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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Vertical wind velocities from superpressure balloons - A case study using Eole data

A method for determining vertical wind velocities using the pressure- and temperature-change data from superpressure (constant-density) balloons was proposed in an earlier paper (1975). In this paper, we present a case study using actual balloon data to test the method. Data from the Eole balloon experiment were used to estimate the sign of vertical wind velocities, as well as the horizontal velocity field, near 200 mb over Australia. The resulting patterns of vertical velocity compare favorably with satellite pictures and with current models of flow near jet-stream maxima. Additionally, this study provides evidence that areas of vertical motion in the troposphere extend upward into the lower stratosphere without changing sign.

Banta, R. M.↗
NASA NTRS1981

The chemical composition, gravity, and temperature of Sirius

Observational data available for Sirius are of poorer quality than those for Vega, with both the angular diameter and absolute fluxes at different wavelengths being less accurately known. While these data yield an effective temperature of 10,000 + or - 250 K, the 13-color photometry of Johnson and Mitchell (1975) suggests that Sirius is about 450 K hotter than Vega's effective temperature of 9650 + or - 200 K. The c(1) color of the uvby system, the 33-52 and 35-52 colors of the 13-color photometry, and the H-alpha, H-beta and H-gamma line profiles all give log g values of about 4.3, which is in agreement with the value deduced from the mass and the radius, the latter being deduced from the angular diameter and the parallax.

Bell, R. A.↗
NASA NTRS1991

A new method for analyzing IRAS data to determine the dust temperature distribution

In attempting to analyze the four-band IRAS images of interstellar dust emission, it is found that an inversion theorem recently developed by Chen (1990) enables distribution of the dust to be determined as a function of temperature and thus the total dust column density, for each line of sight. The method and its application to a hypothetical IRAS data set created by assuming a power-law dust temperature distribution, which is characteristic of the actual IRAS data for the Monoceros R2 cloud, are reported. To use the method, the wavelength dependence of the dust emissivity is assumed and a simple function is fitted to the four intensity-wavelength data points. The method is shown to be very successful at retrieving the dust temperature distribution in this case and is expected to have wide applicability to astronomical problems of this type.

Xie, Taoling↗
NASA NTRS1992

Results of thermal vacuum tests for the PASP Plus flight panels

The PASP+ experiment is collection of 16 individual cell strings on 12 different photovoltaic modules, representing a wide variety of cell and array technologies, which will be launched from a Pegasus in early 1993. The main objectives of the experiment are to obtain environmental interaction data between the modules and the space plasma; and to obtain radiation damage data on the newer types of cells. The orbit will be about 1050 nautical miles by 190 nautical miles with an inclination of 70 degrees. During late June and early July of this year, we took the PASP+ panels with all 12 modules and the flight controller to Boeing for a series of thermal vacuum tests. The main objectives of these tests were to verify the thermal balance model of the space experiment; to obtain good data for temperature coefficients of the various modules; and to have an 'end-to-end' test of the modules and controller. We will present data on the module temperatures and the measured temperature coefficients. We shall discuss the limitations of the test setup and some of the assumptions that were made. We shall also present some module performance as a function of temperature.

Guidice, Don↗
DOE OSTI2015

Building the Next Generation of Regional Geothermal Potential Maps: Examples from the Great Basin Region, Western USA

Over the past decade research has greatly advanced our understanding of structurally controlled geothermal systems and the potential for “deep stratigraphic reservoirs” in the Great Basin region, western USA. For example, studies have shown that structurally controlled geothermal systems are associated with specific structural settings, such as terminations of major normal faults, accommodation zones, pull-aparts in strike-slip faults, displacement transfer zones, or step-overs in range-front faults. However, we know that not every structure (e.g., termination of a major normal fault or step-over in a range-front fault) hosts an active geothermal system. Recent research has also shown that regional strain rate model as determined from GPS geodesy, the composition of that strain (extensional versus shear or compressive strain), recency of Quaternary faulting, and slip and dilation tendency of faults correlate positively with the distribution of both high and low-temperature, structurally controlled geothermal systems within the Great Basin. Combining these strain data and fault slip history data sets with existing temperature gradient data, heat flow data, spring temperatures, fluid geothermometry, and geophysical data provides an effective platform for evaluating the geothermal potential of respective structural plays. Recent studies focused on deep stratigraphic reservoirs indicate the best conditions for economically viable development are associated with thick sedimentary basins with low-thermal-conductivity sedimentary cap rocks overlying permeable host rocks (e.g. carbonates) and co-located with areas of high heat flow. Some of the factors that contribute to the potential for deep stratigraphic reservoirs and conventional structurally controlled geothermal systems apply to both types of resources, and in some places the potential for these two types of resources overlap in space, suggesting the potential for hybrid reservoirs (structurally controlled deep stratigraphic reservoirs). Effective and complete evaluation of geothermal potential in the Great Basin should include parameters that cover both types of resources. In this study, two areas with a combined area of 26,000 km 2 were evaluated for geothermal resource potential, equating to <4% of the total 680,000 km 2 size of the Great Basin region. Within these two study areas, 73 potential structural targets and 8 potential deep sedimentary target areas were identified. Four of the 73 potential structural target areas are associated with known thermal anomalies. All 73 structural target areas were ranked according to multiple data sets.

15 GEOTHERMAL ENERGY↗
NASA NTRS1983

Planetary atmospheres

During the period from 1979 to 1982, Pioneer and Voyager missions to Venus, Jupiter, and Saturn combined with ongoing analysis and data collection from the Viking-Mars mission have contributed greatly to an understanding of planetary atmospheres. Research concerning the atmosphere of Venus is discussed, taking into account the atmospheric composition, the isotopic ratios of noble gases, data concerning temperature and pressure, information regarding various atmospheric layers, atmospheric density data, and models regarding the dynamical properties of Venus' atmosphere. Information concerning the atmosphere of Mars is also examined. Isotopic ratios of carbon and oxygen are considered along with altitude profiles, diurnal heating and cooling, and thermal tides and their relationship to dust storms. Attention is given to the temperature structure of the Jovian atmosphere, the morphology of Jovian cloud features, features in the Saturnian atmosphere, information with respect to the atmosphere of Titan, the rotation rates of Uranus, masses and densities of Uranus and Neptune, and the identification of Pluto as a small icy body.

Beebe, R.↗
NASA NTRS2000

A Method for Assessing the Quality of Model-Based Estimates of Ground Temperature and Atmospheric Moisture Using Satellite Data

A method is developed for validating model-based estimates of atmospheric moisture and ground temperature using satellite data. The approach relates errors in estimates of clear-sky longwave fluxes at the top of the Earth-atmosphere system to errors in geophysical parameters. The fluxes include clear-sky outgoing longwave radiation (CLR) and radiative flux in the window region between 8 and 12 microns (RadWn). The approach capitalizes on the availability of satellite estimates of CLR and RadWn and other auxiliary satellite data, and multiple global four-dimensional data assimilation (4-DDA) products. The basic methodology employs off-line forward radiative transfer calculations to generate synthetic clear-sky longwave fluxes from two different 4-DDA data sets. Simple linear regression is used to relate the clear-sky longwave flux discrepancies to discrepancies in ground temperature ((delta)T(sub g)) and broad-layer integrated atmospheric precipitable water ((delta)pw). The slopes of the regression lines define sensitivity parameters which can be exploited to help interpret mismatches between satellite observations and model-based estimates of clear-sky longwave fluxes. For illustration we analyze the discrepancies in the clear-sky longwave fluxes between an early implementation of the Goddard Earth Observing System Data Assimilation System (GEOS2) and a recent operational version of the European Centre for Medium-Range Weather Forecasts data assimilation system. The analysis of the synthetic clear-sky flux data shows that simple linear regression employing (delta)T(sub g)) and broad layer (delta)pw provides a good approximation to the full radiative transfer calculations, typically explaining more thin 90% of the 6 hourly variance in the flux differences. These simple regression relations can be inverted to "retrieve" the errors in the geophysical parameters, Uncertainties (normalized by standard deviation) in the monthly mean retrieved parameters range from 7% for (delta)T(sub g) to approx. 20% for the lower tropospheric moisture between 500 hPa and surface. The regression relationships developed from the synthetic flux data, together with CLR and RadWn observed with the Clouds and Earth Radiant Energy System instrument, ire used to assess the quality of the GEOS2 T(sub g) and pw. Results showed that the GEOS2 T(sub g) is too cold over land, and pw in upper layers is too high over the tropical oceans and too low in the lower atmosphere.

Wu, Man Li C.↗
NASA NTRS1990

Acquisition and correlation of cryogenic nitrogen mass flow data through a multiple orifice Joule-Thomson device

Liquid nitrogen mass flow rate, pressure drop, and temperature drop data were obtained for a series of multiple orifice Joule-Thomson devices, known as Visco Jets, over a wide range of flow resistance. The test rig used to acquire the data was designed to minimize heat transfer so that fluid expansion through the Visco Jets would be isenthalpic. The data include a range of fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures from 118 to 164 R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to 162 R and flow rate from 0.04 to 4.0 lbm/hr of nitrogen. A flow rate equation supplied by the manufacturer was found to accurately predict single-phase (noncavitating) liquid nitrogen flow through the Visco Jets. For cavitating flow, the manufacturer's equation was found to be inaccurate. Greatly improved results were achieved with a modified version of the single-phase equation. The modification consists of a multiplication factor to the manufacturer's equation equal to one minus the downstream quality on an isenthalpic expansion of the fluid across the Visco Jet. For a range of flow resistances represented by Visco Jet Lohm ratings between 17,600 and 80,000, 100 percent of the single-phase data and 85 percent of the two-phase data fall within + or - 10 percent of predicted values.

Papell, S. Stephen↗
DOE OSTI2016

Planck 2015 results: XXI. The integrated Sachs-Wolfe effect

Here, this paper presents a study of the integrated Sachs-Wolfe (ISW) effect from the Planck 2015 temperature and polarization data release. This secondary cosmic microwave background (CMB) anisotropy caused by the large-scale time-evolving gravitational potential is probed from different perspectives. The CMB is cross-correlated with different large-scale structure (LSS) tracers: radio sources from the NVSS catalogue; galaxies from the optical SDSS and the infrared WISE surveys; and the Planck 2015 convergence lensing map. The joint cross-correlation of the CMB with the tracers yields a detection at 4σ where most of the signal-to-noise is due to the Planck lensing and the NVSS radio catalogue. In fact, the ISW effect is detected from the Planck data only at ≈3σ (through the ISW-lensing bispectrum), which is similar to the detection level achieved by combining the cross-correlation signal coming from all the galaxy catalogues mentioned above. We study the ability of the ISW effect to place constraints on the dark-energy parameters; in particular, we show that Ω Λ is detected at more than 3σ. This cross-correlation analysis is performed only with the Planck temperature data, since the polarization scales available in the 2015 release do not permit significant improvement of the CMB-LSS cross-correlation detectability. Nevertheless, the Planck polarization data are used to study the anomalously large ISW signal previously reported through the aperture photometry on stacked CMB features at the locations of known superclusters and supervoids, which is in conflict with ΛCDM expectations. We find that the current Planck polarization data do not exclude that this signal could be caused by the ISW effect. In addition, the stacking of the Planck lensing map on the locations of superstructures exhibits a positive cross-correlation with these large-scale structures. Finally, we have improved our previous reconstruction of the ISW temperature fluctuations by combining the information encoded in all the previously mentioned LSS tracers. In particular, we construct a map of the ISW secondary anisotropies and the corresponding uncertainties map, obtained from simulations. Lastly, we also explore the reconstruction of the ISW anisotropies caused by the large-scale structure traced by the 2MASS Photometric Redshift Survey (2MPZ) by directly inverting the density field into the gravitational potential field.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1982

Performance characteristics of an electric vehicle lead-acid battery pack at elevated temperatures

Discharge testing data electric car battery pack over initial electrolyte temperature variations between 27 and 55 C are presented. The tests were conducted under laboratory conditions and then compared to detailed electric vehicle simulation models. Battery discharge capacity increased with temperature for constant current discharges, and battery energy capacity increased with temperature for constant power discharges. Dynamometer tests of the electric test vehicle showed an increase in range of 25% for the higher electrolyte temperature.

Chapman, P.↗
DOE OSTI2014

The Atacama Cosmology Telescope: temperature and gravitational lensing power spectrum measurements from three seasons of data

We present the temperature power spectra of the cosmic microwave background (CMB) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. We detect and correct for contamination due to the Galactic cirrus in our equatorial maps. We present the results of a number of tests for possible systematic error and conclude that any effects are not significant compared to the statistical errors we quote. Where they overlap, we cross-correlate the ACT and the South Pole Telescope (SPT) maps and show they are consistent. The measurements of higher-order peaks in the CMB power spectrum provide an additional test of the ΛCDM cosmological model, and help constrain extensions beyond the standard model. The small angular scale power spectrum also provides constraining power on the Sunyaev-Zel'dovich effects and extragalactic foregrounds. We also present a measurement of the CMB gravitational lensing convergence power spectrum at 4.6σ detection significance.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2014

The Atacama Cosmology Telescope: Temperature and Gravitational Lensing Power Spectrum Measurements from Three Seasons of Data

We present the temperature power spectra of the cosmic microwave background (CMB) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. We detect and correct for contamination due to the Galactic cirrus in our equatorial maps. We present the results of a number of tests for possible systematic error and conclude that any effects are not significant compared to the statistical errors we quote. Where they overlap, we cross-correlate the ACT and the South Pole Telescope (SPT) maps and show they are consistent. The measurements of higher-order peaks in the CMB power spectrum provide an additional test of the ΛCDM cosmological model, and help constrain extensions beyond the standard model. The small angular scale power spectrum also provides constraining power on the Sunyaev-Zel'dovich effects and extragalactic foregrounds. We also present a measurement of the CMB gravitational lensing convergence power spectrum at 4.6σ detection significance.

Atacama Cosmology Telescope (ACT)↗
NASA NTRS1982

Determination of the horizontal and vertical distribution of clouds from infrared satellite sounding data

A numerical algorithm, based on a physical inversion of the radiative transfer equation, is developed to retrieve the global distribution of the horizontal cloud cover, the cloud-top pressure levels and their temperature. The algorithm makes use of infrared and microwave temperature sounding data to derive the clear-column vertical temperature profiles and then uses the same infrared sounding data to obtain the corresponding cloud parameters. Experimental verification of this method is carried out using data from the High resolution Infrared Sounder (HIRS) and the Microwave Sounding Unit (MSU) operating on the NOAA weather satellite system.

Chahine, M. T.↗
DOE OSTI2018

The homometallic warwickite V{sub 2}OBO{sub 3}

Highlights: • New mixed valent vanadium borate. • Multiple phase transitions on cooling. • High resolution synchrotron powder X-ray diffraction data. - Abstract: The synthesis, structure and elementary magnetic characterization of the homometallic warwickite V{sub 2}OBO{sub 3} are reported. The material adopts the orthorhombic warwickite structure type at room temperature, space group Pnma (No. 62) with lattice parameters a = 9.2317(1) Å, b = 3.1172(1) Å, and c = 9.5313(1) Å. Temperature-dependent magnetic susceptibility, electrical resistivity, and specific heat measurements show anomalies near 35 K, between 135 K and 150 K, and near 260 K, with the transition at ~ 35 K likely to a ferrimagnetic state. High resolution synchrotron powder X-ray diffraction data at temperatures between 295 K and 90 K display significant peak splitting upon cooling, indicating that at least one crystallographic symmetry change occurs at low temperatures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Valence Band Modification and High Thermoelectric Performance in SnTe Heavily Alloyed with MnTe

Herein we demonstrate a high solubility limit of >9 mol% for MnTe alloying in SnTe. The electrical conductivity of SnTe decreases gradually while the Seebeck coefficient increases remarkably with increasing MnTe content, leading to enhanced power factors. The room-temperature Seebeck coefficients of Mn-doped SnTe are significantly higher than those predicted by theoretical Pisarenko plots for pure SnTe, indicating a modified band structure. The high-temperature Hall data of Sn 1– x Mn x Te show strong temperature dependence, suggestive of a two-valence-band conduction behavior. Moreover, the peak temperature of the Hall plot of Sn 1– x Mn x Te shifts toward lower temperature as MnTe content is increased, which is clear evidence of decreased energy separation (band convergence) between the two valence bands. The first-principles electronic structure calculations based on density functional theory also support this point. The higher doping fraction (>9%) of Mn in comparison with ~3% for Cd and Hg in SnTe gives rise to a much better valence band convergence that is responsible for the observed highest Seebeck coefficient of ~230 μV/K at 900 K. The high doping fraction of Mn in SnTe also creates stronger point defect scattering, which when combined with ubiquitous endotaxial MnTe nanostructures when the solubility of Mn is exceeded scatters a wide spectrum of phonons for a low lattice thermal conductivity of 0.9 W m –1 K –1 at 800 K. The synergistic role that Mn plays in regulating the electron and phonon transport of SnTe yields a high thermoelectric figure of merit of 1.3 at 900 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Auger recombination in long-wave infrared InAs/InAsSb type-II superlattices

The Auger lifetime is a critical intrinsic parameter for infrared photodetectors as it determines the longest potential minority carrier lifetime and consequently the fundamental limitations to their performance. Here, Auger recombination is characterized in a long-wave infrared InAs/InAsSb type-II superlattice. Auger coefficients as small as 7.1×10 –26 cm 6 /s are experimentally measured using carrier lifetime data at temperatures in the range of 20 K–80 K. The data are compared to Auger-1 coefficients predicted using a 14-band K•p electronic structure model and to coefficients calculated for HgCdTe of the same bandgap. In conclusion, the experimental superlattice Auger coefficients are found to be an order-of-magnitude smaller than HgCdTe.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1976

Description and catalog of ionospheric F-region data, Jicamarca Radar Observatory, November 1966 - April 1969

Equatorial ionospheric F-region data reduced from the Jicamarca Radar Observatory (JRO) incoherent scatter observations for particular periods is described. It lists in catalog form the times of the observations made during those periods. These F-region data include the electron concentration and the electron and ion temperatures. The data were inferred from the incoherent scatter observations of JRO.

Clark, W. L.↗
NASA NTRS1996

Assessment of Uncertainty in the Determination of Kinetic Reaction Parameters for Polymeric Materials

The use of thermogravimetric analysis to obtain data describing the thermal response of a polymeric resin with temperature. This data can then be used to obtain activation energy and pre-exponential factor used in an Arrhenius representation of material ablation. The methods which allow to assess the uncertainties associated with the experimental determination of activation energy and pre-exponential factor are employed.

Darby, Stephanie P.↗