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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Operational Characteristics of a Low-Energy FARAD Thruster

Data from a 100 J per pulse electrodeless accelerator employing pulsed RF-preionization are presented to gain insight into the accelerator's operating characteristics. The data suggest that the propellant distribution is highly unoptimized, with most of the gas inaccessible to the discharge and the remainder mostly concentrated at the inner radius of the coil. The pulsed RF-preionization discharge produces a visible plasma, but like the gas distribution it mostly appears concentrated at the inner radius of the thruster. Magnetic field probes in the discharge point to a current sheet that is not magnetically impermeable. These data also exhibit signs of nonrepeatability, and time-integrated discharge photography shows signs of spatial nonuniformity in both the radial and azimuthal directions. Terminal voltage measurements on the two capacitor banks of the thruster do not exhibit the asymmetric nature (in time) typically associated with an efficient pulsed plasma accelerator. Based on the experimental evidence, the poor performance of the thruster is thought to be due to insufficient preionization, which at these low discharge energy levels severely limits the ability of the main current pulse to couple with and effectively accelerate the propellant.

Polzin, Kurt A.↗
NASA NTRS1984

The Use of Available Potential Energy to Evaluate Two GLAS FGGE Data Sets

Meteorological data derived from satellites provided an essential component of the FGGE data sets, especially in data sparse regions of the globe. The impact of satellite derived observations on objective analyses and numerical model predictions are investigated. The FGGE data sets and resulting numerical forecasts and the ability to define the available potential energy of the atmosphere, and its relationship to synoptic scale features such as extratropical cyclones are studied.

Horn, L. H.↗
NASA NTRS1982

Comparison of Venusian lightning observations

Spacecraft observations of Venusian lightning are reviewed to determine the energy dissipation rate. Optical sensors provide data on the total energy dissipated per flash, so long as the contributions of atomic oxygen and ionized carbon are accounted for. Radio probes yield information on the total lightning occurrences. Venera 9-12 radio surveys are reviewed, and event rates of 20-30/sec for Venera 11 are mentioned. Venera 9 observed a sole, 70 sec event period on the Venusian nightside. Comparisons are made between the recorded electromagnetic energy levels and terrestrial lightning data. The nightside occurrence rate is calculated to be 0.08 strokes/sq km per year, while the dayside exhibits 85 flashes/sq km per sec. Energy dissipation rates ranging from 0.0012-0.25 W/sq m are calculated for various flash durations. It is suggested that the lightning occurs in the clouds as part of an organized meteorological system.

Borucki, W. J.↗
NASA NTRS1990

Imaging and two-dimensional spectra of the IR-bright galaxy NGC 2146 - A recent low-energy merger?

New data are presented on the IR-luminous galaxy NGC 2146 from several sources: direct imaging in B, R, and H-alpha; IR imaging in the J, H, and K bands; long-slit spectroscopy at optical and IR wavelengths; and scanning etalon observations in H-alpha. The results allow measurement of the interstellar extinction in the dust lane, and estimation of the true luminosity of the galaxy and nuclear regions. The spectra indicate that there is no active nucleus, and measure the changing ratio of forbidden to permitted lines across the galaxy. IR images and colors indicate the existence of a significant population of hot young stars in the central regions of the system. The H-alpha velocity maps show the full radial-velocity pattern, and suggest that the system consists of a disturbed disk and a merging or interacting arm which connects to the inner dust and radio structures. Outer H-alpha and H I structures appear to be the earlier remnants of this spiraling merger.

Hutchings, J. B.↗
NASA NTRS1992

The Yohkoh mission for high-energy solar physics

Data on solar flare mechanisms and the sun's corona will be generated by Japan's Yohkoh satellite's X-ray imaging sensors and X-ray and gamma-ray spectrometers. It is noted that the X-ray corona above active regions expands, in some cases almost continually, in contradiction of the widely accepted model of magnetohydrostatic equilibrium in such regions. Flaring X-ray bright points have been discovered to often involve ejecta into an adjacent, much larger and fainter magnetic loop, which brightens along its length at speeds up to 1000 km/sec.

Acton, L.↗
NASA NTRS1988

The use of available potential energy to evaluate the impact of satellite data on numerical model analysis during FGGE

To evaluate the effect of the FGGE satellite observing system, the following two data sets were compared by examining the available potential energy (APE) and extratropical cyclone activity within the entire global domain during the first Special Observing Period: (1) the complete FGGE IIIb set, which incorporates satellite soundings, and (2) a NOSAT set which incorporates only conventional data. The time series of the daily total APEs indicate that NOSAT values are larger than the FGGE values, although in the Northern Hemisphere the differences are negligible. Analyses of cyclone scale features revealed only minor differences between the Northern Hemisphere FGGE and NOSAT analyses. On the other hand, substantial differences were revealed in the two Southern Hemisphere analyses, where the satellite soundings apparently add detail to the FGGE set.

Horn, Lyle H.↗
NASA NTRS2000

Significant Dissipation of Tidal Energy in the Deep Ocean Inferred from Satellite Altimeter Data

How and where the ocean tides dissipate their energy are longstanding questions that have consequences ranging from the history of the Moon to the mixing of the oceans. Historically, the principal sink of tidal energy has been thought to be bottom friction in shallow seas. There has long been suggestive however, that tidal dissipation also occurs in the open ocean through the scattering by ocean-bottom topography of surface tides into internal waves, but estimates of the magnitude of this possible sink have varied widely. Here we use satellite altimeter data from Topex/Poseidon to map empirically the tidal energy dissipation. We show that approximately 10(exp 12) watts-that is, 1 TW, representing 25-30% of the total dissipation-occurs in the deep ocean, generally near areas of rough topography. Of the estimated 2 TW of mixing energy required to maintain the large-scale thermohaline circulation of the ocean, one-half could therefore be provided by the tides, with the other half coming from action on the surface of the ocean.

Egbert, G. D.↗
NASA NTRS1975

Solar heating and cooling: Technical data and systems analysis

The solar energy research is reported including climatic data, architectural data, heating and cooling equipment, thermal loads, and economic data. Lists of data sources presented include: selected data sources for solar energy heating and cooling; bibliography of solar energy, and other energy sources; sources for manufacturing and sales, solar energy collectors; and solar energy heating and cooling projects.

Christensen, D. L.↗
NASA NTRS1993

Classifying multispectral data by neural networks

Several energy functions for synthesizing neural networks are tested on 2-D synthetic data and on Landsat-4 Thematic Mapper data. These new energy functions, designed specifically for minimizing misclassification error, in some cases yield significant improvements in classification accuracy over the standard least mean squares energy function. In addition to operating on networks with one output unit per class, a new energy function is tested for binary encoded outputs, which result in smaller network sizes. The Thematic Mapper data (four bands were used) is classified on a single pixel basis, to provide a starting benchmark against which further improvements will be measured. Improvements are underway to make use of both subpixel and superpixel (i.e. contextual or neighborhood) information in tile processing. For single pixel classification, the best neural network result is 78.7 percent, compared with 71.7 percent for a classical nearest neighbor classifier. The 78.7 percent result also improves on several earlier neural network results on this data.

Telfer, Brian A.↗
NASA NTRS1972

Stored energy function of rubberlike materials derived from simple tensile data.

An explicit formulation is developed to obtain the stored energy function, based on the Valanis-Landel separable symmetric stored energy function. This formulation is applicable to any multiaxial stress state, from simple tensile data alone, for those cases in which the stored energy function is a separable function of the stretch ratios. By direct comparison, it is also shown that styrene butadiene rubber, at least over a specific range, follows this postulated separable form.

Peng, T. J.↗
NASA NTRS1999

Multi-Wavelength Superoutburst Observations of T Leonis

We present results of simultaneous superoutburst observations in the X-ray, Extreme Ultraviolet (EUV), optical, and IR bands of the tremendous outburst amplitude dwarf novae T Leonis. Near peak luminosity, a single blackbody represents a good fit to T Leo's observed continuum in the EUV spectral region, yielding a boundary layer temperature of 71,000 to 97,000K. Inclusion of the longer wavelength observations, UV to the IR, indicates that a blackbody fit is inappropriate. A single temperature fit to only the UV and red-ward data for T Leo works well, but yields a much lower temperature, near 28,000K. Using our own observations and previously obtained EUV, UV and optical (super)outburst observations for the dwarf novae U Gem and SS Cyg, the SU UMa star VW Hyi, and the TOADS, TV Crv, BC UMa, and SW UMa, we find that in all cases, high energy observations yield high temperature, small emitting regions, while fits to UV and red-ward data produce cooler temperatures from much larger emitting regions. These results are consistent with the idea that high energy data provide a direct measurement of the boundary layer while the lower energy data measure a much larger, multi-temperature region, likely to be dominated by the outburst heated inner accretion disk. High energy outburst observations show that the boundary layer temperature decreases with decreasing orbital period and UV outburst observations provide evidence for a missing or weak inner disk in the TOADs. We present a simple model of mass accretion onto the white dwarf during (super)outburst which can account for the observed correlation between temperature.

Howell, Steve B.↗
NASA NTRS2006

Hera - The HEASARC's New Data Analysis Service

Hera is the new computer service provided by the HEASARC at the NASA Goddard Space Flight Center that enables qualified student and professional astronomical researchers to immediately begin analyzing scientific data from high-energy astrophysics missions. All the necessary resources needed to do the data analysis are freely provided by Hera, including: * the latest version of the hundreds of scientific analysis programs in the HEASARC's HEASOFT package, as well as most of the programs in the Chandra CIAO package and the XMM-Newton SAS package. * high speed access to the terabytes of data in the HEASARC's high energy astrophysics Browse data archive. * a cluster of fast Linw workstations to run the software * ample local disk space to temporarily store the data and results. Some of the many features and different modes of using Hera are illustrated in this poster presentation.

Pence, William↗
NASA NTRS1986

The magnetosphere of Uranus - Hot plasma and radiation environment

Inferences are drawn on the morphology and composition of the Uranus magnetosphere based on low-energy charged particle data collected by Voyager 2. Proton and electron energies in the magnetosphere attained energies of 4 and 1.2 MeV, respectively, although electron intensities surpassed the proton intensities at most energy levels. Protons dominated in the ion energy regime 0.6-1.0 MeV. The ion and electron spectra were Maxwellian below about 200 keV and had a power law distribution at energies over 590 keV. The power law was reduced by a factor of nearly three inside the orbit of Miranda. The proton population is dense enough to polymerize CO and CH4 ice surfaces within 10,000-100,000 yr. The data indicated that the particles are swept out at least to the orbit of Titania by the satellites. The morphology of the magnetosphere closely resembles that around Jupiter, except that plasma sheet distorsion from particle loading is negligible in regions within 15 Uranus radii.

Krimigis, S. M.↗
NASA NTRS2006

Updated Computational Model of Cosmic Rays Near Earth

An updated computational model of the galactic-cosmic-ray (GCR) environment in the vicinity of the Earth, Earth s Moon, and Mars has been developed, and updated software has been developed to implement the updated model. This model accounts for solar modulation of the cosmic-ray contribution for each element from hydrogen through iron by computationally propagating the local interplanetary spectrum of each element through the heliosphere. The propagation is effected by solving the Fokker-Planck diffusion, convection, energy-loss boundary-value problem. The Advanced Composition Explorer NASA satellite has provided new data on GCR energy spectra. These new data were used to update the original model and greatly improve the accuracy of prediction of interplanetary GCR.

ONeill, Patrick M.↗
NASA NTRS2012

Estimation of the Relationship Between Remotely Sensed Anthropogenic Heat Discharge and Building Energy Use

This paper examined the relationship between remotely sensed anthropogenic heat discharge and energy use from residential and commercial buildings across multiple scales in the city of Indianapolis, Indiana, USA. The anthropogenic heat discharge was estimated with a remote sensing-based surface energy balance model, which was parameterized using land cover, land surface temperature, albedo, and meteorological data. The building energy use was estimated using a GIS-based building energy simulation model in conjunction with Department of Energy/Energy Information Administration survey data, the Assessor's parcel data, GIS floor areas data, and remote sensing-derived building height data. The spatial patterns of anthropogenic heat discharge and energy use from residential and commercial buildings were analyzed and compared. Quantitative relationships were evaluated across multiple scales from pixel aggregation to census block. The results indicate that anthropogenic heat discharge is consistent with building energy use in terms of the spatial pattern, and that building energy use accounts for a significant fraction of anthropogenic heat discharge. The research also implies that the relationship between anthropogenic heat discharge and building energy use is scale-dependent. The simultaneous estimation of anthropogenic heat discharge and building energy use via two independent methods improves the understanding of the surface energy balance in an urban landscape. The anthropogenic heat discharge derived from remote sensing and meteorological data may be able to serve as a spatial distribution proxy for spatially-resolved building energy use, and even for fossil-fuel CO2 emissions if additional factors are considered.

Multi-scale↗