FN Thomson Reuters Web of Science™ VR 1.0 PT J AU RUSCH, DW CLANCY, RT BHARTIA, BK AF RUSCH, DW CLANCY, RT BHARTIA, BK TI COMPARISON OF SATELLITE MEASUREMENTS OF OZONE AND OZONE TRENDS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAGE-I AB Measurements of ozone retrieved from satellite instruments over the 1979-1991 period ate compared. The instruments used are the total ozone mapping spectrometer (TOMS), the solar backscattered ultraviolet experiment (SBUV), and stratospheric aerosol and gas experiments (SAGE) I and II. Although there is good agreement between the absolute densities of ozone as measured by the various instruments, the long-term changes (1979-1990) disagree sharply as a function of pressure and in the integrated ozone amount. In the upper stratosphere, SBUV trends are negative with maximum values of about -1.5%/year at high latitudes. Combined SAGE I and II trends are slightly positive in this region and peak near 0.5%/year at equatorial latitudes. In the lower stratosphere, SBUV trends reflect small decreases in ozone, generally less than -0.4%/year except at high southern latitudes where the trends reach values of approximately -1.5%/year. SAGE ozone trends exhibit large decreases particularly in the equatorial regions where decreases of 3-6%/year are seen at pressures between 60 and 90 mbar. At higher latitudes, SAGE trends are more comparable to SBUV trends in the lower stratosphere. Total ozone trends from TOMS and SBUV agree within their uncertainties. Near-zero trends are indicated at low latitudes, and larger, negative trends (similar to -0.5%/year) are indicated near the poles. The SAGE column ozone trends depend upon the base level altitude of integration but do not exhibit a strong latitude dependence. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RP RUSCH, DW (reprint author), UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, CAMPUS BOX 392, BOULDER, CO 80309 USA. RI Bhartia, Pawan/A-4209-2016 OI Bhartia, Pawan/0000-0001-8307-9137 NR 12 TC 12 Z9 12 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 OCT 20 PY 1994 VL 99 IS D10 BP 20501 EP 20511 DI 10.1029/94JD01821 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900002 ER PT J AU MCPETERS, RD MILES, T FLYNN, LE WELLEMEYER, CG ZAWODNY, JM AF MCPETERS, RD MILES, T FLYNN, LE WELLEMEYER, CG ZAWODNY, JM TI COMPARISON OF SBUV AND SAGE-II OZONE PROFILES - IMPLICATIONS FOR OZONE TRENDS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TEMPERATURE; VALIDATION; UMKEHR AB Solar backscattered ultraviolet (SBUV) ozone profiles have been compared with Stratospheric Aerosol and Gas Experiment (SAGE) II profiles over the period October 1984 through June 1990, when data are available from both instruments. SBUV measurements were selected to closely match the SAGE II latitude/longitude measurement pattern. There are significant differences between the SAGE II sunrise and the sunset zonal mean ozone profiles in the equatorial zone, particularly in the upper stratosphere, that may be connected with extreme SAGE II solar azimuth angles for tropical sunrise measurements. Calculation of the average sunset bias between SBUV and SAGE II ozone profiles shows that allowing for diurnal variation in Umkehr layer 10, SBUV and SAGE II agree to within +/-5% for the entire stratosphere in the northern midlatitude zone. The worst agreement is seen at southern midlatitudes near the ozone peak (disagreements of +/-10%), apparently the result of the SBUV ozone profile peaking at a lower altitude than SAGE. The integrated ozone columns (cumulative above 15 km) agree very well, to within +/-2.3% in all zones for both sunset and sunrise measurements. A comparison of the time dependence of SBUV and SAGE II shows that there was less than +/-5% relative drift over the 5.5 years for all altitudes except below 25 km, where the SBUV vertical resolution is poor. The best agreement with SAGE is seen in the integrated column ozone (cumulative above 15 km), where SAGE II has a 1% negative trend relative to SBUV over the comparison period. There is a persistent disagreement of the two instruments in Umkehr layers 9 and 10 of +/-4% over the 5.5-year comparison period. In the equatorial zone this disagreement may be caused in part by a large positive trend (0.8 degrees K per year) in the National Meteorologica Center temperatures used to convert the SAGE II measurement of ozone density versus altitude to a pressure scale for comparison with SBUV. In the middle stratosphere (30-40 km), SBUV shows a 2-4% negative drift relative to SAGE II. If the actual ozone trends are considered, SBUV and SAGE II agree in showing little ozone change (less than 2%) between 1984 and 1990, except in layer 3 where SAGE II measures a large ozone decrease. But over 11 years, SBUV measured a 7% per decade ozone decrease between 40 and 50 km, decreasing in magnitude at lower altitudes, in good agreement with 11-year trends derived from the average of 5 Umkehr stations. C1 SOFTWARE CORP AMER, GREENBELT, MD 20706 USA. HUGHES STX CORP, GREENBELT, MD 20770 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP MCPETERS, RD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Flynn, Lawrence/B-6321-2009; McPeters, Richard/G-4955-2013 OI Flynn, Lawrence/0000-0001-6856-2614; McPeters, Richard/0000-0002-8926-8462 NR 35 TC 47 Z9 52 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 20513 EP 20524 DI 10.1029/94JD02008 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900003 ER PT J AU TUCK, AF FAHEY, DW LOEWENSTEIN, M PODOLSKE, JR KELLY, KK HOVDE, SJ MURPHY, DM ELKINS, JW AF TUCK, AF FAHEY, DW LOEWENSTEIN, M PODOLSKE, JR KELLY, KK HOVDE, SJ MURPHY, DM ELKINS, JW TI SPREAD OF DENITRIFICATION FROM 1987 ANTARCTIC AND 1988-1989 ARCTIC STRATOSPHERIC VORTICES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID POLAR VORTEX; OZONE EXPERIMENT; REACTIVE NITROGEN; AIRCRAFT MEASUREMENTS; POTENTIAL VORTICITY; WATER-VAPOR; LATE WINTER; OXIDE; HEMISPHERE; HOLE AB Vertical profiles of N2O and NOy taken by the ER-2 outside the vortex are used to construct average vertical profiles of F(NOy)= NOy/(A-N2O), where A is the tropospheric content of N2O three years prior to the measurements. The southern hemisphere had less nitrous oxide in the range 400 < theta < 470 K, by up to 25% relative to the northern hemisphere. F(NOy) is the ratio of NOy produced to N2O lost in a stratospheric air mass since entry from the troposphere. The profiles of F(NOy) have the following characteristics: (1) Relative to 1991-1992, a year without denitrification Inside or outside the vortex, the northern hemisphere in 1988-1989 showed denitrification outside the vortex ranging up to 25% and averaging 17% above theta = 425 K. (2) Relative to the northern hemisphere in 1991-1992, the southern hemisphere in 1987 showed denitrification outside the vortex ranging up to 32% and averaging 20% above theta = 400 K. (3) Below theta = 400 K the southern hemisphere showed enhancements of F(NOy) relative to the northern hemisphere in 1991-1992 ranging up to 200% at theta = 375 K, outside the vortex. Corresponding profiles of residual water, R(H2O) = H2O - 2 [1.6 - CH4], are considered and shown to be consistent with those of F(NOy) in the sense that they show deficits outside the Antarctic vortex, which was both dehydrated and denitrified, but not outside the 1988-1989 Arctic vortex, which was denitrified but not dehydrated. R(H2O) is the water content of stratospheric air with the contribution from methane oxidation subtracted. Comparison of F(NOy) and R(H2O) below 400 K outside the Antarctic vortex leads to the suggestion that dehydration in the Antarctic vortex occurs by the sedimentation of ice crystals large enough to fall out of the stratosphere, whereas denitrification occurs mainly on mixed nitric acid-water crystals which evaporate below the base of the vortex at theta = 400 K but above the tropopause. C1 NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. UNIV COLORADO, CIRES, BOULDER, CO 80309 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP TUCK, AF (reprint author), NOAA, AERON LAB, BOULDER, CO 80303 USA. RI Tuck, Adrian/F-6024-2011; Murphy, Daniel/J-4357-2012; Fahey, David/G-4499-2013 OI Tuck, Adrian/0000-0002-2074-0538; Murphy, Daniel/0000-0002-8091-7235; Fahey, David/0000-0003-1720-0634 NR 52 TC 15 Z9 15 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 20573 EP 20583 DI 10.1029/94JD01532 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900008 ER PT J AU CHANDRA, S MCPETERS, RD AF CHANDRA, S MCPETERS, RD TI THE SOLAR-CYCLE VARIATION OF OZONE IN THE STRATOSPHERE INFERRED FROM NIMBUS-7 AND NOAA-11 SATELLITES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; ULTRAVIOLET VARIATIONS; TEMPERATURE; MESOSPHERE; VARIABILITY; IRRADIANCE; PINATUBO; TRENDS; FLUX; SBUV AB The combined Nimbus 7 solar backscattered ultraviolet (SBUV) and NOAA 11 SBUV/2 ozone data, covering a period of more than a solar cycle (about 15 years), are used to study the UV response of ozone in the stratosphere. The study shows that about 2% change in total column ozone and about 5-7% change in ozone mixing ratio in the upper stratosphere (0.7 to 2 hPa) may be attributed to the change in the solar UV flux over a solar cycle. In the upper stratosphere, where photochemical processes are expected to play a major role, the measured solar cycle variation of ozone is significantly larger than inferred either from the photochemical models or from the ozone response to the 27-day solar UV modulation. For example, the observed solar cycle related change in ozone mixing ratio at 2 hPa is about 1% for 1% change in the solar UV flux near 200 nm. The inferred change in ozone from either the photochemical models or from the 27-day ozone-UV response is about a factor of 2-3 lower than this value. RP CHANDRA, S (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, MAIL STOP 916, GREENBELT, MD 20771 USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 36 TC 84 Z9 85 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 OCT 20 PY 1994 VL 99 IS D10 BP 20665 EP 20671 DI 10.1029/94JD02010 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900014 ER PT J AU LAMBETH, JD CALLIS, LB AF LAMBETH, JD CALLIS, LB TI TEMPERATURE-VARIATIONS IN THE MIDDLE AND UPPER-STRATOSPHERE - 1979-1992 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EL-CHICHON; ROCKETSONDE; HEMISPHERE; ATMOSPHERE; ERUPTION AB Temperature variations in the stratosphere from 1979 to 1992 are investigated using a 365-day running mean of the National Meteorological Center gridded analysis temperature data. Significant variations are seen at all levels between 70 and 1 mbar. The middle stratosphere shows temperature peaks during 1982 and 1983. The upper stratosphere has significant temperature declines between 1 and 10 mbar from 1981 to 1984. Temperatures at all levels recover to near their prior values after 1984, with the 5-mbar temperatures requiring the greatest time to fully recover. The temperature declines at 1 mbar occur in both hemispheres over all longitudes, and in every month of the year. The decreases are largest in the middle latitudes and the polar regions' and during the fall and the winter months. Such temperature variations, which appear to be of natural origin, must be taken into consideration when searching for temperature trends caused by the increase of CO2 or other greenhouse gases which affect the radiative balance of the Earth-atmosphere system or stratospheric ozone. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP LAMBETH, JD (reprint author), SCI APPLICAT INT CORP, 1 ENTERPRISE PKWY, SUITE 250, HAMPTON, VA 23666 USA. NR 20 TC 4 Z9 5 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 OCT 20 PY 1994 VL 99 IS D10 BP 20701 EP 20712 DI 10.1029/94JD00962 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900018 ER PT J AU STRAHAN, SE ROSENFIELD, JE LOEWENSTEIN, M PODOLSKE, JR WEAVER, A AF STRAHAN, SE ROSENFIELD, JE LOEWENSTEIN, M PODOLSKE, JR WEAVER, A TI EVOLUTION OF THE 1991-1992 ARCTIC VORTEX AND COMPARISON WITH THE GEOPHYSICAL FLUID-DYNAMICS LABORATORY SKYHI GENERAL-CIRCULATION MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITROUS-OXIDE; TRACER; AIRCRAFT; OZONE AB Nitrous oxide (N2O) measured on board the ER-2 aircraft during the Airborne Arctic Stratospheric Expedition 2 (AASE 2) has been used to monitor descent of air inside the Arctic vortex between October 1991 and March 1992. Monthly mean N2O fields are calculated from the flight data and then compared with mean fields calculated from the high-resolution Geophysical Fluid Dynamics Laboratory general circulation model SKYHI in order to evaluate the model's simulation of the polar vortex. From late fall through winter the model vortex evolves in much the same way as the 1991-1992 vortex, with N2O gradients at the edge becoming progressively steeper. The October to March trends in N2O profiles inside the vortex are used to verify daily net heating rates in the vortex that were computed from clear sky radiative heating rates and National Meteorological Center temperature observations. The computed heating rates successfully estimate the descent of vortex air from December through February but suggest that before December, air at high latitudes may not be isolated from the midlatitudes. SKYHI heating rates are in good agreement with the computed rates but tend to be slightly higher (i.e., less cooling) due to meteorological differences between SKYHI and the 1991-1992 winter. Three ER-2 flights measured N2O just north of the subtropical jet. These low-midlatitude profiles show only slight differences from the high-midlatitude profiles (45 degrees-60 degrees N), indicating strong meridional mixing in the midlatitude ''surf zone.'' Mean midwinter N2O profiles inside and outside the vortex calculated from AASE 2 data are shown to be nearly identical to 1989 AASE profiles, pointing to the N2O/potential temperature relationship as an excellent marker for vortex air. C1 APPL RES CORP, LANDOVER, MD 20785 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RI Strahan, Susan/H-1965-2012 NR 13 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 20713 EP 20723 DI 10.1029/94JD01333 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900019 ER PT J AU RANDALL, DA CESS, RD BLANCHET, JP CHALITA, S COLMAN, R DAZLICH, DA DELGENIO, AD KEUP, E LACIS, A LETREUT, H LIANG, XZ MCAVANEY, BJ MAHFOUF, JF MELESHKO, VP MORCRETTE, JJ NORRIS, PM POTTER, GL RIKUS, L ROECKNER, E ROYER, JF SCHLESE, U SHEININ, DA SOKOLOV, AP TAYLOR, KE WETHERALD, RT YAGAI, I ZHANG, MH AF RANDALL, DA CESS, RD BLANCHET, JP CHALITA, S COLMAN, R DAZLICH, DA DELGENIO, AD KEUP, E LACIS, A LETREUT, H LIANG, XZ MCAVANEY, BJ MAHFOUF, JF MELESHKO, VP MORCRETTE, JJ NORRIS, PM POTTER, GL RIKUS, L ROECKNER, E ROYER, JF SCHLESE, U SHEININ, DA SOKOLOV, AP TAYLOR, KE WETHERALD, RT YAGAI, I ZHANG, MH TI ANALYSIS OF SNOW FEEDBACKS IN 14 GENERAL-CIRCULATION MODELS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATE FEEDBACK; SURFACE ALBEDO; SEA ICE; COVER AB Snow feedbacks produced by 14 atmospheric general circulation models have been analyzed through idealized numerical experiments. Included in the analysis is an investigation of the surface energy budgets of the models. Negative or weak positive snow feedbacks occurred in some of the models, while others produced strong positive snow feedbacks. These feedbacks are due not only to melting snow, but also to increases in boundary temperature, changes in air temperature, changes in water vapor, and changes in cloudiness. As a result, the net response of each model is quite complex. We analyze in detail the responses of one model with a strong positive snow feedback and another with a weak negative snow feedback. Some of the models include a temperature dependence of the snow albedo, and this has significantly affected the results. C1 SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, MARINE SCI RES CTR, STONY BROOK, NY 11794 USA. CANADIAN CLIMATE CTR, ATMOSPHER ENVIRONM SERV, DOWNSVIEW, ON, CANADA. LAB METEOROL DYNAM, PARIS, FRANCE. BUR METEOROL RES CTR, MELBOURNE, VIC 3001, AUSTRALIA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. UNIV HAMBURG, MAX PLANCK INST METEOROL, W-2000 HAMBURG 13, GERMANY. SUNY ALBANY, ATMOSPHER SCI RES CTR, ALBANY, NY 12205 USA. CTR NATL RECH METEOROL, METRO FRANCE, F-31057 TOULOUSE, FRANCE. VOEIKOV MAIN GEOPHYS OBSERV, ST PETERSBURG, RUSSIA. EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS, READING RG2 9AX, BERKS, ENGLAND. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, CLIMATE RES GRP, SAN DIEGO, CA 92093 USA. LAWRENCE LIVERMORE NATL LAB, PROGRAM CLIMATE MODEL DIAG & INTERCOMPARISON, LIVERMORE, CA 94550 USA. PRINCETON UNIV, NOAA, GEOPHYS FLUID DYNAM LAB, PRINCETON, NJ 08542 USA. METEOROL RES INST, TSUKUBA, IBARAKI 305, JAPAN. RP RANDALL, DA (reprint author), COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80523 USA. RI Taylor, Karl/F-7290-2011; Lacis, Andrew/D-4658-2012; Del Genio, Anthony/D-4663-2012; Randall, David/E-6113-2011; Meleshko, Valentin/D-2157-2016; Norris, Peter/H-2008-2012 OI Taylor, Karl/0000-0002-6491-2135; Del Genio, Anthony/0000-0001-7450-1359; Randall, David/0000-0001-6935-4112; Norris, Peter/0000-0001-6807-9884 NR 21 TC 48 Z9 50 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 20757 EP 20771 DI 10.1029/94JD01633 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900021 ER PT J AU KIM, YS AF KIM, YS TI ANALYSIS AND COMPARISON OF DIURNAL-VARIATIONS OF CLOUD RADIATIVE FORCING - EARTH RADIATION BUDGET EXPERIMENT AND INTERNATIONAL SATELLITE CLOUD CLIMATOLOGY PROJECT RESULTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OUTGOING LONGWAVE RADIATION; TROPICAL PACIFIC; EXPERIMENT ERBE; CONVECTION; VARIABILITY; BALANCE; ALBEDO; MODEL AB Cloud radiative forcing (CRF) is the radiative impact of clouds on the Earth's radiation budget. This study examines the diurnal variations of CRF using the Earth Radiation Budget Experiment (ERBE) monthly hourly flux data and the flux data derived from the International Satellite Cloud Climatology Project (ISCCP) using the Goddard Institute for Space Studies general circulation model radiation code. The results for the months of April, July, and October 1985 and January 1986 are analyzed. We found that, in general, two data sets agreed. For longwave (LW) CRF the diurnal range over land is generally greater than that observed over oceans. For the 4-month averages the ERBE values are 15.8 W m(-2) and 6.8 W m(-2) for land and ocean, respectively, compared with the ISCCP calculated values of 18.4 W m(-2) and 8.0 W m(-2), respectively. The land/ocean contrast is largely associated with changes in cloud amount and the temperature difference between surface and cloud top. It would be more important to note that the clear-sky flux (i.e., surface temperature) variabilities are shown to be a major contributor to the large variabilities over land. The maximum diurnal range is found to be in the summer hemisphere, and the minimum values in the winter hemisphere. It is also shown that the daytime maximum and the nighttime minimum are seen over large portions of land, whereas they occur at any local hour over most oceans. For shortwave (SW) CRF the daytime maximum values are about twice as large as monthly averages, and their highest frequency occurs at local noon, indicating that solar insolation is a primary factor for the diurnal variation of SW CRF. However, the comparison of the ERBE data with the ISCCP results demonstrated that the largest differences in the diurnal range and monthly mean of LW CRF were associated with tropical convergence zones, where clear-sky fluxes could be easily biased by persistent cloudiness and the inadequate treatment of the atmospheric water vapor. C1 COLUMBIA UNIV, NEW YORK, NY 10032 USA. RP KIM, YS (reprint author), NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 22 TC 1 Z9 1 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 1994 VL 99 IS D10 BP 20847 EP 20862 DI 10.1029/94JD01722 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900026 ER PT J AU LIN, B ROSSOW, WB AF LIN, B ROSSOW, WB TI OBSERVATIONS OF CLOUD LIQUID WATER PATH OVER OCEANS - OPTICAL AND MICROWAVE REMOTE-SENSING METHODS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEA-SURFACE TEMPERATURE; PRECIPITABLE WATER; RADIATIVE-TRANSFER; NIMBUS-7 SMMR; WIND-SPEED; GLOBAL OCEANS; IMAGER SSM/I; SATELLITE; RETRIEVAL; MODEL AB Published estimates of cloud liquid water path (LWP) from satellite-measured microwave radiation show little agreement, even about the relative magnitudes of LWP in the tropics and midlatitudes. To understand these differences and to obtain a more reliable estimate, optical and microwave LWP retrieval methods are compared using the International Satellite Cloud Climatology Project (ISCCP) and special sensor microwave/imager (SSM/I) data. Errors in microwave LWP retrieval associated with uncertainties in surface, atmosphere, and cloud properties are assessed. Sea surface temperature may not produce great LWP errors, if accurate contemporaneous measurements are used in the retrieval. An uncertainty of estimated near-surface wind speed as high as 2 m/s produces uncertainty in LWP of about 5 mg/cm(2). Cloud liquid water temperature has only a small effect on LWP retrievals (rms errors < 2 mg/cm(2)), if errors in the temperature are < 5 degrees C; however, such errors can produce spurious variations of LWP with latitude and season. Errors in atmospheric column water vapor (CWV) are strongly coupled with errors in LWP (for some retrieval methods) causing errors as large as 30 mg/cm(2) Because microwave radiation is much less sensitive to clouds with small LWP (less than 7 mg/cm(2)) than visible wavelength radiation, the microwave results are very sensitive to the process used to separate clear and cloudy conditions. Different cloud detection sensitivities in different microwave retrieval methods bias estimated LWP values. Comparing ISCCP and SSM/I LWPs, we find that the two estimated values are consistent in global, zonal, and regional means for warm, nonprecipitating clouds, which have average LWP values of about 5 mg/cm(2) and occur much more frequently than precipitating clouds. Ice water path (IWP) can be roughly estimated from the differences between ISCCP total water path and SSM/I LWP for cold, nonprecipitating clouds. IWP in the winter hemisphere is about 3 times the LWP but only half the LWP in the summer hemisphere. Precipitating clouds contribute significantly to monthly, zonal mean LWP values determined from microwave, especially in the intertropical convergence zone (ITCZ), because they have almost 10 times the liquid water (cloud plus precipitation) of nonprecipitating clouds on average. There are significant differences among microwave LWP estimates associated with the treatment of precipitating clouds. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. RP LIN, B (reprint author), COLUMBIA UNIV, DEPT GEOL SCI, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Rossow, William/F-3138-2015 NR 69 TC 76 Z9 80 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 1994 VL 99 IS D10 BP 20907 EP 20927 DI 10.1029/94JD01831 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900030 ER PT J AU SODEN, BJ ACKERMAN, SA STARR, DO MELFI, SH FERRARE, RA AF SODEN, BJ ACKERMAN, SA STARR, DO MELFI, SH FERRARE, RA TI COMPARISON OF UPPER-TROPOSPHERIC WATER-VAPOR FROM GOES, RAMAN LIDAR, AND CROSS-CHAIN LORAN ATMOSPHERIC SOUNDING SYSTEM MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RELATIVE-HUMIDITY; AEROSOLS; MOISTURE AB Observations of upper tropospheric relative humidity obtained from Raman lidar and CLASS sonde instruments obtained during the FIRE Cirrus-II field program are compared with satellite measurements from the GOES 6.7-mu m channel. The 6.7-mu m channel is sensitive to water vapor integrated over a broad layer in the upper troposphere (roughly 500-200 mbar). Instantaneous measurements of the upper tropospheric relative humidity from GOES are shown to agree to within roughly 6% of the nearest lidar observations and 9% of the nearest CLASS observations. The CLASS data exhibit a slight yet systematic dry bias in upper tropospheric humidity, a result which is consistent with previous radiosonde intercomparisons. Temporal stratification of the CLASS data indicates that the magnitude of the bias is dependent upon the time of day, suggesting a solar heating effect in the radiosonde sensor. Using CLASS profiles, the impact of vertical variability in relative humidity upon the GOES upper tropospheric humidity measurements is also examined. The upper tropospheric humidity inferred from the GOES 6.7-mu m channel is demonstrated to agree to within roughly 5% of the relative humidity vertically averaged over the depth of atmosphere to which the 6.7-mu m channel is sensitive. The results of this study encourage the use of satellite measurements in the 6.7-mu m channel to quantitatively describe the distribution and temporal evolution of the upper tropospheric humidity field. C1 UNIV WISCONSIN, COOPERAT INST METEOROL SATELLITE STUDIES, MADISON, WI USA. PRINCETON UNIV, ATMOSPHER & OCEAN SCI PROGRAM, PRINCETON, NJ USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. HUGHES STX CORP, LANHAM, MD USA. RI Ackerman, Steven/G-1640-2011 OI Ackerman, Steven/0000-0002-4476-0269 NR 22 TC 22 Z9 22 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 OCT 20 PY 1994 VL 99 IS D10 BP 21005 EP 21016 DI 10.1029/94JD01721 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900037 ER PT J AU HOLZWORTH, RH SUVOROV, EV TRAKHTENGERTS, VY GOLDBERG, RA AF HOLZWORTH, RH SUVOROV, EV TRAKHTENGERTS, VY GOLDBERG, RA TI MIDDLE ATMOSPHERE ELECTRODYNAMICS AND COMPOSITION, A STEP WORKSHOP - PREFACE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Editorial Material ID MESOSPHERE; RADAR; ECHOES C1 RUSSIAN ACAD SCI, INST PHYS APPL, NIZHNII NOVGOROD 603600, RUSSIA. NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP HOLZWORTH, RH (reprint author), UNIV WASHINGTON, SEATTLE, WA 98195 USA. RI Goldberg, Richard /E-1881-2012 NR 16 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 21057 EP 21058 DI 10.1029/94JD02495 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900043 ER PT J AU GOLDBERG, RA BAKER, DN HERRERO, FA MCCARTHY, SP TWIGG, PA CROSKEY, CL HALE, LC AF GOLDBERG, RA BAKER, DN HERRERO, FA MCCARTHY, SP TWIGG, PA CROSKEY, CL HALE, LC TI ENERGY DEPOSITION AND MIDDLE ATMOSPHERE ELECTRODYNAMIC RESPONSE TO A HIGHLY RELATIVISTIC ELECTRON-PRECIPITATION EVENT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT Workshop on Electrodynamics and Composition of Mesosphere CY MAR 16-20, 1992 CL NIZHNIY NOVGOROD, RUSSIA SP SCOSTEP, SOLAR TERRESTRIAL ENERGY PROGRAM, WORKING GRP 4 ID SOLAR PROTON EVENTS AB Rocket data have been used to evaluate the characteristics of precipitating relativistic electrons and their effects on the electrodynamic structure of the middle atmosphere. These data were obtained at Poker Flat, Alaska, on May 13 and 14, 1990, during a midday, highly relativistic electron (HRE) precipitation event. Solid state detectors were used to measure the electron fluxes and their energy spectra. An X ray scintillator was included on each flight to measure bremsstrahlung X rays produced by energetic electrons impacting on the upper atmosphere. However, these were found to be of negligible importance for this particular event. The energy deposition by the electrons has been determined from the flux measurements and compared with in situ measurements of the atmospheric electrical response. The electrodynamic measurements were obtained by the same rockets and additionally on May 13, with an accompanying rocket. The impacting flux was highly irregular, containing short-lived bursts of relativistic electrons, mainly with energies below 0.5 MeV and with fluxes most enhanced between pitch angles of 0 degrees-20 degrees. Although the geostationary counterpart of this measured event was considered to be of relatively low intensity and hardness, energy deposition peaked near 75 km with fluxes approaching an ion pair production rate in excess of 100/cm(3) s. This exceeds peak fluxes in relativistic electron precipitation (REP) events as observed by us in numerous rocket soundings since 1976. Conductivity measurements from a blunt probe showed that negative electrical conductivities exceeded positive conductivities down to 50 km or lower, consistent with steady ionization by precipitating electrons above 1 MeV. These findings imply that the electrons from the outer radiation zone can modulate the electrical properties of the middle atmosphere to altitudes below 50 km. During the decline and activity minimum of the current solar cycle, we anticipate the occurrence of similar events but with fluxes 1-2 orders of magnitude above that reported here, based on studies of earlier solar cycles (e.g., Baker et al., 1993). C1 PENN STATE UNIV, COMMUN & SPACE SCI LAB, UNIVERSITY PK, PA 16802 USA. RP GOLDBERG, RA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, MAIL CODE 690, GREENBELT, MD 20771 USA. RI Goldberg, Richard /E-1881-2012 NR 22 TC 9 Z9 9 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 20 PY 1994 VL 99 IS D10 BP 21071 EP 21081 DI 10.1029/94JD00084 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN309 UT WOS:A1994PN30900045 ER PT J AU FRENDI, A MAESTRELLO, L BAYLISS, A AF FRENDI, A MAESTRELLO, L BAYLISS, A TI COUPLING BETWEEN PLATE VIBRATION AND ACOUSTIC RADIATION SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID HARMONIC EXCITATION; FLEXIBLE SURFACE; BOUNDARY-LAYER; FLAT-PLATE; CHAOS; TRANSITION; WAVES AB A detailed numerical investigation of the coupling between the vibration of a flexible plate and the ensuing acoustic radiation is described. The non-linear Euler equations are used to describe the acoustic fluid, while the non-linear von Karman plate equations are used to describe the plate response. The plate is excited by a time harmonic, normally incident acoustic source, the amplitude of which is varied. We compute and describe both linear and non-linear time periodic vibrations as well as aperiodic responses. In each case, we also describe the acoustic radiation pattern resulting from the plate vibration. We find that for low excitation levels, so that the plate response is essentially linear, the effect of acoustic coupling is negligible. However, as the level of the loading increases, the radiated pressure from a plate undergoing non-linear or chaotic vibrations is found to propagate non-linearly into the far-field. The non-linearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NORTHWESTERN UNIV, CHICAGO, IL 60035 USA. RP FRENDI, A (reprint author), ANALYT SERV & MAT INC, HAMPTON, VA 23666 USA. RI Bayliss, Alvin/B-7337-2009 NR 32 TC 27 Z9 27 U1 0 U2 3 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD OCT 20 PY 1994 VL 177 IS 2 BP 207 EP 226 DI 10.1006/jsvi.1994.1428 PG 20 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA PN001 UT WOS:A1994PN00100005 ER PT J AU ZUBER, MT AF ZUBER, MT TI PLATE-TECTONICS - FOLDING A JELLY SANDWICH SO NATURE LA English DT Editorial Material ID DEFORMATION C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. RP ZUBER, MT (reprint author), JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218, USA. NR 8 TC 8 Z9 9 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 20 PY 1994 VL 371 IS 6499 BP 650 EP 651 DI 10.1038/371650a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PM773 UT WOS:A1994PM77300024 ER PT J AU KHUNDKAR, LR PERRY, JW HANSON, JE DERVAN, PB AF KHUNDKAR, LR PERRY, JW HANSON, JE DERVAN, PB TI WEAK TEMPERATURE-DEPENDENCE OF ELECTRON-TRANSFER RATES IN FIXED-DISTANCE PORPHYRIN-QUINONE MODEL SYSTEMS SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID FREE-ENERGY DEPENDENCE; MARCUS INVERTED REGION; SOLVENT DEPENDENCE; CHARGE-SEPARATION; RHODOPSEUDOMONAS-SPHAEROIDES; BIOLOGICAL MOLECULES; TRANSFER KINETICS; RADICAL-ANIONS; RELAXATION; DYNAMICS AB Electron transfer rate constants of several derivatives of [5-(4'-(4''-(2''',5'''-benzoquinonyl)bicyclo[2.2.2]octyl)phenyl)-2,3,7,8,12,13,17,18-octamethylporphyrinato]zinc(II) have been measured as a function of temperature in 2-methyltetrahydrofuran, toluene, and toluene-d(8). The observed temperature dependencies of the electron transfer rate constants are relatively weak in both the polar and nonpolar solvents. Nonexponential ET dynamics are observed at low temperatures and described in terms of an initial (k(ET)(0)) and an average ET rate constant (k(av)). The k(ET)(0) values for the molecules with different driving forces, spanning a range of 0.2 eV, show parallel trends over the range of temperatures studied. The trends in k(ET)(0) are described in terms of the effects of temperature-dependent changes in solvent dielectric constants on the barrier height. Good agreement is observed for the case of toluene solvent, using a semiclassical model, but poorer quantitative agreement is found for the 2-methyltetrahydrofuran data. The temperature dependence of k(av) is described using a model incorporating an angle-dependent electronic coupling and interconversion of rotational conformers. A temperature-dependent solvent isotope effect is observed on going from toluene to toluene-d(8), with k(ET)(0)(toluene)/k(ET)(0)(toluene-d(8)) being as large at 1.5 over the range of temperatures studied. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,DIV CHEM & CHEM ENGN,PASADENA,CA 91125. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 75 TC 44 Z9 44 U1 0 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD OCT 19 PY 1994 VL 116 IS 21 BP 9700 EP 9709 DI 10.1021/ja00100a040 PG 10 WC Chemistry, Multidisciplinary SC Chemistry GA PN452 UT WOS:A1994PN45200040 ER PT J AU POTTER, AE MORGAN, TH AF POTTER, AE MORGAN, TH TI VARIATION OF LUNAR SODIUM EMISSION INTENSITY WITH PHASE-ANGLE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE; MOON; SURFACE AB We report new measurements of the sodium emission intensity seen in a line of sight just above the surface of the Moon. These data show a strong dependence on lunar phase. The emission intensity decreases from a maximum around first quarter (phase angle 90-degrees) to very small values near full Moon (phase angle 0-degrees). This suggests that the rate of sodium vapor production from the lunar surface is largest at the subsolar point and becomes small near the terminator. However, the sodium emission near full Moon falls below that which would be expected for solar photon-driven processes. Since the solar wind flux decreases substantially when the Moon enters the Earth's magnetotail near full Moon, while the global solar photon flux is undiminished, we suggest that solar wind sputtering is the dominant process for sodium production. C1 SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78228. RP POTTER, AE (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 11 TC 38 Z9 38 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 1994 VL 21 IS 21 BP 2263 EP 2266 DI 10.1029/94GL01702 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PN308 UT WOS:A1994PN30800001 ER PT J AU TSURUTANI, BT HO, CM SMITH, EJ NEUGEBAUER, M GOLDSTEIN, BE MOK, JS ARBALLO, JK BALOGH, A SOUTHWOOD, DJ FELDMAN, WC AF TSURUTANI, BT HO, CM SMITH, EJ NEUGEBAUER, M GOLDSTEIN, BE MOK, JS ARBALLO, JK BALOGH, A SOUTHWOOD, DJ FELDMAN, WC TI THE RELATIONSHIP BETWEEN INTERPLANETARY DISCONTINUITIES AND ALFVEN WAVES - ULYSSES OBSERVATIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR; STORMS AB The rate of occurrence of interplanetary discontinuities (ROID) is examined using Ulysses magnetic field and plasma data from 1 to 5 AU radial distance from the Sun and at high heliographic latitudes. We find two regions where the ROID is high: in stream-stream interaction regions and in Alfven wave trains. This latter feature is particularly obvious at high latitudes when Ulysses enters a high speed stream associated with a polar coronal hole. These streams are characterized by the presence of continuous, large-amplitude (DELTAB/\B\ approximately 1-2) Alfven waves and an extraordinarily high ROID value (approximately 150 discontinuities/day). In a number of intervals examined, it is found that (rotational) discontinuities are an integral part of the Alfven waves. The nonlinear Alfven waves are spherically polarized, i.e., the tip of the perturbation vector resides on the surface of a sphere (a consequence of constant \B\). The slowly rotating part of the waves rotates approximately 270-degrees in phase. There is a slight arc in the B1-B2 hodogram, suggesting an almost linear polarization. The phase rotation associated with the discontinuity is approximately 90-degrees, lies in the same plane as the slowly rotating part of the Alfven wave, and therefore completes the 360-degrees phase rotation. The best description of the overall Alfven wave plus discontinuity is a spherical, arc-polarized, phase-steepened wave. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP TSURUTANI, BT (reprint author), JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 169 506,PASADENA,CA 91109, USA. NR 12 TC 103 Z9 107 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 15 PY 1994 VL 21 IS 21 BP 2267 EP 2270 DI 10.1029/94GL02194 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PN308 UT WOS:A1994PN30800002 ER PT J AU GOSLING, JT MCCOMAS, DJ PHILLIPS, JL WEISS, LA PIZZO, VJ GOLDSTEIN, BE FORSYTH, RJ AF GOSLING, JT MCCOMAS, DJ PHILLIPS, JL WEISS, LA PIZZO, VJ GOLDSTEIN, BE FORSYTH, RJ TI A NEW CLASS OF FORWARD-REVERSE SHOCK PAIRS IN THE SOLAR-WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID COROTATING SHOCKS; PIONEER-10 AB A new class of forward-reverse shock pairs in the solar wind has been discovered using Ulysses observations at high heliographic latitudes. These shock pairs are produced by expansion of coronal mass ejections, CMEs, that have internal pressures that are higher than, and speeds that are comparable to, that of the surrounding solar wind plasma. Of six certain CMEs observed poleward of S31-degrees, three have associated shock pairs of this nature. We suggest that high internal CME pressures may exist primarily for events that have high speeds close to the surface of the Sun. C1 SAN JUAN INST,SAN JUAN CAPISTRANO,CA. NOAA,SEL,BOULDER,CO 80303. JET PROP LAB,PASADENA,CA 91109. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP GOSLING, JT (reprint author), LOS ALAMOS NATL LAB,MS D466,LOS ALAMOS,NM 87545, USA. NR 15 TC 98 Z9 98 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 1994 VL 21 IS 21 BP 2271 EP 2274 DI 10.1029/94GL02245 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PN308 UT WOS:A1994PN30800003 ER PT J AU BARCLAY, VJ DATEO, CE HAMILTON, IP AF BARCLAY, VJ DATEO, CE HAMILTON, IP TI AB-INITIO VIBRATIONAL LEVELS FOR HO2 AND VIBRATIONAL SPLITTINGS FOR HYDROGEN-ATOM TRANSFER SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID POTENTIAL-ENERGY SURFACE; MANY-BODY EXPANSION; LASER SPECTROSCOPY; MOLECULES; STATES AB We calculate vibrational levels and wave functions for HO2 using the recently reported ab initio potential energy points of Walch and Duchovic [J. Chem. Phys. 94, 7068 (1991)] as fit by Dateo (unpublished). There is intramolecular hydrogen atom transfer when the hydrogen atom tunnels through a T-shaped saddle point separating the two equivalent equilibrium geometries, and correspondingly, the vibrational levels are split. We focus on vibrational levels and wave functions with significant splitting. The first three vibrational levels with splitting greater than 2 cm(-1) are (1,5,0), (0,7,1), and (0,8,0), where v(2) is the O-O-H bend quantum number. We discuss the dynamics of hydrogen atom transfer, in particular, the O-O distances at which hydrogen atom transfer is most probable for these vibrational levels. C1 UNIV TORONTO,DEPT CHEM,TORONTO M5S 1A1,ON,CANADA. NASA AMES RES CTR M52303,INST THERMOSCI,MOFFETT FIELD,CA 94035. WILFRID LAURIER UNIV,DEPT CHEM,WATERLOO N2L 3C5,ON,CANADA. NR 21 TC 18 Z9 18 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 15 PY 1994 VL 101 IS 8 BP 6766 EP 6775 DI 10.1063/1.468372 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PL716 UT WOS:A1994PL71600040 ER PT J AU CHEN, D BUSALACCHI, AJ ROTHSTEIN, LM AF CHEN, D BUSALACCHI, AJ ROTHSTEIN, LM TI THE ROLES OF VERTICAL MIXING, SOLAR-RADIATION, AND WIND STRESS IN A MODEL SIMULATION OF THE SEA-SURFACE TEMPERATURE SEASONAL CYCLE IN THE TROPICAL PACIFIC-OCEAN SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID VARIABILITY; PRODUCTS AB The climatological seasonal cycle of sea surface temperature (SST) in the tropical Pacific is simulated using a newly developed upper ocean model. The roles of vertical mixing, solar radiation, and wind stress are investigated in a hierarchy of numerical experiments with various combinations of vertical mixing algorithms and surface-forcing products. It is found that the large SST annual cycle in the eastern equatorial Pacific is, to a large extent, controlled by the annually varying mixed layer depth which, in turn, is mainly determined by the competing effects of solar radiation and wind forcing. With the application of our hybrid vertical mixing scheme the model-simulated SST annual cycle is much improved in both amplitude and phase as compared to the case of a constant mixed layer depth. Beside the strong effects on vertical mixing, solar radiation is the primary heating term in the surface layer heat budget, and wind forcing influences SST by driving oceanic advective processes that redistribute heat in the upper ocean. For example, the SST seasonal cycle in the western equatorial Pacific basically follows the seminanual variation of solar heating, and the cycle in the central equatorial region is significantly affected by the zonal advective heat flux associated with the seasonally reversing South Equatorial Current. It has been shown in our experiments that the amount of heat flux modification needed to eliminate the annual mean SST errors in the model is, on average, no larger than the annual mean uncertainties among the various surface flux products used in this study. Whereas a bias correction is needed to account for remaining uncertainties in the annual mean heat flux, this study demonstrates that with proper treatment of mixed layer physics and realistic forcing functions the seasonal variability of SST is capable of being simulated successfully in response to external forcing without relying on a relaxation or damping formulation for the dominant surface heat flux contributions. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771. RP CHEN, D (reprint author), UNIV RHODE ISL,GRAD SCH OCEANOG,NARRAGANSETT,RI 02882, USA. RI Chen, Dake/E-7082-2011 NR 26 TC 106 Z9 114 U1 3 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 1994 VL 99 IS C10 BP 20345 EP 20359 DI 10.1029/94JC01621 PG 15 WC Oceanography SC Oceanography GA PM276 UT WOS:A1994PM27600002 ER PT J AU MCKAY, CP CLOW, GD ANDERSEN, DT WHARTON, RA AF MCKAY, CP CLOW, GD ANDERSEN, DT WHARTON, RA TI LIGHT TRANSMISSION AND REFLECTION IN PERENNIALLY ICE-COVERED LAKE HOARE, ANTARCTICA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA ICE; RADIATIVE-TRANSFER; HEATING RATES; ABSORPTION; LIGHT; SEDIMENTATION; ATMOSPHERES; COMMUNITIES; SCATTERING; IRRADIANCE AB We have investigated the transmission and albedo of the perennial ice cover on Lake Hoare, Antarctica. Our database consists of year-round measurements of the photosynthetically active radiation (400-700 nm) under the ice, measurements of the spatial variation of the under-ice light in midsummer, and spectrally resolved measurements from 400 to 700 nm of the albedo and transmission of the ice cover in early (November) and in midsummer (January). Our results show that the transmission decreases in the first part of summer, dropping by a factor of approximately 4 from November to January. We suggest that this is due to heating in the upper layers of the ice cover and the formation of Tyndall figures. Later in the summer when a significant liquid water fraction occurs within the ice cover, the transmission increases. In the fall when the ice cover freezes solid the transmission drops markedly. The spectrally resolved measurements from 400 to 700 nm show that approximately 2-5% of the incident light in this spectral region penetrates the 3.5-m thick ice cover. We have analyzed the spectral data using a two-stream scattering solution to the radiative transfer equation with three vertical layers in the ice cover. A surficial glaze of scattering ice 1 cm thick overlies a layer of sandy, bubbly ice about a meter thick, and below this is a thick layer of sand-free ice with bubbles. We find that the ice cover is virtually opaque at wavelengths longer than 800 nm. The net transmission of solar energy is approximately 2%. Significant changes in the thickness of the ice cover have been reported at Lake Hoare. These are due primarily to changes in the thickness of the bottom layer only. Because this layer is relatively clear, the effect on the transmission through the ice cover from these changes is less than would be predicted assuming a homogeneous ice cover. C1 DESERT RES INST,CTR BIOL SCI,RENO,NV 89506. US GEOL SURVEY,ASTROGEOL BRANCH,MENLO PK,CA 94025. RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 31 TC 37 Z9 37 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 1994 VL 99 IS C10 BP 20427 EP 20444 DI 10.1029/94JC01414 PG 18 WC Oceanography SC Oceanography GA PM276 UT WOS:A1994PM27600009 ER PT J AU ROOD, RB GELLER, MA AF ROOD, RB GELLER, MA TI THE UPPER-ATMOSPHERE RESEARCH SATELLITE - EARLY SCIENTIFIC RESULTS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Editorial Material C1 SUNY STONY BROOK,STONY BROOK,NY 11794. RP ROOD, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 0 TC 4 Z9 4 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 OCT 15 PY 1994 VL 51 IS 20 BP 2781 EP 2782 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700001 ER PT J AU ONEILL, A GROSE, WL POPE, VD MACLEAN, H SWINBANK, R AF ONEILL, A GROSE, WL POPE, VD MACLEAN, H SWINBANK, R TI EVOLUTION OF THE STRATOSPHERE DURING NORTHERN WINTER 1991/92 AS DIAGNOSED FROM UK-METEOROLOGICAL-OFFICE ANALYSES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID POTENTIAL VORTICITY; POLAR VORTEX; DYNAMICS; MODEL; OZONE; AIR AB Meteorological analyses, produced at the U.K. Meteorological Office by data assimilation, are used to study the circulation of the stratosphere in the Northern Hemisphere during winter 1991/92. The analyses are supplemented by Lagrangian visualizations of the circulation. The main features discussed are 1) the changes in vertical structure of the circulation, 2) the merger of anticyclones that precipitated a strong stratospheric warming, 3) vortex roll up in the upper stratosphere, 4) the entrainment of air into the polar vortex in the middle and upper stratosphere, and 5) the influence of tropospheric blocking on the lower stratosphere. The study provides a meteorological basis for the interpretation of data from the Upper Atmosphere Research Satellite. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. METEOROL OFF,BRACKNELL RB12 2SZ,BERKS,ENGLAND. RP ONEILL, A (reprint author), UNIV READING,DEPT METEOROL,CGAM,READING RG6 2AU,BERKS,ENGLAND. NR 35 TC 59 Z9 59 U1 1 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 OCT 15 PY 1994 VL 51 IS 20 BP 2800 EP 2817 DI 10.1175/1520-0469(1994)051<2800:EOTSDN>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700003 ER PT J AU FROIDEVAUX, L WATERS, JW READ, WG ELSON, LS FLOWER, DA JARNOT, RF AF FROIDEVAUX, L WATERS, JW READ, WG ELSON, LS FLOWER, DA JARNOT, RF TI GLOBAL OZONE OBSERVATIONS FROM THE UARS MLS - AN OVERVIEW OF ZONAL-MEAN RESULTS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID QUASI-BIENNIAL OSCILLATION; ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; TWO-DIMENSIONAL MODEL; MT-PINATUBO; STRATOSPHERIC OZONE; TROPOSPHERIC OZONE; HETEROGENEOUS CHEMISTRY; SULFATE AEROSOLS; MOUNT-PINATUBO AB Global ozone observations from the Microwave Limb Sounder (MLS) aboard the Upper Atmosphere Research Satellite (UARS) are presented, in both vertically resolved and column abundance formats. The authors review the zonal-mean ozone variations measured over the two and a half years since launch in September 1991. Well-known features such as the annual and semiannual variations are ubiquitous. In the equatorial regions, longer-term changes are believed to be related to the quasi-biennial oscillation (QBO), with a strong semiannual signal above 20 hPa. Ozone values near 50 hPa exhibit an equatorial low from October 1991 to June 1992, after which the low ozone pattern splits into two subtropical lows (possibly in connection with residual circulation changes tied to the QBO) and returns to an equatorial low in September 1993. The ozone hole development at high southern latitudes is apparent in MLS column data integrated down to 100 hPa, with a pattern generally consistent with Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) measurements of total column; the MLS data reinforce current knowledge of this lower-stratospheric phenomenon by providing a height-dependent view of the variations. The region of 30-degrees-S to 30-degrees-N (an area equal to half the global area) shows very little change in the ozone column from year to year and within each year. The most striking ozone changes have occurred at northern midlatitudes, with the October 1992 to July 1993 column values significantly lower than during the prior year. The zonal-mean changes manifest themselves as a slower rate of increase during the 1992/93 winter, and there is some evidence for a lower fall minimum. A recovery occurs during late summer of 1993; early 1994 values are significantly larger than during the two previous winters. These results are in general agreement with variations measured by the Nimbus-7 TOMS and Meteor-3 TOMS instruments at midlatitudes. However, the southern midlatitudes exhibit less of a column ozone decrease (relative to the north) in the MLS data (down to 100 hPa) than in the TOMS column results. The timing and latitudinal extent of the northern midlatitude decreases appear to rule out observed ClO enhancements in the Arctic vortex, with related chemical processing and ozone dilution effects, as a unique cause. Local depletion from ClO-related chemical mechanisms alone is also not sufficient, based on MLS ClO data. The puzzling asymmetric nature of the changes probably requires a dynamical component as an explanation. A combination of effects (including chemical destruction via heterogeneous processes and QBO phasing) apparently needs to be invoked. This dataset will place constraints on future modeling studies, which are required to better understand the source of the observed changes. Finally, residual ozone values extracted from TOMS-minus-MLS column data are briefly presented as a preliminary view into the potential usefulness of such studies, with information on tropospheric ozone as an ultimate goal. RP FROIDEVAUX, L (reprint author), JET PROP LAB,MAIL STOP 183-701,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 99 TC 51 Z9 51 U1 3 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 2846 EP 2866 DI 10.1175/1520-0469(1994)051<2846:GOOFTM>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700006 ER PT J AU ELSON, LS MANNEY, GL FROIDEVAUX, L WATERS, JW AF ELSON, LS MANNEY, GL FROIDEVAUX, L WATERS, JW TI LARGE-SCALE VARIATIONS IN OZONE FROM THE 1ST 2 YEARS OF UARS MLS DATA SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID STRATOSPHERE; WAVES; HEMISPHERE; WINTER; ATMOSPHERE; STABILITY AB Two years of stratospheric measurements of ozone from the Upper Atmosphere Research Satellite Microwave Limb Sounder are examined in order to characterize large horizontal scale wave variations. The use of Fourier analysis allows the detection of variations from daily through seasonal and interannual timescales. High-latitude winter variations at 10 hPa often have very large amplitudes, but smaller midlatitude variations are more ubiquitous. Some variations have the characteristics of locally generated instabilities. Correlations of wave features with changes in the zonal-mean ozone at 10 hPa suggest the presence of significant horizontal motions during strong wintertime polar warming events. Such correlations are not evident at other levels. Spectral analysis of the large-scale variations show most waves to be slowly propagating. In contrast to some past observations, equatorial regions are shown to lack large amplitude wave events. RP ELSON, LS (reprint author), JET PROP LAB,M-S 183-701,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 16 Z9 16 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 2867 EP 2876 DI 10.1175/1520-0469(1994)051<2867:LSVIOF>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700007 ER PT J AU PARK, JH RUSSELL, JM AF PARK, JH RUSSELL, JM TI SUMMER POLAR CHEMISTRY OBSERVATIONS IN THE STRATOSPHERE MADE BY HALOE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID TOTAL OZONE; SATELLITE; CHLORINE; SINK AB Regions of low stratospheric ozone that are anticorrelated with HCl, NO, and NO2 levels have been observed in the Arctic and Antarctic summers of 1992 and 1993 by the Halogen Occultation Experiment on the UARS platform. The low ozone areas are confined to the approximately 8 -45 mb (approximately 33 -21 km) region and poleward of approximately 60-degrees in each hemisphere. While low polar summer ozone has been observed before, this is the first time simultaneous observations of relevant nitrogen and chlorine chemical species have been made. The phenomenon appears to be a recurring geophysical feature, and the satellite data should provide an excellent opportunity to improve our understanding of the chemistry causing these conditions. RP PARK, JH (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 21 TC 23 Z9 23 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 OCT 15 PY 1994 VL 51 IS 20 BP 2903 EP 2913 DI 10.1175/1520-0469(1994)051<2903:SPCOIT>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700009 ER PT J AU LAHOZ, WA ONEILL, A CARR, ES HARWOOD, RS FROIDEVAUX, L READ, WG WATERS, JW KUMER, JB MERGENTHALER, JL ROCHE, AE PECKHAM, GE SWINBANK, R AF LAHOZ, WA ONEILL, A CARR, ES HARWOOD, RS FROIDEVAUX, L READ, WG WATERS, JW KUMER, JB MERGENTHALER, JL ROCHE, AE PECKHAM, GE SWINBANK, R TI 3-DIMENSIONAL EVOLUTION OF WATER-VAPOR DISTRIBUTIONS IN THE NORTHERN-HEMISPHERE STRATOSPHERE AS OBSERVED BY THE MLS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; OZONE; VORTEX; CLAES; UARS; CH4; N2O AB The three-dimensional evolution of stratospheric water vapor distributions observed by the Microwave Limb Sounder (MLS) during the period October 1991-July 1992 is documented. The transport features inferred from the MLS water vapor distributions are corroborated using othe dynamical fields, namely, nitrous oxide from the Cryogenic Limb Array Etalon Spectrometer instrument, analyzed winds from the U.K. Meteorological Office (UKMO), UKMO-derived potential vorticity, and the diabatic heating field. By taking a vortex-centered view and an along-track view, the authors observe in great detail the vertical and horizontal structure of the northern winter stratosphere. It is demonstrated that the water vapor distributions show clear signatures of the effects of diabatic descent through isentropic surfaces and quasi-horizontal transport along isentropic surfaces, and that the large-scale winter flow is organized by the interaction between the westerly polar vortex and the Aleutian high. C1 UNIV EDINBURGH,DEPT METEOROL,EDINBURGH EH8 9YL,MIDLOTHIAN,SCOTLAND. HERIOT WATT UNIV,DEPT PHYS,EDINBURGH EH1 1HX,MIDLOTHIAN,SCOTLAND. METEOROL OFF,BRACKNELL RB12 2SZ,BERKS,ENGLAND. JET PROP LAB,PASADENA,CA 91109. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. RP LAHOZ, WA (reprint author), UNIV READING,DEPT METEOROL,CTR GLOBAL ATMOSPHER MODELLING,READING RG6 2AU,ENGLAND. NR 30 TC 31 Z9 31 U1 1 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 OCT 15 PY 1994 VL 51 IS 20 BP 2914 EP 2930 DI 10.1175/1520-0469(1994)051<2914:TDEOWV>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700010 ER PT J AU PIERCE, RB GROSE, WL RUSSELL, JM TUCK, AF SWINBANK, R ONEILL, A AF PIERCE, RB GROSE, WL RUSSELL, JM TUCK, AF SWINBANK, R ONEILL, A TI SPRING DEHYDRATION IN THE ANTARCTIC STRATOSPHERIC VORTEX OBSERVED BY HALOE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article AB The distribution of dehydrated air in the middle and lower stratosphere during the 1992 Southern Hemisphere spring is investigated using Halogen Occultation Experiment (HALOE) observations and trajectory techniques. Comparisons between previously published Version 9 and the improved Version 16 retrievals on the 700-K isentropic surface show very slight (0.05 ppmv) increases in Version 16 CH4 relative to Version 9 within the polar vortex. Version 16 H2O mixing ratios show a reduction of 0.5 ppmv relative to Version 9 within the polar night jet and a reduction of nearly 1.0 ppmv in middle latitudes when compared to Version 9. The Version 16 HALOE retrievals show low mixing ratios of total hydrogen (2CH4 + H2O) within the polar vortex on both 700 and 425 K isentropic surfaces relative to typical middle-stratospheric 2CH4 + H2O mixing ratios. The low 2CH4 + H2O mixing ratios are associated with dehydration. Slight reductions in total hydrogen, relative to typical middle-stratospheric values, are found at these levels throughout the Southern Hemisphere during this period. Trajectory calculations show that middle-latitude air masses are composed of a mixture of air from within the polar night jet and air from middle latitudes. A strong kinematic barrier to large-scale exchange is found on the poleward flank of the polar night jet at 700 K. A much weaker kinematic barrier is found at 425 K. The impact of the finite tangent pathlength of the HALOE measurements is investigated using an idealized tracer distribution. This experiment suggests that HALOE should be able to resolve the kinematic barrier, if it exists. C1 NOAA,AERON LAB,BOULDER,CO 80303. UNIV READING,READING RG6 2AH,BERKS,ENGLAND. METEOROL OFF,BRACKNELL RB12 2SZ,BERKS,ENGLAND. RP PIERCE, RB (reprint author), NASA,LANGLEY RES CTR,MS 401B,HAMPTON,VA 23665, USA. RI Pierce, Robert Bradley/F-5609-2010; Tuck, Adrian/F-6024-2011 OI Pierce, Robert Bradley/0000-0002-2767-1643; Tuck, Adrian/0000-0002-2074-0538 NR 13 TC 20 Z9 20 U1 1 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 OCT 15 PY 1994 VL 51 IS 20 BP 2931 EP 2941 DI 10.1175/1520-0469(1994)051<2931:SDITAS>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700011 ER PT J AU BITHELL, M GRAY, LJ HARRIES, JE RUSSELL, JM TUCK, AF AF BITHELL, M GRAY, LJ HARRIES, JE RUSSELL, JM TUCK, AF TI SYNOPTIC INTERPRETATION OF MEASUREMENTS FROM HALOE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID STRATOSPHERIC POLAR VORTEX; BREAKING PLANETARY-WAVES; ANTARCTIC OZONE HOLE; TRACER DISTRIBUTIONS; TRANSPORT; MODEL; DYNAMICS AB The degree to which the Southern Hemisphere polar vortex is isolated against horizontal (isentropic) mixing is investigated using data from the Halogen Occulation Experiment (HALOE), U.K. Meteorological Office (UKMO) potential vorticity (PV), and contour advection diagnostics. Measurements of methane and water vapor taken by HALOE during a disturbed period in the Southern Hemisphere springtime (21 September - 15 October 1992) are interpreted in light of the prevailing synoptic meteorology. Daily fields of winds and PV are shown to be essential in the interpretation of the data. A climatological high pressure region is responsible for a distorted vortex, and a substantial ''vortex stripping'' event is present, associated with the early stages of vortex breakdown. This leads to significant temporal, zonal, and altitudinal variations in the distribution of tracers. The authors point out the difficulties this presents for the interpretation of solar occultation data, especially with regard to the use of zonal average time series. Longitude-height methane distributions from two days during the period are examined. Both days show substantial variations in abundance around a latitude circle. In particular the authors investigate HALOE measurements at 77-degrees-S on 15 October 1992, which indicate an abundance of methane in the height region 600-2000 K (approximately 30-1 mb) that is more typical of midlatitude air. Similar distributions, observed in the 1991 HALOE data, have previously been interpreted as evidence for the penetration of midlatitude air into the vortex. Gradients of potential vorticity and contour advection diagnostics are employed to examine whether the UKMO winds are consistent with this hypothesis in 1992. Although midlatitude air is able to penetrate poleward of the main jet core by advection processes alone, an essentially intact inner core of vortex air remains, which does not mix to any great extent with air from lower latitudes. The authors show that the high-latitude HALOE abundances that are typical of midlatitude air were observed in a region of extensive filamentation and mixing, rather than within the inner, more isolated, core. C1 DARESBURY & RUTHERFORD APPLETON LAB,CHILTON,ENGLAND. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,LONDON SW7 2AZ,ENGLAND. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NOAA,AERON LAB,BOULDER,CO 80303. RI Gray, Lesley/D-3610-2009; Tuck, Adrian/F-6024-2011 OI Tuck, Adrian/0000-0002-2074-0538 NR 41 TC 22 Z9 22 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 OCT 15 PY 1994 VL 51 IS 20 BP 2942 EP 2956 DI 10.1175/1520-0469(1994)051<2942:SIOMFH>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700012 ER PT J AU PIERCE, RB FAIRLIE, TD GROSE, WL SWINBANK, R ONEILL, A AF PIERCE, RB FAIRLIE, TD GROSE, WL SWINBANK, R ONEILL, A TI MIXING PROCESSES WITHIN THE POLAR NIGHT JET SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MIDDLE ATMOSPHERE; VORTEX; STRATOSPHERE; WAVES AB Lagrangian material line simulations are performed using U.K. Meteorological Office assimilated winds and temperatures to examine mixing processes in the middle- and lower-stratospheric polar night jet during the 1992 Southern Hemisphere spring and Northern Hemisphere winter. The Lagrangian simulations are undertaken to provide insight into the effects of mixing within the polar night jet on observations of the polar vortex made by instruments onboard the Upper Atmosphere Research Satellite during these periods. A moderate to strong kinematic barrier to large-scale isentropic exchange, similar to the barrier identified in GCM simulations, is identified during both of these periods. Characteristics timescales for mixing by large-scale isentropic motions within the polar night jet range from 20 days in the Southern Hemisphere lower stratosphere to years in the Northern Hemisphere middle stratosphere. The long mixing timescales found in the Northern Hemisphere polar night jet do not persist. Instead, the Northern Hemisphere kinematic barriers are broken down as part of the large-scale stratospheric response to a strong tropospheric blocking event. A series of Lagrangian experiments are conducted to investigate the sensitivity of the kinematic barrier to diabatic effects and to small-scale inertial gravity wave motions. Differential diabatic descent is found to have a significant impact on mixing processes within the Southern Hemisphere middle-stratospheric jet core. The interaction between small-scale displacements by idealized, inertial gravity waves and the large-scale flow is found to have a significant impact on mixing within the polar night jet in both hemispheres. These sensitivity experiments suggests that scales of motion that are unresolved in global assimilated datasets may contribute to mass exchange across the kinematic barrier to large-scale isentropic motion. C1 SCI & TECHNOL CORP,HAMPTON,VA. METEOROL OFF,BRACKNELL RB12 2SZ,BERKS,ENGLAND. UNIV READING,READING RG6 2AH,BERKS,ENGLAND. RP PIERCE, RB (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. RI Pierce, Robert Bradley/F-5609-2010 OI Pierce, Robert Bradley/0000-0002-2767-1643 NR 21 TC 55 Z9 55 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 2957 EP 2972 DI 10.1175/1520-0469(1994)051<2957:MPWTPN>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700013 ER PT J AU MANNEY, GL ZUREK, RW ONEILL, A SWINBANK, R AF MANNEY, GL ZUREK, RW ONEILL, A SWINBANK, R TI ON THE MOTION OF AIR THROUGH THE STRATOSPHERIC POLAR VORTEX SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ANTARCTIC OZONE HOLE; POTENTIAL VORTICITY; MIDDLE ATMOSPHERE; LATE WINTER; EVOLUTION; SOUTHERN; TRANSPORT; UARS; MLS AB Trajectory calculations using horizontal winds from the U.K. Meteorological Office data assimilation system and vertical velocities from a radiation calculation are used to simulate the three-dimensional motion of air through the stratospheric polar vortex for Northern Hemisphere (NH) and Southern Hemisphere (SH) winters since the launch of the Upper Atmosphere Research Satellite. Throughout the winter, air from the upper stratosphere moves poleward and descends into the middle stratosphere. In the SH lower to middle stratosphere, strongest descent occurs near the edge of the polar vortex, with that edge defined by mixing characteristics. The NH shows a similar pattern in late winter, but in early winter strongest descent is near the center of the vortex, except when wave activity is particularly strong. Strong barriers to latitudinal mixing exist above about 420 K throughout the winter. Below this, the polar night jet is weak in early winter, so air descending below that level mixes between polar and middle latitudes. In late winter, parcels descend less and the polar night jet moves downward, so there is less latitudinal mixing. The degree of mixing in the lower stratosphere thus depends strongly on the position and evolution of the polar night jet and on the amount of descent experienced by the air parcels; these characteristics show considerable interannual variability in both hemispheres. The computed trajectories provide a three-dimensional picture of air motion during the final warming. Large tongues of air are drawn off the vortex and stretched into increasingly long and narrow tongues extending into low latitudes. This vortex erosion process proceeds more rapidly in the NH than in the SH. In the lower stratosphere, the majority of air parcels remain confined within a lingering region of strong potential vorticity gradients into December in the SH and April in the NH, well after the vortex breaks up in the midstratosphere. C1 CTR GLOBAL ATMOSPHER MODELLING,READING,ENGLAND. METEOROL OFF,BRACKNELL RB12 2SZ,BERKS,ENGLAND. RP MANNEY, GL (reprint author), JET PROP LAB,MS 183-701,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 44 TC 184 Z9 186 U1 1 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 2973 EP 2994 DI 10.1175/1520-0469(1994)051<2973:OTMOAT>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700014 ER PT J AU MASSIE, ST BAILEY, PL GILLE, JC LEE, EC MERGENTHALER, JL ROCHE, AE KUMER, JB FISHBEIN, EF WATERS, JW LAHOZ, WA AF MASSIE, ST BAILEY, PL GILLE, JC LEE, EC MERGENTHALER, JL ROCHE, AE KUMER, JB FISHBEIN, EF WATERS, JW LAHOZ, WA TI SPECTRAL SIGNATURES OF POLAR STRATOSPHERIC CLOUDS AND SULFATE AEROSOL SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; NITRIC-ACID TRIHYDRATE; MICROWAVE LIMB SOUNDER; OPTICAL-CONSTANTS; SULFURIC-ACID; LIDAR OBSERVATIONS; PINATUBO AEROSOL; OZONE HOLE; SAM-II; ABSORPTION AB Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605 cm-1 (10.8, 8.0, and 6.2 mum) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheroidal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculations and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles. C1 PRINCETON UNIV,PRINCETON,NJ 08544. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. JET PROP LAB,PASADENA,CA 91109. UNIV READING,READING RG6 2AH,BERKS,ENGLAND. RP MASSIE, ST (reprint author), NATL CTR ATMOSPHER RES,POB 3000,BOULDER,CO 80307, USA. NR 47 TC 24 Z9 24 U1 0 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 15 PY 1994 VL 51 IS 20 BP 3027 EP 3044 DI 10.1175/1520-0469(1994)051<3027:SSOPSC>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700018 ER PT J AU RAY, EA HOLTON, JR FISHBEIN, EF FROIDEVAUX, L WATERS, JW AF RAY, EA HOLTON, JR FISHBEIN, EF FROIDEVAUX, L WATERS, JW TI THE TROPICAL SEMIANNUAL OSCILLATIONS IN TEMPERATURE AND OZONE AS OBSERVED BY THE MLS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID EQUATORIAL MIDDLE ATMOSPHERE; UPPER-STRATOSPHERE; KELVIN WAVE; ZONAL WIND; MODEL; CIRCULATION; VARIABILITY; MESOSPHERE AB The first two years of MLS temperature and ozone data are used to examine the tropical upper-stratospheric SAO. Time series analysis revealed that the strongest amplitudes of the SAO occurred near the equator at 2 mb for temperature and 5 mb for ozone, consistent with previous observations. The first cycle of each calendar year was observed to have a much higher amplitude than the second cycle except for the warm phase in late 1991. Interannual variability in the strength of the SAO, such as the much stronger warm phase of late 1991 as compared to late 1992, was significant and could be partly attributed to the QBO in zonal wind. C1 JET PROP LAB,PASADENA,CA 91109. RP RAY, EA (reprint author), UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195, USA. RI Ray, Eric/D-5941-2013 OI Ray, Eric/0000-0001-8727-9849 NR 28 TC 23 Z9 23 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 3045 EP 3052 DI 10.1175/1520-0469(1994)051<3045:TTSOIT>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700019 ER PT J AU CANZIANI, PO HOLTON, JR FISHBEIN, E FROIDEVAUX, L WATERS, JW AF CANZIANI, PO HOLTON, JR FISHBEIN, E FROIDEVAUX, L WATERS, JW TI EQUATORIAL KELVIN WAVES - A UARS MLS VIEW SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; SEMIANNUAL OSCILLATION; UPPER-STRATOSPHERE; LATITUDINAL SHEAR; MIDDLE ATMOSPHERE; OZONE; VARIABILITY AB Data from the Microwave Limb Sounder instrument on the Upper Atmosphere Research Satellite are used to compare two periods of Kelvin wave activity during different stages of the equatorial quasi-biennial oscillation. The analysis is carried out using an asynoptic mapping technique. A wide bandpass filter is used to isolate the frequency bands where Kelvin waves have been identified in previous studies. Time-height and time-latitude plots of the bandpassed data are used to identify Kelvin wave activity in the temperature and ozone fields. Frequency spectra of temperature and ozone amplitudes are constructed to further analyze the latitudinal and meridional distribution of Kelvin wave activity in zonal wavenumbers 1 and 2. The characteristics identified in these plots agree well with theoretical predictions and previous observations of middle atmosphere Kelvin waves. The time-height and time-latitude plots support the existence of Kelvin waves in discrete frequency bands; the slow, fast, and ultrafast Kelvin modes are all identified in the data. The characteristics of these modes do not vary much despite different mean flow conditions in the two periods examined. For the Kelvin wave-induced perturbations in ozone, the change from a transport-dominated regime below 10 hPa to a photochemically controlled regime above 10 hPa is clearly apparent in the height dependence of the phase difference between temperature and ozone. The ratios of the ozone perturbation amplitude to the temperature perturbation amplitude for the various observed Kelvin wave modes are in agreement with model estimates and LIMS (Limb Infrared Monitor of the Stratosphere) observations in the lower half of the region sampled but appear to be too large in the upper stratosphere and lower mesosphere. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP UNIV WASHINGTON, DEPT ATMOSPHER SCI AK40, SEATTLE, WA 98195 USA. NR 30 TC 52 Z9 52 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 EI 1520-0469 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 15 PY 1994 VL 51 IS 20 BP 3053 EP 3076 DI 10.1175/1520-0469(1994)051<3053:EKWAUM>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN067 UT WOS:A1994PN06700020 ER PT J AU BRANDUARDIRAYMONT, G MASON, KO WARWICK, RS CARRERA, FJ GRAFFAGNINO, VG MITTAZ, JPD PUCHNAREWICZ, EM SMITH, PJ BARBER, CR POUNDS, KA STEWART, GC MCHARDY, IM JONES, LR MERRIFIELD, MR FABIAN, AC MCMAHON, RG WARD, MJ GEORGE, IM JONES, MH LAWRENCE, A ROWANROBINSON, M AF BRANDUARDIRAYMONT, G MASON, KO WARWICK, RS CARRERA, FJ GRAFFAGNINO, VG MITTAZ, JPD PUCHNAREWICZ, EM SMITH, PJ BARBER, CR POUNDS, KA STEWART, GC MCHARDY, IM JONES, LR MERRIFIELD, MR FABIAN, AC MCMAHON, RG WARD, MJ GEORGE, IM JONES, MH LAWRENCE, A ROWANROBINSON, M TI THE UK DEEP AND MEDIUM SURVEYS WITH ROSAT - LOG-N-LOG-S RELATION SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE GALAXIES, ACTIVE; DIFFUSE RADIATION; X-RAYS, GENERAL ID MEDIUM-SENSITIVITY SURVEY; X-RAY SURVEY; LUMINOSITY FUNCTION; ORIGIN; EMISSION; DENSITY; COUNTS AB We have carried out a soft X-ray survey of the sky using the ROSAT Position Sensitive Proportional Counter (PSPC) in a region of very low Galactic column density (N-H = 6-9 x 10(19) cm(-2)). The data consist of a deep > 70 ks pointing (the Deep Survey) and six pointings at lower sensitivity (13-20 ks; the Medium Survey). We detect a total of 141 sources over the 0.9 deg(2) of sky area used. The faintest source detected has a flux of 3.2 x 10(-15) erg cm(-2) s(-1) (0.5-2.0 keV). We present the source number-nux distribution, and we compare it with the distributions constructed from other ROSAT observations and from surveys carried out with X-ray instruments operating at higher energies. We estimate the contribution of the resolved sources to the soft X-ray background by direct comparison of their integrated spectrum with that of the diffuse background: 44 per cent of the extragalactic X-ray background between 0.5 and 2.0 keV is resolved directly into discrete sources whose average spectrum is steeper than that of the background. Integration of our number-flux relation to infinite flux produces a background resolved fraction of 44 +/- (56)(5) per cent (0.5-2.0 keV). Limits on the slope of the log N-log S curve at very faint fluxes are set by the measured value of the X-ray background. C1 UNIV LEICESTER, DEPT PHYS, XRAY ASTRON GRP, LEICESTER LE1 7RH, LEICS, ENGLAND. UNIV SOUTHAMPTON, DEPT PHYS, SOUTHAMPTON SO9 5NH, HANTS, ENGLAND. ASTRON INST, CAMBRIDGE CB3 0HA, ENGLAND. UNIV OXFORD, DEPT ASTROPHYS, OXFORD OX1 3RQ, ENGLAND. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. OPEN UNIV, ACAD COMP SERV, MILTON KEYNES MK7 6AA, BUCKS, ENGLAND. UNIV LONDON QUEEN MARY & WESTFIELD COLL, DEPT PHYS, LONDON E1 4NS, ENGLAND. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, DEPT PHYS, LONDON SW7 2BZ, ENGLAND. RP BRANDUARDIRAYMONT, G (reprint author), UCL, MULLARD SPACE SCI LAB, HOLMBURY ST MARY, DORKING RH5 6NT, SURREY, ENGLAND. NR 32 TC 54 Z9 54 U1 0 U2 1 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 15 PY 1994 VL 270 IS 4 BP 947 EP 957 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN052 UT WOS:A1994PN05200024 ER PT J AU KATZ, N QUINN, T BERTSCHINGER, E GELB, JM AF KATZ, N QUINN, T BERTSCHINGER, E GELB, JM TI FORMATION OF QUASARS AT HIGH-REDSHIFT SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Letter DE GALAXIES, FORMATION; QUASARS, GENERAL ID COLD DARK MATTER; GALAXY FORMATION; UNIVERSE; EVOLUTION; MERGERS; PEAKS; GAS AB Analytic arguments have suggested that the existence of high-redshift quasars challenges hierarchical galaxy formation theories in which the majority of galaxies form late. We address this issue by using a series of numerical simulations of the biased cold dark matter model with and without gas dynamics. Potential quasar sites are identified with massive density peaks collapsing to form massive self-gravitating cold, gas clouds. The Press-Schechter formalism, using a Gaussian filter with delta(c) = 1.61, correctly predicts the number of high-mass dark haloes. Very efficient cooling and angular momentum transfer to the dark halo, however, allow the gas to become much denser than naive predictions would suggest. We find that there are > 10(3) times the required number of potential quasar sites at z = 4.5; at z = 8 there is already at least one site in our simulation volume of 10(6) Mpc(3). Thus sites for quasars could easily form at significantly higher redshifts than those of observed quasars, even in models where most galaxy formation occurs late. C1 MIT,DEPT PHYS,CAMBRIDGE,MA 02139. NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. NR 29 TC 39 Z9 39 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 1994 VL 270 IS 4 BP L71 EP & PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN052 UT WOS:A1994PN05200003 ER PT J AU MISHCHENKO, MI MACKOWSKI, DW AF MISHCHENKO, MI MACKOWSKI, DW TI LIGHT-SCATTERING BY RANDOMLY ORIENTED BISPHERES SO OPTICS LETTERS LA English DT Article ID AXIALLY-SYMMETRICAL PARTICLES; ELECTROMAGNETIC SCATTERING; POLARIZED-LIGHT AB We describe how the T-matrix approach can be used to compute analytically the Stokes scattering matrix for randomly oriented bispheres with touching or separated components. Computations for randomly oriented bispheres with touching components are compared with those for volume-equivalent randomly oriented prolate spheroids with an aspect ratio of 2 and for a single volume-equivalent sphere. We show that cooperative (multiple-scattering) effects can make bispheres more efficient depolarizers than spheroids in the backscattering direction. C1 AUBURN UNIV, DEPT MECH ENGN, AUBURN, AL 36849 USA. RP NASA, GODDARD INST SPACE STUDIES, HUGHES STX CORP, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mackowski, Daniel/K-1917-2013; Mishchenko, Michael/D-4426-2012 NR 15 TC 55 Z9 55 U1 0 U2 9 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 EI 1539-4794 J9 OPT LETT JI Opt. Lett. PD OCT 15 PY 1994 VL 19 IS 20 BP 1604 EP 1606 DI 10.1364/OL.19.001604 PG 3 WC Optics SC Optics GA PL585 UT WOS:A1994PL58500002 PM 19855595 ER PT J AU LAMBRECHT, WRL SEGALL, B YOGANATHAN, M SUTTROP, W DEVATY, RP CHOYKE, WJ AF LAMBRECHT, WRL SEGALL, B YOGANATHAN, M SUTTROP, W DEVATY, RP CHOYKE, WJ TI CALCULATED AND MEASURED UV REFLECTIVITY OF SIC POLYTYPES SO PHYSICAL REVIEW B LA English DT Article ID OPTICAL-PROPERTIES; SEMICONDUCTORS; POTENTIALS; CRYSTALS AB A systematic study of the vacuum uv-reflectivity (4-10 eV) for an electric field perpendicular to the c axis is presented for SiC polytypes. Experimental results for the 4H, 15R, 6R, and 3C SiC polytypes are compared to theoretical calculations within the local-density approximation in conjunction with a muffin-tin-orbital basis set for the 2H, 4H, 6H, and 3C polytypes. Agreement to similar to 0.2 eV is obtained between theorical and experimental peak positions assuming a single, k-point-, energy-, and polytype-independent gap correction, the value of which agrees well with recent calculations based on Hedin's GW approximation. The main features and their trends with degree of hexagonality of the polytype are interpreted in terms of interband transitions involving extended regions in the Brillouin zone where valence and conduction bands are nearly parallel. C1 UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. CREE RES INC, DURHAM, NC 27713 USA. NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. OHIO STATE UNIV, DEPT PHYS, COLUMBUS, OH 43210 USA. RP CASE WESTERN RESERVE UNIV, DEPT PHYS, CLEVELAND, OH 44106 USA. RI Lambrecht, Walter/O-1083-2016 NR 27 TC 69 Z9 71 U1 0 U2 6 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9950 EI 2469-9969 J9 PHYS REV B JI Phys. Rev. B PD OCT 15 PY 1994 VL 50 IS 15 BP 10722 EP 10726 DI 10.1103/PhysRevB.50.10722 PG 5 WC Physics, Condensed Matter SC Physics GA PP124 UT WOS:A1994PP12400034 ER PT J AU CARR, BJ GILBERT, JH LIDSEY, JE AF CARR, BJ GILBERT, JH LIDSEY, JE TI BLACK-HOLE RELICS AND INFLATION - LIMITS ON BLUE PERTURBATION SPECTRA SO PHYSICAL REVIEW D LA English DT Article ID RADIOMETER 1ST-YEAR MAPS; EXTENDED INFLATION; DENSITY PERTURBATIONS; GRAVITATIONAL-WAVES; GRAND UNIFICATION; GRACEFUL EXIT; UNIVERSE; COBE; COSMOLOGY; EVAPORATION AB Blue primordial power spectra have spectral index n > 1 and arise naturally in the recently proposed hybrid inflationary scenario. An observational upper Limit op n is derived by normalizing the spectrum at the quadrupole scale and considering the possible overproduction of Planck mass relies formed in the final stage of primordial black hole evaporation. In the inflationary Universe with the maximum reheating temperature compatible with the observed quadrupole anisotropy, the upper limit is n = 1.4, but it is slightly weaker for lower reheat temperatures. This limit applies over 57 decades of mass and is therefore insensitive to cosmic variance and any gravitational wave contribution to the quadrupole anisotropy. It is also independent of the dark matter content of the Universe and therefore the bias parameter. In some circumstances, there maybe an extended dustlike phase between the end of inflation and reheating. In this case, primordial black holes form more abundantly and the upper limit is n = 1.3. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP CARR, BJ (reprint author), UNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,ASTRON UNIT,MILE END RD,LONDON E1 4NS,ENGLAND. NR 95 TC 179 Z9 180 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 1994 VL 50 IS 8 BP 4853 EP 4867 DI 10.1103/PhysRevD.50.4853 PG 15 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PP250 UT WOS:A1994PP25000017 ER PT J AU SILVEIRA, V WAGA, I AF SILVEIRA, V WAGA, I TI DECAYING LAMBDA-COSMOLOGIES AND POWER SPECTRUM SO PHYSICAL REVIEW D LA English DT Article ID LARGE-SCALE STRUCTURE; COLD DARK MATTER; CONSTANT; MODELS; UNIVERSE; EVOLUTION; INFLATION; DENSITY; LAW AB We investigate the evolution of matter density perturbations in a universe with a cosmological term that decreases with time as Lambda alpha a(-m). For fixed values of Omega(m0) the power spectrum is constructed and we show that it is only slightly modified when the parameter m is changed from m = 0 to m = 2. Some properties concerning the peculiar velocity held are also discussed. C1 FERMILAB NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV FED RIO DE JANEIRO,INST FIS,BR-21943 RIO JANEIRO,BRAZIL. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP SILVEIRA, V (reprint author), UNIV BRASILIA,DEPT FIS,BR-70910900 BRASILIA,DF,BRAZIL. RI Waga, Ioav/B-6288-2014 NR 27 TC 152 Z9 153 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1994 VL 50 IS 8 BP 4890 EP 4894 DI 10.1103/PhysRevD.50.4890 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PP250 UT WOS:A1994PP25000021 ER PT J AU FRIEMAN, JA HARARI, DD SURPI, GC AF FRIEMAN, JA HARARI, DD SURPI, GC TI GRAVITATIONAL LENS TIME DELAYS AND GRAVITATIONAL-WAVES SO PHYSICAL REVIEW D LA English DT Article ID FERMAT PRINCIPLE AB Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens with a different alignment between source, deflector, and observer in the absence of gravity waves. Contrary to a recent claim, we conclude that measurements of time delays in gravitational lenses cannot serve as a method to detect or constrain a stochastic background of gravitational waves of cosmological wavelengths, because the wave-induced time delay is observationally indistinguishable from an intrinsic time delay due to the lens geometry. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV BUENOS AIRES,FAC CIENCIAS EXACTAS & NAT,DEPT FIS,RA-1428 BUENOS AIRES,DF,ARGENTINA. RP FRIEMAN, JA (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,POB 500,BATAVIA,IL 60510, USA. NR 20 TC 14 Z9 14 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 1994 VL 50 IS 8 BP 4895 EP 4902 DI 10.1103/PhysRevD.50.4895 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PP250 UT WOS:A1994PP25000022 ER PT J AU LEE, TJ BAUSCHLICHER, CW DATEO, CE RICE, JE AF LEE, TJ BAUSCHLICHER, CW DATEO, CE RICE, JE TI THE MOLECULAR-STRUCTURE OF CIS-FONO SO CHEMICAL PHYSICS LETTERS LA English DT Article ID NITROSYL HYPOFLUORITE; BASIS SETS; DENSITY; FOOF; EXCHANGE; ATOMS AB The molecular structure of cis-FONO has been determined with the CCSD(T) correlation method using an spdf quality basis set. In agreement with previous coupled-cluster calculations cis-FONO exhibits normal bond distances. The cubic force field of cis-FONO has been determined in order to evaluate the effect of vibrational averaging on the geometry. Vibrational averaging is found to increase bond distances, as expected, but it does not affect the qualitative description of the bonding. The CCSD(T)/spdf harmonic frequencies of cis-FONO support our previous assertion that a band observed at 1200 cm(-1) is a combination band (upsilon(3)+upsilon(4)), and not a fundamental. In contrast to earlier density functional theory (DFT) studies, calculations using an empirically optimized hybrid functional give a structure and vibrational frequencies for cis-FONO that are in qualitative agreement with the CCSD(T) values, resolving the discrepancy between DFT and CCSD(T). C1 IBM CORP, ALMADEN RES CTR, DIV RES, SAN JOSE, CA 95120 USA. RP LEE, TJ (reprint author), NASA, AMES RES CTR, INST THERMOSCI, MOFFETT FIELD, CA 94035 USA. RI Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Rice, Julia/0000-0001-5059-5127; NR 21 TC 22 Z9 22 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 OCT 14 PY 1994 VL 228 IS 6 BP 583 EP 588 DI 10.1016/0009-2614(94)00988-0 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PL261 UT WOS:A1994PL26100013 ER PT J AU ARRIGO, KR MCCLAIN, CR AF ARRIGO, KR MCCLAIN, CR TI SPRING PHYTOPLANKTON PRODUCTION IN THE WESTERN ROSS SEA SO SCIENCE LA English DT Article ID MARGINAL ICE-ZONE; MCMURDO SOUND; ANTARCTICA; OCEAN; COMMUNITIES; PATTERNS; BIGHT AB Coastal zone color scanner (CZCS) imagery of the western Ross Sea revealed the presence of an intense phytoplankton bloom covering >106,000 square kilometers in early December 1978. This bloom developed inside the Ross Sea polynya, within 2 weeks of initial polynya formation in late November. Primary productivity calculated from December imagery (3.9 grams of carbon per square meter per day) was up to four times the values measured during in situ studies in mid-January to February 1979. Inclusion of this early season production yields a spring-to-summer estimate of 141 to 171 grams of carbon per square meter, three to four times the values previously reported for the western Ross Sea. RP ARRIGO, KR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 20 TC 103 Z9 106 U1 0 U2 10 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD OCT 14 PY 1994 VL 266 IS 5183 BP 261 EP 263 DI 10.1126/science.266.5183.261 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PM134 UT WOS:A1994PM13400029 PM 17771447 ER PT J AU GREEN, S AF GREEN, S TI COLLISIONAL EXCITATION OF INTERSTELLAR SULFUR MONOXIDE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; MOLECULAR PROCESSES ID CROSS-SECTIONS; SCATTERING; MOLECULES; QUANTUM AB Excitation rates among fine structure levels of sulfur monoxide in collisions with hydrogen molecules are estimated using methods expected to provide adequate accuracy for modeling millimeter and submillimeter observations of this species in relatively warm (100-300 K) molecular clouds. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 17 TC 34 Z9 34 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 1994 VL 434 IS 1 BP 188 EP 191 DI 10.1086/174715 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK764 UT WOS:A1994PK76400017 ER PT J AU DGANI, R SOKER, N AF DGANI, R SOKER, N TI RADIATIVE SHOCK OVERSTABILITY OF FINITE-SIZED OBJECTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; INSTABILITIES; PLANETARY NEBULAE, GENERAL; SHOCK WAVES ID INTERSTELLAR-MEDIUM; PLANETARY-NEBULAE; STABILITY; INSTABILITY; ACCRETION; WAVES; STARS AB we investigate the radiative shock overstability for finite-sized objects. We follow the analysis of Chevalier and Imamura (1982), but we take into account the transverse flow of material out of the postshock region. The mass loss from the postshock region stabilizes the how. As a rough estimate, the shock radiative instability takes place when the shock wave position with no radiative cooling (only mass loss present) is larger than the shock position with no mass loss (only radiative cooling present). For typical conditions of planetary nebulae we find that in order for the shock radiative overstability to occur, the nebular radius should be R less than or similar to 10(19)n(a)(-1) cm, where n(a) is the total number density of the interstellar medium (in units of cm(-3)). We give several examples of interacting planetary nebulae in light of this condition. C1 ORANIM UNIV DIV,IL-36910 TIVON,ISRAEL. RP DGANI, R (reprint author), CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,CALTECH 100-22,PASADENA,CA 91125, USA. NR 16 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1994 VL 434 IS 1 BP 262 EP 267 DI 10.1086/174723 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK764 UT WOS:A1994PK76400025 ER PT J AU WAHLGREN, GM ADELMAN, SJ ROBINSON, RD AF WAHLGREN, GM ADELMAN, SJ ROBINSON, RD TI AN OPTICAL-REGION ELEMENTAL ABUNDANCE ANALYSIS OF THE CHEMICALLY PECULIAR HGMN STAR-(CHI)-LUPI SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ABUNDANCES; STARS, INDIVIDUAL ((CHI) LUPI); STARS, PECULIAR ID ATOMIC TRANSITION-PROBABILITIES; CRITICAL DATA COMPILATION; OSCILLATOR-STRENGTHS; SOLAR ABUNDANCE; B-STARS; A-STARS; ALLOWED LINES; SI-II; SPECTRA; IRON AB The optical spectrum of the chemically peculiar HgMn type binary star X Lupi has been analyzed to determine atmospheric parameters and elemental abundances. Echelle spectra were obtained with the 3.9 m Anglo-Australian telescope to exploit the extreme shape-lined nature of the spectrum. This study was undertaken in support of ultraviolet analyses currently underway that utilize echelle spectra obtained with the Hubble Space Telescope. For the B9.5 V primary star we obtain T-eff = 10650 K, log g = 3.9, and xi = 0 km s(-1), while for the A2 V secondary, T-eff = 9200 K, log g = 4.0, and xi = 2 km s(-1). Most of the elemental abundances are typical of HgMn stars with similar T-eff, showing an overall iron-peak elemental abundance distribution that is basically solar in nature with enhancement of the light elements Si P, and S, as well as all detected elements heavier than the iron group. Abundances for several elements have been determined for the first time in this star, including several of the rare-earths. The secondary star spectrum shows Am star characteristics. We also discuss the relative merits of the equivalent width and synthetic spectrum techniques in determining the elemental abundances, concluding that the synthetic spectrum technique is necessary for obtaining abundances with the utmost accuracy. C1 NASA,GODDARD SPACE FLIGHT CTR,GHRS SCI TEAM,GREENBELT,MD 20771. DEPT PHYS,CHARLESTON,SC 29409. RP WAHLGREN, GM (reprint author), COMP SCI CORP,ASTRON PROGRAM,CODE 681,GREENBELT,MD 20771, USA. NR 61 TC 42 Z9 42 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1994 VL 434 IS 1 BP 349 EP 362 DI 10.1086/174733 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK764 UT WOS:A1994PK76400035 ER PT J AU GEBALLE, TR JOBLIN, C DHENDECOURT, LB DEMUIZON, MJ TIELENS, AGGM LEGER, A AF GEBALLE, TR JOBLIN, C DHENDECOURT, LB DEMUIZON, MJ TIELENS, AGGM LEGER, A TI DETECTION OF THE OVERTONE OF THE 3.3-MICRON EMISSION FEATURE IN IRAS-21282+5050 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, ISM, LINES AND BANDS; ISM, MOLECULES; PLANETARY NEBULAE, INDIVIDUAL (IRAS 21282 + 5050) ID CARBONACEOUS COMPOSITE QCC; INFRARED-SPECTRUM; BANDS; SPECTROSCOPY; IDENTIFICATION; CARRIERS; MODELS; DUST AB The 1.6-1.8 mu m spectrum of the planetary nebula, IRAS 21282+5050, a strong emitter of the unidentified interstellar bands, contains a 0.02 mu m wide emission feature centered at 1.680 mu m, which is well matched by laboratory spectra of the 0-2 CH stretching mode in polycyclic aromatic hydrocarbons. We identify the new feature as the overtone of the well-known 3.3 mu m band. In view of the high excitation required for emission in this band, the identification indicates that the emission is by free molecules rather than molecular moieties in solid dust grains. Modeling of the intensity ratio of the 2-0 to 1-0 band implies that the PAHs emitting in these bands contain about 60 carbon atoms. It is inferred that the upsilon = 2-1 hot band of the CH stretching mode occurs at about 3.43 mu m and contributes to the long-wavelength shoulder of the 3.40 mu m feature. The main 3.40 mu m feature probably is due to aliphatic sidegroups on PAH molecules. C1 NASA,AMES RES CTR,MT VIEW,CA 94035. UNIV PARIS 11,INST ASTROPHYS SPATIALE,F-91405 ORSAY,FRANCE. OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. STERREWACHT LEIDEN,2300 RA LEIDEN,NETHERLANDS. RP GEBALLE, TR (reprint author), JOINT ASTRON CTR,660 N AOHOKU PL,HILO,HI 96720, USA. NR 27 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 1994 VL 434 IS 1 BP L15 EP L18 DI 10.1086/187561 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK765 UT WOS:A1994PK76500004 ER PT J AU MACLOW, MM ZAHNLE, K AF MACLOW, MM ZAHNLE, K TI EXPLOSION OF COMET SHOEMAKER-LEVY-9 ON ENTRY INTO THE JOVIAN ATMOSPHERE SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS, INDIVIDUAL (SHOEMAKER-LEVY 9); PLANETS AND SATELLITES, INDIVIDUAL (JUPITER) AB We use the astrophysical hydrocode ZEUS to compute high-resolution models of the disruption and deceleration of cometary fragments striking Jupiter. We find that simple analytic and semianalytic models work well for kilometer-size impactors. We show that previous numerical models that placed the explosion much deeper in the atmosphere failed to fully resolve important gasdynamical instabilities. These instabilities tear the comet apart, greatly increase its effective cross section, and bring it to an abrupt halt. A 1 km diameter fragment loses over 90% of its kinetic energy within a single scale height at an atmospheric pressure of order 10 bars. For all practical purposes, it explodes. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801. RP MACLOW, MM (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 24 TC 66 Z9 66 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 1994 VL 434 IS 1 BP L33 EP & DI 10.1086/187565 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK765 UT WOS:A1994PK76500008 PM 11539567 ER PT J AU ZEBKER, HA ROSEN, PA GOLDSTEIN, RM GABRIEL, A WERNER, CL AF ZEBKER, HA ROSEN, PA GOLDSTEIN, RM GABRIEL, A WERNER, CL TI ON THE DERIVATION OF COSEISMIC DISPLACEMENT-FIELDS USING DIFFERENTIAL RADAR INTERFEROMETRY - THE LANDERS EARTHQUAKE SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SYNTHETIC APERTURE RADAR; CURRENTS; MODEL AB We present a map of the coseismic displacement field resulting from the Landers, California, June 28, 1992, earthquake derived using data acquired from an orbiting high-resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS 1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high-resolution, wide area map of the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m resolution element in a 113 km by 90 km image. Our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of these data with Global Positioning System and electronic distance measurement survey data yield a correlation of 0.96; thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous similar applications of differential radar interferometry. Since we require only remotely sensed satellite data with no additional requirements for ancillary information, the technique is well suited for global seismic monitoring and analysis. RP ZEBKER, HA (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MS 300-227, PASADENA, CA 91109 USA. NR 19 TC 310 Z9 355 U1 4 U2 31 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 1994 VL 99 IS B10 BP 19617 EP 19634 DI 10.1029/94JB01179 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PL027 UT WOS:A1994PL02700001 ER PT J AU ORTIZ, R MARDER, SR CHENG, LT TIEMANN, BG CAVAGNERO, S ZILLER, JW AF ORTIZ, R MARDER, SR CHENG, LT TIEMANN, BG CAVAGNERO, S ZILLER, JW TI THE DEPENDENCE OF THE MOLECULAR FIRST HYPERPOLARIZABILITIES OF MEROCYANINES ON GROUND-STATE POLARIZATION AND LENGTH SO JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS LA English DT Article ID NONLINEAR OPTICAL POLARIZABILITIES AB We report here the dipole moment (mu) and first hyperpolarizability (beta) determined by electric field-induced second harmonic generation, for several merocyanine dyes containing an 1,3,3-trimethylindoline heterocycle as a 'donor' in which the 'acceptor' end of the molecule and the polyene bridge length was systematically varied; dyes with hexamethine bridges gave positive beta, while that with a dimethine bridge gave a negative beta value. C1 CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. DUPONT CO INC,EXPTL STN,WILMINGTON,DE 19880. CALTECH,ARTHUR AMOS NOYES LAB CHEM PHYS,PASADENA,CA 91125. UNIV CALIF IRVINE,DEPT CHEM,IRVINE,CA 92717. NR 12 TC 23 Z9 23 U1 0 U2 1 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0022-4936 J9 J CHEM SOC CHEM COMM JI J. Chem. Soc.-Chem. Commun. PD OCT 7 PY 1994 IS 19 BP 2263 EP 2264 DI 10.1039/c39940002263 PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA PK777 UT WOS:A1994PK77700032 ER PT J AU MONKS, PS STIEF, LJ KRAUSS, M KUO, SC ZHANG, Z KLEMM, RB AF MONKS, PS STIEF, LJ KRAUSS, M KUO, SC ZHANG, Z KLEMM, RB TI A DISCHARGE FLOW-PHOTOIONIZATION MASS-SPECTROMETRIC STUDY OF THE NO3((2)A(2)') RADICAL - PHOTOIONIZATION SPECTRUM, ADIABATIC IONIZATION-ENERGY, AND GROUND-STATE SYMMETRY SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID NO3; SPECTROSCOPY; NITRATE; ION AB The photoion efficiency spectrum of the nitrate radical (NO3) was measured over the region lambda = 90-104 nm by using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. NO3 was generated by the reaction of fluorine atoms with nitric acid. A value of 12.57 +/- 0.03 eV was obtained for the adiabatic ionization energy (IE) of NO3 from photoion thresholds, corresponding to the NO3+((1)A(1)') <-- NO3((2)A(2)') transition. These direct ionization measurements are the first to be reported for the NO3 radical. Relative energetics and optimized geometries for ground state NO3 and several states of NO3+ were determined in both D-3h and C-2V symmetries using multiconfiguration self-consistent-field calculations. The results of the present study strongly suggest that the neutral ground state of NO3 has D-3h symmetry. This conclusion is based on the following observations: (1) the experimental photoion threshold exhibits a large, steep initial step with no evidence of significant structure, indicating that the neutral and cation must share the same symmetry, and (2) the theoretical evidence is unambiguous that the cation symmetry is D-3h A value of Delta(f)H(298)degrees(NO3+) and the proton affinity of NO3 are also derived. A brief comparison is made of the ionization energies of NO, NO2, and NO3, and some new results on the dissociative ionization of HNO3 are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. CTR ADV RES BIOTECHNOL,ROCKVILLE,MD 20850. BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. RI Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 31 TC 24 Z9 25 U1 1 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD OCT 6 PY 1994 VL 98 IS 40 BP 10017 EP 10022 DI 10.1021/j100091a013 PG 6 WC Chemistry, Physical SC Chemistry GA PK740 UT WOS:A1994PK74000013 ER PT J AU GORNITZ, V ROSENZWEIG, C HILLEL, D AF GORNITZ, V ROSENZWEIG, C HILLEL, D TI IS SEA-LEVEL RISING OR FALLING SO NATURE LA English DT Letter ID TROPICAL DEFORESTATION C1 UNIV MASSACHUSETTS,DEPT PLANT SOIL & ENVIRONM SCI,AMHERST,MA 01003. RP GORNITZ, V (reprint author), COLUMBIA UNIV,INST SPACE STUDIES,GODDARD SPACE FLIGHT CTR,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 11 TC 9 Z9 10 U1 1 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 6 PY 1994 VL 371 IS 6497 BP 481 EP 481 DI 10.1038/371481a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PK589 UT WOS:A1994PK58900035 ER PT J AU OECHEL, WC COWLES, S GRULKE, N HASTINGS, SJ LAWRENCE, B PRUDHOMME, T RIECHERS, G STRAIN, B TISSUE, D VOURLITIS, G AF OECHEL, WC COWLES, S GRULKE, N HASTINGS, SJ LAWRENCE, B PRUDHOMME, T RIECHERS, G STRAIN, B TISSUE, D VOURLITIS, G TI TRANSIENT NATURE OF CO2 FERTILIZATION IN ARCTIC TUNDRA SO NATURE LA English DT Article ID ATMOSPHERIC CARBON-DIOXIDE; TRANSGENIC TOBACCO PLANTS; ELEVATED CO2; TUSSOCK TUNDRA; CLIMATE CHANGE; PHOTOSYNTHETIC ACCLIMATION; UNMANAGED ECOSYSTEMS; BIOMASS PRODUCTION; MINERAL-NUTRITION; SOIL-TEMPERATURE AB THERE has been much debate about the effect of increased atmospheric CO2 concentrations on plant net primary production(1,3) and on net ecosystem CO2 flux(3-10). Apparently conflicting experimental findings could be the result of differences in genetic potential(11-15) and resource availability(16-20), different experimental conditions(21-24) and the fact that many studies have focused on individual components of the system(2,21,25-27) rather than the whole ecosystem. Here we present results of an in situ experiment on the response of an intact native ecosystem to elevated CO2. An undisturbed patch of tussock tundra at Toolik Lake, Alaska, was enclosed in greenhouses in which the CO2 level, moisture and temperature could be controlled(28), and was subjected to ambient (340 p.p.m.) and elevated (680 p.p.m.) levels of CO2 and temperature (+4 degrees C). Air humidity, precipitation and soil water table were maintained at ambient control levels. For a doubled CO2 level alone, complete homeostasis of the CO2 flux was re-established within three Sears, whereas the regions exposed to a combination of higher temperatures and doubled CO2 showed persistent fertilization effect on net ecosystem carbon sequestration over this time. This difference may be due to enhanced sink activity from the direct effects of higher temperatures on growth(16,29-33) and to indirect effects from enhanced nutrient supply caused by increased mineralization(10,11,19,27,34). These results indicate that the responses of native ecosystems to elevated CO2 may not always be positive, and are unlikely to be straightforward. Clearly, CO2 fertilization effects must always be considered in the context of genetic limitation, resource availability and other such factors. C1 SAN DIEGO STATE UNIV,SYST ECOL RES GRP,SAN DIEGO,CA 92182. STANFORD UNIV,STANFORD HUMAN GENOME CTR,DEPT GENET,STANFORD,CA 94305. US FOREST SERV,PACIFIC NW RES STN,FORESTRY SCI LAB,CORVALLIS,OR 97331. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. OMEGA MED SYST INC,RALEIGH,NC 27619. UNIV CALIF RIVERSIDE,STATEWIDE AIR POLLUT RES CTR,RIVERSIDE,CA 92521. DUKE UNIV,DEPT BOT,DURHAM,NC 27706. RP OECHEL, WC (reprint author), SAN DIEGO STATE UNIV,GLOBAL CHANGE RES GRP,SAN DIEGO,CA 92182, USA. RI Oechel, Walter/F-9361-2010; Tissue, David/H-6596-2015 OI Oechel, Walter/0000-0002-3504-026X; Tissue, David/0000-0002-8497-2047 NR 79 TC 169 Z9 178 U1 3 U2 46 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD OCT 6 PY 1994 VL 371 IS 6497 BP 500 EP 503 DI 10.1038/371500a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PK589 UT WOS:A1994PK58900050 ER PT J AU DESCH, MD BLEYER, WA AF DESCH, MD BLEYER, WA TI AMENDED LONG-TERM TRENDS IN CANCER INCIDENCE RATES IN CHILDREN SO JOURNAL OF THE NATIONAL CANCER INSTITUTE LA English DT Letter C1 UNIV TEXAS,MD ANDERSON CANC CTR,HOUSTON,TX. RP DESCH, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU NATL CANCER INSTITUTE PI BETHESDA PA 9030 OLD GEORGETOWN RD, BETHESDA, MD 20814 SN 0027-8874 J9 J NATL CANCER I JI J. Natl. Cancer Inst. PD OCT 5 PY 1994 VL 86 IS 19 BP 1481 EP 1481 DI 10.1093/jnci/86.19.1481 PG 1 WC Oncology SC Oncology GA PJ101 UT WOS:A1994PJ10100014 PM 8089869 ER PT J AU BENNETT, GL PILCHER, CB SMITH, WL STETSON, DS AF BENNETT, GL PILCHER, CB SMITH, WL STETSON, DS TI AN OVERVIEW OF NASA PROJECTED MISSION REQUIREMENTS FOR SPACE NUCLEAR SYSTEMS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 44th International-Astronautical-Federation Congress: Challenges of Space for a Better World CY OCT 16-22, 1993 CL AUSTRIAN SPACE AGCY, GRAZ, AUSTRIA SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW HO AUSTRIAN SPACE AGCY AB NASA has completed a series of top-down reviews of its missions and space technology programs with a strong focus on missions which can be done faster, at less cost and with better performance. In addition, NASA has created a new office, the Office of Advanced Concepts and Technology, with a strong customer focus on technology. As a result of these reviews a number of exciting options are being considered for space nuclear systems. Of course, the near-term ongoing NASA space nuclear program is the Cassini mission to Saturn which will use three radioisotope thermoelectric generators (RTGs). Beyond that NASA is studying a Pluto Fast Flyby mission which will challenge the space power community to produce a low-mass RTG. Another candidate RTG mission is the Mars Environmental Survey (MESUR) mission to emplace a number of probes on the surface of Mars to obtain a more global survey of the planet than was accomplished with the two Viking Landers. Looking toward the 21st century there are a number of exciting planetary missions, such as the Jupiter Grand Tour, Outer Planet Orbiters/Probes, comet/asteroid rendezvous/sample return, which are enabled or greatly enhanced by nuclear reactor power coupled with electric propulsion. RP BENNETT, GL (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 2 Z9 2 U1 1 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 1994 VL 34 BP 1 EP 16 DI 10.1016/0094-5765(94)90237-2 PG 16 WC Engineering, Aerospace SC Engineering GA PN203 UT WOS:A1994PN20300002 ER PT J AU SADIN, SR DAVIS, RW AF SADIN, SR DAVIS, RW TI THE SMALLSAT REVOLUTION .... BACK TO THE FUTURE SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 44th International-Astronautical-Federation Congress: Challenges of Space for a Better World CY OCT 16-22, 1993 CL AUSTRIAN SPACE AGCY, GRAZ, AUSTRIA SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW HO AUSTRIAN SPACE AGCY AB In engineering, as in the sciences, mathematics and the arts, evolutionary processes ultimately lead to the sophistication of simplicity. The smallsat revolution is producing a return to sensible scales of size, mass, and cost. Space missions evolved from modest flight research to complex, space-based laboratory and operational systems. Continuing growth in vehicle size yielded excessive system complexity, extended design and development cycles, and unrealistic unit flight cost and risk. Technology combined with a collateral user market pull spawned smallsats for simple, short lifetime scientific experiments and technology demonstrations. A small launch vehicle industry emerged to serve a new generation of highly capable smallsats, and networked systems of smallsats. Small satellites can now support long-life, complex operational missions such as commercial communications, earth observations, and military surveillance. Future advances in satellite technologies augur systems built with micro- and nano-scale devices, other breakthroughs, and ''spin-in'' from non-space, commercial fields. A potential new genre of spacecraft with modular plug-in elements could be employed in standardized model runs. End-to-end design, build and launch schedules will be substantially compressed. Clustered/distributed systems on orbit will be maintained and/or upgraded by replacing relatively inexpensive smallsats. RP SADIN, SR (reprint author), NASA HQ,WASHINGTON,DC, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1994 VL 34 BP 109 EP 122 DI 10.1016/0094-5765(94)90249-6 PG 14 WC Engineering, Aerospace SC Engineering GA PN203 UT WOS:A1994PN20300014 ER PT J AU CRAFT, HG MARMANN, RA AF CRAFT, HG MARMANN, RA TI SPACELAB PROGRAMS SCIENTIFIC BENEFITS TO MANKIND SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 44th International-Astronautical-Federation Congress: Challenges of Space for a Better World CY OCT 16-22, 1993 CL AUSTRIAN SPACE AGCY, GRAZ, AUSTRIA SP INT ASTRONAUT FEDERAT, INT ACAD ASTRONAUT, INT INST SPACE LAW HO AUSTRIAN SPACE AGCY AB This paper describes the Spacelab program's scientific accomplishments during the past 10 years, highlighting major scientific accomplishments. An overview of Spacelab systems performance, significant issues, and utilization and operations activities applicable to the space station era is presented. RP CRAFT, HG (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,PAYLOAD PROJECTS OFF,HUNTSVILLE,AL 35812, 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 1994 VL 34 BP 297 EP 305 DI 10.1016/0094-5765(94)90267-4 PG 9 WC Engineering, Aerospace SC Engineering GA PN203 UT WOS:A1994PN20300032 PM 11540745 ER PT J AU VARSI, G CHRISP, M JONES, R VANZANDT, T KENNY, T KAISER, W BANERDT, W HUI, E CRISP, D AF VARSI, G CHRISP, M JONES, R VANZANDT, T KENNY, T KAISER, W BANERDT, W HUI, E CRISP, D TI MICROINSTRUMENTS AND MICROSENSORS FOR SPACE SCIENCE SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 43rd Astronautical Congress CY AUG 28-SEP 05, 1992 CL WASHINGTON, DC AB Advances in micromachining technology in many defense and civilian programs make it feasible to design miniature sensors and instruments of the order of 10(2)-10(3) and 10(3)-10(4) g, respectively. By applying new signal detection principles, we have designed microspectrometers, microseismometers, microsamplers and other devices, which are now in varying phases of development and testing. Microspacecraft of the order of 10 kg, employing miniature sensors and instruments, are uniquely suited for three types of space science missions: missions that require multiple simultaneous measurements in different locations, missions that require very high launch energy and high risk missions where risk may be reduced by replacing a single large and expensive spacecraft with numerous independent small crafts. Applications examined include seismological and meteorological measurements on planetary surfaces and atmospheres and investigation of the mesoscale plasma structure around the Earth. RP VARSI, G (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD OCT PY 1994 VL 32 IS 10 BP 705 EP 713 DI 10.1016/0094-5765(94)90181-3 PG 9 WC Engineering, Aerospace SC Engineering GA QE694 UT WOS:A1994QE69400009 ER PT J AU CASPER, J SHU, CW ATKINS, H AF CASPER, J SHU, CW ATKINS, H TI COMPARISON OF 2 FORMULATIONS FOR HIGH-ORDER ACCURATE ESSENTIALLY NONOSCILLATORY SCHEMES SO AIAA JOURNAL LA English DT Article ID SHOCK-CAPTURING SCHEMES; EFFICIENT IMPLEMENTATION; SYSTEMS AB The finite volume and finite difference implementations of high-order accurate essentially nonoscillatory shock-capturing schemes are discussed and compared. Results obtained with fourth-order accurate algorithms based on both formulations are examined for accuracy, sensitivity to grid irregularities, resolution of waves that are oblique to the mesh, and computational efficiency. Some algorithm modifications that may be required for a given application are suggested. Conclusions that pertain to the relative merits of both formulations are drawn, and some circumstances for which each might be useful are noted. C1 BROWN UNIV,DIV APPL MATH,PROVIDENCE,RI 02912. NASA,LANGLEY RES CTR,DIV FLUID MECH,COMPUTAT AERODYNAM BRANCH,HAMPTON,VA 23681. RP CASPER, J (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. RI Shu, Chi-Wang/A-3216-2013 OI Shu, Chi-Wang/0000-0001-7720-9564 NR 13 TC 26 Z9 29 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 1994 VL 32 IS 10 BP 1970 EP 1977 DI 10.2514/3.12240 PG 8 WC Engineering, Aerospace SC Engineering GA PJ487 UT WOS:A1994PJ48700004 ER PT J AU VENKATAKRISHNAN, V AF VENKATAKRISHNAN, V TI PARALLELIMPLICIT UNSTRUCTURED GRID EULER SOLVERS SO AIAA JOURNAL LA English DT Article ID EQUATIONS; MESHES AB A mesh-vertex finite volume scheme for solving the Euler equations on triangular unstructured meshes is implemented on a multiple-instruction/multiple-data stream parallel computer. An explicit four-stage Runge-Kutta scheme is used to solve two-dimensional flow problems. A family of implicit schemes is also developed to solve these problems, where the linear system that arises at each time step is solved by a preconditioned GMRES algorithm. Two partitioning strategies are employed: one that partitions triangles and the other that partitions vertices. The choice of the preconditioner in a distributed memory setting is discussed. All of the methods are compared both in terms of elapsed times and convergence rates. It is shown that the implicit schemes offer adequate parallelism at the expense of minimal sequential overhead. The use of a global coarse grid to further minimize this overhead is also investigated. The schemes are implemented on a distributed memory parallel computer, the Intel iPSC/860. RP VENKATAKRISHNAN, V (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,MS 132C,HAMPTON,VA 23681, USA. NR 24 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1994 VL 32 IS 10 BP 1985 EP 1991 DI 10.2514/3.12242 PG 7 WC Engineering, Aerospace SC Engineering GA PJ487 UT WOS:A1994PJ48700006 ER PT J AU HUANG, PG COLEMAN, GN AF HUANG, PG COLEMAN, GN TI VANDRIEST TRANSFORMATION AND COMPRESSIBLE WALL-BOUNDED FLOWS SO AIAA JOURNAL LA English DT Note ID TURBULENT; LAYERS C1 ELORET INST,PALO ALTO,CA 94303. RP HUANG, PG (reprint author), NASA,AMES RES CTR,MS 2291,MOFFETT FIELD,CA 94035, USA. NR 15 TC 22 Z9 22 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1994 VL 32 IS 10 BP 2110 EP 2113 DI 10.2514/3.12259 PG 4 WC Engineering, Aerospace SC Engineering GA PJ487 UT WOS:A1994PJ48700023 ER PT J AU SPEZIALE, CG GATSKI, TB AF SPEZIALE, CG GATSKI, TB TI ASSESSMENT OF 2ND-ORDER CLOSURE MODELS IN TURBULENT SHEAR FLOWS SO AIAA JOURNAL LA English DT Note ID PRESSURE STRAIN CORRELATION; SIMULATIONS C1 NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665. NR 16 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 1994 VL 32 IS 10 BP 2113 EP 2115 DI 10.2514/3.12260 PG 3 WC Engineering, Aerospace SC Engineering GA PJ487 UT WOS:A1994PJ48700024 ER PT J AU BASHOUR, TT MANSOUR, NN AF BASHOUR, TT MANSOUR, NN TI LOOPY CORONARY-ARTERIES REVEAL THEIR SECRETS SO AMERICAN HEART JOURNAL LA English DT Editorial Material ID MYOCARDIAL-ISCHEMIA C1 SETON HOSP,SAN FRANCISCO HEART HLTH INST,DALY CITY,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BASHOUR, TT (reprint author), ST MARYS HOSP,WESTERN HEART INST,GOLDEN GATE PK,450 STANYAN ST,SAN FRANCISCO,CA 94117, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU MOSBY-YEAR BOOK INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 SN 0002-8703 J9 AM HEART J JI Am. Heart J. PD OCT PY 1994 VL 128 IS 4 BP 846 EP 850 DI 10.1016/0002-8703(94)90291-7 PG 5 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA PJ929 UT WOS:A1994PJ92900033 PM 7942463 ER PT J AU OREMLAND, RS MILLER, LG CULBERTSON, CW CONNELL, TL JAHNKE, L AF OREMLAND, RS MILLER, LG CULBERTSON, CW CONNELL, TL JAHNKE, L TI DEGRADATION OF METHYL-BROMIDE BY METHANOTROPHIC BACTERIA IN CELL-SUSPENSIONS AND SOILS SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID METHANE MONO-OXYGENASE; OZONE DEPLETION; DIMETHYL ETHER; OXIDATION; METABOLISM; SEDIMENTS; ACETYLENE; SEAWATER; FLUORIDE; HALIDES AB Cell suspensions of Methylococcus capsulatus mineralized methyl bromide (MeBr), as evidenced by its removal from the gas phase, the quantitative recovery bf Br- in the spent medium, and the production of (CO2)-C-14, from [C-14]MeBr. Methyl fluoride (MeF) inhibited oxidation of methane as well as that of [C-14]MeBr. The rate of MeBr consumption by cells varied inversely with the supply of methane, which suggested a competitive relationship between these two substrates. However, MeBr did not support growth of the methanotroph. In soils exposed to high levels (10,000 ppm) of MeBr, methane oxidation,vas completely inhibited. At this concentration, MeBr removal rates were equivalent in killed and live controls, which indicated a chemical rather than biological removal reaction. At lower concentrations (1,000 ppm) of MeBr, methanotrophs were active and MeBr consumption rates were 10-fold higher in live controls than in killed controls. Soils exposed to trace levels (10 ppm) of MeBr demonstrated complete consumption within 5 h of incubation, while controls inhibited with MeF or incubated without O-2 had 50% lower removal rates. Aerobic soils oxidized [C-14]MeBr to (CO2)-C-14, and MeF inhibited oxidation by 72%. Field experiments demonstrated slightly lower MeBr removal rates in chambers containing MeF than in chambers lacking MeF. Collectively, these results show that soil methanotrophic bacteria, as well as other microbes, can degrade MeBr present in the environment. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP OREMLAND, RS (reprint author), US GEOL SURVEY,345 MIDDLEFIELD RD,MENLO PK,CA 94025, USA. NR 37 TC 54 Z9 55 U1 0 U2 5 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1325 MASSACHUSETTS AVENUE, NW, WASHINGTON, DC 20005-4171 SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD OCT PY 1994 VL 60 IS 10 BP 3640 EP 3646 PG 7 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA PK266 UT WOS:A1994PK26600025 PM 7986039 ER PT J AU VANDERWAL, RL WEILAND, KJ AF VANDERWAL, RL WEILAND, KJ TI LASER-INDUCED INCANDESCENCE - DEVELOPMENT AND CHARACTERIZATION TOWARDS A MEASUREMENT OF SOOT-VOLUME FRACTION SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article ID DIFFUSION FLAMES; VISIBLE FLUORESCENCE; DIAGNOSTICS; PARTICLES AB Laser-Induced Incandescence (LII) occurs when a high-energy pulsed laser is used to heat soot to incandescent temperatures. Theoretical calculations predict and experimental tests demonstrate the resulting incandescence to be a measure of soot-volume fraction. Practical implementation of the technique is detailed by examining the spectral character, temporal behavior, and excitation-intensity dependence of the resulting thermal emission from the laser-heated soot in both premixed and diffusion flames. Spatial and temporal capabilities of LII are demonstrated by obtaining one- and two-dimensional images of soot-volume fraction via laser-induced incandescence in both types of flames. RP VANDERWAL, RL (reprint author), NASA,LEWIS RES CTR,21000 BROOKPARK RD,MAIL STOP 110-3,CLEVELAND,OH 44135, USA. NR 20 TC 155 Z9 155 U1 1 U2 15 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0946-2171 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD OCT PY 1994 VL 59 IS 4 BP 445 EP 452 PG 8 WC Optics; Physics, Applied SC Optics; Physics GA PN574 UT WOS:A1994PN57400010 ER PT J AU HE, QB LIU, HK YEH, P AF HE, QB LIU, HK YEH, P TI ASYMMETRIC PHOTOREFRACTIVE FABRY-PEROT ETALONS SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article AB We theoretically analyze the properties of Fabry-Perot etalons which consist of photorefractive-crystal plates with asymmetric mirror reflectance. Peak transmissions and non-reciprocities are enhanced significantly compared with the symmetric photorefractive etalons. The effect of material absorption is also considered. C1 UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106. RP HE, QB (reprint author), CALTECH,JET PROP LAB,MS 303310,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Yeh, Pochi/A-2109-2010 NR 8 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0946-2171 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD OCT PY 1994 VL 59 IS 4 BP 467 EP 470 DI 10.1007/BF01081069 PG 4 WC Optics; Physics, Applied SC Optics; Physics GA PN574 UT WOS:A1994PN57400012 ER PT J AU OUTLAW, RA LEE, WS HOEKJE, SJ SANKARAN, SN AF OUTLAW, RA LEE, WS HOEKJE, SJ SANKARAN, SN TI SULFUR SEGREGATION IN TITANIUM AND SELECTED TITANIUM-ALLOYS SO APPLIED SURFACE SCIENCE LA English DT Article ID FREE SURFACES; AUGER AB The segregation of S in electrotransport-purified polycrystalline alpha-Ti and in several polycrystalline Ti alloys has been studied by Auger electron spectroscopy and ion scattering spectroscopy in the temperature range extending from 20 to 1000-degrees-C. The chemisorbed oxygen and carbon on Ti were observed to disappear at T > 400-degrees-C after which the S signal increased to levels approaching 0.5 monolayer. At lower temperatures the presence of the surface oxygen and carbon appeared to inhibit the segregation, presumably because there were no available surfaces sites for the S emerging from the bulk. The activation energy for the S segregation in pure polycrystalline Ti was determined to be 16.7 kcal/mol, which, when compared to S segregation from single-crystal Ti, is quite small and suggests grain boundary or defect diffusion segregation kinetics. In the Ti-aluminide alloys, the presence of Al appeared to enhance the retention of surface oxygen which, in turn, substantially reduced the S segregation. The gamma alloy, with its high Al content, exhibited the greatest retention of surface oxygen and the smallest quantity of S segregation (T almost-equal-to 1000-degrees-C). On the other hand, the beta-21S alloy exhibited a greater segregation rate for the S than did alpha-Ti. C1 HAMPTON UNIV,HAMPTON,VA 23668. RP OUTLAW, RA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 19 TC 4 Z9 4 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-4332 J9 APPL SURF SCI JI Appl. Surf. Sci. PD OCT PY 1994 VL 81 IS 2 BP 143 EP 150 DI 10.1016/0169-4332(94)00165-0 PG 8 WC Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Chemistry; Materials Science; Physics GA PK160 UT WOS:A1994PK16000005 ER PT J AU NAYAK, PP AF NAYAK, PP TI CAUSAL APPROXIMATIONS SO ARTIFICIAL INTELLIGENCE LA English DT Article ID MODEL; SIMULATION; BEHAVIOR; CIRCUITS AB Adequate models require the identification of abstractions and approximations that are well suited to the task at hand. In this paper we analyze the problem of automatically selecting adequate models for the task of generating parsimonious causal explanations. We make three important contributions. First, we develop a precise formalization of this problem. In this formalization, models are defined as sets of model fragments, causal explanations are generated using causal ordering, and model simplicity is based on the intuition that using more approximate descriptions of fewer phenomena leads to simpler models. Second, we use this formalization to show that the problem is intractable (NP-hard) and identify three sources of intractability: (a) deciding what phenomena to model; (b) deciding how to model the chosen phenomena; and (c) satisfying domain-dependent constraints. Third, we introduce a new class of approximations called causal approximations that are commonly found in modeling the physical world. Causal approximations are based on the idea that more approximate descriptions usually explain less about a phenomenon than more accurate descriptions. Hence, when all approximations are causal approximations, the causal relations entailed by a model decrease monotonically as models become simpler, leading to an efficient, polynomial-time algorithm for finding adequate models. RP NAYAK, PP (reprint author), NASA,AMES RES CTR,AI RES BRANCH,MS 269-2,MOFFETT FIELD,CA 94035, USA. NR 52 TC 39 Z9 39 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0004-3702 J9 ARTIF INTELL JI Artif. Intell. PD OCT PY 1994 VL 70 IS 1-2 BP 277 EP 334 DI 10.1016/0004-3702(94)90108-2 PG 58 WC Computer Science, Artificial Intelligence SC Computer Science GA PQ999 UT WOS:A1994PQ99900008 ER PT J AU GARMANY, CD MASSEY, P PARKER, JW AF GARMANY, CD MASSEY, P PARKER, JW TI THE OB-ASSOCIATION LH-58 IN THE LARGE MAGELLANIC CLOUD SO ASTRONOMICAL JOURNAL LA English DT Article ID WOLF-RAYET STARS; MASSIVE STARS; STELLAR CONTENT; SPECTROPHOTOMETRY; CLASSIFICATION; EVOLUTION; GALAXIES; CLUSTERS; TABLES; LINES AB We present CCD photometry and spectroscopy for stars in Lucke-Hodge 58, an isolated OB association in the Large Magellanic Cloud (LMC) northwest of 30 Doradus. The photometric catalog contains 839 stars with UBV magnitudes complete to V approximate to 19. We have obtained spectra and classified 35 stars; combined with previous published spectral types, we find 22 O-type stars. The earliest type is 03-4 V, and there are three WR stars in the association. The slope of the initial mass function, Gamma=-1.7+/-0.3, is in good agreement with other LMC associations. The presence of several evolved supergiants with masses about 15-25.M(circle dot) suggests that some star formation took place as early as 10 million years ago, but the majority of stars formed coevally within the past few million years. C1 NATL OPT ASTRON OBSERV,KITT PEAK NATL OBSERV,TUCSON,AZ 85726. NASA,GODDARD SPACE FLIGHT CTR,ASTROPHYS & SPACE ASTRON LAB,GREENBELT,MD 20771. RP GARMANY, CD (reprint author), UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOX 440,BOULDER,CO 80309, USA. NR 51 TC 33 Z9 33 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 1994 VL 108 IS 4 BP 1256 EP 1265 DI 10.1086/117151 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ505 UT WOS:A1994PJ50500010 ER PT J AU WHITNEY, JH OCONNELL, RW ROOD, RT DORMAN, B LANDSMAN, WB CHENG, KP BOHLIN, RC HINTZEN, PMN ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP AF WHITNEY, JH OCONNELL, RW ROOD, RT DORMAN, B LANDSMAN, WB CHENG, KP BOHLIN, RC HINTZEN, PMN ROBERTS, MS SMITH, AM SMITH, EP STECHER, TP TI FAR-ULTRAVIOLET PHOTOMETRY OF THE GLOBULAR-CLUSTER OMEGA-CEN SO ASTRONOMICAL JOURNAL LA English DT Article ID HORIZONTAL-BRANCH STARS; UV-BRIGHT STARS; SOUTHERN SPECTROPHOTOMETRIC STANDARDS; IMAGING TELESCOPE; ELLIPTIC GALAXIES; IUE OBSERVATIONS; CENTAURI; M5; M3; DWARFS AB We present far-ultraviolet images of the globular cluster omega Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620 Angstrom to a limiting UV magnitude of 16.4 in the central 24' diameter region of the field and a limit of 15.6 over the remainder of the 40' diameter field. Over 1400 of these sources are matched with stars on a Stromgren u band CCD frame obtained with the CTIO 0.9 m telescope to produce a (far-UV, u) color-magnitude diagram. Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000 It. A large number of ''extreme HB'' stars are found hotter than a conspicuous break in the HB at T-e similar to 16 000 K. There is also a significant population of stars above the HB, the brightest of which is 4 mag brighter than the HB. Most of the hotter of these appear to be ''AGB-manque'' or ''Post-Early Asymptotic Giant Branch'' stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with T-e greater than or similar to 50 000 K, which are hotter than zero-age HB stars with envelope masses of 0.003 M(circle dot) . C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CALIF STATE UNIV LONG BEACH,DEPT PHYS & ASTRON,LONG BEACH,CA 90840. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP WHITNEY, JH (reprint author), UNIV VIRGINIA,DEPT ASTRON,POB 3818,CHARLOTTESVILLE,VA 22903, USA. NR 58 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 1994 VL 108 IS 4 BP 1350 EP 1363 DI 10.1086/117157 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ505 UT WOS:A1994PJ50500016 ER PT J AU NORIEGACRESPO, A GARNAVICH, PM AF NORIEGACRESPO, A GARNAVICH, PM TI MOLECULAR-HYDROGEN AND EXCITATION IN THE HH-1-2 SYSTEM SO ASTRONOMICAL JOURNAL LA English DT Article ID HERBIG-HARO OBJECTS; LINE EMISSION MODELS; INTERSTELLAR SHOCKS; INFRARED-EMISSION; H2 EMISSION; BOW SHOCKS; JETS; SPECTROSCOPY; VARIABILITY; COMPLEX AB We present a series of molecular hydrogen images of the Herbig-Haro 1-2 system in the 1-0 S(1) transition at 2.121 mu m, with a spatial resolution of similar to-2''. The distribution of H-2 is then compared with that of the excitation, given by the [S II] 6717+6731 to H alpha line ratio. We find that most optical condensations in the HH 1-2 system, including the VLA 1 jet, have Hz counterparts. H-2 emission is detected in most low excitation knots, as expected for low velocity shocks (50 km s(-1)<), but also in high excitation regions, like in HH 1F and HH 2A'. For these latter objects, the H-2 emission could be due to the interaction of the preionizing flux, produced by 150-200 km s(-1) shocks, with the surrounding interstellar matter, i.e., fluorescence. The lack fluorescent lines in the UV, however, suggest a different mechanism. H-2 is detected at the tip of the VLA 1 jet, where the knot morphology suggests the presence of a second bow shock. H-2 is detected also SE of HH 2E and SW of HH 1F, in regions with known NH3 emission. C1 NATL RES COUNCIL CANADA,HERZBERG INST ASTROPHYS,DOMINION ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. RP NORIEGACRESPO, A (reprint author), CALTECH,CTR INFRARED PROC & ANAL,JPL,PASADENA,CA 91125, USA. NR 54 TC 18 Z9 18 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 1994 VL 108 IS 4 BP 1432 EP 1436 DI 10.1086/117166 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ505 UT WOS:A1994PJ50500025 ER PT J AU Sigl, G Schramm, DN Bhattacharjee, P AF Sigl, G. Schramm, D. N. Bhattacharjee, P. TI On the origin of highest energy cosmic rays SO ASTROPARTICLE PHYSICS LA English DT Article AB In this paper we show that the conventional diffusive shock acceleration mechanism for cosmic rays associated with relativistic astrophysical shocks in active galactic nuclei (AGNs) has severe difficulties to explain the highest energy cosmic ray events. We show that protons above around 2 x 10(20) eV could have marginally been produced by this mechanism in an AGN or a rich galaxy cluster not further away than around 100 Mpc. However, for the highest energy Fly's Eye and Yakutsk events this is inconsistent with the observed arrival directions. Galactic and intergalactic magnetic fields appear unable to alter the direction of such energetic particles by more than a few degrees. We also discuss some other options for these events associated with relativistic particles including pulsar acceleration of high Z nuclei. At the present stage of knowledge the concept of topological defects left over from the early universe as the source for such events appears to be a promising option. Such sources are discussed and possible tests of this hypothesis are proposed. C1 [Sigl, G.; Schramm, D. N.] Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. [Sigl, G.; Schramm, D. N.] NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. [Bhattacharjee, P.] Indian Inst Astrophys, Bangalore 560034, Karnataka, India. RP Sigl, G (reprint author), Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. FU NSF at the University of Chicago; NASA at the University of Chicago; DOE at the University of Chicago; DOE; NASA at Fermi lab [NAGW 2381]; Alexander-von-Humboldt Foundation FX We would like to thank James Cronin, Eugene Parker, Hongyue Dai, Stirling Colgate, Gene Loh, Cy Hoffman, Corbin Covault, Felix Aharonian, Arnold Wolfendale and Bob Nichol for highly valuable discussions. In addition, we are grateful to Paul Sommers and Rene Ong for their suggestions concerning the manuscript. Furthermore, we thank the editor Tom Gaisser and the referee for various points brought to our attention. We would also like to thank Chris Hill for his collaboration in earlier papers dealing with topological defects and his enthusiastic contributions to this topic. This work has been supported, in part, by NSF, NASA and the DOE at the University of Chicago, by the DOE and by NASA through grant NAGW 2381 at Fermi lab and by the Alexander-von-Humboldt Foundation. NR 76 TC 122 Z9 123 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD OCT PY 1994 VL 2 IS 4 BP 401 EP 414 DI 10.1016/0927-6505(94)90029-9 PG 14 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA V26DQ UT WOS:000208526700007 ER PT J AU KOGUT, A BANDAY, AJ BENNETT, CL HINSHAW, G LOEWENSTEIN, K LUBIN, P SMOOT, GF WRIGHT, EL AF KOGUT, A BANDAY, AJ BENNETT, CL HINSHAW, G LOEWENSTEIN, K LUBIN, P SMOOT, GF WRIGHT, EL TI SEARCH FOR UNRESOLVED SOURCES IN THE CODE-DMR 2-YEAR SKY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; RADIO CONTINUUM; GENERAL ID DIFFERENTIAL MICROWAVE RADIOMETER; MILLIMETER CONTINUUM MEASUREMENTS; DEGREE ANGULAR SCALES; BACKGROUND-RADIATION; ANISOTROPY AB We have searched the temperature maps from the COBE Differential Microwave Radiometers (DMR) first two years of data for evidence of unresolved sources. The high-latitude sky (Absolute value of b > 30-degrees) contains no sources brighter than 192 muK thermodynamic temperature (322 Jy at 53 GHz). The cumulative count of sources brighter than threshold T, N(>T), is consistent with a superposition of instrument noise plus scale-invariant spectrum of cosmic temperature fluctuations normalized to Q(rms-PS) = 17 muK. We examine the temperature maps toward nearby clusters and find no evidence for any Sunyaev-Zel'dovich effect, DELTAy < 7.3 x 10(-6) (95% CL) averaged over the DMR beam. We examine the temperature maps near the brightest expected radio sources and detect no evidence of significant emission. The lack of bright unresolved sources in the DMR maps, taken with anisotropy measurements on smaller angular scales, places a weak constraint on the integral number density of any unresolved Planck-spectrum sources brighter than flux density S, n(>S) < 2 x 10(4) (S/1 jy)-2 sr-1. C1 NASA, GODDARD SPACE FLIGHT CTR, GSFC, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. UCSB, DEPT PHYS, SANTA BARBARA, CA 93106 USA. UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. UNIV CALIF BERKELEY, SSL, LBL, BERKELEY, CA 94720 USA. UNIV CALIF BERKELEY, CFPA, BERKELEY, CA 94720 USA. RP KOGUT, A (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GSFC, HUGHES STX CORP, CODE 685 3, GREENBELT, MD 20771 USA. RI Kogut, Alan/D-6293-2012 NR 24 TC 14 Z9 14 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 1 PY 1994 VL 433 IS 2 BP 435 EP 439 DI 10.1086/174655 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ925 UT WOS:A1994PJ92500001 ER PT J AU DODELSON, S STEBBINS, A AF DODELSON, S STEBBINS, A TI ANALYSIS OF SMALL-SCALE MICROWAVE BACKGROUND-RADIATION ANISOTROPY IN THE PRESENCE OF FOREGROUND CONTAMINATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, THEORY; LARGE-SCALE STRUCTURE OF UNIVERSE ID RADIOMETER AB Many of the current round of experiments searching for anisotroPies in the microwave background radiation (MBR) are confronting the problem of how to disentangle the cosmic signal from contamination due to Galactic and intergalactic foreground sources. Here we show how commonly used likelihood function techniques can be generalized to account for foreground. Specifically we set some restrictions on the spectrum of foreground contamination but allow the amplitude to vary arbitrarily. The likelihood function thus generalized gives reasonable limits on the MBR anisotropy which, in some cases, are not much less restrictive than what one would get from more detailed modeling of the foreground. Furthermore, the likelihood function is exactly the same as one would obtain by simply projecting out foreground contamination and looking at the reduced data set. We apply this generalized analysis to the recent medium-angle data sets of ACME-HEMT (Gaier et al. 1992; Schuster et al. 1993) and MAX (Meinhold et al. 1993; Gunderson et al. 1993). The resulting analysis constrains the one free parameter in the standard cold dark matter theory to be Q(rms-ps) = 18(-5)+8 muK. This best fit value, although in striking agreement with the normalization from COBE, is not a very good fit, with an overall chi2/degrees of freedom = 208/168. We also argue against three commonly used methods of dealing with foreground: (1) ignoring it completely; (2) subtracting off a best-fit foreground and treating the residuals as if uncontaminated; and (3) culling data which appears to be contaminated by foreground. RP DODELSON, S (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 13 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1994 VL 433 IS 2 BP 440 EP 453 DI 10.1086/174656 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ925 UT WOS:A1994PJ92500002 ER PT J AU WHITE, RE DAY, CSR HATSUKADE, I HUGHES, JP AF WHITE, RE DAY, CSR HATSUKADE, I HUGHES, JP TI ABUNDANCE GRADIENTS IN COOLING FLOW CLUSTERS - GINGA LARGE-AREA COUNTERS AND EINSTEIN SOLID-STATE SPECTROMETER SPECTRA OF A496, A1795, A2142, AND A2199 SO ASTROPHYSICAL JOURNAL LA English DT Article DE COOLING FLOWS; GALAXIES, ABUNDANCES; GALAXIES, CLUSTERS OF; X-RAYS, GALAXIES ID X-RAY-EMISSION; INTRACLUSTER GAS; PERSEUS CLUSTER; VIRGO CLUSTER; SPATIAL-DISTRIBUTION; EXOSAT OBSERVATIONS; ABSORBING MATTER; OPTICAL-EMISSION; COMA CLUSTER; DARK MATTER AB We analyze the Ginga LAC and Einstein SSS spectra of four cooling flow clusters, A496, A1795, A2142, and A2199, each of which shows firm evidence of a relatively cool component. The inclusion of such cool spectral components in joint fits of SSS and LAC data leads to somewhat higher global temperatures than are derived from the high-energy LAC data alone. We find little evidence of cool emission outside the SSS field of view. Metal abundances appear to be centrally enhanced in all four clusters, with varying degrees of model dependence and statistical significance: the evidence is statistically strongest for A496 and A2142, somewhat weaker for A2199 and weakest for A1795. We also explore the model dependence in the amount of cold, X-ray absorbing matter discovered in these clusters by White et al. C1 MIYAZAKI UNIV,DEPT ELECTR ENGN,MIYAZAKI 88921,JAPAN. NASA,GODDARD SPACE FLIGHT CTR,GSFC,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP WHITE, RE (reprint author), UNIV ALABAMA,DEPT PHYS & ASTRON,BOX 870324,TUSCALOOSA,AL 35487, USA. NR 69 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 OCT 1 PY 1994 VL 433 IS 2 BP 583 EP 601 DI 10.1086/174669 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ925 UT WOS:A1994PJ92500015 ER PT J AU KRISHER, TP AF KRISHER, TP TI A POTENTIAL NEW TEST FOR UNSEEN MATTER IN THE OUTER SOLAR-SYSTEM SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; SOLAR SYSTEM, GENERAL; TECHNIQUES, RADAR ASTRONOMY ID GRAVITATIONAL REDSHIFT; PLANET-X; COMETS AB The recent development of trapped-ion frequency standards, which offer high stability over long time periods, provides us with a potential new method for detecting unseen matter in the outer solar system. A distribution of matter or a planetary body could produce a measurable gravitational redshift of the radio signal received from a spacecraft equipped with an ultrastable frequency standard. Trapped-ion standards have a potential frequency stability of 1 part in 10(16) or better over long time periods (> 10(6) s). We consider the potential improvements this method could yield over conventional dynamical tests for unseen matter in the outer solar system possible now or anticipated in the near future. RP KRISHER, TP (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 31 TC 4 Z9 4 U1 0 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 OCT 1 PY 1994 VL 433 IS 2 BP 666 EP 669 DI 10.1086/174675 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ925 UT WOS:A1994PJ92500021 ER PT J AU KUIPER, TBH AF KUIPER, TBH TI ON THE ANALYSIS OF PARA-AMMONIA OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; METHODS, DATA ANALYSIS; RADIO LINES, ISM ID MOLECULAR CLOUD; METHYL CYANIDE; NH3; TEMPERATURE; LINES AB The intensities and optical depths of the (1, 1), (2, 2), and (2, 1) inversion transitions of ammonia can be calculated quite accurately without solving the equations of statistical equilibrium. A two-temperature partition function suffices. The excitation of the K-ladders can be approximated by using a temperature obtained from a two-level model with the (2, 1) and (1, 1) levels. Distribution of populations between the ladders is described with the kinetic temperature. This enables one to compute the (1, 1) and (2, 1) inversion transition excitation temperatures and optical depths. To compute the (2, 2) brightness temperatures, the fractional population of the (2, 2) doublet is computed from the population of the (1, 1) doublet using the ''true rotation temperature,'' which is calculated using a three-level model with the (2, 1), (2, 2), and (1, 1) levels. In spite of some iterative steps, the calculation is quite fast. RP KUIPER, TBH (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 19 TC 6 Z9 6 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1994 VL 433 IS 2 BP 712 EP 718 DI 10.1086/174679 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ925 UT WOS:A1994PJ92500025 ER PT J AU HANNER, MS BROOKE, TY TOKUNAGA, AT AF HANNER, MS BROOKE, TY TOKUNAGA, AT TI SILICATES AND AROMATIC-HYDROCARBONS IN THE 10 MICRON SPECTRUM OF THE TAURUS DARK CLOUD SOURCE ELIAS-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, INDIVIDUAL (ELIAS-1); STARS PRE-MAIN-SEQUENCE ID INFRARED-EMISSION BANDS; FEATURES; STARS; DUST AB We have obtained 10.4-12 mum spectra at spectral resolution R almost-equal-to 190 of the Herbig Ae star Elias 1 in the Taurus dark cloud with the UKIRT CGS3 spectrometer, along with an 8-13 mum spectrum at R almost-equal-to 55. The 11.2 mum emission feature matches the wavelength, shape, and FWHM of the 11.22 mum aromatic hydrocarbon band, consistent with the presence of other aromatic features. A strong 11.06 mum feature is present, and there are two possible new emission features at 11.6 and 11.76 mum. The strong silicate emission feature is broader and peaks at a longer wavelength than can be reproduced with the Trapezium emissivity. Larger grains, with mean radius a approximately 1.5 mum, appear to be required, a possible indication of grain growth around a young star. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP HANNER, MS (reprint author), JET PROP LAB,MAIL STOP 183-601,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1994 VL 433 IS 2 BP L97 EP L100 DI 10.1086/187557 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ927 UT WOS:A1994PJ92700012 ER PT J AU PALMER, DM TEEGARDEN, BJ SCHAEFER, BE CLINE, TL BAND, DL FORD, LA MATTESON, JL PACIESAS, WS PENDLETON, GN BRIGGS, MS PREECE, RD FISHMAN, GJ MEEGAN, CA WILSON, RB AF PALMER, DM TEEGARDEN, BJ SCHAEFER, BE CLINE, TL BAND, DL FORD, LA MATTESON, JL PACIESAS, WS PENDLETON, GN BRIGGS, MS PREECE, RD FISHMAN, GJ MEEGAN, CA WILSON, RB TI BATSE GAMMA-RAY BURST LINE SEARCH .1. SEARCH FOR NARROW LINES IN SPECTROSCOPY DETECTOR DATA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS ID CYCLOTRON AB Analysis of data from the Spectroscopy Detectors (SDs) of the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (GRO) has found no convincing line features in the spectra of gamma-ray bursts (GRBs) in almost 3 years of operation, in contrast to expectations based on results from other experiments. In this Letter we discuss the visual search for narrow lines in the SD data. The search has examined 192 bursts, of which approximately 18 were intense enough that lines similar to those seen by instruments on the Ginga satellite would have been visible between approximately 20 and approximately 100 keV. A simplified calculation shows that the BATSE and Ginga results are consistent at the 13% level. C1 UNIV CALIF SAN DIEGO,CASS,LA JOLLA,CA 92093. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. MISSISSIPPI STATE UNIV,MISSISSIPPI STATE,MS 39762. RP PALMER, DM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 19 TC 28 Z9 28 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 1994 VL 433 IS 2 BP L77 EP L80 DI 10.1086/187552 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ927 UT WOS:A1994PJ92700007 ER PT J AU FICHTEL, CE BERTSCH, DL CHIANG, J DINGUS, BL ESPOSITO, JA FIERRO, JM HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MCDONALD, L MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINKAU, K RADECKE, HD ROTHERMEL, H SREEKUMAR, P SOMMER, M SCHNEID, EJ THOMPSON, DJ WILLIS, T AF FICHTEL, CE BERTSCH, DL CHIANG, J DINGUS, BL ESPOSITO, JA FIERRO, JM HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MCDONALD, L MICHELSON, PF VONMONTIGNY, C NOLAN, PL PINKAU, K RADECKE, HD ROTHERMEL, H SREEKUMAR, P SOMMER, M SCHNEID, EJ THOMPSON, DJ WILLIS, T TI THE FIRST ENERGETIC GAMMA-RAY EXPERIMENT TELESCOPE (EGRET) SOURCE CATALOG SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GAMMA RAYS, OBSERVATIONS ID ACTIVE GALACTIC NUCLEI; MAGELLANIC CLOUD; COMPLETE SAMPLE; RADIO-SOURCES; COMPTON; RADIATION; EMISSION; BLAZARS; GEMINGA; SPECTRA AB In this catalog the results related to high-energy gamma-ray sources obtained from the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory are summarized for the period from 1991 April 22 to 1992 November 17, called phase I. This phase ofthe Compton Observatory mission was devoted to an all-sky survey. Tables are included for the following EGRET results: solar flares with detected gamma radiation; pulsars; sources with \b\ < 10 degrees; gamma-ray bursts; normal galaxies; clusters of galaxies; positive detections of radio-loud quasars and BL Lac objects; marginal detections of radio-loud quasars and BL Lac objects; upper limits for radio-loud quasars and BL Lac objects; upper limits for Seyfert galaxies and selected radio-quiet quasars, and other sources with \b\ greater than or equal to 10 degrees the Galactic plane. There is also a table relating the dates of the observations to the Compton Observatory viewing period numbers to assist in referencing the observations. C1 STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. NAS,NRC RES ASSOCIATE,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,CTR SCI SUPPORT,COMPTON OBSERV,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP FICHTEL, CE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 662,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 52 TC 315 Z9 317 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD OCT PY 1994 VL 94 IS 2 BP 551 EP 581 DI 10.1086/192082 PG 31 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PH224 UT WOS:A1994PH22400003 ER PT J AU NOEVER, DA AF NOEVER, DA TI CRYSTALLOGRAPHY OF RARE GALACTIC HONEYCOMB STRUCTURE NEAR SUPERNOVA 1987A SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID CELLS AB Near supernova 1987a, the rare honeycomb structure of 20-30 galactic bubbles measures 30 x 90 light years. Its remarkable regularity in bubble size suggests a single-event origin which may correlate with the nearby supernova. To test the honeycomb's regularity in shape and size, the formalism of statistical crystallography is developed here for bubble sidedness. The standard size-shape relations (Lewis's law, Desch's law, and Aboav-Weaire's law) govern area, perimeter and nearest neighbor shapes. Taken together, they predict a highly non-equilibrium structure for the galactic honeycomb which evolves as a bimodal shape distribution without dominant bubble perimeter energy. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 15 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 OCT PY 1994 VL 220 IS 1 BP 65 EP 74 DI 10.1007/BF00628077 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ758 UT WOS:A1994PQ75800005 ER PT J AU DADONAS, V SPERAUSKAS, J FEKEL, FC MORTON, MD AF DADONAS, V SPERAUSKAS, J FEKEL, FC MORTON, MD TI RADIAL-VELOCITY MEASUREMENTS OF THE CHROMOSPHERICALLY-ACTIVE STARS .2. HD28591=V492 PER SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article ID BINARY STARS; PHOTOMETRY AB From two sets of the spectroscopic observations covering a ten year period we have obtained 59 radial velocities of the chromospherically-active star HD 28591 = V492 Per. It is a G9III single-lined spectroscopic binary with a period of 21.2910 days and a circular orbit. The nu sin i of 24.6 km s-1, results in a minimum radius 10.3R.. We estimate a distance of 165 +/- 40 pc and an orbital inclination of 65 +/- 25 degrees. The secondary is probably a mid to late-type K dwarf. The star is brighter than the limiting magnitude of the Bright Star Catalogue. The mean photometric and the orbital periods are identical within their uncertainties. Since the star fills a significant fraction of its Roche lobe, about 62%, the photometric light curve may be the result of starspots and a modest ellipticity effect. C1 NASA,MSFC,HUNTSVILLE,AL. VANDERBILT UNIV,DEPT PHYS & ASTRON,NASHVILLE,TN 37240. RP DADONAS, V (reprint author), VILNIUS UNIV,ASTRON OBSERV,VILNIUS,LITHUANIA. NR 20 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 OCT PY 1994 VL 220 IS 1 BP 97 EP 105 DI 10.1007/BF00628080 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ758 UT WOS:A1994PQ75800008 ER PT J AU GAWRONSKI, W AF GAWRONSKI, W TI A BALANCED LQG COMPENSATOR FOR FLEXIBLE STRUCTURES SO AUTOMATICA LA English DT Article DE CONTROL SYSTEM DESIGN; LINEAR OPTIMAL CONTROL; CONTROLLER REDUCTION; FLEXIBLE STRUCTURES ID MODEL-REDUCTION; LINEAR-SYSTEMS AB LQG compensator gains (i.e. the gains of a controller and of an estimator) are obtained from solutions of Riccati equations. For the balanced compensator the solutions are equal and diagonal. An approximately balanced LQG compensator for flexible structures is analyzed in this paper. The performance of an LQG compensator depends on the weights of the quadratic performance index and on the variance of the estimator noise. The relationships between weights/variances and characteristic values of the system as well as between weights/variances and the system pole location are derived. Thus the weights can be determined to meet the requirements of a closed-loop system. For the balanced reduced-order compensator the stability margin and performance are similar to the fun-order compensator. RP GAWRONSKI, W (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 7 Z9 7 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0005-1098 J9 AUTOMATICA JI Automatica PD OCT PY 1994 VL 30 IS 10 BP 1555 EP 1564 DI 10.1016/0005-1098(94)90095-7 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA PN585 UT WOS:A1994PN58500004 ER PT J AU MCFADDEN, TJ HELMREICH, RL ROSE, RM FOGG, LF AF MCFADDEN, TJ HELMREICH, RL ROSE, RM FOGG, LF TI PREDICTING ASTRONAUT EFFECTIVENESS - A MULTIVARIATE APPROACH SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB In this study, measures of astronaut effectiveness were administered to volunteers from the astronaut corps in order to validate psychological ''select-in'' criteria for long-duration space missions. Using a peer nomination format, astronauts rated their peers with whom they had either flown or trained. Factor analysis revealed two latent performance dimensions: job competence and group living. The job competence dimension measured the instrumental aspects relating to job knowledge and job performance. The group living dimension measured the interpersonal aspects relating to teamwork and desirability as ct colleague on Space Station. Analyses revealed that the personality variables could explain a significant proportion of the variance in the group living performance dimension, but not the job competence performance dimension. The findings are not surprising since astronauts are highly screened on the basis of past attainment, but are not as highly screened on aspects relating to teamwork and interpersonal concerns. C1 MACARTHUR FDN,CHICAGO,IL. RP MCFADDEN, TJ (reprint author), UNIV TEXAS,NASA,FAA,AEROSP CREW RES PROJECT,AUSTIN,TX 78701, USA. NR 13 TC 25 Z9 25 U1 2 U2 3 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 1994 VL 65 IS 10 BP 904 EP 909 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PK843 UT WOS:A1994PK84300003 PM 7832731 ER PT J AU ROSE, RM FOGG, LF HELMREICH, RL MCFADDEN, TJ AF ROSE, RM FOGG, LF HELMREICH, RL MCFADDEN, TJ TI PSYCHOLOGICAL PREDICTORS OF ASTRONAUT EFFECTIVENESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB Are the personality characteristics of astronauts related to their professional effectiveness? In order to answer this question, effectiveness and personality data were collected from 65 NASA astronauts. Several findings emerged from these data. Five personality subscales were related to effectiveness in one form or another. They were: high Negative Expressivity and Negative Communion (subordinate and gullible), low Impatience and Irritability, low Openness (to new ideas and experiences), low Negative Instrumentality (egotism) and high Agreeableness. Examining the graphs of these relationships indicated that they were not linear. This examination indicated that high levels on these undesirable personality characteristics (e.g., Impatience/lrritability) were distributed across all levels of effectiveness. Low levels of the undesirable personality characteristics were found only among the most effective astronauts. We concluded that these other-directed personality qualities will assume increasing importance in long-term spaceflight, and consequently, should be the focus of greater attention in future astronaut selection and training. C1 RUSH UNIV,DEPT PSYCHIAT & PSYCHOL,CHICAGO,IL 60612. UNIV TEXAS,NASA,FAA,AEROSP CREW RES PROJECT,AUSTIN,TX 78712. RP ROSE, RM (reprint author), JOHN D & CATHERINE T MACARTHUR FDN,140 S DEARBORN ST,SUITE 1100,CHICAGO,IL 60603, USA. NR 10 TC 40 Z9 41 U1 1 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD OCT PY 1994 VL 65 IS 10 BP 910 EP 915 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PK843 UT WOS:A1994PK84300004 PM 7832732 ER PT J AU IMHOFF, ML AF IMHOFF, ML TI MAPPING HUMAN IMPACTS ON THE GLOBAL BIOSPHERE SO BIOSCIENCE LA English DT Note RP IMHOFF, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. NR 1 TC 6 Z9 6 U1 0 U2 1 PU AMER INST BIOLOGICAL SCI PI WASHINGTON PA 1444 EYE ST, NW, STE 200, WASHINGTON, DC 20005 SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD OCT PY 1994 VL 44 IS 9 BP 598 EP 598 PG 1 WC Biology SC Life Sciences & Biomedicine - Other Topics GA PJ530 UT WOS:A1994PJ53000007 ER PT J AU HELD, IM SUAREZ, MJ AF HELD, IM SUAREZ, MJ TI A PROPOSAL FOR THE INTERCOMPARISON OF THE DYNAMICAL CORES OF ATMOSPHERIC GENERAL-CIRCULATION MODELS SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID RADIATION CODES; VARIABILITY; EQUATIONS; CLIMATE AB A benchmark calculation is proposed for evaluating the dynamical cores of atmospheric general circulation models independently of the physical parameterizations. The test focuses on the long-term statistical properties of a fully developed general circulation; thus, it is particularly appropriate for intercomparing the dynamics used in climate models. To illustrate the use of this benchmark, two very different atmospheric dynamical cores-one spectral, one finite difference-are compared. It is found that the long-term statistics produced by the two models are very similar. Selected results from these calculations are presented to initiate the intercomparison. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HELD, IM (reprint author), PRINCETON UNIV,NOAA,GEOPHYS FLUID DYNAM LAB,POB 308,PRINCETON,NJ 08542, USA. NR 17 TC 451 Z9 461 U1 1 U2 15 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 OCT PY 1994 VL 75 IS 10 BP 1825 EP 1830 DI 10.1175/1520-0477(1994)075<1825:APFTIO>2.0.CO;2 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN886 UT WOS:A1994PN88600005 ER PT J AU GILMOUR, S MONTGOMERY, RA MARDER, SR CHENG, LT JEN, AKY CAI, YM PERRY, JW DALTON, LR AF GILMOUR, S MONTGOMERY, RA MARDER, SR CHENG, LT JEN, AKY CAI, YM PERRY, JW DALTON, LR TI SYNTHESIS OF DIARYLTHIOBARBITURIC ACID CHROMOPHORES WITH ENHANCED 2ND-ORDER OPTICAL NONLINEARITIES AND THERMAL-STABILITY SO CHEMISTRY OF MATERIALS LA English DT Note ID STILBENE DERIVATIVES; POLARIZABILITIES; MOLECULES C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,DEPT CHEM,LOS ANGELES,CA 90089. CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. ENICHEM AMER INC,CTR RES & DEV,MONMOUTH JCT,NJ 08852. DUPONT CO INC,CENT RES & DEV,WILMINGTON,DE 19880. RI Jen, Alex/E-5957-2012; Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 20 TC 82 Z9 82 U1 1 U2 9 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD OCT PY 1994 VL 6 IS 10 BP 1603 EP 1604 DI 10.1021/cm00046a007 PG 2 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA PM630 UT WOS:A1994PM63000007 ER PT J AU HODIS, HN SELZER, RH KWONGFU, H MACK, WJ LIU, CR LIU, CH LEE, PL AF HODIS, HN SELZER, RH KWONGFU, H MACK, WJ LIU, CR LIU, CH LEE, PL TI AUTOMATED COMPUTERIZED EDGE TRACKING - A NEW METHOD FOR MEASUREMENT OF CAROTID ARTERIAL-WALL INTIMA-MEDIA THICKNESS SO CIRCULATION LA English DT Meeting Abstract C1 UNIV SO CALIF,LOS ANGELES,CA 90089. JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0009-7322 J9 CIRCULATION JI Circulation PD OCT PY 1994 VL 90 IS 4 BP 535 EP 535 PN 2 PG 1 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA PN417 UT WOS:A1994PN41702913 ER PT J AU VANELST, H LIDSEY, JE TAVAKOL, R AF VANELST, H LIDSEY, JE TAVAKOL, R TI QUANTUM COSMOLOGY AND HIGHER-ORDER LAGRANGIAN THEORIES SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article ID INFLATIONARY UNIVERSE; GENERAL-RELATIVITY; HIGHER DERIVATIVES; 4TH-ORDER GRAVITY; CREATION; MODELS; STATE; LIMIT AB In this paper the quantum cosmological consequences of introducing a term cubic in the Ricci curvature scalar R into the Einstein-Hilbert action are investigated. It is argued that this term represents a more generic perturbation to the action than the quadratic correction usually considered. A qualitative argument suggests that there exists a region of parameter space in which neither the tunnelling nor the no-boundary boundary conditions predict an epoch of inflation that can solve the horizon and flatness problems of the standard big bang model. This is in contrast to the R(2)-theory. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP VANELST, H (reprint author), UNIV LONDON QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,MILE END RD,LONDON E1 4NS,ENGLAND. NR 37 TC 18 Z9 18 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD OCT PY 1994 VL 11 IS 10 BP 2483 EP 2497 PG 15 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PP746 UT WOS:A1994PP74600008 ER PT J AU CHENG, TS WEHRMEYER, JA PITZ, RW JARRETT, O NORTHAM, GB AF CHENG, TS WEHRMEYER, JA PITZ, RW JARRETT, O NORTHAM, GB TI RAMAN MEASUREMENT OF MIXING AND FINITE-RATE CHEMISTRY IN A SUPERSONIC HYDROGEN-AIR DIFFUSION FLAME SO COMBUSTION AND FLAME LA English DT Article ID KRF EXCIMER LASER; OH A2-SIGMA+; SCATTERING; PREDISSOCIATION AB Ultraviolet (UV) spontaneous vibrational Raman scattering and laser-induced predissociative fluorescence (LIPF) from a KrF excimer laser are combined to simultaneously measure temperature, major species concentrations (H-2, O-2, N-2, H2O), and OH radical concentration in a supersonic lifted co-flowing hydrogen-air diffusion flame. The axisymmetric flame is formed when a sonic jet of hydrogen mixes with a Mach 2 annular jet of vitiated air. Mean and rms profiles of temperature, species concentrations, and mixture fraction are obtained throughout the supersonic flame. Simultaneous measurements of the chemical species and temperature are compared with frozen chemistry and equilibrium chemistry limits to assess the local state of the mixing and chemistry. Upstream of the lifted flame base, a very small amount of reaction occurs from mixing with hot vitiated air. Downstream of the lifted flame base, strong turbulent mixing leads to subequilibrium values of temperature and OH concentration. Due to the interaction of velocity and temperature in supersonic compressible flames, the fluctuations of temperature and species concentrations are found to be higher than subsonic flames. Farther downstream, slow three-body recombination reactions result in superequilibrium OH concentrations that depress temperatures below their equilibrium values. C1 VANDERBILT UNIV,DEPT MECH ENGN,NASHVILLE,TN 37235. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RI Pitz, Robert/H-7868-2016 OI Pitz, Robert/0000-0001-6435-5618 NR 26 TC 65 Z9 67 U1 1 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD OCT PY 1994 VL 99 IS 1 BP 157 EP 173 DI 10.1016/0010-2180(94)90087-6 PG 17 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA PH996 UT WOS:A1994PH99600010 ER PT J AU WANG, MM CHEN, JG YOON, HS VASUDEVAN, S WEBSTER, L AF WANG, MM CHEN, JG YOON, HS VASUDEVAN, S WEBSTER, L TI A HYPERMEDIA EXPERT-SYSTEM FOR ADVANCED CARDIAC LIFE-SUPPORT MANAGEMENT SO DECISION SUPPORT SYSTEMS LA English DT Article DE EXPERT SYSTEM; INTERACTIVE VIDEODISC TECHNOLOGY; ADVANCED CARDIAC LIFE SUPPORT SYSTEM; OBJECT ORIENTED PROGRAMMING AB A hypermedia expert system was developed to assist in diagnosing and recommending treatment for cardiac arrhythmia on space station freedom and to serve as a supplemental tool for training and retraining the crew in the practice of advanced cardiac life support (ACLS) protocols. The system includes five modules: ACLS expert system module, database module, reference-materials module, hypermedia instruction module, and friendly user interface module designed for the use of both the expert and the novice. More than 100 test scenarios adapted from ALCS mega code review study cards were used to validate the system as a performance aid and supplemental training tool. Results indicated that the subjects' performance improved significantly after consulting the system. The subjects also reached an acceptable level of performance after receiving 40-60 minutes training via the system. In conclusion, this system has been found to be an excellent ACLS supplemental training tool and performance aid and can also serve as a model and building block for developing a more advanced state of the art time-constrained decision support system. C1 UNIV HOUSTON,DEPT IND ENGN,HOUSTON,TX 77204. UNIV TEXAS,HLTH SCI CTR,DEPT ENDODONT,DENT BRANCH,HOUSTON,TX 77225. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 10 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-9236 J9 DECIS SUPPORT SYST JI Decis. Support Syst. PD OCT PY 1994 VL 12 IS 3 BP 169 EP 179 DI 10.1016/0167-9236(94)90001-9 PG 11 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Operations Research & Management Science SC Computer Science; Operations Research & Management Science GA PN276 UT WOS:A1994PN27600001 ER PT J AU ARDEMA, MD BOWLES, JV WHITTAKER, T AF ARDEMA, MD BOWLES, JV WHITTAKER, T TI OPTIMAL TRAJECTORIES FOR HYPERSONIC LAUNCH VEHICLES SO DYNAMICS AND CONTROL LA English DT Article AB In this paper, we derive a near-optimal guidance law for the ascent trajectory from earth surface to earth orbit of a hypersonic, dual-mode propulsion, lifting vehicle. Of interest are both the optimal flight path and the optimal operation of the propulsion system. The guidance law is developed from the energy-state approximation of the equations of motion. Because liquid hydrogen fueled hypersonic aircraft are volume sensitive, as well as weight sensitive, the cost functional is a weighted sum of fuel mass and volume; the weighting factor is chosen to minimize gross take-off weight for a given payload mass and volume in orbit. RP ARDEMA, MD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 9 Z9 9 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0925-4668 J9 DYNAM CONTROL JI Dynam. Control PD OCT PY 1994 VL 4 IS 4 BP 337 EP 347 DI 10.1007/BF01974139 PG 11 WC Automation & Control Systems; Engineering, Mechanical SC Automation & Control Systems; Engineering GA PN428 UT WOS:A1994PN42800002 ER PT J AU SPINA, EF MCGINLEY, CB AF SPINA, EF MCGINLEY, CB TI CONSTANT-TEMPERATURE ANEMOMETRY IN HYPERSONIC FLOW - CRITICAL ISSUES AND SAMPLE RESULTS SO EXPERIMENTS IN FLUIDS LA English DT Article AB The critical issues are examined in the application of constant-temperature hot-wire anemometry to hypersonic boundary layers. While continuous turbulence measurements are more challenging to make in hypersonic flows, it is shown Re here that the difficulties can be overcome for a wide range of flow conditions. An extensive review of the literature reveals that many of the heat transfer complexities associated with hypersonic anemometry have already been resolved. Frequency-response tests, calibration results and boundary-layer measurements in hypersonic flow are also presented. A hot-wire frequency response of about 500 kHz was obtained in a Mach 11 flow, and the resulting boundary-layer spectra are smooth and repeatable. C1 NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,HAMPTON,VA 23681. RP SPINA, EF (reprint author), SYRACUSE UNIV,SYRACUSE CTR HYPERSON,SYRACUSE,NY 13244, USA. NR 25 TC 18 Z9 20 U1 1 U2 4 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD OCT PY 1994 VL 17 IS 6 BP 365 EP 374 DI 10.1007/BF01877036 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA PR681 UT WOS:A1994PR68100001 ER PT J AU RAMAN, G RICE, EJ RESHOTKO, E AF RAMAN, G RICE, EJ RESHOTKO, E TI MODE SPECTRA OF NATURAL DISTURBANCES IN A CIRCULAR JET AND THE EFFECT OF ACOUSTIC FORCING SO EXPERIMENTS IN FLUIDS LA English DT Article ID AXISYMMETRIC JET; TURBULENT JET; LAYER; EVOLUTION; STABILITY; NOZZLE; FLOW AB A modal spectrum technique was used to study coherent instability modes (both axisymmetric and azimuthal) triggered by naturally occurring disturbances in a circular jet. This technique was applied to a high Reynolds number (400,000) jet for both untripped (transitional) and tripped (turbulent) nozzle exit boundary layers, with both cases having a core turbulence level of 0.15%. The region up to the end of the potential core was dominated by the axisymmetric mode, with the azimuthal modes dominating further downstream. The growth of the azimuthal modes was observed closer to the nozzle exit for the jet with a transitional boundary layer. Whether for locally parallel flow or slowly diverging flow, even at low levels of acoustic forcing, the inviscid linear theory is seen to be inadequate for predicting the amplitude of the forced mode. In contrast, the energy integral approach reasonably predicts the evolution of the forced mode. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. RP RAMAN, G (reprint author), NYMA INC,NASA,LEWIS RES CTR GRP,EXPTL FLUID DYNAM SECT,BROOKPARK,OH 44142, USA. NR 34 TC 20 Z9 21 U1 0 U2 2 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD OCT PY 1994 VL 17 IS 6 BP 415 EP 426 DI 10.1007/BF01877044 PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA PR681 UT WOS:A1994PR68100007 ER PT J AU MULLIN, KD HOGGARD, W RODEN, CL LOHOEFENER, RR ROGERS, CM TAGGART, B AF MULLIN, KD HOGGARD, W RODEN, CL LOHOEFENER, RR ROGERS, CM TAGGART, B TI CETACEANS ON THE UPPER CONTINENTAL-SLOPE IN THE NORTH-CENTRAL GULF-OF-MEXICO SO FISHERY BULLETIN LA English DT Article ID UNITED-STATES; WHALE; HABITATS; STENELLA; DOLPHINS; RECORDS; SHELF AB Little is known about cetaceans in the oceanic Gulf of Mexico (depths >200 m). From July 1989 to June 1990, we conducted aerial surveys in the oceanic north-central Gulf (long. 87.5 degrees W-90.5 degrees W) with the following objectives: 1) to determine which cetacean species were present; 2) to document temporal and spatial distribution for each species; and 3) to estimate relative abundance for each species. We surveyed a total of 20,593 transect km and sighted at least 18 species. Of 278 identified herds (6,084 animals), 94% of the herds and 98% of the animals represented seven species or species groups: Risso's dolphin, Grampus griseus (22% of the herds, 13% of the animals); sperm whale, Physeter macrocephalus (16%, 1%); bottlenose dolphin, Tursiops truncatus 14%, 7%); Atlantic spotted dolphin, stenella frontalis (13%, 15%); pygmy sperm whale, Kogia breviceps, and dwarf sperm whale, Kogia simus (12%, 1%); striped dolphin, Stenella coeruleoalba, spinner dolphin, S. longirostris, and clymene dolphin, S. clymene (9%, 34%); and pantropical spotted dolphin, S. attenuata (8%, 27%). Each of these species or species groups was sighted throughout the area surveyed in at least three seasons. Mean water depths of bottlenose dolphin and Atlantic spotted dolphin sightings were less than 400 m; mean water depths of Risso's dolphins and pygmy and dwarf sperm whales were between 400-600 m; and mean water depths of striped, spinner, and clymene dolphins, sperm whales, and pantropical spotted dolphins were greater than 700 m. Mean herd sizes varied by species and species groups and ranged from 1.9 animals for pygmy and dwarf sperm whales to 87.8 animals for striped, spinner, and clymene dolphins. C1 NOAA,CTR AIRCRAFT OPERAT,MACDILL AFB,FL 33608. RP MULLIN, KD (reprint author), NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,POB DRAWER 1207,PASCAGOULA,MS 39568, USA. NR 40 TC 25 Z9 28 U1 1 U2 8 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 1994 VL 92 IS 4 BP 773 EP 786 PG 14 WC Fisheries SC Fisheries GA PL097 UT WOS:A1994PL09700010 ER PT J AU WILSON, CD SEKI, MP AF WILSON, CD SEKI, MP TI BIOLOGY AND POPULATION CHARACTERISTICS OF SQUALUS-MITSUKURII FROM A SEAMOUNT IN THE CENTRAL NORTH PACIFIC-OCEAN SO FISHERY BULLETIN LA English DT Article ID BRITISH-COLUMBIA WATERS; SPINY DOGFISH; ACANTHIAS; AGE; INTERFACE; SPURDOG; COAST; FOOD AB Little information exists on the biology of the demersal shark, Squalus mitsukurii. Recently, large numbers of this species were taken incidentally during research surveys conducted at Southeast Hancock Seamount in the central North Pacific Ocean. The information collected during 1985 to 1988 from these surveys is used to describe the life history, depth distribution, and biology of S. mitsukurii. Bathymetric distributional patterns of female and male S. mitsukurii differed slightly, although bottom longline catches revealed a depth distribution extending from the summit (260 m) to 740 m for both sexes. Males generally were found deeper than females. In addition, the size of males generally increased with depth whereas no apparent trend was observed for females. Reproductive parameters for both sexes are presented. Males tended to reach maturity at smaller sizes than did females. Gravid females had broods of up to six uterine embryos. Length of young close to parturition was 21-26 cm. Tentative estimates of age and growth were made from dorsal spine increment counts. Maximum ages were 27 years for females and 18 years for males. Females exhibited more rapid growth than males after about age 9. The diet of S. mitsukurii included both benthic and mesopelagic prey. Fishes, cephalopods, and crustaceans were the major components of the diet. Comparison of the biological characteristics suggest that this species is probably typical of other slow-growing, low fecund members of the genus Squalus. The 50% decline in catch rates observed during this study suggests that the number of S. mitsukurii on the seamount declined dramatically, possibly as a result of overfishing. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. RP WILSON, CD (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,7600 SAND POINT WAY NE,SEATTLE,WA 98115, USA. NR 42 TC 28 Z9 30 U1 2 U2 10 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 1994 VL 92 IS 4 BP 851 EP 864 PG 14 WC Fisheries SC Fisheries GA PL097 UT WOS:A1994PL09700015 ER PT J AU RAO, MN GARRISON, DH BOGARD, DD REEDY, RC AF RAO, MN GARRISON, DH BOGARD, DD REEDY, RC TI DETERMINATION OF THE FLUX-DISTRIBUTION AND ENERGY-DISTRIBUTION OF ENERGETIC SOLAR PROTONS IN THE PAST 2-MYR USING LUNAR ROCK-68815 SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID PARTICLES AB Cosmogenic Ne-21, Ne-22, Ar-38, and He-3 produced by nuclear interactions of energetic (>10 MeV) solar protons were determined in 11 depth samples of lunar rock 68815. Concentrations of these proton-produced, SCR nuclides smoothly decrease from the rock surface down to 4.3 cm, where a galactic cosmic ray (GCR) component dominates. The cosmogenic Ne-21/Ne-22 isotopic ratio shows a systematic change with depth, from the characteristic GCR value of 0.79 at 4.9 cm to a mixed SCR + GCR ratio of 0.66 near the surface. The surface exposure age for 68815 calculated from both SCR and GCR components for Ne-21, Ne-22, and Ar-38 agrees with the reported Kr-81-Kr exposure age of 2.04 Myr. Theoretical SCR + GCR depth profiles were calculated from cross-section data for different assumed spectra of energetic solar protons (R(0), or rigidity, values of 50-125 MV) and for different rock surface erosion rates (0-3 mm/Myr). These theoretical SCR profiles were added to GCR profiles and statistically compared with measured data by minimizing the standard deviation of the least squares statistical fit and by requiring the GCR component in the 4.3 cm sample to be >90% of the measured concentration. SCR Ne-21, Ne-22, and Ar-38 give the following results for energetic solar protons over the last 2 Myr. For a preferred erosion rate of 1 mm/Myr and R(0) of 80-90 MV, J(4 pi, E > 10 MeV) similar or equal to 58-73 p/cm(2)/s; for the broader possible range of R(0) values of 70-100 MV, J(4 pi, E, 10 MeV) similar or equal to 49-92 p/cm(2)/s. These proton fluxes increase by similar to 12 and similar to 24% for erosion rates of 2 mm/Myr and 3 mm/Myr, respectively. These same data analysis techniques were also applied to literature depth profiles for SCR radionuclides in rock 68815. Al-26 and Mn-53 give proton fluxes comparable to those obtained from neon and argon at R(0) values of 70-85 MV, but give somewhat higher J values at larger values of R(0). Proton fluxes characterized by Kr-81 and C-14 tend to be higher compared to the other nuclides. The most likely reason for different J values determined from different SCR nuclides is errors in cross section data, although measurement errors and temporal variations in J cannot be excluded. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP RAO, MN (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 35 TC 31 Z9 31 U1 0 U2 0 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 1994 VL 58 IS 19 BP 4231 EP 4245 DI 10.1016/0016-7037(94)90275-5 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PK700 UT WOS:A1994PK70000016 ER PT J AU FOMENKOVA, MN CHANG, S MUKHIN, LM AF FOMENKOVA, MN CHANG, S MUKHIN, LM TI CARBONACEOUS COMPONENTS IN THE COMET HALLEY DUST SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID POROUS CHONDRITIC MICROMETEORITES; MAJOR ELEMENT COMPOSITION; INTERPLANETARY DUST; MURCHISON METEORITE; INTERSTELLAR GRAINS; AMORPHOUS-CARBON; SILICON-CARBIDE; ORGANIC-MATTER; PARTICLES; HYDROCARBONS AB Cometary grains containing large amounts of carbon and/or organic matter (CHON) were discovered by in situ measurements of comet Halley dust composition during VEGA and GIOTTO flyby missions. In this paper, we report the classification of these cometary grains by means of cluster analysis, discuss the resulting compositional groups, and compare them with substances observed or hypothesized in meteorites, interplanetary dust particles, and the interstellar medium. Grains dominated by carbon and/or organic matter (CHON grains) represent approximately 22% of the total population of measured cometary dust particles. They usually contain a minor abundance of rock-forming elements as well. Grains having organic material are relatively more abundant in the vicinity of the nucleus than in the outer regions of the coma, which suggests decomposition of the organics in the coma environment. The majority of comet Halley organic particles are multicomponent mixtures of carbon phases and organic compounds. Possibly, the cometary CHON grains may be related to kerogen material of an interstellar origin in carbonaceous meterorites. Pure carbon grains, hydrocarbons and polymers of cyanopolyynes, and multi-carbon monoxides are present in cometary dust as compositionally simple and distinctive components among a variety of others. There is no clear evidence of significant presence of pure formaldehyde or HCN polymers in Halley dust particles. The diversity of types of cometary organic compounds is consistent with the interstellar dust model of comets and probably reflects differences in composition of precursor dust. Preservation of this heterogeneity among submicron particles suggests the gentle formation of cometary nucleus by aggregation of interstellar dust in the protosolar nebula without complete mixing or chemical homogenization at the submicron level. C1 ACAD SCI,INST SPACE RES,MOSCOW,RUSSIA. RUSSIAN EMBASSY,WASHINGTON,DC 20036. RP FOMENKOVA, MN (reprint author), NASA,AMES RES CTR,MS 239-4,MOFFETT FIELD,CA 94035, USA. NR 87 TC 61 Z9 61 U1 1 U2 10 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 1994 VL 58 IS 20 BP 4503 EP 4512 DI 10.1016/0016-7037(94)90351-4 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PP043 UT WOS:A1994PP04300020 PM 11539150 ER PT J AU SCHULTZ, PH KOEBERL, C BUNCH, T GRANT, J COLLINS, W AF SCHULTZ, PH KOEBERL, C BUNCH, T GRANT, J COLLINS, W TI GROUND TRUTH FOR OBLIQUE IMPACT PROCESSES - NEW INSIGHT FROM THE RIO-CUARTO, ARGENTINA, CRATER FIELD SO GEOLOGY LA English DT Article AB New evidence for an impact origin of oblong rimmed depressions near Rio Cuarto, Cordoba Province, Argentina, includes shocked silicate phases (e.g., dialectic glass), thermal decomposition of high-temperature mineral clasts (e.g., baddeleyite from zircon), rapid quenching, very low water contents (less-than-or-equal-to 0.1 wt%), and generation of identical glasses in hypervelocity laboratory impact experiments. The results indicate that glasses with a wide range in major element concentrations can form from a single target type in a relatively small impact event. Impact glasses with the greatest volatile loss typically exhibit the greatest meteoritic contamination (as defined by Cr, Ni, and Ir abundances). The different impact glass types and the different degrees of impactor contamination are proposed to reflect proximity to the projectile-target interface during shallow penetration in an oblique impact, consistent with laboratory simulations and planetary analogues. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV VIENNA,INST GEOCHEM,A-1010 VIENNA,AUSTRIA. RP SCHULTZ, PH (reprint author), BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912, USA. NR 22 TC 24 Z9 24 U1 0 U2 2 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD OCT PY 1994 VL 22 IS 10 BP 889 EP 892 DI 10.1130/0091-7613(1994)022<0889:GTFOIP>2.3.CO;2 PG 4 WC Geology SC Geology GA PJ581 UT WOS:A1994PJ58100006 ER PT J AU LANG, HR AF LANG, HR TI WILSHIRE FAULT - EARTHQUAKES IN HOLLYWOOD - COMMENT SO GEOLOGY LA English DT Note RP LANG, HR (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 3 TC 0 Z9 0 U1 0 U2 1 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0091-7613 J9 GEOLOGY JI Geology PD OCT PY 1994 VL 22 IS 10 BP 959 EP 959 DI 10.1130/0091-7613(1994)022<0959:WFEIHC>2.3.CO;2 PG 1 WC Geology SC Geology GA PJ581 UT WOS:A1994PJ58100026 ER PT J AU DEMETS, C GORDON, RG ARGUS, DF STEIN, S AF DEMETS, C GORDON, RG ARGUS, DF STEIN, S TI EFFECT OF RECENT REVISIONS TO THE GEOMAGNETIC REVERSAL TIME-SCALE ON ESTIMATES OF CURRENT PLATE MOTIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BASE-LINE INTERFEROMETRY; ASTRONOMICAL CALIBRATION; POLARITY; DEFORMATION; TECTONICS; TIMESCALE; RATES AB Recent revisions to the geomagnetic time scale indicate that global plate motion model NUVEL-1 should be modified for comparison with other rates of motion including those estimated from space geodetic measurements. The optimal recalibration, which is a compromise among slightly different calibrations appropriate for slow, medium, and fast rates of seafloor spreading, is to multiply NUVEL-1 angular velocities by a constant, alpha, of 0.9562. We refer to this simply recalibrated plate motion model as NUVEL-1A, and give correspondingly revised tables of angular velocities and uncertainties. Published work indicates that space geodetic rates are slower on average than those calculated from NUVEL-1 by 6+/-1%. This average discrepancy is reduced to less than 2% when space geodetic rates are instead compared with NUVEL-1A. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NORTHWESTERN UNIV,DEPT GEOL SCI,EVANSTON,IL 60208. RP DEMETS, C (reprint author), UNIV WISCONSIN,DEPT GEOL & GEOPHYS,MADISON,WI 53706, USA. RI Argus, Donald/F-7704-2011; Wright, Dawn/A-4518-2011 OI Wright, Dawn/0000-0002-2997-7611 NR 20 TC 2212 Z9 2282 U1 3 U2 83 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 1994 VL 21 IS 20 BP 2191 EP 2194 DI 10.1029/94GL02118 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PK063 UT WOS:A1994PK06300003 ER PT J AU TSELIOUDIS, G ROSSOW, WB AF TSELIOUDIS, G ROSSOW, WB TI GLOBAL, MULTIYEAR VARIATIONS OF OPTICAL-THICKNESS WITH TEMPERATURE IN LOW AND CIRRUS CLOUDS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FEEDBACK; CLIMATE AB The International Satellite Cloud Climatology Project (ISCCP) dataset is used to correlate variations of cloud optical thick ness and cloud temperature in today's atmosphere. The analysis focuses on low and cirrus clouds. Cold low clouds show increases in cloud optical thickness with temperature consistent with adiabatic behavior, while warm low clouds primarily show decreases in cloud optical thickness with temperature. An exception are subtropical low clouds which show a tendency for increases in optical thickness with temperature, particularly during El Nino years. High and middle latitude cirrus clouds show increases in optical thickness with temperature. In subtropical and tropical latitudes, cirrus cloud optical thicknesses show a complicated behavior that could be related to changes in the dynamical regime in which the clouds are formed. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP TSELIOUDIS, G (reprint author), COLUMBIA UNIV,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Rossow, William/F-3138-2015 NR 11 TC 22 Z9 23 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 1 PY 1994 VL 21 IS 20 BP 2211 EP 2214 DI 10.1029/94GL02004 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PK063 UT WOS:A1994PK06300008 ER PT J AU GUNSON, MR ABRAMS, MC LOWES, LL MAHIEU, E ZANDER, R RINSLAND, CP KO, MKW SZE, ND WEISENSTEIN, DK AF GUNSON, MR ABRAMS, MC LOWES, LL MAHIEU, E ZANDER, R RINSLAND, CP KO, MKW SZE, ND WEISENSTEIN, DK TI INCREASE IN LEVELS OF STRATOSPHERIC CHLORINE AND FLUORINE LOADING BETWEEN 1985 AND 1992 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MOLECULE SPECTROSCOPY EXPERIMENT; HYDROGEN-CHLORIDE; JUNGFRAUJOCH STATION; HCL; SPACELAB-3; COLUMN; OZONE; GASES AB Mixing ratios of 3.44 ppbv (parts per billion by volume) and 1.23 ppbv for HCl and HF above 50 km, surrogates for total chlorine and fluorine, have been measured by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment on a March 1992 flight of the Space Shuttle. Compared to the measured values obtained on a 1985 flight, these correspond to a 37% and 62% increase for HCl and HF, respectively. The derived trend in HCl (similar to 0.13 ppbv per year) is in good agreement with the model-predicted increase in chlorine loading of 0.13 ppbv per year [Prather and Watson. 1990], and with the measured trends in HCl total column abundance from reported ground-based observations. The main source of this change can be attributed to the release of man-made chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). This new value for HCl represents an upper limit to the inorganic chlorine concentration in the stratosphere available for participation in photochemical processes which destroy ozone. C1 UNIV LIEGE,INST ASTROPHYS,LIEGE,BELGIUM. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. ATMOSPHER & ENVIRONM RES INC,CAMBRIDGE,MA 02139. RP GUNSON, MR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Ko, Malcolm/D-5898-2015 NR 18 TC 35 Z9 35 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 1994 VL 21 IS 20 BP 2223 EP 2226 DI 10.1029/94GL02077 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PK063 UT WOS:A1994PK06300011 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 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID KELVIN-HELMHOLTZ INSTABILITY; SURFACE-WAVES; SOLAR CORONA AB The first nonlinear study of the instability of the resonant absorption is presented in this paper. The nonlinear evolution of the resonant absorption of Alfven waves in an inhomogeneous plasma is studied via solution of the time-dependent 3-D, low-beta, resistive MHD equations. Highly sheared velocities that are subject to the Kelvin-Helmholtz like instability are found at the narrow dissipation layers. Three dimensional Kelvin-Helmholtz like vortices appear at and near the dissipation layers and propagate along the slab of plasma. The narrow resonant heating layers are deformed by the self-consistent shear flow. In the solar active regions where the resonant absorption of Alfven waves is believed to occur the instability may lead to turbulent enhancement of the dissipation parameters and account for the observed turbulent velocities inferred from the non-thermal broadening of x-ray and EUV emission lines. C1 SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78228. RP OFMAN, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6821,GREENBELT,MD 20771, USA. NR 18 TC 56 Z9 56 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 1994 VL 21 IS 20 BP 2259 EP 2262 DI 10.1029/94GL01416 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PK063 UT WOS:A1994PK06300020 ER PT J AU WEISSMAN, PR STERN, SA AF WEISSMAN, PR STERN, SA TI THE IMPACTOR FLUX IN THE PLUTO-CHARON SYSTEM SO ICARUS LA English DT Article ID SHORT-PERIOD COMETS; SOLAR-SYSTEM; OORT CLOUD; ORIGIN; CONSTRAINTS AB Current impact rates of comets on Pluto and Charon are estimated. It is shown that the dominant sources of impactors are comets from the Kuiper belt and the inner Oort cloud, each of whose perihelion distributions extends across Pluto's orbit. In contrast, long-period comets from the outer Oort cloud are a negligible source of impactors. The total predicted number of craters is not sufficient to saturate the surface areas of either Pluto or Charon over the age of the Solar System. However, heavy cratering may have occurred early in the Solar System's history during clearing of planetesimals from the outer planets' zone. (C) 1994 Academic Press, Inc. C1 SW RES INST,DEPT SPACE SCI,SAN ANTONIO,TX 78238. RP WEISSMAN, PR (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 41 TC 14 Z9 14 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1994 VL 111 IS 2 BP 378 EP 386 DI 10.1006/icar.1994.1151 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PT606 UT WOS:A1994PT60600007 ER PT J AU SCHUBERT, G LIMONADI, D ANDERSON, JD CAMPBELL, JK GIAMPIERI, G AF SCHUBERT, G LIMONADI, D ANDERSON, JD CAMPBELL, JK GIAMPIERI, G TI GRAVITATIONAL COEFFICIENTS AND INTERNAL STRUCTURES OF THE ICY GALILEAN SATELLITES - AN ASSESSMENT OF THE GALILEO ORBITER MISSION SO ICARUS LA English DT Article ID GANYMEDE; MODELS AB Simulated radio tracking data from one flyby of Europa, two flybys of Ganymede, and two flybys of Callisto by the Galileo Orbiter yield estimates of the standard errors in the gravitational coefficient J(2) of 44, 8.5, and 12 (in units of 10(-6)) for Europa, Ganymede, and Callisto, respectively; errors in C-22 (in units of 10(-6)) are 12, 1.7, and 2.1. These errors are sufficiently small that the values of J(2) and C-22 to be measured by Galileo should suffice to determine if the ice and rock in the satellite interiors are uniformly mixed or separated, so long as the bodies are in hydrostatic equilibrium. (C) 1994 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SCHUBERT, G (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024, USA. NR 10 TC 23 Z9 23 U1 2 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1994 VL 111 IS 2 BP 433 EP 440 DI 10.1006/icar.1994.1154 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PT606 UT WOS:A1994PT60600010 ER PT J AU VILAS, F AF VILAS, F TI A CHEAPER, FASTER, BETTER WAY TO DETECT WATER OF HYDRATION ON SOLAR-SYSTEM BODIES SO ICARUS LA English DT Article ID CCD REFLECTANCE SPECTRA; 8-COLOR ASTEROID SURVEY; LOW-ALBEDO ASTEROIDS; C-CLASS ASTEROIDS; OUTER-BELT; CARBONACEOUS CHONDRITES; AQUEOUS ALTERATION; PHOTOMETRY; SPECTROPHOTOMETRY; LAPETUS AB The 3.0-mu m water of hydration absorption feature observed in the IR photometry of many low-albedo and some medium-albedo asteroids strongly correlates with the 0.7-mu m Fe2+ --> Fe3+ oxidized iron absorption feature observed in narrowband spectrophotometry of these asteroids. Using this relationship, an empirical algorithm for predicting the presence of water of hydration in the surface material of a Solar System body using photometry obtained through the Eight-Color Asteroid Survey v (0.550 mu m), w (0.701 mu m), and x (0.853 mu m) filters was developed and applied to the ECAS photometry of asteroids and outer planet satellites. The percentage of objects in low-albedo, outer main-belt asteroid classes that test positively for water of hydration increases from P --> B --> C --> G class and correlates linearly with the increasing mean albedos of those objects testing positively. The aqueous alteration sequence in the Solar System thus ranges from P-class asteroids, which represent the least-altered objects created at temperatures attained at the onset of aqueous alteration, to G-class asteroids, which represent the upper range of the alteration sequence. The medium-albedo M class asteroids do not test positively in large number using this algorithm. These objects could represent a mixture of metals with phyllosilicates that have been significantly altered to the extent that iron has been leached out of the phyllosilicates and sequestered in opaque phases such as magnetite or iron sulfides. Spatial variation in the presence of water of hydration across the surface of some asteroids is suggested in the variability of the water of hydration test for observations of many asteroids on different nights, although an effort to correlate variation with rotational period is unsuccessful due to the small sample of eligible asteroids. Aqueously altered asteroids dominate the Solar System population between heliocentric distances of 2.6 to 3.5 AU, bracketing the Solar System region where the aqueous alteration mechanism operated most strongly. One jovian satellite, J VI Himalia, and one saturnian satellite. Phoebe, tested positively for water of hydration, supporting the hypothesis that these may be captured C-class asteroids from a postaccretional dispersion. The proposed testing technique could be applied to an Earth-based survey of asteroids or a space-probe study of an asteroid's surface characteristics in order to identify a potential water source. (C) 1994 Academic Press, Inc. RP VILAS, F (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN3,HOUSTON,TX 77058, USA. NR 43 TC 91 Z9 91 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1994 VL 111 IS 2 BP 456 EP 467 DI 10.1006/icar.1994.1156 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PT606 UT WOS:A1994PT60600012 ER PT J AU DEPATER, I PALMER, P MITCHELL, DL OSTRO, SJ YEOMANS, DK SNYDER, LE AF DEPATER, I PALMER, P MITCHELL, DL OSTRO, SJ YEOMANS, DK SNYDER, LE TI RADAR APERTURE SYNTHESIS OBSERVATIONS OF ASTEROIDS SO ICARUS LA English DT Article ID ARAKI-ALCOCK 1983D; MERCURY; IMAGES; ICE AB We report results of Goldstone-VLA, radar aperture-synthesis observations of the mainbelt asteroids 324 Bamberga and 7 Iris and the near-Earth asteroids 1991 EE and 4179 Toutatis. Simultaneous resolution of echoes in both angle and Doppler frequency provide new constraints on the mainbelt asteroids' pole directions: Bamberga's spin vector is within 40 degrees of the south ecliptic pole, and the twofold ambiguity in Iris' pole direction (P. Magnusson, 1989, in Asteroids II, pp. 1180-1190) is resolved in favor of the ecliptic coordinates lambda = 15 degrees, beta = +25 degrees. For Bamberga, monostatic and bistatic radar echoes and VLA thermal-emission measurements, also reported here, are consistent with radiometric estimates of Bamberga's size and with the hypothesis that the asteroid is overlain by a regolith having a porosity of similar to 50%. Our near-Earth asteroid measurements required the development of new on-line VLA software that allows imaging of objects that are in the telescope's ''near field.'' This software has been successfully tested on Toutatis at a distance of 0.06 AU and will be essential for VLA observations of Earth-approaching comets. (C) 1994 Academic Press, Inc. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801. RP DEPATER, I (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,601 CAMPBELL HALL,BERKELEY,CA 94720, USA. NR 29 TC 16 Z9 16 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 1994 VL 111 IS 2 BP 489 EP 502 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PT606 UT WOS:A1994PT60600015 ER PT J AU PAIN, B FOSSUM, ER AF PAIN, B FOSSUM, ER TI A CURRENT MEMORY CELL WITH SWITCH FEEDTHROUGH REDUCTION BY ERROR FEEDBACK SO IEEE JOURNAL OF SOLID-STATE CIRCUITS LA English DT Note AB A new switch feedthrough suppressing current memory cell, capable of accurately memorizing low current levels is presented. The scheme operates by feeding back a fraction of the error current to the storage node whose voltage is adjusted so that the error is reduced to zero. Using the feedback compensation scheme, absolute current error of less than 0.1% was achieved even at ultra-low current levels of 10 nA. The negative feedback circuit consumes negligibly low power and can be laid in a very small area. With this scheme, memory accuracy is traded for error correction speed, a feature common to all feedback-based switch feedthrough reduction schemes. The feedback compensated current memory cell can be used for low-power high-background infrared focal-plane readout electronics featuring in-pixel background suppression. RP PAIN, B (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 9 TC 4 Z9 4 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 0018-9200 J9 IEEE J SOLID-ST CIRC JI IEEE J. Solid-State Circuit PD OCT PY 1994 VL 29 IS 10 BP 1288 EP 1290 DI 10.1109/4.315216 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA PK224 UT WOS:A1994PK22400019 ER PT J AU LEE, TH CHI, CY EAST, JR REBEIZ, GM HADDAD, GI AF LEE, TH CHI, CY EAST, JR REBEIZ, GM HADDAD, GI TI A NOVEL BIASED ANTI-PARALLEL SCHOTTKY DIODE STRUCTURE FOR SUBHARMONIC MIXING SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article AB Subharmonically pumped mixers using zero-biased anti-parallel Schottky diode pairs produce good results, but require a larger LO power than biased Schottky diodes. Presented here is a novel planar-diode anti-parallel pair that allows independent biasing of the two diodes. This diode pair is integrated into a quasi-optical wideband receiver and the RF measurements on a 1.2-mum anode diameter pair show a reduced LO power requirement at 180 GHz by a factor of 2 to 3 with a similar DSB conversion loss and noise temperature (9.7 dB and 1850-degrees-K) to an unbiased Schottky diode pair. This structure has potential for applications at submillimeter-wave frequencies where a large amount of LO power is not easily available. RP LEE, TH (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 5 Z9 5 U1 2 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD OCT PY 1994 VL 4 IS 10 BP 341 EP 343 DI 10.1109/75.324710 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA PK412 UT WOS:A1994PK41200009 ER PT J AU CHEN, OTC SHEU, BJ FANG, WC AF CHEN, OTC SHEU, BJ FANG, WC TI IMAGE COMPRESSION USING SELF-ORGANIZATION NETWORKS SO IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY LA English DT Article DE IMAGE PROCESSING; VECTOR QUANTIZATION; NEURAL NETWORK ID ADAPTIVE PATTERN-CLASSIFICATION; VECTOR QUANTIZATION AB A self-organization neural network architecture is used to implement vector quantization for image compression. A modified self-organization algorithm, which is based on the frequency-sensitive cost function and centroid learning rule, is utilized to construct the codebooks. Performances of this frequency-sensitive self-organization network and a conventional algorithm for vector quantization are compared. The proposed method is quite efficient and can achieve near-optimal results. Good adaptivity for different statistics of source data can also be achieved. C1 CALTECH,JET PROPULS LAB,PASADENA,CA 91109. RP CHEN, OTC (reprint author), UNIV SO CALIF,INST SIGNAL & IMAGE PROC,DEPT ELECT ENGN,LOS ANGELES,CA 90089, USA. NR 21 TC 28 Z9 28 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 1051-8215 J9 IEEE T CIRC SYST VID JI IEEE Trans. Circuits Syst. Video Technol. PD OCT PY 1994 VL 4 IS 5 BP 480 EP 489 DI 10.1109/76.322995 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA PW319 UT WOS:A1994PW31900003 ER PT J AU ELEFTHERIADES, GV OMAR, AS KATEHI, LPB REBEIZ, GM AF ELEFTHERIADES, GV OMAR, AS KATEHI, LPB REBEIZ, GM TI SOME IMPORTANT PROPERTIES OF WAVE-GUIDE JUNCTION GENERALIZED SCATTERING MATRICES IN THE CONTEXT OF THE MODE MATCHING TECHNIQUE SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID RECTANGULAR WAVEGUIDES; WAVE-GUIDE; DISCONTINUITIES; TRANSFORMERS; COMPLEX AB Some important properties for the generalized scattering matrix [S] of waveguide step discontinuities, in the context of the mode matching technique, are derived by considering the conservation of the complex power and self reaction across the discontinuities. Apart from their theoretical significance, these properties are useful for the numerical verification of the mode matching technique when designing waveguide circuits. The properties are shown to apply in the general case of junctions between lossless inhomogeneously filled waveguides, and they are proven to remain valid irrespective of the number of modes retained in the field expansions. During the process of deriving these properties, the mode matching technique for a waveguide step discontinuity is revisited and some subtle theoretical issues are resolved. In this framework, the selection of the appropriate testing modes for enforcing the field continuity conditions across the discontinuity is rigorously justified. In addition, two distinct mode matching formulations corresponding to the two possible orthogonality relations among the eigenmodes of lossless waveguides are proven to be equivalent. Finally, it is shown that the correct application of the field boundary conditions across the step discontinuity implies requirements on the number of modes used to represent the fields, in each waveguide, which are compatible with the relative convergence criterion. C1 TECH UNIV HAMBURG,ARBEITSBEREICH HOCHFREQUENZTECH,D-21071 HAMBURG,GERMANY. RP ELEFTHERIADES, GV (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 19 TC 67 Z9 70 U1 1 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD OCT PY 1994 VL 42 IS 10 BP 1896 EP 1903 DI 10.1109/22.320771 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA PL265 UT WOS:A1994PL26500009 ER PT J AU ONEILL, PM BADHWAR, GD AF ONEILL, PM BADHWAR, GD TI SINGLE EVENT UPSETS FOR SPACE-SHUTTLE FLIGHTS OF NEW GENERAL-PURPOSE COMPUTER MEMORY DEVICES SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB The replacement of magnetic core with a well characterized semiconductor memory in the Space Shuttle orbiter general purpose computers (GPC's) has provided a wealth of on-orbit radiation effects data since 1991. The fault tolerant GPC's detect, correct, and downlink memory upset status and orbiter position information every few seconds, giving us the ability to correlate 1400 upsets to date with altitude, geomagnetic latitude, and solar conditions. The predicted upset rate was computed by a modified path-length distribution method. The modification accounts for the Weibull distribution cross-section (rather than a single upset threshold) and the device sensitive volume thickness. Device thickness was estimated by the method normally used to account for edge effects at the upset cross-section discontinuity that occurs at ion changes. A galactic cosmic ray environment model accurately models the average particle flux for each mission. The predicted and observed upset rates were found to be in good agreement for sensitive volume thicknesses consistent with the device's fabrication technology. RP ONEILL, PM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 26 TC 18 Z9 18 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 1994 VL 41 IS 5 BP 1755 EP 1764 DI 10.1109/23.317386 PG 10 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PH823 UT WOS:A1994PH82300006 ER PT J AU WEISER, ES BAUCOM, RM AF WEISER, ES BAUCOM, RM TI MOLDING OF COMPLEX COMPOSITE PARTS UTILIZING MODIFIED SILICONE-RUBBER TOOLING SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB Control of the pressure at the core temperature of polymer matrix composites is critical to the fabrication of high quality composite structures. Cast silicone rubber has been utilized as a tooling aid to apply pressure to complex composite parts during cure. Due to the high expansion rates of most silicone rubber systems in the ''as received'' form if is very difficult to achieve proper pressure application levels at the cure temperature. This study focused on selective addition of silica powder to Aircast 3700 castable silicone rubber. The addition of 5% silica reduced the expansion rate by a factor of 10 compared to ''as received'' Aircast 3700. This allows very accurate selected pressure levels to be applied at composite core temperatures. Governing formulas and experimental test results from silica modified Aircast 3700 castable silicone robber are presented herein. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP WEISER, ES (reprint author), GEORGIA INST TECHNOL,ATLANTA,GA, USA. NR 5 TC 4 Z9 4 U1 0 U2 2 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 1994 VL 26 IS 1 BP 2 EP 8 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA PJ902 UT WOS:A1994PJ90200001 ER PT J AU HASKO, G DEXTER, HB LOOS, A KRANBUEHL, D AF HASKO, G DEXTER, HB LOOS, A KRANBUEHL, D TI APPLICATION OF SCIENCE-BASED RTM FOR FABRICATING PRIMARY AIRCRAFT STRUCTURAL ELEMENTS SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB Resin Transfer Molding (RTM) technology is being developed by the NASA Langley Research Center under the Advanced Composites Technology (ACT) program as a cost-effective method for fabricating primary aircraft structures. Challenges lie in successfully infiltrating large, skin/stiffener textile preforms using hot, reacting resins. RTM variations include resin film infusion (RFI) and pressure injection (PI). This paper describes the program which includes modeling, dielectric sensing, model verification, and applications. Preform compaction and permeability measurements are described Resins are characterized using differential scanning calorimetry (DSC) and rheometry Darcy's law continuity equations, and finite element techniques are used to model the flow. Models are verified with data taken by conventional temperature and pressure sensors, and by dielectric sensors for flow front position, viscosity, and eye monitoring. C1 VIRGINIA POLYTECH INST & STATE UNIV,BLACKSBURG,VA. COLL WILLIAM & MARY,WILLIAMSBURG,VA. RP HASKO, G (reprint author), LOCKHEED ENGN & SCI CO,NASA,LANGLEY RES CTR,HAMPTON,VA, USA. NR 6 TC 6 Z9 6 U1 0 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 1994 VL 26 IS 1 BP 9 EP 15 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA PJ902 UT WOS:A1994PJ90200002 ER PT J AU BOWLES, KJ JAYNE, D LEONHARDT, TA BORS, D AF BOWLES, KJ JAYNE, D LEONHARDT, TA BORS, D TI THERMAL-STABILITY RELATIONSHIPS BETWEEN PMR-15 RESIN AND ITS COMPOSITES SO JOURNAL OF ADVANCED MATERIALS LA English DT Article ID THERMOOXIDATIVE STABILITY AB A study was conducted to investigate the relationships between the the thermo-oxidative stability of PMR-15 matrix resin and the stability of graphite-fiber reinforced composites that contain this resin as the matrix material. Three areas were investigated. The first was the effect of fiber/matrix interfacial bond strength on the isothermal aging weight loss of composites. By using type-A graphite fibers produced by Hercules, it was possible to study composites reinforced with fibers that were processed to receive different surface treatments. One of the fibers was untreated, a second fiber was treated by oxidation to enhance fiber/matrix bonding, and the third type of fiber was coated with an epoxy sizing. These treatments produced three significantly different interfacial bond strengths. The epoxy sizing on rite third fiber was quickly oxidized from the bare fiber surfaces at 288, 316, and 343 degrees C. The weight loss due to the removal of the sizing was constant at 1.5 percent. This initial weight loss was not observed in thermo-oxidative stability studies of composites. The PMR-15 matrix satisfactorily protected the reinforcement at all three temperatures. C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH. SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOKPARK,OH. CALSPAN CORP,CLEVELAND,OH. RP BOWLES, KJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH, USA. NR 9 TC 20 Z9 21 U1 0 U2 3 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 1994 VL 26 IS 1 BP 23 EP 32 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA PJ902 UT WOS:A1994PJ90200004 ER PT J AU SHEN, JY ABUSABA, EG MCGINLEY, WM SHARPE, L TAYLOR, LW AF SHEN, JY ABUSABA, EG MCGINLEY, WM SHARPE, L TAYLOR, LW TI CONTINUOUS DYNAMIC-MODEL FOR TAPERED BEAM-LIKE STRUCTURES SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB Distributed parameter modeling may offer a viable alternative to the finite-element approach for modeling large flexible space structures. In addition, the introduction of the transfer matrix method to the continuum modeling process provides a very useful tool to facilitate the distributed parameter model applied to more complex configurations. This paper proposes a piecewise continuous Timoshenko beam model, which was used for the dynamic analysis of a tapered beam-like structure. Instead of the arbitrarily assumed shape functions used in a finite-element analysis, the closed-form solution of the Timoshenko beam equation was used. Application of the transfer matrix method was used to relate all elements as a whole. Using the corresponding boundary conditions and compatibility equations, a characteristic equation for the global tapered beam was produced and natural frequencies derived. The results from this analysis were compared to those obtained from a conventional finite-element analysis. While comparable results are obtained, the piecewise continuous Timoshenko beam model significantly decreased the number of modal elements required. C1 NC A&T STATE UNIV,DEPT ARCHITECTURAL ENGN,GREENSBORO,NC. NC A&T STATE UNIV,DEPT MECH ENGN,GREENSBORO,NC. LANGLEY RES CTR,DIV SCI CONTROL & GUIDANCE,HAMPTON,VA 23665. RP SHEN, JY (reprint author), NC A&T STATE UNIV,SCH ENGN,CTR AEROSP RES,GREENSBORO,NC 27411, USA. NR 8 TC 5 Z9 5 U1 0 U2 0 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD OCT PY 1994 VL 7 IS 4 BP 435 EP 445 DI 10.1061/(ASCE)0893-1321(1994)7:4(435) PG 11 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA QU053 UT WOS:A1994QU05300006 ER PT J AU FRITSCHYELLE, JM CHARLES, JB JONES, MM BEIGHTOL, LA ECKBERG, DL AF FRITSCHYELLE, JM CHARLES, JB JONES, MM BEIGHTOL, LA ECKBERG, DL TI SPACEFLIGHT ALTERS AUTONOMIC REGULATION OF ARTERIAL-PRESSURE IN HUMANS SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE VALSALVA MANEUVER; BAROREFLEX; SYMPATHETIC; VAGAL; POWER SPECTRA ID BARORECEPTOR-CARDIAC REFLEX; BLOOD-PRESSURE; SPACE-FLIGHT; HEART-RATE; RESPONSES; REPRODUCIBILITY; NORADRENALINE; MODULATION; POSTURE AB Spaceflight is associated with decreased orthostatic tolerance after landing. Short-duration spaceflight (4-5 days) impairs one neural mechanism: the carotid baroreceptor-cardiac reflex. To understand the effects of longer-duration spaceflight on baroreflex function, we measured R-R interval power spectra, antecubital vein plasma catecholamine levels, carotid baroreceptor-cardiac reflex responses, responses to Valsalva maneuvers, and orthostatic tolerance in 16 astronauts before and after shuttle missions lasting 8-14 days. We found the following changes between preflight and landing day: I) orthostatic tolerance decreased; 2) R-R interval spectral power in the 0.05- to 0.15-Hz band increased; 3) plasma norepinephrine and epinephrine levels increased; 4) the slope, range, and operational point of the carotid baroreceptor cardiac reflex response decreased; and 5) blood pressure and heart rate responses to Valsalva maneuvers were altered. Autonomic changes persisted for several days after landing. These results provide further evidence of functionally relevant reductions in parasympathetic and increases in sympathetic influences on arterial pressure control after spaceflight. C1 KRUG LIFE SCI,HOUSTON,TX 77058. HUNTER HOLMES MCGUIRE DEPT VET AFFAIRS MED CTR,DEPT MED,RICHMOND,VA 23249. HUNTER HOLMES MCGUIRE DEPT VET AFFAIRS MED CTR,DEPT PHYSIOL,RICHMOND,VA 23249. VIRGINIA COMMONWEALTH UNIV MED COLL VIRGINIA,RICHMOND,VA 23249. RP FRITSCHYELLE, JM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,SD5,HOUSTON,TX 77058, USA. FU NHLBI NIH HHS [HL-22296] NR 35 TC 155 Z9 165 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 OCT PY 1994 VL 77 IS 4 BP 1776 EP 1783 PG 8 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA PL694 UT WOS:A1994PL69400030 PM 7836199 ER PT J AU CRANDALL, CG JOHNSON, JM CONVERTINO, VA RAVEN, PB ENGELKE, KA AF CRANDALL, CG JOHNSON, JM CONVERTINO, VA RAVEN, PB ENGELKE, KA TI ALTERED THERMOREGULATORY RESPONSES AFTER 15 DAYS OF HEAD-DOWN TILT SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE BED REST; SPACEFLIGHT; SKIN BLOOD FLOW; TEMPERATURE REGULATION; MICROGRAVITY ID EARLY CARDIOVASCULAR ADAPTATION; INDUCED LIMB VASODILATION; BED REST; MUSCLE VASOCONSTRICTION; ELECTROLYTE SHIFTS; ZERO GRAVITY; BLOOD-FLOW; FLUID; EXERCISE; BABOONS AB To determine whether extended exposure to a simulation of microgravity alters thermoregulatory reflex control of skin blood flow, six adult males (mean age 40 +/- 2 yr) were exposed to 15 days of 6 degrees head-down tilt (HDT). On an ambulatory control day before HDT exposure and on HDT day 15, the core temperature of each subject was increased by 0.5-1.0 degrees C by whole body heating with a water-perfused suit. Mean skin temperature, oral temperature (T-or), mean arterial pressure, and forearm blood flow were measured throughout the protocol. Forearm vascular conductance (FVC) was calculated from the ratio of forearm blood flow to mean arterial pressure. After HDT exposure, the T-or threshold at which reflex thermally induced increases in FVC began was elevated (36.87 +/- 0.06 to 37.00 +/- 0.09 degrees C; P = 0.043), whereas the slope of the T-or-FVC relationship after this threshold was reduced (13.7 +/- 2.3 to 9.5 +/- 1.1 FVC units/degrees C; P = 0.038). Moreover, normothermic FVC and FVC at the highest common T-or between pre- and post-HDT trials were reduced after HDT (normothermic: 4.2 +/- 0.5 to 3.0 +/- 0.4 ml.100 ml(-1).min(-1).100 mmHg(-1), P = 0.04; hyperthermic: 12.4 +/- 1.0 to 7.8 +/- 0.7 ml.100 ml(-1).min(-1).100 mmHg(-1), P < 0.001). These data suggest that HDT exposure reduces thermoregulatory responses to heat stress. The mechanisms resulting in such an impaired thermoregulatory response are unknown but are likely related to the relative dehydration that accompanies this exposure. C1 TEXAS COLL OSTEOPATH MED,DEPT PHYSIOL,FT WORTH,TX 76107. CLIN SCI DIV,PHYSIOL RES BRANCH,BROOKS AFB,TX 78235. NASA,KENNEDY SPACE CTR,FL 32899. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CRANDALL, CG (reprint author), UNIV TEXAS,HLTH SCI CTR,DEPT PHYSIOL,7703 FLOYD CURL DR,SAN ANTONIO,TX 78284, USA. FU NHLBI NIH HHS [HL-08861] NR 38 TC 30 Z9 32 U1 0 U2 3 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 OCT PY 1994 VL 77 IS 4 BP 1863 EP 1867 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA PL694 UT WOS:A1994PL69400042 PM 7836211 ER PT J AU NAKAMITSU, S SAGAWA, S MIKI, K WADA, F NAGAYA, K KEIL, LC DRUMMER, C GERZER, R GREENLEAF, JE HONG, SK SHIRAKI, K AF NAKAMITSU, S SAGAWA, S MIKI, K WADA, F NAGAYA, K KEIL, LC DRUMMER, C GERZER, R GREENLEAF, JE HONG, SK SHIRAKI, K TI EFFECT OF WATER TEMPERATURE ON DIURESIS-NATRIURESIS - AVP, ANP, AND URODILATIN DURING IMMERSION IN MEN SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE COOL WATER; WARM WATER; ESOPHAGEAL TEMPERATURE; NATRIURESIS; CARDIAC OUTPUT; PLASMA RENIN ACTIVITY; ALDOSTERONE; GUANOSINE 3', 5'-CYCLIC MONOPHOSPHATE; ARGININE VASOPRESSIN; ATRIAL NATRIURETIC PEPTIDE ID HEAD-OUT IMMERSION; SALINE INFUSION; PLASMA; VASOPRESSIN; HUMANS; HYPERVOLEMIA; RESPONSES; VOLUME; STRESS; NIGHT AB Effects of water temperature on diuresis, natriuresis, and associated endocrine responses during head-out immersion were studied in eight men (23.4 +/- 0.3 yr) during four 5-h experimental conditions: air control at 28 degrees C and immersion at 34.5 degrees C [thermoneutral (Tnt)], 36 degrees C [above Tnt (aTnt)], and 32 degrees C [below Tnt (bTnt)]. Esophageal temperature decreased by similar to 0.4 degrees C in bTnt and increased by similar to 0.5 degrees C in aTnt. Cardiac output increased by similar to 80% in aTnt and similar to 40% in bTnt while thoracic impedance, an index of central blood pooling, decreased by 7.5 Omega in bTnt (NS vs. Tnt) and 8.8 Omega in aTnt (P < 0.05 vs. Tnt and bTnt). Total peripheral resistance decreased at all temperatures (50% in aTnt, 20% in bTnt). Urine flow and Na+ excretion increased by sixfold in bTnt and Tnt but by only threefold in aTnt. Creatinine clearance was unchanged while osmolal clearance (but not free water clearance) increased twofold with all immersions. Plasma atrial natriuretic peptide (ANP), urinary urodilatin, and urinary guanosine 3',5'-cyclic monophosphate increased while plasma renin activity, aldosterone, and arginine vasopressin (AVP) decreased similarly at all temperatures. bTnt did not potentiate diuresis by selective attenuation of AVP. The overall natriuretic response exhibited a higher correlation with urodilatin (r = 0.45, P < 0.001) than with ANP (r = 0.26, P < 0.01). Because diuresis and natriuresis were significantly attenuated in aTnt where central blood pooling was greater, we conclude that mechanisms other than the atrial stretch receptor reflex, i.e., urodilatin and effective arterial blood volume, may play more predominant roles in the mechanism of immersion-induced diuresis and natriuresis. C1 UNIV OCCUPAT & ENVIRONM HLTH,SCH MED,DEPT PHYSIOL,YAHATANISHI KU,KITAKYUSHU,FUKUOKA 807,JAPAN. SUNY BUFFALO,SCH MED,BUFFALO,NY 14214. SUNY BUFFALO,SCH BIOMED SCI,BUFFALO,NY 14214. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV MUNICH,MUNICH 2,GERMANY. FU NHLBI NIH HHS [HL-28542] NR 29 TC 24 Z9 24 U1 0 U2 0 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 OCT PY 1994 VL 77 IS 4 BP 1919 EP 1925 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA PL694 UT WOS:A1994PL69400051 PM 7836219 ER PT J AU PHILLIPS, TR MALUENDES, S MCLEAN, AD GREEN, S AF PHILLIPS, TR MALUENDES, S MCLEAN, AD GREEN, S TI ANISOTROPIC RIGID ROTOR POTENTIAL-ENERGY FUNCTION FOR H2O-H-2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID COLLISIONAL EXCITATION; ROTATIONAL-EXCITATION; CROSS-SECTIONS; WATER MOLECULE; ATOMS; SPECTROSCOPY; ORTHO-H2; PARA-H2; RATES; MASER AB We have calculated the interaction for H2O-H-2 at 722 points on a five-dimensional surface where both molecules are treated as rigid rotators and we have fitted the ab initio points to a 48-term angular expansion of products of spherical harmonics and rotation matrices. The resulting potential energy function shows strong angle dependence with a large contribution from electrostatic interactions. When averaged over H-2 orientations, the resulting water-atom-like surface is found to have zero crossing and minimum at similar distances to the corresponding H2O-He surface but to be generally more repulsive at short range and more attractive at long range. The isotropic average of the potential has a zero-crossing radius sigma=3.05 Angstrom and a well depth epsilon=49.5 cm(-1) at an intermolecular separation R(m)=3.52 Angstrom. C1 HUGHES STX CORP, NEW YORK, NY 10025 USA. MOLEC RES INST, PALO ALTO, CA 94304 USA. IBM CORP, ALMADEN RES CTR, SAN JOSE, CA 95120 USA. RP NASA, GODDARD INST SPACE STUDIES, GODDARD SPACE FLIGHT CTR, NEW YORK, NY 10025 USA. NR 40 TC 48 Z9 48 U1 0 U2 5 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 1 PY 1994 VL 101 IS 7 BP 5824 EP 5830 DI 10.1063/1.467297 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PH987 UT WOS:A1994PH98700039 ER PT J AU DATEO, CE LEE, TJ SCHWENKE, DW AF DATEO, CE LEE, TJ SCHWENKE, DW TI AN ACCURATE QUARTIC FORCE-FIELD AND VIBRATIONAL FREQUENCIES FOR HNO AND DNO SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID EQUILIBRIUM STRUCTURE; TRIATOMIC-MOLECULES; INFRARED-SPECTRUM; ENERGY-LEVELS; ATOMS AB An accurate ab initio quartic force field for HNO has been determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, CCSD(T), in conjunction with the correlation consistent polarized valence triple zeta (cc-pVTZ) basis set. Improved harmonic frequencies were determined with the cc-pVQZ basis set. Fundamental vibrational frequencies were determined using a second-order perturbation theory analysis and also using variational calculations. The N-O stretch and bending fundamentals are determined well from both vibrational analyses. The H-N stretch, however, is shown to have an unusually large anharmonic correction, and is not well determined using second-order perturbation theory. The H-N fundamental is well determined from the variational calculations, demonstrating the quality of the ab initio quartic force field. The zero-point energy of HNO that should be used in isodesmic reactions is also discussed. RP DATEO, CE (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. RI Lee, Timothy/K-2838-2012; schwenke, david/I-3564-2013 NR 27 TC 78 Z9 78 U1 0 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 1 PY 1994 VL 101 IS 7 BP 5853 EP 5859 DI 10.1063/1.467301 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PH987 UT WOS:A1994PH98700043 ER PT J AU PRICE, C RIND, D AF PRICE, C RIND, D TI THE IMPACT OF A 2-X-CO2 CLIMATE ON LIGHTNING-CAUSED FIRES SO JOURNAL OF CLIMATE LA English DT Article ID WILDLAND FIRE; UNITED-STATES; FOREST; VEGETATION; MINNESOTA; MODEL; CLOUD AB Future climate change could have significant repercussions for lightning-caused wildfires. Two empirical fire models are presented relating the frequency of lightning fires and the area burned by these fires to the effective precipitation and the frequency of thunderstorm activity. One model deals with the seasonal variations in lightning fires, while the second model deals with the interannual variations of lightning fires. These fire models are then used with the Goddard Institute for Space Studies General Circulation Model to investigate possible changes in fire frequency and area burned in a 2 x CO2 climate. In the United States, the annual mean number of lightning fires increases by 44%, while the area burned increases by 78%. On a global scale, the largest increase in lightning fires can be expected in untouched tropical ecosystems where few natural fires occur today. C1 COLUMBIA UNIV,NEW YORK,NY. NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP PRICE, C (reprint author), LAWRENCE LIVERMORE NATL LAB,GLOBAL CLIMATE RES DIV,L-262,POB 808,LIVERMORE,CA 94550, USA. NR 44 TC 125 Z9 129 U1 1 U2 16 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 1994 VL 7 IS 10 BP 1484 EP 1494 DI 10.1175/1520-0442(1994)007<1484:TIOACC>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PN511 UT WOS:A1994PN51100003 ER PT J AU RAJU, IS WANG, JT AF RAJU, IS WANG, JT TI CLASSICAL LAMINATE THEORY MODELS FOR WOVEN FABRIC COMPOSITES SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE FABRIC AND WOVEN COMPOSITES; PLAIN WEAVE; SATIN WEAVES; CLASSICAL LAMINATE THEORY (CLT); UNIT CELLS, REPEATING CELLS; ELASTIC MODULI; POISSONS RATIOS; THERMAL COEFFICIENTS OF EXPANSION AB Improved classical laminate theory (CLT) models are developed for plain weave, 5-, and 8-harness satin weave composites. These models retain the simplicity of the fiber undulation model and the bridging model developed by Chou and Ishikawa but do not have the assumptions made to simplify the analysis. Closed-form expressions are derived for the CLT matrices for the woven fabric composites. These expressions are then used to predict moduli, Poisson's ratios, and the coefficients of thermal expansion (CTE) using the properties of the constituents. The results from the present CLT model are compared to the results from the fabric analysis method, three-dimensional (3D) finite element mosaic models, and other CLT models. The present model results for moduli and Poisson's ratio are, in general, in good agreement with those of other models and the very limited experimental results available in the literature. However, the comparisons for the thermal coefficients of expansion are not satisfactory. The models presented in this paper can be used to predict and rank the performance of woven fabric composites starting from the properties of the constituents. C1 NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23666. RP RAJU, IS (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 8 TC 56 Z9 58 U1 2 U2 8 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 1994 VL 16 IS 4 BP 289 EP 303 PG 15 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA QF516 UT WOS:A1994QF51600001 ER PT J AU CASTELLI, MG AF CASTELLI, MG TI AN ADVANCED TEST TECHNIQUE TO QUANTIFY THERMOMECHANICAL FATIGUE DAMAGE ACCUMULATION IN COMPOSITE-MATERIALS SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE THERMOMECHANICAL FATIGUE (TMF); COMPOSITES; DAMAGE PROGRESSION; TEST TECHNIQUES; STIFFNESS; COEFFICIENT OF THERMAL EXPANSION (CTE) ID THERMAL-EXPANSION AB A mechanical test technique was developed to assist in quantifying the accumulation of damage in composite materials during thermomechanical fatigue (TMF) cycling. This was accomplished by incorporating explicit mechanical property measurements into an ongoing load-controlled TMF test without disturbing the test specimen or significantly altering the test conditions. The technique allows two fundamental composite properties consisting of the isothermal elastic static moduli and the macroscopic coefficient of thermal expansion (CTE) to be measured and collected as functions of the TMF cycles. The specific implementation was incorporated into the commonly employed idealized in-phase and out-of-phase TMF cycles. However, the techniques discussed could be easily implemented into any form of load-controlled TMF mission cycle. By quantifying the degradations of these properties, tremendous insights are gained concerning the progression of macroscopic composite damage and often times the progression of damage within a given constituent. This information should also be useful for the characterization and is essential for the verification of analytical damage modeling methodologies. Several examples using this test technique are given for three titanium metal matrix composite (MMC) laminates. RP CASTELLI, MG (reprint author), NYMA INC,NASA,LEWIS RES CTR GRP,BROOKPARK,OH 44142, USA. NR 25 TC 0 Z9 2 U1 2 U2 2 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 1994 VL 16 IS 4 BP 323 EP 328 PG 6 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA QF516 UT WOS:A1994QF51600004 ER PT J AU YUEN, JL PETRASEK, DW AF YUEN, JL PETRASEK, DW TI ELEVATED-TEMPERATURE FATIGUE BEHAVIOR OF TUNGSTEN FIBER-REINFORCED SUPERALLOY COMPOSITES SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE COMPOSITES; TUNGSTEN FIBER; METAL MATRIX; SUPERALLOYS; TYPE 316 STAINLESS STEEL; INCOLOY 907; WASPALOY; FATIGUE; ELEVATED TEMPERATURES; FRACTOGRAPHY; INERT GAS; THERMAL SHOCK AB The low- and high-cycle fatigue behavior of three different fiber-reinforced superalloy (FRS) composite materials were evaluated. Each composite material contained 40 vol% unidirectionally aligned continuous length tungsten-1.5 wt% ThO2 fibers. The metal matrices were Waspaloy, Type 316L stainless steel, and Incoloy 907. Fatigue tests were conducted at 871 degrees C in a helium atmosphere under load control with a load ratio (minimum stress/maximum stress) of 0.2. The composites were found to have excellent elevated temperature fatigue strength. The fibers played a major role in controlling the fatigue strength of the composites. Fatigue crack fronts were found to be retarded by the fibers. The cracks tended to branch at the fiber/matrix interface and grew by a sliding made along the interface. Matrix surface cracks induced by thermal shock damage had little influence on the fatigue strength of the FRS composites. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP YUEN, JL (reprint author), ROCKWELL INT CORP,ROCKETDYNE DIV,CANOGA PK,CA 91303, USA. NR 15 TC 2 Z9 2 U1 0 U2 5 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 1994 VL 16 IS 4 BP 343 EP 351 PG 9 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA QF516 UT WOS:A1994QF51600007 ER PT J AU SURESH, A AF SURESH, A TI AN ASSESSMENT OF SPECTRAL NONOSCILLATORY SCHEMES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID SHOCK-CAPTURING SCHEMES; EFFICIENT IMPLEMENTATION; WAVE CALCULATIONS AB A new spectral nonoscillatory interpolation scheme is proposed that achieves spectral accuracy in smooth regions and is nonoscillatory on piecewise discontinuous data. The essential idea behind the scheme is to increase the order of an ENO scheme in proportion to the number of points, wherever possible. Numerical experiments with the new scheme on interpolation, 1D advection, inviscid Burgers' equation, and 1D gas dynamics confirm the high resolution features of the scheme. Comparisons with the results of earlier spectral nonoscillatory schemes show that the new scheme is competitive both in efficiency and accuracy. (C) 1994 Academic Press, Inc. RP SURESH, A (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 14 TC 2 Z9 2 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT PY 1994 VL 114 IS 2 BP 339 EP 349 DI 10.1006/jcph.1994.1171 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA PJ462 UT WOS:A1994PJ46200015 ER PT J AU ROGERS, JR DOWNEY, JP WITHEROW, WK FACEMIRE, BR FRAZIER, DO FRADKOV, VE MANI, SS GLICKSMAN, ME AF ROGERS, JR DOWNEY, JP WITHEROW, WK FACEMIRE, BR FRAZIER, DO FRADKOV, VE MANI, SS GLICKSMAN, ME TI COARSENING OF 3-DIMENSIONAL DROPLETS BY 2-DIMENSIONAL DIFFUSION .1. EXPERIMENT SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article; Proceedings Paper CT Symposium on the Development of Microstructure in Deposited Thin Films, at the TMS Annual Meeting CY MAR 01-02, 1994 CL SAN FRANCISCO, CA SP MINERALS MET & MAT SOC DE DIFFUSION; HOLOGRAPHY; KINETICS; MICROSTRUCTURE COARSENING; OSTWALD RIPENING; PHASE TRANSFORMATION ID SUCCINONITRILE-WATER; SYSTEM AB An experimental study of diffusional coarsening, or Ostwald ripening, in a liquid-liquid two-phase system is described. An experiment performed at its isopycnic point, 42-degrees-C, allowed observations for the long times required to investigate coarsening. A holographic technique was instrumental in this work. Holograms taken in situ permit investigation of details regarding both the influence of local environmental conditions on individual droplet size histories and measurement of global averages. This study utilized a 100 mum pathlength test cell. The discrete phase was nucleated on one wall of the cell. This configuration resembles island formation in thin film growth. Observation of Ostwald ripening over a period of 1 x 10(7) s (approximately 4 mo.) reveals that droplet number decays ast-0.733 and the average radius increases as t-0.247, in the asymptotic limit. This shows good agreement with theoretical predictions for diffusional growth of spherical caps on a two-dimensional substrate which is a valid approximation for the geometry of this experiment. Part I of this paper describes the experimental results. Part II discusses a numerical model for droplet growth in a comparison with the experimental results. C1 RENSSELAER POLYTECH INST,TROY,NY 12180. RP ROGERS, JR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,NTL RES COUNCIL,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 11 TC 10 Z9 10 U1 0 U2 5 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD OCT PY 1994 VL 23 IS 10 BP 999 EP 1006 DI 10.1007/BF02650367 PG 8 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA PK994 UT WOS:A1994PK99400002 ER PT J AU FRADKOV, VE MANI, SS GLICKSMAN, ME ROGERS, JR DOWNEY, JP WITHEROW, WK FACEMIRE, BR FRAZIER, DO AF FRADKOV, VE MANI, SS GLICKSMAN, ME ROGERS, JR DOWNEY, JP WITHEROW, WK FACEMIRE, BR FRAZIER, DO TI COARSENING OF 3-DIMENSIONAL DROPLETS BY 2-DIMENSIONAL DIFFUSION .2. THEORY SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article; Proceedings Paper CT Symposium on the Development of Microstructure in Deposited Thin Films, at the TMS Annual Meeting CY MAR 01-02, 1994 CL SAN FRANCISCO, CA SP MINERALS MET & MAT SOC DE COARSENING; KINETICS; MICROSTRUCTURE COARSENING; OSTWALD RIPENING; PHASE TRANSFORMATION; QUASI-STATIONARY DIFFUSION AB Theoretical modeling of coarsening among a finite cluster of precipitates is implemented, using the multipole expansion method. This method requires the diffusion field to behave quasi-statically. Two approximate solutions were developed, one to monopolar order, and other to the dipolar order. The conventional Gibbs-Thomson equilibrium relationship was used as the boundary condition at the precipitate-matrix interface. Part I of this paper considers a liquid-liquid system in a mixed-dimensional geometrical configuration, wherein three-dimensional precipitates interact via a diffusion field constrained in two dimensions. This kind of geometric configuration is often encountered in island evolution dynamics and phase segregation in thin films. The initial experimental configuration of droplets provides the initial condition for the simulation. Both monopole and dipole approximations closely follow the experimentally observed scaling laws, characteristic for the mixed-dimensional coarsening (N-4/3 and R4BAR, varied linearly with time, where N is the number of droplets in the experimental field of view, and RBAR is the average droplet radius). Good agreement is observed for time evolution of radii of some individual precipitates. Certain deviations appearing among the two approximate solutions and the experimental data are discussed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,NATL RES COUNCIL,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP FRADKOV, VE (reprint author), RENSSELAER POLYTECH INST,TROY,NY 12180, USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 8 TC 1 Z9 1 U1 0 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD OCT PY 1994 VL 23 IS 10 BP 1007 EP 1013 DI 10.1007/BF02650368 PG 7 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA PK994 UT WOS:A1994PK99400003 ER PT J AU BURTON, WS NOOR, AK AF BURTON, WS NOOR, AK TI 3-DIMENSIONAL SOLUTIONS FOR THERMOMECHANICAL STRESSES IN SANDWICH PANELS AND SHELLS SO JOURNAL OF ENGINEERING MECHANICS-ASCE LA English DT Article ID 3-DIMENSIONAL ELASTICITY SOLUTION; FINITE-ELEMENT; STATIC RESPONSE; PLATES; SHEAR AB Analytic three-dimensional thermoelasticity solutions are presented for static problems of simply supported sandwich panels and cylindrical shells subjected to mechanical and thermal loads. The panels and shells have laminated composite face sheets of arbitrary thickness separated by a core. Each of the individual layers of the face sheets and the core is modeled as a three-dimensional continuum. Analytic first-order sensitivity coefficients are evaluated to assess the sensitivity of the responses to variations in material parameters of the face sheets and the core, as well as to variations in the curvatures and thicknesses of the sandwich and face sheets. Also, the strain energy associated with various stress components in the face sheets and core are calculated and compared. The information obtained in the present study can aid the development and assessment of two-dimensional models for sandwich structures and illuminate the role of particular material parameters in an equivalent model for the core. RP BURTON, WS (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECH,HAMPTON,VA 23681, USA. NR 27 TC 27 Z9 28 U1 0 U2 7 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9399 J9 J ENG MECH-ASCE JI J. Eng. Mech.-ASCE PD OCT PY 1994 VL 120 IS 10 BP 2044 EP 2071 DI 10.1061/(ASCE)0733-9399(1994)120:10(2044) PG 28 WC Engineering, Mechanical SC Engineering GA PH580 UT WOS:A1994PH58000003 ER PT J AU CUNNINGHAM, HA WELCH, RB AF CUNNINGHAM, HA WELCH, RB TI MULTIPLE CONCURRENT VISUAL-MOTOR MAPPINGS - IMPLICATIONS FOR MODELS OF ADAPTATION SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article; Proceedings Paper CT Engineering-Foundation Conference on Biomechanics and Neural Control of Movement CY 1992 CL VENTURA, CA SP ENGN FDN ID VESTIBULO-OCULAR REFLEX; S-R COMPATIBILITY; HYPOTHESIS; RETENTION; MOVEMENT; VECTOR AB Previous research on adaptation to visual-motor rearrangement suggests that the central nervous system represents accurately only 1 visual-motor mapping at a time. This idea was examined in 3 experiments where subjects tracked a moving target under repeated alternations between 2 initially interfering mappings (the ''normal'' mapping characteristic of computer input devices and a 108-degrees rotation of the normal mapping). Alternation between the 2 mappings led to significant reduction in error under the rotated mapping and significant reduction in the adaptation aftereffect ordinarily caused by switching between mappings. Color as a discriminative cue, interference versus decay in adaptation aftereffect, and intermanual transfer were also examined. The results reveal a capacity for multiple concurrent visual-motor mappings, possibly controlled by a parametric process near the motor output stage of processing. RP CUNNINGHAM, HA (reprint author), NASA,AMES RES CTR,DEPT LIFE SCI,MAIL STOP 239-11,MOFFETT FIELD,CA 94035, USA. NR 64 TC 89 Z9 89 U1 2 U2 5 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD OCT PY 1994 VL 20 IS 5 BP 987 EP 999 DI 10.1037/0096-1523.20.5.987 PG 13 WC Psychology; Psychology, Experimental SC Psychology GA PM608 UT WOS:A1994PM60800005 PM 7964533 ER PT J AU LYLE, KH DOWELL, EH AF LYLE, KH DOWELL, EH TI ACOUSTIC RADIATION DAMPING OF FLAT RECTANGULAR-PLATES SUBJECTED TO SUBSONIC FLOWS .1. ISOTROPIC SO JOURNAL OF FLUIDS AND STRUCTURES LA English DT Article ID MODEL; SOUND AB The acoustic radiation damping for various plates and semi-infinite strips subjected to a uniform, subsonic and steady flow has been predicted. The predictions are based on the linear vibration of a flat plate. The fluid loading is characterized as the perturbation pressure derived from the linearized Bernoulli and continuity equations. Parameters varied in the analysis include Mach number, mode number and plate size, aspect ratio and mass. Results show that the fluid loading can significantly affect realistic plate responses. In addition, acoustic radiation damping values can be greater than or equal to the structural component of the modal critical damping ratio (assumed as 0.01) for the higher subsonic Mach numbers. C1 DUKE UNIV,SCH ENGN,DURHAM,NC 27708. RP LYLE, KH (reprint author), NASA,LANGLEY RES CTR,USA,VEHICLE STRUCT DIRECTORATE,HAMPTON,VA 23665, USA. NR 25 TC 9 Z9 9 U1 0 U2 6 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0889-9746 J9 J FLUID STRUCT JI J. Fluids Struct. PD OCT PY 1994 VL 8 IS 7 BP 711 EP 735 DI 10.1016/S0889-9746(94)90180-5 PG 25 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA PN332 UT WOS:A1994PN33200003 ER PT J AU LYLE, KH DOWELL, EH AF LYLE, KH DOWELL, EH TI ACOUSTIC RADIATION DAMPING OF FLAT RECTANGULAR-PLATES SUBJECTED TO SUBSONIC FLOWS .2. COMPOSITE SO JOURNAL OF FLUIDS AND STRUCTURES LA English DT Article AB The acoustic radiation damping for various laminated composite and aluminum plates subjected to a uniform, subsonic, and steady flow has been predicted. The predictions are based on the linear equations of motion of a flat plate. The fluid loading is characterized as the perturbation pressure derived from the linearized Bernoulli and continuity equations of fluid mechanics. Parameters varied in the analysis include Mach number and plate material properties and ply lay-up. Results show that the fluid loading can significantly affect realistic plate responses. Universal curves are presented where the acoustic radiation damping normalized by the mass ratio is a smooth function of the reduced frequency. A separate curve was required for each Mach number and plate aspect ratio. Generally, graphite/epoxy and carbon/carbon plates have higher acoustic radiation damping values than similar aluminum plates, except near plate divergence conditions resulting from aeroelastic instability. In addition, acoustic radiation damping values can be greater than or equal to the structural damping ratio component (assumed as 0.01) for the higher Mach numbers. C1 DUKE UNIV,SCH ENGN,DURHAM,NC 27708. RP LYLE, KH (reprint author), NASA,LANGLEY RES CTR,USA,VEHICLE STRUCT DIRECTORATE,HAMPTON,VA 23665, USA. NR 14 TC 1 Z9 1 U1 1 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0889-9746 J9 J FLUID STRUCT JI J. Fluids Struct. PD OCT PY 1994 VL 8 IS 7 BP 737 EP 746 DI 10.1016/S0889-9746(94)90200-3 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA PN332 UT WOS:A1994PN33200004 ER PT J AU CLARK, FE PATTERSON, RT FISHBEIN, E AF CLARK, FE PATTERSON, RT FISHBEIN, E TI DISTRIBUTION OF HOLOCENE BENTHIC FORAMINIFERA FROM THE TROPICAL SOUTHWEST PACIFIC-OCEAN SO JOURNAL OF FORAMINIFERAL RESEARCH LA English DT Article ID POLAR FRONT REGION; SEA; ATLANTIC; ASSEMBLAGES; ECOLOGY AB A suite of 62 surface and near surface samples has been examined for its benthic foraminiferal faunas, The cores sampled ranged from 110 to 8900 m water depth, and are distributed across the tropical southwest pacific Ocean, north and east of Australia, A total of 606 species were identified, Census data was obtained for each sample, and species found in statistically significant fractional abundances (88 in all) were analyzed using a new Q-mode clustering algorithm (Error Weighted Maximum Likelihood [EWML]), Both the fun data set, and an edited data set comprising 44 samples and 39 species, were analyzed. With the aid of these analyses, ten benthic foraminiferal assemblages were identified, Three manually constrained assemblages, each represented by a single sample, were recognized, namely tbe Bolivina dilatata-Siphouvigerina interrupda Assemblage, the Cymbaloporetta squammosa-Brizalina abbreviata Assemblage, and the Brizalina beyrichi-Melonis barleeanum Assemblage, Five statistically constrained assemblages were recognized, each having a water depth range coincident with the range for known wafer masses of the region, The Astrononion echolsi-Cassidulina teretis Assemblage and the Nuttallides bradyanus Assemblage were developed in samples from depths bathed by waters of the Deep Oxygen Minimum, the Epistominella exigua-Globocassidulina rarilocula Assemblage was developed in samples from depths bathed by Deep Water, a derivative of Antarctic Bottom Water, and both the Globocassidulina subglobosa-Pseudoparrella parca Assemblage and the Nuttallides umboniferus Assemblage were developed in samples from depths bathed by Antarctic Bottom Water proper, From depths very near the calcite compensation depth (CCD), a Mixed Calcareous/ Agglutinated Abyssal Assemblage was developed in a pair of samples, whereas below the CCD, the tenth assemblage, the Abyssal Agglutinated Assemblage, was developed, with only a few corroded calcareous specimens accompanying the agglutinated benthic faunas, These latter two assemblages were also manually constrained, C1 CARLETON UNIV,OTTAWA CARLETON GEOSCI CTR,OTTAWA K1S 5B6,ON,CANADA. CARLETON UNIV,DEPT EARTH SCI,OTTAWA K1S 5B6,ON,CANADA. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CLARK, FE (reprint author), UNIV ALBERTA,DEPT GEOL,EDMONTON T6G 2E3,AB,CANADA. NR 93 TC 10 Z9 10 U1 0 U2 2 PU CUSHMAN FOUNDATION FORAMINIFERAL RES PI CAMBRIDGE PA MUSEUM COMPARATIVE ZOOLOGY, DEPT INVERTEBRATE PALEONTOLOGY 26 OXFORD ST, HARVARD UNIV, CAMBRIDGE, MA 02138 SN 0096-1191 J9 J FORAMIN RES JI J. Foraminifer. Res. PD OCT PY 1994 VL 24 IS 4 BP 241 EP 267 PG 27 WC Paleontology SC Paleontology GA PW781 UT WOS:A1994PW78100006 ER PT J AU HUDDLESTON, DE NEUGEBAUER, M GOLODSTEIN, BE AF HUDDLESTON, DE NEUGEBAUER, M GOLODSTEIN, BE TI MODELING OF PICKUP ION DISTRIBUTIONS IN THE HALLEY COMET OSHEATH - EMPIRICAL LIMITS ON RATES OF IONIZATION, DIFFUSION, LOSS AND CREATION OF FAST NEUTRAL ATOMS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND INTERACTION; COMET-P-HALLEY; BOW SHOCK; GIOTTO OBSERVATIONS; INNER COMA; P/HALLEY; PLASMA; SPACE; GAS; TURBULENCE AB The shape of the velocity distribution of water group ions observed by the Giotto ion mass spectrometer on its approach to comet Halley is modeled to derive empirical values for the rates of ionization, energy diffusion, and loss in the midcometosheath. The model includes the effect of rapid pitch angle scattering into a bispherical shell distribution as well as the effect of the magnetization of the plasma on the charge exchange loss rate. It is found that the average rate of ionization of cometary neutrals in this region of the cometosheath appears to be of the order of a factor 3 faster than the ''standard'' rates approximately 1 x 10(-6) s-1 that are generally assumed to model the observations in most regions of the comet environment. For the region of the coma studied in the present work (approximately 1-2x10(5) km from the nucleus), the inferred energy diffusion coefficient is D0 almost-equal-to 0.002 to 0.005 km2s-3, which is generally lower than values used in other models. The empirically obtained loss rate appears to be about an order of magnitude greater than can be explained by charge exchange with the ''standard'' cross section of approximately 2x10(-15) cm-2. However such cross sections are not well known and for water group ion / water group neutral interactions, rates as high as 8x10(-15) cm2 have previously been suggested in the literature. Assuming the entire loss rate is due to charge exchange yields a rate of creation of fast neutral atoms of the order of approximately 10(-4) s-1 or higher, depending on the level of velocity diffusion. The fast neutrals may, in turn, be partly responsible for the higher-than-expected ionization rate. RP HUDDLESTON, DE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 38 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1994 VL 99 IS A10 BP 19245 EP 19254 DI 10.1029/94JA01482 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500012 ER PT J AU GOLDSTEIN, R ALTWEGG, K FUSELIER, SA GOLDSTEIN, BE BALSIGER, H JOST, F COATES, A NEUBAUER, FM ROSENBAUER, H AF GOLDSTEIN, R ALTWEGG, K FUSELIER, SA GOLDSTEIN, BE BALSIGER, H JOST, F COATES, A NEUBAUER, FM ROSENBAUER, H TI GIOTTO ION MASS-SPECTROMETER MEASUREMENTS AT COMET-P GRIGG-SKJELLERUP SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COMET GRIGG-SKJELLERUP; WATER GROUP IONS; COMPUTER-SIMULATIONS; PICKUP IONS; ENCOUNTER; P/HALLEY; INSTABILITIES; SPACECRAFT; HALLEY; DUST AB The Giotto ion mass spectrometer high-intensity spectrometer (IMS-HIS) measured fluxes of ions from about 260,000 km before (1008:37 UT spacecraft time) to about 86,000 km after (1701:33 UT spacecraft time) closet approach to comet P/Grigg-Skjellerup during the encounter on July 10, 1992. Although the HIS sensor was not designed to measure protons, these ions were measured far from the comet. Close in to the comet, the ions observed were probably also protons, although heavier ions cannot be completely ruled out. Considerable temporal structure appears in the data, well-correlated with the data of other instruments onboard, especially those of the magnetometer. In particular, the ion count rate correlates with the direction of the magnetic field. This strong modulation at the water group ion cyclotron period (approximately 90 s) inside the inbound bow wave indicates a very narrow ion pitch angle distribution. Hence at Grigg-Skjellerup the ions appear to experience very little pitch angle scattering. This may result from strong compression in the rapidly increasing magnetic field. C1 UNIV BERN, INST PHYS, CH-3012 BERN, SWITZERLAND. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. UCL, MULLARD SPACE SCI LAB, DORKING RH5 6NT, SURREY, ENGLAND. UNIV COLOGNE, INST GEOPHYS & METEOROL, D-50923 COLOGNE, GERMANY. MAX PLANCK INST AERON, D-37191 KATLENBURG DUHM, GERMANY. RP GOLDSTEIN, R (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. RI Coates, Andrew/C-2396-2008 OI Coates, Andrew/0000-0002-6185-3125 NR 24 TC 3 Z9 3 U1 0 U2 2 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 1994 VL 99 IS A10 BP 19255 EP 19265 DI 10.1029/94JA01746 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500013 ER PT J AU GHOSH, S VINAS, AF GOLDSTEIN, ML AF GHOSH, S VINAS, AF GOLDSTEIN, ML TI NONLINEAR EVOLUTION OF A LARGE-AMPLITUDE CIRCULARLY-POLARIZED ALFVEN-WAVE - HIGH-BETA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PARAMETRIC-INSTABILITIES; INCOMPRESSIBLE MAGNETOHYDRODYNAMICS; FILAMENTATION INSTABILITY; RELAXATION PROCESSES; TURBULENCE; MAGNETOFLUID; EXCITATION; DAUGHTER AB The nonlinear dynamics following saturation of the parametric instabilities of a monochromatic field-aligned large-amplitude circularly polarized Alfven wave is investigated via direct numerical simulation in the case of high plasma beta and no wave dispersion. The magnetohydrodynamic (MHD) code permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Turbulent cascades develop after saturation of two coupled oblique three-wave parametric instabilities; one of which is an oblique filamentationlike instability reported earlier. Remnants of the parametric processes, as well as of the original Alfven pump wave, persist during late nonlinear times. Nearly incompressible MHD features such as spectral anisotropies appear as well. C1 APPL RES CORP,LANDOVER,MD. RP GHOSH, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Goldstein, Melvyn/B-1724-2008 NR 17 TC 20 Z9 20 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 1994 VL 99 IS A10 BP 19289 EP 19300 DI 10.1029/94JA01483 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500015 ER PT J AU BURLAGA, LF AF BURLAGA, LF TI MERGED INTERACTION REGIONS AND LARGE-SCALE MAGNETIC-FIELD FLUCTUATIONS DURING 1991 - VOYAGER-2 OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COSMIC-RAY MODULATION; OUTER HELIOSPHERE; SOLAR-WIND; PIONEER-10; SHOCK; EARTH AB This paper analyzes Voyager 2 observations of the magnetic field between 33.6 AU and 36.2 AU during 1991 when extraordinary events were observed on the Sun and in the heliosphere. The magnetic field strength signal B(t) has the unusual form of two large transient merged interaction regions (MIRs) on a fluctuating background. The two MIRs moved past the spacecraft in 32 days and 18 days, respectively. The mean field strength in each transient MIR was almost-equal-to 2.6 times the mean field during the remaining part of the year (0.11 nT). Each of the MIRs is related to a fast stream. The magnetic field is strong throughout each stream, suggesting that the strong fields are carried by the streams as well as produced by shock and stream compression. The fluctuations in B(t) during 1991 are not multifractal, and the MIRs cannot be approximated as multifractal clusters of intense magnetic fields. The distribution of the hour-averaged magnetic field strengths is approximately lognormal over 90% of its intermediate range, and it has an exponential tail for B greater than the average magnetic field strength. The elevation angles of B have a normal distribution with a standard deviation of 16-degrees +/- 4-degrees. The distributions of the azimuthal angles of B in the ranges 0-degree-180-degrees and 180-degrees-360-degrees are approximately normal over a more limited range, and non-Gaussian tails associated with nearly radial magnetic fields; the standard deviations are almost-equal-to 40-degrees. Individual sectors are present throughout most of the interval, even in the MIRs, but there is no recurrent sector pattern. A model of the large-scale fluctuations in 1991 will have to include both deterministic and statistical factors. C1 UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 29 TC 28 Z9 28 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 1994 VL 99 IS A10 BP 19341 EP 19350 DI 10.1029/94JA01513 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500018 ER PT J AU KESSEL, RL COATES, AJ MOTSCHMANN, U NEUBAUER, FM AF KESSEL, RL COATES, AJ MOTSCHMANN, U NEUBAUER, FM TI SHOCK NORMAL DETERIORATION FOR MULTIPLE-ION SHOCKS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GIOTTO MAGNETOMETER EXPERIMENT; HALLEY BOW SHOCK; COMET HALLEY; SOLAR-WIND; GIACOBINI-ZINNER; GRIGG-SKJELLERUP; FLOW AB We have adapted the single-ion Vinas and Scudder (1986) solution to the Rankine-Hugoniot problem to a multiple-on solution. Using this technique, we can calculate a shock normal direction, shock speed, best estimate of the upstream and downstream magnetic field and plasma asymptotic states, and theta(Bn), the angle between the shock normal and the upstream magnetic field. We test the multi-ion solution with a theoretical case but are restricted to a perpendicular shock in order to close the multi-ion Rankine-Hugoniot equations. For this test case both single-ion and multi-ion solutions are equally valid. We examine parameter regimes to look for differences between single-ion and multi-ion solutions of the R-H equations, and we find that the largest differences occur for quasi-parallel shocks, small values of solar wind speed, large values of heavy ion density, and very strong and very weak shocks. For both the inbound and outbound crossing of comet Halley we have a slow solar wind speed, small values of water group ions and fairly weak shocks. We examine both the quasi-perpendicular inbound crossing and the quasi-parallel outbound crossing at comet Halley. For the inbound crossing we have good resolution data and make an accurate determination. However, it is likely that the shock normal determination was influenced by the interplanetary disturbances flowing from the Sun that permeate the inbound crossing region and that force the normal to an antisunward direction. For the outbound case the FIS experiment is not providing data because it was damaged by cometary dust soon after closest approach. However, the results are more definitive: all of the normals are within 31-degrees of each other, which makes the analysis essentially independent of interval. In both cases there are differences between the single- and multi-ion solutions with the multi-ion solution being the more reliable. C1 MULLARD SPACE SCI LAB,DORKING,SURREY,ENGLAND. TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG,INST GEOPHYS & METEOROL,W-3300 BRAUNSCHWEIG,GERMANY. UNIV COLOGNE,INST GEOPHYS & METEOROL,W-5000 COLOGNE 41,GERMANY. RP KESSEL, RL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,SPACE PHYS DATA FACIL,GREENBELT,MD 20771, USA. RI Coates, Andrew/C-2396-2008 OI Coates, Andrew/0000-0002-6185-3125 NR 26 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1994 VL 99 IS A10 BP 19359 EP 19374 DI 10.1029/94JA01234 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500020 ER PT J AU SOTIRELIS, T TSYGANENKO, NA STERN, DP AF SOTIRELIS, T TSYGANENKO, NA STERN, DP TI METHOD FOR CONFINING THE MAGNETIC-FIELD OF THE CROSS-TAIL CURRENT INSIDE THE MAGNETOPAUSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOMAGNETIC-FIELD; MAGNETOSPHERIC FIELD; QUANTITATIVE MODELS; PARAMETERS; SHAPE AB A method is presented for analytically representing the magnetic field due to the cross-tail current and its closure on the magnetopause. It is an extension of a method used by Tsyganenko (1989b) to confine the dipole field inside an ellipsoidal magnetopause using a scalar potential. Given a model of the cross-tail current, the implied net magnetic field is obtained by adding to the cross-tail current field a potential field B = -delgamma, which makes all field lines divide into two disjoint groups, separated by the magnetopause (i.e., the combined field is made to have zero normal component with the magnetopause). The magnetopause is assumed to be an ellipsoid of revolution (a prolate spheroid) as an approximation to observations (Sibeck et al., 1991). This assumption permits the potential gamma to be expressed in spheroidal coordinates, expanded in spheroidal harmonics and its terms evaluated by performing inversion integrals. Finally, the field outside the magnetopause is replaced by zero, resulting in a consistent current closure along the magnetopause. This procedure can also be used to confine the modeled field of any other interior magnetic source, though the model current must always flow in closed circuits. The method is demonstrated on the T87 cross-tail current, examples illustrate the effect of changing the size and shape of the prescribed magnetopause and a comparison is made to an independent numerical scheme based on the Biot-Savart equation. RP SOTIRELIS, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 26 TC 10 Z9 10 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 OCT 1 PY 1994 VL 99 IS A10 BP 19393 EP 19402 DI 10.1029/94JA01656 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500023 ER PT J AU FARRUGIA, CJ SANDHOLT, PE BURLAGA, LF AF FARRUGIA, CJ SANDHOLT, PE BURLAGA, LF TI AURORAL ACTIVITY ASSOCIATED WITH KELVIN-HELMHOLTZ INSTABILITY AT THE INNER EDGE OF THE LOW-LATITUDE BOUNDARY-LAYER SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; CONVECTION TWIN-VORTICES; IONOSPHERIC CONVECTION; ALIGNED CURRENTS; EARTHS MAGNETOSPHERE; MAGNETOPAUSE; MODEL; MAGNETOSHEATH; EVENTS; ENERGY AB Auroral activity occurred in the late afternoon sector (approximately 16 MLT) in the northern hemisphere during the passage at Earth of an interplanetary magnetic cloud on January 14, 1988. The auroral activity consisted of a very dynamic display which was preceded and followed by quiet auroral displays. During the quiet displays, discrete rayed arcs aligned along the geomagnetic L shells were observed. In the active stage, rapidly evolving spiral forms centered on magnetic zenith were evident. The activity persisted for many minutes and was characterized by the absence of directed motion. They were strongly suggestive of intense filaments of upward field-aligned currents embedded in the large-scale region 1 current system. Distortions of the flux ropes as they connect from the equatorial magnetosphere to the ionosphere were witnessed. We assess as possible generating mechanisms three nonlocal sources known to be associated with field-aligned currents. Of these, partial compressions of the magnetosphere due to variations of solar wind dynamic pressure seem an unlikely source. The possibility that the auroral forms are due to reconnection is investigated but is excluded because the active aurora were observed on the closed field line region just equatorward of the convection reversal boundary. To support this conclusion further, we apply recent results on the mapping of ionospheric regions to the equatorial plane based on the Tsyganenko 1989 model (Kaufmann et al., 1993). We find that for comparable magnetic activity the aurora map to the equatorial plane at X(GSM) = approximately 3 R(E) and approximately 2 R(E) inward of the magnetopause, that is, the inner edge of the boundary layer close to dusk. Since the auroral forms are manifestly associated with magnetic field shear, a vortical motion at the equatorial end of the flux rope is indicated, making the Kelvin-Helmholtz instability acting at the inner edge of the low-latitude boundary layer the most probable generating source. Our proposed auroral signature of viscous-type solar wind-magnetosphere interaction is easily distinguished from the well-documented sequence of moving auroral forms in the near-noon sector, which are observed to be associated with a time-dependent structure of merging-cell convection. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV OSLO,DEPT PHYS,OSLO 3,NORWAY. NR 47 TC 14 Z9 14 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 OCT 1 PY 1994 VL 99 IS A10 BP 19403 EP 19411 DI 10.1029/94JA00926 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500024 ER PT J AU KAMIDE, Y RICHMOND, AD EMERY, BA HUTCHINS, CF AHN, BH DELABEAUJARDIERE, O FOSTER, JC HEELIS, RA KROEHL, HW RICH, FJ SLAVIN, JA AF KAMIDE, Y RICHMOND, AD EMERY, BA HUTCHINS, CF AHN, BH DELABEAUJARDIERE, O FOSTER, JC HEELIS, RA KROEHL, HW RICH, FJ SLAVIN, JA TI GROUND-BASED STUDIES OF IONOSPHERIC CONVECTION ASSOCIATED WITH SUBSTORM EXPANSION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; MAPPING ELECTRODYNAMIC FEATURES; INTERPLANETARY MAGNETIC-FIELD; HIGH-LATITUDE IONOSPHERE; ELECTRIC-FIELDS; MILLSTONE HILL; SOLAR-WIND; LOCALIZED OBSERVATIONS; AURORAL IONOSPHERE; PLASMA CONVECTION AB The instantaneous patterns of electric fields and currents in the high-latitude ionosphere are deduced by combining satellite and radar measurements of the ionospheric drift velocity, along with ground-based magnetometer observations for October 25, 1981. For this purpose, an updated version of the assimilative mapping of ionospheric electrodynamics technique has been used. These global patterns are unobtainable from any single data set. The period under study was characterized by a relatively stable southward interplanetary magnetic field (IMF), so that the obtained electric field patterns do reflect, in general, the state of sustained and enhanced plasma convection in the magnetosphere. During one of the satellite passes, however, an intense westward electrojet caused by a substorm into the satellite (DE 2) and radar (Chatanika, Alaska) field of view in the premidnight sector, providing a unique opportunity to differentiate the enhanced convection and substorm expansion fields. The distributions of the calculated electric potential for the expansion and maximum phases of the substorm show the first clear evidence of the coexistence of two physically different systems in the global convection pattern. The changes in the convection pattern during the substorm indicate that the large-scale potential distributions are indeed of general two-cell patterns representing the southward IMF status, but the night-morning cell has two positive peaks, one in the midnight sector and the other in the late morning hours, corresponding to the substorm expansion and the convection enhancement, respectively. C1 NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. KYUNGPOOK NATL UNIV,DEPT EARTH SCI,TAEGU 702701,SOUTH KOREA. STANFORD RES INST INT,RADIO PHYS LAB,MENLO PK,CA 94025. MIT,HAYSTACK OBSERV,WESTFORD,MA 01866. UNIV TEXAS,CTR SPACE SCI,RICHARDSON,TX 75080. NOAA,NAT GEOPHYS DATA CTR,BOULDER,CO 80303. USAF,GEOPHYS LAB,BEDFORD,MA 01731. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP KAMIDE, Y (reprint author), NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA 442,JAPAN. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 40 TC 40 Z9 40 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 1994 VL 99 IS A10 BP 19451 EP 19466 DI 10.1029/94JA01625 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500029 ER PT J AU FARRELL, WM AGGSON, TL RODGERS, EB HANSON, WB AF FARRELL, WM AGGSON, TL RODGERS, EB HANSON, WB TI OBSERVATIONS OF IONOSPHERICS ELECTRIC-FIELDS ABOVE ATMOSPHERIC WEATHER SYSTEMS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EXPLOSIVE SPREAD-F; THUNDERSTORM; MODEL; ELECTRIFICATION; MAGNETOSPHERE; THUNDERCLOUD; RADIATION; SATELLITE; BUBBLES AB We report on the observations of a number of quasi-dc electric field events associated with large-scale atmospheric weather formations. The observations were made by the electric field experiment onboard the San Marco D satellite, operational in an equatorial orbit from May to December 1988. Several theoretical studies suggest that electric fields generated by thunderstorms are present at high altitudes in the ionosphere. In spite of such favorable predictions, weather-related events are not often observed since they are relatively weak. We shall report here on a set of likely E field candidates for atmosphere-ionosphere causality, these being observed over the Indonesian Basin, northern South America, and the west coast of Africa; all known sites of atmospheric activity. As we shall demonstrate, individual events can often be traced to specific active weather features. For example, a number of events were associated with spacecraft passages near Hurricane Joan in mid-October 1988. As a statistical set, the events appear to coincide with the most active regions of atmospheric weather. C1 UNIV TEXAS,CTR SPACE PHYS,RICHARDSON,TX 75083. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP FARRELL, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 31 TC 11 Z9 11 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1994 VL 99 IS A10 BP 19475 EP 19483 DI 10.1029/94JA01135 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500031 ER PT J AU TINSLEY, BA ROHRBAUGH, RP ISHIMOTO, M TORR, MR TORR, DG AF TINSLEY, BA ROHRBAUGH, RP ISHIMOTO, M TORR, MR TORR, DG TI MIDDLE-LATITUDE AND LOW-LATITUDE EMISSIONS FROM ENERGETIC NEUTRAL ATOM PRECIPITATION SEEN FROM ATLAS-1 UNDER QUIET MAGNETIC CONDITIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RING CURRENT; STATISTICAL-MODEL; AURORAE; PARTICLES AB During the ATLAS 1 mission spectral observations were made at middle and low latitudes of features expected from the precipitation of energetic neutral atoms. The Imaging Spectrometric Observatory was used at night in the UV and visible with maximum gain. The tangent ray heights of the look directions ranged from near 100 km to near 200 km, and the geomagnetic conditions were quiet during the observations, which were made March 28 to April 3, 1992. The N2+1N 391.4-nm and O I 130.4 and 135.6-nm emissions were observed at all latitudes, with lower emission rates at lower magnetic dip latitudes, except that enhancements in the O I lines were seen within 30-degrees of the dip equator due to radiative recombination of ionospheric plasma. The latitude profile observed for the N2+1N emission did not show an equatorial or midlatitude peak. This implies that the source of energetic neutrals is more consistent with prompt charge exchange loss of freshly injected trapped ions with relatively low mirror heights (i.e., ions on higher L shells with equatorial pitch angle distributions nearly isotropic to the loss cone) than loss of highly eroded populations of particles with high mirror heights (i.e., ions on lower L shells with pancake equatorial pitch angle distributions). The N2+1N emission rates have been compared with models of atmospheric emission due to fluxes of O/O+ and H/H+ in the thermosphere, as produced by energetic neutral oxygen or hydrogen atom precipitation. Energy deposition rates are inferred that range from about 12 (+/-3) x 10(-4) erg cm-2 s-1 near 45-degrees geomagnetic latitude to about 3 (+/-1) x 10(-4) erg cm-2 s-1 near the geomagnetic equator. These can be compared with energy deposition rates a factor of 10(2) higher during magnetic storms. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35807. NASA,MARSHALL SPACE FLIGHT CTR,PAYLOADS PROJECT OFF,HUNTSVILLE,AL 35807. COMPUTAT PHYS INC,FAIRFAX,VA 22031. RP TINSLEY, BA (reprint author), 88,2601 FLOYD RD,DALLAS,TX, USA. NR 19 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD OCT 1 PY 1994 VL 99 IS A10 BP 19577 EP 19584 DI 10.1029/94JA01265 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK515 UT WOS:A1994PK51500039 ER PT J AU BANSAL, NP AF BANSAL, NP TI LOW-TEMPERATURE SYNTHESIS, PYROLYSIS AND CRYSTALLIZATION OF TANTALUM OXIDE GELS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SPUTTERED TA2O5; FILMS AB Tantalum oxide gels in the form of transparent monoliths and powders have been prepared from hydrolysis of tantalum pentaethoxide under controlled conditions using different mole ratios of Ta(OC2H5)(5):C2H5OH:H2O:HCl. Alcohol acts as the mutual solvent and HCl as the deflocculating agent. For a fixed alkoxide:water:HCl ratio, the time of gel formation increased with the alcohol to alkoxide molar ratio. Thermal evolution of the physical and structural changes in the gel has been monitored by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, and infrared spectroscopy. On heating to similar to 400 degrees C, the amorphous gel crystallized into the low-temperature orthorhombic phase beta-Ta2O5, which transformed into the high-temperature tetragonal phase alpha-Ta2O5 when further heated to similar to 1450 degrees C. The volume fraction of the crystalline phase increased with the firing temperature. The alpha-Ta2O5 converted back into the low-temperature phase, beta-Ta2O5, on slow cooling through the transformation temperature of 1360 degrees C, indicating a slow but reversible transformation. RP BANSAL, NP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 14 Z9 14 U1 1 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD OCT 1 PY 1994 VL 29 IS 19 BP 5065 EP 5070 DI 10.1007/BF01151098 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA PL024 UT WOS:A1994PL02400017 ER PT J AU COOK, LS WOLFENDEN, A BRINDLEY, WJ AF COOK, LS WOLFENDEN, A BRINDLEY, WJ TI TEMPERATURE-DEPENDENCE OF DYNAMIC YOUNGS MODULUS AND INTERNAL-FRICTION IN LPPS NICRALY SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB The piezoelectric ultrasonic composite oscillator technique (PUCOT), operating near 80 kHz, was used to measure the temperature dependence, in the range 23-1000 degrees C, of dynamic Young's modulus, E, and internal friction, Q(-1), in three compositions of low-pressure plasma-sprayed NiCrAlY: Ni-15.6Cr-5.2Al-0.20Y (16-5), Ni-17.2Cr-11.6Al-0.98Y (17-12), and Ni-33Cr-6.2Al-0.95Y (33-6). Ambient temperature (23 degrees C) dynamic Young's moduli for the three alloys were 205.0, 199.8, and 231.0 GPa, respectively. In each case, dE/dT was found to be - 0.06 GPa degrees C-1 over temperature ranges 23-800, 23-400 and 600-900, and 23-700 degrees C, respectively. Internal friction was essentially independent of temperature to about 600 degrees C (700 degrees C for the 16-5 alloy), at which point a temperature dependence of the form Q(-1) = A exp( - Cl RT) was observed. The constant A for the three alloys was determined to be 62.7, 555, and 2.01 x 10(6), respectively. The constant C for the three alloys was determined to be 82.8, 111, and 170 kJ/mol(-1), respectively. While the physical mechanism is not fully understood, both the pre-exponential constant A and the activation energy C correlate with durability in thermal barrier coatings (TBCs) wherein these alloys are used as bond coats. C1 TEXAS A&M UNIV,DEPT MECH ENGN,COLLEGE STN,TX 77843. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 12 TC 21 Z9 21 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD OCT 1 PY 1994 VL 29 IS 19 BP 5104 EP 5108 DI 10.1007/BF01151103 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA PL024 UT WOS:A1994PL02400022 ER PT J AU CHEN, D ROTHSTEIN, LM BUSALACCHI, AJ AF CHEN, D ROTHSTEIN, LM BUSALACCHI, AJ TI A HYBRID VERTICAL MIXING SCHEME AND ITS APPLICATION TO TROPICAL OCEAN MODELS SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID SEA-SURFACE TEMPERATURE; MIXED-LAYER; NUMERICAL-MODELS; SEASONAL CYCLE; PACIFIC-OCEAN; PARAMETERIZATION; SIMULATION; TURBULENCE; EQUATION; BUDGET AB A novel hybrid vertical mixing scheme, based jointly on the Kraus-Turner-type mixed layer model and Price's dynamical instability model, is introduced to aid in parameterization of vertical turbulent mixing in numerical ocean models. The scheme is computationally efficient and is capable of simulating the three major mechanisms of vertical turbulent mixing in the upper ocean, that is, wind stirring, shear instability, and convective overturning. The hybrid scheme is first tested in a one-dimensional model against the Kraus-Turner-type bulk mixed layer model and the Mellor-Yamada level 2.5 (MY2.5) turbulence closure model. As compared with those two models, the hybrid model behaves more reasonably in both idealized experiments and realistic simulations. The improved behavior of the hybrid model can be attributed to its more complete physics. For example, the MY2.5 model underpredicts mixed layer depth at high latitudes due to its lack of wind stirring and penetrative convection, while the Kraus-Turner bulk model produces rather shallow mixed layers in the equatorial region because of its lack of shear-produced mixing. The hybrid model reproduces the good results of the MY2.5 model toward the equator and the bulk model toward high latitudes, thereby taking the advantages of those two models while avoiding their shortcomings. The hybrid scheme is then implemented in a three-dimensional model of the tropical Pacific Ocean. This leads to an improved simulation of the large-scale equatorial circulation. Compared with the other two commonly used mixing schemes tested in this experiment, the hybrid scheme helps to produce more realistic velocity profiles in the eastern and central equatorial Pacific. This is mainly due to the improved parameterization of interior mixing related to the large shears of the Equatorial Undercurrent. Another feature in this model that is sensitive to the vertical mixing scheme is the equatiorial instability waves; in the eastern Pacific Ocean these waves are most energetic when the hybrid scheme is used. The meridional heat flux associated with these waves can be locally important in the mixed layer heat budget. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHERE PROC LAB,GREENBELT,MD 20771. RP CHEN, D (reprint author), UNIV RHODE ISL,GRAD SCH OCEANOG,NARRAGANSETT BAY CAMPUS,NARRAGANSETT,RI 02882, USA. RI Chen, Dake/E-7082-2011 NR 24 TC 188 Z9 195 U1 0 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1994 VL 24 IS 10 BP 2156 EP 2179 DI 10.1175/1520-0485(1994)024<2156:AHVMSA>2.0.CO;2 PG 24 WC Oceanography SC Oceanography GA PL709 UT WOS:A1994PL70900009 ER PT J AU WAJSOWICZ, RC AF WAJSOWICZ, RC TI A RELATIONSHIP BETWEEN INTERANNUAL VARIATIONS IN THE SOUTH-PACIFIC WIND STRESS CURL, THE ONDINESIAN THROUGHFLOW, AND THE WEST PACIFIC WARM WATER POOL SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Note ID DEPTH-INTEGRATED FLOW; WORLD OCEAN; CIRCULATION; OSCILLATION; REFLECTION; BOUNDARY; ISLAND; MODEL AB Simple theory gives that the depth-integrated flow between the Pacific and Indian Oceans, on interannual timescales and longer, is driven by the integral of the wind stress along a line from the northern tip of Papua-New Guinea across the equatorial Pacific, south along the South American west coast, westward across the South Pacific at the latitude of the southern tip of Australia, and northward along the west coast of Australia. Evaluation of this integral using ECMWF/JMA 1000-mb wind data for the decade 1980-89 yields an interdecadal and interannual signal. The interannual signal peaks in 1981 and 1985, then decreases sharply through the ensuing ENSO events. The variations are chiefly attributable to variations in the integral of wind stress across the midlatitude line in the South Pacific. The presence of the shallow sills within the Indonesian seas will partially block the midlatitude contribution, but local baroclinic adjustment over the sills will reduce the blocking effect and produce a corresponding interannual variation in upper-layer transport through the seas. Two mechanisms by which variations in throughflow magnitude could contribute to warm water pileup in the west Pacific are proposed. RP WAJSOWICZ, RC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEAN & ICE BRANCH,MAIL CODE 971,GREENBELT,MD 20771, USA. NR 16 TC 22 Z9 25 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD OCT PY 1994 VL 24 IS 10 BP 2180 EP 2187 DI 10.1175/1520-0485(1994)024<2180:ARBIVI>2.0.CO;2 PG 8 WC Oceanography SC Oceanography GA PL709 UT WOS:A1994PL70900010 ER PT J AU LIM, HS ZELTER, GR SMITHRICK, JJ HALL, SW AF LIM, HS ZELTER, GR SMITHRICK, JJ HALL, SW TI DESTRUCTIVE PHYSICAL ANALYSIS RESULTS OF NI/H2 CELLS CYCLED IN LOW-EARTH-ORBIT REGIME .2. SO JOURNAL OF POWER SOURCES LA English DT Article ID NICKEL HYDROGEN CELLS; LIFE AB Six 48-Ah individual pressure vessel Ni/H-2 cells containing 26 and 31% KOH electrolytes have been on a low earth orbit cycle-life test. Three cells containing 31% KOH have failed after an average of 6400 cycles while the other three with 26% KOH have cycled for an average of 19 500 cycles. We have carried out post-cycle characterization tests and destructive physical analyses (DPA) of all cells. The DPA included visual inspections, measurements of electrode thickness, scanning electron microscopy, chemical analyses, and measurements of nickel electrode capacity in an electrolyte flooded cell. A gradual decrease of the usable cell capacity at high rate (1.4C) was the failure mode of all cells tested. Decrease of the usable capacity was due to decrease in the utilization of the active material with cycling mainly due to build-up of low rate capacity (residual capacity) and undischargeable active material. Cycle life of one of the cells might have been shortened prematurely due to the breakage of the cell core. Many gradual changes occurred with cycling at a rate which is independent of the KOH concentration. Each of these individual changes are difficult to be attributed to be the direct cause of the utilization decrease. However, an involved interaction of the changes might be responsible for the decrease. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. USN,CTR WEAP SUPPORT,CRANE,IN 47522. RP LIM, HS (reprint author), HUGHES AIRCRAFT CO,IND ELECTR GRP,TORRANCE,CA 90505, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD OCT PY 1994 VL 51 IS 3 BP 445 EP 456 DI 10.1016/0378-7753(94)80112-6 PG 12 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA PV282 UT WOS:A1994PV28200011 ER PT J AU WILSON, ML BUCKLEY, JD AF WILSON, ML BUCKLEY, JD TI THE POTENTIAL FOR LOW-COST THERMOPLASTIC PULTRUSION SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB For the past several years, thermoplastic pultrusion technology development has concentrated on high-performance polymers, for example: polyetheretherketone (PEEK), polyetherimide (PEI), and polyphenylene sulfide (PPS), While these polymers are more likely to find use as engineering materials for aircraft and spacecraft, lower temperature, lower cost fiber reinforced thermoplastics have a greater potential in the automotive, industrial, recreational, and building supplies markets. The present state of the art in thermoplastic pultrusion is primarily to consolidate prepreg, towpreg, or commingled fibers by pulling such materials through a die system. In using this approach, manufacturing costs have escalated. If in-line impregnation (without the use of hazardous solvents) was perfected, many of the recyclable thermoplastics recovered from municipal waste could be used in cost-effective pultrusion production lines. This paper identifies several potential pultrudable, recyclable, low cost thermoplastics and compares their mechanical properties with conventional pultruded materials. Manufacturing methodology and costs are also addressed, as well as methods for characterizing and testing of these materials. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. THERMOPLAST PULTRUS TECHNOL,YORKTOWN,VA 23693. NR 12 TC 3 Z9 3 U1 0 U2 10 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0731-6844 J9 J REINF PLAST COMP JI J. Reinf. Plast. Compos. PD OCT PY 1994 VL 13 IS 10 BP 927 EP 941 DI 10.1177/073168449401301007 PG 15 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA PJ942 UT WOS:A1994PJ94200007 ER PT J AU SINGH, D SINGH, JP MAJUMDAR, S KUPPERMAN, DS COWDIN, E BHATT, RT AF SINGH, D SINGH, JP MAJUMDAR, S KUPPERMAN, DS COWDIN, E BHATT, RT TI EFFECT OF PROCESSING VARIABLES ON INTERFACIAL PROPERTIES OF AN SIC-FIBER-REINFORCED REACTION-BONDED SI3N4 MATRIX COMPOSITE SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID CERAMIC-MATRIX; MECHANICAL-PROPERTIES; PUSHOUT TESTS; GLASS; STRENGTH; ROUGHNESS; BEHAVIOR AB Fiber/matrix interfacial debonding and frictional sliding stresses were evaluated by single-fiber pushout tests on unidirectional continuous silicon-carbide-fiber-reinforced, reaction-bonded silicon nitride matrix composites. The debonding and maximum pushout loads required to overcome interfacial friction were obtained from load-displacement plots of pushout tests. Interfacial debonding and frictional sliding stresses were evaluated for composites with various fiber contents and fiber surface conditions (coated and uncoated), and after matrix densification by hot isostatic pressing (HIPing). For as-fabricated composites, both debonding and frictional sliding stresses decreased with increasing fiber content. The HIPed composites, however, exhibited higher interfacial debonding and frictional sliding stresses than those of the as-fabricated composites. These results were related to variations in axial and transverse residual stresses on fibers in the composites. A shearlag model developed for a partially debonded composite, including full residual stress field, was employed to analyze the nonlinear dependence of maximum pushout load on embedded fiber length for as-fabricated and HIPed composites. Interfacial friction coefficients of 0.1-0.16 fitted the experimental data well. The extremely high debonding stress observed in uncoated fibers is believed to be due to strong chemical bonding between fiber and matrix. C1 NASA,LEWIS RES CTR,USA,PROPULS DIRECTORATE,CLEVELAND,OH 44035. RP SINGH, D (reprint author), ARGONNE NATL LAB,DIV ENERGY TECHNOL,ARGONNE,IL 60439, USA. NR 34 TC 13 Z9 13 U1 0 U2 5 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD OCT PY 1994 VL 77 IS 10 BP 2561 EP 2568 DI 10.1111/j.1151-2916.1994.tb04643.x PG 8 WC Materials Science, Ceramics SC Materials Science GA PM483 UT WOS:A1994PM48300010 ER PT J AU ORTIZLONGO, CR WHITE, KW AF ORTIZLONGO, CR WHITE, KW TI ELEVATED-TEMPERATURE FRACTURE CHARACTERIZATION OF ADVANCED FIBROUS CERAMIC THERMAL INSULATORS SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID CELLULAR SOLIDS; TOUGHNESS; COMPOSITE AB The elevated-temperature mechanical behavior of two low-density fibrous ceramic thermal insulators is discussed. Fracture toughness and R-curve behavior are obtained from chevron notched bend bar and short double cantilever beam specimens, respectively. The fracture behavior is related to the bulk microstructures, the properties of the fibers, and the various fiber-to-fiber bond chemistries. A strong behavioral change at elevated temperatures is linked to the glass-softening temperature of the multiphase structure characteristic of each material. C1 UNIV HOUSTON,COLL ENGN,HOUSTON,TX 77204. RP ORTIZLONGO, CR (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 38 TC 12 Z9 12 U1 0 U2 4 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD OCT PY 1994 VL 77 IS 10 BP 2703 EP 2711 DI 10.1111/j.1151-2916.1994.tb04665.x PG 9 WC Materials Science, Ceramics SC Materials Science GA PM483 UT WOS:A1994PM48300032 ER PT J AU CAGLIOSTRO, DE RICCITIELLO, SR REN, J ZAGHI, F AF CAGLIOSTRO, DE RICCITIELLO, SR REN, J ZAGHI, F TI COMPARISON OF THE PYROLYSIS PRODUCTS OF DICHLORODIMETHYLSILANE IN THE CHEMICAL-VAPOR-DEPOSITION OF SILICON-CARBIDE ON SILICA IN HYDROGEN OR ARGON SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article AB A chemical analysis of the pyrolysis gases and solids formed during the deposition of silicon carbide from the decomposition of dichlorodimethylsilane in argon and hydrogen is reported. Depositions were performed at 1 atm pressure, temperatures from 700-degrees to 1100-degrees-C, and a mean residence time of approximately 1 min. The chemical analysis shows that, under reactor conditions, the gases formed were mainly methane, hydrogen, silicon tetrachloride, trichlorosilane, and trichloromethylsilane. The presence of hydrogen chloride was not examined. The use of hydrogen, as a carrier gas, decreased the trichloromethylsilane and solid aerosol (smoke) in the reaction products, compared to that present in the argon system, and increased methane, trichlorosilane, and silicon production. Primarily, silicon and silicon carbide were deposited when hydrogen was used as the carrier gas. When argon was used, a complex mixture of silicon carbide and organosilicon compounds was formed. It is hypothesized that, when hydrogen was used as the carrier gas, silicon carbide formed from chlorosilanes and methane, which were products from the decomposition of dichlorodimethylsilane. These products subsequently reacted to form silicon, which then reacted with methane to form silicon carbide. In argon, however, it is hypothesized that silicon carbide can be formed in two ways: (1) from the pyrolysis of solid organosilicon compounds which are products from the pyrolysis of dichlorodimethylsilane in argon and (2) as the reduction of dichlorodimethylsilane to chlorosilanes and methane, caused by the hydrogen produced from the pyrolysis of dichlorodimethylsilane in argon. C1 DEANZA COLL,CUPERTINO,CA 95014. SAN JOSE STATE UNIV,DEPT MAT SCI,SAN JOSE,CA 95192. RP CAGLIOSTRO, DE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 15 Z9 15 U1 0 U2 4 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD OCT PY 1994 VL 77 IS 10 BP 2721 EP 2726 DI 10.1111/j.1151-2916.1994.tb04667.x PG 6 WC Materials Science, Ceramics SC Materials Science GA PM483 UT WOS:A1994PM48300034 ER PT J AU SPLETTSTOESSER, WR SCHULTZ, KJ KUBE, R BROOKS, TF BOOTH, ER NIESL, G STREBY, O AF SPLETTSTOESSER, WR SCHULTZ, KJ KUBE, R BROOKS, TF BOOTH, ER NIESL, G STREBY, O TI A HIGHER HARMONIC CONTROL TEST IN THE DNW TO REDUCE IMPULSIVE BVI NOISE SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A model rotor acoustic test was performed to examine the benefit of higher harmonic control (HHC) of blade pitch to reduce blade-vortex interaction (BVI) impulsive noise. A 40-percent dynamically scaled, four-bladed model of a BO-105 main rotor was tested in the German-Dutch Wind Tunnel (DNW). Acoustic measurements were made in a large plane underneath the rotor employing a traversing in-flow microphone array in the anechoic environment of the open test section. Noise characteristics and noise directivity patterns as well as vibratory loads were measured and used to demonstrate the changes when different HHC schedules (different modes, amplitudes, phases) were applied. Dramatic changes of the acoustic signatures and the noise radiation directivity with HHC phase variations are found. Compared to the baseline conditions (without HHC), significant mid-frequency noise reductions of as much as 6 dB are obtained for low speed descent conditions where BVI is most intense, For other rotor operating conditions with less intense BVI there is less or no benefit from the use of HHC. Low frequency loading noise and vibratory loads, especially at optimum noise reduction control settings, are found to increase. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. ECD,OTTOBRUNN,GERMANY. ECF,MARIGNANE,FRANCE. RP SPLETTSTOESSER, WR (reprint author), DLR,RES CTR,BRAUNSCHWEIG,GERMANY. NR 23 TC 6 Z9 7 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 1994 VL 39 IS 4 BP 3 EP 13 PG 11 WC Engineering, Aerospace SC Engineering GA RN423 UT WOS:A1994RN42300001 ER PT J AU COVERSTONECARROLL, V WILLIAMS, SN AF COVERSTONECARROLL, V WILLIAMS, SN TI OPTIMAL LOW THRUST TRAJECTORIES USING DIFFERENTIAL INCLUSION CONCEPTS SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article AB A direct optimization method based on differential inclusion concepts has been developed and used to compute low thrust trajectories. This new formulation removes explicit control dependence from the problem statement thereby reducing the dimension of the parameter space of the resulting nonlinear programming problem. A simple example of a two-dimensional gravity-free trajectory involving a maximum velocity transfer to a rectilinear path is discussed. Three interplanetary trajectory examples, an Earth-Mars constant specific impulse transfer, an Earth-Jupiter constant specific impulse transfer, and an Earth-Venus-Mars variable specific impulse gravity assist, are also included. An evaluation of the technique's performance is provided. C1 CALTECH,JET PROP LAB,MISS DESIGN SECT,PASADENA,CA 91109. RP COVERSTONECARROLL, V (reprint author), UNIV ILLINOIS,DEPT AERONAUT & ASTRONAUT ENGN,URBANA,IL 61801, USA. NR 11 TC 38 Z9 41 U1 1 U2 2 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 1994 VL 42 IS 4 BP 379 EP 393 PG 15 WC Engineering, Aerospace SC Engineering GA QX364 UT WOS:A1994QX36400001 ER PT J AU BEGAULT, DR ERBE, T AF BEGAULT, DR ERBE, T TI MULTICHANNEL SPATIAL AUDITORY DISPLAY FOR SPEECH COMMUNICATIONS SO JOURNAL OF THE AUDIO ENGINEERING SOCIETY LA English DT Article ID FREE-FIELD; LEVEL AB A spatial auditory display for multiple speech communications was developed at NASA/Ames Research Center. Input is spatialized by the use of simplified head-related transfer functions, adapted for FIR filtering on Motorola 56001 digital signal processors. Hardware and firmware design implementations are overviewed for the initial prototype developed for NASA-Kennedy Space Center. An adaptive staircase method was used to determine intelligibility levels of four-letter call signs used by launch personnel at NASA against diotic speech babble. Spatial positions at 30-degrees azimuth increments were evaluated. The results from eight subjects showed a maximum intelligibility improvement of about 6-7 dB when the signal was spatialized to 60 or 90-degrees azimuth positions. C1 CALIF INST ARTS,SCH MUS,VALENCIA,CA 91355. RP BEGAULT, DR (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,HUMAN INTERFACE BRANCH,MOFFETT FIELD,CA 94035, USA. NR 25 TC 10 Z9 10 U1 5 U2 6 PU AUDIO ENGINEERING SOC PI NEW YORK PA 60 E 42ND ST, NEW YORK, NY 10165-2520 SN 0004-7554 J9 J AUDIO ENG SOC JI J. Audio Eng. Soc. PD OCT PY 1994 VL 42 IS 10 BP 819 EP 825 PG 7 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA PP705 UT WOS:A1994PP70500005 PM 11539275 ER PT J AU PANZARELLA, CH KASSEMI, M AF PANZARELLA, CH KASSEMI, M TI PROPORTIONAL-INTEGRAL-DERIVATIVE-CONTROLLED NUMERICAL-MODEL FOR THE PROGRAMMABLE MULTIZONE FURNACE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID CZOCHRALSKI CRYSTAL-GROWTH; HEAT-TRANSFER AB This article presents a two-dimensional axisymmetric combined conduction and radiation model for the prototype of the programmable multizone furnace, which is under design at NASA Lewis Research Center. The actual furnace is intended for growing high-quality semiconductor crystals and performing other materials processing experiments in space. A novel feature of the model is a control algorithm that automatically adjusts the power in any number of independently controlled heaters to establish the desired sample temperatures during the numerical simulations. The control algorithm eliminates the need for numerous trial and error runs previously required to obtain the same results. The finite element code, FIDAP, was modified to directly incorporate the control algorithm. This algorithm, which presently uses proportional-integral-derivative (PID) control, and the associated heat transfer model are briefly discussed. Together, they have been used to predict the heater power distributions for a variety of furnace configurations and desired temperature profiles. Examples are included to demonstrate the effectiveness of the PID-controlled model in establishing isothermal, Bridgman, and other complicated temperature profiles in the sample. An example is also given to show how the algorithm can be used to change the desired profile with time according to a prescribed temperature-time evolution. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 12 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 670 EP 677 DI 10.2514/3.597 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800006 ER PT J AU MILOS, FS SHEPARD, CE AF MILOS, FS SHEPARD, CE TI THERMAL-ANALYSIS OF AN ARC-HEATER ELECTRODE WITH A ROTATING ARC FOOT SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT AB Analytic formulations are presented for the analysis of an arc-heater electrode with a rotating arc foot. Two limiting cases, a smoothly rotating arc foot and an arc foot that jumps between multiple sticking points, are analyzed. For each case the temperature distribution for a copper electrode is obtained for the plausible range of operating conditions. It is shown that the smoothly rotating arc foot is an extremely safe mode of operation, whereas the jumping arc foot produces excessively high electrode surface temperatures. It is suggested to eliminate arc-foot rotation and rely on a distribution of fixed electrodes with stationary arc attachment to avoid electrode failure at high current. C1 ELORET INST,INST THERMOSCI,PALO ALTO,CA 94303. RP MILOS, FS (reprint author), NASA,AMES RES CTR,THERMAL PROTECT MAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 13 TC 4 Z9 4 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 723 EP 729 DI 10.2514/3.604 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800013 ER PT J AU DURGAPAL, P PALMER, G AF DURGAPAL, P PALMER, G TI STRONGLY COUPLED RADIATIVE-TRANSFER AND JOULE HEATING IN AN ARC HEATER CATHODE SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Radiation and joule heating in the electrode region of an arc heater are discussed. Radiative transport equations for a true axisymmetric geometry are used. A subsonic code is developed to numerically solve the fluid equations with strongly coupled radiation, del . q(r) and Joule heating j . E, representative of a high-pressure and high-current arc heater. Analytic expression for the divergence of radiative heat flux derived in a previous paper is used. Jacobians of the radiation term are derived. The Joule heating term is computed using a previouslv developed code. The equilibrium gas model consists of seven species. The fluxes are differenced using Van Leer flux splitting. Using this code the effects of radiative cooling on the thermodynamic parameters of the arc core are discussed. RP NASA, AMES RES CTR, INST THERMOSCI, MOFFETT FIELD, CA 94035 USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 EI 1533-6808 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 730 EP 736 DI 10.2514/3.605 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800014 ER PT J AU BABIKIAN, DS GOPAUL, NKJM PARK, C AF BABIKIAN, DS GOPAUL, NKJM PARK, C TI MEASUREMENT AND ANALYSIS OF NITRIC-OXIDE RADIATION IN AN ARCJET FLOW SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT AB Radiation from the nitric oxide (NO) band systems emitted by the flow in the test section of a 20-MW arcjet wind tunnel was measured and compared with the computed values for the purpose of testing the validity of an existing thermochemical model. The settling chamber pressure and enthalpy were 2.4 atm and 28 +/- 10 MJ/kg, respectively. The measurements were made using photographic films in the wavelength region from 225 to 305 nm. Of the four band systems of NO (beta, gamma, delta, and epsilon), vibrational transitions were observed from only the upper v' = 0 levels. Excitation temperatures were deduced by comparing the experimental spectrum with those calculated using the nonequilibrium radiation code NEQAIR. The rotational, vibrational, and electronic excitation temperatures deduced from the data were T(r) = 560 +/- 50 K, T(v) less-than-or-equal-to 950 +/- 50 K, and T(ex) = 11,500 +/- 520 K, respectively. A multitemperature nonequilibrium nozzle flow code NOZNT was used to calculate the nozzle flow. The calculated temperatures were T(r) = 560 K, T(v) = 950 K, and electron thermal temperature T(e) = 6100 K, respectively at 30 MJ/kg. The presented results show that by using the centerline enthalpy value deduced from heat transfer measurement and the NOZNT code, one can predict the freestream conditions in an arcjet wind-tunnel flow fairly well. RP BABIKIAN, DS (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035, USA. NR 28 TC 12 Z9 12 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 737 EP 743 DI 10.2514/3.606 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800015 ER PT J AU HAAS, BL FALLAVOLLITA, MA AF HAAS, BL FALLAVOLLITA, MA TI FLOW RESOLUTION AND DOMAIN INFLUENCE IN RAREFIELD HYPERSONIC BLUNT-BODY FLOWS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB This parametric study assesses the influence of upstream domain size and grid resolution upon flowfield properties and body aerodynamics computed for rarefied flows over cold blunt bodies with a direct simulation Monte Carlo (DSMC) particle method. Empirical correlations are suggested for aerodynamic coefficients for two-dimensional flows past a perpendicular flat plate. Freestream parameters that were varied in the study include the Mach number, Knudsen number, surface temperature, and intermolecular potential. Insufficient grid resolution leads to overprediction of aerodynamic heating and forces in the DSMC method. Molecular diffusion from the body surface results in greater far-field domain influence as flow rarefaction increases. As a result, insufficient upstream domain size in the DSMC method leads to overprediction of heating and drag. Simulation of a hard sphere gas is more sensitive to grid resolution, whereas simulation of a Maxwell gas is more sensitive to upstream domain size. Finally, a simple study of normal shock waves indicates that a grid cell dimension less than one-third of the upstream mean free path is required to capture shock profiles accurately. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. RP HAAS, BL (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035, USA. NR 11 TC 6 Z9 8 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 751 EP 757 DI 10.2514/3.608 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800017 ER PT J AU HASH, DB MOSS, JN HASSAN, HA AF HASH, DB MOSS, JN HASSAN, HA TI DIRECT SIMULATION OF DIATOMIC GASES USING THE GENERALIZED HARD-SPHERE MODEL SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID MONTE-CARLO SIMULATION; ROTATIONAL RELAXATION; COLLISION AB The generalized hard sphere model that incorporates the effects of attraction and repulsion is examined. First, the model is used to study simple adiabatic heat baths. Then, it is used to predict now measurements in tests involving extremely low freestream temperatures. For the two cases considered, a Mach 26 nitrogen shock and a Mach 20 nitrogen flow over a flat plate, only rotational excitation is deemed important, and appropriate modifications for the Borgnakke-Larsen procedure are developed. In general, for the cases considered, the present model showed a modest improvement over the variable hard sphere model. C1 NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665. RP HASH, DB (reprint author), N CAROLINA STATE UNIV,RALEIGH,NC 27695, USA. NR 21 TC 14 Z9 14 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 758 EP 764 DI 10.2514/3.609 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800018 ER PT J AU JUSTIZ, CR SEGA, RM DALTON, C IGNATIEV, A AF JUSTIZ, CR SEGA, RM DALTON, C IGNATIEV, A TI DSMC-BASED AND BGK-BASED CALCULATIONS FOR RETURN FLUX CONTAMINATION OF AN OUTGASSING SPACECRAFT SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note C1 UNIV HOUSTON,CULLEN COLL ENGN,HOUSTON,TX 77204. UNIV HOUSTON,CTR SPACE VACUUM EPITAXY,HOUSTON,TX 77204. RP JUSTIZ, CR (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 7 TC 5 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 1994 VL 8 IS 4 BP 802 EP 803 DI 10.2514/3.617 PG 2 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PL528 UT WOS:A1994PL52800026 ER PT J AU JOHNSON, BV WAGNER, JH STEUBER, GD YEH, FC AF JOHNSON, BV WAGNER, JH STEUBER, GD YEH, FC TI HEAT-TRANSFER IN ROTATING SERPENTINE PASSAGES WITH SELECTED MODEL ORIENTATIONS FOR SMOOTH OR SKEWED TRIP WALLS SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 38th International Gas Turbine and Aeroengine Congress and Exposition CY MAY 24-27, 1993 CL CINCINNATI, OH SP INT GAS TURBINE INST AB Experiments were conducted to determine the effects of model orientation as well as buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. Turbine blades have internal coolant passage surfaces at the leading and trailing edges of the airfoil with surfaces at angles that are as large as +/-50 to 60 deg to the axis of rotation. Most of the previously presented, multiple-passage, rotating heat transfer experiments have focused on radial passages aligned with the axis of rotation. The present work compares results from serpentine passages with orientations 0 and 45 deg to the axis of rotation, which simulate the coolant passages for the midchord and trailing edge regions of the relating airfoil. The experiments were conducted with rotation in both directions to simulate serpentine coolant passages with the rearward flow of coolant or with the forward flow of coolant. The experiments were conducted for passages with smooth surfaces and with 45 deg trips adjacent to airfoil surfaces for the radial portion of the serpentine passages. At a typical flow condition, the heat transfer on the leading surfaces for flow outward in the first passage with smooth walls was twice as much for the model at 45 deg compared to the model at 0 deg. However, the differences for the other passages and with trips were less. In addition, the effects of buoyancy and Coriolis forces on heat transfer in the rotating passage were decreased with the model at 45 deg, compared to the results at 0 deg. The hear transfer in the turn regions and immediately downstream of the turns in the second passage with flow inward and in the third passage with flow outward was also a function of model orientation with differences as large as 40 to 50 percent occurring between the model orientations with forward flow and rearward flow of coolant. C1 PRATT & WHITNEY,E HARTFORD,CT 06108. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP JOHNSON, BV (reprint author), UNITED TECHNOL RES CTR,E HARTFORD,CT 06108, USA. NR 15 TC 35 Z9 37 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 1994 VL 116 IS 4 BP 738 EP 744 DI 10.1115/1.2929467 PG 7 WC Engineering, Mechanical SC Engineering GA PP430 UT WOS:A1994PP43000023 ER PT J AU BOYLE, RJ AF BOYLE, RJ TI PREDICTION OF SURFACE-ROUGHNESS AND INCIDENCE EFFECTS ON TURBINE PERFORMANCE SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 38th International Gas Turbine and Aeroengine Congress and Exposition CY MAY 24-27, 1993 CL CINCINNATI, OH SP INT GAS TURBINE INST ID FLOWS AB The use of a Navier-Stokes analysis to predict the change in turbine efficiency resulting from changes in blade surface roughness or incidence flow angles is discussed. The results of a midspan Navier-Stokes analysis are combined with those from a quasi-three-dimensional flow analysis code to predict turbine performance. A quasi-three-dimensional flow analysis code was used to determine turbine performance over a range of incidence flow angles. This analysis was done for a number of incidence loss models. The change in loss due to changes in incidence flow computed from the Navier-Stokes analysis is compared with the results obtained using the empirical loss models. The Navier-Stokes analysis was also used to determine the effects of surface roughness using a mixing length turbulence model, which incorporated the roughness height. The validity of the approach used was verified by comparisons with experimental data for a turbine with both smooth and rough blades tested over a wide range of blade incidence flow angles. RP BOYLE, RJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 21 TC 12 Z9 12 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 1994 VL 116 IS 4 BP 745 EP 751 DI 10.1115/1.2929468 PG 7 WC Engineering, Mechanical SC Engineering GA PP430 UT WOS:A1994PP43000024 ER PT J AU THIELE, L CHOW, E AF THIELE, L CHOW, E TI APPLICATION-SPECIFIC ARRAY PROCESSORS (ASAP-92) SO JOURNAL OF VLSI SIGNAL PROCESSING LA English DT Editorial Material C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP THIELE, L (reprint author), UNIV SAARLAND,LEHRSTUHL MIKROELEKTR,D-66041 SAARBRUCKEN,GERMANY. NR 0 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 0922-5773 J9 J VLSI SIGNAL PROC JI J. VLSI Signal Process. PD OCT PY 1994 VL 8 IS 2 BP 95 EP 95 DI 10.1007/BF02109377 PG 1 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PZ676 UT WOS:A1994PZ67600001 ER PT J AU GOLUB, MA LOPATA, ES FINNEY, LS AF GOLUB, MA LOPATA, ES FINNEY, LS TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF ARGON-PLASMA-TREATED FLUOROPOLYMERS SO LANGMUIR LA English DT Article ID POLYMER SURFACES; HYDROCARBON CONTAMINATION; GRAFT-COPOLYMERIZATION; GLOW-DISCHARGE; OXYGEN PLASMA; POLY(TETRAFLUOROETHYLENE); ETHYLENE; TEFLON; PTFE; ESCA AB Films of poly(tetrafluoroethylene) (PTFE) and of a tetrafluoroethylene-perfluoroalkyl vinyl ether(approximate to 49:1) copolymer (PFA) were exposed to a radio-frequency argon plasma and then examined by X-ray photoelectron spectroscopy (XPS). The use of fluoropolymer films nearly free of surface hydrocarbon contamination as well as the use of a monochromatized X-ray source for XPS removed two factors contributing to conflicting reports on the effect of exposure time on the fluorine-to-carbon (F/C) and oxygen-to-carbon (O/C) ratios for several Ar-plasma-treated fluoropolymers. Contrary to literature indications, a common pattern was found for PTFE and PFA: a moderate decrease in F/C ratio (from 1.99 to 1.40, and from 1.97 to 1.57, respectively), together with a moderate increase in O/C ratio (from negligible to approximate to 0.10, and from 0.012 to approximate to 0.10, respectively) at very short exposures, after which the F/C ratios remained essentially constant on prolonged exposures, while the O/C ratios for PTFE and PFA leveled off at 0.11 and 0.15, respectively. The XPS C-1s, spectra for these polymers exposed to the Ar plasma for 20 min were similar and presented, besides a prominent peak at 292.0 eV (CF2) and a minor peak at 294.0 or 294.1 eV (CF3), a composite band of four curve-resolved peaks (approximate to 285 - 290 eV) representing various CH, CC, CO, CN, and CF functionalities. C1 HIMONT PLASMA SCI,FOSTER CITY,CA 94404. SURFACE SCI LABS,MT VIEW,CA 94043. RP GOLUB, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 TC 40 Z9 40 U1 3 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD OCT PY 1994 VL 10 IS 10 BP 3629 EP 3634 DI 10.1021/la00022a041 PG 6 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA PN287 UT WOS:A1994PN28700041 ER PT J AU MULLIN, KD HIGGINS, LV JEFFERSON, TA HANSEN, LJ AF MULLIN, KD HIGGINS, LV JEFFERSON, TA HANSEN, LJ TI SIGHTINGS OF THE CLYMENE DOLPHIN (STENELLA CLYMENE) IN THE GULF-OF-MEXICO SO MARINE MAMMAL SCIENCE LA English DT Note C1 TEXAS A&M UNIV,DEPT WILDLIFE & FISHERIES SCI,MARINE MAMMAL RES PROGRAM,COLLEGE STN,TX 77843. RP MULLIN, KD (reprint author), NOAA,NATL MARINE FISHERIES SERV,CTR SE FISHERIES SCI,PO DRAWER 1207,PASCAGOULA,MS 39568, USA. NR 18 TC 12 Z9 13 U1 0 U2 2 PU SOC MARINE MAMMALOGY PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 SN 0824-0469 J9 MAR MAMMAL SCI JI Mar. Mamm. Sci. PD OCT PY 1994 VL 10 IS 4 BP 464 EP 470 DI 10.1111/j.1748-7692.1994.tb00502.x PG 7 WC Marine & Freshwater Biology; Zoology SC Marine & Freshwater Biology; Zoology GA PP912 UT WOS:A1994PP91200007 ER PT J AU GUERRA, DV COYLE, DB KREBS, DJ AF GUERRA, DV COYLE, DB KREBS, DJ TI A COMPLETELY SOLID-STATE TI-SAPPHIRE LASER SYSTEM FOR LIDAR AND ATMOSPHERIC SPECTROSCOPY SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Note AB Since many NASA lidar missions have restrictions on the weight, power and size of the instruments employed, we have designed and constructed a compact, completely solid state, passively cooled, tunable laser system. This Ti:sapphire-based laser system is pumped with a frequency-doubled, diode-pumped Nd:YAG laser and exhibits a tuning range 750-800 nm. The resulting Ti:sapphire radiation has a peak pulse energy of 0.218 mJ in a 16.8 ns gain-switched pulse, when pumped with 0.95 mJ of doubled Nd:YAG radiation of the same pulsewidth. Potassium titanyl phosphate, a nonlinear type II doubler, is used to shift the Nd:YAG radiation from 1064 to 532 nm with 50% doubling efficiency. Overall, the system exhibits an optical-to-optical efficiency of 0.5% from the pump diodes to the Ti:sapphire output. We have also demonstrated close agreement between our experimental results and theoretical modelling of the system. This firm understanding gives us the ability to scale the system to meet laser requirements for specific missions. RP NASA, GODDARD SPACE FLIGHT CTR, NATL RES COUNCIL, CODE 715, GREENBELT, MD 20771 USA. NR 6 TC 4 Z9 4 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-0233 EI 1361-6501 J9 MEAS SCI TECHNOL JI Meas. Sci. Technol. PD OCT PY 1994 VL 5 IS 10 BP 1306 EP 1308 DI 10.1088/0957-0233/5/10/017 PG 3 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PN056 UT WOS:A1994PN05600017 ER PT J AU COTTON, JD NOEBE, RD AF COTTON, JD NOEBE, RD TI DISCUSSION OF THE ROLE OF MICROSTRUCTURE ON STRENGTH AND DUCTILITY OF HOT-EXTRUDED MECHANICALLY ALLOYED NIAL SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Note ID DEFORMATION MECHANISMS; TEMPERATURE; TENSILE; SLIP; TEXTURE C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP COTTON, JD (reprint author), LOS ALAMOS NATL LAB,DIV MAT SCI & TECHNOL,LOS ALAMOS,NM 87545, USA. NR 21 TC 0 Z9 0 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 1994 VL 25 IS 10 BP 2303 EP 2304 DI 10.1007/BF02652330 PG 2 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA PH400 UT WOS:A1994PH40000023 ER PT J AU TAUB, SR ALTEROVITZ, SA AF TAUB, SR ALTEROVITZ, SA TI SILICON TECHNOLOGIES ADJUST TO RF APPLICATIONS SO MICROWAVES & RF LA English DT Article RP TAUB, SR (reprint author), NASA,LEWIS RES CTR,TECH STAFF,CLEVELAND,OH 44135, USA. NR 0 TC 6 Z9 6 U1 0 U2 0 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0745-2993 J9 MICROWAVES RF JI Microw. RF PD OCT PY 1994 VL 33 IS 10 BP 60 EP & PG 0 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PM973 UT WOS:A1994PM97300008 ER PT J AU CHARNLEY, SB MILLAR, TJ AF CHARNLEY, SB MILLAR, TJ TI THE CHEMISTRY OF PHOSPHORUS IN HOT MOLECULAR CORES SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE MOLECULAR PROCESSES; ISM, CLOUDS; DUST, EXTINCTION; ISM, MOLECULES ID INTERSTELLAR PN; CLOUDS; IONS AB Hot molecular cores in star-forming regions are known to have gas-phase chemical compositions determined by the material evaporated from the icy mantles of interstellar grains, followed by subsequent reactions in the gas phase. Current models suggest that the evaporated material is rich in hydrogenated species. In this paper, we consider the chemistry induced in a hot core by the release of phosphine, PH3 from interstellar grains. We find that PH3 is rapidly destroyed by a series of reactions with atomic hydrogen and is converted, within 10(4) yr, into atomic P, and PO and PN, with P atoms being the most abundant species. Other P-bearing molecules can be formed in the hot gas, but on time-scales that are long compared to those of the hot cores. C1 UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV MANCHESTER,INST SCI & TECHNOL,DEPT MATH,MANCHESTER M60 1QD,LANCS,ENGLAND. RP CHARNLEY, SB (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS 245-3,MOFFETT FIELD,CA 94035, USA. RI Charnley, Steven/C-9538-2012 NR 22 TC 39 Z9 39 U1 1 U2 2 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 1 PY 1994 VL 270 IS 3 BP 570 EP 574 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ863 UT WOS:A1994PJ86300011 ER PT J AU SANTOSLLEO, M CLAVEL, J BARR, P GLASS, IS PELAT, D PETERSON, BM REICHERT, G AF SANTOSLLEO, M CLAVEL, J BARR, P GLASS, IS PELAT, D PETERSON, BM REICHERT, G TI MULTIFREQUENCY MONITORING OF THE SEYFERT-1 GALAXY NGC-4593 .1. ISOLATING THE NUCLEAR-EMISSION SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE GALAXIES, INDIVIDUAL, NGC 4593; GALAXIES, NUCLEI; GALAXIES, SEYFERT; INFRARED, GALAXIES; ULTRAVIOLET, GALAXIES; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; HARD X-RAY; ENERGY-DISTRIBUTIONS; SURFACE PHOTOMETRY; STELLAR COMPONENTS; SPIRAL GALAXIES; UV-SPECTRUM; FE-II; VARIABILITY; ULTRAVIOLET AB We present data obtained within a campaign to monitor spectral variations in the low-luminosity Seyfert 1 galaxy NGC 4593, at X-ray, ultraviolet, optical and near-IR (J, H, K and L) frequencies. The different 'parasitic' contributions that contaminate the pure nuclear continuous emission have been isolated and modelled. The light from the composite stellar population and the dust in the bulge and disc of the underlying galaxy are characterized by a spectral energy distribution similar to that of the Sb spiral M31. Its surface brightness profile is modelled with two components and provides the luminosity through any given aperture. Stars are responsible for as much as 70-85 per cent of the 5600-Angstrom flux through a 4 x 4 arcsec(2) square aperture. The 'small bump' which characterizes the spectral energy distribution of active nuclei in the 2000-4000 Angstrom range is well accounted for by many blended broad Fe II lines plus Balmer continuum emission. On average similar to 64 per cent of the total 2710-Angstrom flux is due to Fe II plus Balmer emission. Almost half of the broad-line cooling is due to Fe II line emission. The pattern of variability of the pure nuclear continuum, as well as the broad lines and their implications, is discussed in an accompanying paper. C1 ESA,IUE OBSERV,E-28080 MADRID,SPAIN. ESTEC,ISO OBSERV,2200 AG NOORDWIJK,NETHERLANDS. S AFRICAN ASTRON OBSERV,CAPE TOWN 7935,SOUTH AFRICA. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SANTOSLLEO, M (reprint author), OBSERV PARIS,DAEC,F-92195 MEUDON,FRANCE. NR 70 TC 13 Z9 13 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 1 PY 1994 VL 270 IS 3 BP 580 EP 596 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PJ863 UT WOS:A1994PJ86300013 ER PT J AU FAIRLIE, TDA TURNER, RE SISKIND, DE AF FAIRLIE, TDA TURNER, RE SISKIND, DE TI TRANSPORT CHARACTERISTICS OF A FINITE-DIFFERENCE DYNAMICS MODEL COMBINED WITH A SPECTRAL TRANSPORT MODEL OF THE MIDDLE ATMOSPHERE SO MONTHLY WEATHER REVIEW LA English DT Article ID VORTICITY AB A three-dimensional off-line spectral transport model has been combined with a global, mechanistic. finite-difference dynamics model of the middle atmosphere in order to study transport and photochemistry in the middle atmosphere for specific, observed episodes. In this paper, the basic transport characteristics of the combined models are examined, first using steady, idealized flow fields and second using time-dependent flow fields closely related to observed atmospheric behavior. Transport conducted with the combined models is found to compare favorably with transport conducted on-line in the dynamics model, given appropriate time averaging of the flow fields and suitable choice of artificial diffusion. C1 SCI & TECHNOL CORP,HAMPTON,VA. RP FAIRLIE, TDA (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 401 B,HAMPTON,VA 23681, USA. NR 23 TC 2 Z9 2 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 1994 VL 122 IS 10 BP 2363 EP 2375 DI 10.1175/1520-0493(1994)122<2363:TCOAFD>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PG580 UT WOS:A1994PG58000009 ER PT J AU FERRANTE, J BOYD, JE AF FERRANTE, J BOYD, JE TI PARTNERSHIPS FOR PROGRESS IN INNER-CITY SCHOOLS SO MRS BULLETIN LA English DT Article RP FERRANTE, J (reprint author), NASA,LEWIS RES CTR,MS 5-9,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0883-7694 J9 MRS BULL JI MRS Bull. PD OCT PY 1994 VL 19 IS 10 BP 63 EP 64 PG 2 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA PR910 UT WOS:A1994PR91000013 ER PT J AU WILSON, JW SHINN, JL TOWNSEND, LW TRIPATHI, RK BADAVI, FF CHUN, SY AF WILSON, JW SHINN, JL TOWNSEND, LW TRIPATHI, RK BADAVI, FF CHUN, SY TI NUCFRG2 - A SEMIEMPIRICAL NUCLEAR FRAGMENTATION MODEL SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article ID HEAVY-ION COLLISIONS; CROSS-SECTIONS; RELATIVISTIC NUCLEI; CARBON TARGETS; HYDROGEN; HELIUM; FE-56 AB The semiempirical abrasion/ablation model has been successful in generating a large nuclear data base for use in the study of high charge and energy (HZE) ion beams, radiation physics and galactic cosmic ray shielding. The cross sections generated agree with the measured HZE fragmentation data to the degree that different experimental groups agree among themselves. Several improvements in the model have been made including a Coulomb trajectory correction, an improved treatment of nuclear attenuation factors, an improved second order correction to the spectator fragment excitation spectrum, a pre-equilibrium emission process, and competitive equilibrium emission of additional hydrogen and helium isotope fragments. C1 CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA 23601. OLD DOMINION UNIV,NORFOLK,VA 23508. RP WILSON, JW (reprint author), NASA,LANGLEY RES CTR,DIV MAT,MAIL STOP 493,HAMPTON,VA 23681, USA. NR 26 TC 68 Z9 70 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD OCT PY 1994 VL 94 IS 1-2 BP 95 EP 102 DI 10.1016/0168-583X(94)95662-6 PG 8 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA PL518 UT WOS:A1994PL51800013 PM 11541190 ER PT J AU WINSKE, D HESSE, M AF WINSKE, D HESSE, M TI HYBRID MODELING OF MAGNETIC RECONNECTION IN-SPACE PLASMAS SO PHYSICA D LA English DT Article; Proceedings Paper CT 13th Annual International Conference of the Center-for-Nonlinear-Studies CY MAY 17-21, 1993 CL LOS ALAMOS, NM SP LOS ALAMOS NATL LAB, CTR NONLINEAR STUDIES ID SIMULATIONS; INSTABILITIES; MAGNETOTAIL; MECHANISM AB Reconnection of magnetic fields is one of the most fundamental and important transport processes in plasma physics, being a very efficient mechanism for converting magnetic field energy into particle energy. In this paper we investigate reconnection using two-dimensional hybrid simulations, in which the ions are treated kinetically and the electrons as a massless fluid. We discuss the details of the model, the need to include the complete electron pressure tenser, and issues associated with numerical implementation. We describe the results of simulations showing the Linear growth of the collisionless ion tearing mode in a neutral sheet configuration and its subsequent nonlinear development. The consequences of reconnection for magnetospheric physics are also briefly discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WINSKE, D (reprint author), LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545, USA. RI Hesse, Michael/D-2031-2012 NR 22 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2789 J9 PHYSICA D JI Physica D PD OCT 1 PY 1994 VL 77 IS 1-3 BP 268 EP 275 DI 10.1016/0167-2789(94)90139-2 PG 8 WC Mathematics, Applied; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA PJ981 UT WOS:A1994PJ98100017 ER PT J AU BRAGE, T FISCHER, CF AF BRAGE, T FISCHER, CF TI SPLINE-GALERKIN METHODS APPLIED TO RYDBERG SERIES BETWEEN THE 4S(2)S AND 3D(2)D LIMITS OF CALCIUM SO PHYSICAL REVIEW A LA English DT Article ID DOUBLE-ELECTRON RESONANCES; CA-I; NEUTRAL CALCIUM; OSCILLATOR STRENGTH; STATES; PHOTOIONISATION; SPECTROSCOPY; HE AB The recently introduced nonvariational spline-Galerkin method [T. Brage and C. Froese Fischer, Phys. Scr. 49, 651 (1994)] for Rydberg series is applied to the J = 0, 1, 2, and 3 even states between the two first limits in neutral calcium. Energies for 3dnl levels up to n = 15-20 are reported and the position of different perturbers belonging to the 4 p2 and 4p 5p configurations are investigated. The 4p 5p P-1(1) level is predicted to have an excitation energy of about 61 200 cm-1 and the 4p 5p 3D level is predicted at about 61 600-62 000 cm-1, while the 4p 5p 3P is just at the 3d2D limit. C1 VANDERBILT UNIV,NASHVILLE,TN 37235. RP BRAGE, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,CODE 681,GREENBELT,MD 20771, USA. OI Brage, Tomas/0000-0003-3985-767X NR 30 TC 11 Z9 11 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 1994 VL 50 IS 4 BP 2937 EP 2947 DI 10.1103/PhysRevA.50.2937 PG 11 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PL627 UT WOS:A1994PL62700028 ER PT J AU BALIYAN, KS BHATIA, AK AF BALIYAN, KS BHATIA, AK TI ELECTRON-IMPACT COLLISION STRENGTHS FOR NEUTRAL FLUORINE SO PHYSICAL REVIEW A LA English DT Article ID GENERAL PROGRAM; CALCULATE AB Configuration-interaction wave functions are constructed for the lowest 11 atomic target states of neutral fluorine. These wave functions are used to calculate target-state energies and absorption oscillator strengths for the dipole-allowed transitions. In general, a good agreement is found between the length and velocity forms of f values. However, f values for some transitions show significant discrepancies between these two forms. All these target states are retained in the R-matrix basis function and the (N + 1)-electron collision wave functions are expanded in terms of these basis functions. The calculations are performed for the electron-impact excitation collision strengths for all transitions between these states using the R-matrix method. In the low-partial-wave region (total angular momentum L less-than-or-equal-to 12) the full exchange R-matrix method is employed while a no-exchange R-matrix method is used for the calculations in the partial-wave region with 13 less-than-or-equal-to L less-than-or-equal-to 40. The effect of this procedure is most evident in the case of dipole-forbidden transitions for which collision strengths increase by about 10-60 % due to the contribution from higher partial waves. Beyond this value of the total angular momentum, the Burgess sum rule is applied to determine the higher partial-wave contribution to the total collision strengths for dipole-allowed transitions. The collision strengths are obtained for a wide range of incident electron energy from the first excitation threshold to 3.0 Ry. The calculations are performed in the LS-coupling scheme. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. OI /0000-0003-0180-8231 NR 18 TC 12 Z9 12 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 1994 VL 50 IS 4 BP 2981 EP 2988 DI 10.1103/PhysRevA.50.2981 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PL627 UT WOS:A1994PL62700033 ER PT J AU JOSLIN, RD STREETT, CL AF JOSLIN, RD STREETT, CL TI THE ROLE OF STATIONARY CROSS-FLOW VORTICES IN BOUNDARY-LAYER-TRANSITION ON SWEPT WINGS SO PHYSICS OF FLUIDS LA English DT Article ID INSTABILITY; SIMULATION; STABILITY AB The spatial evolution of stationary cross-flow-vortex packets in a laminar boundary layer on a swept wing is computed by direct numerical simulation with the incompressible Navier-Stokes equations. Steady suction and blowing at the wing surface is used to generate disturbances that are periodic and equally spaced in the spanwise direction. The initiated disturbances become unstable and lead to distinct stages of instability evolution. Initially, each vortex packet undergoes a region of chordwise and spanwise linear independent growth; then the individual packets coalesce downstream and lead to spanwise wave adjustments and linear superposition of adjacent packets; finally, the vortex packets reach sufficiently large amplitudes in later stages of disturbance development to nonlinearly interact, which results in the rapid growth of the disturbances. In this later stage, the low-velocity fluid near the wing surface is lifted out into the boundary layer and rolled over the high-speed fluid in the direction of the positive spanwise velocity component. Highly inflectional chordwise and spanwise velocity profiles are recorded in this region. Previous studies have demonstrated that these inflectional profiles spawn the rapid growth of secondary instabilities, which lead to the catastrophic breakdown to turbulence. RP JOSLIN, RD (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23681, USA. NR 43 TC 19 Z9 21 U1 0 U2 0 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 1994 VL 6 IS 10 BP 3442 EP 3453 DI 10.1063/1.868401 PG 12 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PJ435 UT WOS:A1994PJ43500025 ER PT J AU BLAISDELL, GA MANSOUR, NN REYNOLDS, WC AF BLAISDELL, GA MANSOUR, NN REYNOLDS, WC TI COMPRESSIBILITY EFFECTS ON THE PASSIVE SCALAR FLUX WITHIN HOMOGENEOUS TURBULENCE SO PHYSICS OF FLUIDS LA English DT Note AB Compressibility effects on turbulent transport of a passive scalar are studied within homogeneous turbulence using a kinematic decomposition of the velocity field into solenoidal and dilatational parts. It is found that the dilatational velocity does not produce a passive scalar flux, and that all of the passive scalar flux is due to the solenoidal velocity. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, DEPT MECH ENGN, STANFORD, CA 94305 USA. RP PURDUE UNIV, SCH AERONAUT & ASTRONAUT, W LAFAYETTE, IN 47907 USA. NR 11 TC 5 Z9 5 U1 1 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 1070-6631 EI 1089-7666 J9 PHYS FLUIDS JI Phys. Fluids PD OCT PY 1994 VL 6 IS 10 BP 3498 EP 3500 DI 10.1063/1.868406 PG 3 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PJ435 UT WOS:A1994PJ43500030 ER PT J AU LEPPING, RP AF LEPPING, RP TI COMPARISONS OF THE FIELD CONFIGURATIONS OF THE MAGNETOTAILS OF URANUS AND NEPTUNE SO PLANETARY AND SPACE SCIENCE LA English DT Article ID MAGNETIC-FIELD; PLASMA OBSERVATIONS; BOUNDARY-LAYER; POLAR CUSP; MAGNETOSPHERE; VOYAGER-2; MAGNETOPAUSE AB The magnetic field configuration-states of the magnetotails of the planets Uranus and Neptune are compared. Earth's case is also briefly treated, as well as some related aspects of the other three magnetic planets. In Uranus' case, due to the large tilt (59-degrees) of the planet's magnetic dipole with respect to its spin axis and the unusual obliquity of that axis, the angle of attack (alpha) of the solar wind with respect to dipole alignment goes through all possible angles, 0-degree to 180-degrees, yielding a very broad spectrum of configuration-states of its tail. Cases are discussed where the planetary magnetic dipole is eithe aligned with the Sun-planet-line (''pole-on'' state) or perpendicular to it and some intermediate states, for both Uranus and Neptune. Only Uranus experiences the pole-on state, which next occurs in November 1999 (+/-2 months); last year (1993.2) it had the first ''perpendicular'' state since Voyager encounter which resembles Earth's case. Neptune never has a pole-on configuration, but it gets as close as alpha = 14-degrees from it; the next occurrence is early in 2003. At Voyager encounter Neptune's magnetotail apparently rapidly migrated through a broad spectrum of field structures with near extreme states resembling an Earth-like case on the one hand and a cylindrically symmetric one on the other. Magnetopause ''openness'' should dramatically change in terms of the rapidly changing angle of attack throughout a planetary day for these two planets, and this has important implications for their magnetotails. Any future magnetospheric mission plans for Uranus or Neptune should take into consideration the allowed range of values for alpha for the epoch of interest; this is especially of concern for Uranus which has a pole-on state, and all possible alphas, around the middle of 2014, 20 years from now. RP LEPPING, RP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 40 TC 5 Z9 5 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD OCT PY 1994 VL 42 IS 10 BP 847 EP 857 DI 10.1016/0032-0633(94)90065-5 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QB193 UT WOS:A1994QB19300005 ER PT J AU CHOUDHURY, BJ AHMED, NU IDSO, SB REGINATO, RJ DAUGHTRY, CST AF CHOUDHURY, BJ AHMED, NU IDSO, SB REGINATO, RJ DAUGHTRY, CST TI RELATIONS BETWEEN EVAPORATION COEFFICIENTS AND VEGETATION INDEXES STUDIED BY MODEL SIMULATIONS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID PRIESTLEY-TAYLOR PARAMETER; LEAF-AREA INDEX; ENERGY-BALANCE; CROP COEFFICIENTS; MANAGEMENT-PRACTICES; NET PHOTOSYNTHESIS; LAND SURFACES; RADIATION; FOREST; REFLECTANCE AB Calculations using a heat balance and a radiative transfer model have been done to study relations among evaporation coefficients and vegetation indices. The evaporation coefficients are the crop coefficient (defined as the ratio of total evaporation and reference crop evaporation) and the transpiration coefficient (defined as the ratio of unstressed transpiration and reference crop evaporation), while the vegetation indices considered in this study are the normalized difference, soil adjusted vegetation index, and transformed soil adjusted vegetation index. The reference crop evaporation has been calculated using the Priestley-Taylor equation. The observed variations of crop (wheat) height, leaf area index, and weather conditions for 30 days at Phoenix (Arizona), together with the reflectances of different types of soil in wet and dry states, are used in the simulation. The total evaporation calculated from the model compared well with lysimeter observations. Variations in soil evaporation can introduce considerable scatter in the relation between the crop coefficient and leaf area index, while this scatter is much less for the relation between transpiration coefficient and leaf area index. The simulation results for 30 days of crop and weather data and reflectances of 19 soil types in wet and dry conditions gave significant linear correlations between the transpiration coefficient and the vegetation indices, the explained variance (r2) being highest for the soil adjusted vegetation index (r2 = 0.88) and lowest for the normalized difference (r2 = 0.81). A clump vegetation model is used to address the effect of spatial heterogeneity on the relationship between the transpiration coefficient and soil adjusted vegetation index. These simulated relationships between transpiration coefficient and vegetation indices for wheat are discussed in the context of the relationships derived from observations for several crops and grasses. The present analysis provides a theoretical basis for estimating, transpiration from remotely sensed data. C1 HUGHES STX CORP,LANHAM,MD. US WATER CONSERVAT LAB,PHOENIX,AZ 85040. USDA ARS,BELTSVILLE AGR RES CTR,REMOTE SENSING RES LAB,BELTSVILLE,MD 20705. RP CHOUDHURY, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Reginato, Robert/F-6199-2011 NR 79 TC 280 Z9 314 U1 4 U2 38 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1994 VL 50 IS 1 BP 1 EP 17 DI 10.1016/0034-4257(94)90090-6 PG 17 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PK819 UT WOS:A1994PK81900001 ER PT J AU WARNER, TA LEVANDOWSKI, DW BELL, R CETIN, H AF WARNER, TA LEVANDOWSKI, DW BELL, R CETIN, H TI RULE-BASED GEOBOTANICAL CLASSIFICATION OF TOPOGRAPHIC, AEROMAGNETIC, AND REMOTELY-SENSED VEGETATION COMMUNITY DATA SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SUPERIOR PROVINCE; CANADA; FOREST AB Classifications of rock-type in areas with closed-canopy forests using remotely sensed data must rely on geobotanical associations. However, the influence of substrate on vegetation communities is generally rather limited, and therefore classifications that are based on geobotanical associations can be improved greatly by including geomorphological and community spatial relationships, particularly those derived from digital elevation data. In a remote sensing study of Quetico Provincial Park, Ontario, Canada, digital topographic data was used to divide the landscape into four microclimate and drainage classes. The Landsat Thematic Mapper data were transformed into the nPDF Deciduous Forest Index, which is an estimate of the deciduous-coniferous mixture in each pixel. This was supplemented by digital aeromagnetic data and geological field mapping. Associations of the vegetation communities with geology, microclimate, and drainage classes were identified from these data, and then used in a rule-based geobotanical classification called TOPOVEG. TOPOVEG achieved an 85% accuracy in a classification of the 10 km x 13 km primary test site. A standard maximum likelihood classification of the same area had an accuracy of only 71%, and produces an output that has a distinctive noisy texture compared to the large, homogeneous classes of TOPOVEG. In a neighboring test site to the north, TOPOVEG accuracy was similarly high (86%). A neighboring southern test site, however, showed changing vegetation associations and consequently a lower accuracy. This suggests that the classification can be extended to neighboring unknown areas, except to the south where the classification rules should be modified to take into account the changing vegetation associations. Although TOPOVEG was developed for geobotanical exploration, the procedure has potential for investigating ecological community associations, and the patterns of those associations. C1 PURDUE UNIV,W LAFAYETTE,IN 47907. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INDIANA GEOL SURVEY,BLOOMINGTON,IN. RP WARNER, TA (reprint author), W VIRGINIA UNIV,DEPT GEOL & GEOG,POB 6300,MORGANTOWN,WV 26506, USA. RI Warner, Timothy/F-1483-2010 NR 41 TC 10 Z9 10 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD OCT PY 1994 VL 50 IS 1 BP 41 EP 51 DI 10.1016/0034-4257(94)90093-0 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PK819 UT WOS:A1994PK81900004 ER PT J AU FORNEY, LJ FRALICK, GC AF FORNEY, LJ FRALICK, GC TI 2 WIRE THERMOCOUPLE - FREQUENCY-RESPONSE IN CONSTANT FLOW SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Experimental measurements are made with a novel two wire thermocouple. Signals from two wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the two wire thermocouple requires no compensation for omegaless-than-or-equal-toomega1 where omega1 is the natural frequency of the smaller wire. A compensation factor is recommended for larger frequencies omega>2omega1. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP FORNEY, LJ (reprint author), GEORGIA TECH,SCH CHEM ENGN,ATLANTA,GA 30332, USA. NR 6 TC 29 Z9 29 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 1994 VL 65 IS 10 BP 3252 EP 3257 DI 10.1063/1.1144559 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA PL968 UT WOS:A1994PL96800030 ER PT J AU SEIDEWITZ, E AF SEIDEWITZ, E TI GENERICITY VERSUS INHERITANCE RECONSIDERED - SELF-REFERENCE USING GENERICS SO SIGPLAN NOTICES LA English DT Article; Proceedings Paper CT 9th Annual Conference on Object-Oriented Programming Systems, Languages, and Applications (OOPSLA 94) CY OCT 23-27, 1994 CL PORTLAND, OR SP ACM SIGPLAN AB As shown by the work of Bertrand Meyer, it is possible to simulate genericity using inheritance, but not vice-versa. This is because genericity is a parameterization mechanism with no way to deal with the polymorphic typing introduced using inheritance. Nevertheless, if we focus on the use of inheritance as an implementation technique, its key feature is the dynamic binding of self-referential operation calls. This turns out to be basically a parameterization mechanism that can in fact be simulated using generics and static binding. And for some applications this approach may actually be of more than academic interest. RP SEIDEWITZ, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 18 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 1994 VL 29 IS 10 BP 153 EP 163 PG 11 WC Computer Science, Software Engineering SC Computer Science GA PR871 UT WOS:A1994PR87100014 ER PT J AU DOMINGO, V FLECK, B POLAND, AI AF DOMINGO, V FLECK, B POLAND, AI TI THE SCIENTIFIC PAYLOAD OF THE SPACE-BASED SOLAR AND HELIOSPHERIC OBSERVATORY (SOHO) SO SPACE SCIENCE REVIEWS LA English DT Review DE SOLAR PHYSICS; SOLAR INTERIOR; SOLAR CORONA; SOLAR WIND; SOHO AB The space-based Solar and Heliospheric Observatory (SOHO) is a joint venture of ESA and NASA within the frame of the Solar Terrestrial Science Programme (STSP), the first ''Cornerstone'' of ESA's long-term programme ''Space Science - Horizon 2000''. The principal scientific objectives of the SOHO mission are: a) a better understanding of the structure and dynamics of the solar interior using techniques of helioseismology, and b) a better insight into the physical processes that form and heat the Sun's corona, maintain it and give rise to its acceleration into the solar wind. To achieve these goals, SOHO carries a payload consisting of 12 sets of complementary instruments which are briefly described here. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP ESTEC, ESA, DEPT SPACE SCI, 2200 AG NOORDWIJK, NETHERLANDS. RI Fleck, Bernhard/C-9520-2012 NR 2 TC 15 Z9 15 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 7 EP 12 DI 10.1007/BF00777835 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600003 ER PT J AU POLAND, AI DOMINGO, V FLECK, B AF POLAND, AI DOMINGO, V FLECK, B TI SOHO OPERATIONS AND GROUND SYSTEM SO SPACE SCIENCE REVIEWS LA English DT Review DE SUN; CORONA; SOHO AB SOHO is a joint ESA/NASA mission to study the sun from its interior to, and including, the solar wind in interplanetary space. It is currently scheduled for launch in 1995. After launch SOHO will be operated from the Experiment Operations Facility (EOF) at Goddard Space Flight Center (GSFC). The EOF will consist of facilities for instrument commanding, data reception, data reduction, and data analysis. In this paper the operations concepts including instrument ground commanding from the EOF and communications capabilities between the EOF and ground observatories and the public networks in general will be described. C1 ESTEC, ESA, DEPT SPACE SCI, 2200 AG NOORDWIJK, NETHERLANDS. RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RI Fleck, Bernhard/C-9520-2012 NR 0 TC 0 Z9 0 U1 2 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 13 EP 18 DI 10.1007/BF00777836 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600004 ER PT J AU FISHER, RR GUHATHAKURTA, M AF FISHER, RR GUHATHAKURTA, M TI SPARTAN-201 WHITE-LIGHT CORONAGRAPH EXPERIMENT SO SPACE SCIENCE REVIEWS LA English DT Review DE SUN; CORONA AB A white light coronagraph was launched into orbit aboard the space shuttle OV 103 (Discovery) on 7 April 1993. This device was one of two instruments included in the SPARTAN 201-1 payload, a completely autonomous sub-satellite deployed from the shuttle for a period of about 47 hours. The WLC system is an externally occulted coronagraph system which incorporates a rotating half-wave plate polarimeter, and the image data is used to infer the brightness, the polarized brightness and the degree of polarization of the white light emission from the solar corona. These data are in turn used to infer estimates of the K- and F-coronal brightnesses and density distributions. We shall present preliminary results of the electron density estimate in the coronal streamer and hole region and describe the methods employed. RP NASA, GODDARD SPACE FLIGHT CTR, GSFC, GREENBELT, MD 20771 USA. NR 5 TC 21 Z9 21 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 267 EP 272 DI 10.1007/BF00777878 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600046 ER PT J AU SUESS, ST WU, ST WANG, AH POLETTO, G AF SUESS, ST WU, ST WANG, AH POLETTO, G TI MAGNETOHYDRODYNAMIC SIMULATION OF A STREAMER BESIDE A REALISTIC CORONAL HOLE SO SPACE SCIENCE REVIEWS LA English DT Review DE STREAMERS; CORONAL HOLES; MHD SIMULATIONS AB Existing models of coronal streamers establish their credibility and act as the initial state for transients. The models have produced satisfactory streamer simulations, but unsatisfactory coronal hole simulations. This is a consequence of the character of the models and the boundary conditions. The models all have higher densities in the magnetically open regions than occur in coronal holes (Noci, et al., 1993). C1 UNIV ALABAMA, CTR SPACE PLASMA & AERON RES, HUNTSVILLE, AL 35899 USA. OSSERVATORIO ARCETRI, FLORENCE, ITALY. RP NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 295 EP 298 DI 10.1007/BF00777883 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600051 ER PT J AU NEUGEBAUER, M AF NEUGEBAUER, M TI OBSERVATIONS OF THE SOLAR-WIND FROM CORONAL HOLES SO SPACE SCIENCE REVIEWS LA English DT Review DE SUN; SOLAR WIND; CORONAL HOLES ID IONS; STREAM AB The solar wind emanating from coronal holes (CH) constitutes a quasi-stationary flow whose properties change only slowly with the evolution of the hole itself. Some of the properties of the wind from coronal holes depend on whether the source is a large polar coronal hole or a small near-equatorial hole. The speed of polar CH flows is usually between 700 and 800 km/s, whereas the speed from the small equatorial CH flows is generally lower and can be <400 km/s. At 1 AU, the average particle and energy fluxes from polar CH are 2.5 x 10(8) cm-2 sec-1 and 2.0 erg cm-2 s-1. This particle flux is significantly less than the 4x10(8) cm-2 sec-1 observed in the slow, interstream wind, but the energy fluxes are approximately the same. Both the particle and energy fluxes from small equatorial holes are somewhat smaller than the fluxes from the large polar coronal holes. Many of the properties of the wind from coronal holes can be explained, at least qualitatively, as being the result of the effect of the large flux of outward-propagating Alfven waves observed in CH flows. The different ion species have roughly equal thermal speeds which are also close to the Alfven speed. The velocity of heavy ions exceeds the proton velocity by the Alfven speed, as if the heavy ions were surfing on the waves carried by the proton fluid. The elemental composition of the CH wind is less fractionated, having a smaller enhancement of elements with low first-ionization potentials than the interstream wind, the wind from coronal mass ejections, or solar energetic particles. There is also evidence of fine-structure in the ratio of the gas and magnetic pressures which maps back to a scale size of roughly 1-degree at the Sun, similar to some of the fine structures in coronal holes such as plumes, macrospicules, and the supergranulation. RP JET PROP LAB, MAIL STOP 169-506, PASADENA, CA 91109 USA. NR 13 TC 9 Z9 9 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 319 EP 330 DI 10.1007/BF00777887 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600055 ER PT J AU HASSLER, DM AF HASSLER, DM TI BROADENGING OF FE-X (6374A-ANGSTROM) PROFILES ABOVE THE LIMB IN A CORONAL HOLE SO SPACE SCIENCE REVIEWS LA English DT Review DE SOLAR CORONA; CORONAL HOLES; SOLAR WIND; UV SPECTROSCOPY ID SOLAR-WIND; TELESCOPE AB Profiles of the visible Fe X (6374 angstrom) coronal emission line as a function of height above the limb were obtained out to 1.16 solar radii in a coronal hole using the NSO/Sacramento Peak Observatory Coronagraph, Universal Spectrograph and a CCD camera. These are the first coronal line profiles obtained as a function of height in a coronal hole from the ground. Analysis of the line widths suggests a large component of nonthermal broadening which increases with height ranging from 40 to 60 km/s, depending upon the assumed temperature or thermal component of the profile. C1 HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 16 TC 14 Z9 14 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD OCT PY 1994 VL 70 IS 1-2 BP 373 EP 377 DI 10.1007/BF00777895 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PN956 UT WOS:A1994PN95600063 ER PT J AU LILLEY, GM AF LILLEY, GM TI THE RADIATED NOISE FROM ISOTROPIC TURBULENCE SO THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS LA English DT Article ID DECAY AB The noise radiated from isotropic turbulence at low Mach numbers and high Reynolds numbers, as derived by Proudman (1952), was the first application of Lighthill's ''Theory of Aerodynamic Noise'' to a complete flow field. The theory presented by Proudman involves the assumption of the neglect of retarded-time differences and so replaces the second-order retarded-time and space covariance of Lighthill's stress tensor, T(ij), and in particular its second time derivative, by the equivalent simultaneous covariance. This assumption is a valid approximation in the derivation of the partial-derivative2T(ij)/partial-derivativet2 covariance at low Mach numbers, but is not justified when that covariance is reduced to the sum of products of the time derivatives of equivalent second-order velocity covariances as required when Gaussian statistics are assumed. When these assumptions are removed the changes to the analysis are substantial, but the change in the numerical result for the total acoustic power is small. This paper is based on an alternative analysis which does not neglect retarded times. It makes use of the Lighthill relationship, whereby the fourth-order T(ij) retarded-time covariance is evaluated from the square of a similar second-order covariance, which is assumed known. In this derivation no statistical assumptions are involved. This result, using distributions for the second-order space-time velocity squared covariance based on the Direct Numerical Simulation (DNS) results of both Sarkar and Hussaini (1993) and Dubois (1993), is compared with a re-evaluation of Proudman's original model. These results are then compared with the sound power derived from a phenomenological model based on simple approximations to the retarded-time/space covariance of T(xx). Finally, the recent numerical solutions of Sarkar and Hussaini (1993) for the acoustic power are compared with the results obtained from the analytic solutions. C1 UNIV SOUTHAMPTON,DEPT AERONAUT & ASTRONAUT,SOUTHAMPTON SO17 1BJ,HANTS,ENGLAND. RP LILLEY, GM (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 19 TC 17 Z9 17 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0935-4964 J9 THEOR COMP FLUID DYN JI Theor. Comput. Fluid Dyn. PD OCT PY 1994 VL 6 IS 5-6 BP 281 EP 301 DI 10.1007/BF00311842 PG 21 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PM737 UT WOS:A1994PM73700003 ER PT J AU HARDIN, JC POPE, DS AF HARDIN, JC POPE, DS TI AN ACOUSTIC VISCOUS SPLITTING TECHNIQUE FOR COMPUTATIONAL AEROACOUSTICS SO THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS LA English DT Article ID HYPERBOLIC SYSTEMS AB A new technique for the numerical analysis of aerodynamic noise generation is developed. The approach involves first solving for the time-dependent incompressible flow for the given geometry. A ''hydrodynamic'' density correction to the constant incompressible density is then calculated from knowledge of the incompressible pressure fluctuations. The compressible flow solution is finally obtained by considering perturbations about the ''corrected'' incompressible flow. This fully nonlinear technique, which is tailored to extract the relevant acoustic fluctuations, appears to be an efficient approach to the numerical analysis of aerodynamic noise generation, particularly in viscous flows. Applications of this technique to some classical acoustic problems of interest, including some with moderately high subsonic Mach numbers, are presented to validate the approach. The technique is then applied to a fully viscous problem where sound is generated by the flow dynamics. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23681. RP HARDIN, JC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 9 TC 68 Z9 74 U1 1 U2 13 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0935-4964 J9 THEOR COMP FLUID DYN JI Theor. Comput. Fluid Dyn. PD OCT PY 1994 VL 6 IS 5-6 BP 323 EP 340 DI 10.1007/BF00311844 PG 18 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PM737 UT WOS:A1994PM73700005 ER PT J AU PADAVALA, S PALAZZOLO, AB VALLELY, P RYAN, S AF PADAVALA, S PALAZZOLO, AB VALLELY, P RYAN, S TI SIMULATION STUDY WITH ARBITRARY PROFILE LIQUID ANNULAR SEALS SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 48th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 17-20, 1993 CL CALGARY, CANADA SP SOC TRIBOLOGISTS & LUBRICAT ENGINEERS DE LIQUID ANNULAR SEALS; AEROSPACE; FILM THICKNESS AB This paper presents an improved dynamic analysis for liquid annular seals with arbitrary profile based on a method first proposed by Nelson and Nguyen. An improved first-order solution that incorporates a continuous interpolation of perturbed quantities in the circumferential direction is presented. The original method uses an approximation scheme for circumferential gradients of zeroth order solution based on Fast Fourier Transforms (FFT). A simpler scheme based on cubic splines is found to be computationally more efficient, with better convergence at higher eccentricities. Arbitrarily varying seal profiles in both axial and circumferential directions are considered. A procedure for computing dynamic coefficients based on external specific load is discussed. An example case of an elliptical seal with varying degrees of axial curvature is analyzed. A case study based on actual operating clearances (6 axial planes with 68 clearances/plane) of an interstage seal of the Space Shuttle Main Engine High Pressure Oxygen Turbopump (SSME-ATD-HPOTP) is presented. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV CONTROLS SYST,HUNTSVILLE,AL 35812. RP PADAVALA, S (reprint author), TEXAS A&M UNIV,DEPT MECH ENGN,COLLEGE STN,TX 77843, USA. NR 11 TC 0 Z9 0 U1 0 U2 3 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 1994 VL 37 IS 4 BP 667 EP 678 DI 10.1080/10402009408983346 PG 12 WC Engineering, Mechanical SC Engineering GA PN115 UT WOS:A1994PN11500001 ER PT J AU MIYOSHI, K AF MIYOSHI, K TI THE EFFECT OF PULSED-LASER ANNEALING ON WEAR AND CORROSION PROPERTIES OF ELECTROLESS NI-P PLATING - DISCUSSION SO TRIBOLOGY TRANSACTIONS LA English DT Discussion RP MIYOSHI, K (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 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 1994 VL 37 IS 4 BP 881 EP 881 PG 1 WC Engineering, Mechanical SC Engineering GA PN115 UT WOS:A1994PN11500029 ER PT J AU MARTINEZ, LF MATLOCK, C MARQUES, RE MCCLURE, JC NUNES, AC AF MARTINEZ, LF MATLOCK, C MARQUES, RE MCCLURE, JC NUNES, AC TI EFFECT OF WELD GASES ON MELT ZONE SIZE IN VPPA WELDING OF AI-2219 SO WELDING JOURNAL LA English DT Article ID TUNGSTEN ARCS C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP MARTINEZ, LF (reprint author), UNIV TEXAS,DEPT MET & MAT ENGN,EL PASO,TX 79968, USA. NR 11 TC 5 Z9 5 U1 0 U2 1 PU AMER WELDING SOC PI MIAMI PA PO BOX 351040, MIAMI, FL 33135 SN 0043-2296 J9 WELD J JI Weld. J. PD OCT PY 1994 VL 73 IS 10 BP 51 EP 55 PG 5 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA PK417 UT WOS:A1994PK41700009 ER PT J AU MEYERS, F MARDER, SR PIERCE, BM BREDAS, JL AF MEYERS, F MARDER, SR PIERCE, BM BREDAS, JL TI TUNING OF LARGE 2ND HYPERPOLARIZABILITIES IN ORGANIC CONJUGATED COMPOUNDS SO CHEMICAL PHYSICS LETTERS LA English DT Article ID NONLINEAR OPTICAL SUSCEPTIBILITY; BOND-LENGTH ALTERNATION; ELECTRONIC HYPERPOLARIZABILITY; MOLECULES; POLYMERS AB The geometry of a typical polymethine dye is tuned as a function of an external electric field from a neutral structure to a zwitterionic (charge-separated) structure. The corresponding evolutions of the ground and excited states and the nonlinear optical response are calculated at the correlated level. Analysis of the results allows us to determine a consistent three-term model for the second hyperpolarizability. This model rationalizes recent experimental data and can be exploited to optimize gamma in either a positive or negative sense. C1 UNIV MONS, CTR RECH ELECTR & PHOTON MOLEC, B-7000 MONS, BELGIUM. CALTECH, BECKMAN INST, CTR MOLEC MAT RESOURCE, PASADENA, CA 91125 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. HUGHES AIRCRAFT CO, LOS ANGELES, CA 90009 USA. RP UNIV MONS, SERV CHIM MAT NOUVEAUX, PL PARC 20, B-7000 MONS, BELGIUM. RI Bredas, Jean-Luc/A-3431-2008 OI Bredas, Jean-Luc/0000-0001-7278-4471 NR 37 TC 29 Z9 29 U1 2 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 EI 1873-4448 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD SEP 30 PY 1994 VL 228 IS 1-3 BP 171 EP 176 DI 10.1016/0009-2614(94)00905-8 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PJ977 UT WOS:A1994PJ97700029 ER PT J AU VELUSAMY, K GARG, VK AF VELUSAMY, K GARG, VK TI ENTRANCE FLOW IN ECCENTRIC ANNULAR DUCTS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE DEVELOPING FLOW; ECCENTRIC ANNULAR DUCTS; 3+D NAVIER-STOKES SOLUTION ID MIXED CONVECTION; LAMINAR AB A control-volume-based solution of the complete set of Navier-Stokes equations for the laminar, three-dimensional developing flow in straight, eccentric, cylindrical annular ducts is described. Numerical results for velocity and pressure development, pressure defect and entrance lengths are presented for a wide range of duct parameters, i.e. relative eccentricity epsilon and radius ratio gamma. The present results match very well with earlier numerical solutions for the limiting cases of developing flow in concentric ducts and fully developed flow in eccentric ducts. Comparison with earlier approximate results for developing flow in eccentric ducts indicates that the approximate model predicts the velocity and pressure development with an error of about 10%. However, the development length predicted by the approximate model is grossly in error. The pressure defect and development length in eccentric ducts are very high compared with their counterparts in concentric ducts. The pressure defect, development length and maximum velocity increase with the radius ratio for eccentric ducts, while the reverse is true for concentric ducts. Also, the apparent friction factor decreases as the eccentricity increases. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP VELUSAMY, K (reprint author), INDIRA GANDHI CTR ATOM RES,THERMAL HYDRAUL SECT,KALPAKKAM 603102,TAMIL NADU,INDIA. NR 16 TC 4 Z9 4 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD SEP 30 PY 1994 VL 19 IS 6 BP 493 EP 512 DI 10.1002/fld.1650190604 PG 20 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA PJ671 UT WOS:A1994PJ67100003 ER PT J AU BALIYAN, KS BHATIA, AK AF BALIYAN, KS BHATIA, AK TI COLLISION STRENGTHS FOR THE ELECTRON-IMPACT EXCITATION OF CA-XIII SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID R-MATRIX METHOD; GENERAL PROGRAM; OSCILLATOR-STRENGTHS AB The R-matrix method is used to obtain collision strengths for the electron impact excitation of the oxygen-like Ca XIII ion for all transitions between the 16 target states of even and odd parity. The wavefunctions for these states are generated using the configuration interaction method. The calculated values of the target state energies agree with the experimental values within 7%. The initial and final state wavefunctions for the composite (electron C ion) system are obtained by retaining these states in the R-matrix basis function expansion. In the low partial wave region (total angular momentum L less than or equal to 9) the standard full exchange R-matrix method is used for the scattering calculation. Beyond this, a no-exchange R-matrix method is applied to calculate collision strengths for a sufficiently large number of partial waves (up to total angular momentum L = 30). The Burgess sum rule is used to determine the high partial wave (L > 30) contribution to the cross sections for dipole allowed transitions. However, it is seen that collision strengths for almost all the transitions, including the dipole allowed, converge below L = 30. The calculations are carried out in LS coupling and the results are compared with those obtained in the distorted-wave approximation along with other results, where available. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. OI /0000-0003-0180-8231 NR 20 TC 6 Z9 6 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 28 PY 1994 VL 27 IS 18 BP 4281 EP 4294 DI 10.1088/0953-4075/27/18/023 PG 14 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PK928 UT WOS:A1994PK92800023 ER PT J AU LARKIN, DJ NEUDECK, PG POWELL, JA MATUS, LG AF LARKIN, DJ NEUDECK, PG POWELL, JA MATUS, LG TI SITE-COMPETITION EPITAXY FOR SUPERIOR SILICON-CARBIDE ELECTRONICS SO APPLIED PHYSICS LETTERS LA English DT Article AB We present and discuss a novel dopant control technique for compound semiconductors, called site-competition epitaxy, which enables a much wider range of reproducible doping control and affords much higher and lower epilayer doping concentrations than was previously possible. Site-competition epitaxy is presented for the chemical vapor deposition of 6H-SiC epilayers on commercially available (0001)SiC silicon-face substrates. Results from utilizing site-competition epitaxy include the production of degenerately doped SiC epilayers for ohmic-as-deposited (i.e., unannealed) metal contacts as well as very low doped epilayers for electronic devices exhibiting SiC record-breaking reverse voltages of 300 and 2000 V for 3C- and 6H-SiC p-n junction diodes, respectively. RP LARKIN, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 218 Z9 222 U1 0 U2 16 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 26 PY 1994 VL 65 IS 13 BP 1659 EP 1661 DI 10.1063/1.112947 PG 3 WC Physics, Applied SC Physics GA PH332 UT WOS:A1994PH33200019 ER PT J AU JIANG, XP THIAGARAJAN, P PATRIZI, GA ROBINSON, GY TEMKIN, H FOROUHAR, S VANDENBERG, JM COBLENTZ, D LOGAN, RA AF JIANG, XP THIAGARAJAN, P PATRIZI, GA ROBINSON, GY TEMKIN, H FOROUHAR, S VANDENBERG, JM COBLENTZ, D LOGAN, RA TI OPTICAL-TRANSITIONS IN STRAINED IN1-XGAXASYP1-Y QUANTUM-WELLS CLAD BY LATTICE-MATCHED BARRIERS OF INGAASP SO APPLIED PHYSICS LETTERS LA English DT Article ID LASERS; SUPERLATTICES AB We extend the deformation potential model developed previously for InGaAs/InP quantum wells to include strained quaternary wells, under compressive or tensile strain, and lattice-matched (or also strained) quaternary barriers. This requires interpolation of the needed quaternary materials parameters in a plane bound by the four binary parent compounds. The calculated energies of heavy and light hole transitions are compared to measured values obtained on a set of compressively strained multi-quantum-well quaternary structures grown on (100) InP with the lattice mismatch strain Delta a/a as large as 0.75%. Our experimental results are in good agreement with the extended model. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. AT&T BELL LABS,MURRAY HILL,NJ 07974. RP JIANG, XP (reprint author), COLORADO STATE UNIV,DEPT ELECT ENGN,FT COLLINS,CO 80523, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 26 PY 1994 VL 65 IS 13 BP 1689 EP 1691 DI 10.1063/1.112887 PG 3 WC Physics, Applied SC Physics GA PH332 UT WOS:A1994PH33200029 ER PT J AU CHOI, KK LEE, CY TIDROW, MZ CHANG, WH GUNAPALA, SD AF CHOI, KK LEE, CY TIDROW, MZ CHANG, WH GUNAPALA, SD TI PERFORMANCE ASSESSMENT OF QUANTUM-WELL INFRARED PHOTODETECTORS SO APPLIED PHYSICS LETTERS LA English DT Article ID HOT-ELECTRON TRANSISTOR AB The performance of GaAs/AlGaAs quantum well infrared photodetectors specified in terms of background limited temperature T-b and specific detectivity D* has been calculated based on realistic detector parameters. It is found that for a detector with an external quantum efficiency eta of 6.9%, T-b is 76 K for a cutoff wavelength of 10 mu m. This value of T-b agrees with the recent experimental result and is significantly higher than the previous estimation given by M. A. Kinch and A. Yariv [Appl. Phys. Lett. 55, 2093 (1989)]. if eta is unity, the projected T-b can be as high as 88 K with a D* of 2.2X10(11) cm root Hz/W. For a lower temperature operation, D* increases to 7.5X10(11) cm root Hz/W at 77 K, comparable to that of a HgCdTe detector. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CHOI, KK (reprint author), USA,RES LAB,EPSD,FT MONMOUTH,NJ 07703, USA. RI Choi, Kwong-Kit/K-9205-2013 NR 14 TC 8 Z9 8 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 26 PY 1994 VL 65 IS 13 BP 1703 EP 1705 DI 10.1063/1.112891 PG 3 WC Physics, Applied SC Physics GA PH332 UT WOS:A1994PH33200034 ER PT J AU LEVIN, E SCHWENKE, DW STALLCOP, JR PARTRIDGE, H AF LEVIN, E SCHWENKE, DW STALLCOP, JR PARTRIDGE, H TI COMPARISON OF SEMICLASSICAL AND QUANTUM-MECHANICAL METHODS FOR THE DETERMINATION OF TRANSPORT CROSS-SECTIONS SO CHEMICAL PHYSICS LETTERS LA English DT Article ID COLLISION INTEGRALS; SCATTERING; HYDROGEN AB Quantitative comparisons of results obtained from a semi-classical approximation and from the numerical solution of the time-independent Schrodinger equation are presented for interactions in a system of small reduced mass involving hydrogen as one of the collision partners. The differences in transport cross sections are only significant at very low energies and consequently the effects on the collision integrals and gas transport properties diminish rapidly with increasing temperature. Furthermore, the differences also diminish rapidly with increasing values of the reduced mass. C1 ELORET INST,PALO ALTO,CA 94303. RP LEVIN, E (reprint author), NASA,AMES RES CTR,COMPUTAT CHEM BRANCH,MS230-3,MOFFETT FIELD,CA 94035, USA. RI schwenke, david/I-3564-2013 NR 19 TC 13 Z9 13 U1 0 U2 1 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 23 PY 1994 VL 227 IS 6 BP 669 EP 675 DI 10.1016/0009-2614(94)00878-7 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PG982 UT WOS:A1994PG98200022 ER PT J AU RICCA, A BAUSCHLICHER, CW ROSI, M AF RICCA, A BAUSCHLICHER, CW ROSI, M TI 2ND-ORDER MOLLER-PLESSET PERTURBATION-THEORY FOR SYSTEMS INVOLVING FIRST TRANSITION ROW METALS SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID COLLISION-INDUCED DISSOCIATION; GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; 2 WATER-MOLECULES; POSITIVE-IONS; BINDING-ENERGIES; ELECTRON CORRELATION; WAVE-FUNCTIONS; ATOMS; 1ST-ROW AB Results obtained using second-order Moller-Plesset (MP2) perturbation theory are compared with those obtained using coupled cluster singles and doubles approach including a perturbational estimate of the connected triple excitations, CCSD(T), or the modified coupled-pair functional (MCPF) approach. For FeCO, FeCO+, FeH2O+, and the states of FeCH4+ derived from the Fe+ 3d(6)4s(1) occupation, the MP2 geometries are found to be in good agreement with those obtained at the CCSD(T) or MCPF level. At the MP2 level the Fe-C bond lengths for the states of FeCH4+ derived from the 3d(7) occupation are too long relative to the MCPF or CCSD(T) results. The geometries computed at the self-consistent-field (SCF) level are quite poor for FeCO+ and all states of FeCH4+. The energetics at the MP2 level, while superior to the SCF, are still significantly inferior to those obtained at the CCSD(T) or MCPF level. We find that FeCH4+ has a quartet ground state with an eta(3) coordination. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV PERUGIA, DEPT CHEM, I-06100 PERUGIA, ITALY. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 47 TC 35 Z9 35 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 22 PY 1994 VL 98 IS 38 BP 9498 EP 9502 DI 10.1021/j100089a023 PG 5 WC Chemistry, Physical SC Chemistry GA PH559 UT WOS:A1994PH55900023 ER PT J AU TIMONEN, RS CHU, LT LEU, MT KEYSER, LF AF TIMONEN, RS CHU, LT LEU, MT KEYSER, LF TI HETEROGENEOUS REACTION OF CLONO2(G)+NACL(S)-]CL-2(G)+NANO3(S) SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID HYDROGEN-CHLORIDE; GASEOUS N2O5; ICE SURFACES; WATER ICE; ATOMIC CL; NACL; STRATOSPHERE; PARTICLES; ERUPTION; CLOUDS AB The heterogeneous reaction of ClONO2 + NaCl --> Cl-2 + NaNO3 (eq 1) was investigated over a temperature range 220-300 K in a now-tube reactor interfaced with a differentially pumped quadrupole mass spectrometer. Partial pressures of ClONO2 in the range 10(-8)-10(-5) Torr were used. Granule sizes and surface roughness of the NaCl substrates were determined by using a scanning electron microscope, and in separate experiments, surface areas of the substrates were measured by using BET analysis of gas-adsorption isotherms. For dry NaCl substrates, both the decay rates of ClONO2 and the growth rates of Cl-2 were used to obtain reaction probabilities, gamma(1) = (4.6 +/- 3.0) x 10(-3) at 296 K and (6.7 +/- 3.2) x 10(-3) at 225 K, after considering the internal surface area. The error bars represent 1 standard deviation. The Ch yield based on the ClONO2 reacted was measured to be 1.0 +/- 0.2. In order to mimic the conditions encountered in the lower stratosphere, the effect of water vapor pressures between 5 x 10(-5) and 3 x 10(-4) Torr on reaction 1 was also studied. With added H2O, reaction probabilities, gamma(1) = (4.1 +/- 2.1) x 10(-3) at 296 K and (4.7 +/- 2.9) x 10(-3) at 225 K, were obtained. A trace of HOCl, the reaction product from the ClONO2 + H2O --> HOCl + HNO3 reaction, was observed in addition to the Cl-2 product from reaction 1. The implications of this result for the enhancement of hydrogen chloride in the stratosphere after the El Chichon volcanic eruption and for the marine troposphere are discussed. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. NR 36 TC 46 Z9 47 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 22 PY 1994 VL 98 IS 38 BP 9509 EP 9517 DI 10.1021/j100089a025 PG 9 WC Chemistry, Physical SC Chemistry GA PH559 UT WOS:A1994PH55900025 ER PT J AU TINKER, ML CUTCHINS, MA AF TINKER, ML CUTCHINS, MA TI INSTABILITIES IN A NONLINEAR MODEL OF A PASSIVE DAMPER SO JOURNAL OF SOUND AND VIBRATION LA English DT Article AB During a study of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, an interesting instability was observed. Following an experimental investigation of this system, a semi-empirical model having non-linear stiffness, nth power velocity damping, and variable Coulomb-type friction damping was developed. Results obtained using ACSL compare well with experimental data. The primary emphasis of this paper, however, centers on the instabilities and large-response behavior of this semi-empirical model. Stabilizing effects are discussed. C1 AUBURN UNIV,DEPT AEROSP ENGN,AUBURN,AL 36849. RP TINKER, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SYST RESPONSE BRANCH,HUNTSVILLE,AL 35812, USA. NR 8 TC 7 Z9 7 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD SEP 22 PY 1994 VL 176 IS 3 BP 415 EP 428 DI 10.1006/jsvi.1994.1385 PG 14 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA PJ647 UT WOS:A1994PJ64700009 ER PT J AU ABRAMS, MC TOON, GC SCHINDLER, RA AF ABRAMS, MC TOON, GC SCHINDLER, RA TI PRACTICAL EXAMPLE OF THE CORRECTION OF FOURIER-TRANSFORM SPECTRA FOR DETECTOR NONLINEARITY SO APPLIED OPTICS LA English DT Article ID FT-IR; HGCDTE AB HgCdTe photoconductive detectors can display a nonlinear response when illuminated. In interferometric applications, this behavior must be accounted for in the data transformation process to avoid erros in the measurement of the spectral distribution of the incident radiation. A model for the distortion of the interferogram is proposed and applied to solar observations made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier-transform spectrometer during orbital sunrise and sunset from the Space Shuttle. Empirical estimation of the dc current level is necessary for this instrument, and satisfactory nonlinearity correction is obtained for several of the primary ATMOS optical filters. For ATMOS broadband optical filters that cover more than one half the alias bandwidth, the model is inadequate because of the presence of antialising electronic filters within the instrument, and it is necessary to resort to estimation and subtraction of the residual baseline offset. In either case the remaining baseline offsets are typically smaller than 1%, which is satisfactory, although offset remains a significant systematic source of error in the estimation of the abundance of telluric and solar constituents from the spectra. RP ABRAMS, MC (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 8 TC 54 Z9 54 U1 0 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 1994 VL 33 IS 27 BP 6307 EP 6314 PG 8 WC Optics SC Optics GA PJ393 UT WOS:A1994PJ39300004 PM 20941162 ER PT J AU DALLAS, JL AF DALLAS, JL TI FREQUENCY-MODULATION MODE-LOCKING PERFORMANCE FOR 4 ND(3+)-DOPED LASER CRYSTALS SO APPLIED OPTICS LA English DT Note DE FM MODE-LOCKING; ND-YVO4; ND-S-VAP ID ND-YLF LASER; YAG LASER AB To determine an optimum host for simultaneous short-pulse-width and large-slope-efficiency generation, the performance of Nd:YAG, Nd:YLF, Nd:YVO4, and Nd3+:Sr5(VO4)3F [Nd:strontium fluorovanadate (S-VAP)] was characterized under a variety of end-pumped and frequency-modulation mode-locking conditions. The slope efficiency, threshold pump power, and pulse width were recorded for each laser and compared with theroy. A figure of merit was defined, yielding Nd:YLF and Nd:YVO4 as the experimentally determined crystals of choice. RP DALLAS, JL (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 13 TC 7 Z9 7 U1 0 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 1994 VL 33 IS 27 BP 6373 EP 6376 PG 4 WC Optics SC Optics GA PJ393 UT WOS:A1994PJ39300014 PM 20941172 ER PT J AU HIGDON, NS BROWELL, EV PONSARDIN, P GROSSMANN, BE BUTLER, CF CHYBA, TH MAYO, MN ALLEN, RJ HEUSER, AW GRANT, WB ISMAIL, S MAYOR, SD CARTER, AF AF HIGDON, NS BROWELL, EV PONSARDIN, P GROSSMANN, BE BUTLER, CF CHYBA, TH MAYO, MN ALLEN, RJ HEUSER, AW GRANT, WB ISMAIL, S MAYOR, SD CARTER, AF TI AIRBORNE DIFFERENTIAL ABSORPTION LIDAR SYSTEM FOR MEASUREMENTS OF ATMOSPHERIC WATER-VAPOR AND AEROSOLS SO APPLIED OPTICS LA English DT Article DE DIFFERENTIAL ABSORPTION LIDAR; ALEXANDRITE LASER; WATER VAPOR; AEROSOLS ID 720-NM WAVELENGTH REGION; RAMAN LIDAR; SENSITIVITY; PROFILES; OZONE AB An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H2O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and >99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H2O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H2O absorption-line parameters were performed to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H2O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H2O radiosondes. The H2O distributions measured with the DIAL system differed by less-than-or-equal-to 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions. C1 APPLICAT INT CORP, HAMPTON, VA 23666 USA. STX CORP, HAMPTON, VA 23665 USA. NATL RES COUNCIL, HAMPTON, VA 23681 USA. LOCKHEED ENGN & SCI CO, HAMPTON, VA 23666 USA. ALLEN ASSOCIATES, HAMPTON, VA 23666 USA. RP HIGDON, NS (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MS 401A, HAMPTON, VA 23665 USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 38 TC 46 Z9 46 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 1994 VL 33 IS 27 BP 6422 EP 6438 PG 17 WC Optics SC Optics GA PJ393 UT WOS:A1994PJ39300023 PM 20941181 ER PT J AU PONSARDIN, P HIGDON, NS GROSSMANN, BE BROWELL, EV AF PONSARDIN, P HIGDON, NS GROSSMANN, BE BROWELL, EV TI SPECTRAL CONTROL OF AN ALEXANDRITE LASER FOR AN AIRBORNE WATER-VAPOR DIFFERENTIAL ABSORPTION LIDAR SYSTEM SO APPLIED OPTICS LA English DT Article DE ALEXANDRITE LASER; DIFFERENTIAL ABSORPTION LIDAR; INTRACAVITY ETALONS; WAVELENGTH STABILIZATION; SPECTRAL PURITY ID SPECTROSCOPY; PROFILES; PRESSURE; REGION AB A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (> 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760 nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm-1 (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm-1 (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (almost-equal-to 1.5 h) of less than 0.7 pm in the laboratory. C1 OLD DOMINION UNIV, RES FDN, NORFOLK, VA 23508 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 29 TC 7 Z9 7 U1 2 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 20 PY 1994 VL 33 IS 27 BP 6439 EP 6450 PG 12 WC Optics SC Optics GA PJ393 UT WOS:A1994PJ39300024 PM 20941182 ER PT J AU COE, MJ ROCHE, P EVERALL, C FISHMAN, GJ HAGEDON, KS FINGER, M WILSON, RB BUCKLEY, DAH SHRADER, C FABREGAT, J POLCARO, VF GIOVANNELLI, F VILLADA, M AF COE, MJ ROCHE, P EVERALL, C FISHMAN, GJ HAGEDON, KS FINGER, M WILSON, RB BUCKLEY, DAH SHRADER, C FABREGAT, J POLCARO, VF GIOVANNELLI, F VILLADA, M TI MULTIWAVEBAND STUDY OF A MAJOR X-RAY OUTBURST FROM THE BE/X-RAY TRANSIENT SYSTEM A-1118-616 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, INDIVIDUAL, A 1118-616; BINARIES, CLOSE STARS, BE; X-RAYS, BURSTS, STARS ID SPECTRAL VARIABILITY; OPTICAL COUNTERPART; REDSHIFTS; STARS AB The Be/X-ray binary system A 1118-616 has been observed to undergo a major outburst in January 1992 by the BATSE all-sky monitor on the Compton Gamma Ray Observatory, Ground-based optical and IR observations, supported by W observations obtained under an IUE Target of Opportunity programme, have provided us with an excellent multiwavelength study of this system to complement the X-ray data set. The results from this campaign are presented showing the details of the X-ray timing studies, the very strong Her emission and the bright IR excess from the Be star's circumstellar disk (the fuel for the accretion process). Implications for the physics of the system are discussed. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. S AFRICAN ASTRON OBSERV, CAPE TOWN 7935, SOUTH AFRICA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV VALENCIA, DEPT ASTRON, E-46100 BURJASSOT, SPAIN. IST ASTROFIS SPAZIALE, I-00044 FRASCATI, ITALY. OBSERV UNIV CORDOBA, CORDOBA, ARGENTINA. RP COE, MJ (reprint author), UNIV SOUTHAMPTON, DEPT PHYS, SOUTHAMPTON SO9 5NH, HANTS, ENGLAND. RI Fabregat, Juan/F-9066-2016 OI Fabregat, Juan/0000-0002-5986-9347 NR 37 TC 34 Z9 34 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 20 PY 1994 VL 289 IS 3 BP 784 EP 794 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PH676 UT WOS:A1994PH67600016 ER PT J AU KANBACH, G ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS CHIANG, J FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, D NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, E SOMMER, M SREEKUMAR, P TAYLOR, JH THOMPSON, DJ AF KANBACH, G ARZOUMANIAN, Z BERTSCH, DL BRAZIER, KTS CHIANG, J FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C NEL, HI NICE, D NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, E SOMMER, M SREEKUMAR, P TAYLOR, JH THOMPSON, DJ TI EGRET OBSERVATIONS OF THE VELA PULSAR, PSR0833-45 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE PULSARS, INDIVIDUAL, PSR0833-45; VELA; GAMMA RAYS, OBSERVATIONS ID RAPIDLY SPINNING PULSARS; GAMMA-RAY EMISSION; ENERGETIC RADIATION; COS-B; PSR-0833-45; RELAXATION; TELESCOPE; CRAB AB During the all sky survey (May 1991 to November 1992) of the Compton Gamma Ray Observatory, the Vela pulsar PSR0833-45 was in the field of view of the Energetic Gamma Ray Experiment Telescope (EGRET) in ten separate viewing periods. The pulsar was detected in each one. The average intensity from 100 MeV to 2 GeV was (7.8 +/- 1.0) x 10(-6) photons cm(-2) s(-1), which indicates that the pulsar in the years 1991/92 cm was in a state comparable to the low fluxes observed in 1977-1980. No significant changes in intensity were detected during the EGRET observations. The total spectrum of PSR0833-45 measured by EGRET can be described by a power-law with index -1.70+/-0.02 over the range 30 MeV to 2 GeV. The extrapolation of this spectrum into the 3-30 MeV range agrees with the observations by COMPTEL. Above 2-4 GeV EGRET detects a strong spectral break. The lightcurves obtained show a familiar structure in the phase histogram: two peaks separated by 0.424 +/- 0.002 in phase with considerable emission in the phase interval between the peaks. The first gamma ray peak maximum trails the single radio peak maximum by 10.54 +/- 0.09 ms (= 0.118 +/- 0.001 in phase). The widths of the emission peaks (FWHM) are 2.7 ms for the first peak (0.03 phase) and 4.1 ms for the second peak (0.05 phase). The widths are approximately constant below a GeV, but show a tendency to become narrower at higher energies. On July 20, 1991 a glitch of the Vela period was registered in monitor radio observations. No significant differences between the pre- and post-glitch gamma ray lightcurves have been found. The statistics available for the Vela observations allow for a division of the lightcurve into eight phase intervals. The emission peak cores (central FWHM) with leading and trailing wings and two interval regions were defined and spectra were derived for all parts of the lightcurve. The energy spectra for the eight phase intervals show significant differences: the first peak (similar to E(-1.81+/-0.04)) is somewhat softer than the second peak (similar to E(-1.71+/-0.03)); the wings attached to each peak show softer spectra than the core of the peaks; the interval emission has the hardest spectrum (similar to E(-1.52+/-0.03)). C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. STANFORD UNIV, HANSEN EXPTL SPACE FLIGHT CTR, STANFORD, CA 94305 USA. COMP SCI CORP, GRO SCI SUPPORT CTR, ASTRON PROGRAMS, GREENBELT, MD USA. GRUMMAN AEROSP CORP, BETHPAGE, NY 11714 USA. NASA, GSFC, UNIV RES ASSOC, GREENBELT, MD USA. HAMPDEN SYDNEY COLL, HAMPDEN SYDNEY, VA 23943 USA. PRINCETON UNIV, DEPT PHYS, PRINCETON, NJ 08544 USA. RP KANBACH, G (reprint author), MAX PLANCK INST EXTRATERR PHYS, D-85748 GARCHING, GERMANY. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 31 TC 110 Z9 110 U1 1 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP 20 PY 1994 VL 289 IS 3 BP 855 EP 867 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PH676 UT WOS:A1994PH67600022 ER PT J AU SELLGREN, K SMITH, RG BROOKE, TY AF SELLGREN, K SMITH, RG BROOKE, TY TI THE 3.2-3.6 MICRON SPECTRA OF MONOCEROS R2/IRS-3 AND ELIAS-16 SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; INFRARED, ISM, LINES AND BANDS; ISM, MOLECULES; STARS, PRE-MAIN-SEQUENCE ID DENSE INTERSTELLAR CLOUDS; TAURUS DARK CLOUD; INFRARED-SPECTROSCOPY; MOLECULAR CLOUDS; SOLID METHANOL; ABSORPTION; EXTINCTION; PROTOSTARS; COMPLEX; ICES AB We have obtained 3.2-3.6 mum spectra, with a resolution lambda/DELTAlambda approximately 750, of the protostar Mon R2/IRS-3 and of Elias 16, a background K giant behind the Taurus molecular cloud. A feature at 3.482 mum (2872 cm-1), with a full width at half-maximum of 0.09 mum (76 cm-1), is clearly seen in Mon R2/IRS-3. This feature is not detected in Elias 16. The 3.482 mum feature in Mon R2/IRS-3 is similar to a feature at 3.466-3.478 mum (2875-2885 cm-1) detected by Allamandola et al. in four protostars and attributed by these authors to a CH stretch in hydrocarbons dominated by sp3-bonded carbon. Neither Mon R2/IRS-3 nor Elias 16 shows absorption at 3.540 mum (2825 cm-1), which has been detected in two of the four protostars observed by Allamandola et al. and attributed by them to CH3OH ice. Our limit on CH3OH ice toward Elias 16 is compared to models of gas-grain chemistry in dark clouds. Our results confirm those of Allamandola et al. that at this resolution the 3.4 mum absorption due to dust in molecular clouds has very different spectral structure than that due to dust in the diffuse interstellar medium. C1 UNIV NEW S WALES, AUSTRALIAN DEF FORCE ACAD, DEPT PHYS, UNIV COLL, CANBERRA 2600, AUSTRALIA. JET PROP LAB, PASADENA, CA 91109 USA. RP SELLGREN, K (reprint author), OHIO STATE UNIV, DEPT ASTRON, 174 W 18TH AVE, COLUMBUS, OH 43210 USA. NR 44 TC 42 Z9 42 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 20 PY 1994 VL 433 IS 1 BP 179 EP 186 DI 10.1086/174634 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG639 UT WOS:A1994PG63900015 ER PT J AU WANG, H GARY, DE LIM, J SCHWARTZ, RA AF WANG, H GARY, DE LIM, J SCHWARTZ, RA TI MICROWAVE SPECTRAL IMAGING H-ALPHA, AND HARD X-RAY OBSERVATIONS OF A SOLAR LIMB FLARE SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, FLARES; SUN, RADIO RADIATION; SUN, X-RAYS, GAMMA-RAYS ID BURSTS; RESOLUTION; ELECTRONS; EMISSION; MAPS AB We compare the microwave, Ha, and hard X-ray observations for a west limb C7.3 flare that occurred at 17:10 UT, 1992 June 26. Halpha movies were obtained at Big Bear Solar Observatory. Before the onset of the flare, overexposed Halpha images show the complicated flux loop structure above the limb. Material was observed to descend along the loops toward the site where the flare occurred hours later. Using the five-antenna solar array at Owens Valley Radio Observatory, we obtain two-dimensional maps of flare emission from 1.4 to 14 GHz. In all three temporal peaks of the microwave bursts, the maps show the same characteristics. The peak low-frequency emission comes from the top of one bundle of the Halpha loops and gradually shifts to the footpoint of the loops (the location of Halpha flare) as the frequency increases. The location of the emission peak shifts 88'' between 1 and 14 GHz. Seventy percent of the shift occurs between 1 and 5 GHz. The locus of the shift of the emission peak follows the shape of an Halpha surge that occurred after the flare. For each point along the locus, we create the microwave brightness temperature spectrum and compare the radio-derived electron distribution with that derived from the high-resolution hard X-ray spectra measured with BATSE on board the Compton Gamma Ray Observatory. We find that the peak frequency changes from approximately 3 GHz at the loop top to approximately 7 GHz at the footpoint, presumably due to the increase of the magnetic field from approximately 160 G at the loop top to approximately 300 G at the footpoint. The high-frequency slope of the microwave power-law spectrum decreases from approximately 10 at the loop top to approximately 5 at the footpoint due to a change in the energy distribution of the dominant electrons. The microwave brightness temperature spectral index predicted by the BATSE power-law hard X-ray spectra agrees with the measured value only at the footpoint. At the loop top, the emission may be thermal gyrosynchrotron with a temperature of 3.5 x 10(7) K, which is likely to correspond to the superhot component seen in the hard X-ray emission. C1 NASA,GODDARD SPACE FLIGHT CTR,GFSC,GREENBELT,MD 20771. RP WANG, H (reprint author), CALTECH,BIG BEAR SOLAR OBSERV,SOLAR ASTRON 264-33,PASADENA,CA 91125, USA. NR 26 TC 30 Z9 37 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 1994 VL 433 IS 1 BP 379 EP 388 DI 10.1086/174652 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG639 UT WOS:A1994PG63900033 ER PT J AU TITARCHUK, L MASTICHIADIS, A AF TITARCHUK, L MASTICHIADIS, A TI HARD X-RAYS FROM NGC-4151 - A THERMAL ORIGIN SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, SEYFERT; PLASMAS; RADIATION MECHANISMS, THERMAL; RADIATIVE TRANSFER; RELATIVITY ID ACCRETION DISKS; EMISSION; COMPTONIZATION; RADIATION; SPECTRUM; SIGMA; LINE AB We present a model for explaining the recent combined X-ray and low-energy gamma-ray observations of the Seyfert galaxy NGC 4151. According to this model, soft photons become Comptonized in a hot spot producing simultaneously the low-energy power law as observed by Ginga and the high-energy cutoff observed by OSSE. Implementing recently developed theoretical calculations toward a generalized theory of Comptonization, we were able to find fits to the observations using only two parameters which characterize the physical quantities of the emission region: the plasma cloud optical depth and its temperature. We find that there is no need for additional nonthermal, reflection, or higher temperature thermal components to fit the aforementioned OSSE and Ginga observations. We derive in addition the size of the photon region and the temperature of the upscattered soft photons. We should emphasize, also, that any attempt at fitting only the high-energy parts of the spectrum (photon energies > 60 keV) by the Sunyaev & Titarchuk (1980) nonrelativistic Comptonization model leads to an underestimate of the Comptonization parameter y (or, equivalently, to an overestimation of the X-ray power-law spectral slope) and leads, as a result, to incorrect proportions between the low-energy and high-energy parts of the spectrum. C1 MAX PLANCK INST KERNPHYS,D-69126 HEIDELBERG,GERMANY. RP TITARCHUK, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 24 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 1994 VL 433 IS 1 BP L33 EP L36 DI 10.1086/187541 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG640 UT WOS:A1994PG64000009 ER PT J AU CAHOON, DR STOCKS, BJ LEVINE, JS COFER, WR PIERSON, JM AF CAHOON, DR STOCKS, BJ LEVINE, JS COFER, WR PIERSON, JM TI SATELLITE ANALYSIS OF THE SEVERE 1987 FOREST-FIRES IN NORTHERN CHINA AND SOUTHEASTERN SIBERIA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID JACK PINE; IDENTIFICATION; BEHAVIOR; PLUMES AB Meteorological conditions, extremely conducive to fire development and spread in the spring of 1987, resulted in forest fires burning over extremely large areas in the boreal forest zone in northeastern China and the southeastern region of Siberia. The great China fire, one of the largest and most destructive forest fires in recent history, occurred during this period in the Heilongjiang Province of China. Satellite imagery is used to examine the development and areal distribution of 1987 forest fires in this region. Overall trace gas emissions to the atmosphere from these fires are determined using a satellite-derived estimate of area burned in combination with fuel consumption figures and carbon emission ratios for boreal forest fires. C1 FORESTRY CANADA, GREAT LAKES FORESTRY CTR, SAULT ST MARIE P6A 5M7, ON, CANADA. RP CAHOON, DR (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL CODE 423, HAMPTON, VA 23681 USA. NR 21 TC 149 Z9 158 U1 1 U2 17 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 1994 VL 99 IS D9 BP 18627 EP 18638 DI 10.1029/94JD01024 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700009 ER PT J AU HAN, Y SNIDER, JB WESTWATER, ER MELFI, SH FERRARE, RA AF HAN, Y SNIDER, JB WESTWATER, ER MELFI, SH FERRARE, RA TI OBSERVATIONS OF WATER-VAPOR BY GROUND-BASED MICROWAVE RADIOMETERS AND RAMAN LIDAR SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MOISTURE MEASUREMENTS; WIND PROFILER; AEROSOLS; LIQUID; SSM/I; RASS AB In November to December 1991, a substantial number of remote sensors and in situ instruments were operated together in Coffeyville, Kansas, during the climate experiment FIRE II. Included in the suite of instruments were (1) the NOAA Environmental Technology Laboratory (ETL) three-channel microwave radiometer, (2) the NASA GSFC Raman lidar, (3) ETL radio acoustic sounding system (RASS), and (4) frequent, research-quality radiosondes. The Raman lidar operated only at night and the focus of this portion of the experiment concentrated on clear conditions. The lidar data, together with frequent radiosondes and measurements of temperature profiles (every 15 min) by RASS allowed profiles of temperature and absolute humidity to be estimated every minute. We compared 2-min measurements of brightness temperature (Tb) With calculations of Tb that were based on the Liebe and Layton (1987) and Liebe et al. (1993) microwave propagation models, as well as the Waters (1976) model. The comparisons showed the best agreement at 20.6 GHz with the Waters model, with the Liebe et al. (1993) model being best at 31.65 GHz. The results at 90 GHz gave about equal success with the Liebe and Layton (1987) and Liebe et al. (1993) models. Comparisons of precipitable water vapor derived independently from the two instruments also showed excellent agreement, even for averages as short as 2 min. The rms difference between Raman and radiometric determinations of precipitable water vapor was 0.03 cm which is roughly 2%. The experiments clearly demonstrate the potential of simultaneous operation of radiometers and Raman lidars for fundamental physical studies of water vapor. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. HUGHES STX CORP, LANHAM, MD 20706 USA. RP HAN, Y (reprint author), NOAA, ENVIRONM RES LAB, ETL, 325 BROADWAY, BOULDER, CO 80303 USA. RI Han, Yong/F-5590-2010 OI Han, Yong/0000-0002-0183-7270 NR 31 TC 34 Z9 35 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 1994 VL 99 IS D9 BP 18695 EP 18702 DI 10.1029/94JD01487 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700014 ER PT J AU THOMPSON, AM PICKERING, KE DICKERSON, RR ELLIS, WG JACOB, DJ SCALA, JR TAO, WK MCNAMARA, DP SIMPSON, J AF THOMPSON, AM PICKERING, KE DICKERSON, RR ELLIS, WG JACOB, DJ SCALA, JR TAO, WK MCNAMARA, DP SIMPSON, J TI CONVECTIVE-TRANSPORT OVER THE CENTRAL UNITED-STATES AND ITS ROLE IN REGIONAL CO AND OZONE BUDGETS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERIC OZONE; CARBON-MONOXIDE; AIR; DISTRIBUTIONS; VEGETATION; CHEMISTRY; OXIDATION; PROFILES; EXPORT AB We have constructed a regional budget for boundary layer carbon monoxide over the central United States (32.5 degrees-50 degrees N, 90 degrees-105 degrees W), emphasizing a detailed evaluation of deep convective vertical fluxes appropriate for the month of June. Deep convective venting of the boundary layer (upward) dominates other components of the CO budget, e.g., downward convective transport, loss of CO by oxidation, anthropogenic emissions, and CO produced from oxidation of methane, isoprene, and anthropogenic nonmethane hydrocarbons (NMHCs). Calculations of deep convective venting are based on the method of Pickering et al. [1992a] which uses a satellite-derived deep convective cloud climatology along with transport statistics from convective cloud model simulations of observed prototype squall line events. This study uses analyses of convective episodes in 1985 and 1989 and CO measurements taken during several midwestern field campaigns. Deep convective venting of the boundary layer over this moderately polluted region provides a net (upward minus downward) flux of 18.1 x 10(8) kg CO month(-1) to the free troposphere during early summer, assuming the June statistics are typical. Shallow cumulus and synoptic-scale weather systems together make a comparable contribution (total net flux 16.2 x 10(8) kg CO month(-1)). Boundary layer venting of CO with other O-3 precursors leads to efficient free tropospheric O-3 formation. We estimate that deep convective transport of CO and other precursors over the central United States in early summer leads to a gross production of 0.66-1.1 Gmol O-3 d(-1) in good agreement with estimates of O-3 production from boundary layer venting in a continental-scale model [Jacob et al., 1993a, b]. In this respect the central U.S. region acts as a ''chimney'' for the country, and presumably this O-3 contributes to high background levels of O-3 in the eastern United States and O-3 export to the North Atlantic. C1 UNIV MARYLAND, DEPT METEOROL, COLLEGE PK, MD 20742 USA. HARVARD UNIV, DIV APPL SCI, CAMBRIDGE, MA 02138 USA. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. APPL RES CORP, LANDOVER, MD 20785 USA. RP THOMPSON, AM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 916, GREENBELT, MD 20771 USA. RI Pickering, Kenneth/E-6274-2012; Dickerson, Russell/F-2857-2010; Thompson, Anne /C-3649-2014 OI Dickerson, Russell/0000-0003-0206-3083; Thompson, Anne /0000-0002-7829-0920 NR 44 TC 75 Z9 76 U1 2 U2 14 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 1994 VL 99 IS D9 BP 18703 EP 18711 DI 10.1029/94JD01244 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700015 ER PT J AU CONSIDINE, DB DOUGLASS, AR JACKMAN, CH AF CONSIDINE, DB DOUGLASS, AR JACKMAN, CH TI EFFECTS OF A POLAR STRATOSPHERIC CLOUD PARAMETERIZATION ON OZONE DEPLETION DUE TO STRATOSPHERIC AIRCRAFT IN A 2-DIMENSIONAL MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HETEROGENEOUS CHEMISTRY; AEROSOLS; PARTICLES; GROWTH; IMPACT AB A parameterization of Type 1 and 2 polar stratospheric cloud (PSC) formation is presented which is appropriate for use in two-dimensional (2-D) photochemical models of the stratosphere. The calculation of PSC frequency of occurrence and surface area density uses climatological temperature probability distributions obtained from National Meteorological Center data to avoid using zonal mean temperatures, which are not good predictors of PSC behavior. The parameterization does not attempt to model the microphysics of PSCs. The parameterization predicts changes in PSC formation and heterogeneous processing due to perturbations of stratospheric trace constituents. It is therefore useful in assessing the potential effects of a fleet of stratospheric aircraft (high speed civil transports, or HSCTs) on stratospheric composition. The model calculated frequency of PSC occurrence agrees well with a climatology based on stratosphepic aerosol measurement (SAM) II observations. PSCs are predicted to occur in the tropics. Their vertical range is narrow, however, and their impact on model O-3 fields is small. When PSC and sulfate aerosol heterogeneous processes are included in the model-calculations, the O-3 change for 1980 - 1990 is in substantially better agreement with the total ozone mapping spectrometer (TOMS)-derived O-3 trend than otherwise. However, significant discrepancies in the northern midlatitudes remain. The overall changes in model O-3 response to standard HSCT perturbation scenarios produced by the parameterization are small and tend to decrease the model sensitivity to the HSCT perturbation. However, in the southern hemisphere spring a significant increase in O-3 sensitivity to HSCT perturbations is found. At this location and time, increased PSC formation leads to increased levels of active chlorine, which produce the O-3 decreases. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP CONSIDINE, DB (reprint author), APPL RES CORP, 8201 CORP DR, LANDOVER, MD 20785 USA. RI Douglass, Anne/D-4655-2012; Jackman, Charles/D-4699-2012 NR 38 TC 46 Z9 46 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1994 VL 99 IS D9 BP 18879 EP 18894 DI 10.1029/94JD01026 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700030 ER PT J AU RINSLAND, CP GUNSON, MR ABRAMS, MC ZANDER, R MAHIEU, E GOLDMAN, A KO, MKW RODRIGUEZ, JM SZE, ND AF RINSLAND, CP GUNSON, MR ABRAMS, MC ZANDER, R MAHIEU, E GOLDMAN, A KO, MKW RODRIGUEZ, JM SZE, ND TI PROFILES OF STRATOSPHERIC CHLORINE NITRATE (CIONO2) FROM ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY ATLAS-1 INFRARED SOLAR OCCULTATION SPECTRA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ABSORPTION-COEFFICIENTS; CLONO2; TEMPERATURES; SPECTROMETRY; 296-K AB Stratospheric volume mixing ratio profiles of chlorine nitrate (ClONO2) have been retrieved from 0.01-cm(-1) resolution infrared solar occultation spectra recorded at latitudes between 14 degrees N and 54 degrees S by the atmospheric trace molecule spectroscopy Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The results were obtained from nonlinear least squares fittings of the ClONO2 nu(4) band Q branch at 780.21 cm(-1) with improved spectroscopic parameters generated on the basis of recent laboratory work. The individual profiles, which have an accuracy of about +/- 20%, are compared with previous observations and model calculations. C1 CALTECH, JET PROP LAB, PASADENA, CA USA. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. UNIV DENVER, DEPT PHYS, DENVER, CO 80208 USA. ATMOSPHER & ENVIRONM RES INC, CAMBRIDGE, MA 02139 USA. RP RINSLAND, CP (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL CODE 401A, HAMPTON, VA 23681 USA. RI Rodriguez, Jose/G-3751-2013; Ko, Malcolm/D-5898-2015 OI Rodriguez, Jose/0000-0002-1902-4649; NR 26 TC 26 Z9 26 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 1994 VL 99 IS D9 BP 18895 EP 18900 DI 10.1029/94JD01520 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700031 ER PT J AU DELUISI, JJ MATEER, CL THEISEN, D BHARTIA, PK LONGENECKER, D CHU, B AF DELUISI, JJ MATEER, CL THEISEN, D BHARTIA, PK LONGENECKER, D CHU, B TI NORTHERN MIDDLE-LATITUDE OZONE PROFILE FEATURES AND TRENDS OBSERVED BY SBUV AND UMKEHR, 1979-1990 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC AEROSOLS; INVERSION ALGORITHM AB A comparison of Umkehr ozone profile data with the reprocessed solar backscatter ultraviolet (SBUV) ozone profile data in the northern middle-latitude region, 30 degrees to 50 degrees N, is reported. Although significant biases exist between the two types of observations, the long-term variations and least squares linear regression trends agree remarkably well over the comparison period of 1979 to 1990. The ozone trend in the upper stratosphere is of the order of -0.9% yr(-1). Near 25 km, little if any trend appears, but a larger negative trend is seen in the lower stratosphere near 15 km. Comparisons show that the average annual ozone cycles in the profiles also agree well. The upper stratospheric ozone results are consistent with photochemical model predictions of ozone depletion near 40 km that are due to the release of anthropogenically produced chlorofluorocarbons. The lower stratospheric ozone trend results are in reasonable agreement with published ozonesonde data trends. It is shown that the ozone trends in the lower stratospheric layers impact significantly on the total ozone trend of the order of -0.47% yr(-1). The good agreement now seen between the two types of observations suggests that the combined ground-based and satellite approach could provide a valuable database for long-term monitoring of stratospheric ozone for trends and extraordinary variations. C1 COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80521 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV COLORADO, COOPERAT INST RES ENVIRONM SCI, BOULDER, CO 80302 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP DELUISI, JJ (reprint author), NOAA, ENVIRONM RES LABS, 325 BROADWAY, BOULDER, CO 80303 USA. RI Bhartia, Pawan/A-4209-2016 OI Bhartia, Pawan/0000-0001-8307-9137 NR 28 TC 22 Z9 22 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD SEP 20 PY 1994 VL 99 IS D9 BP 18901 EP 18908 DI 10.1029/94JD01518 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PH357 UT WOS:A1994PH35700032 ER PT J AU KASHLINSKY, A TKACHEV, II FRIEMAN, J AF KASHLINSKY, A TKACHEV, II FRIEMAN, J TI MICROWAVE BACKGROUND ANISOTROPY IN LOW-OMEGA(0) INFLATIONARY MODELS AND THE SCALE OF HOMOGENEITY IN THE UNIVERSE SO PHYSICAL REVIEW LETTERS LA English DT Article ID COSMOLOGICAL PERTURBATIONS; PREINFLATIONARY UNIVERSE; GALAXY; CLUSTERS; REMNANTS AB We study the microwave background anisotropy due to superhorizon-size perturbations in open universes with negative spatial curvature. Using results on the low-order temperature multipole moments from the Cosmic Background Explorer satellite, we find that if the homogeneity of the observable Universe arises from an early epoch of inflation, the present density parameter cannot differ from unity by more than the observed quadrupole anisotropy, \1 - Omega(0)\ less than or similar to Q similar or equal to 5 x 10(-6), assuming preinflationary density perturbations to be of order unity. With this assumption, inflation models with low Omega(0) either do not fit the microwave background observations or they do not solve the horizon problem. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RUSSIAN ACAD SCI,INST NUCL RES,MOSCOW 117312,RUSSIA. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP KASHLINSKY, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 685,GREENBELT,MD 20771, USA. NR 36 TC 41 Z9 41 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD SEP 19 PY 1994 VL 73 IS 12 BP 1582 EP 1585 DI 10.1103/PhysRevLett.73.1582 PG 4 WC Physics, Multidisciplinary SC Physics GA PG522 UT WOS:A1994PG52200005 ER PT J AU NOOR, AK HADIAN, MJ PETERS, JM AF NOOR, AK HADIAN, MJ PETERS, JM TI REDUCED BASIS TECHNIQUE FOR EVALUATING THE SENSITIVITY OF THE NONLINEAR VIBRATIONAL RESPONSE OF COMPOSITE PLATES SO COMPUTERS & STRUCTURES LA English DT Article ID FLEXURAL VIBRATIONS; RECTANGULAR-PLATES AB A reduced basis technique and a computational procedure are presented for generating the nonlinear vibrational response, and evaluating the first-order sensitivity coefficients of composite plates (derivatives of the nonlinear frequency with respect to material and geometric parameters of the plate). The analytical formulation is based on a form of the geometrically nonlinear shallow shell theory with the effects of transverse shear deformation, rotatory inertia and anisotropic material behavior included. The plate is discretized by using mixed finite element models with the fundamental unknowns consisting of both the nodal displacements and the stress-resultant parameters of the plate. The computational procedure can be conveniently divided into three distinct steps. The first step involves the generation of various-order perturbation vectors, and their derivatives with respect to the material and lamination parameters of the plate, using Linstedt-Poincare perturbation technique. The second step consists of using the perturbation vectors as basis vectors, computing the amplitudes of these vectors and the nonlinear frequency of vibration, via a direct variational procedure. The third step consists of using the perturbation vectors, and their derivatives, as basis vectors and computing the sensitivity coefficients of the nonlinear frequency via a second application of the direct variational procedure. The effectiveness of the proposed technique is demonstrated by means of numerical examples of composite plates. RP NOOR, AK (reprint author), UNIV VIRGINIA,NAS LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23681, USA. NR 23 TC 4 Z9 4 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD SEP 17 PY 1994 VL 52 IS 6 BP 1097 EP 1105 DI 10.1016/0045-7949(94)90176-7 PG 9 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA PJ563 UT WOS:A1994PJ56300001 ER PT J AU JEDRZEJAS, MJ TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF AF JEDRZEJAS, MJ TOWNS, RLR BAKER, RJ DURAJ, SA HEPP, AF TI TRANS-BIS(ACETATO-O)BIS(4-METHYLPYRIDINE-N)COPPER(II) SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article AB The structure of trans-bis(acetato-O)bis(4-methyl-pyridine-N)copper(II), [Cu(C2H3O2)2(C6H7N)2], reported herein, represents a monomeric parent acetate complex with a distorted square-planar arrangement of acetate and 4-methylpyridine ligands around the Cu atom with the following distances and angles: Cu-N = 2.027 (4) and Cu-O1 = 1.950 (3) angstrom; O1-Cu-N = 89.1 (2) and O1-Cu-N' = 90.9 (2)-degrees. The Cu atom resides on a center of inversion. The most important dihedral angles are the angle between the 4-methylpyridine plane and the acetate plane (O1, O2, C21 and C22), 78.2-degrees, and the angle between the 4-methylpyridine ring and the coordination plane (Cu, N, 01), 31.6-degrees. C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. NASA,LEWIS RES CTR,PHOTOVALTAIC BRANCH,CLEVELAND,OH 44135. NR 8 TC 2 Z9 2 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD SEP 15 PY 1994 VL 50 BP 1442 EP 1443 DI 10.1107/S0108270193013502 PN 9 PG 2 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA PK710 UT WOS:A1994PK71000029 ER PT J AU MATNEY, ML LIMERO, TF JAMES, JT AF MATNEY, ML LIMERO, TF JAMES, JT TI PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY ANALYSES OF BIOLOGICAL PARTICULATES COLLECTED DURING RECENT SPACE-SHUTTLE MISSIONS SO ANALYTICAL CHEMISTRY LA English DT Article ID RESOLUTION MASS-SPECTROMETRY AB Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of ''marker'' compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0.5-1-mm diameter and weighing as little as 40 mu g could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight. C1 NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. RP MATNEY, ML (reprint author), KRUG LIFE SCI INC,1290 HERCULES,HOUSTON,TX 77058, USA. NR 15 TC 3 Z9 3 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD SEP 15 PY 1994 VL 66 IS 18 BP 2820 EP 2828 DI 10.1021/ac00090a006 PG 9 WC Chemistry, Analytical SC Chemistry GA PG636 UT WOS:A1994PG63600009 PM 11536649 ER PT J AU MELBOURNE, WG DAVIS, ES YUNCK, TP TAPLEY, BD AF MELBOURNE, WG DAVIS, ES YUNCK, TP TAPLEY, BD TI THE GPS FLIGHT EXPERIMENT ON TOPEX POSEIDON SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The precision orbit determination (POD) experiment on TOPEX/POSEIDON using the Global Positioning System (GPS) is yielding concrete results. Orbit consistency and accuracy tests indicate that GPS is routinely providing satellite altitude with an accuracy of better than 3 cm. Here we review the GPS experiment, its basic concepts, POD techniques and key results, and discuss the possible cost and performance benefits that may flow to future missions. C1 UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. RP MELBOURNE, WG (reprint author), JET PROP LAB,DIV TELECOMMUN,PASADENA,CA 91109, USA. NR 8 TC 22 Z9 25 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 15 PY 1994 VL 21 IS 19 BP 2171 EP 2174 DI 10.1029/94GL02192 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PH573 UT WOS:A1994PH57300025 ER PT J AU CHRISTENSEN, EJ HAINES, BJ MCCOLL, KC NEREM, RS AF CHRISTENSEN, EJ HAINES, BJ MCCOLL, KC NEREM, RS TI OBSERVATIONS OF GEOGRAPHICALLY CORRELATED ORBIT ERRORS FOR TOPEX POSEIDON USING THE GLOBAL POSITIONING SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We have compared Global Positioning System (GPS)-based dynamic and reduced-dynamic TOPEX/Poseidon orbits over three 10-day repeat cycles of the ground-track. The results suggest that the prelaunch joint gravity model (JGM-1) introduces geographically correlated errors (GCEs) which have a strong meridional dependence. The global distribution and magnitude of these GCEs are consistent with a prelaunch covariance analysis, with estimated and predicted global rms error statistics of 2.3 and 2.4 cm rms, respectively. Repeating the analysis with the post-launch joint gravity model (JGM-2) suggests that a portion of the meridional dependence observed in JGM-1 still remains, with a global rms error of 1.2 cm. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. RP CHRISTENSEN, EJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 8 TC 21 Z9 21 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 1994 VL 21 IS 19 BP 2175 EP 2178 DI 10.1029/94GL02191 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PH573 UT WOS:A1994PH57300026 ER PT J AU SONG, KD ALEXANDER, DR AF SONG, KD ALEXANDER, DR TI EXCIMER-LASER PRODUCED PLASMAS IN COPPER WIRE TARGETS AND WATER DROPLETS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID INDUCED BREAKDOWN; RADIATION; AEROSOLS AB Elastically scattered incident radiation (ESIR) from a copper wire target illuminated by a KrF laser pulse at lambda=248 nm shows a distinct two-peak structure which is dependent on the incident energy. The time required to reach the critical electron density (n(c) approximate to 1.8 X 10(22) electrons/cm(3)) is estimated at 11 ns based on experimental results. Detailed ESIR characteristics for water have been reported previously by the authors. Initiation of the broadband emission for copper plasma begins at 6.5 +/- 1.45 ns after the arrival of the laser pulse. However, the broadband emission occurs at 11 +/- 0.36 ns for water. For a diatomic substance such as water, the electron energy rapidly dissipates due to dissociation of water molecules, which is absence in a monatomic species such as copper. When the energy falls below the excitation energy of the lowest electron state for water, it becomes a subexcitation electron. Lifetimes of the subexcited electrons to the vibrational states are estimated to be of the order of 10(-9) s. In addition, the ionization potential of copper (440-530 nm) is approximately 6 eV, which is about two times smaller than the 13 eV ionization potential reported for water. The higher ionization potential contributes to the longer observed delay time for plasma formation in water. After initiation, a longer time is required for copper plasma to reach its peak value. This time delay in reaching the maximum intensity is attributed to the energy loss during the interband transition in copper. C1 UNIV NEBRASKA,DEPT ELECT ENGN,CTR ELECTROOPT,LINCOLN,NE 68588. RP SONG, KD (reprint author), NASA,LANGLEY RES CTR,MS 493,HAMPTON,VA 23665, USA. NR 20 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 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD SEP 15 PY 1994 VL 76 IS 6 BP 3297 EP 3301 DI 10.1063/1.357451 PG 5 WC Physics, Applied SC Physics GA PJ117 UT WOS:A1994PJ11700010 ER PT J AU SONG, KD ALEXANDER, DR AF SONG, KD ALEXANDER, DR TI PROPAGATION VELOCITIES OF LASER-PRODUCED PLASMAS FROM COPPER WIRE TARGETS AND WATER DROPLETS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SHOCK-WAVE EXPERIMENTS; PRESSURE; BREAKDOWN; WAVELENGTH; RADIATION; SURFACES; DEPENDENCE; ALUMINUM AB Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire targets (75 mu m diameter) and water droplets (75 E Lm diameter) at irradiance levels ranging from 25 to 150 GW/cm(2). Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximate to 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/cm(2), the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/cm(2) showed a quantitative agreement within approximately 50 % while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma for liquid droplets obtained by previous research are compared with current work. C1 UNIV NEBRASKA, DEPT ELECT ENGN, CTR ELECTROOPT, LINCOLN, NE 68588 USA. RP SONG, KD (reprint author), NASA, LANGLEY RES CTR, MS 493, HAMPTON, VA 23665 USA. NR 39 TC 6 Z9 8 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 1994 VL 76 IS 6 BP 3302 EP 3312 DI 10.1063/1.357452 PG 11 WC Physics, Applied SC Physics GA PJ117 UT WOS:A1994PJ11700011 ER PT J AU CANTRELL, JH AF CANTRELL, JH TI CRYSTALLINE-STRUCTURE AND SYMMETRY DEPENDENCE OF ACOUSTIC NONLINEARITY PARAMETERS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID ELASTIC-CONSTANTS; RADIATION STRESS; SOLIDS; BCC AB A quantitative measure of elastic wave nonlinearity in crystals is provided by the acoustic nonlinearity parameters. The nonlinearity parameters are defined for arbitrary propagation modes for solids of arbitrary crystalline symmetry and are determined along the pure mode propagation directions for 33 crystals of cubic symmetry from data reported in the literature. The magnitudes of the nonlinearity parameters are found to exhibit a strong dependence on the crystalline structure and symmetries associated with the modal direction in the solid. Calculations based on the Born-Mayer potential for crystals having a dominant repulsive contribution to the elastic constants from the interatomic pair potential suggest that the origin of the structure dependence is associated with the shape rather than the strength of the potential. Considerations based on variations in crystal symmetry during loading along pure mode propagation directions of face-centered-cubic solids provide a qualitative explanation for the dependence of the acoustic nonlinearity parameters on modal direction. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP CANTRELL, JH (reprint author), UNIV CAMBRIDGE, CAVENDISH LAB, MADINGLEY RD, CAMBRIDGE CB3 0HE, CAMBS, ENGLAND. NR 37 TC 29 Z9 32 U1 1 U2 6 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 1994 VL 76 IS 6 BP 3372 EP 3380 DI 10.1063/1.357463 PG 9 WC Physics, Applied SC Physics GA PJ117 UT WOS:A1994PJ11700023 ER PT J AU REDDY, BR NASHSTEVENSON, SK AF REDDY, BR NASHSTEVENSON, SK TI RED-TO-VIOLET AND NEAR-INFRARED-TO-GREEN ENERGY UP-CONVERSION IN LAF3-ER3+ SO JOURNAL OF APPLIED PHYSICS LA English DT Note ID UP-CONVERSION LUMINESCENCE; GLASSES; BLUE; LASER; ER3+; UV AB When the F-4(9/2) state was resonantly excited, emission was detected from the higher states S-4(3/2)(H-2(11/2)), (4)G(11/2), and P-2(3/2) in addition to the resonant emission. Two- and three-photon processes were found to be responsible in populating the S-4(3/2) and the P-2(3/2) states, respectively. Energy upconversion efficiencies into the S-4(3/2) and the P-2(3/2) states were found to be 7.2X10(-3) and 1.4X10(-4), respectively. When the I-4(9/2) state was resonantly excited we detected green emission from the S-4(3/2)(H-2(11/2)). The energy upconversion efficiency of this process was found to be 1.4X10(-3). C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP REDDY, BR (reprint author), ALABAMA A&M UNIV,DEPT PHYS,POB 1268,NORMAL,AL 35762, USA. NR 14 TC 30 Z9 30 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 15 PY 1994 VL 76 IS 6 BP 3896 EP 3898 DI 10.1063/1.357395 PG 3 WC Physics, Applied SC Physics GA PJ117 UT WOS:A1994PJ11700098 ER PT J AU CAVALIERI, DJ MARTIN, S AF CAVALIERI, DJ MARTIN, S TI THE CONTRIBUTION OF ALASKAN, SIBERIAN, AND CANADIAN COASTAL POLYNYAS TO THE COLD HALOCLINE LAYER OF THE ARCTIC-OCEAN SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID MULTICHANNEL MICROWAVE RADIOMETER; SEA ICE CONCENTRATION; NIMBUS-7 SMMR; BERING SEA; SHELF; CIRCULATION; WATER; EXCHANGE; PROFILES; IMAGERY AB Numerous Arctic Ocean circulation and geochemical studies suggest that ice growth in polynyas over the Alaskan, Siberian, and Canadian continental shelves is a source of cold, saline water which contributes to the maintenance of the Arctic Ocean halocline. The purpose of this study is to estimate for the 1978-1987 winters the contributions of Arctic coastal polynyas to the cold halocline layer of the Arctic Ocean. The study uses a combination of satellite, oceanographic, and weather data to calculate the brine fluxes from the polynyas; then an oceanic box model is used to calculate their contributions to the cold halocline layer of the Arctic Ocean. This study complements and corrects a previous study of dense water production by coastal polynyas in the Barents, Kara, and Laptev Seas. Recurrent polynyas form on the Canadian and Alaskan coasts from Banks Island to the Bering Strait and on the Siberian coast from the Bering Strait to the New Siberian Islands. In the Bering Sea, polynyas form in Norton Sound, south and west of St. Lawrence Island, and in the Gulf of Anadyr. Two regions that account for almost 50% of the total dense water production are the Siberian coastal polynyas in the adjacent regions of the Gulf of Anadyr and Anadyr Strait and the Alaskan coastal polynyas which occur along the coast from Cape Lisburne to Point Barrow. For all of the western Arctic coastal regions examined, the mean annual total brine flux is 0.5 +/- 0.2 Sv. Combination of this flux with the contribution from the Barents, Kara, and Laptev Seas, which is recalculated from data in the earlier study, shows that over the entire Arctic, coastal polynyas generate about 0.7-1.2 Sv of dense water. This compares well with the theoretical estimates of 1-1.5 Sv. Because an unknown fraction of the Barents, Kara, and Laptev brine flux must go to the Eurasian Basin deep water, the coastal polynyas alone cannot renew the halocline layer. Other potential brine generation mechanisms include overall freezing on the shelves and the response of the ice to infrequent violent storms. For example, during February 1982 an intense storm generated a large region of low ice concentration in the eastern Chukchi Sea over Barrow Canyon. The refreezing of the region was followed by the flow of a dense plume down Barrow Canyon. Although the ocean dynamical response to this refreezing needs to be established, the possible response of a Barrow Canyon flow to this refreezing event suggests that the overall refreezing in response to infrequent violent storms may be a potential source of the additional brine needed to maintain the Arctic Ocean halocline. C1 UNIV WASHINGTON,SCH OCEANOG,SEATTLE,WA 98195. RP CAVALIERI, DJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771, USA. NR 37 TC 175 Z9 181 U1 2 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 1994 VL 99 IS C9 BP 18343 EP 18362 DI 10.1029/94JC01169 PG 20 WC Oceanography SC Oceanography GA PG783 UT WOS:A1994PG78300010 ER PT J AU BELL, LD MILLIKEN, AM MANION, SJ KAISER, WJ FATHAUER, RW PIKE, WT AF BELL, LD MILLIKEN, AM MANION, SJ KAISER, WJ FATHAUER, RW PIKE, WT TI BALLISTIC-ELECTRON-EMISSION MICROSCOPY OF STRAINED SI1-XGEX LAYERS SO PHYSICAL REVIEW B LA English DT Note ID ELASTIC-SCATTERING; INTERFACE; SPECTROSCOPY; TEMPERATURE; TRANSPORT; SURFACE; SUPERLATTICES; EPITAXY; SI AB Ballistic-electron-emission microscopy (BEEM) has been used to investigate the effects of strain on Si1-xGex alloys. Lifting of the degeneracy of the conduction-band minimum of Si1-xGex due to lattice deformation has been directly measured by application of BEEM spectroscopy to Ag/Si structures. Experimental values for this conduction-band splitting agree well with calculations. In addition, an unexpected heterogeneity in the strain of the Si1-xGex layer is introduced by deposition of Au. This effect, not observed with Ag, is attributed to species interdiffusion and has important implications for metal-semiconductor devices based on pseudomorphic Si1-xGex/Si material systems. RP BELL, LD (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 22 TC 14 Z9 14 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD SEP 15 PY 1994 VL 50 IS 11 BP 8082 EP 8085 DI 10.1103/PhysRevB.50.8082 PG 4 WC Physics, Condensed Matter SC Physics GA PJ437 UT WOS:A1994PJ43700119 ER PT J AU LI, Y WANG, S ZETNER, PW TRAJMAR, S AF LI, Y WANG, S ZETNER, PW TRAJMAR, S TI MAGNETIC SUBLEVEL PARTIAL-DIFFERENTIAL CROSS-SECTIONS FOR ELECTRON-IMPACT EXCITATION OF THE BA(...6S6P 6(1)P1) LEVEL SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID LASER-INDUCED FLUORESCENCE; STEPWISE ELECTRON; ANGULAR-CORRELATIONS; HELIUM COLLISIONS; SCATTERING; ALIGNMENT; MERCURY; BARIUM; STATES; ORIENTATION AB Magnetic sublevel partial differential cross sections for excitation of the Ba(...6s6p 6(1)P1) level are presented based upon the differential cross section measurements of Jensen et al and Wang et al in combination with new electron impact coherence parameter measurements and electron impact coherence parameter measurements previously reported by Zetner and Li. These partial differential cross sections, determined for electron impact energies of E0 = 10, 20, 37, 50 and 80 eV, are compared with available theory. C1 JET PROP LAB,PASADENA,CA 91109. RP LI, Y (reprint author), UNIV MANITOBA,DEPT PHYS,WINNIPEG R3T 2N2,MANITOBA,CANADA. NR 34 TC 7 Z9 7 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 1994 VL 27 IS 17 BP 4025 EP 4037 DI 10.1088/0953-4075/27/17/025 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PJ483 UT WOS:A1994PJ48300025 ER PT J AU WANG, JM KANTERAKIS, E KATZ, A ZHANG, Y LI, Y MURRAY, N AF WANG, JM KANTERAKIS, E KATZ, A ZHANG, Y LI, Y MURRAY, N TI HIGH-SPEED FREE-SPACE INTERCONNECT BASED ON OPTICAL RING TOPOLOGY - EXPERIMENTAL DEMONSTRATION SO APPLIED OPTICS LA English DT Article DE RING TOPOLOGY; SINGLE-INSTRUCTION MULTIPLE DATA; FREE-SPACE OPTICAL INTERCONNECT; NEAREST-NEIGHBOR INTERCONNECT ID NETWORKS; SYSTEMS AB The design and implementation of a high-speed optical-ring-topology-based free-space optical interconnect is described. This interconnect system operates at 500 MHz and consists of 16 laser transmitters, a four-channel free-space interconnect, and a high-speed receiver. A nearest-neighbor interconnect is demonstrated. At the data rate of 500 MHz the total system throughput is 8 Gbits/s. The system can easily be operated at much higher data rates since the rate is limited only by the electronic circuitry. A discussion is given about device issues such as optical switching devices, and practical system-design issues such as integration and interface with current electronic systems are considered. This interconnect is promising to the implementation of ultrafast massively parallel single-instruction multiple-data machines. C1 NEC CORP LTD, RES INST, PRINCETON, NJ 08540 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. RP WANG, JM (reprint author), INTERDIGITAL TELECOM, 833 NORTHERN BLVD, NEW YORK, NY 11021 USA. NR 12 TC 2 Z9 3 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 10 PY 1994 VL 33 IS 26 BP 6181 EP 6187 PG 7 WC Optics SC Optics GA PG458 UT WOS:A1994PG45800006 PM 20936035 ER PT J AU NEMIROFF, RJ WICKRAMASINGHE, WADT NORRIS, JP KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA PACIESAS, WS HORACK, J AF NEMIROFF, RJ WICKRAMASINGHE, WADT NORRIS, JP KOUVELIOTOU, C FISHMAN, GJ MEEGAN, CA PACIESAS, WS HORACK, J TI NULL RESULT IN GAMMA-RAY BURST LENSED ECHO SEARCH SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS; GRAVITATIONAL LENSING ID BATSE AB We have searched for gravitational-lens-induced echoes between gamma-ray bursts (GRBs) in BATSE data. The search was conducted in two phases, In the first phase we compared all GRBs in a brightness-complete sample of the first 260 GRBs with recorded angular positions having at least a 5% chance of being coincident from their combined positional error. In the second phase, we compared all GRB light curves of the first 611 GRBs with recorded angular positions having at least a 55% chance of being coincident from their combined positional error. No unambiguous gravitational lens candidate pairs were found in either phase, although a ''library of close calls'' was accumulated for future reference. This result neither excludes nor significantly constrains a cosmological origin for GRBs. C1 GEORGE MASON UNIV,FAIRFAX,VA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV PENN,DEPT ASTRON & ASTROPHYS,PHILADELPHIA,PA 19104. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP NEMIROFF, RJ (reprint author), UNIV SPACE RES ASSOC,WASHINGTON,DC, USA. RI Horack, John/J-6670-2016 NR 20 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1994 VL 432 IS 2 BP 478 EP 484 DI 10.1086/174587 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE877 UT WOS:A1994PE87700007 ER PT J AU CONTOPOULOS, J AF CONTOPOULOS, J TI MAGNETICALLY DRIVEN RELATIVISTIC JETS AND WINDS - EXACT-SOLUTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, JETS; MHD; STARS, MASS LOSS ID ACTIVE GALACTIC NUCLEI; HYDROMAGNETIC FLOWS; ASTROPHYSICAL JETS; ACCRETION DISKS; RADIO-SOURCES; OBJECTS; MODEL AB We present self-consistent solutions of the full set of ideal MHD equations which describe steady-state relativistic cold outflows from thin accretion disks. The magnetic field forms a spiral which is anchored in the disk, rotates with it, and accelerates the how out of the disk plane. The collimation at large distances depends on the total amount of electric current that flows along the jet. We considered various distributions of electric current and derived the result that in straight jets which extend to infinite distances, a strong electric current flows along their axis of symmetry. The asymptotic flow velocities are of the order of the initial rotational velocity at the base of the how (a few tenths of the speed of light). The solutions are applied to both galactic (small-scale) and extragalactic (large-scale) jets. RP CONTOPOULOS, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 23 TC 70 Z9 70 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 1994 VL 432 IS 2 BP 508 EP 517 DI 10.1086/174590 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE877 UT WOS:A1994PE87700010 ER PT J AU MADEJSKI, G AF MADEJSKI, G TI SOFT-X-RAY SPECTRUM OF BL LACERTAE OBJECT AO-0235-164 AS A TRACER OF ELEMENTAL ABUNDANCES AT Z-APPROXIMATE-TO-0.5 SO ASTROPHYSICAL JOURNAL LA English DT Article DE LACERTAE OBJECTS, INDIVIDUAL (AO 0235+164); GALAXIES, ABUNDANCES; QUASARS, ABSORPTION LINES; X-RAYS, GALAXIES ID EXTRAGALACTIC RADIO-SOURCES; CENTIMETER ABSORPTION; PKS-1413+135; GALAXY; LINE AB We report the soft X-ray spectrum of BL Lac object AO 0235 + 164, observed with the Einstein Observatory Imaging Proportional Counter. This object (z = 0.94) has an intervening galaxy (or a protogalactic disk) at z = 0.524 present in the line of sight, producing both radio and optical absorption lines in the background BL Lac continuum. The X-ray spectrum exhibits a substantial soft X-ray cutoff, corresponding to several times that expected from our own Galaxy; we interpret that excess cutoff as due to the intervening galaxy. The comparison of the hydrogen column density inferred from the 21 cm radio data and the X-ray absorption allows, in principle, the determination of the elemental abundances in the intervening galaxy. However, the uncertainties in both the H I spin temperature and X-ray spectral parameters only loosely restrict these abundances to be 2 +/- 1 solar, which even at the lower limit appears higher than that inferred from studies of samples of optical absorption-line systems. C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. RP MADEJSKI, G (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 34 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1994 VL 432 IS 2 BP 554 EP 559 DI 10.1086/174593 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE877 UT WOS:A1994PE87700013 ER PT J AU DOLAN, JF BOYD, PT WOLINSKI, KG SMITH, PS IMPEY, CD BLESS, RC NELSON, MJ PERCIVAL, JW TAYLOR, MJ ELLIOT, JL ROBINSON, EL VANCITTERS, GW AF DOLAN, JF BOYD, PT WOLINSKI, KG SMITH, PS IMPEY, CD BLESS, RC NELSON, MJ PERCIVAL, JW TAYLOR, MJ ELLIOT, JL ROBINSON, EL VANCITTERS, GW TI THE LINEAR-POLARIZATION OF 3C-345 IN THE ULTRAVIOLET SO ASTROPHYSICAL JOURNAL LA English DT Article DE POLARIZATION; QUASARS, INDIVIDUAL (3C 345); ULTRAVIOLET, GALAXIES ID QUASAR 3C-345; OBJECTS AB The linear polarization of 3C 345, a superluminal radio source and OW quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 Angstrom and 2770 Angstrom) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the W (p > 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. (1986, 1988). This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV WISCONSIN,SPACE ASTRON LAB,MADISON,WI 53706. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. NATL SCI FDN,DIV ASTRON SCI,ARLINGTON,VA 22230. PURDUE UNIV,DEPT PHYS,W LAFAYETTE,IN 47907. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP DOLAN, JF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Boyd, Patricia/D-3274-2012 NR 29 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1994 VL 432 IS 2 BP 560 EP 566 DI 10.1086/174594 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE877 UT WOS:A1994PE87700014 ER PT J AU SEO, ES MCDONALD, FB LAL, N WEBBER, WR AF SEO, ES MCDONALD, FB LAL, N WEBBER, WR TI STUDY OF COSMIC-RAY H-ISOTOPE AND HE-ISOTOPE AT 23 AU SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; INTERPLANETARY MEDIUM; ISM, ABUNDANCES ID ENERGY-SPECTRA; PRIMARY RATIOS; TRANSPORT; ACCELERATION; HELIOSPHERE; MINIMUM; DRIFT AB We have measured the spectra of H and He isotopes during the 1987 solar minimum with the cosmic-ray detector system (CRS) on the Voyager 2 spacecraft. By carrying out the measurement near solar minimum and at large heliospheric distances, the effects of solar modulation were reduced. In particular, the adiabatic energy losses were smaller, and these results from 23 AU over the solar minimum period of cycle 21 represent observations at energies not accessible from previous measurements near 1 AU. The modulated spectra with the diffusion coefficient constant k(0) = 3.15 x 10(22) cm(2) s(-1) (which corresponds to a solar modulation parameter of 360 MV at 23 AU and 500 MV at 1 AU) agree well with both our data at 23 AU and the previous solar minimum measurements at 1 AU. The measured H-1 and H-2 spectra are both consistent with the calculated spectra, using standard Galactic and heliospheric propagation models without invoking an anomalous hydrogen component. With the fixed modulation parameter of 360 MV, the mean pathlengths, source spectra, and cross sections were varied to study the effects of different input parameters on the spectra and relative abundances. At this stage of our work, we have not found any strong evidence from the low-energy H-2 and He-3 data that H-1 and He-4 should have a different propagation history, or different types of source spectra from the heavier cosmic-ray nuclei. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. RP SEO, ES (reprint author), UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742, USA. OI Seo, Eun-Suk/0000-0001-8682-805X NR 31 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 SEP 10 PY 1994 VL 432 IS 2 BP 656 EP 664 DI 10.1086/174604 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE877 UT WOS:A1994PE87700024 ER PT J AU MACALPINE, GM LAWRENCE, SS BROWN, BA UOMOTO, A WOODGATE, BE BROWN, LW OLIVERSEN, RJ LOWENTHAL, JD LIU, C AF MACALPINE, GM LAWRENCE, SS BROWN, BA UOMOTO, A WOODGATE, BE BROWN, LW OLIVERSEN, RJ LOWENTHAL, JD LIU, C TI EXTRAORDINARY LINE-EMITTING KNOTS IN THE CRAB-NEBULA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (CRAB NEBULA); PULSARS, INDIVIDUAL (PSR 0531+21); SUPERNOVA REMNANTS AB Extraordinary, semistellar, line-emitting knots are apparent in images of the Crab Nebula which were obtained with the Goddard Fabry-Perot imager at the Michigan-Dartmouth-MIT Observatory. The knots are most prominent for [O III] lambda5007 emission through a 5.3 angstrom (FWHM) bandpass centered at 5015.3 angstrom, with representative fluxes of roughly 10(-11) ergs cm-2 s-1. They are aligned in arcs, seven to the north and four to the south, from the pulsar. The northern group appears to be in a bounded corridor through the filamentary structure. Measurements over a 2 year baseline yield proper motions of order 0.1'' yr-1, corresponding to transverse velocities of order 900 km s-1 for a distance of 1830 pc. The knots are characterized by remarkably strong [Ar III] emission, possibly indicating high argon abundances, high gas temperatures, or anomalous physical processes. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF SANTA CRUZ,LICK OBSERV,SANTA CRUZ,CA 95064. UNIV ARIZONA,DEPT ASTRON,TUCSON,AZ 85721. RP MACALPINE, GM (reprint author), UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109, USA. RI Woodgate, Bruce/D-2970-2012 NR 13 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 1994 VL 432 IS 2 BP L131 EP & DI 10.1086/187529 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE878 UT WOS:A1994PE87800015 ER PT J AU MACARIO, A HAXBY, WF GOFF, JA RYAN, WBF CANDE, SC RAYMOND, CA AF MACARIO, A HAXBY, WF GOFF, JA RYAN, WBF CANDE, SC RAYMOND, CA TI FLOW LINE VARIATIONS IN ABYSSAL HILL MORPHOLOGY FOR THE PACIFIC-ANTARCTIC RIDGE AT 65-DEGREES-S SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SPREADING RATE; MEDIAN VALLEY; OCEAN RIDGES; DEPENDENCE; ROUGHNESS; RISE; STATISTICS; FLANKS; AXIS AB We present the results of a statistical study on the morphological characteristics of abyssal hills recently mapped along two adjacent segments of the Pacific-Antarctic Ridge at 65 degrees S. The studied area is a densely surveyed corridor (60 km wide by 600 km long) which is centered on the Pitman Fracture Zone (PFZ) and extends to 12 Ma crust on both sides of the ridge. Abyssal hill size parameters (RMS height H and characteristic width lambda) are estimated using Hydrosweep multibeam data. Variations in abyssal hill characteristics are compared with spreading rate history and crustal structure (as inferred from the mantle Bouguer gravity) in order to indirectly quantify the evolution of this ridge crest system. The magnetic data document an abrupt acceleration in spreading rate from similar to 36 to similar to 63 mm/yr (full rate) at Chron 3a (5.7-6.4 Ma). Our results indicate a statistically significant negative correlation between abyssal hill size parameters and full spreading rates. Abyssal hills formed during the slower spreading period (ages >8 Ma; full rates 36-44 mm/yr) are 31-86% taller and 21- >100% wider than hills created during the faster spreading interval (ages <4 Ma; full rates 52-63 mm/yr). The well-resolved positive correlation between H and lambda is interpreted as an indication of temporal changes in the flexural rigidity of the lithosphere near the vicinity of the ridge crest and, by implication, axial thermal structure. However, we cannot rule out that such positive trend is due to constructional volcanism. The lack of correlation between crustal thick-ness and abyssal hill size parameters is likely to be caused by the small magnitude of crustal thickness variations along flow lines (similar to 0.4 km in contrast to similar to 2 km reported in previous studies for the Mid-Atlantic Ridge). The most significant variations in crustal thickness are seen across the PFZ (thinning from north to south by 0.5-0.7 km), which coincide with a well-resolved increase in the averaged lambda estimate. The predictions of the detachment surface model in terms of morphological and structural inside/outside corner asymmetries are not supported by our observations. The main variations in H and lambda that cannot be explained in terms of either the spreading rate or crustal thickness effect include the following: (1) anomalously large abyssal hills north of the PFZ for 4-6 Ma age crust; (2) abyssal hill size estimates for crustal ages greater than 8 Ma show significant asymmetry for opposite ridge flanks north of the PFZ; and (3) toward the segment ends, H estimates are 27-68% larger, while lambda estimates either do not significantly change (to the north of the PFZ) or are up to 40% smaller (to the south of the PFZ). We suggest that the H and lambda changes seen toward the segment ends are related to either an increase in the amount of extension (without a corresponding increase in the strength of the lithosphere) or variations in the relative contribution of constructional volcanism to overall abyssal hill morphology. C1 UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, DIV GEOL RES, LA JOLLA, CA 92093 USA. UNIV TEXAS, INST GEOPHYS, AUSTIN, TX 78759 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV, PALISADES, NY 10964 USA. RI Goff, John/B-9972-2008; OI Goff, John/0000-0001-9246-5048; Macario, Ana/0000-0003-3747-793X NR 41 TC 22 Z9 22 U1 0 U2 2 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 1994 VL 99 IS B9 BP 17921 EP 17934 DI 10.1029/94JB01409 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PG767 UT WOS:A1994PG76700021 ER PT J AU HERRING, TA DONG, DN AF HERRING, TA DONG, DN TI MEASUREMENT OF DIURNAL AND SEMIDIURNAL ROTATIONAL VARIATIONS AND TIDAL PARAMETERS OF EARTH SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GLOBAL POSITIONING SYSTEM; BASE-LINE INTERFEROMETRY; CORE-MANTLE BOUNDARY; OCEAN TIDES; RADIO INTERFEROMETRY; FORCED NUTATIONS; PERIODIC CHANGES; UNIVERSAL TIME; POLE POSITION; WORLD OCEAN AB We discuss the determination of diurnal and semidiurnal variations in the rotation rate and the direction of rotation axis of Earth from the analysis of 8 years of very long baseline interferometry (VLBI) data. This analysis clearly show that these variations are largely periodic and tidally driven; that is, the periods of the variations correspond to the periods of the largest lunar and solar tides. For rotation rate variations, expressed in terms of changes in universal time (UT), the tidal lines with the largest observed signals are O1 (amplitude 23.5 microseconds in time (mu s), period 25.82 solar hours); K1 (18.9 mu s, 23.93 hours); M2 (17.9 mu s, 12.54 hours); and S2 (8.6 mu s, 12.00 hours). For variations in the direction of the rotation axis (polar motion), significant signals exist in the retrograde semidiurnal band at the M2 and S2 tides (amplitudes 265 and 119 microarc seconds (mu as), respectively); the prograde diurnal band at the O1, K1, and Fl tides (amplitudes 199, 152, and 60 mu as, respectively); and the prograde semidiurnal band at the M2 and K2 tides (amplitudes 58 and 39 mu as, respectively). Variations in the retrograde diurnal band are represented by corrections to the nutations of Earth's body axes, and our estimates here are consistent with previous estimates except that a previously noted discrepancy in the 13.66-day nutation (corresponding to the O1 tide) is largely removed in this new analysis. We estimate that the standard deviations of these estimates are 1.0 mu s for the UT1 variations and 14-16 mu as for the polar motion terms. These uncertainties correspond to surface displacements of similar to 0.5 mm. From the analysis of atmospheric angular momentum data we conclude that variations in UT1 excited by the atmosphere with subdaily periods are small (similar to 1 mu s). We find that the average radial tidal displacements of the VLBI sites in the diurnal band are largely consistent with known deficiencies in current tidal models, i.e., deficiencies of up to 0.9 mm in the treatment of the free core nutation resonance. In the semidiurnal band, our analysis yields estimates of the second-degree harmonic radial Love number h(2) at the M2 tide of 0.604+i0.005 +/- 0.002. The most likely explanation for the rotational variations are the effects of ocean tides, but there may also be some contributions from atmospheric tides, the effects of triaxiality of Earth, and the equatorial second-degree-harmonic components of the core-mantle boundary. C1 MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. RP HERRING, TA (reprint author), JET PROPULS LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 53 TC 60 Z9 63 U1 0 U2 7 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 1994 VL 99 IS B9 BP 18051 EP 18071 DI 10.1029/94JB00341 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PG767 UT WOS:A1994PG76700030 ER PT J AU MACMILLAN, DS GIPSON, JM AF MACMILLAN, DS GIPSON, JM TI ATMOSPHERIC-PRESSURE LOADING PARAMETERS FROM VERY LONG-BASE-LINE INTERFEROMETRY OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID EARTHS SURFACE; GRAVITY AB Atmospheric mass loading produces a primarily vertical displacement of the Earth's crust. This displacement is correlated with surface pressure and is large enough to be detected by very long baseline interferometry (VLBI) measurements. Using the measured surface pressure at VLBI stations, we have estimated the atmospheric loading term for each station location directly from VLBI data acquired from 1979 to 1992. Our estimates of the vertical sensitivity to change in pressure range from 0 to -0.6 mm/mbar depending on the station. These estimates agree with inverted barometer model calculations (Manabe et al., 1991; vanDam and Herring, 1994) of the vertical displacement sensitivity computed by convolving actual pressure distributions with loading Green's functions. The pressure sensitivity tends to be smaller for stations near the coast, which is consistent with the inverted barometer hypothesis. Applying this estimated pressure loading correction in standard VLBI geodetic analysis improves the repeatability of estimated lengths of 25 out of 37 baselines that were measured at least 50 times. In a root-sum-square (rss) sense, the improvement generally increases with baseline length at a late of about 0.3 to 0.6 ppb depending on whether the baseline stations are close to the coast. For the 5998-km baseline from Westford, Massachusetts, to Wettzell, Germany, the rss improvement is about 3.6 mm our of 11.0 mm. The average rss reduction of the vertical scatter for inland stations ranges from 2.7 to 5.4 mm. RP MACMILLAN, DS (reprint author), NASA, GODDARD SPACE FLIGHT CTR, NVI INC, CODE 926-9, GREENBELT, MD 20771 USA. NR 14 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD SEP 10 PY 1994 VL 99 IS B9 BP 18081 EP 18087 DI 10.1029/94JB01190 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PG767 UT WOS:A1994PG76700032 ER PT J AU BELTON, MJS CHAPMAN, CR VEVERKA, J KLAASEN, KP HARCH, A GREELEY, R GREENBERG, R HEAD, JW MCEWEN, A MORRISON, D THOMAS, PC DAVIES, ME CARR, MH NEUKUM, G FANALE, FP DAVIS, DR ANGER, C GIERASCH, PJ INGERSOLL, AP PILCHER, CB AF BELTON, MJS CHAPMAN, CR VEVERKA, J KLAASEN, KP HARCH, A GREELEY, R GREENBERG, R HEAD, JW MCEWEN, A MORRISON, D THOMAS, PC DAVIES, ME CARR, MH NEUKUM, G FANALE, FP DAVIS, DR ANGER, C GIERASCH, PJ INGERSOLL, AP PILCHER, CB TI FIRST IMAGES OF ASTEROID-243-IDA SO SCIENCE LA English DT Article ID SOLAR-SYSTEM; FAMILIES; EVOLUTION; PHOBOS AB The first images of the asteroid 243 Ida from Galileo show an irregular object measuring 56 kilometers by 24 kilometers by 21 kilometers. Its surface is rich in geologic features, including systems of grooves, blocks, chutes, albedo features, crater chains, and a full range of crater morphologies. The largest blocks may be distributed nonuniformly across the surface; lineaments and dark-floored craters also have preferential locations. Ida is interpreted to have a substantial regolith. The high crater density and size-frequency distribution (-3 differential power-law index) indicate a surface in equilibrium with saturated cratering. A minimum model crater age for Ida-and therefore for the Koronis family to which Ida belongs-is estimated at 1 billion years, older than expected. C1 SCI APPLICAT INT CORP,INST PLANETARY SCI,TUCSON,AZ 85705. NATL OPT ASTRON OBSERV,TUCSON,AZ 85719. CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. CALTECH,JET PROP LAB,PASADENA,CA 91109. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. BROWN UNIV,DEPT GEOL,PROVIDENCE,RI 02912. US GEOL SURVEY,FLAGSTAFF,AZ 86001. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RAND CORP,SANTA MONICA,CA 90406. US GEOL SURVEY,MENLO PK,CA 94025. DEUTSCH FORSCH ANSTALT LUFT & RAUMFAHRT,INST PLANETARY EXPLORAT,BERLIN,GERMANY. UNIV HAWAII,INST GEOPHYS,HONOLULU,HI 96822. INST SPACE & TERR SCI,CONCORD L4K 3C8,ON,CANADA. CALTECH,PASADENA,CA 91125. NASA,WASHINGTON,DC 20546. NR 33 TC 94 Z9 94 U1 1 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD SEP 9 PY 1994 VL 265 IS 5178 BP 1543 EP 1547 DI 10.1126/science.265.5178.1543 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PF336 UT WOS:A1994PF33600023 PM 17801529 ER PT J AU SMITH, GD JAFFE, RL YOON, DY AF SMITH, GD JAFFE, RL YOON, DY TI CONFORMATIONAL CHARACTERISTICS OF DIMETHOXYMETHANE BASED UPON AB-INITIO ELECTRONIC-STRUCTURE CALCULATIONS SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID MODEL MOLECULES; 1,2-DIMETHOXYETHANE; ENERGIES AB The conformational properties of dimethoxymethane (DMM) have been determined from ab initio electronic structure calculations as a critical step in the characterization of the conformational statistics of poly-(oxymethylene). The preference of the gauche (g) conformation of the C...O-C...O bond over the trans (t) conformation, as denoted by the energy Delta E(gt) of the gt conformer relative to the g conformer, was found to depend strongly on basis set size, with the energy decreasing from 4.7 kcal/mol for a 4-31G MP2 calculation to 2.8 kcal/mol using a D95+(2df,p) basis set, also at the MP2 level. Electron correlation effects were also found to be important but were accounted for accurately at the MP2 level; calculations of correlation effects beyond the MP2 level resulted in only a slight decrease in Delta E(gt). These effects led to a best estimate for Delta E(gt) of ca. 2.5 kcal/mol. Such a strong preference for the g conformation results in a very steep energy well for the DMM gg conformer relative to the remaining conformers. In terms of a rotational isomeric state (RIS) model, this necessitates the inclusion of preexponential factors for the statistical weights which deviate significantly from unity. The energies and preexponential factors which were estimated from the ab initio calculations yielded RIS conformer populations for DMM that reproduce the gas-phase dipole moment and NMR vicinal coupling constant as a function of temperature, in good agreement with experiment. C1 IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. RP SMITH, GD (reprint author), NASA,AMES RES CTR,INST THERMOSCI,RTC 230-3,MOFFETT FIELD,CA 94035, USA. NR 14 TC 36 Z9 36 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 8 PY 1994 VL 98 IS 36 BP 9072 EP 9077 DI 10.1021/j100087a040 PG 6 WC Chemistry, Physical SC Chemistry GA PF331 UT WOS:A1994PF33100040 ER PT J AU SMITH, GD JAFFE, RL YOON, DY AF SMITH, GD JAFFE, RL YOON, DY TI CONFORMATIONAL CHARACTERISTICS OF POLY(OXYMETHYLENE) BASED UPON AB-INITIO ELECTRONIC-STRUCTURE CALCULATIONS ON MODEL MOLECULES SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ENERGIES AB A revised rotational isomeric state (RIS) model for poly(oxymethylene) (POM) chains has been developed on the basis of the conformational energetics of the model molecules, dimethoxymethane (DMM) and 1,3-dimethoxydimethyl ether (DEE), as determined from ab initio electronic structure calculations. Due to the strong preference for gauche (g) conformations in POM chains, the energy minima for the g states were found to be deep and narrow, necessitating the inclusion of preexponential factors for the statistical weights in the RIS model that deviate from unity. Therefore, both the energy minima and preexponential factors for all of the important conformations of the model molecules were estimated by performing ab initio electronic structure calculations using a D95+(2df,p) basis set. Electron correlation effects were included at the MP2 level. The revised RIS model, with all parameters estimated from ab initio calculations, predicts the unperturbed chain dimensions and the dipole moment of POM chains as a function of temperature in good agreement with experiments. Therefore, it is demonstrated that ab initio calculations at the level of theory employed (D95+(2df,p) basis set at the MP2 level) are sufficient to provide accurate estimates of the conformational energetics of POM chains. Moreover, it is also shown that proper description of the conformation-dependent properties of POM chains requires consideration of not only the energy minima but also the energy well profile for each of the important conformations. C1 NASA,AMES RES CTR,INST THERMOSCI,RTC 230-3,MOFFETT FIELD,CA 94035. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. NR 15 TC 16 Z9 16 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD SEP 8 PY 1994 VL 98 IS 36 BP 9078 EP 9082 DI 10.1021/j100087a041 PG 5 WC Chemistry, Physical SC Chemistry GA PF331 UT WOS:A1994PF33100041 ER PT J AU MARTIN, JH COALE, KH JOHNSON, KS FITZWATER, SE GORDON, RM TANNER, SJ HUNTER, CN ELROD, VA NOWICKI, JL COLEY, TL BARBER, RT LINDLEY, S WATSON, AJ VANSCOY, K LAW, CS LIDDICOAT, MI LING, R STANTON, T STOCKEL, J COLLINS, C ANDERSON, A BIDIGARE, R ONDRUSEK, M LATASA, M MILLERO, FJ LEE, K YAO, W ZHANG, JZ FRIEDERICH, G SAKAMOTO, C CHAVEZ, F BUCK, K KOLBER, Z GREENE, R FALKOWSKI, P CHISHOLM, SW HOGE, F SWIFT, R YUNGEL, J TURNER, S NIGHTINGALE, P HATTON, A LISS, P TINDALE, NW AF MARTIN, JH COALE, KH JOHNSON, KS FITZWATER, SE GORDON, RM TANNER, SJ HUNTER, CN ELROD, VA NOWICKI, JL COLEY, TL BARBER, RT LINDLEY, S WATSON, AJ VANSCOY, K LAW, CS LIDDICOAT, MI LING, R STANTON, T STOCKEL, J COLLINS, C ANDERSON, A BIDIGARE, R ONDRUSEK, M LATASA, M MILLERO, FJ LEE, K YAO, W ZHANG, JZ FRIEDERICH, G SAKAMOTO, C CHAVEZ, F BUCK, K KOLBER, Z GREENE, R FALKOWSKI, P CHISHOLM, SW HOGE, F SWIFT, R YUNGEL, J TURNER, S NIGHTINGALE, P HATTON, A LISS, P TINDALE, NW TI TESTING THE IRON HYPOTHESIS IN ECOSYSTEMS OF THE EQUATORIAL PACIFIC-OCEAN SO NATURE LA English DT Article ID SUB-ARCTIC PACIFIC; MARINE-PHYTOPLANKTON; PRODUCTIVITY; ENVIRONMENTS; LIMITATION; SEAWATER; GROWTH; WATER; SEA AB The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km(2) in the open equatorial Pacific Ocean with iron. This resulted in a doubling of plant biomass, a threefold increase In chlorophyll and a fourfold increase in plant production. Similar increases were found in a chlorophyll-rich plume downstream of the Galapagos Islands, which was naturally enriched in iron. These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean. C1 MOSS LANDING MARINE LABS,MOSS LANDING,CA 95039. DUKE UNIV,MARINE LAB,BEAUFORT,NC 28516. PLYMOUTH MARINE LAB,PLYMOUTH PL1 3DH,ENGLAND. USN,POSTGRAD SCH,MONTEREY,CA 93943. UNIV HAWAII,DEPT OCEANOG,HONOLULU,HI 96822. UNIV MIAMI,ROSENSTIEL SCH MARINE & ATMOSPHER SCI,MIAMI,FL 33149. MONTEREY BAY AQUARIUM RES INST,PACIFIC GROVE,CA 93950. BROOKHAVEN NATL LAB,DIV OCEANOG & ATMOSPHER SCI,UPTON,NY 11973. MIT,DEPT CIVIL & ENVIRONM ENGN,RALPH M PARSONS LAB,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. UNIV E ANGLIA,SCH ENVIRONM SCI,NORWICH NR4 7TJ,NORFOLK,ENGLAND. TEXAS A&M UNIV,DEPT METEOROL,COLLEGE STN,TX 77843. RI Latasa, Mikel/D-2202-2011; Zhang, Jia-Zhong/B-7708-2008; Johnson, Kenneth/F-9742-2011; Ondrusek, Michael/F-5617-2010; LISS, Peter/A-8219-2013; Hatton, Angela/D-6196-2013; Nightingale, Philip/I-4324-2012; Lindley, Steven/G-3997-2014 OI Latasa, Mikel/0000-0002-8202-0923; Zhang, Jia-Zhong/0000-0002-1138-2556; Johnson, Kenneth/0000-0001-5513-5584; Ondrusek, Michael/0000-0002-5311-9094; Nightingale, Philip/0000-0001-7177-5469; Lindley, Steven/0000-0001-9556-0411 NR 52 TC 917 Z9 980 U1 12 U2 177 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD SEP 8 PY 1994 VL 371 IS 6493 BP 123 EP 129 DI 10.1038/371123a0 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PF191 UT WOS:A1994PF19100054 ER PT J AU CONNOLLY, HC HEWINS, RH ASH, RD ZANDA, B LOFGREN, GE BOUROTDENISE, M AF CONNOLLY, HC HEWINS, RH ASH, RD ZANDA, B LOFGREN, GE BOUROTDENISE, M TI CARBON AND THE FORMATION OF REDUCED CHONDRULES SO NATURE LA English DT Article ID DYNAMIC CRYSTALLIZATION; CHONDRITES; TEXTURES; ORIGIN; MELTS AB CHONDRULES are millimetre-sized spheroidal bodies composed mainly of olivine and orthopyroxene, which comprise the dominant fraction of most chondritic meteorites. They are the products of partial melting of aggregates of fine-grained silicates with minor contributions from metals, sulphides and oxides. Although the formation conditions of chondrules are not well understood, these are thought to involve a transient melting event in the solar nebula(1-3). The ubiquity of reduced carbon in interstellar clouds and primitive meteorites implies that it was also present in the early solar nebula, and may thus have been a potential constituent of chondrule precursor material. We describe here experiments in which carbon and magnesian silicate precursor material of primitive chondrule composition are 'flash-heated' together and then crystallized. The resulting material shows many mineralogical features characteristic of natural chondrules, which are not produced in the absence of carbon(4-12). Our results suggest not only that carbon was present in the solar nebula, but also that it played a key role in chondrule formation by creating within the melt a reducing environment that was decoupled from the nebula gas. C1 UNIV MANCHESTER,DEPT GEOL,MANCHESTER M13 9PL,LANCS,ENGLAND. MUSEUM NATL HIST NAT,MINERAL LAB,F-75005 PARIS,FRANCE. INST ASTROPHYS SPATIALE,ORSAY,FRANCE. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP CONNOLLY, HC (reprint author), RUTGERS STATE UNIV,DEPT GEOL SCI,NEW BRUNSWICK,NJ 08903, USA. RI Zanda, Brigitte/D-6787-2015 OI Zanda, Brigitte/0000-0002-4210-7151 NR 29 TC 66 Z9 66 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD SEP 8 PY 1994 VL 371 IS 6493 BP 136 EP 139 DI 10.1038/371136a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PF191 UT WOS:A1994PF19100056 ER PT J AU SINGH, J AF SINGH, J TI MICROSTRUCTURAL EVOLUTION OF DIAMOND GROWTH DURING HFCVD SO ACTA METALLURGICA ET MATERIALIA LA English DT Article ID CHEMICAL-VAPOR-DEPOSITION; METHANE; FILMS; ACETYLENE AB High resolution transmission electron microscopy (HRTEM) was used to study the nucleation and growth mechanism of diamond by hot filament chemical vapor deposition (HFCVD) process. A novel technique has shown a direct evidence for the formation of the diamond-like carbon layer 8-14 nm thick in which small diamond micro-crystallites were embedded. These diamond micro-crystallites were formed as a result of transformation of diamond-like carbon into diamond. The diamond micro-crystallites present in the amorphous diamond-like carbon layer provided nucleation sites for diamond growth. Large diamond crystallites were observed to grow from these micro-crystallites. The mechanism of diamond growth will be presented based on experimental findings. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NR 21 TC 2 Z9 2 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-7151 J9 ACTA METALL MATER JI Acta Metall. Mater. PD SEP PY 1994 VL 42 IS 9 BP 3197 EP 3208 DI 10.1016/0956-7151(94)90418-9 PG 12 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA PB268 UT WOS:A1994PB26800031 ER PT J AU HARRIS, RT DUDLEY, GA AF HARRIS, RT DUDLEY, GA TI FACTORS LIMITING FORCE DURING SLOW, SHORTENING ACTIONS OF THE QUADRICEPS FEMORIS MUSCLE GROUP IN-VIVO SO ACTA PHYSIOLOGICA SCANDINAVICA LA English DT Article DE FORCE-VELOCITY; HUMAN SKELETAL MUSCLE; NEUROMUSCULAR ID VELOCITY RELATIONSHIPS; FIBER COMPOSITION; ACTIVATION; TORQUE; HUMANS AB Speed-torque relations of the quadriceps femors muscle group were determined using eight healthy subjects. Isometric or isovelocity, shortening muscle actions were performed at 15 speeds (0-6.28 rad s(-1)) and torque was measured 0.78 and 0.52 rad below horizontal. Unilateral actions were evoked by surface electrical stimulation or by maximal voluntary effort. Stimulation current evoked a torque equal to approx. 70% of maximal voluntary isometric and was held constant across speeds. For the voluntary or stimulation tests, torque decreased (P < 0.05) with increasing speed. This response in relative terms was greater (P < 0.05) for the stimulation than for the voluntary tests. The difference in the decline in relative torque for the simulation vs. voluntary tests was not influenced by the angle at which torque was measured, and thereby muscle length. Speed-torque data for the two stimulation tests fit a linearized plot of a hyperbolic relation for the higher tests speeds. When torque was measured at the greater joint angle (0.78 rad), and thereby longer muscle length, the equation was Po-P/V = Po 0.724-1.078 (P < 0.05, r(2) = 0.95) for speeds greater than 0.70 rad s(-1). For the shorter muscle length, the equation for data collected at speeds greater than 1.13 rad s(-1) was Po - P/V = Po 0.467 + 4.61 (P < 0.05, r(2) = 0.91). Inclusion of data for the next slower speed markedly compromised the 'fit' for either linear relation. The results suggest that the extent of force limitation by 'some neural inhibitory mechanism' during maximal voluntary effort has previously been over-estimated because the speed-torque relation for the quadriceps femoris muscle group was not hyperbolic in nature at 'slow' speeds when involuntary, shortening actions were studied. The magnitude of force limitation does not, however, appear to depend on muscle length. C1 OHIO UNIV,DEPT BIOL SCI,ATHENS,OH 45701. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. NR 25 TC 17 Z9 17 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0001-6772 J9 ACTA PHYSIOL SCAND JI Acta Physiol. Scand. PD SEP PY 1994 VL 152 IS 1 BP 63 EP 71 DI 10.1111/j.1748-1716.1994.tb09785.x PG 9 WC Physiology SC Physiology GA PF497 UT WOS:A1994PF49700007 PM 7810333 ER PT J AU PIATETSKYSHAPIRO, G MATHEUS, C SMYTH, P UTHURUSAMY, R AF PIATETSKYSHAPIRO, G MATHEUS, C SMYTH, P UTHURUSAMY, R TI KDD-93 - PROGRESS AND CHALLENGES IN KNOWLEDGE DISCOVERY IN DATABASES SO AI MAGAZINE LA English DT Editorial Material AB Over 60 researchers from 10 countries took part in the Third Knowledge Discovery in Databases (KDD) Workshop, held during the Eleventh National Conference on Artificial Intelligence in Washington, D.C. A major trend evident at the workshop was the transition to applications in the core KDD area of discovery of relatively simple patterns in relational databases; the most successful applications are appearing in the areas of greatest need, where the databases are so large that manual analysis is impossible. Progress has been facilitated by the availability of commercial KDD tools for both generic discovery and domain-specific applications such as marketing. At the same time, progress has been slowed by problems such as lack of statistical rigor, overabundance of patterns, and poor integration. Besides applications, the main themes of this workshop were (1) the discovery of dependencies and models and (2) integrated and interactive KDD systems. C1 JET PROP LAB,TECH GRP,PASADENA,CA 91109. GM CORP,RES LABS,DETROIT,MI 48202. RP PIATETSKYSHAPIRO, G (reprint author), GTE LABS INC,KNOWLEDGE DISCOVERY DATABASES PROJECT,WALTHAM,MA 02254, USA. NR 25 TC 5 Z9 5 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD FAL PY 1994 VL 15 IS 3 BP 77 EP 82 PG 6 WC Computer Science, Artificial Intelligence SC Computer Science GA PK574 UT WOS:A1994PK57400008 ER PT J AU YU, ST HULTGREN, LS LIU, NS AF YU, ST HULTGREN, LS LIU, NS TI DIRECT CALCULATIONS OF WAVES IN FLUID-FLOWS USING HIGH-ORDER COMPACT DIFFERENCE SCHEME SO AIAA JOURNAL LA English DT Article AB The solution of the unsteady Euler equations by a sixth-order compact difference scheme combined with a fourth-order Runge-Kutta method is investigated. Closed-form expressions for the amplification factors and their corresponding dispersion correlations are obtained by Fourier analysis of the fully discretized, two-dimensional Euler equations. The numerical dissipation, dispersion, and anisotropic effects are assessed. It is found that the CFL limit for stable calculations is about 0.8. For a CFL number equal to 0.6, the smallest wavelength which is resolved without numerical damping is about six-eight grid nodes. For phase speeds corresponding to acoustic waves, the corresponding time period is resolved by about 200-300 time steps. Three numerical examples of waves in compressible flow are included: 1) sound propagation in a duct with linear shear, 2) linear wave growth in a compressible free shear layer, and 3) vortex pairing in a compressible free shear layer perturbed at two frequencies. C1 SVERDRUP TECHNOL INC,BROOKPARK,OH 44142. NASA,LEWIS RES CTR,LEWIS RES ACAD,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. NR 8 TC 8 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1994 VL 32 IS 9 BP 1766 EP 1773 DI 10.2514/3.12172 PG 8 WC Engineering, Aerospace SC Engineering GA PF092 UT WOS:A1994PF09200002 ER PT J AU CHEN, CL CHAKRAVARTHY, SR HUNG, CM AF CHEN, CL CHAKRAVARTHY, SR HUNG, CM TI NUMERICAL INVESTIGATION OF SEPARATED NOZZLE FLOWS SO AIAA JOURNAL LA English DT Article AB A numerical study of axisymmetric overexpanded nozzle flows is presented. The flow structures of the startup and throttle-down processes are examined. During the impulsive startup process, observed flow features include the Mach disk, separation shock, Mach stem, vortex core, contact surface, slip stream, initial shock front, and shocklet. Also the movement of the Mach disk is not monotonical in the downstream direction. For a range of pressure ratios, hysteresis phenomenon occurs; different solutions were obtained depending on different processes. Three types of flow structures were observed. The location of separation point and the lower end turning point of hysteresis are closely predicted. A high peak of pressure is associated with the nozzle flow reattachment. The reversed vortical structure trapped behind the Mach disk appears to be key to causing the differences in the flow structures and affects engine performance. C1 NASA,AMES RES CTR,DIV FLUID DYNAM,MOFFETT FIELD,CA 94035. RP CHEN, CL (reprint author), ROCKWELL INT SCI CTR,DEPT COMPUTAT FLUID DYNAM,THOUSAND OAKS,CA 91360, USA. NR 9 TC 49 Z9 50 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 1994 VL 32 IS 9 BP 1836 EP 1843 DI 10.2514/3.12181 PG 8 WC Engineering, Aerospace SC Engineering GA PF092 UT WOS:A1994PF09200011 ER PT J AU GARTENBURG, E WRIGHT, RE AF GARTENBURG, E WRIGHT, RE TI BOUNDARY-LAYER-TRANSITION DETECTION WITH INFRARED IMAGING EMPHASIZING CRYOGENIC APPLICATIONS SO AIAA JOURNAL LA English DT Article AB This paper reviews the technique of boundary-layer transition detection using infrared (IR) imaging, emphasizing cryogenic wind-tunnel testing. With the exception of the low-temperature effects on the IR radiation, the discussion is relevant to conventional wind-tunnel and flight testing as well. At low temperatures, IR imaging encounters a reduction in the radiated energy throughout the IR spectrum, combined with a shift to longer wavelengths of the bulk of the radiation. This radiation behavior affects the minimum resolvable temperature difference (MRTD) of the IR imaging system because of its fixed wave band sensitivity. In the absence of commercial long wavelength IR imaging systems, operating at wavelengths longer than 13 mum, some measures can be taken to alleviate the problem caused by the MRTD limitation. The thermal signature of transition can be enhanced by allowing a small and controlled temperature increase of the wind-tunnel flow that induces a transient heat transfer to the model. This action temporarily reveals the model area under the turbulent regime through its higher heating rate compared with the laminar regime. The contrast between the areas exposed to the two regimes can be enhanced by subtraction of thermograms (the equilibrium thermogram from the transient thermogram). Further visual improvement can be obtained through shade stretching or binary shading. C1 NASA,LANGLEY RES CTR,DIV EXPTL TESTING TECHNOL,AERODYNAM MEASUREMENT BRANCH,HAMPTON,VA 23681. RP GARTENBURG, E (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23529, USA. NR 9 TC 9 Z9 9 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1994 VL 32 IS 9 BP 1875 EP 1882 DI 10.2514/3.12186 PG 8 WC Engineering, Aerospace SC Engineering GA PF092 UT WOS:A1994PF09200016 ER PT J AU KIM, CM KREJSA, EA KHARAVAN, A AF KIM, CM KREJSA, EA KHARAVAN, A TI SIGNIFICANCE OF SHOCK STRUCTURE ON SUPERSONIC JET MIXING NOISE OF AXISYMMETRICAL NOZZLES SO AIAA JOURNAL LA English DT Note C1 NYMA,LEWIS RES GRP,PROPELLER & ACOUST TECHNOL BRANCH,BROOKPARK,OH 44142. RP KIM, CM (reprint author), NASA,LEWIS RES CTR,TURBOMACHINERY TECHNOL BRANCH,MS 77-6,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 6 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1994 VL 32 IS 9 BP 1920 EP 1923 DI 10.2514/3.12192 PG 4 WC Engineering, Aerospace SC Engineering GA PF092 UT WOS:A1994PF09200022 ER PT J AU HUANG, PG BRADSHAW, P COAKLEY, TJ AF HUANG, PG BRADSHAW, P COAKLEY, TJ TI SKIN FRICTION AND VELOCITY PROFILE FAMILY FOR COMPRESSIBLE TURBULENT BOUNDARY-LAYERS - REPLY SO AIAA JOURNAL LA English DT Note C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. ELORET INST,DIV RES,PALO ALTO,CA 94303. RP HUANG, PG (reprint author), NASA,AMES RES CTR,MODELING & EXPTL VALIDAT BRANCH,MS 229-1,MOFFETT FIELD,CA 94035, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 1994 VL 32 IS 9 BP 1939 EP 1939 DI 10.2514/3.48304 PG 1 WC Engineering, Aerospace SC Engineering GA PF092 UT WOS:A1994PF09200031 ER PT J AU BECK, LR RODRIGUEZ, MH DISTER, SW RODRIGUEZ, AD REJMANKOVA, E ULLOA, A MEZA, RA ROBERTS, DR PARIS, JF SPANNER, MA WASHINO, RK HACKER, C LEGTERS, LJ AF BECK, LR RODRIGUEZ, MH DISTER, SW RODRIGUEZ, AD REJMANKOVA, E ULLOA, A MEZA, RA ROBERTS, DR PARIS, JF SPANNER, MA WASHINO, RK HACKER, C LEGTERS, LJ TI REMOTE-SENSING AS A LANDSCAPE EPIDEMIOLOGIC TOOL TO IDENTIFY VILLAGES AT HIGH-RISK FOR MALARIA TRANSMISSION SO AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE LA English DT Article ID ANOPHELES-ALBIMANUS DIPTERA; LARVAL HABITATS; SOUTHERN CHIAPAS; LANDSAT-TM; MEXICO; IDENTIFICATION; CULICIDAE; AREAS; PSEUDOPUNCTIPENNIS; CLASSIFICATION AB A landscape approach using remote sensing and geographic information system (GIS) technologies was developed to discriminate between villages at high and low risk for malaria transmission, as defined by adult Anopheles albimanus abundance. Satellite data for an area in southern Chiapas, Mexico were digitally processed to generate a map of landscape elements. The GIS processes were used to determine the proportion of mapped landscape elements surrounding 40 villages where An. albimanus abundance data had been collected. The relationships between vector abundance and landscape element proportions were investigated using stepwise discriminant analysis and stepwise linear regression. Both analyses indicated that the most important landscape elements in terms of explaining vector abundance were transitional swamp and unmanaged pasture. Discriminant functions generated for these two elements were able to correctly distinguish between villages with high and low vector abundance, with an overall accuracy of 90%. Regression results found both transitional swamp and unmanaged pasture proportions to be predictive of vector abundance during the mid-to-late wet season. This approach, which integrates remotely sensed data and GIS capabilities to identify villages with high vector-human contact risk, provides a promising tool for malaria surveillance programs that depend on labor-intensive field techniques. This is particularly relevant in areas where the lack of accurate surveillance capabilities may result in no malaria control action when, in fact, directed action is necessary. In general, this landscape approach could be applied to other vector-borne diseases in areas where 1) the landscape elements critical to vector survival are known and 2) these elements can be detected at remote sensing scales. C1 MINIST HLTH,CTR INVEST PALUDISMO,TAPACHULA 30700,CHIAPAS,MEXICO. UNIV CALIF DAVIS,DIV ENVIRONM STUDIES,DAVIS,CA 95616. UNIV CALIF DAVIS,DEPT ENTOMOL,DAVIS,CA 95616. UNIFORMED SERV UNIV HLTH SCI,BETHESDA,MD 20814. CALIF STATE UNIV FRESNO,DEPT BIOL,FRESNO,CA 93740. UNIV TEXAS,HLTH SCI CTR,HOUSTON,TX 77225. RP BECK, LR (reprint author), NASA,AMES RES CTR,JOHNSON CONTROLS WORLD SERV,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 37 TC 150 Z9 167 U1 0 U2 20 PU AMER SOC TROP MED & HYGIENE PI MCLEAN PA 8000 WESTPARK DRIVE SUITE 130, MCLEAN, VA 22101 SN 0002-9637 J9 AM J TROP MED HYG JI Am. J. Trop. Med. Hyg. PD SEP PY 1994 VL 51 IS 3 BP 271 EP 280 PG 10 WC Public, Environmental & Occupational Health; Tropical Medicine SC Public, Environmental & Occupational Health; Tropical Medicine GA PJ690 UT WOS:A1994PJ69000003 PM 7943544 ER PT J AU OGLESBY, DM UPCHURCH, BT LEIGHTY, BD COLLMAN, JP ZHANG, XM HERRMANN, PC AF OGLESBY, DM UPCHURCH, BT LEIGHTY, BD COLLMAN, JP ZHANG, XM HERRMANN, PC TI SURFACE-ACOUSTIC-WAVE OXYGEN SENSOR SO ANALYTICAL CHEMISTRY LA English DT Article ID DUAL-MODE TRANSPORT; BINDING HEMOPROTEINS; CHEMICAL-ANALYSIS; SYNTHETIC MODELS; MOLECULAR-OXYGEN; VAPOR SENSORS; MICROSENSORS; PORPHYRINS; MEMBRANE; COMPLEX AB A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158-MHz quartz SAW device with an oxygen-binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen-binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen-binding porphyrin in a toluene solution containing excess axial ligand without a polymer matrix. In the polymer-based coatings, the copolymer served to provide the axial ligand to the oxygen-binding agent and as a coating matrix on the surface of the SAW device. The oxygen,sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen-binding compound in the coating matrix. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. STANFORD UNIV,DEPT CHEM,STANFORD,CA 94305. RP OGLESBY, DM (reprint author), OLD DOMINION UNIV,DEPT CHEM & BIOCHEM,NORFOLK,VA 23529, USA. RI Zhang, Xumu/K-8746-2013 NR 24 TC 14 Z9 14 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0003-2700 J9 ANAL CHEM JI Anal. Chem. PD SEP 1 PY 1994 VL 66 IS 17 BP 2745 EP 2751 DI 10.1021/ac00089a023 PG 7 WC Chemistry, Analytical SC Chemistry GA PD717 UT WOS:A1994PD71700025 ER PT J AU SHANG, HM KIM, YM CHEN, CP WANG, TS AF SHANG, HM KIM, YM CHEN, CP WANG, TS TI NUMERICAL-STUDIES OF DROPLET TURBULENCE INTERACTIONS SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article; Proceedings Paper CT 1st Conference on Differential Equations and Computational Simulations CY MAR 19-20, 1993 CL MISSISSIPPI STATE, MS SP NATL SCI FDN, ENGN RES CTR, MISSISSIPPI STATE UNIV, DEPT MATH ID STATISTICAL TRANSPORT MODEL; PARTICLE DISPERSION; VELOCITY; SPRAYS; FLOW AB A nonevaporating atomized spray was studied for droplet turbulent dispersion and turbulence modulation. To account for the dense spray effects, turbulence modulation models, droplet collision model, and breakup model were incorporated into a state-of-the-art multiphase all-speed transient flow solution procedure. Comparative performance of the existing turbulence modulation models are discussed in details. A parcel probability density function (PDF) approach was implemented to improve the computational efficiency in droplet dispersion calculations. The numerical results indicate that the parcel PDF model has the capability of realistically representing turbulent dispersion in dense sprays with improved efficiency over the delta function stochastic separated flow (SSF) model. Numerical predictions show good agreement with available experimental data. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP SHANG, HM (reprint author), ENGN SCI INC,HUNTSVILLE,AL, USA. NR 17 TC 3 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD SEP-OCT PY 1994 VL 65 IS 1-3 BP 63 EP 78 DI 10.1016/0096-3003(94)90166-X PG 16 WC Mathematics, Applied SC Mathematics GA PZ275 UT WOS:A1994PZ27500006 ER PT J AU VU, B WANG, TS SHIH, MH SONI, B AF VU, B WANG, TS SHIH, MH SONI, B TI NAVIER-STOKES FLOW-FIELD ANALYSIS OF COMPRESSIBLE FLOW IN A HIGH-PRESSURE SAFETY RELIEF VALVE SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article; Proceedings Paper CT 1st Conference on Differential Equations and Computational Simulations CY MAR 19-20, 1993 CL MISSISSIPPI STATE, MS SP NATL SCI FDN, ENGN RES CTR, MISSISSIPPI STATE UNIV, DEPT MATH AB The objective of this study is to investigate the complex three-dimensional flow held of an oxygen safety pressure relieve valve during an incident, with a computational fluid dynamics (CFD) analysis. Specifically, the analysis will. provide a flow pattern that would lead to the explanation of the eventual erosion pattern of the hardware, so as to combine it with other findings to piece together a most likely scenario for the investigation. The CFD model is a pressure-based solver. An adaptive upwind difference scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the velocity-pressure coupling. The computational result indicated vortices formation near the opening of the valve which matched the erosion pattern of the damaged hardware. C1 MISSISSIPPI STATE UNIV,ENGN RES CTR COMPUTAT FIELD SIMULAT,MISSISSIPPI STATE,MS 39762. RP VU, B (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MSFIC,COMPUTAT FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812, USA. NR 6 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD SEP-OCT PY 1994 VL 65 IS 1-3 BP 345 EP 353 DI 10.1016/0096-3003(94)90187-2 PG 9 WC Mathematics, Applied SC Mathematics GA PZ275 UT WOS:A1994PZ27500027 ER PT J AU BLUMENSTOCK, GM KESKIKUHA, RAM AF BLUMENSTOCK, GM KESKIKUHA, RAM TI ION-BEAM-DEPOSITED BORON-CARBIDE COATINGS FOR THE EXTREME-ULTRAVIOLET SO APPLIED OPTICS LA English DT Note DE BORON CARBIDE; ULTRAVIOLET; REFLECTANCE; THIN FILMS; SPACE OPTICS AB The normal-incidence reflectance of ion-beam-deposited boron carbide thin films has been evaluated in the extreme ultraviolet (EUV) spectral region. High-reflectance coatings have been produced with reflectances greater than 30% between 67 and 121.6 nm. This high reflectance makes ion-beam-deposited boron carbide an attractive coating for EUV applications. RP BLUMENSTOCK, GM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 5 TC 30 Z9 31 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 1 PY 1994 VL 33 IS 25 BP 5962 EP 5963 PG 2 WC Optics SC Optics GA PF320 UT WOS:A1994PF32000019 PM 20936006 ER PT J AU KEFFER, CE TORR, MR ZUKIC, M SPANN, JF TORR, DG KIM, J AF KEFFER, CE TORR, MR ZUKIC, M SPANN, JF TORR, DG KIM, J TI RADIATION-DAMAGE EFFECTS IN FAR-ULTRAVIOLET FILTERS, THIN-FILMS, AND SUBSTRATES SO APPLIED OPTICS LA English DT Article DE RADIATION EFFECTS; ULTRAVIOLET FILTERS; THIN FILMS AB Advances in vacuum ultraviolet thin-film filter technology have been made through the use of filter designs with multilayers of materials such as Al2O3, BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2. Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 x 9 RE orbit will expose the instrument to approximately 250 krad of radiation. Because to our knowledge no previous studies have been made on the potential radiation damage of these materials in the thin-film format, we report on such an assessment here. Transmittances and reflectances of BaF2, CaF2, HfO2, MgF2, and SiO2 thin films on MgF2 substrates, Al2O3 thin films on fused-silica substrates, uncoated fused silica and MgF2, and four multilayer filters made from these materials were measured from 120 to 180 nm before and after irradiation by 250 krad from a Co-60 gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 to 300 nm indicates 2-5% radiation-induced absorption near 260 nm in some of the samples with MgF2 substrates. From these measurements we conclude that far-ultraviolet filters made from the materials tested should experience less than 5% change from exposure to up to 250 krad of high-energy radiation in space applications. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, PAYLOADS PROJECTS OFF, HUNTSVILLE, AL 35812 USA. RP KEFFER, CE (reprint author), UNIV ALABAMA, DEPT PHYS, OPT BLDG, SUITE 300, HUNTSVILLE, AL 35899 USA. NR 13 TC 2 Z9 2 U1 5 U2 10 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD SEP 1 PY 1994 VL 33 IS 25 BP 6041 EP 6045 PG 5 WC Optics SC Optics GA PF320 UT WOS:A1994PF32000030 PM 20936017 ER PT J AU MIZUGUCHI, K DAMM, GA ABER, GS BOZEMAN, RJ BACAK, JW SVEJKOVSKY, PA ORIME, Y OHARA, Y NAITO, K TASAI, K MAKINOUCHI, K TAKATANI, S NOSE, Y NOON, GP DEBAKEY, ME AF MIZUGUCHI, K DAMM, GA ABER, GS BOZEMAN, RJ BACAK, JW SVEJKOVSKY, PA ORIME, Y OHARA, Y NAITO, K TASAI, K MAKINOUCHI, K TAKATANI, S NOSE, Y NOON, GP DEBAKEY, ME TI DOES HEMATOCRIT AFFECT IN-VITRO HEMOLYSIS TEST-RESULTS - PRELIMINARY-STUDY WITH BAYLOR/NASA PROTOTYPE AXIAL-FLOW PUMP SO ARTIFICIAL ORGANS LA English DT Article DE HEMOLYSIS TEST; INDEX OF HEMOLYSIS; HEMATOCRIT; ROTARY BLOOD PUMP; AXIAL FLOW PUMP; STANDARDIZATION ID INVITRO AB The effect of hematocrit (Ht) on in vitro hemolysis test results (i.e., index of hemolysis) was evaluated using a Baylor/NASA prototype axial flow pump. Red blood cell suspensions of six different Ht (5, 10, 15, 20, 30, 40%; n = 30) were prepared and used for this evaluation. The pump was operated for 60 min under 5 L/min flow conditions, and blood samples were taken every 10 min to measure plasma free hemoglobin levels. The normalized index of hemolysis (NIH) was calculated using the regression line slope between time and plasma free hemoglobin level, and relationships between NIH and Ht or hemoglobin (Hb) were checked. NIH and Ht had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976, and NIH and Hb had a statistically significant (p < 0.0001) correlation with a coefficient of fit of 0.976. To reduce the effect of I-It, NIH/Ht was proposed and compared with a modified index of hemolysis (MIH), which was normalized by the Hb level of blood. NIH/Ht and MIH had a poor correlation with I-It (coefficient of fit, 0.608) and Hb (coefficient of fit, 0.577), respectively. When blood that has a wide range of I-It or Hb values is used for in vitro hemolysis tests, NIH/Ht is suggested for use as an index of hemolysis to evaluate the hemolysis characteristics of rotary blood pumps because MIH has no dimension and it requires Hb values. In contrast, NIH/Ht has a dimension of g/100 L, which is quite understandable, and it does not require measurement of Hb levels of blood; it is therefore cost-effective. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MIZUGUCHI, K (reprint author), BAYLOR COLL MED,DEPT SURG,1 BAYLOR PLAZA,HOUSTON,TX 77030, USA. NR 9 TC 22 Z9 22 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0160-564X J9 ARTIF ORGANS JI Artif. Organs PD SEP PY 1994 VL 18 IS 9 BP 650 EP 656 DI 10.1111/j.1525-1594.1994.tb03394.x PG 7 WC Engineering, Biomedical; Transplantation SC Engineering; Transplantation GA PG145 UT WOS:A1994PG14500006 PM 7998881 ER PT J AU BRIDLE, AH HOUGH, DH LONSDALE, CJ BURNS, JO LAING, RA AF BRIDLE, AH HOUGH, DH LONSDALE, CJ BURNS, JO LAING, RA TI DEEP VLA IMAGING OF 12 EXTENDED 3CR QUASARS SO ASTRONOMICAL JOURNAL LA English DT Review ID EXTRAGALACTIC RADIO-SOURCES; MULTIFREQUENCY OBSERVATIONS; COSMOLOGICAL EVOLUTION; SUPERLUMINAL MOTION; 5-KM TELESCOPE; LOW LUMINOSITY; JETS; GALAXIES; QSOS; EMISSION AB A representative sample of 12 extended quasars from the 3CR catalog has been imaged at 4.9 GHz using the VLA. These full synthesis observations typically achieve an rms noise of 20 mu Jy per beam, at a resolution (FWHM) of 0.''34 to 0.''38. Jets are detected on at least one side of every source. The jets are well collimated compared with those in less powerful sources, but spreading is detected in most of them. The opening angles of several jets are not constant, but show recollimation after an initial regime of rapid spreading. Many of the jets contain quasiperiodic strings of knots, of which the knot closest to the central feature is usually the brightest (until the jet nears its hot spot). The degrees of linear polarization at the jet knots range from <5% to similar to 50%, but show no common trend with distance along the jets. In knots that are elongated in directions close to that of the jet, the E vectors tend to be orthogonal to the jet axis. The exceptions-misaligned knots with misaligned polarizations-tend to be bright features near large bends in the jets. Many of the jets are initially straight to within a few degrees, but bend more in the outer part of the source. The prominence of the inner, straighter jet segments relative to the extended lobes correlates significantly with the prominence of the milliarcsecond-scale central features, but the prominence of the more bent jet segments does not. Candidates for counterjet emission are detected in seven sources, but there is no unambiguous, continuous counterjet in any of them. Estimates of the flux density ratios between the straighter jet segments and the counterjets based on these tentative detections range from 1.2:1 to >175:1. There is no evidence in this sample that counterjet detectability correlates with such putative inclination indicators as central feature prominence or projected linear size. There is also no evidence that the prominence of the counterjets anticorrelates with that of the jets as predicted by simple relativistic-beaming models for the jet/counterjet asymmetry. There is, however, strong evidence that large bends in the main jet favor counterjet detection, and there are no counterjet candidates opposite long, uninterrupted straight segments of the main jets.The detectability of the counterjets in these quasars may therefore be strongly influenced by interactions between the underlying beams and inhomogeneities in the surrounding material. We offer a new empirical definition of the term ''hot spot'' that is intended to improve the distinction between such features and ''jet knots.'' Both the compactness of hot spots and their position in the lobe are affected by whether they are fed by a detectable jet. When the hot spots differ significantly in compactness, the more compact one is always on the jetted side. Jetted hot spots are also more likely to be recessed deeply from the outer edge of their lobes than are their counterjetted counterparts. The jetted hot spot is less prominent relative to other extended emission if the jet bends through a large angle, particularly if a large bend occurs abruptly. The counterjetted hot spot is also less well defined if the jet is more bent. The lobes of several sources show considerable inhomogeneity, including filamentation.There is little difference in the inhomogeneity of the jetted and counterjetted lobes if the hot spots are excluded. The lobes have a common linear polarization pattern, with low polarization at the center and high polarization (often reaching 40% to 60%) near the edges. This pattern matches the expectations of models in which the magnetic field in the lobes is provided by passively expanding the field in the jets. The lobes in sources with promising counterjet candidates are often S-symmetric relative to the jet axis and their hot spots are more misaligned than in sources without such candidates. Counterjets may therefore be easier to detect if the jets change orientation during the lifetime of the source. We outline the implications of our results for various models of the prominence and asymmetries of central features, jets, counterjets, and hot spots. The correlations between the prominence and sidedness of the large-scale straight jet segments and of the small-scale central features favor models in which the kiloparsec-scale jets initially have bulk relativistic velocities. The slope of the prominence correlation is less than expected if the larger-scale jets have characteristic Lorentz factors as high as those in the milliarcsecond-scale features, however. This result is fragile within our small sample, but other aspects of our data also suggest that another phenomenon, closely coupled to jet bending, helps to determine the prominence of features far from the central region. Overall, our data favor ''tired jet'' models in which the average jet velocity decreases with increasing distance from the central object. This makes it harder for the simplest relativistic-jet models to account for the systematic differences in compactness and placement of jetted and counterjetted hot spots. The models may need refinement to include a range of Lorentz factors in the jets at any given distance from the quasar. C1 TRINITY UNIV,SAN ANTONIO,TX 78284. CALTECH,JET PROP LAB,PASADENA,CA 91125. MIT,HAYSTACK OBSERV,WESTFORD,MA 01886. NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. ROYAL GREENWICH OBSERV,CAMBRIDGE CB3 0EZ,CAMBS,ENGLAND. RP BRIDLE, AH (reprint author), NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903, USA. NR 103 TC 187 Z9 187 U1 0 U2 2 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 1994 VL 108 IS 3 BP 766 EP 820 DI 10.1086/117112 PG 55 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD586 UT WOS:A1994PD58600003 ER PT J AU BOTHUN, GD ERIKSEN, J SCHOMBERT, JM AF BOTHUN, GD ERIKSEN, J SCHOMBERT, JM TI ROSAT OBSERVATIONS OF QUIESCENT LOW-MASS DISK GALAXIES - NO EVIDENCE OF BARYONIC BLOW-OUT SO ASTRONOMICAL JOURNAL LA English DT Article ID NEUTRAL HYDROGEN OBSERVATIONS; SURFACE BRIGHTNESS GALAXIES; DWARF IRREGULAR GALAXIES; EMISSION-LINE GALAXIES; LYMAN-ALPHA-CLOUDS; ELLIPTICAL GALAXIES; IRAS OBSERVATIONS; VIRGO CLUSTER; DARK MATTER; EVOLUTION AB To test the hypothesis that galactic winds associated with star formation in low mass disk galaxies can be an effective means of relocating cold disk gas to a warm tenuous halo, we have obtained long exposure ROSAT PSPC observations of three such galaxies. The sensitivity of the PSPC to the presence of an extended, approximately 0.15 KEV halo of 10(9) M. of gas, is quite high for the exposure times we used. We failed to detect this halo in all three cases and the observed x-ray luminosity of the galaxy is two orders of magnitude less than the hypothetical case in which the mass of gas that has been expelled by previous generations of star formation is equal to the stellar mass of the galaxy itself This limit is much less than the actual mass of cold gas in these galaxies. Thus, we were unable to verify directly the presence of significant galactic winds in these three galaxies either because they are not operative, because their halos are not sufficiently massive to aid in the retention of this gas, or because the amount of injected gas is just a small percentage of the cold disk gas. if the latter reason is emblematic of low mass galaxies then we would not expect the detection of halos. We also report here the serendipitous detection of Abell 1560, a distance class 7 cluster of unknown redshift. C1 SAN DIEGO STATE UNIV,DEPT ASTRON,SAN DIEGO,CA 92182. CALTECH,JET PROP LAB,IPAC,PASADENA,CA 91125. RP BOTHUN, GD (reprint author), UNIV OREGON,DEPT PHYS,EUGENE,OR 97403, USA. NR 56 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 SEP PY 1994 VL 108 IS 3 BP 913 EP 920 DI 10.1086/117121 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD586 UT WOS:A1994PD58600012 ER PT J AU HAUSCHILDT, PH STARRFIELD, S SHORE, SN GONZALEZRIESTRA, R SONNEBORN, G ALLARD, F AF HAUSCHILDT, PH STARRFIELD, S SHORE, SN GONZALEZRIESTRA, R SONNEBORN, G ALLARD, F TI THE EARLY SPECTRAL EVOLUTION OF NOVA CASSIOPEIAE 1993 SO ASTRONOMICAL JOURNAL LA English DT Article AB In this paper we describe the evolution of Nova Cas 1993 over the first two months of its outburst. We present an ultraviolet light curve that covers the period from announcement to just after dust began forming in the ejecta (1994 Feb. 15) and IUE spacecraft constraints forced us to halt our observations. We have used spherical, expanding, NLTE stellar atmospheres to compute synthetic spectra and have compared the results to combined ultraviolet (low-resolution 1200-3400 Angstrom A and high-resolution 2400-3300 Angstrom A) spectra. Our fits show that the effective temperature of the ejecta increased from similar to 8000 to about similar to 16 000 K between 1993 Dec. 12 and 1993 Dec. 26. The temperature then increased more slowly to similar to 24 000 on 1994 Jan. 28. A preliminary abundance analysis shows evidence for hydrogen depletion, as we also found for Nova V1974 Cygni; however we find a larger enhancement of carbon, nitrogen, and oxygen. We also show that the principal mechanism for mass ejection in this nova is a radiation pressure driven wind and that mechanical driving is not necessary. C1 INDIANA UNIV,DEPT PHYS & ASTRON,S BEND,IN 46634. ESA,IUE OBSERV,VILLAFRANCA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV BRITISH COLUMBIA,DEPT GEOPHYS & ASTRON,VANCOUVER V6T 1Z4,BC,CANADA. RP HAUSCHILDT, PH (reprint author), ARIZONA STATE UNIV,DEPT PHYS & ASTRON,BOX 871504,TEMPE,AZ 85287, USA. OI Allard, France/0000-0003-1929-9340 NR 31 TC 36 Z9 36 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 1994 VL 108 IS 3 BP 1008 EP 1015 DI 10.1086/117131 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD586 UT WOS:A1994PD58600022 ER PT J AU VANBUREN, D DGANI, R NORIEGACRESPO, A AF VANBUREN, D DGANI, R NORIEGACRESPO, A TI THE WIND OF EG ANDROMEDAE IS NOT DUST DRIVEN SO ASTRONOMICAL JOURNAL LA English DT Article ID MASS-LOSS MECHANISMS; LATE-TYPE STARS; SYMBIOTIC STARS; EVOLVED STARS; STELLAR ATMOSPHERES; GRAINS; GIANTS; EXTINCTION; ENVELOPES; EVOLUTION AB The symbiotic star EG Andromedae has recently been the subject of several studies investigating its wind properties. Late-type giants are usually considered to have winds driven by radiation pressure on dust. Indeed, the derived wind velocity for EG Andromedae is consistent with this model. We point out here that there is no appreciable dust opacity in the wind of EG Andromedae using constraints on extinction limits from IUE and far infrared fluxes from IRAS. An alternate mechanism must operate in this star. We suggest that the wind can be driven by radiation pressure on molecular lines. RP VANBUREN, D (reprint author), CALTECH,CTR INFRARED PROC & ANAL,JET PROPULS LAB,PASADENA,CA 91125, USA. NR 35 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 1994 VL 108 IS 3 BP 1112 EP 1114 DI 10.1086/117138 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD586 UT WOS:A1994PD58600029 ER PT J AU AJELLO, JM PRYOR, WR BARTH, CA HORD, CW STEWART, AIF SIMMONS, KE HALL, DT AF AJELLO, JM PRYOR, WR BARTH, CA HORD, CW STEWART, AIF SIMMONS, KE HALL, DT TI OBSERVATIONS OF INTERPLANETARY LYMAN-ALPHA WITH THE GALILEO ULTRAVIOLET SPECTROMETER - MULTIPLE-SCATTERING EFFECTS AT SOLAR MAXIMUM SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE RADIATIVE TRANSFER; SUN, SOLAR WIND; SUN, UV RADIATION; INTERPLANETARY MEDIUM; SOLAR NEIGHBORHOOD; ULTRAVIOLET, SOLAR SYSTEM ID PIONEER-VENUS; INTERSTELLAR HYDROGEN; LATITUDE VARIATION; WIND SPEED; FLUX; MARINER-10; ANISOTROPY; EVOLUTION; MINIMUM; VOYAGER AB The Galileo Ultraviolet Spectrometer Experiment (UVS) obtained a partial celestial sphere map of interplanetary Lyman-alpha (IP Lalpha) on 13-14 December 1990 during the first Earth encounter. The Galileo spacecraft was near the downwind axis of the local interstellar medium flow. These UVS measurements sampled the downwind, anti-sunward hemisphere. The data were modelled using a hot model of the interplanetary hydrogen density distribution with the goal of studying multiple scattering effects in the inner solar system. The derived ratio in the downwind direction of the observed brightness and a single scattering model brightness, both normalized to unity in the upwind direction, is 1.82 +/- 0.2. This brightness ratio requires a multiple scattering correction which is 36% larger than can be accounted for by theoretical calculations. Other physical phenomena not included in the model density distribution must contribute to the downwind brightness enhancement. The hot model may require: (1) a temperature perturbation of the interstellar wind velocity distribution or (2) an additional downstream source of interplanetary hydrogen. However, a more likely explanation which affects the hot model is the latitude dependence of the radiation pressure. This dependence, based on the known solar Lalpha flux latitude variation at solar maximum, causes a downwind brightness enhancement by preferential focusing of H-atoms with trajectory planes containing the solar poles. This result implies that radiation pressure near the solar poles is nearly independent of solar cycle and is insufficient to lead to a net repulsion of hydrogen atoms by the sun, as can occur near the ecliptic plane during solar maximum. In addition, the UVS performed 13 observations of IP Lalpha while in cruise between Venus and the Earth in 3 directions fixed in ecliptic coordinates. The observations made while viewing in the ecliptic have more brightness variation in time than observations made viewing ecliptic north, which is a result of enhanced low-latitude solar activity during solar maximum in 1990. Models of the interstellar wind that fit both the anti-sun map and the UVS 3-position observations require a number density of atomic hydrogen near 50 AU of 0.17 +/- 0.05 cm-3. C1 UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, BOULDER, CO 80303 USA. JOHNS HOPKINS UNIV, DEPT PHYS & ASTRON, BALTIMORE, MD 21218 USA. RP AJELLO, JM (reprint author), JET PROP LAB, MS 183-601, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 47 TC 41 Z9 41 U1 0 U2 1 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD SEP PY 1994 VL 289 IS 1 BP 283 EP 303 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PE582 UT WOS:A1994PE58200042 ER PT J AU HUBENY, I HARMANEC, P SHORE, SN AF HUBENY, I HARMANEC, P SHORE, SN TI ON THE STRATEGY OF FUTURE OBSERVATIONS AND MODELING OF THE BETA-LYR SYSTEM SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ACCRETION, ACCRETION DISKS; STARS, BINARIES, CLOSE; STARS, INDIVIDUAL, BETA LYRAE; STARS, BE; STARS, ATMOSPHERES ID DIFFERENTIALLY ROTATING-DISKS; ACCRETION DISKS; BOUNDARY-LAYER; DYNAMICAL STABILITY; RADIATION HYDRODYNAMICS; ALGOL SYSTEMS; DWARF NOVAE; STARS AB beta Lyr is an enigmatic object. Despite several decades of concentrated observational and theoretical effort, our understanding of the system is still rather poor. We discuss two existing structural models of the system, the massive torus model of Wilson (1981), and the low mass accretion disk model of Hubeny and Plavec (1991). In particular, we answer recent criticism of the low mass disk model expressed by the proponents of the massive disk hypothesis. We show that although both theories have a large degree of internal consistency, there are several serious physical objections against the massive disk model. In particular, such a model requires unrealistically low viscosity (large Reynolds number). Moreover, such massive disk is likely to be dynamically unstable. Finally, we propose several observational and theoretical approaches that could lead to construction of a more physically realistic model of the beta Lyr system. C1 UNIV SPACE RES ASSOC, WASHINGTON, DC USA. ACAD SCI CZECH REPUBL, INST ASTRON, CR-25165 ONDREJOV, CZECH REPUBLIC. INDIANA UNIV, DEPT PHYS & ASTRON, S BEND, IN 46634 USA. RP HUBENY, I (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 681, GREENBELT, MD 20771 USA. NR 58 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 1994 VL 289 IS 2 BP 411 EP 418 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF506 UT WOS:A1994PF50600007 ER PT J AU SEKANINA, Z CHODAS, PW YEOMANS, DK AF SEKANINA, Z CHODAS, PW YEOMANS, DK TI TIDAL DISRUPTION AND THE APPEARANCE OF PERIODIC COMET SHOEMAKER-LEVY-9 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMET P/SHOEMAKER-LEVY 9; TIDAL DISRUPTION; DEBRIS EVOLUTION; SECONDARY FRAGMENTATION; ENCOUNTER AND IMPACT CIRCUMSTANCES ID NUCLEUS; MECHANISM; P/HALLEY AB A unified model is formulated to interpret quantitatively the observed characteristics of the nuclear train, the two dust trails, and the tail region of P/Shoemaker-Levy 9 in terms of a collisionally modified rotation velocity distribution of the comet's debris. Since there is no evidence for the comet's outgassing, the model does not assume activity. The disruption of the parent comet was due primarily to tidal stresses during its extremely close approach to Jupiter in July 1992. The original nucleus is found to have been most probably similar to 5 km in radius or, equivalently, similar to 10(17) g in mass. The dynamical separation of the debris occurred apparently similar to 2.2 hr after the perijove passage, even though the actual fragmentation of the original mass is likely to have begun before closest approach. Physical breakup was accompanied by ubiquitous low-velocity collisions among the particulates, resulting in a rearrangement of the initial rotational velocities into a rapidly ''thermalized'' distribution, characterized by a long tail of relatively high velocities for the debris that populates the dust trails far from the nuclear train. The period of intense particle-particle collisions is estimated to have continued for at least similar to 0.1 day, at which time the radial differential perturbations by Jupiter and orbital-velocity differences began to dominate the relative motions of the debris. The particle mass distribution appears to be fairly flat, proportional to m(-1) dm, for submeter-sized and larger fragments, but steeper than m(-2) dm for the microscopic debris. The fine dust contributes much of the total observed cross-sectional area, but its share of the total mass of the assemblage is negligible. The effective radii of the 21 largest fragments range from <1 km to >2 km, based on Weaver et al.'s (1994) results and on constraints implied by our model. The debris populating the west-southwestern trail appears to be predominantly; pebble-sized, while the debris in the east-northeastern trail is mostly subcentimeter-sized. The diffuse sector to the north of the trails (including the tails of the individual fragments) consists primarily of microscopic dust, subjected to appreciable effects of solar radiation pressure. Compelling evidence is presented for secondary fragmentation events, indicative of the comet's continuing disintegration. Secondary fragmentation may be caused by rotational bursting of the massive fragments that had been cracked but unbroken during the tidal disruption. Impact conditions and possible interactions of the comet's debris with the jovian system during the encounter in July 1994 are described. RP SEKANINA, Z (reprint author), CALTECH, JET PROP LAB, MAIL STOP 169-237, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 51 TC 47 Z9 47 U1 0 U2 4 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 1994 VL 289 IS 2 BP 607 EP 636 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF506 UT WOS:A1994PF50600022 ER PT J AU UNWIN, SC WEHRLE, AE URRY, CM GILMORE, DM BARTON, EJ KJERULF, BC ZENSUS, JA RABACA, CR AF UNWIN, SC WEHRLE, AE URRY, CM GILMORE, DM BARTON, EJ KJERULF, BC ZENSUS, JA RABACA, CR TI INVERSE COMPTON X-RAY-EMISSION FROM THE SUPERLUMINAL QUASAR 3C 345 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, JETS; QUASARS, INDIVIDUAL, (3C 345); RADIATION MECHANISMS, NONTHERMAL; RADIO CONTINUUM, GALAXIES; X-RAYS, GALAXIES ID BL LACERTAE OBJECTS; EXTRAGALACTIC RADIO-SOURCES; ACTIVE GALACTIC NUCLEI; SPECTRAL VARIABILITY; RELATIVISTIC JETS; SPHERICAL GEOMETRIES; VLBI OBSERVATIONS; VLA OBSERVATIONS; COMPLETE SAMPLE; MOTION AB In quasars with strong radio cores, the inverse-Compton process is believed to be the dominant source X-ray emission. For objects with parsec-scale radio jets, simple models have predicted that components in the jet emerging from the quasar nucleus generate the observed X-ray emission. We have tested this hypothesis in detail for the quasar 3C 345 using a ROSAT X-ray observation in 1990 July, together with quasi-simultaneous VLBI imaging of the parsec-scale jet at five frequencies. The ROSAT spectrum is well fitted by a power law with index alpha = -0.96 +/- 0.13, consistent with models in which the X-ray emission results from inverse-Compton scattering of radio radiation from high-energy electrons in compact components. We show that the radio properties of brightest '' knot '' in the jet ('' C5 '') can be fitted with a homogeneous sphere model whose parameters require bulk relativistic motion of the emitting material; otherwise the predicted inverse-Compton X-ray emission exceeds the observed flux. If C5 is the origin of the X-ray emission, then it has a Doppler factor delta = 7.5(-2)+3. If the nucleus or other components contribute to the X-ray emission, then this becomes a firm lower limit to delta. The inhomogeneous jet model of Konigl is a good fit both to the barely resolved (< 1 pc) flat-spectrum nucleus in the radio, and also to the ROSAT X-ray spectrum. The synchrotron and inverse-Compton emitting fluid moves down a narrow cone (opening angle 2phi almost-equal-to 5-degrees) nucleus relativistically, with delta almost-equal-to 4.6. Doppler factors for the nucleus and C5, derived from our ROSAT observation, provide evidence for bulk relativistic motion in the jet. By combining these constraints with the well-known superluminal motion of jet components, we can deduce the jet geometry. For epoch 1990.5 we infer the Lorentz factor gamma = 7.5(-1.5)=1.0 and angle to the line of sight theta = 8(-3-degrees)+2-degrees for H-0 = 100 km s-1 Mpc-1. These values are the most reliable yet derived using this method, because of the near-simultaneity of our X-ray and VLBI observations and the quality of the multifrequency VLBI images and component radio spectra. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. RP UNWIN, SC (reprint author), CALTECH,OWENS VALLEY RADIO OBSERV,PASADENA,CA 91125, USA. RI Urry, Claudia/G-7381-2011 OI Urry, Claudia/0000-0002-0745-9792 NR 55 TC 38 Z9 38 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1994 VL 432 IS 1 BP 103 EP 113 DI 10.1086/174552 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD611 UT WOS:A1994PD61100011 ER PT J AU NEUFELD, DA GREEN, S AF NEUFELD, DA GREEN, S TI EXCITATION OF INTERSTELLAR HYDROGEN-CHLORIDE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; MOLECULAR DATA; MOLECULAR PROCESSES; RADIO LINES, ISM ID COLLISIONAL EXCITATION; ROTATIONAL EXCITATION; MOLECULAR-SCATTERING; DENSE CLOUDS; HCL; HE; POTENTIALS; OMC-1; CORES AB We have computed new rate coefficients for the collisional excitation of HCI by He, in the close-coupled formalism and using an interaction potential determined recently by Willey, Choong, & DeLucia. Results have been obtained for temperatures between 10 K and 300 K. With the use of the infinite order sudden approximation, we have derived approximate expressions of general applicability which may be used to estimate how the rate constant for a transition (J --> J') is apportioned among the various hyperfine states F' of the final state J'. Using these new rate coefficients, we have obtained predictions for the HCI rotational line strengths expected from a dense clump of interstellar gas, as a function of the HCI fractional abundance. Over a wide range of HCl abundances, we have found that the line luminosities are proportional to (abundance)2/3, a general result which can be explained using a simple analytical approximation. Our model for the excitation of HCI within a dense molecular cloud core indicates that the J = 1-0 line strengths measured by Blake, Keene, & Phillips toward the Orion Molecular Cloud (OMC-1) imply a fractional abundance n(HCl)/n(H-2) approximately 2 x 10(-9), a value which amounts to only approximately 0.3% of the cosmic abundance of chlorine nuclei. Given a fractional abundance of 2 x 10(-9), the contribution of HCl emission to the total radiative cooling of a dense clump is small. For Orion, we predict a flux approximately 10(-19) W cm-2 for the HCl J = 3-2 line near 159.8 mum suggesting that the strength of this line could be measured using the Infrared Space Observatory. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP NEUFELD, DA (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,3400 N CHARLES ST,BALTIMORE,MD 21218, USA. NR 33 TC 49 Z9 49 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 1994 VL 432 IS 1 BP 158 EP 166 DI 10.1086/174557 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD611 UT WOS:A1994PD61100016 ER PT J AU SMITH, MA HUBENY, I LANZ, T MEYLAN, T AF SMITH, MA HUBENY, I LANZ, T MEYLAN, T TI DYNAMIC PROCESSES IN BE STAR ATMOSPHERES .2. HE I 2P-ND LINE FORMATION IN LAMBDA ERIDANI (OUTBURST) SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE, FORMATION; LINE, PROFILES; RADIATIVE TRANSFER; STARS, EMISSION-LIKE, BE; STARS, INDIVIDUAL (LAMBDA-ERIDANI) ID MODEL STELLAR ATMOSPHERES; B-STARS; SPECTRA; HELIUM; EQUILIBRIUM; HYDROGEN; B2E AB The He I lambda6678 line of early Be stars generally shows violet (V) and red (R) emission whenever Halpha emission is present, but its use as a diagnostic has been handicapped by a poor understanding of the processes that drive it into emission. In an attempt to address this problem we obtained three series of echelle spectra of the first two members of the singlet and triplet 2P-nD series of lambda Eri (B2e) during 1992 November 3-5 at Kitt Peak. During these observations lambda6678 showed substantial emission variability in both the wings and central profile, providing an opportunity to compare its behavior with that of the lambda4922, lambda5876, and lambda4471 lines. We found that the responses of the lines were different in several respects. Whereas the emissions in the V wings of all four lines scaled together, the R wing of the lambda4922 line invariably responded with increased absorption whenever the R wing of lambda6678 line showed increased emission. These same trends occurred within the central photospheric profiles. The R-wing behavior shows that much, but not all, of the emission in lambda6678 is caused by matter projected against the stellar disk.. The excitation temperatures of the neighboring 2(1)P transitions, lambda6678 and lambda4922, must be greater than and less than the photospheric continuum temperature, respectively. We have investigated departures from LTE for the He I spectrum in a variety of ad hoc, perturbed model atmospheres. We have found only one way to cause the source function of lambda6678 to increase so strongly, namely, by increasing the atmospheric temperature in the line formation region to 30,000-40,000 K. When the kinetic temperature is this hot, the resonance lambda584 transition becomes transparent, causing the 2(1)P level to become underpopulated relative to other levels. Stimulated emission amplifies this condition, driving lambda6678 selectively into emission. This effect was discovered by Auer and Mihalas for O3-O4 atmosphere models, but it has not been applied to active B stars. Our models suggest that lambda6678 emission in Be stars can be used as a sensitive monitor of localized hot spots on these stars' surfaces. In particular they show that lambda6678 emission originates in the plasma having a high (photosphere-like) density. Combining this finding with our observation that foreground material exhibits and predominant redshift implies at physical mechanism that incorporates both heat and violent downward motions penetrating well into the photosphere. The energies involved in heating the active portions of the atmosphere are too high to be produced by gravitational infall. This leaves magnetically induced flares among the few known processes on the surfaces of stars capable of sustaining this energy level. C1 UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS,CODE 681,GREENBELT,MD 20771. RP SMITH, MA (reprint author), COMP SCI CORP,OBSERV SCI PROGRAMS,IUE,10000 A AEROSP RD,LANHAM,MD 20706, USA. NR 31 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1994 VL 432 IS 1 BP 392 EP 402 DI 10.1086/174577 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD611 UT WOS:A1994PD61100036 ER PT J AU GANGA, K PAGE, L CHENG, E MEYER, S AF GANGA, K PAGE, L CHENG, E MEYER, S TI THE AMPLITUDE AND SPECTRAL INDEX OF THE LARGE ANGULAR SCALE ANISOTROPY IN THE COSMIC MICROWAVE BACKGROUND-RADIATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND ID RADIOMETER; MILLIMETER AB In many cosmological models, the large angular scale anisotropy in the cosmic microwave background is parameterized by a spectral index, n, and a quadrupolar amplitude, rho. For a Harrison-Peebles-Zel'dovich spectrum, n = 1. Using data from the Far Infrared Survey (FIRS) and a new statistical measure, a contour plot of the likelihood for cosmological models for which -1 < n < 3 and 0 less-than-or-equal-to rho less-than-or-equal-to 50 muK is obtained. Depending upon the details of the analysis, the maximum likelihood occurs at n between 0.8 and 1.4 and rho between 18 and 21 muK. Regardless of rho, the likelihood is always less than half its maximum for n < -0.4 and for n > 2.2, as it is for rho < 8 muK and rho > 44 muK. C1 NASA,GODDARD SPACE FLIGHT CTR,CODE 6850,GREENBELT,MD 20771. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. RP GANGA, K (reprint author), PRINCETON UNIV,JOSEPH HENRY LABS,DEPT PHYS,JADWIN HALL,PRINCETON,NJ 08544, USA. NR 28 TC 40 Z9 40 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 1994 VL 432 IS 1 BP L15 EP L18 DI 10.1086/187500 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD612 UT WOS:A1994PD61200004 ER PT J AU LISSE, CM FREUDENREICH, HT HAUSER, MG KELSALL, T MOSELEY, SH REACH, WT SILVERBERG, RF AF LISSE, CM FREUDENREICH, HT HAUSER, MG KELSALL, T MOSELEY, SH REACH, WT SILVERBERG, RF TI INFRARED OBSERVATIONS OF COMET AUSTIN (1990-V) BY THE COBE DIFFUSE INFRARED BACKGROUND EXPERIMENT SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS, INDIVIDUAL (AUSTIN 1990-V); INFRARED, SOLAR SYSTEM ID DUST; PARTICLES; P/HALLEY; ALBEDO AB Comet Austin was observed by the COBE/Diffuse Infrared Background Experiment with broadband photometry at 1-240 mum during the comet's close passage by Earth in 1990 May. A 6-degrees long (6 x 10(6) km) dust tail was found at 12 and 25 mum, with detailed structure due to variations in particle properties and mass-loss rate. The spectrum of the central 42 x 42 arcmin2 pixel was found to agree with that of a graybody of temperature 309 +/- 5 K and optical depth 7.3 +/- 1.4 x 10(-8). Comparison with IUE and ground-based observations indicates that particles of radius greater than 20 mum predominate by surface area. A mass-loss rate of 510 (+ 510/- 205) kg s-1 and a total tail mass of 7 +/- 2 x 10(10) kg was found for a model dust tail composed of Mie spheres with a differential particle mass distribution dn/d log m approximately m-0.63 and 2:1 silicate:amorphous carbon composition by mass. C1 NASA,GODDARD SPACE FLIGHT CTR,CODE 680,GREENBELT,MD 20771. RP LISSE, CM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Reach, William/0000-0001-8362-4094 NR 26 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 1994 VL 432 IS 1 BP L71 EP L74 DI 10.1086/187514 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD612 UT WOS:A1994PD61200018 ER PT J AU OLSON, KM DORBAND, JE AF OLSON, KM DORBAND, JE TI AN IMPLEMENTATION OF A TREE CODE ON A SIMD, PARALLEL COMPUTER SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE METHODS, NUMERICAL ID ALGORITHM AB We describe a fast tree algorithm for gravitational N-body simulation on SIMD parallel computers. The tree construction uses fast, parallel sorts. The sorted lists are recursively divided along their x, y, and z coordinates. This data structure is a completely balanced tree (i.e., each particle is paired with exactly one other particle) and maintains good spatial locality. An implementation of this tree-building algorithm on a 16k processor Maspar MP-1 performs well and constitutes only a small fraction (approximately 15%) of the entire cycle of finding the accelerations. Each node in the tree is treated as a monopole. The tree search and the summation of accelerations also perform well. During the tree search, node data that is needed from another processor is simply fetched. Roughly 55% of the tree search time is spent in communications between processors. We apply the code to two problems of astrophysical interest. The first is a simulation of the close passage of two gravitationally, interacting, disk galaxies using 65,636 particles. We also simulate the formation of structure in an expanding, model universe using 1,048,576 particles. Our code attains speeds comparable to one head of a Cray Y-MP, so SIMD type computers can be used for these simulations. The cost/performance ratio for SIMD machines like the Maspar MP-1 make them an extremely attractive alternative to either vector processors or large MIMD type parallel computers. With further optimizations (e.g., more careful load balancing), speeds in excess of today's vector processing computers should be possible. C1 UNIV SPACE RES ASSOC,GREENBELT,MD. RP OLSON, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CTR COMPUTAT SCI,CODE 934,GREENBELT,MD 20771, USA. NR 16 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1994 VL 94 IS 1 BP 117 EP 125 DI 10.1086/192074 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC549 UT WOS:A1994PC54900005 ER PT J AU MEIER, SR KAFATOS, M FAHEY, RP MICHALITSIANOS, AG AF MEIER, SR KAFATOS, M FAHEY, RP MICHALITSIANOS, AG TI A FAR-ULTRAVIOLET ATLAS OF SYMBIOTIC STARS OBSERVED WITH IUE .1. THE SWP RANGE SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE BINARIES, SPECTROSCOPIC; LINE, IDENTIFICATION; ULTRAVIOLET, STARS ID AG-DRACONIS; VARIABILITY; SPECTRUM; PERIOD AB This atlas contains sample spectra from the far-ultraviolet observations of 32 symbiotic stars obtained with the International Ultraviolet Explorer (IUE) satellite. In all, 394 low-resolution spectra from the short-wavelength primary (SWP) camera covering the range 1200-2000 angstrom have been extracted from the IUE archive, calibrated, and measured. Absolute line fluxes and wavelengths for the prominent emission lines have been tabulated. Tables of both the general properties of these symbiotics and of features specific to the spectrum of each are included. The spectra shown are representative of the different classes of symbiotic stars that are currently in the IUE archive. These include known eclipsing systems and those that have been observed in outburst (as well as quiescence). C1 GEORGE MASON UNIV,INST CSI,FAIRFAX,VA 22030. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. GEORGE MASON UNIV,DEPT PHYS,FAIRFAX,VA 22030. NR 43 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD SEP PY 1994 VL 94 IS 1 BP 183 EP 220 DI 10.1086/192078 PG 38 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC549 UT WOS:A1994PC54900009 ER PT J AU BAYARD, DS AF BAYARD, DS TI HIGH-ORDER MULTIVARIABLE TRANSFER-FUNCTION CURVE-FITTING - ALGORITHMS, SPARSE-MATRIX METHODS AND EXPERIMENTAL RESULTS SO AUTOMATICA LA English DT Note DE FREQUENCY RESPONSE; CURVE FITTING; SYSTEM IDENTIFICATION; TRANSFER FUNCTION MATRIX; PARAMETER ESTIMATION; SPARSE MATRICES; MATHEMATICAL PROGRAMMING ID IDENTIFICATION AB This paper develops a computational approach to multivariable frequency domain curve fitting, based on two-norm minimization. The algorithm is specifically tailored to the identification of complex systems having a large number of parameters, and includes a sparse matrix method for reducing computation and memory requirements on large problems. The algorithm is also well-suited for identification of lightly damped systems such as flexible structures. The overall approach is successfully demonstrated on a high-order multivariable flexible structure experiment requiring the estimation of 780 parameters over a 100 Hz band width. RP BAYARD, DS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 41 Z9 41 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0005-1098 J9 AUTOMATICA JI Automatica PD SEP PY 1994 VL 30 IS 9 BP 1439 EP 1444 DI 10.1016/0005-1098(94)90009-4 PG 6 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA PJ366 UT WOS:A1994PJ36600009 ER PT J AU NEWMAN, DJ ALEXANDER, HL WEBBON, BW AF NEWMAN, DJ ALEXANDER, HL WEBBON, BW TI ENERGETICS AND MECHANICS FOR PARTIAL GRAVITY LOCOMOTION SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB The role of gravitational acceleration on human locomotion is not clearly understood. It is hypothesized that the mechanics and energetics of locomotion depend upon the prevailing gravity level. A unique human-rated underwater treadmill and an adjustable ballasting harness were used to simulate partial gravity environments. This study has two research aspects, biome chanics and energetics. Vertical forces which are exerted by subjects on the treadmill-mounted, split-plate force platform show that peak vertical force and stride frequency significantly decrease (p < 0.05) as the gravity level is reduced, while ground contact time is independent of gravity level. A loping gait is employed over a wide range of speeds (similar to 1.5 m/s to similar to 2.3 m/s) suggesting a change in the mechanics for lunar (1/6 G) and Martian (3/8 G) locomotion. As theory predicts, locomotion energy requirements for partial gravity levels are significantly less than at 1 G (p < 0.05). C1 ORBITAL SCI CORP,DULLES,VA. NASA,AMES RES CTR,DIV ADV LIFE SUPPORT,MOFFETT FIELD,CA 94035. RP NEWMAN, DJ (reprint author), MIT,DEPT AERONAUT & ASTRONAUT,MAN VEHICLE LAB,ROOM 33-119,CAMBRIDGE,MA 02139, USA. NR 21 TC 32 Z9 32 U1 1 U2 5 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 1994 VL 65 IS 9 BP 815 EP 823 PG 9 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PF322 UT WOS:A1994PF32200003 PM 7818450 ER PT J AU JAMES, JT LIMERO, TF LEANO, HJ BOYD, JF COVINGTON, PA AF JAMES, JT LIMERO, TF LEANO, HJ BOYD, JF COVINGTON, PA TI VOLATILE ORGANIC CONTAMINANTS FOUND IN THE HABITABLE ENVIRONMENT OF THE SPACE-SHUTTLE - STS-26 TO STS-55 SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note ID TOXICITY; POLYMERS AB The health and performance of spacecraft crews can be adversely affected by contaminants present in the respirable air. Contaminants originate from hardware offgassing, crew and microbial metabolism, use of utility chemicals, leakage from fluid systems and payload experiments, and from electrical overheating. The quality of Shuttle air is measured by collecting contaminants in evacuated cylinders or on sorbent resin for later ground-based analysis by gas chromatography (GC) and GC mass spectrometry (MS). The results of those analyses are presented for 28 missions, including 5 Spacelabs which were flown in the payload bay of the Shuttle. The major contaminants were relatively nontoxic alcohols (ethanol, isopropanol), ketones (ae etone, diacetone alcohol), alkanes, halocarbons (Halon 1301, Freon 113), and siloxanes. Occasionally, more toxic contaminants, such as methanol, acetaldehyde, and tetrachloroethene, were present at low concentrations (below 1 mg/m(3)). The contaminant concentrations measured in spacecraft air were compared to spacecraft maximum allowable concentrations (SMAC's) which are set to protect the crew from adverse health effects or performance decrements. Aggregate toxicity assessments (T values) of the contaminants present during each mission, calculated by summing the ratios of measured concentrations to each contaminant's SMAC, showed that air quality consistently met the criterion that the T value be less than 1. C1 KRUG LIFE SCI INC,HOUSTON,TX. RP JAMES, JT (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,MAIL DROP SD4,HOUSTON,TX 77058, USA. NR 20 TC 17 Z9 17 U1 1 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD SEP PY 1994 VL 65 IS 9 BP 851 EP 857 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PF322 UT WOS:A1994PF32200009 PM 7818456 ER PT J AU YING, R CANUTO, VM YPMA, RM AF YING, R CANUTO, VM YPMA, RM TI NUMERICAL-SIMULATION OF FLOW DATA OVER 2-DIMENSIONAL HILLS SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID BOUNDARY-LAYER FLOW; HEAT-FLUX; MODEL; TURBULENCE; PROJECT AB We have studied a neutrally-stratified how over two-dimensional hills using a two dimensional, non-hydrostatic version of the Regional Atmospheric Modeling System (RAMS). We have implemented three different turbulence closure models: the standard E-epsilon model, an Algebraic Reynolds Stress Model (ARSM) and a new E - epsilon - <(uw)over bar> model. Model predictions for the mean and turbulence flows using different closure schemes are compared with the data of a wind tunnel experiment containing isolated two-dimensional hills of varying slope. From the comparison, it is concluded that all three models predict the mean flow velocities equally well while only the new E - epsilon - <(uw)over bar> closure model accurately predicts the turbulence data statistics. RP YING, R (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 27 TC 18 Z9 18 U1 1 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD SEP PY 1994 VL 70 IS 4 BP 401 EP 427 DI 10.1007/BF00713778 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PK293 UT WOS:A1994PK29300005 ER PT J AU DEMARTINI, EE BARNETT, AM JOHNSON, TD AMBROSE, RF AF DEMARTINI, EE BARNETT, AM JOHNSON, TD AMBROSE, RF TI GROWTH AND PRODUCTION ESTIMATES FOR BIOMASS-DOMINANT FISHES ON A SOUTHERN CALIFORNIA ARTIFICIAL REEF SO BULLETIN OF MARINE SCIENCE LA English DT Article ID KELP FOREST AB Somatic growth and somatic and gonadal production were estimated during May-November 1989 for six species, comprising most of the standing crop biomass of the fishes on a shallow (10- to 15-m deep), 14-year-old, quarry rock reef (Torrey Pines Artificial Reef #2, TPAR), off La Jolla, California. Growth was estimated from weight-converted length increments of 142 Floy-tagged individuals at liberty for a median of 187 days. Egg production was estimated for females of three taxa (four species) as the product of the weight of batch egg production and spawning frequency (the latter determined from histological evidence of day-old postovulatory follicles). Milt production was deduced from male to female ratios of gonad weights for reproductive fish. Somatic growth rates varied three- to fourfold among the six species and, in part, reflected the distribution of maturity stages of intraspecific populations. On average, the per capita growth rates of taxa dominated by immature stages were faster than those dominated by large adults. Somatic production varied more than somatic growth rates (by a factor of 15), because of additional variations in standing stock biomass among populations. The somatic production of at least one species was underestimated as a result of a tag effect on growth. Weight-specific egg production varied only twofold among the three taxa examined, perhaps because fishes with smaller batch egg productions compensated by spawning more frequently, and vice versa. Estimates of weight-specific milt production further diverged because of the influence of relative testis-to-ovary weights that ranged from a small fraction to unity. Additional variation among taxa in total gonadal (egg plus milt) production was about one-half that of somatic production (a factor of eight). Besides representing interspecific differences in adult biomass, variations in gonadal production reflected intraspecific differences in the biomass contributions of the two sexes within the fraction of adults that were reproductively active. Despite likely substantial underestimates of gametic materials, gonadal production ranged from a large fraction to a large multiple of somatic production among the four species. Our observations suggest that the elaboration of tissue unrelated to yield is nontrivial and represents a major component of energy flow through the fishes in this reef system and perhaps others. C1 MEC ANALYT SYST INC,CARLSBAD,CA 92009. PORT LONG BEACH PLANNING DEPT,LONG BEACH,CA 90802. UNIV CALIF LOS ANGELES,ENVIRONM SCI & ENGN PROGRAM,LOS ANGELES,CA 90024. RP DEMARTINI, EE (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. OI Ambrose, Richard/0000-0001-8653-6487 NR 36 TC 28 Z9 31 U1 1 U2 8 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1994 VL 55 IS 2-3 BP 484 EP 500 PG 17 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA QB584 UT WOS:A1994QB58400020 ER PT J AU JOHNSON, TD BARNETT, AM DEMARTINI, EE CRAFT, LL AMBROSE, RF PURCELL, LJ AF JOHNSON, TD BARNETT, AM DEMARTINI, EE CRAFT, LL AMBROSE, RF PURCELL, LJ TI FISH PRODUCTION AND HABITAT UTILIZATION ON A SOUTHERN CALIFORNIA ARTIFICIAL REEF SO BULLETIN OF MARINE SCIENCE LA English DT Article AB The feeding habits of fish, their production, and their fidelity to the reef habitat were estimated on and near Torrey Pines Artificial Reef (TPAR) during April-October 1989. Taxonomic and biomass analysis of gut contents and benthic resources suggested that at least 70% of the diet of reef fish was derived from the reef itself and another 20-25% from the ecotone. For most reef fishes, suitable prey was 100 times more abundant in the reef habitat than in adjacent sand habitats. Estimates of somatic production by tagged fish were based on standing stocks, size distribution, and growth rates, and by untagged species, on changes in mean length of a cohort or population biomass over time. Estimated total production of the fish on TPAR was 116 kg, or 649 kg.ha(-1), more than a third of it as gonadal production by the six target species. Production by the sand-bottom fish assemblage, estimated from literature-derived somatic and gonadal production rates and the biomass of trawled fish, was 73 kg hectare year(-1). Calculated reef production was, therefore, about nine times greater than the production of sand-bottom fish. From 30 to 70% of the four species of tagged fish (sheephead, rock wrasse, black perch, and garibaldi) that could be captured by divers were recaptured after 7 months, indicating a high degree of fidelity to the reef. Recapture of 12% of tagged kelp bass via hook-and-line after 7 months and the recapture of five tagged kelp bass of a total of 40 kelp bass caught 1 year later by a sport fishing boat indicate that kelp bass, too, remained associated with the reef for long periods. C1 MEC ANALYT SYST INC,CARLSBAD,CA 92008. NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES CTR,HONOLULU,HI 96820. UNIV CALIF SANTA BARBARA,INST MARINE SCI,SANTA BARBARA,CA 93106. SAN DIEGO CTY WATER AUTHOR,SAN DIEGO,CA 92103. RP JOHNSON, TD (reprint author), PORT LONG BEACH,LONG BEACH,CA 90802, USA. RI Langhamer, Olivia/J-3425-2012; OI Ambrose, Richard/0000-0001-8653-6487 NR 20 TC 38 Z9 39 U1 0 U2 12 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1994 VL 55 IS 2-3 BP 709 EP 723 PG 15 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA QB584 UT WOS:A1994QB58400038 ER PT J AU FOSTER, KL STEIMLE, FW MUIR, WC KROPP, RK CONLIN, BE AF FOSTER, KL STEIMLE, FW MUIR, WC KROPP, RK CONLIN, BE TI MITIGATION POTENTIAL OF HABITAT REPLACEMENT - CONCRETE ARTIFICIAL REEF IN DELAWARE BAY - PRELIMINARY-RESULTS SO BULLETIN OF MARINE SCIENCE LA English DT Article ID NEW-YORK-BIGHT; FOULING COMMUNITY; CAROLINA; ESTUARY AB Artificial reefs are being proposed as mitigation for habitat loss in estuaries and coastal areas. However there is insufficient information to verify that artificial reefs enhance biological resources. To study their value for mitigating habitat loss, 16 prefabricated concrete terraced artificial reef modules were deployed in lower Delaware Bay in 1989. A 5-year monitoring study was begun to assess the artificial reef's value as a long-term habitat and forage area for fishery resources as compared to non-reef habitats in the Bay. After 2 years, the reef modules appear to be physically stable and support biological resources. Fishes, including juveniles, typical of reefs in the region, were observed in and near the reef The blue mussel, Mytilus edulis, dominated the epibenthic community that developed on the modules and was primarily responsible for a mean epibenthic biomass density of 24.865 kg.nm-2 (wet wt.) on module surfaces through June 1991. However, this mussel-dominated density was reduced, by approximately 95%, in August 1991 to a mean 0.596 kg.m(-2), with other taxa such as, sponges, corals, and anemones increasing in community importance. In comparison to the epibenthic biomass on the modules, the mean benthic infauna biomass in the silty sand sediments of the reef site ranged from 0.046 to 0.316 kg.m(-2) in 1991. These preliminary results suggest that this artificial reef complex enhanced gross benthic biomass at the reef site by about 147 to 895 fold over the benthic infauna in the study area, based on a standard area of Bay bottom, the reef module ''footprint.'' C1 NOAA,NATL MARINE FISHERIES SERV,HIGHLANDS,NJ 07732. US EPA,PHILADELPHIA,PA 19106. US CORPS ENGINEERS,PHILADELPHIA,PA 19106. RP FOSTER, KL (reprint author), BATTELLE OCEAN SCI,397 WASHINGTON ST,DUXBURY,MA 02332, USA. NR 34 TC 12 Z9 12 U1 2 U2 5 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD SEP PY 1994 VL 55 IS 2-3 BP 783 EP 795 PG 13 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA QB584 UT WOS:A1994QB58400042 ER PT J AU PLATT, CM YOUNG, SA CARSWELL, AI PAL, SR MCCORMICK, MP WINKER, DM DELGUASTA, M STEFANUTTI, L EBERHARD, WL HARDESTY, M FLAMANT, PH VALENTIN, R FORGAN, B GIMMESTAD, GG JAGER, H KHMELEVTSOV, SS KOLEV, I KAPRIEOLEV, B LU, DR SASSEN, K SHAMANAEV, VS UCHINO, O MIZUNO, Y WANDINGER, U WEITKAMP, C ANSMANN, A WOOLDRIDGE, C AF PLATT, CM YOUNG, SA CARSWELL, AI PAL, SR MCCORMICK, MP WINKER, DM DELGUASTA, M STEFANUTTI, L EBERHARD, WL HARDESTY, M FLAMANT, PH VALENTIN, R FORGAN, B GIMMESTAD, GG JAGER, H KHMELEVTSOV, SS KOLEV, I KAPRIEOLEV, B LU, DR SASSEN, K SHAMANAEV, VS UCHINO, O MIZUNO, Y WANDINGER, U WEITKAMP, C ANSMANN, A WOOLDRIDGE, C TI THE EXPERIMENTAL CLOUD LIDAR PILOT-STUDY (ECLIPS) FOR CLOUD-RADIATION RESEARCH SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID OPTICAL-PROPERTIES; CLIMATE FEEDBACK; CIRRUS CLOUDS; WATER CLOUDS; EXTINCTION; RETURNS; DATASET; CO2 AB The Experimental Cloud Lidar Pilot Study (ECLIPS) was initiated to obtain statistics on cloud-base height, extinction, optical depth, cloud brokenness, and surface fluxes. Two observational phases have taken place, in October-December 1989 and April-July 1991, with intensive 30-day periods being selected within the two time intervals. Data are being archived at NASA Langley Research Center and, once there, are readily available to the international scientific community. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. YORK UNIV,DEPT PHYS,N YORK,ON,CANADA. YORK UNIV,CRESS,N YORK,ON,CANADA. CNR,INST RIC ONDE ELETTROMAGNET,I-50127 FLORENCE,ITALY. NOAA,ENVIRONM TOXICOL LAB,BOULDER,CO 80303. ECOLE POLYTECH,CNRS,METEOROL DYNAM LAB,F-91128 PALAISEAU,FRANCE. BUR METEOROL,MELBOURNE,VIC,AUSTRALIA. GEORGIA INST TECHNOL,GTRI,EMLEOD,ATLANTA,GA 30332. FRAUNHOFER INST ATMOSPHAR UMWELTFORSCH,GARMISCH PARTENKIRCH,GERMANY. INST EXPTL METEOROL,PHYS & CLIMATE LAB,OBNINSK,RUSSIA. BULGARIAN ACAD SCI,INST ELECTR,BU-1113 SOFIA,BULGARIA. INST ATMOSPHER PHYS,BEIJING,PEOPLES R CHINA. UNIV UTAH,DEPT METEOROL,SALT LAKE CITY,UT 84112. INST ATMOSPHER OPT,TOMSK,RUSSIA. JAPAN METEOROL AGCY,METEOROL RES INST,YATABE,IBARAKI,JAPAN. GKSS FORSCHUNGSZENTRUM GEESTHACHT GMBH,GEESTHACHT,GERMANY. INST TROPOSPHARENFORSCH,LEIPZIG,GERMANY. MACQUARIE UNIV,SCH EARTH SCI,SYDNEY,AUSTRALIA. RP PLATT, CM (reprint author), CSIRO,DIV ATMOSPHER RES,PB 1,MORDIALLOC,VIC 3195,AUSTRALIA. RI Young, Stuart/A-8641-2011; Hardesty, Robert/H-9844-2013; Wandinger, Ulla/E-3348-2014; Garmisch-Pa, Ifu/H-9902-2014; Eberhard, Wynn/B-5402-2015 OI Young, Stuart/0000-0001-6434-9816; NR 43 TC 48 Z9 53 U1 1 U2 2 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 1994 VL 75 IS 9 BP 1635 EP 1654 DI 10.1175/1520-0477(1994)075<1635:TECLPS>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PJ538 UT WOS:A1994PJ53800004 ER PT J AU NOEVER, DA MATSOS, HC CRONISE, RJ LOOGER, LL RELWANI, RA JOHNSON, JU AF NOEVER, DA MATSOS, HC CRONISE, RJ LOOGER, LL RELWANI, RA JOHNSON, JU TI COMPUTERIZED IN-VITRO TEST FOR CHEMICAL TOXICITY BASED ON TETRAHYMENA SWIMMING PATTERNS SO CHEMOSPHERE LA English DT Article ID BIOCONVECTIVE PATTERNS; OCULAR IRRITATION; THERMOPHILA; BIOASSAY; RABBITS AB An apparatus and a method for rapidly determining chemical toxicity have been evaluated as an alternative to the rabbit eye initancy test (Draize). The toxicity monitor includes an automated scoring of how motile biological cells (Tetrahymena pyriformis) slow down or otherwise change their swimming patterns in a hostile chemical environment. The method, called the Motility Assay (MA), is tested for 30 s to determine the chemical toxicity in 20 aqueous samples containing trace organics and salts. With equal or better detection limits, results compare favorably to in vivo animal tests of eye irritancy. C1 ALABAMA A&M UNIV,DEPT ANIM & FOOD SCI,NORMAL,AL. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES76,HUNTSVILLE,AL 35812, USA. NR 9 TC 9 Z9 9 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-6535 J9 CHEMOSPHERE JI Chemosphere PD SEP PY 1994 VL 29 IS 6 BP 1373 EP 1384 DI 10.1016/0045-6535(94)90269-0 PG 12 WC Environmental Sciences SC Environmental Sciences & Ecology GA PK802 UT WOS:A1994PK80200019 PM 7953473 ER PT J AU MARENGO, JA MILLER, JR RUSSELL, GL ROSENZWEIG, CE ABRAMOPOULOS, F AF MARENGO, JA MILLER, JR RUSSELL, GL ROSENZWEIG, CE ABRAMOPOULOS, F TI CALCULATIONS OF RIVER-RUNOFF IN THE GISS GCM - IMPACT OF A NEW LAND-SURFACE PARAMETERIZATION AND RUNOFF ROUTING MODEL ON THE HYDROLOGY OF THE AMAZON RIVER SO CLIMATE DYNAMICS LA English DT Article ID TROPICAL DEFORESTATION; REGIONAL CLIMATE; SEDIMENT; SCALE; BASIN AB This study examines the impact of a new land-surface parameterization and a river routing scheme on the hydrology of the Amazon basin, as depicted by the NASA/Goddard Institute of Space Studies (GISS) global climate model (GCM). The more physically realistic land surface scheme introduces a vegetation canopy resistance and a six-layer soil system. The new routing scheme allows runoff to travel from a river's headwater to its mouth according to topography and other channel characteristics and improves the timing of the peak flow. River runoff is examined near the mouth of the Amazon and for all of its sub-basins. With the new land-surface parameterization, river runoff increases significantly and is consistent with that observed in most basins and at the mouth. The representation of the river hydrology in small basins is not as satisfactory as in larger basins. One positive impact of the new land-surface parameterization is that it produces more realistic evaporation over the Amazon basin, which was too high in the previous version of the GCM. The realistic depiction of evaporation also affects the thermal regime in the lower atmosphere in the Amazon. In fact, the lower evaporation in some portions of the basin reduces the cloudiness, increases the solar radiation reaching the ground, increases the net radiation at the surface, and warms the surface as compared to observations. Further GCM improvement is needed to obtain a better representation of rainfall processes. C1 RUTGERS STATE UNIV,DEPT MARINE & COASTAL SCI,NEW BRUNSWICK,NJ 08903. COLUMBIA UNIV,NEW YORK,NY 10025. NASA,GODDARD INST SPACE STUDIES,HUGHES STX CORP,NEW YORK,NY 10025. RP MARENGO, JA (reprint author), FLORIDA STATE UNIV,DEPT METEOROL,TALLAHASSEE,FL 32306, USA. RI Marengo, Jose /J-9382-2012 OI Marengo, Jose /0000-0002-8154-2762 NR 59 TC 39 Z9 40 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD SEP PY 1994 VL 10 IS 6-7 BP 349 EP 361 DI 10.1007/BF00228032 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PJ544 UT WOS:A1994PJ54400006 ER PT J AU STARK, G DURST, RC VOWELL, CW AF STARK, G DURST, RC VOWELL, CW TI USING METRICS IN MANAGEMENT DECISION-MAKING SO COMPUTER LA English DT Article AB This article describes the local environmental factors that influenced the implementation of this metrics initiative and shaped the development of the MOD metrics toolkit. Describing several projects, the authors show how the metrics toolkit helped MOD determine whether a project was on schedule and within budget, when subsystems were ready to be integrated, and whether a particular test schedule made sense. The toolkit helped ensure consistent data collection across projects and increased the number and types of analysis options available to project personnel. Most important, the metrics analysis described here helped MOD project engineers and managers make decisions about project and mission readiness by removing the inherent optimism of ''engineering judgment.'' C1 NASA,LYNDON B JOHNSON SPACE CTR,MISS OPERAT DIRECTORATE,SYST ENGN OFF,HOUSTON,TX 77058. MITRE CORP,HOUSTON,TX. RP STARK, G (reprint author), MITRE CORP,1259 LAKE PLAZA,COLORADO SPRINGS,CO 80906, USA. RI Sawhney, Davinder/A-5736-2010 NR 8 TC 16 Z9 16 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 0018-9162 J9 COMPUTER JI Computer PD SEP PY 1994 VL 27 IS 9 BP 42 EP 48 DI 10.1109/2.312037 PG 7 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA PF958 UT WOS:A1994PF95800013 ER PT J AU YAO, XS MALEKI, L AF YAO, XS MALEKI, L TI HIGH-FREQUENCY OPTICAL SUBCARRIER GENERATOR SO ELECTRONICS LETTERS LA English DT Article DE ELECTROOPTICAL DEVICES; OPTICAL MODULATION AB The authors describe an electro-optical oscillator capable of generating high stability optical signals at frequencies up to 70GHz. Signals as high as 9.2GHz were generated with an optical wavelength of 1310nm using the oscillator, and a comb of stable frequencies was produced by modelocking the oscillator. RP YAO, XS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 3 TC 91 Z9 97 U1 2 U2 11 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD SEP 1 PY 1994 VL 30 IS 18 BP 1525 EP 1526 DI 10.1049/el:19941033 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA PG482 UT WOS:A1994PG48200046 ER PT J AU RAY, RD SANCHEZ, BV AF RAY, RD SANCHEZ, BV TI IMPROVED SMOOTHING OF AN ALTIMETRIC OCEAN-TIDE MODEL WITH GLOBAL PROUDMAN FUNCTIONS SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Note DE OCEAN TIDES; RIDGE REGRESSION; SATELLITE ALTIMETRY; TIDES ID GEOSAT ALTIMETRY AB A set of global Proudman functions, computed on a 2 degrees finite-difference grid, is used to smooth raw tidal estimates previously derived by Cartwright and Ray from a two-year analysis of Geosat altimeter data. The least-squares problem provides an interesting application of ridge regression and Hansen's L-curve analysis. The final smoothed maps are found to agree more closely to a set of 80 'ground-truth' constants than did the original tidal models. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE GEODESY BRANCH,GREENBELT,MD 20771. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HSTX,CODE 926,GREENBELT,MD 20771, USA. RI Sanchez, Braulio/I-5952-2013 NR 11 TC 3 Z9 3 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD SEP PY 1994 VL 118 IS 3 BP 788 EP 794 DI 10.1111/j.1365-246X.1994.tb04000.x PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PG500 UT WOS:A1994PG50000022 ER PT J AU SMITH, DE KOLENKIEWICZ, R ROBBINS, JW DUNN, PJ TORRENCE, MH AF SMITH, DE KOLENKIEWICZ, R ROBBINS, JW DUNN, PJ TORRENCE, MH TI HORIZONTAL CRUSTAL MOTION IN THE CENTRAL AND EASTERN MEDITERRANEAN INFERRED FROM SATELLITE LASER RANGING MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ALPINE-HIMALAYAN BELT; ACTIVE TECTONICS; AEGEAN SEA; DEFORMATION; KINEMATICS; ROTATION; REGION; GREECE AB Four campaigns to acquire Satellite Laser Ranging (SLR) measurements at sites in the Mediterranean region have been completed. These measurements to the LAGEOS satellite, made largely by mobile systems, cover a time span beginning in November 1985 and ending in June 1993. The range data from 18 sites in the central and eastern Mediterranean have been simultaneously analyzed with data acquired by the remainder of the global laser tracking network. Estimates of horizontal motion were placed into a regional, northern Europe-fixed, kinematic reference frame. Uncertainties are on the order of 5 mm/yr for sites having at least four occupations by mobile systems and approach 1 mm/yr for permanently located sites with long histories of tracking. The resulting relative motion between sites in the Aegean exhibit characteristics of broadly distributed pattern of radial extension, but at rates that are about 50% larger than those implied from studies of seismic strain rates based on seismicity of magnitude 6 or greater across the region. The motion estimated for sites in Turkey exhibit velocity components associated with the westward motion of the Anatolian Block relative to Eurasia. These results provide a present-day ''snapshot'' of ongoing deformational processes as experienced by the locations occupied by SLR systems. C1 HUGHES STX CORP,GREENBELT,MD 20770. RP SMITH, DE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,CODE 921,GREENBELT,MD 20771, USA. NR 25 TC 46 Z9 46 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 1994 VL 21 IS 18 BP 1979 EP 1982 DI 10.1029/94GL01612 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PE824 UT WOS:A1994PE82400014 ER PT J AU JENSEN, EJ TOON, OB AF JENSEN, EJ TOON, OB TI ICE NUCLEATION IN THE UPPER TROPOSPHERE - SENSITIVITY TO AEROSOL NUMBER DENSITY, TEMPERATURE, AND COOLING RATE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VOLCANIC AEROSOLS; SOLUTION DROPLETS; CLOUDS; SIMULATIONS; WATER AB We have investigated the processes that control ice crystal nucleation in the upper troposphere using a numerical model. Nucleation of ice resulting from cooling was simulated for a range of aerosol number densities, initial temperatures, and cooling rates. In contrast to observations of stratus clouds, we find that the number of ice crystals that nucleate in cirrus is relatively insensitive to the number of aerosols present. The ice crystal size distribution at the end of the nucleation process is unaffected by the assumed initial aerosol number density. Essentially, nucleation continues until enough ice crystals are present such that their deposition growth rapidly depletes the vapor and shuts off any further nucleation. However, the number of ice crystals nucleated increases rapidly with decreasing initial temperature and increasing cooling rate. This temperature dependence alone could explain the large ice crystal number density observed in very cold tropical cirrus. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 16 TC 72 Z9 71 U1 1 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 1994 VL 21 IS 18 BP 2019 EP 2022 DI 10.1029/94GL01287 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PE824 UT WOS:A1994PE82400024 ER PT J AU JENSEN, EJ KINNE, S TOON, OB AF JENSEN, EJ KINNE, S TOON, OB TI TROPICAL CIRRUS CLOUD RADIATIVE FORCING - SENSITIVITY STUDIES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ICE CRYSTALS; PARAMETERIZATION AB We have performed one dimensional radiative transfer calculations to evaluate the impact of cirrus clouds on the tropical radiation budget. We investigate the sensitivity of solar and infrared fluxes to cloud optical depth, particle size distributions, and cloud height. If the observed solar cloud forcing in excess of 100 W-m-2 is to be attributed to cirrus anvils alone, then the optical depth of these anvils must be at least 5 (assuming 50% cloud cover and an ice crystal effective radius of 15 mum). The net radiative forcing of cirrus near the tropical tropopause is positive (heating) for cloud optical depths less than about 16 and negative (cooling) for larger optical depths. If cirrus clouds alone are responsible for the equal and opposite shortwave and longwave cloud forcing in excess of 100 W-m-2 observed by ERBE, then the cirrus must typically take the form of deep, optically thick clouds with relatively small particles (radii of 10-20 mum) and cloud-tops well below the tropopause. The maintenance of this balance on monthly time scales can be attributed to a variety of correlations: The cloud cover of optically thick cirrus or thin cirrus overlying low-level stratus clouds could vary; or cirrus anvil height could increase along with a decrease in the ice crystal effective radius and an increase in optical depth. It would be of great interest to determine observationally which of these correlations is responsible for the observed lack of variation in cloud forcing. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 10 TC 48 Z9 48 U1 1 U2 8 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 1994 VL 21 IS 18 BP 2023 EP 2026 DI 10.1029/94GL01358 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PE824 UT WOS:A1994PE82400025 ER PT J AU HOYT, DV SCHATTEN, KH NESMESRIBES, E AF HOYT, DV SCHATTEN, KH NESMESRIBES, E TI THE 100TH YEAR OF WOLF,RUDOLF DEATH - DO WE HAVE THE CORRECT RECONSTRUCTION OF SOLAR-ACTIVITY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB In the one hundred years since Wolf died, little effort has gone into research to see if improved reconstructions of sunspot numbers can be made. We have gathered more than 349,000 observations of daily sunspot group counts from more than 350 observers active from 1610 to 1993. Based upon group counts alone, it is possible to make an objective and homogeneous reconstruction of sunspot numbers. From our study, it appears that the Sun has steadily increased in activity since 1700 with the exception of a brief decrease in the Dalton Minimum (1795-1823). The significant results here are the greater depth of the Dalton Minimum, the generally lower activity throughout the 1700's, and the gradual rise in activity from the Maunder Minimum to the present day. This solar activity reconstruction is quite similar to those Wolf published before 1868 rather than the revised Wolf reconstructions after 1873 which used geomagnetic fluctuations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. OBSERV PARIS,F-92190 MEUDON,FRANCE. RP HOYT, DV (reprint author), RES & DATA SYST CORP,7855 WALKER DR,SUITE 460,GREENBELT,MD 20770, USA. NR 9 TC 84 Z9 84 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 1 PY 1994 VL 21 IS 18 BP 2067 EP 2070 DI 10.1029/94GL01698 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PE824 UT WOS:A1994PE82400036 ER PT J AU GORNITZ, V FUNG, I AF GORNITZ, V FUNG, I TI POTENTIAL DISTRIBUTION OF METHANE HYDRATES IN THE WORLDS OCEANS SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID BOTTOM-SIMULATING-REFLECTORS; SEA-LEVEL; HEAT-FLOW; GAS; BASE; SEDIMENT; ZONE AB Estimates of the magnitudes and spatial distribution of potential oceanic methane hydrate reservoirs have been made from pressure-temperature phase relations and a plausible range of thermal gradients, sediment porosities, and pore fillings taken from published sources, based on two major theories of gas hydrate formation (1) in situ bacterial production and (2) pore fluid expulsion models. The implications of these two models on eventual atmospheric methane release, due to global warming, are briefly examined. The calculated range of methane volumes in oceanic gas hydrates is 26.4 to 139.1 x 10(15) m(3), with the most likely value on the lower end of this range. The results for the bacterial model show a preferential distribution of hydrates at mid- to high latitudes, with an equatorial enhancement in the case of the fluid migration model. The latter model also generates a deeper and thicker hydrate stability zone at most latitudes than does the former. Preliminary results suggest that the hydrate distribution predicted by the fluid migration model may be more consistent with observations. However, this preliminary finding is based on a very limited sample size, and there are high uncertainties in the assumptions. The volume of methane hydrate within the uppermost 1 m of the hydrate stability zone and within 1 degrees-2 degrees C of the equilibrium curve, assuming in situ bacterial generation, is 0.93-6.32 x 10(12) m(3), or 0.0035-0.012% of the maximal estimated hydrate reservoir. Nevertheless this volume, if released uniformly over the next 100 years, is comparable to current CH4 release rates for several important CH4 sources. Corresponding CH4 volumes calculated using the fluid migration model are nearly 2 orders of magnitude lower. C1 UNIV VICTORIA,SCH EARTH & OCEAN SCI,VICTORIA V8W 2Y2,BC,CANADA. COLUMBIA UNIV,INST SPACE STUDIES,NEW YORK,NY. RP GORNITZ, V (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 52 TC 103 Z9 133 U1 1 U2 23 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD SEP PY 1994 VL 8 IS 3 BP 335 EP 347 DI 10.1029/94GB00766 PG 13 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA PE619 UT WOS:A1994PE61900007 ER PT J AU LAUNIUS, RD AF LAUNIUS, RD TI NASA AND THE DECISION TO BUILD THE SPACE-SHUTTLE, 1969-72 SO HISTORIAN LA English DT Article RP LAUNIUS, RD (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 39 TC 5 Z9 5 U1 0 U2 3 PU PHI ALPHA THETA PI ALLENTOWN PA THE HISTORIAN 50 COLLEGE DR, ALLENTOWN, PA 18104-6100 SN 0018-2370 J9 HISTORIAN JI Historian PD FAL PY 1994 VL 57 IS 1 BP 17 EP 34 DI 10.1111/j.1540-6563.1994.tb01331.x PG 18 WC History SC History GA PQ427 UT WOS:A1994PQ42700002 ER PT J AU SADER, SA SEVER, T SMOOT, JC RICHARDS, M AF SADER, SA SEVER, T SMOOT, JC RICHARDS, M TI FOREST CHANGE ESTIMATES FOR THE NORTHERN PETEN REGION OF GUATEMALA - 1986-1990 SO HUMAN ECOLOGY LA English DT Article DE REMOTE SENSING; GIS, PETEN ID POPULATION; VEGETATION; HABITAT AB Landsat-thematic mapper images recorded April 1986 and 1990 were obtained for northern Guatemala. The study area corresponds to a major portion of Guatemala's Maya Biosphere reserve but also includes land outside the western and southern boundary of the reserve. The normalized difference vegetation index (NDVI) was computed at each date and image differencing (subtraction) was performed. The resulting image was thresholded into three categories: regrowth, no change, and forest clearing. A 10 x 10 km grid system was superimposed on the image to categorize the percentage of each 100 km2 cell that changed between 1986 and 1990. Forest clearing patterns were apparent along the border areas (Mexico and Guatemala) and all along the southern portion of the study area where human populations were moving toward the Maya Biosphere borders, along existing roads. Forest clearing was negligible or absent in the roadless areas. C1 NASA,EARTH OBSERVAT RES,BAY ST LOUIS,MS. LOCKHEED ENGN & SCI CO,BAY ST LOUIS,MS. UNIV VALLE GUATEMALA,GUATEMALA CITY,GUATEMALA. RP SADER, SA (reprint author), UNIV MAINE,COLL NAT RESOURCES FORESTRY & AGR,ORONO,ME 04469, USA. NR 30 TC 40 Z9 41 U1 1 U2 2 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0300-7839 J9 HUM ECOL JI Hum. Ecol. PD SEP PY 1994 VL 22 IS 3 BP 317 EP 332 DI 10.1007/BF02168855 PG 16 WC Anthropology; Environmental Studies; Sociology SC Anthropology; Environmental Sciences & Ecology; Sociology GA PZ904 UT WOS:A1994PZ90400004 ER PT J AU WOODWARD, RC SCHERB, F ROESLER, FL OLIVERSEN, RJ AF WOODWARD, RC SCHERB, F ROESLER, FL OLIVERSEN, RJ TI PERIODIC INTENSITY VARIATIONS IN SULFUR EMISSIONS FROM THE IO PLASMA TORUS SO ICARUS LA English DT Article; Proceedings Paper CT IO Conference CY JUN 22-25, 1993 CL SAN JUAN CAPISTRANO RES INST, SAN JUAN CAPISTRANO, CA SP SAN JUAN CAPISTRANO RES INST HO SAN JUAN CAPISTRANO RES INST ID JOVIAN KILOMETRIC RADIATION; JUPITERS MAGNETOSPHERE; COROTATION LAG; TIME-SERIES; SPACED DATA; ROTATION; RADIO; DEPARTURE; FIELDS AB In November and December 1988, we acquired 157 spectra of [S II]lambda6731 emissions from the Io plasma torus with a Fabry-Perot interferometer at the McMath-Pierce Solar Telescope facility on Kitt Peak. A major goal of this experiment was to extend our earlier studies of intensity variations in the plasma torus. Our earlier analysis (F. L. Roesler, F. Scherb, and R. J. Oliversen, 1984, Geophys. Res. Lett. 11, 128-130) of [S III]lambda9531 emission spectra acquired in April 1982 had shown that the intensity of torus emissions varied periodically with a period of 10.20 +/- 0.06 hr (1-sigma uncertainty level), slightly longer than Jupiter's System III rotational period of 9.925 hr. We present here a reanalysis of our 1982 data revealing, in addition to the 10.20-hr period, a clear secondary periodicity at 9.95 +/- 0.06 hr. By contrast, we show that our new [S II]lambda6731 data have a single period of 10.14 +/- 0.03 hr, which is neither the System III period nor the proposed ''System IV'' period of 10.224 hr. (C) 1994 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WOODWARD, RC (reprint author), UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706, USA. NR 29 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1994 VL 111 IS 1 BP 45 EP 64 DI 10.1006/icar.1994.1132 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP107 UT WOS:A1994PP10700005 ER PT J AU BELL, JF POLLACK, JB GEBALLE, TR CRUIKSHANK, DP FREEDMAN, R AF BELL, JF POLLACK, JB GEBALLE, TR CRUIKSHANK, DP FREEDMAN, R TI SPECTROSCOPY OF MARS FROM 2.04 TO 2.44 MU-M DURING THE 1993 OPPOSITION - ABSOLUTE CALIBRATION AND ATMOSPHERIC VS MINERALOGIC ORIGIN OF NARROW ABSORPTION FEATURES SO ICARUS LA English DT Article ID REFLECTANCE SPECTROSCOPY; MARTIAN ATMOSPHERE; INFRARED-SPECTRA; SURFACE REGIONS; SOIL; DUST; MONTMORILLONITE; ANALOG; CARBONATES; METEORITES AB We present moderate-resolution (lambda/DELTAlambda = 300 to 370) reflectance spectra of Mars from 2.04 to 2.44 mum that were obtained at UKIRT during the 1993 opposition. Seven narrow absorption features were detected and found to have a Mars origin. By comparison with solar and Mars atmospheric spectra, five of these features were attributed all or in part to Mars atmospheric CO2 or CO (2.052 +/- 0.003, 2.114 +/- 0.002, 2.150 +/- 0.003, 2.331 +/- 0.001, and 2.357 +/- 0.002 mum). Two of the bands (2.331 +/- 0.001 and 2.357 +/- 0.002 mum) appear to have widths and depths that are consistent with additional, nonatmospheric absorptions, although a solar contribution cannot be entirely ruled out. Two other weak bands centered at 2.278 +/- 0.002 and 2.296 +/- 0.002 mum may be at least partially mineralogic in origin. The data provide no conclusive identification of the mineralogy responsible for these absorption features. However, examination of terrestrial spectral libraries and previous moderate spectral resolution mineral studies indicates that the most likely origin of these features is either (bi)carbonate or (bi)sulfate anions in framework silicates or (Fe, Mg)-OH bonds in sheet silicates. If the bands are caused by phyllosilicate minerals, then an explanation must be found for the extremely narrow widths of the cation-OH features in the Mars spectra as compared to terrestrial minerals. (C) 1994 Academic Press, Inc. C1 JOINT ASTRON CTR,HILO,HI 96720. STERLING SOFTWARE INC,PALO ALTO,CA 94030. RP BELL, JF (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 65 TC 30 Z9 30 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1994 VL 111 IS 1 BP 106 EP 123 DI 10.1006/icar.1994.1136 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP107 UT WOS:A1994PP10700009 ER PT J AU BOHN, RB SANDFORD, SA ALLAMANDOLA, LJ CRUIKSHANK, DP AF BOHN, RB SANDFORD, SA ALLAMANDOLA, LJ CRUIKSHANK, DP TI INFRARED-SPECTROSCOPY OF TRITON AND PLUTO ICE ANALOGS - THE CASE FOR SATURATED-HYDROCARBONS SO ICARUS LA English DT Article ID TIME-DEPENDENT CHEMISTRY; DENSE MOLECULAR CLOUDS; SOLID NITROGEN; AB-INITIO; MATRIX; IRRADIATION; SPECTRA; SURFACE; FORMALDEHYDE; COMETARY AB The infrared transmission spectra and photochemical behavior of various organic compounds isolated in solid N2 ices, appropriate for applications to Triton and Pluto, are presented. It is shown that excess absorption in the surface spectra of Triton and Pluto, i.e., absorption not explained by present models incorporating molecules already identified on these bodies (N2, CH4, CO, and CO2), that starts near 4450 cm-1 (2.25 mum) and extends to lower frequencies, may be due to alkanes (C(n)H2n+2) and related molecules frozen in the nitrogen. Branched and linear alkanes may be responsible. Experiments in which the photochemistry of N2:CH4 and N2:CH4:CO ices was explored demonstrate that the surface ices of Triton and Pluto may contain a wide variety of additional species containing H, C, O, and N. Of these, the reactive molecule diazomethane, CH2N2, is particularly important since it may be largely responsible for the synthesis of larger alkanes from CH4 and other small alkanes. Diazomethane would also be expected to drive chemical reactions involving organics in the surface ices of Triton and Pluto toward saturation, i.e., to reduce multiple CC bonds. The positions and intrinsic strengths (A values) of many of the infrared absorption bands of N2 matrix-isolated molecules of relevance to Triton and Pluto have also been determined. These can be used to aid in their search and to place constraints on their abundances. For example, using these A values the abundance ratios CH4/N2 almost-equal-to 1.3 x 10(-3), C2H4/N2 less-than-or-equal-to 9.5 x 10(-7), and H2CO/N2 less-than-or-equal-to 7.8 x 10(-7) are deduced for Triton and CH4/N2 almost-equal-to 3.1 x 10(-3), C2H4/N2 less-than-or-equal-to 4.1 x 10(-6), and H2CO/N2 less-than-or-equal-to 5.2 x 10(-6) deduced for Pluto. The small amounts of C2H4 and H2CO in the surface ices of these bodies are in disagreement with the large abundances expected from many theoretical models. RP BOHN, RB (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 61 TC 65 Z9 65 U1 0 U2 7 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1994 VL 111 IS 1 BP 151 EP 173 DI 10.1006/icar.1994.1138 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP107 UT WOS:A1994PP10700011 PM 11539177 ER PT J AU PLESCIA, JB AF PLESCIA, JB TI GEOLOGY OF THE SMALL THARSIS VOLCANOS - JOVIS-THOLUS, ULYSSES-PATERA, BIBLIS-PATERA, MARS SO ICARUS LA English DT Article ID KILAUEA-VOLCANO; TERRESTRIAL ANALOGS; CALDERAS; ORIGIN; FERNANDINA; SUBSIDENCE; SEAMOUNTS; GALAPAGOS; EVOLUTION; CRATERS AB Jovis Tholus, Ulysses Patera, and Biblis Patera, three small volcanoes in the Tharsis area of Mars, provide important insight into the evolution of volcanism on Mars. All three are interpreted to be shield volcanoes, indicating that shield volcanism was present from the outset in Tharsis. Jovis Tholus is the least complex with simple repeated outpouring of lavas and caldera-forming events. Ulysses Patera is dominated by a giant caldera within which is a line of cinder cones or domes suggesting terminal stages of volcanism in which the magma had either significant volatiles or increased viscosity. Biblis Patera is characterized by nested calderas which have expanded by block faulting of the flank; it also exhibits lava flows erupted onto the flanks from events along concentric fractures. These shields are different from the younger Tharsis Montes shields only in terms of the volume of erupted material. The limited shield volume suggests that the magma source which fed the shields was rapidly depleted. The relatively large size of the calderas probably results from relatively large, shallow magma bodies rather than significant burial of the flanks by younger lavas. Eruption rates consistent with typical terrestrial basaltic eruption rates suggest that these volcanoes were probably built over time spans of 10(4) to 10(5) years. Stratigraphic ages range from Early to Upper Hesperian; absolute ages range from 1.9 to 3.4 Ga. (C) 1994 Academic Press, Inc. C1 JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RI Plescia, Jeffrey/B-7738-2016 NR 74 TC 23 Z9 23 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 1994 VL 111 IS 1 BP 246 EP 269 DI 10.1006/icar.1994.1144 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PP107 UT WOS:A1994PP10700017 ER PT J AU CHAPMAN, B ZIMA, H MEHROTRA, P AF CHAPMAN, B ZIMA, H MEHROTRA, P TI EXTENDING HPF FOR ADVANCED DATA-PARALLEL APPLICATIONS SO IEEE PARALLEL & DISTRIBUTED TECHNOLOGY LA English DT Article ID EXECUTION; LOOPS AB High Performance Fortran can support regular numerical algorithms, but it cannot adequately express advanced applications such as particle-in-cell codes or unstructured mesh solvers. This article addresses this problem and outlines possible development paths. C1 NASA, LANGLEY RES CTR, INST COMP APPLICAT SCI & ENGN, HAMPTON, VA 23681 USA. RP CHAPMAN, B (reprint author), UNIV VIENNA, INST SOFTWARE TECHNOL & PARALLEL SYST, BRUNNER STR 72, A-1210 VIENNA, AUSTRIA. NR 16 TC 12 Z9 12 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1063-6552 J9 IEEE PARALL DISTRIB JI IEEE Parallel Distrib. Technol. PD FAL PY 1994 VL 2 IS 3 BP 59 EP 70 DI 10.1109/M-PDT.1994.329803 PG 12 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PW320 UT WOS:A1994PW32000012 ER PT J AU MENDEZ, AJ LAMBERT, JL MOROOKIAN, JM GAGLIARDI, RM AF MENDEZ, AJ LAMBERT, JL MOROOKIAN, JM GAGLIARDI, RM TI SYNTHESIS AND DEMONSTRATION OF HIGH-SPEED, BANDWIDTH EFFICIENT OPTICAL CODE-DIVISION MULTIPLE-ACCESS (CDMA) TESTED AT 1-GB/S THROUGHPUT SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article ID NETWORKS AB Code division multiple access (CDMA) permits concurrent communication over all virtual channels (in principle), independent of the data rate and the network size. In reality, most CDMA approaches have a bandwidth penalty due to the code length and a loss penalty due to the broadcasting required by CDMA. Both of these penalties can be reduced or ameliorated by means of multi-attribute coding. Matrices constructed from relatively inefficient (0, 1) pulse sequences are suitable multi-attribute non-coherent CDMA codes which are both bandwidth and broadcast efficient. We exhibit a novel approach to synthesizing matrix CDMA codes, develop a 4 x 4 physical model, and demonstrate concurrent communication experimentally at concurrent data rates of 100-, 150-, and 250 Mb/s per port. C1 JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,INST COMMUN SCI,LOS ANGELES,CA 90089. RP MENDEZ, AJ (reprint author), MENDEZ R&D ASSOCIATES,EL SEGUNDO,CA 90245, USA. NR 13 TC 28 Z9 29 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD SEP PY 1994 VL 6 IS 9 BP 1146 EP 1149 DI 10.1109/68.324694 PG 4 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA PK226 UT WOS:A1994PK22600029 ER PT J AU GONG, JA VOLAKIS, JL WOO, AC WANG, HTG AF GONG, JA VOLAKIS, JL WOO, AC WANG, HTG TI A HYBRID FINITE-ELEMENT BOUNDARY INTEGRAL METHOD FOR THE ANALYSIS OF CAVITY-BACKED ANTENNAS OF ARBITRARY SHAPE SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID MICROSTRIP ANTENNAS; SCATTERING; COMPUTATION AB An edge-based hybrid finite element-boundary integral (FE-BI) formulation using tetrahedral elements is described for scattering and radiation analysis of arbitrarily shaped cavity-backed patch antennas. By virtue of the finite element method (FEM), the cavity irregularities, the dielectric super/substrate inhomogeneities, and the diverse excitation schemes inside the cavity may be readily modeled when tetrahedral elements are used to discretize the cavity. On the aperture, the volume mesh reduces to a triangular grid allowing the modeling of non-rectangular patches. Without special handling of the boundary integral system, this formulation is typically applicable to cavity-backed antenna systems with moderate aperture size. To retain an O(N) memory requirement, storage of the full matrix due to the boundary integral equation is avoided by resorting to a structured triangular aperture grid and taking advantage of the integral's convolutional property. If necessary, this is achieved by overlaying a structured triangular grid on the unstructured triangular grid and relating the edge field coefficients between the two grids via two narrow banded transformation matrices. The combined linear system of equations is solved via the biconjugate gradient (BiCG) method, and the FFT algorithm is incorporated to compute the matrix-vector product efficiently, with minimal storage requirements. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. USN,CTR AIR WARFARE,CHINA LAKE,CA 93555. RP GONG, JA (reprint author), UNIV MICHIGAN,RADIAT LAB,ANN ARBOR,MI 48109, USA. NR 15 TC 31 Z9 31 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 1994 VL 42 IS 9 BP 1233 EP 1242 DI 10.1109/8.318644 PG 10 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PH084 UT WOS:A1994PH08400004 ER PT J AU BAYARD, DS AF BAYARD, DS TI AN ALGORITHM FOR STATE-SPACE FREQUENCY-DOMAIN IDENTIFICATION WITHOUT WINDOWING DISTORTIONS SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note AB An algorithm is presented for identifying state-space models from frequency-domain data. The main advantage of this approach is that it avoids windowing distortions associated with other frequency-domain methods. Other advantages are that an arbitrary frequency weighting can be introduced to shape the estimation error, and the system order can be overspecified. The numerical properties are demonstrated on real physical data taken on a complex flexible structure, leading to the successful identification of a multivariable (four-input/three-output) 100-state model over a bandwidth of 100 Hertz. The results indicate that the algorithm would be useful in applications requiring the accurate identification of high-order systems over wide bandwidths. RP BAYARD, DS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 30 TC 13 Z9 13 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD SEP PY 1994 VL 39 IS 9 BP 1880 EP 1885 DI 10.1109/9.317117 PG 6 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA PG373 UT WOS:A1994PG37300016 ER PT J AU SARABANDI, K PIERCE, LE OH, Y DOBSON, MC ULABY, FT FREEMAN, A DUBOIS, P AF SARABANDI, K PIERCE, LE OH, Y DOBSON, MC ULABY, FT FREEMAN, A DUBOIS, P TI CROSS-CALIBRATION EXPERIMENT OF JPL AIRSAR AND TRUCK-MOUNTED POLARIMETRIC SCATTEROMETER SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT IEEE International Geoscience and Remote Sensing Symposium: Better Understanding of Earth Environment (IGARSS 93) CY AUG 18-22, 1993 CL TOKYO, JAPAN SP INST ELECT INFORMAT & COMMUN ENGINEERS JAPAN, URSI ID SAR AB When point calibration targets are used to calibrate a SAR image, the calibration accuracy is governed by two major factors. The first factor stems from the stringent requirement on the radar cross section (RCS) of the point calibration target. To reduce the effect of radar return from the background, the RCS of a point calibration target must be much larger than that of the background. Calibration targets with large RCS require large physical dimensions for passive targets or high amplifier gain for active targets, which in practice leads to uncertainty in the nominal RCS of the targets. The second factor is related to the fact that point calibration targets are used to develop a calibration algorithm which is applied to distributed targets. To this end, accurate knowledge of the impulse response (ambiguity function) of the SAR system is required. To evaluate the accuracy of such a calibration process, a cross-calibration experiment was conducted at a test site near Pellston, MI, using the JPL aircraft SAR and the University of Michigan truck-mounted polarimetric scatterometer. Five different types of distributed surfaces, all in the same area, were chosen: three of these were bare surfaces with varying roughnesses, and the other two were covered with vegetation (one with short grass and the other with tall grass). Trihedral corner reflectors were used for calibrating the aircraft SAR, and the UM scatterometer was calibrated using a metallic sphere. The scatterometer data were collected at L and C bands immediately after the aircraft flew over the test site. This paper presents results of the cross calibration between the polarimetric SAR and ground-based polarimetric scatterometer measurements at L and C bands. Comparison of the data measured by the two radar systems shows that SAR calibration with trihedrals may lead to unreliable results. It is shown that coherent and incoherent interaction of the ground with a trihedral reflector can significantly alter the expected RCS of an isolated trihedral. A distributed-target calibration technique is introduced and applied to the data with good results. C1 NASA,CTR SPACE TERAHERTZ TECHNOL,WASHINGTON,DC 20546. JET PROP LAB,RADAR SYST GRP,PASADENA,CA 91109. RP SARABANDI, K (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,RADIAT LAB,MICROWAVE IMAGE PROC FACIL,ANN ARBOR,MI 48109, USA. RI Dubois-Fernandez, Pascale/A-6743-2012 NR 9 TC 12 Z9 15 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1994 VL 32 IS 5 BP 975 EP 985 DI 10.1109/36.312886 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA PF415 UT WOS:A1994PF41500003 ER PT J AU RIGNOT, EJM WILLIAMS, CL WAY, JB VIERECK, LA AF RIGNOT, EJM WILLIAMS, CL WAY, JB VIERECK, LA TI MAPPING OF FOREST TYPES IN ALASKAN BOREAL FORESTS USING SAR IMAGERY SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT IEEE International Geoscience and Remote Sensing Symposium: Better Understanding of Earth Environment (IGARSS 93) CY AUG 18-22, 1993 CL TOKYO, JAPAN SP INST ELECT INFORMAT & COMMUN ENGINEERS JAPAN, URSI ID POLARIMETRIC RADAR IMAGES; CLASSIFICATION; SIGNATURES; BIOMASS AB Mapping of forest types in the Tanana river floodplain, interior Alaska, is performed using a maximum-a-posteriori Bayesian classifier applied on SAR data acquired by the NASA/JPL three-frequency polarimetric AIRSAR system on several dates. Five vegetation types are separated, dominated by 1) white spruce, 2) balsam poplar, 3) black spruce, 4) alder/willow shrubs, and 5) bog/fen/nonforest vegetation. Open water of rivers and lakes is also separated. Accuracy of forest classification is investigated as a function of frequency and polarization of the radar, as well as the forest seasonal state, which includes winter/frozen, winter/thawed, spring/flooded, spring/unflooded, and summer/dry conditions. Classifications indicate that C-band is a more useful frequency for separating forest types than L- or P-bands, and HV polarization is the most useful polarization at all frequencies. The highest classification accuracy, with 90 percent of forest pixels classified correctly, is obtained by combining L-band HV and C-band HV data acquired in spring as seasonal river flooding recedes and before deciduous tree species have leaves. In 17 forest stands for which actual percentages of each tree species are known, the same radar data are capable of predicting tree species composition with less than 10 percent error. For the same combination of observation channels, classification accuracy is 79 percent in spring on a day of intense river flooding, and 62 percent on a dry summer day with leaves on deciduous trees. In winter, using 4-look SAR data instead of 16-look, classification accuracy is 55 percent on a frozen day, and 76 percent on a thawed day. White spruce and balsam poplar stands are best separated in thawed conditions when balsam poplar trees have no leaves. From our classification, we predict that current and future spaceborne SAR systems will have limited mapping capabilities when used alone. Yet, RADARSAT combined with J-ERS-1 and ERS-1 could resolve forest types with 80 percent accuracy, separate nonforest areas resulting from commercial logging or forest wildfire, and map river edges. For comparison, a combination of green, red, and near-infrared radiance data acquired by SPOT-2 on a dry summer day yields a classification accuracy of 83 percent for the same forest stands, with limited success in distinguishing among deciduous forest types and among coniferous forest types. C1 US FOREST SERV,INST NO FORESTRY,FAIRBANKS,AK 99701. RP RIGNOT, EJM (reprint author), JET PROP LAB,RADAR SCI & ENGN SECT,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 23 TC 32 Z9 33 U1 2 U2 12 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1994 VL 32 IS 5 BP 1051 EP 1059 DI 10.1109/36.312893 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA PF415 UT WOS:A1994PF41500010 ER PT J AU SMITH, JA GOLTZ, SM AF SMITH, JA GOLTZ, SM TI A THERMAL EXCITANCE AND ENERGY-BALANCE MODEL FOR FOREST CANOPIES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT IEEE International Geoscience and Remote Sensing Symposium: Better Understanding of Earth Environment (IGARSS 93) CY AUG 18-22, 1993 CL TOKYO, JAPAN SP INST ELECT INFORMAT & COMMUN ENGINEERS JAPAN, URSI ID RADIANCE; FIELD AB A steady-state thermal radiance model to compute thermal exitance and energy balance within forest canopies is described. The model treats fully leafed canopies as discrete ensembles of leaves partitioned into slope-angle and height classes. Short-wave energy flux absorbed within the canopy is estimated by solving simplified radiosity equations. Sensible heat exchange is estimated using a logarithmic wind profile above the canopy and a modified exponential profile within the canopy. The latent heat boundary layer resistance is estimated from site-specific measurements summarizing the effects of solar irradiance, air temperature, and vapor pressure deficit on stomatal conductance. Example comparisons for a dense spruce-fir forest study site in central Maine are given. For clear days the resulting root mean square error in modeled versus measured canopy temperatures was 1.2-degrees-C. Corresponding errors in latent and sensible heat flux energy budget terms were 30 and 32 W/m-2, respectively. For partly cloudy days the root mean square error in predicted temperature was 1.0-degrees-C and corresponding errors in latent and sensible heat were 40 and 110 W/m-2. RP SMITH, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 22 TC 15 Z9 15 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 1994 VL 32 IS 5 BP 1060 EP 1066 DI 10.1109/36.312894 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 PF415 UT WOS:A1994PF41500011 ER PT J AU GONG, P MILLER, JR SPANNER, M AF GONG, P MILLER, JR SPANNER, M TI FOREST CANOPY CLOSURE FROM CLASSIFICATION AND SPECTRAL UNMIXING OF SCENE COMPONENTS - MULTISENSOR EVALUATION OF AN OPEN CANOPY SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT IEEE International Geoscience and Remote Sensing Symposium: Better Understanding of Earth Environment (IGARSS 93) CY AUG 18-22, 1993 CL TOKYO, JAPAN SP INST ELECT INFORMAT & COMMUN ENGINEERS JAPAN, URSI ID LEAF-AREA INDEX; AVHRR DATA; VEGETATION; IMAGES AB Three types of remote sensing data, color infrared aerial photography (CIR), compact airborne spectrographic imager (CASI) imagery, and airborne visible/infrared imaging spectrometer (AVIRIS) imagery, have been used to estimate forest canopy closure for an open-canopy forest environment. The high-spatial-resolution CIR and CASI images were classified to generate forest canopy closure estimates. These estimates were used to validate the forest canopy closure estimation accuracy obtained using the AVIRIS image. Reflectance spectra extracted from the spectral-mode CASI image were used to normalize the raw AVIRIS image to a reflectance image. Classification and spectral unmixing methods have been applied to the AVIRIS image. Results indicate that both the classification and the spectral unmixing methods can produce reasonably accurate estimates of forest canopy closure (within 3 percent agreement) when related statistics are extracted from the AVIRIS image and relatively pure reflectance spectra are extracted from the CASI image. However, it is more challenging to use the spectral unmixing technique to derive subpixel-scale components whose reflectance spectra cannot be directly extracted from the AVIRIS image. C1 YORK UNIV,DEPT PHYS & ASTRON,N YORK M3J 1P3,ON,CANADA. NASA,AMES RES CTR,JOHNSON CONTROLS WORLD SERV,MOFFETT FIELD,CA 94035. YORK UNIV,INST SPACE & TERR SCI,EARTH OBSERVAT LAB,N YORK M3J 1P3,ON,CANADA. RP GONG, P (reprint author), UNIV CALIF BERKELEY,DEPT ENVIRONM SCI POLICY & MANAGEMENT,BERKELEY,CA 94720, USA. NR 37 TC 49 Z9 57 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1994 VL 32 IS 5 BP 1067 EP 1080 DI 10.1109/36.312895 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA PF415 UT WOS:A1994PF41500012 ER PT J AU RIGNOT, E WAY, JB WILLIAMS, C VIERECK, L AF RIGNOT, E WAY, JB WILLIAMS, C VIERECK, L TI RADAR ESTIMATES OF ABOVEGROUND BIOMASS IN BOREAL FORESTS OF INTERIOR ALASKA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Letter ID ATMOSPHERE-BIOSPHERE EXCHANGE; CARBON-DIOXIDE; SAR DATA; PRODUCTIVITY; BACKSCATTER; ECOSYSTEMS; IMAGES AB Airborne SAR data gathered by the NASA/JPL three-frequency, polarimetric, radar system in winter, spring, and summer over the Bonanza Creek Experimental Forest, near Fairbanks, AK, are compared to estimates of whole-tree aboveground dry biomass from 21 forest stands and two clear-cuts. While C-band radar backscatter shows little sensitivity to biomass, L- and P-band radar backscatter increase by more than 6 dB when biomass increases from 5 to 200 tons/ha. Using second-order polynomial regressions, biomass values are predicted from the radar at L- and P-band and compared to actual biomass values. At P-band HV-polarization, the error in predicted biomass is about 30% of the actual biomass. When HV- , HH- , and VV-polarization are used together in the regression, the error in predicted biomass is about 20%. Errors obtained using L-band data are a few percents larger. These errors are caused by uncertainties in actual stand biomass estimates, significant inner-stand spatial variations in biomass, unusual conditions of forest stands following natural disturbances, along with interactions of the radar signals with a complex three-dimensional structure of the canopy. Multiple incidence angle data reveal that the incidence angle theta(i) of the radar illumination is also a factor influencing the retrieval of biomass, even at HV-polarization, when theta(i) > 50-degrees or theta(i) < 25-degrees. Finally, the radar response of the forest-and thereby the regression curves for biomas retrieval-are dependent on the seasonal and environmental conditions. C1 US FOREST SERV,INST NO FORESTRY,FAIRBANKS,AK 99775. RP RIGNOT, E (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 25 TC 98 Z9 101 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 1994 VL 32 IS 5 BP 1117 EP 1124 DI 10.1109/36.312903 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 PF415 UT WOS:A1994PF41500019 ER PT J AU CRAMER, PW IMBRIALE, WA AF CRAMER, PW IMBRIALE, WA TI SPEED-UP OF NEAR-FIELD PHYSICAL OPTICS SCATTERING CALCULATIONS BY USE OF THE SAMPLING THEOREM SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 9th Conference on the Computation of Electromagnetic Fields (COMPUMAG 93) CY OCT 31-NOV 04, 1993 CL MIAMI, FL SP DIGITAL EQUIPMENT CORP, USA, VECTOR FIELDS INC, UK, INFOLYTICA CORP, CANADA, GE TRANSPORTAT SYST, USA, IBM CORP, USA, ALPS ELECT CO LTD, JAPAN, ANSOFT CORP, USA, BATH UNIV, APPL ELECTROMAGNET CTR, UK, DAEWOO ELECTR CO, KOREA, HYOSUNG IND CO, KOREA, INTEGRATED ENGN SOFTWARE INC, KOREA, MATSUSHITA ELECT IND CO LTD, JAPAN, SAMSUNG ELECTRO MECH, KOREA, SWANSEN ANAL SYST, USA, FLORIDA INT UNIV, USA AB Physical optics scattering calculations performed on the NASA Deep Space Network (DSN) 34-meter beam-waveguide antennas at Ka-band requires approximately 12 hours CPU time on a Cray Y-MP2 computer - excessive in terms of resource utilization. The calculations are done two mirrors at a time. The sampling theorem is used to reduce the number of points on the second surface obtained by performing a physical optics integration over the first surface. The number of points required by subsequent physical optics integrations is obtained by interpolation. Time improvements on the order of 2 to 4 were obtained for typical scattering pairs. RP CRAMER, PW (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 2 Z9 2 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 1994 VL 30 IS 5 BP 3156 EP 3159 DI 10.1109/20.312607 PN 2 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA PD542 UT WOS:A1994PD54200075 ER PT J AU GREENSPAN, H GOODMAN, R CHELLAPPA, R ANDERSON, CH AF GREENSPAN, H GOODMAN, R CHELLAPPA, R ANDERSON, CH TI LEARNING TEXTURE-DISCRIMINATION RULES IN A MULTIRESOLUTION SYSTEM SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article ID FILTERS AB We describe a texture analysis system in which informative discrimination rules are learned from a multiresolution representation of the textured input. The system incorporates unsupervised and supervised learning via statistical machine learning and rule-based neural networks, respectively. The textured input is represented in the frequency-orientation space via a log-Gabor pyramidal decomposition. In the unsupervised learning stage a statistical clustering scheme is used for the quantization of the feature-vector attributes. A supervised stage follows in which labeling of the textured map is achieved using a rule-based network. Simulation results for the texture classification task are given. An application of the system to real-world problems is demonstrated. C1 UNIV MARYLAND,INST ADV COMP STUDIES,DEPT ELECT ENGN,COLLEGE PK,MD 20742. UNIV MARYLAND,CTR AUTOMAT RES,COLLEGE PK,MD 20742. JET PROP LAB,PASADENA,CA 91109. RP GREENSPAN, H (reprint author), CALTECH,DEPT ELECT ENGN,PASADENA,CA 91125, USA. NR 18 TC 28 Z9 29 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0162-8828 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD SEP PY 1994 VL 16 IS 9 BP 894 EP 901 DI 10.1109/34.310685 PG 8 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PE802 UT WOS:A1994PE80200005 ER PT J AU SILVESTER, JP GENUARDI, MT KLINGBIEL, PH AF SILVESTER, JP GENUARDI, MT KLINGBIEL, PH TI MACHINE-AIDED INDEXING AT NASA SO INFORMATION PROCESSING & MANAGEMENT LA English DT Article AB This report describes the NASA Lexical Dictionary (NLD), a machine-aided indexing system used online at the National Aeronautics and Space Administration's Center for AeroSpace Information (CASI). This system automatically suggests a set of candidate terms from NASA's controlled vocabulary for any designated natural language text input. The system is comprised of a text processor that is based on the computational, nonsyntactic analysis of input text and an extensive knowledge base that serves to recognize and translate text-extracted concepts. The functions of the various NLD system components are described in detail, and production and quality benefits resulting from the implementation of machine-aided indexing at CASI are discussed. RP SILVESTER, JP (reprint author), NASA,CASI,800 ELKRIDGE LANDING RD,LINTHICUM HTS,MD 21090, USA. RI Genuardi, Michael/F-8784-2016 OI Genuardi, Michael/0000-0002-3348-393X NR 12 TC 6 Z9 6 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0306-4573 J9 INFORM PROCESS MANAG JI Inf. Process. Manage. PD SEP-OCT PY 1994 VL 30 IS 5 BP 631 EP 645 DI 10.1016/0306-4573(94)90075-2 PG 15 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA PC477 UT WOS:A1994PC47700004 ER PT J AU SONG, YD ANDERSON, JN LAI, HY AF SONG, YD ANDERSON, JN LAI, HY TI ROBUST-CONTROL OF MULTIROBOT SYSTEMS - THE GENERALIZED ENERGY ACCUMULATION APPROACH SO INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL LA English DT Article DE MULTIROBOT SYSTEMS; UNKNOWN PAYLOADS; ROBUST CONTROL; ADAPTIVE CONTROL; FORCE CONSTRAINTS ID MANIPULATORS; DYNAMICS; MOTION; ARMS AB This paper is concerned with the control problem of a multi-robot system handling a common payload with unknown mass properties. Force constraints at the grasp points are considered. Robust control schemes are proposed to cope with the model uncertainty and achieve asymptotic path tracking. To deal with the force constraints, a strategy for optimally sharing the task is suggested. This strategy basically consists of two steps. The first is to detect the roots that need help and the second to arrange for help. It is shown that the overall system is robust to uncertain payload parameters, and satisfies the force constraints. C1 N CAROLINA AGR & TECH STATE UNIV,DEPT ELECT ENGN,GREENSBORO,NC 27411. TENNESSEE TECHNOL UNIV,CTR MFG RES,COOKEVILLE,TN 38505. N CAROLINA AGR & TECH STATE UNIV,NASA,CTR AEROSP RES,GREENSBORO,NC 27411. RI Song, Yong-Duan/A-2730-2015 NR 35 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1049-8923 J9 INT J ROBUST NONLIN JI Int. J. Robust Nonlinear Control PD SEP-OCT PY 1994 VL 4 IS 5 BP 673 EP 696 DI 10.1002/rnc.4590040504 PG 24 WC Automation & Control Systems; Engineering, Electrical & Electronic; Mathematics, Applied SC Automation & Control Systems; Engineering; Mathematics GA PH447 UT WOS:A1994PH44700003 ER PT J AU SRIDHARAN, S ZEGGANE, M STARNES, JH AF SRIDHARAN, S ZEGGANE, M STARNES, JH TI MODE INTERACTION ANALYSIS OF STIFFENED SHELLS USING LOCALLY BUCKLED ELEMENTS SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article ID COMPOSITE CYLINDRICAL-SHELLS; POSTBUCKLING ANALYSIS; FINITE STRIPS AB A novel methodology for the analysis of local and overall instabilities in stiffened plates and shells is proposed. The method consists of embedding the local buckling deformation-the buckling mode together with the associated second order fields-in an appropriate shell element. The local buckling deformation is controlled by a relatively small number of degrees of freedom which also allow for amplitude modulation. Examples of stringer-stiffened plates and shells subjected to axial compression are presented. Excellent agreement is found to exist between the results given by the method and those obtained from full blown nonlinear analysis and experiments. It is shown that the proposed technique offers a simple and considerably less expensive approach to mode interaction problems than conventional nonlinear finite element analysis. Imperfection-sensitivity under coincident buckling of axially compressed stringer-stiffened cylindrical shells is explored and it is shown that there can be an erosion of 50% of the load carrying capacity under imperfections of the kind unavoidable in practice. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SRIDHARAN, S (reprint author), WASHINGTON UNIV,DEPT CIVIL ENGN,ST LOUIS,MO 63130, USA. NR 19 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD SEP PY 1994 VL 31 IS 17 BP 2347 EP 2366 DI 10.1016/0020-7683(94)90156-2 PG 20 WC Mechanics SC Mechanics GA PC504 UT WOS:A1994PC50400004 ER PT J AU PREISSER, JS BROOKS, TF MARTIN, RM AF PREISSER, JS BROOKS, TF MARTIN, RM TI RECENT STUDIES OF ROTORCRAFT BLADE-VORTEX INTERACTION NOISE SO JOURNAL OF AIRCRAFT LA English DT Article AB Recent results are presented from several research efforts aimed at the understanding of rotorcraft blade-vortex interaction (BVI) in terms of the noise generation, directivity, and control. The results are based on work performed by NASA Langley Research Center researchers, both alone and in collaboration with other research organizations. Based on analysis of a simplified physical model, the critical parameters controlling BVI noise generation have been identified. The detailed mapping of the acoustic radiation field of a model rotor in a wind tunnel has revealed the extreme sensitivity of directivity to rotor advance ratio and disk attitude. The control and reduction of BVI noise through the use of higher harmonic pitch control is discussed. RP PREISSER, JS (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1009 EP 1015 DI 10.2514/3.46603 PG 7 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300001 ER PT J AU HAMORY, PJ MURRAY, JE AF HAMORY, PJ MURRAY, JE TI FLIGHT EXPERIENCE WITH LIGHTWEIGHT, LOW-POWER MINIATURIZED INSTRUMENTATION SYSTEMS SO JOURNAL OF AIRCRAFT LA English DT Article AB Engineers at the NASA Dryden Flight Research Facility (NASA-Dryden) have conducted two flight research programs with lightweight, low-power miniaturized instrumentation systems built around commercial data loggers. One program quantified the performance of a radio-controlled model airplane. The other program was a laminar boundary-layer transition experiment on a manned sailplane. The purpose of this article is to report NASA-Dryden personnel's flight experience with the miniaturized instrumentation systems used on these two programs. This article will describe the data loggers, the sensors, and the hardware and software developed to complete the systems. It also describes how the systems were used and covers the challenges encountered to make them work. Examples of raw data and derived results will be shown as well. For some flight research applications where miniaturized instrumentation is a requirement, the authors conclude that commercially available data loggers and sensors are viable alternatives. In fact, the data loggers and sensors make it possible to gather research-quality data in a timely and cost-effective manner. RP HAMORY, PJ (reprint author), NASA,DRYDEN FLIGHT RES FACIL,EDWARDS AFB,CA 93523, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1016 EP 1021 DI 10.2514/3.46604 PG 6 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300002 ER PT J AU EKATERINARIS, JA SCHIFF, LB AF EKATERINARIS, JA SCHIFF, LB TI NUMERICAL-SIMULATION OF INCIDENCE AND SWEEP EFFECTS ON DELTA-WING VORTEX BREAKDOWN SO JOURNAL OF AIRCRAFT LA English DT Article AB The structure of the vortical flowfield over delta wings at high angles of attack was investigated. Three-dimensional Navier-Stokes numerical simulations were carried out to predict the complex leeward-side flowfield characteristics, including leading-edge separation, secondary separation, and vortex breakdown. Flows over a 75- and a 63-deg sweep delta wing with sharp leading edges were investigated and compared with available experimental data. The effect of variation of circumferential grid resolution in the vicinity of the wing leading edge on the accuracy of the solutions was addressed. Furthermore, the effect of turbulence modeling on the solutions was investigated. The effects of variation of angle of attack on the computed vortical flow structure for the 75-deg sweep delta wing were examined. At moderate angles of attack no vortex breakdown was observed. When a critical angle of attack was reached, bubble-type vortex breakdown was found. With further increase in angle of attack, a change from bubble-type breakdown to spiral-type vortex breakdown was predicted by the numerical solution. The effects of variation of sweep angle and freestream Mach number were addressed with the solutions on a 63-deg sweep delta wing. RP EKATERINARIS, JA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 5 Z9 8 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 SEP-OCT PY 1994 VL 31 IS 5 BP 1043 EP 1049 DI 10.2514/3.46608 PG 7 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300006 ER PT J AU SHIN, J BOND, TH AF SHIN, J BOND, TH TI REPEATABILITY OF ICE SHAPES IN THE NASA LEWIS ICING RESEARCH TUNNEL SO JOURNAL OF AIRCRAFT LA English DT Article AB Tests were conducted in the Icing Research Tunnel (IRT) at the NASA Lewis Research Center to document the current capability of the IRT, focused mainly on the repeatability of the ice shape over a range of icing conditions. Measurements of drag increase due to ice accretion were also made to document the repeatability of drag. The repeatability of the ice shape was very good at low temperatures, but only fair at near freezing temperatures. In general, drag data shows good repeatability. RP SHIN, J (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 3 Z9 5 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 1994 VL 31 IS 5 BP 1057 EP 1063 DI 10.2514/3.46610 PG 7 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300008 ER PT J AU WOODWARD, RP BOCK, LA HEIDELBERG, LJ HALL, DG AF WOODWARD, RP BOCK, LA HEIDELBERG, LJ HALL, DG TI MODEL DUCTED PROPULSOR NOISE CHARACTERISTICS AT TAKEOFF CONDITIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB A model Advanced Ducted Propulsor (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The model was designed and manufactured by Pratt & Whitney. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and inlet angles of attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe that identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 10-dB fundamental tone reduction was associated with the long inlet and 40-vane stator. The fundamental tone level was essentially unaffected by inlet angle of attack at rotor speeds of above 96% design. RP WOODWARD, RP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 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 SEP-OCT PY 1994 VL 31 IS 5 BP 1064 EP 1070 DI 10.2514/3.46611 PG 7 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300009 ER PT J AU DORR, DW MORALEZ, E MERRICK, VK AF DORR, DW MORALEZ, E MERRICK, VK TI SIMULATION AND FLIGHT TEST EVALUATION OF HEAD-UP-DISPLAY GUIDANCE FOR HARRIER APPROACH TRANSITIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB Position and speed guidance displays for STOVL aircraft curved, decelerating approaches to hover and vertical landing have been evaluated for their effectiveness in reducing pilot workload and improving performance. The NASA V/STOL Systems Research Aircraft, a modified YAV-8B Harrier prototype, was used to evaluate the displays in flight, whereas the NASA Ames Vertical Motion Simulator was used to extend the flight test results to instrument meteorological conditions (IMC) and to examine performance in various conditions of wind and turbulence. The simulation data showed close correlation with the flight test data, and both demonstrated the feasibility of the displays. With the exception of the hover task in zero visibility, which was level-3, average Cooper-Harper handling qualities ratings given during simulation were level-2 for both the approach task and the hover taks in all conditions. During flight tests in calm and clear conditions, the displays also gave rise to level-2 handling qualities ratings. Pilot opinion showed that the guidance displays would be useful in visual flight, especially at night, as well as in IMC. RP DORR, DW (reprint author), NASA,AMES RES CTR,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 1994 VL 31 IS 5 BP 1089 EP 1094 DI 10.2514/3.46615 PG 6 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300013 ER PT J AU COCKRELL, CE AF COCKRELL, CE TI INTERPRETATION OF WAVERIDER PERFORMANCE DATA USING COMPUTATIONAL FLUID-DYNAMICS SO JOURNAL OF AIRCRAFT LA English DT Article AB A computational study was conducted to better understand experimental results obtained from wind-tunnel tests of a Mach 4 conical-flow-derived waverider and a comparative reference configuration, which showed that the aerodynamic performance of the reference configuration was slightly better than that of the waverider. The computational results showed that the predicted surface pressure values and the integrated lift and drag coefficients were much lower for the reference model because the reference model bottom is an expansion surface. However, the lift-drag ratios for the reference model were higher due to a relatively low drag for a comparable amount of lift. The results also showed that the reference model exhibited the same shock attachment characteristics as the conical-flow-derived waverider, and is therefore also a waverider. The shock attachment characteristics gives the waverider a performance advantage over conventional hypersonic vehicles, and the results suggest that altering the bottom surface does not cause significant performance degradation. Flowfield solutions also show that the conical-flow waverider model has better propulsion/airframe integration characteristics than the reference configuration. The results also suggest that generating flowfields other than conical ones may be used to design waveriders with improved aerodynamic performance. RP COCKRELL, CE (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 0 TC 3 Z9 4 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1095 EP 1100 DI 10.2514/3.46616 PG 6 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300014 ER PT J AU SIM, AG MURRAY, JE NEUFELD, DC REED, RD AF SIM, AG MURRAY, JE NEUFELD, DC REED, RD TI DEVELOPMENT AND FLIGHT TEST OF A DEPLOYABLE PRECISION LANDING SYSTEM SO JOURNAL OF AIRCRAFT LA English DT Article AB A joint NASA Dryden Flight Research Facility and Johnson Space Center program was conducted to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space that included a precision landing. The feasibility of this system was studied using a flight model of a spacecraft in the generic shape of a flattened biconic that weighted approximately 150 lb and was flown under a commerically available, ram-air parachute. Key elements of the vehicle included the Global Positioning System guidance for navigation, flight control computer, ultrasonic sensing for terminal altitude, electronic compass, and onboard data recording. A flight test program was used to develop and refine the vehicle. This vehicle completed an autonomous flight from an altitude of 10,000 ft and a lateral offset of 1.7 miles that resulted in a precision flare and landing into the wind at a predetermined location. At times, the autonomous flight was conducted in the presence of winds approximately equal to vehicle airspeed. Several novel techniques for computing the winds postflight were evaluated. Future program objectives are also presented. RP SIM, AG (reprint author), NASA,DRYDEN FLIGHT RES FACIL,EDWARDS AFB,CA 93534, USA. NR 0 TC 6 Z9 8 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1101 EP 1108 DI 10.2514/3.46617 PG 8 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300015 ER PT J AU GILES, GL NORWOOD, K AF GILES, GL NORWOOD, K TI COUPLING EQUIVALENT PLATE AND FINITE-ELEMENT FORMULATIONS IN MULTIPLE-METHOD STRUCTURAL-ANALYSES SO JOURNAL OF AIRCRAFT LA English DT Article AB A coupled multiple-method analysis procedure for use late in conceptual design or early in preliminary design of aircraft structures is described. Using this method, aircraft wing structures are represented with equivalent plate models, and structural details such as engine/pylon structure, landing gear, or a ''stick'' model of a fuselage are represented with beam finite element models. These two analysis methods are implemented in an integrated multiple-method formulation that involves the assembly and solution of a combined set of linear equations. The corresponding solution vector contains coefficients of the polynomials that describe the deflection of the wing and also the components of translations and rotations at the joints of the beam members. Two alternative approaches for coupling the methods are investigated; one using transition finite elements and the other using Lagrange multipliers. The coupled formulation is applied to the static analysis and vibration analysis of a conceptual design model of a fighter aircraft. The results from the coupled method are compared with corresponding results from an analysis in which the entire model is composed of finite elements. RP GILES, GL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1189 EP 1196 DI 10.2514/3.46629 PG 8 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300028 ER PT J AU WOOD, RM BANKS, DW BAUER, SXS AF WOOD, RM BANKS, DW BAUER, SXS TI PASSIVE POROSITY WITH FREE AND FIXED SEPARATION ON A TANGENT-OGIVE FOREBODY SO JOURNAL OF AIRCRAFT LA English DT Note RP WOOD, RM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 1994 VL 31 IS 5 BP 1219 EP 1221 DI 10.2514/3.46635 PG 3 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300034 ER PT J AU ROSSOW, VJ AF ROSSOW, VJ TI EFFECT OF GROUND AND CEILING PLANES ON SHAPE OF ENERGIZED WAKES SO JOURNAL OF AIRCRAFT LA English DT Note RP ROSSOW, VJ (reprint author), NASA,AMES RES CTR,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 1994 VL 31 IS 5 BP 1227 EP 1231 DI 10.2514/3.46638 PG 5 WC Engineering, Aerospace SC Engineering GA PK523 UT WOS:A1994PK52300038 ER PT J AU NEMETH, MP AF NEMETH, MP TI NONDIMENSIONAL PARAMETERS AND EQUATIONS FOR BUCKLING OF ANISOTROPIC SHALLOW SHELLS SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article AB A procedure for deriving nondimensional parameters and equations for bifurcation buckling of anisotropic shallow shells subjected to combined loads is presented. First, The Donnell-Mushtari-Vlasov equations governing Buckling of symmetrically laminated doubly curved thin elastic shallow shells are presented. Then, the rationale used to perform the nondimensionalization of the buckling equations is presented, and fundamental parameters are identified that represent measures of the shell orthotropy and anisotropy. In addition, nondimensional curvature parameters are identified that are analogues of the well-known Batdorf Z parameter for isotropic shells, and analogues of Dunnell's and Bardorf's shell buckling equations are presented. Selected results are presented for shear buckling of balanced symmetric laminated shells that illustrate the usefulness of the nondimensional parameters. RP NEMETH, MP (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23681, USA. NR 11 TC 17 Z9 17 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD SEP PY 1994 VL 61 IS 3 BP 664 EP 669 DI 10.1115/1.2901511 PG 6 WC Mechanics SC Mechanics GA PJ704 UT WOS:A1994PJ70400024 ER PT J AU BELL, TL SUHASINI, R AF BELL, TL SUHASINI, R TI PRINCIPAL MODES OF VARIATION OF RAIN-RATE PROBABILITY-DISTRIBUTIONS SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID THRESHOLD METHOD; SATELLITE-OBSERVATIONS; PRECIPITATION AB Radar or satellite observations of an area generate sequences of rain-rate maps. From a gridded map a histogram of rain rates can be obtained representing the relative areas occupied by rain rates of various strengths. The histograms vary with time as precipitating systems in the area evolve and decay and amounts of convective and stratiform rain in the area change. A method of decomposing the histograms into linear combinations of a few empirical distributions with time-dependent coefficients is developed, using principal component analysis as a starting point. When applied to a tropical Atlantic dataset (GATE), two distributions emerge naturally from the analysis, resembling stratiform and convective rain-rate distributions in that they peak at low and high rain rates, respectively. The two ''modes'' have different timescales and only the high-rain-rate mode has a statistically significant diurnal cycle. The ability of just two modes to describe rain variability over an area can explain why methods of estimating area-averaged rain rate from the area covered by rain rates above a certain threshold are so successful. C1 PHYS RES LAB,NAVRANGPURA,INDIA. RP BELL, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI Bell, Thomas/G-5425-2012 NR 17 TC 15 Z9 15 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD SEP PY 1994 VL 33 IS 9 BP 1067 EP 1078 DI 10.1175/1520-0450(1994)033<1067:PMOVOR>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PD382 UT WOS:A1994PD38200003 ER PT J AU PRADHAN, AD PARTRIDGE, H BAUSCHLICHER, CW AF PRADHAN, AD PARTRIDGE, H BAUSCHLICHER, CW TI THE DISSOCIATION-ENERGY OF CN AND C-2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; BASIS-SETS; HEAT; C2 AB The dissociation energies of CN and C-2 are determined with multireference configuration-interaction calculations utilizing very large Gaussian basis sets. Valence level one-particle errors, such as basis set incompleteness and basis set superposition error, are essentially eliminated by extrapolation. The errors in the correlation, or n particle, treatment are considered in detail. The effect of 1s correlation is computed using the averaged coupled-pair functional approach. Our best estimate for C-2 is in very good agreement with the recent experimental result by Urdahl et al. Our best D-0 value for CN is 7.72+/-0.04 eV. This is larger than previous theoretical values and in good agreement with the recent experimental result (7.738+/-0.02 eV) of Huang et al. The origin of the differences between the current D-0 and our previous theoretical value is discussed. RP PRADHAN, AD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 29 TC 64 Z9 64 U1 1 U2 7 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 1994 VL 101 IS 5 BP 3857 EP 3861 DI 10.1063/1.467503 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PE110 UT WOS:A1994PE11000049 ER PT J AU DRUYAN, LM HASTENRATH, S AF DRUYAN, LM HASTENRATH, S TI TROPICAL IMPACTS OF SST FORCING - A CASE-STUDY FOR 1987 VERSUS 1988 SO JOURNAL OF CLIMATE LA English DT Article ID SUMMER MONSOONS AB The response of the NASA/Goddard Institute for Space Studies GCM to large tropical sea surface temperature (SST) anomalies is investigated by evaluating model simulations of the particularly contrasting summer monsoon seasons 1987 and 1988. These years are representative of the warm and cold phases, respectively, of a recent ENSO event. An ensemble averaging the results of three simulations was considered for each season, using monthly mean observed SST anomalies for June-August 1987 and 1988 as lower boundary forcing. Consistent with the ECMWF-analyzed winds, the simulations based on 1988 as compared to 1987 SST exhibit stronger upper-tropospheric irrotational circulation between the monsoon regions and the Southern Hemispheric sub-tropical anticyclones, a stronger Pacific Walker cell and a weaker subtropical westerly jet over the South Pacific. In the same vein, the modeled precipitation, indicating a more northerly position of the Pacific ITCZ in 1988 compared with 1987, is supported by satellite observations of outgoing longwave radiation and highly reflective clouds. C1 COLUMBIA UNIV,NEW YORK,NY 10027. UNIV WISCONSIN,DEPT ATMOSPHER & OCEAN SCI,MADISON,WI 53706. RP DRUYAN, LM (reprint author), COLUMBIA UNIV,NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 13 TC 11 Z9 11 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 SEP PY 1994 VL 7 IS 9 BP 1316 EP 1323 DI 10.1175/1520-0442(1994)007<1316:TIOSFA>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PK473 UT WOS:A1994PK47300002 ER PT J AU MILLER, RL DELGENIO, AD AF MILLER, RL DELGENIO, AD TI TROPICAL CLOUD FEEDBACKS AND NATURAL VARIABILITY OF CLIMATE SO JOURNAL OF CLIMATE LA English DT Article ID TOP ENTRAINMENT INSTABILITY; CIRCULATION MODEL; ATMOSPHERE AB Simulations of natural variability by two GCMs are examined. One GCM is a sector model, allowing relatively rapid integration without simplification of the model physics. which would potentially exclude mechanisms of variability. Two mechanisms are found in which tropical surface temperature and SST vary on interannual and longer timescales. Both are related to changes in cloud cover that modulate SST through the surface radiative flux. Over the equatorial ocean, SST and surface temperature vary on an interannual timescale, which is determined by the magnitude of the associated cloud cover anomalies. Over the subtropical ocean, variations in low cloud cover drive SST variations. In the sector model, the variability has no preferred timescale, but instead is characterized by a ''red'' spectrum with increasing power at longer periods. In the terrestrial GCM, SST variability associated with low cloud anomalies has a decadal timescale and is the dominant form of global temperature variability. Both GCMs are coupled to a mixed layer ocean model, where dynamical heat transports are prescribed, thus filtering out ENSO and thermohaline circulation variability. The occurrence of variability in the absence of dynamical ocean feedbacks suggests that climatic variability on long timescales can arise from atmospheric processes alone. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY. RI Miller, Ron/E-1902-2012; Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 28 TC 11 Z9 11 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 SEP PY 1994 VL 7 IS 9 BP 1388 EP 1402 DI 10.1175/1520-0442(1994)007<1388:TCFANV>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PK473 UT WOS:A1994PK47300007 ER PT J AU PALOSZ, W SZOFRAN, FR LEHOCZKY, SL AF PALOSZ, W SZOFRAN, FR LEHOCZKY, SL TI THE EFFECT OF HEAT-TREATMENT ON THE MAGNITUDE AND COMPOSITION OF RESIDUAL-GAS IN SEALED SILICA GLASS AMPOULES SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID VITREOUS SILICA; HYDROGEN AB The residual gas pressure and composition in sealed silica glass ampoules as a function of different treatment procedures has been investigated. The dependence of the residual gas on the outgassing and annealing parameters has been determined. The effects of the fused silica brand, of the ampoule fabrication, and of post-outgassing procedures have been evaluated. RP NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. NR 13 TC 12 Z9 12 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 EI 1873-5002 J9 J CRYST GROWTH JI J. Cryst. Growth PD SEP PY 1994 VL 142 IS 1-2 BP 215 EP 224 DI 10.1016/0022-0248(94)90290-9 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA PE509 UT WOS:A1994PE50900029 ER PT J AU RAY, A WU, MK CARPINO, M LORENZO, CF AF RAY, A WU, MK CARPINO, M LORENZO, CF TI DAMAGE-MITIGATING CONTROL OF MECHANICAL SYSTEMS .1. CONCEPTUAL DEVELOPMENT AND MODEL FORMULATION SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article ID CRACK-GROWTH; FATIGUE AB A major goal in the control of complex mechanical systems such as advanced aircraft, spacecraft, and power plants is to achieve high performance with increased reliability availability, component durability, and maintainability. The current state-of-the-art of control systems synthesis focuses on improving performance and diagnostic capabilities under constraints that often do not adequately represent the dynamic properties of the materials. The reason is that the traditional design is based upon the assumption of conventional materials with invariant characteristics. In view of high performance requirements and availability of improved materials, the lack of appropriate knowledge about the properties of these materials will lead to either less than achievable performance due to overly conservative design, or over-straining of the structure leading to unexpected failures and drastic reduction of the service life. The key idea of the research reported in this paper is that a significant improvement in service life can be achieved by a small reduction in the system dynamic performance. This requires augmentation of the current system-theoretic techniques for synthesis of decision and control laws with governing equations and inequality constraints that would model the properties of the materials for the purpose of damage representation and failure prognosis. The major challenge in this research is to characterize the damage generation process in a continuous-time setting, and then utilize this information for synthesizing algorithms of robust control diagnostics, and risk assessment in complex mechanical systems. Damage mitigation for control of mechanical systems is reported in the two-part paper. The concept of damage mitigation is introduced and a continuous-time model of fatigue damage dynamics is formulated in this paper which is the first part. The second part which is a companion paper presents the synthesis of the open-loop control policy and the results of simulation experiments for transient operations of a reusable rocket engine. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAY, A (reprint author), PENN STATE UNIV,DEPT MECH ENGN,UNIVERSITY PK,PA 16802, USA. NR 33 TC 30 Z9 31 U1 2 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1994 VL 116 IS 3 BP 437 EP 447 DI 10.1115/1.2899239 PG 11 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA PJ922 UT WOS:A1994PJ92200014 ER PT J AU RAY, A WU, MK CARPINO, M LORENZO, CF AF RAY, A WU, MK CARPINO, M LORENZO, CF TI DAMAGE-MITIGATING CONTROL OF MECHANICAL SYSTEMS .2. FORMULATION OF AN OPTIMAL POLICY AND SIMULATION SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article ID SPACE AB The objective of damage-mitigating control introduced in the first part of this two-part paper is to achieve high performance without overstraining the mechanical structures. The major benefit is an increase in the functional life of critical plant components along with enhanced safety, operational reliability, and availability Specifically, a methodology for modeling fatigue damage has been developed as an augmentation to control and diagnostics of complex dynamic processes such as advanced aircraft, spacecraft, and power plants. In this paper which is the second part, an optimal control policy is formulated via nonlinear programming under specified constraints of the damage rate and accumulated damage. The results of simulation experiments for upthrust transient operations of a reusable rocket engine are presented to demonstrate efficacy of the damage-mitigating control concept. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP RAY, A (reprint author), PENN STATE UNIV,DEPT MECH ENGN,UNIVERSITY PK,PA 16802, USA. NR 18 TC 7 Z9 8 U1 1 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1994 VL 116 IS 3 BP 448 EP 455 DI 10.1115/1.2899240 PG 8 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA PJ922 UT WOS:A1994PJ92200015 ER PT J AU EKE, FO MACALA, GA MAN, GK AF EKE, FO MACALA, GA MAN, GK TI IMPACT OF FLEXIBILITY ON THE CLOCK CONTROLLER OF THE GALILEO SPACECRAFT SO JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME LA English DT Article AB This paper presents a study of the effects of structural flexibility on one of the control loops that constitute the Attitude and Articulation Control Subsystem of the Galileo Spacecraft. Both stability analysis and time domain simulation studies are discussed. Results obtained indicate that the control loop of interest-the Clock Controller-will interact stably with the spacecraft structure as long as the spacecraft scan platform boresight points at least 30 deg away from the spacecraft spin axis (poles). Flexibility effects become more and more pronounced with proximity of the bore-sight to the poles as several structural modes become excitable to resonance. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP EKE, FO (reprint author), UNIV CALIF DAVIS,DEPT AERONAUT & MECH ENGN,DAVIS,CA 95616, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-0434 J9 J DYN SYST-T ASME JI J. Dyn. Syst. Meas. Control-Trans. ASME PD SEP PY 1994 VL 116 IS 3 BP 521 EP 528 DI 10.1115/1.2899247 PG 8 WC Automation & Control Systems; Instruments & Instrumentation SC Automation & Control Systems; Instruments & Instrumentation GA PJ922 UT WOS:A1994PJ92200022 ER PT J AU FOOTE, MC VASQUEZ, RP JONES, BB HUNT, BD BARNER, JB AF FOOTE, MC VASQUEZ, RP JONES, BB HUNT, BD BARNER, JB TI COMPOSITION OF PULSED-LASER-DEPOSITED Y-BA-CU-O AND BA-K-BI-O THIN-FILMS SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article; Proceedings Paper CT Symposium on Synthesis and Processing of Electronic and Photonic Materials CY FEB, 1993 CL DENVER, CO SP MINERALS MET & MAT SOC DE COMPOSITION VARIATION; LASER ABLATION; SUPERCONDUCTOR; THIN FILMS ID EVAPORATION TECHNIQUE; THEORETICAL-MODEL; OXYGEN-PRESSURE; YBA2CU3O7-DELTA; PARAMETERS; ABLATION; TARGET AB The composition of pulsed-laser-deposited Y-Ba-Cu-O and Ba-K-Bi-O thin films is shown to be strongly affected by target conditioning, gas pressure, and target-substrate distance. For both compounds, ablation from a freshly sanded target surface results in films with an excess of the more volatile elements. The concentration of these volatile elements in the films decreases until the system reaches a steady state after sufficient ablation from the target. Y-Ba-Cu-O film composition is also affected by oxygen pressure and target-substrate distance. Increasing pressure or distance results in relative copper and barium depletion in the central region of deposition, presumably due to differences in the efficacy of oxygen in scattering the different elements. This relationship between pressure, distance, and composition is shown to be significant for the growth of optimal superconducting Y-Ba-Cu-O thin films. The composition of Ba-K-Bi-O is also affected strongly by background gas pressure. Ba-K-Bi-O deposited in vacuum is potassium deficient in the film center. A background argon pressure of 1 Torr, however, increases the potassium concentration and results in films with uniform composition over a broad area. We argue that this effect is significant in explaining a successful growth method for superconducting Ba-K-Bi-O films. RP FOOTE, MC (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 14 TC 4 Z9 4 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD SEP PY 1994 VL 23 IS 9 BP 849 EP 853 DI 10.1007/BF02655354 PG 5 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA PF342 UT WOS:A1994PF34200003 ER PT J AU DEWAR, H BRILL, RW OLSON, KR AF DEWAR, H BRILL, RW OLSON, KR TI SECONDARY CIRCULATION OF THE VASCULAR HEAT-EXCHANGERS IN SKIPJACK TUNA, KATSUWONUS-PELAMIS SO JOURNAL OF EXPERIMENTAL ZOOLOGY LA English DT Note ID FISH AB Vascular corrosion replicas of the counter current heat exchanger microcirculation in skipjack tuna, Katsuwonus pelamis, were examined by scanning electron microscopy. Small-bore (7-10 mu m diameter) vessels, with characteristics typical of those associated with the secondary circulation, were abundant in the central and lateral heat exchangers. These vessels arise from the large-bore (70 mu m diameter) retial arterioles and, after a tortuous path, anastomose repeatedly to form 50-200 mu m diameter secondary collecting vessels which ultimately exit from either pole of the rete. (C) 1994 Wiley-Liss, Inc. C1 NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU,HI 96822. UNIV NOTRE DAME,INDIANA UNIV,SCH MED,S BEND CTR MED EDUC,NOTRE DAME,IN 46556. RP DEWAR, H (reprint author), UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,CTR BIOTECHNOL & BIOMED,LA JOLLA,CA 92093, USA. NR 17 TC 6 Z9 6 U1 0 U2 1 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0022-104X J9 J EXP ZOOL JI J. Exp. Zool. PD SEP 1 PY 1994 VL 269 IS 6 BP 566 EP 570 DI 10.1002/jez.1402690610 PG 5 WC Zoology SC Zoology GA PE231 UT WOS:A1994PE23100009 ER PT J AU RAMAN, G RICE, EJ CORNELIUS, DM AF RAMAN, G RICE, EJ CORNELIUS, DM TI EVALUATION OF FLIP-FLOP JET NOZZLES FOR USE AS PRACTICAL EXCITATION DEVICES SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article AB This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above-mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. RP RAMAN, G (reprint author), NYMA INC,NASA,LEWIS RES CTR GRP,BROOKPARK,OH 44142, USA. NR 24 TC 20 Z9 21 U1 0 U2 4 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD SEP PY 1994 VL 116 IS 3 BP 508 EP 515 DI 10.1115/1.2910306 PG 8 WC Engineering, Mechanical SC Engineering GA PK459 UT WOS:A1994PK45900020 ER PT J AU STERN, DP AF STERN, DP TI THE ART OF MAPPING THE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID FIELD-ALIGNED CURRENTS; ANISOTROPIC MAGNETOHYDROSTATIC PLASMA; GEOMAGNETIC NEUTRAL SHEET; WIND DYNAMIC PRESSURE; MAGNETIC-FIELD; BIRKELAND CURRENTS; ELECTRIC-FIELDS; RING CURRENT; EQUATORIAL MAGNETOTAIL; QUANTITATIVE MODELS AB A comprehensive review is presented of the mathematical methods used to represent magnetic fields in the Earth's magnetosphere, of the way existing data-based models use these methods and of the associated problems and concepts. The magnetic field has five main components: the internal field, the magnetopause, the ring current, the tail and Birkeland currents. Methods of representing separately each of these are discussed, as is the deformation of magnetic fields; Appendix B traces the connection between deformations and the Cauchy integral. A summary section lists the uses of data-based models and their likely future evolution, and Appendix A supplements the text with a set of problems. RP STERN, DP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,MAIL CODE 695,GREENBELT,MD 20771, USA. NR 155 TC 37 Z9 37 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17169 EP 17198 DI 10.1029/94JA01239 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500001 ER PT J AU ROSENBAUER, H VERIGIN, MI KOTOVA, GA LIVI, S REMIZOV, AP RIEDLER, W SCHWINGENSCHUH, K SHUTTE, NM SLAVIN, JA SZEGO, K TATRALLYAY, M ZHANG, TL AF ROSENBAUER, H VERIGIN, MI KOTOVA, GA LIVI, S REMIZOV, AP RIEDLER, W SCHWINGENSCHUH, K SHUTTE, NM SLAVIN, JA SZEGO, K TATRALLYAY, M ZHANG, TL TI THE RELATIONSHIP BETWEEN THE MAGNETIC-FIELD IN THE MARTIAN MAGNETOTAIL AND UPSTREAM SOLAR-WIND PARAMETERS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BOW SHOCK; MARS; MAGNETOSPHERE; ORIGIN; IONS AB Magnetic field data measured by the MAGMA instrument in the Martian magnetotail lobes are compared with the ram pressure of the upstream solar wind observed by the TAUS instrument in the circular orbits of the Phobos 2 spacecraft. High correlation was found between the magnetic field intensity in the Martian magnetotail lobes and the solar wind ram pressure. From this relationship the average flaring angle of the Martian magnetotail was determined as similar to 13 degrees, and the average magnetosonic Mach number was estimated as similar to 5. The observed relationship between the Martian magnetotail magnetic field intensity and the solar wind magnetic field reflects the correlation of the solar wind magnetic field to the ram pressure providing a value of similar to 7 for the average Alfvenic Mach number. The flaring angle obtained for the Martian magnetotail was found to be an intermediate value between the flaring angle of the magnetotail of the Earth and that of Venus at comparable distances. C1 MOSCOW SPACE RES INST,MOSCOW 117810,RUSSIA. OAW,INST WELTRAUMFORSCH,A-8010 GRAZ,AUSTRIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. KFKI,PARTICLE & NUCL PHYS RES INST,H-1525 BUDAPEST,HUNGARY. RP ROSENBAUER, H (reprint author), MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 24 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17199 EP 17204 DI 10.1029/94JA00946 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500002 ER PT J AU DESCH, MD FARRELL, WM KAISER, ML AF DESCH, MD FARRELL, WM KAISER, ML TI ASYMMETRIES IN THE IO PLASMA TORUS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETOSPHERE; JUPITER; WAVES AB Using Ulysses radio wave data taken during the 1992 Jupiter encounter, we conclude that there are significant large and small spatial scale azimuthal asymmetries at high latitudes in the Io plasma torus. During a period of time near perijove when the spacecraft motion was predominantly in the azimuthal direction and was relatively fixed in both latitude and radial distance, inferred electron densities depart significantly from the common assumption of longitudinal symmetry. Specifically, electron plasma concentrations near 0 degrees system III longitude (and 0400 LT) are greater than those near 180 degrees (and 0000 LT). Superposed on this large-scale variation are regularly spaced density depletions, 30-50% in magnitude, and having a spatial periodicity of about 17 degrees. Some of these depletions may drive various known radio and plasma wave sources by means of large B parallel electric potentials. The observations are compared with recent models and with the in situ Voyager observations. RP DESCH, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 20 TC 14 Z9 14 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17205 EP 17210 DI 10.1029/94JA01615 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500003 ER PT J AU HUANG, TS BIRMINGHAM, TJ AF HUANG, TS BIRMINGHAM, TJ TI KINETIC AND THERMODYNAMIC PROPERTIES OF A CONVECTING PLASMA IN A 2-DIMENSIONAL DIPOLE FIELD SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FINITE-WIDTH MAGNETOTAIL; MODELS AB Charged particle guiding center motion is considered in the magnetic field of a two-dimensional (''line'') dipole on which is superimposed a small, static, perpendicular electric field. The parallel equation of motion is that of a simple harmonic oscillator for cos theta, the cosine of magnetic colatitude theta. Equations for the perpendicular electric and magnetic drifts are derived as well as their bounce-averaged forms. The latter are solved to yield a bounce-averaged guiding center trajectory, which is the same as that obtained from conservation of magnetic moment mu, longitudinal invariant J, and total (kinetic plus electrostatic) energy K. The algebraic simplicity of the trajectory equations is also manifest in the forms of the invariants. An interesting result is that guiding centers drift in such a way that they preserve the values of their equatorial pitch angles and (equivalently) mirror latitudes. The most general Maxwellian form of the equilibrium one-particle distribution function f is constructed from the invariants, and spatially varying density and pressure moments, parallel and perpendicular to the magnetic field, are identified. Much of the paper deals with the more restricted problem in which f is specified as a bi-Maxwellian over a straight line of finite length in the equatorial plane of the dipole and perpendicular to field lines. This might be thought of as specifying a cross-tail ion injection source; our formalism then describes the subsequent spatial development. The distribution away from the source is a scaled bi-Maxwellian but one that is cut off at large and small kinetic energies, which depend on position. Density and pressure components are reduced from the values they would have if the total content of individual flux tubes convected intact. The equatorial and meridional variations of density and pressure components are examined and compared systematically for the isotropic and highly anisotropic situations. There appears to be little qualitative difference due to anisotropy. An anisotropy measure is defined, and its spatial variation determined as a signature of possible MHD instability. Extreme values are found, larger than at the source, but the plasma beta in such regions is probably so low as to render the effect inconsequential energetically. Finally, the possible consequence of ''nonadiabatic'' pressure profiles on electrostatic interchanges is considered, and a boundary delineating stabilizing and destabilizing regions determined. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP HUANG, TS (reprint author), PRAIRIE VIEW A&M UNIV,DEPT PHYS,PRAIRIE VIEW,TX 77446, USA. NR 22 TC 7 Z9 7 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17295 EP 17307 DI 10.1029/94JA01452 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500011 ER PT J AU SANDHOLT, PE FARRUGIA, CJ BURLAGA, LF HOLTET, JA MOEN, J LYBEKK, B JACOBSEN, B OPSVIK, D EGELAND, A LEPPING, R LAZARUS, AJ HANSEN, T BREKKE, A FRIISCHRISTENSEN, E AF SANDHOLT, PE FARRUGIA, CJ BURLAGA, LF HOLTET, JA MOEN, J LYBEKK, B JACOBSEN, B OPSVIK, D EGELAND, A LEPPING, R LAZARUS, AJ HANSEN, T BREKKE, A FRIISCHRISTENSEN, E TI CUSP/CLEFT AURORAL ACTIVITY IN RELATION TO SOLAR-WIND DYNAMIC PRESSURE, INTERPLANETARY MAGNETIC-FIELD B-Z AND B-Y SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LATITUDE BOUNDARY-LAYER; FLUX-TRANSFER EVENTS; POLAR-CAP BOUNDARY; DAYSIDE IONOSPHERE; PARTICLE-PRECIPITATION; BIRKELAND CURRENTS; LARGE-SCALE; CUSP; MAGNETOSPHERE; MAGNETOSHEATH AB Continuous optical observations of cusp/cleft auroral activities within approximate to 09-15 MLT and 70-76 degrees magnetic latitude are studied in relation to changes in solar wind dynamic pressure and interplanetary magnetic field (IMF) variability. The observed latitudinal movements of the cusp/cleft aurora in response to WIF B, changes may be explained as an effect of a variable magnetic field intensity in the outer dayside magnetosphere associated with the changing intensity of region 1 field-aligned currents and associated closure currents. Ground magnetic signatures related to such currents were observed in the present case (January 10, 1993). Strong, isolated enhancements in solar wind dynamic pressure (Delta p/p greater than or equal to 0.5) gave rise to equatorward shifts of the cusp/cleft aurora, characteristic auroral transients, and distinct ground magnetic signatures of enhanced convection at cleft latitudes. A sequence of auroral events of approximate to 5-10 min recurrence time, moving eastward along the poleward boundary of the persistent cusp/cleft aurora in the approximate to 10-14 MLT sector, during negative WIF B, and B, conditions, were found to be correlated with brief pulses in solar wind dynamic pressure (0.1 < Delta p/p < 0.5). Simultaneous photometer observations from Ny Alesund, Svalbard, and Danmarkshavn, Greenland, show that the events often appeared on the prenoon side (approximate to 10-12 MLT), before moving into the postnoon sector in the case we study here, when IMF B-y < 0. In other cases, similar auroral event sequences have been observed to move westward in the prenoon sector, during intervals of positive B-y. Thus a strong prenoon/postnoon asymmetry of event occurence and motion pattern related to the IMF B-y polarity is observed. We find that this category of auroral event sequence is stimulated bursts of electron precipitation that originate from magnetosheath plasma that has accessed the dayside magnetosphere in the noon or near-noon sector, possibly at high latitudes, partly governed by the IMF orientation as well as by solar wind dynamic pressure pulses. C1 MIT,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20077. UNIV TROMSO,AURORAL OBSERV,N-9037 TROMSO,NORWAY. DANISH METEOROL INST,COPENHAGEN,DENMARK. RP SANDHOLT, PE (reprint author), UNIV OSLO,DEPT PHYS,POB 1048 BLINDERN,N-0316 OSLO,NORWAY. NR 44 TC 59 Z9 60 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 SEP 1 PY 1994 VL 99 IS A9 BP 17323 EP 17342 DI 10.1029/94JA00679 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500013 ER PT J AU FUSELIER, SA MENDE, SB GELLER, SP MILLER, M HOFFMAN, RA WYGANT, JR PONGRATZ, M MEREDITH, NP ANDERSON, RR AF FUSELIER, SA MENDE, SB GELLER, SP MILLER, M HOFFMAN, RA WYGANT, JR PONGRATZ, M MEREDITH, NP ANDERSON, RR TI DYNAMICS OF THE CRRES BARIUM RELEASES IN THE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB The Combined Release and Radiation Effects satellite (CRRES) G-2, G-3, and G-4 ionized and neutral barium cloud positions are triangulated from ground-based optical data; From the time history of the ionized cloud motion perpendicular to the magnetic field, the late time coupling of the ionized cloud with the collisionless ambient plasma in the magnetosphere is investigated for each of the releases. The coupling of the ionized clouds with the ambient medium is qualitatively consistent with predictions from theory in that the coupling time increases with increasing distance from the Earth. Quantitative comparison with simple theory for the coupling time also yields reasonable agreement. Other effects not predicted by the theory are discussed in the context of the observations. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. UCL, ATMOSPHER PHYS LAB, LONDON W1P 7PP, ENGLAND. UNIV IOWA, DEPT PHYS & ASTRON, IOWA CITY, IA 52242 USA. RP FUSELIER, SA (reprint author), LOCKHEED PALO ALTO RES LABS, DEPT 9120, BLDG 255, 3251 HANOVER ST, PALO ALTO, CA 94304 USA. NR 9 TC 3 Z9 3 U1 1 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 SEP 1 PY 1994 VL 99 IS A9 BP 17379 EP 17389 DI 10.1029/94JA01099 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500017 ER PT J AU INTRILIGATOR, DS BRACE, LH CLOUTIER, PA GREBOWSKY, JM HARTLE, RE KASPRZAK, WT KNUDSEN, WC STRANGEWAY, RJ AF INTRILIGATOR, DS BRACE, LH CLOUTIER, PA GREBOWSKY, JM HARTLE, RE KASPRZAK, WT KNUDSEN, WC STRANGEWAY, RJ TI EVIDENCE FOR ION-TRANSPORT AND MOLECULAR ION DOMINANCE IN THE VENUS IONOTAIL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA OBSERVATIONS; MASS-SPECTROMETER; ENERGETIC IONS; PIONEER; TAIL; IONOPAUSE AB We present analyses from the five Pioneer Venus Orbiter plasma experiments and the plasma wave experiment when a patch of plasma with enhanced densities was encountered in the near-Venus ionotail during atmospheric entry at an altitude of similar to 1100 km in the nightside ionosphere. Our analyses of the thermal and superthermal ion measurements in this plasma feature provides the first evidence that at times molecular ions in the 28-32 amu mass range are dominant over atomic mass species thus yielding evidence for a transport mechanism that reaches into the lower ionosphere. Analysis of plasma analyzer (OPA) observations at this time indicates the presence of ions measured in the rest frame of the spacecraft at similar to 27 and 37 volt energy per unit charge steps. In the rest frame of the planet these superthermal ions are flowing from the dawn direction at speeds (assuming they are O-2(+)) of similar to 8 km/s and with a flow component downward (perpendicular to the ecliptic plane) at speeds of similar to 2 km/s. OPA analyses also determine the ion number flux, energy, flow angles, and angular distributions. Plasma wave bursts appear to indicate that plasma density decreases within and on the equatorward edge of the patch of enhanced plasma densities are associated with ion acoustic waves and relative ion streaming. C1 UNIV MICHIGAN,SPACE RES LAB,ANN ARBOR,MI. RICE UNIV,DEPT SPACE PHYS,HOUSTON,TX 77251. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. KNUDSEN GEOPHYS RES INC,MONTE SERENO,CA 95030. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. RP INTRILIGATOR, DS (reprint author), CARMEL RES CTR,SPACE PLASMA LAB,POB 1732,SANTA MONICA,CA 90406, USA. RI Grebowsky, Joseph/I-7185-2013 NR 18 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17413 EP 17420 DI 10.1029/94JA01341 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500020 ER PT J AU IMHOF, WL GAINES, EE MCGLENNON, JP BAKER, DN REEVES, GD BELIAN, RD AF IMHOF, WL GAINES, EE MCGLENNON, JP BAKER, DN REEVES, GD BELIAN, RD TI RELATIVISTIC ELECTRON FLUX COMPARISONS AT LOW AND HIGH-ALTITUDES WITH FAST TIME RESOLUTION AND BROAD SPATIAL COVERAGE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID ENHANCEMENTS; ATMOSPHERE AB Analyses are presented for the first high-time resolution multisatellite study of the spatial and temporal characteristics of a relativistic electron enhancement event with a rapid onset. Measurements of MeV electrons were made from two low-altitude polar orbiting satellites and three spacecraft at synchronous altitude. The electron fluxes observed by the low-altitude satellites include precipitating electrons in both the bounce and drift loss cones as well as electrons that are stably trapped, whereas the observations at geosynchronous altitude are dominated by the trapped population. The fluxes of >1 MeV electrons at low-satellite altitude over a wide range of L shells tracked very well the fluxes >0.93 MeV at synchronous altitude. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP IMHOF, WL (reprint author), LOCKHEED PALO ALTO RES LABS,3251 HANOVER ST,PALO ALTO,CA 94304, USA. RI Reeves, Geoffrey/E-8101-2011 OI Reeves, Geoffrey/0000-0002-7985-8098 NR 10 TC 2 Z9 2 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 SEP 1 PY 1994 VL 99 IS A9 BP 17421 EP 17426 DI 10.1029/94JA01266 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500021 ER PT J AU LORANC, M STMAURICE, JP AF LORANC, M STMAURICE, JP TI A TIME-DEPENDENT GYRO-KINETIC MODEL OF THERMAL ION UPFLOWS IN THE HIGH-LATITUDE F-REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID POLAR PLASMA OUTFLOW; SUPRATHERMAL O+ IONS; EISCAT OBSERVATIONS; VELOCITY DISTRIBUTIONS; AURORAL IONOSPHERE; LOW-ALTITUDE; MAGNETOSPHERE; FLOWS; WIND; ACCELERATION AB Ample evidence supports the significance of the high-latitude ionospheric contribution to magnetospheric plasma. Assuming flux conservation along a flux tube, the upward field-aligned ion flows observed in the magnetosphere require high-latitude ionospheric field-aligned ion upflows of the order of 10(8) to 10(9) cm(-2) s(-1). Since radar and satellite observations of high-latitude F region flows at times exceed this flux requirement by an order of magnitude, the thermal ionospheric upflows are not simply the ionospheric response to a magnetospheric flux requirement. Several ionospheric ion upflow mechanisms have been proposed, but simulations based on fluid theory do not reproduce all the observed features of ionospheric ion upflows. Certain asymmetries in the statistical morphology of high-latitude F region ion upflows suggest that the ion upflows may be generated by ion-neutral frictional heating. We developed a single-component (O+), time-dependent gyro-kinetic model of the high-latitude F region response to frictional heating in which the neutral exobase is a discontinuous boundary between fully collisional and collisionless plasmas. The concept of a discontinuous neutral exobase and the assumption of a constant and uniform polarization electric field reduce the ion guiding center motion in the frame of a convecting flux tube to simple one-dimensional ballistic trajectories. We thus are able to analytically calculate a time and height-dependent ion velocity distribution function, from which we can compute the ion density, parallel velocity, parallel and perpendicular temperature, and parallel flux. Using our model, we simulated the response of a convecting flux tube between 500 km and 2500 km to various frictional heating inputs; the results were both qualitatively and quantitatively different from fluid model results, which may indicate an inadequacy of the fluid theory approach. The gyro-kinetic frictional heating model responses to the various simulations were qualitatively similar: (1) initial perturbations of all the modeled parameters propagated rapidly up the flux tube, (2) transient values of the ion parallel velocity, temperature, and flux exceeded 3 km s(-1), 2 x 10(4) K, and 10(9) cm(-2) s(-1), respectively, (3) a second transient regime developed wherein the parallel temperature drops to very low values (a few hundred Kelvins), and (4) well after heating ceased, large parallel temperatures and large downward parallel velocities and fluxes developed as the flux tube slowly returned to diffusive equilibrium. The ion velocity distributions during the simulation are often non-Maxwellian and are sometimes composed of two distinct ion populations. C1 UNIV WESTERN ONTARIO,DEPT PHYS,LONDON N6A 3K7,ON,CANADA. RP LORANC, M (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES83,HUNTSVILLE,AL 35812, USA. NR 50 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17429 EP 17451 DI 10.1029/93JA01852 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500022 ER PT J AU GILES, BL CHAPPELL, CR MOORE, TE COMFORT, RH WAITE, JH AF GILES, BL CHAPPELL, CR MOORE, TE COMFORT, RH WAITE, JH TI STATISTICAL-SURVEY OF PITCH-ANGLE DISTRIBUTIONS IN-CORE (0-50-EV) IONS FROM DYNAMICS-EXPLORER-1 - OUTFLOW IN THE AURORAL-ZONE, POLAR-CAP, AND CUSP SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RING CURRENT COMPOSITION; SUPRATHERMAL O+ IONS; PLASMA SHEET; EARTHS MAGNETOSPHERE; BOUNDARY-LAYER; MAGNETIC STORM; DE-1 ALTITUDES; ORIGIN; THERMOSPHERE; MAGNETOTAIL AB Core(0-50 eV) ion pitch angle measurements from the retarding ion mass spectrometer on Dynamics Explorer 1 are examined with respect to magnetic disturbance, invariant latitude, magnetic local time, and altitude for ions H+, He+, O+, M/Z=2 (D+ or He++), and O++. Included are outflow events in the auroral zone, polar cap, and cusp, separated into altitude regions below and above 3 R(E) In addition to the customary division into beam, conic, and upwelling distributions, the high-latitude observations fall into three categories corresponding to ion bulk speeds that are (1) less than, (2) comparable to, or (3) faster than that of the spacecraft. This separation, along with the altitude partition, serves to identify conditions under which ionospheric source ions are gravitationally bound and when they are more energetic and able to escape to the outer magnetosphere. Features of the cleft ion fountain inferred from single event studies are clearly identifiable in the statistical results. In addition, it is found that the dayside pre-noon cleft is a consistent source of escape velocity low-energy ions regardless of species or activity level and the dayside afternoon cleft, or auroral zone, becomes an additional source for increased activity. The auroral oval as a whole appears to be a steady source of escape velocity H+, a steady source of escape velocity He+ ions for the dusk sector, and a source of escape velocity heavy ions for dusk local times primarily during increased activity. The polar cap above the auroral zone is a consistent source of low-energy ions, although only the lighter mass particles appear to have sufficient velocity, on average, to escape to higher altitudes. The observations support two concepts for outflow: (1) The cleft ion fountain consists of ionospheric plasma of 1-20 eV energy streaming upward into the magnetosphere where high-latitude convection electric fields cause poleward dispersion. (2) The auroral ion fountain involves field-aligned beams which flow out along auroral latitude field lines; and, in addition, for late afternoon local times, they experience additional acceleration such that the ion energy distribution tends to exceed the detection range of the instrument (>50-60 eV). C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899. SW RES INST,SAN ANTONIO,TX 78284. RP GILES, BL (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 57 TC 33 Z9 33 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 SEP 1 PY 1994 VL 99 IS A9 BP 17483 EP 17501 DI 10.1029/94JA00864 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500026 ER PT J AU MEYEROTT, RE SWENSON, GR SCHWEITZER, EL KOCH, DG AF MEYEROTT, RE SWENSON, GR SCHWEITZER, EL KOCH, DG TI EXCITATION OF THE LOW-LYING VIBRATIONAL LEVELS OF H2O BY O(P-3) AS MEASURED ON SPACELAB-2 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SHUTTLE GLOW; SURFACE GLOW; COLLISIONS; O(3P) AB The data from the infrared telescope (IRT), which was flown on space shuttle Challenger Spacelab 2 mission (July 1985), were originally reported by Koch et al. (1987) as originating from near orbital emissions, primarily H2O In this study, analysis of this data was extended to determine the collisional cross sections for the excitation of the low lying vibrational levels of H2O, present in the orbiter cloud, by atmospheric O(P-3). The evaluation of the contribution to the measured signal from solar excitation and ram O excitation of outgassing H2O permits the determination of the H2O column density and the excitation cross section of the (010) level at an O(P-3) velocity of similar to 7.75 km/s. Contributions to the radiation in the 1.7-3.0 mu m band by transitions from the (100), (001); and multiquantum excited levels are discussed. The findings of the study are (1) the IRT data for the 4.5-9.5 mu m and the nighttime data for the 1.7-3.0 mu m sensors are consistent with being explained by collision excitation of H2O by O(P-3), (2) diurnal variations of 4.5-9.5 mu m intensities follow the model predicted O density for a full orbit, (3) daytime increases in the H2O cloud density were not evident, (4) the cross sections for the collisional excitation process are derived and compared to values computated by Johnson (1986) and Redmon et al. (1986), (5) theoretical investigation suggests >60% of the radiation from H2O is a result of multiphoton emission resulting from collisional multiquanta excitation, and (6) the large daytime increase in the 1.7-3.0 mu m intensity data suggests that Of may likely be instrumental in producing excited H2O+ through charge exchange. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MEYEROTT, RE (reprint author), LOCKHEED PALO ALTO RES LABS,3251 HANOVER ST,O-91-20,B-255,PALO ALTO,CA 94304, USA. NR 22 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17559 EP 17575 DI 10.1029/94JA01241 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500032 ER PT J AU HEDIN, AE BUONSANTO, MJ CODRESCU, M DUBOIN, ML FESEN, CG HAGAN, ME MILLER, KL SIPLER, DP AF HEDIN, AE BUONSANTO, MJ CODRESCU, M DUBOIN, ML FESEN, CG HAGAN, ME MILLER, KL SIPLER, DP TI SOLAR-ACTIVITY VARIATIONS IN MIDLATITUDE THERMOSPHERIC MERIDIONAL WINDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GENERAL-CIRCULATION MODEL; NEUTRAL WINDS; ELECTRIC-FIELDS; MILLSTONE HILL; CYCLE; LATITUDES; EQUINOX; HEIGHT AB Upper thermospheric meridional wind data at midlatitudes and for low magnetic activity are examined for solar activity variations following an analysis scheme suggested by a Coordinated Analysis of the Thermosphere workshop. Wind data from incoherent scatter, Fabry-Perot, and F2 peak heights show decreasing diurnal amplitudes with increasing solar activity during all seasons, except for Saint Santin data, which show a slight increase in summer. Equivalent winds from F2 peak height data have strong decreases in diurnal amplitude in all seasons. The coupled thermosphere ionosphere model and thermosphere ionosphere global circulation model predictions of diurnal amplitude, while differing considerably in magnitude, also show decreasing amplitudes during all seasons except summer, while the HWM90 empirical model amplitudes increase slightly with solar activity during all seasons. The diurnal mean wind trends with solar activity are fairly weak, except for Millstone Hill incoherent scatter radar, which shows a shift from strong southward to near zero or northward wind with increasing activity. Model results for the mean generally fall within the band of measurements. Near midnight, most of the data also show that the typically southward winds weaken with increasing solar activity in all seasons except summer, when results are mixed. There are significant differences between the trends and between absolute values for the various data sets and models which need further investigation. C1 MIT,HAYSTACK OBSERV,WESTFORD,MA 01886. NOAA,SPACE ENVIRONM LAB,BOULDER,CO 80303. UNIV MARNE VALLEE,F-92131 ISSY MOULINEAUX,FRANCE. CTR ETUD ENVIRONNEMENTS TERRESTRE & PLANETAIRE,F-92131 ISSY MOULINEAUX,FRANCE. DARTMOUTH COLL,THAYER SCH ENGN,HANOVER,NH 03755. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. UTAH STATE UNIV,CTR ATMOSPHER & SPACE SCI,LOGAN,UT 84322. RP HEDIN, AE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Hagan, Maura/C-7200-2008 OI Hagan, Maura/0000-0002-8866-7429 NR 26 TC 35 Z9 36 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 JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17601 EP 17608 DI 10.1029/94JA01134 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500035 ER PT J AU GLOECKLER, G GEISS, J ROELOF, EC FISK, LA IPAVICH, FM OGILVIE, KW LANZEROTTI, LJ VONSTEIGER, R WILKEN, B AF GLOECKLER, G GEISS, J ROELOF, EC FISK, LA IPAVICH, FM OGILVIE, KW LANZEROTTI, LJ VONSTEIGER, R WILKEN, B TI ACCELERATION OF INTERSTELLAR PICKUP IONS IN THE DISTURBED SOLAR-WIND OBSERVED ON ULYSSES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COROTATING INTERACTION REGIONS; INTERPLANETARY ACCELERATION; COSMIC-RAYS; SHOCK; NUCLEONS; HYDROGEN; EVENTS AB Acceleration of interstellar pickup H+ and He+ as well as of solar wind protons and alpha particles has been observed on Ulysses during the passage of a corotating interaction region (CIR) at similar to 4.5 AU. Injection efficiencies for both the high thermal speed interstellar pickup ions (H+ and He+) and the low thermal speed solar wind ions (H+ and He++) are derived using velocity distribution functions of protons, pickup He+ and alpha particles from < 1 to 60 keV/e and of ions principally protons) above similar to 60 keV. The observed spatial variations of the few keV and the few hundred keV accelerated pickup protons across the forward shock of the CIR indicate a two stage acceleration mechanism. Thermal ions are first accelerated to speeds of 3 to 4 times the solar wind speed inside the CIR, presumably by some statistical mechanism, before reaching higher energies by a shock acceleration process. Our results also indicate that (1) the injection efficiencies for pickup ions are almost 100 times higher than they are for solar wind ions, (2) pickup H+ and He+ are the two most abundant suprathermal ion species and they carry a large fraction of the particle thermal pressure, (3) the injection efficiency is highest for protons, lowest for He+, and intermediate for alpha particles, (4) both H+ and He+ have identical spectral shapes above the cutoff speed for pickup ions, and (5) the solar wind frame velocity distribution function of protons has the form F(w) = F(0)w(-4) for 1 < w < similar to 5, where w is the ion speed divided by the solar wind speed. Above w similar to 5-10 the proton spectrum becomes steeper. These results have important implications concerning acceleration of ions by shocks and CIRs, acceleration of anomalous cosmic rays, and particle dynamics in the outer heliosphere. C1 UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. UNIV BERN,INST PHYS,CH-3102 BERN,SWITZERLAND. AT&T BELL LABS,MURRAY HILL,NJ 07974. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742. RP GLOECKLER, G (reprint author), UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742, USA. RI Von Steiger, Rudolf/F-6822-2011 OI Von Steiger, Rudolf/0000-0002-3350-0023 NR 25 TC 189 Z9 189 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17637 EP 17643 DI 10.1029/94JA01509 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500040 ER PT J AU FEYNMAN, J RUZMAIKIN, A AF FEYNMAN, J RUZMAIKIN, A TI DISTRIBUTIONS OF THE INTERPLANETARY MAGNETIC-FIELD REVISITED SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; VELOCITY FLUCTUATIONS; TURBULENCE AB The adequacy of the power spectrum to characterize the variations of a parameter depends on whether or not the parameter has a Gaussian distribution. We here perform very simple tests of Gaussianity on the distributions of the magnitudes of the interplanetary magnetic field, and on the distributions of the components; that is, we find the first four cumulants of the distributions (mean, variance, skewness, and kurtosis) and their solar cycle variations. We find, consistent with other recent analyses, that the traditional distributions of the 1-hour averaged magnitude are not distributed normally or lognormally as has often been assumed and the 1-hour averaged z component is found to have a nonzero kurtosis. Thus the power spectrum is insufficient to completely characterize these variations and polyspectra are needed. We have isolated variations in the 1/f frequency region of the spectrum and show that the distributions of the magnitudes have nonzero skewness and kurtosis, the magnitudes are not distributed lognormally, and the distributions of the components have nonzero kurtosis. Thus higher-order spectra are again needed for a full characterization. C1 CALIF STATE UNIV NORTHRIDGE,DEPT PHYS & ASTRON,NORTHRIDGE,CA 91330. RP FEYNMAN, J (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17645 EP 17651 DI 10.1029/94JA01098 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500041 ER PT J AU NAIDU, K BARNES, A AF NAIDU, K BARNES, A TI MOTION OF THE HELIOSPHERIC TERMINATION SHOCK .4. MHD EFFECTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DISTANCE AB In this paper we generalize earlier gasdynamic analyses of the motion of the heliospheric termination shock in response to upstream disturbances (Barnes, 1993, 1994; Naidu and Barnes, 1994), to include magnetohydrodynamic (MHD) phenomena. We assume that the termination shock is a strong, perpendicular shock and that the initial upstream disturbance is a tangential discontinuity. The resulting configuration after the interaction is very similar to that in the gasdynamic models after an interaction with a contact discontinuity or interplanetary shock, and for an increase (decrease) in dynamic pressure consists of an outward (inward) propagating termination shock and an outward propagating shock (MI-ID rarefaction wave) that carries the signal of the disturbance into the far downstream plasma. The plasma immediately behind the new termination shock is separated from the downstream signal by a tangential discontinuity. The results of the model show that the speed of the new termination shock depends mainly on the magnitude of the change in dynamic pressure and are typically of order similar to 100 km/s, comparable to the results of the gasdynamic models. RP NAIDU, K (reprint author), NASA,AMES RES CTR,THEORET STUDIES BRANCH,CODE 245-3,MOFFETT FIELD,CA 94035, USA. NR 11 TC 20 Z9 20 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD SEP 1 PY 1994 VL 99 IS A9 BP 17673 EP 17679 DI 10.1029/94JA01342 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PF925 UT WOS:A1994PF92500043 ER PT J AU SRIDHAR, B CHATTERJI, GB AF SRIDHAR, B CHATTERJI, GB TI VISION-BASED OBSTACLE DETECTION AND GROUPING FOR HELICOPTER GUIDANCE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Electro-optical sensors can be used to compute range to objects in the night path of a helicopter, The computation is based on the optical flow/motion at different points in the Image. The motion algorithms provide a sparse set of ranges to discrete features in the image sequence as a function of azimuth and elevation. For obstacle avoidance guidance and display purposes, these discrete sets of ranges, varying from a few hundred to several thousand, need to be grouped into sets that correspond to objects in the real world. This paper presents a new method for object segmentation based on clustering the sparse range information provided by motion algorithms together with the spatial relation provided by the static image. Object grouping allows interpolation within a group and enables the creation of dense range maps. The paper presents object segmentation results for a sequence of flight images. RP SRIDHAR, B (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 1 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1994 VL 17 IS 5 BP 908 EP 915 DI 10.2514/3.21289 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PZ257 UT WOS:A1994PZ25700005 ER PT J AU CRASSIDIS, JL LEO, DJ INMAN, DJ MOOK, DJ AF CRASSIDIS, JL LEO, DJ INMAN, DJ MOOK, DJ TI ROBUST IDENTIFICATION AND VIBRATION SUPPRESSION OF A FLEXIBLE STRUCTURE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ALGORITHM AB A robust vibration suppression design involving the use of H-infinity optimal control theory is studied for a complex flexible structure. The digital control architecture involves noncollocated feedback utilizing active piezoceramic actuators and position sensor data. The modal properties of the multi-input, multi-output structure are first determined from experimental data in order to obtain an identified state-space model. This model forms the basis for the H-infinity vibration suppression design. Performance specifications are developed that obtain adequate damping in the structure while maintaining controller integrity without the destabilization of higher modes. A controller optimized for these H-infinity performance specifications is implemented on the actual test structure. Experimental structural perturbations are also examined in order to determine the robustness of the vibration suppression design. The experimental study indicates that the H-infinity design substantially increases damping in the targeted frequency region and conforms to predicted analytical simulations. C1 VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061. SUNY BUFFALO,DEPT MECH & AEROSP ENGN,BUFFALO,NY 14260. RP CRASSIDIS, JL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,GREENBELT,MD 20771, USA. NR 25 TC 6 Z9 6 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1994 VL 17 IS 5 BP 921 EP 928 DI 10.2514/3.21291 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PZ257 UT WOS:A1994PZ25700007 ER PT J AU XU, K WARNITCHAI, P IGUSA, T AF XU, K WARNITCHAI, P IGUSA, T TI OPTIMAL PLACEMENT AND GAINS OF SENSORS AND ACTUATORS FOR FEEDBACK-CONTROL SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents an optimal design method for placement and gains of actuators and sensors in output feedback control systems. A quadratic performance function is minimized using nonlinear programming. The new contribution is the derivation of analytical expressions for the gradients of the performance function. These gradients are important because they can be efficiently computed and do not suffer from errors associated with finite differences. This makes the method suitable for systems with a Large number of actuators. Several numerical studies are performed for a two-dimensional structure. In all cases, even with 100 optimization variables, convergence is rapid. C1 ASIAN INST TECHNOL,BANGKOK 10501,THAILAND. NORTHWESTERN UNIV,EVANSTON,IL 60208. RP XU, K (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. RI Igusa, Takeru/A-3218-2010 OI Igusa, Takeru/0000-0002-3632-2867 NR 21 TC 24 Z9 35 U1 1 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1994 VL 17 IS 5 BP 929 EP 934 DI 10.2514/3.21292 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PZ257 UT WOS:A1994PZ25700008 ER PT J AU ARMSTRONG, ES AF ARMSTRONG, ES TI COPRIME FACTORIZATION APPROACH TO ROBUST STABILIZATION OF CONTROL-STRUCTURES INTERACTION EVOLUTIONARY MODEL SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID INFINITY AB Stabilization in the presence of uncertainties is a fundamental requirement in the design of feedback compensators for flexible structures. The search for the largest neighborhood around a given design plant for which a single feedback controller produces closed-loop stability can be formulated as an H-infinity control problem. It has been shown that the use of normalized coprime factor plant descriptions, where the plant perturbations are defined as additive modifications to the coprime factors, leads to a closed-form expression for the maximal-neighborhood boundary allowing optimal and suboptimal H-infinity compensators to be computed directly without the usual gamma-iteration. This paper describes an application of normalized coprime factor stabilization theory to the computation of robustly stable compensators for the NASA Control Structures Interaction Evolutionary Model. Results indicate that the suboptimal version of the theory has the potential of providing low authority compensators that are robustly stable for significant regions of variations in design model parameters and additive unmodeled dynamics. RP ARMSTRONG, ES (reprint author), NASA,LANGLEY RES CTR,GUIDANCE & CONTROL BRANCH,HAMPTON,VA 23681, USA. NR 15 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1994 VL 17 IS 5 BP 935 EP 941 DI 10.2514/3.21293 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PZ257 UT WOS:A1994PZ25700009 ER PT J AU SU, TJ JUANG, JN AF SU, TJ JUANG, JN TI SUBSTRUCTURE SYSTEM-IDENTIFICATION AND SYNTHESIS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper explores the possibility of performing system identification at the substructure level and then synthesizing the results to obtain an analysis model for the assembled structure. The study here shows that to produce exact substructure coupling, the input-output transfer function relations among all of the interface degrees of freedom must be measured. Procedures for assembling substructure transfer function data, substructure state-space models, and substructure Markov parameters are presented. Some potential testing difficulties and possible solution approaches are also discussed. A mass-loaded interface approach is proposed to produce interface excitations without using actuators. A spring-supported boundary approach is developed for the testing of free substructures. Some feasible testing setups for the measurement and excitation of the interface rotational degrees of freedom are also included. The proposed methods are illustrated by a numerical example. RP SU, TJ (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23681, USA. NR 9 TC 10 Z9 11 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD SEP-OCT PY 1994 VL 17 IS 5 BP 1087 EP 1095 DI 10.2514/3.21314 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PZ257 UT WOS:A1994PZ25700030 ER PT J AU SATHISH, S CANTRELL, JH YOST, WT AF SATHISH, S CANTRELL, JH YOST, WT TI RADIAL VARIATION OF ELASTIC PROPERTIES OF SCS-6 SILICON-CARBIDE FIBER SO JOURNAL OF MATERIALS RESEARCH LA English DT Article AB The upper and lower bounds of the bulk, shear, and Young's moduli are calculated point-by-point along the radius of SCS-6 silicon carbide fibers using the Hashin-Shtrikman equations from considerations of the Auger spectra along the fiber radius. The calculated values are in agreement with measurements of the average Young modulus obtained over relatively large radial regions of the fiber using scanning acoustic microscopy (SAM). The validity of the Hashin-Shtrikman bounds calculations is enhanced by the agreement found between experimental SAM V(z) curves for fixed z along the fiber radius and the theoretical bounds of such curves obtained from the bounds of the calculated bulk and shear moduli. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP SATHISH, S (reprint author), ANALYT SESRV & MAT INC,107 RES DR,HAMPTON,VA 23666, USA. NR 6 TC 4 Z9 4 U1 0 U2 2 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD SEP PY 1994 VL 9 IS 9 BP 2298 EP 2303 DI 10.1557/JMR.1994.2298 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA PD705 UT WOS:A1994PD70500015 ER PT J AU BANSAL, NP AF BANSAL, NP TI SYNTHESIS AND THERMAL EVOLUTION OF STRUCTURE IN ALKOXIDE-DERIVED NIOBIUM PENTOXIDE GELS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID METAL FLUORIDE GLASSES; SPECTRA; CRYSTALLIZATION; KINETICS; NB2O5 AB Niobium pentoxide gels in the form of transparent monoliths and powder have been synthesized from the controlled hydrolysis and polycondensation of niobium pentaethoxide under different experimental conditions using various mole ratios of Nb(OC2H5)5:H2O:C2H5OH:HCl. Alcohol acted as the mutual solvent and HCl as the deflocculating agent. In the absence of HCl, precipitation of colloidal particles was encountered on the addition of any water to the alkoxide. The gels were subjected to various thermal treatments and characterized by differential thermal analysis, thermogravimetric analysis, X-ray diffraction and infra-red spectroscopy. After drying at 400-degrees-C, the gels were amorphous to X-rays. The amorphous powder crystallized into the low temperature orthorhombic form of Nb2O5 at approximately 500-degrees-C, which transformed irreversibly into the high temperature monoclinic alpha-Nb2O5 between 900 to 1000-degrees-C. The kinetics of crystallization of the amorphous niobium pentoxide have been investigated by non-isothermal differential scanning calorimetry. The crystallization activation energy was determined to be 399 kJ mol-1. RP BANSAL, NP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 24 TC 16 Z9 16 U1 0 U2 1 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD SEP 1 PY 1994 VL 29 IS 17 BP 4481 EP 4486 DI 10.1007/BF00376270 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA PE419 UT WOS:A1994PE41900008 ER PT J AU KENNY, TW KAISER, WJ ROCKSTAD, HK REYNOLDS, JK PODOSEK, JA VOTE, EC AF KENNY, TW KAISER, WJ ROCKSTAD, HK REYNOLDS, JK PODOSEK, JA VOTE, EC TI WIDE-BANDWIDTH ELECTROMECHANICAL ACTUATORS FOR TUNNELING DISPLACEMENT TRANSDUCERS SO JOURNAL OF MICROELECTROMECHANICAL SYSTEMS LA English DT Article ID NOISE; MICROSCOPY; SILICON; SENSOR AB A series of displacement transducers have been demonstrated which are based on the detection of electrons that quantum-mechanically tunnel across a narrow gap between electrodes, These transducers have important applications due to the sensitivity of the tunneling mechanism to sub-Angstrom variations in the electrode gap. In this paper, we describe the recent development of wide-bandwidth electromechanical actuators and simple feedback circuitry which have been adapted for use in tunneling displacement transducers. With these actuators and circuits, we have built tunneling transducers with control bandwidths well in excess of 10 kHz, The design, fabrication, operation, and applications of these actuators are described. [69] C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. NR 23 TC 27 Z9 29 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 1057-7157 J9 J MICROELECTROMECH S JI J. Microelectromech. Syst. PD SEP PY 1994 VL 3 IS 3 BP 97 EP 104 DI 10.1109/84.311559 PG 8 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Instruments & Instrumentation; Physics, Applied SC Engineering; Science & Technology - Other Topics; Instruments & Instrumentation; Physics GA RM176 UT WOS:A1994RM17600002 ER PT J AU CHATTERJEE, S GILBERT, JR SCHREIBER, R SHEFFLER, TJ AF CHATTERJEE, S GILBERT, JR SCHREIBER, R SHEFFLER, TJ TI MODELING DATA-PARALLEL PROGRAMS WITH THE ALIGNMENT-DISTRIBUTION GRAPH SO JOURNAL OF PROGRAMMING LANGUAGES LA English DT Article DE ARRAY PARALLELISM; ALIGNMENT; DISTRIBUTION; INTERMEDIATE REPRESENTATION; DISTRIBUTED-MEMORY PARALLEL COMPUTER; COMMUNICATION OPTIMIZATION ID MACHINES AB An intermediate representation of a program called the alginment-distribution graph, that exposes the communication requirements of a program is presented. The representation exploits ideas developed in the static single assignment form of programs, but is tailored for communication optimization. It serves as the basis for algorithms that map the array data and program computation to the nodes of a distributed-memory parallel computer so as to minimize completion time. The details of the representation are described, its construction from source text is shown, its use in modelling communication cost is shown, several algorithms for determining mappings that approximately minimize residual communication are outlined and it is compared with other related intermediate representations of programs. C1 XEROX CORP,PALO ALTO RES CTR,PALO ALTO,CA 94304. RP CHATTERJEE, S (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MAIL STOP T27A-1,MOFFETT FIELD,CA 94035, USA. NR 23 TC 4 Z9 4 U1 0 U2 0 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0963-9306 J9 J PROGRAM LANG JI J. Program. Lang. PD SEP PY 1994 VL 2 IS 3 BP 227 EP 258 PG 32 WC Computer Science, Software Engineering SC Computer Science GA QC552 UT WOS:A1994QC55200003 ER PT J AU YUNGSTER, S RABINOWITZ, MJ AF YUNGSTER, S RABINOWITZ, MJ TI COMPUTATION OF SHOCK-INDUCED COMBUSTION USING A DETAILED METHANE-AIR MECHANISM SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ ID OXIDATION AB The shock-induced combustion of methane-air mixtures in hypersonic flows is investigated using a new reaction mechanism consisting of 19 reacting species and 52 elementary reactions. This reduced model is derived from a full kinetic mechanism via the detailed reduction technique. Zero-dimensional computations of several shock-tube experiments are presented first. The computed values for ignition delay and flame speed are in close agreement with experimental data and with results obtained using a full mechanism. The new reaction mechanism is then combined with a fully implicit Navier-Stokes CFD code to simulate two-dimensional and axisymmetric shock-induced combustion experiments of stoichiometric methane-air mixtures at a Mach number of M = 6.61. Good agreement with the experiments is obtained. Furthermore, it is shown that previous calculations were unable to accurately predict this type of flow due to their use of severely limited reduced chemical mechanisms. Finally, applications to the ram accelerator concept are also presented, based on a novel double-ramp configuration. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP YUNGSTER, S (reprint author), NASA,LEWIS RES CTR,INST MECH PROP,CLEVELAND,OH 44135, USA. NR 21 TC 18 Z9 18 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 609 EP 617 DI 10.2514/3.23770 PG 9 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600003 ER PT J AU HOCHSTEIN, JI AYDELOTT, JC MJOLSNESS, RC TORREY, MD AF HOCHSTEIN, JI AYDELOTT, JC MJOLSNESS, RC TORREY, MD TI ON-ORBIT PROPELLANT MOTION RESULTING FROM AN IMPULSIVE ACCELERATION SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB In-space docking and separation maneuvers of spacecraft that have large fluid mass fractions may cause undesirable spacecraft motion in response to the impulsive-acceleration-induced fluid motion. An example of this potential low-gravity fluid management problem arose during the development of the shuttle/Centaur vehicle. Experimentally verified numerical modeling techniques were developed to establish the propellant dynamics, and subsequent vehicle motion, associated with the separation of the Centaur vehicle from the shuttle cargo bay. Although the shuttle/Centaur development activity has been suspended, the numerical modeling techniques are available to predict on-orbit liquid motion resulting from impulsive accelerations for other missions and spacecraft. C1 NASA,LEWIS RES CTR,CYROGEN FLUIDS TECHNOL OFF,CLEVELAND,OH 44135. LOS ALAMOS NATL LAB,FLUID DYNAM GRP T3,LOS ALAMOS,NM 87545. RP HOCHSTEIN, JI (reprint author), MEMPHIS STATE UNIV,MEMPHIS,TN 38152, USA. NR 9 TC 0 Z9 0 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 653 EP 660 DI 10.2514/3.23776 PG 8 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600009 ER PT J AU ANDERSON, BH REDDY, DR KAPOOR, K AF ANDERSON, BH REDDY, DR KAPOOR, K TI STUDY ON COMPUTING SEPARATING FLOWS WITHIN A DIFFUSING INLET S-DUCT SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ ID VELOCITY AB A three-dimensional implicit full Navier-Stokes (FNS) analysis and a three-dimensional reduced Navier-Stokes (RNS) initial value space marching solution technique have been applied to a class of separated flow problems within a diffusing S-duct configuration characterized as vortex-liftoff. Both the FNS and the RNS solution technique were able to capture the overall flow physics of vortex liftoff, and gave remarkably similar results which agreed reasonably well with the experimental performance data. However, the FNS and RNS also consistently predicted separation further downstream in the M2129 inlet S-duct than was indicated by experimental data. The separated region associated with vortex liftoff in M2129 inlet S-duct increased in size as the inlet mass now increased, although the radial extent of the reverse flow region remained very small. Since the reverse flow velocity was also very small, the separated flow in the M2129 S-duct might be regarded as incipient. This, along with the fact that the RNS analysis was able to capture the topology of vortex liftoff, indicates that the parabolized form of the Navier-Stokes equations are appropriate for separated flows represented by the M2129 inlet S-duct. RP ANDERSON, BH (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 21 TC 7 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 661 EP 667 DI 10.2514/3.23777 PG 7 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600010 ER PT J AU WELLBORN, SR REICHERT, BA OKIISHI, TH AF WELLBORN, SR REICHERT, BA OKIISHI, TH TI STUDY OF THE COMPRESSIBLE FLOW IN A DIFFUSING S-DUCT SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Benchmark aerodynamic data are presented for compressible now through a representative S-duct configuration. Measurements of the three-dimensional velocity field, total pressures, and static pressures were obtained in five cross-sectional planes. Surface static pressure and surface flow visualization data were also acquired. All reported tests were conducted with an inlet centerline Mach number of 0.6. The Reynolds number, based on the inlet centerline velocity and duct inlet diameter, was 2.6 x 10(6). Thin inlet turbulent boundary layers existed. The collected data should be beneficial to aircraft inlet designers and are suitable for the validation of computational codes. The results show that a region of streamwise flow separation occurred within the duct. Measurements indicate that the duct curvature induced strong pressure-driven secondary flows. The crossflows evolved into counter-rotating vortices. These vortices convected low momentum fluid of the boundary layer toward the center of the duct, degrading both the uniformity and magnitude of the total pressure profile. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WELLBORN, SR (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT MECH ENGN,AMES,IA 50011, USA. NR 27 TC 12 Z9 12 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 668 EP 675 DI 10.2514/3.23778 PG 8 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600011 ER PT J AU MILLER, JH STEINETZ, BM SIROCKY, PJ KREN, LA AF MILLER, JH STEINETZ, BM SIROCKY, PJ KREN, LA TI HOT DYNAMIC TEST RIG FOR MEASURING HYPERSONIC ENGINE SEAL FLOW AND DURABILITY SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A test fixture for measuring the dynamic performance of candidate high-temperature engine seal concepts has been developed and installed at NASA Lewis Research Center. Th, test fixture has been developed to evaluate seal concepts under development for advanced hypersonic engines, such as those being considered for the National Aerospace Plane. The fixture can measure dynamic seal leakage performance from room temperature up to 840-degrees-C (1550-degrees-F), and air pressure differentials up to 0.7 MPa (100 psi). Performance of the seals can be measured while sealing against flat or engine-simulated distorted walls. In the fixture two seals are preloaded against the sides of a 0.3-m- (1-ft-) long saber that slides transverse to the axis of the seals, simulating the scrubbing motion anticipated in these engines. This report covers the capabilities of this text fixture along with preliminary data showing the dependence of seal leakage performance on high-temperature cycling. C1 NASA,LEWIS RES CTR,STRUCT DYNAM BRANCH,CLEVELAND,OH 44135. CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106. RP MILLER, JH (reprint author), SVERDRUP TECHNOL INC,LEWIS RES GRP,BROOKPARK,OH 44142, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 716 EP 720 DI 10.2514/3.23784 PG 5 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600017 ER PT J AU ZELEZNIK, FJ AF ZELEZNIK, FJ TI EVALUATION OF THE MUNICH METHOD FOR MODELING ROCKET ENGINE PERFORMANCE - REPLY SO JOURNAL OF PROPULSION AND POWER LA English DT Note RP ZELEZNIK, FJ (reprint author), NASA,LEWIS RES CTR,AEROTHERMOCHEM BRANCH,27000 BROOKPK RD,M-S 5-11,CLEVELAND,OH 44135, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD SEP-OCT PY 1994 VL 10 IS 5 BP 752 EP 753 DI 10.2514/3.51394 PG 2 WC Engineering, Aerospace SC Engineering GA PG536 UT WOS:A1994PG53600026 ER PT J AU RINSLAND, CP YUE, GK GUNSON, MR ZANDER, R ABRAMS, MC AF RINSLAND, CP YUE, GK GUNSON, MR ZANDER, R ABRAMS, MC TI MIDINFRARED EXTINCTION BY SULFATE AEROSOLS FROM THE MT-PINATUBO ERUPTION SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID STRATOSPHERIC AEROSOL; OPTICAL-CONSTANTS; SIZE DISTRIBUTION; SULFURIC-ACID; ABSORPTION; LARAMIE; CLOUDS; SUMMER AB Quantitative measurements of the wavelength dependence of aerosol extinction in the 750-3400 cm(-1) spectral region have been derived from 0.01 cm(-1) resolution stratospheric solar occultation spectra recorded by the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer about 91/2 months after the Mt Pinatubo volcanic eruption. Strong, broad aerosol features have been identified near 900, 1060, 1190, 1720, and 2900 cm(-1) below a tangent height of similar to 30 km. Aerosol extinction measurements derived from similar to 0.05 cm(-1) wide microwindows nearly free of telluric line absorption in the ATMOS spectra are compared with transmission calculations derived from aerosol size distribution profiles retrieved from correlative SAGE (Stratospheric Aerosol and Gas Experiment) II visible and near i.r. extinction measurements, seasonal and zonally averaged H2SO4 aerosol weight percentage profiles, and published sulfuric acid optical constants derived from room temperature laboratory measurements. The calculated shapes and positions of the aerosol features are generally consistent with the observations, thereby confirming that the aerosols are predominantly concentrated H2SO4-H2O droplets, but there are significant differences between the measured and calculated wavelength dependences of the aerosol extinction. We attribute these differences as primarily the result of errors in the calculated low temperature H2SO4-H2O optical constants. Errors in both the published room temperature optical constants and the limitations of the Lorentz-Lorenz relation are likely to be important. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 35 TC 42 Z9 42 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 SEP-OCT PY 1994 VL 52 IS 3-4 BP 241 EP 252 DI 10.1016/0022-4073(94)90154-6 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800003 ER PT J AU RINSLAND, CP GOLDMAN, A MURCRAY, FJ DAVID, SJ BLATHERWICK, RD MURCRAY, DG AF RINSLAND, CP GOLDMAN, A MURCRAY, FJ DAVID, SJ BLATHERWICK, RD MURCRAY, DG TI INFRARED SPECTROSCOPIC MEASUREMENTS OF THE ETHANE (C2H6) TOTAL COLUMN ABUNDANCE ABOVE MAUNA-LOA, HAWAII - SEASONAL-VARIATIONS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID 3000 CM-1 REGION; LOWER STRATOSPHERE; ATMOSPHERIC GASES; UPPER TROPOSPHERE; LINE PARAMETERS; SPECTRA; RESOLUTION; ACETYLENE; AIRCRAFT; PROPANE AB About 200 i.r. solar spectra recorded at 0.01 cm(-1) resolution on 71 days between November 1991 and July 1993 at the Network for the Detection of Stratospheric Change (NDSC) station at Mauna Loa, Hawaii (latitude 19.53 degrees N, longitude 155.58 degrees W, elevation 3.459 km) have been analyzed with a nonlinear least-squares spectral fitting technique to study temporal variations in the total column of atmospheric ethane (C2H6) above the site. The results were derived from the analysis of the unresolved v(7) band (P)Q(3) subbranch at 2976.8 cm(-1) A distinct seasonal cycle is observed with a factor of 2 variation, a maximum total column of 1.16 x 10(16)mol.cm(-2) at the end of winter, and a minimum total column of 0.53 x 10(16) mol.cm(-2) at the end of summer. Our measurements are compared with previous observations and model predictions. C1 UNIV DENVER,DEPT PHYS,DENVER,CO 80208. RP RINSLAND, CP (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 27 TC 9 Z9 9 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP-OCT PY 1994 VL 52 IS 3-4 BP 273 EP 279 DI 10.1016/0022-4073(94)90157-0 PG 7 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800006 ER PT J AU PERRIN, A FLAUD, JM CAMYPEYRET, C GOLDMAN, A RINSLAND, CP GUNSON, MR AF PERRIN, A FLAUD, JM CAMYPEYRET, C GOLDMAN, A RINSLAND, CP GUNSON, MR TI IDENTIFICATION OF THE HNO3 3-NU(9)-NU(9) BAND-Q BRANCH IN STRATOSPHERIC SOLAR OCCULTATION SPECTRA SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID LINE PARAMETERS; AIR AB The spectroscopic identification for the HNO3 3v(9)-v(9) band and branch at 830.4 cm(-1) is reported based on 0.01 cm(-1) resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025 cm(-1) resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(18)cm(-1)/mol.cm(-2) at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated. C1 UNIV DENVER,DEPT PHYS,DENVER,CO 80208. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP PERRIN, A (reprint author), UNIV PARIS 06,PHYS MOLEC & APPLICAT LAB,CNRS,4 PL JUSSIEU,F-75252 PARIS,FRANCE. NR 14 TC 15 Z9 15 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 SEP-OCT PY 1994 VL 52 IS 3-4 BP 319 EP 322 DI 10.1016/0022-4073(94)90161-9 PG 4 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800010 ER PT J AU GOLDMAN, A GILLIS, JR RINSLAND, CP BURKHOLDER, JB AF GOLDMAN, A GILLIS, JR RINSLAND, CP BURKHOLDER, JB TI IMPROVED LINE PARAMETERS FOR THE CHI(2)PI-CHI(2)PI(1-0) BANDS OF (CLO)-CL-35 AND (CLO)-CL-37 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID CLO AB Improved line parameters at 296K for the X(2) Pi-X(2) Pi (1-0) bands of (ClO)-Cl-35 and (ClO)-Cl-37 have been calculated with J up to 43.5. The integrated intensity for the 2048 lines in the main and satellite bands has been normalized to 9.68 cm(-2)atm(-1) at 296K. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. NOAA,AERON LAB,BOULDER,CO 80303. UNIV COLORADO,DEPT CHEM & BIOCHEM,BOULDER,CO 80309. UNIV COLORADO,CIRES,BOULDER,CO 80309. BOEING DEF & SPACE GRP,SEATTLE,WA 98124. RP GOLDMAN, A (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. RI Burkholder, James/H-4914-2013 NR 8 TC 5 Z9 5 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP-OCT PY 1994 VL 52 IS 3-4 BP 357 EP 359 DI 10.1016/0022-4073(94)90165-1 PG 3 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800014 ER PT J AU GOLDMAN, A RINSLAND, CP MURCRAY, FJ BLATHERWICK, RD MURCRAY, DG AF GOLDMAN, A RINSLAND, CP MURCRAY, FJ BLATHERWICK, RD MURCRAY, DG TI HIGH-RESOLUTION STUDIES OF HEAVY NOY MOLECULES IN ATMOSPHERIC SPECTRA SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID NITRIC-ACID; BALLOON-BORNE; LABORATORY SPECTRA; LINE PARAMETERS; HNO3; STRATOSPHERE; INTENSITIES; SPACELAB-3; PROFILES; 2-NU-9 AB New line parameters for two heavy odd nitrogen molecules HNO3 in the v(5)/2v(9) region, and ClONO2 in the v(4) region are incorporated in the analysis of high resolution i.r. atmospheric spectra. The line parameters are tested and renormalized vs laboratory spectra, and then applied to retrievals from balloon-borne and ground-based solar absorption spectra. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. RP GOLDMAN, A (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. NR 19 TC 22 Z9 22 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP-OCT PY 1994 VL 52 IS 3-4 BP 367 EP 377 DI 10.1016/0022-4073(94)90167-8 PG 11 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800016 ER PT J AU EDWARDS, DP LOPEZPUERTAS, M MLYNCZAK, MG AF EDWARDS, DP LOPEZPUERTAS, M MLYNCZAK, MG TI NONLOCAL THERMODYNAMIC-EQUILIBRIUM LIMB RADIANCE FROM O-3 AND CO2 IN THE 9-11-MU-M SPECTRAL REGION SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article; Proceedings Paper CT 3rd Conference on Atmospheric Spectroscopy Applications CY SEP 08-10, 1993 CL REIMS, FRANCE ID TERRESTRIAL MIDDLE ATMOSPHERE; VIBRATIONALLY EXCITED OZONE; RADIATIVE-TRANSFER MODEL; M BANDS; CARBON-DIOXIDE; INFRARED BANDS; EMISSION; TEMPERATURES AB Satellite remote sensing of mesospheric and thermospheric O-3 abundance in the terrestrial atmosphere often uses 9-11 mu m thermal emission. In this paper, we apply a line-by-line non-local thermodynamic equilibrium (non-LTE) radiance model to this spectral region and investigate the conditions of LTE breakdown and the effect that this has on the limb radiance measured by an i.r. sounder. Monochromatic and band-integrated radiance calculations have been performed for limb view tangent heights between 55 and 105 km under daytime and nighttime conditions. Non-LTE emission from both O-3 and CO2 are shown to be important with the divergence of radiance from LTE values and the diurnal variation being band dependent. We have shown that the contribution of the CO2 bands to the Limb Infrared Monitor of the Stratosphere O-3 channel is significant for daytime conditions at tangent heights above about 60 km. A study has been made to choose O-3 sounding channel spectral passbands for the High Resolution Dynamics Limb Sounder. High resolution calculations are required to determine those spectral intervals that will filter radiance from selected bands and characterize their non-LTE behavior. This will allow for improved O-3 retrievals above 70 km and non-LTE studies. C1 CSIC,INST ASTROFIS ANDALUCIA,E-18080 GRANADA,SPAIN. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP EDWARDS, DP (reprint author), NATL CTR ATMOSPHER RES,POB 3000,BOULDER,CO 80307, USA. RI Mlynczak, Martin/K-3396-2012; Lopez Puertas, Manuel/M-8219-2013 OI Lopez Puertas, Manuel/0000-0003-2941-7734 NR 26 TC 16 Z9 16 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 SEP-OCT PY 1994 VL 52 IS 3-4 BP 389 EP 407 DI 10.1016/0022-4073(94)90169-4 PG 19 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PT838 UT WOS:A1994PT83800018 ER PT J AU SREENIVASAN, SV WILCOX, BH AF SREENIVASAN, SV WILCOX, BH TI STABILITY AND TRACTION CONTROL OF AN ACTIVELY ACTUATED MICRO-ROVER SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB This article addresses the issue of enhancing mobility of actively actuated vehicles by the use of optimal force distribution, and by actively controlling the location of the center of mass of the vehicle body. Force distribution in actively actuated vehicles is an underspecified problem, and optimal force distribution leads to improved contact conditions. Actively actuated vehicles also possess the ability to vary their configuration. This capability can be used to locate the center of mass of the system to further enhance mobility by providing sufficient traction, and ensuring vehicle stability, during difficult vehicle maneuvers. In this work, the general idea of control of the location of the center of mass, followed by optimal force distribution, is addressed first. This is followed by an application of these ideas to Gofor, a simple actively actuated wheeled micro-rover system, that has been designed and fabricated at the Jet Propulsion Laboratory. An algorithm to achieve desired traction and stability has been developed. Simulation studies were performed to investigate negotiation of a vertical surface, It was found that one set of wheels readily climbed the vertical surface with the use of active mass and force distribution. This is a significant improvement over traditional wheeled vehicle systems. (C) 1994 John Wiley & Sons, Inc. C1 JET PROP LAB,ROBOT VEHICLES GRP,PASADENA,CA 91109. RP SREENIVASAN, SV (reprint author), OHIO STATE UNIV,DEPT MECH ENGN,COLUMBUS,OH 43210, USA. NR 14 TC 56 Z9 66 U1 2 U2 5 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD SEP PY 1994 VL 11 IS 6 BP 487 EP 502 DI 10.1002/rob.4620110604 PG 16 WC Robotics SC Robotics GA PC797 UT WOS:A1994PC79700003 ER PT J AU DOGRA, VK MOSS, JN WILMOTH, RG PRICE, JM AF DOGRA, VK MOSS, JN WILMOTH, RG PRICE, JM TI HYPERSONIC RAREFIED FLOW PAST SPHERES INCLUDING WAKE STRUCTURE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Results of a numerical study using the direct simulation Monte Carlo method are presented for hypersonic rarefied now past spheres. The flow conditions considered are those corresponding to low-density wind-tunnel test conditions. The set of the experimental conditions for the calculations encompasses the transitional to near-continuum now regimes. Comparison of the calculated drag with experimental results shows good agreement to well within the experimental error Particular attention is focused on the wake structure. Calculations show that the wake is very rarefied with considerable thermal nonequilibrium for all the cases considered. No now separation is observed in the wake for the near-continuum case where a vortex has been predicted by Navier-Stokes-type calculations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP DOGRA, VK (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 19 TC 8 Z9 8 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 SEP-OCT PY 1994 VL 31 IS 5 BP 713 EP 718 DI 10.2514/3.26503 PG 6 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400001 ER PT J AU RAULT, DFG AF RAULT, DFG TI AERODYNAMIC CHARACTERISTICS OF A HYPERSONIC VISCOUS OPTIMIZED WAVERIDER AT HIGH-ALTITUDES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The aerodynamic characteristics of a University of Maryland viscous optimized waverider are studied at altitudes ranging from 97 to 145 km and incidence angles of 0 to 30 deg. The direct simulation Monte Carlo method is used to simulate and analyze the flowfield around the waverider and evaluate surface loads. It is shown that the vehicle lift-to-drag ratio decreases rapidly as night altitude is increased, and is confined to values less than 0.3. At high altitudes, the waverider is surrounded by a thick viscous shock layer, and the friction forces, which are typically large at high Knudsen numbers, are shown to significantly reduce lift and increase drag. RP RAULT, DFG (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 18 TC 9 Z9 10 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 719 EP 727 DI 10.2514/3.26504 PG 9 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400002 ER PT J AU CHEN, YK HENLINE, WD AF CHEN, YK HENLINE, WD TI HYPERSONIC NONEQUILIBRIUM NAVIER-STOKES SOLUTIONS OVER AN ABLATING GRAPHITE NOSETIP SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The general boundary conditions, including mass and energy balances, of chemically equilibrated or nonequilibrated gas adjacent to ablating surfaces have been derived. A computer procedure based on these conditions was developed and interfaced with the Navier-Stokes solver GASP (General Aerodynamics Simulation Program). A test case with a proposed hypersonic test-vehicle configuration and associated freestream conditions was developed. The solutions of the GASP code with various surface boundary conditions were obtained and compared with those of the ASCC (ABRES Shape Change) code, and the effect of nonequilibrium gas as well as surface chemistry on surface heating and ablation rate were examined. C1 NASA,AMES RES CTR,THERMAL PROTECT MAT BRANCH,MOFFETT FIELD,CA 94035. RP CHEN, YK (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 234-1,MOFFETT FIELD,CA 94035, USA. NR 22 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 728 EP 734 DI 10.2514/3.26505 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400003 ER PT J AU STEWART, DA CHEN, YK AF STEWART, DA CHEN, YK TI HYPERSONIC CONVECTIVE HEAT-TRANSFER OVER 140-DEG BLUNT CONES IN DIFFERENT GASES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Large-angle blunt cones, with various corner radii, were tested in dissociated air, CO2, and CO2-Ar gas mixtures. These experiments were conducted at angles of attack from 0 to 20 deg. Heating distribution data and bow shock-wave geometry were obtained during exposure of the cones to the three gases, The data can be used to partially validate two-dimensional (2-D) axisymmetric and three-dimensional Navier-Stokes solutions of the heating distribution over a 140-deg blunt cone in a simulated Martian atmosphere. The predicted heating distribution over the cones and estimated bow shock standoff distances using a 2-D axisymmetric Navier-Stokes code were compared with test data taken at zero angle of attack. C1 ELORET INST,PALO ALTO,CA 94303. RP STEWART, DA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 TC 14 Z9 14 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 735 EP 743 DI 10.2514/3.26506 PG 9 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400004 ER PT J AU GREENE, FA AF GREENE, FA TI APPLICATION OF THE MULTIGRID SOLUTION TECHNIQUE TO HYPERSONIC ENTRY VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEMES; LAURA AB Multigrid techniques have been incorporated into an existing hypersonic now analysis code, the Langley aerothermodynamic upwind relaxation algorithm. The multigrid scheme is based on the full approximation storage approach and uses full multigrid to obtain a well-defined fine-mesh starting solution. Predictions were obtained using standard transfer operators, and a V cycle was used to control grid sequencing. Computed hypersonic now solutions, compared with experimental data for a 15-deg blunted sphere-cone and a blended-wing body, are presented. It is shown that the algorithm predicts heating rates accurately, and computes solutions in one-third the computational time of the nonmultigrid algorithm. RP GREENE, FA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 23 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 744 EP 750 DI 10.2514/3.26507 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400005 ER PT J AU GUPTA, RN ZOBY, EV NAYANI, SN LEE, KP AF GUPTA, RN ZOBY, EV NAYANI, SN LEE, KP TI HIGHER-ORDER VISCOUS SHOCK-LAYER SOLUTIONS FOR HIGH-ALTITUDE FLOWS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID REYNOLDS-NUMBER FLOWS; LONG SLENDER BODIES AB A higher-order viscous-shock-layer method has been developed and is used to obtain physically consistent results under varying degrees of low-density conditions for perfect-gas and nonequilibrium flows past slender bodies. The method of solution is a spatial-marching, implicit finite-difference technique, which employs a Vigneron pressure condition in the subsonic nose region. Higher-order body and shock slip conditions are employed with the method to obtain solutions for the low-density flows. Detailed comparisons with the direct simulation Monte Carlo method and Navier-Stokes calculations clearly show that the higher-order terms included in the HVSL equations are required to predict comparable values of surface pressure and heat transfer rate at higher altitude. The deficiency of the standard viscous shock-layer method in predicting low-density flows can not be corrected by the slip conditions alone as considered by earlier researchers. C1 VIGYAN INC,HAMPTON,VA 23666. RP GUPTA, RN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 23 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 751 EP 758 DI 10.2514/3.26508 PG 8 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400006 ER PT J AU MOORE, FG WILCOX, F HYMER, T AF MOORE, FG WILCOX, F HYMER, T TI BASE DRAG PREDICTION ON MISSILE CONFIGURATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB New wind-tunnel data have been taken, and a new empirical model has been developed for predicting base drag on missile configurations. The new wind-tunnel data were taken at NASA Langley Research Center in the unitary wind tunnel at Mach numbers from 2.0 to 4.5, angles of attack to 16 deg, fin control deflections up to 20 deg, fin thickness-to-chord ratio of 0.05 to 0.15, and fin locations flush with the base to two chord lengths upstream of the base. The newly developed empirical model uses these data along with previous wind-tunnel data. It estimates base drag as a function of all the preceding variables along with boattail and power-on or power-off effects. In comparing the new empirical model to that used in the former aeroprediction code, the new model gives improved accuracy compared to wind-tunnel data. The new model also is more robust due to inclusion of additional variables. On the other hand, additional wind-tunnel data are needed to validate or modify the current empirical model in areas where data are not available. C1 NASA,LANGLEY RES CTR,HIGH SPEED AERODYNAM BRANCH,HAMPTON,VA 23665. RP MOORE, FG (reprint author), USN,CTR SURFACE WARFARE,DEPT WEAPONS SYST,DAHLGREN DIV,DAHLGREN,VA 22448, USA. NR 27 TC 5 Z9 5 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 759 EP 765 DI 10.2514/3.26509 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400007 ER PT J AU STANLEY, DO ENGELUND, WC LEPSCH, RA MCMILLIN, M WURSTER, KE POWELL, RW GUINTA, T UNAL, R AF STANLEY, DO ENGELUND, WC LEPSCH, RA MCMILLIN, M WURSTER, KE POWELL, RW GUINTA, T UNAL, R TI ROCKET-POWERED SINGLE-STAGE VEHICLE CONFIGURATION SELECTION AND DESIGN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID LAUNCH VEHICLES; SYSTEM AB A reusable rochet-powered, single-stage launch vehicle has been designed as a part of the Advanced Manned Launch System study to examine options for a next-generation manned space transportation system. The configuration selection process used a response surface methodology for multidisciplinary optimization. The methodology was used to determine the minimum dry weight entry vehicle to meet constraints on landing velocity and on subsonic, supersonic, and hypersonic trim and stability. Once the optimum configuration was determined, a multidisciplinary conceptual vehicle design was performed. This paper presents the results of the configuration selection methodology and summarizes the overall conceptual design process with special attention given to the individual disciplines of weights/sizing, structures/materials, configuration, flight mechanics, aerodynamics, aeroheating, propulsion, and operations. C1 VIRGINIA POLYTECH INST & STATE UNIV,BLACKSBURG,VA 24061. OLD DOMINION UNIV,DEPT ENGN MANAGEMENT,NORFOLK,VA 23529. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST & CONCEPTS,HAMPTON,VA 23665, USA. NR 25 TC 4 Z9 4 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 792 EP 798 DI 10.2514/3.26514 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400012 ER PT J AU TAUBER, M WERCINSKI, P HENLINE, W PATERSON, J YANG, L AF TAUBER, M WERCINSKI, P HENLINE, W PATERSON, J YANG, L TI URANUS AND NEPTUNE ATMOSPHERIC-ENTRY PROBE STUDY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Entry trajectories, decelerations, and heating and heat shielding requirements of probes entering the atmospheres of Uranus and Neptune at velocities up to 26.5 km/s were studied. Much of the Galileo Jupiter probe technology was applicable to these outer-planet probes; therefore, the same configuration was used. Steep (ballistic) entry night-path angles were needed to facilitate communication from the probes to the spacecraft during atmospheric descent. The Galileo probe's 400 g maximum deceleration structural design was used to define the maximum entry angles for the Uranus and Neptune probes. The carbon phenolic heat shield material used on the Galileo and the successful Pioneer-Venus probes was selected. Turbulent boundary-layer convection dominated the heating of the Uranus and Neptune probes; radiative heating was negligible by comparison. The peak heating rates were found to be about 6 kW/cm(2), or approximately 25% of the Galileo probe's expected maximum value. The forebody heat shield mass fractions for these outer-planet probes were found to vary from about 0.08 to 0.16 for entry velocities from 22 to 26.5 km/s. By comparison, the Pioneer-Venus probes' heat shield mass fractions ranged from 0.10 to 0.13, and the Galileo probe's forebody value is 0.43. C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP TAUBER, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 5 Z9 5 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 799 EP 805 DI 10.2514/3.26515 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400013 ER PT J AU RICHARDSON, JA TOWNSEND, JS AF RICHARDSON, JA TOWNSEND, JS TI EXAMINING THE ACCURACY OF SPACE-SHUTTLE SUPPORT LOADS USING PROBABILISTIC ANALYSIS TECHNIQUES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB To understand unexpectedly erratic load measurements in the launch pad supports for the Space Shuttle, the sensitivities of the load cells in the supports were analyzed using simple probabilistic techniques. NASA engineers use the loads in the Shuttle's supports to calculate critical stresses in the Shuttle vehicle just before liftoff. The support loads are measured with ''load cells,'' which actually are structural components of the mobile launch platform that have been instrumented with strain gauges. Although these load cells adequately measure vertical loads, horizontal load measurements have been erratic. Load measurements were simulated in this study using Monte Carlo simulation procedures. The simulation studies showed that the support loads are sensitive to small deviations in strain and calibration. In their current configuration, the load cells will not measure loads with sufficient accuracy to reliably calculate stresses in the Shuttle vehicle. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB,HUNTSVILLE,AL 35812. RP RICHARDSON, JA (reprint author), UNIV ALABAMA,DEPT CIVIL ENGN,TUSCALOOSA,AL 35487, USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 814 EP 820 DI 10.2514/3.26517 PG 7 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400015 ER PT J AU ROBINSON, JC STANLEY, DO AF ROBINSON, JC STANLEY, DO TI STRUCTURAL AND LOADS ANALYSIS OF A 2-STAGE REUSABLE MANNED LAUNCH SYSTEM SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The conceptual design of a rocket-powered, two-stage, fully reusable launch vehicle has been performed as a part of the NASA's Advanced Manned Launch System study. This paper summarizes the structural design and load analysis of this vehicle. The method used to determine the structural weights consists of generating a finite-element model for each vehicle, selecting a set of critical loading conditions, determining the loads on the model caused by those conditions, determining the model response, and changing the sizes of individual elements to obtain a safe structure. The integrated loads on the vehicle were obtained from a three-degree-of-freedom trajectory analysis. C1 OLD DOMINION UNIV,RES FDN,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23681. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 821 EP 829 DI 10.2514/3.26518 PG 9 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400016 ER PT J AU VIGUE, Y LICHTEN, SM MUELLERSCHOEN, RJ BLEWITT, G HEFLIN, MB AF VIGUE, Y LICHTEN, SM MUELLERSCHOEN, RJ BLEWITT, G HEFLIN, MB TI IMPROVED GPS SOLAR-RADIATION PRESSURE MODELING FOR PRECISE ORBIT DETERMINATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Data collected from a worldwide 1992 experiment have been processed at the Jet Propulsion Laboratory to determine precise orbits for the satellites of the Global Positioning System (GPS). The goal of this study was to improve satellite force modeling in order to achieve centimeter-level accuracy for global geocentric coordinates. A filtering technique has been tested to improve modeling of solar radiation pressure parameters for GPS satellites. The new approach improves orbit quality for eclipsing GPS satellites by a factor of 2, with typical results in the range of 25-50 cm. C1 CALTECH,JET PROP LAB,EARTH ORBITER SYST GRP,SECT 335,PASADENA,CA 91109. CALTECH,JET PROP LAB,SATELLITE GEODESY & GEODYNAM GRP,SECT 335,PASADENA,CA 91109. RP VIGUE, Y (reprint author), CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 8 TC 6 Z9 6 U1 1 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 830 EP 833 DI 10.2514/3.26519 PG 4 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400017 ER PT J AU VIGUE, Y SCHUTZ, BE ABUSALI, PAM AF VIGUE, Y SCHUTZ, BE ABUSALI, PAM TI THERMAL FORCE MODELING FOR GLOBAL POSITIONING SYSTEM SATELLITES USING THE FINITE-ELEMENT METHOD SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Geophysical applications of the Global Positioning System (GPS) require the capability to estimate and propagate satellite orbits with high precision. An accurate model of all the forces acting on a satellite is an essential part of achieving high orbit accuracy. Methods of analyzing the perturbation due to thermal radiation and determining its effects on the long-term orbital behaviour of GPS satellites are presented. The thermal imbalance force, a nongravitational orbit perturbation previously considered negligible, is the focus of this paper. The Earth's shadowing of a satellite in orbit causes periodic changes in the satellite's thermal environment. Simulations show that neglecting thermal imbalance in the satellite force model gives orbit errors larger than 10 m over several days for eclipsing satellites. This orbit mismodeling can limit accuracy in orbit determination and in estimation of baselines used for geophysical applications. C1 UNIV TEXAS,CTR SPACE RES,AUSTIN,TX 78712. RP VIGUE, Y (reprint author), CALTECH,JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 17 TC 7 Z9 7 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 855 EP 859 DI 10.2514/3.26523 PG 5 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400021 ER PT J AU WANG, J LEUNG, P GARRETT, H MURPHY, G AF WANG, J LEUNG, P GARRETT, H MURPHY, G TI MULTIBODY-PLASMA INTERACTIONS - CHARGING IN THE WAKE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID VOLTAGE SPACE PLATFORMS; SHUTTLE; FLOW AB Multibody-plasma interactions occur when two or more charged bodies simultaneously interact with the surrounding plasma as well as each other. This paper concerns a basic type of such interactions in the ionosphere: the charging of a free flyer in the wake of a large plate structure. Computer particle simulations are coupled with charging calculations to obtain the free-flyer charging potentials in the wake of a plate, which can be either floating or biased. The conditions under which multibody interaction occurs are identified. It is shown that a severe charging zone exists in the near wake of a large floating plate under the nightside auroral-electron condition. Whether the plate structure is biased or floating, a large potential difference always exists between the plate and a free flyer docking in the wake. The effects of this wake charging on spacecraft docking operations are discussed. RP WANG, J (reprint author), CALTECH,JET PROP LAB,TECH STAFF,4800 OAK GROVE DR,MS301-460,PASADENA,CA 91109, USA. NR 27 TC 10 Z9 10 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 889 EP 894 DI 10.2514/3.26528 PG 6 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400026 ER PT J AU HILLARD, GB AF HILLARD, GB TI MEASURED PLASMA CONDUCTIVITY OF ZINC-OXIDE-BASED THERMAL CONTROL COATINGS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note RP HILLARD, GB (reprint author), NASA,LEWIS RES CTR,DIV POWER TECHNOL,SPACE ENVIRONM EFFECTS BRANCH,CLEVELAND,OH 44135, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD SEP-OCT PY 1994 VL 31 IS 5 BP 910 EP 912 DI 10.2514/3.26532 PG 3 WC Engineering, Aerospace SC Engineering GA QA684 UT WOS:A1994QA68400030 ER PT J AU RODAK, EM TAYLOR, RJ HIRSCH, DB LINLEY, LJ AF RODAK, EM TAYLOR, RJ HIRSCH, DB LINLEY, LJ TI EFFECTS OF SAMPLE AND TEST VARIABLES ON ELECTRICAL WIRE INSULATION FLAMMABILITY SO JOURNAL OF TESTING AND EVALUATION LA English DT Article DE WIRE INSULATION; FLAMMABILITY; OXYGEN-ENRICHED ATMOSPHERES; TEST METHODS AB A new test method has been adopted to evaluate the flammability of electrical wire insulation materials. In this test, wire insulation is exposed to an external ignition source while the electrical conductor is internally heated by an electric current. The repeatability of the test and the effects of wire gage and insulation thickness, internal wire temperature, and sample orientation on the wire insulation flammability were evaluated. Experimental results showed that the new test is a practical and repeatable method for evaluating flammability of wire insulation materials. C1 ALLIED SIGNAL TECH SERV CORP,LAS CRUCES,NM. RP RODAK, EM (reprint author), NASA,JOHNSON SPACE CTR,WHITE SANDS TEST FACIL,LAS CRUCES,NM 88004, USA. NR 10 TC 3 Z9 3 U1 1 U2 1 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0090-3973 J9 J TEST EVAL JI J. Test. Eval. PD SEP PY 1994 VL 22 IS 5 BP 447 EP 450 PG 4 WC Materials Science, Characterization & Testing SC Materials Science GA PJ305 UT WOS:A1994PJ30500007 ER PT J AU MARCHIONINI, G BARLOW, D HILL, L AF MARCHIONINI, G BARLOW, D HILL, L TI EXTENDING RETRIEVAL STRATEGIES TO NETWORKED ENVIRONMENTS - OLD WAYS, NEW WAYS, AND A CRITICAL-LOOK AT WAIS SO JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE LA English DT Note ID SEARCH C1 NASA,SCI & TECH INFORMAT PROGRAM,WASHINGTON,DC 20546. RP MARCHIONINI, G (reprint author), UNIV MARYLAND,COLL LIB & INFORMAT SERV,COLLEGE PK,MD 20742, USA. NR 6 TC 12 Z9 10 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0002-8231 J9 J AM SOC INFORM SCI JI J. Am. Soc. Inf. Sci. PD SEP PY 1994 VL 45 IS 8 BP 561 EP 564 DI 10.1002/(SICI)1097-4571(199409)45:8<561::AID-ASI4>3.0.CO;2-C PG 4 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA PE434 UT WOS:A1994PE43400004 ER PT J AU COPLEY, J LINDBERG, J CROCKETT, S HARPER, J WADE, C AF COPLEY, J LINDBERG, J CROCKETT, S HARPER, J WADE, C TI ASSESSMENT OF POSTOPERATIVE RENAL-FUNCTION (RF) FOLLOWING ORTHOTOPIC LIVER-TRANSPLANTATION (OLT) IN PATIENTS (PTS) WITH ELEVATED BLOOD UREA NITROGEN (BUN) TO CREATININE (CR) RATIOS SO JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY LA English DT Meeting Abstract C1 ALTON OCHSNER MED FDN & OCHSNER CLIN,NEW ORLEANS,LA 70121. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 1046-6673 J9 J AM SOC NEPHROL JI J. Am. Soc. Nephrol. PD SEP PY 1994 VL 5 IS 3 BP 390 EP 390 PG 1 WC Urology & Nephrology SC Urology & Nephrology GA PG771 UT WOS:A1994PG77100577 ER PT J AU WENG, HY LAU, KM AF WENG, HY LAU, KM TI WAVELETS, PERIOD-DOUBLING, AND TIME-FREQUENCY LOCALIZATION WITH APPLICATION TO ORGANIZATION OF CONVECTION OVER THE TROPICAL WESTERN PACIFIC SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID TRANSFORMS; CLUSTERS AB In this paper, preliminary results in using orthogonal and continuous wavelet transform (WT) to identify period doubling and time-frequency localization in both synthetic and real data are presented. First, the Haar WT is applied to synthetic time series derived from a simple nonlinear dynamical system-a first-order quadratic difference equation. Second, the complex Morlet WT is used to study the time-frequency localization of tropical convection based on a high-resolution Japanese Geostationary Meteorological Satellite infrared (IR) radiance dataset. The Haar WT of the synthetic time series indicates the presence and distinct separation of multiple frequencies in a period-doubling sequence. The period-doubling process generates a multiplicity of intermediate frequencies, which are manifested in the nonuniformity in time with respect to the phase of oscillations in the lower frequencies. Wavelet transform also enables the detection of extremely weak signals in higher-order subharmonics resulting from the period-doubling bifurcations. These signals are either undetected or considered statistically insignificant by traditional Fourier analysis. The Morlet WT of the IR radiance dataset indicates the presence of multiple timescales, which are localized in both frequency and time. There are two regimes in the variation of IR radiance, corresponding to the wet and dry periods. Multiple timescales, ranging from semidiurnal, diurnal, synoptic, to intraseasonal with embedding structures, are active in the wet regime. In particular, synoptic variability is more prominent during the wet phase of an intensive intraseasonal cycle. These are not only consistent with, but also show more details than, previous findings by using other techniques. The phase-locking relationships among the oscillations with different time-scales suggest that both synoptic and intraseasonal variations may be mixed oscillations due to the interaction of self-excited oscillations in the tropical atmosphere and external forcings such as annual and diurnal solar radiation variations. Both examples show that WT is a powerful tool for analysis of phenomena involving multiscale interactions that exhibit localization in both frequency and time. A discussion on the caveats in the use of WT in geophysical data analysis is also presented. RP WENG, HY (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20770, USA. RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 31 TC 152 Z9 171 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD SEP 1 PY 1994 VL 51 IS 17 BP 2523 EP 2541 DI 10.1175/1520-0469(1994)051<2523:WPDATL>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PE440 UT WOS:A1994PE44000004 ER PT J AU REZAIESEREJ, S OUTLAW, RA AF REZAIESEREJ, S OUTLAW, RA TI THERMAL-DESORPTION OF CO AND H2 FROM DEGASSED 304 AND 347 STAINLESS-STEEL SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID SURFACES; SS-304 AB Thermal desorption spectroscopy (TDS), along with Auger electron spectroscopy, was used to study the desorption of H-2 and CO from baked 304 and 347 stainless-steel samples exposed only to residual gases. Both 347 and 304 samples gave identical TDS spectra. The spectra for CO contained a sharp leading peak centered in the temperature range 410-440-degrees-C and an exponentially increasing part for temperatures higher than 500-degrees-C, with a small peak around 600-degrees-C appearing as a shoulder. The leading peak followed a second-order desorption behavior with an activation energy of 28 +/- 2 kcal/mol, suggesting that the rate-limiting step for this peak is most likely a surface reaction that produces the CO molecules in the surface layer. The amount of desorbed CO corresponding to this peak was approximately 0.5 x 10(14) molecules/cm2. The exponentially rising part of the CO spectrum appeared to originate from a bulk diffusion process. The TDS spectrum for H-2 consisted of a main peak centered also in the temperature range 410-440-degrees-C, with two small peaks appearing as shoulders at approximately 500 and 650-degrees-C. The main peak in this case also displayed a second-order behavior with an activation energy of 14 +/- 2 kcal/mol. The amount of desorbed H-2, approximately 1.9 x 10(15) molecules/cm2, appeared to be independent of the concentration of hydrogen in the bulk, indicating that the majority of the desorbed H-2 originated from the surface layer. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP REZAIESEREJ, S (reprint author), OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529, USA. NR 22 TC 13 Z9 13 U1 2 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD SEP-OCT PY 1994 VL 12 IS 5 BP 2814 EP 2819 DI 10.1116/1.578949 PG 6 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA PH791 UT WOS:A1994PH79100033 ER PT J AU RICHARDSON, LL BUISSON, D LIU, CJ AMBROSIA, V AF RICHARDSON, LL BUISSON, D LIU, CJ AMBROSIA, V TI THE DETECTION OF ALGAL PHOTOSYNTHETIC ACCESSORY PIGMENTS USING AIRBORNE VISIBLE-INFRARED IMAGING SPECTROMETER (AVIRIS) SPECTRAL DATA SO MARINE TECHNOLOGY SOCIETY JOURNAL LA English DT Article ID PERFORMANCE LIQUID-CHROMATOGRAPHY; RESOLUTION DERIVATIVE SPECTRA AB Image data from NASA's high-altitude flown hyperspectral sensor AVIRIS (Airborne Visible-Infrared Imaging Spectrometer) were acquired of salt evaporation ponds near South San Francisco Bay The ponds contained a dense biomass of algae and/or photosynthetic bacteria, and were highly colored. The image data were processed as spectra (derived from radiance data averaged from individual ponds), and analyzed for detection of algal and photosynthetic bacterial accessory pigments by comparison with absorbance and reflectance spectra, supported by HPLC pigment analysis, of known algae, photosynthetic bacteria and pigment standards. The overall spectral characteristics of the ponds allowed identification as to population composition, corroborated by salinity data and parallel research on hypersaline ponds in Baja California, Mexico. Fourth derivative analysis of the spectra was used to detect diagnostic peaks of specific pigments. A was determined that chlorophyll and phycobilin pigments were detectable in the AVIRIS data, but specific carotenoids, although detectable as present, could not be resolved due to extensive spectral overlap. C1 FLORIDA INT UNIV, DRINKING WATER RES CTR, MIAMI, FL 33199 USA. FLORIDA INT UNIV, DEPT ELECT & COMP ENGN, MIAMI, FL 33199 USA. NASA, AMES RES CTR, JCWS INC, MOFFETT FIELD, CA 94035 USA. RP FLORIDA INT UNIV, DEPT BIOL SCI, MIAMI, FL 33199 USA. NR 16 TC 28 Z9 30 U1 0 U2 1 PU MARINE TECHNOLOGY SOC INC PI COLUMBIA PA 5565 STERRETT PLACE, STE 108, COLUMBIA, MD 21044 USA SN 0025-3324 EI 1948-1209 J9 MAR TECHNOL SOC J JI Mar. Technol. Soc. J. PD FAL PY 1994 VL 28 IS 3 BP 10 EP 21 PG 12 WC Engineering, Ocean; Oceanography SC Engineering; Oceanography GA QJ558 UT WOS:A1994QJ55800002 ER PT J AU NOOR, AK VENNERI, SL AF NOOR, AK VENNERI, SL TI FUTURE FLIGHT SO MECHANICAL ENGINEERING LA English DT Article RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0025-6501 J9 MECH ENG JI Mech. Eng. PD SEP PY 1994 VL 116 IS 9 BP 86 EP 88 PG 3 WC Engineering, Mechanical SC Engineering GA PG177 UT WOS:A1994PG17700023 ER PT J AU TREIMAN, AH MCKAY, GA BOGARD, DD MITTLEFEHLDT, DW WANG, MS KELLER, L LIPSCHUTZ, ME LINDSTROM, MM GARRISON, D AF TREIMAN, AH MCKAY, GA BOGARD, DD MITTLEFEHLDT, DW WANG, MS KELLER, L LIPSCHUTZ, ME LINDSTROM, MM GARRISON, D TI COMPARISON OF THE LEW88516 AND ALHA77005 MARTIAN METEORITES - SIMILAR BUT DISTINCT SO METEORITICS LA English DT Article ID ALLAN HILLS 77005; SHOCK METAMORPHISM; SNC METEORITES; SHERGOTTITE; CHONDRITES; SYSTEMATICS; ANTARCTICA; ORIGIN; EARTH; AGES AB By mineral and bulk compositions, the Lewis Cliff (LEW) 88516 meteorite is quite similar to the ALHA77005 martian meteorite. These two meteorites are not paired because their mineral compositions are distinct, they were found 500 km apart in ice fields with different sources for meteorites, and their terrestrial residence ages are different. Minerals in LEW88516 include: olivine, pyroxenes (low- and high-Ca), and maskelynite (after plagioclase); and the minor minerals chromite, whitlockite, ilmenite, and pyrrhotite. Mineral grains in LEW88516 range up to a few mm. Texturally, the meteorite is complex, with regions of olivine and chromite poikilitically enclosed in pyroxene, regions of interstitial basaltic texture, and glass-rich (shock) veinlets. Olivine compositions range from Fo64 to Fo70, (avg. Fo67), more ferroan and with more variation than in ALHA77005 (fo69 to Fo73). Pyroxene compositions fall between En77Wo4 and En65Wo15 and in clusters near En63 Wo9 and En53Wo33, on average more magnesian and with more variation than in ALHA77005. Shock features in LEW88516 range from weak deformation through complete melting. Bulk chemical analyses by modal recombination of electron microprobe analyses, instrumental neutron activation, and radiochemical neutron activation confirm that LEW88516 is more closely related to ALHA77005 than to other known martian meteorites. Key element abundance ratios are typical of martian meteorites, as is its nonchondritic rare earth pattern. Differences between the chemical compositions of LEW88516 and ALHA77005 are consistent with slight differences in the proportions of their constituent minerals and not from fundamental petrogenetic differences. Noble gas abundances in LEW88516, like those in ALHA77005, show modest excesses of Ar-40 and Xe-129 from trapped (shock-implanted) gas. As with other ALHA77005 and the shergottite martian meteorites (except EETA79001), noble gas isotope abundances in LEW88516 are consistent with exposure to cosmic rays for 2.5-3 Ma. The absence of substantial effects of shielding from cosmic rays suggest LEW88516 spent this time as an object no larger than a few cm in diameter. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. NR 47 TC 86 Z9 92 U1 1 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1994 VL 29 IS 5 BP 581 EP 592 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PF653 UT WOS:A1994PF65300005 ER PT J AU ZOLENSKY, ME BARRETT, RA AF ZOLENSKY, ME BARRETT, RA TI COMPOSITIONAL VARIATIONS OF OLIVINES AND PYROXENES IN CHONDRITIC INTERPLANETARY DUST PARTICLES SO METEORITICS LA English DT Article ID DISSOLUTION; KINETICS AB We report here analyses of olivines and pyroxenes, and petrofabrics of 27 chondritic interplanetary dust particles (IDPs), comparing those from anhydrous and hydrous types. Approximately 40% of the hydrous particles contain diopside, a probable indicator of parent body thermal metamorphism, while this mineral is rarely present in the anhydrous particles. Based on this evidence, we find that hydrous and anhydrous IDPs are, in general, not directly related, and we conclude that olivine and pyroxene major-element compositions can be used to help discriminate between IDPs that are (1) predominantly nebular condensates, and lately resided in anhydrous or icy (no liquids) primitive parent bodies, and (2) those originating from more geochemically active parent bodies (probably hydrous and anhydrous asteroids). 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 27 TC 31 Z9 31 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1994 VL 29 IS 5 BP 616 EP 620 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PF653 UT WOS:A1994PF65300008 ER PT J AU PAQUE, JM BECKETT, JR BARBER, DJ STOLPER, EM AF PAQUE, JM BECKETT, JR BARBER, DJ STOLPER, EM TI A NEW TITANIUM-BEARING CALCIUM ALUMINOSILICATE PHASE .1. METEORITIC OCCURRENCES AND FORMATION IN SYNTHETIC SYSTEMS SO METEORITICS LA English DT Note ID AL-RICH INCLUSIONS; CRYSTALLIZATION SEQUENCES; REFRACTORY INCLUSIONS; ALLENDE METEORITE; CHONDRITE; MELILITE; ORIGIN AB A new titanium-bearing calcium aluminosilicate mineral has been identified in coarse-grained calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites. The formula for this phase, which we have temporarily termed ''UNK,'' is Ca3Ti(Al,Ti)2(Si,Al)3O14, and it is present in at least 8 of the 20 coarse-grained CAIs from the Allende CV3 chondrite examined as part of this project. The phase occurs in Types A and B1 inclusions as small tabular crystals oriented along two mutually perpendicular planes in melilite. UNK crystallizes from melts in dynamic crystallization experiments conducted in air from four bulk compositions modeled after Types A, B1, B2 and C inclusions. Cooling rates resulting in crystallization of UNK ranged from 0.5 to 200-degrees-C/h from maximum (initial) temperatures of 1375 to 1580-degrees-C. Only below 1190-degrees-C does UNK itself begin to crystallize. To first order, the presence or absence of UNK from individual experiments can be understood in terms of the compositions of residual melts and nucleation probabilities. Compositions of synthetic and meteoritic UNK are very similar in terms of major oxides, differing only in the small amounts of trivalent Ti(7-13% of total Ti) in meteoritic samples. UNK crystallized from the Type A analog is similar texturally to that found in CAIs, although glass, which is typically associated with synthetic UNK, is not observed in meteoritic occurrences. A low Ti end-member of UNK (''Si-UNK'') with a composition near that of Ca3Al2Si4O14 was produced in a few samples from the Type B1 analog. This phase has not been found in the meteoritic inclusions. C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. UNIV ESSEX,DEPT PHYS,COLCHESTER CO4 3SQ,ESSEX,ENGLAND. RP PAQUE, JM (reprint author), NASA,AMES RES CTR,SETI INST,MS 24411,MOFFETT FIELD,CA 94035, USA. NR 24 TC 12 Z9 12 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD SEP PY 1994 VL 29 IS 5 BP 673 EP 682 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PF653 UT WOS:A1994PF65300017 ER PT J AU OKEEFE, JA AF OKEEFE, JA TI THE ORIGIN OF TEKTITES - REPLY SO METEORITICS LA English DT Note RP OKEEFE, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 681,GREENBELT,MD 20771, USA. NR 18 TC 4 Z9 4 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 SEP PY 1994 VL 29 IS 5 BP 743 EP 746 PG 4 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PF653 UT WOS:A1994PF65300026 ER PT J AU HEARN, CP AF HEARN, CP TI STUDY EXAMINES WINDOWING EFFECTS ON VNA MEASUREMENTS SO MICROWAVES & RF LA English DT Article RP HEARN, CP (reprint author), NASA,LANGLEY RES CTR,MS 490,HAMPTON,VA 23681, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0745-2993 J9 MICROWAVES RF JI Microw. RF PD SEP PY 1994 VL 33 IS 9 BP 108 EP 110 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PH666 UT WOS:A1994PH66600013 ER PT J AU BAYLISS, A BELYTSCHKO, T KULKARNI, M LOTTCRUMPLER, DA AF BAYLISS, A BELYTSCHKO, T KULKARNI, M LOTTCRUMPLER, DA TI ON THE DYNAMICS AND THE ROLE OF IMPERFECTIONS FOR LOCALIZATION IN THERMOVISCOPLASTIC MATERIALS SO MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING LA English DT Article ID ADIABATIC SHEAR BANDS AB We employ an adaptive Chebyshev pseudo-spectral method for the computation of adiabatic shear bands in materials with temperature-dependent viscoplastic materials coupled with heat conduction. The method allows very high resolution of the spatial structure of the band with a relatively small number of computational degrees of freedom. The method is used to study the dynamics of band formation and the spatial structure of the resulting bands with special emphasis on the role of the imperfection. We find that the spatial structure of the band can be characterized by an inner band, in which the field quantities, (e.g. viscoplastic strain or temperature) attain a nearly constant large value, and an outer band connecting the inner band to the underformed portion of the specimen. The outer band is sensitive to the spatial structure of the imperfection while the inner band is sensitive to the structure of the imperfection during the early stages of severe localization but not during the later stages. The dynamics of shear-band formation during severe localization can be divided into three stages. In the first stage (stage A), the band narrows but the spatial extent of the inner band is sensitive to the imperfection. In the second stage (stage B) the band continues to narrow, but the spatial structure of the inner band is insensitive to the imperfection. A length scale for the smallest width of the temperature band is derived and shown to be in reasonable agreement with the computations. In the third stage (stage C), the band widens as diffusion and elastic effects become important. A residual effect of the imperfection persists in the outer band throughout all three stages. C1 NASA,LARC,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23681. RP BAYLISS, A (reprint author), NORTHWESTERN UNIV,EVANSTON,IL 60208, USA. RI Belytschko, Ted/B-6710-2009; Bayliss, Alvin/B-7337-2009 NR 20 TC 20 Z9 20 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0965-0393 J9 MODEL SIMUL MATER SC JI Model. Simul. Mater. Sci. Eng. PD SEP PY 1994 VL 2 IS 5 BP 941 EP 964 DI 10.1088/0965-0393/2/5/001 PG 24 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA PL438 UT WOS:A1994PL43800001 ER PT J AU SHENK, WE HOPE, WA AF SHENK, WE HOPE, WA TI THE EFFECTS OF TIME COMPOSITING ON OBTAINING CLEAR-SKY COVERAGE FOR INFRARED TEMPERATURE AND MOISTURE PROFILING FROM GEOSYNCHRONOUS ORBIT SO MONTHLY WEATHER REVIEW LA English DT Note AB The impact of time compositing on infrared profiling from geosynchronous orbit was evaluated for two convective outbreak cases. Time compositing is the accumulation of the data from several successive images taken at short intervals to provide a single held of measurements with the temporal resolution equal to the time to take all of the images. This is especially effective when the variability of the measurement is slow compared to the image interval. Time compositing should be able to reduce the interference of clouds for infrared measurements since clouds move and change. The convective outbreak cases were on 4 and 21 May 1990 over the eastern Midwest and southeastern United States, respectively. Geostationary Operational Environmental Satellite imagery was used to outline clear areas at hourly intervals by two independent analysts. Time compositing was done every 3 h (1330-1530 UTC; 1630-1830 UTC) and over the full 5-h period. For both cases, a significant increase in coverage was measured with each 3-h compositing (about a factor of 2) and a further increase over the full period (approximately a factor of 3). The increase was especially useful in areas of broken cloud cover where large gaps between potential profiling areas on each image were reduced. To provide information on measurement variability over local areas, the regions where the clear-area analyses were done were subdivided into 0.5 degrees latitude-longitude boxes, and if same portion of each box was clear. it was assumed that at least one profile could be obtained within the box. In the largest clear areas, at least some portion was clear every hour. Even in the cloudier regions, multiple clear looks were possible during the entire period. RP SHENK, WE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MESOSCALE DYNAM & PRECIPITAT BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 1994 VL 122 IS 9 BP 2192 EP 2201 DI 10.1175/1520-0493(1994)122<2192:TEOTCO>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PE318 UT WOS:A1994PE31800014 ER PT J AU KROEGER, RA INDERHEES, SE JOHNSON, WN KINZER, RL KURFESS, JD GEHRELS, N AF KROEGER, RA INDERHEES, SE JOHNSON, WN KINZER, RL KURFESS, JD GEHRELS, N TI CHARGE DIVISION READOUT OF A 2-DIMENSIONAL GERMANIUM STRIP DETECTOR SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 3rd London Conference on Position Sensitive Detectors CY SEP 06-10, 1993 CL BRUNEL UNIV, LONDON, ENGLAND HO BRUNEL UNIV ID RADIATION AB Germanium strip detectors combine superior spectroscopy typical of germanium detectors with good spatial resolution. Our work has been to develop a 2-dimensional position readout of a 5 x 5 strip X-Y detector. The prototype device uses two capacitive charge division strings. Each string is read out by two 13-bit ADCs, one on each end of the string. The four data channels are stored as an event list for subsequent processing. We form a response map over the detector surface in order to locate the position of each interaction with the spatial resolution of the strip pitch, in our case 9 mm. Cross-talk and non-linearities are removed using the response map. Energy resolution of 5-6 keV FWHM is achieved between 60 and 662 keV across the full surface of the detector. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KROEGER, RA (reprint author), USN,RES LAB,WASHINGTON,DC 20375, USA. RI Gehrels, Neil/D-2971-2012; Johnson, Neil/G-3309-2014 NR 10 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD SEP 1 PY 1994 VL 348 IS 2-3 BP 507 EP 509 DI 10.1016/0168-9002(94)90789-7 PG 3 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA PF645 UT WOS:A1994PF64500059 ER PT J AU CHAI, JC LEE, HOS PATANKAR, SV AF CHAI, JC LEE, HOS PATANKAR, SV TI TREATMENT OF IRREGULAR GEOMETRIES USING A CARTESIAN COORDINATES FINITE-VOLUME RADIATION HEAT-TRANSFER PROCEDURE SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article ID RECTANGULAR ENCLOSURES AB This article presents a blocked-off-region procedure to model radiative transfer in irregular geometries using a Cartesian coordinates finite-volume method (FTM). Straight-edged, inclined and curved boundaries can be treated. It is capable of handling participating or transparent media enclosed by black or reflecting walls. With this procedure, irregular geometries can be specified through the problem specification portion of the program. Four test problems are used to show that the procedure is capable of reproducing available results for inclined and curved walls, transparent, nonscattering, and anisotropically scattering media. C1 UNIV MINNESOTA,DEPT MECH ENGN,MINNEAPOLIS,MN 55455. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RI Chai, John/A-3764-2010 NR 15 TC 85 Z9 86 U1 1 U2 7 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD SEP PY 1994 VL 26 IS 2 BP 225 EP 235 DI 10.1080/10407799408914927 PG 11 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA PG382 UT WOS:A1994PG38200007 ER PT J AU Cai, XC Gropp, WD Keyes, DE AF Cai, Xiao-Chuan Gropp, William D. Keyes, David E. TI A Comparison of Some Domain Decomposition and ILU Preconditioned Iterative Methods for Nonsymmetric Elliptic Problems SO NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS LA English DT Article DE Domain decomposition; Preconditioning; Iterative methods; Nonsymmetric and/or indefinite elliptic problems AB In recent years, competitive domain-decomposed preconditioned iterative techniques of Krylov-Schwarz type have been developed for nonsymmetric linear elliptic systems. Such systems arise when convection-diffusion-reaction problems from computational fluid dynamics or heat and mass transfer are linearized for iterative solution. Through domain decomposition, a large problem is divided into many smaller problems whose requirements for coordination can be controlled to allow effective solution on parallel machines. A central question is how to choose these small problems and how to arrange the order of their solution. Different specifications of decomposition and solution order lead to a plethora of algorithms possessing complementary advantages and disadvantages. In this report we compare several methods, including the additive Schwarz algorithm, the classical multiplicative Schwarz algorithm, an accelerated multiplicative Schwarz algorithm, the tile algorithm, the CGK algorithm, the CSPD algorithm, and also the popular global ILU-family of preconditioners, on some nonsymmetric or indefinite elliptic model problems discretized by finite difference methods. The preconditioned problems are solved by the unrestarted GMRES method. A version of the accelerated multiplicative Schwarz method is a consistently good performer. C1 [Cai, Xiao-Chuan] Univ Colorado, Dept Comp Sci, Boulder, CO 80309 USA. [Gropp, William D.] Argonne Natl Lab, Div Math & Comp Sci, Argonne, IL 60439 USA. [Keyes, David E.] Old Dominion Univ, Dept Comp Sci, Norfolk, VA 23529 USA. [Keyes, David E.] NASA Langley Res Ctr, Inst Comp Applicat Sci & Eng, Hampton, VA 23681 USA. RP Cai, XC (reprint author), Univ Colorado, Dept Comp Sci, Boulder, CO 80309 USA. FU National Science Foundation; Kentucky EPSCoR Program [STI-9108764]; Applied Mathematical Sciences subprogram of the Office of Energy Research, US. Department of Energy [W-31-109-Eng-38]; NSF [ECS-8957475]; National Aeronautics and Space Administration under NASA [NAS1-18605] FX The work of first author was supported in part by the National Science Foundation and the Kentucky EPSCoR Program under grant STI-9108764. The work of second author was supported in part by the Applied Mathematical Sciences subprogram of the Office of Energy Research, US. Department of Energy, under Contract W-31-109-Eng-38. The work of third author was supported in part by the NSF under contract ECS-8957475 and by the National Aeronautics and Space Administration under NASA Contract NAS1-18605 while the author was in residence at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, VA 23665. NR 40 TC 5 Z9 5 U1 0 U2 1 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 1070-5325 EI 1099-1506 J9 NUMER LINEAR ALGEBR JI Numer. Linear Algebr. Appl. PD SEP-OCT PY 1994 VL 1 IS 5 BP 477 EP 504 DI 10.1002/nla.1680010504 PG 28 WC Mathematics, Applied; Mathematics SC Mathematics GA V32QC UT WOS:000208964700003 ER PT J AU HEMMATI, H LESH, JR AF HEMMATI, H LESH, JR TI 3.5-W Q-SWITCHED 532-NM NDYAG LASER-PUMPED WITH FIBER-COUPLED DIODE-LASERS SO OPTICS LETTERS LA English DT Article ID ND-YAG LASER; SOLID-STATE LASERS; MODE; CW AB A diode-pumped laser with greater than 11 W of cw 1064-nm output power and 3.5 W of frequency-doubled average power at a 50-kHz pulse repetition frequency has been developed. A single Nd:YAG rod was pumped with the combined output of three fiber-coupled diode-laser arrays. Each pump laser was capable of 10 W of cw output power. The fiber output of each pump laser was first collimated and then focused with a single lens onto one end of a Nd:YAG rod. The resonator mirrors for the L-shaped cavity were selected such that thermal lensing in the laser crystal was mostly compensated. The 532-nm output beam quality factor (M2) was less than 1.5. RP HEMMATI, H (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 18 TC 31 Z9 31 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD SEP 1 PY 1994 VL 19 IS 17 BP 1322 EP 1324 DI 10.1364/OL.19.001322 PG 3 WC Optics SC Optics GA PD417 UT WOS:A1994PD41700019 PM 19855508 ER PT J AU SCHWARTZMAN, DW SHORE, SN VOLK, T MCMENAMIN, M AF SCHWARTZMAN, DW SHORE, SN VOLK, T MCMENAMIN, M TI SELF-ORGANIZATION OF THE EARTHS BIOSPHERE - GEOCHEMICAL OR GEOPHYSIOLOGICAL SO ORIGINS OF LIFE AND EVOLUTION OF THE BIOSPHERE LA English DT Article ID STANDARD SOLAR MODELS; SURFACE TEMPERATURES; CARBON-DIOXIDE; LIFE-SPAN; ENTROPY; EVOLUTION; THERMODYNAMICS; ATMOSPHERE; GAIA; SUN AB We explore the implications of indicating the biosphere's self-organization by the trend over time of the net entropic flow from the Earth's surface, the actual physical boundary of virtually all biotic mass. This flow, derived from the radiative surface entropy budget, is approximately inversely related to the surface temperature when the solar incident flux remains constant. In the geophysiological ('gaian') interpretation, biospheric self-organization has increased with the progressive colonization of the continents and evolutionary developments in the land biota, as a result of surface cooling arising from biotic enhancement of weathering. The key site for this self-organization is at the interface between land and atmosphere, the soil, where carbon is sequestered by its reaction (as carbonic and organic acids) with calcium magnesium silicates. Along with disequilibrium (steady-state) levels of carbon dioxide in the atmosphere, the occurrence of differentiated soil is the critical material evidence for biospheric self-organization, whether it be geophysiological or geochemical (ie., purely result of inorganic reactions). The computed equilibrium levels of carbon dioxide and corresponding equilibrium temperatures in the past are dramatically different from the steady-state levels. With future solar luminosity increase, the biospheric capacity for climatic regulation will decrease, leading to the ending of self-organization some two billion years from now. The Earth's surface will then approach chemical equilibrium with respect to the carbonate-silicate cycle. C1 INDIANA UNIV,DEPT PHYS & ASTRON,S BEND,IN 46634. NASA,GODDARD SPACE FLIGHT CTR,CSC,GHRS SCI TEAM,GREENBELT,MD 20771. NYU,DEPT EARTH SYST SCI,NEW YORK,NY 10003. MT HOLYOKE COLL,DEPT GEOG & GEOL,S HADLEY,MA 01075. RP SCHWARTZMAN, DW (reprint author), HOWARD UNIV,DEPT BIOL,WASHINGTON,DC 20059, USA. OI McMenamin, Mark/0000-0002-3764-0963 NR 60 TC 6 Z9 7 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0169-6149 J9 ORIGINS LIFE EVOL B JI Orig. Life Evol. Biosph. PD SEP PY 1994 VL 24 IS 5 BP 435 EP 450 DI 10.1007/BF01582019 PG 16 WC Biology SC Life Sciences & Biomedicine - Other Topics GA PK575 UT WOS:A1994PK57500003 ER PT J AU MORROW, BA STARCEVIC, VP KEIL, LC SEVERS, WB AF MORROW, BA STARCEVIC, VP KEIL, LC SEVERS, WB TI DEXAMETHASONE AND ERGONOVINE EFFECTS ON CEREBROSPINAL-FLUID PRESSURE IN CONSCIOUS RATS SO PHARMACOLOGY LA English DT Article DE INTRACRANIAL HYPERTENSION; CSF DYNAMICS; CSF PRESSURE; ERGONOVINE; DEXAMETHASONE ID INTRACRANIAL HYPERTENSION; CEREBROVENTRICULAR INFUSIONS AB Prior work showed that intracerebroventricular (ICV) infusions of artificial cerebrospinal fluid (aCSF), at a rate of 8 mu l/ min x 10 min, elevated CSF pressure (CSFp) of conscious rats after a 2-hour delay. The rise was associated with an increased resistance to outflow and decreased intracranial compliance. When maintained by a continuous infusion of 0.25 mu l/min into each lateral ventricle, CSFp recordings can be made for 24 h and a higher CSFp occurs. Here, we pretreated rats with ergonovine or dexamethasone to determine their effects on the delayed CSFp rise. Ergonovine (0.5 mg/kg i.p.) pretreatment, in a 6-hour protocol using only the 10-min infusion, slightly reduced CSFp (p < 0.05, one-tail test) but the time course of the delayed rise in CSFp was unchanged (p > 0.05). Ergonovine increased intracranial compliance (p < 0.05) 20 min after infusion when CSFp was normal, but not when CSFp was elevated at 4 h (p > 0.05). Dexamethasone (40 mu g i.m.) pretreatment was tested in the 24-hour protocol. It reduced (p < 0.05) normal CSFp during the 2-hour lag after infusion and the CSFp rise was reduced (p < 0.05) for about 8 h. However, the time course and ending CSFp were unchanged (p > 0.05). Thus, prior cerebral vasoconstriction or a steroidal anti-inflammatory drug have partial efficacy in reducing CSFp, but do not prevent the unknown events that precede the delayed CSFp rise after ICV infusions. C1 PENN STATE UNIV,COLL MED,MILTON S HERSHEY MED CTR,DEPT PHARMACOL,HERSHEY,PA 17033. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 20 TC 0 Z9 0 U1 0 U2 1 PU KARGER PI BASEL PA ALLSCHWILERSTRASSE 10, CH-4009 BASEL, SWITZERLAND SN 0031-7012 J9 PHARMACOLOGY JI Pharmacology PD SEP PY 1994 VL 49 IS 3 BP 199 EP 204 DI 10.1159/000139235 PG 6 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA PB946 UT WOS:A1994PB94600009 PM 7972335 ER PT J AU HUNT, BD FOOTE, MC PIKE, WT BARNER, JB VASQUEZ, RP AF HUNT, BD FOOTE, MC PIKE, WT BARNER, JB VASQUEZ, RP TI HIGH-T-C EDGE-GEOMETRY SNS WEAK LINKS ON SILICON-ON-SAPPHIRE SUBSTRATES SO PHYSICA C LA English DT Article ID YSZ BUFFER LAYERS; THIN-FILMS; JOSEPHSON-JUNCTIONS; EPITAXIAL-GROWTH; YBA2CU3O7 FILMS; DC SQUIDS; BARRIER; ORIENTATION; INTERFACES; SI(100) AB High-quality superconductor/normal-metal/superconductor (SNS) edge-geometry weak links have been produced on silicon-on-sapphire (SOS) substrates using a new SrTiO3/''seed-layer''/cubic-zirconia (YSZ) buffer system. The seed layer is a thin YBa2Cu3O7-x (YBCO) or PrBa2Cu3O7-x (PBCO) film, which provides a template for growth of the SrTiO3. This multilayer buffer system eliminates problems with series grain-boundary weak links seen in edge junctions on single YSZ buffer layers on SOS, while the use of moderate-dielectric-constant SOS substrates should benefit high-frequency applications and enable integration with silicon circuitry. SNS weak links fabricated on SOS with PBCO and Co doped YBCO normal-metal layers exhibit current-voltage characteristics qualitatively consistent with the resistively shunted junction model, with modulating AC Josephson steps and operation to temperatures above 77 K. These are the first reported epitaxial edge-geometry SNS devices on SOS substrates. RP HUNT, BD (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 32 TC 23 Z9 23 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD SEP 1 PY 1994 VL 230 IS 1-2 BP 141 EP 152 DI 10.1016/0921-4534(94)90456-1 PG 12 WC Physics, Applied SC Physics GA PE884 UT WOS:A1994PE88400017 ER PT J AU DUBOVIKOV, MS AF DUBOVIKOV, MS TI TRANSITION RADIATION AND BRAGG RESONANCES SO PHYSICAL REVIEW A LA English DT Article ID QUANTUM-THEORY; X-RAYS; EMISSION AB Both spontaneous and stimulated radiation emitted by an electron beam traversing a periodic medium are studied in the approximation of neglecting the influence of the field on the motion of the electrons. The results are valid both in the vicinity of the Bragg domain as well as far from it. In the latter case, we recover previous results with some corrections. In the Bragg domains the result is of interest since in this case the emission of quanta increases considerably. RP DUBOVIKOV, MS (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 33 TC 12 Z9 13 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD SEP PY 1994 VL 50 IS 3 BP 2068 EP 2074 DI 10.1103/PhysRevA.50.2068 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PG809 UT WOS:A1994PG80900017 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI (1,3)D(0) RESONANT STATES IN PS(-) SO PHYSICAL REVIEW A LA English DT Article ID POSITRONIUM NEGATIVE-ION; PRECISE NONVARIATIONAL CALCULATION; ANNIHILATION RATE; BOUND-STATES; PS AB We present a complex-coordinate rotation calculation of doubly excited 1,3D0 resonance states in Ps- associated with the N = 3, N = 4, and N = 5 Ps thresholds. Elaborate Hylleraas-type wave functions with up to N = 1330 terms are used. In addition to Feshbach resonances below various Ps thresholds, we have identified 3D0 shape resonance with one each lying above the N = 3 and N = 5 Ps thresholds, respectively, as well as a 1D0 shape resonance above the N = 4 threshold. A physical interpretation of the doubly excited Ps- is also given. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HO, YK (reprint author), ACAD SINICA,INST ATOM & MOLEC SCI,POB 23166,TAIPEI 115,TAIWAN. RI Ho, Yew Kam/F-7912-2012 NR 31 TC 17 Z9 17 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD SEP PY 1994 VL 50 IS 3 BP 2155 EP 2160 DI 10.1103/PhysRevA.50.2155 PG 6 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PG809 UT WOS:A1994PG80900026 ER PT J AU BOZZOLO, G FERRANTE, J AF BOZZOLO, G FERRANTE, J TI COMPOSITION DEPENDENCE OF BULK ALLOY PROPERTIES SO PHYSICAL REVIEW B LA English DT Article ID BINARY-ALLOYS; UNIVERSAL FEATURES; ELECTRONIC THEORY; PHASE-STABILITY; PARAMETERS; METALS; AG; AU AB We introduce an approximate expression for the direct calculation of properties of alloys in terms of the pure components. This rule can be obtained as a particular case from the Bozzolo-Ferrante-Smith (BFS) method, a recently developed semiempirical method for alloys. In particular, we examine the application of this rule to several examples of the concentration dependence of the lattice parameter of binary and ternary alloys. C1 NASA,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOKPARK,OH 44142, USA. NR 24 TC 11 Z9 11 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD SEP 1 PY 1994 VL 50 IS 9 BP 5971 EP 5980 DI 10.1103/PhysRevB.50.5971 PG 10 WC Physics, Condensed Matter SC Physics GA PG285 UT WOS:A1994PG28500020 ER PT J AU GASTER, M GROSCH, CE JACKSON, TL AF GASTER, M GROSCH, CE JACKSON, TL TI THE VELOCITY-FIELD CREATED BY A SHALLOW BUMP IN A BOUNDARY-LAYER SO PHYSICS OF FLUIDS LA English DT Article AB The results of measurements of the disturbance velocity field generated in a boundary layer by a shallow three-dimensional bump oscillating at a very low frequency on the surface of a flat plate are reported. The disturbance was entirely confined to the boundary layer. Profiles of the mean velocity, the disturbance velocity at the fundamental frequency, and at the first harmonic are presented. These profiles were measured both upstream and downstream of the oscillating bump. About 100 boundary layer thicknesses downstream of the bump the intensity had a maximum near eta=2, with a magnitude of about 0.2%. Measurements of the disturbance velocity were also made at various spanwise and downstream locations at a fixed distance from the boundary of one displacement thickness. The spanwise profiles of the disturbance field changed dramatically from the near-field region of the bump to the far downstream region. Finally, the spanwise spectrum of the disturbances at three locations downstream of the bump are presented. The spanwise spectrum of the disturbance showed a primary peak consistent with the motion and geometry of the driver. This peak decreased slowly with downstream distance. In addition, a small secondary peak in the spanwise spectrum was apparent near the bump. This peak increased rapidly with downstream distance. C1 OLD DOMINION UNIV,NORFOLK,VA 23529. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP GASTER, M (reprint author), UNIV CAMBRIDGE,CAMBRIDGE CB2 1PZ,CAMBS,ENGLAND. NR 3 TC 19 Z9 20 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 SEP PY 1994 VL 6 IS 9 BP 3079 EP 3085 DI 10.1063/1.868132 PG 7 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PF980 UT WOS:A1994PF98000034 ER PT J AU PALM, DE KEIL, LC SEVERS, WB AF PALM, DE KEIL, LC SEVERS, WB TI ANGIOTENSIN, VASOPRESSIN, AND ATRIAL-NATRIURETIC-PEPTIDE IN THE RAT EYE SO PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE LA English DT Article ID RABBIT ANTERIOR UVEA; RETINA; RECEPTORS; OXYTOCIN; SYSTEM AB Angiotensin (Ang), vasopressin (VP) and atrial natriuretic peptide (ANP) were assayed in the anterior uvea and retina from eyes of decapitated rats and rats perfused through the heart with phosphate buffered saline to remove peptides from blood and ocular fluids. All peptides were detected, and ANP was the most abundant. Uveal content of each peptide was greater than the retina. Perfusion did not affect ANP or VP content, but Ang was eliminated. Washout may explain the lack of immunohistochemical localization in the eye for Ang, but not VP. Also, washout does not account for available immunohistochemical data describing the localization of ANP in ocular tissue. C1 PENN STATE UNIV,COLL MED,MILTON S HERSHEY MED CTR,DEPT PHARMACOL,HERSHEY,PA 17033. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 18 TC 7 Z9 8 U1 0 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0037-9727 J9 P SOC EXP BIOL MED JI Proc. Soc. Exp. Biol. Med. PD SEP PY 1994 VL 206 IS 4 BP 392 EP 395 PG 4 WC Medicine, Research & Experimental SC Research & Experimental Medicine GA PE330 UT WOS:A1994PE33000007 PM 8073048 ER PT J AU MANN, DH PETEET, DM AF MANN, DH PETEET, DM TI EXTENT AND TIMING OF THE LAST GLACIAL MAXIMUM IN SOUTHWESTERN ALASKA SO QUATERNARY RESEARCH LA English DT Article ID EQUILIBRIUM-LINE ALTITUDES; CORDILLERAN ICE-SHEET; LATE WISCONSIN GLACIATION; QUEEN-CHARLOTTE-ISLANDS; BRITISH-COLUMBIA; PUGET LOBE; DEPOSITS; CANADA; USA; SEA AB A glacier complex composed of confluent alpine glaciers, island ice caps, and piedmont lobes covered much of the Alaska Peninsula and Kodiak Island during the last glacial maximum (LGM). Because this glacier complex formed the southeastern border of Beringia, its dynamics may have been important in the timing and feasibility of the northwest coast route for human migration into lower-latitude North America. Radiocarbon dates from stratigraphic sections on Kodiak Island and in the Bristol Bay lowlands bracket the LGM in southwestern Alaska between 23,000 and 14,700 yr B.P. Reconstruction of ice thickness based on glacier trimlines, moraines, and calculations of basal-shear stress depict the Alaska Peninsula Glacier Complex flowing to the outer edge of the continental shelf in the Gulf of Alaska. Equilibrium-line altitudes (ELAs) were 300 to 700 m lower than today and approached sea level on the southwestern Alaska Peninsula. In northeastern areas where ELAs were higher, bedrock topography largely controlled ice flow except where ice saddles bridged straits and inlets. (C) 1994 University of Washington. C1 NASA,GODDARD INST,NEW YORK,NY 10025. NR 62 TC 69 Z9 71 U1 1 U2 20 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0033-5894 J9 QUATERNARY RES JI Quat. Res. PD SEP PY 1994 VL 42 IS 2 BP 136 EP 148 DI 10.1006/qres.1994.1063 PG 13 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA PM157 UT WOS:A1994PM15700003 ER PT J AU BADHWAR, GD CUCINOTTA, FA BRABY, LA KONRADI, A AF BADHWAR, GD CUCINOTTA, FA BRABY, LA KONRADI, A TI MEASUREMENTS ON THE SHUTTLE OF THE LET SPECTRA OF GALACTIC COSMIC-RADIATION AND COMPARISON WITH THE RADIATION TRANSPORT MODEL SO RADIATION RESEARCH LA English DT Article AB A new class of tissue-equivalent proportional counters has been flown on two space shuttle flights. These detectors and their associated electronics cover a lineal energy range from 0.4 to 1250 keV/mu m with a multichannel analyzer resolution of 0.1 keV/mu m from 0.4 to 20 keV/mu m and 5 keV/mu m from 20 to 1250 keV/mu m. These detectors provide the most complete dynamic range and highest resolution of any technique currently in use. On one mission, one detector was mounted in the Shuttle payload bay and another older model in the mid-deck, thus providing information on the depth dependence of the lineal energy spectrum. A detailed comparison of the observed lineal energy and calculated LET spectra for galactic cosmic radiation shows that, although the radiation transport models provide a rather accurate description of the dose (+/-15%) and equivalent dose (+/-15%), the calculations significantly underestimate the frequency of events below about 100 keV/mu m. This difference cannot be explained by the inclusion of the contribution of splash protons. The contribution of the secondary pions, kaons and electrons produced in the Shuttle shielding, if included in the radiation transport model, may explain these differences. There are also significant differences between the model predictions and observations above 140 keV/mu m, particularly for 28.5 degrees inclination orbit. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. PACIFIC NW LAB, RICHLAND, WA 99352 USA. RP BADHWAR, GD (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. NR 24 TC 52 Z9 53 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD SEP PY 1994 VL 139 IS 3 BP 344 EP 351 DI 10.2307/3578832 PG 8 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA PE751 UT WOS:A1994PE75100010 PM 8073117 ER PT J AU MYNENI, RB WILLIAMS, DL AF MYNENI, RB WILLIAMS, DL TI ON THE RELATIONSHIP BETWEEN FAPAR AND NDVI SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT Remote Sensing of Soils and Vegetation Symposium CY 1993 CL TEMPE, AZ ID PHOTOSYNTHETICALLY ACTIVE RADIATION; SPECTRAL REFLECTANCE; VEGETATION CANOPIES; CORN CANOPIES; INDEXES; MODEL; SCATTERING; WHEAT AB The influence of pixel heterogeneity, background, atmospheric and bidirectional effects on the relationship between fraction of photosynthetically active radiation absorbed by the photosynthesizing tissue in a canopy (FAPAR) and normalized difference vegetation index (NDVI) is investigated using a three-dimensional model of radiation transfer. Top of the canopy (TOC) NDVI and FAPAR increase with ground cover and plant leaf area. Their functional response to leaf orientation, solar zenith angle and atmospheric optical depth is similar. For instance, planophile canopies (mostly horizontal leaves) have a higher FAPAR and TOC NDVI than erectophile canopies (mostly erect leaves). However, FAPAR and TOC NDVI respond differently to other parameters such as soil reflectance and leaf optical properties. For example, an increase in soil reflectance increases FAPAR but decreases TOC NDVI. Atmospheric and bidirectional effects confound the interpretation of top of the atmosphere (TOA) NDVI. The transmissivity of NDVI, defined as the ratio TOA/TOC NDVI, decreases with increasing atmospheric turbidity and solar zenith angle. Sensing about the nadir directions under clear sky conditions and moderate solar incidence angles can result in transmissivities as high as 0.8. There are sufficient causal grounds for relating FAPAR to NDVI. The relationship is independent of pixel heterogeneity, parameterized here with ground cover, plant leaf area, and variations in leaf orientation and optical properties. On the other hand, the relationship is sensitive to background, atmospheric, and bidirectional effects. A simple linear model relating FAPAR to TOC NDVI is proposed, and its validity is discussed. RP MYNENI, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. RI Myneni, Ranga/F-5129-2012 NR 31 TC 322 Z9 347 U1 5 U2 53 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD SEP PY 1994 VL 49 IS 3 BP 200 EP 211 DI 10.1016/0034-4257(94)90016-7 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PK030 UT WOS:A1994PK03000006 ER PT J AU CHOUDHURY, BJ AF CHOUDHURY, BJ TI SYNERGISM OF MULTISPECTRAL SATELLITE-OBSERVATIONS FOR ESTIMATING REGIONAL LAND-SURFACE EVAPORATION SO REMOTE SENSING OF ENVIRONMENT LA English DT Article; Proceedings Paper CT Remote Sensing of Soils and Vegetation Symposium CY 1993 CL TEMPE, AZ ID METEOROLOGICAL DATA; CANOPY TEMPERATURE; BOUNDARY-LAYER; WATER-BALANCE; EVAPOTRANSPIRATION; TRANSPIRATION; VEGETATION; FLUXES; AVHRR; MODEL AB The global water cycle is perhaps the most important of all the biogeochemical cycles, and land surface evaporation, which is a significant component of the water cycle, is also linked with heat and carbon cycles. Long-term, regional and global land surface evaporation have been computed using meteorological and river runoff data, although much uncertainties remain due to inadequacy of the input data. Multispectral observations could aid in estimating evaporation by providing spatially representative, multitemporal data for surface characteristics and fluxes. Estimation of evaporation using the residual method with coarse resolution multispectral satellite observations in the optical region is briefly reviewed. Then, semiempirical equations are used to relate unstressed transpiration to potential evaporation and vegetation indices, and correlations among multispectral data are discussed in the context of estimating evaporation. RP CHOUDHURY, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. NR 57 TC 45 Z9 48 U1 1 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD SEP PY 1994 VL 49 IS 3 BP 264 EP 274 DI 10.1016/0034-4257(94)90021-3 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PK030 UT WOS:A1994PK03000011 ER PT J AU PATER, RH AF PATER, RH TI THERMOSETTING POLYIMIDES - A REVIEW SO SAMPE JOURNAL LA English DT Review ID NUCLEAR MAGNETIC-RESONANCE; END-CAPPED POLYIMIDES; N-PHENYLNADIMIDE; POLYMERIZATION; 371-DEGREES-C; PERFORMANCE; COMPOSITES; SYSTEM; IMIDES; RESIN AB This paper reviews the chemistry, properties, and applications of PMR polyimides, acetylene-terminated polyimides and bismaleimides. Thermosetting polyimides are being developed for use as matrix resins in structurally efficient advanced composites for aerospace and future non-aerospace applications. Their chemical structures can be altered to enhance toughness, processing ease, and temperature performance. However, it is very difficult to attain these three desired properties in one product. Bismaleimides are popular for use in the temperature range of 150-250 degrees C because of their epoxy-like processing and polyimide-like temperature capability. PMR polyimides are suitable for temperatures up to 371 degrees C because of their outstanding thermo-oxidative stability, Acetylene-terminated Thermid materials are less favored because of the difficulty in processing; however, improvements in the processability are emerging. RP PATER, RH (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 67 TC 72 Z9 84 U1 4 U2 23 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0091-1062 J9 SAMPE J JI Sampe J. PD SEP-OCT PY 1994 VL 30 IS 5 BP 29 EP 38 PG 10 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA QZ181 UT WOS:A1994QZ18100003 ER PT J AU LOH, CY LIOU, MS AF LOH, CY LIOU, MS TI A LAGRANGIAN RANDOM CHOICE APPROACH FOR SUPERSONIC REAL-GAS FLOWS SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE LAGRANGIAN DESCRIPTION; RANDOM CHOICE METHOD; REAL GAS; RIEMANN PROBLEM; SUPERSONIC STEADY FLOW ID DIFFERENCE-SCHEMES; HYPERBOLIC SYSTEMS; GODUNOV; SHOCK AB This paper presents a random choice version of the Lagrangian approach for supersonic real gas flows, reported previously by Loh and Liou [J. Comput. Phsy., 104 (1993), pp. 150-161]. The exact real gas Riemann solution and the random choice method (RCM) are briefly reviewed and the derivation of the Lagrangian geometrical quantities, which represent the deformation of fluid particles in the motion, are described in detail. Extensive calculations were made to test the accuracy against the exact solution and the robustness of the Lagrangian RCM approach for real gas supersonic flows, including complex wave interactions of different types. The real gas effect is also presented by comparison with the perfect gas solution. The inherent parallelism in the Lagrangian approach lends a natural application in the massively parallel computation. RP LOH, CY (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,MS 5-11,CLEVELAND,OH 44135, USA. NR 24 TC 2 Z9 2 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD SEP PY 1994 VL 15 IS 5 BP 1038 EP 1058 DI 10.1137/0915063 PG 21 WC Mathematics, Applied SC Mathematics GA PD568 UT WOS:A1994PD56800003 ER PT J AU BAILEY, DH SWARZTRAUBER, PN AF BAILEY, DH SWARZTRAUBER, PN TI A FAST METHOD FOR THE NUMERICAL EVALUATION OF CONTINUOUS FOURIER AND LAPLACE TRANSFORMS SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE FAST FOURIER TRANSFORM; FRACTIONAL FOURIER TRANSFORM; NUMERICAL INTEGRATION ID FFTS AB The fast Fourier transform (FFT) is often used to compute numerical approximations to continuous Fourier and Laplace transforms. However, a straightforward application of the FFT to these problems often requires a large FFT to be performed, even though most of the input data to this FFT may be zero and only a small fraction of the output data may be of interest. In this note, the ''fractional Fourier transform,'' previously developed by the authors, is applied to this problem with a substantial savings in computation. C1 NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP BAILEY, DH (reprint author), NASA,DIV NUMER AERODYNAM SIMULAT SYST,MOFFETT FIELD,CA 94035, USA. NR 6 TC 22 Z9 22 U1 0 U2 5 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD SEP PY 1994 VL 15 IS 5 BP 1105 EP 1110 DI 10.1137/0915067 PG 6 WC Mathematics, Applied SC Mathematics GA PD568 UT WOS:A1994PD56800007 ER PT J AU GEARING, AF MCKISSOCK, BI COOKSON, SA AHLF, PR HUCKINS, EK AF GEARING, AF MCKISSOCK, BI COOKSON, SA AHLF, PR HUCKINS, EK TI US RUSSIAN COOPERATION ON SPACE STATION - THE NASA NPO ENERGIA STUDIES CONTRACT SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB In July 1992, the National Aeronautics and Space Administration (NASA) signed a contract with the Russian enterprise NPO Energia. Initial efforts under this contract focused on performing a number of studies. One of the study tasks examined the potential application of a broad range of Russian capabilities (hardware, experience, and know-how) to enhance Space Station. This paper will review those study efforts, which were related to the evolution of Space Station. These efforts included: utilization of Russian launch vehicles and transfer stages for logistics resupply; addition of a Russian laboratory module to Space Station; and incorporation of Russian systems and technologies for Space Station upgrades. NPO Energia's studies began in August 1992 and were completed in March 1993. NASA worked with NPO Energia to lay out the major topic areas, ground-rules, and desired study products. Periodic reviews of progress were held during the study period. The initial efforts were intentionally broad in nature. The goals of the effort were not only to learn about Russian capabilities, but to develop a working relationship and a firm framework for greater future cooperation. C1 EGAN GRP,WASHINGTON,DC. RP GEARING, AF (reprint author), NASA,SPACE STN ENGN,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 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD SEP PY 1994 VL 14 IS 5 BP 299 EP 305 PG 7 WC Engineering, Aerospace SC Engineering GA QX515 UT WOS:A1994QX51500001 ER PT J AU STANLEY, DO PILAND, WM AF STANLEY, DO PILAND, WM TI TECHNOLOGY REQUIREMENTS FOR AFFORDABLE SINGLE-STAGE ROCKET LAUNCH VEHICLES SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB A number of manned Earth-to-orbit (ETO) vehicle options for replacing or complementing the current Space Transportation System are being examined under the Advanced Manned Launch System (AMLS) study. The introduction of a reusable single-stage vehicle (SSV) into the U.S. launch vehicle fleet early in the next century could greatly reduce ETO launch costs. As a part of the AMLS study, the conceptual design of an SSV using a wide variety of enhancing technologies has recently been completed and is described in this paper. This paper also identifies the major enabling and enhancing technologies for a reusable rocket-powered SSV and provides examples of the mission payoff potential of a variety of important technologies. This paper also discusses the impact of technology advancements on vehicle margins, complexity, and risk, all of which influence the total system cost. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 365,HAMPTON,VA 23681, USA. NR 0 TC 2 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD SEP PY 1994 VL 14 IS 5 BP 319 EP 330 PG 12 WC Engineering, Aerospace SC Engineering GA QX515 UT WOS:A1994QX51500003 ER PT J AU MITSKY, VP WORKMAN, RJ NICHOLSON, WE VERNIKOS, J ROBERTSON, RM ROBERTSON, D AF MITSKY, VP WORKMAN, RJ NICHOLSON, WE VERNIKOS, J ROBERTSON, RM ROBERTSON, D TI A SENSITIVE RADIOIMMUNOASSAY FOR FLUDROCORTISONE IN HUMAN PLASMA SO STEROIDS LA English DT Article DE FLUDROCORTISONE; MICROGRAVITY; ORTHOSTATIC HYPOTENSION; MINERALOCORTICOID; AUTONOMIC FAILURE; HYPERTENSION AB Fludrocortisone has been a mainstay of therapy for orthostatic hypotension for many years. Clinical experience suggests that there exists a substantial interindividual variation in responsiveness to the drug. To assess this, we have developed an assay that permits measurement of the low concentrations of fludrocortisone found in human plasma. Fludrocortisone was detected by radioimmunoassay. A polyclonal rabbit antibody, raised against dexamethasone which cross-reacts strongly with fludrocortisone, was reacted with either standard or unknown samples in the presence of [I-125]fludrocortisone-3-TyrNH(2) (synthesized by coupling tyrosine amide to fludrocortisone-3-oxime and iodinating with chloramine T oxidation). The ED(10), ED(50), and ED(80) were 0.34, 5.0, and 30 ng/mL of plasma, respectively. The cross reactivity with other 9-fluorinated steroids was found as follows: dexamethasone, 340%; betamethasone, 230%; and triamcinolone, 8%. To preclude an erroneous result, subjects who were pregnant or receiving any steroid medication were excluded from the study. The percent cross-reactivity with the main naturally occurring steroids was as follows: 11-desoxycortisol 3.2%, cortisol 1.1%, DOC 0.3%, pregnenolone 0.1%, corticosterone 0.06%, progesterone 0.05%, and aldosterone <0.05%. The only compound with potential for interference, because of its high level in the circulation in the early morning, was cortisol. In plasma samples obtained before administration of fludrocortisone, levels of fludrocortisone were undetectable even though the plasma cortisol ranged from 40-175 ng/mL. In preliminary studies, fludrocortisone was given orally in doses of 0.2 and 2 mg. Timed plasma samples were collected. With doses of 0.2 mg, fludrocortisone levels peaked at about 2.4 ng/mL after 1-2 h and were undetectable by 12 h. With 2 ms, the levels peaked at 17.6-24.5 ng/mL at 1 h and was undetectable by 24 h. With the 2 mg dose, plasma cortisol fell at 10 h to 71-87% (14-23 ng/mL) of baseline. This decline was greater than would have been expected from the diurnal variation in cortisol. The estimated T-1/2 for fludrocortisone was 1.6 h for the 2 mg dose and 2.4 h for the 0.3 mg dose. This new fludrocortisone assay can now be used to define the pharmacokinetics of this agent. C1 VANDERBILT UNIV,CLIN RES CTR,DEPT MED,DIV CARDIOL,NASHVILLE,TN 37232. VANDERBILT UNIV,DEPT MED,DIV CLIN PHARMACOL,NASHVILLE,TN. VANDERBILT UNIV,DEPT MED,DIV ENDOCRINOL,NASHVILLE,TN. VANDERBILT UNIV,DEPT PHARMACOL & NEUROL,NASHVILLE,TN 37232. NASA HEADQUARTERS,DIV LIFE & BIOMED SCI & APPLICAT,WASHINGTON,DC 20546. FU NCRR NIH HHS [RR00095]; NHLBI NIH HHS [HL14192, HL44589] NR 14 TC 4 Z9 4 U1 0 U2 2 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0039-128X J9 STEROIDS JI Steroids PD SEP PY 1994 VL 59 IS 9 BP 555 EP 558 DI 10.1016/0039-128X(94)90074-4 PG 4 WC Biochemistry & Molecular Biology; Endocrinology & Metabolism SC Biochemistry & Molecular Biology; Endocrinology & Metabolism GA PF314 UT WOS:A1994PF31400007 PM 7846738 ER PT J AU KUMAR, P GUTTARP, P FOUFOULA-GEORGIOU, E AF KUMAR, P GUTTARP, P FOUFOULA-GEORGIOU, E TI A PROBABILITY-WEIGHTED MOMENT TEST TO ASSESS SIMPLE SCALING SO STOCHASTIC HYDROLOGY AND HYDRAULICS LA English DT Article DE PROBABILITY WEIGHTED MOMENT; SCALING IN RAINFALL; STABLE DISTRIBUTION ID SPATIAL RAINFALL FIELDS; MULTICOMPONENT DECOMPOSITION; FRACTAL DIMENSION; DISTRIBUTIONS AB We present a statistically robust approach based on probability weighted moments to assess the presence of simple scaling in geophysical processes. The proposed approach is different from current approaches which rely on estimation of high order moments. High order moments of simple scaling processes (distributions) may not have theoretically defined values and consequently, their empirical estimates are highly variable and do not converge with increasing sample size. They are, therefore, not an appropriate tool for inference. On the other hand we show that the probability weighted moments of such processes (distributions) do exist and hence, their empirical estimates are more robust. These moments, therefore, provide an appropriate tool for inferring the presence of scaling. We illustrate this using simulated Levy-stable processes and then draw inference on the nature of scaling in fluctuations of a spatial rainfall process. C1 UNIV WASHINGTON, DEPT STAT, SEATTLE, WA 98105 USA. UNIV MINNESOTA, DEPT CIVIL ENGN, ST ANTHONY FALLS HYDRAUL LAB, MINNEAPOLIS, MN 55414 USA. RP KUMAR, P (reprint author), UNIV SPACE RES, ASSOC HYDROL SCI BRANCH, NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RI Kumar, Praveen/D-2036-2010 OI Kumar, Praveen/0000-0002-4787-0308 NR 14 TC 28 Z9 28 U1 1 U2 4 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0931-1955 J9 STOCH HYDROL HYDRAUL JI Stoch. Hydrol. Hydraul. PD SEP PY 1994 VL 8 IS 3 BP 173 EP 183 DI 10.1007/BF01587233 PG 11 WC Engineering, Environmental; Engineering, Civil; Statistics & Probability; Water Resources SC Engineering; Mathematics; Water Resources GA PF085 UT WOS:A1994PF08500001 ER PT J AU RAMESHAM, R ROSE, MF ASKEW, RF BEKKER, TL DAYTON, JA KRAINSKY, IL MEARINI, G VANZANT, L FILE, DM GILMOUR, AS AYRES, V AF RAMESHAM, R ROSE, MF ASKEW, RF BEKKER, TL DAYTON, JA KRAINSKY, IL MEARINI, G VANZANT, L FILE, DM GILMOUR, AS AYRES, V TI EFFECT OF HYDROGEN ON THE PROPERTIES OF POLYCRYSTALLINE DIAMOND THIN-FILMS (VOL 64, PG 81, 1994) SO SURFACE & COATINGS TECHNOLOGY LA English DT Correction, Addition C1 USN,CTR SURFACE WARFARE,PORT HUENEME,CA. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. USN,CTR SURFACE WARFARE,CRANE,IN. SUNY BUFFALO,AMHERST,NY. USN,CTR SURFACE WARFARE,DAHLGREN,VA. RP RAMESHAM, R (reprint author), AUBURN UNIV,INST SPACE POWER,231 LEACH CTR,AUBURN,AL 36849, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD SEP PY 1994 VL 67 IS 1-2 BP 137 EP 137 DI 10.1016/S0257-8972(05)80038-6 PG 1 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA PF316 UT WOS:A1994PF31600019 ER PT J AU SOLOMON, JA SPERLING, G AF SOLOMON, JA SPERLING, G TI FULL-WAVE AND HALF-WAVE RECTIFICATION IN 2ND-ORDER MOTION PERCEPTION SO VISION RESEARCH LA English DT Article DE MOTION; NON-FOURIER MOTION; RECTIFICATION; TRANSPARENCY; ATTENTION ID APPARENT MOTION; MOVEMENT; MODEL AB Microbalanced stimuli are dynamic displays which do not stimulate motion mechanisms that apply standard (Fourier-energy or autocorrelational) motion analysis directly to the visual signal. In order to extract motion information from microbalanced stimuli, Chubb and Sperling [(1988) Journal of the Optical Society of America, 5, 1986-2006] proposed that the human visual system performs a rectifying transformation on the visual signal prior to standard motion analysis. The current research employs two novel types of microbalanced stimuli: half-wave stimuli preserve motion information following half-wave rectification (with a threshold) but lose motion information following full-wave rectification; full-wave stimuli preserve motion information following full-wave rectification but lose motion information following half-wave rectification. Additionally, Fourier stimuli, ordinary square-wave gratings, were used to stimulate standard motion mechanisms. Psychometric functions (direction discrimination vs stimulus contrast) were obtained for each type of stimulus when presented alone, and when masked by each of the other stimuli (presented as moving masks and also as nonmoving, counterphase-flickering masks). Results: given sufficient contrast, all three types of stimulus convey motion. However, only one-third of the population can perceive the motion of the half-wave stimulus. Observers are able to process the motion information contained in the Fourier stimulus slightly more efficiently than the information in the full-wave stimulus but are much less efficient in processing half-wave motion information. Moving masks are more effective than counterphase masks at hampering direction discrimination, indicating that some of the masking effect is interference between motion mechanisms, and some occurs at earlier stages. When either full-wave and Fourier or half-wave and Fourier gratings are presented simultaneously, there is a wide range of relative contrasts within which the motion directions of both gratings are easily determinable. Conversely, when half-wave and full-wave gratings are combined, the direction of only one of these gratings can be determined with high accuracy. Conclusions: the results indicate that three motion computations are carried out, any two in parallel: one standard (''first order'') and two non-Fourier (''second-order'') computations that employ full-wave and half-wave rectification. C1 UNIV CALIF IRVINE,DEPT COGNIT SCI,IRVINE,CA 92717. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 23 TC 56 Z9 56 U1 0 U2 1 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 SEP PY 1994 VL 34 IS 17 BP 2239 EP 2257 DI 10.1016/0042-6989(94)90105-8 PG 19 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA NZ968 UT WOS:A1994NZ96800006 PM 7941419 ER PT J AU MINELLO, TJ ZIMMERMAN, RJ MEDINA, R AF MINELLO, TJ ZIMMERMAN, RJ MEDINA, R TI THE IMPORTANCE OF EDGE FOR NATANT MACROFAUNA IN A CREATED SALT-MARSH SO WETLANDS LA English DT Article DE EDGE; SPARTINA; SALT MARSH; RESTORATION; TRANSPLANT; FISH; SHRIMP; CRUSTACEANS; HABITAT COMPLEXITY; HYDROPERIOD AB The relationship between marsh edge and animal use was examined in a planted Spartina alterniflora marsh located in the Galveston Bay system of Texas. A completely randomized block experimental design was used with each of four blocks containing a control and experimental sector. Marsh edge was increased through the construction of channels in experimental sectors. Channel construction had no detectable effect on marsh surface elevation. Effects of these simulated tidal creeks on habitat use were examined by sampling nekton at high tide with,drop enclosures both on the marsh surface and within the channels. Crustaceans dominated the nekton, and use of the marsh surface in experimental sectors was significantly higher than in controls; densities of brown shrimp Penaeus aztecus, white shrimp P. setiferus, and daggerblade grass shrimp Palaemonetes pugio were 4.6 to 13 times higher near the channels. Polychaete densities in marsh sediments were also significantly higher near channels, and densities of decapod predators were positively correlated with densities of these infaunal prey. Thus, channel effects on natant decapods may have been related to the distribution of prey organisms. However, increased densities of natant fauna along the channel edge may simply reflect a requirement for departure from the marsh surface at low tide. Marsh-surface densities of small bait fishes,bay anchovy Anchoa mitchilli and the inland silverside Menidia beryllina, also increased near channels, but highest densities of these fishes were in the creeks themselves. The abundance and distribution of juvenile blue crabs Callinectes sapidus and gulf marsh fiddler crabs Uca longisignalis were not affected by the addition of experimental channels. Overall, the study results indicate that habitat value of created salt marshes can be enhanced by incorporating tidal creeks into the marsh design. RP MINELLO, TJ (reprint author), NATL MARINE FISHERIES SERV,SEFC,GALVESTON LAB,GALVESTON,TX 77551, USA. NR 0 TC 104 Z9 107 U1 2 U2 22 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 SN 0277-5212 J9 WETLANDS JI Wetlands PD SEP PY 1994 VL 14 IS 3 BP 184 EP 198 PG 15 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA PJ256 UT WOS:A1994PJ25600004 ER PT J AU RICCA, A BAUSCHLICHER, CW AF RICCA, A BAUSCHLICHER, CW TI THE LOW-LYING ELECTRONIC-STATE OF MG2+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CORE POLARIZATION POTENTIALS; PHOTODISSOCIATION SPECTROSCOPY; ABINITIO CALCULATIONS; MG2CO2+; ALKALI AB The low-lying doublet and quartet states of Mg2+ have been studied using a multireference configuration interaction approach. The effect of inner-shell correlation has been included using the core-polarization potential method. The computed spectroscopic constants, lifetimes, and oscillator strengths should help resolve the difference between the recent experiments and previous theoretical calculations. RP RICCA, A (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 9 TC 2 Z9 2 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 AUG 26 PY 1994 VL 226 IS 5-6 BP 459 EP 462 DI 10.1016/0009-2614(94)00756-X PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PE005 UT WOS:A1994PE00500005 ER PT J AU HORACK, JM AF HORACK, JM TI GAMMA-RAY BURSTS - NEAR OR FAR SO SCIENCE LA English DT Editorial Material ID BATSE RP HORACK, JM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. RI Horack, John/J-6670-2016 NR 21 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 26 PY 1994 VL 265 IS 5176 BP 1186 EP 1187 DI 10.1126/science.265.5176.1186 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PD422 UT WOS:A1994PD42200023 PM 17787581 ER PT J AU VEEDER, GJ MATSON, DL JOHNSON, TV BLANEY, DL GOGUEN, JD AF VEEDER, GJ MATSON, DL JOHNSON, TV BLANEY, DL GOGUEN, JD TI IOS HEAT-FLOW FROM INFRARED RADIOMETRY - 1983-1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GALILEAN SATELLITES; VISCOELASTIC MODELS; GLOBAL DISTRIBUTION; SILICATE VOLCANISM; MONITORING PROGRAM; TIDAL DISSIPATION; HOT SPOTS; PHOTOMETRY; HOTSPOTS; SYSTEM AB We report the following results from a decade of infrared radiometry of Io: (1) The average global heat flow is more than approximately 2.5 W m-2, (2) large warm (greater-than-or-equal-to 200 K) volcanic regions dominate the global heat flow, (3) small high-temperature (greater-than-or-equal-to 300 K) ''hotspots'' contribute little to the average heat flow, (4) thermal anomalies on the leading hemisphere contribute about half of the heat flow, (5) a substantial amount of heat is radiated during Io's night, (6) high-temperature (greater-than-or-equal-to 600 K) ''outbursts'' occurred during approximately 4% of the nights we observed, (7) ''Loki'' is the brightest, persistent, infrared emission feature, and (8) some excess emission is always present at the longitude of Loki, but its intensity and other characteristics change between apparitions. Observations of lo at M (4.8 mum), 8.7 mum, N (10 mum), and Q (20 mum) with the Infrared Telescope Facility presented here were collected during nine apparitions between 1983 and 1993. These measurements provide full longitudinal coverage as well as an eclipse observation and the detection of two outbursts. Reflected sunlight, passive thermal emission, and radiation from thermal anomalies all contribute to the observed flux densities. We find that a new thermophysical model is required to match all the data. Two key elements of this model are (1) a ''thermal reservoir'' unit which lowers daytime temperatures, and (2) the ''thermal pedestal effect' which shifts to shorter wavelengths the spectral emission due to the reradiation of solar energy absorbed by the thermal anomalies. The thermal anomalies are modeled with a total of 10 source components at five locations. Io's heat flow is the sum of the power from these components. RP VEEDER, GJ (reprint author), JET PROP LAB,MAIL STOP 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 76 TC 134 Z9 134 U1 2 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1994 VL 99 IS E8 BP 17095 EP 17162 DI 10.1029/94JE00637 PG 68 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PD384 UT WOS:A1994PD38400003 ER PT J AU WARGO, MJ AF WARGO, MJ TI MICROGRAVITY - A RESEARCH TOOL FOR BIOTECHNOLOGY, COMBUSTION SCIENCE, FLUID PHYSICS AND MATERIALS SCIENCE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA HEADQUARTERS,DIV MICROGRAV & APPLICAT,WASHINGTON,DC. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 9 EP TECH PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA261 UT WOS:A1994PA26100996 ER PT J AU ANDREWS, JH KHAYDAROV, JDV SINGER, KD HULL, DL CHUANG, KC AF ANDREWS, JH KHAYDAROV, JDV SINGER, KD HULL, DL CHUANG, KC TI 3RD HARMONIC SPECTRAL DISPERSION OF SQUARAINES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RI Singer, Kenneth/G-6553-2011 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 29 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901044 ER PT J AU TRUHLAR, DG MIELKE, SL ALLISON, TC TAWA, GJ SCHWENKE, DW AF TRUHLAR, DG MIELKE, SL ALLISON, TC TAWA, GJ SCHWENKE, DW TI QUANTUM DYNAMICS OF CHEMICAL-REACTIONS WITH ELECTRONICALLY NONADIABATIC COUPLING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV MINNESOTA,DEPT CHEM,MINNEAPOLIS,MN 55455. UNIV MINNESOTA,INST SUPERCOMP,MINNEAPOLIS,MN 55455. NASA,AMES RES CTR,RES LAB,MOFFETT FIELD,CA 94035. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 58 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26900670 ER PT J AU EAKER, CW SCHWENKE, DW AF EAKER, CW SCHWENKE, DW TI A FFT METHOD FOR PREPARING VIBRATIONAL-ROTATIONAL STATES OF TRIATOMIC-MOLECULES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV DALLAS,DEPT CHEM,IRVING,TX 75062. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI schwenke, david/I-3564-2013 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 72 EP COMP PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA261 UT WOS:A1994PA26101379 ER PT J AU REDDY, VS WEIKEL, WJ ARBAUGH, J FITCH, JW CASSIDY, PE STCLAIR, AK AF REDDY, VS WEIKEL, WJ ARBAUGH, J FITCH, JW CASSIDY, PE STCLAIR, AK TI SYNTHESIS AND CHARACTERIZATION OF NEW FLUORINATED POLYACRYLATES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SW TEXAS STATE UNIV,DEPT CHEM,POLYMER RES GRP,SAN MARCOS,TX 78666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 90 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901105 ER PT J AU HERBERT, CG BASS, RG WATSON, KA AF HERBERT, CG BASS, RG WATSON, KA TI THE PREPARATION OF POLY(ARYLENE ETHER)S CONTAINING PYRIMIDINE RINGS BY AROMATIC NUCLEOPHILIC DISPLACEMENT-REACTIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 VIRGINIA COMMONWEALTH UNIV,DEPT CHEM,RICHMOND,VA 23284. NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 99 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901114 ER PT J AU ILLINGSWORTH, ML BANKS, BA SMITH, JW JAYNE, D GARLICK, RG RUTLEDGE, SK DEGROH, KK AF ILLINGSWORTH, ML BANKS, BA SMITH, JW JAYNE, D GARLICK, RG RUTLEDGE, SK DEGROH, KK TI ATOMIC OXYGEN EROSION OF A TRANSITION-METAL COMPLEX SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 ROCHESTER INST TECHNOL,DEPT CHEM,ROCHESTER,NY 14623. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 143 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA261 UT WOS:A1994PA26102320 ER PT J AU MINTON, TK MOORE, TA GIAPIS, KP AF MINTON, TK MOORE, TA GIAPIS, KP TI INTERACTIONS OF HYPERTHERMAL FLUORINE-ATOMS WITH SILICON - SCATTERING DYNAMICS AND ETCHING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 JET PROP LAB,PASADENA,CA 91109. CALTECH,DEPT CHEM & CHEM ENGN,PASADENA,CA 91125. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 159 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26900771 ER PT J AU MEYERS, F MARDER, SR PERRY, JW BREDAS, JL PIERCE, BM AF MEYERS, F MARDER, SR PERRY, JW BREDAS, JL PIERCE, BM TI OPTIMIZING MOLECULAR POLARIZABILITIES IN LINEAR CONJUGATED ORGANIC-MOLECULES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV MONS,B-7000 MONS,BELGIUM. CALTECH,BECKMAN INST,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. HUGHES AIRCRAFT CO,LOS ANGELES,CA 90009. RI Bredas, Jean-Luc/A-3431-2008; Perry, Joseph/B-7191-2011 OI Bredas, Jean-Luc/0000-0001-7278-4471; Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 169 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901183 ER PT J AU JEN, AKY DROST, KJ RAO, VP CAI, YM LIU, YJ MININNI, RM KENNEY, JT BINKLEY, ES DALTON, LR XU, C MARDER, S AF JEN, AKY DROST, KJ RAO, VP CAI, YM LIU, YJ MININNI, RM KENNEY, JT BINKLEY, ES DALTON, LR XU, C MARDER, S TI THE INCORPORATION OF HIGHLY-ACTIVE AND THERMALLY STABLE HETEROAROMATIC CHROMOPHORES INTO HIGH-TEMPERATURE POLYIMIDES FOR E-O APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 ROITECHNOL,SANTA CLARA,CA 95051. UNIV SO CALIF,DEPT CHEM,LOS ANGELES,CA 90089. JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 175 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901189 ER PT J AU STIEGMAN, AE SCOTT, G ECKERT, H AF STIEGMAN, AE SCOTT, G ECKERT, H TI PHOTOPHYSICAL AND PHOTOCHEMICAL PROCESSES AT DISCREET PSEUDOTETRAHEDRAL VANADIUM-OXIDE CENTERS IN A SILICA XEROGEL MATRIX SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 JET PROP LAB,PASADENA,CA 91109. UNIV CALIF RIVERSIDE,RIVERSIDE,CA 92521. UNIV CALIF SANTA BARBARA,SANTA BARBARA,CA 93106. RI Eckert, Hellmut/G-3176-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 191 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26900803 ER PT J AU PERRY, JW BOURHILL, G MARDER, SR LU, D CHEN, G GODDARD, WA AF PERRY, JW BOURHILL, G MARDER, SR LU, D CHEN, G GODDARD, WA TI HYPERPOLARIZABILITIES OF PUSH-PULL POLYENES - EXPERIMENTAL RESULTS AND A NEW 2-STATE MODEL SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 BECKMAN INSTRUMENTS INC,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. CALTECH,DIV CHEM & CHEM ENGN,PASADENA,CA 91125. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 218 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901232 ER PT J AU RUBIRA, AF RANCOURT, JD CAPLAN, ML STCLAIR, AK TAYLOR, LT AF RUBIRA, AF RANCOURT, JD CAPLAN, ML STCLAIR, AK TAYLOR, LT TI OPTICALLY REFLECTIVE AND ELECTRICALLY CONDUCTIVE SILVER-COATED POLYIMIDE FILMS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23681. VIRGINIA POLYTECH INST & STATE UNIV,DEPT CHEM,BLACKSBURG,VA 24061. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. UNIV ESTADUAL MARINGA,DEPT QUIM,BR-87020900 MARINGA,PARANA,BRAZIL. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 275 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901799 ER PT J AU THIBEAULT, SA LONG, ER GLASGOW, MB ORWOLL, RA KIEFER, RL AF THIBEAULT, SA LONG, ER GLASGOW, MB ORWOLL, RA KIEFER, RL TI BORON-LOADED EPOXY MATERIAL FOR NEUTRON SHIELDING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. COLL WILLIAM & MARY,WILLIAMSBURG,VA 23187. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 325 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901339 ER PT J AU KIM, MHY THIBEAULT, SA WILSON, JW KIEFER, RL ORWOLL, RA AF KIM, MHY THIBEAULT, SA WILSON, JW KIEFER, RL ORWOLL, RA TI PERFORMANCE OF POLYMERIC MATERIALS AS SHIELDING FOR COSMIC-RADIATION SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 COLL WILLIAM & MARY,WILLIAMSBURG,VA 23187. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 329 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901343 ER PT J AU SCHWENKE, DW MIELKE, SL TRUHLAR, DG AF SCHWENKE, DW MIELKE, SL TRUHLAR, DG TI THEORETICAL-STUDIES OF GAS-PHASE REACTIONS INVOLVING MULTIPLE POTENTIAL-ENERGY SURFACES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV MINNESOTA,DEPT CHEM,MINNEAPOLIS,MN 55455. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 381 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26900990 ER PT J AU THOMPSON, DW SOUTHWARD, RE STCLAIR, AK AF THOMPSON, DW SOUTHWARD, RE STCLAIR, AK TI LANTHANIDE(III) DOPED POLYIMIDE FILMS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 393 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901917 ER PT J AU YOUNG, PR SIOCHI, EJ SLEMP, WS AF YOUNG, PR SIOCHI, EJ SLEMP, WS TI MOLECULAR-LEVEL RESPONSE OF SELECTED POLYMERIC MATERIALS TO THE LEO ENVIRONMENT SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 396 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901410 ER PT J AU CAPLAN, ML SOUTHWARD, RE THOMPSON, DW STCLAIR, AK AF CAPLAN, ML SOUTHWARD, RE THOMPSON, DW STCLAIR, AK TI SILVER-DOPED POLYIMIDE FILMS FOR SPACE APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 427 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901951 ER PT J AU ABDELAYEM, H PALEY, MS FRAZIER, DO WITHEROW, WK MCMANUS, SP AF ABDELAYEM, H PALEY, MS FRAZIER, DO WITHEROW, WK MCMANUS, SP TI 3RD-ORDER NONLINEAR-OPTICAL PROPERTIES OF POLYDIACETYLENES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 429 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA269 UT WOS:A1994PA26901443 ER PT J AU CHEN, CT MANSOUR, K PERRY, JW MARDER, SR KWAG, GH KENNEY, ME AF CHEN, CT MANSOUR, K PERRY, JW MARDER, SR KWAG, GH KENNEY, ME TI METALLO-PHTHALOCYANINES AND NAPHTHALOCYANINES FOR OPTICAL SWITCHING APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. CASE WESTERN RESERVE UNIV,DEPT CHEM,CLEVELAND,OH 44106. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 21 PY 1994 VL 208 BP 535 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA PA261 UT WOS:A1994PA26102710 ER PT J AU TIRA, NE MAHAN, JR LEE, RB KEYNTON, RJ AF TIRA, NE MAHAN, JR LEE, RB KEYNTON, RJ TI LINEAR-ARRAY APERTURES FOR IN-FLIGHT DYNAMIC SOLAR CALIBRATION OF RADIOMETRIC CHANNELS FOR EARTH RADIATION-BUDGET APPLICATIONS SO APPLIED OPTICS LA English DT Article ID INSTRUMENT AB The zero-frequency gain of nonimaging radiometers used in Earth radiation-budget applications is usually verified by a procedure that allows the instrument to view the Sun through an appropriate attenuating aperture and then equates its response to the known attenuated solar constant. However, channel intercomparison often requires that data from a low-resolution, relatively slow instrument such as an active-cavity radiometer be compared with data from a high-resolution, fast instrument such as a scanning thermistor-bolometer radiometer. In such a case, consideration of the difference in the dynamic responses of the two channels may be important. A novel technique for in-flight measurement of the radiometric transfer function of such instruments is described and then demonstrated through the use of a high-order dynamic model of the total, wide-field-of-view, nonscanning channel of NASA's Earth Radiation Budget Experiment (ERBE). C1 NASA, LANGLEY RES CTR, RADIAT SCI BRANCH, HAMPTON, VA 23681 USA. RP TIRA, NE (reprint author), VIRGINIA POLYTECH INST & STATE UNIV, DEPT MECH ENGN, BLACKSBURG, VA 24061 USA. NR 6 TC 1 Z9 1 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5617 EP 5627 PG 11 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800021 PM 20935961 ER PT J AU PALM, SP MELFI, SH CARTER, DL AF PALM, SP MELFI, SH CARTER, DL TI NEW AIRBORNE SCANNING LIDAR SYSTEM - APPLICATIONS FOR ATMOSPHERIC REMOTE-SENSING SO APPLIED OPTICS LA English DT Article DE AIRBORNE SCANNING LIDAR; BOUNDARY-LAYER HEIGHT; AEROSOL OPTICAL DEPTH ID CONVECTIVE BOUNDARY-LAYER; COLD-AIR OUTBREAK; DYNAMICS AB A new scanning airborne-aerosol lidar system that has the potential to be a valuable atmospheric remote-sensing tool has been developed. The system has the ability to scan both parallel and perpendicular to an aircraft's flight path, and this ability permits both the three-dimensional rendering of the aerosol structure below the aircraft and the measurement of aerosol extinction and optical depth. The system has been integrated into a NASA P-3 aircraft and during a recent flight was used to acquire excellent data with both scanning modes. The system design, the application of the across-track scanning data to the study of the atmospheric boundary layer, and the computation of optical depth derived from along-track scan data are reported. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP PALM, SP (reprint author), SCI SYST & APPLICAT INC, LANHAM, MD 20706 USA. NR 9 TC 13 Z9 13 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5674 EP 5681 PG 8 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800028 PM 20935968 ER PT J AU MENZIES, RT TRATT, DM AF MENZIES, RT TRATT, DM TI AIRBORNE CO2 COHERENT LIDAR FOR MEASUREMENTS OF ATMOSPHERIC AEROSOL AND CLOUD BACKSCATTER SO APPLIED OPTICS LA English DT Article ID OPTICAL-PROPERTIES; WAVELENGTHS; CALIBRATION; INJECTION; LASER; STABILIZATION; TRANSMITTER; MODEL AB An airborne CO2 coherent lidar has been developed and flown on over 30 flights of the NASA DC-8 research aircraft to obtain aerosol and cloud backscatter and extinction data at a wavelength near 9 mum. Designed to operate in either zenith- or nadir-directed modes, the lidar can be used to measure vertical profiles of backscatter throughout the vertical extent of the troposphere and the lower stratosphere. Backscatter measurements in absolute units are obtained through a hard-target calibration methodology. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Aerosol backscatter profile intercomparisons with other airborne and ground-based CO2 lidars were conducted during instrument checkout flights over the NASA Ames Research Center before extended deployment over the Pacific Ocean. Selected results from data taken during the flights over the Pacific Ocean are presented, emphasizing intercomparisons with backscatter profile data obtained at 1.06 mum with a NASA Goddard Space Flight Center Nd:YAG lidar on the same flights. RP MENZIES, RT (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 39 TC 28 Z9 28 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5698 EP 5711 PG 14 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800031 PM 20935971 ER PT J AU WINKER, DM AF WINKER, DM TI FABRICATION AND TESTING OF LARGE STEERING MIRRORS FOR A SCANNING LIDAR SO APPLIED OPTICS LA English DT Note DE MIRRORS; LIDAR AB Large, inexpensive scanning mirrors for a lidar have been designed and built out of common float glass mirrors and aluminum honeycomb. The flatness of the scanning mirrors has been characterized with a modified Foucault knife-edge test. The peak-to-peak surface slope error over the entire surface of the mirrors was found to be less than 1 mrad, with slope errors of 0.15 mrad over small areas. This performance was sufficient for use of the mirrors in a scanning CO2 lidar system that uses direct detection. RP WINKER, DM (reprint author), NASA LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NR 3 TC 1 Z9 1 U1 1 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5712 EP 5714 PG 3 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800032 PM 20935972 ER PT J AU LEE, ZP CARDER, KL HAWES, SK STEWARD, RG PEACOCK, TG DAVIS, CO AF LEE, ZP CARDER, KL HAWES, SK STEWARD, RG PEACOCK, TG DAVIS, CO TI MODEL FOR THE INTERPRETATION OF HYPERSPECTRAL REMOTE-SENSING REFLECTANCE SO APPLIED OPTICS LA English DT Article ID APPARENT OPTICAL-PROPERTIES; ZONE COLOR SCANNER; DIFFUSE-REFLECTANCE; OCEAN COLOR; PHYTOPLANKTON POPULATIONS; BIOGENOUS MATTER; RAMAN-SCATTERING; NATURAL-WATERS; CHLOROPHYLL-A; SUN ANGLE AB Remote-sensing reflectance is easier to interpret for the open ocean than for coastal regions because the optical signals are highly coupled to the phytoplankton (e.g., chlorophyll) concentrations. For estuarine or coastal waters, variable terrigenous colored dissolved organic matter (CDOM), suspended sediments, and bottom reflectance, all factors that do not covary with the pigment concentration, confound data interpretation. In this research, remote-sensing reflectance models are suggested for coastal waters, to which contributions that are due to bottom reflectance, CDOM fluorescence, and water Raman scattering are included. Through the use of two parameters to model the combination of the backscattering coefficient and the Q factor, excellent agreement was achieved between the measured and modeled remote-sensing reflectance for waters from the West Florida Shelf to the Mississippi River plume. These waters cover a range of chlorophyll of 0.2-40 mg/m3 and gelbstoff absorption at 440 nm from 0.02-0.4 m-1. Data with a spectral resolution of 10 nm or better, which is consistent with that provided by the airborne visible and infrared imaging spectrometer (AVIRIS) and spacecraft spectrometers, were used in the model evaluation. C1 JET PROP LAB, PASADENA, CA 91109 USA. RP LEE, ZP (reprint author), UNIV S FLORIDA, DEPT MARINE SCI, 140 7TH AVE, ST PETERSBURG, FL 33701 USA. RI Liu, Cheng-Chien/E-4859-2011 NR 48 TC 177 Z9 192 U1 2 U2 17 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5721 EP 5732 PG 12 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800034 PM 20935974 ER PT J AU GENTRY, BM AF GENTRY, BM TI EDGE TECHNIQUE FOR HIGH-ACCURACY DOPPLER VELOCIMETRY SO APPLIED OPTICS LA English DT Article DE VELOCIMETRY; EDGE TECHNIQUE; DOPPLER; FABRY-PEROT INTERFEROMETER ID FABRY-PEROT; LASER AB The edge technique has been used in simple laboratory experiments to demonstrate velocity measurements with an experimental error, standard deviation, as small as 12 cm/s, which represents a Doppler-shift measurement accuracy of 8 parts in 10(10) of the laser frequency. An edge filter with a spectral width 140 times larger than the measurement accuracy achieved is used. The measurements are made in the presence of short-term frequency drifts equivalent to velocities of 5 to 10 m/s, which are eliminated by the differential frequency measurement used in the edge technique. Long-term frequency drifts are compensated for by servo locking the edge to the laser frequency. High accuracy is achieved for a range of locations on the edge from 0.33 to 4.5 fringe half-widths (half-width at half-maximum), a dynamic range greater than 500 times the measurement accuracy. RP GENTRY, BM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 917, GREENBELT, MD 20771 USA. NR 20 TC 37 Z9 45 U1 5 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1994 VL 33 IS 24 BP 5770 EP 5777 PG 8 WC Optics SC Optics GA PE548 UT WOS:A1994PE54800039 PM 20935979 ER PT J AU CHIAR, JE KUTNER, ML VERTER, F LEOUS, J AF CHIAR, JE KUTNER, ML VERTER, F LEOUS, J TI A COMPARISON OF CO (J=1-]0) AND CO (J=2-]1) EMISSION IN THE MILKY-WAY MOLECULAR RING SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, STRUCTURE; ISM, CLOUDS; ISM, MOLECULES; RADIO LINES, ISM; STARS, FORMATION ID 1ST GALACTIC QUADRANT; CARBON-MONOXIDE; STAR FORMATION; INNER GALAXY; CLOUDS; CALIBRATION; DIFFUSE; SEARCH; MODEL; MASS AB We have carried put a CO (J = 2 --> 1) survey of the Scutum Arm region of the Milky Way molecular ring. Our goals are to compare CO (J = 2 --> 1) maps of individual Galactic clouds with the large-scale CO (J = 2 --> 1) emission from the Galactic plane, and to predict the CO (J = 2 --> 1) appearance of a Galactic cloud ensemble in an external galaxy. The angular resolution and spatial coverage of our survey are compatible with the existing CO (J = 1 --> 0) survey of this region by Sanders et al., which we use for comparison. We identify 34 molecular clouds in our map region; their relationships between size and line width and between virial mass and luminosity are consistent with the relationships seen in CO (J = 1 --> 0) emission. However, we note that previous studies have shown considerable variation in these relationships; we attribute much of this variation to differences in their cloud definition algorithm and statistical method. We find that the median ratio of integrated emission in the two lowest CO transitions for the clouds in our sample is I(2 --> 1)/I(1 --> 0) = 0.69, implying that the typical emitting region in the line of sight contains cold gas that is not actively star-forming. Our conclusion that the molecular ring emission is not dominated by star-forming regions is consistent with other large-scale studies of the Milky Way. Our distributions of cloud size and temperature also imply that relatively massive molecular clouds that lack star formation, such as Maddalena's cloud, are not rare in the inner Galaxy. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,UNIVERSITY PK,PA 16802. RP CHIAR, JE (reprint author), RENSSELAER POLYTECH INST,DEPT PHYS,TROY,NY 12180, USA. OI Leous, Jim/0000-0002-7930-0609 NR 42 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1994 VL 431 IS 2 BP 658 EP 673 DI 10.1086/174517 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC148 UT WOS:A1994PC14800019 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI GALACTIC STARS APPLIED TO TESTS OF THE CRITERION FOR CONVECTION AND SEMICONVECTION IN AN INHOMOGENEOUS STAR SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; STARS, EARLY TYPE; STARS, INDIVIDUAL (SN-1987A); STARS, INTERIORS; SUPERGIANTS ID LARGE MAGELLANIC CLOUD; POPULATION-I STARS; C-12(ALPHA,GAMMA)O-16 CROSS-SECTION; YELLOW SEMIREGULAR VARIABLES; INITIAL MASS FUNCTION; M-CIRCLE-DOT; STELLAR MODELS; P-CYGNI; SN 1987A; SUPER-GIANTS AB The question of the effective criterion for convection and semiconvection to use in the inhomogeneous layers of models of massive stars is addressed here in terms of a choice between the Schwarzschild (temperature-gradient) criterion and the Ledoux (density-gradient) criterion. These two extremes give rise to and suppress, respectively, a fully convective zone (FCZ) in the layers immediately above the hydrogen-burning shell, if the star's mass is neither too low nor too high. Specifically, the existence of a large FCZ delays or prevents the star during core helium burning from becoming a red supergiant. The applicable range of initial stellar masses for a solar metallicity is approximately 13-30 M.. Nine different tests for the effective criterion for convection and semiconvection in Galactic supergiants, as well as a test using SN 1987A of the Large Magellanic Cloud, are performed, or reexamined, by using both old and new theoretical data, while three of the Galactic tests are repeated for association supergiants separately from cluster supergiants. Although eight of the 13 tests yield inconclusive results, five do support the Ledoux criterion, and three do so strongly. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 149 TC 18 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1994 VL 431 IS 2 BP 797 EP 805 DI 10.1086/174530 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC148 UT WOS:A1994PC14800032 ER PT J AU OLSON, KM DORBAND, JE AF OLSON, KM DORBAND, JE TI AN IMPLEMENTATION OF A TREE CODE ON A SIMD, PARALLEL COMPUTER SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 NASA,GODDARD SPACE FLIGHT CTR,CTR COMPUTAT SCI,GREENBELT,MD 20771. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1994 VL 431 IS 2 BP 904 EP 904 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC148 UT WOS:A1994PC14800049 ER PT J AU MEIER, SR KAFATOS, M FAHEY, RP MICHALITSIANOS, AG AF MEIER, SR KAFATOS, M FAHEY, RP MICHALITSIANOS, AG TI A FAR-ULTRAVIOLET ATLAS OF SYMBIOTIC STARS OBSERVED WITH IUE .1. THE SWP RANGE SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 GEORGE MASON UNIV,DEPT PHYS,FAIRFAX,VA 22030. GEORGE MASON UNIV,CSI INST,FAIRFAX,VA 22030. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1994 VL 431 IS 2 BP 906 EP 906 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC148 UT WOS:A1994PC14800053 ER PT J AU WILKING, BA CLAUSSEN, MJ BENSON, PJ MYERS, PC TEREBEY, S WOOTTEN, A AF WILKING, BA CLAUSSEN, MJ BENSON, PJ MYERS, PC TEREBEY, S WOOTTEN, A TI WATER MASERS ASSOCIATED WITH LOW-MASS STARS - A 13 MONTH MONITORING SURVEY SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; MASERS; STARS, PRE-MAIN-SEQUENCE ID H2O MASERS; MOLECULAR OUTFLOWS; FORMING REGIONS AB We report the results of a 13 month survey of embedded young stellar objects (YSOs) for H2O masers using the Haystack 37 m telescope. YSOs were selected to be in an early phase of evolution based on IRAS colors and association with molecular outflows or dense cores. The sample was restricted to YSOs in nearby clouds (d < 450 pc) with luminosities < 120 L.. Six new sources of water maser emission have been found, raising the total number of maser sources in this luminosity range to 20. Three sources (L1448C, L1534B, and VLA 1623) have luminosities less than 3 L.. Of the YSOs monitored on a regular basis, we estimate that maser activity occupies at least one-third of the duration of the embedded state. All sources with L > 25 L. displayed some maser activity. Although the maser strength of a given source can vary by two orders of magnitude, there is a general correlation between maser strength and YSO luminosity. For YSOs with L < 25 L., no single property, such as the CO mass-loss rate or luminosity at lambda = 6 cm, successfully predicts maser activity. We propose that other factors, such as the inclination of the outflow axis, may be important in enhancing the detectability of the masers in lower luminosity sources. C1 AOC,NRAO,SOCORRO,NM 87801. WELLESLEY COLL,WHITIN OBSERV,WELLESLEY,MA 02181. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. IPAC,JPL,PASADENA,CA 91125. CALTECH,IPAC,PASADENA,CA 91125. NRAO,CHARLOTTESVILLE,VA 22903. RP WILKING, BA (reprint author), UNIV MISSOURI,DEPT PHYS & ASTRON,8001 NAT BRIDGE RD,ST LOUIS,MO 63121, USA. NR 29 TC 44 Z9 44 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1994 VL 431 IS 2 BP L119 EP L122 DI 10.1086/187487 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC149 UT WOS:A1994PC14900013 ER PT J AU LERDAU, M DILTS, SB WESTBERG, H LAMB, BK ALLWINE, EJ AF LERDAU, M DILTS, SB WESTBERG, H LAMB, BK ALLWINE, EJ TI MONOTERPENE EMISSION FROM PONDEROSA PINE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HYDROCARBON EMISSIONS; ACETIC-ACID; ISOPRENE; MECHANISM; TREES AB We explore the variability in monoterpene emissions from ponderosa pine beyond that which can be explained by temperature alone. Specifically, we examine the roles that photosynthesis and needle monoterpene concentrations play in controlling emissions. We measure monoterpene concentrations and emissions, photosynthesis, temperature, and light availability in the late spring and late summer in a ponderosa pine forest in central Oregon. We use a combination of measurements from cuvettes and Teflon bag enclosures to show that photosynthesis is not correlated with emissions in the short term. We also show that needle monoterpene concentrations are highly correlated with emissions for two compounds, alpha-pinene and beta-pinene, but that DELTA-carene concentrations are not correlated with emissions. We suggest that direct effects of light and photosynthesis do not need to be included in emission algorithms. Our results indicate that the role of needle concentration bears further investigation; our results for alpha-pinene and beta-pinene are explainable by a Raoult's law relationship, but we cannot yet explain the cause of our results with DELTA-carene. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. WASHINGTON STATE UNIV, DEPT CIVIL & ENVIRONM ENGN, PULLMAN, WA 99164 USA. RP LERDAU, M (reprint author), STANFORD UNIV, STANFORD, CA 94305 USA. RI Lerdau, Manuel/E-7320-2011 OI Lerdau, Manuel/0000-0003-1864-0834 NR 38 TC 50 Z9 52 U1 4 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16609 EP 16615 DI 10.1029/94JD00406 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400024 ER PT J AU ROSENFIELD, JE NEWMAN, PA SCHOEBERL, MR AF ROSENFIELD, JE NEWMAN, PA SCHOEBERL, MR TI COMPUTATIONS OF DIABATIC DESCENT IN THE STRATOSPHERIC POLAR VORTEX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; ATMOSPHERIC HEATING RATE; MCMURDO-STATION; SOLAR-RADIATION; ARCTIC VORTEX; TRACE GASES; LATE WINTER; ER-2; PARAMETERIZATION; ABSORPTION AB A radiation model, together with National Meteorological Center temperature observations, was used to compute daily net heating rates in the northern hemisphere (NH) for the Arctic late fall and winter periods of both 1988-1989 and 1991-1992 and in the southern hemisphere (SH) for the Antarctic fall and winters of 1987 and 1992. The heating rates were interpolated to potential temperature (theta) surfaces between 400 K and 2000 K and averaged within the polar vortex, the boundary of which was determined by the maximum gradient in potential vorticity. The averaged heating rates were used in a one-dimensional vortex interior descent model to compute the change in potential temperature with time of air parcels initialized at various theta values, as well as to compute the descent in log pressure coordinates. In the NH vortex, air parcels which were initialized at 18 km on November 1, descended about 6 km by March 21, while air initially at 25 km descended 9 km in the same time period. This represents an average descent rate in the lower stratosphere of 1.3 to 2 km per month. Air initialized at 50 km descended 27 km between November 1 and March 21. In the SH vortex, parcels initialized at 18 km on March 1, descended 3 km, while air at 25 km descended 5-7 km by the end of October. This is equivalent to an average descent in the lower stratosphere of 0.4 to 0.9 km per month during this 8-month period. Air initialized at 52 km descended 26-29 km between March 1 and October 31. In both the NH and the SH, computed descent rates increased markedly with height. The descent for the NH winter of 1992-1993 and the SH winter of 1992 computed with a three-dimensional trajectory model using the same radiation code was within 1 to 2 km of that calculated by the one-dimensional model, thus validating the vortex averaging procedure. The computed descent rates generally agree well with observations of long-lived tracers, thus validating the radiative transfer model. RP ROSENFIELD, JE (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 39 TC 155 Z9 155 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16677 EP 16689 DI 10.1029/94JD01156 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400030 ER PT J AU LUO, M CICERONE, RJ RUSSELL, JM HUANG, TYW AF LUO, M CICERONE, RJ RUSSELL, JM HUANG, TYW TI OBSERVATIONS OF STRATOSPHERIC HYDROGEN-FLUORIDE BY HALOGEN OCCULTATION EXPERIMENT (HALOE) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ARCTIC WINTER STRATOSPHERE; TRACER DISTRIBUTIONS; CHLORIDE; MODEL; HCL; HF; SPECTROSCOPY; OSCILLATION AB The Halogen Occultation Experiment (HALOE) Hydrogen Fluoride (HF) channel on the Upper Atmospheric Research Satellite is providing the first global measurements of stratospheric HF, the dominant fluorine reservoir in the atmosphere. This paper describes the latitudinal and seasonal variations of HALOE-observed HF in terms of vertical profiles, altitude/latitude cross sections, and column abundances. The HF global distribution shows a ''tracerlike'' structure and its column amount increases with latitude, in agreement with previous aircraft measurements of the HF column amount. A comparison between the HALOE HF column above 20 km and the ATMOS 1985 measurements is used to estimate the annual rate of increase of stratospheric HF. Exponential rates of 4.9-6.6% yr-1 and linear growth rates of 6-8.6% yr-1 in 1985 and 4.3-5.5% yr-1 iii 1992-1993 are found. HALOE HF measurements during the 1993 Antarctic spring are briefly described. This species behaves like a conserved tracer and its distribution shows an area of enhanced mixing ratios correlated with the polar vortex that has a clear latitude boundary. Finally, simulated HF distributions by the National Center for Atmospheric Research two-dimensional model are used to compare with HALOE observations of HF. Reasonable agreements in the global structure and the absolute amount of HF are found. The differences between the model and the observed results indicate the need for improving treatment of atmospheric dynamics and fluorine-related chemical parameters in the model simulations. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NATL CTR ATMOSPHER RES, ADV STUDY PROGRAM, BOULDER, CO 80307 USA. RP LUO, M (reprint author), UNIV CALIF IRVINE, DEPT EARTH SYST SCI, IRVINE, CA 92717 USA. NR 40 TC 20 Z9 21 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16691 EP 16705 DI 10.1029/94JD01246 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400031 ER PT J AU ROBERTI, L HAFERMAN, J KUMMEROW, C AF ROBERTI, L HAFERMAN, J KUMMEROW, C TI MICROWAVE RADIATIVE-TRANSFER THROUGH HORIZONTALLY INHOMOGENEOUS PRECIPITATING CLOUDS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID FINITE CLOUDS; HYDROMETEORS; RADIANCES; MODEL AB Recent advances in cloud microphysical models have led to realistic three-dimensional distributions of cloud constituents. Radiative transfer schemes can make-use of this detailed knowledge in order to study the effects of horizontal as well as vertical inhomogeneities within clouds. This study looks specifically at the differences between three-dimensional radiative transfer results and those obtained by plane parallel, independent pixel approximations in the microwave spectrum. A three-dimensional discrete ordinates method as well as a backward Monte Carlo method are used to calculate realistic radiances emerging from the cloud. Analyses between these models and independent pixel approximations reveal that plane parallel approximations introduce two distinct types of errors. The first error is physical in nature and is related to the fact that plane parallel approximations do not allow energy to leak out of dense areas into surrounding areas. In general, it was found that these errors are quite small for emission-dominated frequencies (37 GHz and lower) and that physical errors are highly pronounced only at scattering frequencies (85 GHz) where large deviations and biases up to 8 K averaged over the entire cloud were found. The second error is more geometric in nature and is related to the fact that plane parallel approximations cannot accommodate physical boundaries in the horizontal dimension for off-nadir viewing angles. The geometric errors were comparable in magnitude for all frequencies. Their magnitude, however, depends on a number of factors including the scheme used to deal with the edge, the nature of the surface, and the viewing angle. C1 UNIV IOWA, DEPT MECH ENGN, IOWA CITY, IA 52242 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP POLITECN TORINO, DIPARTIMENTO ELETTR, CORSO DUCA ABRUZZI 24, I-10100 TURIN, ITALY. NR 29 TC 64 Z9 65 U1 0 U2 3 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 AUG 20 PY 1994 VL 99 IS D8 BP 16707 EP 16718 DI 10.1029/94JD01150 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400032 ER PT J AU ZANDER, R RINSLAND, CP MAHIEU, E GUNSON, MR FARMER, CB ABRAMS, MC KO, MKW AF ZANDER, R RINSLAND, CP MAHIEU, E GUNSON, MR FARMER, CB ABRAMS, MC KO, MKW TI INCREASE OF CARBONYL FLUORIDE (COF2) IN THE STRATOSPHERE AND ITS CONTRIBUTION TO THE 1992 BUDGET OF INORGANIC FLUORINE IN THE UPPER-STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MOLECULE SPECTROSCOPY EXPERIMENT; HYDROGEN-FLUORIDE; PARAMETERS; ATMOSPHERE; PROFILES; DIOXIDE; SPECTRA; TRENDS; HF AB Volume mixing ratio profiles of COF2 have been derived through most of the stratosphere between 30-degrees-N and 54-degrees-S from series of 0.01-cm-1 resolution infrared solar spectra recorded in the occultation mode by the atmospheric trace molecule spectroscopy (ATMOS) instrument during the ATLAS 1 space shuttle mission of March-April 1992. When compared with similar results obtained from the ATMOS/Spacelab 3 mission of April-May 1985, the cumulative increase in the burden of COF2 in the middle and upper stratosphere was found to be 67% for that 7-year time interval. By combining a subset of these COF2 results with upper stratospheric concentrations of HF also derived from the ATMOS observations, it was further found that the budget of inorganic fluorine above 35 km altitude increased by (60 +/- 10) % over the 1985-1992 time interval, which corresponds to an average exponential rate of increase of (6.7 +/- 1.1)% yr-1, or a linear rate of increase referenced to 1985 of (8.5 +/- 1.3) % yr-1 at the 1 sigma confidence level. The total inorganic F atom volume mixing ratio found in the upper stratosphere for 1985 and 1992 and the increase during this period mirror the rise in man-made fluorine-bearing compounds at the ground during the early to mid 1980s. This demonstrates the negligible impact of natural sources of fluorine, in particular volcanic activity, on the observed change of F in the upper stratosphere. Implications of the present findings and comparison with model results are discussed. C1 JET PROP LAB, PASADENA, CA 91109 USA. AER INC, CAMBRIDGE, MA 02139 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23685 USA. RP ZANDER, R (reprint author), UNIV LIEGE, INST ASTROPHYS, 5 AVE COINTE, B-4000 LIEGE, BELGIUM. RI Ko, Malcolm/D-5898-2015 NR 37 TC 17 Z9 17 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16737 EP 16743 DI 10.1029/94JD01029 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400034 ER PT J AU ZANDER, R EHHALT, DH RINSLAND, CP SCHMIDT, U MAHIEU, E RUDOLPH, J DEMOULIN, P ROLAND, G DELBOUILLE, L SAUVAL, AJ AF ZANDER, R EHHALT, DH RINSLAND, CP SCHMIDT, U MAHIEU, E RUDOLPH, J DEMOULIN, P ROLAND, G DELBOUILLE, L SAUVAL, AJ TI SECULAR TREND AND SEASONAL VARIABILITY OF THE COLUMN ABUNDANCE OF N2O ABOVE THE JUNGFRAUJOCH STATION DETERMINED FROM IR SOLAR SPECTRA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITROUS-OXIDE EMISSIONS; VERTICAL-DISTRIBUTION; ATMOSPHERIC N2O; CARBON-MONOXIDE; CLIMATE CHANGE; TRACE GASES; DATABASE; INCREASE; METHANE; IMPACT AB Infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch (3580 m altitude), Switzerland, in 1950-1951 and from 1984 to 1992 have been analyzed to determine vertical column abundances of nitrous oxide (N2O) above the station. The best fit to the relatively dense set of measurements made between 1984 and 1992 indicates a mean exponential rate of increase equal to 0.36 +/- 0.06% yr-1 (1 sigma) and a seasonal modulation of 7.2% peak to peak, the minimum occurring at the end of the winter and the maximum in early September. The column abundances for April of the years 1951, 1984, and 1992 were found equal to 3.49 x 10(18), 3.76 x 10(18), and 3.87 x 10(18) molecules cm-2, respectively; they translate into N2O concentrations at the altitude of the Jungfraujoch equal to 275, 296, and 305 parts per billion by volume. These results indicate that the exponential rate of increase for 1951-1984 was equal to 0.23 +/- 0.04% yr-1 (1 sigma), thus substantially lower than for the 1984-1992 time interval and that the so-called preindustrial levels of N2O pertained until 1951 with most of the increase in atmospheric N2O occurring thereafter. C1 FORSCHUNGSZENTRUM JULICH, D-52425 JULICH, GERMANY. NASA, LANGLEY RES CTR, HAMPTON, VA 23685 USA. ROYAL OBSERV BELGIUM, B-1180 BRUSSELS, BELGIUM. RP UNIV LIEGE, INST ASTROPHYS, 5 AVE COINTE, B-4000 LIEGE, BELGIUM. NR 54 TC 23 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16745 EP 16756 DI 10.1029/94JD01030 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400035 ER PT J AU CONNOR, BJ SISKIND, DE TSOU, JJ PARRISH, A REMSBERG, EE AF CONNOR, BJ SISKIND, DE TSOU, JJ PARRISH, A REMSBERG, EE TI GROUND-BASED MICROWAVE OBSERVATIONS OF OZONE IN THE UPPER-STRATOSPHERE AND MESOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DIURNAL-VARIATIONS; MIDDLE ATMOSPHERE; TEMPERATURE; RADIOMETRY; PROFILES AB A 9-month-long series of measurements of ozone in the upper stratosphere and mesosphere is reported. The measurements are presented as monthly averages of profiles in blocks of roughly 20 min local time and as night-to-day ratios. An error analysis predicts accuracies of 5-26% for the monthly profiles and 2.5-9% for the ratios. The data are compared to historical data from SME and limb infrared monitor of the stratosphere (LIMS), and it is shown how to remove the effect of different vertical resolution from the comparisons. The microwave data typically agree to better than 10% with SME and nighttime LIMS ozone at all altitudes below the 0.1-mbar surface. Comparison of the microwave night-to-day ratio with the corresponding ratio from LIMS suggests that nonlocal thermodynamic equilibrium effects in the LIMS daytime data exceed 10% at all pressures less than or equal to 1 mbar. C1 LOCKHEED ENGN & SCI CO, HAMPTON, VA 23666 USA. UNIV MASSACHUSETTS, AMHERST, MA 01003 USA. USN, RES LAB, WASHINGTON, DC 20375 USA. RP CONNOR, BJ (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NR 24 TC 92 Z9 92 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16757 EP 16770 DI 10.1029/94JD01153 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400036 ER PT J AU FAN, SM JACOB, DJ MAUZERALL, DL BRADSHAW, JD SANDHOLM, ST BLAKE, DR SINGH, HB TALBOT, RW GREGORY, GL SACHSE, GW AF FAN, SM JACOB, DJ MAUZERALL, DL BRADSHAW, JD SANDHOLM, ST BLAKE, DR SINGH, HB TALBOT, RW GREGORY, GL SACHSE, GW TI ORIGIN OF TROPOSPHERIC NOX OVER SUB-ARCTIC EASTERN CANADA IN SUMMER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OBSERVATORY PHOTOCHEMISTRY EXPERIMENT; GAS-PHASE REACTION; PEROXYACETYL NITRATE; ORGANIC-COMPOUNDS; RADIOMETER MEASUREMENTS; PHOTOSTATIONARY STATE; CHEMISTRY; NITROGEN; OZONE; OH AB The origin of NO(x) in the summertime troposphere over subarctic eastern Canada is investigated by photochemical modeling of aircraft and ground-based measurements from the Arctic Boundary Layer Expedition (ABLE 3B). It is found that decomposition of peroxyacetyl nitrate (PAN) can account for most of the NO(x) observed between the surface and 6.2 km altitude (aircraft ceiling). Forest fires represent the principal source of PAN in the region, implying the same origin for NO(x). There is, however, evidence for an unidentified source of NO., in occasional air masses subsiding from the upper troposphere. Isoprene emissions from boreal forests maintain high NO(x) concentrations in the continental boundary layer over eastern Canada by scavenging OH and NO3, thus slowing down conversion of NO(x) to HNO3, both in the daytime and at night. This effect is partly compensated by the production of CH3CO3 radicals during isoprene oxidation, which slows down the decomposition of PAN subsiding from the free troposphere. The peroxy radical concentrations estimated from concurrent measurements of NO and NO2 concentrations during ABLE 3B are consistent with values computed from our photochemical model below 4 km, but model values are low at higher altitudes. The discrepancy may reflect either a missing radical source in the model or interferences in the NO2 measurement. C1 UNIV CALIF IRVINE, DEPT CHEM, IRVINE, CA 92171 USA. UNIV NEW HAMPSHIRE, COMPLEX SYST RES CTR, DURHAM, NH 03814 USA. GEORGIA INST TECHNOL, SCH EARTH & ATMOSPHER SCI, ATLANTA, GA 30332 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 22331 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94305 USA. RP FAN, SM (reprint author), HARVARD UNIV, DIV APPL SCI, CAMBRIDGE, MA 02138 USA. RI Mauzerall, Denise/I-5977-2013 OI Mauzerall, Denise/0000-0003-3479-1798 NR 64 TC 73 Z9 73 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1994 VL 99 IS D8 BP 16867 EP 16877 DI 10.1029/94JD01122 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC944 UT WOS:A1994PC94400045 ER PT J AU MIELKE, SL LYNCH, GC TRUHLAR, DG SCHWENKE, DW AF MIELKE, SL LYNCH, GC TRUHLAR, DG SCHWENKE, DW TI AB-INITIO CHEMICAL-KINETICS - CONVERGED QUANTAL REACTION-RATE CONSTANTS FOR THE D+H-2 SYSTEM SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POTENTIAL-ENERGY SURFACE; INTEGRAL CROSS-SECTIONS; QUANTIZED TRANSITION-STATES; WAVE VARIATIONAL PRINCIPLE; BASIS-SET CALCULATIONS; MANY-BODY EXPANSION; S-MATRIX VERSION; SCATTERING CALCULATIONS; ROTATIONAL-EXCITATION; REACTION H+H2->H2+H AB We present accurate quantal rate constants for the D + H-2 system in the 167-900 K temperature range and rate constants calculated in the separable rotation approximation up to 1500 K. We have calculated rate constants for the three most accurate ab initio potential energy surfaces. The separable-rotation calculations agree to within 2.2% with the present accurate quantal calculations, and the results show substantially better agreement with high-temperature experimental rate constants than do previous quantal calculations. The ab initio rate constants for the LSTH and DMBE surfaces agree well with experiment over a wide temperature range; but the newer BKMP surface gives poor agreement at low temperatures. From 200 to 900 K, a factor of 4.5 in temperature, the present totally ab initio reaction rate constants agree with experiment within 13% or better at each temperature, with an average absolute deviation of only 5%. C1 UNIV MINNESOTA, DEPT CHEM, CHEM PHYS PROGRAM, MINNEAPOLIS, MN 55455 USA. UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 97 TC 95 Z9 97 U1 0 U2 8 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 AUG 18 PY 1994 VL 98 IS 33 BP 8000 EP 8008 DI 10.1021/j100084a014 PG 9 WC Chemistry, Physical SC Chemistry GA PC619 UT WOS:A1994PC61900014 ER PT J AU ISKOVITZ, I CHANG, TYP SALEEB, AF AF ISKOVITZ, I CHANG, TYP SALEEB, AF TI EXTENSION OF AN ASYMPTOTIC ALGORITHM TO ORTHOTROPIC VISCOPLASTIC STRUCTURAL-ANALYSIS SO COMPUTERS & STRUCTURES LA English DT Article ID TEMPERATURE AB The modern applications of structures, operating under severe loading conditions and at an elevated temperature, result in nonlinear viscoplastic material behavior. The inevitable prediction of the mechanical response leads to an expensive numerical analysis. In the following, a numerical study is presented for a new, asymptotic, numerical method applied to an orthotropic viscoplastic material. Its numerical features are compared to those of the explicit Runge-Kutta method. A canonical transformation and an adaptive step scheme are included within the material solver for algorithmic efficiency and solution accuracy. The asymptotic algorithm appears to be computationally appearing especially in regions of numerical stiffness and, in general, it tolerates larger iterative steps. C1 HONG KONG UNIV SCI & TECHNOL,DEPT CIVIL ENGN,KOWLOON,HONG KONG. UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. RP ISKOVITZ, I (reprint author), NASA,LEWIS RES CTR,MS 105-1,CLEVELAND,OH 44135, USA. NR 20 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD AUG 17 PY 1994 VL 52 IS 4 BP 667 EP 678 DI 10.1016/0045-7949(94)90348-4 PG 12 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA PC028 UT WOS:A1994PC02800007 ER PT J AU LOSEY, GS BALAZS, GH PRIVITERA, LA AF LOSEY, GS BALAZS, GH PRIVITERA, LA TI CLEANING SYMBIOSIS BETWEEN THE WRASSE, THALASSOMA-DUPERRY, AND THE GREEN TURTLE, CHELONIA-MYDAS SO COPEIA LA English DT Article ID LABROIDES-PHTHIROPHAGUS LABRIDAE; PREFERENCE; HAWAII; FISHES AB A previously undocumented association between green turtles and wrasses is reported from several sites in Hawaii. Observations from videotaped encounters at common turtle aggregation sites indicated that turtles exhibited a solicitation posture for cleaning of ectoparasites by wrasses (Thalassoma duperry). Time-lapse activity budgets revealed at least one turtle present nearly half of the time and posing for cleaning over one-third of the time. Gut contents of wrasses captured from these cleaning stations revealed that some of the fish had specialized to feed exclusively on ectoparasitic barnacles from the skin of turtles. No barnacles were found in the gut contents of wrasses caught more than 10 m from the cleaning stations. We propose several possible explanations for the development and adaptive significance of this symbiotic relationship, particularly with respect to the recent epidemic outbreak of fibropapilloma or ''tumor'' infections in green turtles in Hawaii. C1 NATL MARINE FISHERIES SERV, SW FISHERIES SCI CTR, HONOLULU LAB, HONOLULU, HI 96822 USA. RP LOSEY, GS (reprint author), UNIV HAWAII, HAWAII INST MARINE BIOL, POB 1346, KANEOHE, HI 96744 USA. NR 21 TC 29 Z9 30 U1 1 U2 6 PU AMER SOC ICHTHYOLOGISTS & HERPETOLOGISTS PI MIAMI PA MAUREEN DONNELLY, SECRETARY FLORIDA INT UNIV BIOLOGICAL SCIENCES, 11200 SW 8TH STREET, MIAMI, FL 33199 USA SN 0045-8511 EI 1938-5110 J9 COPEIA JI Copeia PD AUG 17 PY 1994 IS 3 BP 684 EP 690 PG 7 WC Zoology SC Zoology GA PD127 UT WOS:A1994PD12700011 ER PT J AU ROLAND, FS MOLINA, MJ AF ROLAND, FS MOLINA, MJ TI OZONE DEPLETION - 20 YEARS AFTER THE ALARM SO CHEMICAL & ENGINEERING NEWS LA English DT Article C1 UNIV CALIF IRVINE,IRVINE,CA 92717. NATL ACAD SCI,WASHINGTON,DC 20418. JET PROP LAB,DEPT CHEM,PASADENA,CA 91109. JET PROP LAB,DEPT EARTH ATMOSPHERE & PLANETARY SCI,PASADENA,CA 91109. NR 2 TC 1 Z9 2 U1 1 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0009-2347 J9 CHEM ENG NEWS JI Chem. Eng. News PD AUG 15 PY 1994 VL 72 IS 33 BP 8 EP 13 PG 6 WC Chemistry, Multidisciplinary; Engineering, Chemical SC Chemistry; Engineering GA PB651 UT WOS:A1994PB65100011 ER PT J AU LOCKWOOD, M COWLEY, SWH SMITH, MF AF LOCKWOOD, M COWLEY, SWH SMITH, MF TI B(Y) FLUCTUATIONS IN THE MAGNETOSHEATH AND AZIMUTHAL FLOW VELOCITY TRANSIENTS IN THE DAYSIDE IONOSPHERE - COMMENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Note ID INTERPLANETARY MAGNETIC-FIELD; MAGNETOPAUSE; EVENTS C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. 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 OI Lockwood, Mike/0000-0002-7397-2172 NR 10 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 AUG 15 PY 1994 VL 21 IS 17 BP 1819 EP 1820 DI 10.1029/94GL01360 PG 2 WC Geosciences, Multidisciplinary SC Geology GA PC817 UT WOS:A1994PC81700019 ER PT J AU ERLANDSON, RE ZANETTI, LJ ACUNA, MH ERIKSSON, AI ELIASSON, L BOEHM, MH BLOMBERG, LG AF ERLANDSON, RE ZANETTI, LJ ACUNA, MH ERIKSSON, AI ELIASSON, L BOEHM, MH BLOMBERG, LG TI FREJA OBSERVATIONS OF ELECTROMAGNETIC ION-CYCLOTRON ELF WAVES AND TRANSVERSE OXYGEN-ION ACCELERATION ON AURORAL FIELD LINES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RESONANCE AB Extremely low-frequency (ELF) magnetic and electric field plasma wave emissions were recorded on 2 October 1993 on auroral field lines by the Magnetic Field Experiment during Freja orbit 4770. The ELF wave frequencies were below the local oxygen gyrofrequency (25 Hz) and between the helium and proton gyrofrequencies (100 to 400 Hz). The ELF waves, interpreted as electromagnetic ion cyclotron (EMIC) waves, were observed in a region of inverted-V-type electron precipitation. The EMIC waves were correlated over time with auroral and lower energy (almost-equal-to 100 eV) electrons, which are both possible sources of free energy, and also with transversely accelerated oxygen ions. The waves above the helium gyrofrequency were more closely correlated with the transverse oxygen ion acceleration than the waves below the oxygen gyrofrequency. These observations are consistent with a scenario in which electron beams generate EMIC waves, which then produce transverse oxygen ion acceleration through a gyroresonant interaction. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SWEDISH INST SPACE PHYS,UPPSALA,SWEDEN. SWEDISH INST SPACE PHYS,KIRUNA,SWEDEN. MAX PLANCK INST EXTRATERR PHYS,GARCHING,GERMANY. ROYAL INST TECHNOL,S-10044 STOCKHOLM 70,SWEDEN. RP ERLANDSON, RE (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723, USA. RI Eriksson, Anders/C-2887-2009; Erlandson, Robert/G-2767-2015 NR 16 TC 61 Z9 62 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1994 VL 21 IS 17 BP 1855 EP 1858 DI 10.1029/94GL01363 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PC817 UT WOS:A1994PC81700029 ER PT J AU ZANETTI, LJ POTEMRA, TA ANDERSON, BJ ERLANDSON, RE HOLLAND, DB ACUNA, MH KAPPENMAN, J LESHER, R FEERO, B AF ZANETTI, LJ POTEMRA, TA ANDERSON, BJ ERLANDSON, RE HOLLAND, DB ACUNA, MH KAPPENMAN, J LESHER, R FEERO, B TI IONOSPHERIC CURRENTS CORRELATED WITH GEOMAGNETIC INDUCED CURRENTS - FREJA MAGNETIC-FIELD MEASUREMENTS AND THE SUNBURST MONITOR SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PARTICLE ENVIRONMENT MONITOR; ALIGNED CURRENTS; SATELLITE; TRIAD AB Temporal and spatial fluctuations of large-scale electric currents totaling millions of amperes in the ionosphere have long been known to induce current and voltage in the Earth's surface and on large manmade conductive structures. A strong, persistent solar wind can interact with the geomagnetic environment and produce auroral zone currents at mid latitudes. Presented here is a specific correlation of ionospheric auroral currents inferred from magnetic field measurements from the Swedish Freja satellite and induced current in the electric power distribution system on the east coast of the United States, in particular the Chalk Point, Maryland, transformer station. The event discussed here registered a Kp level of 6 to 8 and occurred on April 4-5, 1993. An important aspect is that information from both of these space- and ground-based monitoring systems is available automatically and in real time. In addition, satellite data from earlier local times, e.g., data monitored from European ground stations, can give precursor information of later North American geomagnetic activity. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MINNESOTA POWER,DULUTH,MN. ELECT RES & MANAGEMENT INC,STATE COLL,PA. RP ZANETTI, LJ (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707, USA. RI Anderson, Brian/I-8615-2012; Erlandson, Robert/G-2767-2015 NR 24 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1994 VL 21 IS 17 BP 1867 EP 1870 DI 10.1029/94GL01425 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PC817 UT WOS:A1994PC81700032 ER PT J AU CHEN, JS KOLAWA, E NICOLET, MA RUIZ, RP BAUD, L JAUSSAUD, C MADAR, R AF CHEN, JS KOLAWA, E NICOLET, MA RUIZ, RP BAUD, L JAUSSAUD, C MADAR, R TI REACTION OF TA THIN-FILM WITH SINGLE-CRYSTALLINE (001) BETA-SIC SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SOLID-STATE REACTIONS; SILICON-CARBIDE; SYSTEMS; METALS AB The reaction between a sputter-deposited Ta film (320 nm thick) and a single crystalline (001) beta-SiC substrate induced by vacuum annealing at temperatures of 600-1200-degrees-C for 1 h (30 min at 1100-degrees-C) is investigated by 3 MeV He++ backscattering spectrometry, x-ray diffraction, secondary ion mass spectrometry, and transmission and scanning electron microscopies. No significant reaction is observed at 800-degrees-C or at lower temperatures. At 900-degrees-C, the main product phases are Ta2C and carbon-stabilized Ta5Si3. A minor amount of unreacted Ta is also present. After annealing at 1000-degrees-C, all the tantalum has reacted; the reaction zone possesses a multilayered structure of beta-SiC/TaC/carbon-stabilized Ta5Si3/alpha-Ta5Si3/Ta2C. The diffusion path at 1000-degrees-C is plotted on the isothermal section of the Ta-Si-C phase diagram. At 1100-degrees-C, the reacted layer has an interface with the SiC substrate that is still quite flat but has a rough surface due to the formation of macroscopic voids within the reacted layer. The equilibrium products predicted by the phase diagram are TaC and TaSi2. This final state is reached by annealing at 1200-degrees-C for 1 h. At that point, the reacted layer has a laterally very uneven structure and morphology. C1 JET PROP LAB,PASADENA,CA 91109. CENG,DMEL,LETI,F-38041 GRENOBLE,FRANCE. ENSPG,LMGP,F-38402 ST MARTIN DHERES,FRANCE. RP CHEN, JS (reprint author), CALTECH,PASADENA,CA 91125, USA. RI Chen, Jen-Sue/A-3298-2015 NR 40 TC 17 Z9 17 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD AUG 15 PY 1994 VL 76 IS 4 BP 2169 EP 2175 DI 10.1063/1.357629 PG 7 WC Physics, Applied SC Physics GA PC021 UT WOS:A1994PC02100024 ER PT J AU BAUSCHLICHER, CW AF BAUSCHLICHER, CW TI A THEORETICAL-STUDY OF CO/CU(100) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID COUPLED-CLUSTER THEORY; GAUSSIAN-BASIS SETS; ELECTRON CORRELATION; CO; CU(100); CHEMISORPTION; ENERGY; ATOMS; CUCO; SURFACE AB The convergence of the binding energy, geometry, and vibrational frequencies for CO/Cu(100) is studied using a cluster model containing up to 38 Cu atoms. A large basis set is used for the Cu atom at the adsorption site and for the CO molecule. Electron correlation, which is included at the modified coupled-pair functional (MCPF) level, is found to increase the binding energy by about 1 eV. The binding energy and geometry are in very good agreement with experiment for the largest Cu clusters considered. The MCPF binding energies for the smaller clusters can be either larger or smaller than experiment. Unlike the binding energies, the shift in the CO vibrational frequency, relative to foe CO, is quite independent of the cluster size or even the inclusion of electron correlation. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 49 Z9 49 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 AUG 15 PY 1994 VL 101 IS 4 BP 3250 EP 3254 DI 10.1063/1.467572 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PA009 UT WOS:A1994PA00900066 ER PT J AU HAINES, BJ BORN, GH WILLIAMSON, RG KOBLINSKY, CJ AF HAINES, BJ BORN, GH WILLIAMSON, RG KOBLINSKY, CJ TI APPLICATION OF THE GEM-T2 GRAVITY-FIELD TO ALTIMETRIC SATELLITE ORBIT COMPUTATION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID EXACT REPEAT MISSION; GRAVITATIONAL MODEL; SEASAT; IMPROVEMENT; TRACKING AB As part of a continuing effort to provide improved orbits for use with existing altimeter data, we have recomputed ephemerides for both the Seasat and Geosat Exact Repeat altimeter missions. The orbits were computed in a consistent fashion, using the Goddard Earth Model T2 gravity field along with available ground-based tracking data. Such an approach allows direct comparisons of sea level between the two altimeter systems. Evaluation of the resulting ephemerides indicates that root-mean-square accuracies of 30-50 cm have been achieved for the radial component of the orbits for both satellites. An exception occurs for the last year of the Geosat Exact Repeat Mission, when the rms radial orbit accuracy degrades to the 1-m level at times owing to the inability to adequately model the drag force arising from the increased solar activity. C1 UNIV COLORADO,COLORADO CTR ASTRODYNAM RES,BOULDER,CO 80310. NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. NR 47 TC 8 Z9 8 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 1994 VL 99 IS C8 BP 16237 EP 16254 DI 10.1029/94JC00257 PG 18 WC Oceanography SC Oceanography GA PC018 UT WOS:A1994PC01800020 ER PT J AU PARKINSON, CL AF PARKINSON, CL TI SPATIAL PATTERNS IN THE LENGTH OF THE SEA-ICE SEASON IN THE SOUTHERN-OCEAN, 1979-1986 SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID CARBON-DIOXIDE; EDGE BANDS; EXCHANGE AB The length of the sea ice season summarizes in one number the ice coverage conditions for an individual location for an entire year. It becomes a particularly valuable variable when mapped spatially over a large area and examined for regional and interannual differences, as is done here for the Southern Ocean over the years 1979-1986, using the satellite passive microwave data of the Nimbus 7 scanning multichannel microwave radiometer. Three prominent geographic anomalies in ice season lengths occur consistently in each year of the data set, countering the general tendency toward shorter ice seasons from south to north: (1) In the Weddell Sea the tendency is toward shorter ice seasons from southwest to northeast, reflective of the cyclonic ice/atmosphere/ocean circulations in the Weddell Sea region. (2) Directly north of the Ross Ice Shelf anomalously short ice seasons occur, lasting only 245-270 days, in contrast to the perennial ice coverage at comparable latitudes in the southern Bellingshausen and Amundsen Seas and in the western Weddell Sea. The short ice season off the Ross Ice Shelf reflects the consistently early opening of the ice cover each spring, under the influence of upwelling along the continental slope and shelf and atmospheric forcing from winds blowing off the Antarctic continent. (3) In the southern Amundsen Sea, anomalously short ice seasons occur adjacent to the coast, owing to the frequent existence of coastal polynyas off the many small ice shelves bordering the sea. Least squares trends in the ice season lengths over the 1979-1986 period are highly coherent spatially, with overall trends toward shorter ice seasons in the northern Weddell and Bellingshausen seas and toward longer ice seasons in the Ross Sea, around much of East Antarctica, and in a portion of the south central Weddell Sea. RP PARKINSON, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 24 TC 40 Z9 40 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 1994 VL 99 IS C8 BP 16327 EP 16339 DI 10.1029/94JC01146 PG 13 WC Oceanography SC Oceanography GA PC018 UT WOS:A1994PC01800025 ER PT J AU CHENG, Y CANUTO, VM AF CHENG, Y CANUTO, VM TI STABLY STRATIFIED SHEAR TURBULENCE - A NEW MODEL FOR THE ENERGY-DISSIPATION LENGTH SCALE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID LAGRANGIAN VELOCITY AUTOCORRELATION; LARGE-EDDY SIMULATION; ISOTROPIC TURBULENCE; BOUNDARY-LAYER; ATMOSPHERE; DIFFUSION; CLOSURES AB A model is presented to compute the turbulent kinetic energy dissipation length scale l(epsilon) in a stably stratified shear flow. The expression for l(epsilon) is derived from solving the spectral balance equation for the turbulent kinetic energy. The buoyancy spectrum entering such equation is constructed using a Lagrangian timescale with modifications due to stratification. The final result for l(epsilon) is given in algebraic form as a function of the Froude number Fr and the flux Richardson number R(f), l(epsilon) = l(epsilon)(Fr, R(f)). The model predicts that for R(f) < R(fc), l(epsilon) decreases with stratification or shear; (or R(f) > R(fc), which may occur in subgrid-scale models, l(epsilon) increases with stratification. An attractive feature of the present model is that it encompasses, as special cases, some seemingly different models for l(epsilon) that have been proposed in the past by Deardorff, Hunt et al., Weinstock, and Canuto and Minotti. An alternative form for the dissipation rate epsilon is also discussed that may be useful when one uses a prognostic equation for the heat flux. The present model is applicable to subgrid-scale models, which are needed in large eddy simulations (LES), as well as to ensemble average models. The model is applied to predict the variation of l(epsilon) with height z in the planetary boundary layer. The resulting l(epsilon) versus z profile reproduces very closely the nonmonotonic profile of l(epsilon) exhibited by many LES calculations, beginning with the one by Deardorff in 1974. C1 NASA,GSFC,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025. NR 44 TC 22 Z9 23 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 1994 VL 51 IS 16 BP 2384 EP 2396 DI 10.1175/1520-0469(1994)051<2384:SSSTAN>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC037 UT WOS:A1994PC03700004 ER PT J AU CAHALAN, RF RIDGWAY, W WISCOMBE, WJ BELL, TL SNIDER, JB AF CAHALAN, RF RIDGWAY, W WISCOMBE, WJ BELL, TL SNIDER, JB TI THE ALBEDO OF FRACTAL STRATOCUMULUS CLOUDS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID RADIATION BUDGET EXPERIMENT; SHAPED OPTICAL MEDIA; CLIMATE; SATELLITE; PARAMETERIZATION; STATISTICS; SCATTERING; SPECTRA; FIELDS; COVER AB An increase in the planetary albedo of the earth-atmosphere system by only 10% can decrease the equilibrium surface temperature to that of the last ice age. Nevertheless, albedo biases of 10% or greater would be introduced into large regions of current climate models if clouds were given their observed liquid water amounts, because of the treatment of clouds as plane parallel. Past work has addressed the effect of cloud shape on albedo; here the focus is on the within-cloud variability of the vertically integrated liquid water. The main result is an estimate of the ''plane-parallel albedo bias'' using the ''independent pixel approximation.'' which ignores net horizontal photon transport, from a simple fractal model of marine stratocumulus clouds that ignores the cloud shape. The use of the independent pixel approximation in this context will be justified in a separate Monte Carlo study. The focus on marine stratocumulus clouds is due to their important role in cloud radiative forcing and also that, of the wide variety of earth's cloud types, they are most nearly plane parallel, so that they have the least albedo bias. The fractal model employed here reproduces both the probability distribution and the wavenumber spectrum of the stratocumulus liquid water path, as observed during the First ISCCP Regional Experiment (FIRE). The model distributes the liquid water by a cascade process, related to the upscale cascade of energy transferred from the cloud thickness scale to the mesoscale by approximately 2D motions. For simplicity, the cloud microphysical parameters are assumed homogeneous, as is the geometrical cloud thickness; and the mesoscale-averaged vertical optical thickness is kept fixed at each step of the cascade. A single new fractal parameter, 0 less-than-or-equal-to f less-than-or-equal-to 1, is introduced and determined empirically by the variance of the logarithm of the vertically integrated liquid water- In the case of conservative scattering, the authors are able to estimate the albedo bias analytically as a function of the fractal parameter f, mean vertical optical thickness tau(upsilon), and sun angle theta. Typical observed values are f = 0.5, tau(upsilon) = 15, and theta = 60-degrees, which give an absolute bias of 0.09, or a relative bias equal to 15% of the plane-parallel albedo of 0.60. The reduced reflectivity of fractal stratocumulus clouds is approximately given by the plane-parallel reflectivity evaluated at a reduced ''effective optical thickness,'' which when f = 0.5 is tau(eff) almost-equal-to 10. Study of the diurnal cycle of stratocumulus liquid water during FIRE leads to a key unexpected result: the plane-parallel albedo bias is largest when the cloud fraction reaches 100%, that is, when any bias associated with the cloud fraction vanishes. This is primarily due to the variability increase with cloud fraction. Thus, the within-cloud fractal structure of stratocumulus has a more significant impact on estimates of its mesoscale-average albedo than does the cloud fraction. C1 NOAA,ERL,WAVE PROPAGAT LAB,BOULDER,CO 80303. APPL RES CORP,LANDOVER,MD. RP CAHALAN, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERE LAB,CODE 913,GREENBELT,MD 20771, USA. RI Cahalan, Robert/E-3462-2012; Bell, Thomas/G-5425-2012; Wiscombe, Warren/D-4665-2012 OI Cahalan, Robert/0000-0001-9724-1270; Wiscombe, Warren/0000-0001-6844-9849 NR 52 TC 376 Z9 382 U1 3 U2 26 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 1994 VL 51 IS 16 BP 2434 EP 2455 DI 10.1175/1520-0469(1994)051<2434:TAOFSC>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PC037 UT WOS:A1994PC03700007 ER PT J AU HERGENROTHER, PM HAVENS, SJ AF HERGENROTHER, PM HAVENS, SJ TI POLYIMIDES CONTAINING QUINOXALINE AND BENZIMIDAZOLE UNITS SO MACROMOLECULES LA English DT Article ID AROMATIC TETRACARBOXYLIC DIANHYDRIDES; ETHER; CHEMISTRY AB Two new aromatic dianhydrides containing 2,3-quinoxaline and 5,5'-bis(benzimidazole) units were synthesized and used to prepare polyimides. The aromatic nucleophilic substitution reaction of either N-phenyl-4-fluorophthalimide or N-phenyl-4-nitrophthalimide with the disodium salts of 2,3-bis(4-hydroxyphenyl)quinoxaline or 5,5'-bis[2-(4-hydroxyphenyl)benzimidazole], respectively, in DMSO at 80-degrees-C provided the intermediate-4-substituted N-phenylphthalimides. The N-phenylphthalimides were hydrolyzed with aqueous sodium hydroxide and subsequently acidified to yield the bis(1,2-dicarboxylic acid)s. Reaction of these compounds with acetic anhydride provided the dianhydrides. Polyimides prepared from these new dianhydrides with various diamines exhibited relatively high glass transition temperatures and good thermal stability. Some of the polyimides formed tough, creasible films with good mechanical properties. Several of the polyimides containing the 5,5'-bis(benzimidazole) group were soluble in DMAc and NMP. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP HERGENROTHER, PM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 31 TC 65 Z9 67 U1 1 U2 9 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD AUG 15 PY 1994 VL 27 IS 17 BP 4659 EP 4664 DI 10.1021/ma00095a004 PG 6 WC Polymer Science SC Polymer Science GA PC276 UT WOS:A1994PC27600004 ER PT J AU KULIG, JJ BRITTAIN, WJ GILMOUR, S PERRY, JW AF KULIG, JJ BRITTAIN, WJ GILMOUR, S PERRY, JW TI SYNTHESIS OF NONLINEAR-OPTICAL POLYCARBONATES VIA THE RING-OPENING POLYMERIZATION OF MACROCYCLIC PREPOLYMERS SO MACROMOLECULES LA English DT Article ID 2ND-HARMONIC GENERATION; POLYMERS; CARBONATES; FILMS C1 UNIV AKRON, DEPT POLYMER SCI, AKRON, OH 44325 USA. JET PROP LAB, PASADENA, CA 91109 USA. NR 16 TC 4 Z9 4 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD AUG 15 PY 1994 VL 27 IS 17 BP 4838 EP 4839 DI 10.1021/ma00095a028 PG 2 WC Polymer Science SC Polymer Science GA PC276 UT WOS:A1994PC27600028 ER PT J AU HYUNG, S ALLER, LH FEIBELMAN, WA AF HYUNG, S ALLER, LH FEIBELMAN, WA TI THE SPECTRUM OF THE PLANETARY-NEBULA NGC-6572 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE ISM, ABUNDANCES; PLANETARY NEBULAE, GENERAL; PLANETARY NEBULAE, INDIVIDUAL, NGC-6572; ULTRAVIOLET, ISM ID EMISSION-LINES; COEFFICIENTS; ABUNDANCES; EVOLUTION AB A detailed, high-spectral-resolution study of the spectrum of the planetary nebula NGC 6572 is made for the optical region 365 to 1005 nm, using the Hamilton echelle spectrograph of Lick Observatory, and for the ultraviolet (UV) spectral region 125 to 3 20 nm with the high-dispersion mode of the International Ultraviolet Explorer (IUE) satellite. NGC 6572 is a rather young planetary nebula, with a high surface brightness and a seemingly relatively regular spatial structure. This nebula and especially its central star are also variable. The rich spectrum in both the optical and UV regions offers outstanding opportunities for diagnostic studies, abundance determinations, and even checking atomic processes. The prominent line spectrum of permitted lines of C II, N II, 0 II etc. may arise primarily from recombination. A density-contrast model is constructed to obtain chemical abundances by two methods and to predict isophotal contours. The metal/hydrogen ratio appears to be smaller than in the Sun. We suggest that NGC 6572 originated from a star of about one solar mass, and that the core may have a mass of about 0.57 M.. The expansion age of the nebula appears to be about 2600 yr. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HYUNG, S (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. NR 36 TC 50 Z9 50 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 AUG 15 PY 1994 VL 269 IS 4 BP 975 EP 997 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC695 UT WOS:A1994PC69500018 ER PT J AU ZDZIARSKI, AA FABIAN, AC NANDRA, K CELOTTI, A REES, MJ DONE, C COPPI, PS MADEJSKI, GM AF ZDZIARSKI, AA FABIAN, AC NANDRA, K CELOTTI, A REES, MJ DONE, C COPPI, PS MADEJSKI, GM TI PHYSICAL PROCESSES IN THE X-RAY GAMMA-RAY SOURCE OF IC-4329A SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Letter DE GALAXIES, INDIVIDUAL, IC-4329A; GALAXIES, SEYFERT; DIFFUSE RADIATION; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; RELATIVISTIC THERMAL PLASMAS; COLD MATTER; COMPTON-SCATTERING; ACCRETION DISKS; PAIR PRODUCTION; GALAXIES; SPECTRA; RADIATION; REFLECTION AB Theoretical implications of the recent simultaneous ROSAT/OSSE observation of the Seyfert 1 IC 4329A are discussed. We find that either thermal or non-thermal Comptonization models can fit the data. Thermal models require optically thin plasma and mildly relativistic electrons. Non-thermal models require most of the injected power to be at low values of the electron Lorentz factor. Both models predict a spectral cut-off at energies below approximately 1 MeV, which agrees with broad-band data including non-simultaneous Ginga spectra that match the ROSAT 2-keV flux. Also, Compton reflection corresponding to cold matter covering a solid angle of 2pi is required, and partial covering is ruled out. Since the spectrum of IC 4329A is typical of Seyfert 1 s, their contribution to the cosmic hard X-ray background can be estimated: without cosmological evolution, it is 30 per cent at 3 keV. As the peak of the nuF(nu) spectrum of IC 4329A is much broader than that of the hard X-ray background, however, Seyfert Is cannot account for the X-ray background spectrum without spectral evolution. C1 UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. UNIV LEICESTER, DEPT PHYS, LEICESTER LE1 7RH, ENGLAND. UNIV CHICAGO, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP ZDZIARSKI, AA (reprint author), NICHOLAS COPERNICUS ASTRON CTR, BARTYCKA 18, PL-00716 WARSAW, POLAND. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 38 TC 71 Z9 71 U1 0 U2 0 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 15 PY 1994 VL 269 IS 4 BP L55 EP L60 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PC695 UT WOS:A1994PC69500003 ER PT J AU LAMOURI, A MULLER, W KRAINSKY, IL AF LAMOURI, A MULLER, W KRAINSKY, IL TI GEOMETRY AND UNOCCUPIED ELECTRONIC STATES OF BA AND BAO ON W(001) SO PHYSICAL REVIEW B LA English DT Article ID RESOLVED INVERSE PHOTOEMISSION; SCATTERED-WAVE THEORY; IMPREGNATED CATHODES; SURFACE; TUNGSTEN; OVERLAYERS; SYSTEM; W(100); FILMS AB A study aimed at understanding the geometrical and electronic properties of barium and oxygen coadsorbed on the tungsten (001) surface has been carried out by means of work-function measurements (Delta phi), Auger-electron spectroscopy, low-energy electron diffraction, inverse photoelectron spectroscopy, and relativistic-electronic-structure calculations. A report of the experimental measurements and a comparison with theoretical results from embedded-cluster-model calculations are presented. Our experimental studies show that the work function of the W(001) surface (phi=4.63 eV) is lowered to approximately 2.3-2.4 eV by coadsorption of 1 ML of Ba and O regardless of the order of deposition of these two species. The technique of IFS in the isochromat mode was used to determine the unoccupied electronic-energy band structure for ordered c(2X2) Ba and O layers on W(001). Several spectral features are observed above the Fermi level (E(F)), which we assign to transitions into Ba and W d states. The measured two-dimensional electronic band structure is independent of the order of Ba and O deposition. Using embedded-cluster-model calculations, we investigated two possible adsorption configurations of an ordered c(2X2) adlayer of Ba and O on W(001): ''tilted,'' where Ba and O are placed on alternate fourfold-hollow sites, and ''upright,'' where the adsorbed atoms lay above the same site with Ba outermost. The calculated densities of states for the tilted geometry show distinct peaks above E(F) Originating from Ba and W d orbitals and are in good agreement with the experimental results. C1 ANALATOM INC,WESTLAKE,OH 44145. RP LAMOURI, A (reprint author), NASA,LEWIS RES CTR,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 37 TC 17 Z9 17 U1 0 U2 4 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD AUG 15 PY 1994 VL 50 IS 7 BP 4764 EP 4770 DI 10.1103/PhysRevB.50.4764 PG 7 WC Physics, Condensed Matter SC Physics GA PD753 UT WOS:A1994PD75300062 ER PT J AU ECHTERNACH, PM GERSHENSON, ME BOZLER, HM BOGDANOV, AL NILSSON, B AF ECHTERNACH, PM GERSHENSON, ME BOZLER, HM BOGDANOV, AL NILSSON, B TI TEMPERATURE-DEPENDENCE OF THE RESISTANCE OF ONE-DIMENSIONAL METAL-FILMS WITH DOMINANT NYQUIST PHASE BREAKING SO PHYSICAL REVIEW B LA English DT Note ID ELECTRON-ELECTRON-SCATTERING; WIRES; LOCALIZATION; TIME AB We report the results of a comprehensive study of the temperature dependences of the resistance of one-dimensional narrow gold films with respect to the effects of weak localization (WL) and electron-electron interaction (EEI) in a wide temperature range. The electron wave-function coherence for such samples is limited by electron-electron collisions with small energy transfer (the Nyquist phase-breaking mechanism). It is shown that the temperature dependence of the WL contribution to the resistance, obtained for such a case, is in excellent agreement with the theory by Altshuler, Aronov, and Khmelnitskii. The experimental dependences DELTAR (T) for one-dimensional samples are described quantitatively by the sum of the WL contribution, the contribution of the singlet part of the diffusion channel of EEI, and the contribution of the quantum interference between electron-phonon and electron-impurity scattering. C1 JET PROP LAB,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,SWEDISH NANOMETER LAB,S-41296 GOTHENBURG,SWEDEN. RP ECHTERNACH, PM (reprint author), UNIV SO CALIF,DEPT PHYS,LOS ANGELES,CA 90089, USA. NR 15 TC 6 Z9 6 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD AUG 15 PY 1994 VL 50 IS 8 BP 5748 EP 5751 DI 10.1103/PhysRevB.50.5748 PG 4 WC Physics, Condensed Matter SC Physics GA PG283 UT WOS:A1994PG28300091 ER PT J AU SHI, X SCHRAMM, DN DEARBORN, DSP AF SHI, X SCHRAMM, DN DEARBORN, DSP TI ON SOLAR MODEL SOLUTIONS TO THE SOLAR-NEUTRINO PROBLEM SO PHYSICAL REVIEW D LA English DT Article ID CAPTURE RATE; SUN; HELIOSEISMOLOGY AB Without assuming any solar neutrino spectra but merely assuming pure nu(e) emissions from the Sun, neutrinos seen by the Kamiokande experiment should produce at least 2.6 +/- 0.45 SNU in the lower threshold Homestake experiment. This rate is compared with the total event rate of 2.55 +/- 0.25 SNU observed by the Homestake experiment which solar models tell us should measure not only B-8 neutrinos seen by the Kamiokande but also uncertainty-free pep neutrinos (which contribute 0.2 SNU) as well as Be-7 neutrinos whose energies are below the Kamiokande threshold. This comparison may imply that Be-7 neutrinos are more severely suppressed than the B-8 neutrinos with respect to the predictions of standard solar models, which cannot be explained by any known astrophysics solution. (In particular, this argument is independent of uncertainties in solar nuclear reaction rates.) It is also noted that the lower limit that the Kamiokande observations set on the B-8 neutrino flux restricts variations of standard solar models to require minimal rates of 3.6 SNU for the Homestake experiment and 114 SNU for GALLEX and SAGE to achieve consistency (and still fit helioseismic data). Therefore, variations of standard solar models as solutions to the solar neutrino problem are inconsistent with the Homestake experiment and only marginally allowed by the gallium experiments. If the gallium experiments eventually confirm a flux significantly below 114 SNU, it would seem to imply new neutrino physics. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. RP SHI, X (reprint author), UNIV CHICAGO,CHICAGO,IL 60637, USA. NR 39 TC 47 Z9 47 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD AUG 15 PY 1994 VL 50 IS 4 BP 2414 EP 2420 DI 10.1103/PhysRevD.50.2414 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PC891 UT WOS:A1994PC89100011 ER PT J AU BORRILL, J COPELAND, EJ LIDDLE, AR STEBBINS, A VEERARAGHAVAN, S AF BORRILL, J COPELAND, EJ LIDDLE, AR STEBBINS, A VEERARAGHAVAN, S TI TEXTURE-INDUCED MICROWAVE BACKGROUND ANISOTROPIES SO PHYSICAL REVIEW D LA English DT Article ID COLD DARK-MATTER; LARGE-SCALE STRUCTURE; GLOBAL TEXTURE; COSMIC STRUCTURE; DOMAIN-WALLS; EVOLUTION; ORIGIN; COSMOLOGY; STRINGS AB We use numerical simulations to calculate the cosmic microwave background anisotropy induced by the evolution of a global texture field, with special emphasis on individual textures. Both spherically symmetric and general configurations are analyzed, and in the latter case we consider field configurations which exhibit unwinding events and also ones which do not. We compare the results given by evolving the field numerically under both the expanded core (XCORE) and nonlinear sigma model (NLSM) approximations with the analytic predictions of the NLSM exact solution for a spherically symmetric self-similar (SSSS) unwinding. We find that the random unwinding configuration spots' typical peak height is 60-75% and angular size typically only 10% of those of the SSSS unwinding, and that random configurations without an unwinding event nonetheless may generate indistinguishable hot and cold spots. A brief comparison is made with other work. C1 UNIV SUSSEX,SCH MATH & PHYS SCI,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. NR 31 TC 17 Z9 17 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD AUG 15 PY 1994 VL 50 IS 4 BP 2469 EP 2478 DI 10.1103/PhysRevD.50.2469 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PC891 UT WOS:A1994PC89100017 ER PT J AU KOLB, EW VADAS, SL AF KOLB, EW VADAS, SL TI RELATING SPECTRAL INDEXES TO TENSOR AND SCALAR AMPLITUDES IN INFLATION SO PHYSICAL REVIEW D LA English DT Article ID MICROWAVE BACKGROUND ANISOTROPY; GRAVITATIONAL-WAVES; EXTENDED INFLATION; PERTURBATIONS; COBE AB Within an expansion in slow-roll inflation parameters, we derive the complete second-order expressions relating the ratio of tensor to scalar density perturbations and the spectral index of the scalar spectrum. We find that ''corrections'' to previously derived formulas can dominate if the tensor to scalar ratio is small. For instance, if VV''/(V')2 not-equal 1 or if [m(Pl)2/(4pi)]\V'''/V'\ greater than or similar to 1, where V(phi) is the inflaton potential and m(Pl) is the Planck mass, then the previously used simple relations between the indices and the tensor to scalar ratio fails. This failure occurs in particular for natural inflation, Coleman-Weinberg inflation, and ''chaotic'' inflation. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. RP KOLB, EW (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. NR 28 TC 32 Z9 32 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD AUG 15 PY 1994 VL 50 IS 4 BP 2479 EP 2487 DI 10.1103/PhysRevD.50.2479 PG 9 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PC891 UT WOS:A1994PC89100018 ER PT J AU RAO, KBS SCHUSTER, H HALFORD, GR AF RAO, KBS SCHUSTER, H HALFORD, GR TI ON MASSIVE CARBIDE PRECIPITATION DURING HIGH-TEMPERATURE LOW-CYCLE FATIGUE IN ALLOY 800H SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 FORSCHUNGSZENTRUM JULICH, INST REACTOR MAT, W-5170 JULICH 1, GERMANY. RP RAO, KBS (reprint author), NASA, LEWIS RES CTR, MAIL STOP 49-7, 21000 BROOK PK RD, CLEVELAND, OH 44135 USA. NR 16 TC 10 Z9 10 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD AUG 15 PY 1994 VL 31 IS 4 BP 381 EP 386 DI 10.1016/0956-716X(94)90004-3 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA NQ042 UT WOS:A1994NQ04200004 ER PT J AU KITANO, K POLLOCK, TM NOEBE, RD AF KITANO, K POLLOCK, TM NOEBE, RD TI THE EFFECT OF IMPURITY CONTENT ON THERMALLY ACTIVATED DEFORMATION IN NIAL SINGLE-CRYSTALS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID TEMPERATURE TENSILE DUCTILITY C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP KITANO, K (reprint author), CARNEGIE MELLON UNIV,DEPT MAT SCI P ENGN,PITTSBURGH,PA 15212, USA. NR 19 TC 15 Z9 15 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD AUG 15 PY 1994 VL 31 IS 4 BP 397 EP 402 DI 10.1016/0956-716X(94)90007-8 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA NQ042 UT WOS:A1994NQ04200007 ER EF