BODY PROTEIN, MINERAL, AND BONE-MINERAL CONTENT FROM TOTAL-BODY WATER AND BODY DENSITY SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Note DE BODY COMPOSITION; UNDERWATER WEIGHING; MULTICOMPONENT MODELS ID VOLUME; MEN AB We hypothesized that investigators could assess bone mineral content (BMC), total body mineral (M), and protein (P) from body water (W) and density (D-B) based on the theory of W. E. Siri (Advances in. Biological and Medical Physics, 1956, p. 239-280 and Techniques for Measuring Body Composition, 1961, p. 223-224) for body composition analysis. Siri used one or more of the body components and the densities of the body, fat (F), W, M, and P to estimate one of the remaining fractional masses. We compared M, BMC, P, F, and fat-free mass (FFM) in 31 subjects (15 women and 16 men) computed from measurements of W and D-B with [4-compartment (4C) model] and without [3-compartment (3C) model] BMC (from dual X-ray absorptiometry). 4C model P was calculated by difference (P = FFM - W - M). Mean difference (P > 0.05) ranged from 0.1 to 0.8%. Correlations [+/-standard error of estimate (%)] between 4C and 3C model values were significant (r = 0.907 +/- 8.8, 0.907 +/- 8.7, 0.969 +/- 6.6, 0.998 +/- 2.0, and 0.999 +/- 0.7% for M, BMC, P, F, and FFM, respectively). We concluded that investigators can assess M, BMC, and P from W and D-B. C1 UNIV HOUSTON,SPACE RES ASSOC,HOUSTON,TX 77058. BAYLOR COLL MED,DEPT PEDIAT,CHILDRENS NUTR RES CTR,USDA ARS,STABLE ISOTOPE PROGRAM,HOUSTON,TX 77030. RP SICONOLFI, SF (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST SD5,EXERCISE PHYSIOL LAB,HOUSTON,TX 77058, USA. NR 20 TC 13 Z9 13 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD NOV PY 1995 VL 79 IS 5 BP 1837 EP 1843 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA TD929 UT WOS:A1995TD92900056 PM 8594047 ER PT J AU KENT, GS WILLIAMS, ER WANG, PH MCCORMICK, MP SKEENS, KM AF KENT, GS WILLIAMS, ER WANG, PH MCCORMICK, MP SKEENS, KM TI SURFACE-TEMPERATURE RELATED VARIATIONS IN TROPICAL CIRRUS CLOUD AS MEASURED BY SAGE-II SO JOURNAL OF CLIMATE LA English DT Article ID WARM-POOL; STRATOSPHERIC AEROSOL; OCCULTATION DATA; DEEP CONVECTION; SATELLITE; DISTRIBUTIONS; CLIMATE; CYCLE; OCEAN; ATMOSPHERE AB Data from the Stratospheric Aerosol and Gas Experiment II (SAGE II) solar occultation satellite instrument have been used to study the properties of tropical cloud over the altitude range 10.5-18.5 km. By virtue of its limb viewing measurement geometry, SAGE II has good vertical resolution and sensitivity to subvisual cloud not detectable by most other satellite instruments. The geographical distribution and temporal variation of the cloud occurrence have been examined over all longitudes on timescales from less than 1 day to that of the El Nino-Southern Oscillation (ENSO) cycle. Significant variations in cloud occurrence are found on each of these scales and have been compared with the underlying surface temperature changes. Maximum cloud occurs over the warm pool region of the Pacific Ocean, with secondary maxima over the South American and Central African landmasses, where the percentage of cloud occurrence in the upper troposphere can exceed 75%. Cloud occurrence at all altitudes within the Tropics, over both land and ocean, increases with the underlying surface temperature at a rate of approximately 13%degrees C-1. Extrapolated threshold temperatures for the formation of cloud are about 5 degrees C lower than those found from nadir viewing observations. This difference is believed to be a consequence of the averaging process and the inclusion of outliers in the dataset. ENSO cycle changes in cloud occurrence are observed, not only over the Tropics but also over the subtropics, indicating a difference in the meridional Hadley circulation between ENSO warm and cold years. Sunrise-sunset cloud differences indicate that large-scale variations, whose form resembles that of the Hadley and Walker circulations, are present, with a timescale of 1 day or less. The global distribution of upper-tropospheric ice and its positive correlation with surface temperature C1 MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA. NASA,LANGLEY RES CTR,AEROSOL RES BRANCH,HAMPTON,VA 23665. RP KENT, GS (reprint author), SCI & TECHNOL CORP,101 RES DR,HAMPTON,VA 23666, USA. NR 87 TC 40 Z9 41 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1995 VL 8 IS 11 BP 2577 EP 2594 DI 10.1175/1520-0442(1995)008<2577:STRVIT>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TG724 UT WOS:A1995TG72400001 ER PT J AU KYLE, HL WEISS, M ARDANUY, P AF KYLE, HL WEISS, M ARDANUY, P TI CLOUD, SURFACE-TEMPERATURE, AND OUTGOING LONGWAVE RADIATION FOR THE PERIOD FROM 1979 TO 1990 SO JOURNAL OF CLIMATE LA English DT Article ID BUDGET ERB EXPERIMENT; DATA SET; EL-NINO; EARTH AB Quasi-biennial global, midlatitude, and tropical oscillations were observed using top-of-the-atmosphere outgoing longwave radiation (OLR), surface air temperature (SAT), and cloud amount for the period from 1979 to 1989. The in-phase quasi-biennial variations of OLR and SAT were strongest in the Tropics. Two prominent peaks in these two data fields were observed after the end of the main phases of the 1982-83 and 1986-87 Fl Nino-Southern Oscillation (ENSO) events, which were also accompanied by a decrease in the mean tropical cloud cover. The quasi-biennial signal was less noticeable in the midlatitudes during the two ENSO events but was strong during two non-ENSO peaks occurring in 1980-81 and 1989-90. In this study, the authors used two SAT datasets comprised of departures estimated from a specific base period, where the record of these two datasets predates the start of this century. The OLR dataset was obtained by concatenating Nimbus-7 (1979-87) and Earth Radiation Budget Satellite (ERBS) (1985-89) measurements. The cloud dataset was generated by concatenating Nimbus-7 (1979-84) estimates with those from the International Satellite Cloud Climatology Program (ISCCP) (1983-90). In the concatenation procedure, adjustments were made for previously identified, long-term nonphysical data trends in the Nimbus-7 datasets; some additional experiments were made in which detrending was applied to all the datasets. As a consequence, decade-long trends were not considered. In the detrended datasets, OLR and SAT were strongly positively correlated with explained variances of 74.5% or larger in the Tropics and midlatitudes and of 96.4% on a global scale. OLR and cloud were negatively correlated; however the results were less definitive with explained variances of 86.7% and 79.4%, respectively, for the globe and midlatitudes but only 17.4% in the Tropics. These observations imply a clear identification of a quasibiennial signal and relationship between OLR and SAT, but the results are less certain when OLR is compared to cloud cover. C1 RES & DATA SYST CORP,GREENBELT,MD. RP KYLE, HL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL STOP 9023,GREENBELT,MD 20771, USA. NR 28 TC 8 Z9 8 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD NOV PY 1995 VL 8 IS 11 BP 2644 EP 2658 DI 10.1175/1520-0442(1995)008<2644:CSTAOL>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TG724 UT WOS:A1995TG72400005 ER PT J AU LI, MR NADARAJAH, A PUSEY, ML AF LI, MR NADARAJAH, A PUSEY, ML TI MODELING THE GROWTH-RATES OF TETRAGONAL LYSOZYME CRYSTALS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID KINETICS; MICROSCOPY AB Although the faceted growth of tetragonal lysozyme crystals is known to occur by 2D nucleation and dislocation-led growth, the measured growth rates do not follow model predictions based on these mechanisms. One possible reason for this deviation is that these models ignore the highly aggregated state of lysozyme in supersaturated solutions. In this study a growth mechanism for tetragonal lysozyme crystals involving aggregation reactions leading to the formation of the growth unit, mass transport of the growth unit to the crystal interface and faceted crystal growth by growth unit addition, is proposed. The distribution of aggregates in lysozyme nutrient solutions were determined from the equilibrium aggregation reactions and comparisons were made with growth rates calculated from the model based on the proposed mechanism and the measured growth rate data. The results indicated than an octamer corresponding to the tetragonal crystal unit cell was the most likely growth unit for the process. Remarkably good fits were obtained with this model to the measured growth rate data for three sets of pH and salt concentrations, suggesting the validity of the proposed mechanism. The values of the kinetic coefficient for the step velocity was in the range for small molecule crystal growth and the heats of reaction compared well with that obtained from lysozyme solubility data. The results presented here suggest that the inorganic and protein crystal growth processes are quite similar in many ways. Lysozyme crystal growth differs primarily due to growth by an aggregate growth unit and in the effect of nutrient solution conditions on the protein aggregation process. C1 UNIV ALABAMA,DEPT CHEM ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH ES76,HUNTSVILLE,AL 35812. NR 25 TC 38 Z9 38 U1 2 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 1995 VL 156 IS 1-2 BP 121 EP 132 DI 10.1016/0022-0248(95)00262-6 PG 12 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA TF387 UT WOS:A1995TF38700018 ER PT J AU MAHONEY, JB MCGHEE, JA MCNULTY, JK AF MAHONEY, JB MCGHEE, JA MCNULTY, JK TI COMPARISON OF SUITABILITY OF GREAT-BAY, NEW-JERSEY, AND PARSONAGE-CREEK, NEW-YORK, FOR ALEXANDRIUM-TAMARENSE SO JOURNAL OF EUKARYOTIC MICROBIOLOGY LA English DT Article DE ALGAL BIOASSAY; HARMFUL ALGAL BLOOMS ID GONYAULAX-TAMARENSIS; IRON; DINOFLAGELLATE; TOXICITY; BLOOMS; WATERS AB Alexandrium tamarense (Lebour) Balech(=Gonyaulax tamarensis Lebour) has been widely distributed and occasionally abundant in coastal waters of Long Island, New York in recent years. However, the distribution on the New Jersey coast has been sparse and this fact cannot be explained by this dinoflagellate's ability to migrate, or by its nutritional and physiological characteristics, or by the region's general suitability for phytoplankton. Therefore, the possibility that New Jersey coastal waters might be chemically exclusionary for A. tamarense seemed worth exploring. In a limited approach, we tested for water quality detrimental to the species in one New Jersey site (Great Bay) with a series of annual assays. Parsonage Creek, Long Island, New York, was assayed for comparison; this creek is assumed to have had at least marginal suitablity for A. tamarense, based on its reported long-term presence. Results provide tentative support for our working hypothesis, i.e. Great Bay chemical water quality is generally unfavorable for A. tamarense. Inhibition of A. tamarense growth, or culture decline, occurred in both assay series, but was substantially greater in Great Bay water. Inimical water quality was the most important factor distinguishing the two sites. Chelation with EDTA had greatest overall benefit in Great Bay assays, suggesting that lower availability of a natural chelator in the bay could be a secondary factor. Assay metal response is problematic, but we believe it permits speculation that essential metals could be partially Limiting to A. tamarense in Great Bay, but would not be a critical regulator. RP MAHONEY, JB (reprint author), US DEPT COMMERCE, NOAA, NATL MARINE FISHERIES SERV, NE FISHERIES CTR, JAMES J HOWARD MARINE SCI LAB, HIGHLANDS, NJ 07732 USA. NR 43 TC 1 Z9 1 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1066-5234 J9 J EUKARYOT MICROBIOL JI J. Eukaryot. Microbiol. PD NOV-DEC PY 1995 VL 42 IS 6 BP 715 EP 721 DI 10.1111/j.1550-7408.1995.tb01622.x PG 7 WC Microbiology SC Microbiology GA TF125 UT WOS:A1995TF12500012 ER PT J AU SAITO, A IYEMORI, T SUGIURA, M MAYNARD, NC AGGSON, TL BRACE, LH TAKEDA, M YAMAMOTO, M AF SAITO, A IYEMORI, T SUGIURA, M MAYNARD, NC AGGSON, TL BRACE, LH TAKEDA, M YAMAMOTO, M TI CONJUGATE OCCURRENCE OF THE ELECTRIC-FIELD FLUCTUATIONS IN THE NIGHTTIME MIDLATITUDE IONOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IRREGULARITIES; CURRENTS AB The DE 2 satellite observed electric field fluctuations on the topside of the nighttime midlatitude ionosphere. They extended several hundred kilometers in the latitudinal direction with wavelengths of several tens of kilometers, and their amplitudes were a few millivolts per meter, Such fluctuations were often observed at magnetically conjugate points in the northern and southern hemispheres, These electric field fluctuations are perpendicular to the geomagnetic field, They are not accompanied by any significant plasma depletion or electron temperature variations. Magnetic field fluctuations are sometimes observed simultaneously with electric field fluctuations, We interpret that these fluctuations are caused by field-aligned currents which flow from the ionosphere in one hemisphere to the conjugate point in the other hemisphere, The power spectrum of these midlatitude electric field fluctuations follows a power law of the form Power proportional to f(-n), with the spectral index n of 3.5 to 4.5, which is steeper than that of the electric; field fluctuations in the high-latitude ionosphere or in the equatorial ionosphere. This phenomenon may be related to other ionospheric phenomena, for example, the F region field-aligned irregularities or spread-F, observed by ground-based methods such as the MU radar, but the relationship is not clear. C1 MISSION RES CORP,NASHUA,NH 03062. TOKAI UNIV,INST RES & DEV,TOKYO 151,JAPAN. KYOTO UNIV,CTR RADIO ATMOSPHER SCI,UJI,KYOTO 611,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. RP SAITO, A (reprint author), KYOTO UNIV,FAC SCI,KYOTO 60601,JAPAN. NR 24 TC 54 Z9 54 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1995 VL 100 IS A11 BP 21439 EP 21451 DI 10.1029/95JA01505 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400014 ER PT J AU TSURUTANI, BT GONZALEZ, WD GONZALEZ, ALC TANG, F ARBALLO, JK OKADA, M AF TSURUTANI, BT GONZALEZ, WD GONZALEZ, ALC TANG, F ARBALLO, JK OKADA, M TI INTERPLANETARY ORIGIN OF GEOMAGNETIC-ACTIVITY IN THE DECLINING PHASE OF THE SOLAR-CYCLE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC STORMS 1978-1979; CORONAL MASS EJECTIONS; SPEED PLASMA STREAMS; SEMIANNUAL VARIATION; EARTHS MAGNETOSPHERE; COROTATING SHOCKS; SUBSTORM ACTIVITY; ALFVEN WAVES; BZ EVENTS; 1 AU AB Interplanetary magnetic field (IMF) and plasma data are compared with ground-based geomagnetic Dst and AE indices to determine the causes of magnetic storms, substorms, and quiet during the descending phase of the solar cycle. In this paper we focus primarily on 1974 when the AE index is anomalously high (<(AE)over bar> = 283 nT). This year is characterized by the presence of two long-lasting corotating streams associated with coronal holes. The corotating streams interact with the upstream low-velocity (300-350 km s(-1)), high-density heliospheric current sheet (HCS) plasma sheet, which leads to field compression and similar to 15- to 25-nT hourly average values. Although the B-z component in this corotating interaction region (CIR) is often < -10 nT, typically the field directionality is highly variable, and large southward components have durations less than 3 hours. Thus the corotating stream/HCS plasma sheet interaction region can cause recurring moderate (-100 nT less than or equal to Dst less than or equal to -50 nT) to weak (-50 nT less than or equal to Dst less than or equal to -25 nT) storms, and sometimes no significant ring current activity at all (Dst > -25 nT). Storms of major (Dst less than or equal to -100 nT) intensities were not associated with CIRs. Solar wind energy is transferred to the magnetosphere via magnetic reconnection during the weak and moderate storms. Because the B-z component in the interaction region is typically highly fluctuating, the corresponding storm main phase profile is highly irregular. Reverse shocks are sometimes present at the sunward edge of the CIR. Because these events cause sharp decreases in field magnitude, they can be responsible for storm recovery phase onsets. The initial phases of these corotating stream-related storms are caused by the increased ram pressure associated with the HCS plasma sheet and the further density enhancement from the stream-stream compression. Although the solar wind speed is generally low in this region of space, the densities can be well over an order of magnitude higher than the average value, leading to significant positive Dst values. Since there are typically no forward shocks at 1 AU associated with the stream-stream interactions, the initial phases have gradual onsets. The most dramatic geomagnetic response to the corotating streams are chains of consecutive substorms caused by the southward components of large-amplitude Alfven waves within the body of the corotating streams. This auroral activity has been previously named high-intensity long-duration continuous AE activity (HILDCAAs). The substorm activity is generally most intense near the peak speed of the stream where the Alfven wave amplitudes are greatest, and it decreases with decreasing wave amplitudes and stream speed. Each of the 27-day recurring HILDCAA events can last 10 days or more, and the presence of two events per solar rotation is the cause of the exceptionally high AE average for 1974 (higher than 1979). HILDCAAs often occur during the recovery phase of magnetic storms, and the fresh (and sporadic) injection of substorm energy leads to unusually long storm recovery phases as noted in Dsr. In the far trailing edge of the corotating stream, the IMF amplitudes become low, <3 nT, and there is an absence of large-amplitude fluctuations (Alfven waves). This is related to and causes geomagnetic quiet. There were three major (Dst less than or equal to -100 nT) storms that occurred in 1974. Each was caused by a nonrecurring moderate speed stream led by a fast forward shock. The mechanisms for generating the intense interplanetary B-s which were responsible for the subsequent intense magnetic storms was shock compression of preexisting southwardly directed B-z (B-s) for the two largest events and a magnetic cloud for the third (weakest) event. Each of the three streams occurred near a HCS crossing with no obvious solar optical or X ray signatures. It is speculated that these events may be associated with flux openings associated with coronal hole expansions. In conclusion, we present a model of geomagnetic activity during the descending phase of the solar cycle. It incorporates storm initial phases, main phases, HILDCAAs, and geomagnetic quiet. It uses some of the recent Ulysses results. We feel that this model is sufficiently developed that it may be used for predictions, and we encourage testing during the current phase of the solar cycle. C1 INST NACL PESQUISAS ESPACIAIS,S JOSE CAMPOS,SP,BRAZIL. NATL INST POLAR RES,TOKYO 173,JAPAN. CALTECH,PASADENA,CA 91125. RP TSURUTANI, BT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 169-506,PASADENA,CA 91109, USA. NR 58 TC 217 Z9 221 U1 2 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1995 VL 100 IS A11 BP 21717 EP 21733 DI 10.1029/95JA01476 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400035 ER PT J AU FARRUGIA, CJ SANDHOLT, PE COWLEY, SWH SOUTHWOOD, DJ EGELAND, A STAUNING, P LEPPING, RP LAZARUS, AJ HANSEN, T FRIISCHRISTENSEN, E AF FARRUGIA, CJ SANDHOLT, PE COWLEY, SWH SOUTHWOOD, DJ EGELAND, A STAUNING, P LEPPING, RP LAZARUS, AJ HANSEN, T FRIISCHRISTENSEN, E TI RECONNECTION-ASSOCIATED AURORAL ACTIVITY STIMULATED BY 2 TYPES OF UPSTREAM DYNAMIC PRESSURE VARIATIONS - INTERPLANETARY MAGNETIC-FIELD B-Z-SIMILAR-TO-0, B-Y-MUCH-LESS-THAN-0 CASE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CONVECTION TWIN-VORTICES; FLUX-TRANSFER EVENTS; SOLAR-WIND; MAGNETOSPHERIC RESPONSE; IONOSPHERIC CONVECTION; EARTHS MAGNETOSPHERE; DAYSIDE AURORA; Y-COMPONENT; BOW SHOCK; MAGNETOPAUSE AB We present observations of transient auroral activity in the 1300 - 1600 MLT range at geomagnetic latitudes of 76 degrees and interpret them in terms of modulations in the reconnection rate at the magnetopause which are, in turn, stimulated by the arrival at Earth of upstream dynamic pressure pulses. The period studied is 1000 - 1200 UT on December 17, 1992. The interplanetary magnetic field (IMF), monitored by IMP 8, was aligned in a Parker spiral direction with a strong westward component (IMF B-y much less than 0) and a small or zero north-south component. The upstream dynamic pressure variations were of two types, reflecting two distinct origins: the unperturbed solar wind and the bow shock. The underlying reconnection interpretation, with the necessary magnetic shear across the magnetopause being provided by the strong westward component of the IMF, is substantiated by a study of ionospheric flows. A twin-cell pattern of standard polarity is evident in which strong asymmetries about noon are seen, as expected from the predominantly westward pointing IMF. Flow perturbations are superimposed on this general pattern. The auroral observations consist of a latitudinally narrow zone of persistent auroral emission, at the poleward edge of which auroral forms are seen moving eastward (tailward) at speeds of 1-2 km s(-1). This intermittent activity, which is often detached from the persistent aurora, has a red line intensity (Line of sight) > 1.5 kR, a broad intensity-versus-zenith angle profiles, and a weak green line intensity (< 1 kR). The brightenings are also associated with the activation of discrete forms at the cleft equatorward boundary. A comparison with results obtained from mapping the magnetopause and its boundary layers to the ionosphere by means of particle precipitation characteristics indicates that the persistent aurora consists mainly of low- latitude boundary layer precipitation on closed field lines. The transients poleward of the persistent aurora are coming from the cusp or near cusp. We find that the auroral transients are correlated with a sequence of magnetic impulses of 50 nT or less amplitude seen at ground stations around the optical site. We also find that there is a further, good correlation between the transients and the arrival at Earth of rapid and large (> 20 % increase relative to background levels) upstream dynamic pressure pulses. Smaller dynamic pressure changes do not seem to affect the aurora noticeably. Our interpretation is in line with some recent studies, namely, that an increase of dynamic pressure on the magnetopause enhances the reconnection rate there. Clearly, theoretical work is needed to understand this important, if indirect, effect of dynamic pressure on the magnetosphere. C1 UNIV OSLO,DEPT PHYS,N-0316 OSLO,NORWAY. UNIV MALTA,DEPT MATH SCI & TECH EDUC,MSIDA,MALTA. DANISH INST FUNDAMENTAL METROL,DK-2100 COPENHAGEN,DENMARK. UNIV TROMSO,AURORAL OBSERV,N-9001 TROMSO,NORWAY. MIT,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP FARRUGIA, CJ (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,PRINCE CONSORT RD,LONDON SW7 2BZ,ENGLAND. NR 52 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1995 VL 100 IS A11 BP 21753 EP 21772 DI 10.1029/95JA01082 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400038 ER PT J AU LOCKWOOD, M DAVIS, CJ SMITH, MF ONSAGER, TG DENIG, WF AF LOCKWOOD, M DAVIS, CJ SMITH, MF ONSAGER, TG DENIG, WF TI LOCATION AND CHARACTERISTICS OF THE RECONNECTION X-LINE DEDUCED FROM LOW-ALTITUDE SATELLITE AND GROUND-BASED OBSERVATIONS .2. DEFENSE METEOROLOGICAL SATELLITE PROGRAM AND EUROPEAN INCOHERENT-SCATTER DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; IONOSPHERIC SIGNATURES; DAYSIDE MAGNETOPAUSE; MAGNETOSPHERIC CUSP; ION; PLASMA; PRECIPITATION; CONVECTION; EXCITATION; DENSITY AB We present an analysis of a cusp ion step, observed by the Defense Meteorological Satellite Program (DMSP) F10 spacecraft, between two poleward moving events of enhanced ionospheric electron temperature, observed by the European Incoherent Scatter (EISCAT) radar. From the ions detected by the satellite, the variation of the reconnection rate is computed for assumed distances along the open-closed field line separatrix from the satellite to the X line, d(0). Comparison with the onset times of the associated ionospheric events allows this distance to be estimated, but with an uncertainty due to the determination of the low-energy cutoff of the ion velocity distribution function, f(nu). Nevertheless, the reconnection site is shown to be on the dayside magnetopause, consistent with the reconnection model of the cusp during southward interplanetary magnetic field (IMF). Analysis of the time series of distribution function at constant energies, f(t(s)), shows that the best estimate of the distance d(0) is 14.5 +/- 2 R(E). This is consistent with various magnetopause observations of the signatures of reconnection for southward IMF. The ion precipitation is used to reconstruct the field-parallel part of the Cowley D ion distribution function injected into the open low-latitude boundary layer in the vicinity of the X line. From this reconstruction, the field-aligned component of the magnetosheath flow is found to be only -55 +/- 65 km s(-1) near the X line, which means either that the reconnection X line is near the stagnation region at the nose of the magnetosphere, or that it is closely aligned with the magnetosheath flow streamline which is orthogonal to the magnetosheath field, or both. In addition, the sheath Alfven speed at the X line is found to be 220 +/- 45 km s(-1), and the speed with which newly opened field lines are ejected from the X line is 165 +/- 30 km s(-1). We show that the inferred magnetic field, plasma density, and temperature of the sheath near the X line are consistent with a near-subsolar reconnection site and confirm that the magnetosheath field makes a large angle (>58 degrees) with the X line. C1 PHILLIPS LAB,GPSG,BEDFORD,MA 01731. UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. UNIV NEW HAMPSHIRE,DEPT PHYS,DURHAM,NH 03824. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP LOCKWOOD, M (reprint author), RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND. RI Lockwood, Mike/G-1030-2011; Scott, Christopher/H-8664-2012 OI Lockwood, Mike/0000-0002-7397-2172; Scott, Christopher/0000-0001-6411-5649 NR 42 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 NOV 1 PY 1995 VL 100 IS A11 BP 21803 EP 21813 DI 10.1029/95JA01339 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400042 ER PT J AU HESSE, M WINSKE, D KUZNETSOVA, MM AF HESSE, M WINSKE, D KUZNETSOVA, MM TI HYBRID MODELING OF COLLISIONLESS RECONNECTION IN 2-DIMENSIONAL CURRENT SHEETS - SIMULATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC RECONNECTION; TEARING MODE; NEUTRAL SHEET; INSTABILITY; PLASMAS; STABILITY; LINE AB The stability of thin current sheets, such as commonly occur in space plasmas, is investigated in the presence of a magnetic normal component. The investigation is based on hybrid simulations using a suitably adapted electron pressure model. In order to properly represent the effects of the electron cyclotron motion in the magnetic normal component, we include the cyclotron part of the electron pressure evolution in an implicit manner. The results of a number of these simulations are presented with emphasis on a comparison with the linear analytical theory (Kuznetsova et al., this issue), and on the nonlinear evolution of the tearing instability. We find, in agreement with linear theory, a transition to stability for electron mass below a certain threshold, which depends on the initial configuration. The results suggest that the onset of fast substorm evolution in the magnetotail may be a two-step process, where another presently not included mechanism leads to the destabilization of the tearing instability followed by the nonlinear growth of a large scale instability. C1 LOS ALAMOS NATL LAB,DIV APPL THEORET PHYS,LOS ALAMOS,NM 87545. RP HESSE, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 47 TC 36 Z9 36 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 NOV 1 PY 1995 VL 100 IS A11 BP 21815 EP 21825 DI 10.1029/95JA01559 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400043 ER PT J AU KUZNETSOVA, MM HESSE, M WINSKE, D AF KUZNETSOVA, MM HESSE, M WINSKE, D TI HYBRID MODELING OF THE TEARING INSTABILITY IN COLLISIONLESS 2-DIMENSIONAL CURRENT SHEETS - LINEAR-THEORY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NEUTRAL SHEET; MAGNETIC RECONNECTION; MAGNETOTAIL PLASMAS; PARTICLE ORBITS; SIMULATIONS; EQUILIBRIA; STABILITY AB The linear stability of thin magnetic field reversals is analyzed using a hybrid approach. The ion resonant response to electromagnetic perturbations is calculated from the kinetic Vlasov equation, whereas the electron response is derived from fluid equations using a suitably adapted electron pressure model. Effects of off-diagonal components of the perturbed pressure tensor on the compressional stabilization are taken into account. The results are presented with emphasis on a comparison with the linear fully kinetic theory and hybrid simulations of the same model (Hesse et al., this issue). We find the stability of perturbations with gradient scales greater than the maximum electron Larmor radius. The transition to instability with the increase of the electron mass is illustrated. C1 LOS ALAMOS NATL LAB,DIV APPL THEORET PHYS,LOS ALAMOS,NM 87545. RP KUZNETSOVA, MM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 40 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 NOV 1 PY 1995 VL 100 IS A11 BP 21827 EP 21833 DI 10.1029/95JA01560 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400044 ER PT J AU GUITER, SM MOORE, TE KHAZANOV, GV AF GUITER, SM MOORE, TE KHAZANOV, GV TI MODELING OF O+ IONS IN THE PLASMASPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID F-REGION; IONOSPHERE; TRANSPORT; FLOWS; TEMPERATURE; DENSITY; ENHANCEMENTS AB Heavy ion (O+, O++, and N+) density enhancements in the outer plasmasphere have been observed using the retarding ion mass spectrometer instrument on the DE 1 satellite. These are seen at L shells from 2 to 5, with most occurrences in the L = 3 to 4 region; the maximum L shell at which these enhancements occur varies inversely with Dst. It is also known that enhancements of O+ and O++ overlie ionospheric electron temperature peaks. It is thought that these enhancements are related to heating of plasmaspheric particles through interactions with ring current ions, This was investigated using a time-dependent one-stream hydrodynamic model for plasmaspheric flows, in which the model flux tube is connected to the ionosphere. The model simultaneously solves the coupled continuity, momentum, and energy equations of a two-ion (H+ and O+) quasi-neutral, currentless plasma, This model is fully interhemispheric and diffusive equilibrium is not assumed; it includes a corotating tilted dipole magnetic field and neutral winds. First, diurnally reproducible results were found assuming only photoelectron heating of thermal electrons. For this case the modeled equatorial O+ density was below 1 cm(-3) throughout the day. The O+ results also show significant diurnal variability, with standing shocks developing when production stops and O+ flows downward under the influence of gravity. Numerical tests were done with different levels of electron heating in the plasmasphere; these show that the equatorial O+ density is highly dependent on the assumed electron heating rates. Over the range of integrated plasmaspheric electron heating (along the flux tube) from 8.7 to 280 x 10(9) eV/s, the equatorial O+ density goes like the heating raised to the power 2.3. RP GUITER, SM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 32 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1995 VL 100 IS A11 BP 21921 EP 21928 DI 10.1029/95JA02224 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400052 ER PT J AU KLIMAS, AJ BAKER, DN VASSILIADIS, D ROBERTS, DA AF KLIMAS, AJ BAKER, DN VASSILIADIS, D ROBERTS, DA TI SUBSTORM RECURRENCE DURING STEADY AND VARIABLE SOLAR-WIND DRIVING - EVIDENCE FOR A NORMAL-MODE IN THE UNLOADING DYNAMICS OF THE MAGNETOSPHERE - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID GEOMAGNETIC-ACTIVITY C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. UNIV SPACE RES ASSOCIATES,SEABROOK,MD. RP KLIMAS, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 22 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD NOV 1 PY 1995 VL 100 IS A11 BP 22003 EP 22005 DI 10.1029/95JA01474 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD904 UT WOS:A1995TD90400061 ER PT J AU ZELENKA, RE YEE, Z ZIRKLER, A AF ZELENKA, RE YEE, Z ZIRKLER, A TI FLIGHT TEST OF RADAR ALTIMETER ENHANCEMENT FOR TERRAIN-REFERENCED GUIDANCE (VOL 18, PG 706, 1995) SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Correction, Addition C1 USA,COMMAND CONTROL & SYST INTEGRAT DIRECTORATE,FT MONMOUTH,NJ 07703. VITRON INC,EATONTOWN,NJ 07724. RP ZELENKA, RE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 1995 VL 18 IS 6 BP 1470 EP 1470 DI 10.2514/3.56692 PG 1 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA TE758 UT WOS:A1995TE75800040 ER PT J AU Geng, ZJ Pan, GG Haynes, LS Wada, BK Garba, JA AF Geng, ZJ Pan, GG Haynes, LS Wada, BK Garba, JA TI An intelligent control system for multiple degree-of-freedom vibration isolation SO JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES LA English DT Article AB Multiple degree-of-freedom (DOF) vibration isolation and suppression capabilities are essential for precision control of a wide range of space-borne structures as well as earth-based systems. This paper presents the system design and implementation, control algorithms, parallel computing architecture, and real-time experiments of a six DOF Hexapod Active Vibration Isolation (HAVI) system developed at Intelligent Automation, Inc. The system design of the HAVI is based on the hexapod (Stewart Platform) concept. A novel geometric arrangement of a hexapod, called the ''Cubic Configuration'' is used. Magnetostrictive material Terfenol-D actuators are employed. A two-layer control system architecture incorporating local force feedback control and a robust adaptive filter control for active vibration isolation are employed. A high performance parallel computation engine MDSP-100 with multiple DSP processors and maximum 566 MFLOPs throughput is also developed for the HAVI applications and was used to implement proposed control algorithms. The unique architecture and functionality of the MDSP-100 facilitate the data acquisition and control law computation operations in a parallel computing fashion. Mechanical hardware for the HAVI system has been fabricated and tested. The six channel simultaneous active vibration control experiments were performed to demonstrate HAVI system's 6 DOF vibration isolation and suppression capabilities. A wide band (below 250 Hz) active vibration attenuation for all six channels was obtained in the real-time experiments. C1 INTELLIGENT AUTOMAT INC,ROCKVILLE,MD 20850. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Geng, ZJ (reprint author), ROBOTRONICS INC,4950 CLOISTER DR,ROCKVILLE,MD 20852, USA. NR 13 TC 11 Z9 12 U1 0 U2 5 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 1045-389X J9 J INTEL MAT SYST STR JI J. Intell. Mater. Syst. Struct. PD NOV PY 1995 VL 6 IS 6 BP 787 EP 800 DI 10.1177/1045389X9500600607 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA TQ347 UT WOS:A1995TQ34700007 ER PT J AU RAGEN, TJ ANTONELIS, GA KIYOTA, M AF RAGEN, TJ ANTONELIS, GA KIYOTA, M TI EARLY MIGRATION OF NORTHERN FUR-SEAL PUPS FROM ST-PAUL ISLAND, ALASKA SO JOURNAL OF MAMMALOGY LA English DT Article DE NORTHERN FUR SEAL; CALLORHINUS URSINUS; BERING SEA; ALASKA; MIGRATION; RADIOTELEMETRY ID CALLORHINUS-URSINUS AB The early migration of northern fur seal (Callorhinus ursinus) pups was investigated using very high-frequency (VHF) radiotelemetry. In 1989-1990, 184 pups were radiotagged and monitored to determine the date of their departure from St. Paul Island, Alaska. After their departure, 70 pups were located by receiver stations in the eastern Aleutian Islands and by aerial surveys. Mean (+/-1 SD) time of travel between St. Paul Island and the Aleutian passes was 11 +/- 6 days (n = 63), suggesting that, on average, pups progressed southward at the rate of ca. 36-40 km/day. Near the Aleutians, they were distributed throughout the study area from Unimak Pass to Samalga Pass, and Unimak Pass was not the main migratory route from the Bering Sea into the North Pacific Ocean. The pups remained dispersed as migration continued south of the Aleutian Islands. The migratory routes of northern fur seal pups in the Bering Sea and North Pacific Ocean have important implications for their pelagic ecology, including the type and availability of prey, oceanographic conditions encountered, population dynamics (e.g., survival and reproductive recruitment), and potential for interaction with human activities. C1 NATL MARINE FISHERIES SERV,NATL MARINE MAMMAL LAB,SEATTLE,WA 98115. NATL RES INST FAR SEAS FISHERIES,SHIMIZU,SHIZUOKA 424,JAPAN. RP RAGEN, TJ (reprint author), NATL MARINE FISHERIES SERV,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 21 TC 13 Z9 13 U1 2 U2 3 PU AMER SOC MAMMALOGISTS PI PROVO PA BRIGHAM YOUNG UNIV, DEPT OF ZOOLOGY, PROVO, UT 84602 SN 0022-2372 J9 J MAMMAL JI J. Mammal. PD NOV PY 1995 VL 76 IS 4 BP 1137 EP 1148 DI 10.2307/1382605 PG 12 WC Zoology SC Zoology GA TJ248 UT WOS:A1995TJ24800014 ER PT J AU WOLFENDEN, A RYNN, PJ SINGH, M AF WOLFENDEN, A RYNN, PJ SINGH, M TI MEASUREMENT OF ELASTIC AND ANELASTIC PROPERTIES OF REACTION-FORMED SILICON CARBIDE-BASED MATERIALS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB The dynamic Young's modulus and the strain amplitude dependence of damping, at room temperature as well as at elevated temperatures, were determined for reaction-formed SIC (RFSC) ceramics, and the results are compared with those for other SiC materials. The method used was the piezoelectric ultrasonic composite oscillator technique (PUCOT). Five specimens were studied: NC 203 (a commercially produced SIC by Norton, Co.); RFSC No. 1 and RFSC No. 2 (each containing residual Si); RFSC No. 3 and RFSC No. 4 (both containing residual Si and MoSi2). Metallographic observations showed that the microstructure of the RFSC is essentially isotropic with a uniform distribution of phases. The ''rule of mixtures'' calculations cannot be used to predict accurately the elastic modulus of the RFSC, but they can be used to predict the density to within 5%. It was determined that for the RFSC, the dynamic Young's modulus decreases as temperature increases, in a manner similar to that for other SiC materials. It was also found that the damping of the RFSC is generally independent of strain amplitude and is weakly affected by temperature. The activation energy was determined for the change in damping with change in temperature of RFSC No. 2 and RFSC No. 3. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WOLFENDEN, A (reprint author), TEXAS A&M UNIV,DEPT MECH ENGN,ADV MAT LAB,COLLEGE STN,TX 77843, USA. NR 19 TC 9 Z9 9 U1 1 U2 2 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD NOV 1 PY 1995 VL 30 IS 21 BP 5502 EP 5507 DI 10.1007/BF00351565 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA TD944 UT WOS:A1995TD94400025 ER PT J AU GHIRARDELLI, JE RIENECKER, MM ADAMEC, D AF GHIRARDELLI, JE RIENECKER, MM ADAMEC, D TI MERIDIONAL EKMAN HEAT-TRANSPORT - ESTIMATES FROM SATELLITE DATA SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID WORLD OCEAN; PACIFIC AB Analyses of satellite-derived SSM/I winds and AVHRR sea surface temperatures are used to compute weekly estimates of global meridional ocean Ekman heat transport for the 4-year period 1987 - 1991. The heat transport is consistently poleward throughout the year over the Atlantic and much of the Pacific between 30 degrees S and 30 degrees N and equatorward at higher latitudes. The zonally integrated Ekman heat transport in the Pacific was weak and equatorward at 10 degrees N in September 1989 and 1990, whereas in other years it is poleward throughout the year. In the Indian Ocean, equatorward heat transport was Strongest in Northern Hemisphere summer 1990. The weekly time series provides better temporal resolution than previous studies that at best used monthly averages. The higher-frequency variations are explored through rotated empirical orthogonal functions (REOFs) of nonseasonal heat transport anomalies. The REOFs show large-scale coherence across the tropical and subtropical Pacific and Indian Oceans. The first REOF has a strong spectral peak at periods of 50-60 days and is dominated by the variability in the Southern Hemisphere Indian Ocean. The second REOF is dominated by the variance in the Northern Hemisphere Indian Ocean and western tropical North Pacific. The first four REOFs, which explain 22.5% of the nonseasonal variance, have spectral peaks at periods consistent with the 30-60 day atmospheric Madden-Julian oscillation. These periods were not resolved in the monthly averaged data from GOADS. Singular spectrum analysis has been used as a filter to show the long timescale variations. The early phase of the 1988-89 La Nina has a strong influence on the heat transport, indicating enhanced poleward heat transport in the eastern Indian Ocean, tropical North Pacific, and tropical and subtropical South Pacific and enhanced equatorward heat transport in the midlatitude North Pacific and western tropical Indian Ocean. C1 NASA,GODDARD SPACE FLIGHT CTR,HYRODSPHER PROC LAB,OCEANS & ICE BRANCH,GREENBELT,MD 20771. UNIV MARYLAND,DEPT METEOROL,COLLEGE PK,MD 20742. NR 20 TC 5 Z9 5 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. Oceanog. PD NOV PY 1995 VL 25 IS 11 BP 2741 EP 2755 DI 10.1175/1520-0485(1995)025<2741:MEHTEF>2.0.CO;2 PN 1 PG 15 WC Oceanography SC Oceanography GA TH641 UT WOS:A1995TH64100016 ER PT J AU Garic, G AF Garic, G TI Cumulative detection probability as a basis for pressure vessel inspection intervals SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB This work discusses use of the cumulative flaw detection probability as the basis for establishing pressure vessel Inspection intervals. The method is based on the accumulated probability of detecting a flaw over several inspections. It explicitly incorporates a user decision as ro the acceptable level of failure risk. A four-step approach is outlined including fracture mechanics flaw growth calculations with probabilistic treatment of detection probability. It is concluded that (a) inspection intervals based on the cumulative probability of detection provide significant advantages over traditional cycle-based methods, (b) pressure vessel recertification inspections should rely on high percentage inspections conducted on a relatively infrequent basis. RP Garic, G (reprint author), NASA,JOHN C STENNIS SPACE CTR,LOCKHEED MARTIN STENNIS OPERAT,BAY ST LOUIS,MS 39529, USA. NR 20 TC 0 Z9 0 U1 1 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD NOV PY 1995 VL 117 IS 4 BP 399 EP 403 DI 10.1115/1.2842143 PG 5 WC Engineering, Mechanical SC Engineering GA TT214 UT WOS:A1995TT21400017 ER PT J AU BULZAN, DL AF BULZAN, DL TI STRUCTURE OF A SWIRL-STABILIZED COMBUSTING SPRAY SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID GAS; ATOMIZER; FLOWS AB Measurements of the structure of a swirl-stabilized, reacting spray are presented, The configuration consisted of a research air-assist atomizer located in the center surrounded by a coflowing airstream, Both the air-assist and coflow streams had swirl imparted to them in the same direction with 45-deg angle swirlers. The fuel and air entered the combustor at ambient temperature and the combustor was operated in an unconfined environment, The gas phase was seeded with aluminum-oxide particles in order to obtain velocity measurements. Mean velocity measurements for the gas phase are reported for both an isothermal, single-phase case without drops and a reacting spray case at axial distances from 2.5 to 50 mm downstream of the nozzle. Heptane fuel was used for all the experiments, Drop size and mean velocity and drop number flux are also reported for five axial distances downstream. The measurements were performed using a two-component phase/Doppler particle analyzer, Profiles across the entire flowfield where velocities were significant are presented, Mean gas-phase temperatures were also measured intrusively using a single pt/pt-13%rh thermocouple and are also reported at axial distances from 2.5 to 50 mm downstream of the nozzle. RP BULZAN, DL (reprint author), NASA,LEWIS RES CTR,AEROTHERMOCHEM BRANCH,MS 5-11,CLEVELAND,OH 44135, USA. NR 17 TC 8 Z9 8 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1995 VL 11 IS 6 BP 1093 EP 1102 DI 10.2514/3.23946 PG 10 WC Engineering, Aerospace SC Engineering GA TF316 UT WOS:A1995TF31600001 ER PT J AU BOYLE, RJ GIEL, PW AF BOYLE, RJ GIEL, PW TI 3-DIMENSIONAL NAVIER-STOKES HEAT-TRANSFER PREDICTIONS FOR TURBINE BLADE ROWS SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID CASCADE AB Results are shown for a three-dimensional Navier-Stokes analysis of both the flow and the surface heat transfer for four turbine blade rows. Heat transfer comparisons are made with the experimental shock-tunnel data of Dunn and Kim and with the data of Blair for the rotor of a large-scale rotating turbine, The analys is was done using the steady-state, three-dimensional, thin-layer Navier-Stokes code developed by Chima, which uses a multistage Runge-Kutta scheme with implicit residual smoothing. An algebraic mixing length turbulence model is used to calculate turbulent eddy viscosity. The variation in heat transfer due to variations in grid parameters is examined. The effects of rotation, tip clearance, and inlet boundary-later thickness variation on the predicted blade and end-wall heat transfer are examined. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,CLEVELAND,OH 44142. RP BOYLE, RJ (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135, USA. NR 21 TC 4 Z9 5 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 1995 VL 11 IS 6 BP 1179 EP 1186 DI 10.2514/3.23957 PG 8 WC Engineering, Aerospace SC Engineering GA TF316 UT WOS:A1995TF31600012 ER PT J AU RODI, PE AF RODI, PE TI EFFECTS OF BODY-SIDE COMPRESSION ON FORWARD-SWEPT SIDEWALL COMPRESSION INLETS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Forward-swept sidewall compression inlets have been tested at Mach 4 to study the effects of body-side compression surfaces on inlet performance, The measurements include mass flow capture and mean surface pressure distributions obtained during simulated combustion-induced pressure increases downstream of the inlet, Inlet performance is evaluated using starting and unstarting characteristics, mass capture, mean surface pressure distributions, and permissible back-pressure limits, The results indicate that inlet performance can be improved with selected body-side compression surfaces placed between the inlet sidewalls. RP RODI, PE (reprint author), NASA,LANGLEY RES CTR,HYPERSON AIRBREATHING PROPULS BRANCH,M-S 168,HAMPTON,VA 23681, USA. NR 16 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 NOV-DEC PY 1995 VL 11 IS 6 BP 1242 EP 1249 DI 10.2514/3.23964 PG 8 WC Engineering, Aerospace SC Engineering GA TF316 UT WOS:A1995TF31600019 ER PT J AU GOLDMAN, A RINSLAND, CP CANOVA, B ZANDER, R DANGNHU, M AF GOLDMAN, A RINSLAND, CP CANOVA, B ZANDER, R DANGNHU, M TI IMPROVED SPECTRAL PARAMETERS FOR THE O-16(2) INFRARED FORBIDDEN LINES IN THE X(3)SIGMA(-)(G)(0-1) BAND SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID QUADRUPOLE FUNDAMENTAL-BAND; OXYGEN MOLECULE; TRANSITIONS; STRENGTHS; IDENTIFICATION; O2; N2 AB New spectral parameters have been generated for the electric quadrupole (eg) and magnetic dipole (md) infrared transitions in the fundamental vibration-rotation (3) Sigma(g)(-) (0-1) band of O-16(2). Significant improvements in line positions (for both eq and md) and in the long standing problem of the md line intensities, have been achieved by combining recent theoretical work with the analysis of high resolution (0.002 and 0.01 cm(-1)) solar absorption spectra. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. UNIV LIEGE,INST ASTROPHYS,LIEGE,BELGIUM. UNIV PARIS 11,CNRS,INFRAROUGE LAB,F-91405 ORSAY,FRANCE. RP GOLDMAN, A (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. NR 23 TC 7 Z9 7 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV PY 1995 VL 54 IS 5 BP 757 EP 765 DI 10.1016/0022-4073(95)00114-Z PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA TE912 UT WOS:A1995TE91200001 ER PT J AU STEYERT, DW WEBER, M SIROTA, JM REUTER, DC AF STEYERT, DW WEBER, M SIROTA, JM REUTER, DC TI ABSOLUTE INTENSITIES FOR THE Q-BRANCH OF THE 4-NU(2)(2)[-3-NU(2)(3) (581.776-CM(-1)) BAND IN CARBON-DIOXIDE SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article AB Absolute intensity measurements in the Q-branch of the 4 nu(2)(2) <-> 3 nu(2)(3) band of CO2 at 581.776 cm(-1) have been performed using tunable diode laser spectroscopy. It was found that the values listed in the HITRAN [Ref. 1, Rothman et al, JQRST 48, 537 (1999)] database, which are calculated by direct numerical diagonalization, are 5% higher than those measured here. The vibrational band strength is 4.963(56) x 10(-3) cm(-2) atm(-1) at 296 K. A vanishing Hermann-Wallis coefficient is adequate to characterize this band up to J = 40. C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RI Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 10 TC 6 Z9 6 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 NOV PY 1995 VL 54 IS 5 BP 815 EP 818 DI 10.1016/0022-4073(95)00101-P PG 4 WC Optics; Spectroscopy SC Optics; Spectroscopy GA TE912 UT WOS:A1995TE91200005 ER PT J AU WANG, Y YELLE, RV AF WANG, Y YELLE, RV TI METHANE HEATING RATES IN OUTER PLANET ATMOSPHERES SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID ABSORPTION; NEPTUNE; MODELS AB We have reviewed and expanded the techniques for calculating the heating rates of CH4 near-i.r. bands (3.3, 2.3, and 1.7 mu m) for conditions relevant to the atmospheres of the outer planets. We consider all pressures below 100 mbar and temperatures from 77 to 300 K. We find that using the correlated-k method, the heating rates of the stronger band, 3.3 mu m band, at all pressures and the heating rates for the other two bands at pressures below 0.1 mbar can be accurately calculated. We also find that the application of the general random band models which depend on the line listings is not appropriate to these three bands. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NR 16 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 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV PY 1995 VL 54 IS 5 BP 819 EP 826 DI 10.1016/0022-4073(95)00097-5 PG 8 WC Optics; Spectroscopy SC Optics; Spectroscopy GA TE912 UT WOS:A1995TE91200006 ER PT J AU FLETCHER, DG MCDANIEL, JC AF FLETCHER, DG MCDANIEL, JC TI COLLISIONAL SHIFT AND BROADENING OF IODINE SPECTRAL-LINES IN AIR NEAR 543 NM SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID PLANAR MEASUREMENT; FLUORESCENCE; TEMPERATURE; POLARIZABILITIES; BAND; I2 AB The collisional processes that influence the absorption of monochromatic light by iodine in air have been investigated. Measurements were made in both a static cell and an underexpanded jet flow over the range of properties encountered in typical compressible-flow aerodynamic applications. Experimentally measured values of the collisional shift and broadening coefficients were 0.058 +/- 0.004 and 0.53 +/- 0.010 GHz K-0.7/torr, respectively. The measured shift value showed reasonable agreement with theoretical calculations based on Lindholm-Foley collisional theory for a simple dispersive potential. The measured collisional broadening showed less favorable agreement with the calculated value. C1 UNIV VIRGINIA,AEROSP RES LAB,CHARLOTTESVILLE,VA 22903. RP FLETCHER, DG (reprint author), NASA,AMES RES CTR,MS229-1,MOFFETT FIELD,CA 94035, USA. NR 40 TC 10 Z9 10 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV PY 1995 VL 54 IS 5 BP 837 EP 850 DI 10.1016/0022-4073(95)00105-T PG 14 WC Optics; Spectroscopy SC Optics; Spectroscopy GA TE912 UT WOS:A1995TE91200008 ER PT J AU HANSON, ML TOLSON, RH AF HANSON, ML TOLSON, RH TI REDUCING FLEXIBLE BASE VIBRATIONS THROUGH LOCAL REDUNDANCY RESOLUTION SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID MANIPULATORS AB Future space systems will use teleoperated robotic systems mounted on flexible bases such as the Shuttle Remote Manipulator System. Due to dynamic coupling, a major control issue associated with these systems is the effect of flexible base vibrations on the performance of the robot. If uncompensated, flexible vibrations can lead to inertial tracking errors and an overall degradation in system performance. One way to overcome this problem is to use kinematically redundant robots. Thus, this article presents research results obtained from locally resolving kinematic redundancies to reduce or damp flexible vibrations. Using a planar, three-link rigid robot example, numerical simulations were performed to evaluate the feasibility of three vibration damping redundancy control algorithms. Results showed that compared to a zero redundancy baseline, the three controllers were able to reduce base vibration by as much as 90% in addition to decreasing the required amount of joint torque. However, similar to locally optimizing joint torques, excessive joint velocities often occurred. To improve stability, fixed weight, multi-criteria optimizations were performed. (C) 1995 John Wiley & Sons, Inc. RP GEORGE WASHINGTON UNIV, NASA, DSIR LAND RESOURCES, JOINT INST ADVANCEMENT FLIGHT SCI, HAMPTON, VA 23681 USA. NR 34 TC 10 Z9 10 U1 0 U2 4 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD NOV PY 1995 VL 12 IS 11 BP 767 EP 779 DI 10.1002/rob.4620121106 PG 13 WC Robotics SC Robotics GA RY918 UT WOS:A1995RY91800005 ER PT J AU Ardema, MD Bowles, JV Whittaker, T AF Ardema, MD Bowles, JV Whittaker, T TI Near-optimal propulsion-system operation for an air-breathing launch vehicle SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID GUIDANCE AB A methodology for determining the near-optimal operation of the propulsion system of hybrid air-breathing launch vehicles is derived. The method is based on selecting propulsion-system modes and parameters that maximize a certain performance function. This function is derived from consideration of the energy-state model of the aircraft equations of motion. The vehicle model reflects the many interactions and complexities of the multimode air-breathing and rocket engine systems proposed for launch-vehicle use. The method is used to investigate the optimal throttle switching of air-breathing and rocket engine modes, and to investigate the desirability of using liquid-oxygen augmentation in air-breathing engine cycles, the oxygen either carried from takeoff or collected in flight. It is found that the air-breathing engine is always at full throttle, and that the rocket is on full at takeoff and at very high Mach numbers, but off otherwise. Augmentation of the air-breathing engine with stored liquid oxygen is beneficial, but only marginally so. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. STERLING SOFTWARE,MOFFETT FIELD,CA 94035. RP Ardema, MD (reprint author), SANTA CLARA UNIV,DEPT MECH ENGN,SANTA CLARA,CA 95053, USA. NR 6 TC 10 Z9 11 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 NOV-DEC PY 1995 VL 32 IS 6 BP 951 EP 956 DI 10.2514/3.26714 PG 6 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400004 ER PT J AU Braun, RD Powell, RW Engelund, TC Gnoffo, PA Weilmuenster, KJ Mitcheltree, RA AF Braun, RD Powell, RW Engelund, TC Gnoffo, PA Weilmuenster, KJ Mitcheltree, RA TI Mars pathfinder six-degree-of-freedom entry analysis SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars Pathfinder mission provides the next opportunity for scientific exploration of the surface of Mars following a 7.6 km/s direct entry: In support of this effort, a six-degree-of-freedom trajectory analysis and aerodynamic characteristic assessment are performed to demonstrate vehicle flyability and to quantify the effect that each of numerous uncertainties has upon the nominal mission profile. The entry vehicle is shown to be aerodynamically stable over a large portion of its atmospheric flight. Two low angle-of-attack static instabilities (freestream velocities of about 6.5 and 3.5 km/s) and a low angle-of-attack dynamic instability (supersonic) are identified and shown to cause bounded increases in vehicle attitude. The effects of center-of-gravity placement, entry attitude, vehicle roll rate, aerodynamic misprediction, and atmospheric uncertainty on the vehicle attitude profile and parachute deployment conditions are quantified. A Monte Carlo analysis is performed to statistically assess the combined impact of multiple off-nominal conditions on the nominal flight characteristics. These results suggest that there is a 99.7% probability that the peak attitude throughout the entry will be less than 8.5 deg, the peak heating attitude mill be below 6.2 deg, and the attitude at parachute deployment will be less than 3.9 deg. C1 NASA,LANGLEY RES CTR,DIV GAS DYNAM,HAMPTON,VA 23681. RP Braun, RD (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST & CONCEPTS,HAMPTON,VA 23681, USA. NR 22 TC 44 Z9 45 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 993 EP 1000 DI 10.2514/3.26720 PG 8 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400010 ER PT J AU Garrett, HB Rustan, P AF Garrett, HB Rustan, P TI Clementine engineering experiments program SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Spacecraft must survive and operate reliably in the space environments for long periods of time. Radiation, temperature variations, spacecraft charging, surface contamination, micrometeoroids, and space debris all present environmental challenges to spacecraft missions. The environmental issues associated with these effects require in situ space experiments to properly quantify the environment and its effects. To obtain data on specific mirco-electronic and sensor systems in the space environment, several engineering experiments were developed for the Clementine spacecraft and the Clementine lunar transfer booster or Interstage Adapter Satellite. These platforms allowed testing of advanced spacecraft microelectronic and sensor devices in a lunar transfer orbit that intersects Earth's radiation belts and debris environment and in interplanetary space where direct exposure to solar flares, galactic cosmic rays, and micrometeoroids was possible. A suite of experiments was developed by the Naval Research Laboratory, the Jet Propulsion Laboratory, NASA Langley Research Center, the Aerospace Corporation, and NASA Goddard Space Flight Center to investigate in detail specific radiation and environmental reliability issues. This paper presents an introduction to the issues being investigated, the instruments provided for the mission, and the rationale for the engineering program. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Garrett, HB (reprint author), BALLIST MISSILE DEF ORG,WASHINGTON,DC 20301, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 1045 EP 1048 DI 10.2514/3.26728 PG 4 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400019 ER PT J AU Baker, DN Kanekal, S Blake, JB Adams, JH AF Baker, DN Kanekal, S Blake, JB Adams, JH TI Charged-particle telescope experiment on Clementine SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The charged-particle telescope (CPT) onboard the Clementine spacecraft measured the fluxes of energetic protons emitted in solar energetic particle events. Protons in the energy range from 10 to 80 MeV were of greatest interest for radiation effects such as total dose and single event upsets. Energetic electrons were also of interest for spacecraft charging and their contribution to total dose. The lower-energy CPT electron channels (25-500 keV) were mainly of geophysical interest. While orbiting the moon, the CPT observed the wake created by the moon when it blocked the flow of energetic particles in the magnetotail region. The CPT provided opportunities to observe energetic electron bursts during magnetic storms and magnetospheric substorms. CPT data are particularly useful in multispacecraft studies of interplanetary disturbances and their interaction with the magnetosphere. The proton channels on the CPT provided data on solar energetic protons and storm-time protons associated with the passage of an interplanetary shock at 0903 UT on Feb. 21, 1994. Results are compared with those from GOES-7, SAMPEX, and GEOTAIL. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. AEROSP CORP,LOS ANGELES,CA 90009. USN,RES LAB,DIV SPACE SCI,COSM RAY SECT,WASHINGTON,DC 20375. RP Baker, DN (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,CAMPUS BOX 590,BOULDER,CO 80309, USA. NR 10 TC 2 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 1060 EP 1064 DI 10.2514/3.26731 PG 5 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400022 PM 11539374 ER PT J AU Soli, G Blaes, B Buehler, M Jones, P Ratliff, JM Garrett, H AF Soli, G Blaes, B Buehler, M Jones, P Ratliff, JM Garrett, H TI Clementine dosimetry SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper presents radiation dosimetry results from the radiation and reliability assurance experiments on the Clementine spacecraft and Interstage Adapter Satellite. The dosimetry instruments utilize low-dose-response p-channel field-effect-transistor and proton-sensitive static-RAM dosimeters. These dosimeters successfully demonstrated an order-of-magnitude decrease in instrument weight and power from previous systems. The data confirm prelaunch predictions of the total-dose effects on charge-coupled-device dark current and on complementary-metal-oxide-semiconductor 1.2 and 0.8-mu m technology design and process parameters in the space environment. A solar proton event during the early phases of the mission allowed a comparison between the Clementine measured proton fluence and energy spectra and the Geostationary Operational Environmental Satellite 6 measured proton fluence and energy spectra. These data confirmed the proton-spectrometer design and operation. C1 BALLIST MISSILE DEF ORG,INNOVAT SCI & TECHNOL OFF,TECH STAFF,WASHINGTON,DC 20301. RP Soli, G (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 1065 EP 1070 DI 10.2514/3.26732 PG 6 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400023 ER PT J AU Garrett, HB Johnson, MS Ratliff, JM Johnston, A Anderson, S Stapor, WJ AF Garrett, HB Johnson, MS Ratliff, JM Johnston, A Anderson, S Stapor, WJ TI Single-event upset effects on the Clementine solid-state data recorder SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ION TRACKS AB The sensitivity of the Clementine 2.1-Gbit solid-state data recorder (SSDR) to single-event upsets was characterized in ground tests. Subsequent in situ measurements of the ambient radiation environment by experiments onboard Clementine permitted evaluation of the ability of models of the single-event phenomenon in the SSDR to be tested using actual data. Initial results from the analysis reveal a nearly constant background upset rate of similar to 71 bit flips/day for the SSDR. There is no obvious correlation with a solar proton event recorded by Clementine and several other spacecraft on Feb. 20-21, 1994, indicating that the SSDR was not sensitive to protons. The constant rate is thus interpreted as being a function of the galactic cosmic-ray heavy-ion environment. A pronounced lunar orbit altitude dependence has also been identified in the data though the cause has not yet been unambiguously identified. C1 USN,RES LAB,WASHINGTON,DC 20375. CALTECH,JET PROP LAB,PASADENA,CA 91109. SEAKR ENGN INC,TORRANCE,CA 90503. EER,TECH STAFF,MONTROSE,CA 91020. RP Garrett, HB (reprint author), BALLIST MISSILE DEF ORG,WASHINGTON,DC 20301, USA. NR 9 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 NOV-DEC PY 1995 VL 32 IS 6 BP 1071 EP 1076 DI 10.2514/3.26733 PG 6 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400024 ER PT J AU Culpepper, M Garrett, H Shannon, M AF Culpepper, M Garrett, H Shannon, M TI Estimates of the Clementine interstage adapter satellite tumble rate SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. RP Culpepper, M (reprint author), USAF,PHILLIPS LAB,TECH STAFF,KIRTLAND AFB,NM 87117, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 1077 EP 1078 DI 10.2514/3.26734 PG 2 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400025 ER PT J AU Riley, CJ DeJarnette, FR AF Riley, CJ DeJarnette, FR TI Engineering interactive inviscid boundary-layer method for hypersonic flow SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP Riley, CJ (reprint author), NASA,LANGLEY RES CTR,AEROTHERMODYNAM BRANCH,DIV GAS DYNAM,HAMPTON,VA 23681, USA. NR 19 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 1995 VL 32 IS 6 BP 1081 EP 1083 DI 10.2514/3.26736 PG 3 WC Engineering, Aerospace SC Engineering GA TK774 UT WOS:A1995TK77400027 ER PT J AU HOPS, JM SHERIF, JS AF HOPS, JM SHERIF, JS TI DEVELOPMENT AND APPLICATION OF COMPOSITE COMPLEXITY MODELS AND A RELATIVE COMPLEXITY METRIC IN A SOFTWARE MAINTENANCE ENVIRONMENT SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article AB A great deal of effort is now being devoted to the study, analysis, prediction, and minimization of expected software maintenance cost, long before software is delivered to users or customers. It had been estimated that, on the average, the effort spent on software maintenance is as costly as the effort spent on all other software stages. Ways to alleviate software maintenance complexity and high costs should originate in software design. Two aspects of maintenance deserve attention: protocols for locating and rectifying defects and ensuring that no new defects are introduced in the development phase of the software process, and development of protocols for increasing the quality and reducing the costs associated with modification, enhancement, and upgrading of software. This article focuses on the second aspect and puts forward newly developed parsimonious models and a relative complexity metric for complexity measurement of software that were used to rank the modules in the system relative to each other. Significant success was achieved by use of the models and relative metric to identify maintenance-prone modules. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALIF STATE UNIV FULLERTON,FULLERTON,CA 92634. NR 34 TC 7 Z9 7 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD NOV PY 1995 VL 31 IS 2 BP 157 EP 169 DI 10.1016/0164-1212(94)00095-5 PG 13 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA TA707 UT WOS:A1995TA70700007 ER PT J AU SATHISH, S MENDIK, M CANTRELL, JH YOST, WT AF SATHISH, S MENDIK, M CANTRELL, JH YOST, WT TI ELASTIC-CONSTANTS AND CRYSTAL ORIENTATION OF INDIVIDUAL GRAINS OF POLYCRYSTALLINE SOLIDS FROM SCANNING ACOUSTIC MICROSCOPY SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Letter ID BRILLOUIN-SCATTERING AB The angular dependence of the surface acoustic wave velocity has been measured on an individual grain of aluminum alloy 2519 using a continuous-wave scanning acoustic microscope equipped with a cylindrical lens. The elastic constants and crystal orientation of the grain have been determined simultaneously using a two step nonlinear least-squares fitting of the data. This is the first time that simultaneous measurements of these properties have been reported using scanning acoustic microscopy. The C-11 elastic constant is determined to be (113 +/- 5) GPa, C-12 is (61 +/- 3) GPa, and C-44 is (29 +/- 2) GPa. These values are within 5% of those reported for pure aluminum. The average Young's modulus for the grain is calculated from the elastic constants to be (74.5 +/- 3.0) GPa and is in agreement with the value 74.4 GPa reported for static load measurements of bulk Al 2519 material. The surface plane orientation of the grain is determined to be (210)+/- 4 degrees and is in agreement with an independent determination using x-ray Laue back reflection measurements. (C) 1995 Acoustical Society of America. C1 COLORADO STATE UNIV,DEPT PHYS,FT COLLINS,CO 80523. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP SATHISH, S (reprint author), ANALYT SERV & MAT INC,107 RES DR,HAMPTON,VA 23666, USA. NR 25 TC 11 Z9 11 U1 0 U2 4 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 NOV PY 1995 VL 98 IS 5 BP 2854 EP 2857 DI 10.1121/1.413187 PN 1 PG 4 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA TB921 UT WOS:A1995TB92100054 ER PT J AU PARK, CK SUAREZ, MJ SCHUBERT, SD AF PARK, CK SUAREZ, MJ SCHUBERT, SD TI RESPONSE OF THE ZONALLY ASYMMETRIC FLOW TO TIME-DEPENDENT TROPICAL HEATING SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CIRCULATION ANOMALIES; TRANSIENT-RESPONSE; DAY OSCILLATION; FIELD BEHAVIOR; MODELS; FLUCTUATIONS; SIMULATIONS; CONVECTION AB An atmospheric general circulation model is used to study the impact of idealized zonally propagating tropical heating anomalies on the low-frequency variability in the North Pacific region. The propagating heating is designed to mimic the thermal forcing associated with the Madden-Julian oscillation (MJO). Results are examined by separating the forced response from other variability and by comparing with runs employing fixed-phase (stationary) heating anomalies. For both the forced and free circulations, the main modes of variability consist of a zonal expansion and retraction of the East Asian jet. The effective Rossby wave forcing associated with the heating is dominated by the advection term and located in the subtropics in the regions of strong absolute vorticity gradients. Compared with cases using stationary forcing, the response to the propagating forcing is weaker and of different phase, indicating that the 40-day period used for the propagating anomalies is too short to allow the development of the steady-state response in the extratropics. The model's total low-frequency variability in the North Pacific sector is dominated by the free oscillations that are the result of local processes uncorrelated with tropical variability. The relatively small forced response appears to be partly the result of the simplicity of the propagating heating anomaly that propagates at a constant phase speed and the simplifications introduced into the GCM that do not allow transient feedback in the diabatic heating. It is suggested that the lack of a significant Rossby wave stretching term in the subtropics is a distinguishing feature of the east-west dipole heating anomalies of the MJO and may contribute to the weakness of the response compared to interannual tropical heating anomalies. C1 UNIV MARYLAND,DEPT METEOROL,JOINT CTR EARTH SYST SCI,COLLEGE PK,MD 20742. RP PARK, CK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,DATA ASSIMILAT OFF,MAIL CODE 9103,GREENBELT,MD 20771, USA. NR 23 TC 11 Z9 11 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD NOV 1 PY 1995 VL 52 IS 21 BP 3738 EP 3756 DI 10.1175/1520-0469(1995)052<3738:ROTZAF>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TD257 UT WOS:A1995TD25700007 ER PT J AU Krasich, M AF Krasich, M TI Getting bigger, better, and stronger SO JOURNAL OF THE INSTITUTE OF ENVIRONMENTAL SCIENCES LA English DT Editorial Material RP Krasich, M (reprint author), JET PROP LAB,4800 OAK GROVE DR,M-S 301-466,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J INST ENVIRON SCI JI J. Inst. Environ. Sci. PD NOV-DEC PY 1995 VL 38 IS 6 BP 12 EP 12 PG 1 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA TL952 UT WOS:A1995TL95200001 ER PT J AU Hine, MJ AF Hine, MJ TI Swept sine vibration test conservatism SO JOURNAL OF THE INSTITUTE OF ENVIRONMENTAL SCIENCES LA English DT Article DE vibration; test; conservatism; swept-sine AB The excessive overtest associated with the swept sine vibration test method was measured quantitatively using the index of conservatism and the associated overtest factor for a dynamic mass model of a typical spacecraft component. The response to a fixed amplitude sine sweep test was compared with the flight transient vibration environment for sweep rates of 2, 4, and 6 octaves/min and 300 Hz/min. A response-limited test was also conducted at 6 octaves/min. The conservatism was measured using several characterizations; namely: number of peaks exceeding, ranked peaks, shock response spectrum, shock intensity, three-dimensional shock response spectrum, and ranked peaks. Overtest factors exceeding an order of magnitude were measured for the test response with the number of peaks exceeding and the three-dimensional shock response spectrum. RP Hine, MJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91125, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J INST ENVIRON SCI JI J. Inst. Environ. Sci. PD NOV-DEC PY 1995 VL 38 IS 6 BP 13 EP 17 PG 5 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA TL952 UT WOS:A1995TL95200002 ER PT J AU Yater, JA Plaut, AS Kash, K Lin, PSD Florez, LT Harbison, JP Das, SR Lebrun, L AF Yater, JA Plaut, AS Kash, K Lin, PSD Florez, LT Harbison, JP Das, SR Lebrun, L TI Photoluminescence of quantum dots fabricated using tungsten stressors SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID GAAS; CONFINEMENT; WIRES; BOXES AB Strain modulation of a semiconductor band gap spatially confines excitons in a near-surface GaAs/AlGaAs quatum well. mie report photoluminescence (PL) results of quantum dot arrays fabricated using tungsten stressors. Excitons are cofined in a 35 meV potential well under 100 nm dot stressors, which is 2.4 times deeper than that observed using 100 nm carbon stressors. Such a confinement potential corresponds to quantum dot energy level splittings of approximately 7 meV. Arrays of dots are studied, each with individual stressors of a different size ranging from 100 to 800 nm. The lateral potential well depth, as measured by the red shift in PL signal, is dependent on the stresser width and thickness in a well-understood manner. The integrated PL signal from the dots increases with increasing temperature, indicating increased efficiency of trapping of excitons from the quantum well into the quantum dots. Interpretation of excitation spectra, and observation of higher energy levels, are complicated by the details of the strain pattern and the near-field coupling of radiation between the metallic stressors and the quantum well. (C) 1995 American Vacuum Society. C1 UNIV EXETER, DEPT PHYS, EXETER EX4 4RJ, DEVON, ENGLAND. CASE WESTERN RESERVE UNIV, DEPT PHYS, CLEVELAND, OH 44106 USA. BELLCORE, RED BANK, NJ 07701 USA. NATL RES COUNCIL CANADA, OTTAWA, ON K1A 0R6, CANADA. RP Yater, JA (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. OI Kash, Kathleen/0000-0002-6126-7302 NR 20 TC 2 Z9 2 U1 0 U2 3 PU A V S AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD NOV-DEC PY 1995 VL 13 IS 6 BP 2284 EP 2288 DI 10.1116/1.588063 PG 5 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA TN816 UT WOS:A1995TN81600025 ER PT J AU ARRIGO, KR DIECKMANN, G GOSSELIN, M ROBINSON, DH FRITSEN, CH SULLIVAN, CW AF ARRIGO, KR DIECKMANN, G GOSSELIN, M ROBINSON, DH FRITSEN, CH SULLIVAN, CW TI HIGH-RESOLUTION STUDY OF THE PLATELET ICE ECOSYSTEM IN MCMURDO SOUND, ANTARCTICA - BIOMASS, NUTRIENT, AND PRODUCTION PROFILES WITHIN A DENSE MICROALGAL BLOOM SO MARINE ECOLOGY PROGRESS SERIES LA English DT Article DE ANTARCTIC; PLATELET ICE; NUTRIENT CYCLING ID MICROBIAL COMMUNITIES SIMCO; ANNUAL SEA ICE; BACTERIAL PRODUCTION; BOTTOM ICE; PHYTOPLANKTON; ABUNDANCE; GROWTH; ALGAE; PHOTOADAPTATION; CANADA AB Vertical distributions of inorganic nutrients (nitrate, nitrite, ammonium, phosphate, and silicic acid) and microalgal and bacterial biomass were monitored within both the lower congelation ice and the platelet ice layer in McMurdo Sound, Antarctica from 31 October to 3 December 1989. Profiles of dissolved organic matter (DOM) (amino acids and simple sugars) and heterotrophic protists were also obtained in early December. Microalgal standing crop increased from 9.4 to 37.4 g C m(-2) during our 34 d study (peak accumulation rate of >1 g C m(-2) d(-1)), and maximum pigment concentrations exceeded 6500 mg chl a m(-3) near the congelation ice/platelet ice interface. Estimates of seawater exchange within the platelet ice ranged from 0.06 to 0.61 m(2) d(-1) when Si(OH)(4) was used as a tracer. The biochemical composition of the autotrophic community and the presence of high nutrient concentrations within the platelet layer indicated that the growth of platelet ice algae was limited by Light, rather than nutrients, throughout the season. NO3 and Si(OH)(4) concentrations in the platelet ice were generally high (30 to 32 and 65 to 82 mmol m(-3), respectively), but became depleted in the uppermost layers as chl a peaked late in November. NH4 was far more abundant in the platelet ice (5 to 10 mmol m(-3)) than in the underlying water column (0.5 mmol m(-3)) throughout the field season. Microbial regenera- tion was primarily responsible for the high background concentrations of NH4 in the platelet ice, although physical processes also may have contributed. A large NH4 pulse (>150 mmol m(-3)) was observed in the platelet layer in early November, possibly attributable to an isolated macrozooplankton grazing and excretion event. PO4 concentrations (2.0 mmol m(-3) in the water column) were minimal (<1.7 mmol m(-3)) in the upper platelet ice on November 11, but began to increase thereafter due to PO4 regeneration. By early December, concentrations reached their maximum of 3.73 mmol m(-3). Rates of PO4 regeneration were highest (peak of 35 mmol m(-3) d(-1)) in the upper layers of the platelet ice where the bulk of the microbial biomass was located. The platelet ice was unusual because, although concentrations of regenerated nutrients were often high, the elemental composition of particulates remained near the Redfield ratios and detrital abundance was low. The coincidence of NO2 and NO3 peaks at a depth of 0.65 to 0.75 m suggests that bacterial nitrification may also occur in the platelet ice. C1 ALFRED WEGENER INST POLAR & MARINE RES, D-27570 BREMERHAVEN, GERMANY. UNIV QUEBEC, DEPT OCEANOG, RIMOUSKI, PQ GL5 3A1, CANADA. UNIV SO CALIF, DEPT BIOL SCI, LOS ANGELES, CA 90080 USA. NATL SCI FDN, OFF POLAR PROGRAMS, ARLINGTON, VA 22230 USA. RP ARRIGO, KR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, OCEANS & ICE BRANCH, GREENBELT, MD 20771 USA. RI Dieckmann, Gerhard/B-4307-2010; Gosselin, Michel/B-4477-2014 OI Gosselin, Michel/0000-0002-1044-0793 NR 59 TC 55 Z9 58 U1 0 U2 8 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0171-8630 J9 MAR ECOL PROG SER JI Mar. Ecol.-Prog. Ser. PD NOV PY 1995 VL 127 IS 1-3 BP 255 EP 268 DI 10.3354/meps127255 PG 14 WC Ecology; Marine & Freshwater Biology; Oceanography SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Oceanography GA TG880 UT WOS:A1995TG88000023 ER PT J AU ZHANG, Y LITVIN, FL HANDSCHUH, RF AF ZHANG, Y LITVIN, FL HANDSCHUH, RF TI COMPUTERIZED DESIGN OF LOW-NOISE FACE-MILLED SPIRAL BEVEL GEARS SO MECHANISM AND MACHINE THEORY LA English DT Article AB An advanced design methodology is proposed for the face-milled spiral bevel gears with modified tooth surface geometry that provides a reduced level of noise and has a stabilized bearing contact. The approach is based on the local synthesis of the gear drive that provides the ''best'' machine-tool settings. The theoretical aspects of the local synthesis approach are based on the application of a predesigned parabolic Function for absorption of undesirable transmission errors caused by misalignment and the direct relations between principal curvatures and directions for mating surfaces. The meshing and contact of the gear drive is synthesized and analyzed by a computer program. The generation of gears with the proposed geometry design can be accomplished with existing equipment. A numerical example that illustrates the proposed theory is presented. C1 UNIV ILLINOIS,CHICAGO,IL 60612. NASA,LEWIS RES CTR,CLEVELAND,OH 44315. RP ZHANG, Y (reprint author), UNIV MICHIGAN,DEARBORN,MI 48128, USA. NR 13 TC 34 Z9 35 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-114X J9 MECH MACH THEORY JI Mech. Mach. Theory PD NOV PY 1995 VL 30 IS 8 BP 1171 EP 1178 DI 10.1016/0094-114X(95)00052-Z PG 8 WC Engineering, Mechanical SC Engineering GA RY475 UT WOS:A1995RY47500006 ER PT J AU GARRISON, DH RAO, MN BOGARD, DD AF GARRISON, DH RAO, MN BOGARD, DD TI SOLAR-PROTON-PRODUCED NEON IN SHERGOTTITE METEORITES AND IMPLICATIONS FOR THEIR ORIGIN SO METEORITICS LA English DT Article ID NOBLE-GASES; COSMOGENIC NUCLIDES; SNC METEORITES; MARTIAN ORIGIN; CHONDRITES; COMPILATION; PROFILES; NE-21; SALEM; GLASS AB Measured Ne isotopes in samples of shergottite ALHA77005 show variations in Ne-21/Ne-22 ratios and Ne-21 abundances that are consistent with the presence of two cosmogenic components: a component produced by nuclear interactions of galactic cosmic rays (GCR) and a component produced at shallow shielding depths (similar to 0-3 cm) by energetic solar flare protons (SCR). We suggest that the Ne-21/Ne-22 ratio generally can be used to distinguish between SCR and GCR components in many meteorite types. Analysis of cosmogenic Ne produced in chondrite mineral separates, eucrites, and anorthositic lunar rocks, all having diverse major element compositions, indicate that the GCR Ne-21/Ne-22 ratio increases modestly with relative Mg content. Data for hundreds of chondrite analyses suggest that SCR Ne is present in no more than a very small fraction of chondrites. Examination of literature data for other shergottites, however, indicate that all of these meteorites contain SCR Ne but that it is apparently absent in other SNC meteorites. The ubiquitous presence of SCR Ne in shergottites, in contrast to most other types of meteorites, suggests that the martian origin of shergottites gave them different orbital parameters compared to other meteorites. This in turn may have contributed to slower entry velocities and lesser surface ablation in the atmosphere or even to higher SCR production rates. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. NR 58 TC 34 Z9 34 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 738 EP 747 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800016 ER PT J AU KROT, AN SCOTT, ERD ZOLENSKY, ME AF KROT, AN SCOTT, ERD ZOLENSKY, ME TI MINERALOGICAL AND CHEMICAL MODIFICATION OF COMPONENTS IN CV3 CHONDRITES - NEBULAR OR ASTEROIDAL PROCESSING SO METEORITICS LA English DT Review ID ALLENDE CARBONACEOUS CHONDRITE; HIGH-TEMPERATURE CONDENSATION; EARLY SOLAR NEBULA; REFRACTORY INCLUSIONS; COMPOSITIONAL CLASSIFICATION; VIGARANO TYPE; CA,AL-RICH INCLUSION; OPAQUE ASSEMBLAGES; AQUEOUS ALTERATION; RICH FREMDLINGE AB Calcium- and aluminum-rich inclusions (CAIs), chondrules, dark inclusions and matrices in certain CV3 carbonaceous chondrites appear to have been modified by different degrees of late-stage alteration processes that caused significant variations in mineralogy and chemistry. Some chondrules and CAIs are rimmed with fayalitic olivine. Metal in all components may be oxidized and sulphidized to magnetite, Ni-rich metal and sulfides. Silicates in all components are aqueously altered to different degrees to phyllosilicates. Primary minerals in some CAIs experienced Fe-alkali-halogen metasomatism forming nepheline, sodalite, wollastonite, hedenbergite and other secondary minerals. In CV3 chondrites with metasomatized CAIs, nepheline, sodalite, etc. are also present in chondrule mesostases and in matrices. McSween's (1977b) reduced subgroup of CV3 chondrites generally shows minimal alteration of all components and may represent the unaltered precursors for the oxidized CV3 chondrites, which generally show major alteration. Most studies have been focused on specific components in CV3 chondrites and have not considered possible relationships between alteration processes. We infer from the correlated occurrences of the alteration features that they were closely related in time and space and review nebular and asteroidal models for their origins. We prefer an asteroidal model. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV EARTH SCI & SOLAR SYST EXPLORAT,HOUSTON,TX 77058. RP KROT, AN (reprint author), UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,HAWAII INST GEOPHYS & PLANETOL,HONOLULU,HI 96822, USA. NR 185 TC 258 Z9 261 U1 7 U2 23 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 748 EP 775 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800017 ER PT J AU MCCOY, TJ EHLMANN, AJ KEIL, K AF MCCOY, TJ EHLMANN, AJ KEIL, K TI THE FAYETTE-COUNTY, TEXAS, METEORITES SO METEORITICS LA English DT Note ID ORDINARY CHONDRITES; METAMORPHISM AB We report the first petrologic examination of all stone meteorites of Fayette County, Texas. The 10 stones represent four or five different fall events. The three recovered Bluff stones represent two falls. Bluff(a), which includes the 145.5-kg Bluff#1 stone, is classified as L5(S4), whereas Bluff(b) is classified as L4(S3) and is represented by a single stone. The studied Cedar stones are classified as H4(S3), and all four Cedar stones appear to define a strewnfield. Round Top (a), classified as L5(S3) and represented by two stones, is unrelated to either Bluff or Cedar. Round Top (b) [H4(S3); 1 stone], whose exact provenance is unknown, might be a transported fragment of the Cedar shower. C1 UNIV HAWAII MANOA, SCH OCEAN & EARTH SCI & TECHNOL, HAWAII INST GEOPHYS & PLANETOL, HONOLULU, HI 96822 USA. TEXAS CHRISTIAN UNIV, DEPT GEOL, FT WORTH, TX 76129 USA. UNIV HAWAII, HAWAII CTR VOLCANOL, HONOLULU, HI 96822 USA. RP MCCOY, TJ (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, CODE SN4, HOUSTON, TX 77058 USA. NR 18 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 776 EP 780 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800018 ER PT J AU REID, AM JAKES, P ZOLENSKY, ME MILLER, RM AF REID, AM JAKES, P ZOLENSKY, ME MILLER, RM TI RECOVERY OF 3 ORDINARY CHONDRITES, ROOIKOP 001-003, FROM THE NAMIB-DESERT IN WESTERN NAMIBIA SO METEORITICS LA English DT Note AB Reconnaissance searches for meteorites were made in five selected areas of western Namibia in 1991. Three new ordinary chondrites (H5, L5, L4/5) were recovered from one of the areas searched. C1 CHARLES UNIV,DEPT GEOL & MINERAL DEPOSITS,PRAGUE 2,CZECH REPUBLIC. NASA,LYNDON B JOHNSON SPACE CTR,DIV SOLAR SYST EXPLORAT,HOUSTON,TX 77058. NATL PETR CORP NAMIBIA,WINDHOEK,NAMIBIA. RP REID, AM (reprint author), UNIV HOUSTON,DEPT GEOSCI,HOUSTON,TX 77204, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 781 EP 784 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800019 ER PT J AU ZOLENSKY, M MARTINEZ, R DELOSRIOS, EM AF ZOLENSKY, M MARTINEZ, R DELOSRIOS, EM TI NEW L-CHONDRITES FROM THE ATACAMA-DESERT, CHILE SO METEORITICS LA English DT Note ID METEORITES; FINDS AB We describe five L chondrites found in the same region of the Atacama Desert, between Antofagasta and Mejillones. These are: Pampa (a), L6S1; Pampa (b), L4/5S4; Pampa (c), L4S6; Pampa (e), L6S1; Pampa de Agua Blanca, L6S4. The Antofagasta-Mejillones area could be a productive meteorite-producing region in the future. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP ZOLENSKY, M (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV EARTH SCI & SOLAR EXPLORAT,HOUSTON,TX 77058, USA. NR 9 TC 4 Z9 4 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 785 EP 787 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800020 ER PT J AU BENEDIX, GK KINSEY, LK MCCOY, TJ KEIL, K WIELER, R AF BENEDIX, GK KINSEY, LK MCCOY, TJ KEIL, K WIELER, R TI THE ROOSEVELT-COUNTY 079-090 METEORITES SO METEORITICS LA English DT Note ID CHONDRITES; METAMORPHISM AB We have classified 12 new, moderately to severely weathered meteorites from Roosevelt County, New Mexico (RC 079-090) that were recovered between 1969 and 1993. They include nine H chondrites and three L chondrites of petrologic types 4 to 6 and shock classification S1 to S4. Among these are a flight-oriented specimen of an H5 chondrite, an L4 chondrite with a porphyritic impact-melt rock clast, an H5 fragmental breccia with an unusual weathering assemblage (probably a Ca sulfate), and an H4 chondrite with unequilibrated pyroxenes. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. ETH ZURICH,CH-8092 ZURICH,SWITZERLAND. HAWAII CTR VOLCANOL,HONOLULU,HI. RP BENEDIX, GK (reprint author), UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,HAWAII INST GEOPHYS & PLANETOL,HONOLULU,HI 96822, USA. RI Wieler, Rainer/A-1355-2010; OI Wieler, Rainer/0000-0001-5666-7494; Benedix, Gretchen/0000-0003-0990-8878 NR 20 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD NOV PY 1995 VL 30 IS 6 BP 788 EP 791 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TD678 UT WOS:A1995TD67800021 ER PT J AU Ramachandran, N Baugher, CR Naumann, RJ AF Ramachandran, N Baugher, CR Naumann, RJ TI Modeling flows and transport in protein crystal growth SO MICROGRAVITY SCIENCE AND TECHNOLOGY LA English DT Article ID MICROGRAVITY AB Analytical and numerical models are developed to describe the flows and transport associated with the growth of protein and other macromolecular crystals under the influence of steady, transient, and periodic accelerations at various levels. Of primary inter est is the development of criteria for achieving diffusion limited transport since it is believed that growth under such conditions may have been responsible for the superior quality crystals obtained in some of the recent flight experiments. This criterion can also be used to determine if excessive acceleration disturbances may have been responsible for those flight experiments that did not produce superior crystals. For steady flows, it was found that the classical solution to the vertical heated flat plate could be adapted to describe the velocity and mass transport in the vicinity of a growing crystal. Empirical formulas based on dimensional analysis such as the Rantz-Marshall correlations for natural and forced convection can also be used after modification to account for the large Schmidt numbers typical of protein growth systems. As acceleration level is decreased, wall effects limit the flow and the momentum equation decouples from the mass transport equation. Finally it is shown that the steady state and periodic accelerations during typical Shuttle operations are sufficiently low to establish diffusion limited transport. However, impulsive disturbances from large thruster firings can disrupt these conditions for hours after the event. C1 UNIV ALABAMA,RES INST,HUNTSVILLE,AL 35899. UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NR 20 TC 31 Z9 31 U1 0 U2 0 PU CARL HANSER VERLAG PI MUNICH PA KOLBERGERSTRASSE 22, POSTFACH 860420, W-8163 MUNICH, GERMANY SN 0938-0108 J9 MICROGRAVITY SCI TEC JI Microgravity Sci. Technol. PD NOV PY 1995 VL 8 IS 3 BP 170 EP 179 PG 10 WC Engineering, Aerospace; Thermodynamics; Mechanics SC Engineering; Thermodynamics; Mechanics GA TW562 UT WOS:A1995TW56200005 ER PT J AU COCKELL, CS ROTHSCHILD, LJ AF COCKELL, CS ROTHSCHILD, LJ TI DNA-SYNTHESIS IN ALGAL MATS SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 NASA,AMES,ECOSYST SCI & TECHNOL BRANCH,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOL PI BETHESDA PA PUBL OFFICE 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD NOV PY 1995 VL 6 SU S BP 2056 EP 2056 PG 1 WC Cell Biology SC Cell Biology GA TF513 UT WOS:A1995TF51302056 ER PT J AU CHEN, CI AF CHEN, CI TI NUMERICAL SIMULATIONS OF GRAVITY CURRENTS IN UNIFORM SHEAR FLOWS SO MONTHLY WEATHER REVIEW LA English DT Article ID DENSITY CURRENTS; MODEL AB The purpose of this study is to examine the effect of wind shear on gravity currents in a neutral atmosphere by using a two-dimensional, nonhydrostatic primitive equation model. The depth of the gravity current is found to be directly related to the sign and the magnitude of the shear; a flow with a positive wind shear produces a gravity current of greater depth than that with a negative shear. As the positive wind shear (i.e., positive partial derivative u/partial derivative z) increases, the gravity current becomes unstable. For sufficiently large positive shear, the gravity current displays a diffuse structure with two distinct gravity current heads. It is found that enhanced eddy mixing, triggered by the presence of a reversed (rear to front) flow in the prefrontal environment, is the source of this phenomenon. From a vorticity budget analysis, it is found that the rear-to-front Row is less efficient in ''ventilating'' or ''removing'' vorticity generated at the leading edge of the gravity current. Therefore, the accumulation of vorticity leads to the development of enhanced eddy circulations that subsequently destroy the gravity current head. RP CHEN, CI (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MESOSCALE ATMOSPER PROC BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 18 TC 16 Z9 16 U1 2 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1995 VL 123 IS 11 BP 3240 EP 3253 DI 10.1175/1520-0493(1995)123<3240:NSOGCI>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TB867 UT WOS:A1995TB86700008 ER PT J AU CHANG, ATC CHIU, LS YANG, G AF CHANG, ATC CHIU, LS YANG, G TI DIURNAL CYCLE OF OCEANIC PRECIPITATION FROM SSM/I DATA SO MONTHLY WEATHER REVIEW LA English DT Note ID OUTGOING LONGWAVE RADIATION; CONVECTION; RAINFALL; RATES AB Four and a half years of the global monthly oceanic rain rates derived from the DMSP (Defense Meteorological Satellite Program) F-8 SSM/I (Special Sensor Microwave/Imager) data are used to study the diurnal cycles. Annual mean rainfall maps based on the SSM/I morning and evening observations are presented, and their differences are examined using a paired t test. The morning estimates are larger than the afternoon estimates by about 20% over the oceanic region between 50 degrees S and 50 degrees N, with significant differences located mainly along the intertropical convergence zone region, Using the measurements from two satellites, either DMSP F-g and F-10 or DMSP F-10 and F-11, amplitudes and phases of the 24-h harmonic are estimated. The diurnal cycle shows a nocturnal or early morning maximum in 35%-40% of the oceanic regions. Monte Carlo simulations show that the rms errors associated with the estimated amplitude and phase are about 100% and 2 h, respectively, mainly due to the large random errors (50%) associated with the present rainfall estimates and the nonoptimal separation times of the DMSP satellite sampling. C1 SAIC GEN SCI CORP,LAUREL,MD. RP CHANG, ATC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. NR 28 TC 56 Z9 58 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD NOV PY 1995 VL 123 IS 11 BP 3371 EP 3380 DI 10.1175/1520-0493(1995)123<3371:DCOOPF>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TB867 UT WOS:A1995TB86700017 ER PT J AU Parrott, TL Jones, MG AF Parrott, TL Jones, MG TI Parallel-element liner impedances for improved absorption of broadband sound in ducts SO NOISE CONTROL ENGINEERING JOURNAL LA English DT Article AB Zwikker and Kosten's theory for propagation of sound in channels was used to predict surface impedance and the spectra of sound absorption for parallel-element acoustical liners, Liner configurations ranged from lumped-element structures with thin acoustically resistive face sheets to ceramic honeycomb structures for which the sub-millimetre-diameter channels provided distributed resistance. Excellent agreement was observed between measured and predicted normal-incidence impedances for constant-depth and variable-depth ceramic-honeycomb structures, For single-degree-of-freedom, lumped-element absorbers, the experimentally observed increase in resistance at frequencies near anti-resonances was predicted, It has been unnecessary to include viscous dissipation near the cavity walls to adequately model the impedance well away from anti-resonance. Inclusion of cavity-wall dissipation allows prediction of the increased resistance at frequencies near anti-resonance. Prediction of this behavior in the region of anti-resonance frequencies may be a critical consideration if parallel elements are to be exploited for increased attenuation bandwidth. (C) 1995 Institute of Noise Control Engineering. RP Parrott, TL (reprint author), NASA,LANGLEY RES CTR,RES TECHNOL GRP,MS 463,2 N DRYDEN ST,HAMPTON,VA 23681, USA. NR 15 TC 5 Z9 5 U1 1 U2 3 PU INST NOISE CONTROL ENG PI POUGHKEEPSIE PA PO BOX 3206 ARLINGTON BRANCH, POUGHKEEPSIE, NY 12603 SN 0736-2501 J9 NOISE CONTROL ENG JI Noise Control Eng. J. PD NOV-DEC PY 1995 VL 43 IS 6 BP 183 EP 195 DI 10.3397/1.2828379 PG 13 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA TU231 UT WOS:A1995TU23100001 ER PT J AU SCHOLL, MS PADILLA, GP WANG, YW AF SCHOLL, MS PADILLA, GP WANG, YW TI DESIGN OF A HIGH-RESOLUTION TELESCOPE FOR AN IMAGING SENSOR TO CHARACTERIZE A (MARTIAN) LANDING SITE SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL REMOTE SENSING; IMAGE PROCESSING; HIGH-RESOLUTION IMAGING; LANDING-SITE CERTIFICATION; SURVEILLANCE AB The surveillance of large areas with high resolution is limited by the CCD technology, the readout electronics, and the data storage rate. An imaging concept that includes an optical camera and a survey strategy is proposed for remote landing-site certification. A I-m-diam telescope performs diffraction-limited imaging over its field of view, imaging an area of 0.25 x 0.25 m of the (Martian) surface on a 7 x 7-mu m pixel. With the sensor at 350 km above the 10 x 10-km site, this push-broom imaging configuration incorporates only five sensor passes over the site. The mission time is decreased by nearly 50% from the previously proposed concept for the site certification imaging. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SCHOLL, MS (reprint author), CTR INVEST OPT,APARTADO POSTAL 1-948,LEON 37000,GUANAJUATO,MEXICO. NR 8 TC 16 Z9 16 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD NOV PY 1995 VL 34 IS 11 BP 3222 EP 3228 PG 7 WC Optics SC Optics GA TF307 UT WOS:A1995TF30700019 ER PT J AU ANSARI, H ROBERTS, LH AF ANSARI, H ROBERTS, LH TI CHARGE-COUPLED-DEVICE IMAGING-SYSTEM FOR PRECISION BEAM-STEERING IN LASER COMMUNICATIONS SO OPTICAL ENGINEERING LA English DT Article DE CHARGE-COUPLED DEVICE CAMERAS; LASER POINTING; LASER COMMUNICATIONS AB A CCD imaging system has been developed for precision laser beam pointing. The system contains a high frame rate CCD camera operated in windowing mode under command of an embedded processor. A laser pointing and tracking update rate of 2 kHz has been achieved. C1 20 20 DESIGNS INC,LOS ALTOS,CA 94022. RP ANSARI, H (reprint author), CALTECH,JET PROP LAB,MAIL STOP 161-135,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 5 Z9 5 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD NOV PY 1995 VL 34 IS 11 BP 3261 EP 3264 DI 10.1117/12.212905 PG 4 WC Optics SC Optics GA TF307 UT WOS:A1995TF30700024 ER PT J AU JUDAY, RD AF JUDAY, RD TI LOG-POLAR DAPPLED TARGET SO OPTICS LETTERS LA English DT Article AB A new class of target for object identification and mask alignment is described. It has some fractal properties and is designed to be viewed by an optical correlator. RP JUDAY, RD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV AVION SYST,HOUSTON,TX 77058, USA. NR 2 TC 3 Z9 3 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD NOV 1 PY 1995 VL 20 IS 21 BP 2234 EP 2236 DI 10.1364/OL.20.002234 PG 3 WC Optics SC Optics GA TB355 UT WOS:A1995TB35500028 PM 19862308 ER PT J AU VAIDYANATHAN, R PADMANABHAN, A AF VAIDYANATHAN, R PADMANABHAN, A TI BUS-BASED NETWORKS FOR FAN-IN AND UNIFORM HYPERCUBE ALGORITHMS SO PARALLEL COMPUTING LA English DT Article DE PARALLEL PROCESSING; BUS-BASED NETWORKS; FAN-IN ALGORITHM; UNIFORM HYPERCUBE ALGORITHM; FAULT-TOLERANCE; COMMUNICATION ID ARCHITECTURES AB We consider the problem of running two large classes of algorithms (called ''fan-in'' and ''uniform hypercube algorithms'') on a synchronous parallel processing environment in which processors are connected by a multiple bus network (MEN). We present two MBNs, F and U, that run fan-in and uniform hypercube algorithms optimally. We also show that the MBN U is highly resilient to bus faults. This coupled with the fact that uniform hypercube algorithms require a rich set of interconnections and find use in a variety of applications, makes U useful as a general purpose interconnection structure. C1 WHEELING JESUIT COLL,NASA,CLASSROOM FUTURE PROGRAM,WHEELING,WV 26003. RP VAIDYANATHAN, R (reprint author), LOUISIANA STATE UNIV,DEPT ELECT & COMP ENGN,BATON ROUGE,LA 70803, USA. NR 10 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD NOV PY 1995 VL 21 IS 11 BP 1807 EP 1821 DI 10.1016/0167-8191(95)00044-5 PG 15 WC Computer Science, Theory & Methods SC Computer Science GA TK091 UT WOS:A1995TK09100005 ER PT J AU SHI, WT APFEL, RE HOLT, RG AF SHI, WT APFEL, RE HOLT, RG TI INSTABILITY OF A DEFORMED LIQUID-DROP IN AN ACOUSTIC FIELD SO PHYSICS OF FLUIDS LA English DT Article ID OSCILLATIONS; SHAPE; DEFORMATION; BREAKUP; DRIVEN AB The flattening and breakup of an axially symmetric liquid drop in an acoustic standing wave field in air have been studied using a boundary integral method. The interaction between the drop and sound field are crucial to this approach. Our computations are focused on the threshold beyond which the drop loses its static equilibrium, and on the dynamic behavior after it loses its equilibrium up to the point when it breaks up. The numerical results are given in terms of drop size and the strength of sound field and are found to be in good agreement with the measurements of others. (C) 1995 American Institute of Physics. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SHI, WT (reprint author), YALE UNIV,DEPT MECH ENGN,NEW HAVEN,CT 06520, USA. RI Holt, Ray/G-5677-2010 NR 25 TC 14 Z9 14 U1 0 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD NOV PY 1995 VL 7 IS 11 BP 2601 EP 2607 DI 10.1063/1.868708 PG 7 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA TB850 UT WOS:A1995TB85000009 ER PT J AU LAUNIUS, RD AF LAUNIUS, RD TI GLENNAN,T.KEITH - OBITUARY SO PHYSICS TODAY LA English DT Item About an Individual RP LAUNIUS, RD (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD NOV PY 1995 VL 48 IS 11 BP 108 EP & DI 10.1063/1.2808276 PG 0 WC Physics, Multidisciplinary SC Physics GA TC377 UT WOS:A1995TC37700023 ER PT J AU Johnston, JC McCann, RS Remington, RW AF Johnston, JC McCann, RS Remington, RW TI Chronometric evidence for two types of attention SO PSYCHOLOGICAL SCIENCE LA English DT Article ID DUAL-TASK; LOCUS; INTERFERENCE AB Parallel processing in the human brain is subject to severe attentional limits, but it is unclear whether such limits arise from a single attentional process or multiple distinct attentional processes. We provide new evidence that two candidates, input attention and central attention, operate at different temporal stages of processing. This conclusion is supported by chronometric analyses showing that the same reference stage (letter identification) operates after the stage at which input attention operates, but prior to the stage at which central attention operates. The finding that attention operates at different temporal loci provides new support for the existence of distinct attentional processes. RP Johnston, JC (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MS 262-2,MOFFETT FIELD,CA 94035, USA. NR 31 TC 114 Z9 115 U1 1 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD NOV PY 1995 VL 6 IS 6 BP 365 EP 369 DI 10.1111/j.1467-9280.1995.tb00527.x PG 5 WC Psychology, Multidisciplinary SC Psychology GA TL378 UT WOS:A1995TL37800007 ER PT J AU SIMON, T DRAKE, SA KIM, PD AF SIMON, T DRAKE, SA KIM, PD TI THE X-RAY-EMISSION OF A-TYPE STARS SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID ICCD SPECKLE OBSERVATIONS; SOLAR-TYPE STARS; CHROMOSPHERIC ACTIVITY; CONVECTION ZONES; BINARY STARS; MASS RATIOS; DWARF STARS; PLEIADES; CLUSTERS; SEARCH AB From X-ray images in the ROSAT public archives, we determine soft X-ray fluxes, or flux upper limits, for 74 A-type stars, which have been observed during deep integrations with the PSPC. Nine supposedly single, late-A stars (0.20100 ns. C1 YALE UNIV,AW WRIGHT NUCL STRUCT LAB,NEW HAVEN,CT 06511. UNIV CALIF LOS ANGELES,LOS ANGELES,CA. KEK,TSUKUBA,IBARAKI,JAPAN. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. WASEDA UNIV,TOKYO,JAPAN. UNIV TOKYO,TOKYO,JAPAN. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA. UNIV SPACE RES ASSOC,GSFC,GREENBELT,MD. COLUMBIA UNIV,NEVIS LAB,IRVINGTON,NY 10533. JOHNS HOPKINS UNIV,BALTIMORE,MD. RP BEAVIS, D (reprint author), BROOKHAVEN NATL LAB,UPTON,NY 11973, USA. RI Hayano, Ryugo/F-7889-2012; Kuo, Chaincy/H-9475-2016 OI Hayano, Ryugo/0000-0002-1214-7806; Kuo, Chaincy/0000-0001-7958-8764 NR 27 TC 35 Z9 35 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD OCT 23 PY 1995 VL 75 IS 17 BP 3078 EP 3081 DI 10.1103/PhysRevLett.75.3078 PG 4 WC Physics, Multidisciplinary SC Physics GA TB161 UT WOS:A1995TB16100013 ER PT J AU EAKER, CW SCHWENKE, DW AF EAKER, CW SCHWENKE, DW TI A FAST FOURIER-TRANSFORM METHOD FOR THE QUASI-CLASSICAL SELECTION OF INITIAL ROVIBRATIONAL STATES OF TRIATOMIC-MOLECULES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SEMICLASSICAL EIGENVALUES; TRAJECTORY METHOD; ENERGY-LEVELS; SYSTEMS; QUANTIZATION; H2O AB This paper describes the use of an exact fast Fourier transform method to prepare specified vibrational-rotational states of triatomic molecules. The method determines the Fourier coefficients needed to describe the coordinates and momenta of a vibrating-rotating triatomic molecule. Once the Fourier coefficients of a particular state are determined, it is possible to easily generate as many random sets of initial Cartesian coordinates and momenta as desired. All the members of each set will correspond to the particular vibrational-rotational state selected. For example, in the case of the ground vibrational state of a nonrotating water molecule, the calculated actions of 100 sets of initial conditions produced actions within 0.001HBAR of the specified quantization values and energies within 5 cm(-1) of the semiclassical eigenvalue. The numerical procedure is straightforward for states in which all the fundamental frequencies are independent. However, for states for which the fundamental frequencies become commensurate (resonance states), there are additional complications. In these cases it is necessary to determine a new set of ''fundamental'' frequencies and to modify the quantization conditions. Once these adjustments are made, good results are obtained for resonance states. The major problems are in labeling the large number of Fourier coefficients and the presence of regions of chaotic motion. Results are presented for the vibrational states of H2O and HCN and the rovibrational states of H2O. (C) 1995 American Institute of Physics. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP EAKER, CW (reprint author), UNIV DALLAS,DEPT CHEM,IRVING,TX 75062, USA. RI schwenke, david/I-3564-2013 NR 31 TC 6 Z9 6 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 22 PY 1995 VL 103 IS 16 BP 6984 EP 6992 DI 10.1063/1.470324 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA TA441 UT WOS:A1995TA44100016 ER PT J AU WALCH, SP AF WALCH, SP TI CHARACTERIZATION OF THE MINIMUM ENERGY PATHS FOR THE REACTIONS OF CH(X (2)PI) AND (CH2)-C-1 WITH C2H2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; ISOMERIZATION; FLAMES AB The reactions of CII((II)-I-2) and singlet methylene ((CH2)-C-1) with acetylene lead to intermediates which may be important in soot formation. CH((II)-I-2)+acetylene leads to CHCHCH (C3H3), CHCCH, CH2CC, and propargyl (CH2CCH). (CH2)-C-1+acetylene leads to cyclopropene, allene, and propyne. Except for CHCCH, which involves a barrier of 7.5 kcal/mol with respect to reactants, all of these reaction products are formed with no barrier. Miller and Melius have previously discussed the dimerization of propargyl to give benzene. C3H3 and CHCCH are shown to dimerize with no barrier to give benzene and para-benzyne, respectively. C3H3, CHCCH, and CH2CC can also add to smaller polycyclic aromatic hydrocarbons (PAH), and may be important species in forming larger PAH or fullerenes. (C) 1995 American Institute of Physics. RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 20 TC 45 Z9 46 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 OCT 22 PY 1995 VL 103 IS 16 BP 7064 EP 7071 DI 10.1063/1.470334 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA TA441 UT WOS:A1995TA44100026 ER PT J AU SCHUSTER, GL ANDREWS, JR AF SCHUSTER, GL ANDREWS, JR TI COHERENT BEAM COMBINING - OPTICAL LOSS EFFECTS ON POWER SCALING SO APPLIED OPTICS LA English DT Article ID AMPLIFIERS AB A model for a coherent array of amplifiers that has multiple stages and uses pairwise beam combining at the final stage has been developed. The model accounts for gain saturation of the individual amplifier elements, optical-coupling losses, and coherent-combining efficiency. The individual amplifier parameters are derived from experimental data. System size, efficiency, and output power are calculated as functions of optical-coupling efficiency and combining efficiency. Because of the exponential losses associated with pairwise beam combining, the coherent-combining losses are the dominant contribution to system efficiency reduction and increased system size. (C) 1995 Optical Society of America C1 XEROX CORP,WEBSTER RES CTR,WEBSTER,NY 14580. RP SCHUSTER, GL (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 420,HAMPTON,VA 23681, USA. NR 5 TC 16 Z9 16 U1 0 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 1995 VL 34 IS 30 BP 6801 EP 6805 PG 5 WC Optics SC Optics GA RZ268 UT WOS:A1995RZ26800001 PM 21060536 ER PT J AU HERRING, GC HILLARD, ME AF HERRING, GC HILLARD, ME TI EFFECT OF CROSSED BEAMS ON STOKES GAIN AND INTERACTION LENGTH IN STIMULATED RAMAN GAIN SPECTROSCOPY SO APPLIED OPTICS LA English DT Article ID GENERATION; BOXCARS; SIGNALS AB We have numerically calculated the change in spatial resolution and Stokes gain for stimulated Raman gain experiments that use two crossed laser beams. The laser beams are modeled as diffraction-limited, Gaussian TEM(00) beams. Results for interaction length and relative Stokes gain are presented for crossing angles of 0-15 degrees, focusingf/#'s 2-250, and mismatches in the positions of the focal points of the two beams. The numerical results for spatial resolution and gain are compared with geometric approximations that have been previously published. These numerical simulations show where the approximations are valid and also extend into regions where the approximations are invalid. (C) 1995 Optical Society of America RP HERRING, GC (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,HAMPTON,VA 23681, USA. NR 11 TC 3 Z9 3 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 1995 VL 34 IS 30 BP 6837 EP 6841 PG 5 WC Optics SC Optics GA RZ268 UT WOS:A1995RZ26800007 PM 21060542 ER PT J AU GROSS, MR MCGEE, TJ SINGH, UN KIMVILAKANI, P AF GROSS, MR MCGEE, TJ SINGH, UN KIMVILAKANI, P TI MEASUREMENTS OF STRATOSPHERIC AEROSOLS WITH A COMBINED ELASTIC RAMAN-BACKSCATTER LIDAR SO APPLIED OPTICS LA English DT Article DE AEROSOL-SCATTERING RATIO; BACKSCATTER AND EXTINCTION; ELASTIC-RAMAN-BACKSCATTER LIDAR ID PINATUBO AEROSOL; EXTINCTION; INVERSION; SYSTEM; CLOUD; OZONE; RATIO AB Improvements made to the NASA Goddard Space Flight Center Stratospheric Ozone Lidar system have extended its atmospheric-aerosol-measuring capabilities. The methods by which aerosol-scattering ratio, aerosol backscatter, and aerosol extinction are simultaneously derived from lidar data are reported, and results obtained during several intercomparison campaigns at worldwide locations are shown. The results track the evolution of the Mt. Pinatubo aerosol cloud from 1991 to 1994 and report wavelength-dependence information for aerosol backscatter between 308 and 351 nm. Two analysis techniques, a more common inversion method and a combined elastic-Raman-backscatter approach, are also compared. (C) 1995 Optical Society of America C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. IDEA CORP,BELTSVILLE,MD 20705. RP GROSS, MR (reprint author), HUGHES STX CORP,LANHAM,MD 20706, USA. RI McGee, Thomas/G-4951-2013 NR 33 TC 16 Z9 16 U1 0 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 OCT 20 PY 1995 VL 34 IS 30 BP 6915 EP 6924 PG 10 WC Optics SC Optics GA RZ268 UT WOS:A1995RZ26800018 PM 21060553 ER PT J AU WANG, MH GORDON, HR AF WANG, MH GORDON, HR TI ESTIMATION OF AEROSOL COLUMNAR SIZE DISTRIBUTION AND OPTICAL-THICKNESS FROM THE ANGULAR-DISTRIBUTION OF RADIANCE EXITING THE ATMOSPHERE - SIMULATIONS SO APPLIED OPTICS LA English DT Article ID COLOR AB We report the results of simulations in which an algorithm developed for estimation of aerosol optical properties from the angular distribution of radiance exiting the top of the atmosphere over the oceans [Appl. Opt. 33, 4042 (1994)] is combined with a technique for carrying out radiative transfer computations by synthesis of the radiance produced by individual components of the aerosol-size distribution [Appl. Opt. 33, 7088 (1994)], to estimate the aerosol-size distribution by retrieval of the total aerosol optical thickness and the mixing ratios for a set of candidate component aerosol-size distributions. The simulations suggest that in situations in which the true size-refractive-index distribution can actually be synthesized from a combination of the candidate components, excellent retrievals of the aerosol optical thickness and the component mixing ratios are possible. An exception is the presence of strongly absorbing aerosols. The angular distribution of radiance in a single spectral band does not appear to contain sufficient information to separate weakly from strongly absorbing aerosols. However, when two spectral bands are used in the algorithm, retrievals in the case of strongly absorbing aerosols are improved. When pseudodata were simulated with an aerosol-size distribution that differed in functional form from the candidate components, excellent retrievals were still obtained as long as the refractive indices of the actual aerosol model and the candidate components were similar. This underscores the importance of component candidates having realistic indices of refraction in the various size ranges for application of the method. The examples presented all focus on the multiangle imaging spectroradiometer; however, the results should be as valid for data obtained by the use of high-altitude airborne sensors. (C) 1995 Optical Society of America C1 UNIV MIAMI,DEPT PHYS,CORAL GABLES,FL 33124. RP WANG, MH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,RES & DATA SYST CORP,CODE 913,GREENBELT,MD 20771, USA. RI Wang, Menghua/F-5631-2010 OI Wang, Menghua/0000-0001-7019-3125 NR 16 TC 4 Z9 4 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 OCT 20 PY 1995 VL 34 IS 30 BP 6989 EP 7001 PG 13 WC Optics SC Optics GA RZ268 UT WOS:A1995RZ26800025 PM 21060560 ER PT J AU HOGE, FE VODACEK, A SWIFT, RN YUNGEL, JK BLOUGH, NV AF HOGE, FE VODACEK, A SWIFT, RN YUNGEL, JK BLOUGH, NV TI INHERENT OPTICAL-PROPERTIES OF THE OCEAN - RETRIEVAL OF THE ABSORPTION-COEFFICIENT OF CHROMOPHORIC DISSOLVED ORGANIC-MATTER FROM AIRBORNE LASER SPECTRAL FLUORESCENCE MEASUREMENTS SO APPLIED OPTICS LA English DT Article ID YELLOW SUBSTANCE; CHLOROPHYLL-A; WATER; CARBON AB The absorption coefficient of chromophoric dissolved organic matter (CDOM) at 355 nm has been retrieved from airborne laser-induced and water Raman-normalized CDOM fluorescence. Four combined airborne and ship field experiments have demonstrated that (1) the airborne CDOM fluorescence-to-water Raman ratio is linearly related to concurrent quinine-sulfate-standardized CDOM shipboard fluorescence measurements over a wide range of water masses (coastal to blue water); (2) the vicarious calibration of the airborne fluorosensor in units traceable to a fluorescence standard can be established and then maintained over an extended time period by tungsten lamp calibration; (3) the vicariously calibrated airborne CDOM fluorescence-to-water Raman ratio can be directly applied to previously developed shipboard fluorescence-to-absorption algorithms to retrieve CDOM absorption; and (4) the retrieval is not significantly affected by long-path multiple scattering, differences in attenuation at the excitation and emission wavelengths, or measurement in the 180 degrees backscatter configuration. Airborne CDOM absorption measurements will find immediate application to (a) forward and inverse modeling of oceanic water-leaving radiance and (b) validation of satellite-retrieved products such as CDOM absorption. C1 UNIV MARYLAND,DEPT CHEM & BIOCHEM,COLLEGE PK,MD 20742. EG&G WASHINGTON ANALYT SERV CTR INC,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. RP HOGE, FE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,WALLOPS ISL FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. RI Blough, Neil/B-7727-2009; Vodacek, Anthony/F-1585-2011 OI Vodacek, Anthony/0000-0001-9196-0928 NR 25 TC 34 Z9 35 U1 2 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 1995 VL 34 IS 30 BP 7032 EP 7038 PG 7 WC Optics SC Optics GA RZ268 UT WOS:A1995RZ26800029 PM 21060564 ER PT J AU BUOTE, DA TSAI, JC AF BUOTE, DA TSAI, JC TI OUANTIFYING THE MORPHOLOGIES AND DYNAMICAL EVOLUTION OF GALAXY CLUSTERS .1. THE METHOD SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERS, GENERAL; X-RAYS, GALAXIES ID NONROTATING STELLAR-SYSTEMS; SHELL-ORBIT MODELS; STABILITY AB We describe and test a method to quantitatively classify clusters of galaxies according to their projected morphologies. This method will be subsequently used to place constraints on cosmological parameters (Omega and the power spectrum of primordial fluctuations on scales at or slightly smaller than that of clusters) and to test theories of cluster formation. We specifically address structure that is easily discernible in projection and dynamically important to the cluster. The method is derived from the two-dimensional multipole expansion of the projected gravitational potential and yields dimensionless power ratios as morphological statistics. If the projected mass profile is used to characterize the cluster morphology, the power ratios are directly related to the cluster potential. However, since detailed mass profiles currently exist for only a few clusters, we use the X-ray-emitting gas as an alternative tracer of cluster morphology. In this case, the relation of the power ratios to the potential is qualitatively preserved. We demonstrate the feasibility of the method by analyzing simulated observations of simple models of X-ray clusters using the instrument parameters of the ROSAT PSPC. For illustrative purposes, we apply the method to ROSAT PSPC images of A85, A514, A1750, and A2029. These clusters, which differ substantially in their X-ray morphologies, are easily distinguished by their respective power ratios. We discuss the suitability of this method to address the connection between cluster morphology and cosmology and to assess whether an individual cluster is sufficiently relaxed for analysis of its intrinsic shape using hydrostatic methods. Approximately 50 X-ray observations of Abell clusters with the PSPC will be amenable to morphological analysis using the method of this paper. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. MIT, SPACE RES CTR, CAMBRIDGE, MA 02139 USA. RP BUOTE, DA (reprint author), MIT, DEPT PHYS, 77 MASSACHUSETTS AVE, CAMBRIDGE, MA 02139 USA. NR 34 TC 100 Z9 100 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP 522 EP 537 DI 10.1086/176326 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY932 UT WOS:A1995RY93200006 ER PT J AU SNOWDEN, SL PIETSCH, W AF SNOWDEN, SL PIETSCH, W TI DIFFUSE-X-RAY EMISSION FROM M101 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M101); GALAXIES, ISM; GALAXIES, STRUCTURE; GALAXY, HALO; X-RAYS, GALAXIES ID INTERSTELLAR-MEDIUM; GALAXY M-101; ROSAT PSPC; H-I; CLOUD; DISK; DISTANCE; LIMITS; SHADOW AB The ROSAT PSPC observation of the face-on spiral galaxy M101 shows conclusive evidence for diffuse X-ray emission. While the emission is strongest in the 1/4 keV band (sensitive to thermal emission near 10(6) K), it is also apparent at 3/4 keV (sensitive to thermal emission at a few 10(6) K). The emission is clearly visible over the inner 7' radius (similar to 15 kpc with a distance to M101 of 7.2 Mpc), or roughly 60% of the D-25 radius. In addition to the emission, a thick spiral arm at roughly an 8' radius in the southwest quadrant is correlated with a depression in surface brightness relative to the region of the observation external to the galaxy. The depression is consistent with the absorption of the entire previously observed extragalactic background at 1/4 keV. The observed 1/4 keV band intensity of M101 varies over the inner 7' of the galaxy with an average value of similar to 790 x 10(-6) counts s(-1) arcmin(-2) and is peaked toward the center of the galaxy. The R2/R1 band ratio implies an emission temperature of similar to 10(5.8) K. After correction for absorption by material associated with Milky Way H I, this implies an intensity of similar to 3280 x 10(-6) counts s(-1) arcmin(-2). This emission most likely originates in the halo of M101 (similar to the 1/4 keV emission detected by ROSAT in NGC 253). If so, it would require an average filling factor of similar to 1 of regions similar to the bright 1/4 keV halo emission observed in our own Galaxy in the direction of Draco. The emission is unlikely to originate in confined regions in the disk of M101, similar to the Local Hot Bubble (T similar to 10(6) K, similar to 1.5 x 10(20) cm(-2) overburden of H I), since the required filling factor of such regions would be much greater than unity and the implied emission temperature would be relatively low (similar to 10(5.5) K). Compared to the Milky Way, either intrinsically brighter but cooler regions or a highly clumped interstellar medium (ISM), or both, would be required if the emission originates in the disk. This detection of extensive diffuse X-ray emission from the halo of a galaxy similar to the Milky Way has implications for our own Galaxy, as well as for M101 itself. By analogy, it implies that the X-ray halo that we observe in the Milky Way has a low filling factor outside the Galactic center region. This is consistent with the apparent patchiness in the solar vicinity. C1 MAX PLANCK INST EXTRATERR PHYS, D-85740 GARCHING, GERMANY. RP SNOWDEN, SL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, USRA, GREENBELT, MD 20771 USA. RI Snowden, Steven/D-5292-2012 NR 47 TC 43 Z9 43 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP 627 EP + DI 10.1086/176335 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY932 UT WOS:A1995RY93200015 ER PT J AU BURROWS, CJ KRIST, J HESTER, JJ SAHAI, R TRAUGER, JT STAPELFELDT, KR GALLAGHER, JS BALLESTER, GE CASERTANO, S CLARKE, JT CRISP, D EVANS, RW GRIFFITHS, RE HOESSEL, JG HOLTZMAN, JA MOULD, JR SCOWEN, PA WATSON, AM WESTPHAL, JA AF BURROWS, CJ KRIST, J HESTER, JJ SAHAI, R TRAUGER, JT STAPELFELDT, KR GALLAGHER, JS BALLESTER, GE CASERTANO, S CLARKE, JT CRISP, D EVANS, RW GRIFFITHS, RE HOESSEL, JG HOLTZMAN, JA MOULD, JR SCOWEN, PA WATSON, AM WESTPHAL, JA TI HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF THE SN 1987A TRIPLE RING NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, BUBBLES; ISM, JETS AND OUTFLOWS; SHOCK WAVES; STARS, MASS LOSS; SUPERNOVAE, INDIVIDUAL (SN 1987A) ID LARGE MAGELLANIC CLOUD; PLANETARY-NEBULAE; SUPERNOVA 1987-A; EMISSION-LINES; LIGHT ECHOES; NAPOLEON HAT; SN-1987A; PROGENITOR; DISCOVERY AB We have observed SN 1987A with the optically corrected WFPC2 on the Hubble Space Telescope both in emission lines and in the UV and optical continuum. The previously observed outer nebular structure is shown to be part of two closed unresolved loops. These loops were flash-ionized by the supernova itself. They are not caused by limb brightening of an hourglass shell produced by the interaction of the winds from the progenitor. The inner ring is seen to be extended and may be connected to the new outer rings by sheets of material. However, beyond the outer rings, emission is not seen, implying a very low density (n < 10) for the outer hourglass shell if it exists. The new outer rings are unresolved, and this together with their observed brightness implies a density n > 1000. This density contrast of at least 100 is difficult to reconcile with the conventional picture of the progenitor evolution. Two models for the rings are presented, but each is deficient in important respects. A proper understanding of this system will require new physical insight. C1 ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MICHIGAN,DEPT ATMOSPHER & OCEAN SCI,ANN ARBOR,MI 48109. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. LOWELL OBSERV,FLAGSTAFF,AZ 86001. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP BURROWS, CJ (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 30 TC 136 Z9 136 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP 680 EP & DI 10.1086/176339 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY932 UT WOS:A1995RY93200019 ER PT J AU LAI, D BILDSTEN, L KASPI, VM AF LAI, D BILDSTEN, L KASPI, VM TI SPIN-ORBIT INTERACTION IN NEUTRON STAR/MAIN-SEQUENCE BINARIES AND IMPLICATIONS FOR PULSAR TIMING SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; PULSARS, INDIVIDUAL (PSR J0045-7319, PSR B1259-63); STARS, NEUTRON; STARS, OSCILLATIONS; STARS, ROTATION ID PSR 1913+16; TIDAL CAPTURE AB The spin-induced quadrupole moment of a rapidly rotating star changes the orbital dynamics in a binary system, giving rise to advance (or regression) of periastron and precession of the orbital plane. We show that these effects are important in the recently discovered radio pulsar/main-sequence star binary system PSR J0045-7319 and reliably account for the observed peculiar timing residuals. Precise measurements of the apsidal motion and orbital plane precession can yield valuable information on the internal structure and rotation of the star. The detection of orbital precession implies that the spin of the companion star is not aligned with the orbital angular momentum and suggests that the supernova gave the pulsar a kick out of the original orbital plane. Tidal excitation of g-mode oscillations in the PSR J0045-7319 system induces an orbital period change of order \Delta P-orb/P-orb\ similar to 10(-6) at each periastron passage, but the secular trend depends on the radiative damping time of the g-modes. We also discuss the spin-orbit coupling effects for the accreting X-ray pulsars and the other known radio pulsar/mainsequence binary, PSR B1259-63. C1 UNIV CALIF BERKELEY, DEPT PHYS, BERKELEY, CA 94720 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. RP LAI, D (reprint author), CALTECH, JET PROP LAB, IPAC, PASADENA, CA 91125 USA. NR 31 TC 57 Z9 57 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP 819 EP 824 DI 10.1086/176350 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY932 UT WOS:A1995RY93200030 ER PT J AU MILLER, JA ROBERTS, DA AF MILLER, JA ROBERTS, DA TI STOCHASTIC PROTON ACCELERATION BY CASCADING ALFVEN WAVES IN IMPULSIVE SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; PLASMAS; SUN, CORONA; SUN, FLARES; SUN, PARTICLE EMISSION ID GAMMA-RAY EMISSION; PARTICLE-ACCELERATION; MAGNETOHYDRODYNAMIC TURBULENCE; IONIZATION EQUILIBRIUM; ELECTRON ACCELERATION; MAGNETIC LOOPS; COSMIC-RAYS; BETA-PLASMA; TRANSPORT; WIND AB We present a model for the acceleration of protons from thermal to relativistic energies on impulsive flare timescales. Long-wavelength Alfven waves are assumed to be generated during the initial flare energy release by, for example, large-scale restructuring of the magnetic field. These waves nonlinearly cascade to high wavenumbers and eventually reach the dissipation range, whereupon they are damped by protons in the tail of the thermal distribution through gyroresonant interactions. The protons, in turn, are energized out the tail and, since longer wavelength waves are already present in the wave spectrum, are promptly accelerated to substantially higher energies. We find that for turbulence energy densities much smaller than the ambient magnetic field energy density and near the lower limit of that required by the total observed energy content of the protons, the acceleration of a sufficient number of protons to gamma-ray line-producing energies occurs on observed timescales essentially independent of the scale at which the waves are generated. Simple scaling arguments are presented in support of, and supported by, detailed numerical results. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP MILLER, JA (reprint author), UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. RI Roberts, Dana/D-4625-2012 NR 69 TC 115 Z9 120 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP 912 EP 932 DI 10.1086/176359 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY932 UT WOS:A1995RY93200039 ER PT J AU LESKE, RA CUMMINGS, JR MEWALDT, RA STONE, EC VONROSENVINGE, TT AF LESKE, RA CUMMINGS, JR MEWALDT, RA STONE, EC VONROSENVINGE, TT TI MEASUREMENTS OF THE IONIC CHARGE STATES OF SOLAR ENERGETIC PARTICLES USING THE GEOMAGNETIC-FIELD SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, FLARES ID EQUILIBRIUM; ABUNDANCES; PLASMA; FLARES AB The mean charge states of C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, and Ni ions with similar to 15-70 MeV nucleon(-1) in the two large solar energetic particle (SEP) events of 1992 October 30 and November 2 have been determined using measurements of the invariant latitude of the cosmic-ray cutoffs of these elements from the Mass Spectrometer Telescope on the polar-orbiting SAMPEX satellite. The deduced charge state values are in good agreement with the mean values measured directly in previous SEP events at much lower energies of similar to 1 MeV nucleon(-1). The inferred equilibrium source temperatures are confirmed to be typically 2 x 10(6) K, which provides additional evidence that SEPs in gradual-type events are accelerated coronal material. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LESKE, RA (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 26 TC 73 Z9 73 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 1995 VL 452 IS 2 BP L149 EP L152 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY935 UT WOS:A1995RY93500017 ER PT J AU NEMIROFF, RJ GOULD, A AF NEMIROFF, RJ GOULD, A TI PROBING FOR MACHOS OF MASS 10-(15) M(CIRCLE-DOT) TO 10(-7) M(CIRCLE-DOT) WITH GAMMA-RAY BURST PARALLAX SPACECRAFT SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GRAVITATIONAL LENSING ID LENS AB Two spacecraft separated by approximately 1 AU and equipped with gamma-ray burst (GRB) detectors could detect or rule out a cosmological density of massive compact halo objects (MACHOs) in the mass range 10(-15) M. less than or similar to M less than or similar to 10(-7) M., provided that GRBs prove to be cosmological. Previously devised methods for detecting MACHOs have spanned the mass range 10(-16) M. less than or similar to M less than or similar to 10(7) M., but with a gap of several orders of magnitude near 10(-9) M.. For MACHOs and sources both at a cosmological distance, the Einstein radius is approximately 1 AU(M/10(-7) M.)(1/2). Hence, if a GRB lies within the Einstein ring of a MACHO of mass M less than or similar to 10(-7) M. as seen by one detector, it will not lie in the Einstein ring as seen by a second detector approximately 1 AU away. This implies that if GRBs are measured to have significantly different fluxes by the two detectors, this would signal the presence of a MACHO less than or similar to 10(-7) M.. By the same token, if the two detectors measured similar fluxes for several hundred events, a cosmological abundance of such low-mass MACHOs would be ruled out. The lower limit is set by the time resolution t(res) of the detectors: M less than or similar to 10(-15) M. corresponds to t(res) less than or similar to 10(-2) s. If low-mass MACHOs are detected, there are tests that can discriminate among events generated by MACHOs in the three mass ranges M less than or similar to 10(-12) M., 10(-12) M. less than or similar to M less than or similar to 10(-7) M., and M greater than or similar to 10(-7) M.. Further experiments would then be required to make more accurate mass measurements. C1 OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 27 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 OCT 20 PY 1995 VL 452 IS 2 BP L111 EP L114 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY935 UT WOS:A1995RY93500008 ER PT J AU PARMAR, AN ANGELINI, L WHITE, NE AF PARMAR, AN ANGELINI, L WHITE, NE TI PERIODIC OUTBURSTS FROM THE ULTRASOFT X-RAY TRANSIENT 4U-1630-47 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; STARS, INDIVIDUAL (4U 1630-47); X-RAYS, STARS ID EVOLUTION; MODEL AB Using ROSAT PSPC and Einstein solid state spectrometer and monitor proportional counter archival data, we have found two previously unreported outbursts from the ultrasoft X-ray transient 4U 1630-47 that occurred in 1979 March and 1992 September. The times of these outbursts are consistent with a previously reported, approximately 600 day outburst recurrence period, as is the subsequent nondetection of the source by ROSAT in 1993 March and August. Future outbursts are predicted to occur in 1995 November and 1997 June. The object 4U 1630-47 is a member of the class of transient X-ray binary systems that are thought to contain black holes. The 601.7 +/- 3.0 day recurrence period of 4U 1630-47 is by far the shortest known for this class. The origin and possible triggers for the outbursts are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP PARMAR, AN (reprint author), EUROPEAN SPACE AGCY,DEPT SPACE SCI,DIV ASTROPHYS,2200 AG NOORDWIJK,NETHERLANDS. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 28 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 OCT 20 PY 1995 VL 452 IS 2 BP L129 EP L132 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY935 UT WOS:A1995RY93500012 ER PT J AU DEFRIES, RS FIELD, CB FUNG, I JUSTICE, CO LOS, S MATSON, PA MATTHEWS, E MOONEY, HA POTTER, CS PRENTICE, K SELLERS, PJ TOWNSHEND, JRG TUCKER, CJ USTIN, SL VITOUSEK, PM AF DEFRIES, RS FIELD, CB FUNG, I JUSTICE, CO LOS, S MATSON, PA MATTHEWS, E MOONEY, HA POTTER, CS PRENTICE, K SELLERS, PJ TOWNSHEND, JRG TUCKER, CJ USTIN, SL VITOUSEK, PM TI MAPPING THE LAND-SURFACE FOR GLOBAL ATMOSPHERE-BIOSPHERE MODELS - TOWARD CONTINUOUS DISTRIBUTIONS OF VEGETATIONS FUNCTIONAL-PROPERTIES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID SATELLITE DATA; CANOPY REFLECTANCE; CARBON-DIOXIDE; COVER CLASSIFICATION; SENSITIVITY ANALYSIS; BIOMASS PRODUCTION; SOLAR-RADIATION; UNITED-STATES; CLIMATE; PHOTOSYNTHESIS AB Global land surface characteristics are important boundary conditions for global models that describe exchanges of water, energy, and carbon dioxide between the atmosphere and biosphere. Existing data sets of global land cover are based on classification schemes that characterize each grid cell as a discrete vegetation type. Consequently, parameter fields derived from these data sets are dependent on the particular scheme and the number of vegetation types it includes. The functional controls on exchanges of water energy, and carbon dioxide between the atmosphere and biosphere are now well enough understood that it is increasingly feasible to model these exchanges using a small number. of vegetation characteristics that either are related to or closely related to the functional controls. Ideally, these characteristics would be mapped as continuous distributions to capture mixtures and gradients in vegetation within the cell size of the model. While such an approach makes it more difficult to build models from detailed observations at a small number of sites, it increases the potential for capturing functionally important variation within, as well as between, vegetation types. Globally, the vegetation characteristics that appear to be most important in controlling fluxes of water, energy, and carbon dioxide include (1) growth form (tree, shrub, herb), (2) seasonality of woody vegetation (deciduous, evergreen), (3) leaf type (broadleaf, coniferous), (4) photosynthetic pathway of nonwoody vegetation (C-3, C-4,), (5) longevity (annual, perennial), and (6) type and intensity of disturbance (e.g., cultivation, fire history). Many of these characteristics can be obtained through remote sensing, though some require ground-based information. The minimum number and the identity of the required land surface characteristics almost certainly vary with the intended objective, but the philosophy of driving models with continuous distributions of a small number of land surface characteristics is likely to be applicable to a broad range of problems. C1 CARNEGIE INST, DEPT PLANT BIOL, STANFORD, CA 94305 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. UNIV VICTORIA, SCH EARTH & OCEAN SCI, VICTORIA, BC V8W 2Y2, CANADA. NASA, GODDARD SPACE FLIGHT CTR, SCI SYST & APPLICAT INC, GREENBELT, MD 20771 USA. UNIV CALIF BERKELEY, DEPT SOIL SCI, BERKELEY, CA 94720 USA. STANFORD UNIV, DEPT BIOL SCI, STANFORD, CA 94305 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NASA, GODDARD SPACE FLIGHT CTR, BIOSPHER SCI BRANCH, GREENBELT, MD 20771 USA. UNIV CALIF DAVIS, DEPT LAND AIR & WATER RESOURCES, DAVIS, CA 95616 USA. RP UNIV MARYLAND, DEPT GEOG, 1113 LEFRAK HALL, COLLEGE PK, MD 20742 USA. RI Los, Sietse/G-8985-2012 NR 111 TC 103 Z9 115 U1 3 U2 20 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 OCT 20 PY 1995 VL 100 IS D10 BP 20867 EP 20882 DI 10.1029/95JD01536 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TD507 UT WOS:A1995TD50700007 ER PT J AU FOLKINS, IA WEINHEIMER, AJ RIDLEY, BA WALEGA, JG ANDERSON, B COLLINS, JE SACHSE, G PUESCHEL, RF BLAKE, DR AF FOLKINS, IA WEINHEIMER, AJ RIDLEY, BA WALEGA, JG ANDERSON, B COLLINS, JE SACHSE, G PUESCHEL, RF BLAKE, DR TI O-3, NOY, AND NOX/NOY IN THE UPPER TROPOSPHERE OF THE EQUATORIAL PACIFIC SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIRBORNE MEASUREMENTS; PEROXYACETYL NITRATE; BOUNDARY-LAYER; NITRIC-OXIDE; OZONE; NITROGEN; DISTRIBUTIONS; SIMULATION; AEROSOLS; EASTERN AB Two of the DC-8 flights during the 1991-1992 second Airborne Arctic Stratospheric Expedition (AASE 2) were between California and Tahiti. Extremely abrupt changes in O-3 and NOy were observed on both flights as the aircraft crossed the subtropical jet. They indicate that the width of the transition from midlatitude to tropical air in the troposphere can be as short as 1 km. The NOy/O-3 ratio was remarkably stable across the transition. We discuss some of the dynamical features associated with the transitions and speculate on the reasons for their abruptness. They occurred south of the subtropical frontal zone and were accompanied by changes in humidity, NOx/NOy, and modest changes in CO, CH4, and CO2. In addition, a chemical model constrained by measurements of the long-lived species is used to simulate the variation of NOx/NOy along the two flight tracks. Although this model is quite successful at simulating observed NOx/NOy in midlatitude air, it drastically overestimates NOx/NOy in tropical air. The rate at which the model converts NOx to HNO3 via the NO2 + OK reaction is very slow in the upper tropical troposphere because the low O-3 concentrations and cold temperatures force most of the NO, to be in the form of NO during the day. We argue that there is an important NO to NO2 pathway in this region not presently included in models, that much of the NOy is in a stable (possibly aerosol) form that is not readily converted to NOx, or that there has been insufficient time since convection for NOx to be released from other more stable forms of NOy. It is important to resolve this discrepancy because present models which have the correct O-3 and NO, may overestimate O-3 production rates and OH concentrations in the upper tropical troposphere. C1 DALHOUSIE UNIV, DEPT PHYS, HALIFAX, NS B3H 4J1, CANADA. NATL CTR ATMOSPHER RES, DIV ATMOSPHER CHEM, BOULDER, CO 80307 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV CALIF IRVINE, DEPT CHEM, IRVINE, CA 92717 USA. SCI & TECHNOL CORP, HAMPTON, VA 23681 USA. RP FOLKINS, IA (reprint author), DALHOUSIE UNIV, DEPT OCEANOG, ATMOSPHER SCI PROGRAM, HALIFAX, NS B3H 4J1, CANADA. NR 32 TC 14 Z9 14 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 OCT 20 PY 1995 VL 100 IS D10 BP 20913 EP 20926 DI 10.1029/95JD01637 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TD507 UT WOS:A1995TD50700010 ER PT J AU REINER, MJ FAINBERG, J STONE, RG AF REINER, MJ FAINBERG, J STONE, RG TI LARGE-SCALE INTERPLANETARY MAGNETIC-FIELD CONFIGURATION REVEALED BY SOLAR RADIO-BURSTS SO SCIENCE LA English DT Article ID MODEL INTERPRETATION; WIND SPEED; EMISSION; SPACE AB An instantaneous view of the interplanetary extension of the solar magnetic field is provided here by measurements from a space platform at high ecliptic latitudes of the trajectories of individual type III solar radio bursts. The Ulysses spacecraft provides this unique vantage point with an orbit taking it far from the ecliptic plane. The Ulysses radio measurements illustrate the capability of detecting and tracking coronal disturbances as they propagate through the interplanetary medium. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REINER, MJ (reprint author), HUGHES STX,LANHAM,MD 20706, USA. NR 26 TC 20 Z9 20 U1 0 U2 0 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 20 PY 1995 VL 270 IS 5235 BP 461 EP 464 DI 10.1126/science.270.5235.461 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA TA374 UT WOS:A1995TA37400039 ER PT J AU SIKIVIE, P TKACHEV, II WANG, Y AF SIKIVIE, P TKACHEV, II WANG, Y TI VELOCITY PEAKS IN THE COLD DARK-MATTER SPECTRUM ON EARTH SO PHYSICAL REVIEW LETTERS LA English DT Article ID SECONDARY INFALL; INVISIBLE-AXION; COSMIC AXIONS; UNIVERSE; HALOS; EVOLUTION AB The cold dark matter spectrum on Earth is expected to have peaks in velocity space. We obtain estimates for the sizes and locations of these peaks using a generalization of the secondary infall model of galactic halo formation, which takes account of the angular momentum of the dark matter particles. The dependence of the spectrum of velocity peaks upon cosmological parameters is studied. Our results are relevant to direct dark matter search experiments. C1 UNIV CALIF SANTA BARBARA, INST THEORET PHYS, SANTA BARBARA, CA 93106 USA. FERMILAB NATL ACCELERATOR LAB, NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. RUSSIAN ACAD SCI, INST NUCL RES, MOSCOW 117312, RUSSIA. RP SIKIVIE, P (reprint author), UNIV FLORIDA, DEPT PHYS, GAINESVILLE, FL 32611 USA. RI Wang, Yun/B-5724-2011 OI Wang, Yun/0000-0002-4749-2984 NR 25 TC 94 Z9 94 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD OCT 16 PY 1995 VL 75 IS 16 BP 2911 EP 2915 DI 10.1103/PhysRevLett.75.2911 PG 5 WC Physics, Multidisciplinary SC Physics GA RZ341 UT WOS:A1995RZ34100001 ER PT J AU HAN, D KIM, YS NOZ, ME AF HAN, D KIM, YS NOZ, ME TI WAVELETS, WINDOWS, AND PHOTONS SO PHYSICS LETTERS A LA English DT Article ID SINGLE-PHOTON; LIGHT WAVES; INTERFERENCE AB Within the wavelet framework, it is shown that it is possible to construct a Lorentz-covariant superposition of light waves. The concept of window allows the definition of a ''finite difference'' between wavelets and photons. It is pointed out that a windowed function is as accurate as any continuous function which may be constructed from a discrete set of experimental data. C1 UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742. NYU,DEPT RADIOL,NEW YORK,NY 10016. RP HAN, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 910 1,GREENBELT,MD 20771, USA. NR 17 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9601 J9 PHYS LETT A JI Phys. Lett. A PD OCT 16 PY 1995 VL 206 IS 5-6 BP 299 EP 304 DI 10.1016/0375-9601(95)00634-F PG 6 WC Physics, Multidisciplinary SC Physics GA RZ468 UT WOS:A1995RZ46800005 ER PT J AU FRANK, LA PATERSON, WR KOKUBUN, S YAMAMOTO, T LEPPING, RP AF FRANK, LA PATERSON, WR KOKUBUN, S YAMAMOTO, T LEPPING, RP TI DIRECT-DETECTION OF THE CURRENT IN A MAGNETOTAIL FLUX ROPE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PLASMOIDS; CDAW-8 AB The field-aligned current densities in the core of a magnetotail flux rope were directly detected with plasma instrumentation on board the Geotail spacecraft at a downstream distance of about 96 R(E) (Earth radii). The axis of the flux rope and the core magnetic fields were directed cross-tail, and the magnitudes of these core magnetic fields were similar to that in the magnetotail lobe at these distances. The radius of the core cross-section was about 0.7 R(E), and the total current was 500,000 A. Together with a recently reported, similar measurement with the Galileo spacecraft these direct detections of current greatly strengthen the previous identifications in favor of flux ropes that were solely based on their magnetic signatures. The detection of the flux rope with the Geotail spacecraft occurred during a period of relative magnetic quiescence. C1 NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA,AICHI 442,JAPAN. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP FRANK, LA (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,VAN ALLEN HALL,IOWA CITY,IA 52242, USA. RI Paterson, William/F-5684-2012 NR 20 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 1995 VL 22 IS 20 BP 2697 EP 2700 DI 10.1029/95GL02002 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TA643 UT WOS:A1995TA64300005 ER PT J AU BOERING, KA HINTSA, EJ WOFSY, SC ANDERSON, JG DAUBE, BC DESSLER, AE LOEWENSTEIN, M MCCORMICK, MP PODOLSKE, JR WEINSTOCK, EM YUE, GK AF BOERING, KA HINTSA, EJ WOFSY, SC ANDERSON, JG DAUBE, BC DESSLER, AE LOEWENSTEIN, M MCCORMICK, MP PODOLSKE, JR WEINSTOCK, EM YUE, GK TI MEASUREMENTS OF STRATOSPHERIC CARBON-DIOXIDE AND WATER-VAPOR AT NORTHERN MIDLATITUDES - IMPLICATIONS FOR TROPOSPHERE-TO-STRATOSPHERE TRANSPORT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER TROPICAL STRATOSPHERE; CONSTITUENTS; DEHYDRATION; SIMULATIONS; AIR AB Simultaneous in situ measurements of CO2 and water vapor in the lower stratosphere were obtained in November 1992 and May 1993 up to 21 km at midlatitudes. Seasonal changes in both species were observed up to pressure-altitudes of 19 km (similar to 440K), a result of vertical propagation of seasonal oscillations in CO2 and H2O mixing ratios for air entering the stratosphere in the tropics followed by horizontal transport to midlatitudes. The inferred phase difference between their seasonal cycles at the tropical tropopause (2 months) remained coherent at midlatitudes, although the amplitudes were reduced, implying a mean transport time of 4-6 months from the tropical tropopause (similar to 16 km) to similar to 18.5-19 km at midlatitudes in both November and May. The measurements indicate that air enters the stratosphere throughout the year and suggest that vertical propagation of the seasonal minimum in water vapor, rather than deep convective overshoot, is both sufficient and necessary to explain the minimum in water (''hygropause'') observed several kilometers above the tropopause. C1 HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. HARVARD UNIV,DEPT CHEM,ATMOSPHER RES PROJECT,CAMBRIDGE,MA 02138. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP BOERING, KA (reprint author), HARVARD UNIV,DIV APPL SCI,29 OXFORD ST,CAMBRIDGE,MA 02138, USA. RI Dessler, Andrew/G-8852-2012 OI Dessler, Andrew/0000-0003-3939-4820 NR 32 TC 38 Z9 38 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 OCT 15 PY 1995 VL 22 IS 20 BP 2737 EP 2740 DI 10.1029/95GL02337 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TA643 UT WOS:A1995TA64300015 ER PT J AU KUMAR, P AF KUMAR, P TI A WAVELET-BASED METHODOLOGY FOR SCALE-SPACE ANISOTROPIC ANALYSIS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB It is well known that several geophysical fields exhibit characteristic features at different scales. For some such fields scale-space anisotropy is also present, that is, features contributing significant fraction of energy are oriented in different directions at different scales. Examples of such fields include clouds, rainfall, hurricanes etc. A technique based on wavelet transforms (with two-dimensional directionally oriented Morlet wavelet) is developed to analyze such random fields. This methodology has significant advantage over Fourier transform based techniques and is demonstrated using the analysis of a spatial rainfall field. RP KUMAR, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,UNIV SPACE RES ASSOC,CODE 974,GREENBELT,MD 20771, USA. RI Kumar, Praveen/D-2036-2010 OI Kumar, Praveen/0000-0002-4787-0308 NR 7 TC 18 Z9 18 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 1995 VL 22 IS 20 BP 2777 EP 2780 DI 10.1029/95GL02934 PG 4 WC Geosciences, Multidisciplinary SC Geology GA TA643 UT WOS:A1995TA64300025 ER PT J AU CORRAL, R JIMENEZ, J AF CORRAL, R JIMENEZ, J TI FOURIER/CHEBYSHEV METHODS FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS IN INFINITE DOMAINS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NUMERICAL-SIMULATION; TURBULENCE; TRANSITION; LAYER; FLOW AB A fully spectral numerical scheme is presented for the unsteady, high Reynolds number, incompressible Navier-Stokes equations, in domains which are infinite or semi-infinite in one dimension. The domain is not mapped, and standard Fourier or Chebyshev expansions can be used. The handling of the infinite domain does not introduce any significant overhead. The scheme assumes that the vorticity in the flow is essentially concentrated in a finite region, which is represented numerically by standard spectral collocation methods, To accommodate the slow exponential decay of the velocities at infinity, extra expansion functions are introduced, which are handled analytically. A detailed error analysis is presented, and two applications to direct numerical simulation of turbulent flows are discussed in relation with the numerical performance of the scheme. (C) 1995 Academic Press, Inc. C1 NASA,AMES RES CTR,AMES,IA. STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. RP CORRAL, R (reprint author), UNIV POLITECN MADRID,SCH AERONAUT,PL CARDENAL CISNEROS 3,E-28040 MADRID,SPAIN. RI jimenez, javier/A-6691-2008 OI jimenez, javier/0000-0003-0755-843X NR 13 TC 13 Z9 13 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT 15 PY 1995 VL 121 IS 2 BP 261 EP 270 DI 10.1016/S0021-9991(95)90085-3 PG 10 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA RZ315 UT WOS:A1995RZ31500005 ER PT J AU STERN, HL ROTHROCK, DA KWOK, R AF STERN, HL ROTHROCK, DA KWOK, R TI OPEN WATER PRODUCTION IN ARCTIC SEA-ICE - SATELLITE MEASUREMENTS AND MODEL PARAMETERIZATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SYNTHETIC APERTURE RADAR; PACK ICE; MOTION AB Sequential synthetic aperture radar (SAR) images from the ERS 1 spacecraft were routinely used as input to the Geophysical Processor System at the Alaska SAR Facility from 1992 through 1994 to produce sea ice displacement vectors on a 5-km grid. We have combined some 5000 of these products, consisting of nearly 700,000 displacement vectors, into a set of 914 strips or mosaics of ice motion that span (mostly) 3-day intervals, For each strip we compute the opening and closing of leads based on the change in area of the 5-km grid cells. We also compute the area-averaged deformation or strain invariants of the motion. The small-scale (several kilometer) lead activity can be parameterized fairly well in terms of the large-scale (several hundred kilometer) strain invariants. Sea ice models implicitly contain such a parameterization through their constitutive equations. The well-known model of Hibler (1979) that uses a viscous-plastic theology and an elliptical yield curve is in good agreement with our data. The variance in the data about this theoretical relationship is less than that suggested by a random model of sea ice motion. The data also indicate that shearing deformation contributes to the opening and closing of leads, Models with two categories or levels of ice thickness generally do not take shearing deformation into account in the evolution of the ice concentration, nor do they redistribute ice as a result of ridging. We show how to add these features to two-level models. However, we argue that three-level models consisting of open water, thin ice, and thick ice are much better suited to the proper treatment of open water production, and we present such a model. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP STERN, HL (reprint author), UNIV WASHINGTON,CTR POLAR SCI,1013 NE 40TH ST,SEATTLE,WA 98105, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 20 TC 55 Z9 56 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 1995 VL 100 IS C10 BP 20601 EP 20612 DI 10.1029/95JC02306 PG 12 WC Oceanography SC Oceanography GA TA726 UT WOS:A1995TA72600008 ER PT J AU WU, DL HAYS, PB SKINNER, WR AF WU, DL HAYS, PB SKINNER, WR TI A LEAST-SQUARES METHOD FOR SPECTRAL-ANALYSIS OF SPACE-TIME SERIES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MIDDLE ATMOSPHERE; SATELLITE AB Common methods in spectral analyses of satellite data are the discrete Fourier transform (DFT) type of approaches, which generally require regular sampling and uniform spacing. These conditions sometimes cannot be met in the satellite applications, for example, such as one made by the High Resolution Doppler Imager (HRDI) on board the Upper Atmosphere Research Satellite (UARS). To be able to handle irregular sampling cases, a least squares fitting method is established here for a space-time Fourier analysis and has been applied to the HRDI sampling as well as other regular sampling cases. This method can resolve space-time spectra as robustly and accurately as DFT-type methods for the regular cases. In the same fashion, given an appropriate sampling pattern, it can also handle the irregular cases in which there exist large data gaps, frequent mode changes, and varying weight samples. Various sampling schemes and the associated aliasing spectra are examined. A better sampling plan than those currently used by the UARS instruments to reduce spectral aliasing is proposed, which leads to the question of how to optimize satellite sampling in the future. C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. RP WU, DL (reprint author), CALTECH,JET PROP LAB,MAIL STOP 183-701,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Wu, Dong/D-5375-2012 NR 18 TC 80 Z9 80 U1 1 U2 5 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 OCT 15 PY 1995 VL 52 IS 20 BP 3501 EP 3511 DI 10.1175/1520-0469(1995)052<3501:ALSMFS>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RY943 UT WOS:A1995RY94300003 ER PT J AU SCHLEGEL, EM SINGH, J AF SCHLEGEL, EM SINGH, J TI ROSAT PSPC SPECTRA OF THE CATACLYSMIC VARIABLES MV-LYR AND KR-AUR SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE STARS, INDIVIDUAL, MV LYR; STARS, INDIVIDUAL, KR AUR; NOVAE, CATACLYSMIC VARIABLES; X-RAYS, STARS ID ACCRETION DISKS; BINARIES; AURIGAE AB We have obtained PSPC spectra of the antidwarf novae MV Lyr and KR Aur. Both spectra can be fitted with simple continuum models; in particular, a blackbody best describes both spectra. For KR Aur, a power law is also a good match to the spectrum. For MV Lyr, the Einstein similar to 5-keV bremsstrahlung spectral model appears to be excluded by the PSPC data. The differences are unlikely to be the result of incomplete phase coverage between the observation epochs. Neither PSPC spectrum shows any evidence for line emission in contrast to a recent report on four dwarf novae. RP SCHLEGEL, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 26 TC 5 Z9 5 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 15 PY 1995 VL 276 IS 4 BP 1365 EP 1372 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TA933 UT WOS:A1995TA93300037 ER PT J AU PENDLETON, GN PACIESAS, WS MALLOZZI, RS KOSHUT, TM FISHMAN, GJ MEEGAN, CA WILSON, RB HORACK, JM LESTRADE, JP AF PENDLETON, GN PACIESAS, WS MALLOZZI, RS KOSHUT, TM FISHMAN, GJ MEEGAN, CA WILSON, RB HORACK, JM LESTRADE, JP TI THE DETECTOR RESPONSE MATRICES OF THE BURST AND TRANSIENT SOURCE EXPERIMENT (BATSE) ON THE COMPTON GAMMA-RAY OBSERVATORY SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article AB The detector response matrices for the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) are described, including their creation and operation in data analysis. These response matrices are a detailed abstract representation of the gamma-ray detectors' operating characteristics that are needed for data analysis. They are constructed from an extensive set of calibration data coupled with a complex geometry electromagnetic cascade Monte Carlo simulation code. The calibration tests and simulation algorithm optimization are described. The characteristics of the BATSE detectors in the spacecraft environment are also described. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. MISSISSIPPI STATE UNIV,DEPT PHYS,MISSISSIPPI STATE,MS 39762. RP PENDLETON, GN (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. RI Horack, John/J-6670-2016 NR 14 TC 39 Z9 39 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD OCT 15 PY 1995 VL 364 IS 3 BP 567 EP 577 DI 10.1016/0168-9002(95)00448-3 PG 11 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA RZ517 UT WOS:A1995RZ51700018 ER PT J AU BELL, LD KAISER, WJ MANION, SJ MILLIKEN, AM FATHAUER, RW PIKE, WT AF BELL, LD KAISER, WJ MANION, SJ MILLIKEN, AM FATHAUER, RW PIKE, WT TI BALLISTIC-ELECTRON-EMISSION MICROSCOPY OF STRAIN NONUNIFORMITIES IN SI1-XGEX/SI STRUCTURES SO PHYSICAL REVIEW B LA English DT Article ID HOT-CARRIER TRANSPORT; INTERFACE; SPECTROSCOPY; SILICON; SURFACE; TEMPERATURE; SCATTERING; LAYERS; SYSTEM; GOLD AB Ballistic-electron-emission microscopy (BEEM) is used to probe local conduction-band structure in strained Si1-xGex layers of pseudomorphic Si1-xGex/Si heterostructures. The strain variation produced by a roughened Si1-xGex surface is seen as a variation of splining between thresholds in BEEM spectroscopy. This splitting is directly related to the strain-induced conduction-band splitting in the Si1-xGex layer, enabling BEEM to directly measure local strain variations. Elasticity calculations for a roughened Si1-xGex surface predict variations in strain that are consistent with BEEM observations. For the case of a smooth Si1-xGex surface, a uniform conduction-band splining is observed that is in good agreement with calculations. RP BELL, LD (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 31 TC 8 Z9 8 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD OCT 15 PY 1995 VL 52 IS 16 BP 12081 EP 12089 DI 10.1103/PhysRevB.52.12081 PG 9 WC Physics, Condensed Matter SC Physics GA TB966 UT WOS:A1995TB96600084 ER PT J AU KNOX, L AF KNOX, L TI DETERMINATION OF INFLATIONARY OBSERVABLES BY COSMIC MICROWAVE BACKGROUND ANISOTROPY EXPERIMENTS SO PHYSICAL REVIEW D LA English DT Article ID MINIMAL ISOCURVATURE MODEL; RADIOMETER 1ST-YEAR MAPS; DEGREE ANGULAR SCALES; TENSOR PERTURBATIONS; GRAVITATIONAL-WAVES; RADIATION; UNIVERSE; COBE; FLUCTUATIONS; CONSTRAINTS AB Inflation produces nearly scale-invariant scalar and tenser perturbation spectra which lead to anisotropy in the cosmic microwave background (CMB). The amplitudes and shapes of these spectra can be parametrized by Q(S)(2), r = Q(T)(2)/Q(S)(2) n(S), and n(T) where Q(S)(2) and Q(T)(2) are the scalar and tenser contributions to the square of the CMB quadrupole and n(S) and n(T) are the power-law spectral indices. Even if we restrict ourselves to information from angles greater than one-third of a degree, three of these observables can be measured with some precision. The combination 105(1-n S)Q(S)(2) can be known to better than +/-0.3%. The scalar index ns can be determined to better than +/-0.02. The ratio r can be known to about +/-0.1 for n(S) similar or equal to 1 and slightly better for smaller n(S). The precision with which n(T) can be measured depends weakly on n(S) and strongly on r. For n(S) similar or equal to 1, n(T) can be determined with a precision of about +/-0.056(1.5 +/- r)/r. A full-sky experiment with a 20 are min beam using technology available today, similar to those being planned by several groups, can achieve the above precision. Good angular resolution is more important than high signal-to-noise ratio; for a given detector sensitivity and observing time a smaller beam provides more information than a larger beam. The uncertainties in ns and r are roughly proportional to the beam size. We briefly discuss the effects of uncertainty in the Hubble constant, baryon density, cosmological constant, and ionization history. C1 UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. NR 82 TC 323 Z9 322 U1 0 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1995 VL 52 IS 8 BP 4307 EP 4318 DI 10.1103/PhysRevD.52.4307 PG 12 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA TA527 UT WOS:A1995TA52700007 ER PT J AU MIECZNIK, G BRAGE, T AF MIECZNIK, G BRAGE, T TI J-DEPENDENT LIFETIMES OF THE 2S2P3P-D-4(E) AND 2S2P3D-F-4(O) TERMS IN THE BORON ISOELECTRONIC SEQUENCE SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID F-V; DECAY AB Lifetimes of fine-structure levels in 2s2p3p D-4 and 2s2p3d F-4(o) quartets are calculated in the boron isoelectronic sequence, for C II to F V, using a multiconfiguration Hartree-Fock approach. These quartets are known from earlier experimental and theoretical studies to have different lifetimes for different J-levels, owing to spin-induced transitions, mainly to doublet states in 2s(2)2p and 2s2p(2) configurations. Present work reproduces adequately the experimental features in F V and O IV. We also predict a weak J-dependency of the lifetimes in N III, in contrast to earlier measurements. C1 UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. NRC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MIECZNIK, G (reprint author), UNIV COLORADO,DEPT PHYS,BOULDER,CO 80309, USA. NR 20 TC 2 Z9 2 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD OCT 14 PY 1995 VL 28 IS 19 BP 4233 EP 4247 DI 10.1088/0953-4075/28/19/009 PG 15 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA TA898 UT WOS:A1995TA89800009 ER PT J AU LEE, TJ AF LEE, TJ TI AB-INITIO CHARACTERIZATION OF TRIATOMIC BROMINE MOLECULES OF POTENTIAL INTEREST IN STRATOSPHERIC CHEMISTRY SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; ELECTRON CORRELATION; ROW ATOMS; CONTRACTION; ENERGIES; 1ST-ROW; DIPOLE AB The equilibrium structures, harmonic vibrational frequencies, quadratic force fields, dipole moments, and IR intensities of several triatomic bromine compounds of known or potential importance in stratospheric ozone depletion chemistry have been determined using the CCSD(T) electron correlation method in conjunction with a basis set of triple zeta double polarized (TZ2P) quality. Specifically, the molecules included in the present study are HOBr, HBrO, FOBr, FBrO, BrNO, BrON, Br2O, BrBrO, BrCN, BrNC, ClOBr, ClBrO, and BrClO. Very accurate isomeric energy differences have also been determined at the CCSD(T) level with atomic natural orbital basis sets that include through g-type functions. In most cases, the isomer with a normal neutral Lewis dot structure is the lowest energy form, with the single exception that FBrO is predicted to be 11.1 kcal/mol (0 K) lower in energy than FOBr. In all cases, however, the hypervalent isomer is more stable relative to the isomer with a normal Lewis riot structure as compared to the chlorine analogs. Consistent with this observation, the energy of the last three molecules given above increases in the order ClOBr (ClBrO < BrClO. The CCSD(T)TZ2P geometries and vibrational frequencies are in good agreement with the available experimental data. Heats of formation are determined for all species using a combination of theoretical isomeric, homodesmic, and isodesmic reaction energies. The accuracy of these quantities is ultimately dependent on the reliability of the experimental heat of formation of HOBr. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 45 TC 76 Z9 76 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD OCT 12 PY 1995 VL 99 IS 41 BP 15074 EP 15080 DI 10.1021/j100041a024 PG 7 WC Chemistry, Physical SC Chemistry GA RZ373 UT WOS:A1995RZ37300024 ER PT J AU DEHU, C MEYERS, F HENDRICKX, E CLAYS, K PERSOONS, A MARDER, SR BREDAS, JL AF DEHU, C MEYERS, F HENDRICKX, E CLAYS, K PERSOONS, A MARDER, SR BREDAS, JL TI SOLVENT EFFECTS ON THE 2ND-ORDER NONLINEAR-OPTICAL RESPONSE OF PI-CONJUGATED MOLECULES - A COMBINED EVALUATION THROUGH SELF-CONSISTENT REACTION FIELD CALCULATIONS AND HYPER-RAYLEIGH SCATTERING MEASUREMENTS SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Note ID SOLVATED MOLECULES; POLARITY C1 UNIV MONS HAINAUT,SERV CHIM MAT NOUVEAUX,CTR RECH ELECTR & PHOTON MOLEC,B-7000 MONS,BELGIUM. UNIV LOUVAIN,CTR RES MOLEC ELECTR & PHOTON,CHEM & BIOL DYNAM LAB,B-3001 LOUVAIN,BELGIUM. CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCES,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. RI Bredas, Jean-Luc/A-3431-2008 OI Bredas, Jean-Luc/0000-0001-7278-4471 NR 23 TC 104 Z9 104 U1 1 U2 9 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD OCT 11 PY 1995 VL 117 IS 40 BP 10127 EP 10128 DI 10.1021/ja00145a030 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA RZ838 UT WOS:A1995RZ83800030 ER PT J AU SHAKLAN, S SHARMAN, MC PRAVDO, SH AF SHAKLAN, S SHARMAN, MC PRAVDO, SH TI HIGH-PRECISION MEASUREMENT OF PIXEL POSITIONS IN A CHARGE-COUPLED-DEVICE SO APPLIED OPTICS LA English DT Article DE CHARGE-COUPLED DEVICES; INTERFEROMETRY; METROLOGY; FIBERS (SINGLE-MODE); ASTRONOMY ID MODULATION TRANSFER-FUNCTION AB The high level of spatial uniformity in modern CCD's makes them excellent devices for astrometric instruments. However, at the level of accuracy envisioned by the more ambitious projects such as the Astrometric Imaging Telescope, current technology produces CCD's with significant pixel registration errors. We describe a technique for making high-precision measurements of relative pixel positions. We measured CCD's manufactured for the Wide Field Planetary Camera II installed in the Hubble Space Telescope. These CCD's are shown to have significant step-and-repeat errors of 0.033 pixel along every 34th row, as well as a 0.003-pixel curvature along 34-pixel stripes. The source of these errors is described. Our experiments achieved a per-pixel accuracy of 0.011 pixel. The ultimate shot-noise limited precision of the method is less than 0.001 pixel. RP SHAKLAN, S (reprint author), CALTECH,JET PROP LAB,MAIL STOP 306-388,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 21 Z9 22 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 OCT 10 PY 1995 VL 34 IS 29 BP 6672 EP 6681 PG 10 WC Optics SC Optics GA RX164 UT WOS:A1995RX16400007 PM 21060522 ER PT J AU CHIANG, J FICHTEL, CE VONMONTIGNY, C NOLAN, PL PETROSIAN, V AF CHIANG, J FICHTEL, CE VONMONTIGNY, C NOLAN, PL PETROSIAN, V TI THE EVOLUTION OF GAMMA-RAY LOUD ACTIVE GALACTIC NUCLEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GAMMA RAYS, OBSERVATIONS; QUASARS, GENERAL ID LUMINOSITY FUNCTION; REDSHIFT; SAMPLES; QUASARS; EGRET; QSOS AB During the period from the launch of the Compton Observatory in 1991 April through 1993 September, the Energetic Gamma-Ray Experiment Telescope (EGRET) has detected, with high significance (> 5 sigma), 33 blatar-type QSOs which are sources of high-energy gamma-rays and another eight which show strong evidence for high-energy gamma-ray emission. Many of the gamma-ray loud blazars have redshifts z similar to 1 with the most distant source having a redshift of z = 2.2. The V/V-max test has been applied to the sample of gamma-ray loud AGNs seen during the phase I and II observing periods, and evidence for the evolution of these sources consistent with pure luminosity evolution is presented. The effects of observational biases due to gamma-ray flux-detection limits and optical identifications are considered. Using the V-e/V-a test, we find the parameters describing the evolution, and by de-evolving the sample, we make an estimate of the luminosity function of these objects. Finally, using this luminosity function, we make an estimate of the gamma-ray loud AGN contribution to the diffuse extragalactic emission. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. STANFORD UNIV, WW HANSEN EXPTL PHYS LAB, STANFORD, CA 94305 USA. STANFORD UNIV, CTR SPACE SCI & ASTROPHYS, STANFORD, CA 94305 USA. STANFORD UNIV, DEPT PHYS, STANFORD, CA 94305 USA. STANFORD UNIV, DEPT APPL PHYS, STANFORD, CA 94305 USA. RP CHIANG, J (reprint author), CANADIAN INST THEORET ASTROPHYS, MCLENNAN LABS, 60 ST GEORGE ST, TORONTO, ON M5S 1A1, CANADA. RI Nolan, Patrick/A-5582-2009 NR 24 TC 72 Z9 75 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP 156 EP 163 DI 10.1086/176287 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700013 ER PT J AU TITARCHUK, L HUA, XM AF TITARCHUK, L HUA, XM TI A COMPARISON OF THERMAL COMPTONIZATION MODELS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES SEYFERT; PLASMAS; RADIATION MECHANISMS, THERMAL; RADIATIVE TRANSFER ID RADIATION; SPECTRA; RAYS AB We compare our analytic and Monte Carlo relativistic thermal models for photon Comptonization with previous thermal models in the literature. We show that the rejection of a pure thermal model for interpreting the OSSE-Ginga data ''at the likelihood of similar to 95%'' is the result of inaccuracy of the numerical thermal model used. Therefore, there is no need for a hybrid nonthermal/thermal model for the interpretation of these data. RP TITARCHUK, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 15 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 OCT 10 PY 1995 VL 452 IS 1 BP 226 EP 229 DI 10.1086/176293 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700019 ER PT J AU SODROSKI, TJ ODEGARD, N DWEK, E HAUSER, MG FRANZ, BA FREEDMAN, I KELSALL, T WALL, WF BERRIMAN, GB ODENWALD, SF BENNET, C REACH, WT WEILAND, JL AF SODROSKI, TJ ODEGARD, N DWEK, E HAUSER, MG FRANZ, BA FREEDMAN, I KELSALL, T WALL, WF BERRIMAN, GB ODENWALD, SF BENNET, C REACH, WT WEILAND, JL TI THE RATIO OF H-2 COLUMN DENSITY TO (CO)-C-12 INTENSITY IN THE VICINITY OF THE GALACTIC-CENTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, CENTER; ISM, ABUNDANCES; ISM, MOLECULES ID GIANT MOLECULAR CLOUDS; MILKY-WAY; RADIAL-DISTRIBUTION; GAS-DISTRIBUTION; CENTRAL REGION; OUTER GALAXY; GAMMA-RAYS; CO SURVEY; EMISSION; DUST AB Observations from the COBE(7) Diffuse Infrared Background Experiment (DIRBE) at wavelengths of 140 and 240 mu m are combined with the Goddard-Columbia (CO)-C-12 (J = 1 --> 0) surveys to derive an estimate for X, the ratio of H-2 column density to (CO)-C-12 intensity, within approximately 400 pc of the Galactic center. The H-2 column density is inferred from the infrared observations by assuming a proportionality between dust-to-gas mass ratio and gas metallicity. It is found that the value of X in the Galactic center region is a factor of 3-10 lower than the corresponding ratio for molecular cloud complexes in the inner Galactic disk. Therefore, the use of the inner disk value of X to derive the mass of molecular hydrogen in the vicinity of the Galactic center and the 300 MeV-5 GeV gamma ray flux from that region will result in overestimates of both quantities. We attribute the so-called gamma-ray deficit from the Galactic center region to the erroneous use of a constant value of X throughout the Galaxy. Combining our results with several virial analyses of giant molecular cloud complexes in the Galactic disk, we find that the value of X increases by more than an order of magnitude from the Galactic center to a Galactocentric distance of 13 kpc. This implies that studies of the large-scale (CO)-C-12 emission from our own Galaxy and external spiral galaxies, in which a constant ratio of H-2 column density to (CO)-C-12 intensity was adopted, have significantly overestimated the relative amount of molecular hydrogen at small Galactocentric distances and significantly underestimated the relative amount of molecular hydrogen at large Galactocentric distances. C1 NASA, GODDARD SPACE FLIGHT CTR, GEN SCI CORP, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RP SODROSKI, TJ (reprint author), NASA, GODDARD SPACE FLIGHT CTR, APPL RES CORP, CODE 6853, GREENBELT, MD 20771 USA. RI Dwek, Eli/C-3995-2012; Franz, Bryan/D-6284-2012; OI Franz, Bryan/0000-0003-0293-2082; Reach, William/0000-0001-8362-4094 NR 55 TC 93 Z9 94 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP 262 EP 268 DI 10.1086/176297 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700023 ER PT J AU MUSIELAK, ZE MOORE, RL AF MUSIELAK, ZE MOORE, RL TI KLEIN-GORDON EQUATION AND THE LOCAL CRITICAL FREQUENCY FOR ALFVEN WAVES PROPAGATING IN AN ISOTHERMAL ATMOSPHERE SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; STARS, ATMOSPHERES; SUN, CORONA; WAVES ID HORIZONTAL MAGNETIC-FIELD; SOLAR CORONAL HOLES; REFLECTION; MODES AB A Klein-Gordon equation approach developed by Musielak, Fontenla, and Moore for assessing reflection of Alfven waves in a smoothly nonuniform medium is reexamined. In this approach, the local critical frequency for strong reflection is simply found by transforming the wave equations into their Klein-Gordon forms and then choosing the largest positive coefficient of the zeroth-order term to be the square of the local critical frequency. In this paper, we verify this approach for a particular atmosphere and show that the local critical frequency can be alternatively defined by using the turning-point property of Euler's equation. Our results are obtained specifically for steady state, linear Alfven waves in an isothermal atmosphere with constant gravity and uniform vertical magnetic field. The upward Alfven waves (those above the wave source) are standing waves and the downward waves (those below the wave source) are propagating waves. We demonstrate that for any given wave frequency both upward and downward waves have the same turning point or critical height. This height is determined by the condition omega = Omega(A) = V-A/2H, where V-A is the Alfven velocity and H is the scale height; Omega(A) can be taken as the local critical frequency for strong reflection for the upward waves and as the local critical frequency for free propagation for the downward waves. Our turning-point analysis also yields another interesting result: for our particular model atmosphere the magnetic field perturbation wave equation yields the local critical frequency but the velocity-perturbation wave equation does not. Thus, for this model atmosphere, we find that the Klein-Gordon equation approach of Musielak, Fontenla, and Moore is correct in (1) its choice of the magnetic-field-perturbation wave equation for finding the local critical frequency, and (2) its assumption that the upward and downward waves have the same critical frequency. C1 UNIV ALABAMA,DEPT MECH & AEROSP ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP MUSIELAK, ZE (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 24 TC 22 Z9 22 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP 434 EP 444 DI 10.1086/176314 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700040 ER PT J AU HOLMAN, GD AF HOLMAN, GD TI DC ELECTRIC-FIELD ACCELERATION OF IONS IN SOLAR-FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; PLASMAS; SUN, FLARES; SUN, X-RAYS; GAMMA RAYS ID THERMAL NONTHERMAL MODEL; MICROWAVE AB It is shown that the seed particles required for solar flare energetic particles and gamma-ray bursts can be generated through the DC electric field acceleration of thermal ions. For an electric field strength on the order of but less than the Dreicer field (the critical field strength above which the entire electron distribution is in the runaway regime), a significant fraction of the thermal ions is accelerated up to a velocity in the range 0.1-1 upsilon(the) where upsilon(the) is the electron thermal velocity (giving ion energies up to 10-1000 keV nucleon(-1)). These ions are then available for additional acceleration by waves, or may be further accelerated in the current channels themselves if the electric field exceeds the Dreicer held. Heavier ions are found to have lower thresholds for runaway acceleration than protons and are therefore expected to have enhanced abundances at the energies to which they are accelerated. Under the conditions required for proton acceleration, the entire population of ions more massive than lithium is accelerated up to the electron drift velocity. RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, CODE 682, GREENBELT, MD 20771 USA. RI Holman, Gordon/C-9548-2012 NR 27 TC 26 Z9 27 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP 451 EP 456 DI 10.1086/176316 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700042 ER PT J AU SHEMANSKY, DE AJELLO, JM KANIK, I AF SHEMANSKY, DE AJELLO, JM KANIK, I TI ELECTRON-EXCITATION FUNCTIONS OF THE N-2 2ND POSITIVE SYSTEM SO ASTROPHYSICAL JOURNAL LA English DT Article ID CROSS-SECTIONS; IMPACT EXCITATION; TRANSITION-PROBABILITIES; VACUUM ULTRAVIOLET; N+2 SYSTEMS; N2; BAND; EMISSION; RESONANCES; THRESHOLD AB The band strengths of the electron excited N-2(C-3 Pi(u)-B-3 Pi(g)) second positive system (2PG) have been measured in the middle ultraviolet (MUV) range (280-444 Mn). The energy dependence of the (0,0) and (1,0) band cross sections is reported with analytic shape functions for use in model calculations. The excitation functions were measured at low pressure to avoid effects of collisional cascade from higher lying states. At low electron energies (11-15 eV), the resolution and energy spacing of the excitation function measurements were sufficient to reveal the importance of threshold effects from resonance processes. The absolute cross section of the 337.14 nm band has a peak value of 1.11 +/- 0.15 x 10(-17) cm(2) at 14.1 eV. Above 30 eV the cross section decreases with an asymptotic E(-2) dependence. A spectral analysis of the 2PG band system at 14 and 20 eV has provided relative excited state vibrational level cross sections. The variation of the electronic transition moment over the wavelength range indicated above, has been derived, and an improved transition probability matrix has been obtained. The rate coefficient for solar photoelectron excitation of the (0,0) band is 9.1 x 10(-10) cm(3) s(-1) for photoelectrons above 11.0 eV, a factor of similar to 1.3 smaller than the previous recommended value. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP SHEMANSKY, DE (reprint author), UNIV SO CALIF, DEPT AEROSP ENGN, LOS ANGELES, CA 90089 USA. NR 32 TC 28 Z9 28 U1 3 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 OCT 10 PY 1995 VL 452 IS 1 BP 472 EP 479 DI 10.1086/176319 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700045 ER PT J AU SHEMANSKY, DE KANIK, I AJELLO, JM AF SHEMANSKY, DE KANIK, I AJELLO, JM TI FINE-STRUCTURE BRANCHING IN N-2-C'(4)-(1)SIGMA(+)(U)-(0) SO ASTROPHYSICAL JOURNAL LA English DT Article DE METHODS, LABORATORY; MOLECULAR DATA; MOLECULAR PROCESSES; ULTRAVIOLET, GENERAL ID EXTREME ULTRAVIOLET EMISSION; ELECTRON-IMPACT EXCITATION; MEDIUM-RESOLUTION; STATE; PREDISSOCIATION; 1-SIGMA-U+; N2 AB We report a quantitative measurement of the predissociation fraction in the N(2)c'(1)(4) Sigma(u)(+)-X(1) Sigma(g)(+) (0,0) band, with an experimental determination of rotational line strengths. The fine structure of the N-2(c'(4)-X) (0,0) band has been analyzed in optically thin laboratory emission spectra obtained from crossed electron and N-2 beams. The distortion of the emission envelope from calculations based on constant rotational level radiative transition probabilities and a thermalized ground state source population has been used to obtain an estimated predissociation loss fraction of 0.15(-0.045)(+0.01) for the N(2)c'(4)(0) level averaged over rotational structure at a neutral gas temperature of 300 K. The analysis has been aided by measurements at gas temperatures depressed over a range from 300 to 30 K. The predissociation rate is temperature dependent, caused by nonuniform predissociation at intermediate and high rotational levels. The coupling of the rotational branches, also measured quantitatively for N(2)c'(4)(0) for the first time in this experiment, is complicated by configuration mixing with the c(3)(1) Pi(u) and b(1) Pi(u) states forcing strong departures from Honl-London factors. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SHEMANSKY, DE (reprint author), UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089, USA. NR 20 TC 29 Z9 29 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP 480 EP 485 DI 10.1086/176320 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX157 UT WOS:A1995RX15700046 ER PT J AU KOERNER, DW CHANDLER, CJ SARGENT, AI AF KOERNER, DW CHANDLER, CJ SARGENT, AI TI APERTURE SYNTHESIS IMAGING OF THE CIRCUMSTELLAR DUST DISK AROUND DO TAURI SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; PLANETARY SYSTEMS; STARS, FORMATION; STARS, INDIVIDUAL (DO TAURI) ID YOUNG STELLAR OBJECTS; T-TAURI; FORBIDDEN-LINE; STARS; PROFILES; SPECTRA AB We have detected the T Tauri star, DO Tauri, in a 0''.6 resolution VLA map of 43.3 GHz (lambda = 7 mm) continuum emission. The 43 GHz flux density lies on the same power-law slope defined by 89-232 GHz measurements, F-nu proportional to nu(alpha) with index alpha = 2.39 +/- 0.23, confirming that the 43.3 GHz emission is thermal radiation from circumstellar dust. Upper limits to the flux densities at 8.4 and 22.5 GHz constrain the contribution of free-free emission from a compact ionized wind to be less than 49%. The dust emissivity index, beta, is 0.39 +/- 0.23 if the emission is optically thin. Fitting a model of a thin circumstellar disk to the observed spectral energy distribution gives beta = 0.6 +/- 0.3, consistent with the power-law derivation. Both values are substantially lower than is generally accepted for the interstellar medium, suggesting grain growth. Given the youth of DO Tau and the early evolutionary state of its circumstellar disk, this result implies that millimeter-size grains have already formed by the early T Tauri phase. C1 CALTECH,PASADENA,CA 91125. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. CALTECH,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. RP KOERNER, DW (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,169-506,PASADENA,CA 91109, USA. NR 37 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 OCT 10 PY 1995 VL 452 IS 1 BP L69 EP L72 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX158 UT WOS:A1995RX15800018 ER PT J AU MASSA, D FULLERTON, AW NICHOLS, JS OWOCKI, SP PRINJA, RK STLOUIS, N WILLIS, AJ ALTNER, B BOLTON, CT CASSINELLI, JP COHEN, D COOPER, RG FELDMEIER, A GAYLEY, KG HARRIES, T HEAP, SR HENRIKSEN, RN HOWARTH, ID HUBENY, I KAMBE, E KAPER, L KOENIGSBERGER, G MARCHENKO, S MCCANDLISS, SR MOFFAT, AFJ NUGIS, T PULS, J ROBERT, C SCHULTELADBECK, RE SMITH, LJ SMITH, MA WALDRON, WL WHITE, RL AF MASSA, D FULLERTON, AW NICHOLS, JS OWOCKI, SP PRINJA, RK STLOUIS, N WILLIS, AJ ALTNER, B BOLTON, CT CASSINELLI, JP COHEN, D COOPER, RG FELDMEIER, A GAYLEY, KG HARRIES, T HEAP, SR HENRIKSEN, RN HOWARTH, ID HUBENY, I KAMBE, E KAPER, L KOENIGSBERGER, G MARCHENKO, S MCCANDLISS, SR MOFFAT, AFJ NUGIS, T PULS, J ROBERT, C SCHULTELADBECK, RE SMITH, LJ SMITH, MA WALDRON, WL WHITE, RL TI THE IUE MEGA CAMPAIGN - WIND VARIABILITY AND ROTATION IN EARLY-TYPE STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACTIVITY; STARS, EARLY-TYPE; STARS, MASS LOSS; ULTRAVIOLET, STARS AB Wind variability in OB stars may be ubiquitous, and a connection between projected stellar rotation velocity and wind activity is well established. However, the origin of this connection is unknown. To probe the nature of the rotation connection, several of the attendees at the workshop on Instability and Variability of Hot-Star Winds drafted an IUE observing proposal. The goal of this program was to follow three stars for several rotations to determine whether the rotation connection is correlative or causal. The stars selected for monitoring all have rotation periods less than or equal to 5 days. They were HD 50896 (WN5), HD 64760 (B0.5 Ib), and HD 66811 [zeta Pup; O4 If(n)]. During 16 days of nearly continuous observations in 1995 January (dubbed the ''MEGA'' campaign), 444 high-dispersion IUE spectra of these stars were obtained. This Letter presents an overview of the results of the MEGA campaign and provides an introduction to the three following Letters, which discuss the results for each star. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. MAX PLANCK INST ASTROPHYS,D-85740 GARCHING,GERMANY. COMP SCI CORP,IUE OBSERV,LANHAM,MD 20706. UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND. UNIV MONTREAL,DEPT PHYS,MONTREAL,PQ H3C 3J7,CANADA. UNIV TORONTO,DAVID DUNLAP OBSERV,RICHMOND HILL,ON L4C 4Y6,CANADA. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV STERNWARTE MUNCHEN,D-81679 MUNICH,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. QUEENS UNIV,DEPT PHYS,KINGSTON,ON K7L 3N6,CANADA. NATL DEF ACAD,DEPT GEOSCI,YOKOSUKA,KANAGAWA 239,JAPAN. EUROPEAN SO OBSERV,D-85748 GARCHING,GERMANY. NATL AUTONOMOUS UNIV MEXICO,INST ASTRON,MEXICO CITY 04510,DF,MEXICO. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CTR ASTRON SCI,BALTIMORE,MD 21218. ESTONIAN ACAD SCI,TARTU ASTROPHYS OBSERV,202444 TARTU,ESTONIA. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. RP MASSA, D (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. RI White, Richard/A-8143-2012; heap, sara/E-2237-2012; OI Harries, Timothy/0000-0001-8228-9503 NR 25 TC 81 Z9 81 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1995 VL 452 IS 1 BP L53 EP & PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX158 UT WOS:A1995RX15800014 ER PT J AU MAHESH, K LEE, SS LELE, SK MOIN, P AF MAHESH, K LEE, SS LELE, SK MOIN, P TI THE INTERACTION OF AN ISOTROPIC FIELD OF ACOUSTIC-WAVES WITH A SHOCK-WAVE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TURBULENCE AMPLIFICATION; FLOW AB Moore's (1954) inviscid linear analysis of the interaction of a shock wave with a plane acoustic wave is evaluated by comparison to computation. The analysis is then extended to study the interaction of an isotropic held of acoustic waves with a normal shock wave. The evolution of fluctuating kinetic energy, sound level and thermodynamic fluctuations across the shock wave are examined in detail. The interaction of acoustic fluctuations with the shock is notably different from that of vortical fluctuations. The kinetic energy of the acoustic fluctuations decreases across the shock wave for Mach numbers between 1.25 and 1.8. For Mach numbers exceeding 3, the kinetic energy amplifies by levels that significantly exceed those found in the interaction of vortical fluctuations with the shock. Upon interacting with the shock wave, the acoustic waves generate vortical fluctuations whose contribution to the far-field kinetic energy increases with increasing Mach number. The level of sound increases across the shock wave. The rise in the sound pressure level across the shock varies from 5 to 20 dB for Mach number varying from 1.5 to 5. The fluctuations behind the shock wave are nearly isentropic for Mach number less than 1.5, beyond which the generation of entropy fluctuations becomes significant. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MAHESH, K (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 42 TC 38 Z9 38 U1 1 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD OCT 10 PY 1995 VL 300 BP 383 EP 407 DI 10.1017/S0022112095003739 PG 25 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA TD014 UT WOS:A1995TD01400016 ER PT J AU RAVAT, D LANGEL, RA PURUCKER, M ARKANIHAMED, J ALSDORF, DE AF RAVAT, D LANGEL, RA PURUCKER, M ARKANIHAMED, J ALSDORF, DE TI GLOBAL VECTOR AND SCALAR MAGSAT MAGNETIC ANOMALY MAPS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID IONOSPHERIC FIELD CORRECTION; SATELLITE DATA; INVERSION; EARTH; 40-DEGREES-N; SEPARATION; LATITUDES; SPECTRUM; REGION; CORE AB Empirical and analytical techniques for modeling ionospheric fields in Magsat data have been developed that facilitate ionospheric field removal from uncorrected anomalies to obtain better estimates of regional lithospheric anomalies. This task has been accomplished for equatorial Delta X, Delta Z, and Delta B component and polar Delta Z and Delta B component measurements. The techniques for modeling ionospheric fields have been integrated into a processing sequence that incorporates some of the important data-processing techniques developed during the last decade. Dataprocessing techniques include retention of common signal in a correlation analysis of adjacent passes; analysis of field differences between dawn and dusk data at points where their orbits cross; and retention of common signal in a covariant spherical harmonic analysis procedure. Results suggest that implementation of the above processing scheme leads to the mapping of the most robust magnetic anomalies of the lithosphere (vector components as well as scalar). C1 NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. MCGILL UNIV, DEPT EARTH & PLANETARY SCI, MONTREAL, PQ, CANADA. CORNELL UNIV, DEPT GEOL SCI, ITHACA, NY 14853 USA. RP RAVAT, D (reprint author), SO ILLINOIS UNIV, DEPT GEOL, MAIL CODE 4324, CARBONDALE, IL 62901 USA. NR 52 TC 62 Z9 69 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD OCT 10 PY 1995 VL 100 IS B10 BP 20111 EP 20136 DI 10.1029/95JB01237 PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RZ312 UT WOS:A1995RZ31200010 ER PT J AU LANGEL, RA AF LANGEL, RA TI AN INVESTIGATION OF A CORRELATION COVARIANCE METHOD OF SIGNAL EXTRACTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID MAGSAT DATA; SATELLITE AB A harmonic correlation technique has been used effectively to isolate a primary signal from two independent data sets each of which is contaminated by the presence of interfering signals. Each of the two data sets is decomposed by a harmonic analysis, and then the correlation coefficients and amplitude ratios between the two decompositions are computed fbr each harmonic. Only harmonics which satisfy predetermined selection criteria are retained. Those criteria are in the form of requiring the correlation coefficient to exceed some magnitude, say, rho(0), and the amplitude ratio not to exceed some value, say, R(0). The resulting pair of retained signals are then typically highly correlated. It is suggested that appropriate values of rho(0) lie between 0.25 and 0.6 and of R(0) between 3.0 and 6.0, depending on the relative amplitudes of the primary and interfering signals. Critical examination of the technique shows that under many conditions it can be an effective tool for eliminating signals which are not a good approximation to the primary signal. This conclusion is confirmed by simulated examples of satellite magnetic anomaly data with interfering fields from ionospheric currents. RP LANGEL, RA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, CODE 921, GREENBELT, MD 20771 USA. NR 9 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD OCT 10 PY 1995 VL 100 IS B10 BP 20137 EP 20157 DI 10.1029/95JB01577 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RZ312 UT WOS:A1995RZ31200011 ER PT J AU RUBINCAM, DP MALLAMA, A AF RUBINCAM, DP MALLAMA, A TI TERRESTRIAL ATMOSPHERIC EFFECTS ON SATELLITE ECLIPSES WITH APPLICATION TO THE ACCELERATION OF LAGEOS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article AB We examine spatial variability of attenuation in the Earth's atmosphere as a cause of asymmetrical eclipses and consequent acceleration of LAGEOS, i.e., the solar radiation pressure on LAGEOS due to the Earth's penumbra. Measurements of atmospheric attenuation derived from the satellite-borne Stratospheric Aerosol and Gas Experiment after the eruption of Mount Pinatubo were used to simulate the largest expected aerosol content of the atmosphere. In our,experiment one hemisphere was loaded with volcanic aerosols, while the other was not. The difference between attenuation in the two hemispheres sets a maximum reasonable limit to the size of eclipse asymmetry. This condition would accelerate LAGEOS only about 0.2 picometers per second squared (pm s(-2) or 10(-12) s(-2)) and indicates that eclipse asymmetry can only account for about 40-50% of the remaining unmodeled residuals. This is slightly less than the penumbral acceleration found by Vokrouhlicky et al. (1994). C1 HUGHES STX CORP, DIV APPL SCI & TECHNOL, GREENBELT, MD USA. RP RUBINCAM, DP (reprint author), NASA, GODDARD SPACE FLIGHT CTR, TERR PHYS LAB, GEODYNAM BRANCH, CODE 921, GREENBELT, MD 20771 USA. RI Rubincam, David/D-2918-2012 NR 19 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD OCT 10 PY 1995 VL 100 IS B10 BP 20285 EP 20290 DI 10.1029/95JB02278 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RZ312 UT WOS:A1995RZ31200020 ER PT J AU FAHEY, DW KEIM, ER BOERING, KA BROOK, CA WILSON, JC JONSSON, HH ANTHONY, S HANISCO, TF WENNBERG, PO MIAKELYE, RC SALAWITCH, RJ LOUISNARD, N WOODBRIDGE, EL GAO, RS DONNELLY, SG WAMSLEY, RC DELNEGRO, LA SOLOMON, S DAUBE, BC WOFSY, SC WEBSTER, CR MAY, RD KELLY, KK LOEWENSTEIN, M PODOLSKE, JR CHAN, KR AF FAHEY, DW KEIM, ER BOERING, KA BROOK, CA WILSON, JC JONSSON, HH ANTHONY, S HANISCO, TF WENNBERG, PO MIAKELYE, RC SALAWITCH, RJ LOUISNARD, N WOODBRIDGE, EL GAO, RS DONNELLY, SG WAMSLEY, RC DELNEGRO, LA SOLOMON, S DAUBE, BC WOFSY, SC WEBSTER, CR MAY, RD KELLY, KK LOEWENSTEIN, M PODOLSKE, JR CHAN, KR TI EMISSION MEASUREMENTS OF THE CONCORDE SUPERSONIC AIRCRAFT IN THE LOWER STRATOSPHERE SO SCIENCE LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; CIVIL TRANSPORT AIRCRAFT; INSITU MEASUREMENTS; ER-2 AIRCRAFT; NITROGEN; AEROSOL; WINTER; OXIDE; CHEMISTRY; IMPACT AB Emission indices of reactive gases and particles were determined from measurements in the exhaust plume of a Concorde aircraft cruising at supersonic speeds in the stratosphere. Values for NOx (sum of NO and NO2) agree well with ground-based estimates. Measurements of NOx and HOx indicate a limited role for nitric acid in the plume. The large number of submicrometer particles measured implies efficient conversion of fuel sulfur to sulfuric acid in the engine or at emission. A new fleer of supersonic aircraft with similar particle emissions would significantly increase stratospheric aerosol surface areas and may increase ozone loss above that expected for NOx emissions alone. C1 UNIV DENVER,DEPT ENGN,DENVER,CO 80208. NOAA,AERON LAB,BOULDER,CO 80303. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. AERODYNE RES INC,BILLERICA,MA 01821. JET PROPULS LAB,PASADENA,CA 91109. OFF NATL ETUD & RECH AEROSP,PARIS,FRANCE. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093. UNIV COLORADO,CIRES,BOULDER,CO 80309. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Salawitch, Ross/B-4605-2009; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Fahey, David/0000-0003-1720-0634 NR 45 TC 118 Z9 119 U1 0 U2 8 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 6 PY 1995 VL 270 IS 5233 BP 70 EP 74 DI 10.1126/science.270.5233.70 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA RY302 UT WOS:A1995RY30200033 ER PT J AU OSTRO, SJ HUDSON, RS JURGENS, RF ROSEMA, KD CAMPBELL, DB YEOMANS, DK CHANDLER, JF GIORGINI, JD WINKLER, R ROSE, R HOWARD, SD SLADE, MA PERILLAT, P SHAPIRO, II AF OSTRO, SJ HUDSON, RS JURGENS, RF ROSEMA, KD CAMPBELL, DB YEOMANS, DK CHANDLER, JF GIORGINI, JD WINKLER, R ROSE, R HOWARD, SD SLADE, MA PERILLAT, P SHAPIRO, II TI RADAR IMAGES OF ASTEROID-4179 TOUTATIS SO SCIENCE LA English DT Article ID HALLEY AB Delay-Doppler images of the Earth-crossing asteroid 4179 Toutatis achieve resolutions as fine as 125 nanoseconds (19 meters in range) and 8.3 millihertz (0.15 millimeter per second in radial velocity) and place hundreds to thousands of pixels on the asteroid, which appears to be several kilometers long, topographically bifurcated, and heavily cratered. The image sequence reveals Toutatis to be in an extremely slow, non-principal axis rotation state. C1 WASHINGTON STATE UNIV,SCH ELECT ENGN & COMP SCI,PULLMAN,WA 99164. CORNELL UNIV,NATL ASTRON & IONOSPHERE CTR,ITHACA,NY 14853. CTR ASTROPHYS,CAMBRIDGE,MA 02138. ARECIBO OBSERV,ARECIBO,PR 00613. RP OSTRO, SJ (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-233,PASADENA,CA 91109, USA. NR 18 TC 62 Z9 63 U1 1 U2 5 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 6 PY 1995 VL 270 IS 5233 BP 80 EP 83 DI 10.1126/science.270.5233.80 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA RY302 UT WOS:A1995RY30200036 ER PT J AU HUDSON, RS OSTRO, SJ AF HUDSON, RS OSTRO, SJ TI SHAPE AND NONPRINCIPAL AXIS SPIN-STATE OF ASTEROID-4179 TOUTATIS SO SCIENCE LA English DT Article ID HALLEY AB Radar observations of Toutatis placed hundreds to thousands of pixels per image on the asteroid and revealed it to be a non-principal axis rotator. The radar data are used to calculate Toutatis's three-dimensional shape, spin state, and the ratios of the principal moments of inertia. Toutatis is rotating in a long-axis mode characterized by periods of 5.41 days (rotation about the long axis) and 7.35 days (average for long-axis precession), and its dimensions along the principal axes are 1.92, 2.40, and 4.60 kilometers. To within the model's uncertainties, Toutatis's density is homogeneous, or its inhomogeneities mimic the inertia tenser of a homogeneous body. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP HUDSON, RS (reprint author), WASHINGTON STATE UNIV,SCH ELECT ENGN & COMP SCI,PULLMAN,WA 99164, USA. NR 18 TC 115 Z9 120 U1 0 U2 7 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 6 PY 1995 VL 270 IS 5233 BP 84 EP 86 DI 10.1126/science.270.5233.84 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA RY302 UT WOS:A1995RY30200037 ER PT J AU FRANCISCO, JS SANDER, SP AF FRANCISCO, JS SANDER, SP TI EXISTENCE OF A CHLORINE OXIDE AND WATER (CLO-CENTER-DOT-H2O) RADICAL COMPLEX SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Note ID CONFIGURATION-INTERACTION; SELF-REACTION; MOLECULE; HO2 C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 18 TC 42 Z9 42 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD OCT 4 PY 1995 VL 117 IS 39 BP 9917 EP 9918 DI 10.1021/ja00144a021 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA RY582 UT WOS:A1995RY58200021 ER PT J AU SCHACHAM, SE HAUGLAND, EJ MENA, RA ALTEROVITZ, SA AF SCHACHAM, SE HAUGLAND, EJ MENA, RA ALTEROVITZ, SA TI MIXED CARRIER CONDUCTION IN MODULATION-DOPED FIELD-EFFECT TRANSISTORS SO APPLIED PHYSICS LETTERS LA English DT Article ID 2-DIMENSIONAL ELECTRON-GAS; MOBILITY; SI; HETEROSTRUCTURES; LAYERS AB The contribution of more than one carrier to the conductivity in modulation-doped field effect transistors (MODFET) affects the resultant mobility and complicates the characterization of these devices. Mixed conduction arises from the population of several subbands in the two-dimensional electron gas (2DEG), as well as the presence of a parallel path outside the 2DEG. We characterized GaAs/AlGaAs MODFET structures with both delta and continuous doping in the barrier. Based on simultaneous Hall and conductivity analysis we conclude that the parallel conduction is taking place in the AlGaAs barrier, as indicated by the carrier freezeout and activation energy. Thus, simple Hall analysis of these structures may lead to erroneous conclusions, particularly for real-life device structures. The distribution of the 2D electrons between the various confined subbands depends on the doping profile. While for a continuously doped barrier the Shubnikov-de Haas analysis shows superposition of two frequencies for concentrations below 10(12) cm(-2), for a delta doped structure the superposition is absent even at 50% larger concentrations. This result is confirmed by self-consistent analysis, which indicates that the concentration of the second subband hardly increases. (C) 1995 American Institute of Physics. RP SCHACHAM, SE (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 0 Z9 0 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD OCT 2 PY 1995 VL 67 IS 14 BP 2031 EP 2033 DI 10.1063/1.115068 PG 3 WC Physics, Applied SC Physics GA RX495 UT WOS:A1995RX49500026 ER PT J AU FREEMAN, DC STANLEY, DO CAMARDA, CJ LEPSCH, RA COOK, SA AF FREEMAN, DC STANLEY, DO CAMARDA, CJ LEPSCH, RA COOK, SA TI SINGLE-STAGE-TO-ORIBIT - A STEP CLOSER SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB Over the past several years there has been a significant effort within the United States to assess options to replace the Space Shuttle some time after the turn of the century. In order to provide a range of technology options, a wide variety of vehicle types and propulsion systems have been examined. These vehicle concepts which are representative of the classes of concepts that could be proposed for any future vehicle development is being used in the initial phase of the access to space activity to identify requirements for the technology maturation effort and to assess approaches to achieve the required low operations cost. This paper provides the results of recent systems analyses and describes the ongoing technology maturation and demonstration program supporting the Reusable Launch Vehicle Program. RP FREEMAN, DC (reprint author), NASA,LANGLEY RES CTR,SPACE TRANSPORTAT OFF,HAMPTON,VA 23681, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 87 EP 94 DI 10.1016/0094-5765(95)00087-G PG 8 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700008 ER PT J AU JARDIN, MR AF JARDIN, MR TI A FEEDBACK-CONTROLLED GAS MIXING SYSTEM FOR THE RAM ACCELERATOR SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT RP JARDIN, MR (reprint author), NASA,STERLING FED SYST INC,AMES DIV,PALO ALTO,CA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 105 EP 114 DI 10.1016/0094-5765(95)00090-M PG 10 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700010 ER PT J AU SPEAR, AJ AF SPEAR, AJ TI LOW-COST APPROACH TO MARS PATHFINDER SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB Mars Pathfinder, launching in December '96 and landing in July '97, will demo a low cost delivery system to the surface of Mars. Historically, spacecraft that orbit or land on a distant body carry a large amount of fuel for braking. Mars Pathfinder, thrusting only for navigation, enters directly into the Martian atmosphere, aerobrakes with its aeroshell, deploys a parachute at 10 km above the surface and, within 100 m off the surface, ignites solid rockets for final braking prior to deployment of air bags which cushion touchdown. After landing, petals open to upright the lander, exposing solar panels to the sun. Even though the lander and rover are expected to last longer, the major objectives of Mars Pathfinder, demonstrating EDL (Entry, Descent, Landing) and lander-rover surface operations, will occur within the first few days, at which time panoramic images of the surface will be transmitted and the rover will be deployed to conduct both mobility tests and rock composition measurements. While Mars Pathfinder is primarily an engineering demo, it accomplishes a focused, exciting set of science investigations with a stereo, multi-color lander imager; atmospheric instrumentation, used as a weather station after landing; and the rover with cameras and the APXS (Alpha Proton X-ray Spectrometer). This paper features Mars Pathfinder's approach to innovative and cost effective mission accomplishment, under a development cost cap. Mars Pathfinder is pathfinding a new way of doing business at NASA and JPL for small, low cost, Discovery class missions. RP SPEAR, AJ (reprint author), CALTECH,JET PROP LAB,MARS PATHFINDER PROJECT,PASADENA,CA, USA. NR 0 TC 0 Z9 0 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 131 EP 139 DI 10.1016/0094-5765(95)00066-9 PG 9 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700012 ER PT J AU ONEIL, WJ AUSMAN, NE LANDANO, MR MITCHELL, RT REICHERT, RJ AF ONEIL, WJ AUSMAN, NE LANDANO, MR MITCHELL, RT REICHERT, RJ TI GALILEO PREPARING FOR JUPITER ARRIVAL SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB The most critical events of the Galileo mission occur on Jupiter arrival day, December 7, 1995. In chronological order, these one-time events are: a 1,000 km altitude flyby of the innermost Galilean satellite Io, the 75-minute Atmospheric Entry Probe mission, and the Orbiter's Jupiter Orbit Insertion (JOI) maneuver. In addition, extensive, unique Orbiter science observations are planned because this is the only time Galileo will encounter Io, fly through the Io torus, and will be so close to Jupiter-three times closer than at any of the perijove passes in the orbital mission. All of these events occur in what will. be by far the most intense radiation environment Galileo will ever see. The focus of this Paper is the extraordinary preparations being made to maximize the reliability of the most critical events in order to ensure a successful Probe mission and Orbit Insertion while also gathering unique arrival day Orbiter science. The Paper also provides a mission status report including the return of the asteroid Ida data and the Galileo direct line-of-sight observations of Comet Shoemaker-Levy fragments impacting Jupiter in July 1994. RP ONEIL, WJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 247 EP 269 DI 10.1016/0094-5765(95)00069-C PG 23 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700022 ER PT J AU HARRIS, DW GROSS, K AF HARRIS, DW GROSS, K TI COMMERCIAL USE OF NASA TRACKING AND DATA RELAY SATELLITE SYSTEM FOR INTERNATIONAL COMMUNICATIONS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT RP HARRIS, DW (reprint author), NASA,OFF SPACE COMMUN,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 395 EP 406 PG 12 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700034 ER PT J AU GREEN, WB AF GREEN, WB TI MULTIMISSION GROUND DATA SYSTEM SUPPORT OF NASA PLANETARY PROGRAM SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB NASA funds the Multimission Operations Systems Office (MOSO) at the Jet Propulsion Laboratory to design, develop, and operate the Advanced Multimission Operations (AMMOS) multimission ground data system capabilities that are used to control operational spacecraft and process data returned from a variety of planetary missions. The AMMOS design is based on use of modular, networked capabilities and industry standard hardware and software. Individual missions adapt multimission tools and services to support ground data processing during spacecraft development and operations. Utilization of a multimission core capability significantly reduces the cost of development and operation of ground data systems for each individual project. This paper describes the AMMOS system, and the general purpose set of AMMOS multimission capabilities, services and tools that are used to support the NASA planetary program. These capabilities include mission planning and analysis tools, sequence generation tools, command processing, ephemeris generation and optical navigation capabilities, real time engineering and science data processing, monitor and display functions, spacecraft analysis systems, science instrument data processing and photoproduct generation capabilities, data acquisition and distribution services, and tools for production of archival science data records. The system is used to support multiple missions that are operating simultaneously. RP GREEN, WB (reprint author), CALTECH,JET PROPULS LAB,IMAGE PROC APPLICAT & DEV SECT,PASADENA,CA 91125, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 407 EP 415 DI 10.1016/0094-5765(95)00067-A PG 9 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700035 ER PT J AU REEVES, EM CRESSY, PJ AF REEVES, EM CRESSY, PJ TI NASA SCIENCE UTILIZATION PLANS FOR THE SPACE STATION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB The Mir-l and International Space Station Alpha capabilities present the science community with unique long duration platforms to conduct a wide range of scientific research in the microgravity and life sciences as well as in the observational sciences. NASA is developing plans to use the capabilities of Mir and Space Station as they emerge during the development of the orbital program. In both cases the planned science utilization programs take advantage of the volume, crew, power, microgravity and logistics resupply unique to each phase. The paper will present these utilization plans in the context of an evolving scientific program. RP REEVES, EM (reprint author), NASA,DIV FLIGHT SYST,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 447 EP 453 DI 10.1016/0094-5765(95)00079-F PG 7 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700039 PM 11541110 ER PT J AU STETSON, D VARSI, G AF STETSON, D VARSI, G TI SOLAR-SYSTEM EXPLORATION TECHNOLOGY REQUIREMENTS AND PLANNING PROCESS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 45th Congress of the International-Astronautical-Federation CY OCT 09-14, 1994 CL ISRAEL SOC AERONAUT & ASTRONAUT, JERUSALEM, ISRAEL SP Int Astronaut Federat, Int Acad Astronaut, Int Inst Space Law HO ISRAEL SOC AERONAUT & ASTRONAUT AB The NASA Office of Space Science, in alliance with the Office of Advanced Concepts and Technology, has developed an Integrated Technology Strategy to guide its investments in technology for space science missions. This strategy establishes goals and strategic objectives that ensure that NASA and the nation derive the greatest possible scientific and economic benefits from investments in space science missions and technologies. Within the Office of Space Science, the Solar System Exploration Division, in collaboration with the Office of Space Access and Technology, is developing a Technology Plan to implement these goals and to identify specific technology needs for solar system missions. This paper describes the philosophy, processes, and preliminary results of the systematic process being established for the identification and prioritization of solar system exploration technology needs. RP STETSON, D (reprint author), JET PROPULS LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1995 VL 37 SU S BP 455 EP 462 DI 10.1016/0094-5765(95)00081-A PG 8 WC Engineering, Aerospace SC Engineering GA RU257 UT WOS:A1995RU25700040 ER PT J AU Schneider, V Oganov, V LeBlanc, A Rakmonov, A Taggart, L Bakulin, A Huntoon, C Grigoriev, A Varonin, L AF Schneider, V Oganov, V LeBlanc, A Rakmonov, A Taggart, L Bakulin, A Huntoon, C Grigoriev, A Varonin, L TI Bone and body mass changes during space flight SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 11th Symposium on Man in Space CY MAR 27-31, 1995 CL TOULOUSE LABEGE, FRANCE SP Int Acad Astronaut, Ctr Natl Etudes Spatiales RP Schneider, V (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 4 TC 30 Z9 30 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT-DEC PY 1995 VL 36 IS 8-12 BP 463 EP 466 DI 10.1016/0094-5765(95)00131-X PG 4 WC Engineering, Aerospace SC Engineering GA UN647 UT WOS:A1995UN64700008 PM 11540977 ER PT J AU Waligora, JM Kumar, MS Kumar, KV AF Waligora, JM Kumar, MS Kumar, KV TI Energy utilization rates during shuttle extravehicular activities SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 11th Symposium on Man in Space CY MAR 27-31, 1995 CL TOULOUSE LABEGE, FRANCE SP Int Acad Astronaut, Ctr Natl Etudes Spatiales DE metabolic rates; extravehicular activities; space shuttle AB The work rates or energy utilization rates during EVA are major factors in sizing of life support systems. These rates also provide a measure of ease of EVA and its cost in crew fatigue. From the first Shuttle EVA on the STS-6 mission in 1983, we have conducted 59 man-EVA and 341 man-hours of EVA. Energy utilization rates have been measured on each of these EVA. Metabolic rate was measured during each EVA using oxygen utilization corrected for suit leakage. From 1981-1987, these data were available for average data over the EVA or over large segments of the EVA. Since 1987, EVA oxygen utilization data were available at 2-minute intervals. The average metabolic rate on Shuttle EVA (194 kcal/hr.) has been significantly lower than metabolic rates during Apollo and Skylab missions. Peak rates have been below design levels, infrequent, and of short duration. The data suggest that the energy cost of tasks may be inversely related to the degree of training for the task. The data provide insight on the safety margins provided by life support designs and on the energy cost of Station construction EVA. RP Waligora, JM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058, USA. NR 5 TC 10 Z9 11 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 OCT-DEC PY 1995 VL 36 IS 8-12 BP 595 EP 599 DI 10.1016/0094-5765(95)00147-6 PG 5 WC Engineering, Aerospace SC Engineering GA UN647 UT WOS:A1995UN64700024 PM 11540993 ER PT J AU Doerr, DF Convertino, VA Blue, J Wheeler, RM Knott, WM AF Doerr, DF Convertino, VA Blue, J Wheeler, RM Knott, WM TI Interaction between exercising humans and growing plants in a closed ecological life support system SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 11th Symposium on Man in Space CY MAR 27-31, 1995 CL TOULOUSE LABEGE, FRANCE SP Int Acad Astronaut, Ctr Natl Etudes Spatiales ID EXCHANGE AB The purpose of this Study was to quantify the gas exchange between plants growing in a Closed Environmental Life Support System (CELSS) and the metabolism of human subjects undergoing various levels of physical exercise, and subsequently determine the buffer characteristics in relation to the carbon exchange established for plants in this closed loop life support system. Two men (ages 42 and 45 yr) exercised on a cycle ergometer at three different work intensities, each on a separate day. The CELSS, a 113 m(3) chamber, was sized to meet the needs of one human. The plants, consisting of 20 m(2) of potato, provided oxygen to the human during an artificially lighted photosynthesis phase and the human provided CO2 to the plants. The average rates of exchange for the subjects were 0.88, 1.69, and 2.47 liters O-2/min and 0.77, 1.47 and 2.21 liters CO2/min at approximately 25%, 50%, and 75% of their maximal aerobic capacity, respectively. The photosynthetic rate for the CELSS was 0.95 liters/min. A balance between human CO2 production and plant utilization was noted at approximately the 50% VO(2)max level. The oxygen balance and changes were not within detectable limits of the CELSS instrumentation for the durations of these exercise exposures. If a CELSS environment is the methodology selected for long term spaceflight, it will be important to select plants that efficiently grow at the available light and nutrient levels while balancing the needs for the human crew at their levels of physical activity. RP Doerr, DF (reprint author), NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899, USA. NR 6 TC 2 Z9 3 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT-DEC PY 1995 VL 36 IS 8-12 BP 601 EP 605 DI 10.1016/0094-5765(95)00148-4 PG 5 WC Engineering, Aerospace SC Engineering GA UN647 UT WOS:A1995UN64700025 PM 11540994 ER PT J AU MARVIN, JG AF MARVIN, JG TI PERSPECTIVE ON COMPUTATIONAL FLUID-DYNAMICS VALIDATION SO AIAA JOURNAL LA English DT Article ID TRANSONIC-FLOWS; MODEL AB A comprehensive approach to computational fluid dynamics (CFD) validation is presented, Requirements from computational and experimental perspectives are given. Experimental validation is emphasized because it ultimately determines the accuracy of CFD modeling and its application to complex problems. The concepts of building block and benchmark experiments are introduced, The types of measurements required of these experiments and their accuracy determination are explained, Contributions from such experiments toward the development and validation of CFD are reviewed and examples provided. Future challenges and strategies for validation are discussed. RP MARVIN, JG (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 52 TC 8 Z9 8 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1995 VL 33 IS 10 BP 1778 EP 1787 DI 10.2514/3.12727 PG 10 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500003 ER PT J AU EKATERINARIS, JA AF EKATERINARIS, JA TI NUMERICAL INVESTIGATION OF DYNAMIC STALL OF AN OSCILLATING WING SO AIAA JOURNAL LA English DT Article ID TURBULENCE; AIRFOIL; MODEL AB The unsteady three-dimensional flowfield over an oscillating wing is investigated with the numerical solution of the compressible, time-dependent, Reynolds-averaged Navier-Stokes equations. Spatial discretization is performed with a third order accurate, upwind-biased, vertex-based, finite volume scheme. An alternative direction implicit, iterative scheme is used for the time Integration. The high Reynolds number turbulent flow behavior is modeled with a one equation turbulence model, The effect of subiterations, time step and grid density on the accuracy of the computed solutions is investigated. It is found that scaling of the time step with the angular velocity of the motion produces accurate solutions at a reduced computational cost. The computational domain over an aspect ratio 5 wing with rounded tip and NACA-0015 airfoil sections is discretized with a single-block grid, The light stall flowfield over the wing oscillating in a subsonic freestream with a mean angle of attack of 11 deg and an amplitude of 4.2 deg is computed. The structure of the separated, unsteady flowfield is investigated and comparisons with available experimental data are performed. RP EKATERINARIS, JA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 35 TC 24 Z9 24 U1 1 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 OCT PY 1995 VL 33 IS 10 BP 1803 EP 1808 DI 10.2514/3.12730 PG 6 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500006 ER PT J AU KAO, KH LIOU, MS AF KAO, KH LIOU, MS TI ADVANCE IN OVERSET GRID SCHEMES - FROM CHIMERA TO DRAGON GRIDS SO AIAA JOURNAL LA English DT Article ID PARTIAL-DIFFERENTIAL EQUATIONS; COMPOSITE AB A new approach that uses nonstructured mesh to replace the arbitrarily overlapped structured regions of embedded grids is presented. The present methodology uses the Chimera overlapped structured grids that are independently generated and body fitted, yielding a high-quality grid readily accessible for efficient solution schemes. A hybrid grid scheme is then proposed that maximizes the advantages of the Chimera scheme and adapts the strengths of the unstructured grid while at the same time keeps its weaknesses minimal. This new adaptation to the Chimera thinking is the direct replacement of arbitrary grid overlapping by nonstructured (DRAGON) grid, The nonstructured grid region sandwiched between the structured grids is limited in size, resulting in only a small increase in memory and computational effort. The DRAGON grid method has three important advantages: 1) preserving strengths of the Chimera grid, 2) eliminating difficulties sometimes encountered in the Chimera scheme, and 3) making grid communication in a fully conservative and consistent manner insofar as the governing equations are concerned. Numerical results on representative two-dimensional steady and unsteady inviscid flows are demonstrated. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP KAO, KH (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135, USA. NR 30 TC 22 Z9 22 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 OCT PY 1995 VL 33 IS 10 BP 1809 EP 1815 DI 10.2514/3.12921 PG 7 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500007 ER PT J AU OLLIVIERGOOCH, CF AF OLLIVIERGOOCH, CF TI MULTIGRID ACCELERATION OF AN UPWIND ENTER SOLVER ON UNSTRUCTURED MESHES SO AIAA JOURNAL LA English DT Article ID EULER EQUATIONS AB Multigrid acceleration has been implemented for an upwind how solver on unstructured meshes, The Row solver is a straightforward implementation of Earth and Jespersen's unstructured scheme, with least-squares linear reconstruction and a directional implementation of Venkatakrishnan's limiter The multigrid scheme itself is designed to work on mesh systems that are not nested, allowing great flexibility in generating coarse meshes and in adapting fine meshes, A new scheme for automatically generating coarse unstructured meshes from fine ones is presented, A subset of the fine mesh vertices is selected for retention in the coarse mesh, The coarse mesh is generated incrementally from the fine mesh by removing one rejected vertex at a time, In this way, a valid coarse mesh triangulation is guaranteed, Factors affecting multigrid convergence rate for inviscid flow are thoroughly examined, including the effect of the number of coarse meshes used, the type of multigrid cycle employed, the spatial discretization used on coarse meshes, and the nature of the flow, The present multigrid scheme is very successful in reducing computational time for inviscid flows in the subsonic and transonic regime. RP OLLIVIERGOOCH, CF (reprint author), NASA,AMES RES CTR,NATL RES COUNCIL,MAIL STOP T27B,MOFFETT FIELD,CA 94035, USA. RI Ollivier-Gooch, Carl/E-8934-2011 OI Ollivier-Gooch, Carl/0000-0001-6514-058X NR 23 TC 13 Z9 14 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1995 VL 33 IS 10 BP 1822 EP 1827 DI 10.2514/3.12733 PG 6 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500009 ER PT J AU AMBUR, DR STARNES, JH AF AMBUR, DR STARNES, JH TI LOW-SPEED IMPACT DAMAGE-INITIATION CHARACTERISTICS OF SELECTED LAMINATED COMPOSITE PLATES SO AIAA JOURNAL LA English DT Article ID INDUCED FRACTURE AB The results of an experimental and analytical study of damage initiation in laminated composite plates subjected to low-speed impact are presented. Here, 8, 16-, 24-, 32-, and 48-ply-thick quasi-isotropic and orthotropic graphite-epoxy and graphite-bismaleimide laminated plates have been impacted with dropped weights and the corresponding plate responses have been predicted analytically, Impact damage-initiation thresholds and damage initiation mechanisms corresponding to a range of impact-energy levels are identified. Impact-damage initiation for the thicker plates occurs at both the impact site and the plate surface opposite to the impact site. Impact-damage initiation for the thinner plates is predominately due to tensile fracture on the plate surface opposite to the impact site. Three-dimensional stress states that correspond to the impact conditions that initiate damage are determined analytically to help identify damage-initiation mechanisms and to predict failure-initiation modes. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. RP AMBUR, DR (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 15 TC 11 Z9 12 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1995 VL 33 IS 10 BP 1919 EP 1925 DI 10.2514/3.12746 PG 7 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500022 ER PT J AU ISSAC, JC KAPANIA, RK BARTHELEMY, JFM AF ISSAC, JC KAPANIA, RK BARTHELEMY, JFM TI SENSITIVITY OF FLUTTER RESPONSE OF A WING TO SHAPE AND MODAL PARAMETERS SO AIAA JOURNAL LA English DT Note C1 NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,MULTIDISCIPLINARY DESIGN OPTIMIZAT BRANCH,HAMPTON,VA 23681. RP ISSAC, JC (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,BLACKSBURG,VA 24061, USA. NR 3 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1995 VL 33 IS 10 BP 1983 EP 1986 DI 10.2514/3.12758 PG 4 WC Engineering, Aerospace SC Engineering GA RY965 UT WOS:A1995RY96500034 ER PT J AU HARVEY, AD LEE, CK ROGERS, SE AF HARVEY, AD LEE, CK ROGERS, SE TI STEADY-STATE MODELING AND EXPERIMENTAL-MEASUREMENT OF A BAFFLED IMPELLER STIRRED-TANK SO AICHE JOURNAL LA English DT Article AB An approximate steady-state method is devised for computing the flow field in a baffled impeller-stirred tank reactor. The flow field in a cylindrical tank with a 45 degrees pitched-blade impeller rotating at 100 rpm and four stationary rectangular side-wall baffles is simulated using a new approximate steady-state approach. The method provides an alternative to a full unsteady Navier- Stokes simulation. The new steady-state analysis involves accurately defining the geometry of the miring tank using a multiblock grid technique. The flow is solved from a rotating frame of reference for a single position of the impeller relative to the side-wall baffles. The steady-state numerical results are then spatially averaged and compared with time-averaged data obtained experimentally using laser Doppler velocimetry (LDV). Spatially averaged numerical predictions obtained using this approximate steady-state method for the radial and axial velocity components agree well with the LDV data. The predicted magnitude of the tangential velocity component, however, is higher than the experimentally measured values. Closer agreement of the tangential velocities with experimental values is obtained using a finer grid and it is found that a relatively fine grid is needed for accurately predicting the tangential velocity magnitude. Use of this approximate steady-state method allows designers of mixing vessels to obtain flow-field results for baffled vessels much more efficiently than using full unsteady Navier-Stokes simulations. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HARVEY, AD (reprint author), DOW CHEM CO USA,PLAQUEMINE,LA 70765, USA. NR 10 TC 54 Z9 58 U1 0 U2 2 PU AMER INST CHEMICAL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0001-1541 J9 AICHE J JI AICHE J. PD OCT PY 1995 VL 41 IS 10 BP 2177 EP 2186 DI 10.1002/aic.690411002 PG 10 WC Engineering, Chemical SC Engineering GA RY080 UT WOS:A1995RY08000001 ER PT J AU GRUNTHANER, FJ RICCO, AJ BUTLER, MA LANE, AL MCKAY, CP ZENT, AP QUINN, RC MURRAY, B KLEIN, HP LEVIN, GV TERHUNE, RW HOMER, ML KSENDZOV, A NIEDERMANN, P AF GRUNTHANER, FJ RICCO, AJ BUTLER, MA LANE, AL MCKAY, CP ZENT, AP QUINN, RC MURRAY, B KLEIN, HP LEVIN, GV TERHUNE, RW HOMER, ML KSENDZOV, A NIEDERMANN, P TI INVESTIGATING THE SURFACE-CHEMISTRY OF MARS SO ANALYTICAL CHEMISTRY LA English DT Article ID FIBER OPTIC MICROMIRROR; FILMS; LIFE C1 SANDIA NATL LABS,DEPT MICROSENSOR RES & DEV,TECH STAFF,ALBUQUERQUE,NM 87185. CALTECH,JET PROP LAB,NANOTECHNOL & SCI GRP,PASADENA,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SANTA CLARA UNIV,SANTA CLARA,CA 95053. BIOSPHER INC,SAN DIEGO,CA. CALTECH,JET PROP LAB,SEMICOND SENSOR TECHNOL GRP,TECH STAFF,PASADENA,CA. RI Ricco, Antonio/A-5273-2010 FU NIDCR NIH HHS [DE-AC04-94AL85000] NR 15 TC 10 Z9 10 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD OCT 1 PY 1995 VL 67 IS 19 BP A605 EP A610 PG 6 WC Chemistry, Analytical SC Chemistry GA RX222 UT WOS:A1995RX22200004 PM 11536721 ER PT J AU RYABENKII, VS TSYNKOV, SV AF RYABENKII, VS TSYNKOV, SV TI AN EFFECTIVE NUMERICAL TECHNIQUE FOR SOLVING A SPECIAL-CLASS OF ORDINARY DIFFERENCE-EQUATIONS SO APPLIED NUMERICAL MATHEMATICS LA English DT Article AB We consider a system of ordinary difference equations with constant coefficients, which is defined on an infinite one-dimensional mesh. The right-hand side (RHS) of the system is compactly supported, therefore, the system appears to be homogeneous outside some finite mesh interval. At infinity, we impose certain boundary conditions, e.g., conditions of boundedness or decay of the solution, so that the resulting boundary-value problem is uniquely solvable and well posed. We also consider a truncation of this infinite-domain problem to some finite mesh interval that entirely contains the support of the RHS. We require that the solution to this truncated problem, which is the one we are going to actually calculate, coincides on the finite mesh interval where it is defined with the corresponding fragment of the solution to the original (infinite) problem. This requirement necessitates setting some special boundary conditions at the ends of the aforementioned finite interval. In so doing, one should guarantee an exact transfer of boundary conditions from infinity through the (semi-infinite) intervals of homogeneity of the original system. It turns out that the desired boundary conditions at the ends of the finite interval can be naturally formulated in terms of the eigen subspaces of the system operator. This, in turn, enables us to develop an effective numerical algorithm for solving the system of ordinary difference equations on the finite mesh interval. This algorithm can be referred to as a version of the well-known successive substitution technique but without its final (''inverse'' or ''resolving'') stage. The special class of systems described in this paper appears to be most useful when constructing highly accurate artificial boundary conditions (ABCs) for the numerical treatment of problems initially formulated on unbounded domains. Therefore, an effective numerical algorithm for solving such systems becomes an important issue. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP RYABENKII, VS (reprint author), RUSSIAN ACAD SCI,MV KELDYSH APPL MATH INST,MIUSSKAYA SQ 4,MOSCOW 125047,RUSSIA. NR 9 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD OCT PY 1995 VL 18 IS 4 BP 489 EP 501 DI 10.1016/0168-9274(95)00081-5 PG 13 WC Mathematics, Applied SC Mathematics GA TG565 UT WOS:A1995TG56500005 ER PT J AU LEVITON, DB WRIGHT, GA THOMAS, RJ DAVILA, JM EPSTEIN, GL AF LEVITON, DB WRIGHT, GA THOMAS, RJ DAVILA, JM EPSTEIN, GL TI PERFORMANCE COMPARISON OF 2 WOLTER TYPE-II TELESCOPES IN THE FAR-ULTRAVIOLET SO APPLIED OPTICS LA English DT Article DE GLANCING-INCIDENCE TELESCOPES; EXTREME-UV TELESCOPES; SOLAR TELESCOPES; IMAGE TESTING ID SOLAR CORONA AB Experimental results for image quality and scatter in far-UV light are used to choose between the conventionally polished Solar Extreme-Ultraviolet Rocket Telescope and Spectrograph (SERTS-A) and computer-controlled polished SERTS-C Welter type II solar rocket telescopes for an extreme-UV flight instrument. In 124-nm light the SERTS-C telescope image had a 0.67-arcsec full width at half-maximum (FWHM), compared with a 1.25-arcsec FWHM for the SERTS-A telescope. In addition SERTS-C had twice the peak irradiance of SERTS-A and an order of magnitude lower near-angle scatter. The inflight performance of the telescopes is consistent with laboratory findings. C1 NASA,GODDARD SPACE FLIGHT CTR,SOLAR PHYS BRANCH,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ORBITING SOLAR LAB,GREENBELT,MD 20771. RP LEVITON, DB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OPT RES SECT,GREENBELT,MD 20771, USA. NR 12 TC 1 Z9 1 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 OCT 1 PY 1995 VL 34 IS 28 BP 6459 EP 6464 PG 6 WC Optics SC Optics GA RW227 UT WOS:A1995RW22700020 PM 21060495 ER PT J AU PILDIS, RA BREGMAN, JN SCHOMBERT, JM AF PILDIS, RA BREGMAN, JN SCHOMBERT, JM TI DEEP OPTICAL OBSERVATIONS OF COMPACT-GROUPS OF GALAXIES SO ASTRONOMICAL JOURNAL LA English DT Article ID CCD SURFACE PHOTOMETRY; ELLIPTICAL GALAXIES; NGC-2300 GROUP; RADIO-SOURCES; DARK MATTER; EVOLUTION; MERGERS; MORPHOLOGY; EMISSION; DYNAMICS AB Compact groups of galaxies appear to be extremely dense, making them likely sites of intense galaxy interaction, while their small populations make them relatively simple to analyze. In order to search for optical interaction tracers such as diffuse light and galaxy tidal features in Hickson compact groups (HCGs), we carried out deep photometry in three filters on a sample of HCCs with ROSAT observations. Using a modeling procedure to subtract the light of bright early-type galaxies, we found shell systems and extended envelopes around many, but not all, of those galaxies. Only one group in our sample, HCG 94, has diffuse light in the group potential (with a luminosity of 7 L*); the other groups do not contain more than 1/3 L* in diffuse light. With the exception of HCG 94 (which is the most x-ray-luminous HCG), we found no correlation between the presence of shells or other tidal features and the x-ray luminosity of a group. Better predictors of detectable group x-ray emission are a low spiral fraction and belonging to a larger galaxy condensation-neither of which are correlated with optical disturbances in the group galaxies. Two elliptical galaxies that are extremely optically luminous but x-ray faint are found to have shells and very complex color structures. This is likely due to recent infall of gas-rich material into the galaxies, which would produce both the disruption of stellar orbits and a significant amount of star formation. (C) 1995 American Astronomical Society. C1 UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NR 55 TC 38 Z9 38 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1995 VL 110 IS 4 BP 1498 EP & DI 10.1086/117623 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RZ271 UT WOS:A1995RZ27100004 ER PT J AU WHITNEY, JH OCONNELL, RW ROOD, RT HILL, RS LANDSMAN, WB BOHLIN, RC ROBERTS, MS SMITH, AM STECHER, TP AF WHITNEY, JH OCONNELL, RW ROOD, RT HILL, RS LANDSMAN, WB BOHLIN, RC ROBERTS, MS SMITH, AM STECHER, TP TI FAR-ULTRAVIOLET LUMINOSITY FUNCTIONS FOR THE GLOBULAR-CLUSTERS M3 AND M13 SO ASTRONOMICAL JOURNAL LA English DT Article ID UV-BRIGHT STARS; STELLAR POPULATIONS; HORIZONTAL BRANCH; ELLIPTIC GALAXIES; IMAGING TELESCOPE; IUE OBSERVATIONS; EVOLUTION AB Far-ultraviolet images of the globular clusters M3 (NGC 5272) and M13 (NGC 6205) obtained with the Ultraviolet Imaging Telescope during the 1990 December Astro-1 mission are presented. 74 sources are detected down to an FUV limiting magnitude of 16.0 in M3, and 56 sources to magnitude 14.2 in M13. Although the two clusters are similar in total population, luminosity, and metallicity, M13 has a much larger population of stars with FUV magnitudes brighter than the zero age horizontal branch. The relative numbers of UV-bright stars in the two clusters are in good agreement with theoretical post-HB evolutionary tracks for normal, non-binary stars given the amount of red giant branch mass loss inferred from the optical color-magnitude diagrams. (C) 1995 American Astronomical Society. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP WHITNEY, JH (reprint author), UNIV VIRGINIA,DEPT ASTRON,POB 3818,CHARLOTTESVILLE,VA 22903, USA. NR 27 TC 6 Z9 6 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1995 VL 110 IS 4 BP 1722 EP 1727 DI 10.1086/117644 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RZ271 UT WOS:A1995RZ27100025 ER PT J AU FOMENKOVA, MN JONES, B PINA, R PUETTER, R SARMECANIC, J GEHRZ, R JONES, T AF FOMENKOVA, MN JONES, B PINA, R PUETTER, R SARMECANIC, J GEHRZ, R JONES, T TI MIDINFRARED OBSERVATIONS OF THE NUCLEUS AND DUST OF COMET P/SWIFT-TUTTLE SO ASTRONOMICAL JOURNAL LA English DT Article ID EMISSION; P/HALLEY; HALLEY; AREAS; GAS AB We report pre-perihelion observations of comet P/Swift-Tuttle obtained with the UCSD mid-infrared astronomical camera on 12 nights in November 1992. The images were taken through a 1 mu m wide filter centered at 11.65 mu m. During the observing run, the heliocentric distance decreased from 1.13 to 0.98 AU, and the geocentric distance increased from 1.16 to 1.33 AU. The spatial scale of the images was 700-800 km per pixel. In addition, photometric data at wavelengths between 3.6 and 18.5 mu m were obtained on one night. The infrared images cover the cometary activity on time scales from hours to weeks and reveal large changes in the overall morphology of the coma. From periodic changes in the jet patterns we determined the period of nuclear rotation of 67.5+/-0.4 h. Photometry indicates that the temperature of the coma was 35% higher than the blackbody temperature at the same heliocentric distance and, hence, that the coma was dominated by small particles of average radius of 0.7 mu m. The dust mass loss rate varied with the R(-6.3) and displayed similar to 40% variation with the rotational phase. Two major jets were heliocentric distance as R present in the images obtained on November 07-17, and a third area became active on November 24-29, increasing the average dust loss rate by a factor of 1.4. The relative positions of the three active areas on the surface of the nucleus are consistent with the positions of the most stable active zones identified by Sekanina [AJ, 86, 1741 (1981)] from the data on the P/Swift-Tuttle apparition in 1862. The radial brightness profiles suggest the radius of the nucleus is 15+/-3 km. This implies that the nucleus of P/Swift-Tuttle is similar to 34 times more massive than the nucleus of P/Halley. (C) 1995 American Astronomical Society. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. UNIV MINNESOTA,DEPT ASTRON,MINNEAPOLIS,MN 55455. RP FOMENKOVA, MN (reprint author), NASA,AMES RES CTR,MS 239-4,MOFFETT FIELD,CA 94035, USA. NR 40 TC 14 Z9 14 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1995 VL 110 IS 4 BP 1866 EP & DI 10.1086/117657 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RZ271 UT WOS:A1995RZ27100038 ER PT J AU GREINER, J SOMMER, M BADE, N FISHMAN, GJ HANLON, LO HURLEY, K KIPPEN, RM KOUVELIOTOU, C PREECE, R RYAN, J SCHONFELDER, V WILLIAMS, OR BOER, M NIEL, M AF GREINER, J SOMMER, M BADE, N FISHMAN, GJ HANLON, LO HURLEY, K KIPPEN, RM KOUVELIOTOU, C PREECE, R RYAN, J SCHONFELDER, V WILLIAMS, OR BOER, M NIEL, M TI THE GAMMA-RAY BURST GB-920622 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GAMMA-RAY BURSTS; COUNTERPARTS ID TELESCOPE; ABOARD AB We have analyzed the Ulysses, BATSE, and COMPTEL spectral data from the gamma-ray burst of June 22, 1992 (GB 920622). COMPTEL data reveal a hard to soft evolution within the first pulse of the burst, while the mean hardness ratios of the three pulses are the same. Unlike the single instrument spectra, the composite spectrum of GB 920622 averaged over the total burst duration ranging from 20 keV up to 10 MeV cannot be fit by a single power law. Instead, the spectrum shows continuous curvature across the full energy range. COMPTEL imaging and BATSE/Ulysses triangulation constrain the source location of GB 920622 to a ring sector 1.1 arcmin wide and 2 degrees long. This area has been searched for quiescent X-ray sources using ROSAT survey data collected about two years before the burst. After the optical identification of the X-ray sources in and near the GRB location we conclude that no quiescent X-ray counterpart candidate for GB 920622 has been found. C1 HAMBURG OBSERV, D-21029 HAMBURG, GERMANY. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. EUROPEAN SPACE AGCY, EUROPEAN SPACE RES & TECHNOL CTR, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS. UNIV NEW HAMPSHIRE, CTR SPACE SCI, DURHAM, NH 03824 USA. CTR ETUD SPATIALE RAYONNEMENTS, F-31029 TOULOUSE, FRANCE. RP GREINER, J (reprint author), MAX PLANCK INST EXTRATERR PHYS, D-85740 GARCHING, GERMANY. NR 29 TC 14 Z9 16 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 1995 VL 302 IS 1 BP 121 EP 132 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RZ170 UT WOS:A1995RZ17000016 ER PT J AU COTTON, WD TODY, D PENCE, WD AF COTTON, WD TODY, D PENCE, WD TI BINARY TABLE EXTENSION TO FITS SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE TECHNIQUES, MISCELLANEOUS IMAGE PROCESSING AB This paper describes the FITS binary tables which are a flexible and efficient means of transmitting a wide variety of data structures. Table rows may be a mixture of a number of numerical, logical and character data entries. In addition, each entry is allowed to be a single dimensioned array. Numeric data are kept in binary formats. The definition of the binary tables contained in this paper has been approved by formal vote of the IAU FITS Working Group, and is a part of the IAU FITS standards. C1 NATL OPT ASTRON OBSERV, TUCSON, AZ 85726 USA. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP NATL RADIO ASTRON OBSERV, 520 EDGEMONT RD, CHARLOTTESVILLE, VA 22903 USA. NR 5 TC 36 Z9 36 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 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD OCT PY 1995 VL 113 IS 1 BP 159 EP 166 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RX216 UT WOS:A1995RX21600013 ER PT J AU MALBET, F BERTOUT, C AF MALBET, F BERTOUT, C TI DETECTING T-TAURI DISKS WITH OPTICAL LONG-BASE-LINE INTERFEROMETRY SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE ACCRETION DISKS; TECHNIQUES, INTERFEROMETRIC; STARS, CIRCUMSTELLAR MATTER; STARS, IMAGING; STARS, PRE-MAIN SEQUENCE; INFRARED, STARS ID ACCRETION DISKS; FORBIDDEN-LINE; CIRCUMSTELLAR DISKS; STARS; PROFILES; EMISSION; SPECTRA AB We present synthetic images of disks around T Tauri stars. We calculate visibility curves in order to study the possibility of directly detecting thermal emission from T Tauri disks. Total fluxes of T Tauri disks are compared to the sensitivity of VISA, the interferometric sub-array of the European Very Large Telescope. We conclude that thermal emission from circumstellar disk around T Tauri stars is detectable with current or soon-to-be interferometric techniques at wavelengths longer than 2.2 mu m. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP MALBET, F (reprint author), OBSERV GRENOBLE,ASTROPHYS LAB,BP 53,F-38041 GRENOBLE,FRANCE. NR 24 TC 30 Z9 30 U1 1 U2 1 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 OCT PY 1995 VL 113 IS 2 BP 369 EP 377 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TA337 UT WOS:A1995TA33700011 ER PT J AU AMENDOLA, L GOTTLOBER, S MUCKET, JP MULLER, V AF AMENDOLA, L GOTTLOBER, S MUCKET, JP MULLER, V TI MATTER DISTRIBUTION FOR POWER SPECTRA WITH BROKEN SCALE-INVARIANCE SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, THEORY; LARGE-SCALE STRUCTURE OF UNIVERSE; METHODS, NUMERICAL ID DARK-MATTER; REDSHIFT SURVEY; GALAXIES; UNIVERSE; FLUCTUATIONS; SIMULATIONS; STATISTICS; SKEWNESS; MODELS; SPACE AB To test the primordial power spectra predicted by a double inflationary model with a break of amplitude Delta = 3 at a scale of 2 pi/k approximate to 10 h(-1) Mpc and cold dark matter (CDM) as dominant matter content, we perform particle-mesh simulations with 128(3) particles on a 256(3) grid. The broken scale invariance of the power spectra explains the extra power observed in the large-scale matter distribution. COBE-normalized spectra and a linear biasing with b approximate to 2 are shown to reproduce the reconstructed power spectra from the CfA catalog. By identifying galactic halos with a random selection of particles in overdensity regions of approximately 2 times the cell variance, we can fit the angular correlation function using both the Limber equation and creating an APM-like angular projection with the observed luminosity function. Finally, the higher order moments of the galaxy distribution are shown to fit reasonably well the observed values. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. ASTROPHYS INST POTSDAM,D-14482 POTSDAM,GERMANY. RP AMENDOLA, L (reprint author), OSSERV ASTRON ROMA,VIALE PARCO MELLINI 84,I-00136 ROME,ITALY. NR 41 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1995 VL 451 IS 2 BP 444 EP 450 DI 10.1086/176233 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV626 UT WOS:A1995RV62600004 ER PT J AU LOWENTHAL, JD HOGAN, CJ GREEN, RF WOODGATE, B CAULET, A BROWN, L BECHTOLD, J AF LOWENTHAL, JD HOGAN, CJ GREEN, RF WOODGATE, B CAULET, A BROWN, L BECHTOLD, J TI IMAGING AND SPECTROSCOPY OF DAMPED LY-ALPHA QUASI-STELLAR OBJECT ABSORPTION-LINE CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE QUASARS, ABSORPTION LINES ID RADIO-QUIET GALAXY; STAR FORMATION; HIGH-REDSHIFT; DISK GALAXIES; METAL ENRICHMENT; PRIMEVAL GALAXY; EMISSION; SYSTEMS; ABSORBER; DUST AB We present the results of a multifaceted search for line emission from the vicinities of high-redshift quasistellar object (QSO) absorption-line clouds, most of them damped Ly alpha systems at z greater than or similar to 2. Seven fields containing QSOs with known intervening damped Ly alpha absorbers were imaged with the GSFC Fabry-Perot Imager to search for diffuse redshifted Ly alpha. Apart from the one Ly alpha companion galaxy reported previously, no confirmed extended Ly alpha emission was detected down to 3 sigma flux levels of around 3 x 10(-17) ergs s(-1) cm(-2), corresponding to star formation rates less than or similar to 1 M. yr(-1), assuming case B recombination, a reasonable initial mass function, and negligible extinction by dust. One of the damped Ly alpha systems studied here, toward Q0836+113, has been reported to show faint, extended Ly alpha emission. While our Ly alpha images of that held are not sensitive enough to confirm the reported flux levels, we did detect and spectroscopically confirm redshifted [O II] lambda 3727 and continuum emission from a closer intervening system, a Mg II system at z = 0.788, at the same spatial position as the reported Ly alpha emission from the more distant object, and we suggest the possibility that all the observations of this field can be explained by the closer system alone. Six damped Ly alpha systems, including two that were imaged with the Fabry-Perot, were also imaged with two-dimensional long-slit CCD spectroscopy at similar to 2 Angstrom resolution in the core of the Ly alpha absorption line. No convincing Ly alpha emission was found from any of the systems, including Q0836+113, for which our sensitivity was again insufficient to confirm the previously reported extended Ly alpha emission. However, there is yet another independent claim of Ly alpha emission from that cloud, but spatially unresolved, in conflict with the report of extended emission; our observations do not reproduce the report of compact Ly alpha emission, which should have appeared at about the 7 sigma level. Although observationally allowable quantities of dust in the damped Ly alpha clouds can in some cases quench Ly alpha flux by up to several orders of magnitude, several of the damped clouds studied here are arguably metal and dust poor, leading us to believe that our limits on Ly alpha emission generally constrain the star formation rates to be less than or similar to 10 M. yr(-1), comparable to normal Sc galaxies today. Whatever their exact nature, the damped Ly alpha clouds therefore appear not to be spectacular primeval galaxies seen in the act of forming a galaxy's worth of stars. C1 KITT PEAK NATL OBSERV,TUCSON,AZ. CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. NATL OPT ASTRON OBSERV,TUCSON,AZ 85732. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ESO,SPACE TELESCOPE EUROPEAN COORDINATING FACIL,W-8064 GARCHING,GERMANY. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. RP LOWENTHAL, JD (reprint author), UNIV CALIF SANTA CRUZ,UNIV CALIF OBSERV,LICK OBSERV,SANTA CRUZ,CA 95064, USA. NR 62 TC 52 Z9 52 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1995 VL 451 IS 2 BP 484 EP 497 DI 10.1086/176237 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV626 UT WOS:A1995RV62600008 ER PT J AU MARSH, KA VANCLEVE, JE MAHONEY, MJ HAYWARD, TL HOUCK, JR AF MARSH, KA VANCLEVE, JE MAHONEY, MJ HAYWARD, TL HOUCK, JR TI SPATIALLY-RESOLVED MIDINFRARED OBSERVATIONS OF CIRCUMSTELLAR DUST AROUND AB AURIGAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, INDIVIDUAL (AB AURIGAE); STARS, PRE-MAIN-SEQUENCE ID T-TAURI STARS; COMPANIONS AB The Herbig Ae star, AB Aur, was observed at wavelengths of 11.7 and 17.9 mu m using the Cornell SpectroCam-10 imaging spectrometer on the 5 m Hale Telescope. The observed images were deconvolved using a Bayesian estimator which provided superresolution from the incorporation of prior information (the positivity of intensity and the finite support of the emission); this yielded an angular resolution of similar to 0.'' 2, which subtends similar to 30 AU at a distance of 160 pc. Our deconvolved images have resolved the source at both wavelengths and show source diameters of approximately 40 and 80 AU at 11.7 and 17.9 mu m, respectively. At 11.7 mu m, the source exhibits some complex structure which has been confirmed using observations on two separate observing runs and different observing techniques; one characteristic of this structure is the presence of a central depression. The source appearance is markedly different at 17.9 mu m and is characterized by a central component which is flanked by a pair of weaker, diametrically opposed features suggestive of an edge-on disk. We hypothesize that such a disk surrounds a tenuous, roughly spherical cloud which produces the silicate emission feature and which dominates the 11.7 mu m emission. C1 CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. RP MARSH, KA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 246-101,PASADENA,CA 91109, USA. NR 9 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 OCT 1 PY 1995 VL 451 IS 2 BP 777 EP 783 DI 10.1086/176264 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV626 UT WOS:A1995RV62600035 ER PT J AU ROBINSON, RD CARPENTER, KG PERCIVAL, JW BOOKBINDER, JA AF ROBINSON, RD CARPENTER, KG PERCIVAL, JW BOOKBINDER, JA TI A SEARCH FOR MICROFLARING ACTIVITY ON DME FLARE STARS .1. OBSERVATIONS OF THE DM8E STAR CN LEONIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACTIVITY; STARS, FLARE; STARS, INDIVIDUAL (CN LEONIS); ULTRAVIOLET, STARS ID X-RAY-EMISSION; SOLAR-FLARES; ENERGY-RELEASE; VARIABILITY; EXOSAT; AVALANCHES; DYNAMICS; CORONAE; FIELDS; REGION AB Microflares are frequent, short-duration, energetically weak disturbances occurring in the nonradiatively heated regions of the Sun and other magnetically active stars. They are thought to be the low-energy extension of hares commonly seen on active dMe stars and may be a major source of heating the chromosphere and corona of cool stars in general. In this paper we describe rapid time sequence UV photometry of the dMe star CN Leo taken with the High Speed Photometer (HSP) aboard the Hubble Space Telescope (HST). The filter was centered at 240 nm, near wavelengths at which flares are expected to have maximum intensity and the stellar background is small. During 2 hr of on-source observing, a total of 32 flarelike events were detected, with integrated counts ranging from 12 to more than 14,000. In most cases the events had integrated energy ranging between 10(27) and 10(28) ergs and can be classified as microflares. A considerable fine structure was seen in these events, with substantial variations sometimes occurring on timescales of less than 1 s. The occurrence rates for the smaller events showed a power-law distribution, with a slope comparable to that seen for larger events observed from the ground. Extrapolating the occurrence rate relation to nanoflare energies indicates a predicted count rate that is significantly smaller than that observed, suggesting that the nanoflares have a different energy distribution than the larger events. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. SMITHSONIAN ASTROPHYS OBSERV, CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV WISCONSIN, SPACE ASTRON LAB, MADISON, WI 53706 USA. RP GODDARD SPACE FLIGHT CTR, COMP SCI CORP, ASTRON PROGRAM, CODE 681, GREENBELT, MD 20771 USA. RI Carpenter, Kenneth/D-4740-2012 NR 38 TC 30 Z9 30 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1995 VL 451 IS 2 BP 795 EP 805 DI 10.1086/176266 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV626 UT WOS:A1995RV62600037 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI A PERIOD-LUMINOSITY RELATION FOR THE SLOW VARIATIONS OF LUMINOUS BLUE VARIABLES SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EVOLUTION; STARS, OSCILLATIONS; STARS, VARIABLES, OTHER ID S-DORADUS VARIABLES; P-CYGNI; MASS-LOSS; ETA-CARINAE; STARS; STABILITY; DOR; AMPLITUDE; OPACITY; LIMIT AB The slow (annual-to-decadal) cycles of light and color variation displayed by many luminous blue variables show mean ''periods'' that are inversely proportional to the stars' luminosities. New theoretical evolutionary tracks reveal that very massive stars undergo repeated mass outbursts due to quasi-secular oscillations of the stellar envelope between dynamically stable and unstable states, at the observed locations of LBVs at quiescence in the H-R diagram. Within the estimated errors, the models correctly predict the observed ''periods,'' eruption mass-loss rates, and lack of dependence of these rates on the stars' luminosities. During a cycle the models shift nearly imperceptibly on the H-R diagram. Observed variations of light and color in the LBVs are therefore probably attributable to changes in size of the optically thick ejected cloud. An earlier phase of stronger dynamical instability is predicted to have led to the ejection of huge circumstellar shells, whose computed masses scale with stellar luminosity in roughly the manner observed for massive old nebulae surrounding LBVs. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 43 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1995 VL 451 IS 2 BP L61 EP L64 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV627 UT WOS:A1995RV62700005 ER PT J AU VELUSAMY, T KUIPER, TBH LANGER, WD AF VELUSAMY, T KUIPER, TBH LANGER, WD TI CCS OBSERVATIONS OF THE PROTOSTELLAR ENVELOPE OF B335 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (B335); ISM, MOLECULES; STARS, FORMATION ID SMALL-SCALE STRUCTURE; STAR FORMATION; CHEMISTRY; COLLAPSE; CLOUDS AB We present single-dish and interferometric spectral line observations of CCS at 22 GHz toward the core of B335, a classical example of a young protostellar region. We combined the VLA and DSN 70 m observations to produce high-resolution (6 '' and 12 '') channel maps at 0.04 km s(-1) velocity intervals. These maps image for the first time the collapsing envelope around the protostar. These show that CCS emission arises primarily from the outer parts of the collapsing envelope down to half the infall radius and that CCS is clumpy throughout the core. LVG excitation analysis indicates that X(CCS) is similar to 3 x 10(-9) in the outer envelope and less than 5 x 10(-11) in the center of the infall region. The absence of CCS in the interior could be due to time-dependent chemical evolution. The velocity structure supports the evidence for inside-out collapse and the high-velocity features are consistent with accretion onto a rotating central disk. The asymmetric clumpy distribution of CCS emission implies that the physical conditions are not spherically symmetric, and that the gas falling onto the circumstellar disk may be episodic. RP VELUSAMY, T (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 45 Z9 45 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1995 VL 451 IS 2 BP L75 EP & PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV627 UT WOS:A1995RV62700009 ER PT J AU FEIBELMAN, WA JOHANSSON, S AF FEIBELMAN, WA JOHANSSON, S TI C-IV AND O-VI TRANSITIONS IN THE REGION LAMBDA-LAMBDA-1100-2000 AND EXAMPLES FOUND IN IUE SPECTRA OF HOT STARS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE LINE, IDENTIFICATION; PLANETARY NEBULAE, GENERAL; STARS, EARLY-TYPE; ULTRAVIOLET, STARS; WHITE DWARFS ID NON-LTE ANALYSIS; PLANETARY-NEBULAE; OLD PLANETARIES AB We present Ritz wavelengths for more than 130 transitions of C IV and O VI in the range lambda lambda 1100-2000 and show examples of absorption features as seen in representative examples of high-dispersion IUE spectra of very hot (similar to 100,000 K) nuclei of planetary nebulae, white dwarfs, and PG 1159-type stars. The regions near He II lambda 1640 and interstellar Si II lambda 1260 are of particular interest because they coincide with strong C IV and O VI transitions. O VI absorptions are detected in the IUE spectrum of the nucleus of the planetary nebula NGC 7293, which suggests that this object may be a ''hybrid'' star with an H-rich atmosphere. C1 LUND UNIV,DEPT PHYS,S-22362 LUND,SWEDEN. LUND UNIV,LUND OBSERV,LUND,SWEDEN. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 19 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD OCT PY 1995 VL 100 IS 2 BP 405 EP 412 DI 10.1086/192226 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RV628 UT WOS:A1995RV62800007 ER PT J AU FERRANDO, AA STUART, CA BRUNDER, DG HILLMAN, GR AF FERRANDO, AA STUART, CA BRUNDER, DG HILLMAN, GR TI MAGNETIC-RESONANCE-IMAGING QUANTITATION OF CHANGES IN MUSCLE VOLUME DURING 7 DAYS OF STRICT BED REST SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID EXERCISE AB Background: Prolonged bed rest results in a loss of leg lean body mass. Previous studies using bed rest as a model for microgravity have shown decreases in leg mass after 12 and 14 d, 5 and 17 wk. Hypothesis: As magnetic resonance imaging (MRI) can provide a precise and non-invasive means of determining muscle volume, we sought to determine if changes in leg muscle volume could be detected in bed rest periods as short as 7 d. Methods: Five young, healthy, male volunteers were subjected to 7 d of absolute bed rest. Each subject underwent MRI quantitation of segmental muscle Volumes of the calves and thighs before and after bed rest. Eleven (calf) and nine (thigh) contiguous 1-cm thick transaxial images were generated over prescribed regions using a Technicare MRI imager with a 0.6T superconducting magnet and body coil. Image processing was performed using a generalized 8-bit medical image analysis package developed at University of Texas Medical Branch. Images were analyzed for muscle and non-muscle volumes (including fat, blood vessel, and bone marrow volumes). Results: The MRI quantitation demonstrated bed rest-induced significant decreases in segmental thigh muscle (approximate to 3.0%, p < 0.05) volume. Conclusions: We conclude that computerized image analysis of MRI images provides a sensitive tool capable of detecting leg Volume changes of as little as 3.0% over a 7-d period of strict bed rest. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV TEXAS,MED BRANCH,DEPT INTERNAL MED,GALVESTON,TX 77550. UNIV TEXAS,MED BRANCH,DEPT ACAD COMP,GALVESTON,TX 77550. UNIV TEXAS,MED BRANCH,DEPT PHARMACOL,GALVESTON,TX 77550. FU PHS HHS [M01-0073] NR 17 TC 70 Z9 72 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 1995 VL 66 IS 10 BP 976 EP 981 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA RX866 UT WOS:A1995RX86600009 PM 8526835 ER PT J AU KNOX, RG HARCOMBE, PA ELSIK, IS AF KNOX, RG HARCOMBE, PA ELSIK, IS TI CONTRASTING PATTERNS OF RESOURCE LIMITATION IN TREE SEEDLINGS ACROSS A GRADIENT IN SOIL TEXTURE SO CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE LA English DT Article ID ENVIRONMENT RELATIONSHIPS; SOUTHEAST TEXAS; COASTAL-PLAIN; UNITED-STATES; FOREST; SUCCESSION; DYNAMICS; AVAILABILITY; HYPOTHESIS; VEGETATION AB Resource competition theory for terrestrial plant communities explains gradients in species composition among various habitats as the outcome of differential supply and demand for limiting resources. To examine one group of assumptions of this theory, for forest vegetation in southeastern Texas, we grew seedlings of three broadly distributed tree species, Acer rubrum L. (red maple), Liquidambar styraciflua L. (sweetgum), and Pinus taeda L. (loblolly pine), in intact soil cores collected from three sites located along a gradient in soil texture. We tested resource limitation in a temperature-controlled greenhouse with nutrient fertilization, light, and moisture treatments applied in a resource-minus or screening design. This design provided most resources at levels not limiting for growth while simulating (potentially limiting) field conditions for a single resource or group of related resources. Light was most limiting with clay-rich floodplain soil cores under simulated floodplain forest conditions. Soil nutrients were most limiting in sandy upland soil cores under upper slope forest conditions. Both light and soil nutrients were strongly limiting with loamy intermediate soil cores under simulated mesic forest conditions. The most limiting soil resource was phosphorus. The pattern of reciprocal limitation by aboveground or belowground resources in extreme habitats and joint limitation in intermediate habitats was consistent with requirements of the theory. C1 RICE UNIV,DEPT ECOL & EVOLUT BIOL,HOUSTON,TX 77251. RP KNOX, RG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. RI Knox, Robert/E-9657-2011 NR 55 TC 8 Z9 8 U1 2 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 OCT PY 1995 VL 25 IS 10 BP 1583 EP 1594 DI 10.1139/x95-173 PG 12 WC Forestry SC Forestry GA TA840 UT WOS:A1995TA84000004 ER PT J AU XU, KM NOOR, AK TANG, YY AF XU, KM NOOR, AK TANG, YY TI 3-DIMENSIONAL SOLUTIONS FOR COUPLED THERMOELECTROELASTIC RESPONSE OF MULTILAYERED PLATES SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID ACTUATORS; BEAM AB Analytic three-dimensional solutions are presented for the coupled thermoelectroelastic response of multilayered hybrid composite plates. The plates consist of a combination of fiber-reinforced cross-ply and piezothermoelastic layers. Both the thermoelectroelastic static response and its sensitivity coefficients are computed. The sensitivity coefficients measure the sensitivity of the response to variations in different mechanical, thermal and piezoelectric material properties of the plate. A linear constitutive model is used, and the material properties are assumed to be independent of the temperature and the electric field. The plates are assumed to have rectangular geometry and special material symmetries. A mixed formulation is used with the fundamental unknowns consisting of the three transverse stress components, three displacement components, transverse component of the electric displacement field, electric potential, transverse heat flux component and temperature change. Each of the fundamental unknowns is expressed in terms of a double Fourier series in the Cartesian surface coordinates. A state space approach is used to generate the static response and to evaluate the sensitivity coefficients. Extensive numerical results are presented showing the effects of variation in the geometric parameters of the plate on the different response quantities and their sensitivity coefficients. C1 UNIV VIRGINIA,CTR COMPUTAT STRUCT TECHNOL,NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NATL RES COUNCIL,STRUCT ACOUST BRANCH,NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 23 TC 116 Z9 128 U1 0 U2 5 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. Methods Appl. Mech. Eng. PD OCT PY 1995 VL 126 IS 3-4 BP 355 EP 371 DI 10.1016/0045-7825(95)00825-L PG 17 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA TH243 UT WOS:A1995TH24300011 ER PT J AU KAZEMINEZHAD, F ZALESAK, S SPICER, D AF KAZEMINEZHAD, F ZALESAK, S SPICER, D TI A PARTICLE MODEL ON AN UNSTRUCTURED MESH SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article DE PLASMA PHYSICS; COLLISIONLESS PLASMAS ID SIMULATION; CODE AB We describe a particle in the cell scheme which incorporates finite elements in space and finite difference in time to follow the trajectories of particles in their self consistent fields. As such the model exploits the power of finite element techniques to better investigate the rich physics embedded in the particle or kinetic models. A brief description of the foundations of the hybrid model of kinetic ions and mass-less fluid electrons is first presented, followed by a brief summary of linear finite elements on triangles with relevance to the particle modeling. The particle trace method on triangular elements, particle to node density assignment, node to particle response, the scheme algorithm, numerical stability, and finally tests of the code via eigenmode analysis and comparison with the analytic theory and the structured simulation results are presented. The version presented here is a 2 1/2-dimensional one. RP KAZEMINEZHAD, F (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,CODE 934,GREENBELT,MD 20771, USA. NR 17 TC 2 Z9 3 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD OCT PY 1995 VL 90 IS 2-3 BP 267 EP 292 DI 10.1016/0010-4655(95)00091-S PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA TB566 UT WOS:A1995TB56600008 ER PT J AU MATTIKALLI, NM DEVEREUX, BJ RICHARDS, KS AF MATTIKALLI, NM DEVEREUX, BJ RICHARDS, KS TI INTEGRATION OF REMOTELY-SENSED SATELLITE IMAGES WITH A GEOGRAPHICAL INFORMATION-SYSTEM SO COMPUTERS & GEOSCIENCES LA English DT Article DE REMOTELY SENSED IMAGERY; GEOGRAPHICAL INFORMATION SYSTEM; DATA INTEGRATION; RASTER-TO-VECTOR CONVERSION; FORTRAN; AML AB The basis data structures of a vector-based Geographical Information System (GIS) and a remotely sensed satellite image are different as the latter are in raster format. Availability of large amounts of data on both of these formats, and the potential of their combined use in environmental applications gives rise to the need for both effective data integration techniques. A new methodology is presented in this paper to integrate remotely sensed raster images with vector data in a GIS and vice versa. This methodology has been implemented successfully and demonstrated as an efficient tool for the integration of both fine and coarse resolution remotely sensed images in a GIS. C1 UNIV CAMBRIDGE,DEPT GEOG,CAMBRIDGE CB2 3EN,ENGLAND. RP MATTIKALLI, NM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. NR 16 TC 14 Z9 15 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0098-3004 J9 COMPUT GEOSCI JI Comput. Geosci. PD OCT PY 1995 VL 21 IS 8 BP 947 EP 956 DI 10.1016/0098-3004(95)00031-3 PG 10 WC Computer Science, Interdisciplinary Applications; Geosciences, Multidisciplinary SC Computer Science; Geology GA TC683 UT WOS:A1995TC68300004 ER PT J AU Polovina, JJ Mitchum, GT Evans, GT AF Polovina, JJ Mitchum, GT Evans, GT TI Decadal and basin-scale variation in mixed layer depth and the impact on biological production in the Central and North Pacific, 1960-88 SO DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS LA English DT Article ID ATLANTIC; CLIMATE; TRENDS; WATERS; OCEAN AB Changes in winter and spring mixed Layer depths in the North Pacific on decadal and basin scales affect biological production. In the subtropical and transition zones these depths were 30-80% greater during 1977-88 than during 1960-76; in the subarctic zone they were 20-30% shallower. We attribute these changes to an intensification of the Aleutian Low Pressure System. A deeper mixed layer might increase phytoplankton production in nutrient-poor regions by supplying more deep nutrients; it might decrease production in light-poor regions by mixing cells into darker water. A plankton population dynamics model suggests that a deeper subtropical mixed layer and a shallower subarctic mixed layer both would increase primary and secondary production by about 50%, and these increases were found not to be very sensitive to model parameter values; in the transition zone, however, the predicted change in production was smaller and more sensitive to changes in model parameters. Increases in higher tropic levels have been observed in subtropical and subarctic zones during 1977-88. This is consistent with model results and the idea that the subtropical zone is nutrient-poor, the subarctic zone is light-poor, and the transition zone is not consistently limited by any one thing. Further, our results show changes in mixed layer depths occur on decadal and basin scales and may be an important mechanism Linking variation in the atmosphere and oceanic ecosystem productivity. C1 UNIV HAWAII,SCH OCEAN & EARTH SCI & TECHNOL,DEPT OCEANOG,HONOLULU,HI 96822. FISHERIES & OCEANS CANADA,SCI BRANCH,ST JOHNS,NF A1C 5X1,CANADA. RP Polovina, JJ (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 25 TC 229 Z9 233 U1 1 U2 23 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0637 J9 DEEP-SEA RES PT I JI Deep-Sea Res. Part I-Oceanogr. Res. Pap. PD OCT PY 1995 VL 42 IS 10 BP 1701 EP 1716 DI 10.1016/0967-0637(95)00075-H PG 16 WC Oceanography SC Oceanography GA TK370 UT WOS:A1995TK37000002 ER PT J AU NAGASUBRAMANIAN, G SHEN, DH SURAMPUDI, S WANG, QJ PRAKASH, GKS AF NAGASUBRAMANIAN, G SHEN, DH SURAMPUDI, S WANG, QJ PRAKASH, GKS TI LITHIUM SUPERACID SALTS FOR SECONDARY LITHIUM BATTERIES SO ELECTROCHIMICA ACTA LA English DT Article; Proceedings Paper CT 5th International Symposium on Polymer Electrolytes (ISPE4) CY JUN 21-25, 1994 CL NEWPORT, RI SP Ciba Geigy Japan Ltd, Cyprus Foote Mineral Co, Dai Ichi Kogyo Seiyaku Co Ltd, Duracell Int Inc, Ever Ready Battery Co Inc, USN, Off Naval Res, Yuasa Corp DE LITHIUM SUPERACID SALT; POLYETHYLENE OXIDE; CONDUCTIVITY; CATHODE CAPACITY AND LITHIUM TRANSPORT NUMBER AB Three newly prepared lithium superacid double dagger salts of the type CnF2n+1SO3Li (where n is 4, 8 and 10) and CF3SO3Li and (CF3SO2)(2)NLi were used as salts in polyethylene oxide (PEG) electrolytes. Our conductivity data shows that among the salts investigated PEO electrolytes containing (CF3SO2)(2) NLi gave the highest conductivity followed by C4F9SO3Li and C3F17SO3Li. PEO electrolytes containing C10F21SO3Li and CF3SO3Li showed a lower conductivity at room temperature than the rest. Experimental Li-TiS2 polymer cells containing either PEO-C4F9SO3Li or PEO-(CF(3)S0(2))(2)NLi as electrolyte were fabricated and tested for cycle life performance. No significant loss in capacity was observed even after 50 to 100 cycles. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,DEPT CHEM,LOS ANGELES,CA 90089. NR 4 TC 15 Z9 16 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-4686 J9 ELECTROCHIM ACTA JI Electrochim. Acta PD OCT PY 1995 VL 40 IS 13-14 BP 2277 EP 2280 DI 10.1016/0013-4686(95)00177-G PG 4 WC Electrochemistry SC Electrochemistry GA RU089 UT WOS:A1995RU08900040 ER PT J AU MORSE, WW ABLE, KW AF MORSE, WW ABLE, KW TI DISTRIBUTION AND LIFE-HISTORY OF WINDOWPANE, SCOPHTHALMUS-AQUOSUS, OFF THE NORTHEASTERN UNITED-STATES SO FISHERY BULLETIN LA English DT Article ID LOWER CHESAPEAKE BAY; NEW-YORK; ICHTHYOPLANKTON; FISHES; ABUNDANCE AB The windowpane, Scophthalmus aquosus, is a shallow water (<110 m), resident species of the Middle Atlantic Eight (and adjacent estuaries) and Georges Bank, although it may undergo short (both inshore-offshore and alongshore) migrations in response to seasonal temperature changes. Spawning occurred throughout the Middle Atlantic Eight during the period from 1977 to 1987 but was most pronounced on Georges Bank. The timing of spawning, determined from the collection of 2-4 mm larvae, varied with location; and a split spawning season (April-May and October-November) was evident in the Middle Atlantic Eight. Spawning on Georges Bank peaked in August. Although spawning occurred over a broad temperature range (5-23 degrees C), the optimal temperature was 16-19 degrees C in the Middle Atlantic Eight and 13-16 degrees C on Georges Bank. Larval development occurred in areas of spawning and was most prolonged on Georges Bank, where the largest larvae (13-20 mm) were consistently found. Few larvae >8 mm were captured in the Middle Atlantic Eight. On the basis of samples from southern New Jersey, settlement probably occurs on the continental shelf and in adjacent estuaries of the Middle Atlantic Eight. The growth patterns of young of the year varied with the timing of spawning and subsequent settlement. In the first six months, fish of the spring-spawned cohort grew to 11-19 cm TL whereas those of the fall-spawned cohort grew to just 4-8 cm TL within that time. These data contribute to our understanding of the distribution and early life history of windowpane on the continental shelf, though the role of estuaries in the Middle Atlantic Eight is incompletely known. C1 RUTGERS STATE UNIV,INST MARINE & COASTAL SCI,MARINE FIELD STN,TUCKERTON,NJ 08087. RP MORSE, WW (reprint author), NOAA,NATL MARINE FISHERIES SERV,JAMES J HOWARD LAB,HIGHLANDS,NJ 07732, USA. NR 58 TC 7 Z9 7 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 1995 VL 93 IS 4 BP 675 EP 693 PG 19 WC Fisheries SC Fisheries GA RZ415 UT WOS:A1995RZ41500007 ER PT J AU STERLING, TL SAVARESE, DF MERKEY, PR GARDNER, JP AF STERLING, TL SAVARESE, DF MERKEY, PR GARDNER, JP TI AN INITIAL EVALUATION OF THE CONVEX SPP-1000 FOR EARTH AND SPACE SCIENCE APPLICATIONS SO FUTURE GENERATION COMPUTER SYSTEMS LA English DT Article; Proceedings Paper CT 1st International Symposium on High-Performance Computer Architecture (HPCA) CY JAN 22-25, 1995 CL RALEIGH, NC DE CONVEX EXEMPLAR; SPP-1000; SHARED MEMORY; CACHE COHERENCE; SCI; PERFORMANCE EVALUATION AB The Convex SPP-1000 is the most recent of the new generation of Scalable Parallel Computing systems being offered commercially. The SPP-1000 is distinguished by incorporating the first commercial version of directory based cache coherence mechanisms and the emerging Scalable Coherent Interface protocol to achieve a true global shared memory capability. Pairs of HP PA-RISC processors are combined in clusters of 8 processors using a cross-bar switch. Up to 16 clusters are interconnected using 4 ring networks in parallel with a distributed global cache. To evaluate this new system in a Beta test environment, the Goddard Space Flight Center conducted three classes of operational experiments with an emphasis on applications related to Earth and space science. A cluster was tested as a platform for executing a multiple program workload exploiting job-stream level parallelism. Synthetic programs were run to measure overhead costs of barrier, fork-join, and message passing synchronization primitives. A key problem for Earth and space science studies is gravitational N-body simulation of solar systems to galactic clusters. An efficient tree-code version of this problem was run to reveal scaling properties of the system and to measure the overall efficiency. This paper presents the experimental results and findings of this study and provides the earliest published evaluation of this new scalable architecture. C1 UNIV MARYLAND,DEPT COMP SCI,COLLEGE PK,MD 20742. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. RP STERLING, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CTR EXCELLENCE SPACE DATA & INFORMAT SCI,CODE 9305,GREENBELT,MD 20771, USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-739X J9 FUTURE GENER COMP SY JI Futur. Gener. Comp. Syst. PD OCT PY 1995 VL 11 IS 6 BP 567 EP 583 DI 10.1016/0167-739X(95)00025-N PG 17 WC Computer Science, Theory & Methods SC Computer Science GA TG013 UT WOS:A1995TG01300006 ER PT J AU BOGARD, DD GARRISON, DH AF BOGARD, DD GARRISON, DH TI AR-39-AR-40 AGE, OF THE IBITIRA EUCRITE AND CONSTRAINTS ON THE TIME OF PYROXENE EQUILIBRATION SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Note ID ANGRA-DOS-REIS; PARENT BODY; RB-SR; ACHONDRITES; METEORITES; CHONDRITES; EVOLUTION AB We determined a Ar-39-Ar-40 age of 4.495 +/- 0.015 Ga for the unbrecciated Ibitira eucrite. This age ranks among the oldest Ar-39-Ar-40 ages for eucrites and suggests that Ibitira escaped the widespread impact resetting of K-Ar ages similar to 4.1-3.5 Ga ago indicated by other HED meteorites. Ibitira exhibits a relatively high degree of chemical equilibration of its pyroxene caused by prolonged annealing. This equilibration must have occurred subsequent to the reported (207)pb-(206)pb formation age for Ibitira of 4.556-4.560 Ga, but prior to its determined Ar-Ar age. If pyroxene equilibration occurred during burial at significant depths or in a large impact deposit, then the Ar-Ar age may date this event. RP BOGARD, DD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,LOCKHEED ESC,CODE SN4,HOUSTON,TX 77058, USA. NR 34 TC 21 Z9 21 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD OCT PY 1995 VL 59 IS 20 BP 4317 EP 4322 DI 10.1016/0016-7037(95)00310-V PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TC228 UT WOS:A1995TC22800017 ER PT J AU MYNENI, RB LOS, SO ASRAR, G AF MYNENI, RB LOS, SO ASRAR, G TI POTENTIAL GROSS PRIMARY PRODUCTIVITY OF TERRESTRIAL VEGETATION FROM 1982-1990 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STOMATAL CONDUCTANCE; MODEL; SATELLITE; CLIMATE; INDEX; CO2; PHOTOSYNTHESIS; EXCHANGE AB Monthly mean global green leaf area and photosynthetically active radiation estimated from observations made from several geostationary and polar orbiting satellites were used to estimate potential, (i.e., unstressed) gross primary productivity of terrestrial vegetation from 1982 to 1990. Mean annual gross primary productivity was estimated to be about 179.9 +/- 1.6 Pg C (1 Pg = 10(15) g). Grasses and xerophgtic vegetation on all continents exhibited high interannual variability. The evolution of monthly gross primary productivity anomalies was similar to atmospheric CO2 growth rate during 1982-1990. This was observed both globally and for the 30 degrees - 90 degrees N latitudional band, but not at other latitudes. From this, we may conclude that total ecosystem respiration and GPP respond similarly but disproportionately to climate: such that the difference between the two resembles the opposite of the observed atmospheric CO2 growth rate. C1 NASA,OFF MISS PLANET EARTH,WASHINGTON,DC. NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RI Los, Sietse/G-8985-2012; Myneni, Ranga/F-5129-2012; OI Los, Sietse/0000-0002-1325-3555 NR 31 TC 40 Z9 40 U1 0 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 1995 VL 22 IS 19 BP 2617 EP 2620 DI 10.1029/95GL02562 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RX918 UT WOS:A1995RX91800017 ER PT J AU KAWA, SR KUMER, JB DOUGLASS, AR ROCHE, AE SMITH, SE TAYLOR, FW ALLEN, DJ AF KAWA, SR KUMER, JB DOUGLASS, AR ROCHE, AE SMITH, SE TAYLOR, FW ALLEN, DJ TI MISSING CHEMISTRY OF REACTIVE NITROGEN IN THE UPPER STRATOSPHERIC POLAR WINTER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NITRIC-ACID; HNO3 AB Data from the CLAES on UARS indicate that a significant mechanism for production of HNO3 in the middle to upper stratosphere is missing from the chemical reaction set currently used by atmospheric models. Measured HNO3 in the polar vortex is strongly enhanced relative to the extra-vortex at 1200 K potential temperature (near 3 mbar) in January, 1992. The HNO3 vertical profile shows this enhancement forms a secondary altitude maximum from about 10 to 2 mbar (800-1500 K). A chemistry/transport model (CTM) simulation of this period produces no increase of HNO3 in the vortex near 3 mbar and no secondary maximum in the HNO3 profile. Furthermore, the CTM produces relatively high N2O5 in the vortex, with a vertical peak near 3 mbar, while both CLAES and ISAMS show a shallow minimum there. The implication of this comparison is that some unmodeled process is acting to enhance HNO3 and reduce N2O5 at high latitudes in the winter middle and upper stratosphere. Heterogeneous conversion of N2O5 to HNO3 on hydrated ion clusters is proposed as a possibility for the missing mechanism. C1 UNIV MARYLAND,DEPT METEOROL,COLLEGE PK,MD 20742. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. UNIV OXFORD,CLARENDON LAB,OXFORD OX1 3PU,ENGLAND. RP KAWA, SR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Allen, Dale/F-7168-2010; Douglass, Anne/D-4655-2012; Kawa, Stephan/E-9040-2012 OI Allen, Dale/0000-0003-3305-9669; NR 15 TC 40 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 1995 VL 22 IS 19 BP 2629 EP 2632 DI 10.1029/95GL02336 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RX918 UT WOS:A1995RX91800020 ER PT J AU BURRAGE, MD HAGAN, ME SKINNER, WR WU, DL HAYS, PB AF BURRAGE, MD HAGAN, ME SKINNER, WR WU, DL HAYS, PB TI LONG-TERM VARIABILITY IN THE SOLAR DIURNAL TIDE OBSERVED BY HRDI AND SIMULATED BY THE GSWM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER THERMOSPHERE; MIDDLE ATMOSPHERE; HOUGH COMPONENTS; GRAVITY-WAVES; MESOSPHERE; MODEL; SATELLITE AB Observations of the mesosphere and lower thermosphere winds obtained by the High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite (UARS) during 1991 to 1995 reveal a semiannual variation in the amplitude of the (1,1) diurnal tide. The global-scale wave model (GSWM) represents the first numerical modeling attempt at simulating this seasonal variability, and a preliminary comparison of the GSWM tidal results with HRDI measurements is presented. The results of the comparison and of numerical tests point to some vital and unresolved questions regarding tidal dissipation and tropospheric forcing. In addition to the seasonal variability, HRDI has revealed a strong interannual modulation of the diurnal tide with amplitudes observed to change by nearly a factor of 2 from 1992 to 1994. C1 NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP BURRAGE, MD (reprint author), UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109, USA. RI Hagan, Maura/C-7200-2008; Wu, Dong/D-5375-2012 OI Hagan, Maura/0000-0002-8866-7429; NR 21 TC 165 Z9 167 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 1995 VL 22 IS 19 BP 2641 EP 2644 DI 10.1029/95GL02635 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RX918 UT WOS:A1995RX91800023 ER PT J AU OFMAN, L DAVILA, JM STEINOLFSON, RS AF OFMAN, L DAVILA, JM STEINOLFSON, RS TI NONLINEAR STUDIES OF CORONAL HEATING BY THE RESONANT ABSORPTION OF ALFVEN WAVES - REPLY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOOPS C1 SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78226. RP OFMAN, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6821,GREENBELT,MD 20771, USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 1995 VL 22 IS 19 BP 2679 EP 2680 DI 10.1029/95GL02622 PG 2 WC Geosciences, Multidisciplinary SC Geology GA RX918 UT WOS:A1995RX91800033 ER PT J AU KHAOUSTOV, VI DARLINGTON, GJ SORIANO, HE KRISHNAN, B RISIN, D PELLIS, NR YOFFE, B AF KHAOUSTOV, VI DARLINGTON, GJ SORIANO, HE KRISHNAN, B RISIN, D PELLIS, NR YOFFE, B TI ESTABLISHMENT OF 3-DIMENSIONAL PRIMARY HEPATOCYTE CULTURES IN MICROGRAVITY ENVIRONMENT SO HEPATOLOGY LA English DT Meeting Abstract C1 BAYLOR COLL MED,VET ADM MED CTR,DEPT MED,DIV MOLEC VIROL,HOUSTON,TX 77030. BAYLOR COLL MED,VET ADM MED CTR,DEPT PATHOL,DIV MOLEC VIROL,HOUSTON,TX 77030. NASA,JSC,HOUSTON,TX. KRUG LIFE SCI,HOUSTON,TX. NR 0 TC 0 Z9 0 U1 0 U2 1 PU W B SAUNDERS CO PI PHILADELPHIA PA INDEPENDENCE SQUARE WEST CURTIS CENTER, STE 300, PHILADELPHIA, PA 19106-3399 SN 0270-9139 J9 HEPATOLOGY JI Hepatology PD OCT PY 1995 VL 22 IS 4 SU S BP 498 EP 498 PN 2 PG 1 WC Gastroenterology & Hepatology SC Gastroenterology & Hepatology GA RX690 UT WOS:A1995RX69000497 ER PT J AU YODER, CF AF YODER, CF TI VENUS FREE OBLIQUITY SO ICARUS LA English DT Article ID SOLAR-SYSTEM; THERMAL EVOLUTION; ATMOSPHERIC TIDES; GRAVITY-FIELD; EARTHS CORE; TOPOGRAPHY; ROTATION; MODEL; LIBRATIONS; TECTONICS AB The predicted orientation of Venus' rotation axis relative to its orbit can be uniquely determined given knowledge of its J(2) gravity coefficient and polar moment of inertia C if its free obliquity is fully damped. This assumption seems warranted given the dominant damping mechanism: turbulent fluid friction at a core mantle boundary (CMB). This skin friction results from differential obliquity of mantle and core spin axes, and the associated damping rare could be as short as 1/10(6) year. However, the observed pole orientation indicates a free obliquity amplitude epsilon similar or equal to 2.1 degrees compared with a nominal forced amplitude of 0.5 degrees. There are two plausible explanations. The most likely is that the observed obliquity is a tidally evolved end state in which core friction, modulated by CMB ellipticity and core obliquity amplitude, counterbalances solid and atmospheric tidal torques. This concept is similar to the explanation for the retrograde spin omega as an end state in which solid and atmospheric thermal tidal torques balance at the present spin rate because of the omega(-1) dependence of the axial thermal torque. Large core ellipticity e(c) drop (C-c - 1/2(A(c) + B-c))/C-c (C-c greater than or equal to B-c greater than or equal to A(c) are core moments of inertia) can substantially increase fluid friction damping time if e(c) is significantly larger than the whole body ellipticity e(o) = J(2)MR(2)/C similar or equal to 1.3 x 10(-5) by reducing the relative obliquity of core and mantle spin vectors. Note that the hydrostatic contribution to oblateness similar to 1.7 x 10(-7) is presently negligible. Weaker effects such as solid and thermal tides can then compete with core friction and for plausible models, their sum tends to increase free obliquity. The obliquity balance is controlled by the nonlinear (and nearly quadratic) dependence of the CMB turbulent ''skin friction'' torque on obliquity. I find that a steady state is achieved for e(c) similar or equal to 29e(o) similar or equal to 4 x 10(-4). If the CMB topography is dynamically supported, then the necessary bottom density anomaly is constrained to the bottom similar to 10% of the mantle. An alternative model is that the obliquity results from resonant excitation due to small amplitude (less than or equal to 0.002 degrees), prograde oscillations in Venus' orbit, one of which happens nearly to match Venus' precession rate sigma. This mechanism can account for the obliquity even if the iron core has solidified, but also requires a tectonically quiescent planet (d\J(2)/dt\ < 10(-15) year(-1)). This model has been explored numerically for a wide range of initial conditions, tidal parameters, temporal J(2) variations, and chaotic wander of the driving frequencies for the orbit. Only four frequencies, in or near the predicted band for sigma, have a significant effect and also have a narrow range of effectiveness. I estimate the polar moment to be in the range 0.0341. (C/MR(2)) less than or equal to 0.331 and hence the precession rate a to be in the range 44.1 less than or equal to sigma less than or equal to 45.8('') year(-1) based on construction of a suite of density profiles in which mantle composition and core size have theoretically limited variations. Comparing resonance widths to the a uncertainty, I find that the resonance hypothesis has about a 30% chance of being correct. Core ellipticity also has a profound effect on tidal evolution of Venus obliquity. The ratio of turbulent core and solid tidal friction scales like omega(-4), implying that core friction ''turns on'' only as the spin omega approaches its end state. I also find that the semiannual atmospheric tide can have a dramatic effect on evolution, allowing for inversion of spin orientation from prograde to retrograde if the initial obliquity is sufficiently large (greater than or equal to 45 degrees). Potential measurements which have a bearing on these models including precession rate, tidal Love number k(2), and semidiurnal variation in atmospheric pressure at Venus' surface. Perhaps the most useful parameter is k(2), which is detectable from orbit, requires only a modest improvement in the tracking accuracy and spacecraft stability over that provided by Magellan, and is an excellent proxy for core fluidity and if fluid, core size and composition. (C) 1995 Academic Press, Inc. RP YODER, CF (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 87 TC 42 Z9 42 U1 2 U2 7 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1995 VL 117 IS 2 BP 250 EP 286 DI 10.1006/icar.1995.1156 PG 37 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD695 UT WOS:A1995TD69500002 ER PT J AU HOURDIN, F TALAGRAND, O SADOURNY, R COURTIN, R GAUTIER, D MCKAY, CP AF HOURDIN, F TALAGRAND, O SADOURNY, R COURTIN, R GAUTIER, D MCKAY, CP TI NUMERICAL-SIMULATION OF THE GENERAL-CIRCULATION OF THE ATMOSPHERE OF TITAN SO ICARUS LA English DT Article ID VOYAGER-1 RADIO-OCCULTATION; DYNAMICS; MARS; MODEL; VENUS; OCEAN AB The atmospheric circulation of Titan is investigated with a general circulation model. The representation of the large-scale dynamics is based on a grid point model developed and used at Laboratoire de Meteorologie Dynamique for climate studies. The code also includes an accurate representation of radiative heating and cooling by molecular gases and haze as well as a parametrization of the vertical turbulent mixing of momentum and potential temperature. Long-term simulations of the atmospheric circulation are presented. Starting from a state of rest, the model spontaneously produces a strong superrotation with prograde equatorial winds (i.e., in the same sense as the assumed rotation of the solid body) increasing from the surface to reach 100 m sec(-1) near the 1-mbar pressure level. Those equatorial winds are in very good agreement with some indirect observations, especially those of the 1989 occultation of Star 28-Sgr by Titan. On the other hand, the model simulates latitudinal temperature contrasts in the stratosphere that are significantly weaker than those observed by Voyager 1 which, we suggest, may be partly due to the nonrepresentation of the spatial and temporal variations of the abundances of molecular species and haze. We present diagnostics of the simulated atmospheric circulation underlying the importance of the seasonal cycle and a tentative explanation for the creation and maintenance of the atmospheric superrotation based on a careful angular momentum budget. (C) 1995 Academic Press, Inc. C1 OBSERV PARIS,DESPA,F-92190 MEUDON,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HOURDIN, F (reprint author), ECOLE NORMALE SUPER,CNRS,METEOROL DYNAM LAB,24 RUE LHOMOND,F-75231 PARIS 05,FRANCE. NR 49 TC 162 Z9 163 U1 0 U2 10 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1995 VL 117 IS 2 BP 358 EP 374 DI 10.1006/icar.1995.1162 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD695 UT WOS:A1995TD69500008 PM 11538593 ER PT J AU NUTH, JA WILKINSON, GM AF NUTH, JA WILKINSON, GM TI MAGNETICALLY ENHANCED COAGULATION OF VERY SMALL IRON GRAINS - A CORRECTION OF THE ENHANCEMENT FACTOR DUE TO DIPOLE-DIPOLE INTERACTIONS SO ICARUS LA English DT Article AB We correct an earlier effort to calculate the magnetically enhanced, coagulation cross section for very small iron grains in the solar nebula. None of the equations derived is completely satisfactory and several problems with regard to the initial assumptions in the derivation are discussed. Our most conservative estimates for the enhancement in the coagulation cross section due to magnetic effects are factors of 10(3) to 10(4), while more realistic values range from 10(5) to 10(7) or higher. We therefore conclude that magnetic dipole-dipole interactions could play a significant role in the initial stages of plantesimal accretion in protosellar nebulae. (C) 1995 Academic Press, Inc. C1 MAXWELL LABS INC,BALBOA DIV,SAN DIEGO,CA 92123. RP NUTH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 691,GREENBELT,MD 20771, USA. RI Nuth, Joseph/E-7085-2012 NR 8 TC 15 Z9 15 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1995 VL 117 IS 2 BP 431 EP 434 DI 10.1006/icar.1995.1167 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TD695 UT WOS:A1995TD69500013 ER PT J AU STUHR, F JORDAN, R WERNER, M AF STUHR, F JORDAN, R WERNER, M TI SIR-C/X-SAR - A MULTIFACETED RADAR SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article ID SYNTHETIC-APERTURE RADAR; B OBSERVATIONS AB The multifaceted Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) was successfully flown twice in 1994 aboard the Shuttle Endeavour as part of an international imaging radar mission. The United States SIR-C operated at L- and C-band, each with multiple polarization, utilizing an active phased array antenna. The German/Italian X-SAR operated a X-band with a single polarization. SIR-C and X-SAR operated synchronously to collect data over common sites. Data were collected for repeat-track interferometric processing at all three frequencies. A total of 143 hours (93 terabits) of SAR data were digitally recorded on tape over the two flights for subsequent processing in the U.S., Germany, and Italy. This advanced multifrequency, multipolarization system has produced a rich radar data set for Earth scientific investigation and demonstration of spaceborne radar remote sensing capabilities. SIR-C/X-SAR data can be accessed electronically via the World Wide Web address herein. RP STUHR, F (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 6 Z9 8 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD OCT PY 1995 VL 10 IS 10 BP 15 EP & DI 10.1109/62.469794 PG 0 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA TB405 UT WOS:A1995TB40500007 ER PT J AU SIMON, MP SCHUH, MJ WOO, AX AF SIMON, MP SCHUH, MJ WOO, AX TI BISTATIC ISAR IMAGES FROM A TIME-DOMAIN CODE SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Article AB Inverse-synthetic-aperture-radar (ISAR) images of radar targets are useful for target identification, visualization, and the analysis of scattering centers. The major advantage of bistatic over monostatic-ISAR imaging is the reduction, in the number of computed incident angles, from hundreds to one. This advantage has already been demonstrated for a Physical Theory of Diffraction (PTD) code, XPATCH. The bistatic-imaging technique can be extended to scattering data obtained from any time-accurate or iterative method, including low-frequency algorithms. This paper presents images from data obtained with a finite-volume time-domain (FVTD) code. It also provides relations between (I),the range and resolution of the bistatic scattering data in the Fourier domain, and (2) the pixel resolution and image extent in the physical domain for the down-range and cross-range directions. A tapering function is applied in the Fourier domain, to dampen ringing effects. Results are shown for a trapezoidal plate, a cone-sphere, and a square-aperture cavity. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SIMON, MP (reprint author), MPS ENGN,LOS ALTOS,CA 94204, USA. NR 8 TC 7 Z9 7 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 1045-9243 J9 IEEE ANTENNAS PROPAG JI IEEE Antennas Propag. Mag. PD OCT PY 1995 VL 37 IS 5 BP 25 EP 32 DI 10.1109/74.475861 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA TH234 UT WOS:A1995TH23400005 ER PT J AU JOSHI, SM MAGHAMI, PG KELKAR, AG AF JOSHI, SM MAGHAMI, PG KELKAR, AG TI DESIGN OF DYNAMIC DISSIPATIVE COMPENSATORS FOR FLEXIBLE SPACE STRUCTURES SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID POSITIVITY AB Control system design is considered for attitude control and vibration suppression of flexible space structures. The problem addressed Is that of controlling both the zero-frequency rigid-body modes and the elastic modes. Model-based compensators, which employ observers tuned to the plant parameters, are first investigated. Such compensators are shown to generally exhibit high sensitivity to the knowledge of the parameters, especially the elastic mode frequencies. To overcome this problem, a class of dynamic dissipative compensators is nest proposed which robustly stabilize the plant in the presence of unmodeled dynamics and parametric uncertainties. An analytical proof of robust stability is gh en, and a method of implementing the controller as a strictly proper compensator is given. Methods of designing such controllers to obtain optimal performance and robust stability are presented Numerical and experimental results of application of the methods are presented, which indicate that dynamic dissipative controllers can simultaneously provide excellent performance and robustness. C1 OLD DOMINION UNIV,NORFOLK,VA 23529. RP JOSHI, SM (reprint author), NASA,LANGLEY RES CTR,M-S 489,HAMPTON,VA 23681, USA. NR 14 TC 4 Z9 4 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 1995 VL 31 IS 4 BP 1314 EP 1324 DI 10.1109/7.464345 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA RX711 UT WOS:A1995RX71100008 ER PT J AU KELKAR, AG JOSHI, SM ALBERTS, TE AF KELKAR, AG JOSHI, SM ALBERTS, TE TI DYNAMIC DISSIPATIVE COMPENSATORS FOR MULTIBODY FLEXIBLE SPACE STRUCTURES SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID POSITIVITY AB The stability characteristics of dynamic dissipative compensators are investigated for multibody flexible space structures having nonlinear dynamics. The problem addressed is that of proving asymptotic stability of dynamic dissipative compensators. The stability proof uses the Lyapunov approach and exploits the inherent passivity of such systems. For such system these compensators are shown to be robust to parametric uncertainties and unmodeled dynamics. The results are applicable to a large class of structures such as satellites with multiple payloads and space-based manipulators. C1 OLD DOMINION UNIV,NORFOLK,VA 23529. RP KELKAR, AG (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 489,HAMPTON,VA 23665, USA. NR 18 TC 1 Z9 1 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 1995 VL 31 IS 4 BP 1325 EP 1330 DI 10.1109/7.464353 PG 6 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA RX711 UT WOS:A1995RX71100009 ER PT J AU LOZANO, R JOSHI, SM AF LOZANO, R JOSHI, SM TI STRICTLY POSITIVE REAL TRANSFER-FUNCTIONS REVISITED - REPLY SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP LOZANO, R (reprint author), UNIV TECHNOL COMPIEGNE,CNRS,URA 817,BP 649,F-60206 COMPIEGNE,FRANCE. NR 2 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD OCT PY 1995 VL 40 IS 10 BP 1799 EP 1800 DI 10.1109/9.467670 PG 2 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA RY374 UT WOS:A1995RY37400013 ER PT J AU JOSHI, SM KELKAR, AG WEN, JTY AF JOSHI, SM KELKAR, AG WEN, JTY TI ROBUST ATTITUDE STABILIZATION OF SPACECRAFT USING NONLINEAR QUATERNION FEEDBACK SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note AB This paper considers the problem of three-axis attitude stabilization of a rigid spacecraft. A nonlinear control law which uses the feedback of the unit quaternion and the measured angular velocities is proposed and is shown to provide global asymptotic stability, The control law does not require the knowledge of the system parameters and is, therefore, robust to modeling errors. The significance of the control law is that it can be used for large-angle maneuvers with guaranteed stability. C1 RENSSELAER POLYTECH INST,DEPT ELECT COMP & SYST ENGN,TROY,NY 12180. RP JOSHI, SM (reprint author), NASA,LANGLEY RES CTR,DIV FLIGHT DYNAM & CONTROL,HAMPTON,VA 23681, USA. RI Wen, John/B-4474-2008 OI Wen, John/0000-0002-5123-5411 NR 13 TC 140 Z9 148 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD OCT PY 1995 VL 40 IS 10 BP 1800 EP 1803 DI 10.1109/9.467669 PG 4 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA RY374 UT WOS:A1995RY37400014 ER PT J AU CROLEY, DR GARRETT, HB MURPHY, GB GARRARD, TL AF CROLEY, DR GARRETT, HB MURPHY, GB GARRARD, TL TI SOLAR PARTICLE-INDUCED UPSETS IN THE TDRS-1 ATTITUDE-CONTROL SYSTEM RAM DURING THE OCTOBER 1989 SOLAR PARTICLE EVENTS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID SINGLE; ENVIRONMENT; MODEL AB The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fiueuces of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAM unit affected was composed of eight Fairchild 93L422 memory chips, The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1., Two solid-state detector telescopes on-board Galileo, designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events, The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system, The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum, The expected number of heavy ion induced SEU's calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEU's by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEU's, The proton fluence spectrum at the device level was gotten by transporting the protons through the estimated shielding distribution, The number of calculated proton-induced SEU's was 72, yielding a total of 248 predicted SEU's, very close to the 243 observed SEV's. These calculations uniquely demonstrate the roles that solar heavy ions and protons played in the production of SEU's during the October 1989 solar particle events. C1 JET PROPULS LAB,PASADENA,CA 91109. CALTECH,GEORGE W DOWNS LAB PHYS,PASADENA,CA 91125. RP CROLEY, DR (reprint author), SYSCON CORP,MONTROSE,CA 91020, USA. NR 14 TC 11 Z9 11 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 1995 VL 42 IS 5 BP 1489 EP 1496 DI 10.1109/23.467946 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA RZ371 UT WOS:A1995RZ37100004 ER PT J AU GUO, HZ HOPPE, DJ RODGERS, J PEREZ, RM TATE, JP CONROY, BL GRANATSTEIN, VL BHANJI, AM LATHAM, PE NUSINOVICH, GS NAIMAN, ML CHEN, SH AF GUO, HZ HOPPE, DJ RODGERS, J PEREZ, RM TATE, JP CONROY, BL GRANATSTEIN, VL BHANJI, AM LATHAM, PE NUSINOVICH, GS NAIMAN, ML CHEN, SH TI PHASE-LOCKING OF A 2ND-HARMONIC GYROTRON OSCILLATOR USING A QUASI-OPTICAL CIRCULATOR TO SEPARATE INJECTION AND OUTPUT SIGNALS SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article ID HIGH-POWER GYROTRON; MODE; CAVITY AB Phase-locking in a 34.5-GHz special complex cavity gyrotron oscillator operating at the second harmonic of the electron cyclotron Frequency was studied, Injection of the locking power was made via a quasi-optical circulator connected to the gyrotron output. Locking bandwidth was measured by comparing the phase of the injection signal and output signal using a balanced mixer, Locking was observed with input power level as low as 40 dB below the gyrotron output power, The locking bandwidth is, however, narrower than in gyrotrons operating at the fundamental cyclotron frequency which may be attributed to the longer resonant cavity in the second harmonic gyrotron and the corresponding larger value of external quality factor, The measurements are roughly in agreement with predictions of Adler's phase-locking equation which is given for our system in terms of powers propagating in the output waveguide toward and away from the gyrotron cavity. C1 JET PROP LAB,PASADENA,CA 91109. RP GUO, HZ (reprint author), UNIV MARYLAND,INST PLASMA RES,COLLEGE PK,MD 20742, USA. NR 17 TC 13 Z9 13 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 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD OCT PY 1995 VL 23 IS 5 BP 822 EP 832 PG 11 WC Physics, Fluids & Plasmas SC Physics GA TE015 UT WOS:A1995TE01500003 ER PT J AU DRUYAN, LM SHAH, KP LO, KWK MARENGO, JA RUSSELL, G AF DRUYAN, LM SHAH, KP LO, KWK MARENGO, JA RUSSELL, G TI IMPACTS OF MODEL IMPROVEMENTS ON GENERAL-CIRCULATION MODEL SENSITIVITY TO SEA-SURFACE TEMPERATURE FORCING SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE GLOBAL CIRCULATION MODEL (GISS); SEA-SURFACE TEMPERATURE FORCING; SUMMER SEASONS 1987 AND 1988; MODEL VALIDATION ID SUMMER MONSOONS; ANOMALIES; CLIMATE; DROUGHT AB The sensitivity of the 4 degrees x 5 degrees resolution general circulation model of the Goddard Institute for Space Studies to some basic changes in model formulation was studied by comparing parallel simulations forced by global sea-surface temperature of June August 1987 and 1988. The new modelling schemes were substituted far the control model's parameterizations of moist convection, planetary boundary layer, ground hydrology, and cloud optical thickness in a series of sensitivity experiments. In addition, linear and quadratic upstream schemes for advecting tracers were tried in place of second-order differencing. Elimination of the vertical mixing of horizontal momentum by moist convection was also tested. Impacts of the new modelling schemes on simulated circulation, temperature, and precipitation rates were inferred from pairs of simulations made by model versions that differed with respect to a single change. No discernible positive impacts were found for the new ground hydrology scheme or for changes in the determination of cloud optical thickness. Profiles of zonal wind speeds and lower tropospheric circulation patterns, both in the tropics, were more realistic when the vertical mixing of horizontal momentum was included. Major improvements in modelling the interannual variability of the planetary circulation, mid-tropospheric temperature, and precipitation can be attributed to the salutory effects of the new moist convection, new planetary boundary layer, and the quadratic upstream scheme for advecting tracers. C1 CTR PREVISAO TEMPO & ESTUDOS CLIMAT,SAO PAULO,BRAZIL. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP DRUYAN, LM (reprint author), COLUMBIA UNIV,CTR CLIMATE SYST RES,NEW YORK,NY 10021, USA. RI Marengo, Jose /J-9382-2012 OI Marengo, Jose /0000-0002-8154-2762 NR 40 TC 9 Z9 9 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 OCT PY 1995 VL 15 IS 10 BP 1061 EP 1086 DI 10.1002/joc.3370151002 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TD614 UT WOS:A1995TD61400001 ER PT J AU MASAD, JA ABID, R AF MASAD, JA ABID, R TI ON TRANSITION IN SUPERSONIC AND HYPERSONIC BOUNDARY-LAYERS SO INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE LA English DT Article ID STABILITY THEORY; HEAT-TRANSFER; FLOW; PLATE AB The roles of the first and second modes of instability in high-speed boundary-layer transition are quantified. Linear stability theory and the N-factor criterion are used to predict transition location. The effect of heat transfer is also studied; the results demonstrate that the transition reversal phenomenon can be explained by the opposite effect of cooling on the first and second modes of instability. A heating strip can be used to stabilize first-mode waves at supersonic speeds. Compressibility is destabilizing at free-stream Mach numbers of 2-3.5. The predicted transition location is due to the oblique first modes of instability, up to free-stream Mach numbers between 6 and 6.5. At higher Mach numbers, the predicted transition location is due to a combination of two-dimensional (2-D) first and second modes of instability. RP MASAD, JA (reprint author), NASA,LANGLEY RES CTR,HIGH TECHNOL CORP,HAMPTON,VA 23681, USA. NR 46 TC 7 Z9 7 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7225 J9 INT J ENG SCI JI Int. J. Eng. Sci. PD OCT PY 1995 VL 33 IS 13 BP 1893 EP 1919 DI 10.1016/0020-7225(95)00046-Z PG 27 WC Engineering, Multidisciplinary SC Engineering GA RW277 UT WOS:A1995RW27700005 ER PT J AU MATTIKALLI, NM AF MATTIKALLI, NM TI INTEGRATION OF REMOTELY-SENSED RASTER DATA WITH A VECTOR-BASED GEOGRAPHICAL INFORMATION-SYSTEM FOR LAND-USE CHANGE DETECTION SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID EXPERT SYSTEM AB Methods of land-use change detection are different for raster and vector data types because of the differences in structures of the two data types. Since large amounts of land-use data (derived from existing maps and aerial photographs) are stored in vector format in a Geographical Information System (GIS), there is a need to develop a change detection algorithm for use with vector-formatted data. Since remotely-sensed images are increasingly being used to derive land-use data, it is necessary to integrate raster data with large volumes of vector data already available in a GIS. This necessitates an efficient and effective data integration technique using which raster data are to be integrated with a vector-based GIS. This paper presents a methodology of data integration of remotely-sensed raster data with vector data. A new approach is developed for land-use change detection for use with vector data in a GIS environment. The approach is based on the mathematical concepts of Sets and Groups, and is successfully implemented for the analysis of historical land-use change from 1931 to 1989 in the River Glen catchment, U.K. Algorithms have been developed for automatic derivation of dynamic statistics of land-use. It is shown that this approach can be efficiently adopted for operational use incorporating products derived from both coarse- and fine-resolution remotely-sensed satellite images once these are integrated with the vector-based GIS. RP MATTIKALLI, NM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. NR 27 TC 7 Z9 7 U1 1 U2 3 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD OCT PY 1995 VL 16 IS 15 BP 2813 EP 2828 PG 16 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA TC093 UT WOS:A1995TC09300006 ER PT J AU WANG, SG SHIEH, LS SUNKEL, JW AF WANG, SG SHIEH, LS SUNKEL, JW TI ROBUST OPTIMAL POLE-PLACEMENT IN A VERTICAL STRIP AND DISTURBANCE REJECTION SO INTERNATIONAL JOURNAL OF SYSTEMS SCIENCE LA English DT Article ID UNCERTAIN LINEAR-SYSTEMS; STABILIZATION; DESIGN AB This paper presents a linear quadratic regulator (LQR) for robust closed-loop pole-placement within a vertical strip, and disturbance rejection with an H-infinity-norm constraint for the uncertain linear systems. The concerned systems cover both matched and mismatched uncertain linear systems with unstructured or structured uncertainties existing in both the system and input matrices. A set of tuning parameters is incorporated for some flexibility in finding a solution to the algebraic Riccati equation, and a controller gain parameter is selected for robust pole clustering. Also, a constraint is established to verify whether the proposed robust LQRs preserve H-2 optimality with respect to a specific quadratic cost function. C1 NASA,LYNDON B JOHNSON SPACE CTR,DIV AVION SYST,HOUSTON,TX 77058. RP WANG, SG (reprint author), UNIV HOUSTON,DEPT ELECT & COMP ENGN,HOUSTON,TX 77204, USA. NR 12 TC 11 Z9 11 U1 0 U2 0 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0020-7721 J9 INT J SYST SCI JI Int. J. Syst. Sci. PD OCT PY 1995 VL 26 IS 10 BP 1839 EP 1853 DI 10.1080/00207729508929140 PG 15 WC Automation & Control Systems; Computer Science, Theory & Methods; Operations Research & Management Science SC Automation & Control Systems; Computer Science; Operations Research & Management Science GA RY576 UT WOS:A1995RY57600006 ER PT J AU TAYLOR, RP STEELE, WG DOUGLAS, F AF TAYLOR, RP STEELE, WG DOUGLAS, F TI UNCERTAINTY ANALYSIS OF ROCKET MOTOR THRUST MEASUREMENTS WITH CORRELATED BIASES SO ISA TRANSACTIONS LA English DT Article DE UNCERTAINTY; SYSTEMATIC; CORRELATION; ROCKET AB The uncertainty analysis of a rocket motor thrust measurement and calibration system is presented. The thrust measurement system has 10 load cells with 5 in tension and 5 in compression, and the calibration system has 6 load cells. The elemental sources of load-cell random uncertainty considered are excitation voltage, amplifier stability and noise, and analog-to-digital conversion resolution. The elemental sources of load-cell systematic uncertainty (bias) considered are calibration, excitation voltage, nonlinearity, hysteresis, system alignment, and other mechanical sources such as friction. The calibration hierarchy and excitation systematic uncertainties are correlated since they have a common source. These correlation effects dominate the resulting thrust measurement uncertainties and form the focus of this study. The trust measurement uncertainty is up to three and a half times larger when correlation effects are considered relative to the case where correlation is neglected. C1 NASA,JOHN C STENNIS SPACE CTR,BAY ST LOUIS,MS 39529. RP TAYLOR, RP (reprint author), MISSISSIPPI STATE UNIV,DEPT MECH ENGN,MISSISSIPPI STATE,MS 39762, USA. NR 0 TC 1 Z9 1 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0019-0578 J9 ISA T JI ISA Trans. PD OCT PY 1995 VL 34 IS 3 BP 253 EP 259 DI 10.1016/0019-0578(95)00016-S PG 7 WC Automation & Control Systems; Engineering, Multidisciplinary; Instruments & Instrumentation SC Automation & Control Systems; Engineering; Instruments & Instrumentation GA TF313 UT WOS:A1995TF31300005 ER PT J AU WANG, JH ROSSOW, WB AF WANG, JH ROSSOW, WB TI DETERMINATION OF CLOUD VERTICAL STRUCTURE FROM UPPER-AIR OBSERVATIONS SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODEL; ISCCP AB A method is described to use rawinsonde data to estimate cloud vertical structure, including cloud-top and cloud-base heights, cloud-layer thickness, and the characteristics of multilayered clouds. Cloud-layer base and top locations are identified based on three criteria: maximum relative humidity in a cloud of at least 87%, minimum relative humidity of at least 84%, and relative humidity jumps exceeding 3% at cloud-layer top and base, where relative humidity is with respect to liquid water at temperatures greater than or equal to 0 degrees C and with respect to ice at temperatures less than 0 degrees C. The analysis method is tested at 30 ocean sites by comparing with cloud properties derived from other independent data sources. Comparison of layer-cloud frequencies of occurrence with surface observations shows that rawinsonde observations (RAOBS) usually detect the same number of cloud layers for low and middle clouds as the surface observers, but disagree more for high-level clouds, There is good agreement between the seasonal variations of RAOBS-determined top pressure of the highest cloud and that from the International Satellite Cloud Climate Project (ISCCP) data. RAOBS-determined top pressures of low and middle clouds agree better with ISCCP, but RAOBS often fail to detect very high and thin clouds. The frequency of multilayered clouds is qualitatively consistent with that estimated from surface observations. In cloudy soundings at these ocean sites, multilayered clouds occur 56% of the time and are predominately two layered. Multilayered clouds are most frequent (approximate to 70%) in the Tropics (10 degrees S-10 degrees N) and least frequent at subtropical eastern Pacific stations. The frequency of multilayered clouds is higher in summer than in winter at low-latitude stations (30 degrees S-30 degrees N), but the opposite variation appears at the two subtropical stations. The frequency distributions of cloud top, cloud base, and cloud-layer thickness and cloud occurrence as a function of height are also presented. The lowest layer of multilayered cloud systems is usually located in the atmospheric boundary layer. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP WANG, JH (reprint author), COLUMBIA UNIV, INST SPACE STUDIES, DEPT GEOL SCI, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Rossow, William/F-3138-2015 NR 38 TC 87 Z9 107 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD OCT PY 1995 VL 34 IS 10 BP 2243 EP 2258 DI 10.1175/1520-0450(1995)034<2243:DOCVSF>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RW334 UT WOS:A1995RW33400010 ER PT J AU OTTERMAN, J STARR, DO AF OTTERMAN, J STARR, DO TI ALTERNATIVE REGIMES OF SURFACE AND CLIMATE CONDITIONS IN SANDY ARID REGIONS - POSSIBLE RELEVANCE TO MESOPOTAMIAN DROUGHT 2200-1900 BC SO JOURNAL OF ARID ENVIRONMENTS LA English DT Article DE MESOPOTAMIA; VOLCANIC; CLIMATE CONDITIONS; SALTATING-SANDS SURFACE; EXTREME ARIDITY ID SOUTHERN ISRAEL; DESERT; ALBEDO; VEGETATION; SATELLITE; IMPACT AB Ten feedback factors acting in sandy arid regions tend to create two alternative regimes of surface and climate conditions: an equilibrium with Vegetated, Crusted soil, and Convective Precipitation, commonly in the 200-400 mm year(-1) range (VC-CP), and an equilibrium with a Saltating-Sands surface and Extreme Aridity (SS-EA). The recently described 300-year long drought in Mesopotamia following a deposition of volcanic dust in 2200 B.C. over the region may be explained as a transition from a VC-CP to an SS-EA regime. The transition is attributed to creation of saltation-favoring conditions by the volcanic layer, brought about by the choking-off of the plants. After the destruction of the soil-crusts, the high albedo saltating-sands surface adversely affected probabilities for convective precipitation. The change again to the VC-CP conditions around 1900 B.C. may have been triggered by unusual patterns of cyclonic activity that brought far-above-average precipitation to the region. (C) 1995 Academic Press Limited C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 33 TC 0 Z9 0 U1 1 U2 1 PU ACADEMIC PRESS (LONDON) LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0140-1963 J9 J ARID ENVIRON JI J. Arid. Environ. PD OCT PY 1995 VL 31 IS 2 BP 127 EP 135 DI 10.1006/jare.1995.0055 PG 9 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA RZ577 UT WOS:A1995RZ57700001 ER PT J AU TSURUTANI, BT GONZALEZ, WD AF TSURUTANI, BT GONZALEZ, WD TI THE FUTURE OF GEOMAGNETIC STORM PREDICTIONS - IMPLICATIONS FROM RECENT SOLAR AND INTERPLANETARY OBSERVATIONST SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; MAJOR MAGNETIC STORMS; SEMIANNUAL VARIATION; BZ EVENTS; WIND; MAGNETOSPHERE; CLOUDS; FIELDS AB Within the last 7-8 years, there has been a substantial growth in our knowledge of the solar and interplanetary causes of geomagnetic storms at Earth. This review article will not attempt to cover all of the work done during this period. This can be found elsewhere. Our emphasis here will be on recent efforts that expose important, presently unanswered questions that must be addressed and solved before true predictability of storms can be possible. Hopefully, this article will encourage some readers to join this effort and perhaps make major contributions to the field. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. INST NATL PESQUISAS ESPACIAIS,MANAUS,BRAZIL. NR 36 TC 37 Z9 38 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD OCT PY 1995 VL 57 IS 12 BP 1369 EP 1384 DI 10.1016/0021-9169(95)00138-R PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TJ901 UT WOS:A1995TJ90100003 ER PT J AU SALATHE, EP CHESTERS, D SUD, YC AF SALATHE, EP CHESTERS, D SUD, YC TI EVALUATION OF THE UPPER-TROPOSPHERIC MOISTURE CLIMATOLOGY IN A GENERAL-CIRCULATION MODEL USING TOVS RADIANCE OBSERVATIONS SO JOURNAL OF CLIMATE LA English DT Article ID RELATIVE-HUMIDITY; BIOSPHERE MODEL; PARAMETERIZATION AB TOVS satellite observations are used to evaluate the upper-tropospheric (400-200 mb) moisture distribution simulated by the GLA GCM in a 10-yr (1979-1988) integration produced for the Atmospheric Model Intercomparison Project, in which several models participated worldwide. The simulated moisture fields show remarkable success in duplicating the large-scale structure and seasonal features in the observations, but they show insufficient contrast between very dry and very moist regions. The simulation generally does well in northern summer (June-July-August) but worse in northern winter. This is consistent with deficiencies in the annual cycle of moist convection so that convective rain stays too close to the equator in northern winter. The related misplacement of convective activity associated with the Asian monsoon produces discrepancies in the moisture over much of the Eastern Hemisphere. The simulation also shows a too weak moisture response to interannual fluctuations in the sea surface temperature, even for the large Fl Nino episode of 1983. These results indicate that deficiencies in modeling oceanic convection may be in part responsible for errors in the simulated upper-tropospheric moisture patterns. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 27 TC 15 Z9 15 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT PY 1995 VL 8 IS 10 BP 2404 EP 2414 DI 10.1175/1520-0442(1995)008<2404:EOTUTM>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TA262 UT WOS:A1995TA26200008 ER PT J AU WANG, YJ GOWAYED, Y KONG, XM LI, J ZHAO, DM AF WANG, YJ GOWAYED, Y KONG, XM LI, J ZHAO, DM TI PROPERTIES AND ANALYSIS OF COMPOSITES REINFORCED WITH E-GLASS WEFT-KNITTED FABRICS SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE TEXTILE COMPOSITES; WEFT KNIT; MECHANICAL PROPERTIES; FAILURE MECHANISMS; THEORETICAL ANALYSIS AB Weft-knitted 1 x 1 rib-fabrics are manufactured from E-glass rovings and are consolidated into flat panels using the resin transfer molding (RTM) process. The panels, with about 50% fiber volume fraction, are tested for their mechanical properties in tension, flexure, compression, and short-beam shear. The property values are reported and the failure mechanisms under different loading conditions are identified and compared. The elastic properties of the knitted composites are analyzed by geometric modeling followed by the finite element analysis (FEA). Good predictions are obtained. C1 AUBURN UNIV,DEPT TEXT ENGN,AUBURN,AL 36849. CLEMSON UNIV,SCH TEXT FIBER & POLYMER SCI,CLEMSON,SC 29634. NASA,LANGLEY RES CTR,NATL RES COUNCIL,HAMPTON,VA 23681. RP WANG, YJ (reprint author), GEORGIA INST TECHNOL,SCH TEXT & FIBER ENGN,ATLANTA,GA 30332, USA. NR 14 TC 6 Z9 6 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD OCT PY 1995 VL 17 IS 4 BP 283 EP 288 PG 6 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA TC994 UT WOS:A1995TC99400001 ER PT J AU FUHRMANN, DR BARO, JA COX, JR AF FUHRMANN, DR BARO, JA COX, JR TI EXPERIMENTAL EVALUATION OF PSYCHOPHYSICAL DISTORTION METRICS FOR JPEG-ENCODED IMAGES SO JOURNAL OF ELECTRONIC IMAGING LA English DT Article AB Two experiments for evaluating psychophysical distortion metrics in Joint Photographic Experts Group (JPEG) encoded images are described. The first is a threshold experiment, in which subjects determined the bit rate or level of distortion at which distortion was just noticeable. The second is a suprathreshold experiment in which subjects ranked image blocks according to perceived distortion. The results of these experiments were used to determine the predictive value of a number of computed image distortion metrics. It was found that mean-square-error is not a good predictor of distortion thresholds or suprathreshold perceived distortion. Some simple pointwise measures were in good agreement with psychophysical data; other more computationally intensive metrics involving spatial properties of the human visual system gave mixed results. It was determined that mean intensity, which is not accounted for in the JPEG algorithm, plays a significant role in perceived distortion. C1 NASA,WHEELING JESUIT COLL,CLASSROOM FUTURE,WHEELING,WV 26003. WASHINGTON UNIV,DEPT COMP SCI,ST LOUIS,MO 63130. RP FUHRMANN, DR (reprint author), WASHINGTON UNIV,DEPT ELECT ENGN,ST LOUIS,MO 63130, USA. NR 15 TC 39 Z9 41 U1 0 U2 1 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 1017-9909 J9 J ELECTRON IMAGING JI J. Electron. Imaging PD OCT PY 1995 VL 4 IS 4 BP 397 EP 406 DI 10.1117/12.220346 PG 10 WC Engineering, Electrical & Electronic; Optics; Imaging Science & Photographic Technology SC Engineering; Optics; Imaging Science & Photographic Technology GA TC359 UT WOS:A1995TC35900007 ER PT J AU Tang, P Palazzolo, AB Kascak, AF Montague, GT AF Tang, P Palazzolo, AB Kascak, AF Montague, GT TI Active vibration control of rotating machinery with a hybrid piezohydraulic actuator system SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS AB An integrated, compact piezohydraulic actuator system for active vibration control was designed and developed with a primary application for gas turbine aircraft engines. Copper tube was chosen as the transmission line material for ease of assembly. Liquid plastic, which meets incompressibility and low-viscosity requirements, was adjusted to provide optimal actuator performance. Variants of the liquid plastic have been prepared with desired properties between -40 degrees F and 400 degrees F. The effectiveness of this hybrid actuator for active vibration control (AVC) was demonstrated for suppressing critical speed vibration through two critical speeds for various levels of intentionally placed imbalance. A high-accuracy closed-loop simulation, which combines both finite element and state space methods, was applied for the closed-loop unbalance response simulation with/without AVC. Good correlation between the simulation and test results was achieved. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Tang, P (reprint author), TEXAS A&M UNIV,COLLEGE STN,TX 77843, USA. NR 14 TC 2 Z9 2 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 767 EP 776 DI 10.1115/1.2815463 PG 10 WC Engineering, Mechanical SC Engineering GA TT881 UT WOS:A1995TT88100016 ER PT J AU Freed, AD AF Freed, AD TI Natural strain SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures afiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of the fundamental body-metric tensors of Lodge. These strain and strain-race measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian stare is obtained. RP Freed, AD (reprint author), NASA,LEWIS RES CTR,COMPUTAT MAT LAB,MS 105-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. OI Freed, Alan/0000-0002-3492-0628 NR 26 TC 24 Z9 25 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 379 EP 385 DI 10.1115/1.2804729 PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA TT876 UT WOS:A1995TT87600007 ER PT J AU Newman, JC AF Newman, JC TI Fatigue-life prediction methodology using a crack-closure model SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB This paper reviews the capabilities of a plasticity-induced crack-closure model and life-prediction code, FASTRAN, to predict fatigue lives of metallic materials using small-crack theory. Crack-tip constraint factors, to account for three-dimensional state-of-stress effects, were selected to correlate large-crack growth rate data as a function of the effective-stress-intensity factor range (Delta K-eff) under constant-amplitude loading. Some modifications to the Delta K-eff-rate relations were needed in the near-threshold regime to fit small-crack growth rate behavior and endurance limits. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched specimens made of several aluminum alloys and a titanium alloy under constant-amplitude and spectrum loading. Fatigue lives were calculated using the crack-growth relations and microstructural features like those that initiated cracks for the aluminum alloys. An equivalent-initial-flaw-size concept was used to bound the fatigue lives for the titanium alloy. Results from the tests and analyses agreed well. RP Newman, JC (reprint author), NASA,LANGLEY RES CTR,MECH MAT BRANCH,HAMPTON,VA 23681, USA. NR 28 TC 32 Z9 32 U1 1 U2 5 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 433 EP 439 DI 10.1115/1.2804736 PG 7 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA TT876 UT WOS:A1995TT87600014 ER PT J AU FRANK, LA ASHOURABDALLA, M BERCHEM, J RAEDER, J PATERSON, WR KOKUBUN, S YAMAMOTO, T LEPPING, RP CORONITI, FV FAIRFIELD, DH ACKERSON, KL AF FRANK, LA ASHOURABDALLA, M BERCHEM, J RAEDER, J PATERSON, WR KOKUBUN, S YAMAMOTO, T LEPPING, RP CORONITI, FV FAIRFIELD, DH ACKERSON, KL TI OBSERVATIONS OF PLASMAS AND MAGNETIC-FIELDS IN EARTHS DISTANT MAGNETOTAIL - COMPARISON WITH A GLOBAL MHD MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MAGNETOHYDRODYNAMIC SIMULATION; NONLINEAR DYNAMICS; GEOMAGNETIC TAIL; ALIGNED CURRENTS; ELECTRIC-FIELDS; BOW SHOCK; MAGNETOSPHERE; RECONNECTION; MAGNETOSHEATH AB We are reporting the first direct comparison of in situ observations of plasmas and magnetic fields in Earth's distant magnetotail with the results of a time-dependent, global magnetohydrodynamic (MHD) simulation of the interaction of the solar wind with the magnetosphere. The magnetotail observations of were taken with the Geotail spacecraft during the period 0300-0630 UT on October 27, 1992 at a position near the dawnside magnetopause at a downstream distance of about 81 R(E). During this period a dense, cold ion stream similar in density and speed to that expected for the magnetosheath plasmas was intermittently observed. When the cold ion stream was not present, the spacecraft was located in the northern magnetotail lobe. The dense, cold ion stream differed from that expected for the magnetosheath in the Y and Z components of ion bulk flow and in the Y component of the magnetic field. These cold ion streams are associated with a magnetopause accommodation region positioned just outside the classical magnetopause, as identified by a well-defined transition from magnetic fields typical of those found in the lobe to the lesser and more fluctuating fields in the magnetosheath. This accommodation region exhibits perturbations in plasma flows and magnetic fields that appear to be related to the complex topology of the magnetopause at these large downstream positions. Simultaneous observations of the solar wind ions and the interplanetary magnetic field (IMF) with the IMP 8 spacecraft upstream from Earth provided the driving input for a global MHD model. The solar wind ion flow was steady during this period, and the IMF exhibited a series of rotations from northward to duskward. The dynamics of the magnetotail were controlled by the Y and Z components of the IMF. When this By was strongly positive, the magnetotail lobe appeared at the downstream Geotail position. Examination of the modeled plasma parameters in the Y-Z plane through the spacecraft position shows that this By provides a torque on the magnetotail about its central axis. The MHD model also accurately positions the spacecraft alternately in the magnetopause accommodation region and the magnetotail lobe as the IMF clock angle varied from northward to duskward, respectively. The temporal variations of modeled parameters, i.e., ion densities, temperatures, and bulk flow velocities and the magnetic field components, are directly compared with the Geotail measurements. This first comparison of the Geotail observations with the modeled plasma parameters and magnetic fields provides substantial encouragement that a global MHD model can provide a valid description of important aspects of the large-scale topology and dynamics of the magnetotail. C1 UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,DEPT PHYS & ASTRON,LOS ANGELES,CA 90024. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA,AICHI 442,JAPAN. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. RP FRANK, LA (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. RI Paterson, William/F-5684-2012 NR 48 TC 45 Z9 45 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19177 EP 19190 DI 10.1029/95JA00571 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400010 ER PT J AU BIRN, J GARY, SP HESSE, M AF BIRN, J GARY, SP HESSE, M TI MICROSCALE ANISOTROPY REDUCTION AND MACROSCALE DYNAMICS OF THE MAGNETOTAIL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA SHEET; NEUTRAL SHEET; TEARING INSTABILITY; TAIL; MECHANISM; PRESSURE AB Anisotropic magnetofluid simulations are used to investigate the influence of several models of anisotropy reduction on the dynamic evolution of the magnetotail. Two distinct magnetotail dynamic models are studied: a nonresistive simulation driven by an external electric field as a representation of the substorm growth phase, and a resistive simulation with a uniform enhanced resistivity as a representation of the substorm expansive phase. The plasma models include one which is fully isotropic, the double adiabatic model in which pressures parallel and perpendicular to the background magnetic field are completely uncoupled, and a model in which small-scale instabilities impose an upper bound on the anisotropy. In this last model, anisotropies that exceed this bound are reduced on a short Alfvenic timescale. To investigate the transition to the fully isotropic model, a fourth plasma model is studied in which any anisotropy is reduced on the same short timescale. The growth phase magnetotail model is characterized by a localised increase in current density and by a reduction in the magnitude of B-z in the near-Earth neutral sheet; both of these effects are more pronounced for the more isotropic plasma models, For the expansive phase magnetotail model the development of a generalized tearing instability occurs faster and the substorm wedge currents grow stronger when the plasma model is closer to isotropy. In both magnetotail models the plasma anisotropy model strongly influences the spatial variation of B-z in the neutral sheet and hence the location where reconnection occurs and a neutral line forms. Both the driven and the unstable anisotropic models develop mirror-type anisotropies (p perpendicular to > p parallel to) in the (low beta or low current density) boundary regions of the plasma sheet and the adjacent lobes, while the (high beta or high current density) center region of the plasma/current sheet remains close to isotropy. C1 NASA, GODDARD SPACE FLIGHT CTR, ELECTRODYNAM BRANCH, GREENBELT, MD 20771 USA. RP LOS ALAMOS NATL LAB, SPACE & ATMOSPHER SCI GRP, MS D466, LOS ALAMOS, NM 87545 USA. RI Hesse, Michael/D-2031-2012 NR 28 TC 17 Z9 18 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19211 EP 19220 DI 10.1029/95JA01401 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400012 ER PT J AU FARRUGIA, CJ ERKAEV, NV BIERNAT, HK BURLAGA, LF AF FARRUGIA, CJ ERKAEV, NV BIERNAT, HK BURLAGA, LF TI ANOMALOUS MAGNETOSHEATH PROPERTIES DURING EARTH PASSAGE OF AN INTERPLANETARY MAGNETIC CLOUD SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC CONVECTION; DAYSIDE MAGNETOPAUSE; FIELD; MAGNETOSPHERE; PLASMA; FLOW; SLOW; DEPLETION; SHOCK; LOOP AB The aim of this paper is to model for the first time the variation of field and flow parameters in the magnetosheath during Earth passage of an interplanetary magnetic cloud. Under typical solar wind conditions, magnetohydrodynamic (MHD) effects on the flow of plasma in the terrestrial magnetosheath are important only in a layer adjacent to the magnetopause which is a few thousand kilometers thick (''depletion layer'' or ''magnetic barrier''). During the passage of an interplanetary magnetic cloud, however, conditions upstream of the bow shock depart strongly from the norm. In this case, interplanetary parameters vary slowly over a wide range of values. Values of the upstream Alfven,Mach number are much lower than those otherwise sampled (similar to 3 versus 8-10). Together with the magnetic shear across the magnetopause, this parameter plays a central role in determining the structure of the magnetosheath. close to the magnetopause. As a consequence of sustained low values of the: upstream Alfven Mach number, the magnetic field exerts a strong influence on the flow over a very substantial fraction of the magnetosheath throughout the duration of cloud passage, i.e., for a time period of the order of 1-2 days. We apply an algorithm to integrate. the ideal MHD equations, using a boundary layer technique, and compute the variations of held and flow parameters along the stagnation streamline. We choose as our example the magnetic cloud which passed Earth on January 14-15, 1988. The interaction of this cloud with the magnetosphere, as regards the resulting ionospheric flow patterns and the substorm activity, has been the subject of various investigations. Using information from these studies, we obtain results on the magnetosheath when the magnetopause is modeled, first as a tangential discontinuity and then as a rotational discontinuity. Our results are in good general agreement with recent observations on the behavior of field and flow quantities in the magnetosheath region adjacent to the magnetopause. In addition, we predict the existence of a magnetic barrier when the upstream Alfven Mach number is low, irrespective of the magnetic shear across the magnetopause. C1 AKAD WISSENSCH GRAZ, INST WELTRAUMFORSCH, A-8042 GRAZ, AUSTRIA. RUSSIAN ACAD SCI, CTR COMP, AKADEMGORODOK 660036, RUSSIA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP FARRUGIA, CJ (reprint author), UNIV MALTA, DEPT MATH SCI & TECH EDUC, MSIDA, MALTA. RI Erkaev, Nikolai/M-1608-2013 OI Erkaev, Nikolai/0000-0001-8993-6400 NR 38 TC 59 Z9 59 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19245 EP 19257 DI 10.1029/95JA01080 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400016 ER PT J AU TAGUCHI, S HOFFMAN, RA AF TAGUCHI, S HOFFMAN, RA TI B-X CONTROL OF POLAR-CAP POTENTIAL FOR NORTHWARD INTERPLANETARY MAGNETIC-FIELD SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC CONVECTION; AURORAL DISTRIBUTION; CONFIGURATION; PATTERNS; IMF AB We have examined how the magnitude of the polar cap potential for northward interplanetary magnetic field (IMF) changes with the angle of the field in the B-X/B-Z plane. From the dawn-dusk passes (November-December 1981, May-June 1982, and November-December 1982) of the Dynamics Explorer 2 satellite, we selected 363 passes by requiring the IMF hourly value B-Z greater than or equal to 1 nT for the preceding 2-hour interval. Of these, 72 cases displayed a reverse convection pattern in the electric field data, i.e., sunward at the highest latitudes and antisunward at lower latitudes. The potential difference across the region of sunward convection correlates well with various functions that consist of all or some of the IMF parameters, B-Z, B-Y, the B-Y/B-Z angle, and the solar wind velocity. We ''normalize'' the potential, using these functions. To test for a B-X dependence while eliminating dipole tilt effects, we introduce phi(h)*, the angle between the IMF vector projected to the X-Z meridian and the Earth dipole axis. The normalized potential F for the northern hemisphere is the largest when phi(h)*, measured from the northern dipole axis toward the Sun, is negative and large (similar to -100 degrees), and decreases as phi(h)* approaches zero and turns positive. An approximate equation for this relation is F(phi(h)*) = a + b /(phi(h)* + 125 degrees), where the values for a and b lie between 0.0086 and 0.015 and between 1.6 and 1.9, respectively. This relation can be interpreted in terms of a model of magnetosheath field line motion which predicts that the reconnection belt on the magnetopause poleward of the cusp becomes longer as the magnetosheath field lines tilt toward the tail lobe. RP TAGUCHI, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 696,GREENBELT,MD 20771, USA. NR 19 TC 13 Z9 13 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19313 EP 19320 DI 10.1029/95JA01085 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400022 ER PT J AU HIGGINS, CA GREEN, JL THIEMAN, JR FUNG, SF CANDEY, RM AF HIGGINS, CA GREEN, JL THIEMAN, JR FUNG, SF CANDEY, RM TI STRUCTURE WITHIN JOVIAN HECTOMETRIC RADIATION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RADIO ASTRONOMY OBSERVATIONS; SOLAR-WIND CONTROL; EMISSION; JUPITER; VOYAGER AB Observations of Jovian hectometric radio emission (HOM) by the Voyager planetary radio astronomy (PRA) experiment at frequencies from 300 kHz to 1.3 MHz indicate persistent dynamic spectral features that had not been previously studied. The features of interest appear as ''lanes'' of decreased emission intensity within the otherwise persistent HOM. The lanes are apparent in intensity and occurrence probability spectrograms of frequency versus Jovian System III (1965) longitude. In the investigation of the morphology of these features, we use inbound and outbound Voyager 2 data at Jupiter to show that the lane occurrence and characteristics do not depend on local time over the range sampled. Occurrence probability spectrograms of frequency versus magnetic latitude are created from the portion of the data when the spacecraft was between 0 degrees and +10 degrees magnetic latitude. These spectrograms represent both the inbound and outbound passes and are quite similar despite the different longitude ranges. A simple extension of decametric (DAM) arc features into the HOM wavelength does not account for all the lane features, giving further evidence that HOM is an independent emission component. Polarization signatures for the data show that the polarization is predominantly right-hand circular and that it does not reverse across the lanes, suggesting the emission is from the same hemisphere. In addition, we investigate possible effects due to solar wind variations and find that the occurrence of the lanes appears to be independent of times of low and high solar wind densities. The intensity of the HOM emission on either side of the lanes is comparable, implying that the lane is probably not a result of a gap between fundamental and second harmonic emission regions. We present these data and analyses asa morphological study to establish that the lane features are an important part of the HOM emission and should be considered in HOM emission models. At this time, no theory of the source of the lanes explains all the observed features. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE SCI DATA OPERAT OFF,GREENBELT,MD 20771. RP HIGGINS, CA (reprint author), UNIV FLORIDA,DEPT ASTRON,POB 112055,GAINESVILLE,FL 32611, USA. RI Candey, Robert/D-4639-2012; Fung, Shing/F-5647-2012 NR 25 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 OCT 1 PY 1995 VL 100 IS A10 BP 19487 EP 19496 DI 10.1029/95JA01128 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400037 ER PT J AU MIHALOV, JD RUSSELL, CT KASPRZAK, WT KNUDSEN, WC AF MIHALOV, JD RUSSELL, CT KASPRZAK, WT KNUDSEN, WC TI OBSERVATIONS OF IONOSPHERIC ESCAPE ON VENUS NIGHTSIDE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MASS-SPECTROMETER; ENERGETIC IONS; PIONEER; IONOTAIL AB A population of low-energy (0 - 250 V E/q) ions with tailward directed velocity vectors and energies above that for escape from Venus is evident in nightside data from the Ames plasma analyzer on the Pioneer Venus Orbiter spacecraft. Good correlations with solar wind parameters were not obtained for the magnitudes of these ion fluxes, but tendencies for occurrence at times of tailward oriented magnetic fields and for alignment of the ion flows with the magnetic field were found. These tendencies seemed to be enhanced for higher-energy ions. In a few cases where comparisons were made, the ion fluxes were consistent with simultaneous O+ measurements by the neutral mass spectrometer experiment on the spacecraft. The mean flux observed of the escaping nightside ions, averaged over an approximately 10-week-long spacecraft nightside season, was < 2 x 10(6) cm(-2) s(-1). C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. KNUDSEN GEOPHYS RES,MONTE SERENO,CA 95030. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. RP MIHALOV, JD (reprint author), NASA,AMES RES CTR,PLANETARY SYST BRANCH,MAIL STOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 18 TC 4 Z9 4 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 OCT 1 PY 1995 VL 100 IS A10 BP 19579 EP 19584 DI 10.1029/95JA01342 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400046 ER PT J AU GREENWALD, RA BRISTOW, WA SOFKO, GJ SENIOR, C CERISIER, JC SZABO, A AF GREENWALD, RA BRISTOW, WA SOFKO, GJ SENIOR, C CERISIER, JC SZABO, A TI SUPER DUAL AURORAL RADAR NETWORK RADAR IMAGING OF DAYSIDE HIGH-LATITUDE CONVECTION UNDER NORTHWARD INTERPLANETARY MAGNETIC-FIELD - TOWARD RESOLVING THE DISTORTED 2-CELL VERSUS MULTICELL CONTROVERSY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BIRKELAND CURRENTS; IMF-BY; IONOSPHERE; REGION; MODEL AB Data from the Kapuskasing and Saskatoon radars of the evolving Super Dual Auroral Radar Network (SuperDARN) HF radar network have been analyzed to study the two-dimensional structure and dynamics of dayside high-latitude ionospheric convection under northward interplanetary magnetic field (IMF) conditions. A period extending from 1600 to 2030 UT (similar to 0900-1330 MLT) on January 10, 1994, was examined, During this interval, magnetic field data were available from the LMP 8 satellite and indicated moderately stable northward IMF conditions. For the first few hours of observation the B-y component of the IMF was positive, reasonably steady, and approximately twice the magnitude of B-z. During this interval, the high-latitude convection images obtained with the SuperDARN radars were very similar to the distorted two-cell convection maps for positive B-y as presented by Heppner and Maynard (1987). At similar to 1840 UT, a decrease in B-y in association with an increase in B-z, led to an extended period with B-y approximate to B-z. During this second interval the convection patterns were highly variable and even chaotic. Finally, a sharp decrease in the B-y component at 1914 UT, probably in association with a rotational discontinuity in the solar wind, led to an extended period with B-y much less than B-z. During this third interval, the high latitude convection pattern was again stable and exhibited a single counterclockwise rotating vortex consistent with one of the polar cap merging cells proposed by Dungey (1963), Burke et al. (1979), and Reiff and Heelis (1994). The transition to the counterclockwise rotating vortex occurred over a large spatial area within two radar scans (200 s) and appeared to proceed via an equatorward incursion of the vortex into the previous convection configuration. Once this polar cap merging cell was formed, it remained stable for the remainder of the period (similar to 40 min) that B-y remained small. Sunward convection was also observed in the polar cap of the conjugate hemisphere at 1932 UT by the DMSP F11 satellite, confirming that both magnetopause and internal reconnection sites were active at that time. C1 CNRS,CTR ETUD ENVIRONM TERR & PLANETAIRES,F-94107 ST MAUR FOSSES,FRANCE. UNIV SASKATCHEWAN,DEPT PHYS & ENGN PHYS,SASKATOON,SK S7N 0W0,CANADA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GREENWALD, RA (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,JOHNS HOPKINS RD,LAUREL,MD 20723, USA. NR 33 TC 53 Z9 53 U1 2 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19661 EP 19674 DI 10.1029/95JA01215 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400052 ER PT J AU LIEWER, PC RATH, S GOLDSTEIN, BE AF LIEWER, PC RATH, S GOLDSTEIN, BE TI HYBRID SIMULATIONS OF INTERSTELLAR PICKUP ION-ACCELERATION AT THE SOLAR-WIND TERMINATION SHOCK SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PARTICLE-ACCELERATION; ANOMALOUS COMPONENT; OBLIQUE SHOCKS; DRIFT; INJECTION; DIFFUSION AB Hybrid (Kinetic ion/fluid electron) simulations have been used to study self-consistently the injection and initial stages of acceleration of interstellar pickup ions at the solar wind termination shock. Results are presented from one-dimensional simulations of high Mach number oblique (40 degrees-50 degrees) shocks with a 10% population of interstellar pickup hydrogen. In these simulations, the pickup ions, the solar wind ions, the shock fields and the waves are all treated self-consistently. Pickup ions reflected by the shock excite large amplitude (Delta B/B similar to 0.3) upstream magnetosonic waves. These waves, in rum, scatter the pickup hydrogen, as expected in the diffusive shock acceleration process. The spectrum of excited waves broadens in time. We find that, for the parameters studied, the termination shock efficiently injects and accelerates the interstellar pickup hydrogen, and thus this work represents a microscopic verification of this anomalous cosmic ray injection mechanism. Comparison of injected fluxes from the simulations with Voyager fluxes extrapolated to the termination shock suggests that injection at the termination shock is probably greater than injection by interplanetary shocks, A study of accelerated pickup ion orbits shows that the energy gain comes predominantly from shock drift acceleration in the shock front, with the upstream waves aiding the acceleration by allowing multiple encounters with the shock. C1 UNIV TORONTO, DEPT PHYS, TORONTO, ON M5S 1A7, CANADA. RP LIEWER, PC (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 25 TC 30 Z9 30 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 OCT 1 PY 1995 VL 100 IS A10 BP 19809 EP 19818 DI 10.1029/95JA01300 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400065 ER PT J AU VERMA, MK ROBERTS, DA GOLDSTEIN, ML AF VERMA, MK ROBERTS, DA GOLDSTEIN, ML TI TURBULENT HEATING AND TEMPERATURE EVOLUTION IN THE SOLAR-WIND PLASMA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY ALFVENIC FLUCTUATIONS; MAGNETOHYDRODYNAMIC TURBULENCE; RADIAL EVOLUTION; INERTIAL RANGE; VELOCITY FLUCTUATIONS; ENERGY-TRANSFER; MHD TURBULENCE; EQUATION; SPECTRA; INTERMITTENCY AB We calculate the turbulent dissipation rate of incompressive hydromagnetic fluctuations and the resulting radial evolution of temperature in the solar wind using generalizations of Kolmogorov and Kraichnan MHD turbulence phenomenologies that include the suppression of dissipation by high cross helicity. The results for the temperature evolution are compared to a variety of data sets to test the phenomenologies over a wide parameter range. Motivated by the observations, we use different power laws in radius for the amplitudes of Alfvenic and non-Alfvenic fluctuations to determine the cascade rates. To explain the observations using Kolmogorov-like models, we found it necessary to suppress the dissipation rates for the high cross helicity streams even further than predicted by simple models; this may be due to the nonequilibrium nature of the spectrum or to other causes as yet unknown. The Kolmogorov-like model gives rise to a significant amount of turbulent heating, implying that turbulent heating, while likely dominant only in the inner heliosphere, may be competitive with heating by shocks and the assimilation of interstellar pickup ions in the outer heliosphere. In contrast, the generalized Kraichnan phenomenology yields less turbulent heating than the Kolmogorov-like model and seems inadequate to explain the observations. We conclude that while no existing turbulence model adequately explains the observed radial dependence of temperature in the solar wind, there appears to be sufficient energy available for turbulent heating to contribute significantly, even in the outer heliosphere. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP VERMA, MK (reprint author), INDIAN INST TECHNOL, DEPT PHYS, KANPUR 208016, UTTAR PRADESH, INDIA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008; verma, mahendra/G-4041-2013 OI verma, mahendra/0000-0002-3380-4561 NR 56 TC 50 Z9 50 U1 1 U2 7 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 OCT 1 PY 1995 VL 100 IS A10 BP 19839 EP 19850 DI 10.1029/95JA01216 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400068 ER PT J AU MCCOMAS, DJ BARRACLOUGH, BL GOSLING, JT HAMMOND, CM PHILLIPS, JL NEUGEBAUER, M BALOGH, A FORSYTH, RJ AF MCCOMAS, DJ BARRACLOUGH, BL GOSLING, JT HAMMOND, CM PHILLIPS, JL NEUGEBAUER, M BALOGH, A FORSYTH, RJ TI STRUCTURES IN THE POLAR SOLAR-WIND - PLASMA AND FIELD OBSERVATIONS FROM ULYSSES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB Ulysses has frequently observed solar wind structures lasting from several hours to several days since it passed into the region of solar wind emanating from the southern polar coronal hole at similar to 36 degrees S. In addition to previously reported Alfven waves and coronal mass ejections, two other sorts of structures are routinely evident. This paper provides the first report of these structures in the high-latitude solar wind: (1) small-scale compressional structures and (2) pressure balance structures. The compressional structures are driven by faster solar wind overtaking slower solar wind ahead of it and exhibit the plasma and field properties expected for compressions. Unlike large-scale stream interaction regions observed in and near the ecliptic plane, these structures are much smaller scale and are nonrecurring from one rotation to the next. These smaller-scale compressional structures appear to arise preferentially from a limited (similar to 120 degrees of heliolongitude) region in the southern polar coronal hole. The pressure balance structures, on the other hand, are indicated by roughly equal increases in the plasma pressure and decreases in the magnetic field pressure, These structures, which are several degrees across, are more dense and have higher plasma pressures and betas than the surrounding solar wind. These pressure balance structures may be the interplanetary manifestations of ''polar plumes.'' C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP MCCOMAS, DJ (reprint author), LOS ALAMOS NATL LAB,SPACE & ATMOSPHER SCI GRP,POB 1663,MS D466,LOS ALAMOS,NM 87545, USA. NR 23 TC 51 Z9 51 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 OCT 1 PY 1995 VL 100 IS A10 BP 19893 EP 19902 DI 10.1029/95JA01634 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400072 ER PT J AU ERKAEV, NV FARRUGIA, CJ BIERNAT, HK BURLAGA, LF BACHMAIER, GA AF ERKAEV, NV FARRUGIA, CJ BIERNAT, HK BURLAGA, LF BACHMAIER, GA TI IDEAL MHD FLOW BEHIND INTERPLANETARY SHOCKS DRIVEN BY MAGNETIC CLOUDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOSHEATH; MAGNETOSPHERE; PLASMA AB We present an ideal MHD theory to describe for the first time the ''magnetic barrier'' (or ''depletion layer'') of that class of interplanetary ejecta called magnetic clouds. By ''magnetic barrier'' we mean that region of the sheath where the magnetic pressure is comparable to, or larger than, the gas pressure and where, therefore, the effects of the magnetic field on the flow are substantial, We model magnetic clouds as cylindrical flux ropes. We consider three cases: one steady state and two nonsteady situations. The two nonsteady situations correspond to (1) a self-similarly expanding magnetic cloud, and (2) to a nonexpanding magnetic cloud which has a net bulk motion with respect to the medium at infinity. In all cases the cloud drives an interplanetary shock ahead of it. We describe an algorithm to integrate the MHD equations in which the: behavior of the sum of the magnetic and plasma pressure: is prescribed. We assume here that the sum of the magnetic and plasma pressure is constant along any line normal to the magnetic cloud boundary. We find that in steady state the cloud boundary cannot be a tangential discontinuity, that is, a finite magnetic barrier thickness can only be obtained with a reconnecting cloud boundary. In general, the magnetic barriers of magnetic clouds are thick, that is, they are a substantial fraction of the cloud's sheath. In steady state and the. nonsteady case (situation 2, above), their width depends inversely on the Alfven Mach number. The non-steady state (situation 1) has similarities with the problem of solar wind flow around the terrestrial magnetosphere. In particular, the. barrier thickness in this case. is proportional to the inverse square of the Alfven Mach number. This work should be useful in the interpretation of data from the sheath region ahead of magnetic clouds driving interplanetary shocks. C1 AUSTRIAN ACAD SCI, INST WELTRAUMFORSCH, A-8042 GRAZ, AUSTRIA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV MALTA, DEPT MATH SCI & TECH EDUC, MSIDA, MALTA. RP ERKAEV, NV (reprint author), RUSSIAN ACAD SCI, CTR COMP, KRASNOYARSK 36, AKADEMGORODOK 660036, RUSSIA. RI Erkaev, Nikolai/M-1608-2013 OI Erkaev, Nikolai/0000-0001-8993-6400 NR 40 TC 27 Z9 27 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19919 EP 19931 DI 10.1029/95JA01617 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400075 ER PT J AU HUDDLESTON, DE WOO, R NEUGEBAUER, M AF HUDDLESTON, DE WOO, R NEUGEBAUER, M TI DENSITY-FLUCTUATIONS IN DIFFERENT TYPES OF SOLAR-WIND FLOW AT 1-AU AND COMPARISON WITH RESULTS FROM DOPPLER SCINTILLATION MEASUREMENTS NEAR THE SUN SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID INTERPLANETARY DISTURBANCES; CORONAL STREAMERS; RADIO SCATTERING; TURBULENCE; DISCONTINUITIES; SPECTRUM; TRACKING; HELIUM AB Density fluctuations with periods in the range 10 min to 1 hour are investigated using ISEE 3 plasma measurements of solar wind flows at 1 AU. Coronal hole, interstream, plasma sheet, coronal mass ejection, and interaction region flow types are considered. The ISEE 3 results are consistent with the interpretation of large-scale variations in density fluctuations observed by Doppler scintillation measurements inside 0.2 AU. The highest absolute and fractional density fluctuations are found ahead of and within the plasma from coronal mass ejections, with the maximum values occurring between the associated interplanetary shocks and the driver gas. For the quasi-stationary solar wind, density and fractional density fluctuations are highest and most variable in the plasma sheet in which the heliospheric current sheet is embedded, and lowest and least variable in the high-speed coronal hole flow. A superposed epoch analysis of heliospheric current sheet crossings shows that the regions of enhanced density fluctuations previously identified in Doppler scintillation measurements near the Sun persist to 1 AU and are broader there. The results of this study confirm the advantages of using density fluctuations rather than density as a tracer of solar wind flows of differing origins at the Sun and as a detector of propagating interplanetary disturbances. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP HUDDLESTON, DE (reprint author), UNIV CALIF LOS ANGELES, INST GEOPHYS & PLANETARY PHYS, LOS ANGELES, CA 90095 USA. NR 45 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1995 VL 100 IS A10 BP 19951 EP 19956 DI 10.1029/95JA01084 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY274 UT WOS:A1995RY27400078 ER PT J AU TIWARI, R TEWARI, SN ASTHANA, R GARG, A AF TIWARI, R TEWARI, SN ASTHANA, R GARG, A TI MECHANICAL-PROPERTIES OF EXTRUDED DUAL-PHASE NIAL ALLOYS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID INTERMETALLIC ALLOYS; AL-W; FRACTURE; DUCTILITY; TENSILE; FEAL AB The mechanical behaviour of dual-phase microstructures, consisting of elongated primary NiAl grains aligned with an intergranular NiAl/X eutectic phase, produced by extrusion of cast NiAl-X (where X=Cr and W) alloys, has been examined. Chromium, added to create a dual-phase NiAl-based aligned microstructure, resulted in large increases in the yield strength, but only marginal improvement in the toughness. In contrast, tungsten alloying leads to ductility or toughness increases with no significant strengthening. The constitutional hardening rate due to deviations from stoichiometry in Ni rich NiAl was estimated to be about 66 MPa (Ni-1 at%). C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TIWARI, R (reprint author), CLEVELAND STATE UNIV,DEPT CHEM ENGN,CLEVELAND,OH 44115, USA. NR 28 TC 6 Z9 6 U1 0 U2 0 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 OCT 1 PY 1995 VL 30 IS 19 BP 4861 EP 4870 DI 10.1007/BF01154496 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA RY260 UT WOS:A1995RY26000015 ER PT J AU JAYNE, DT MATTHIESEN, MM AF JAYNE, DT MATTHIESEN, MM TI REMOVING HYDROXYPROPYL METHYLCELLULOSE SIZING FROM SAPPHIRE FIBERS BY ULTRAVIOLET OZONE CLEANING SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Note ID MATRIX COMPOSITES; INTERFACES AB Ceramic-fiber-reinforced metallic and intermetallic matrix composites require well-characterized fiber/matrix interfaces. These interfaces require that the fiber surface be clean prior to the formation of a composite or application of a fiber coating. This work investigates the effectiveness of ultraviolet (UV)/ozone exposure at removing hydroxypropyl methylcellulose sizing from sapphire plates and fibers. The surface cleanliness was characterized using X-ray photoelectron spectroscopy (XPS). It was found that UV/ozone exposure removed the hydroxypropyl methylcellulose sizing from the plates and fibers but did not remove inorganic species contained in the coating or on the sapphire surface. These inorganic species were readily removed with a water/methanol rinse, providing a clean sapphire surface for incorporation into a composite. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP JAYNE, DT (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106, USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU AMER CERAMIC SOC 735 CERAMIC PLACE PI WESTERVILLE PA PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD OCT PY 1995 VL 78 IS 10 BP 2861 EP 2864 DI 10.1111/j.1151-2916.1995.tb08069.x PG 4 WC Materials Science, Ceramics SC Materials Science GA TJ791 UT WOS:A1995TJ79100043 ER PT J AU Rutkowski, MJ Ruzicka, GC Ormiston, RA Saberi, H Jung, Y AF Rutkowski, MJ Ruzicka, GC Ormiston, RA Saberi, H Jung, Y TI Comprehensive aeromechanics analysis of complex rotorcraft using 2GCHAS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB 2GCHAS is a comprehensive, multi-disciplinary, computer software system for predicting rotorcraft aeromechanics characteristics, It is a finite element based system with a variety of aerodynamic modeling options and provides modeling and analysis flexibility, prediction accuracy, and user-friendly input and output, The software is maintainable, expandable, and transportable to various computer platforms. The paper briefly describes the development of the System and key features for modeling complex rotorcraft, A series of rotorcraft analysis problems is presented to illustrate the range of capabilities available, including single and tandem rotor helicopters with engine/drive trains and feedback flight control systems, Various aerodynamic airloads, rotor wake, and component interference models are used in calculating performance, flight dynamic response, rotor loads and vibrations, and aeroelastic stability. C1 ADV ROTORCRAFT TECHNOL INC,MT VIEW,CA. RP Rutkowski, MJ (reprint author), USA,AVIAT & TROP COMMAND,AMES RES CTR,AEROFLIGHTDYNAM DIRECTORATE,DIV ROTORCRAFT DYNAM,MOFFETT FIELD,CA 94035, USA. NR 20 TC 9 Z9 9 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1995 VL 40 IS 4 BP 3 EP 17 PG 15 WC Engineering, Aerospace SC Engineering GA TM061 UT WOS:A1995TM06100001 ER PT J AU Cicolani, LS Kanning, G Synnestvedt, R AF Cicolani, LS Kanning, G Synnestvedt, R TI Simulation of the dynamics of helicopter slung load systems SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Equations of motion are derived for general slung load systems, Systematic approaches have not previously been studied for deriving slung load dynamic models, but an interest in simulation, analysis, and control for slung loads carried by two or more helicopters motivates attention to this topic, Slung load systems are approximated as several rigid bodies connected by suspensions consisting of straight line cables and links which can be assumed elastic or inelastic and which transmit force only along the link Equations for the general system are obtained from the Newton-Euler equations with the introduction of generalized speeds, Several systematic formulations are given which generalize previous case-specific results from the slung load literature or occur in the existing literature on the dynamics of multibody systems, A novel formulation is derived for inelastic suspensions from the elastic suspension equations and in which the constraint fortes appear explicitly, The result is computationally more efficient for slung loads than the other formulations, is readily combined with the elastic suspension equations in a single simulation, and is readily applied to complex dual and multilift systems. The new formulation is applied to a 4-body dual lift system, Simulation equations are given along with a review of issues related to simulation of the dynamics, and numerical results. RP Cicolani, LS (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 11 Z9 11 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1995 VL 40 IS 4 BP 44 EP 61 PG 18 WC Engineering, Aerospace SC Engineering GA TM061 UT WOS:A1995TM06100004 ER PT J AU Duyar, A Gu, Z Litt, JS AF Duyar, A Gu, Z Litt, JS TI A simplified dynamic model of the T700 turboshaft engine SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A simplified open-loop dynamic model of the T700 turboshaft engine, valid within the normal operating range df the engine, is developed. This model is obtained by linking linear state space models determined at different engine operating points. Each linear model is developed from a detailed nonlinear engine simulation using a multivariable system identification and realization method. The simplified model may be used with a model-based real time diagnostic scheme for fault detection and diagnostics, as well as for open loop engine dynamics studies and closed loop control analysis utilizing a user generated control law. C1 LEWIS RES CTR,US ARMY AVIAT SYST COMMAND,PROPULS DIRECTORATE,CLEVELAND,OH. RP Duyar, A (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. NR 16 TC 7 Z9 8 U1 0 U2 2 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 1995 VL 40 IS 4 BP 62 EP 70 PG 9 WC Engineering, Aerospace SC Engineering GA TM061 UT WOS:A1995TM06100005 ER PT J AU Harch, AP Dunham, DW Farquhar, RW Veverka, J Williams, BG Yeomans, DK AF Harch, AP Dunham, DW Farquhar, RW Veverka, J Williams, BG Yeomans, DK TI Encounter strategy for a flyby of the main-belt asteroid 253 Mathilde SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The NEAR trajectory provides the opportunity for a close flyby of the main-belt asteroid 253 Mathilde en route to the final destination, 433 Eros. Major science objectives include high-resolution imaging, a determination of the asteroid's mass, and a search for any intrinsic magnetic field. To achieve these objectives, the spacecraft must be targeted to within 1200 km of the asteroid and the camera pointed at the target near closest approach. We describe the details of the optical navigation and spacecraft pointing strategies that will be executed to achieve these goals. C1 JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. CALTECH,JET PROP LAB,NAVIGAT & FLIGHT MECH SECT,PASADENA,CA 91109. RP Harch, AP (reprint author), CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853, USA. NR 19 TC 8 Z9 8 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1995 VL 43 IS 4 BP 399 EP 415 PG 17 WC Engineering, Aerospace SC Engineering GA UF540 UT WOS:A1995UF54000005 ER PT J AU Yeomans, DK AF Yeomans, DK TI Asteroid 433 Eros: The target body of the NEAR mission SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article ID RADAR OBSERVATIONS; 433-EROS AB Asteroid 433 Eros was the first near-Earth asteroid to be discovered and nearly 100 years of ground-based observations have allowed a rough physical characterization of the body. Eros is a S-type asteroid whose dimensions are approximately 40.5 x 14.5 x 14.1 km. Its rotation is in a direct sense with a period of 5.27 hours and its geometric albedo is 0.17. Good observing opportunities in late 1995 and several months in 1998 will allow these physical parameters to be further refined. At the time of the NEAR spacecraft arrival in early 1999, the Eros ephemeris uncertainties will be less than 50 km based on ground-based astrometric observations alone. RP Yeomans, DK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 19 Z9 19 U1 0 U2 0 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1995 VL 43 IS 4 BP 417 EP 426 PG 10 WC Engineering, Aerospace SC Engineering GA UF540 UT WOS:A1995UF54000006 ER PT J AU Scheeres, DJ AF Scheeres, DJ TI Analysis of orbital motion around 433 Eros SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The Near Earth Asteroid Rendezvous (NEAR) mission spacecraft will arrive at asteroid 433 Eros in February 1999. Following an initial period of characterization, the science phase of the mission will commence, and unprecedented information concerning an asteriod's shape, mass, density, composition and rotational dynamics will be sent to Earth for analysis. It will also mark the start of orbital operations about the smallest mass and the most complex and irregular gravity field ever orbited in the history of space exploration. The smallness of Eros' mass and the severity of its distortion from the usual spheroid bodies encountered in planetary exploration leads to fundamental differences in the orbital dynamics about it. This paper reviews the expected orbital dynamics of the NEAR spacecraft at Eros and discusses the problem of orbit control of the NEAR spacecraft orbit. The dynamical environment may be differentiated according to whether the spacecraft is close to or far from Eros. When far from Eros, the spacecraft must contend with the solar tide and solar radiation pressure forces which are large perturbations to the Eros attractive force. When close to Eros, the spacecraft must contend with the irregular gravity held of the body. Orbits exist which are quite unstable and may crash onto the asteroid surface in a matter of days. Obviously, it is important to understand when and where such orbits exist, and how they may be avoided. There are a number of mission specific constraints which the NEAR spacecraft must operate under. These include pointing, operational, and safety concerns as well as science directives and goals. The application of these constraints in the NEAR spacecraft environment at Eros is discussed, including some specific strategy implementations. RP Scheeres, DJ (reprint author), CALTECH,JET PROP LAB,NAVIGAT & FLIGHT MECH SECT,PASADENA,CA 91109, USA. NR 14 TC 27 Z9 28 U1 0 U2 3 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD OCT-DEC PY 1995 VL 43 IS 4 BP 427 EP 452 PG 26 WC Engineering, Aerospace SC Engineering GA UF540 UT WOS:A1995UF54000007 ER PT J AU Miller, JK Williams, BG Bollman, WE Davis, RP Helfrich, CE Scheeres, DJ Synnott, SP Wang, TC Yeomans, DK AF Miller, JK Williams, BG Bollman, WE Davis, RP Helfrich, CE Scheeres, DJ Synnott, SP Wang, TC Yeomans, DK TI Navigation analysis for Eros rendezvous and orbital phases SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB The navigation of the Near Earth Asteroid Rendezvous (NEAR) mission is described. This mission is the first of several low cost missions being planned to study the solar system. The primary purpose of this mission is to orbit the near-Earth asteroid 433 Eros and study it at close range. Elements of the NEAR Navigation System are described including navigation instrumentation, the spacecraft attitude control and propulsion system and the ground system consisting of tracking stations and software. Navigation accuracies are given for spacecraft orbit prediction and control. Key navigation parameters are noted, including the physical parameters that describe Eros such as mass, moments of inertia, and gravity harmonics. We also describe the orbit determination in support of science observations while in orbit about Eros. RP Miller, JK (reprint author), CALTECH,JET PROP LAB,NAVIGAT & FLIGHT MECH SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 32 Z9 32 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 OCT-DEC PY 1995 VL 43 IS 4 BP 453 EP 476 PG 24 WC Engineering, Aerospace SC Engineering GA UF540 UT WOS:A1995UF54000008 ER PT J AU THOMPSON, AM AF THOMPSON, AM TI MEASURING AND MODELING THE TROPOSPHERIC HYDROXYL RADICAL (OH) SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID OBSERVATORY PHOTOCHEMISTRY EXPERIMENT; LONG-PATH ABSORPTION; OZONE PRODUCTION; CHEMISTRY; INSTRUMENTATION; CONSTITUENTS; LASER; HO AB Efforts to measure the tropospheric hydroxyl radical concentration OH, the transient that plays a role in acid deposition formation and cleanses the atmosphere of many pollutants, began 20 years ago. In the past five years considerable progress has been made in local (in situ or point) measurement of OH (refer to other papers in this issue). New measurements put constraints on photochemical models that compute OH and other species. Reproducing observed OH with a model is more successful in some regimes than in others with calculated OH usually within 20% of measurements. This paper reviews OH photochemistry, comparisons of model-derived and measured OH in the continental boundary layer, and model calculation of OH in the marine boundary layer and free troposphere when high-frequency aircraft measurements of O-3 and related trace gases are assimilated into a photochemical model. Factors affecting model calculation of OH-nonlinearities, imprecisions in kinetics, differences among model formulation-are also discussed. RP THOMPSON, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 73 TC 19 Z9 20 U1 1 U2 3 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 OCT 1 PY 1995 VL 52 IS 19 BP 3315 EP 3327 DI 10.1175/1520-0469(1995)052<3315:MAMTTH>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RW724 UT WOS:A1995RW72400003 ER PT J AU LEARNER, RCM THORNE, AP WYNNEJONES, I BRAULT, JW ABRAMS, MC AF LEARNER, RCM THORNE, AP WYNNEJONES, I BRAULT, JW ABRAMS, MC TI PHASE CORRECTION OF EMISSION-LINE FOURIER-TRANSFORM SPECTRA SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID HOLLOW-CATHODE LAMP; FE-II WAVELENGTHS AB The process of phase correction for emission line spectra with high signal-to-noise ratios has remained a surprisingly complicated problem that can seriously affect the precision of data derived from Fourier transform emission spectra. Traditional methods, using a low resolution phase spectrum can produce spectra that show systematic errors in line positions and profiles. An improved phase correction strategy has been developed for and tested with infrared, visible, and ultraviolet emission line sources. A carefully apodized transform of relatively high resolution provides the phase data. A discriminator is used to restrict the data to those points that have a sufficiently high signal-to-noise ratio to provide a reliable phase estimate, and a smooth phase function is obtained by fitting a polynomial to these points. Some characteristics of real interferograms that complicate this simple picture are discussed. C1 NATL SOLAR OBSERV,TUCSON,AZ 85726. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP LEARNER, RCM (reprint author), UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,PRINCE CONSORT RD,LONDON SW7 2BZ,ENGLAND. NR 10 TC 26 Z9 26 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD OCT PY 1995 VL 12 IS 10 BP 2165 EP 2171 DI 10.1364/JOSAA.12.002165 PG 7 WC Optics SC Optics GA RW333 UT WOS:A1995RW33300010 ER PT J AU OLYNICK, DR HENLINE, WD CHAMBERS, LH CANDLER, GV AF OLYNICK, DR HENLINE, WD CHAMBERS, LH CANDLER, GV TI COMPARISON OF COUPLED RADIATIVE FLOW SOLUTIONS WITH PROJECT FIRE-II FLIGHT DATA SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA/ASME 6th Joint Thermophysics and Heat Transfer Conference CY JUN 20-23, 1994 CL COLORADO SPRINGS, CO SP Amer Inst Aeronaut & Astronaut, Amer Soc Mech Engineers AB A nonequilibrium, axisymmetric, Navier-Stokes flow solver with coupled radiation has been developed for use in the design of thermal protection systems for vehicles where radiation effects are important. The present method has been compared with an existing flow and radiation solver and with the Project Fire II experimental data. Good agreement has been obtained over the entire Fire II trajectory with the experimentally determined values of the stagnation radiation intensity in the 0.2-6.2 eV range and with the total stagnation heating. The effects of a number of flow models are examined to determine which combination of physical models produces the best agreement with the experimental data. These models include radiation coupling, multitemperature thermal models, and finite rate chemistry. Finally, the computational efficiency of the present model is evaluated. The radiation properties model developed for this study is shown to offer significant computational savings compared to existing codes. C1 NASA,LANGLEY RES CTR,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681. UNIV MINNESOTA,MINNEAPOLIS,MN 55455. RP OLYNICK, DR (reprint author), NASA,AMES RES CTR,REACTING FLOW ENVIRONM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 26 TC 37 Z9 37 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1995 VL 9 IS 4 BP 586 EP 594 DI 10.2514/3.712 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA TB802 UT WOS:A1995TB80200002 ER PT J AU TSUYUKI, G REEVE, R AF TSUYUKI, G REEVE, R TI GALILEO HIGH-GAIN ANTENNA DEPLOYMENT ANOMALY THERMAL-ANALYSIS SUPPORT SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA/ASME 6th Joint Thermophysics and Heat Transfer Conference CY JUN 20-23, 1994 CL COLORADO SPRINGS, CO SP Amer Inst Aeronaut & Astronaut, Amer Soc Mech Engineers AB In April of 1991, the Galileo spacecraft executed a sequence of commands to unfurl its umbrella-like high-gain antenna, but confirmation of deployment was not received. The primary theory was that a very high coefficient of friction existed between the midrib restraint pins and their receptacles along the antenna's central tower. Recovery actions included extreme antenna cold soaking, cyclic warming and cooling of the antenna, and pulsing the deployment motors to act as a mechanical hammer. An analytical model was extensively used to quantify the benefit of these actions. This model was not primarily intended to produce accurate temperatures in extremely cold environments. Initially, predicted antenna temperatures for cold soaking were different by as much as 40 degrees C. However, with additional night experience, this difference was reduced to within 20 degrees C. Good agreement (within 5 degrees C) with flight data was achieved for antenna warming and meter hammering. Although deployment was not achieved, the analytical model evolved without extensive revision into an accurate tool for predicting antenna temperatures. RP TSUYUKI, G (reprint author), CALTECH,JET PROP LAB,SPACECRAFT THERMAL ENGN & FLIGHT OPERAT GRP,THERMAL & PROP ENGN SECT,PASADENA,CA 91109, USA. NR 4 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 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1995 VL 9 IS 4 BP 771 EP 777 DI 10.2514/3.737 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA TB802 UT WOS:A1995TB80200027 ER PT J AU LIN, EI STULTZ, JW AF LIN, EI STULTZ, JW TI CASSINI MULTILAYER INSULATION BLANKET HIGH-TEMPERATURE EXPOSURE TESTS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The Saturn-bound Cassini spacecraft will be subjected to a high-temperature environment at 0.61 AU, Thermal vacuum tests demonstrated that the hybrid Kapton(R)-Mylar multilayer insulation layup can withstand an outer layer temperature of 250 degrees C without incurring any damage, and the all-Kapton layup can withstand 430 degrees C. The latter will be applied to locales of extremely high temperatures, while the former will be applied to more than 85% of the spacecraft's blanketed surfaces. A solar simulator provided a 2.7-sun exposure to the blanket samples; outer layer temperatures of 200 degrees C and 250 degrees C were observed for second surface aluminized Kapton and black Kapton, respectively, which are in line with predictions. The high-temperature exposure tests established that current blanket designs will survive the Cassini mission thermal environments with margins. RP LIN, EI (reprint author), CALTECH,JET PROP LAB,DIV MECH SYST ENGN & RES,TECH STAFF,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 5 Z9 5 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1995 VL 9 IS 4 BP 778 EP 783 DI 10.2514/3.738 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA TB802 UT WOS:A1995TB80200028 ER PT J AU Suder, KL Chima, RV Strazisar, AJ Roberts, WB AF Suder, KL Chima, RV Strazisar, AJ Roberts, WB TI The effect of adding roughness and thickness to a transonic axial compressor rotor SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS ID FLOWS AB The performance deterioration of a high-speed axial compressor rotor due to surface roughness and airfoil thickness variations is reported. A 0.025 mm (0.001 in.) thick rough coating with a surface finish of 2.54-3.18 rms mu m (100-125 mts mu in.) is applied to the pressure and suction surface of the rotor blades. Coating both surfaces increases the leading edge thickness by 10 percent at the hub and 20 percent at the tip. Application of this coating results in a loss in efficiency of 6 points and a 9 percent reduction in the pressure ratio across the rotor at an operating condition near the design point. To separate the effects of thickness and roughness, a smooth coating of equal thickness is also applied to the blade. The smooth coating surface finish is 0.254-0.508 rms mu m (10-20 rms mu in.), compared to the bare metal blade surface finish of 0.508 rms mu m (20 mts mu in.). The smooth coating results in approximately half of the performance deterioration found from the rough coating. Both coatings are then applied to different portions of the blade surface to determine which portions of the airfoil are most sensitive to thickness/roughness variations. Aerodynamic performance measurements are presented for a number of coating configurations at 60, 80, and 100 percent of design speed. The results indicate that thickness/roughness over the first 2 percent of blade chord accounts for virtually all of the observed performance degradation for the smooth coating, compared to about 70 percent of the observed performance degradation for the rough coating. The performance deterioration is investigated in more detail at design speed using laser anemometer measurements as well as predictions generated by a quasi-three-dimensional Navier-Stokes pow solver, which includes a surface roughness model. Measurements and analysis are performed on the baseline blade and the full-coverage smooth and rough coatings. The results indicate that adding roughness at the blade lending edge causes a thickening of the blade boundary layers. The interaction between the rotor passage shock and the thickened suction surface boundary layer then results in an increase in blockage, which reduces the diffusion level in the rear half of the blade passage, thus reducing the aerodynamic performance of the rotor. C1 FLOW APPLICAT RES & SERMATECH INT INC,FREMONT,CA 94539. RP Suder, KL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 22 TC 55 Z9 57 U1 1 U2 7 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 491 EP 505 PG 15 WC Engineering, Mechanical SC Engineering GA TT091 UT WOS:A1995TT09100001 ER PT J AU Gallus, HE Zeschky, J Hah, C AF Gallus, HE Zeschky, J Hah, C TI Endwall and unsteady flow phenomena in an axial turbine stage SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS ID ROTOR AB Detailed experimental and numerical studies have been performed in a subsonic, axial-flow turbine stage to investigate the secondary flow field, the aerodynamic loss generation, and the spanwise mixing under a stage environment. The experimental study includes measurements of the static pressure distribution on the rotor blade surface and the rotor exit flow field using three-dimensional hot-wire and pneumatic, probes. The rotor exit flow field was measured with an unsteady hot-wire probe, which has high temporal and spatial resolution. Both steady and unsteady numerical analyses were performed with a three-dimensional Navier-Stokes code for the multiple blade rows. Special attention was focused on how well the steady multiple-blade-row calculation predicts the rotor exit flow field and how much the blade interaction affects the radial distribution of flow properties at the stage exit. Detailed comparisons between the measurement and the steady calculation indicate that the steady multiple-blade-row calculation predicts the overall time-averaged pow field very well. However, the steady calculation does not predict the secondary flow at the stage exit accurately. The current study indicates that the passage vortex near the hub of the rotor is transported toward the midspan due to the blade interaction effects. Also, the structure of the secondary flow field at the exit of the rotor is significantly modified by the unsteady effects. The time-averaged secondary flow field and the radial distribution of the flow properties, which are used for the design of the following stage, can be predicted more accurately with the unsteady flow calculation. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Gallus, HE (reprint author), RHEIN WESTFAL TH AACHEN,W-5100 AACHEN,GERMANY. NR 27 TC 24 Z9 24 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 562 EP 570 PG 9 WC Engineering, Mechanical SC Engineering GA TT091 UT WOS:A1995TT09100008 ER PT J AU VanZante, DE Suder, KL Strazisar, AJ Okiishi, TH AF VanZante, DE Suder, KL Strazisar, AJ Okiishi, TH TI An improved aspirating probe for total-temperature and total-pressure measurements in compressor flows SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS AB The aspirating probe originally designed by Epstein and Ng at MIT was modified by replacing the two platinum-coated tungsten hot wires normally used with platinum-iridium alloy wires. The resulting improved unsteady total pressure and total temperature resolution of the modified probe is demonstrated. Flowfield measurements were made downstream of NASA Rotor 37 for a part-speed operating condition to test the performance of the probe. Time-resolved blade-to-blade total temperature and total pressure as calculated from the two platinum-iridium her-wire voltages are shown. The flowfield measurements are compared with independent measurements of total pressure with high response transducers and total temperature calculated from laser anemometer measurements. Limitations of a more often used unsteady temperature data reduction method, which involves only one aspirating probe hot-wire voltage and a high-response pressure measurement, are discussed. C1 IOWA STATE UNIV SCI & TECHNOL,DEPT MECH ENGN,AMES,IA 50011. RP VanZante, DE (reprint author), NASA,LEWIS RES CTR,INTERNAL FLUID MECH DIV,CLEVELAND,OH 44135, USA. NR 12 TC 9 Z9 9 U1 1 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 1995 VL 117 IS 4 BP 642 EP 649 PG 8 WC Engineering, Mechanical SC Engineering GA TT091 UT WOS:A1995TT09100020 ER PT J AU RAJ, SV AF RAJ, SV TI AN EVALUATION OF THE PROPERTIES OF CR3SI ALLOYED WITH MO SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE CR3SI ALLOY; CREEP; OXIDATION PROPERTIES ID MOLYBDENUM DISILICIDE; COMPOSITES; OXIDATION AB The properties of a Cr3Si alloy designed for the high temperature, high velocity gas dow conditions typical of the operating environment within an aircraft engine are discussed. The alloy composition was obtained by macroalloying Cr3Si with Mo to improve its high temperature oxidation resistance. Detailed cyclic, isothermal and low temperature ''pest'' oxidation studies conducted between 773 and 1673 K revealed that the alloy has excellent oxidation properties due to the formation of dual protective oxides scales of Cr2O3 at low temperatures and SiO2 at high temperatures. Preliminary burner rig tests conducted at 1473 K in a 0.3 mach combustion flame indicated that the alloy life is expected to exceed 100 cycles. The alloy exhibits a compressive brittle-to-ductile transition temperature of about 1500 K. The compression strengths vary between 650 MPa at 1500 K and 50 MPa at 1700 K. Preliminary results suggest that the compressive creep strength of the as-cast alloy is equal to or better than MoSi2-reinforced with either SiCp or SiCw, while that of the powder metallurgically-processed alloy is comparable only to the unreinforced MoSi2. The room temperature fracture toughness of the alloy was determined to be between 2.0 and 3.0 MPa m1/2. RP RAJ, SV (reprint author), NASA,LEWIS RES CTR,MS 49-1,CLEVELAND,OH 44135, USA. NR 34 TC 33 Z9 38 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 OCT PY 1995 VL 201 IS 1-2 BP 229 EP 241 DI 10.1016/0921-5093(95)09767-8 PG 13 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA TB242 UT WOS:A1995TB24200024 ER PT J AU OLSSON, P AF OLSSON, P TI SUMMATION BY PARTS, PROJECTIONS, AND STABILITY .2. SO MATHEMATICS OF COMPUTATION LA English DT Article AB In this paper we prove strict stability of high-order finite difference approximations of parabolic and symmetric hyperbolic systems of partial differential equations on bounded, curvilinear domains in two space dimensions. The boundary need not be smooth. We also show how to derive strict stability estimates for inhomogeneous boundary conditions. RP OLSSON, P (reprint author), NASA,AMES RES CTR,RIACS,MAIL STOP T20G-5,MOFFETT FIELD,CA 94035, USA. NR 2 TC 62 Z9 62 U1 0 U2 1 PU AMER MATHEMATICAL SOC PI PROVIDENCE PA 201 CHARLES ST, PROVIDENCE, RI 02940-2213 SN 0025-5718 J9 MATH COMPUT JI Math. Comput. PD OCT PY 1995 VL 64 IS 212 BP 1473 EP 1493 DI 10.2307/2153366 PG 21 WC Mathematics, Applied SC Mathematics GA RZ442 UT WOS:A1995RZ44200008 ER PT J AU HUA, F GRUGEL, RN AF HUA, F GRUGEL, RN TI MICROSTRUCTURAL DEVELOPMENT IN UNDERCOOLED LEAD-TIN EUTECTIC ALLOYS SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID METASTABLE PHASE-EQUILIBRIA; SI ALLOYS; GROWTH; SOLIDIFICATION; SELECTION; COLUMNAR; TRANSITION; DROPLETS; SYSTEM; HEAT AB A model was developed to predict microstructural development in lead-61.9 wt pet Sn (eutectic) alloys which were undercooled 5 to 25 K below their equilibrium freezing temperature prior to being preferentially nucleated. While the initial solidification velocity rapidly increases with increasing undercooling, the model predicts it to quickly decrease, prior to 10 pet solid formation, after which growth continues near the equilibrium temperature. Experimentally, and in accordance with the prediction, the eutectic emanated from the nucleation site with an initially fine spacing that increased with distance. However, in contrast to the model, the eutectic grew outward in a spokelike manner with each arm surrounded by a globular structure, this being attributed to the difficulty of lateral nucleation. Microstructural uniformity was further compromised by equiaxed eutectic grains which grew ahead of the advancing interface in the now only slightly undercooled liquid. Consequently, while containerless techniques may ensure sample purity and permit processing of high-temperature materials, development of a continuously fine and uniformly aligned microstructure cannot be assumed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812. RP HUA, F (reprint author), VANDERBILT UNIV,CTR MICROGRAV RES & APPLICAT,NASHVILLE,TN 37235, USA. NR 30 TC 3 Z9 3 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD OCT PY 1995 VL 26 IS 10 BP 2699 EP 2706 DI 10.1007/BF02669426 PG 8 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA RY683 UT WOS:A1995RY68300021 ER PT J AU DRAPER, SL AIKIN, BJM ELDRIDGE, JI AF DRAPER, SL AIKIN, BJM ELDRIDGE, JI TI TENSILE BEHAVIOR OF AL2O3/FEAL+B AND AL2O3/FECRALY COMPOSITES SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID INTERFACIAL BONDING STRENGTH; FIBER AB The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al2O3/FeAl + B and moderate to high for Al2O3/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al2O3 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. RP DRAPER, SL (reprint author), NASA,LEWIS RES CTR,DIV MAT,CLEVELAND,OH 44135, USA. NR 18 TC 7 Z9 7 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD OCT PY 1995 VL 26 IS 10 BP 2719 EP 2731 DI 10.1007/BF02669428 PG 13 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA RY683 UT WOS:A1995RY68300023 ER PT J AU LEDVINA, DV PFAENDTNER, J AF LEDVINA, DV PFAENDTNER, J TI INCLUSION OF SPECIAL SENSOR MICROWAVE/IMAGER (SSM/I) TOTAL PRECIPITABLE WATER ESTIMATES INTO THE GEOS-1 DATA ASSIMILATION SYSTEM SO MONTHLY WEATHER REVIEW LA English DT Article ID MODELS; CLOUD AB At this time, most current data assimilation systems use dewpoint depression data, converted to an appropriate moisture variable (relative humidity or mixing ratio), provided by rawinsondes as the lone source of moisture information. Because of the poor spatial and temporal characteristics of this data, additional moisture data are necessary to better resolve the global moisture field. This study investigates the impact of using the Special Sensor Microwave/Imager (SSM/I) total precipitable water (TPW) estimates as an additional source of moisture information. One forecast acid four data assimilation experiments were performed to determine the impact of assimilating SSM/I TPW estimates into the NASA/Goddard Earth Observing System (version 1) Data Assimilation System (GEOS-1 DAS). It is shown that assimilation of SSM/I TPW estimates improves the precipitation pattern in the Tropics. In addition, a known dry bias in the GEOS-1 DAS was reduced by over 50% and observation minus first guess (O - F) error variance is reduced by nearly 50% after only 3 days of assimilation. Improvements were also noted in monthly and 6-h-averaged precipitation patterns when compared to other independent estimates. C1 GEN SCI CORP,LAUREL,MD. RP LEDVINA, DV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. NR 20 TC 20 Z9 22 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD OCT PY 1995 VL 123 IS 10 BP 3003 EP 3015 DI 10.1175/1520-0493(1995)123<3003:IOSSMT>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RU743 UT WOS:A1995RU74300006 ER PT J AU LEE, S LEE, JM AF LEE, S LEE, JM TI NONLINEAR-SYSTEM CONTROL-BASED ON MULTIRESOLUTION RADIAL-BASIS COMPETITIVE AND COOPERATIVE NETWORKS SO NEUROCOMPUTING LA English DT Article DE RADIAL-BASIS NETWORKS; NONLINEAR SYSTEM CONTROL; COMPETITIVE AND COOPERATIVE NETWORKS; CLUSTERING; MANY-TO-MANY MAPPING ID FEEDFORWARD NETWORKS; NEURAL-NETWORK; APPROXIMATION AB Most mapping neural networks to date can learn only one-to-one and many-to-one mapping. However, the inverse control of certain nonlinear systems requires to handle one-to-many inverse mapping, which most conventional mapping neural networks are unable to cope with. This paper presents a novel Multi-resolution Radial-basis Competitive and Cooperative Network (MRCCN) capable of dealing with one-to-many inverse mapping for control. MRCCN self-organizes a collection of local clusters of various locations, shapes and sizes to represent an arbitrary many-to-many mapping under uniform mapping accuracy. MRCCN is able to retrieve multiple outputs based on the cooperative decision of local clusters relevant to the given input. The highlight of this paper is the demonstration that MRCCN is able to control those nonlinear systems that can not be handled by conventional mapping networks due to the one-to-many mapping involved. Simulation results are shown. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. KANGWEON NATL UNIV,DEPT CONTROL & INSTRUMENTAT ENG,CHUNCHON 200701,SOUTH KOREA. RP LEE, S (reprint author), UNIV SO CALIF,DEPT EE SYST & CS,LOS ANGELES,CA 90089, USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0925-2312 J9 NEUROCOMPUTING JI Neurocomputing PD OCT PY 1995 VL 9 IS 2 BP 187 EP 206 DI 10.1016/0925-2312(95)00034-4 PG 20 WC Computer Science, Artificial Intelligence SC Computer Science GA TC902 UT WOS:A1995TC90200006 ER PT J AU PALM, DE SHUE, SG KEIL, LC BALABAN, CD SEVERS, WB AF PALM, DE SHUE, SG KEIL, LC BALABAN, CD SEVERS, WB TI EFFECTS OF ANGIOTENSIN, VASOPRESSIN AND ATRIAL-NATRIURETIC-PEPTIDE ON INTRAOCULAR-PRESSURE IN ANESTHETIZED RATS SO NEUROPEPTIDES LA English DT Article ID RABBIT ANTERIOR UVEA; CEREBROVENTRICULAR INFUSIONS; INTRACRANIAL HYPERTENSION; CHOROID-PLEXUS; CONSCIOUS RATS; AQUEOUS-HUMOR; BINDING-SITES; RETINA; TISSUES; FLUID AB The effects of atrial natriuretic peptide (ANP), vasopressin (AVP) and angiotensin (ANG) on blood and intraocular pressures of pentobarbital anesthetized rats were evaluated following intravenous, intracerebroventricular or anterior chamber routes of administration. Central injections did not affect intraocular pressure. Equipressor intravenous infusions of ANG raised, whereas AVP decreased, intraocular pressure. Direct infusions of a balanced salt solution (0.175 mu l/min) raised intraocular pressure between 30 and 60 min. Adding ANG or ANP slightly reduced this solvent effect but AVP was markedly inhibitory. An AVP-V1 receptor antagonist reversed the blunting of the solvent-induced rise by the peptide, indicating receptor specificity. Acetazolamide pretreatment lowered intraocular pressure, but the solvent-induced rise in intraocular pressure and inhibition by AVP still occurred without altering the temporal pattern. Thus, these effects appear unrelated to aqueous humor synthesis rate. The data support the possibility of intraocular pressure regulation by peptides acting from the blood and aqueous humor. C1 PENN STATE UNIV,HERSHEY MED CTR,COLL MED,DEPT PHARMACOL,HERSHEY,PA 17033. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. EYE & EAR INST PITTSBURGH,DEPT OTOLARYNGOL,PITTSBURGH,PA 15213. NR 41 TC 12 Z9 13 U1 1 U2 1 PU CHURCHILL LIVINGSTONE PI EDINBURGH PA JOURNAL PRODUCTION DEPT, ROBERT STEVENSON HOUSE, 1-3 BAXTERS PLACE, LEITH WALK, EDINBURGH, MIDLOTHIAN, SCOTLAND EH1 3AF SN 0143-4179 J9 NEUROPEPTIDES JI Neuropeptides PD OCT PY 1995 VL 29 IS 4 BP 193 EP 203 DI 10.1016/0143-4179(95)90061-6 PG 11 WC Endocrinology & Metabolism; Neurosciences SC Endocrinology & Metabolism; Neurosciences & Neurology GA TC239 UT WOS:A1995TC23900002 PM 8584137 ER PT J AU BOGART, D AF BOGART, D TI RADIAL RESONANCE CAPTURES IN U-238 METAL RODS AND SPATIAL RESONANCE PRODUCTION OF PU-239 IN URANIUM-OXIDE FUELS SO NUCLEAR TECHNOLOGY LA English DT Article AB Precise calculation of radial distributions of resonance region capture in U-238 metal rods and for partially enriched uranium-oxide fuels is important for current and proposed water-moderated power reactors. Advanced core designs for pressurized and boiling water reactors have considered resonance region in-core generation of Pu-239 as a means of extending core operating cycles between refuelings. The calculations of detailed spatial resonance captures are beyond the scope of multigroup codes used for practical reactor core design because of the broad resonance energy groups required. Group average resonance capture cross-section parameters employed may conserve total neutron captures, but the spatial detail is washed out. A simplified method is presented that enables direct calculation of resonance region spatial captures in fuel moderator lattices. The validity of the method is confirmed by comparison with published experimental measurements for epicadmium capture with radial distance from the moderator-fuel interface for metal uranium rods from 0.8 to 5.0 cm in diameter. A method is illustrated for spatial resonance capture in partially enriched uranium-oxide fuel rods, and the spatial complexity of Pu-239 production during conversion of U-238 in the resonance region is discussed. Although the products of the conversion chain can be precisely defined geometrically with operating time, their spatial concentrations cannot be calculated with the accuracy required to determine net production of Pu-239. RP BOGART, D (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU AMER NUCLEAR SOCIETY PI LA GRANGE PK PA 555 N KENSINGTON AVENUE, LA GRANGE PK, IL 60525 SN 0029-5450 J9 NUCL TECHNOL JI Nucl. Technol. PD OCT PY 1995 VL 112 IS 1 BP 9 EP 20 PG 12 WC Nuclear Science & Technology SC Nuclear Science & Technology GA RY688 UT WOS:A1995RY68800002 ER PT J AU MACKE, A MISHCHENKO, MI MUINONEN, K CARLSON, BE AF MACKE, A MISHCHENKO, MI MUINONEN, K CARLSON, BE TI SCATTERING OF LIGHT BY LARGE NONSPHERICAL PARTICLES - APPROXIMATION VERSUS T-MATRIX METHOD SO OPTICS LETTERS LA English DT Article ID AXIALLY-SYMMETRICAL PARTICLES; CRYSTALS; ICE AB We report, for the first time to our knowledge, comparisons of light-scattering computations for large, randomly oriented, moderately absorbing spheroids based on the geometric-optics approximation and the exact T-matrix method. We show that in most cases the geometric-optics approximation is (much) more accurate for spheroids than for surface-equivalent spheres and can be used in phase function computations (but not in polarization computations) for nonspherical particles with size parameters as small as 60. Differences in the single-scattering albedo between geometric-optics and T-matrix results are surprisingly small, even for small size parameters. (C) 1995 Optical Society of America C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. HELSINKI UNIV OBSERV,SF-00014 HELSINKI,FINLAND. NASA,SCI SYST & APPLICAT INC,NEW YORK,NY 10025. RP MACKE, A (reprint author), COLUMBIA UNIV,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Carlson, Barbara/D-8319-2012; Mishchenko, Michael/D-4426-2012 NR 15 TC 67 Z9 67 U1 2 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD OCT 1 PY 1995 VL 20 IS 19 BP 1934 EP 1936 DI 10.1364/OL.20.001934 PG 3 WC Optics SC Optics GA RW114 UT WOS:A1995RW11400002 PM 19862208 ER PT J AU LEPRIEUR, C CARRERE, V GU, XF AF LEPRIEUR, C CARRERE, V GU, XF TI ATMOSPHERIC CORRECTIONS AND GROUND REFLECTANCE RECOVERY FOR AIRBORNE VISIBLE INFRARED IMAGING SPECTROMETER (AVIRIS) DATA - MAC-EUROPE-91 SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID WATER-VAPOR AB It is now well established that a valid atmospheric correction procedure is required for a physically based analysis of measured high spectral resolution remote sensing data. While the theory of radiative transfer in the atmosphere is now well understood, remaining difficulties are due to the inaccurate knowledge of the state of the atmosphere at the time of acquisition. We have taken the opportunity of the MAC Europe to compare two atmospheric correction procedures applied to Airborne Visible/infrared Imaging Spectrometer (AVIRIS) data. Atmospheric condition estimates were acquired concurrently with the overflights. These in situ measurements were used to constrain the LOWTRAN-7 and 5S radiative transfer codes to recover the spectral reflectance at ground level in the 400- to 2500-nm region. The influence of various input atmospheric parameters such as aerosols and wafer vapor amounts on reflectance recovery is evaluated. The accuracy of the radiative transfer code based recovery is discussed using ground reflectance measurements acquired at the Camargue site over sunflower, alfalfa, and wheat crops during the AVIRIS flights. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. INRA,F-84143 MONTFAVET,FRANCE. RP LEPRIEUR, C (reprint author), CTR NATL ETUD SPATIALES,CNRS,UMR,LERTS,18 AVE EDOUARD BELIN,F-31055 TOULOUSE,FRANCE. NR 23 TC 7 Z9 9 U1 1 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD OCT PY 1995 VL 61 IS 10 BP 1233 EP 1238 PG 6 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA RX962 UT WOS:A1995RX96200005 ER PT J AU Greco, M Rolli, S AF Greco, M Rolli, S TI Light meson production at the Fermilab tevatron to next-to-leading order SO PHYSICAL REVIEW D LA English DT Article ID PARTON-PARTON SCATTERING; = 1.8 TEV; CROSS-SECTION; QCD CORRECTIONS; COLLISIONS; DISTRIBUTIONS; SIMULATION; PHOTON AB Inclusive production of light mesons (pi(o), eta, pi(+/-), K-+/-) at the Fermilab Tevatron is considered in QCD to next-to-leading order in the formalism of fragmentation functions. We present various distributions of phenomenological interest, along with a new set of K meson fragmentation functions. The fragmentation properties of jets in charged and neutral pions are also considered. C1 IST NAZL FIS NUCL,LAB NAZL FRASCATI,I-00044 FRASCATI,ITALY. UNIV PAVIA,DIPARTIMENTO FIS NUCL & TEOR,I-27100 PAVIA,ITALY. IST NAZL FIS NUCL,SEZ PAVIA,I-27100 PAVIA,ITALY. NASA,FERMILAB ASTROPHYS CTR,FERMILAB,BATAVIA,IL 60510. RP Greco, M (reprint author), UNIV AQUILA,DIPARTIMENTO FIS,LAQUILA,ITALY. NR 24 TC 17 Z9 17 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 1 PY 1995 VL 52 IS 7 BP 3853 EP 3861 DI 10.1103/PhysRevD.52.3853 PG 9 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA TL182 UT WOS:A1995TL18200014 ER PT J AU CORNELIUS, D RAMAN, G AF CORNELIUS, D RAMAN, G TI DISTURBANCE GROWTH TRIGGERED BY STEADY HEATING OF A JETS NOZZLE EXIT BOUNDARY-LAYER SO PHYSICS OF FLUIDS LA English DT Letter ID ABSOLUTE INSTABILITY; HEATED JETS AB Experiments were conducted to investigate how heating only the nozzle exit boundary layer of an axisymmetric jet, with an unheated potential core, affects disturbance growth in the initial shear layer. The exit boundary layer had a minimum density ratio of 0.74, was laminar, and had a constant momentum thickness (theta) for all levels of nozzle heating used in this study. The fluctuating velocity (u') and temperature (t') in the exit boundary layer increased monotonically with increasing nozzle temperature. Low-amplitude acoustic excitation produced a more rapid growth of coherent velocity fluctuations for the heated case than for the unheated. (C) 1995 American Institute of Physics. C1 NASA,LEWIS RES CTR GRP,NYMA INC,EXPTL FLUID DYNAM SECT,BROOKPARK,OH 44142. RP CORNELIUS, D (reprint author), STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305, USA. NR 8 TC 1 Z9 1 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD OCT PY 1995 VL 7 IS 10 BP 2304 EP 2306 DI 10.1063/1.868743 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA RW579 UT WOS:A1995RW57900002 ER PT J AU SALAMA, F JOBLIN, C ALLAMANDOLA, LJ AF SALAMA, F JOBLIN, C ALLAMANDOLA, LJ TI NEUTRAL AND IONIZED PAHS - CONTRIBUTION TO THE INTERSTELLAR EXTINCTION SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Conference on Dust, Molecules and Background - From Laboratory to Space CY 1994 CL CAPRI, ITALY SP Italian Soc Phys, Italian Astron Soc ID POLYCYCLIC AROMATIC-HYDROCARBONS; BANDS; ULTRAVIOLET; MOLECULES; SPECTRA; CATION; C10H8+; CURVE; ION AB A detailed study of the UV-to-near-IR absorption spectra of neutral and ionized polycyclic aromatic hydrocarbons (PAHs) is reported. The experimental results obtained using matrix isolation spectroscopy combined with the general spectroscopic properties of PAHs derived from theoretical modeling are compared with astronomical observations. From this study, it is concluded that: (i) small neutral PAHs (less than 25 carbon atoms) absorb only in the UV and cannot contribute to the known diffuse interstellar bands, although they may contribute to the extinction curve. A search for their spectral signatures should provide a test to the PAH model and should allow us to set significant limits for the abundances of specific PAHs; (ii) small ionized PAHs (less than 25 carbon atoms) absorb in the visible and near-IR close to the position of well-known diffuse interstellar bands. Based on these promising results it is argued that PAH ions constitute good candidates to explain the diffuse interstellar bands. An assessment of the PAH/diffuse interstellar band proposal is made and predictions for new diffuse interstellar bands to be searched for are presented. RP SALAMA, F (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Salama, Farid/A-8787-2009 OI Salama, Farid/0000-0002-6064-4401 NR 29 TC 33 Z9 33 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT-NOV PY 1995 VL 43 IS 10-11 BP 1165 EP 1173 DI 10.1016/0032-0633(95)00051-6 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TJ949 UT WOS:A1995TJ94900003 ER PT J AU JOBLIN, C TIELENS, AGGM ALLAMANDOLA, LJ LEGER, A DHENDECOURT, L GEBALLE, TR BOISSEL, P AF JOBLIN, C TIELENS, AGGM ALLAMANDOLA, LJ LEGER, A DHENDECOURT, L GEBALLE, TR BOISSEL, P TI PAHS AS THE CARRIERS OF THE 3.3 AND 3.4 MU-M EMISSION BANDS SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Conference on Dust, Molecules and Background - From Laboratory to Space CY 1994 CL CAPRI, ITALY SP Italian Soc Phys, Italian Astron Soc ID POLYCYCLIC AROMATIC-HYDROCARBONS; CARBONACEOUS COMPOSITE QCC; INFRARED-SPECTRUM; MICRON EMISSION; IR EMISSION; MOLECULES; IDENTIFICATION; SPECTROSCOPY; FEATURES; PHYSICS AB Using recent laboratory measurements on gas-phase polycyclic aromatic hydrocarbons (PAHs) as well as new astronomical observations, we discuss the origin of the 3.3 mu m emission band and of its major satellite band at 3.40 mu m. These studies show that the position, width and profile of the 3.3 mu m band are consistent with the carriers being free PAH molecules. The peak position and width of this band are sensitive to the emission temperature (i.e. absorbed UV photon). The observed peak position and width correspond to an ''average'' emission temperature of 1200 K which implies a size of 24 and 48 carbon atoms for a 6 and 10 eV absorbed photon, respectively. The first overtone of the 3.3 mu m band has been detected at 1.68 mu m in the planetary nebula IRAS 21282 + 5050. These observations imply that the hot band is expected at 3.43 mu m rather than at 3.40 mu m. The main 3.40 mu m band is attributed to the CH stretching mode from methyl side groups attached to the periphery of PAHs. This assignment is supported by the spectral agreement with laboratory spectra and by the behavior of the 3.40 mu m band upon UV radiation field in astronomical environments. C1 UNIV PARIS 11,INST ASTROPHYS SPATIALE,CNRS LAB,F-91405 ORSAY,FRANCE. JOINT ASTRON CTR,HILO,HI 96720. UNIV PARIS 11,PHOTOPHYS MOLEC LAB,CNRS LAB,F-91405 ORSAY,FRANCE. RP JOBLIN, C (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 25 TC 10 Z9 10 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT-NOV PY 1995 VL 43 IS 10-11 BP 1189 EP 1194 DI 10.1016/0032-0633(95)00022-W PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TJ949 UT WOS:A1995TJ94900006 ER PT J AU ROUSH, TL AF ROUSH, TL TI OPTICAL-CONSTANTS OF AMORPHOUS-CARBON IN THE MID-IR (2.5-25 MU-M, 4000-400 CM(-1)) SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Conference on Dust, Molecules and Background - From Laboratory to Space CY 1994 CL CAPRI, ITALY SP Italian Soc Phys, Italian Astron Soc ID POLYCYCLIC AROMATIC-HYDROCARBONS; INFRARED-EMISSION BANDS; ULTRAVIOLET EXTINCTION MEASUREMENTS; GRAINS; FEATURES; SPECTRA; DUST; MICRONS; NEBULAE; ROCKS AB Laboratory measurement of the Fresnel reflectance are used to derive the real and imaginary indices of refraction of amorphous carbon in the 2.5-25 mu m region. Comparison to previously reported optical constants, derived from extinction measurements at these wavelengths, show both similarities and differences. The differences are likely due to the different samples studied. wavelength-dependent calculated extinction coefficients (Q(ext)/a) from these values derived here are intermediate in value to previously reported Q(ext)/a other amorphous carbon samples. The overall spectral shape exhibits a lambda(-a) behavior with alpha = 1.05 +/- 0.05. However, more spectral structure is seem in the 18-25 mu m region than has been reported previously. RP ROUSH, TL (reprint author), NASA,AMES RES CTR,SAN FRANCISCO STATE UNIV,DEPT GEOSCI,MAILSTOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 43 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT-NOV PY 1995 VL 43 IS 10-11 BP 1297 EP 1301 DI 10.1016/0032-0633(95)00008-S PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TJ949 UT WOS:A1995TJ94900023 ER PT J AU PENDLETON, YJ AF PENDLETON, YJ TI LABORATORY COMPARISONS OF ORGANIC MATERIALS TO INTERSTELLAR DUST AND THE MURCHISON METEORITE SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Conference on Dust, Molecules and Background - From Laboratory to Space CY 1994 CL CAPRI, ITALY SP Italian Soc Phys, Italian Astron Soc ID CARBONACEOUS CHONDRITES; ABSORPTION FEATURE; AMORPHOUS-CARBON; SPECTROSCOPY; BANDS AB Spectra of objects which lie along several lines of sight through the diffuse interstellar medium (DISM) reveal an absorption feature near 3.4 mu m, which has been attributed to saturated aliphatic hydrocarbons on interstellar grains. The similarity of the absorption bands near 3.4 mu m (2950 cm(-1)) along different lines of sight indicates that the carrier of this band lies in the diffuse dust. Several materials have been proposed as ''fits'' to the 3.4 mu m feature over the years. A comparision of these identifications is presented. These comparisons illustrate the need for high resolution, high signal-to-noise observational data as a means of distinguishing between laboratory organics as matches to the interstellar material. Although amy material containing hydrocarbons will produce features in the 3.4 mu m region, the proposed ''matches'' to the DISM do differ in detail. These differences may help in the analyses of the chemical composition and physical processes which led to the production of the DISM organics, although ISO Observation through the 5-8 mu m spectra region are essential for a definitive identification. A remarkable similarity between the spectrum of the diffuse and an organic extract form the Murchison meteorite suggests that some of the interstellar organic material may be preserved in primitive solar system bodies. The 3.4 mu m absorption feature (in the rest frame) has recently been detected in external galaxies, indicating the widespread availability of organic material for incorporation into planetary systems. RP PENDLETON, YJ (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 34 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT-NOV PY 1995 VL 43 IS 10-11 BP 1359 EP 1364 DI 10.1016/0032-0633(95)00024-Y PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TJ949 UT WOS:A1995TJ94900032 PM 11540309 ER PT J AU BERSANELLI, M BENSADOUN, M DANESE, L DEAMICI, G KOGUT, A LEVIN, S LIMON, M MAINO, D SMOOT, GF WITEBSKY, C AF BERSANELLI, M BENSADOUN, M DANESE, L DEAMICI, G KOGUT, A LEVIN, S LIMON, M MAINO, D SMOOT, GF WITEBSKY, C TI MEASUREMENTS OF THE ATMOSPHERIC EMISSION AND VARIATIONS IN THE 1-90 GHZ RANGE SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Conference on Dust, Molecules and Background - From Laboratory to Space CY 1994 CL CAPRI, ITALY SP Italian Soc Phys, Italian Astron Soc ID COSMIC BACKGROUND-RADIATION; 12 CENTIMETER WAVELENGTH; SCALE MEASUREMENT; SOUTH-POLE; 7.5 GHZ; TEMPERATURE; FREQUENCY AB Ground-based measurements of the Cosmic Background Radiation (CBR) are hampered by emission from atmospheric O-2 and water molecules. We performed multifrequency measurements of the atmospheric emission in the 1-90 GHz spectral range from two high-altitude sites (White Mountain, California, and South Pole, Antarctica). A power spectrum analysis of our data shows variations of the atmospheric antenna temperature which exceed, on time scales of a few hours or more, those expected from radiometer noise and changes in water column density. When combined with real-time measurements of the local profiles of atmospheric pressure, temperature and humidity, our results indicate variations of order 10% of the O-2 emission (both resonant and non-resonant components) on time scales of hours to days, driven by the evolution of the atmospheric pressure profile. These oxygen emission fluctuations appear significantly larger than previously expected, and may affect ground-based CBR experiments. C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. DIPARTIMENTO ASTRON,I-35122 PADUA,ITALY. NASA,GSFC,HUGHES STX,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP BERSANELLI, M (reprint author), CNR,IST FIS COSM,VIA BASSINI 15,I-20133 MILAN,ITALY. RI Kogut, Alan/D-6293-2012 NR 34 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 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT-NOV PY 1995 VL 43 IS 10-11 BP 1467 EP 1472 DI 10.1016/0032-0633(95)00007-R PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TJ949 UT WOS:A1995TJ94900046 ER PT J AU HILAIRE, E PAULSEN, AQ BROWN, CS GUIKEMA, JA AF HILAIRE, E PAULSEN, AQ BROWN, CS GUIKEMA, JA TI CORTICAL MICROTUBULES IN SWEET CLOVER COLUMELLA CELLS DEVELOPED IN MICROGRAVITY SO PLANT AND CELL PHYSIOLOGY LA English DT Note DE COLUMELLA CELLS; CYTOSKELETON; MELILOTUS ALBA L; MICROGRAVITY; MICROTUBULE; ROOT ID ROOTS; GRAVITY; ULTRASTRUCTURE; GRAVITROPISM; ARABIDOPSIS; STATOCYTES AB Electron micrographs of columella cells from sweet clover seedlings grown and fixed in microgravity revealed longitudinal and cross sectioned cortical microtubules. This is the first report demonstrating the presence and stability of this network in plants in microgravity. C1 DYNAMAC CORP, PLANT SPACE BIOL LAB, KENNEDY SPACE CTR, FL 32899 USA. RP HILAIRE, E (reprint author), KANSAS STATE UNIV AGR & APPL SCI, NASA, SPECIALIZED CTR RES & TRAINING GRAVITAT BIOL, DIV BIOL, MANHATTAN, KS 66506 USA. RI Guikema, James/C-1313-2010 NR 30 TC 4 Z9 4 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0032-0781 EI 1471-9053 J9 PLANT CELL PHYSIOL JI Plant Cell Physiol. PD OCT PY 1995 VL 36 IS 7 BP 1387 EP 1392 PG 6 WC Plant Sciences; Cell Biology SC Plant Sciences; Cell Biology GA TC923 UT WOS:A1995TC92300030 PM 11536715 ER PT J AU FAWCETT, SC ENGELHAUPT, D AF FAWCETT, SC ENGELHAUPT, D TI DEVELOPMENT OF WOLTER-I X-RAY OPTICS BY DIAMOND TURNING AND ELECTROCHEMICAL REPLICATION SO PRECISION ENGINEERING-JOURNAL OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING LA English DT Article DE X-RAY; DIAMOND TURNING; REPLICATED OPTICS AB Demonstration x-ray optics have been produced by diamond turning and replication techniques that could revolutionize the fabrication of advanced mirror assemblies. The prototype optics were developed as part of the Advanced X-ray Astrophysics Facility-Spectrographic program (AXAF-S). The initial part of the project was aimed at developing and testing the replication technique so that it could potentially be used for the production of the entire mirror array. This assembly will ultimately be comprised of up to 50 nested mirror shells. The mirrors are produced by electroforming a thin shell optic with a conical mandrel. The mandrel is diamond-termed electroless nickel over an aluminum substrate. The initial goal was to produce a surface finish on the replicated mirror shell of less than 10 Angstrom rms (measured with a WYKO 30 at 20X). The electroformed mirror shell is made from pure nickel deposited in a state of minimum stress. A cryogenic separation technique is used to remove the finished mirror from the mandrel. The replication technology for the mirror components has the potential to revolutionize the fabrication of precision components. The extremely high precision required of x-ray optics may lead to advances in manufacturing techniques that could be utilized in the fabrication of other precision components. The key procedures of the fabrication process are presented with the appropriate testing results. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,OPT FABRICAT BRANCH,EB53,HUNTSVILLE,AL 35812. NR 0 TC 12 Z9 12 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0141-6359 J9 PRECIS ENG JI Precis. Eng.-J. Am. Soc. Precis. Eng. PD OCT PY 1995 VL 17 IS 4 BP 290 EP 297 DI 10.1016/0141-6359(95)00018-9 PG 8 WC Engineering, Multidisciplinary; Engineering, Manufacturing; Nanoscience & Nanotechnology; Instruments & Instrumentation SC Engineering; Science & Technology - Other Topics; Instruments & Instrumentation GA TA199 UT WOS:A1995TA19900007 ER PT J AU FEIBELMAN, WA KALER, JB BOND, HE GRAUER, AD AF FEIBELMAN, WA KALER, JB BOND, HE GRAUER, AD TI VARIABILITY OF IUE SPECTRA OF THE PULSATING NUCLEUS OF THE PLANETARY-NEBULA K-1-16 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID CENTRAL STAR; HOT AB We report on some subtle changes which were detected in old IUE low-dispersion spectra of the pulsating central star of the planetary nebula K 1-16. Although most of the data were taken more than ten years ago, the improved data reduction techniques and more accurate line identifications that have become available only recently permit measurement of variability in absorption lines. These changes are suspected of being caused by variations of O VI and high-excitation C IV transitions that on low-dispersion spectra are unresolved from interstellar Si Il and may also mimic He II lambda 1640 absorption. We compare features in low- and high-resolution spectra of K 1-16 with those found in other PG 1159- and O VI-type central stars, C1 UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV ARKANSAS,DEPT PHYS & ASTRON,LITTLE ROCK,AR 72204. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 21 TC 4 Z9 4 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 1995 VL 107 IS 716 BP 914 EP 926 DI 10.1086/133639 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY845 UT WOS:A1995RY84500002 ER PT J AU BAKER, MB CHRISTIAN, HJ LATHAM, J AF BAKER, MB CHRISTIAN, HJ LATHAM, J TI A COMPUTATIONAL STUDY OF THE RELATIONSHIPS LINKING LIGHTNING FREQUENCY AND OTHER THUNDERCLOUD PARAMETERS SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE CLOUD ELECTRIFICATION; LIGHTNING; THUNDERSTORMS ID SQUALL LINE; ELECTRIFICATION; PRECIPITATION; THUNDERSTORMS; GROWTH; RATES AB In an effort to optimize the value of global-scale measurements obtained with the NASA/MSFC satellite-borne Lightning Imaging System (LIS), a simple computational model of thundercloud electrification has been developed, from which it is possible to derive crude relationships between lightning frequency f (which LIS will measure) and cloud parameters such as radar reflectivity Z, precipitation rate P, updraught speed w, cloud radius R, ice-crystal concentration N-i and graupel-pellet concentration N-g. Electric field-growth is assumed to occur via the non-inductive charging mechanism, for both Fletcher and Hallett-Mossop types of glaciation mechanisms. A simple criterion is used to distinguish between cloud-to-ground and intracloud lightning discharges. f is found to be especially sensitive to w in situations where, as updraught speed increases, the temperature at balance level, T-bal, of the upper boundary of the charging zone falls. In these circumstances Ni and the sizes of the ice hydrometeors are significantly increased, with a corresponding enhancement of the effectiveness of charge transfer. Over a wide range of conditions, f is found to be roughly proportional to the first power of the parameters R, N-i, N-g and Z and (in some circumstances) to at least the sixth power of w. The relationship between f and P depends critically on whether or not w and T-bal are strongly linked. Hallett-Mossop glaciation is capable of producing inverted-polarity lightning from thunderclouds; Fletcher glaciation is not. C1 UNIV WASHINGTON,WASHINGTON,DC. NASA,HUNTSVILLE,AL. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. NR 26 TC 60 Z9 69 U1 0 U2 4 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING, BERKS, ENGLAND RG1 7LJ SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD OCT PY 1995 VL 121 IS 527 BP 1525 EP 1548 DI 10.1002/qj.49712152703 PN A PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TA293 UT WOS:A1995TA29300002 ER PT J AU Bates, JR Li, Y Brandt, A McCormick, SF Ruge, J AF Bates, JR Li, Y Brandt, A McCormick, SF Ruge, J TI A global shallow-water numerical model based on the semi-Lagrangian advection of potential vorticity SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article DE numerical methods; potential vorticity; semi-Lagrangian models ID FINITE-DIFFERENCE SCHEME; INTEGRATION SCHEME; EQUATION MODEL; IMPLICIT; INITIALIZATION; APPROXIMATIONS; ATMOSPHERE; COORDINATE; SPHERE; SIGMA AB A global shallow-water primitive equation model based on the semi-Lagrangian advection of potential vorticity is presented. A modification of the basic advection scheme needed to stabilize Rossby waves is introduced. The divergence and continuity equations are the remaining governing equations. A two-time-level semi-Lagrangian semi-implicit numerical scheme that avoids forward extrapolation of non-linear terms is used. This leads to a set of non-linear implicit equations to be solved at each time-step. The wind field is expressed in terms of a streamfunction and velocity potential, and a spatial discretization based on second-order finite differences on an unstaggered grid is used. The implicit equations are solved simultaneously using a non-linear multigrid method. The model is integrated for periods of up to 50 days at various resolutions, using a variety of initial conditions including real data. Comparisons with an existing semi-Lagrangian finite-difference shallow-water model and an Eulerian spectral shallow-water model are carried out. The new model is found to integrate stably and efficiently, and to require no noise suppressors other than the inherent diffusivity associated with the interpolations. The model gives results that are, in general, very close to those of the comparison models, but a case of highly non-linear flow (where the true solution is unknown) is presented in which it gives results that stand notably apart. C1 NASA,GODDARD LAB ATMOSPHERES,WASHINGTON,DC. WEIZMANN INST SCI,IL-76100 REHOVOT,ISRAEL. UNIV COLORADO,BOULDER,CO 80309. NR 47 TC 27 Z9 27 U1 0 U2 1 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING, BERKS, ENGLAND RG1 7LJ SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD OCT PY 1995 VL 121 IS 528 BP 1981 EP 2005 DI 10.1002/qj.49712152810 PN B PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA TL851 UT WOS:A1995TL85100009 ER PT J AU JACKSON, TJ LEVINE, DM SWIFT, CT SCHMUGGE, TJ SCHIEBE, FR AF JACKSON, TJ LEVINE, DM SWIFT, CT SCHMUGGE, TJ SCHIEBE, FR TI LARGE-AREA MAPPING OF SOIL-MOISTURE USING THE ESTAR PASSIVE MICROWAVE RADIOMETER IN WASHITA92 SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB Washita'92 was a large-scale study of remote sensing and hydrology conducted on the Little Washita watershed in southwest Oklahoma. Data collection during the experiment included passive microwave observations using an L-band electronically scanned thinned array radiometer (ESTAR) and surface soil moisture observations at sites distributed over the area. Data were collected on 8 days over a 9-day period in June 1992. The watershed was saturated with a great deal of standing water at the outset of the study. During the experiment there was no rainfall and surface soil moisture observations exhibited a drydown pattern over the period. Significant variations in the level and rate of change in surface soil moisture were noted over areas dominated by different soil textures. ESTAR data were processed to produce brightness temperature maps of a 740 sq, km, area on each of the 8 days. These data exhibited significant spatial and temporal patterns. Spatial patterns were clearly associated with soil textures and temporal patterns with drainage and evaporative processes. Relationships between the ground-sampled soil moisture and the brightness temperatures were consistent with previous results. Spatial averaging of both variables was analyzed to study scaling of soil moisture over a mixed landscape. Results of these studies showed that a strong correlation is retained at these scales, suggesting that mapping surface moisture for large footprints may provide important information for regional studies. C1 NASA,GODDARD SPACE FLIGHT CTR,MICROWAVE SENSORS BRANCH,GREENBELT,MD 20771. UNIV MASSACHUSETTS,DEPT ELECT ENGN,AMHERST,MA 01003. USDA,WATER QUAL LAB,DURANT,OK. RP JACKSON, TJ (reprint author), USDA ARS,BARC W,HYDROL LAB,104 BLDG 007,BELTSVILLE,MD 20705, USA. NR 16 TC 82 Z9 85 U1 0 U2 3 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1995 VL 54 IS 1 BP 27 EP 37 DI 10.1016/0034-4257(95)00084-E PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA TA594 UT WOS:A1995TA59400003 ER PT J AU OTTERMAN, J BRAKKE, T SMITH, J AF OTTERMAN, J BRAKKE, T SMITH, J TI EFFECTS OF LEAF-TRANSMITTANCE VERSUS LEAF-REFLECTANCE ON BIDIRECTIONAL SCATTERING FROM CANOPY SOIL SURFACE - AN ANALYTICAL STUDY SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID VEGETATION; SATELLITE; RED; PROTRUSIONS; CANOPIES; DESERT; ALBEDO; PLANE; FIELD; MODEL AB A simple single-scattering model for a surface with sparse erectophile plants Is developed as a plane-parallel canopy consisting of small leaves (relative to leaf-to-leaf spacing) with a spherical-shell distribution of the leaf area. The contributions to the overall surface reflectance in the visible spectral bands by the soil-reflectance, leaf-reflection, and leaf-transmission (which are assumed isotropic) are analyzed under different view/illumination geometries. High values of leaf reflectance r, relative to leaf transmittance t, produce significantly different patterns of bidirectional reflectance, because r and t control the backscattering and the forward scattering, respectively. These two effects, especially strong at large solar zenith angles, produce high canopy reflectance at large view zenith angles around the principal plane. Model inversion with the PARABOLA bidirectional reflectance measurements over the Konza Prairie yield values of r and t for grassblades of this grassland canopy. The inversion results point to a possibility of assessing canopy condition from its bidirectional reflectances, as both r and t are sensitive to plant vigor and phenology. In an inversion with satellite measurements over a desert-scrub surface in the northern Sinai, the optical thickness of these dark plants (inferred in the visible band) and the near-infrared reflectance of the plant elements were inferred. The value of the optical thickness of this sparse canopy essentially did not depend on the assumed plant-element transmittance, but the inferred infrared reflectances of the plant elements were appreciably dependent. The canopy structure representation (the spherical-shell distribution of the planar leaf area) constitutes a rotation-invariant reflectance model. It allows formulation of the longwave exchanges identical to the conventional radiative transfer calculation through a layer of molecules or particles with a specified optical thickness. C1 LAND ATMOSPHERE OCEAN RES,GREENBELT,MD. RP OTTERMAN, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 9104,GREENBELT,MD 20771, USA. NR 46 TC 11 Z9 12 U1 0 U2 3 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1995 VL 54 IS 1 BP 49 EP 60 DI 10.1016/0034-4257(95)00128-N PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA TA594 UT WOS:A1995TA59400005 ER PT J AU FORNEY, LJ FRALICK, GC AF FORNEY, LJ FRALICK, GC TI MULTIWIRE THERMOCOUPLES IN REVERSING FLOW SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Measurements are recorded for multiwire thermocouples consisting of either two or three wires of unequal diameters. Signals from the multiwire probe are recorded for a reversing gas flow with both a periodic temperature and time constant fluctuation. It is demonstrated that the reconstructed signal from the multiwire thermocouple requires no compensation provided omega/omega(1)<2.3 for two wires or omega/omega(1)<3.6 for three wires where omega(1) (=2 pi f) is the natural frequency of the smaller wire based on the maximum gas velocity. The latter results were possible provided Fourier transformed data from the wires were used and knowledge of the gas velocity phase angle was available. (C) 1995 American Institute of Physics. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44195. RP FORNEY, LJ (reprint author), GEORGIA INST TECHNOL,SCH CHEM ENGN,ATLANTA,GA 30332, USA. NR 7 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1995 VL 66 IS 10 BP 5050 EP 5054 DI 10.1063/1.1146129 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA TA431 UT WOS:A1995TA43100046 ER PT J AU SIDI, A AF SIDI, A TI APPLICATION OF VECTOR-VALUED RATIONAL-APPROXIMATIONS TO THE MATRIX EIGENVALUE PROBLEM AND CONNECTIONS WITH KRYLOV SUBSPACE METHODS SO SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS LA English DT Article DE KRYLOV SUBSPACE METHODS; METHOD OF AMOLDI; METHOD OF LANCZOS; POWER ITERATIONS; GENERALIZED POWER METHODS; DIAGONALIZABLE MATRICES; DEFECTIVE MATRICES; EIGENVALUES; INVARIANT SUBSPACES; VECTOR-VALUED RATIONAL APPROXIMATIONS ID EXTRAPOLATION METHODS; CONVERGENCE; ALGORITHMS; SEQUENCES AB Let F(z) be a vector-valued function F : C --> C-N, which is analytic at z = 0 and meromorphic in a neighborhood of z = 0, and let its Maclaurin series be given. In a recent work [J. Approx Theory, 76 (1994), pp. 89-111] by the author, vector-valued rational approximation procedures for F(z) that are based on its Maclaurin series, were developed, and some of their convergence properties were analyzed in detail. In particular, a Koenig-type theorem concerning their poles and a de Montessus-type theorem concerning their uniform convergence in the complex plane were given. With the help of these theorems it was shown how optimal approximations to the poles of F(z) and the principal parts of the corresponding Laurent series expansions can be obtained. In this work we use these rational approximation procedures in conjunction with power iterations to develop bona fide generalizations of the power method for an arbitrary N x N matrix that may or may not be diagonalizable. These generalizations can be used to obtain simultaneously several of the largest distinct eigenvalues and corresponding eigenvectors and other vectors in the invariant subspaces. We provide interesting constructions for both nondefective and defective eigenvalues acid the corresponding invariant subspaces, and present a detailed convergence theory for them. This is made possible by the observation that vectors obtained by power iterations with a matrix are actually coefficients of the Maclaurin series of a vector-valued rational function, whose poles are the reciprocals of some or all of the nonzero eigenvalues of the matrix being considered, while the coefficients in the principal parts of the Laurent expansions of this rational function are vectors in the corresponding invariant subspaces. In addition, it is shown that the generalized power methods of this work are equivalent to some Krylov subspace methods, among them the methods of Arnoldi and Lanczos. Thus, the theory of the present work provides a set of completely new results and constructions for these Krylov subspace methods, At the same time this theory suggests a new mode of usage for these Krylov subspace methods that has been observed to possess computational advantages over their common mode of usage in some cases. We illustrate some of the theory and conclusions derived from it with numerical examples. C1 NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135. RP SIDI, A (reprint author), TECHNION ISRAEL INST TECHNOL,DEPT COMP SCI,IL-32000 HAIFA,ISRAEL. NR 28 TC 11 Z9 11 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0895-4798 J9 SIAM J MATRIX ANAL A JI SIAM J. Matrix Anal. Appl. PD OCT PY 1995 VL 16 IS 4 BP 1341 EP 1369 DI 10.1137/S089547989224316X PG 29 WC Mathematics, Applied SC Mathematics GA RY079 UT WOS:A1995RY07900021 ER PT J AU HUYNH, HT AF HUYNH, HT TI ACCURATE UPWIND METHODS FOR THE EULER EQUATIONS SO SIAM JOURNAL ON NUMERICAL ANALYSIS LA English DT Article DE UPWIND SCHEMES; EULER EQUATIONS; APPROXIMATE RIEMANN SOLVERS ID HYPERBOLIC CONSERVATION-LAWS; FINITE-DIFFERENCE METHODS; HIGH-RESOLUTION SCHEMES; SHOCK-CAPTURING SCHEMES; GODUNOV-TYPE METHODS; ENTROPY CONDITION; RIEMANN SOLVERS; GAS-DYNAMICS; ENO SCHEMES; SYSTEMS AB A new class of piecewise linear methods for the numerical solution of the one dimensional Euler equations of gas dynamics is presented. These methods are uniformly second-order accurate and can be considered as extensions of Godunov's scheme. With an appropriate definition of monotonicity preservation for the case of linear convection, it can be shown that they preserve monotonicity. Similar to Van Leer's scheme, they consist of two key steps: a reconstruction step followed by an upwind step. For the reconstruction step, a monotonicity constraint that preserves uniform second-order accuracy is introduced. Computational efficiency is enhanced by devising a criterion that detects the ''smooth'' part of the data where the constraint is redundant, The concept and coding of the constraint are simplified by the use of the median function. A slope-steepening technique, which has no effect at smooth regions and can resolve a contact discontinuity in four cells, is described. As for the upwind step, existing and new methods are applied in a manner slightly different from those in the literature. These methods are derived by approximating the Euler equations via linearization and diagonalization. At a ''smooth'' interface, for economy, the linearization employs the arithmetic average of the left and right states,and she Aux is obtained by one of the four simple models: the primitive-variable splitting, a simplified flux splitting. the one-intermediate-state model, or the central difference with artificial viscosity. Near a discontinuity, Roe's flux-difference splitting is used. The current presentation of Roe's method, via the conceptually simple flux-vector splitting, not only establishes a connection between the two splittings, but also leads to an admissibility correction with no conditional statement and an efficient approximation to Osher's approximate Riemann solver. These reconstruction and upwind steps result in schemes that are uniformly second-order accurate and economical at smooth regions and yield high resolution at discontinuities. RP NASA, LEWIS RES CTR, MS 5-11, CLEVELAND, OH 44135 USA. NR 63 TC 23 Z9 26 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1429 EI 1095-7170 J9 SIAM J NUMER ANAL JI SIAM J. Numer. Anal. PD OCT PY 1995 VL 32 IS 5 BP 1565 EP 1619 DI 10.1137/0732071 PG 55 WC Mathematics, Applied SC Mathematics GA RX186 UT WOS:A1995RX18600010 ER PT J AU GOSSAIN, S BATORY, D GOMAA, H LUBARS, M PIDGEON, C SEIDEWITZ, E AF GOSSAIN, S BATORY, D GOMAA, H LUBARS, M PIDGEON, C SEIDEWITZ, E TI PANEL - OBJECTS AND DOMAIN ENGINEERING - DISCUSSION SO SIGPLAN NOTICES LA English DT Discussion C1 UNIV TEXAS,AUSTIN,MN. GEORGE MASON UNIV,FAIRFAX,VA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0362-1340 J9 SIGPLAN NOTICES JI Sigplan Not. PD OCT PY 1995 VL 30 IS 10 BP 333 EP 336 PG 4 WC Computer Science, Software Engineering SC Computer Science GA TA748 UT WOS:A1995TA74800030 ER PT J AU HAINES, M MEHROTRA, P VANROSENDALE, J AF HAINES, M MEHROTRA, P VANROSENDALE, J TI SMARTFILES - AN OO APPROACH TO DATA FILE INTEROPERABILITY SO SIGPLAN NOTICES LA English DT Article; Proceedings Paper CT 10th Annual Conference on Object-Oriented Programming Systems, Languages, and Applications (OOPSLA 95) CY OCT 17-19, 1995 CL AUSTIN, TX SP Assoc Comp Machinery, SIGPLAN AB Data files for scientific and engineering codes typically consist of a series of raw data values whose description is buried in the programs that interact with these files. In this situation, making even minor changes in the file structure or sharing files between programs (interoperability) can only be done after careful examination of the data files and the I/O statements of the programs interacting with this file. In short, scientific data files lack self-description, and other self-describing data techniques are not always appropriate or useful for scientific data files. By applying an object-oriented methodology to data files, we can add the intelligence required to improve data interoperability and provide an elegant mechanism for supporting complex, evolving, or multidisciplinary applications, while still supporting legacy codes. As a result, scientists and engineers should be able to share datasets with far greater ease, simplifying multidisciplinary applications and greatly facilitating remote collaboration between scientists. C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA. RP HAINES, M (reprint author), UNIV WYOMING,DEPT COMP SCI,LARAMIE,WY 82071, USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0362-1340 J9 SIGPLAN NOTICES JI Sigplan Not. PD OCT PY 1995 VL 30 IS 10 BP 453 EP 466 PG 14 WC Computer Science, Software Engineering SC Computer Science GA TA748 UT WOS:A1995TA74800040 ER PT J AU RIEKE, GH YOUNG, ET GAUTIER, TN AF RIEKE, GH YOUNG, ET GAUTIER, TN TI DETECTION LIMITS IN THE FAR-INFRARED SO SPACE SCIENCE REVIEWS LA English DT Review DE CONFUSION LIMIT; INFRARED ARRAYS ID CONFUSION AB The advent of far infrared arrays will change fundamentally the means of analyzing observations in this spectral region. Sources much fainter than traditional ''confusion Limits'' will be extracted from images by using computer algorithms similar to CLEAN or DAOPHOT. We have conducted numerical experiments to evaluate these techniques and show that they will permit long integrations (similar to 10,OOC sec at 60 mu m, similar to 200 sec at 100 mu m) to achieve nearly photon-background-limited performance and hence very deep detection Limits. The dominant noise sources - photon noise, confusion by distant galaxies, and confusion by IR cirrus - scale with nearly the same power of the telescope aperture. As a result, the integration times required to reach confusion limits are nearly aperture-independent. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP RIEKE, GH (reprint author), UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721, USA. NR 10 TC 6 Z9 6 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1995 VL 74 IS 1-2 BP 17 EP 25 DI 10.1007/BF00751248 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TG809 UT WOS:A1995TG80900004 ER PT J AU HACKING, PB WERNER, MW AF HACKING, PB WERNER, MW TI THE WIDE-FIELD INFRARED EXPLORER (WIRE) SO SPACE SCIENCE REVIEWS LA English DT Review RP HACKING, PB (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1995 VL 74 IS 1-2 BP 89 EP 89 DI 10.1007/BF00751256 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TG809 UT WOS:A1995TG80900012 ER PT J AU ERICKSON, EF AF ERICKSON, EF TI SOFIA - THE NEXT-GENERATION AIRBORNE OBSERVATORY SO SPACE SCIENCE REVIEWS LA English DT Review AB The United States and German Space Agencies (NASA and DARA) are collaborating in plans for SOFIA - The Stratospheric Observatory for Infrared Astronomy. It is a 2.5 meter telescope to be installed in a Boeing 747 aircraft and operated at altitudes from 41,000 to 45,000 feet. It will permit routine measurement of infrared radiation absorbed by the atmosphere at lower altitudes, and observation of astronomical objects and transient events from anywhere in the world. The concept is based on 20 years of experience with NASA's Kuiper Airborne Observatory (KAO), which SOFIA would replace. SOFIA will complement the capabilities of other future space missions, and will enable scientists to make observations which would otherwise be made from space. RP ERICKSON, EF (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 2 TC 17 Z9 17 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1995 VL 74 IS 1-2 BP 91 EP 100 DI 10.1007/BF00751257 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TG809 UT WOS:A1995TG80900013 ER PT J AU WERNER, MW SIMMONS, LL AF WERNER, MW SIMMONS, LL TI SIRFT - THE MODERATE MISSION SO SPACE SCIENCE REVIEWS LA English DT Review AB The Space Infrared Telescope Facility (SIRTF) has been planned by NASA and the US scientific and aerospace communities as a cryogenically-cooled observatory for infrared astronomy from space. Within the past few years, severe pressures on NASA's budget have led to the cancellation of many programs and to dramatic rescoping of others; SIRTF is in the latter category. This paper describes the resulting redefinition of SIRTF and the technical innovations which have made it possible to package SIRTF's key scientific capabilities into the envelope of a moderate-class mission. RP WERNER, MW (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1995 VL 74 IS 1-2 BP 125 EP 138 DI 10.1007/BF00751261 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TG809 UT WOS:A1995TG80900017 ER PT J AU LANGE, AE BOCK, JJ MASON, P AF LANGE, AE BOCK, JJ MASON, P TI THE FAR-INFRARED EXPLORER (FIRE) SO SPACE SCIENCE REVIEWS LA English DT Review ID MICROWAVE AB We describe the Far IR Explorer, a MIDEX-class orbital mission designed to survey the entire sky at millimeter and sub-millimeter wavelengths. The primary science goal of FIRE is to map the Cosmic Microwave Background with 20' resolution and 1ppm precision. In addition, FIRE will measure diffuse radio and infrared emission from the Galaxy with unprecedented sensitivity, and will uniformly survey the entire sky to a limiting flux density of < 100 mJy (3 sigma). C1 JET PROP LAB,PASADENA,CA. RP LANGE, AE (reprint author), UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1995 VL 74 IS 1-2 BP 151 EP 156 DI 10.1007/BF00751264 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TG809 UT WOS:A1995TG80900020 ER PT J AU BONDAR, RL KASSAM, MS STEIN, F DUNPHY, PT FORTNEY, S RIEDESEL, ML AF BONDAR, RL KASSAM, MS STEIN, F DUNPHY, PT FORTNEY, S RIEDESEL, ML TI SIMULTANEOUS CEREBROVASCULAR AND CARDIOVASCULAR-RESPONSES DURING PRESYNCOPE SO STROKE LA English DT Article DE BLOOD FLOW VELOCITY; CEREBRAL BLOOD FLOW; HYPOTENSION; SYNCOPE; ULTRASONICS ID CEREBRAL BLOOD-FLOW; SYMPATHETIC-NERVE STIMULATION; BODY NEGATIVE-PRESSURE; AUTO-REGULATION; PIAL ARTERIES; AUTOREGULATION; HUMANS AB Background and Purpose Presyncope, characterized by symptoms and signs indicative of imminent syncope, can be aborted in many situations before loss of consciousness occurs. The plasticity of cerebral autoregulation in healthy humans and its behavior during this syncopal prodrome are unclear, although systemic hemodynamic instability has been suggested as a key factor in the precipitation of syncope. Using lon er body negative pressure (LBNP) to simulate central hypovolemia, we previously observed falling mean Bow velocities (MFVs) with maintained mean arterial blood pressure (MABP). These findings, and recent reports suggesting increased vascular tone within the cerebral vasculature at presyncope, cannot be explained by the classic static cerebral autoregulation curve; neither san they be totally explained by a recent suggestion of a rightward shift in this curve. Methods Four male and five female healthy volunteers were exposed to presyncopal LBNP to evaluate their cerebrovascular and cardiovascular responses by use of continuous acquisition of MFV from the right middle cerebral artery with transcranial Doppler sonography, MABP (Finapres), and heart rate (EGG). Results At presyncope, MFV dropped on average by 27.3+/-14% of its baseline value (P<.05), while MABP remained at 2.0+/-27% above its baseline level. Estimated cerebrovascular resistance increased during LBNP. The percentage change from baseline to presyncope in MFV and MABP revealed consistent decreases in MFV before MABP. Conclusions increased estimated cerebrovascular resistance, falling MFV, and constant MABP are evidence of an increase in cerebral vascular tone with falling flow, suggesting a downward shift in the cerebral autoregulation curve. Cerebral vessels may have a differential sensitivity to sympathetic drive or more than one type of sympathetic innervation. Future work to induce dynamic changes in MABP during LBNP may help in assessing the plasticity of the cerebral autoregulation mechanism. C1 RYERSON POLYTECH UNIV,CTR ADV TECHNOL EDUC,TORONTO,ON M5B 2K3,CANADA. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV NEW MEXICO,DEPT BIOL,ALBUQUERQUE,NM 87131. NR 37 TC 84 Z9 85 U1 4 U2 4 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0039-2499 J9 STROKE JI Stroke PD OCT PY 1995 VL 26 IS 10 BP 1794 EP 1800 PG 7 WC Clinical Neurology; Peripheral Vascular Disease SC Neurosciences & Neurology; Cardiovascular System & Cardiology GA RX185 UT WOS:A1995RX18500010 PM 7570727 ER PT J AU MIRANDA, FA MUELLER, CH KOEPF, GA YANDROFSKI, RM AF MIRANDA, FA MUELLER, CH KOEPF, GA YANDROFSKI, RM TI ELECTRICAL RESPONSE OF FERROELECTRIC SUPERCONDUCTING DIELECTRIC BAXSR1-XTIO3/YBA2CU3O7-DELTA/LAALO3 THIN-FILM MULTILAYER STRUCTURES SO SUPERCONDUCTOR SCIENCE & TECHNOLOGY LA English DT Article ID MICROWAVE AB Multilayered structures of ferroelectric and superconducting films deposited on dielectric substrates are being developed for use in low-loss tunable microwave components for satellite and ground-based communications. In this paper, we report on the electrical characterization of BaxSr1-xTiO3 (x = 0, 0.08 and 0.10)/YBa2Cu3O7-delta/LaAlO3 thin-film multilayer structures. These structures were formed in situ using a pulsed laser deposition method by the sequential deposition of the YBa2Cu3O7-delta (YBCO) high-temperature superconductor (HTS) and the SrTiO3 (STO) or Ba0.10Sr0.90TiO3 (BST) films on 20 mil (0.5 mm) thick (100) LaAlO3 single-crystal substrates and by using a metal organic deposition method to deposit the Ba0.08Sr0.92TiO3 films. These processes produced YBCO films with thicknesses of 300 nm and ferroelectric films with thicknesses of 250 and 500 nm. The YBCO films showed a transition temperature (T-c) above 89 K after deposition and processing of the ferroelectric layers. Electrical characterization of these structures was performed by measuring the capacitance (C), relative dielectric constant (epsilon(r)), and loss tangent (tan delta) of the ferroelectric film in the temperature range from 300 to 40 K and at electric fields (E) from zero to 2.0 x 10(5) V cm(-1). For 500 nm and 250 nm thick BST films having the same stoichiometry, epsilon(r) values of 191 and 126, respectively, were obtained at 300 K, 1.0 MHz, and zero E. Corresponding tan delta values of 0.096 and 0.021 were measured for the 500 nm and 250 nm thick samples, respectively, at the aforementioned temperature, frequency and E. It was observed that the amount of variation of epsilon(r) as a function of E was closely related to the microstructure of the films. Evidence of conductive pathways in the ferroelectric film as well as of ferroelectric domain 'lock-in' under a d.c. bias is presented. C1 SUPERCONDUCTING CORE TECHNOL,GOLDEN,CO 80401. RP MIRANDA, FA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 43 Z9 43 U1 0 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-2048 J9 SUPERCOND SCI TECH JI Supercond. Sci. Technol. PD OCT PY 1995 VL 8 IS 10 BP 755 EP 763 DI 10.1088/0953-2048/8/10/003 PG 9 WC Physics, Applied; Physics, Condensed Matter SC Physics GA RY769 UT WOS:A1995RY76900003 ER PT J AU BEMIS, K BOGDANSKI, MS DELLACORTE, C SLINEY, HE AF BEMIS, K BOGDANSKI, MS DELLACORTE, C SLINEY, HE TI THE EFFECT OF PROLONGED EXPOSURE TO 750-DEGREES-C AIR ON THE TRIBOLOGICAL PERFORMANCE OF PM212 - SELF-LUBRICATING COMPOSITE-MATERIAL SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 49th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 01-05, 1994 CL PITTSBURGH, PA SP Soc Tribologists & Lubricat Engineers DE SOLID LUBRICATION; HIGH TEMPERATURE; FRICTION; WEAR AB The effect of prolonged exposure to 750 degrees C air on the tribological performance and dimensional stability of PM212, a high temperature, self-lubricating composite, is studied. PM212, by weight, contains 70% metal-bonded Cr3C2, 15% BaF2/CaF2 eutectic and 15% silver. Rub blocks were fabricated from PM212 by cold isostatic pressure followed by sintering. Prior to tribo-testing, the rub blocks were exposed to 750 degrees C air for periods ranging from 100 to 1000 hours. Then, the rub blocks were slid against nickel-based superalloy disks in a double-rub-block tribometer in air under a 66N load at temperatures from 25 degrees to 750 degrees C with a sliding velocity of 0.36 m/s. Unexposed rub blocks were tested for baseline comparison. Friction coefficients ranged from 0.24 to 0.37 for the unexposed rub blocks and from 0.32 to 0.56 for the exposed ones. Wear for both the composite blocks and superalloy disks was typically in the moderate to low range of 10(-5) to 10(-6) mm(3)/N-m. Friction and wear data were similar for the rub blocks exposed for 100, 500. and 1000 hours. Prolonged exposure to 750 degrees C air increased friction and war of the PM212 rub blocks at room temperature, but their triboperformance remained unaffected at higher temperatures, probably due to the formation of lubricious metal oxides. Dimensional stability of the composite was studied by exposing specimens of varying thicknesses for 500 hours in air at 750 degrees C. Block thicknesses were found to increase with increased exposure time until steady state was reached after 100 hours of exposure, probably due to oxidation. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. AEROSP DESIGN & FABRICAT INC,BROOKPARK,OH 44142. RP BEMIS, K (reprint author), CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106, USA. NR 10 TC 3 Z9 4 U1 0 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD OCT PY 1995 VL 38 IS 4 BP 745 EP 756 DI 10.1080/10402009508983468 PG 12 WC Engineering, Mechanical SC Engineering GA RY454 UT WOS:A1995RY45400001 ER PT J AU VERGHESE, P STONE, LS AF VERGHESE, P STONE, LS TI COMBINING SPEED INFORMATION ACROSS SPACE SO VISION RESEARCH LA English DT Article DE MULTIPLE STIMULI; INTEGRATION; SEARCH; UNCERTAINTY; SPEED DISCRIMINATION ID SPATIAL-FREQUENCY; TEMPORAL FREQUENCY; VISUAL-PATTERNS; PERCEIVED SPEED; STIMULUS SIZE; OPTIC FLOW; CONTRAST; FIELD; DISCRIMINATION; MOTION AB We used speed discrimination tasks to measure the ability of observers to combine speed information from multiple stimuli distributed across space. We compared speed discrimination thresholds in a classical discrimination paradigm to those in an uncertainty/search paradigm. Thresholds were measured using a temporal two-interval forced-choice design. In the discrimination paradigm, the n gratings in each interval all moved at the same speed and observers were asked to choose the interval with the faster gratings. Discrimination thresholds for this paradigm decreased as the number of gratings increased. This decrease was not due to increasing the effective stimulus area as a control experiment that increased the area of a single grating did not show a similar improvement in thresholds. Adding independent speed noise to each of the n gratings caused thresholds to decrease at a rate similar to the original no-noise case, consistent with observers combining an independent sample of speed from each grating in both the added- and no-noise cases. In the search paradigm, observers were asked to choose the interval in which one of the n gratings moved faster. Thresholds in this case increased with the number of gratings, behavior traditionally attributed to an input bottleneck. However, results from the discrimination paradigm showed that the increase was not due to observers' inability to process these gratings. We have also shown that the opposite trends of the data in the two paradigms can be predicted by a decision theory model that combines independent samples of speed information across space. This demonstrates that models typically used in classical detection and discrimination paradigms are also applicable to search paradigms. As our model does not distinguish between samples in space and time, it predicts that discrimination performance should be the same regardless of whether the gratings are presented in two spatial intervals or two temporal intervals. Our last experiment largely confirmed this prediction. RP VERGHESE, P (reprint author), NASA,AMES RES CTR,M-S 262-2,MOFFETT FIELD,CA 94035, USA. NR 44 TC 64 Z9 64 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD OCT PY 1995 VL 35 IS 20 BP 2811 EP 2823 DI 10.1016/0042-6989(95)00038-2 PG 13 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA RY459 UT WOS:A1995RY45900002 PM 8533322 ER PT J AU PATNAIK, SN GUPTILL, JD BERKE, L AF PATNAIK, SN GUPTILL, JD BERKE, L TI MERITS AND LIMITATIONS OF OPTIMALITY CRITERIA METHOD FOR STRUCTURAL OPTIMIZATION SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE STRUCTURES; STRUCTURAL DESIGN; OPTIMIZATION; LAGRANGIAN AB The merits and limitations of the Optimality Criteria (OC) method for the minimum weight design of structures subjected to multiple load conditions under stress, displacement and frequency constraints were investigated by examining several numerical examples. The examples were solved utilizing the OC design code that was developed for this purpose at the NASA Lewis Research Center. This OC code incorporates OC methods available in the literature with generalizations for stress constraints, fully utilized design concepts, and hybrid methods that combine both techniques. It includes multiple choices for Lagrange multiplier and design variable update methods, design strategies for several constraint types, variable linking, displacement and integrated force method analysers, and analytical and numerical sensitivities. On the basis of the examples solved, the optimality criteria for general application were found to be satisfactory for problems with few active constraints or with small numbers of design variables. However, the OC method without stress constraints converged to optimum even for large structural systems. For problems with large numbers of behaviour constraints and design variables, the method appears to follow a subset of active constraints that can result in a heavier design. The computational efficiency of OC methods appears to be similar to some mathematical programming techniques. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PATNAIK, SN (reprint author), OHIO AEROSP INST,BROOKPARK,OH 44142, USA. NR 23 TC 23 Z9 23 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD SEP 30 PY 1995 VL 38 IS 18 BP 3087 EP 3120 DI 10.1002/nme.1620381806 PG 34 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA RU970 UT WOS:A1995RU97000005 ER PT J AU RICCA, A BAUSCHLICHER, CW AF RICCA, A BAUSCHLICHER, CW TI THE LOW-LYING ELECTRONIC STATES OF LIC SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CORE POLARIZATION POTENTIALS; ABINITIO CALCULATIONS; ALKALI; ATOMS; IONS AB The spectroscopic constants for the doublet and quartet states of LiC below about 30000 cm(-1) are determined using an internally contracted multireference configuration-interaction approach in conjunction with a [6s5p3d2f] atomic natural orbital basis sets. All of the strongly bound states, X(4) Sigma(-), (1)(2) Delta, (1)(2) Sigma(+), and (2)(2) Pi, are very ionic in character. The only bound-bound quartet transition in this energy range is (2)(4) Sigma(-) - X(4) Sigma(-) and Franck-Condon factors, Einstein A values, and lifetimes are reported for this transition. RP RICCA, A (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 12 TC 13 Z9 14 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD SEP 29 PY 1995 VL 244 IS 1-2 BP 32 EP 38 DI 10.1016/0009-2614(95)00909-N PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA RX739 UT WOS:A1995RX73900005 ER PT J AU KEMP, P AF KEMP, P TI PROGRAM PROVIDES ISA-BUS DLL FOR WINDOWS SO EDN LA English DT Note RP KEMP, P (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU CAHNERS-DENVER PUBLISHING CO PI HIGHLANDS RANCH PA 8773 S RIDGELINE BLVD, HIGHLANDS RANCH, CO 80126-2329 SN 0012-7515 J9 EDN JI EDN PD SEP 28 PY 1995 VL 40 IS 20 BP 90 EP 92 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA RX227 UT WOS:A1995RX22700024 ER PT J AU SIMONS, RN DIB, NI KATEHI, LPB AF SIMONS, RN DIB, NI KATEHI, LPB TI COPLANAR STRIPLINE TO MICROSTRIP TRANSITION SO ELECTRONICS LETTERS LA English DT Article DE COPLANAR WAVE-GUIDE; STRIP LINE COUPLERS; STRIP LINES AB A newcoplanar stripline to microstrip line transition is experimentally demonstrated and modelled using the finite difference time domain technique, The measured insertion loss and return loss for two back-to-back transitions with a short length of microstrip line in between are better than 2.4 and -10dB, respectively, over the frequency range of 5.1 - 6.1GHz. The bandwidth cf the transition is similar to 18% at a centre frequency of 5.55 GHz. C1 UNIV MICHIGAN,RADIAT LAB,ANN ARBOR,MI 48109. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,NYMA GRP,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 4 TC 23 Z9 24 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTS PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTS, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD SEP 28 PY 1995 VL 31 IS 20 BP 1725 EP 1726 DI 10.1049/el:19951179 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA RY742 UT WOS:A1995RY74200015 ER PT J AU HINKLEY, JA YUE, JJ AF HINKLEY, JA YUE, JJ TI OXIDATIVE AGING OF THERMOPLASTIC POLYIMIDE FILMS SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article AB Two linear polyimides were subjected to accelerated isothermal aging at temperatures between 300 and 400 degrees C. Losses in toughness correlated well with changes in glass transition temperature (T-g) of the films, but not with weight loss. Both materials have extrapolated lifetimes of 100,000 h near their T-g's. (C) 1995 John Wiley & Sons, Inc. RP HINKLEY, JA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 14 TC 5 Z9 5 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD SEP 26 PY 1995 VL 57 IS 13 BP 1539 EP 1543 DI 10.1002/app.1995.070571301 PG 5 WC Polymer Science SC Polymer Science GA RQ715 UT WOS:A1995RQ71500001 ER PT J AU PIQUE, A HARSHAVARDHAN, KS MOSES, J MATHUR, M VENKATESAN, T BRASUNAS, JC LAKEW, B AF PIQUE, A HARSHAVARDHAN, KS MOSES, J MATHUR, M VENKATESAN, T BRASUNAS, JC LAKEW, B TI DEPOSITION OF HIGH-QUALITY YBA2CU3O7-X FILMS ON ULTRATHIN (12 MU-M THICK) SAPPHIRE SUBSTRATES FOR INFRARED DETECTOR APPLICATIONS SO APPLIED PHYSICS LETTERS LA English DT Article AB High quality epitaxial YBa2Cu3O7-x (YBCO) thin films have been deposited on 12 mu m thick (1 (1) over bar 02) oriented sapphire substrates using a CeO2 buffer layer. Both layers were deposited by pulsed laser deposition (PLD) using a blackbody-type heater, The YBCO films showed superconductive transition temperatures of 88-89.5 K and transition widths less than or equal to 0.5 K. Structural evaluation of the films indicate that the YBCO films are c-axis oriented, with the YBCO (005) peak showing a rocking angle full width half-maximum (FWHM) of about 0.7 degrees. The phi-scans of the (103) YBCO peak indicate a high degree of in-plane epitaxy with no signs of high angle grain boundaries, The high quality of these films combined with the low heat capacity of the substrates, make these structures ideal for infrared detector applications. (C) 1995 American Institute of Physics. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,DEPT ELECT ENGN,COLLEGE PK,MD 20742. UNIV MARYLAND,DEPT PHYS,CTR SUPERCONDUCT RES,COLLEGE PK,MD 20742. HUGHES STX CORP,LANHAM,MD 20706. RP PIQUE, A (reprint author), NEOCERA INC,BELTSVILLE,MD 20705, USA. RI brasunas, john/I-2798-2013; Venkatesan, Thirumalai/E-1667-2013 NR 7 TC 10 Z9 10 U1 0 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 25 PY 1995 VL 67 IS 13 BP 1920 EP 1922 PG 3 WC Physics, Applied SC Physics GA RW225 UT WOS:A1995RW22500043 ER PT J AU MOORE, JM SCHENK, PM NASH, DB AF MOORE, JM SCHENK, PM NASH, DB TI INTRODUCTION TO THE ICY GALILEAN SATELLITES SPECIAL SECTION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material C1 NASA,AMES RES CTR,INST SETI,MOFFETT FIELD,CA 94035. LUNAR & PLANETARY INST,HOUSTON,TX 77058. SAN JUAN CAPISTRANO RES INST,SAN JUAN CAPISTRANO,CA 92675. RP MOORE, JM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 18933 EP 18933 DI 10.1029/95JE01619 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300001 ER PT J AU CARR, MH BELTON, MJS BENDER, K BRENEMAN, H GREELEY, R HEAD, JW KLAASEN, KP MCEWEN, AS MOORE, JM MURCHIE, S PAPPALARDO, RT PLUTCHAK, J SULLIVAN, R THORNHILL, G VEVERKA, J AF CARR, MH BELTON, MJS BENDER, K BRENEMAN, H GREELEY, R HEAD, JW KLAASEN, KP MCEWEN, AS MOORE, JM MURCHIE, S PAPPALARDO, RT PLUTCHAK, J SULLIVAN, R THORNHILL, G VEVERKA, J TI THE GALILEO IMAGING TEAM PLAN FOR OBSERVING THE SATELLITES OF JUPITER SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID INTERNAL STRUCTURE; GROOVED TERRAIN; DOME CRATERS; ICE SHELL; GANYMEDE; EUROPA; CALLISTO; SURFACE; SYSTEM; EVOLUTION AB The Galileo spacecraft carries a 1500-nm focal length camera with a 800 X 800 CCD detector that will provide images with a spatial resolution of 10 mu rad/pixel. The spacecraft will fly by Io at the time of Jupiter Orbit Insertion (JOI) and, subsequently, while in Jupiter's orbit, will have a total of 10 close passes by Europa, Ganymede, and Callisto. These dose passes, together with more distant encounters, will be used by the imaging experiment primarily to obtain high-resolution coverage of selected targets, to fill gaps left in the Voyager coverage, to extend global color coverage of each satellite, and to follow changes in the volcanic activity of Io. The roughly 390 Mbit allocated for imaging during the tour will be distributed among several hundred frames compressed by factors that range from 1 to possibly as high as 50. After obtaining high-resolution samples during the initial Io encounter at JOI, roughly 10% of imaging resources are devoted to near-terminator mapping of Io's topography at 2- to 10-km resolution, monitoring color and albedo changes of the Ionian surface, and monitoring plume activity. Observations of Europa range in resolution from several kilometers per pixel to 10 m/pixel. The objectives of Europa are (1) to determine the nature, origin, and age of the tectonic features, (2) to determine the nature, rates, and sequence of resurfacing events, (3) to assess the satellite's cratering history, and (4) to map variations in spectral and photometric properties. Europa was poorly imaged by Voyager, so the plan includes a mix of high- and low-resolution sequences to provide context. The imaging objectives at Ganymede are (1) to characterize any volcanism, (2) to determine the nature and timing of any tectonic activity, (3) to determine the history of formation and degradation of impact craters, and (4) to determine the nature of the surface materials. Because Ganymede was well imaged by Voyager, most of the resources at Ganymede are devoted to high-resolution observations. The Callisto observations will be directed mostly toward (1) filling Voyager gaps, (2) acquiring high-resolution samples of typical cratered terrain and components of the Valhalla and Asgaard basins, (3) acquiring global color, and (4) determining the photometric properties of the surface. A small number of frames will be used to better characterize the small inner satellites of Jupiter, Thebe, Amalthea, Metis, and Adrastea. C1 NATL OPT ASTRON OBSERV,TUCSON,AZ. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. JET PROP LAB,PASADENA,CA. BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. US GEOL SURVEY,FLAGSTAFF,AZ 86001. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. APPL PHYS LAB,BALTIMORE,MD. CORNELL UNIV,ITHACA,NY. RP CARR, MH (reprint author), US GEOL SURVEY,345 MIDDLEFIELD RD,MENLO PK,CA 94025, USA. RI Murchie, Scott/E-8030-2015 OI Murchie, Scott/0000-0002-1616-8751 NR 70 TC 24 Z9 24 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 18935 EP 18955 DI 10.1029/95JE00971 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300002 ER PT J AU SMYTHE, WD LOPESGAUTIER, R OCAMPO, A HUI, J SEGURA, M SODERBLOM, LA MATSON, DL KIEFFER, HH MCCORD, TB FANALE, FP CALVIN, WM SUNSHINE, J BARBINIS, E CARLSON, RW WEISSMAN, PR AF SMYTHE, WD LOPESGAUTIER, R OCAMPO, A HUI, J SEGURA, M SODERBLOM, LA MATSON, DL KIEFFER, HH MCCORD, TB FANALE, FP CALVIN, WM SUNSHINE, J BARBINIS, E CARLSON, RW WEISSMAN, PR TI GALILEAN SATELLITE OBSERVATION PLANS FOR THE NEAR-INFRARED MAPPING SPECTROMETER EXPERIMENT ON THE GALILEO SPACECRAFT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID SULFUR FLOWS; LONGITUDINAL DISTRIBUTION; IOS SURFACE; REFLECTANCE; VOLCANISM; CALLISTO; GANYMEDE; SPECTRA; SO2; VOYAGER-1 AB On December 7, 1995, the Galileo spacecraft will begin observations of the Jovian system with orbit insertion and a satellite tour of 10 orbits. The Galilean satellites will be observed with four remote sensing instruments spanning the ultraviolet, visible, near infrared, and thermal infrared regions of the spectrum. The Galileo near-infrared mapping spectrometer will observe the satellites in the wavelength range 0.7-5.2 mu m, a region particularly well suited for analyzing volatile components. Planned observations include mapping most available longitudes at about 100-km resolution per pixel at full wavelength resolution, together with observing limited regions at high spatial resolution. The opportunity to affect the choice and design of observations for the Galileo tour ex-tends until June 1996. C1 US GEOL SURVEY,ASTROGEOL STUDIES BRANCH,FLAGSTAFF,AZ 86001. UNIV HAWAII,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. SETS TECHNOL INC,MILILANI,HI 96789. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. RP SMYTHE, WD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Lopes, Rosaly/D-1608-2016 OI Lopes, Rosaly/0000-0002-7928-3167 NR 53 TC 20 Z9 20 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 18957 EP 18972 DI 10.1029/95JE01766 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300003 ER PT J AU TAMPPARI, LK SPENCER, JR MARTIN, TZ AF TAMPPARI, LK SPENCER, JR MARTIN, TZ TI OBSERVING THE ICY JOVIAN SATELLITES WITH THE GALILEO PHOTOPOLARIMETER RADIOMETER INSTRUMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID INFRARED OBSERVATIONS; IO; GANYMEDE; CALLISTO; HOTSPOTS AB The photopolarimeter/radiometer (PPR) instrument aboard the Galileo spacecraft will go into orbit around Jupiter in December 1995. The 23-month tour offers PPR four Ganymede encounters, three Callisto encounters, and three Europa encounters with maximum PPR resolution varying from 0.5 km to 8 km and typical resolution of 200 km. In addition, there will be one Ganymede, one Callisto, and two Europa ''nontargeted'' encounters, giving maximum PPR resolution from 58 km to 200 km, with a typical resolution of 300 km. There is a single Io encounter before Jupiter orbit insertion that will provide resolutions ranging from 400 km to 2.5 km, and numerous subsequent opportunities to observe Io with resolution as good as 600 km. The PPR will be used to study the polarization of reflected sunlight from each satellite over a wide range of phase angles. It will also map daytime and nighttime surface temperatures to look for spatial variations in thermophysical properties, study volcanic activity on Io, and look for possible endogenic thermal activity on Europa. These observation plans are presented. C1 LOWELL OBSERV,FLAGSTAFF,AZ 86001. RP TAMPPARI, LK (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 264-723,PASADENA,CA 91109, USA. NR 29 TC 0 Z9 0 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 18973 EP 18983 DI 10.1029/95JE00941 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300004 ER PT J AU SCHENK, PM MOORE, JM AF SCHENK, PM MOORE, JM TI VOLCANIC CONSTRUCTS ON GANYMEDE AND ENCELADUS - TOPOGRAPHIC EVIDENCE FROM STEREO IMAGES AND PHOTOCLINOMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID GALILEAN SATELLITES; CRATER FORMATION; ICY SATELLITES; DOME CRATERS; RHEOLOGY; CALLISTO; TERRAIN; JUPITER; SATURN; SYSTEM AB The morphology of volcanic features on Ganymede differs significantly from that on the terrestrial planets. Few if any major volcanic landforms, such as thick flows of shield volcanoes, have been identified to date. Using new stereo Voyager images, we have searched Ganymede for relief-generating volcanic constructs. We observed seven major types of volcanic structures, including several not previously recognized. The oldest are broad flat-topped domes partially filling many older craters in dark terrain. Similar domes occur on Enceladus. Together with smooth dark deposits, these domes indicate that the volcanic history of the dark terrain is complex. Bright terrain covers vast areas, although the style of emplacement remains unclear. Smooth bright materials embay and flood older terrains, and may have been emplaced as low-viscosity fluids. Associated with smooth bright material are a number of scalloped-shaped, semi-enclosed scarps that cut into preexisting terrain. In planform these structures resemble terrestrial calderas, The youngest volcanic materials identified are a series of small flows that may have flooded the floor of the multiring impact structure Gilgamesh, forming a broad dome. The identification of volcanic constructs up to 1 km thick is the first evidence for extrusion of moderate-to-high viscosity material on Ganymede. Viscosity and yield strength estimates for these materials span several orders of magnitude, indicating that volcanic materials on Ganymede have a range of compositions and/or were extruded under a wide range of conditions and/or eruptive styles. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. RP SCHENK, PM (reprint author), LUNAR & PLANETARY INST,3600 BAY AREA BLVD,HOUSTON,TX 77058, USA. NR 64 TC 23 Z9 23 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 19009 EP 19022 DI 10.1029/95JE01854 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300006 ER PT J AU CALVIN, WM CLARK, RN BROWN, RH SPENCER, JR AF CALVIN, WM CLARK, RN BROWN, RH SPENCER, JR TI SPECTRA OF THE ICY GALILEAN SATELLITES FROM 0.2 TO 5 MU-M - A COMPILATION, NEW OBSERVATIONS, AND A RECENT SUMMARY SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID MAGNETOSPHERIC ION-BOMBARDMENT; INFRARED-SPECTRA; REFLECTANCE SPECTROSCOPY; OPTICAL-CONSTANTS; CALLISTO; EUROPA; SPECTROPHOTOMETRY; MICROMETERS; ULTRAVIOLET; AMMONIA AB From a variety of sources in the literature and from recent, unpublished, high-spectral-resolution data, we can now piece together spectra of both leading and trailing hemispheres for all three icy Galilean satellites from 0.24 to 4 or, in some cases, to 5 mu m. The presentation of composite spectra for both hemispheres of all three satellites lends itself to a brief summary of recent results and observations, discussion of the variation in surface composition and surface processing among the three satellites, evolution of our understanding since the comprehensive reviews of the early to mid-1980's, and suggestions for future observations. The data compilation will assist those planning telescopic observations or spectral modeling studies in support of the Galileo mission to Jupiter, those making observations of other icy solar system bodies, or those designing observation plans for the Cassini mission to Saturn. C1 CALTECH,JET PROP LAB,MS 183-501,PASADENA,CA 91109. US GEOL SURVEY,DENVER FED CTR,MS 964,DENVER,CO 80225. LOWELL OBSERV,FLAGSTAFF,AZ 86001. RP CALVIN, WM (reprint author), US GEOL SURVEY,ASTROGEOL BRANCH,2255 N GEMINI DR,FLAGSTAFF,AZ 86001, USA. NR 47 TC 83 Z9 83 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 19041 EP 19048 DI 10.1029/94JE03349 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300008 ER PT J AU BURATTI, BJ AF BURATTI, BJ TI PHOTOMETRY AND SURFACE-STRUCTURE OF THE ICY GALILEAN SATELLITES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article; Proceedings Paper CT Icy Galilean Satellites Conference CY FEB, 1994 CL SAN JUAN CAPISTRANO INST, SAN JUAN CAPISTRANO, CA SP Galileo Project Off, San Juan Capistrano Inst HO SAN JUAN CAPISTRANO INST ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; DISK-INTEGRATED PHOTOMETRY; VOYAGER PHOTOMETRY; RADIATIVE-TRANSFER; GANYMEDE; CALLISTO; EUROPA; SYSTEM AB Observations of the icy Galilean satellites from both spacecraft and ground-based telescopes have been fit to radiative transfer models describing the surfaces in terms of their roughness, compaction state, and single-particle phase function and albedo. The macroscopically rough nature of Ganymede and Callisto is similar to the Moon's, while Europa is significantly smoother. The sharply peaked opposition surge on Europa may be due to an extremely uncompacted upper regolith. However, if the peak is attributed to coherent backscatter, its surface may be the most compacted of the Galilean satellites. The compaction state of Callisto is similar to that of the Moon, while Ganymede's surface is more compacted. Callisto and possibly Europa exhibit textural differences in their leading and trailing hemispheres. This dichotomy is due to enhanced erosion by meteorites on the leading side. RP BURATTI, BJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL CODE 183-501,PASADENA,CA 91109, USA. NR 43 TC 18 Z9 18 U1 3 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 1995 VL 100 IS E9 BP 19061 EP 19066 DI 10.1029/95JE00146 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RW743 UT WOS:A1995RW74300011 ER PT J AU LEE, TJ HEADGORDON, M RENDELL, AP AF LEE, TJ HEADGORDON, M RENDELL, AP TI INVESTIGATION OF A DIAGNOSTIC FOR PERTURBATION-THEORY - COMPARISON TO THE T-1 DIAGNOSTIC OF COUPLED-CLUSTER THEORY SO CHEMICAL PHYSICS LETTERS LA English DT Article ID HARTREE-FOCK REFERENCE; GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; SPIN ORBITALS; ROW ATOMS; 5TH-ORDER; ABINITIO AB A diagnostic for perturbation theory calculations, S-2, is defined and numerical results compared to the established I-1 diagnostic from coupled-cluster theory. S-2 is the lowest-order non-zero contribution to a Moller-Plesset perturbation expansion of I-1. S-2 is a reasonable estimate of the importance of non-dynamical electron correlation although not as reliable as I-1. S-2 values less than or equal to 0.012 suggest that low orders of perturbation theory should yield reasonable results; S-2 values between 0.012 and 0.015 suggest that caution is required in interpreting results from low orders of perturbation theory; S-2 values greater than or equal to 0.015 indicate that low orders of perturbation theory are not reliable for accurate results. Although not required mathematically, S-2 is always less than I-1 for the examples studied here. C1 UNIV CALIF BERKELEY, DEPT CHEM, BERKELEY, CA 94720 USA. AUSTRALIAN NATL UNIV, SUPERCOMP FACIL, CANBERRA, ACT 0200, AUSTRALIA. 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 30 TC 24 Z9 24 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 SEP 22 PY 1995 VL 243 IS 5-6 BP 402 EP 408 DI 10.1016/0009-2614(95)00875-5 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA RV435 UT WOS:A1995RV43500007 ER PT J AU WALCH, SP AF WALCH, SP TI CHARACTERIZATION OF THE MINIMUM ENERGY PATH FOR THE REACTION OF SINGLET METHYLENE WITH N-2 - THE ROLE OF SINGLET METHYLENE IN PROMPT NO SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; REACTION CH(X2-PI)+N2(X1-SIGMA-G+)->HCN(X1-SIGMA+)+N(4S); BASIS-SETS; MECHANISM AB We report calculations of the minimum energy pathways connecting (CH2)-C-1+N-2 to diazomethane and diazirine, for the rearrangement of diazirine to diazomethane, for the dissociation of diazirine to HCN2+H, and of diazomethane to CH2N+N. The calculations use complete active space self-consistent field (CASSCF) derivative methods to characterize the stationary points and internally contracted configuration interaction (ICCI) to determine the energetics. The calculations suggest a potential new source of prompt NO from the reaction of (CH2)-C-1 with N-2 to give diazirine, and subsequent reaction of diazirine with hydrogen abstracters to form doublet HCN2, which leads to HCN+N(S-4) on the previously studied CH+N-2 surface. The calculations also predict accurate 0 K heats of formation of 77.7 kcal/mol and 68.0 kcal/mol for diazirine and diazomethane, respectively. (C) 1995 American Institute of Physics. RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 27 TC 13 Z9 13 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 22 PY 1995 VL 103 IS 12 BP 4930 EP 4936 DI 10.1063/1.470629 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA RU876 UT WOS:A1995RU87600013 ER PT J AU WALCH, SP TAYLOR, PR AF WALCH, SP TAYLOR, PR TI CHARACTERIZATION OF THE MINIMUM ENERGY PATHS AND ENERGETICS FOR THE REACTION OF VINYLIDENE WITH ACETYLENE SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; GAUSSIAN-BASIS SETS; PHOTOELECTRON-SPECTROSCOPY; STATES; ATOMS AB The reaction of vinylidene (CH2C) with acetylene may be an initiating reaction in soot formation. We report minimum energy paths and accurate energetics for a pathway leading to vinylacetylene and for a number of isomers of C4H4. The calculations use complete active space self-consistent field (CASSCF) derivative methods to characterize the stationary points and internally contacted configuration interaction (ICCI) and/or coupled cluster singles and doubles with a perturbational estimate of triple excitations [CCSD(T)] to determine the energetics. We find an entrance channel barrier of about 5 kcal/mol for the addition of vinylidene to acetylene, but no barriers above reactants for the reaction pathway leading to vinylacetylene. (C) 1995 American Institute of Physics. C1 ELORET INST,PALO ALTO,CA 94303. RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035, USA. NR 25 TC 8 Z9 8 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 22 PY 1995 VL 103 IS 12 BP 4975 EP 4979 DI 10.1063/1.470583 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA RU876 UT WOS:A1995RU87600018 ER PT J AU CHEN, D ZEBIAK, SE BUSALACCHI, AJ CANE, MA AF CHEN, D ZEBIAK, SE BUSALACCHI, AJ CANE, MA TI AN IMPROVED PROCEDURE FOR EL-NINO FORECASTING - IMPLICATIONS FOR PREDICTABILITY SO SCIENCE LA English DT Article ID OCEAN-ATMOSPHERE MODEL; SOUTHERN OSCILLATION; PREDICTION; SYSTEM; ENSO AB A coupled ocean-atmosphere data assimilation procedure yields improved forecasts of El Nino for the 1980s compared with previous forecasting procedures. As in earlier forecasts with the same model, no oceanic data were used, and only wind information was assimilated. The improvement is attributed to the explicit consideration of air-sea interaction in the initialization. These results suggest that El Nino is more predictable than previously estimated, but that predictability may vary on decadal or longer time scales. This procedure also eliminates the well-known spring barrier to El Nino prediction, which implies that it may not be intrinsic to the real climate system. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771. RP CHEN, D (reprint author), COLUMBIA UNIV,LAMONT DOHERTY EARTH OBSERV,PALISADES,NY 10964, USA. RI Cane, Mark/I-8086-2012; Chen, Dake/E-7082-2011 NR 22 TC 217 Z9 245 U1 3 U2 12 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 22 PY 1995 VL 269 IS 5231 BP 1699 EP 1702 DI 10.1126/science.269.5231.1699 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA RV948 UT WOS:A1995RV94800030 PM 17821639 ER PT J AU RYU, SO HWANG, SM RABINOWITZ, MJ AF RYU, SO HWANG, SM RABINOWITZ, MJ TI SHOCK-TUBE AND MODELING STUDY OF THE H+O-2=OH+O REACTION OVER A WIDE-RANGE OF COMPOSITION, PRESSURE, AND TEMPERATURE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POTENTIAL-ENERGY SURFACE; THERMAL RATE COEFFICIENT; TRAJECTORY CALCULATIONS; REACTION H+O2->OH+O; LASER PHOTOLYSIS; RATE CONSTANTS; MIXTURES; DYNAMICS; STATE; FLASH AB The rate coefficient of the reaction H + O-2 = OH + O (1) was determined using OH laser absorption spectroscopy behind reflected shock waves over the temperature range 1050-2500 K and the pressure range 0.7-4.0 atm. Eight mixtures and three stoichiometries were used. Two distinct and independent criteria were employed in the evaluation of k(1). Our recommended expression for k(1) is k(1) = 7.13 x 10(13) exp(-6957 K/T) cm(3) mol(-1) s(-1) with a statistical uncertainty of 6%. A critical review of recent evaluations of k(1) yields a consensus expression given by k(1) = 7.82 x 10(13) exp(-7105 K/T) cm(3) mol(-1) s(-1) over the temperature range 960-5300 K. We do not support a non-Arrhenius rate coefficient expression, nor do we find evidence of composition dependence upon the determination of k(1). C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. UNIV TOLEDO,DEPT CHEM ENGN,TOLEDO,OH 43606. NR 39 TC 34 Z9 34 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 21 PY 1995 VL 99 IS 38 BP 13984 EP 13991 DI 10.1021/j100038a033 PG 8 WC Chemistry, Physical SC Chemistry GA RW499 UT WOS:A1995RW49900033 ER PT J AU MCDERMID, IS WALSH, TD DESLIS, A WHITE, ML AF MCDERMID, IS WALSH, TD DESLIS, A WHITE, ML TI OPTICAL-SYSTEMS DESIGN FOR A STRATOSPHERIC LIDAR SYSTEM SO APPLIED OPTICS LA English DT Article ID OZONE; LASER AB The optical systems for the transmitter and receiver of a high-power lidar for stratospheric measurements. have been designed and analyzed. The system requirements and design results are presented and explained. An important and driving factor of this design was the requirement for a small image diameter in the plane of an optical chopper to allow the high-intensity lidar returns from the lower atmosphere to be shielded from the detection system. Some results relevant to the optical performance of the system are presented. The resulting system has been constructed and is now in operation at the Mauna Loa Observatory, Hawaii, and is making regular measurements of stratospheric ozone, temperature, and aerosol profiles. C1 CALTECH,JET PROPULS LAB,PASADENA,CA 92397. RP MCDERMID, IS (reprint author), CALTECH,TABLE MT FACIL,JET PROPULS LAB,POB 367,WRIGHTWOOD,CA 92397, USA. NR 14 TC 35 Z9 35 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 SEP 20 PY 1995 VL 34 IS 27 BP 6201 EP 6210 PG 10 WC Optics SC Optics GA RV160 UT WOS:A1995RV16000021 PM 21060463 ER PT J AU GAO, BC GREEN, RO AF GAO, BC GREEN, RO TI PRESENCE OF TERRESTRIAL ATMOSPHERIC GAS-ABSORPTION BANDS IN STANDARD EXTRATERRESTRIAL SOLAR IRRADIANCE CURVES IN THE NEAR-INFRARED SPECTRAL REGION SO APPLIED OPTICS LA English DT Article ID RADIATION; AVIRIS AB The solar irradiance curves compiled by Wehrli [Physikalisch-Meteorologisches Observatorium Publ. 615 (World Radiation Center, Davosdorf, Switzerland, 1985)] and by Neckel and Labs [Sol. Phys. 90, 205 (1984)] are widely used. These curves were obtained based on measurements of solar radiation from the ground and from aircraft platforms. Contaminations in these curves by atmospheric gaseous absorptions were inevitable. A technique for deriving the transmittance spectrum of the Sun's atmosphere from high-resolution (0.01 cm(-1)) solar occultation spectra measured above the Earth's atmosphere by the use of atmospheric trace molecule spectroscopy (ATMOS) aboard the space shuttle is described. The comparisons of the derived ATMOS solar transmittance spectrum with the two solar irradiance curves show that the curve derived by Wehrli contains many absorption features in the 2.0-2.5-mu m region that are not of solar origin, whereas the curve obtained by Neckel and Labs is completely devoid of weak solar absorption features that should be there. An Earth atmospheric oxygen band at 1.268 mu m and a water-vapor band near 0.94 mu m are likely present in the curve obtained by Wehrli. It is shown that the solar irradiance measurement errors in some narrow spectral intervals can be as large as 20%. An improved solar irradiance spectrum is formed by the incorporation of the solar transmittance spectrum derived from the ATMOS data into the solar irradiance spectrum from Neckel and Labs. The availability of a new solar spectrum from 50 to 50000 cm(-1) from the U.S. Air Force Phillips Laboratory is also discussed. (C) 1995 Optical Society of America. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 19 TC 9 Z9 9 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 SEP 20 PY 1995 VL 34 IS 27 BP 6263 EP 6268 PG 6 WC Optics SC Optics GA RV160 UT WOS:A1995RV16000027 PM 21060469 ER PT J AU COPI, CJ OLIVE, KA SCHRAMM, DN AF COPI, CJ OLIVE, KA SCHRAMM, DN TI LARGE-SCALE BARYON ISOCURVATURE INHOMOGENEITIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, THEORY; ELEMENTARY PARTICLES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID PRIMORDIAL NUCLEOSYNTHESIS; MODEL; UNIVERSE AB Big bang nucleosynthesis constraints on baryon isocurvature perturbations are determined. A simple model ignoring the effects of the scale of the perturbations is first reviewed. This model is then extended to address the claim that large amplitude perturbations will collapse, preventing their baryons from contributing to the observed baryon density. It is found that baryon isocurvature perturbations are constrained to provide only a slight increase in the density of baryons in the universe over the standard homogeneous model. In particular, it is found that models which rely on power laws and the random phase approximation for the power spectrum are incompatible with big bang nucleosynthesis unless an ad hoc, small-scale cutoff is included. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. RP COPI, CJ (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 29 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1995 VL 451 IS 1 BP 51 EP 59 DI 10.1086/176199 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RU168 UT WOS:A1995RU16800005 ER PT J AU WEAVER, KA NOUSEK, J YAQOOB, T HAYASHIDA, K MURAKAMI, S AF WEAVER, KA NOUSEK, J YAQOOB, T HAYASHIDA, K MURAKAMI, S TI AN ASCA X-RAY-SPECTRUM OF A PROTOTYPE BARE SEYFERT-1 NUCLEUS IN MCG-2-58-22 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (MCG -2-58-22); GALAXIES, NUCLEI; GALAXIES, SEYFERT; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; COLD MATTER; GALAXIES; LINE; EMISSION; REFLECTION; VARIABILITY; CATALOG; DISKS AB We present new X-ray spectral data for the Seyfert 1 galaxy MCG-2-58-22 obtained with the Advanced Satellite for Cosmology and Astrophysics (ASCA). The simplicity of the spectrum between 0.5 and 6 keV due to a lack of complex absorption or an appreciable contribution from Compton reflection allows a measure of the true continuum slope. Accounting for excess flux at similar to 1.0 keV, the intrinsic photon index is Gamma = 1.75 +/- 0.05. This is flatter than Gamma similar to 2.0 predicted by current pair/reflection models and thermal Comptonization models although no conclusions can be drawn until the distribution of intrinsic indices for Seyfert galaxies is known. The 6-10 keV data do not require or rule out Compton reflection. Assuming no reflection component is present in the ASCA bandpass, we confirm a strong Fe K alpha fluorescence line at 6.2 +/- 0.17 keV that is resolved with a velocity width of 31,000(-18,000)(+29,500) km s(-1) FWHM and an equivalent width (EW) of 340(-140)(+150) eV. Although the line width is consistent with arising in some portion of the broad line region, the EW is larger than similar to 50-150 eV expected for typical broad line region column densities of 10(22-23) cm(-2). Alternatively, we derive a self-consistent model of the X-ray spectrum if we assume that the predicted amount of Compton reflection from a face-on accretion disk is present. In this case, the Fe K line appears to be unresolved with an upper limit of 47,400 km s(-1) FWHM, while the EW of 230(-120)(+140) eV is less and consistent with production by the disk. The Fe K line parameters constrain the inclination of the disk to our line of sight to be about 40 degrees. We use the MCG-2-58-22 data to illustrate unique problems and limitations encountered in fitting ASCA spectra of Seyfert galaxies. In particular, how the continuum is modeled has profound effects on the parameters inferred for the Fe K alpha line. C1 PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,UNIVERSITY PK,PA 16802. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. OSAKA UNIV,TOYONAKA,OSAKA 560,JAPAN. OSAKA CITY UNIV,OSAKA 558,JAPAN. NR 36 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 SEP 20 PY 1995 VL 451 IS 1 BP 147 EP 155 DI 10.1086/176206 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RU168 UT WOS:A1995RU16800012 ER PT J AU REACH, WT DWEK, E FIXSEN, DJ HEWAGAMA, T MATHER, JC SHAFER, RA BANDAY, AJ BENNETT, CL CHENG, ES EPLEE, RE LEISAWITZ, D LUBIN, PM READ, SM ROSEN, LP SHUMAN, FGD SMOOT, GF SODROSKI, TJ WRIGHT, EL AF REACH, WT DWEK, E FIXSEN, DJ HEWAGAMA, T MATHER, JC SHAFER, RA BANDAY, AJ BENNETT, CL CHENG, ES EPLEE, RE LEISAWITZ, D LUBIN, PM READ, SM ROSEN, LP SHUMAN, FGD SMOOT, GF SODROSKI, TJ WRIGHT, EL TI FAR-INFRARED SPECTRAL OBSERVATIONS OF THE GALAXY BY COBE SO ASTROPHYSICAL JOURNAL LA English DT Article DE DIFFUSE RADIATION; DUST, EXTINCTION; INFRARED, ISM, CONTINUUM; RADIO CONTINUUM, ISM ID HIGH GALACTIC LATITUDES; COSMIC BACKGROUND-RADIATION; MOLECULAR CLOUDS; INTERSTELLAR GRAINS; OPTICAL-PROPERTIES; MILKY-WAY; DUST; EMISSION; ANISOTROPY; SCALE AB We derive Galactic continuum spectra from 5-96 cm(-1) from COBE/FIRAS observations. The spectra are dominated by warm dust emission, which may be fitted with a single temperature in the range 16-21 K (for nu(2) emissivity) along each line of sight. Dust heated by the attenuated radiation field in molecular clouds gives rise to intermediate-temperature (10-14 K) emission in the inner Galaxy only. A widespread, very cold component (4-7 K) with optical depth that is spatially correlated with the warm component is also detected. The cold component is unlikely to be due to very cold dust shielded from starlight because it is present at high latitude. We consider hypotheses that the cold component is due to enhanced submillimeter emissivity of the dust that gives rise to the warm component, or that it may be due to very small, large, or fractal particles. Lack of substantial power above the emission from warm dust places strong constraints on the amount of cold gas in the Galaxy. The microwave sky brightness due to interstellar dust is dominated by the cold component, and its angular variation could limit our ability to discern primordial fluctuations in the cosmic microwave background radiation. C1 APPL RES CORP,GREENBELT,MD 20771. HUGHES STX,GREENBELT,MD 20771. GEN SCI CORP,GREENBELT,MD 20771. UNIV CALIF SANTA BARBARA,DEPT PHYS,SANTA BARBARA,CA 93106. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP REACH, WT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 685,GREENBELT,MD 20771, USA. RI Reach, William/C-4710-2008; Hewagama, T/C-8488-2012; Dwek, Eli/C-3995-2012; OI Reach, William/0000-0001-8362-4094 NR 61 TC 214 Z9 214 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 SEP 20 PY 1995 VL 451 IS 1 BP 188 EP 199 DI 10.1086/176210 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RU168 UT WOS:A1995RU16800016 ER PT J AU SOBIESKI, PW BLIVEN, LF AF SOBIESKI, PW BLIVEN, LF TI SCATTEROMETRY OF A DROP IMPACT ON A SALT-WATER SURFACE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Note ID RAIN AB Experiments of scatterometry at 13.5 and 36 GHz, VV polarization have been conducted in the new Rain-Sea Interaction Facility at NASA Wallops. Radar backscatterings of rain drop impacts on a salt water surface have been measured with an incidence angle of 30 degrees for various dropsizes at terminal fall velocity. Results for 2.8 mm drops are presented. Surface features were imaged by an ultra high speed digital camera synchronized with the radar data acquisition. Backscattered powers from crowns, craters, stalks and ringwaves were measured. These measurements confirm that for the scatterometric configuration under consideration, ringwaves are the dominant scattering contribution and that stalks scattering is much smaller but not negligible. C1 NASA,GODDARD SPACE FLIGHT CTR,WFF,HYDROSPHER PROC LAB,WALLOPS ISL,VA 23337. RP SOBIESKI, PW (reprint author), UNIV CATHOLIQUE LOUVAIN,B-1348 LOUVAIN,BELGIUM. RI bliven, francis/E-1450-2012 NR 17 TC 18 Z9 18 U1 0 U2 1 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD SEP 20 PY 1995 VL 16 IS 14 BP 2721 EP 2726 PG 6 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA RX630 UT WOS:A1995RX63000014 ER PT J AU LEVINE, DM WILLETT, JC AF LEVINE, DM WILLETT, JC TI THE INFLUENCE OF CHANNEL GEOMETRY ON THE FINE-SCALE STRUCTURE OF RADIATION FROM LIGHTNING RETURN STROKES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID FIELDS; MODEL; CURRENTS AB Evidence is presented indicating that channel geometry is a factor in determining the shape of the electric field waveforms radiated by subsequent return strokes in cloud-to-ground lightning. The data consist of 61 subsequent return strokes in both triggered flashes and natural lightning recorded at the NASA Kennedy Space Center during the summer of 1987. In the case of the triggered flashes, the data include the electric field change, the current at the channel base, and video images of the channel. Video images were obtained for about half of the natural flashes. The fine scale structure of the electric field changes radiated by these strokes has been compared during the first 10 mu s. In cases where unambiguous identification of the channel could be made from the video recordings, this fine scale structure is similar for return strokes in the same channel and differs. significantly for return strokes in different channels. This is true for both natural and triggered flashes. On the other hand, the current waveforms measured at the channel base (available for the triggered flashes) are similar in shape for all strokes, regardless of the channel. Similar results were also obtained for the natural flashes without video images, in which case strokes from the same flash exhibit a greater similarity than do strokes from different flashes (and therefore different channels). C1 PHILLIPS LAB, GEOPHYS DIRECTORATE, BEDFORD, MA 01731 USA. RP LEVINE, DM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 975, GREENBELT, MD 20771 USA. NR 26 TC 9 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1995 VL 100 IS D9 BP 18629 EP 18638 DI 10.1029/95JD01282 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RV887 UT WOS:A1995RV88700001 ER PT J AU TEGEN, I FUNG, I AF TEGEN, I FUNG, I TI CONTRIBUTION TO THE ATMOSPHERIC MINERAL AEROSOL LOAD FROM LAND-SURFACE MODIFICATION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; WIND EROSION; SIZE DISTRIBUTIONS; UNITED-STATES; DESERT DUST; VARIABILITY; SOILS; SIMULATIONS; VEGETATION; BIOSPHERE AB An estimation of the contribution of mineral dust from disturbed soils (i.e., soils affected by human activity and/or climate variability) to the total atmospheric mineral aerosol load is presented. A three-dimensional atmospheric dust transport model was used to simulate the distribution of dust optical thickness in response to individual dust sources, which include natural soils known to have been affected by the Saharan/Sahelian boundary shift, cultivation, deforestation, and wind erosion. The distributions extracted from advanced very high resolution radiometer (AVHRR) optical thickness retrievals were used to constrain likely source combinations. The results indicate that observed features Like the seasonal shift of maximum optical thickness caused by Saharan dust over the Atlantic ocean are best reproduced if disturbed sources contribute 30-50% of the total atmospheric dust loading. C1 COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10025 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. NR 43 TC 362 Z9 370 U1 4 U2 24 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1995 VL 100 IS D9 BP 18707 EP 18726 DI 10.1029/95JD02051 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RV887 UT WOS:A1995RV88700007 ER PT J AU ZHANG, RY LEU, MT KEYSER, LF AF ZHANG, RY LEU, MT KEYSER, LF TI SULFURIC-ACID MONOHYDRATE - FORMATION AND HETEROGENEOUS CHEMISTRY IN THE STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLOUD FORMATION; PHYSICAL-CHEMISTRY; OZONE HOLE; DROPLETS; SYSTEM; WINTER; NUCLEATION; REACTORS; AEROSOLS; GROWTH AB We have investigated some thermodynamic properties (i.e., freezing/melting points) and heterogeneous chemistry of sulfuric acid monohydrate (SAM, H2SO4 . H2O), using a fast flow reactor coupled to a quadrupole mass spectrometer. The freezing point observations of thin liquid sulfuric acid films show that for acid contents between 75 and 85 wt % the monohydrate crystallizes readily at temperatures between 220 and 240 K on a glass substrate. Once formed, SAM can be thermodynamically stable in the H2O partial pressure range of (1-4) x 10(-4) torr and in the temperature range of 220-240 K. For a constant H2O partial pressure, lowering the temperature causes SAM to melt when the temperature and water partial pressure conditions are out of its stability regime. The reaction probability measurements indicate that the hydrolysis of N2O5 is significantly suppressed owing to the formation of crystalline SAM: The reaction probability on water-rich SAM (with higher relative humidity, or RH) is of the order of 10(-3) at 210 K and decreases by more than an order of magnitude for the acid-rich form (with lower RH). The hydrolysis rate of CIONO2 on water-rich SAM is even smaller, of the order of 10(-4) at 195 K. These reported values on crystalline SAM are much smaller than those on liquid solutions. No enhancement of these reactions is observed in the presence of HCl vapor at the stratospheric concentrations. In addition, Brunauer, Emmett, and Teller analysis of gas adsorption isotherms and photomicrography have been performed to characterize the surface roughness and porosities of the SAM substrate. The results suggest the possible formation of SAM in some regions of the middle- or low-latitude stratosphere and, consequently, much slower heterogeneous reactions on the frozen aerosols. RP ZHANG, RY (reprint author), CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, MAIL STOP 183-901, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Zhang, Renyi/A-2942-2011 NR 43 TC 20 Z9 20 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1995 VL 100 IS D9 BP 18845 EP 18854 DI 10.1029/95JD01876 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RV887 UT WOS:A1995RV88700019 ER PT J AU WEN, GY FREDERICK, JE HILSENRATH, E AF WEN, GY FREDERICK, JE HILSENRATH, E TI PINATUBO AEROSOLS AND THE BEHAVIOR OF OZONE INFERRED FROM BACKSCATTER ULTRAVIOLET MEASUREMENTS ON THE SPACE-SHUTTLE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MT-PINATUBO; LIDAR OBSERVATIONS; TROPICAL OZONE; VOLCANIC PLUME; ERUPTION; TEMPERATURE; CLOUD AB Backscattered radiation measurements from the shuttle solar backscatter ultraviolet spectral radiometer were used to examine aerosol optical properties and a possible ozone decrease in the tropical region after the eruption of Mt. Pinatubo. Observations made on two flights separated in time by 10 months show that backscattered ultraviolet radiation was greatly enhanced after the eruption as compared to the earlier measurements. The enhancements in backscattered radiation exhibit a special wavelength dependent signature. The peak percentage enhancement was found near 302 nm for solar zenith angles greater than 20 degrees, corresponding to the latitude band 14 degrees S-14 degrees N. Radiative transfer calculations indicate that the wavelength dependence of the enhancement is consistent with an ozone decrease in the altitude region of the Pinatubo aerosol clouds. The Pinatubo aerosol optical depth was found to vary in the range 0.07-0.53 in the ultraviolet region at tropical latitudes. Furthermore, a 16-22 Dobson unit decrease of ozone in the altitude region occupied by the aerosol cloud is consistent with the spectral dependence of the enhanced backscattered radiance. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. UNIV CHICAGO, DEPT GEOPHYS SCI, CHICAGO, IL 60637 USA. NR 36 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1995 VL 100 IS D9 BP 18855 EP 18862 DI 10.1029/95JD01839 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RV887 UT WOS:A1995RV88700020 ER PT J AU SUTTER, JK JOBE, JM CRANE, EA AF SUTTER, JK JOBE, JM CRANE, EA TI STATISTICAL DESIGN IN ISOTHERMAL AGING OF POLYIMIDE RESINS SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article AB Recent developments in research on polyimides for high temperature applications have led to the synthesis of many new polymers. Among the criteria that determines their thermal oxidative stability, isothermal aging is one of the most important. Isothermal aging studies require that many experimental factors are controlled to provide accurate results. In this article we describe a statistical plan that compares the isothermal stability of several polyimide resins, while minimizing the variations inherent in high-temperature aging studies. (C) 1995 John Wiley and Sons, Inc. C1 JOHN CARROLL UNIV,CLEVELAND,OH 44118. RP SUTTER, JK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 11 TC 6 Z9 7 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD SEP 19 PY 1995 VL 57 IS 12 BP 1491 EP 1499 DI 10.1002/app.1995.070571209 PG 9 WC Polymer Science SC Polymer Science GA RP410 UT WOS:A1995RP41000009 ER PT J AU BENJAMIN, I WILSON, MA POHORILLE, A NATHANSON, GM AF BENJAMIN, I WILSON, MA POHORILLE, A NATHANSON, GM TI SCATTERING OF WATER FROM THE GLYCEROL LIQUID-VACUUM INTERFACE SO CHEMICAL PHYSICS LETTERS LA English DT Article ID SURFACES; COLLISIONS; MOLECULES; DYNAMICS AB Molecular dynamics calculations of the scattering of D2O from the glycerol surface at different collision energies are reported. The results for the trapping probabilities and energy transfer are in good agreement with experiments. The calculations demonstrate that the strong attractive forces between these two strongly hydrogen bonding molecules have only a minor effect on the initial collision dynamics. The trapping probability is influenced to a significant extent by the repulsive hard sphere-like initial encounter with the corrugated surface and, only at a later stage, by the efficiency of energy flow in the multiple interactions between the water and the surface molecules. C1 UNIV CALIF SAN FRANCISCO,DEPT PHARMACEUT CHEM,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV WISCONSIN,DEPT CHEM,MADISON,WI 53706. RP BENJAMIN, I (reprint author), UNIV CALIF SANTA CRUZ,DEPT CHEM,SANTA CRUZ,CA 95064, USA. FU NCI NIH HHS [NCA 2-792] NR 20 TC 37 Z9 37 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD SEP 15 PY 1995 VL 243 IS 3-4 BP 222 EP 228 DI 10.1016/0009-2614(95)00857-Z PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA RV057 UT WOS:A1995RV05700006 PM 11540427 ER PT J AU GAZIS, PR AF GAZIS, PR TI LIMITS ON DECELERATION AND ASYMMETRY OF SOLAR-WIND SPEED SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERSTELLAR PICKUP IONS AB It has been suggested by Richardson et al. [1995] that the solar wind shows signs of deceleration due to mass-loading by interstellar pickup ions. They based their conclusion on observations from the Voyager 2 and IMP 8 spacecraft. Observations from the Pioneer Venus Orbiter (PVO), IMP 8, Voyager 2, and Pioneer 10 spacecraft are compared to look for this deceleration. While these comparisons suggest the possibility of deceleration at Voyager 2, the magnitude of this deceleration appears to be significantly less than the deceleration reported by Richardson et al. [1995]. Some of this difference could be explained by a north-south asymmetry in solar wind speed during solar cycle 21. The implications of these results are discussed, along with possibilities for further investigations. RP GAZIS, PR (reprint author), NASA,AMES RES CTR,SAN JOSE STATE UNIV FDN,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 12 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1995 VL 22 IS 18 BP 2441 EP 2444 DI 10.1029/95GL02469 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100001 ER PT J AU COMFORT, RH CRAVEN, PD RICHARDS, PG AF COMFORT, RH CRAVEN, PD RICHARDS, PG TI A MODIFIED THERMAL-CONDUCTIVITY FOR LOW-DENSITY PLASMA MAGNETIC-FLUX TUBES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IONOSPHERE AB In response to inconsistencies which have arisen in results from a hydrodynamic model in simulations of high ion temperatures (1-2 eV) observed in low density, outer plasmasphere flux tubes, we postulate a reduced thermal conductivity co-efficient in which only particles in the loss cone of the quasi-collisionless plasma contribute to the thermal conduction. Other particles are assumed to magnetically mirror before they reach the topside ionosphere and therefore not to remove thermal energy from the plasmasphere. This concept is used to formulate a mathematically, simple, but physically limiting model for a modified thermal conductivity coefficient. When this modified coefficient is employed in the hydrodynamic model in a case study, the inconsistencies between simulation results and observations are largely resolved. The high simulated ion temperatures are achieved with significantly less heat input, and result in substantially lower ion temperatures in the topside ionosphere. We suggest that this mechanism may be operative under the limited low density, refilling conditions in which high ion temperatures are observed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP COMFORT, RH (reprint author), UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899, USA. NR 11 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 SEP 15 PY 1995 VL 22 IS 18 BP 2457 EP 2460 DI 10.1029/95GL02408 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100005 ER PT J AU LEHMACHER, G LUBKEN, FJ AF LEHMACHER, G LUBKEN, FJ TI SIMULTANEOUS OBSERVATION OF CONVECTIVE ADJUSTMENT AND TURBULENCE GENERATION IN THE MESOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER THERMOSPHERE; FLUCTUATIONS; TEMPERATURE AB We present simultaneous in situ measurements of turbulence and temperature in the midlatitude mesosphere obtained as part of the DYANA campaign on March 13, 1990 at Biscarrosse, France (44 degrees N, 1 degrees W). In this study, we have extended the temperature measurements of our rocket borne ionization gauge down to 70 km and directly compared them to the small scale density fluctuations. Between 74 and 81 km we observed a unique, sawtooth shape layer in the temperature profile with a slightly superadiabatic lapse rate. In the same region, strong turbulent density fluctuations were present. We interpret these observations as convective adjustment and associated turbulence. C1 UNIV BONN,INST PHYS,D-53115 BONN,GERMANY. RP LEHMACHER, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Lehmacher, Gerald/F-2653-2013 NR 17 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1995 VL 22 IS 18 BP 2477 EP 2480 DI 10.1029/95GL02351 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100010 ER PT J AU CHANDRA, S LEAN, JL WHITE, OR PRINZ, DK ROTTMAN, GJ BRUECKNER, GE AF CHANDRA, S LEAN, JL WHITE, OR PRINZ, DK ROTTMAN, GJ BRUECKNER, GE TI SOLAR UV IRRADIANCE VARIABILITY DURING THE DECLINING PHASE OF THE SOLAR-CYCLE-22 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LYMAN ALPHA FLUX; ULTRAVIOLET IRRADIANCE; MONITOR AB The SUSIM (Solar Ultraviolet Spectral Irradiance Monitor) and the SOLSTICE (Solar Stellar Irradiance Comparison Experiment) instruments on the UARS (Upper Atmosphere Research Satellite) have been making continuous measurements of the solar UV flux in the spectral range 115-420 nm since October 1991. This period, characterized as the declining phase of solar cycle 22, shows a transition from near maximum to near minimum solar activity levels. During this period, the solar UV flux at Lyman alpha decreased by about 45% from a mean solar maximum value of about 9 mW/m(2), and the integrated solar flux between 200-205 nm decreased by about 5 % from a mean value of about 47 mW/m(2). Using the MgII index as a proxy of solar UV irradiance variability, it is shown that the temporal relationship of the UARS solar Lyman alpha irradiance and the MgII index during solar cycle 22 is significantly different than during solar cycle 21, inferred from the SME (Solar Mesosphere Explorer) Lyman alpha measurements. Moreover, during solar cycle 22, the scale factor for solar Lyman alpha irradiance (% change for 1% change in MgII index) is about 1.5 times larger for long term changes than for changes over the time scale of a solar rotation. Unlike Lyman alpha, the scale factor for the UV flux in the 200-205 nm wavelength range, is close to unity both for the rotational and longer time scales. The spectral dependence of the two scale factors in the 120-200 nm range is derived from the SOLSTICE data which may be used with the MgII index to estimate the UV irradiance variability in this spectral range for both short and long time scales. C1 USN,RES LAB,WASHINGTON,DC 20375. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. OI Lean, Judith/0000-0002-0087-9639 NR 13 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1995 VL 22 IS 18 BP 2481 EP 2484 DI 10.1029/95GL02476 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100011 ER PT J AU NEWMAN, PA SCHOEBERL, MR AF NEWMAN, PA SCHOEBERL, MR TI A REINTERPRETATION OF THE DATA FROM THE NASA STRATOSPHERE TROPOSPHERE EXCHANGE PROJECT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WAVES; TRANSPORT AB Data obtained during the NASA Stratosphere Troposphere Exchange Project (STEP) Mid-Latitude Field Experiment displayed laminae of ozone, water, and condensation nuclei in the stratosphere in association with a mid-latitude stratosphere-troposphere folding event. Danielsen et al. (1991) constructed cross sections of these observations, and interpreted these quasi-horizontal laminae as evidence of ultra-low frequency gravity waves. We use a new technique to show that these laminae could have resulted from differential advection, rather than transport by ultra-low frequency gravity waves. This new technique uses reverse domain filling back trajectories on multiple isentropic surfaces. in conjunction with modified potential vorticity to reveal the qualitative details of the constituent laminae. RP NEWMAN, PA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 19 TC 41 Z9 42 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1995 VL 22 IS 18 BP 2501 EP 2504 DI 10.1029/95GL02220 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100016 ER PT J AU GOLDSTEIN, R AF GOLDSTEIN, R TI ATMOSPHERIC LIMITATIONS TO REPEAT-TRACK RADAR INTERFEROMETRY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB In its recent radar imaging mission, the Shuttle Imaging Radar satellite (SIR-C) devoted three days to repeat-track interferometry. We have analyzed the data from a test site in the Mojave desert of California. Although good topography (+/-10 m on 21 m postings) was obtained, most of the error was caused by turbulent water vapor in the lower atmosphere. Spatial structure of 6 km and all smaller sizes was observed. The RMS, one-way time delay was found to be 0.24 cm. Essentially identical results were obtained at two wavelengths, 24 and 5.7 cm. RP GOLDSTEIN, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 182 Z9 206 U1 2 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 SEP 15 PY 1995 VL 22 IS 18 BP 2517 EP 2520 DI 10.1029/95GL02475 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RW251 UT WOS:A1995RW25100020 ER PT J AU MENA, RA SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA BIBYK, SB RINGEL, SA AF MENA, RA SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA BIBYK, SB RINGEL, SA TI SUBBAND QUANTUM SCATTERING TIMES FOR ALGAAS/GAAS OBTAINED USING DIGITAL FILTERING SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID MOBILITY; TRANSPORT; SYSTEMS AB In this study we investigate both the transport and quantum scattering times as a function of the carrier concentration for a modulation doped Al0.3Ga0.7As/GaAs structure. Carriers in the well are generated as a result of the persistent photoconductivity effect. When more than one subband becomes populated, digital filtering is used to separate the components for each of the excited subbands. We find that the quantum scattering time for the ground subband increases initially as the carrier concentration is increased. However, once the second subband becomes populated, the ground subband scattering time begins to decrease. The quantum scattering time for the excited subband is also observed to decrease as the concentration is increased. Our results are consistent with the theoretical results by A. Isihara and L, Smrcka [J. Phys, C 19, 6777 (1986)]. Finally, from the ratio of the transport and quantum scattering times, it is seen that the transport in the well becomes more isotropic as the concentration is increased. (C) 1995 American Institute of Physics. C1 OHIO STATE UNIV, DEPT ELECT ENGN, COLUMBUS, OH 43210 USA. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 11 TC 4 Z9 4 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-8979 EI 1089-7550 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 1995 VL 78 IS 6 BP 3940 EP 3944 DI 10.1063/1.359913 PG 5 WC Physics, Applied SC Physics GA RU953 UT WOS:A1995RU95300056 ER PT J AU WANG, LP KOBLINSKY, CJ AF WANG, LP KOBLINSKY, CJ TI LOW-FREQUENCY VARIABILITY IN REGIONS OF THE KUROSHIO EXTENSION AND THE GULF-STREAM SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SURFACE TRANSPORT; GEOSAT ALTIMETER; ROSSBY WAVES; INTERANNUAL VARIABILITY; SEASONAL VARIABILITY; SATELLITE ALTIMETRY; TROPICAL PACIFIC; KINETIC-ENERGY; NORTH-ATLANTIC; OCEAN AB Using sea, surface height data collected by the TOPES/POSEIDON altimeter, we studied the low-frequency variability in the Kuroshio Extension and Gulf Stream. The most significant signals are the basin-wide background seasonal cycle and low-frequency wave activity generated over major bottom bathymetry and subsequent westward propagation in both regions. The spatial structures of the seasonal cycle in the two regions are quite different. In the Kuroshio Extension the seasonal cycle has a northeast-southwest orientation and lies closer to the western boundary, whereas it has an east-west orientation and lies more offshore in the Gulf Stream. The close relationship between the low-frequency wave activity and major bottom bathymetry features is discussed through both empirical orthogonal functional (EOF) analysis and calculation of eddy kinetic energy and Reynolds stress. The spatial structures of these eddy statistics are fundamentally different from those of high-frequency mesoscale variability. They ape not in the proximity of maximum time-mean flow, but rather, they lie mostly to the west of major bottom bathymetry. The close association of the clusters of local maximum eddy properties with major bottom topographic features in both regions, wave generation over the major bottom topographic features and subsequent westward propagation, and difference of the eddy statistics from that associated with high-frequency mesoscale variability all suggest that unlike in the case with high-frequency mesoscale variability generation in which internal dynamics of the background mean flow such as nonlinear instability plays a fundamental role, external forcing through bottom topography must play a fundamental role im generating the low-frequency wave activity. RP WANG, LP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 971,GREENBELT,MD 20771, USA. NR 41 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1995 VL 100 IS C9 BP 18313 EP 18331 DI 10.1029/95JC01832 PG 19 WC Oceanography SC Oceanography GA RV579 UT WOS:A1995RV57900005 ER PT J AU CHOI, SR SALEM, JA AF CHOI, SR SALEM, JA TI DYNAMIC, STATIC AND CYCLIC FATIGUE OF ALUMINA WITH INDENTATION-INDUCED FLAWS SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article ID CRACK-PROPAGATION; BEHAVIOR C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP CHOI, SR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 6 TC 4 Z9 4 U1 1 U2 3 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD SEP 15 PY 1995 VL 14 IS 18 BP 1286 EP 1288 DI 10.1007/BF01262269 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA RW347 UT WOS:A1995RW34700012 ER PT J AU CHOU, SH AF CHOU, SH TI WAVE-NUMBER SELECTION AND HYSTERESIS IN NONLINEAR BAROCLINIC FLOWS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID SUPERCRITICAL DYNAMICS; WEATHER REGIMES; DISTURBANCES; INSTABILITY AB Wavenumber transition and hysteresis in a highly unstable baroclinic flow are investigated using a high-resolution spectral numerical model. As the flow becomes more supercritical, the dominant wave gradually shifts from the most unstable wave predicted by the linear theory to a longer wave with a larger time-averaged amplitude, while the rectified mean flow attains a stronger shear at the center of the channel. The numerical results display a complex hysteresis behavior, which occurs not only between the states of different dominant wavenumbers, but also between the states of identical dominant wavenumber but of different dynamic characteristics. In a certain parameter range three stable states, each with different dominant wavenumber, are possible, and in another parameter range four stable states are possible, among them three stable states with an identical dominant wave. The numerical results suggest that a multiple weather regime exists even without external forcing in which the flow aperiodically varies between two distinct behaviors. The effects of stable higher harmonics are assessed and it is found that their presence contributes not only to the better approximation of the model solutions but also to the selection of the final equilibrium state, due to the chaotic nature of the initial transient period. RP CHOU, SH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SYST SCI,ES42,HUNTSVILLE,AL 35812, USA. NR 16 TC 2 Z9 2 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 SEP 15 PY 1995 VL 52 IS 18 BP 3236 EP 3246 DI 10.1175/1520-0469(1995)052<3236:WSAHIN>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RU789 UT WOS:A1995RU78900003 ER PT J AU GOLDSTEIN, ME AF GOLDSTEIN, ME TI THE ROLE OF NONLINEAR CRITICAL LAYERS IN BOUNDARY-LAYER-TRANSITION SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article ID FREE SHEAR-LAYER; TOLLMIEN-SCHLICHTING WAVES; RESONANT-TRIAD; OBLIQUE WAVES; STOKES LAYER; UPPER BRANCH; EVOLUTION; DISTURBANCES; INSTABILITY; STABILITY AB Asymptotic methods are used to describe the nonlinear self-interaction between pairs of oblique instability modes that eventually develops when initially linear spatially growing instability waves evolve downstream in nominally two-dimensional laminar boundary layers. The first nonlinear reaction takes place locally within a so-called 'critical layer', with the flow outside this layer consisting of a locally parallel mean flow plus a pair of oblique instability waves - which may or may not be accompanied by an associated plane wave. The amplitudes of these waves, which are completely determined by nonlinear effects within the critical layer, satisfy either a single integro-differential equation or a pair of integro-differential equations with quadratic to quartic-type nonlinearities. The physical implications of these equations are discussed. RP GOLDSTEIN, ME (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 59 TC 17 Z9 18 U1 1 U2 3 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T R SOC A JI Philos. Trans. R. Soc. A-Math. Phys. Eng. Sci. PD SEP 15 PY 1995 VL 352 IS 1700 BP 425 EP 442 DI 10.1098/rsta.1995.0080 PG 18 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA RY001 UT WOS:A1995RY00100003 ER PT J AU YURTSEVER, U AF YURTSEVER, U TI GEOMETRY OF CHAOS IN THE 2-CENTER PROBLEM IN GENERAL-RELATIVITY SO PHYSICAL REVIEW D LA English DT Article ID BLACK-HOLES; PERIODIC-ORBITS AB The now-famous Majumdar-Papapetrou exact solution of the Einstein-Maxwell equations describes, in general, N static, maximally charged black holes balanced under mutual gravitational and electrostatic interaction. When N = 2, this solution defines the two-black-hole spacetime, and the relativistic two-center problem is the problem of geodesic motion on this static background. Contopoulos and a number of other workers have recently discovered through numerical experiments that, in contrast with the Newtonian two-center problem, where the dynamics is completely integrable, relativistic null-geodesic motion on the two-black-hole spacetime exhibits chaotic behavior. Here I identify the geometric sources of this chaotic dynamics by first reducing the problem to that of geodesic motion on a negatively curved (Riemannian) surface. C1 CALTECH,PASADENA,CA 91125. RP YURTSEVER, U (reprint author), CALTECH,JET PROP LAB 169-327,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 25 Z9 25 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1995 VL 52 IS 6 BP 3176 EP 3183 DI 10.1103/PhysRevD.52.3176 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA RV636 UT WOS:A1995RV63600004 ER PT J AU STEBBINS, A CALDWELL, RR AF STEBBINS, A CALDWELL, RR TI NO VERY LARGE-SCALE STRUCTURE IN AN OPEN UNIVERSE SO PHYSICAL REVIEW D LA English DT Article AB We study the effects of negative spatial curvature on the statistics of inhomogeneities in open cosmological models. In particular we examine the suppression of large-separation correlations in density and gravitational potential fluctuations and the resulting suppression of large-angle correlations in the anisotropy of the microwave background radiation. We obtain an expression which gives the minimum amount of suppression of correlations for any statistical distribution described by a ''power spectrum.'' This minimum suppression requires that the correlations fall off exponentially above the curvature scale. To the extent that the observed correlations in the temperature anisotropy extend to large angular scales, one can set a lower bound to the radius of curvature and hence on Omega(0). A preliminary analysis suggests that this bound is, in practice, extremely weak, and less stringent than other cosmological tests of curvature. C1 UNIV CAMBRIDGE,DEPT APPL MATH & THEORET PHYS,CAMBRIDGE CB3 9EW,ENGLAND. RP STEBBINS, A (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,MS 209,POB 500,BATAVIA,IL 60510, USA. OI Caldwell, Robert/0000-0001-7490-7463 NR 18 TC 9 Z9 9 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD SEP 15 PY 1995 VL 52 IS 6 BP 3248 EP 3264 DI 10.1103/PhysRevD.52.3248 PG 17 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA RV636 UT WOS:A1995RV63600010 ER PT J AU UNAL, O ECKEL, AJ LAABS, FC AF UNAL, O ECKEL, AJ LAABS, FC TI THE 1400-DEGREES-C-OXIDATION EFFECT ON MICROSTRUCTURE, STRENGTH AND CYCLIC LIFE OF SIC/SIC COMPOSITES SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 AMES LAB,DIV MET & CERAM,AMES,IA 50010. NASA,LEWIS RES CTR,DIV MAT,CLEVELAND,OH 44135. NR 10 TC 2 Z9 2 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD SEP 15 PY 1995 VL 33 IS 6 BP 983 EP 988 DI 10.1016/0956-716X(95)00309-J PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA RR228 UT WOS:A1995RR22800021 ER PT J AU RAO, KBS CASTELLI, MG ELLIS, JR AF RAO, KBS CASTELLI, MG ELLIS, JR TI ON THE LOW-CYCLE FATIGUE DEFORMATION OF HAYNES-188 SUPERALLOY IN THE DYNAMIC STRAIN-AGING REGIME SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID STACKING-FAULT ENERGY; SLIP; TEMPERATURE; MECHANISMS; ALLOYS C1 NYMA INC,NASA,LEWIS RES CTR GRP,CLEVELAND,OH 44135. RP RAO, KBS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 25 TC 29 Z9 29 U1 4 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD SEP 15 PY 1995 VL 33 IS 6 BP 1005 EP 1012 DI 10.1016/0956-716X(95)00320-U PG 8 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA RR228 UT WOS:A1995RR22800024 ER PT J AU WARNER, RD WASILEWSKI, PJ AF WARNER, RD WASILEWSKI, PJ TI MAGNETIC PETROLOGY OF LOWER CRUST AND UPPER-MANTLE XENOLITHS FROM MCMURDO SOUND, ANTARCTICA SO TECTONOPHYSICS LA English DT Article ID MAGSAT DATA; ANOMALIES; SUSCEPTIBILITY; LITHOSPHERE; PERSPECTIVE; BOUNDARY; ROCKS; RIFT AB A suite of xenoliths was collected from Ross Island in the McMurdo Sound area, Antarctica. The purpose of the study of these xenoliths was to determine the level of magnetization in lower crust and upper mantle lithologies and to discover the mineralogical basis for the magnetization records. The majority of xenoliths are pyroxene granulites of mafic composition; a few hornblendites occur, and upper mantle dunites are fairly common. The primary mineral assemblage of the pyroxene granulites is plagioclase + calcic pyroxene +/- orthopyroxene +/- olivine +/- ilmenite; mineral stability relations together with two-pyroxene geothermometry indicate derivation from, depths of 12 to 20 km. The pyroxene granulites show evidence of partial melting, presumably related to incorporation of the xenoliths in the host basaltic magmas. Prior to their ascent to the surface, many underwent metamorphic reactions producing secondary hornblende, biotite and titanomagnetite. On the whole, the Antarctic xenoliths are weakly magnetic, but a few ilmenite-rich pyroxene granulites have MIM > 40 X 10(-4) A m(2)/kg and Xo > 0.005 SI units. The latter contain 1-3% titanomagnetite, which is largely of secondary origin and occurs chiefly as tiny quench crystals concentrated in fine-grained melt areas and as coronas about primary ilmenite crystals. Oxidation of Fe-Ti oxides is pervasive as revealed by the frequent occurrence of wispy ferrian rutile lamellae in ilmenite and trellis-type ilmenite oxyexsolution lamellae in titanomagnetite. The oxidized nature of the samples is further indicated by the presence of hematite and pseudobrookite-titanohematite intergrowths. The oxidation has caused a shift in titanomagnetite toward Fe3O4-rich compositions and in ilmenite toward higher Fe2O3. As a consequence, the pyroxene granulites exhibit thermal unblocking in the vicinity of 500-570 degrees C. The high geothermal gradient, characteristic of a continental rift setting, argues for about 12 km of magnetic crust before the Curie point is exceeded. The primary oxide of consequence in this rift environment appears to be ilmenite, which may be a common lower crust oxide mineral in this type of tectonic setting. No evidence was found in thermomagnetic experiments or in petrographic studies to suggest the presence of native iron. The secondary origin of much of the titanomagnetite now present suggests that unaltered, in situ granulite lower crust in this area would be weakly magnetic even in a situation where the geothermal gradient was lower or where a tectonic reconfiguration would render the lower crust above the Curie geotherm. The strongest magnetizations reside in Cenozoic volcanic cap rocks, and these are expected to be the major source of local magnetic anomalies in the area. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP WARNER, RD (reprint author), CLEMSON UNIV,DEPT EARTH SCI,CLEMSON,SC 29634, USA. NR 37 TC 15 Z9 16 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD SEP 15 PY 1995 VL 249 IS 1-2 BP 69 EP 92 DI 10.1016/0040-1951(95)00014-E PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA TB286 UT WOS:A1995TB28600005 ER PT J AU FUJII, K SRIVASTAVA, SK AF FUJII, K SRIVASTAVA, SK TI A MEASUREMENT OF THE ELECTRON-IMPACT IONIZATION CROSS-SECTION OF SODIUM SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Letter ID SCATTERING; ATOMS AB A novel experimental technique is used to determine accurate relative values of ionization cross sections as a function of electron impact for Na. The ionization efficiency curves are then compared with the recent convergent close-coupling (ccc) calculations of Bray which have been very successful in predicting ionization cross sections of atomic hydrogen. The present results are also compared with the plane-wave Born approximation calculations of McGuire which are expected to be accurate at high electron-impact energies (> 500 eV). These comparisons show that at electron-impact energies greater than about 60 eV, inner-shell ionization plays an important role in Na. RP FUJII, K (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 16 Z9 16 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD SEP 14 PY 1995 VL 28 IS 17 BP L559 EP L563 DI 10.1088/0953-4075/28/17/007 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA RW629 UT WOS:A1995RW62900007 ER PT J AU CHUI, TCP SHAO, M REDDING, D GURSEL, Y BODEN, A AF CHUI, TCP SHAO, M REDDING, D GURSEL, Y BODEN, A TI MIRROR BIREFRINGENCE IN A FABRY-PEROT CAVITY AND THE DETECTION OF VACUUM BIREFRINGENCE IN A MAGNETIC-FIELD SO MODERN PHYSICS LETTERS A LA English DT Article AB Quantum electrodynamics (QED) theory predicts that vacuum under the influence of a strong magnetic field is birefringence. Recently, several groups have proposed to used a high finesse Fabry-Perot cavity to increase the average path length of the light in the magnetic field. This together with the state-of-the-art dipole magnets, should bring the effect within reach of observation. However, the mirrors used in the FP are known to have intrinsic birefringence which is of orders of magnitude larger than the birefringence of the vacuum. In this letter, we analyze the effect of uncontrollable variations of mirror birefringence on two recently proposed optical schemes. The first scheme,(1) which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to variations of its value. In the second scheme, which we called the polarization scheme, laser polarized at 45 degrees relative to the B-field is injected into the cavity. The ellipticity and polarization rotation of the light exiting the cavity is measured.(2) Under this scheme, mirror birefringence contributes as a correction of the QED effect, greatly reducing its sensitivity to the undesirable changes. RP CHUI, TCP (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 5 TC 4 Z9 4 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 SEP 14 PY 1995 VL 10 IS 28 BP 2125 EP 2134 DI 10.1142/S0217732395002271 PG 10 WC Physics, Nuclear; Physics, Particles & Fields; Physics, Mathematical SC Physics GA RW549 UT WOS:A1995RW54900007 ER PT J AU FRIEMAN, JA HILL, CT STEBBINS, A WAGA, I AF FRIEMAN, JA HILL, CT STEBBINS, A WAGA, I TI COSMOLOGY WITH ULTRALIGHT PSEUDO NAMBU-GOLDSTONE BOSONS SO PHYSICAL REVIEW LETTERS LA English DT Article ID PHASE-TRANSITIONS; CONSTANT; MODELS; FIELD; EVOLUTION AB We explore the cosmological implications of an ultralight pseudo Nambu-Goldstone boson. With global spontaneous symmetry breaking scale f similar or equal to 10(18) GeV and explicit breaking scale comparable to Mikheyev-Smirnov-Wolfenstein neutrino masses, M similar to 10(-3) eV, such a field, which acquires a mass m(phi) similar to M(2)/f, similar to H-0, would currently dominate the energy density of the Universe. The field acts as an effective cosmological constant before relaxing into a condensate of nonrelativistic bosons. Such a model can reconcile dynamical estimates of the density parameter, Omega(m) similar to 0.2, with a spatially flat universe, yielding H(0)t(0) similar or equal to 1 consistent with limits from gravitational lens statistics. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,DEPT THEORET PHYS,BATAVIA,IL 60510. FED UNIV RIO DE JANEIRO,INST FIS,BR-21943 RIO JANEIRO,BRAZIL. RP FRIEMAN, JA (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. RI Waga, Ioav/B-6288-2014 NR 33 TC 572 Z9 573 U1 0 U2 4 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 SEP 11 PY 1995 VL 75 IS 11 BP 2077 EP 2080 DI 10.1103/PhysRevLett.75.2077 PG 4 WC Physics, Multidisciplinary SC Physics GA RT810 UT WOS:A1995RT81000003 ER PT J AU DOWNIE, JD AF DOWNIE, JD TI APPLICATION OF BACTERIORHODOPSIN FILMS IN AN ADAPTIVE-FOCUSING SCHLIEREN SYSTEM SO APPLIED OPTICS LA English DT Article ID PROTON UPTAKE; REISOMERIZATION; PHOTOCYCLE AB The photochromic property of bacteriorhodopsin films is exploited in the application of a focusing schlieren optical system for the visualization of optical phase information. By encoding an image on the film with light of one wavelength and reading out with a different wavelength, the readout beam can effectively see the photographic negative of the original image. The potential advantage of this system over previous focusing schlieren systems is that the updatable nature of the bacteriorhodopsin film allows system adaptation. I discuss two image encoding and readout techniques for the bacteriorhodopsin and use film transmission characteristics to choose the more appropriate method. I demonstrate the system principle with experimental results using argon-ion and He-Cd lasers as the two light sources of different wavelengths, and I discuss current limitations to implementation with a white-light source. RP DOWNIE, JD (reprint author), NASA,AMES RES CTR,MAIL STOP 269-3,MOFFETT FIELD,CA 94035, USA. NR 12 TC 12 Z9 13 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 10 PY 1995 VL 34 IS 26 BP 6021 EP 6028 PG 8 WC Optics SC Optics GA RR883 UT WOS:A1995RR88300018 PM 21060441 ER PT J AU STANFORD, SA EISENHARDT, PRM DICKINSON, M AF STANFORD, SA EISENHARDT, PRM DICKINSON, M TI EVOLUTION OF INFRARED-SELECTED GALAXIES IN Z-SIMILAR-TO-0.4 CLUSTERS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERS, INDIVIDUAL (ABELL 370, ABELL 851); GALAXIES, EVOLUTION; GALAXIES, PHOTOMETRY ID BULGE M-GIANTS; DISTANT CLUSTERS; ELLIPTICAL GALAXIES; SPECTRAL EVOLUTION; MAGNITUDE RELATION; STELLAR CONTENT; STANDARD STARS; PHOTOMETRY; ABELL-370; SPECTROPHOTOMETRY AB Wide-field optical and near-IR (JHK) imaging is presented for two rich galaxy clusters: Abell 370 at z = 0.374 and Abell 851 (Cl 0939 + 47) at z = 0.407. The new data are combined to produce colors sampling the 0.55-1.65 mu m range in the rest frame. Galaxy catalogs selected from the near-IR images are 90% complete to a limiting magnitude approximately 1.5 mag below K*. The resulting samples contain similar to 100 probable member galaxies per cluster in the central similar to 2 Mpc. Comparison with Hubble Space Telescope (HST) wide-field planetary camera images yields subsamples of similar to 70 galaxies in each cluster with morphological types. Analysis of the complete samples and the HST subsamples gives the following results: 1. The optical-K colors of the cluster galaxies are bounded by a red envelope of E/SO's which follow a color-magnitude relation with a slope similar to the corresponding color-magnitude relation in present-epoch E/SO's. 2. The z similar to 0.4 E/SO's are bluer than those in the Bower, Lucey, and Ellis (1992) Coma sample in the optical-K color by 0.13 mag for Abell 370 and by 0.18 mag for Abell 851. Our estimate of the systematic uncertainty indicates this color difference is significant at the 2-3 sigma level. If real, the bluing of the E/SO populations at moderate redshift is consistent with that calculated from the Bruzual and Chariot (1993) models of passive elliptical galaxy evolution. 3. In both clusters the intrinsic scatter of the known E/SO's about their optical - K color-magnitude relation is small (similar to 0.06 mag) and not significantly different from that of Coma E/SO's as given by Bower et al. (1992), indicating that the galaxies within each cluster formed at the same time at an early epoch. These results support the paradigm in which the stellar population in cluster E/SO's is a function only of the galaxy mass and the look-back time. 4. Although the passive-evolution models fit the z similar to 0.4 early-type galaxies in the optical-K color, they fail to reproduce the observations at intervening wavelengths. When normalized at rest frame similar to 1.6 mu m, the z similar to 0.4 E/SO's are fainter than the model at rest frame similar to 0.9 mu m, and brighter than the model (and than Coma E/SO's) at rest frame similar to 1.2 mu m. Such color differences are difficult to explain in terms of age or conventional metallicity effects. 5. The disk galaxies in Abell 851 are bluer and represent a greater fraction of the total sample compared to those in Abell 370. X-ray maps and large-field optical images indicate that Abell 370 is ''older'' than Abell 851, in the sense of showing a more relaxed distribution of galaxies and hot gas. In agreement with the apparent difference in cluster age, our results suggest the disk galaxies of Abell 370 have had more time in the cluster environment, relative to the disks in Abell 851, to redden and/or fade into obscurity. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. NR 59 TC 115 Z9 117 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1995 VL 450 IS 2 BP 512 EP 533 DI 10.1086/176162 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400005 ER PT J AU CONTOPOULOS, J AF CONTOPOULOS, J TI A SIMPLE TYPE OF MAGNETICALLY DRIVEN JETS - AN ASTROPHYSICAL PLASMA GUN SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; GALAXIES, JETS; ISM, JETS AND OUTFLOWS ID ACCRETION DISKS; STAR FORMATION; BIPOLAR FLOWS; ACCELERATION AB We propose a simple theoretical formulation of the problem of magnetically driven outflows when poloidal magnetic flux surfaces are absent, and the magnetic field has only a toroidal component. The present formulation is the limiting case of the more general Grad-Shafranov one, when B-p/B-phi --> 0. We show that the toroidal magnetic field alone is very efficient in accelerating and collimating outflows (jets) from accretion disks. We therefore suggest that the important physical mechanism which might be responsible for jet production in the inner part of a fully ionized thick accretion disk around an active galactic nucleus is the buildup of the toroidal magnetic field component by the differential rotation of the disk, and its subsequent escape out of the disk. This is qualitatively different from the centrifugal driving mechanism of Blandford and Payne (1982), which might be important only in the partially ionized parts of the accretion disk where B-p similar to B-phi. Our formalism is also applied to describe briefly the time-dependent problem. RP CONTOPOULOS, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 29 TC 97 Z9 98 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1995 VL 450 IS 2 BP 616 EP 627 DI 10.1086/176170 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400013 ER PT J AU PIER, EA VOIT, GM AF PIER, EA VOIT, GM TI PHOTOEVAPORATION OF DUSTY CLOUDS NEAR ACTIVE GALACTIC NUCLEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; GALAXIES, ACTIVE; GALAXIES, SEYFERT; HYDRODYNAMICS; ISM, CLOUDS; LINE, FORMATION ID SEYFERT 2 GALAXIES; IONIZING-RADIATION; HEATED WINDS; LINE REGIONS; NGC-1068; EMISSION; GRAINS; SPECTROPOLARIMETRY; SPECTRUM; MODELS AB We investigate the hydrodynamic and line-emitting properties of dusty clouds exposed to an active galactic nucleus (AGN) continuum. Such clouds may be found on the inner edges of the tori commonly implicated in AGN unification schemes. An X-ray-heated wind will be driven off the surface of such a cloud, eventually destroying it. Dust grains are carried along with the flow and are destroyed by sputtering as the wind heats. In smaller clouds, sputtering regulates the outflow by reducing the radiation force opposing the flow. Cloud evaporation may be fast enough to determine the location of the inner edge of the torus. However, since the evaporation time is much longer than the orbital time, clouds on eccentric orbits can penetrate well inside the inner edge of the torus. Therefore, the ionization structure of the cloud is determined only by the incipient continuum shape. The inner faces of exposed clouds are pressurized primarily by the incident radiation. Radiation pressure on dust grains regulates how gas pressure increases with optical depth. Ionization levels decrease inward, and the bulk of the cloud is molecular and neutral. The effects of dust extinction and high density suppress the hydrogen recombination lines and the forbidden lines from C, N, and O ions below observed levels despite the high covering factor expected for the torus. However, the inner edge of the torus is a natural place for producing the iron coronal lines often seen in the spectra of AGNs (i.e., [Fe VIII] lambda 6087, [Fe X] lambda 6375, [Fe XI] lambda 7892, and [Fe XIV] lambda 5303). C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. RP PIER, EA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 665,GREENBELT,MD 20771, USA. OI Voit, Gerard/0000-0002-3514-0383 NR 42 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 SEP 10 PY 1995 VL 450 IS 2 BP 628 EP 637 DI 10.1086/176171 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400014 ER PT J AU RAMANAMURTHY, PV BERTSCH, DL FICHTEL, CE KANBACH, G KNIFFEN, DA MAYERHASSELWANDER, HA NOLAN, PL SREEKUMAR, P THOMPSON, DJ AF RAMANAMURTHY, PV BERTSCH, DL FICHTEL, CE KANBACH, G KNIFFEN, DA MAYERHASSELWANDER, HA NOLAN, PL SREEKUMAR, P THOMPSON, DJ TI A LONG-TERM STUDY OF HIGH-ENERGY GAMMA-RAY EMISSION FROM THE VELA, GEMINGA, AND CRAB PULSARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, OBSERVATIONS; PULSARS, INDIVIDUAL (VELA, GEMINGA, AND CRAB) ID RAPIDLY SPINNING PULSARS; NEBULA; RADIATION AB We have analyzed similar to 3 yr of data on the Vela, Geminga, and Crab pulsars in the energy range 30 MeV to 30 GeV, gathered by the EGRET detector aboard the Compton Gamma Ray Observatory, to study long-term variability in the various characteristics of high-energy gamma-ray emission by these objects. The light curves at energies greater than or equal to 100 MeV are generally constant in time. However, it is noticed that occasionally the emission of high-energy gamma rays under one of the two peaks of the Vela and Crab pulsars is significantly less than the long-term average. The ratio of background-subtracted pulsed intensities under the two peaks, P2/P1, in the Crab pulsar is consistent with both the hypotheses of a 13.5 yr sinusoidal variation and a constant (no variation) ratio. While the integral flux at E greater than or equal to 100 MeV is nearly constant in the case of the Crab pulsar, it appears to be variable in the cases of the Vela and Geminga pulsars. The slopes of the energy spectra show evidence of variability particularly for the Vela and Geminga pulsars. C1 NASA,NRC,WASHINGTON,DC 20546. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. UNIV SPACE RES ASSOC,COLUMBIA,MD. RP RAMANAMURTHY, PV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 662,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 52 TC 39 Z9 39 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1995 VL 450 IS 2 BP 791 EP 804 DI 10.1086/176184 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400027 ER PT J AU BURROWS, A HAYES, J FRYXELL, BA AF BURROWS, A HAYES, J FRYXELL, BA TI ON THE NATURE OF CORE-COLLAPSE SUPERNOVA EXPLOSIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUCLEAR REACTIONS,NUCLEOSYNTHESIS, ABUNDANCES; STARS, INTERIORS; SUPERNOVAE, GENERAL ID II SUPERNOVAE; EARLY EVOLUTION; NEUTRON-STARS; MASSIVE STARS; SHOCK-WAVES; SN-1987A; INSTABILITY; CONVECTION; NUCLEOSYNTHESIS; SIMULATIONS AB We investigate in this paper the core-collapse supernova explosion mechanism in both one and two dimensions. With a radiation/hydrodynamic code based upon the PPM algorithm, we verify the usefulness of neutrino-driven overturn (''convection'') between the shock and the neutrinosphere in igniting the supernova explosion. The two-dimensional simulation of the core of a 15 M(circle dot) star that we present here indicates that the breaking of spherical symmetry may be central to the explosion itself and that a multitude of bent and broken fingers is a common feature of the ejecta. As in one dimension, the explosion seems to be a mathematically critical phenomenon, evolving from a steady state to explosion after a critical mass accretion rate through the stalled shock has been reached. In the two-dimensional simulation the preexplosion convective phase lasted similar to 30 overturns (similar to 100 ms) before exploding. The preexplosion steady state in two dimensions is similar to that achieved in one dimension, but in two dimensions, owing to the longer dwell time of matter in the overturning region, the average entropy achieved behind the stalled shock is larger. In addition, the entropy gradient in the convecting region is flatter. These effects, together with the dynamical pressure of the buoyant plumes, serve to increase the steady state shock radius (R(s)) over its value in one dimension by 30%-100%. A large R(s) enlarges the volume of the gain region, puts shocked matter lower in the gravitational potential well, and lowers the accretion ram pressure at the shock for a given hi. The critical condition for explosion is thereby relaxed. Since the ''escape'' temperature (T-esc) decreases with radius faster than the actual matter temperature (T) behind the shock, a larger R(s) puts a larger fraction of the shocked material above its local escape temperature. T > T-esc is the condition for a thermally driven corona to lift off a star. In one, two, or three dimensions, since supernovae are driven by neutrino heating, they are coronal phenomena, akin to winds, though initially bounded by an accretion ram. Neutrino radiation pressure is unimportant. We find that large and small eddies coexist, both before and after explosion. In the unstable region before explosion, columnar downflows are quasi-periodically formed and break up. These plumes excite nonlinear internal g-modes that feed back onto the convection and cause the plumes to meander over the neutrinosphere. The radial neutrino flux fluctuates with angle and time in response to the anisotropic mass flux onto the neutrinospheres by as much as a factor of 3. The boiling motion of the unstable region interior to the shock is epitomized by neutrino-heated bubbles that rise and collide episodically with the shock, whose radius oscillates in angle and time by as much as 30%. The angle-averaged neutrino luminosities vary by as much as 60% and decrease by a factor of 2 right after the explosion in a characteristic way. The region interior to the neutrinosphere has weakly unstable lepton and entropy gradients that drive persistent convective motions after core bounce. However, the effects of this convection on the driving neutrino luminosities seem dwarfed by the effects of convective dredge-up and by the wildly varying accretion component. We see no evidence of a ''building'' or accumulation of energy before explosion, save in the kinetic energy, in response to the decaying accretion ram. In fact, the total energy in the overturning region decreases steadily before explosion. In addition, we have noted a nontrivial dependence on the neutrino transport algorithm. We would eschew terms such as ''robust'' when referring to the effect of convection on the outcome of collapse. Neutrino energy is pumped into the supernova during the shock's propagation through the inner many thousands of kilometers and not ''instantaneously.'' Curiously, just after the explosion is triggered, the matter that will eventually be ejected is still bound. In addition, for a given asymptotic explosion energy, the amount of mass that reaches explosive nucleosynthesis temperatures is less than heretofore assumed. This may help to solve the Ni-56 overproduction problem encountered in previous models of explosive nucleosynthesis. The high-speed fingers that emerge from our model core seem a natural explanation for the nickel bullets seen in SN 1987A and the shrapnel inferred in some supernova remnants. In addition, the vigorous convective motions interior to the shock can impart to the residue recoil velocities and spins. The magnitudes of the former might be within reach of the observed pulsar proper motions, but extensive new calculations remain to be done to verify this. Within 100 ms of the explosion, a strong, neutrino-driven wind is blowing outward from the proto-neutron star that clears the interior of mass and, while operative, does not allow fallback. At the base of the rising explosion plumes (in the early wind), a few high-entropy (similar to 60) clumps are ejected, whose subsequent evolution may prove to be of relevance to the r-process. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BURROWS, A (reprint author), UNIV ARIZONA,DEPT PHYS & ASTRON,TUCSON,AZ 85721, USA. NR 97 TC 511 Z9 517 U1 1 U2 15 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1995 VL 450 IS 2 BP 830 EP & DI 10.1086/176188 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400031 ER PT J AU TITARCHUK, L LYUBARSKIJ, Y AF TITARCHUK, L LYUBARSKIJ, Y TI POWER-LAW SPECTRA AS A RESULT OF COMPTONIZATION OF THE SOFT RADIATION IN A PLASMA CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLASMA; RADIATION MECHANISMS, THERMAL; RADIATIVE TRANSFER; SCATTERING ID BLACK-HOLE CANDIDATES; THERMAL PLASMAS; ACCRETION DISKS; CYGNUS X-1 AB We show that power-law spectra are the exact solutions of the radiative kinetic equation with an assumption of low-frequency photon injection for a wide range of the electron distributions. We derive the dispersion equation for the determination of the power-law index. The whole problem of the determination of power-law spectra is separable. The radiative transfer in the photon energy space and in the configuration space can be considered independently. This is a result of there being no preferred energy scale for the radiation in this Comptonization problem. We confirm Sunyaev and Titarchuk's (1985) result that the angular distribution of the hard radiation depends only on the plasma cloud optical depth and it does not depend on photon energy. Also, the power index for the monoenergetic electron distribution is derived, allowing the appropriate indices to be determined for a wide range of electron distributions. As an example we give the power-law indices as a function of the plasma optical depth and the plasma temperature for the Maxwellian distribution. The exact analytical solutions of this equation are given without any limitation on the optical depth and plasma temperature for two geometries of plasma cloud: disk and spherical. The analytical models, verified by Monte Carlo calculations, make possible a more efficient spectral analysis of data obtained from X-ray and gamma-ray sources. C1 UKRAINIAN ACAD SCI, INST RADIOASTRON, KHARKOV 310002, UKRAINE. RP TITARCHUK, L (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RI LYUBARSKY, YURY/F-2362-2012 NR 34 TC 86 Z9 86 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1995 VL 450 IS 2 BP 876 EP 882 DI 10.1086/176191 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RT244 UT WOS:A1995RT24400034 ER PT J AU VERMOTE, E KAUFMAN, YJ AF VERMOTE, E KAUFMAN, YJ TI ABSOLUTE CALIBRATION OF AVHRR VISIBLE AND NEAR-INFRARED CHANNELS USING OCEAN AND CLOUD VIEWS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID RADIOMETRIC CALIBRATION; RADIATIVE PROPERTIES; RAYLEIGH-SCATTERING; SATELLITE IMAGERY; AEROSOL LAYER; IN-FLIGHT; SENSORS; NOAA-7; RETRIEVAL; AIRCRAFT AB Methods for absolute calibration of visible and near-infrared sensors using ocean and cloud views have been developed and applied to channels 1 (red) and 2 (near-infrared) of the Advanced Very High Resolution Radiometer (AVHRR) for the NOAA-7, -9 and -11 satellites. The approach includes two steps. First step is intercalibration between channels 1 and 2 using high altitude (12km and above) bright clouds as 'white' targets. This cloud intercalibration is compared with intercalibration using ocean glint. The second step is an absolute calibration of channel 1 employing ocean off-nadir view (40-70 degrees) in channels 1 and 2 and correction for the aerosol effect. In this process the satellite measurements in channel 2, corrected for water vapour absorption are used to correct channel 1 for aerosol effect. The net signal in channel 1 composed from the predictable Rayleigh scattering component is used to calibrate this channel. The result is an absolute calibration of the two AVHRR channels. NOAA-9 channels 1 and 2 show a degradation rate of 8.8 per cent and 6 per cent, respectively, during 1985-1988 and no further degradation during 1988-1989 period. NOAA-11 shows no degradation during the 1989 mid 1991 period. This trend is similar to the calibration trend obtained using desert site observations, the absolute calibration found in this work for both sensors is lower by 17 to 20 per cent (suggesting higher degradation) from the absolute calibration of Abel et al. (1993, Journal of Atmospheric and Ocean Technology, 10, 493-508), that used aircraft measurements. Furthermore we show that application of the calibration of Abel et al. or the present one for remote sensing of aerosol over Tasmania, Australia failed to predict correctly the aerosol optical thickness measured there. The only way to reconcile all these differences is by allowing for a shift of 17 nm towards longer wavelengths of the AVHRR channel 1 effective wavelength. We show that with this shift, we get an agreement between the two absolute calibration techniques (+/-3 per cent), and both of them do predict correctly the optical thickness in the two channels (+/-0.02). Recent work in preparation for publication (Vermote et al., 1995, in preparation) indicates that this shift is due to an out of band transmission (6 per cent at 900 nm) for AVHRR channel 1 previously unidentified. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP VERMOTE, E (reprint author), UNIV MARYLAND,GLOBAL REMOTE SENSING LAB,LEFRAK HALL,COLLEGE PK,MD, USA. RI Vermote, Eric/K-3733-2012 NR 42 TC 166 Z9 176 U1 2 U2 6 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD SEP 10 PY 1995 VL 16 IS 13 BP 2317 EP 2340 PG 24 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA RU687 UT WOS:A1995RU68700004 ER PT J AU WELKER, JE AU, AY BROWN, RD AF WELKER, JE AU, AY BROWN, RD TI GRAVITY ANALYSIS OVER THE ARAL, BLACK, AND CASPIAN SEAS FROM A COMBINED GEOS-3-SEASAT-GEOSAT ALTIMETER DATA SET SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SURFACES; ERRORS AB GEOS 3, Seasat and Geosat satellite altimetry data over the Aral, Black and Caspian Seas are processed using least squares collocation to predict geoid undulations and free-air gravity anomalies on a 0.25 degrees x 0.25 degrees grid. A 180 x 180 geopotential model provides a reference Surface for the collocation procedure and the framework for a regional map. Using local empirical covariance functions computed by an iterative numerical convolution technique, prediction accuracies of 24, 8, and 10 mGal were achieved for the Aral, Black, and Caspian Seas, respectively. Over the Caspian Sea, a hybrid theoretical/empirical covariance function was used to obtain reliable short-wavelength gravity anomalies. The resulting regional gravity anomaly map confirms tectonic structures postulated by other investigators, reveals gravitational evidence of river sediments, and generally improves our knowledge of the geophysics of inland seas. C1 HUGHES STX CORP, GREENBELT, MD 20770 USA. RP NASA, GODDARD SPACE FLIGHT CTR, TERR PHYS LAB, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. NR 31 TC 0 Z9 0 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD SEP 10 PY 1995 VL 100 IS B9 BP 18103 EP 18115 DI 10.1029/94JB01177 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RU400 UT WOS:A1995RU40000038 ER PT J AU LI, ZJ FRIEDL, RR SANDER, SP AF LI, ZJ FRIEDL, RR SANDER, SP TI KINETICS OF FO2 WITH NO, NO2, O-3, CH4, AND C2H6 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID THERMAL UNIMOLECULAR REACTIONS; RATE CONSTANTS; LOW-PRESSURES; UPPER LIMITS; CF3O+O3->CF3O2+O2; RADICALS; FLUORINE; REACTORS; 295-K AB The kinetics of the reactions FO2 + NO --> products (11) and FO2 + NO2 --> products (12) have been studied as functions of temperature at 1 Torr total pressure using a discharge-flow mass spectrometric technique. The measured rate coefficients, expressed in Arrhenius form, are k(11) (7.5 +/- 0.5) x 10(-12) exp[(-688 +/- 377)/T] cm(3) molecule(-1) s(-1) for 190 K < T < 298 K and k(12) = (3.8 +/- 0.8) x 10(-11) exp[(-2042 +/- 456)/T] cm(3) molecule(-1) s(-1) for 260 K < T < 315 K. The observed temperature dependencies of the rate coefficients indicate that the reactions occur primarily by simple bimolecular, rather than termolecular, mechanisms. Mass spectral product studies are consistent with bimolecular processes involving F atom extraction from FO2. Upper limits for the rate coefficients of FO2 + O-3 --> products (13), FO2 + CH4 --> products (14), and FO2 + C2H6 --> products (15) have also been determined with the same experimental system at room temperature: k(13) < 3 X 10(-15) cm(3) molecule(-1) s(-1), k(14) < 2 x 10(-16) cm(3) molecule(-1) s-(1,) and k(15) < 4 x 10(-16) cm(3) molecule(-1) s(-1). As part of the FO2 + O-3 study, an investigation of the reaction FO + O-3 --> FO2 + O-2 (6) was conducted. An upper limit of k(6) < 1 x 10(-14) cm(3) molecule(-1) s(-1) has been obtained for the FO reaction. The implications of these results for fluorine oxide chemistry in the atmosphere are discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 33 TC 20 Z9 20 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 7 PY 1995 VL 99 IS 36 BP 13445 EP 13451 DI 10.1021/j100036a019 PG 7 WC Chemistry, Physical SC Chemistry GA RU476 UT WOS:A1995RU47600019 ER PT J AU CONNELL, JW CRIVELLO, JV BI, D AF CONNELL, JW CRIVELLO, JV BI, D TI EFFECT OF LOW-EARTH-ORBIT ATOMIC OXYGEN EXPOSURE ON EPOXY FUNCTIONALIZED SILOXANES SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article ID SPACE STATION; SILICON; PLASMA AB Epoxy functionalized siloxanes (EFS) are a novel class of UV curable monomers that can be rapidly photopolymerized to give transparent coatings and composites. Thin films of these materials have been subjected to low Earth orbit exposure to atomic oxygen (AO) aboard the space shuttle. It was found that UV cured samples of all four different EFS monomers exhibited excellent AO resistance both to ambient in-flight conditions as well as exposure at 120 degrees C. Based on SEM, STM, XPS, and weight loss data, it was proposed that AO exposure of these materials efficiently produces a thin layer of SiOx at the surface of the sample. This layer provides a barrier toward further attack by AO. (C) 1995 John Wiley and Sons, Inc. C1 RENSSELAER POLYTECH INST,DEPT CHEM,TROY,NY 12180. RP CONNELL, JW (reprint author), NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23681, USA. NR 37 TC 21 Z9 24 U1 0 U2 6 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD SEP 6 PY 1995 VL 57 IS 10 BP 1251 EP 1259 DI 10.1002/app.1995.070571011 PG 9 WC Polymer Science SC Polymer Science GA RL466 UT WOS:A1995RL46600011 ER PT J AU GOLDBERG, RK HOPKINS, DA AF GOLDBERG, RK HOPKINS, DA TI APPLICATION OF THE BOUNDARY-ELEMENT METHOD TO THE MICROMECHANICAL ANALYSIS OF COMPOSITE-MATERIALS SO COMPUTERS & STRUCTURES LA English DT Article AB A new boundary element formulation for the micromechanical analysis of composite materials is presented in this study. A unique feature of the formulation is the use of circular shape functions to convert the two-dimensional integrations of the composite fibers to one-dimensional integrations. To demonstrate the applicability of the formulations, several example problems including elastic and thermal analyses of laminated composites and elastic analyses of woven composites are presented and the boundary element results compared to experimental observations and/or results obtained through alternate analytical procedures. While several issues remain to be addressed in order to make the methodology more robust, the formulations presented here show the potential in providing an alternative to traditional finite element methods, particularly for complex composite architectures. RP GOLDBERG, RK (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 22 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD SEP 3 PY 1995 VL 56 IS 5 BP 721 EP 731 DI 10.1016/0045-7949(95)00003-Y PG 11 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA RJ227 UT WOS:A1995RJ22700003 ER PT J AU DACLESMARIANI, J ZILLIAC, GG CHOW, JS BRADSHAW, P AF DACLESMARIANI, J ZILLIAC, GG CHOW, JS BRADSHAW, P TI NUMERICAL EXPERIMENTAL-STUDY OF A WINGTIP VORTEX IN THE NEAR-FIELD SO AIAA JOURNAL LA English DT Article ID PRESSURE AB The near-field behavior of a wingtip vortex flow has been studied computationally and experimentally in an interactive fashion, The computational approach involved using the method of artificial compressibility to solve the three-dimensional, incompressible, Navier-Stokes equations with experimentally determined boundary conditions and a modified Baldwin-Barth turbulence model. Inaccuracies caused by the finite difference technique, grid resolution, and turbulence modeling have been explored. The complete geometry case was computed using 1.5 million grid points and compared with mean velocity measurements on the suction side of the wing and in the near wake. Good agreement between the computed and measured flowfields has been obtained. The velocity distribution in the vortex core compares to within 3% of the experiment. C1 NASA,AMES RES CTR,FLUID MECHANISMS LAB,MOFFETT FIELD,CA 94035. STANFORD UNIV,INST DEF ANAL,STANFORD,CA. RP DACLESMARIANI, J (reprint author), NASA,AMES RES CTR,ADC BRANCH,MOFFETT FIELD,CA 94035, USA. NR 22 TC 158 Z9 165 U1 4 U2 16 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1995 VL 33 IS 9 BP 1561 EP 1568 DI 10.2514/3.12826 PG 8 WC Engineering, Aerospace SC Engineering GA RU508 UT WOS:A1995RU50800001 ER PT J AU CHUNG, CH DEWITT, KJ STUBBS, RM PENKO, P AF CHUNG, CH DEWITT, KJ STUBBS, RM PENKO, P TI SIMULATION OF OVEREXPANDED LOW-DENSITY NOZZLE PLUME FLOW SO AIAA JOURNAL LA English DT Article ID NITROGEN AB The direct simulation Monte Carlo method was applied to the analysis of low-density nitrogen plumes exhausting from a small converging-diverging nozzle into finite ambient pressures. Two cases were considered that simulated actual test conditions in a vacuum facility. The numerical simulations readily captured the complicated flow structure of the overexpanded plumes adjusting to the finite ambient pressures, including Mach disks and barrel-shaped shocks. The numerical simulations compared well to experimental data of Rothe. C1 UNIV TOLEDO,DEPT CHEM ENGN,TOLEDO,OH 43606. NASA,LEWIS RES CTR,COMPUTAT METHODS SPACE BRANCH,CLEVELAND,OH 44135. 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 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1995 VL 33 IS 9 BP 1646 EP 1650 DI 10.2514/3.12812 PG 5 WC Engineering, Aerospace SC Engineering GA RU508 UT WOS:A1995RU50800013 ER PT J AU HUANG, PG COLEMAN, GN AF HUANG, PG COLEMAN, GN TI VANDRIEST TRANSFORMATION AND COMPRESSIBLE WALL-BOUNDED FLOWS (VOL 32, PG 2110, 1994) SO AIAA JOURNAL LA English DT Correction, Addition C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP HUANG, PG (reprint author), ELORET INST,PALO ALTO,CA 94303, USA. NR 1 TC 3 Z9 3 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1995 VL 33 IS 9 BP 1756 EP 1756 DI 10.2514/3.48353 PG 1 WC Engineering, Aerospace SC Engineering GA RU508 UT WOS:A1995RU50800033 ER PT J AU ENGELKE, KA DOERR, DF CONVERTINO, VA AF ENGELKE, KA DOERR, DF CONVERTINO, VA TI A SINGLE BOUT OF EXHAUSTIVE EXERCISE AFFECTS INTEGRATED BAROREFLEX FUNCTION AFTER 16 DAYS OF HEAD-DOWN TILT SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE BLOOD PRESSURE; HEART RATE; MICROGRAVITY; VALSALVA MANEUVER ID CARDIAC REFLEX RESPONSES; VAGAL BAROREFLEX; VALSALVA MANEUVER; BED REST; BARORECEPTOR; HYPOTENSION; TOLERANCE; PRESSURE; VOLUME; HUMANS AB We tested the hypothesis that one bout of maximal exercise performed 24 h before reambulation from 16 days of 6 degrees head-down tilt (HDT) could increase integrated baroreflex sensitivity. Isolated carotid-cardiac and integrated baroreflex function was assessed in seven subjects before and after two periods of HDT separated by 11 mo. On the last day of one HDT period, subjects performed a single bout of maximal cycle ergometry (exercise). Subjects did not exercise after the other HDT period (control). Carotid-cardiac baroreflex sensitivity was evaluated using a neck collar device. Integrated baroreflex function was assessed by recording heart rate (HR) and blood pressure (MAP) during a 15-s Valsalva maneuver (VM) at a controlled expiratory pressure of 30 mmHg. The ratio of change in HR to change in MAP (Delta HR/Delta MAP) during phases II and IV of the VM was used as an index of cardiac baroreflex sensitivity. Baroreflex-mediated vasoconstriction was assessed by measuring the late phase II rise in MAP. Following HDT, carotid-cardiac baroreflex sensitivity was reduced (2.8 to 2.0 ms/mmHg; P = 0.05) as was Delta HR/Delta MAP during phase II (-1.5 to -0.8 beats/mmHg; P = 0.002). After exercise, isolated carotid baroreflex activity and phase II Delta HR/Delta MAP returned to pre-HDT levels but remained attenuated in the control condition. Phase IV Delta HR/Delta Add > Ham > RF, with the Ham and RF showing essentially no involvement. CSA of the VS and Add muscle groups were increased 10 and 5%, respectively, immediately after exercise in each thigh with no changes in Ham and RF CSA. PV was decreased 22% immediately following exercise. The absolute loss of PV was correlated (r(2) = 0.75) with absolute increase in muscle CSA immediately postexercise, supporting the notion that increased muscle size after resistance exercise reflects primarily fluid movement from the vascular space into active but not inactive muscle. C1 NASA, BIOMED OPERAT & RES OFF, KENNEDY SPACE CTR, FL 32899 USA. RP PLOUTZSNYDER, LL (reprint author), OHIO UNIV, DEPT BIOL SCI, IRVINE HALL, ATHENS, OH 45701 USA. NR 31 TC 66 Z9 66 U1 0 U2 4 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regulat. Integr. Compar. Physiol. PD SEP PY 1995 VL 269 IS 3 BP R536 EP R543 PG 8 WC Physiology SC Physiology GA RW600 UT WOS:A1995RW60000008 PM 7573553 ER PT J AU HOWARD, SK GABA, DM ROSEKIND, MR AF HOWARD, SK GABA, DM ROSEKIND, MR TI EVALUATION OF DAYTIME SLEEPINESS IN RESIDENT ANESTHESIOLOGISTS SO ANESTHESIOLOGY LA English DT Meeting Abstract C1 STANFORD UNIV,SCH MED,PALO ALTO,CA 94304. NASA,AMES RES CTR,PALO ALTO,CA 94304. VET ADM MED CTR,ANESTHESIA SERV 112A,PALO ALTO,CA 94304. NR 1 TC 2 Z9 2 U1 0 U2 1 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0003-3022 J9 ANESTHESIOLOGY JI Anesthesiology PD SEP PY 1995 VL 83 IS 3A SU S BP A1007 EP A1007 PG 1 WC Anesthesiology SC Anesthesiology GA RX685 UT WOS:A1995RX68501007 ER PT J AU HOWARD, SK GABE, DM ROSEKIND, MR AF HOWARD, SK GABE, DM ROSEKIND, MR TI SUBJECTIVE ASSESSMENT OF SLEEPINESS AND SLEEP ONSET PERCEPTION OF RESIDENT ANESTHESIOLOGISTS SO ANESTHESIOLOGY LA English DT Meeting Abstract C1 STANFORD UNIV,SCH MED,PALO ALTO,CA 94304. NASA,AMES RES CTR,PALO ALTO,CA 94304. VET ADM MED CTR,ANESTHESIA SERV 112A,PALO ALTO,CA 94304. NR 0 TC 3 Z9 3 U1 0 U2 1 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0003-3022 J9 ANESTHESIOLOGY JI Anesthesiology PD SEP PY 1995 VL 83 IS 3A SU S BP A1009 EP A1009 PG 1 WC Anesthesiology SC Anesthesiology GA RX685 UT WOS:A1995RX68501009 ER PT J AU NAMKUNG, JS HOKE, M ROGOWSKI, RS ALBIN, S AF NAMKUNG, JS HOKE, M ROGOWSKI, RS ALBIN, S TI FT-IR OPTICAL-FIBER REMOTE DETECTION OF ALUMINUM HYDROXIDE BY EVANESCENT-WAVE ABSORPTION-SPECTROSCOPY SO APPLIED SPECTROSCOPY LA English DT Article DE ATR SPECTROSCOPY; EVANESCENT WAVE ABSORPTION SPECTROSCOPY; REMOTE FIBEROPTIC SENSING ID CELL AB Remote detection of very small amounts of aluminum hydroxide has been achieved with the use of evanescent wave absorption spectroscopy. Aluminum hydroxide is a principal corrosion product of aluminum. Five absorption bands have been recorded in the spectral range from 3350 to 3650 cm(-1). The recorded positions, transition strengths, and widths of the absorption bands are in qualitative agreement with reference spectral data. A four-wavenumber-resolution Michelson interferometer and decoated 200-mu m-core-diameter multimode chalcogenide optical fibers were combined to make the evanescent wave absorption measurements. One-to four-meter lengths of fiber were used with 15 to 25 cm of the fibers decoated. The technique is very sensitive and can detect a very small amount of aluminum hydroxide in contact with the decoated fiber core. This study is a valuable step in the development of a technique for monitoring industrial corrosion of aluminum alloys. C1 PHILLIPS LAB,GEOPHYS DIRECTORATE,BEDFORD,MA 01731. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. OLD DOMINION UNIV,DEPT ELECT & COMP ENGN,NORFOLK,VA 23529. RP NAMKUNG, JS (reprint author), COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185, USA. NR 17 TC 7 Z9 7 U1 1 U2 2 PU SOC APPLIED SPECTROSCOPY PI FREDERICK PA PO BOX 1438, FREDERICK, MD 21701 SN 0003-7028 J9 APPL SPECTROSC JI Appl. Spectrosc. PD SEP PY 1995 VL 49 IS 9 BP 1305 EP 1310 DI 10.1366/0003702953965344 PG 6 WC Instruments & Instrumentation; Spectroscopy SC Instruments & Instrumentation; Spectroscopy GA RW317 UT WOS:A1995RW31700015 ER PT J AU THOMPSON, D DJORGOVSKI, S TRAUGER, J AF THOMPSON, D DJORGOVSKI, S TRAUGER, J TI A NARROW-BAND IMAGING SURVEY FOR PRIMEVAL GALAXIES SO ASTRONOMICAL JOURNAL LA English DT Article ID LYMAN-ALPHA EMISSION; STAR-FORMING GALAXIES; REDSHIFT SURVEY; STANDARD STARS; RADIO GALAXY; QUASAR; SEARCH; SYSTEM; POPULATIONS; PHOTOMETRY AB We present the results of a narrowband imaging survey for Ly alpha emission from young and forming ellipticals or spheroids at high redshifts. A total of 11 independent datacubes, each consisting of 6-11 images at slightly different central wavelengths, were obtained using a Fabry-Perot imaging interferometer on fields of similar to 5 arcmin square. Each datacube spans Delta z-0.2 while the total survey spans a redshift range of 2.78-4.89 for Ly alpha line emission. We reach a 1 sigma limiting Line flux (in an aperture of twice the seeing FWHM) of similar to 1.5 X 10(-17) ergs cm(-2) s(-1) over 0.05 deg(2), with a total of 0.63 deg(2) surveyed to a limiting line flux of similar to 8.5X10(-17) ergs cm(-2) s(-1). The survey reaches a 1 sigma average limiting restframe Ly alpha emission line luminosity of similar to 1.5X10(42) ergs s(-1) over a volume of 3000 comoving Mpc(3), with a total volume of 110 000 comoving Mpc(3) surveyed to an emission line luminosity of similar to 2.0X10(43) ergs s(-1) (for H-0 = 75 km s(-1) Mpc(-1) and Ohm(0)=0.2). No obvious population of Ly alpha luminous primeval galaxies has been detected so far, although a number of candidates remain which need to be checked by follow-up spectroscopy. Possible explanations for the lack of detection of a population of primeval galaxies at optical wavelengths in this and similar surveys include the possibility that they were obscured by dust or that the bulk of galaxy formation occurred at redshifts z(gf)greater than or equal to 5. The instrument used for this survey is also briefly described. (C) 1995 American Astronomical Society. C1 CALTECH, PALOMAR OBSERV, PASADENA, CA 91125 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 82 TC 57 Z9 57 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1995 VL 110 IS 3 BP 963 EP 981 DI 10.1086/117576 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700001 ER PT J AU CRENSHAW, DM BOGGESS, A WU, CC AF CRENSHAW, DM BOGGESS, A WU, CC TI FAINT OBJECT SPECTROGRAPH OBSERVATIONS OF MRK-509 - ULTRAVIOLET-ABSORPTION LINES NEAR THE REDSHIFT OF THE SEYFERT-GALAXY SO ASTRONOMICAL JOURNAL LA English DT Article ID DETAILED OBSERVATIONS; NGC-3516; SPECTRA; IUE; MARKARIAN-509; NGC-4151; NGC-5548; GAS AB Ultraviolet spectra of the Seyfert 1 galaxy Mrk 509 have been obtained with the Faint Object Spectrograph on the Hubble Space Telescope. The spectra show strong absorption lines in the cores of the redshifted emission Lines of Ly alpha and C IV lambda lambda 1548.2, 1550.8, confirming an earlier detection in IUE high-dispersion spectra, and a new detection of strong N V lambda lambda 1238.8, 1242.8 absorption lines, also near the redshift of Mrk 509. There is no evidence for absorption in the Lines of Mg II or Si IV at the redshift of Mrk 509. The absorption lines have two components that are at the same velocities as those in the IUE observations obtained similar to 12 yr earlier: one at the systemic redshift of the host galaxy, as defined by the low-ionization emission lines in the optical, and one at a radial velocity of -390 km s(-1) relative to the systemic redshift. The equivalent widths and velocities of the absorption lines indicate that they arise from an extended region of highly ionized gas surrounding the nucleus of the host galaxy consisting of two distinct kinematic components. (C) 1995 American Astronomical Society. C1 SPACE TELESCOPE SCI INST,COMP SCI CORP,BALTIMORE,MD 21218. RP CRENSHAW, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 24 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 SEP PY 1995 VL 110 IS 3 BP 1026 EP 1031 DI 10.1086/117582 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700007 ER PT J AU WALLER, WH MARSH, M BOHLIN, RC CORNETT, RH DIXON, WV ISENSEE, JE MURTHY, J OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP AF WALLER, WH MARSH, M BOHLIN, RC CORNETT, RH DIXON, WV ISENSEE, JE MURTHY, J OCONNELL, RW ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET SKY AS OBSERVED BY THE SHUTTLE-BORNE ULTRAVIOLET IMAGING TELESCOPE SO ASTRONOMICAL JOURNAL LA English DT Article ID BACKGROUND-RADIATION; NIGHTGLOW; EMISSION; SPECTRUM; DUST AB Analysis of 489 wide-field images obtained by the Shuttle-borne Ultraviolet Imaging Telescope (UIT) has yielded positive detections of FUV and NUV backgrounds in both the orbital daytime and nighttime skies. The daytime backgrounds can be attributed to atmospheric dayglow line emission (in the FUV) and solar stray-light contamination (in the NUV). A few of the nighttime backgrounds (in both bands) appear to be affected by stray light from UV-bright stars just beyond the imaged fields of view. In both bands, the highest nighttime background levels are found in nebular fields at low galactic latitude. The diffuse backgrounds in these fields are probably associated with the adjoining nebulosity. Away from the galactic plane, the nighttime FUV backgrounds are confused by O I nightglow emission and possible photometric errors. The more tightly constrained NUV intensities correlate with those predicted from corresponding optical measurements of the Zodiacal light, yielding a NUV/Vis ''color'' of 0.5+/-0.2 for the Zodiacal light. After subtraction of the predicted Zodiacal component, the residual NUV intensities correlate with FIR measurements of the corresponding fields. Extrapolation to negligible FIR intensities yields an extragalactic NUV component of 300 photon units or less. This upper limit supports the low intensities that have been proposed in the debate over the strength and structure of the UV background (cf. Henry, ARA&A, 29, 89, 1991; Bowyer, ARA&A, 29, 59 1991). Such low values reinforce the characterization of the ultraviolet sky as the ''window'' of choice in the search for nearby low-surface-brightness galaxies and faint primeval galaxies much farther away. (C) 1995 American Astronomical Society. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP WALLER, WH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,HUGHES STX CORP,CODE 681,GREENBELT,MD 20771, USA. RI Murthy, Jayant/F-4433-2010 NR 51 TC 20 Z9 20 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1995 VL 110 IS 3 BP 1255 EP 1284 DI 10.1086/117601 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700026 ER PT J AU SMALE, AP AF SMALE, AP TI THE INFRARED COUNTERPART OF X1323-619 SO ASTRONOMICAL JOURNAL LA English DT Article ID PERIODIC INTENSITY DIPS; X-RAY BINARIES; DISCOVERY; PHOTOMETRY; CATALOG AB X1323-619 is a low-mass x-ray binary which shows deep 50 min dips in its x-ray light curve with a periodicity of 2.93 h. Using the AAT+IRIS, we have discovered a faint (K' = 17.05+/-0.20, J similar to 20), variable IR object within the Einstein error circle for X1323-619. The variability observed from this object, combined with the positional coincidence, brightness considerations, and the lack of other suitable candidates in the field, make it very likely that this is the IR counterpart of X1323-619. (C) 1995 American Astronomical Society. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. RP SMALE, AP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 668,GREENBELT,MD 20771, USA. NR 20 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1995 VL 110 IS 3 BP 1292 EP 1294 DI 10.1086/117603 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700028 ER PT J AU GOLDSTEIN, RM GOLDSTEIN, SJ AF GOLDSTEIN, RM GOLDSTEIN, SJ TI FLUX OF MILLIMETRIC SPACE DEBRIS SO ASTRONOMICAL JOURNAL LA English DT Article AB In 21.4 hr of zenith radar observations on 4 days at 8510 MHz, we found 831 particles with altitudes between 177 and 1662 km. From the duration of the echoes and the angular size (0.030 degrees) of the antenna beam 157 particles were identified as passing through the side lobes and not through the main beam. Our analysis is based on the 674 particles that did not broaden the beam. On the assumptions that these particles went through the main beam, their radar cross sections vary between 0.02 and 260 mm(2), and their radial velocities vary between +/-700 m/s. if they are conducting spheres, their diameters lie between 2 and 18 mm. If not, they must be larger. The flux of these particles, that is the number per km(2) day, was determined in 100 km intervals. The maximum flux, 3.3 particles per km(2) day, occurs at 950 km altitude. The small and large particles are not well mixed. The largest particles occur beyond 1000 km and middle-sized particles are missing below 300 km. if the earth's atmosphere caused the smallest particles to lose energy from initial orbits identical to those of the large particles, the orbits would have lower eccentricity at low altitudes. We find a larger eccentricity for the inner particles, and conclude that two or more populations are present. (C) 1995 American Astronomical Society. C1 UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. RP GOLDSTEIN, RM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1995 VL 110 IS 3 BP 1392 EP 1396 DI 10.1086/117612 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700037 ER PT J AU BURATTI, BJ DUNBAR, RS TEDESCO, EF GIBSON, J MARCIALIS, RL WONG, F BENNETT, S DOBROVOLSKIS, A AF BURATTI, BJ DUNBAR, RS TEDESCO, EF GIBSON, J MARCIALIS, RL WONG, F BENNETT, S DOBROVOLSKIS, A TI MODELING PLUTO-CHARON MUTUAL EVENTS .2. CCD OBSERVATIONS WITH THE 60 IN TELESCOPE AT PALOMAR MOUNTAIN SO ASTRONOMICAL JOURNAL LA English DT Article ID PHYSICAL PARAMETERS; ALBEDO; SYSTEM; SURFACE AB We present observations of 15 Pluto-Charon mutual events which were obtained with the 60 in. telescope at Palomar Mountain Observatory. A CCD camera and Johnson V filter were used for the observations, except for one event that was observed with a Johnson B filter, and another event that was observed with a Gunn R filter. We observed two events in their entirety, and three pairs of complementary mutual occultation-transit events. (C) 1995 American Astronomical Society. C1 CALTECH,PALOMAR OBSERV,PASADENA,CA 91109. UNIV CALIF SANTA CRUZ,NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BURATTI, BJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR 183-501,PASADENA,CA 91109, USA. NR 30 TC 10 Z9 10 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1995 VL 110 IS 3 BP 1405 EP 1419 DI 10.1086/117614 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700039 ER PT J AU WILLIAMS, JG AF WILLIAMS, JG TI PLANETARY-INDUCED NUTATION OF THE EARTH - DIRECT TERMS SO ASTRONOMICAL JOURNAL LA English DT Article ID INNER CORE DYNAMICS; FORCED NUTATIONS; MOTION; EPHEMERIDES AB Small torques by the planets can alter the direction of the Earth's rotation axis in space. These direct planetary-induced nutations have been computed using a numerical technique. 62 nutation terms with periods between 0.2 and 883 yr are presented. The maximum nutation is 0.5 marcsec. Also given are planetary-induced rates and accelerations of precession and obliquity. (C) 1995 American Astronomical Society. RP WILLIAMS, JG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 24 TC 14 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 SEP PY 1995 VL 110 IS 3 BP 1420 EP 1426 DI 10.1086/117615 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RR927 UT WOS:A1995RR92700040 ER PT J AU SCHOENFELD, WG CHANG, ES GELLER, M JOHANSSON, S NAVE, G SAUVAL, AJ AF SCHOENFELD, WG CHANG, ES GELLER, M JOHANSSON, S NAVE, G SAUVAL, AJ TI HIGH-EXCITATION RYDBERG LEVELS OF FE-I FROM THE ATMOS SOLAR SPECTRUM AT 2.5 AND 7 MU-M SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE LINES, IDENTIFICATION; ATOMIC DATA; SUN, INFRARED; LINES, PROFILES; SUN, PHOTOSPHERE ID FOURIER-TRANSFORM; LINES; SPECTROSCOPY; IRON AB The quadrupole-polarization theory has been applied to the 3d(6)4s(D-6)4f and 5g subconfigurations of Fe I by a parametric fit, and the fitted parameters are used to predict levels in the 6g and 6h subconfigurations. Using the predicted values, we have computed the 4f-6g and 5g-6h transition arrays and made identifications in the ATMOS infrared solar spectrum. The newly identified 6g and 6h levels, based on ATMOS wavenumbers, are combined with the 5g levels and found to agree with the theoretical values with a root mean-squared-deviation of 0.042 cm(-1). Our approach yields a polarizability of 28.07 a(o)(3) and a quadrupole moment of 0.4360 +0.0010 ea(o)(2) for Fe II, as well as an improved ionization potential of 63737.700 +/- 0.010 cm(-1) for Fe I. C1 UNIV MASSACHUSETTS, DEPT PHYS & ASTRON, AMHERST, MA 01003 USA. JET PROP LAB, ATMOSPHER & COMETARY SCI SECT, PASADENA, CA 91109 USA. LUND UNIV, DEPT PHYS, S-22362 LUND, SWEDEN. LUND OBSERV, S-22100 LUND, SWEDEN. OBSERV ROYAL BELGIQUE, B-1180 BRUSSELS, BELGIUM. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. NR 19 TC 14 Z9 14 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1995 VL 301 IS 2 BP 593 EP 601 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RW136 UT WOS:A1995RW13600025 ER PT J AU BARRETT, P SCHLEGEL, E DEJAGER, OC CHANMUGAM, G AF BARRETT, P SCHLEGEL, E DEJAGER, OC CHANMUGAM, G TI HIGH-ENERGY GAMMA-RAYS FROM POLARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, OBSERVATIONS; NOVAE, CATACLYSMIC VARIABLES; PARTICLE ACCELERATION ID AM-HERCULIS; VV-PUPPIS; DEGENERATE STARS; ACCRETION COLUMN; POLARIMETRY; E1405-451; DISCOVERY; SPECTRA; MODEL; PHASE AB An analysis of the EGRET phase 1 data was made to search for gamma-ray emission from the magnetic cataclysmic variables V834 Cen, VV Pup, and AM Her. These sources were not detected using either a steady (DC) or a periodic (AC) analysis. These results are consistent with the upper limit detected by the Whipple Observatory at TeV energies, if we assume that gamma-rays are produced, via pion decay, from accelerated protons with a power-law energy spectrum of -2, and are inconsistent with a claimed detection at TeV energies by the Gulmarg Observatory. Our results show that the gamma-ray luminosity from polars is less than 1% of the bolometric luminosity and that the acceleration of particles (protons) to gamma-ray energies by diffusive shocks is probably not important for polars. C1 POTCHEFSTROOM UNIV CHRISTIAN HIGHER EDUC,SPACE RES UNIT,POTCHEFSTROOM 2520,SOUTH AFRICA. LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70808. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NR 30 TC 1 Z9 1 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1995 VL 450 IS 1 BP 334 EP 338 DI 10.1086/176143 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RQ577 UT WOS:A1995RQ57700032 ER PT J AU SCHNEIDER, NM TRAUGER, JT AF SCHNEIDER, NM TRAUGER, JT TI THE STRUCTURE OF THE IO TORUS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLANETS AND SATELLITES, JUPITER, IO; PLASMAS; VIDEOTAPES ID PLASMA TORUS; JOVIAN MAGNETOSPHERE; INNER MAGNETOSPHERE; LO TORUS; JUPITER; ASYMMETRY; VARIABILITY; EMISSION; IMAGES; SODIUM AB New high-quality images of the Io plasma torus allow improved measurements of its structure. We have analyzed almost 80 images of [S II] 6731 Angstrom emissions from S+ revealing interesting structures in the radial, local time, latitudinal, and longitudinal dimensions. The averaged radial profile shows a maximum intensity at 5,71R(J), significantly inside Io's orbit at 5.91R(J). The radial structure is offset 0.14R(J) toward the dawn (east) side of Jupiter, and emissions are similar to 20% brighter on the dusk (west.) In the latitudinal dimension, the plasma torus ''illuminates'' the centrifugal equator of Jupiter's magnetic field. The centrifugal equator derived from our data is generally consistent with the ''O6 + current sheet'' field model derived by spacecraft measurements, but some unexplained differences stand out. We find lower ion temperatures in the ''active sector,'' perhaps a direct consequence of higher emission rates there. We also report the puzzling result that the ribbon (the most prominent plasma feature encircling Jupiter) is not centered on Jupiter's rotation axis or on the offset magnetic axis. The origin of the structure we describe here remains enigmatic. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SCHNEIDER, NM (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,CAMPUS BOX 392,BOULDER,CO 80309, USA. OI SCHNEIDER, NICHOLAS/0000-0001-6720-5519 NR 48 TC 80 Z9 80 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1995 VL 450 IS 1 BP 450 EP 462 DI 10.1086/176155 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RQ577 UT WOS:A1995RQ57700044 ER PT J AU GREEN, S AF GREEN, S TI COLLISIONAL EXCITATION OF INTERSTELLAR SULFUR-DIOXIDE SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE MOLECULAR PROCESSES ID MOLECULES; ATOMS AB Rotational excitation rates for sulfur dioxide in collisions with He atoms at temperatures from 25 to 125 K, obtained from theoretical calculations by Palma (1987), have been reanalyzed in terms of corrected asymmetric top rotational wavefunctions. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 7 TC 20 Z9 20 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1995 VL 100 IS 1 BP 213 EP 216 DI 10.1086/192216 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RQ010 UT WOS:A1995RQ01000011 ER PT J AU HAKKILA, J VO, V MEEGAN, C HORACK, J FISHMAN, G HARTMANN, D PENDLETON, G BRIGGS, M PACIESAS, W AF HAKKILA, J VO, V MEEGAN, C HORACK, J FISHMAN, G HARTMANN, D PENDLETON, G BRIGGS, M PACIESAS, W TI SELECTION EFFECTS AND TESTS OF REPETITION (CLUSTERING) IN THE BATSE 1B CATALOG SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article DE GAMMA-RAY BURSTS; REPETITION ID GAMMA-RAY BURSTS AB A ''repeater statistic'' (derived from the two-point angular correlation function and accounting for location errors) is used to identify constraints on the rate of burst repetition from the BATSE 1B catalog. Because of the anisotropic sky exposure, repeating sources should create additional effects in the large-scale distribution of close burst pairs. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. CLEMSON UNIV, CLEMSON, SC USA. UNIV ALABAMA, HUNTSVILLE, AL 35899 USA. RP HAKKILA, J (reprint author), MANKATO STATE UNIV, MANKATO, MN 56001 USA. RI Horack, John/J-6670-2016 NR 13 TC 3 Z9 3 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 23 EP 26 DI 10.1007/BF00658581 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700006 ER PT J AU KOUVELIOTOU, C AF KOUVELIOTOU, C TI SGR ACTIVITY AND GLOBAL CHARACTERISTICS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE SOFT GAMMA REPEATERS ID GAMMA-RAY TRANSIENT; 5 MARCH 1979; HIGH-ENERGY TRANSIENT; BURST; PERIODICITY; EVENT AB Of the over one thousand detected cosmic transient gamma-ray sources, only three are known to have exhibited recurrent activity. Apart from their recurrent nature, these events differ from the majority of bursts in that they are of much shorter duration and have relatively soft spectra. They can thus be considered as a distinct class of objects - the Soft Gamma Repeaters (SGRs). Their embryonic sky distribution suggests that they are galactic objects. The absence of detection of new sources in the 4.0 years of BATSE operation, together with the BATSE detection of the reactivation of two of the three already known SGRs, indicates that these objects are rare. We present here a short review of the overall SGR activity and their global characteristics. RP KOUVELIOTOU, C (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812, USA. NR 30 TC 18 Z9 18 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 SEP PY 1995 VL 231 IS 1-2 BP 49 EP 56 DI 10.1007/BF00658587 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700012 ER PT J AU BARING, MG HARDING, AK AF BARING, MG HARDING, AK TI PHOTON SPLITTING IN SOFT GAMMA-REPEATERS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE SOFT GAMMA REPEATERS; NEUTRON STARS; MAGNETIC FIELDS; GAMMA-RAYS ID RAY BURSTS; SPECTRA AB The exotic quantum process of photon splitting gamma --> gamma gamma has great potential to explain the softness of emission in soft gamma repeaters (SGRs) if they originate in neutron stars with surface fields above the quantum critical field B-cr = 4.413x10(13) Gauss. Splitting becomes prolific at such field strengths: its principal effect is to degrade photon energies, initiating a cascade that softens gamma-ray spectra. Uniform field cascade calculations have demonstrated that emission could be softened to the observed SGR energies for fields exceeding about 10(14) Gauss. Recently, we have determined splitting attenuation lengths and maximum energies for photon escape in neutron star environments including the effects of magnetospheric dipole field geometry. Such escape energies epsilon(esc) suitably approximate the peak energy of the emergent spectrum, and in this paper we present results for epsilon(esc) as a function of photon emission angles for polar cap and equatorial emission regions. The escape energy is extremely insensitive to viewing perspective for equatorial emission, arguing in favour of such a site for the origin of SGR activity. RP BARING, MG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 665,GREENBELT,MD 20771, USA. RI Harding, Alice/D-3160-2012 NR 11 TC 12 Z9 12 U1 0 U2 1 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 SEP PY 1995 VL 231 IS 1-2 BP 77 EP 80 DI 10.1007/BF00658591 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700016 ER PT J AU WALLYN, P MAHONEY, WA CORBEL, S CAO, Y DUROUCHOUX, P VILHU, O AF WALLYN, P MAHONEY, WA CORBEL, S CAO, Y DUROUCHOUX, P VILHU, O TI MILLIMETER AND INFRARED OBSERVATIONS OF SGR1806-20 SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA-RAY, BURSTS; ISM, INDIVIDUAL (G10.0-0.3); SUPERNOVA REMNANTS AB We present CO(1-0) observations toward the soft gamma-ray repeater SGR 1806-20. We discuss the implications on the distance to the X-ray counterpart: AX 1805.7-2025. We also present an upper limit at lambda = 1.3 mm for the thermal emission from dust and high resolution IRAS maps of the region. SGR 1806-20 is very likely associated with the H II complex W31. The G10.0-0.3 supernova remnant (SNR) could be expanding in the very low density region produced by the wind of the bright O9-B2 star recently detected. C1 CALTECH,SPACE RADIAT LAB,PASADENA,CA 91125. CE SACLAY,SERV ASTROPHYS,DAPNIA,F-91191 GIF SUR YVETTE,FRANCE. RP WALLYN, P (reprint author), CALTECH,JET PROP LAB,169-327,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 7 Z9 7 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 89 EP 92 DI 10.1007/BF00658594 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700019 ER PT J AU NORRIS, JP AF NORRIS, JP TI GAMMA-RAY BURSTS - THE TIME-DOMAIN SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article DE GAMMA-RAY BURSTS; TIME PROFILES AB Temporal aspects of the gamma-ray burst phenomenon are reviewed in a hierarchical schema. The macrocosm - burst profiles taken as a whole - is fairly well characterized. The bimodal duration distribution can be framed in terms of discretization of pulse structures. The average burst envelope is slightly asymmetric, an aspect possibly related to spectral softening. Burst durations are longer for dim BATSE bursts, an effect explainable by either cosmic time dilation or a luminosity function governed by special relativistic beaming, or a combination. GeV emission, persisting up to thousands of seconds after burst cessation at keV-MeV energies is one of the most challenging features of bursts. On the timescale of pulses structures (the ''mesocosm''), some properties mirror the macrocosm: rise/decay asymmetry; wider pulses and longer intervals between pulses in dim bursts than in bright ones; and the tendency of pulses to soften with time. A central clue to the burst mechanism may be the organization in time and energy, manifest as pulses, for both long and short bursts. Burst profiles appear to be well represented by pulses, accounting for the vast majority of emission in the BATSE energy band. In the microcosm, existence of a higher frequency component - with properties possibly unlike those of pulses - has not been well addressed. RP NORRIS, JP (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 28 TC 10 Z9 10 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 95 EP 102 DI 10.1007/BF00658595 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700020 ER PT J AU MATZ, SM GROVE, JE JOHNSON, WN KURFESS, JD SHARE, GH FISHMAN, GJ MEEGAN, CA AF MATZ, SM GROVE, JE JOHNSON, WN KURFESS, JD SHARE, GH FISHMAN, GJ MEEGAN, CA TI BATSE OSSE RAPID BURST RESPONSE SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA-RAY BURSTS; COUNTERPARTS; INSTRUMENTATION AB The BATSE and OSSE instrument teams have modified flight software to promptly (within 2 min of trigger) slew the OSSE detectors to burst locations determined on-board by BATSE. This enables OSSE to make sensitive searches for prompt and delayed post-burst line and continuum emission above 50 keV. In the best cases our sensitivity will be more than an order of magnitude better than any other search in this energy range. We expect to slew to 1-2 bursts per month, based on the OSSE FOV and BATSE event rate. Detections or limits from continued operation of this system may provide significant constraints on burst models. As an example of the observations made using this system, we present preliminary limits for post-burst emission from GRB 950223 on several time scales. C1 USN,RES LAB,WASHINGTON,DC 20375. NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RI Johnson, Neil/G-3309-2014 NR 11 TC 0 Z9 0 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 SEP PY 1995 VL 231 IS 1-2 BP 127 EP 130 DI 10.1007/BF00658601 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700026 ER PT J AU TEEGARDEN, BJ AF TEEGARDEN, BJ TI THE ENERGY-SPECTRA OF GAMMA-RAY BURSTS - OLD PUZZLES, RECENT ANALYSIS AND NEW RESULTS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR ID CYCLOTRON; GINGA AB Gamma-ray burst spectroscopy has at times been thought of as the key to understanding these mysterious events, and at others as a source of disappointment and confusion. Early spectral measurements contained evidence for cyclotron-line-like absorption and emission features. These results were the main anchor for the galactic neutron star paradigm for the origin of gamma-ray bursts. Ginga provided striking confirmation with evidence in three bursts for cyclotron absorption with both first and second harmonics present. The absorption line energies were consistent with the teragauss magnetic fields expected for neutron stars. The BATSE experiment on CGRO has dealt a severe blow to this paradigm. BATSE has found no evidence for the expected galactic anisotropy and also no evidence for cyclotron lines. The exact degree of inconsistency between BATSE and earlier GRB line results remains a complicated and unresolved question. In general, burst spectra display a wide variety of both spectral and temporal behavior. In essentially all bursts where spectral measurements are possible, the spectrum evolves during the burst. This spectral complexity and variability has presented researchers with a challenging task. At the present time, only the broadest correlations and characterizations are in hand. This paper will; 1) give a brief historical overview of GRB spectroscopic measurements and 2) provide a summary of the current observational situation with emphasis on the BATSE/Ginga controversy. RP TEEGARDEN, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 16 TC 4 Z9 4 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 SEP PY 1995 VL 231 IS 1-2 BP 137 EP 144 DI 10.1007/BF00658603 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700028 ER PT J AU BAND, DL FORD, LA MATTESON, JL PALMER, DM TEEGARDEN, BJ BRIGGS, MS PENDLETON, GN PREECE, RD PACIESAS, WS AF BAND, DL FORD, LA MATTESON, JL PALMER, DM TEEGARDEN, BJ BRIGGS, MS PENDLETON, GN PREECE, RD PACIESAS, WS TI THE BATSE SEARCH FOR ABSORPTION-LINES SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR ID GAMMA-RAY BURSTS; CYCLOTRON AB No absorption lines between 15 and 100 keV have been detected in burst spectra accumulated by BATSE. Almost 250 bursts have been inspected visually, and a computerized search has begun. Our simulations show that BATSE could indeed detect Lines similar to those observed by Ginga in strong bursts, and our tests of the detectors' actual capabilities demonstrate they function as understood. The apparent discrepancy between BATSE and Ginga is not yet compelling, and therefore the BATSE nondetections do not invalidate the Ginga detections. Nonetheless, the absence of BATSE line detections indicates a low line-occurrence frequency. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20770. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP BAND, DL (reprint author), UNIV CALIF SAN DIEGO,CASS,LA JOLLA,CA 92093, USA. OI Preece, Robert/0000-0003-1626-7335 NR 14 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 SEP PY 1995 VL 231 IS 1-2 BP 145 EP 148 DI 10.1007/BF00658604 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700029 ER PT J AU PALMER, DM TEEGARDEN, BJ SEIFERT, H GEHRELS, N CLINE, TL RAMATY, R OWENS, A HURLEY, K MADDEN, N PEHL, R AF PALMER, DM TEEGARDEN, BJ SEIFERT, H GEHRELS, N CLINE, TL RAMATY, R OWENS, A HURLEY, K MADDEN, N PEHL, R TI FIRST RESULTS FROM THE TGRS HIGH-RESOLUTION GRB SPECTROMETER SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GRBS; HIGH RESOLUTION SPECTROSCOPY; SOLID STATE DETECTORS ID GAMMA-RAY BURSTS; CYCLOTRON AB The Transient Gamma Ray Spectrometer (TGRS) is a 215 cm(3) passively-cooled germanium detector designed primarily to study spectral features of gamma ray bursts. Since shortly after its launch on 1994 Nov. 1 it has been producing high-resolution spectra of GRBs and solar flares. Some of these spectra are presented here. Although it has not yet detected any line features in GRBs-none were expected so early in the mission-several bursts have been seen simultaneously by TGRS, the Konus instruments on the same spacecraft, and the BATSE instrument on Compton GRO. A comparison of the spectra obtained by these various instruments, as presented here, may resolve the question of whether line features actually exist, and if so provide detailed spectroscopy to determine their physical origin. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV CALIF BERKELEY,BERKELEY,CA 94720. UNIV LEICESTER,LEICESTER LE1 7RH,LEICS,ENGLAND. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. RP PALMER, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012 NR 4 TC 1 Z9 1 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 SEP PY 1995 VL 231 IS 1-2 BP 161 EP 164 DI 10.1007/BF00658608 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700033 ER PT J AU BARING, MG AF BARING, MG TI GAMMA-RAY BURST ENERGY-SPECTRA - THEORETICAL-MODELS, OLD AND NEW SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA-RAY BURSTS; NEUTRON STARS; COSMOLOGY; GAMMA-RAYS ID STRONG MAGNETIC-FIELDS; CYCLOTRON LINES; RESONANT SCATTERING; COMPTON-SCATTERING; ANNIHILATION LINES; PAIR ANNIHILATION; RADIATION; ABSORPTION; FEATURES; FIREBALLS AB The modelling of gamma-ray burst (GRB) spectra has considerable potential for increasing the understanding of these enigmatic sources. A diversity of ideas and analyses has been generated over the last two decades to explain line features and continuum shapes, encompassing both older galactic neutron star and ''new age'' cosmological source models. This paper reviews some of the highlights of these studies, discussing the merits and limitations of various ideas, and in particular their compatibility with the observational data. The first focus will be on continuum models for GRBs, which include optically thin synchrotron emission and resonant Compton upscattering near galactic neutron stars, while the synchrotron and non-magnetic inverse Compton scattering mechanisms are prominent in the less well-developed cosmological scenarios. Line formation scenarios will then be discussed, in particular the scattering model for producing cyclotron features, which remains the only viable explanation for the Ginga observations of double lines. Absorption-like line production in cosmological burst models is generally difficult, though interesting notions such as femtolensing interference patterns have been proffered. RP BARING, MG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 665,GREENBELT,MD 20771, USA. NR 54 TC 5 Z9 5 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 169 EP 176 DI 10.1007/BF00658610 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700035 ER PT J AU KARGATIS, VE LIANG, EP AF KARGATIS, VE LIANG, EP TI SPECTRAL EVOLUTION OF GRB PULSES SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article DE GAMMA-RAYS, BURSTS; DATA ANALYSIS AB We perform time-resolved spectral analysis on 26 multi-pulse BATSE GRBs. By fixing two parameters of a a-parameter fit to the time-integrated values, we achieve a robust spectral hardness measure and physical fluxes. 28 pulse decay phases in 15 GRBs show significant correlation between peak power energy and instantaneous energy flux (characterized by F-E proportional to E(p)(1.7)). We compare peak energy fluxes, peak hardnesses, and pulse durations and separation for pulse pairs in our sample. There may be some indication of a ''recovery timescale'' for the bursters' energy source or environment. C1 NASA, MSFC, HUNTSVILLE, AL 35812 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UAH, HUNTSVILLE, AL USA. UNIV CALIF SAN DIEGO, CASS, LA JOLLA, CA 92093 USA. RP KARGATIS, VE (reprint author), RICE UNIV, DEPT SPACE PHYS & ASTRON, POB 1892, HOUSTON, TX 77251 USA. NR 9 TC 19 Z9 20 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 177 EP 180 DI 10.1007/BF00658611 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700036 ER PT J AU DINGUS, BL AF DINGUS, BL TI EGRET OBSERVATIONS OF GREATER-THAN-30-MEV EMISSION FROM THE BRIGHTEST BURSTS DETECTED BY BATSE SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GEV, GAMMA-RAY BURSTS AB EGRET on the Compton Gamma Ray Observatory has detected 5 gamma-ray bursts above 30 MeV. The sub-MeV emission, as detected by BATSE, for these 5 bursts has the largest fluence, F, and peak intensity, I, of any of the BATSE detected bursts within the EGRET field of view. The BATSE data reported in the 2B catalog and the EGRET exposure, E, are combined to select additional bursts with large F x E and I x E. The EGRET data for these bright BATSE bursts are searched for prompt, as well as delayed, emission above 30 MeV. The average properties of the >30 MeV emission are obtained by adding the EGRET data from the 5 bursts. On average the fluence is greater than 15% of the fluence detected by BATSE below an MeV, and the average spectrum is flatter than the spectrum from 1-30 MeV. RP DINGUS, BL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,USRA,CODE 662,GREENBELT,MD 20771, USA. OI Dingus, Brenda/0000-0001-8451-7450 NR 15 TC 69 Z9 70 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 SEP PY 1995 VL 231 IS 1-2 BP 187 EP 190 DI 10.1007/BF00658613 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700038 ER PT J AU BAND, DL RYDER, S FORD, LA MATTESON, JL PALMER, DM TEEGARDEN, BJ BRIGGS, MS PACIESAS, WS PENDLETON, GN PREECE, RD AF BAND, DL RYDER, S FORD, LA MATTESON, JL PALMER, DM TEEGARDEN, BJ BRIGGS, MS PACIESAS, WS PENDLETON, GN PREECE, RD TI THE EVALUATION OF BATSE LINE CANDIDATES SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR AB We evaluated the significance of the line candidates identified by the visual search of burst spectra from BATSE's spectroscopy detectors. None of the candidates satisfy the detection criteria: an F-test probability less than 10(-4) for a feature in one detector and consistency among the detectors which viewed the burst. Most of the candidates are not very significant, and are likely to be fluctuations. Because of the expectation of finding absorption lines, the search was biased towards absorption features. We do not have a quantitative measure of the completeness of the search which would form the basis of a comparison with previous missions. Therefore a more objective computerized search has begun. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20770. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP BAND, DL (reprint author), UNIV CALIF SAN DIEGO,CASS,LA JOLLA,CA 92093, USA. OI Preece, Robert/0000-0003-1626-7335 NR 13 TC 0 Z9 0 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 SEP PY 1995 VL 231 IS 1-2 BP 203 EP 206 DI 10.1007/BF00658617 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700042 ER PT J AU HURLEY, K SOMMER, M CLINE, T BOER, M NIEL, M AF HURLEY, K SOMMER, M CLINE, T BOER, M NIEL, M TI ULYSSES OBSERVATIONS OF COSMIC GAMMA-RAY BURSTS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR AB We review the current status of the Ulysses mission and summarize the results to date of the GRB experiment. This instrument detects bursts at the rate of about one every 3.5 days, and the localization data are being disseminated rapidly via the BACO- DINE and NMSU networks. The mission should operate through 2001, and future missions to Mars starting in 1996 will complete the 3rd Interplanetary Network. C1 MAX PLANCK INST EXTRATERR PHYS,GARCHING,GERMANY. GODDARD SPACE FLIGHT CTR,GREENBELT,MD. CESR,TOULOUSE,FRANCE. RP HURLEY, K (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. OI Boer, Michel/0000-0001-9157-4349 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 SEP PY 1995 VL 231 IS 1-2 BP 227 EP 230 DI 10.1007/BF00658621 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700046 ER PT J AU BARTHELMY, SD BUTTERWORTH, P CLINE, TL GEHRELS, N FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA AF BARTHELMY, SD BUTTERWORTH, P CLINE, TL GEHRELS, N FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA TI BACODINE, THE REAL-TIME BATSE GAMMA-RAY BURST COORDINATES DISTRIBUTION NETWORK SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR AB The celestial coordinates of gamma-ray burst sources observed with BATSE on GRO are automatically determined and distributed in real time to members of the global scientific community. These data are now being used by more than 20 operations to enable searches for associated transients in a variety of other wavelength or energy regimes to identify the burst source objects. The minimum total delay time from the onset of a burst to the receipt of its coordinates by distant experimenters can be under 4 sec, less than the duration of a typical GRB, and the maximum total delay is 7 sec, or longer, depending on the distribution method. Some improvements to the BACODINE system and a summary of the follow-up observations made by some of the sites are given. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP BARTHELMY, SD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012; Barthelmy, Scott/D-2943-2012 NR 2 TC 33 Z9 34 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 SEP PY 1995 VL 231 IS 1-2 BP 235 EP 238 DI 10.1007/BF00658623 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700048 ER PT J AU MCNAMARA, BJ HARRISON, TE RYAN, J KIPPEN, RM BENNETT, K HANLON, LO GREINER, J FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA AF MCNAMARA, BJ HARRISON, TE RYAN, J KIPPEN, RM BENNETT, K HANLON, LO GREINER, J FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA TI THE FIRST 2 YEARS OF THE BATSE COMPTEL NMSU GRB RAPID RESPONSE NETWORK SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA-RAY BURSTS; OPTICAL AND RADIO OBSERVATIONS AB The BATSE/COMPTEL/NMSU Rapid Response Network (RRN) was formed to provide rapid follow-up of gamma-ray bursts imaged by the COMPTEL instrument on the Compton Gamma-Ray Observatory. The RRN consists of approximate to 22 professional observatories located around the world spanning both northern and southern hemispheres. Also included in the RRN is the Airforce GEODSS network. The goal of the RRN is to perform optical and radio observations of COMPTEL error boxes as soon after the burst as possible. We present results from the first two years of operation of this network. C1 UNIV NEW HAMPSHIRE,CTR SPACE SCI,DURHAM,NH 03824. ESTEC,DIV ASTROPHYS,2200 AG NOORDWIJK,NETHERLANDS. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35899. RP MCNAMARA, BJ (reprint author), NEW MEXICO STATE UNIV,DEPT 4500,BOX 30001,LAS CRUCES,NM 88003, USA. NR 5 TC 5 Z9 5 U1 0 U2 1 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 SEP PY 1995 VL 231 IS 1-2 BP 251 EP 254 DI 10.1007/BF00658626 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700051 ER PT J AU AKERLOF, C ABLES, E BARTHELMY, S BIONTA, R CLINE, T FERGUSON, D FISHMAN, G GEHRELS, N KOUVELIOTOU, C LEE, B MEEGAN, C OTT, L PARK, HS PARKER, E AF AKERLOF, C ABLES, E BARTHELMY, S BIONTA, R CLINE, T FERGUSON, D FISHMAN, G GEHRELS, N KOUVELIOTOU, C LEE, B MEEGAN, C OTT, L PARK, HS PARKER, E TI RESULTS FROM GROCSE, A REAL-TIME SEARCH FOR THE OPTICAL COUNTERPARTS OF GAMMA-RAY BURSTS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR AB The GROCSE Collaboration (Gamma-Ray Optical Counterpart Search Experiment) has been operating a rapid response camera since January 1994 in an attempt to capture optical images of GRB events. This detector has a response time of 15 seconds and a limiting magnitude of 8. A second generation detector is now under construction which is expected to eventually reach m(v) similar or equal to 15 with a 5 second exposure. C1 LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. EARTHWATCH INC,LIVERMORE,CA 94550. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP AKERLOF, C (reprint author), UNIV MICHIGAN,DEPT PHYS,ANN ARBOR,MI 48109, USA. RI Barthelmy, Scott/D-2943-2012; Gehrels, Neil/D-2971-2012 NR 5 TC 4 Z9 4 U1 0 U2 1 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 SEP PY 1995 VL 231 IS 1-2 BP 255 EP 258 DI 10.1007/BF00658627 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700052 ER PT J AU GREEN, DA DESSENNE, CAC WARNER, PJ TITTERINGTON, DJ WALDRAM, EM BARTHELMY, SD CLINE, TL GEHRELS, N PALMER, D FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA AF GREEN, DA DESSENNE, CAC WARNER, PJ TITTERINGTON, DJ WALDRAM, EM BARTHELMY, SD CLINE, TL GEHRELS, N PALMER, D FISHMAN, GJ KOUVELIOTOU, C MEEGAN, CA TI A SEARCH FOR PROMPT RADIO-EMISSION FROM GRBS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GRB RADIO COUNTERPARTS; BACODINE AB The Cambridge Low Frequency Synthesis Telescope (CLFST) is being used to search for prompt radio emission from GRBs at 151 MHz. For this search a special observing mode has recently been developed; the antennas of the CLFST are split into seven groups which are spaced about 30 degrees apart. When triggered by the real-time signals from the BACODINE system the antennas are slewed to the GRB position, with data being sampled at 1.5 or 3-s intervals. The antennas slew at about 10 degrees per minute, so that an appreciable fraction of the sky can be accessed on timescales of a few minutes - any prompt radio emission from a GRB might be delayed by this timescale due to propagation effects. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP GREEN, DA (reprint author), UNIV CAMBRIDGE,CAVENDISH LAB,MULLARD RADIO ASTRON OBSERV,MADINGLEY RD,CAMBRIDGE CB3 0HE,ENGLAND. RI Gehrels, Neil/D-2971-2012; Green, David/E-9609-2010; Barthelmy, Scott/D-2943-2012 OI Green, David/0000-0003-3189-9998; NR 8 TC 5 Z9 5 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 281 EP 284 DI 10.1007/BF00658632 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700057 ER PT J AU LUGINBUHL, CB VRBA, FJ HUDEC, R HARTMANN, D HURLEY, K BOER, M NIEL, M SOMMER, M KOUVELIOTOU, C MEEGAN, C FISHMAN, G AF LUGINBUHL, CB VRBA, FJ HUDEC, R HARTMANN, D HURLEY, K BOER, M NIEL, M SOMMER, M KOUVELIOTOU, C MEEGAN, C FISHMAN, G TI PRELIMINARY-RESULTS OF OPTICAL SEARCHES OF IPN3 LOCALIZATIONS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GRB OPTICAL COUNTERPARTS; OPTICAL TRANSIENTS AB We present preliminary results from deep optical searches of small (less than or equal to similar to-5 arcmin(2)) GRB error boxes determined using the Third Interplanetary Network (IPN3). Two of these fields also have been found to have historical OT events located within the IPN3 error boxes. We compare the preliminary results of these searches to those reported for the larger IPN1 error boxes. The small size of the IPN3 error boxes should allow a test of the hypothesis suggested by the IPN1 study that there are excess QSOs associated with the GRB fields. C1 ASTRON INST ONDREJOV,CR-25165 ONDREJOV,CZECH REPUBLIC. CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. CTR ETUD SPATIALE RAYONNEMENTS,TOULOUSE,FRANCE. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL. RP LUGINBUHL, CB (reprint author), USN OBSERV,FLAGSTAFF STN,POB 1149,FLAGSTAFF,AZ 86002, USA. RI Hudec, Rene/G-9018-2014; OI Boer, Michel/0000-0001-9157-4349 NR 7 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 SEP PY 1995 VL 231 IS 1-2 BP 289 EP 292 DI 10.1007/BF00658634 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700059 ER PT J AU PALMER, DM CLINE, TL LAROS, JG HURLEY, K FISHMAN, GJ KOUVELIOTOU, C AF PALMER, DM CLINE, TL LAROS, JG HURLEY, K FISHMAN, GJ KOUVELIOTOU, C TI VLA OBSERVATIONS OF GRB ERROR BOXES SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GRBS-RADIO COUNTERPART SEARCHES ID RADIO AB Very Large Array (VLA) radio observations of precisely-located GRB error boxes have been performed to search for fading and quiescent emission associated with gamma-ray bursts. These observations were made as quickly as 23 hours and as late as 13 years after the time of the burst. Our measurements presented here have found GRB error boxes to be empty of sources to the 80 mu Jy level (lambda = 3.6 cm) at 9 months, to 1 mJy (20 cm) at 9 days, and probably to 5 mJy (20 cm) at 23 hours after the bursts. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV ARIZONA,TUCSON,AZ 85721. UNIV CALIF BERKELEY,BERKELEY,CA 94720. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35899. NR 7 TC 5 Z9 5 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 315 EP 318 DI 10.1007/BF00658640 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700065 ER PT J AU HUDEC, R SPURNY, P FLORIAN, J BOCEK, J TICHY, M TICHA, J VYSKCIL, L WENZEL, W BARTHELMY, S CLINE, T GEHRELS, N FISHMAN, G KOUVELIOTOU, C MEEGAN, C MUTAFOV, A HOVORKA, F AF HUDEC, R SPURNY, P FLORIAN, J BOCEK, J TICHY, M TICHA, J VYSKCIL, L WENZEL, W BARTHELMY, S CLINE, T GEHRELS, N FISHMAN, G KOUVELIOTOU, C MEEGAN, C MUTAFOV, A HOVORKA, F TI EUROPEAN OBSERVATION NETWORK - FIRST EXPERIENCE WITH BACODINE TRIGGERS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA RAY, BURSTS; ASTRONOMICAL PHOTOGRAPHY; CCD IMAGING AB We present preliminary results obtained with the European Observation Network. This network consists of 9 observatories in the Czech Republic, Germany and Bulgaria and has been involved in the BACODINE activities since April 1, 1994. We also discuss related problems such as the background of unknown variable stars and suggest a strategy for work in this area. C1 KLET OBSERV,CR-37001 CESKE BUDEJOVICE,CZECH REPUBLIC. UPICE OBSERV,CR-54232 UPICE,CZECH REPUBLIC. STERNWARTE SONNEBERG,D-96515 SONNEBERG,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ASTRON OBSERV,BU-1504 SOFIA,BULGARIA. OBSERV HRADEC KRALOVE,CR-50008 HRADEC KRALOVE,CZECH REPUBLIC. RP HUDEC, R (reprint author), ACAD SCI CZECH REPUBL,INST ASTRON,CR-25165 ONDREJOV,CZECH REPUBLIC. RI Barthelmy, Scott/D-2943-2012; Gehrels, Neil/D-2971-2012; Spurny, Pavel/G-9044-2014; Hudec, Rene/G-9018-2014 NR 10 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 SEP PY 1995 VL 231 IS 1-2 BP 335 EP 338 DI 10.1007/BF00658645 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700070 ER PT J AU HAKKILA, J MEEGAN, C HORACK, J PENDLETON, G BRIGGS, M PACIESAS, W EMSLIE, G MALLOZZI, R AF HAKKILA, J MEEGAN, C HORACK, J PENDLETON, G BRIGGS, M PACIESAS, W EMSLIE, G MALLOZZI, R TI CONSTRAINTS ON THE LUMINOSITIES OF GAMMA-RAY BURSTS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article DE GAMMA-RAY BURSTS; LUMINOSITIES; ORIGINS AB Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with Omega = 1 and Lambda = 0, then very few luminosity constraints exist. C1 NASA, MSFC, HUNTSVILLE, AL USA. UNIV ALABAMA, HUNTSVILLE, AL 35899 USA. RP HAKKILA, J (reprint author), MANKATO STATE UNIV, MANKATO, MN 56001 USA. RI Horack, John/J-6670-2016 NR 9 TC 4 Z9 4 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 1995 VL 231 IS 1-2 BP 369 EP 372 DI 10.1007/BF00658652 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700077 ER PT J AU SEIFERT, H TEEGARDEN, BJ PALMER, D GEHRELS, N CLINE, TL RAMATY, R OWENS, A HURLEY, K PEHL, R MADDEN, N AF SEIFERT, H TEEGARDEN, BJ PALMER, D GEHRELS, N CLINE, TL RAMATY, R OWENS, A HURLEY, K PEHL, R MADDEN, N TI STATUS OF THE TRANSIENT GAMMA-RAY SPECTROMETER SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GRBS; HIGH RESOLUTION SPECTROSCOPY; SOLID STATE DETECTORS AB The Transient Gamma-Ray Spectrometer (TGRS) was launched aboard the GGS/WIND spacecraft on November 1, 1994. After several deep space orbits (similar to 2 yrs) WIND will eventually be injected into a halo orbit around the Sun-Earth L(1) point. TGRS consists of a 215 cm(3) high purity n-type Ge crystal which is kept at cryogenic temperatures by a passive radiative cooler. The energy range covered by the instrument is similar to 25-8000 keV with an energy resolution of similar to 2-3 keV. The primary task of TGRS is to perform high resolution spectroscopy of gamma-ray bursts and solar flares. Additional objectives are the study of transient x-ray pulsars and, using an on-board passive occulter, the long-term monitoring of sources such as the Crab and the Galactic Center. Since launch, TGRS has been performing exceedingly well, and all the important experiment parameters such as background levels, gain, and resolution have proven to be very stable. To date, TGRS has detected 27 GRBs and three solar flares. Preliminary analysis of our data also indicates that TGRS is indeed sensitive to sources such as the Crab and the Galactic Center. C1 UNIV LEICESTER,LEICESTER LE1 7RH,LEICS,ENGLAND. UNIV CALIF BERKELEY,BERKELEY,CA 94720. UNIV CALIF BERKELEY,LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. RP SEIFERT, H (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012 NR 5 TC 2 Z9 2 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 SEP PY 1995 VL 231 IS 1-2 BP 475 EP 478 DI 10.1007/BF00658674 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700099 ER PT J AU DESAI, UD PANTAZIS, J SHAH, K AF DESAI, UD PANTAZIS, J SHAH, K TI ROOM-TEMPERATURE SOLID-STATE DETECTORS FOR GAMMA-RAY BURST SPECTROSCOPY SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 29th ESLAB Symposium on Towards the Source of Gamma-Ray Bursts CY APR 26-28, 1995 CL EUROPEAN SPACE RES & TECHNOL CTR, NOORDWIJK, NETHERLANDS SP ESLAB, ESTEC HO EUROPEAN SPACE RES & TECHNOL CTR DE GAMMA RAY BURSTS; SOLID-STATE DETECTORS; INSTRUMENTATION AB We have evaluated several solid state detectors which offer excellent energy resolution at room temperature for soft X-rays. For soft X-rays (< 1 keV to 20 keV), silicon P-intrinsic-N (PIN) and avalanche-mode photodiodes (APD's) have been studied. Using commercially available charge sensitive pre-amplifiers, these photodiodes provide 1 keV resolution without cooling. Their detection efficiencies are limited to about 20 keV and 15 keV, respectively. To overcome this constraint, we have studied thick (1.5 mm) PIN detectors made by Micron Semiconductor Ltd., U.K., as well as compound semiconducting materials with high ''Z'' constituents such as CZT and PbI2. PbI2 allows high detection efficiencies of photons up to 100 keV with detectors 100-300 microns thick. These new detectors offer the capability to study the low-energy spectral evolution of Gamma ray bursts (GRBs). A matrix of these detectors could be used as an image plane detector with moderate spatial resolution for imaging. C1 AMPTEK,BEDFORD,ENGLAND. RMD,WATERTOWN,MA. RP DESAI, UD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 6 TC 2 Z9 2 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 SEP PY 1995 VL 231 IS 1-2 BP 487 EP 491 DI 10.1007/BF00658677 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA TF267 UT WOS:A1995TF26700102 ER PT J AU PUESCHEL, RF ALLEN, DA BLACK, C FAISANT, S FERRY, GV HOWARD, SD LIVINGSTON, JM REDEMANN, J SORENSON, CE VERMA, S AF PUESCHEL, RF ALLEN, DA BLACK, C FAISANT, S FERRY, GV HOWARD, SD LIVINGSTON, JM REDEMANN, J SORENSON, CE VERMA, S TI CONDENSED WATER IN TROPICAL CYCLONE-OLIVER, 8-FEBRUARY-1993 SO ATMOSPHERIC RESEARCH LA English DT Article ID ICE AB On February 8, 1993, the NASA DC-8 aircraft profiled from 10,000 to 37,000 feet (3.1-11.3 km) pressure altitude in a stratified section of tropical cyclone ''Oliver'' over the Coral Sea northeast of Australia. Size, shape and phase of cloud and precipitation particles were measured with a 2-D Greyscale probe. Cloud/precipitation particles changed from liquid to ice as soon as the freezing level was reached near 17,000 feet (5.2 km) pressure altitude. The cloud was completely glaciated at -5 degrees C. There was no correlation between ice particle habit and ambient temperature, In the liquid phase, the precipitation-cloud drop concentration was 4.0 X 10(3) m(-3), the geometric mean diameter D-g = 0.5-0.7 mm, and the liquid water content 0.7-1.9 g m(-3), The largest particles anywhere in the cloud, dominated by fused dendrites at concentrations similar to that of raindrops (2.5 X 10(3) m(-3)) but a higher condensed water content (5.4 g m(-3) estimated) were found in the mixed phase; condensed water is removed very effectively from the mixed layer due to high settling Velocities of the large mixed particles. The highest number concentration (4.9 X 10(4) m(-3)), smallest size (D-g = 0.3-0.4 mm), largest surface area (up to 2.6 X 10(2) cm(2) m(-3) at 0.4-1.0 g m(-3) of condensate) existed in the ice phase at the coldest temperature (-40 degrees C) at 35,000 feet (10.7 km), Each cloud contained aerosol (haze particles) in addition to cloud particles. The aerosol total surface area exceeded that of the cirrus particles at the coldest temperature. Thus, aerosols must play a significant role in the upscattering of solar radiation. Light extinction (6.2 km(-1)) and backscatter (0.8 sr(-1) km(-1)) was highest in the coldest portion of the cirrus cloud at the highest altitude. C1 STERLING SOFTWARE INC,MOFFETT FIELD,CA 94035. SYNERNET INC,MOFFETT FIELD,CA 94035. FREE UNIV BERLIN,W-1000 BERLIN,GERMANY. TMA NORCAL,MOFFETT FIELD,CA 94035. RP PUESCHEL, RF (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 6 Z9 6 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0169-8095 J9 ATMOS RES JI Atmos. Res. PD SEP PY 1995 VL 38 IS 1-4 BP 297 EP 313 DI 10.1016/0169-8095(95)00002-9 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RX723 UT WOS:A1995RX72300017 ER PT J AU NORFLEET, WT COATS, AC POWELL, MR AF NORFLEET, WT COATS, AC POWELL, MR TI INVERTED IMMERSION AS A NOVEL GRAVITOINERTIAL ENVIRONMENT SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID MOTION SICKNESS; WATER AB Background: Inverted immersion (II) offers a unique opportunity to swing the orientation of the gravity vector 180 degrees from its usual configuration with vestibular end organs. During II, extrathoracic fluid dynamics are identical to those of upright immersion (UI). II exposes individuals to a novel gravitoinertial environment and, therefore, should produce motion sickness (MS). Hypothesis: II is more provocative of signs and symptoms of MS than UI. Methods: Nine subjects were exposed once to II and UI. Conventional SCUBA gear was worn. In II, the subject wore a wetsuit which provided 5-7 kg force of positive buoyancy and, with no weight belt, caused him to float while inverted against the underside of a platform. An experiment with UI was identical except that a weight belt was worn which provided 5-7 kg force of negative buoyancy, and the subject stood upright against the bottom of the pool. The experiment was terminated after 3 hours or ''upon the onset of the first, clear, persistent feeling of nausea'', whichever came first. Throughout the experiment the subject rotated through a series of tasks: assembly of a pipe puzzle, performance of a series of head movements, and ambulation. Immediately post-dive, postural stability was assessed with tandem standing with and without eyes closed and with and without the neck extended 45 degrees. A questionnaire regarding susceptibility to motion sickness was completed pre-dive. Results: No subject terminated the test because of MS during UI; seven subjects terminated the test during II (p < 0.025, McNemar's test). Posture was less stable after II than after UI (p < 0.05, sign test). MS questionnaire results did not predict susceptibility to II. Conclusion: II is provocative of MS and postural instability. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. BAYLOR COLL MED,HOUSTON,TX. UNIV SPACE RES ASSOC,DIV SPACE LIFE SCI,HOUSTON,TX. NR 11 TC 4 Z9 5 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1995 VL 66 IS 9 BP 825 EP 828 PN 1 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA RR602 UT WOS:A1995RR60200001 PM 7487819 ER PT J AU LIEBERMAN, P PROTOPAPAS, A KANKI, BG AF LIEBERMAN, P PROTOPAPAS, A KANKI, BG TI SPEECH PRODUCTION AND COGNITIVE DEFICITS ON MT EVEREST SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID HIGH-ALTITUDE; PARKINSONS-DISEASE; MOUNT EVEREST; POSITRON TOMOGRAPHY; COMPREHENSION; PERFORMANCE; EXPOSURE; CLIMBERS; ALCOHOL; GLUCOSE AB Deficits in speech motor control and in the comprehension of syntax were observed as five members of the 1993 American Sagarmatha Expedition ascended Mt. Everest, We analyzed speech recordings and cognitive test scores of the climbers at different altitudes. The mean ''voice onset time'' interval that differentiates ''voiced'' stop consonants from their ''unvoiced'' counterparts (e.g., a [b] from a [p]) decreased from 24.0 ms at Base Camp to 5.4 ms at Camp Three. The time needed to comprehend simple spoken English sentences increased by 50% at higher altitudes, and was correlated with speech motor deterioration. This pattern of deficits is similar to that noted for Parkinson's disease and may reflect disruption of subcortical pathways to prefrontal cortex. Similar procedures could be used to remotely assess cognitive impairments caused by hypoxia, carbon monoxide or alcohol intoxication, or drugs, in order to monitor crew behavior in aeronautics and spaceflight operations, or to evaluate the treatment of neurodegenerative diseases such as Parkinson's disease. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LIEBERMAN, P (reprint author), BROWN UNIV,DEPT COGNIT & LINGUIST SCI,BOX 1978,PROVIDENCE,RI 02912, USA. RI Protopapas, Athanassios/A-9571-2009; Protopapas, Athanassios/E-5626-2010 OI Protopapas, Athanassios/0000-0002-7285-8845 NR 36 TC 28 Z9 30 U1 1 U2 7 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1995 VL 66 IS 9 BP 857 EP 864 PN 1 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA RR602 UT WOS:A1995RR60200006 PM 7487824 ER PT J AU STOUT, MS WATENPAUGH, DE BREIT, GA HARGENS, AR AF STOUT, MS WATENPAUGH, DE BREIT, GA HARGENS, AR TI SIMULATED MICROGRAVITY INCREASES CUTANEOUS BLOOD-FLOW IN THE HEAD AND LEG OF HUMAN SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID ATRIAL NATRIURETIC PEPTIDE; LASER-DOPPLER FLOWMETRY; SKIN TEMPERATURE; VENOUS-PRESSURE; FLUID SHIFTS; DOWN TILT; RESPONSES; MICROCIRCULATION; WEIGHTLESSNESS; CIRCULATION AB Background: The cutaneous microcirculation vasodilates during acute 6 degrees head-down tilt (HDT, simulated microgravity) relative to upright conditions, more in the lower body than in the upper body. Hypothesis: We expected that relative magnitudes of and differences between upper and lower body cutaneous blood flow elevation would be sustained during initial acclimation to simulated microgravity. Methods: We measured cutaneous microvascular blood flow with laser-Doppler flowmetry at the leg (over the distal tibia) and cheek (over the zygomatic arch) of eight healthy men before, during, and after 24 h of HDT. Results were calculated as a percentage of baseline value (100% measured during pre-tilt uptight sitting). Results: Cutaneous blood flow in the cheek increased significantly to 165 +/- 37% (mean +/- SE, p<0.05) at 9-12 h HDT, then returned to near baseline values by 24 h HDT (114 +/- 29%, NSD), despite increased local arterial pressure. Microvascular flow in the leg remained significantly elevated above baseline throughout 24 h HDT (427 +/- 85% at 3 h HDT and 215 +/- 142% at 24 h HDT, p<0.05). During the 6-h uptight sitting recovery period, cheek and leg blood flow levels returned to near pre-tilt baseline values. Conclusions: Because hydrostatic effects of HDT increase local arterial pressure at the carotid sinus, baroreflex-mediated withdrawal of sympathetic tone probably contributed to increased microvascular flows at the head and leg during HDT. In the leg, baroreflex effects combined with minimal stimulation of local veno-arteriolar and myogenic autoregulatory vasoconstriction to elicit relatively larger and more sustained increases in cutaneous flow during HDT. In the cheek, delayed myogenic vasoconstriction and/or humoral effects apparently compensated for flow elevation by 24 h of HDT. Therefore, localized vascular adaptations to gravity probably explain differences in acclimation of lower and upper body blood flow to HDT and actual microgravity. C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 34 TC 6 Z9 6 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1995 VL 66 IS 9 BP 872 EP 875 PN 1 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA RR602 UT WOS:A1995RR60200008 PM 7487826 ER PT J AU SELLERS, P HALL, F MARGOLIS, H KELLY, B BALDOCCHI, D DENHARTOG, G CIHLAR, J RYAN, MG GOODISON, B CRILL, P RANSON, KJ LETTENMAIER, D WICKLAND, DE AF SELLERS, P HALL, F MARGOLIS, H KELLY, B BALDOCCHI, D DENHARTOG, G CIHLAR, J RYAN, MG GOODISON, B CRILL, P RANSON, KJ LETTENMAIER, D WICKLAND, DE TI THE BOREAL ECOSYSTEM-ATMOSPHERE STUDY (BOREAS) - AN OVERVIEW AND EARLY RESULTS FROM THE 1994 FIELD YEAR SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID MODEL; DYNAMICS; CARBON; FIFE AB The Boreal Ecosystem Atmosphere Study (BOREAS) is a large-scale international field experiment that has the goal of improving our understanding of the exchanges of radiative energy, heat, water, CO2, and trace gases between the boreal forest and the lower atmosphere. An important objective of BOREAS is to collect the data needed to improve computer simulation models of the processes controlling these exchanges so that scientists can anticipate the effects of global change. From August 1993 through September 1994, a continuous set of monitoring measurements-meteorology, hydrology, and satellite remote sensing-were gathered over the 1000 x 1000 km BOREAS study region that covers most of Saskatchewan and Manitoba, Canada. This monitoring program was punctuated by six campaigns that saw the deployment of some 300 scientists and aircrew into the field, supported by 11 research aircraft. The participants were drawn primarily from U.S. and Canadian agencies and universities, although there were also important contributions from France, the United Kingdom, and Russia. The field campaigns lasted for a total of 123 days and saw the compilation of a comprehensive surface-atmosphere flux dataset supported by ecological, trace gas, hydrological, and remote sensing science observations. The surface-atmosphere fluxes of sensible heat, latent heat, CO2, and momentum were measured using eddy correlation equipment mounted on a surface network of 10 towers complemented by four flux-measurement aircraft. All in all, over 350 airborne missions (remote sensing and eddy correlation) were flown during the 1994 field year. Preliminary analyses of the data indicate that the area-averaged photosynthetic capacity of the boreal forest is much less than that of the temperate forests to the south. This is reflected in very low photosynthetic and carbon drawdown rates, which in turn are associated with low transpiration rates (less than 2 mm day-1 over the growing season for the coniferous species in the area). The strong sensible fluxes generated as a result of this often lead to the development of a deep dry planetary boundary layer over the forest, particularly during the spring and early summer. The effects of frozen soils and the strong physiological control of evapotranspiration in the biome do not seem to be well represented in most operational general circulation models of the atmosphere. Analyses of the data will continue through 1995 and 1996. Some limited revisits to the field are anticipated. C1 UNIV LAVAL,ST FOY,PQ,CANADA. UNIV WYOMING,DEPT ATMOSPHER SCI,LARAMIE,WY. NOAA,OAK RIDGE,TN. ATMOSPHER ENVIRONM SERV,DOWNSVIEW,ON,CANADA. CANADIAN CTR REMOTE SENSING,OTTAWA,ON,CANADA. USDA,FT COLLINS,CO. CLIMATE RES BRANCH,DOWNSVIEW,ON,CANADA. UNIV NEW HAMPSHIRE,DURHAM,NH. UNIV WASHINGTON,SEATTLE,WA. NASA HEADQUARTERS,WASHINGTON,DC. RP SELLERS, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BLDG 22,CODE 923,GREENBELT,MD 20771, USA. RI Ryan, Michael/A-9805-2008; Baldocchi, Dennis/A-1625-2009; Ranson, Kenneth/G-2446-2012; lettenmaier, dennis/F-8780-2011 OI Ryan, Michael/0000-0002-2500-6738; Baldocchi, Dennis/0000-0003-3496-4919; Ranson, Kenneth/0000-0003-3806-7270; lettenmaier, dennis/0000-0003-3317-1327 NR 21 TC 361 Z9 375 U1 2 U2 36 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD SEP PY 1995 VL 76 IS 9 BP 1549 EP 1577 DI 10.1175/1520-0477(1995)076<1549:TBESAO>2.0.CO;2 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RZ299 UT WOS:A1995RZ29900001 ER PT J AU ATLAS, D IGUCHI, T PIERCE, HF AF ATLAS, D IGUCHI, T PIERCE, HF TI STORM-INDUCED WIND PATTERNS ON THE SEA FROM SPACEBORNE SYNTHETIC-APERTURE RADAR SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID THUNDERSTORM AB The authors discuss the origin of a unique footprint on the sea induced by storm winds and rainfall as seen by synthetic aperture radar (SAR) from space. Two hypotheses are presented to explain the origin of an apparent wind shadow downwind of a storm cell. The first suggests that the cool air pool from the storm acts as an obstacle to divert the low-level easterly ambient winds and leaves a ''wind shadow'' on its downwind side. This theory is discarded because of the excessive storm lifetime needed to cause the long downstream ''shadow.'' The second hypothesis invokes the cool outflows from two preexisting storm cells such that their boundaries intersect obliquely leaving a triangular wedge of weaker winds and radar cross section (i.e., the shadow). A new precipitation cell is initiated at the point of intersection of the boundaries at the apex of the shadow, giving the illusion that this cell is the cause of the shadow. While the authors lack corroborative observations, this theory is consistent with prior evidence of the triggering of convective clouds and precipitation by intersecting cool air boundaries. The regular observation of such persistent cool air storm outflow boundaries both in satellite observations, and more recently in SAR imagery, suggests that such discontinuities are ubiquitous and serve to trigger new convection in the absence of large-scale forcing. C1 MINIST POSTS & TELECOMMUN,COMMUN RES LAB,TOKYO,JAPAN. SCI SYST & APPLICAT INC,LANHAM,MD. RP ATLAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 9102,GREENBELT,MD 20771, USA. NR 16 TC 5 Z9 5 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD SEP PY 1995 VL 76 IS 9 BP 1585 EP 1592 DI 10.1175/1520-0477(1995)076<1585:SIWPOT>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RZ299 UT WOS:A1995RZ29900003 ER PT J AU KEEN, JE AOTA, S BRILL, RW FARRELL, AP RANDALL, DJ AF KEEN, JE AOTA, S BRILL, RW FARRELL, AP RANDALL, DJ TI CHOLINERGIC AND ADRENERGIC REGULATION OF HEART-RATE AND VENTRAL AORTIC PRESSURE IN 2 SPECIES OF TROPICAL TUNAS, KATSUWONUS-PELAMIS AND THUNNUS-ALBACARES SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID RAINBOW-TROUT; GADUS-MORHUA; CARDIOVASCULAR-RESPONSES; OXYGEN-TRANSPORT; BLOOD-PRESSURE; SKIPJACK TUNA; ACUTE-HYPOXIA; CATECHOLAMINES; TEMPERATURE; ACCLIMATION AB Tonic cholinergic and adrenergic control of heart rate and ventral aorta pressure was examined in two species of tropical tunas, the skipjack tuna (Katsuwonus pelamis) and the yellowfin tuna (Thunnus albacares). Unlike that of many other teleosts, the basal heart rate in spinally blocked tunas (at 25 degrees C) was dominated by a cholinergic rather than an adrenergic tonus. Infusion of atropine increased the heart rate by 143 and 58% in skipjack and yellowfin tunas, respectively. Ventral aortic pulse pressure was significantly decreased and mean ventral aortic pressure was slightly increased. Blockade of beta-adrenergic receptors with propranolol produced small (< 6%) decreases in both heart rate and mean ventral aortic pressure, indicating a low level of tonic beta-adrenergic stimulation. The small magnitude of the drop, however, suggests that tonic adrenergic regulation of heart rate and pressure is of less importance in tunas than in other teleosts, despite comparable circulating levels of adrenaline and noradrenaline. The alpha-adrenergic blocker phentolamine did not affect either heart rate or pressure. The intrinsic heart rate (i.e., the heart rate in the absence of cholinergic or adrenergic stimulation) was 180 beats/min in skipjack tuna and 119 beats/min in yellowfin tuna; these are the highest reported values for any teleost to date. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. GOTHENBURG UNIV,DEPT ZOOPHYSIOL,S-41309 GOTHENBURG,SWEDEN. SIMON FRASER UNIV,DEPT BIOL SCI,BURNABY,BC V5A 1S6,CANADA. UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER,BC V6T 1Z4,CANADA. NR 30 TC 21 Z9 21 U1 0 U2 0 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 SEP PY 1995 VL 73 IS 9 BP 1681 EP 1688 DI 10.1139/z95-200 PG 8 WC Zoology SC Zoology GA TF324 UT WOS:A1995TF32400013 ER PT J AU DETTINGER, MD GHIL, M KEPPENNE, CL AF DETTINGER, MD GHIL, M KEPPENNE, CL TI INTERANNUAL AND INTERDECADAL VARIABILITY IN UNITED-STATES SURFACE-AIR TEMPERATURES, 1910-87 SO CLIMATIC CHANGE LA English DT Article ID PRINCIPAL COMPONENTS ANALYSES; SINGULAR-SPECTRUM ANALYSIS; NORTHERN-HEMISPHERE; DOMAIN SHAPE; TIME-SERIES; INTRASEASONAL OSCILLATIONS; SOUTHERN OSCILLATION; GLOBAL ATMOSPHERE; CLIMATE CHANGE; FLUCTUATIONS AB Monthly mean surface-air temperatures at 870 sites in the contiguous United States were analyzed for interannual and interdecadal variability over the time interval 1910-87. The temperatures were analyzed spatially by empirical-orthogonal-function analysis and temporally by singular-spectrum analysis (SSA). The dominant modes of spatio-temporal variability are trends and nonperiodic variations with time scales longer than 15 years, decadal-scale oscillations with periods of roughly 7 and 10 years, and interannual oscillations of 2.2 and 3.3 years. Together, these modes contribute about 18% of the slower-than-annual United States temperature variance. Two leading components roughly capture the mean hemispheric temperature trend and represent a long-term warming, largest in the southwest, accompanied by cooling of the domain's southeastern quadrant. The extremes of the 2.2-year interannual oscillation characterize temperature differences between the Northeastern and Southwestern States, whereas the 3.3-year cycle is present mostly in the Western States. The 7- to 10-year oscillations are much less regular and persistent than the interannual oscillations and characterize temperature differences between the western and interior sectors of the United States. These continental- or regional-scale temperature variations may be related to climatic variations with similar periodicities, either global or centered in other regions; such variations include quasi-biennial oscillations over the tropical Pacific or North Atlantic and quasi-triennial oscillations of North Pacific sea-surface temperatures. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA. CALTECH,JET PROP LAB,NASA,PASADENA,CA 91109. RP DETTINGER, MD (reprint author), US GEOL SURVEY,SAN DIEGO,CA 92123, USA. NR 66 TC 46 Z9 47 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD SEP PY 1995 VL 31 IS 1 BP 35 EP 66 DI 10.1007/BF01092980 PG 32 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA TA779 UT WOS:A1995TA77900004 ER PT J AU SHIH, TH ZHU, J LUMLEY, JL AF SHIH, TH ZHU, J LUMLEY, JL TI A NEW REYNOLDS STRESS ALGEBRAIC EQUATION SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID TURBULENCE; FLOWS; MODEL; CHANNEL; LAYER AB A general turbulent constitutive relation [1] is directly applied to propose a new Reynolds stress algebraic equation model. In the development of this model, the constraints based on rapid distortion theory and realizability (i.e. the positivity of the normal Reynolds stresses and the Schwarz' inequality between turbulent velocity correlations) are imposed. Model coefficients are calibrated using well-studied basic flows such as homogenous shear how and the surface flow in the inertial sublayer. The performance of this model is then tested in complex turbulent hows including the separated flow over a backward-facing step and the flow in a confined jet. The calculation results are encouraging and point to the success of the present model in modeling turbulent hows with complex geometries. C1 NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135. CORNELL UNIV,ITHACA,NY. NR 38 TC 77 Z9 87 U1 1 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. Methods Appl. Mech. Eng. PD SEP 1 PY 1995 VL 125 IS 1-4 BP 287 EP 302 DI 10.1016/0045-7825(95)00796-4 PG 16 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA RU668 UT WOS:A1995RU66800015 ER PT J AU SRINIVASAN, GR EKATERINARIS, JA MCCROSKEY, WJ AF SRINIVASAN, GR EKATERINARIS, JA MCCROSKEY, WJ TI EVALUATION OF TURBULENCE MODELS FOR UNSTEADY FLOWS OF AN OSCILLATING AIRFOIL SO COMPUTERS & FLUIDS LA English DT Article ID DYNAMIC STALL AB Unsteady flowfields of a two-dimensional oscillating airfoil are calculated using an implicit, finite-difference, Navier-Stokes numerical scheme. Five widely used turbulence models are used with the numerical scheme to assess the accuracy and suitability of the models for simulating the retreating blade stall of helicopter rotor in forward flight. Three unsteady flow conditions corresponding to an essentially attached flow, light-stall, and deep-stall cases of an oscillating NACA 0015 wing experiment were chosen as test cases for computations. Results of unsteady airloads hysteresis curves, harmonics of unsteady pressures, and instantaneous flowfield patterns are presented. Some effects of grid density, time-step size, and numerical dissipation on the unsteady solutions relevant to the evaluation of turbulence models are examined. Comparison of unsteady airloads with experimental data show that all models tested are deficient in some sense and no single model predicts airloads consistently and in agreement with experiment for the three flow regimes. The chief findings are that the simple algebraic model based on the renormalization group theory (RNG) offers some improvement over the Baldwin-Lomax model in all flow regimes with nearly same computational cost. The one-equation models provide significant improvement over the algebraic and the half-equation models but have their own limitations. The Baldwin-Barth model overpredicts separation and underpredicts reattachment. In contrast, the Spalart-Allmaras model underpredicts separation and overpredicts reattachment. RP SRINIVASAN, GR (reprint author), NASA,AMES RES CTR,MAIL STOP 258-1,MOFFETT FIELD,CA 94035, USA. NR 29 TC 33 Z9 33 U1 0 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD SEP PY 1995 VL 24 IS 7 BP 833 EP 861 DI 10.1016/0045-7930(95)00016-6 PG 29 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA RW183 UT WOS:A1995RW18300006 ER PT J AU GALBRAITH, L AF GALBRAITH, L TI A METHOD TO HELP MINIMIZE THE COST-OF-QUALITY SO COMPUTERS & INDUSTRIAL ENGINEERING LA English DT Article; Proceedings Paper CT 17th International Conference on Computers and Industrial Engineering CY MAR 05-08, 1995 CL PHOENIX, AZ RP GALBRAITH, L (reprint author), CALTECH,JET PROP LAB,MAIL STOP 125-161,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 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 0360-8352 J9 COMPUT IND ENG JI Comput. Ind. Eng. PD SEP PY 1995 VL 29 BP 405 EP 409 DI 10.1016/0360-8352(95)00107-C PG 5 WC Computer Science, Interdisciplinary Applications; Engineering, Industrial SC Computer Science; Engineering GA TC835 UT WOS:A1995TC83500074 ER PT J AU PRESCOTT, R MITCHELL, DF GRAHAM, MJ DOYCHAK, J AF PRESCOTT, R MITCHELL, DF GRAHAM, MJ DOYCHAK, J TI OXIDATION MECHANISMS OF BETA-NIAL+ZR DETERMINED BY SIMS SO CORROSION SCIENCE LA English DT Article ID CYCLIC OXIDATION; GROWTH-MECHANISM; HIGH-TEMPERATURE; ALUMINA SCALES; ALLOYS; BEHAVIOR; ALPHA-AL2O3; ZIRCONIUM; TRANSPORT; ADHESION AB The oxidation mechanisms of single crystal Zr-doped beta-NiAl from 800 to 1200 degrees C were determined using primarily secondary ion mass spectrometry (SIMS) imaging and depth profiling. High spatial resolution SIMS imaging provides a means for critically assessing the effects of diffusion through the boundaries of the Various morphologies of alpha-Al2O3 scales that form on beta-NiAl. Transient oxidation occurs by outward Al diffusion through transition Al2O3 scales, theta-Al2O3 in this case, for temperatures from 800 to 1100 degrees C. Steady-state oxidation occurs by counter-diffusion of oxygen inward and both Al and Zr outward through boundaries in the alpha-Al2O3 ridge morphology. C1 NATL RES COUNCIL CANADA,INST MICROSTRUCT SCI,OTTAWA,ON K1A 0R6,CANADA. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 46 TC 61 Z9 63 U1 4 U2 16 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0010-938X J9 CORROS SCI JI Corrosion Sci. PD SEP PY 1995 VL 37 IS 9 BP 1341 EP 1364 DI 10.1016/0010-938X(95)00034-H PG 24 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA RU172 UT WOS:A1995RU17200002 ER PT J AU TURYSHEV, SG AF TURYSHEV, SG TI A NEW SOLUTION FOR DILATON-MAXWELL GRAVITY SO GENERAL RELATIVITY AND GRAVITATION LA English DT Article ID BLACK-HOLES; FIELD AB An interesting static spherically symmetric solution corresponding to Einstein-Maxwell gravity coupled to a dilaton field with negative kinetic term has been obtained. This solution is characterized by the set of two arbitrary parameters, the physical mass mu(0) and electric charge Q. It has two horizons on which the metric, scalar curvature and both dilaton and electromagnetic fields are regular. Another feature of this solution is that the physical mass is bounded by the electric charge as mu(0) greater than or equal to root 2\Q\ (unlike the Reisner-Nordstrom solution for which mu(0) greater than or equal to \Q\). The structure of the scalar curvature has been analyzed. RP TURYSHEV, SG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 TC 5 Z9 5 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0001-7701 J9 GEN RELAT GRAVIT JI Gen. Relativ. Gravit. PD SEP PY 1995 VL 27 IS 9 BP 981 EP 987 DI 10.1007/BF02113080 PG 7 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA RR152 UT WOS:A1995RR15200008 ER PT J AU CHADWICK, OA NETTLETON, WD STAIDL, GJ AF CHADWICK, OA NETTLETON, WD STAIDL, GJ TI SOIL POLYGENESIS AS A FUNCTION OF QUATERNARY CLIMATE-CHANGE, NORTHERN GREAT-BASIN, USA SO GEODERMA LA English DT Article ID PEDOGENIC PROCESSES; NEVADA; DESERT; RATES; ENVIRONMENTS; TEMPERATURE; CHRONOLOGY; CALIFORNIA; DEPOSITS; MONTANA AB The Quaternary environmental history of the northern Great Basin is characterized by a combination of lower temperature and higher moisture than present. Using water-balance analysis of soils sampled along a climatic gradient, we demonstrate that long-term average effective moisture was about 2-4 cm yr(-1) greater than present. Although this long-term average represents most of Quaternary time, there are important short-term excursions from these values during full glacial and interglacial times. Full glacial conditions are characterized by effective moisture about 7-9 cm yr(-1) greater than present; interglacial times, similar to present conditions, are characterized by dry lake basins that provide major increases in eolian activity. These climatic extremes drive pedogenic processes that leave polygenetic imprints on soils of Pleistocene age, Soils that are now dominated by opaline silica, carbonate, and smectite contain evidence of earlier, more acidic, chemical environments conducive to dissolution of primary carbonate and formation of kaolinite. During interglacial time, more eolian activity and less effective moisture combine to decrease the depth of leaching, increase base cations, and modify the soil chemical environment in relict paleosols. In a soil of Bull Lake age (approximate to 150 ky BP), desert loess accumulation created a 25% increase in water holding capacity and decreased the depth of water penetration by 65 cm; climatic drying at the end of the Pleistocene decreased leaching depth by about 150 cm. C1 USDA,NATL SOIL SURVEY LAB,LINCOLN,NE 68508. USDA,SOIL CONSERVAT SERV,PINEDALE,WY 82941. RP CHADWICK, OA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 55 TC 19 Z9 19 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0016-7061 J9 GEODERMA JI Geoderma PD SEP PY 1995 VL 68 IS 1-2 BP 1 EP 26 DI 10.1016/0016-7061(95)00025-J PG 26 WC Soil Science SC Agriculture GA TA710 UT WOS:A1995TA71000001 ER PT J AU CHAO, BF EANES, R AF CHAO, BF EANES, R TI GLOBAL GRAVITATIONAL CHANGES DUE TO ATMOSPHERIC MASS REDISTRIBUTION AS OBSERVED BY THE LAGEOS NODAL RESIDUAL SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE ATMOSPHERIC MASS; GRAVITATIONAL CHANGE; LAGEOS NODE ID TEMPORAL VARIATIONS; EARTHS ROTATION; FIELD; STARLETTE AB Variations in the even-degree zonal gravitational field will produce perturbations to the otherwise constant nodal precession rate in satellite orbits. The contribution of the atmospheric mass redistribution to this nodal 'excitation' on the laser-ranging geodetic satellite Lageos is computed using the ECMWF (European Centre for Medium-range Weather Forecasts) meteorological analysis data over the period 1985-1991, with and without assuming the inverted-barometer (IB) effect for the ocean. These excitation time series are then compared with the observed Lageos nodal residual caused by global gravitational variations. Three frequency bands are examined with the following results. (i) In the interannual band (longer than a year), an apparent similar to 14-month phase lead is found in the atmospheric excitation relative to the Lageos observation. (ii) At seasonal periods, the atmospheric annual signal agrees reasonably well with the observations; the agreement is further strengthened by incorporating continental hydrological contributions. The semi-annual signal compares poorly with observations, indicating the presence of other geophysical sources than the atmosphere. (iii) At the intraseasonal time-scale (shorter than a year) a wide-band correlation coefficient of 0.64 is found between the observed and the atmospheric excitations with the IB effect. The non-IB model yields a somewhat lower correlation of 0.59, but a better correspondence in amplitude. The correlations, together with the corresponding coherence spectra, clearly demonstrate a strong atmospheric contribution to the global gravitational variations. C1 UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 24 TC 28 Z9 33 U1 1 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD SEP PY 1995 VL 122 IS 3 BP 755 EP 764 DI 10.1111/j.1365-246X.1995.tb06834.x PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RU035 UT WOS:A1995RU03500006 ER PT J AU CHAO, BF MERRIAM, JB TAMURA, Y AF CHAO, BF MERRIAM, JB TAMURA, Y TI GEOPHYSICAL ANALYSIS OF ZONAL TIDAL SIGNALS IN LENGTH OF DAY SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE EARTHS ROTATION; LENGTH OF DAY; OCEAN TIDES; SOLID TIDES ID ATMOSPHERIC ANGULAR-MOMENTUM; EARTHS ROTATION; OCEAN-TIDE; PERIODIC CHANGES; WORLD OCEAN AB The Earth's zonal response coefficient kappa is estimated from the tidal signals in the observed length-of-day (LOD) data. Its magnitude and phase are functionals of the Earth's internal structure and dynamics. In this paper, an analysis of 13 years of precise LOD data (1980-1992) reveals strong signals for nine zonal tidal groups ranging from 5 to 35 days in period. Numerical estimates of kappa for 27 major tides are thus obtained, 11 among which are considered sufficiently high in signal-to-noise ratio to provide meaningful geophysical constraints on the Earth's rotational dynamics. The results favour a kappa magnitude close to, but somewhat smaller than, 0.315, which is the theoretical value for an elastic mantle completely decoupled from the fluid core plus equilibrium oceans. A small amount of dispersion is also detectable, where shorter periods tend to have lower kappa magnitude and larger phase lag. Our kappa magnitude estimates are consistent with two recently published non-equilibrium ocean-tide models and an anelastic response in the mantle, although an equilibrium response in the ocean and a purely elastic response in the mantle is not disallowed. Phase lags of a few degrees are required by both ocean-tide models, and by our data. C1 UNIV SASKATCHEWAN,DEPT GEOL SCI,SASKATOON,SK S7N 0W0,CANADA. NATL ASTRON OBSERV,MIZUSAWA,IWATE,JAPAN. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 36 TC 20 Z9 23 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD SEP PY 1995 VL 122 IS 3 BP 765 EP 775 DI 10.1111/j.1365-246X.1995.tb06835.x PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RU035 UT WOS:A1995RU03500007 ER PT J AU CHAO, BF GROSS, RS AF CHAO, BF GROSS, RS TI CHANGES IN THE EARTHS ROTATIONAL ENERGY INDUCED BY EARTHQUAKES SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE EARTHQUAKES; ROTATIONAL ENERGY ID POLAR MOTION AB The kinetic energy of the Earth's rotation can be separated into two parts: the spin energy and the polar-motion energy. Here we derive rigorous formulae for their changes, where the polar-motion energy change is related to the polar-motion excitation function via a treatment of reference frames. The formulae are then used to compute co-seismic energy changes induced by the static displacement held produced in an idealized earth model by a total of 11 015 major earthquakes that occurred during the period 1977 to 1993. An extremely strong statistic is found for the earthquakes' tendency to increase the Earth's spin energy; the rate during 1977 to 1993 was +6.7 GW, about the same as the total seismic-wave energy release. The corresponding polar-motion energy changes are 10(-6) times smaller and had no detectable statistical tendency in their signs. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 17 TC 18 Z9 22 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD SEP PY 1995 VL 122 IS 3 BP 776 EP 783 DI 10.1111/j.1365-246X.1995.tb06836.x PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RU035 UT WOS:A1995RU03500008 ER PT J AU CHAO, BF GROSS, RS DONG, DN AF CHAO, BF GROSS, RS DONG, DN TI CHANGES IN GLOBAL GRAVITATIONAL ENERGY INDUCED BY EARTHQUAKES SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE EARTHQUAKES; GRAVITATIONAL ENERGY ID RELATIVE IMPORTANCE; DRIVING FORCES; PLATE MOTION AB Besides operating its own energy budget, an earthquake acts as an agent transferring a much greater amount of energy among the Earth's rotation, elastic held, gravitational held and internal heat. This paper computes the co-seismic, globally integrated gravitational energy change induced by 11 015 large earthquakes that occurred during 1977 to 1993. The result shows an extremely strong tendency for the earthquakes to decrease the global gravitational energy, Thus, energy is being extracted from the Earth's gravitational held by the action of earthquakes. The average rate of this energy decrease over the period is found to be fairly constant at about 2.0 TW (TW = 10(12) watt), larger by far than the 0.0067 TW for the average rate of the earthquake-induced rotational energy increase and 0.0047 TW for that of total seismic-wave energy release during the same period. Assuming the inability of the Earth to build up elastic energy continuously over time, it is argued that earthquakes, by converting gravitational energy, may make a significant contribution to the global heat flow. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 14 TC 23 Z9 24 U1 0 U2 3 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD SEP PY 1995 VL 122 IS 3 BP 784 EP 789 DI 10.1111/j.1365-246X.1995.tb06837.x PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA RU035 UT WOS:A1995RU03500009 ER PT J AU KRABILL, W THOMAS, R JEZEK, K KUIVINEN, K MANIZADE, S AF KRABILL, W THOMAS, R JEZEK, K KUIVINEN, K MANIZADE, S TI GREENLAND ICE-SHEET THICKNESS CHANGES MEASURED BY LASER ALTIMETRY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MASS BALANCE AB Precise airborne laser-altimetry surveys, at locations on the Greenland ice sheet, that had been accurately surveyed in 1980 and 1981, reveal a thickening in western Greenland of up to two meters between 1980 and 1993. We cannot yet state whether this represents a long-term trend or the cumulative effects of interannual variability of snow-accumulation rates. Nevertheless, the information presented here provides an indication of ice-thickness changes across southern Greenland in unprecedented detail. Laser altimetery surveys have now been made over all the major ice sheet drainage basins, and will be repeated at regular intervals to provide detailed estimates of ice thickening/thinning rates over the entire ice sheet. C1 NASA,WASHINGTON,DC 20546. OHIO STATE UNIV,BYRD POLAR RES CTR,COLUMBUS,OH 43210. UNIV NEBRASKA,LINCOLN,NE 68508. EG&G,WALLOPS FACIL,WALLOPS ISL,VA 23337. RP KRABILL, W (reprint author), NASA,HYDROSPHER PROC LAB,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. NR 18 TC 57 Z9 57 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 SEP 1 PY 1995 VL 22 IS 17 BP 2341 EP 2344 DI 10.1029/95GL02069 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900005 ER PT J AU KURSINSKI, ER HAJJ, GA HARDY, KR ROMANS, LJ SCHOFIELD, JT AF KURSINSKI, ER HAJJ, GA HARDY, KR ROMANS, LJ SCHOFIELD, JT TI OBSERVING TROPOSPHERIC WATER-VAPOR BY RADIO OCCULTATION USING THE GLOBAL POSITIONING SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STEP-MOUNTAIN COORDINATE; SATELLITE SOUNDING DATA; REFRACTIVE-INDEX; RETRIEVALS AB Given the importance of water vapor to weather, climate and hydrology, global humidity observations from satellites are critical. At low latitudes, radio occultation observations of Earth's atmosphere using the Global Positioning System (GPS) satellites allow water vapor profiles to be retrieved with accuracies of 10 to 20% below 6 to 7 km altitude and similar to 5% or better within the boundary layer. GPS observations provide a unique combination of accuracy, vertical resolution (less than or equal to 1 km) and insensitivity to cloud and aerosol particles that is well suited to observations of the lower troposphere. These characteristics combined with the inherent stability of radio occultation observations make it an excellent candidate for the measurement of long term trends. C1 LOCKHEED MARTIN MISSLES & SPACE,PALO ALTO,CA 94304. RP KURSINSKI, ER (reprint author), CALTECH,JET PROP LAB,DIV GEOL & PLANETARY SCI,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 55 Z9 60 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 SEP 1 PY 1995 VL 22 IS 17 BP 2365 EP 2368 DI 10.1029/95GL02127 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900011 ER PT J AU SRIVASTAVA, V BOWDLE, DA JARZEMBSKI, MA ROTHERMEL, J CHAMBERS, DM CUTTEN, DR AF SRIVASTAVA, V BOWDLE, DA JARZEMBSKI, MA ROTHERMEL, J CHAMBERS, DM CUTTEN, DR TI HIGH-RESOLUTION REMOTE-SENSING OF SULFATE AEROSOLS FROM CO2 LIDAR BACKSCATTER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CO2-LASER WAVELENGTHS; DUST AB A high resolution technique for remotely sensing aerosol sulfate composition has been developed, based on the ratio of aerosol backscatter measured at 9.1 and 10.6 mu m wavelengths with two continuous wave CO2 lidars. This is demonstrated using data from the NASA GLObal Backscatter Experiment (GLOBE) over the Pacific Ocean in 1990. Results indicate changes from sulfuric acid with some ammoniation in clean conditions and presence of dust with ammoniated sulfates in continental plumes. Lidars provide good estimates of backscatter ratio with similar to 5 second sample times (similar to 1 km spatial resolution) in aerosol concentrations as low as similar to 10(-2) mu g/m(3). C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL. MICRO CRAFT INC,HUNTSVILLE,AL. RP SRIVASTAVA, V (reprint author), UNIV SPACE RES ASSOC,HUNTSVILLE,AL, USA. NR 14 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 1995 VL 22 IS 17 BP 2373 EP 2376 DI 10.1029/95GL02194 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900013 ER PT J AU BALLESTER, GE HARRIS, WM GLADSTONE, GR CLARKE, JT PRANGE, R FELDMAN, PD COMBI, MR EMERICH, C STROBEL, DF TALAVERA, A BUDZIEN, SA VINCENT, MB LIVENGOOD, TA JESSUP, KL MCGRATH, MA HALL, DT AJELLO, JM BENJAFFEL, L REGO, D FIREMAN, G WOODNEY, L MILLER, S LIU, X AF BALLESTER, GE HARRIS, WM GLADSTONE, GR CLARKE, JT PRANGE, R FELDMAN, PD COMBI, MR EMERICH, C STROBEL, DF TALAVERA, A BUDZIEN, SA VINCENT, MB LIVENGOOD, TA JESSUP, KL MCGRATH, MA HALL, DT AJELLO, JM BENJAFFEL, L REGO, D FIREMAN, G WOODNEY, L MILLER, S LIU, X TI FAR-UV EMISSIONS FROM THE SL9 IMPACTS WITH JUPITER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DAYGLOW AB Observations with the International Ultraviolet Explorer (IUE) during the impacts of the fragments of comet D/Shoemaker-Levy 9 with Jupiter show far-UV emissions from the impact sites within a similar to 10 min time scale. Positive detections of H-2 Lyman and Werner band (1230-1620 Angstrom) and H-Ly alpha emissions are made for impacts K and S, and marginally for P2. No thermal continuum is observed. The radiated far-UV output was >10(21) ergs. The H-2 spectrum is consistent with electron collisional excitation if significant CH4 absorption is included. Such emissions could result from plasma processes generated by the impacts. Non-thermal excitation by the high altitude entry and explosion shocks may also be relevant. Emissions by Al+ (1671 Angstrom) and C (1657 Angstrom) of cometary origin are tentatively identified. C1 SW RES INST, SAN ANTONIO, TX USA. INST ASTROPHYS SPATIALE, ORSAY, FRANCE. INST ASTROPHYS PARIS, PARIS, FRANCE. JOHNS HOPKINS UNIV, BALTIMORE, MD USA. IUE OBSERV, MADRID, SPAIN. USN, RES LAB, WASHINGTON, DC 20375 USA. GODDARD SPACE FLIGHT CTR, GREENBELT, MD USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD USA. JET PROP LAB, PASADENA, CA USA. COMP SCI CORP, LANHAM, MD USA. UNIV MARYLAND, COLLEGE PK, MD USA. UCL, LONDON, ENGLAND. RP BALLESTER, GE (reprint author), UNIV MICHIGAN, DEPT ATMOSPHER OCEAN & SPACE SCI, SPACE PHYS RES LAB, 2455 HAYWARD, ANN ARBOR, MI 48109 USA. RI Livengood, Timothy/C-8512-2012; Combi, Michael/J-1697-2012; Clarke, John/C-8644-2013 OI Combi, Michael/0000-0002-9805-0078; NR 21 TC 3 Z9 3 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 1995 VL 22 IS 17 BP 2425 EP 2428 DI 10.1029/95GL02422 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900026 ER PT J AU TAKATA, T AHRENS, TJ HARRIS, AW AF TAKATA, T AHRENS, TJ HARRIS, AW TI COMET SHOEMAKER-LEVY-9 - FRAGMENT AND PROGENITOR IMPACT ENERGY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Initial observational data from the impact of fragments of Comet Shoemaker-Levy 9 (SL9) are compared with smoothed particle hydrodynamic (SPH) calculations to determine their pre-impact diameters and the equivalent diameter of the SL9 progenitor. Diameters (solid ice) of 2.0+/-0.1, 2.0+/-0.05, 2.1+/-0.04 and 1.9+/-0.05 km for fragments A, E, G1, and W are obtained from impact-induced plume heights from the Hubble Space Telescope (HST) data. Applying these values to scale apparent diameters for the balance of 18 SL fragments in Weaver et al.'s [1995] catalog of 22 objects yields a SL9 progenitor diameter of 5.0+/-1.8 km. This corresponds to total impact energy of 1.2 (+1.8 - 0.8) x 10(30) erg. Such an energetic event occurs on Jupiter and Earth at least every 4,900 +4,700, -2,700, and similar to 0.5 x 10(8) years, respectively. C1 CALTECH, DIV GEOL & PLANETARY SCI, LINDHURST LAB EXPTL GEOPHYS, PASADENA, CA 91125 USA. JET PROP LAB, PASADENA, CA 91109 USA. NR 21 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 1995 VL 22 IS 17 BP 2433 EP 2436 DI 10.1029/95GL02237 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900028 ER PT J AU CACCIANI, A MORETTI, PF DOLCI, M BROCATO, E SMITH, EJ AF CACCIANI, A MORETTI, PF DOLCI, M BROCATO, E SMITH, EJ TI DOPPLER OBSERVATIONS OF THE IMPACT OF COMET-P SHOEMAKER-LEVY-9, FRAGMENT-A SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID JOVIAN GLOBAL OSCILLATIONS AB This paper discusses an attempt to detect the impact of fragment A of the comet Shoemaker-Levy 9 on Jupiter using the Doppler effect. We give a short description of the technique used to observe the impact, then present the observations along with a tentative theoretical analysis and interpretation. The instrumentation used is an advanced and more sensitive version of the Magneto-Optical Filter (normally used in Helioseismology to detect global oscillations of the Sun) and a 40 cm aperture telescope. The observed signal in July 16 (fragment A) consists of a pair of transients that, if related to the comet impact, could be interpreted as the signature of an expanding perturbation. We present only the first step of the theoretical analysis simulating a wave pulse expanding radially from the impact site. The result is remarkable in that it reproduces the two peaks although with much lower amplitudes than observed. Furthermore, the inferred particle speed is in the range 5-20 km/s which is more consistent with the plume and debris material expansion speeds derived from the HST observations and/or with shock wave propagation away from the impact site. C1 OSSERVATORIO ASTRON TERAMO V CERULLI,TERAMO,ITALY. JET PROP LAB,PASADENA,CA. RP CACCIANI, A (reprint author), UNIV ROMA LA SAPIENZA,DEPT PHYS,I-00185 ROME,ITALY. OI Brocato, Enzo/0000-0001-7988-8177 NR 15 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 1995 VL 22 IS 17 BP 2437 EP 2440 DI 10.1029/95GL02559 PG 4 WC Geosciences, Multidisciplinary SC Geology GA RT829 UT WOS:A1995RT82900029 ER PT J AU HAHN, JM WARD, WR RETTIG, TW AF HAHN, JM WARD, WR RETTIG, TW TI RESONANT TRAPPING IN A SELF-GRAVITATING PLANETESIMAL DISK SO ICARUS LA English DT Article ID PRIMORDIAL SOLAR NEBULA; ORBITAL RESONANCES; DENSITY WAVES; DRAG; FRAGMENTATION; LINDBLAD; BODIES; RINGS AB The effects of collective particle behavior on the trapping strength of a perturber's mth order outer Lindblad resonance in a planetesimal disk are examined. We find that if the particle disk supports density waves, the spiral disk potential generated in response to forcing by the perturber shields particles from the perturber and may greatly diminish the perturber's ability to trap particles undergoing orbit decay via aerodynamic drag. The density waves can transport away from the resonance much of the angular momentum deposited in the disk by the perturber. If these waves are modestly damped by gas drag and/or particle collisions, the energy and angular momentum delivered to particles at resonance is greatly reduced (relative to the isolated particle treatment of resonant trapping commonly employed in the literature) and cannot compensate for the losses the particles suffer due to drag. Hence wave propagation, when combined with a moderate degree of wave damping, weakens the perturber's trapping barrier. We describe the range of disk conditions (i.e., the range of perturber masses and disk particle sizes) for which waves in the planetesimal disk propagate away from resonance without return and thus exclude resonant particle trapping. Planetary embryos formed by runaway accretion in the solar nebula are likely to satisfy these conditions. However, we also find that wave action weakens the trapping barrier only if the perturber's mass is not too large; for a minimum mass solar nebula at 5 AU, a perturber exceeding similar to 4 Earth masses/m will force a nonlinear wave response which likely damps rapidly to the planetesimal disk in the vicinity of the resonance. This heats the disk and eventually shuts off the waves, restoring the possibility of resonant trapping by embryos this size and larger. (C) 1995 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP HAHN, JM (reprint author), UNIV NOTRE DAME,DEPT PHYS,NOTRE DAME,IN 46556, USA. NR 47 TC 8 Z9 8 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1995 VL 117 IS 1 BP 25 EP 44 DI 10.1006/icar.1995.1140 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY933 UT WOS:A1995RY93300002 ER PT J AU SPENCER, JR AKIMOV, LA ANGELI, C ANGELINI, P BARUCCI, MA BIRCH, P BLANCO, C BUIE, MW CARUSO, A CHIORNIJ, VG COLAS, F DENTCHEV, P DOROKHOV, NI DESANCTIS, MC DOTTO, E EZHKOVA, OB FULCHIGNONI, M GREEN, S HARRIS, AW HOWELL, ES HUDECEK, T KALASHNIKOV, AV KOBELEV, VV KOROBOVA, ZB KOSHKIN, NI KOZHEVNIKOV, VP KRUGLY, YN LAZZARO, D LECACHEUX, J MACCONNELL, J MELNIKOV, SY MICHALOWSKI, T MUELLER, BEA NAKAMURA, T NEESE, C NOLAN, MC OSBORN, W PRAVEC, P RICCIOLI, D SHEVCHENKO, VS SHEVCHENKO, VG THOLEN, DJ VELICHKO, FP VENDITTI, C VENDITTI, R WISNIEWSKI, W YOUNG, J ZELLNER, B AF SPENCER, JR AKIMOV, LA ANGELI, C ANGELINI, P BARUCCI, MA BIRCH, P BLANCO, C BUIE, MW CARUSO, A CHIORNIJ, VG COLAS, F DENTCHEV, P DOROKHOV, NI DESANCTIS, MC DOTTO, E EZHKOVA, OB FULCHIGNONI, M GREEN, S HARRIS, AW HOWELL, ES HUDECEK, T KALASHNIKOV, AV KOBELEV, VV KOROBOVA, ZB KOSHKIN, NI KOZHEVNIKOV, VP KRUGLY, YN LAZZARO, D LECACHEUX, J MACCONNELL, J MELNIKOV, SY MICHALOWSKI, T MUELLER, BEA NAKAMURA, T NEESE, C NOLAN, MC OSBORN, W PRAVEC, P RICCIOLI, D SHEVCHENKO, VS SHEVCHENKO, VG THOLEN, DJ VELICHKO, FP VENDITTI, C VENDITTI, R WISNIEWSKI, W YOUNG, J ZELLNER, B TI THE LIGHTCURVE OF 4179-TOUTATIS - EVIDENCE FOR COMPLEX ROTATION SO ICARUS LA English DT Article ID STANDARD STARS; COMET; NUCLEUS; HALLEY AB The Apollo asteroid 4179 Toutatis passed within 0.0242 AU of Earth in December 1992, and photometry was obtained by observers from at least 25 sites around the world, at solar phase angles between 121 degrees and 0.2 degrees. The phase curve is well described in the H, G system with a mean H of 15.3 and a slope parameter G of 0.10 +/- 0.10. However, the rotational lightcurve is very unusual. The amplitude is large (1.2 magnitudes) and the rotation period is extremely long (several days). Most remarkably, the lightcurve does not appear to be periodic: it is unlikely that a single rotation period can account for the lightcurve even when the rapidly changing viewing and illumination geometry during the close Earth approach is taken into account, though strong lightcurve minima recurred approximately every 7.3 days. The likely explanation is that Toutatis has complex, tumbling, rotation with a characteristic period between 3 and 7 days. As noted by A. W. Harris (1994 Icarus 107, 209-211), the damping time scale from complex to simple rotation for a small, slowly rotating asteroid like Toutatis is so long that complex rotation is expected, but Toutatis is the first asteroid to show such strong observational evidence for complex rotation. (C) 1995 Academic Press, Inc. C1 LOWELL OBSERV,FLAGSTAFF,AZ 86001. KHARKOV UNIV,ASTRON OBSERV,KHARKOV 310022,UKRAINE. OBSERV PARIS,F-92195 MEUDON,FRANCE. UNIV ROMA LA SAPIENZA,IST ASTRON,I-00161 ROME,ITALY. PERTH OBSERV,BICKLEY,WA,AUSTRALIA. UNIV CATANIA,IST ASTRON,I-95125 CATANIA,ITALY. BUR LONGITUDES,F-75014 PARIS,FRANCE. PEOPLES ASTRON OBSERV & PLANETARIUM,BU-5300 GABROVO,BULGARIA. UNIV PADUA,DIPARTIMENTO FIS,I-35131 PADUA,ITALY. UNIV KENT,CANTERBURY,KENT,ENGLAND. JET PROPULS LAB,PASADENA,CA. BRNO OBSERV,CR-62700 BRNO,CZECH REPUBLIC. URALS UNIV,ASTRON OBSERV,SVERDLOVSK,RUSSIA. DAF,OBSERV NATL,BR-20921 RIO JANEIRO,BRAZIL. COMP SCI CORP,SPACE TELESCOPE SCI INST,ASTRON PROGRAM,BALTIMORE,MD 21218. ADAM MICKIEWICZ UNIV POZNAN,ASTRON OBSERV,POZNAN,POLAND. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. NATL ASTRON OBSERV,TOKYO 181,JAPAN. PLANETARY SCI INST,TUCSON,AZ. CENT MICHIGAN UNIV,DEPT PHYS,MT PLEASANT,MI 48859. ASTRON INST ACAD SCI,ONDREJOV,CZECH REPUBLIC. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. ODESSA UNIV,ASTRON OBSERV,ODESSA 270014,UKRAINE. UZBEKISTAN ACAD SCI,INST ASTRON,TASHKENT 700000,UZBEKISTAN. RI Green, Simon/C-7408-2009; Nolan, Michael/H-4980-2012; Pravec, Petr/G-9037-2014; Lazzaro, Daniela/I-3509-2012; Shevchenko, Vasilij/H-1366-2011; OI Nolan, Michael/0000-0001-8316-0680; Lazzaro, Daniela/0000-0002-4470-6043; Shevchenko, Vasilij/0000-0003-1000-223X; De Sanctis, Maria Cristina/0000-0002-3463-4437; Dotto, Elisabetta/0000-0002-9335-1656 NR 25 TC 46 Z9 48 U1 1 U2 6 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1995 VL 117 IS 1 BP 71 EP 89 DI 10.1006/icar.1995.1143 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY933 UT WOS:A1995RY93300005 ER PT J AU BISHOP, JL PIETERS, CM BURNS, RG EDWARDS, JO MANCINELLI, RL FROSCHL, H AF BISHOP, JL PIETERS, CM BURNS, RG EDWARDS, JO MANCINELLI, RL FROSCHL, H TI REFLECTANCE SPECTROSCOPY OF FERRIC SULFATE-BEARING MONTMORILLONITES AS MARS SOIL ANALOG MATERIALS SO ICARUS LA English DT Article ID HYDROUS OXIDE SOLS; IRON-OXIDES; MOSSBAUER-SPECTROSCOPY; QUANTITATIVE-ANALYSIS; IMAGING SPECTROSCOPY; SPECTRAL REFLECTANCE; BACTERIAL OXIDATION; SURFACE-COMPOSITION; AQUEOUS ALTERATION; MINERALOGY AB Spectroscopic analyses have shown that smectites enhanced in the laboratory with additional ferric species exhibit important similarities to those of the soils on Mars. Ferrihydrite in these chemically treated smectites has features in the visible to near-infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. New samples have been prepared with sulfate as well, because S was found by Viking to be a major component in the surface material on Mars. A suite of ferrihydrite-bearing and ferric sulfate-bearing montmorillonites, prepared with variable Fe3+ and S concentrations and variable pH conditions, has been analyzed using reflectance spectroscopy in the visible and infrared regions, Mossbauer spectroscopy at room temperature and 4 K, differential thermal analysis, and X-ray diffraction. These analyses support the formation of ferrihydrite of variable crystallinity in the ferrihydrite-bearing montmorillonites and a combination of schwertmannite and ferrihydrite in the ferric sulfate-bearing montmorillonites. Small quantities of pearly crystalline or nanophase forms of other ferric materials may also be present in these samples. The chemical formation conditions of the ferrihydrite-bearing and ferric sulfate-bearing montmorillonites influence the character of the low temperature Mossbauer sextets and the visible reflectance spectra. An absorption minimum is observed at 0.88-0.89 mu m in spectra of the ferric sulfate-bearing samples, and at 0.89-0.92 mu m in spectra of the ferrihydrite-bearing montmorillonites. Mossbauer spectra of the ferric sulfate-bearing montmorillonites indicate variable concentrations of ferrihydrite and schwertmannite in the interlaminar spaces and along grain surfaces. Dehydration under reduced atmospheric pressure conditions induces a greater effect on the adsorbed and interlayer water in ferrihydrite-bearing montmorillonite than on the water in ferric sulfate-bearing montmorillonite. Reflectance spectra of ferric sulfate-bearing montmorillonite include a strong 3-mu m band that is more resistant to dry atmospheric conditions than the 3-mu m band in spectra of similarly prepared ferrihydrite-bearing montmorillonites. (C) 1995 Academic Press, Inc. C1 BROWN UNIV,DEPT CHEM,PROVIDENCE,RI 02912. BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. AGR UNIV VIENNA,DEPT APPL GEOL,A-1180 VIENNA,AUSTRIA. RI Mancinelli, Rocco/L-8971-2016 NR 96 TC 45 Z9 45 U1 1 U2 11 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1995 VL 117 IS 1 BP 101 EP 119 DI 10.1006/icar.1995.1145 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY933 UT WOS:A1995RY93300007 PM 11538594 ER PT J AU ENCRENAZ, T LELLOUCH, E CERNICHARO, J PAUBERT, G GULKIS, S SPILKER, T AF ENCRENAZ, T LELLOUCH, E CERNICHARO, J PAUBERT, G GULKIS, S SPILKER, T TI THE THERMAL PROFILE AND WATER ABUNDANCE IN THE VENUS MESOSPHERE FROM H2O AND HDO MILLIMETER OBSERVATIONS SO ICARUS LA English DT Article ID ATMOSPHERE; DEUTERIUM; HYDROGEN; VAPOR AB The 183.310-GHz water vapor transition has been observed in the Venus atmosphere for the first time. The detection was made in January 1991, using the 30-m IRAM radiotelescope. A spectrum of Saturn, recorded during the same night, was used to remove the contribution due to terrestrial mesospheric water. Using the depth and the FWHM of the observed absorption line, we derive a water mixing ratio of 1.0 (+1.0, -0.5) ppm above the clouds, and a temperature of 140 (+/- 10) K at the level z = 95 km (P = 0.06 mb). In July 1993, we reobserved the HDO transition at 225.987 GHz, which we first detected in August 1990 (T. Encrenaz et al. 1991, Astron. Astrophys. 246, L63-L66). The new set of data was obtained at the Caltech Submillimeter Observatory (CSO), with improved signal-to-noise and spectral resolution with respect to previous measurements. From the 1993 data we derive a water mixing ratio of 7.0 (+5.0, -4.0) ppm above the clouds, and a temperature higher than 145 K at the z = 95-km level. The water abundance is derived assuming a deuterium enrichment factor of 120 with respect to the terrestrial value (C. de Bergh et al. 1991, Science 251, 547-549). If the deuterium enrichment factor is close to 160, as measured by G. L. Bjoraker et al. (1992, Bull. Am. Astron. Sec. 24, 995-995), the difference between the H2O measurements is reduced, but the data might still suggest some possible fluctuation in the water vapor content above the clouds between 1991 and 1993. (C) 1995 Academic Press, Inc. C1 CTR ASTRON YEBES,E-19080 GUADALAJARA,SPAIN. IRAM,E-18012 GRANADA,SPAIN. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ENCRENAZ, T (reprint author), OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. NR 28 TC 31 Z9 31 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1995 VL 117 IS 1 BP 162 EP 172 DI 10.1006/icar.1995.1149 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RY933 UT WOS:A1995RY93300011 ER PT J AU ROSENBLUM, LJ BRYSON, S FEINER, SK AF ROSENBLUM, LJ BRYSON, S FEINER, SK TI VIRTUAL-REALITY UNBOUND SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article C1 OFF NAVAL RES,ARLINGTON,VA 22217. NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT SYST,APPL RES OFF,MOFFETT FIELD,CA 94035. COLUMBIA UNIV,COMP GRAPH & USER INTERFACES LAB,NEW YORK,NY 10027. USN,RES LAB,DIV INFORMAT TECHNOL,WASHINGTON,DC 20375. NR 0 TC 6 Z9 6 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD SEP PY 1995 VL 15 IS 5 BP 19 EP 21 PG 3 WC Computer Science, Software Engineering SC Computer Science GA RQ198 UT WOS:A1995RQ19800005 ER PT J AU SIMONS, RN TAUB, SR AF SIMONS, RN TAUB, SR TI UNTITLED SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Editorial Material C1 NASA,LEWIS RES CTR,SOLID STATE TECHNOL BRANCH,CLEVELAND,OH 44135. 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD SEP PY 1995 VL 43 IS 9 BP 913 EP 914 PG 2 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA RR991 UT WOS:A1995RR99100001 ER PT J AU SANZGIRI, S BOSTROM, D POTTENGER, W LEE, RQ AF SANZGIRI, S BOSTROM, D POTTENGER, W LEE, RQ TI A HYBRID TILE APPROACH FOR KA BAND SUBARRAY MODULES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article AB A "thin" array construction using the module architecture is presented in this paper, Several transmit-only the modules operating at 30 GHz have been fabricated. The tile module involves a layered construction that contributes to reduced array thickness, weight, and cost, In such layered construction, the radiating aperture, active devices, and signal distribution functions are placed in different layers and involve vertical interconnections. The subarray module described in this paper involves a hybrid construction in which conventional wire bonding is utilized for interconnecting devices to the signal distribution layers. As in conventional modules, the devices are mounded on the carrier plates and fully tested before insertion in the module. The radiating elements which are integral to the module housing are Connected to the devices through electromagnetic coupling, This hybrid construction is a first step towards a fully batch-processed tile module architecture, The construction approach and the performance results at the module and array level are presented in the paper. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP SANZGIRI, S (reprint author), TEXAS INSTRUMENT, DEPT ANTENNA, DIV ADV TECHNOL, MCKINNEY, TX 75070 USA. NR 5 TC 9 Z9 10 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD SEP PY 1995 VL 43 IS 9 BP 953 EP 959 DI 10.1109/8.410212 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA RR991 UT WOS:A1995RR99100008 ER PT J AU SIMONS, RN DIB, NI LEE, RQ KATEHI, LPB AF SIMONS, RN DIB, NI LEE, RQ KATEHI, LPB TI INTEGRATED UNIPLANAR TRANSITION FOR LINEARLY TAPERED SLOT ANTENNA SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID ABSORBING BOUNDARY-CONDITIONS; DIFFERENCE AB This paper presents the design, fabrication, and numerical modeling of two new uniplanar microstrip-to-coplanar strip (CPS) line transitions and a new variant of the linearly tapered slot antenna (LTSA). This new variant with an integrated uniplanar microstrip-to-coplanar strip line feed is called a V-LTSA. The advantages of these transitions in packaging and monolithic microwave integrated circuits (MMIC) integration have been listed. The two transitions and the feed are modeled using finite difference time domain (FDTD) method. The overall agreement between the measured and modeled return-loss and insertion-loss characteristics of two back-to-back transitions is good, The resonance frequencies predicted by the FDTD method are within a few percentage points of the measurements, Furthermore, the V-LTSA with the feed is experimentally shown to have a wide return toss (less than or equal to -10 dB) bandwidth, good radiation patterns, and low cross-polarization. The gain of the V-LTSA is 9 dB at the design frequency of 10 GHz, A proof-of-concept package to house the feed is experimentally evaluated and shown to have negligible effect on the antenna characteristics. This type of antenna readily integrates with MMIC packages in an array having a brick architecture. The V-LTSA has potential applications in phased arrays. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 NR 17 TC 20 Z9 24 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 SEP PY 1995 VL 43 IS 9 BP 998 EP 1002 DI 10.1109/8.410217 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA RR991 UT WOS:A1995RR99100013 ER PT J AU KORY, CL WILSON, JD AF KORY, CL WILSON, JD TI NOVEL HIGH-GAIN, IMPROVED-BANDWIDTH, FINNED-LADDER V-BAND TRAVELING-WAVE TUBE SLOW-WAVE CIRCUIT-DESIGN SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article AB The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (Solution of MAxwell's Equations by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation, and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth. RP KORY, CL (reprint author), NASA,LEWIS RES CTR,ANALEX CORP,CLEVELAND,OH 44135, USA. NR 9 TC 5 Z9 6 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD SEP PY 1995 VL 42 IS 9 BP 1686 EP 1692 DI 10.1109/16.405285 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA RQ561 UT WOS:A1995RQ56100017 ER PT J AU NAKAMURA, JI KEMENY, SE FOSSUM, ER AF NAKAMURA, JI KEMENY, SE FOSSUM, ER TI CMOS ACTIVE PIXEL IMAGE SENSOR WITH SIMPLE FLOATING-GATE PIXELS SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Note AB A new pixel structure using a simple floating gate (SFG) has been proposed. The pixel consists of a coupling capacitor, a photogate, a barrier gate and a MOS transistor. It features complete reset that results in no kTC noise and no image lag, high blooming overload protection, nondestructive readout (NDRO), and CMOS compatibility. Its basic operation has been confirmed with a 32(H) x 27(V) pixel area array. Since the pixel structure is relatively simple, small pixel size is feasible. C1 OLYMPUS AMER INC,E SETAUKET,NY. RP NAKAMURA, JI (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 3 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD SEP PY 1995 VL 42 IS 9 BP 1693 EP 1694 DI 10.1109/16.405286 PG 2 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA RQ561 UT WOS:A1995RQ56100018 ER PT J AU NJOKU, EG WAY, J AF NJOKU, EG WAY, J TI SPECIAL ISSUE ON THE 1994 INTERNATIONAL-GEOSCIENCE-AND-REMOTE-SENSING-SYMPOSIUM (IGARSS94) - SURFACE AND ATMOSPHERIC REMOTE-SENSING - TECHNOLOGIES, DATA-ANALYSIS, AND INTERPRETATION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Editorial Material RP NJOKU, EG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1995 VL 33 IS 5 BP 1101 EP 1101 PG 1 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA TB578 UT WOS:A1995TB57800001 ER PT J AU AINSWORTH, TL CHUBB, SR FUSINA, RA GOLDSTEIN, RM JANSEN, RW LEE, JS VALENZUELA, GR AF AINSWORTH, TL CHUBB, SR FUSINA, RA GOLDSTEIN, RM JANSEN, RW LEE, JS VALENZUELA, GR TI INSAR IMAGERY OF SURFACE CURRENTS, WAVE-FIELDS, AND FRONTS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 14th Annual International Geoscience and Remote Sensing Symposium (IGARSS 94) CY AUG 08-12, 1994 CL CALIF INST TECHNOL, PASADENA, CA SP IEEE, Geosci & Remote Sensing Soc, Int Union Radio Sci, Opt Soc Amer HO CALIF INST TECHNOL ID RADAR AB We demonstrate the ability of interferometric radar imagery to determine both relative and absolute surface velocities in the open ocean. Absolute phase calibration is accomplished by noting the azimuthal displacement of range-travelling targets-demonstrating for the first time that under favorable circumstances phase calibration can be achieved in open-ocean in the absence of ground truth. The high resolution of radar imagery permits observation of sharp velocity discontinuities, e.g. the Gulf Stream boundary and the wave held. The recent SIR-C/X-SAR shuttle missions dramatically emphasize the experimental and observational aspects of space-based radar. The combination of absolute velocities, high spatial resolution, and wide-area coverage suggest that interferometric radar imagery can provide a unique and powerful aid both for studies of global circulation patterns and detailed analysis of slope/shelf water interactions with ocean currents. In particular, we employ this measurement of the surface currents and wave field near a velocity front to help refine and bound results of our modeling of calculated radar images of the front. The results of this paper are compared with available ground truth. C1 USN,RES LAB,DIV REMOTE SENSING,WASHINGTON,DC 20375. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP AINSWORTH, TL (reprint author), COMPUTAT PHYS INC,FAIRFAX,VA 22031, USA. NR 12 TC 14 Z9 15 U1 2 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1995 VL 33 IS 5 BP 1117 EP 1123 DI 10.1109/36.469475 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 TB578 UT WOS:A1995TB57800004 ER PT J AU RIGNOT, EJ ZIMMERMANN, R VANZYL, JJ AF RIGNOT, EJ ZIMMERMANN, R VANZYL, JJ TI SPACEBORNE APPLICATIONS OF P-BAND IMAGING RADARS FOR MEASURING FOREST BIOMASS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID RAIN-FOREST; AMERICAN AB In three sites of boreal and temperate forests, P band HH, HV, and VV polarization data combined estimate total aboveground dry woody biomass within 12 to 27% of the values derived from allometric equations, depending on forest complexity. Biomass estimates derived from HV-polarization data only are 2 to 14% less accurate. When the radar operates at circular polarization, the errors exceed 100% over flooded forests, wet or damaged trees and sparse open tall forests because double-bounce reflections of the radar signals yield radar signatures similar to that of tall and massive forests, Circular polarizations, which minimize the effect of Faraday rotation in spaceborne applications, are therefore of limited use for measuring forest biomass. In the tropical rain forest of Manu, in Peru, where forest biomass ranges from 4 kg m(-2) in young forest succession up to 50 kg m(-2) in old, undisturbed floodplain stands, the P band horizontal and vertical polarization data combined separate biomass classes in good agreement with forest inventory estimates. The worldwide need for large scale, updated, biomass estimates, achieved with a uniformly applied method, justifies a more in-depth exploration of multi-polarization long wavelength imaging radar applications for tropical forests inventories. C1 CALTECH, JET PROP LAB, AIRBORNE ACT MICROWAVE INSTRUMENTS PROGRAM, PASADENA, CA 91109 USA. RP RIGNOT, EJ (reprint author), CALTECH, JET PROP LAB, RADAR SCI & ENGN SECT, HYDROL SOILS & ECOL GRP, PASADENA, CA 91109 USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 33 TC 76 Z9 82 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1995 VL 33 IS 5 BP 1162 EP 1169 DI 10.1109/36.469480 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 TB578 UT WOS:A1995TB57800009 ER PT J AU DAVIS, DT CHEN, ZX HWANG, JN TSANG, L NJOKU, E AF DAVIS, DT CHEN, ZX HWANG, JN TSANG, L NJOKU, E TI SOLVING INVERSE PROBLEMS BY BAYESIAN ITERATIVE INVERSION OF A FORWARD MODEL WITH APPLICATIONS TO PARAMETER MAPPING USING SMMR REMOTE-SENSING DATA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT 14th Annual International Geoscience and Remote Sensing Symposium (IGARSS 94) CY AUG 08-12, 1994 CL CALIF INST TECHNOL, PASADENA, CA SP IEEE, Geosci & Remote Sensing Soc, Int Union Radio Sci, Opt Soc Amer HO CALIF INST TECHNOL ID MULTICHANNEL MICROWAVE RADIOMETER; NEURAL-NETWORK; SNOW PARAMETERS; SURFACES AB Inverse problems have been often considered ill-posed, i.e., the statement of the problem does not thoroughly constrain the solution space. In this paper we take advantage of this lack of information by adding additional informative constraints to the problem solution using Bayesian methodology. Bayesian modeling gains much of its power from its ability to isolate and incorporate causal models as conditional probabilities. As causal models are accurately represented by forward models, we convert implicit functional models into data driven forward models represented by neural networks, to be used as engines in a Bayesian modeling setting. Remote sensing problems afford opportunities for inclusion of ground truth information, prior probabilities, noise distributions, and other informative constraints within a Bayesian probabilistic framework. We first apply these Bayesian methods to a synthetic remote sensing problem, showing that the performance is superior to a previously published method of iterative inversion of neural networks. Next, microwave brightness temperatures obtained from the Scanning Multichannel Microwave Radiometer (SMMR) over the African continent are inverted. The values of soil moisture, surface air temperature and vegetation moisture retrieved from the inversion produced contours that agree with the expected trends for that region. C1 CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91125. RP DAVIS, DT (reprint author), UNIV WASHINGTON,DEPT ELECT ENGN,SEATTLE,WA 98195, USA. NR 25 TC 19 Z9 19 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1995 VL 33 IS 5 BP 1182 EP 1193 DI 10.1109/36.469482 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 TB578 UT WOS:A1995TB57800011 ER PT J AU MOGHADDAM, M SAATCHI, S AF MOGHADDAM, M SAATCHI, S TI ANALYSIS OF SCATTERING MECHANISMS IN SAR IMAGERY OVER BOREAL FOREST - RESULTS FROM BOREAS-93 SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note CT 14th Annual International Geoscience and Remote Sensing Symposium (IGARSS 94) CY AUG 08-12, 1994 CL CALIF INST TECHNOL, PASADENA, CA SP IEEE, Geosci & Remote Sensing Soc, Int Union Radio Sci, Opt Soc Amer HO CALIF INST TECHNOL ID RADAR BACKSCATTER; BIOMASS; VEGETATION; MODEL AB As part of the intensive field campaign (IFC) for the Boreal forest ecosystem-atmosphere research (BOREAS) project in August 1993, the NASA/JPL AIRSAR covered an area of about 100 km x 100 km near the Prince Albert National Park in Saskatchewan, Canada. At the same time, ground-truth measurements were made in several stands which have been selected as the primary study sites. This paper focuses on an area including jack pine stands in the Nipawin area near the park. Upon examining the AIRSAR data from stands of old and young jack pine (OJP and YJP), distinct signatures are observed for each of the forest types at various frequencies and polarizations, in particular, at P-band HH. We use a forest scattering model in conjunction with the ground-truth measurements to explain such behavior. The forest model includes the major scattering mechanisms by taking the forest component interactions into account. The contribution from each of the scattering mechanisms to the total backscatter is calculated and their differences for OJP and YJP stands are evaluated. The results are used to discuss the effect of the physical properties of the forest components in each stand on radar backscatter. They are also used to show that it is not only the backscatter level but also the relative contribution from various scattering mechanisms that will help in quantitative interpretation of SAR data. This work is mainly intended as a precursor to our ongoing work which uses a mechanism-specific inversion technique to retrieve forest parameters from SAR data for these BOREAS sites. RP MOGHADDAM, M (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 19 TC 31 Z9 33 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 SEP PY 1995 VL 33 IS 5 BP 1290 EP 1296 DI 10.1109/36.469495 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 TB578 UT WOS:A1995TB57800023 ER PT J AU DICK, GJ SANTIAGO, DG WANG, RT AF DICK, GJ SANTIAGO, DG WANG, RT TI TEMPERATURE-COMPENSATED SAPPHIRE RESONATOR FOR ULTRA-STABLE OSCILLATOR CAPABILITY AT TEMPERATURES ABOVE 77 K SO IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL LA English DT Article AB We report on the design and test of a whispering gallery sapphire resonator for which the dominant (WGH(n11)) microwave mode family shows frequency-stable, compensated operation for temperatures above 77 K. The resonator makes possible a new ultra-stable oscillator (USO) capability that promises performance improvements over the best available crystal quartz oscillators in a compact cryogenic package. A mechanical compensation mechanism, enabled by the difference between copper and sapphire expansion coefficients, tunes the resonator to cancel the temperature variation of sapphire's dielectric constant. In experimental tests, the WGH(811) mode showed a frequency turnover temperature of 87 K in agreement with finite element calculations. Preliminary tests of oscillator operation show an Allan Deviation of frequency variation of 1.4-6 x 10(-12) for measuring times 1 s less than or equal to tau less than or equal to 100 s with unstabilized resonator housing temperature and a mode Q of 2 x 10(6). We project a frequency stability 10(-14) for this resonator with stabilized housing temperature and with a mode Q of 10(7). RP DICK, GJ (reprint author), CALTECH,JET PROP LAB,TIME & FREQUENCY RES GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 TC 21 Z9 21 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 0885-3010 J9 IEEE T ULTRASON FERR JI IEEE Trans. Ultrason. Ferroelectr. Freq. Control PD SEP PY 1995 VL 42 IS 5 BP 812 EP 819 DI 10.1109/58.464836 PG 8 WC Acoustics; Engineering, Electrical & Electronic SC Acoustics; Engineering GA RW007 UT WOS:A1995RW00700002 ER PT J AU DIPASQUALE, RC WHITLOCK, CH AF DIPASQUALE, RC WHITLOCK, CH TI GLOBAL DISTRIBUTION OF SURFACE SHORTWAVE FLUXES DERIVED FROM SATELLITE DATA FOR THE WORLD CLIMATE RESEARCH-PROGRAM SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE NET SHORTWAVE DATA; BROAD-BAND SURFACE ALBEDO; SOLAR RADIATION FLUXES; WORLD CLIMATE RESEARCH PROGRAM; SATELLITE DATA; SURFACE SITE MEASUREMENTS AB The World Climate Research Programme has established the Surface Radiation Budget Climatology Project with the ultimate goal of providing, for the scientific community, a long-term (10 years) data set of the global surface radiation budget. This report describes the first global product produced and archived as part of that effort. It reviews product content and accuracy, and highlights sample data from several regions around the globe. Interested users can obtain global data sets, at no cost, from the Langley Distributed Active Archive Center. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP DIPASQUALE, RC (reprint author), LOCKHEED ENGN & SCI CO,144 RES DR,HAMPTON,VA 23666, USA. NR 11 TC 3 Z9 3 U1 0 U2 1 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 SEP PY 1995 VL 15 IS 9 BP 961 EP 973 DI 10.1002/joc.3370150903 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA RX282 UT WOS:A1995RX28200002 ER PT J AU WHITMORE, M MCKAY, TD MOUNT, FE AF WHITMORE, M MCKAY, TD MOUNT, FE TI ERGONOMIC EVALUATION OF A SPACELAB GLOVEBOX SO INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS LA English DT Article DE GLOVEBOX DESIGN; WORKSTATION DESIGN; ERGONOMIC EVALUATIONS; ANTHROPOMETRIC EVALUATIONS; VIDEO ANALYSIS; HUMAN COMPUTER MODELING AB A Glovebox is an enclosure used to manipulate potentially hazardous or hard-to-contain objects. A human factors experiment was flown during a recent Shuttle mission to evaluate a Glovebox design in microgravity. The study consisted of a video analysis of posture at the Glovebox and compilation of crew comments on the design of the interface and perceived discomfort level. The results showed that the Glovebox was too small to perform tasks requiring fine manipulation and dexterity. The operators experienced neck and shoulder discomfort. It was found that a ''hunched'' shoulder posture was assumed approximately 40% of the total observed time. Future plans are evaluation of other glovebox designs and development of microgravity human factors requirements for gloveboxes. Relevance to industry The Spacelab Glovebox is an enclosed workstation with constrained access to the work area. These kinds of workstations are used in various industrial settings such as research laboratories, hospitals, chemical or nuclear plants. Although there are technical specifications and design guidelines such as air flow requirements, level of containment, the ergonomic considerations are not investigated extensively. This study is an attempt to identify the ergonomic design requirements of gloveboxes through evaluating a material science glovebox designed for use in a microgravity laboratory. RP WHITMORE, M (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HUMAN FACTORS & ERGON LAB,HOUSTON,TX 77058, USA. NR 4 TC 1 Z9 1 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-8141 J9 INT J IND ERGONOM JI Int. J. Ind. Ergon. PD SEP PY 1995 VL 16 IS 3 BP 155 EP 164 DI 10.1016/0169-8141(94)00096-L PG 10 WC Engineering, Industrial; Ergonomics SC Engineering GA RV484 UT WOS:A1995RV48400001 ER PT J AU BISHU, RR KLUTE, G AF BISHU, RR KLUTE, G TI THE EFFECTS OF EXTRA VEHICULAR ACTIVITY (EVA) GLOVES ON HUMAN-PERFORMANCE SO INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS LA English DT Article; Proceedings Paper CT International Ergonomics and Safety Conference CY JUN, 1993 CL COPENHAGEN, DENMARK DE STRENGTH; DEXTERITY; TACTILITY; GLOVES AB Human strength and capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective, multipurpose tool. This is especially true for unknown microgravity environments such as the EVA environment. Facilitation of these activities, with simultaneous protection from the cruel EVA environment, are the two, often conflicting, objectives of glove design. The objective of this study was to assess the effects of EVA gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment in which a number of dexterity measures such as time to tie a rope, and the time to assemble a nut and bolt, were recorded. Tactility was measured through a two-point discrimination test. The results indicate that (a) With EVA gloves there is a considerable reduction in both strength and dexterity performance; and (b) performance decrements increase with increasing pressure differential. Some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed. Relevance to industry Gloves are used almost in all the industries as a safety device to protect the human hand. However, performance is reduced with gloves. This study attempts to link glove attributes to performance of gloved hand. Hence it is very relevant to the industry. C1 NASA,LYNDON B JOHNSON SPACE CTR,ANTHROPOMETRY & BIOMECH LAB,HOUSTON,TX 77058. RP BISHU, RR (reprint author), UNIV NEBRASKA,DEPT IND ENGN,LINCOLN,NE 68588, USA. NR 7 TC 21 Z9 24 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-8141 J9 INT J IND ERGONOM JI Int. J. Ind. Ergon. PD SEP PY 1995 VL 16 IS 3 BP 165 EP 174 DI 10.1016/0169-8141(95)00077-T PG 10 WC Engineering, Industrial; Ergonomics SC Engineering GA RV484 UT WOS:A1995RV48400002 ER PT J AU GHOSH, MK BREWE, DE AF GHOSH, MK BREWE, DE TI TEMPERATURE DISTRIBUTION AND THERMAL DISTORTION DUE TO FRICTIONAL HEATING IN A DRY SHAFT-BUSH TRIBOSYSTEM USING THE FINITE-ELEMENT METHOD SO INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES LA English DT Article ID SLIDING SYSTEMS; MEDIA AB The temperatures due to frictional heating within a solid lubricated or coated journal bearing were analysed by using a finite element method. Distortion due to frictional heating was also calculated in the case of the coated system to ascertain the suitability of coating materials for high temperature applications. A solid model of the shaft-bush tribocontact was generated with an eight-node, three-dimensional, first-order isoparametric heat-transfer element and Patran solid modeller software. The Patmar (Patran-Marc) translator was used to help develop the Marc-based finite element program for the system; this software was used on the CRAY X-MP supercomputer to perform a finite element analysis of the contact. The analysis was performed for various liner materials, for thin, hard, wear-resistant coated bearings and for different geometries and thermal cooling boundary conditions. The analysis indicated that thermal conductivity of the liner or coating material is the most vital thermal parameter that controls the interface temperature. In addition to design variations, the proximity of the cooling source to the heat flux-generating interface is critically important to the temperature control in the system. Further, the thermal stresses and deformation are dependent on the elastic properties and thermal expansion coefficient of the coating material for a given geometry. C1 NASA, LEWIS RES CTR, PROPULS DIRECTORATE, CLEVELAND, OH 44135 USA. RP GHOSH, MK (reprint author), BANARAS HINDU UNIV, INST TECHNOL, DEPT MECH ENGN, VARANASI 221005, UTTAR PRADESH, INDIA. NR 15 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7403 EI 1879-2162 J9 INT J MECH SCI JI Int. J. Mech. Sci. PD SEP PY 1995 VL 37 IS 9 BP 1021 EP + DI 10.1016/0020-7403(94)00078-X PG 1 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA RU068 UT WOS:A1995RU06800008 ER PT J AU PREMACK, T DOUGLAS, AS AF PREMACK, T DOUGLAS, AS TI 3-DIMENSIONAL ANALYSIS OF THE IMPACT FRACTURE OF 4340-STEEL SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article; Proceedings Paper CT International Symposium on Dynamic Failure Mechanics of Modern Materials CY 1994 CL CALIF INST TECHNOL, PASADENA, CA HO CALIF INST TECHNOL ID FINITE-ELEMENT ANALYSIS; FATIGUE CRACK CLOSURE; ENERGY-RELEASE RATE; DYNAMIC FRACTURE; BEHAVIOR; SPECIMEN; INITIATION; PLATE; FRONT; BODY AB An analysis of the impact fracture of a three-point-bend specimen made of 4340 steel is performed using the finite element method (FEM). In the experiments performed by Sharpe et al. [(1988) WNS/ASD-88-02. The Johns Hopkins University Baltimore, Maryland] the crack tip opening displacement (CTOD) 100 mu m behind a prefatigued crack tip was measured. The numerical analyses performed to model this experiment used a three-dimensional mesh which accounted for crack curvature and examined the role played by the residual plastic deformation as a result of the precracking procedure and also the role played by material rate sensitivity of the Row stress. The finite element simulation which included both precracking and strain rate sensitivity effects modeled the CTOD well for the observed 10 mu s. From this model, local stress and deformation fields can be assessed. These indicate a significant increase in the impact fracture toughness over the quasi-static toughness. Error estimates and other observations for experimentalists are made, based on different FEM simulations. C1 JOHNS HOPKINS UNIV,DEPT MECH ENGN,BALTIMORE,MD 21218. RP PREMACK, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 751,GREENBELT,MD 20771, USA. RI Douglas, Andrew/C-6862-2009 NR 57 TC 11 Z9 12 U1 1 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD SEP PY 1995 VL 32 IS 17-18 BP 2793 EP 2812 DI 10.1016/0020-7683(94)00295-8 PG 20 WC Mechanics SC Mechanics GA RL557 UT WOS:A1995RL55700023 ER PT J AU YU, YH TUNG, C GALLMAN, J SCHULTZ, KJ VANDERWALL, B SPIEGEL, P MICHEA, B AF YU, YH TUNG, C GALLMAN, J SCHULTZ, KJ VANDERWALL, B SPIEGEL, P MICHEA, B TI AERODYNAMICS AND ACOUSTICS OF ROTOR BLADE-VORTEX INTERACTIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB As part of an international cooperative program, several aerodynamic and acoustic prediction codes have been recently developed to understand the rotor blade-vortex interaction (BVI) noise. Furthermore, a joint validation activity of these prediction codes was performed with the blade surface pressure and acoustic data taken in the German-Dutch Wind Tunnel with the 1/7-scale model AH-I Operational Loads Survey blades. Careful attention has been given to the detailed flowfield, especially wake structures during BVIs including the miss-distance between vortex and blade, vortex core size, and tip vortex trajectories. The results of flowfield including wake systems from various prediction codes show some quantitative differences, but the acoustic results using these calculated airloads as inputs compare reasonably well with test data. RP YU, YH (reprint author), NASA,AMES RES CTR,AEROLIGHTDYNAM DIRECTORATE,DIV FLUID MECH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 11 Z9 12 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1995 VL 32 IS 5 BP 970 EP 977 DI 10.2514/3.46825 PG 8 WC Engineering, Aerospace SC Engineering GA RY916 UT WOS:A1995RY91600009 ER PT J AU GEE, K RIZK, YM SCHIFF, LB AF GEE, K RIZK, YM SCHIFF, LB TI ANALYSIS OF TANGENTIAL SLOT BLOWING ON F/A-18 ISOLATED FOREBODY SO JOURNAL OF AIRCRAFT LA English DT Article AB The generation of significant side forces and yawing moments on an F/A-18 fuselage through tangential slot blowing is analyzed using computational fluid dynamics. The effects of freestream Mach number, jet exit conditions, jet length, and jet location are studied. The effects of over- and underblowing on force and moment production are analyzed. Non-time-accurate solutions are obtained to determine the steady-state side forces, yawing moments, and surface pressure distributions generated by tangential slat blowing. Time-accurate solutions are obtained to study the force onset time lag of tangential slot blowing. Comparison with available experimental data from full-scale wind-tunnel and subscale wind-tunnel tests are made. This computational analysis complements the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flowfield about the isolated F/A-18 forebody. Additionally, it extends the slot-blowing database to transonic maneuvering Mach numbers. RP GEE, K (reprint author), NASA,AMES RES CTR,MCAT INST,M-S 258-1,MOFFETT FIELD,CA 94035, 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 SEP-OCT PY 1995 VL 32 IS 5 BP 1040 EP 1046 DI 10.2514/3.46834 PG 7 WC Engineering, Aerospace SC Engineering GA RY916 UT WOS:A1995RY91600018 ER PT J AU SCOTT, RC POTOZKY, AS PERRY, B AF SCOTT, RC POTOZKY, AS PERRY, B TI MATCHED-FILTER AND STOCHASTIC-SIMULATION-BASED METHODS OF GUST LOADS PREDICTION SO JOURNAL OF AIRCRAFT LA English DT Article AB Two analysis methods, one deterministic and the other stochastic, for computing maximized and time-correlated gust loads fur aircraft with nonlinear control systems are described. The first method is based on matched-filter theory, and the second is based on stochastic simulation. This article summarizes the methods, discusses the selection of gust intensity for each method, and presents numerical results, The critical gust profiles and the maximized and time-correlated load time histories obtained from the two methods are compared. Their striking similarity demonstrates that the key quantities from the matched-filter-based method are realized in the stochastic-simulation-based method. The similarity between the results of the two methods is seen to exist for both linear and nonlinear configurations, indicating that these methods are capable of predicting the critical gust profiles and loads for those classes of nonlinear systems examined. RP SCOTT, RC (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT,AEROELAST BRANCH,M-S 340,HAMPTON,VA 23681, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1995 VL 32 IS 5 BP 1047 EP 1055 DI 10.2514/3.46835 PG 9 WC Engineering, Aerospace SC Engineering GA RY916 UT WOS:A1995RY91600019 ER PT J AU Krzynowek, J Panunzio, LJ AF Krzynowek, J Panunzio, LJ TI Practical application of thin-layer chromatography for detection of polyphosphates in seafood SO JOURNAL OF AOAC INTERNATIONAL LA English DT Article AB The practical application of previously published thin-layer chromatographic (TLC) methods to polyphosphate detection in seafood was determined. Exogenous polyphosphates are distinguishable from naturally occurring phosphates by using TLC; their detection can be enhanced by sampling techniques. Polyphosphates will eventually hydrolyze to monophosphates and make detection virtually impossible. Hydrolysis and therefore, nondetection, is accelerated by certain commercial practices. Results indicate that TLC detection of added phosphates can be used as an inspection tool for fresh products and for frozen products stored about 1 year. C1 US DEPT COMMERCE,NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,GLOUCESTER LAB,GLOUCESTER,MA 01930. NR 6 TC 6 Z9 6 U1 0 U2 3 PU AOAC INTERNATIONAL PI GAITHERSBURG PA 481 NORTH FREDRICK AVE, STE 500, GAITHERSBURG, MD 20877-2504 SN 1060-3271 J9 J AOAC INT JI J. AOAC Int. PD SEP-OCT PY 1995 VL 78 IS 5 BP 1328 EP 1332 PG 5 WC Chemistry, Analytical; Food Science & Technology SC Chemistry; Food Science & Technology GA TV259 UT WOS:A1995TV25900033 ER PT J AU RYBICKI, GC AF RYBICKI, GC TI DEEP-LEVEL DEFECTS IN ALPHA-PARTICLE IRRADIATED 6H SILICON-CARBIDE SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID RADIATION DEFECTS AB A deep level transient spectroscopy study of native and radiation induced defects in metal organic chemical vapor deposition rt on p 6H-SiC diodes has been conducted. Three majority carrier levels were found, at E(v) +0.50, +0.55, and +0.69 eV, and three minority carrier deep levels were found, at E(c) -0.38, -0.48, and -0.58 eV. These six levels were initially observed in the unirradiated materials. Their concentration increased 2 to 13-fold after irradiation to a fluence of 2X10(11) cm(-2) of 5.5 MeV alpha particles. In addition the carrier removal was monitored during irradiation, and a carrier removal rate of 7.8x10(4) cm(-1) for 5.5 MeV alpha particles was measured. When compared with a similar study of alpha particle irradiation of InP, the results suggest that SiC has radiation resistance comparable to that of InP, another highly radiation resistant semiconductor. (C) 1995 American Institute of Physics. RP RYBICKI, GC (reprint author), NASA,LEWIS RES CTR,PHOTOVOLTA BRANCH,CLEVELAND,OH 44135, USA. NR 27 TC 32 Z9 32 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 1 PY 1995 VL 78 IS 5 BP 2996 EP 3000 DI 10.1063/1.360048 PG 5 WC Physics, Applied SC Physics GA RR845 UT WOS:A1995RR84500015 ER EF