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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Electrical structure in a region of the Transverse Ranges, southern California

Magnetotelluric sounding at a site in the Transverse Ranges province in southern California indicates a low-resistivity region in the lower crust and possibly also the upper mantle. A two-dimensional model fit to the data indicates that the resistivity of this region is between 1 and 10 ohm-meters. The depth to the top surface of this zone is between 15 and 20 km. The lateral extent of this feature, which strikes N65 deg W, appears to be confined to the Transverse Ranges province. The petrological characteristics of this region cannot be deduced unambiguously from the magnetotelluric sounding alone.

Reddy, I. K.↗
NASA NTRS1977

Evaluation of spectral channels and wavelength regions for separability of agricultural cover types

The spectral channels were evaluated as well as wavelength regions; visible, near infrared, middle infrared and thermal infrared were evaluated with respect to their estimated probability of correct classification (P sub c) in discriminating agricultural cover types. Multispectral scanner data in twelve spectral channels in the wavelength range of 0.4 to 11.7 micrometers acquired in the middle of July for three flightlines were analyzed by applying automatic pattern recognition techniques. The same analysis was performed for the data acquired in the middle of August, over the same three flightlines, to investigate the effect of time on the results. The effect of deletion of each spectral channel as well as each wavelength region on P sub c was given. Values of P sub c for all possible combinations of wavelength regions in the subsets of one to twelve spectral channels were also given. The overall values of P sub c were found to be greater for the data of the middle of August than the data of the middle of July.

Kumar, R.↗
NASA NTRS1977

Benefit-cost evaluation of an intra-regional air service in the Bay area

Utilization of an iterative statistical model is presented to evaluate combinations of commuter airport sites and surface transportation facilities in confunction with service by a given commuter aircraft type in light of Bay Area regional growth alternatives and peak and off-peak regional travel patterns. The model evaluates such transportation options with respect to criteria of airline profitability, public acceptance, and public and private nonuser costs. It incorporates information modal split, peak and off-peak use of the air commuter fleet, terminal and airport cost, development costs and uses of land in proximity to the airport sites, regional population shifts, and induced zonal shifts in travel demand. The model is multimodal in its analytical capability, and performs exhaustive sensitivity analysis.

Haefner, L. E.↗
NASA NTRS1978

Regional energetic coupling of man and his environment: Data requirements

An energy analysis methodology was developed to serve as a rational basis for evaluating alternative regional management/use schemes. Human and natural systems are coupled and can be interpreted, using a common base of energy-flow analysis to evaluate past, present, and future states of regional integrated systems in the coastal zone and to provide the capability for rational selection of alternative patterns of resource use. Energy flows (or flows of dollars or materials converted to energy equivalents) are believed to be the basic factor in the organizations of all types of systems. An analysis example is provided of an estuarine subsystem of the Chesapeake Bay, and tabular listings of regional data needs are given. Current remote sensing capabilities were used to provide some of the necessary information.

Mihursky, J. A.↗
NASA NTRS1977

A model of F2 peak electron densities in the main trough region of the ionosphere

An empirical model of the peak electron densities in the region of the northerly main trough in the ionospheric F region is presented. The model was derived from measurements made by the satellites Alouette I and II and is in the form of a multiplicative modification factor to the CCIR peak electron density model. The model is a computer program which, when provided with the location, universal time, day number, sunspot number, and Kp index, provides the modification factor, the CCIR model prediction of Nm F2, and the new prediction including the effect of the trough. The model is expected to be of considerable use for propagation calculations in the affected region.

Halcrow, B. W.↗
NASA NTRS1977

A high-resolution far-infrared survey of the W31 region

A 1-m balloon-borne telescope was used to conduct a far-infrared survey of the W31 region at an effective wavelength of 69 microns with a resolution of 1 arcmin. Within this region seven far-infrared sources were observed. Five of these sources were associated with thermal radio emission. For each of these sources the infrared luminosity is much greater than the Ly-alpha luminosity, a situation requiring either dust absorption of Lyman-continuum photons or a large nonionizing stellar luminosity. Two faint infrared sources had no radio counterparts. Far-infrared radiation was not detected from two known radio sources and from one midinfrared source in this region.

Wright, E. L.↗
NASA NTRS1977

Evaluation of spectral channels and wavelength regions for separability of agricultural cover types

The purpose of this study was to evaluate the spectral channel as well as wavelength regions - visible, near infrared, middle infrared and thermal infrared - with respect to their estimated probability of correct classification (P-c) in discriminating agricultural cover types. Multispectral scanner data in twelve spectral channels in the wavelength range of 0.4 to 11.7 micron acquired in the middle of July for three flightlines were analysed by applying automatic pattern recognition techniques. The same analysis was performed for the data acquired in the middle of August, over the same three flightlines, to investigate the effect of time on the results. The effect of deletion of each spectral channel as well as each wavelength region on P-c is given. Values of P-c for all possible combinations of wavelength regions in the subsets of one to twelve spectral channels are also given. The overall values of P-c were found to be greater for the data of the middle of August than the data of the middle of July.

Kumar, R.↗
NASA NTRS1977

Early evolution of an X-ray emitting solar active region

The birth and early evolution of a solar active region has been investigated using X-ray observations from the mapping X-ray heliometer on board the OSO-8 spacecraft. X-ray emission is observed within three hours of the first detection of H-alpha plage. At that time, a plasma temperature of four million K in a region having a density on the order of 10 to the 10th power per cu cm is inferred. During the fifty hours following birth almost continuous flares or flare-like X-ray bursts are superimposed on a monotonically increasing base level of X-ray emission produced by the plasma. If the X-rays are assumed to result from heating due to dissipation of current systems or magnetic field reconnection, it may be concluded that flare-like X-ray emission soon after active region birth implies that the magnetic field probably emerges in a stressed or complex configuration.

Wolfson, C. J.↗
NASA NTRS1977

The gross energy balance of solar active regions

Parker's (1974) model in which sunspots denote regions of increased heat transport from the convection zone is briefly described. The amount of excess mechanically transported power supposed to be delivered to the atmosphere is estimated for a typical active region, and the total radiative power output of the active-region atmosphere is computed. It is found that only a very small fraction (about 0.001) of the sunspot 'missing flux' can be accounted for by radiative emission from the atmosphere above a spot group in the manner suggested by Parker. The power-loss mechanism associated with mass loss to the solar wind is briefly considered and shown not to be sufficient to account for the sunspot missing flux.

Evans, K. D.↗
NASA NTRS1978

Two-micron line emission from the H II region G 333.6-0.2

Spectrophotometry of the H II region G 333.6-0.2 with a resolution of approximately 100 shows strong emission lines of hydrogen and helium superimposed on a continuum. Spatial variations in the equivalent widths of the lines suggest the presence of very hot (at least 600 K) dust grains within the region. The shape of this very powerful H II region indicates that its dense ionized core is being continuously replenished from a reservoir of neutral gas.

Wynn-Williams, C. G.↗
NASA NTRS1978

Far-infrared observations of Large Magellanic Cloud H II regions

Far-infrared emission has been measured from four Large Magellanic Cloud H II regions: the 30 Doradus nebula, MC75, MC76 and MC77. The far-infrared radiation is thermal emission from dust heated by starlight. The results show that the LMC H II regions, like H II regions in the Galaxy, have far-infrared luminosities comparable to the total luminosity of their exciting stars.

Werner, M. W.↗
NASA NTRS1978

Electron temperatures in the F region of the ionosphere - Theory and observations

The theory and observations relating to electron temperatures in the F region of the ionosphere are reviewed. The review is divided into three basic parts. In the first part the theory concerning electron heating, cooling, and energy transport processes is reviewed, and all the relevant expressions are updated. In the second part the behavior of F region electron temperatures, as measured by satellites, rockets, and incoherent scatter radars, is discussed. This portion covers electron temperature variations with altitude, latitude, local time, season, geomagnetic activity, and solar cycle. The third part is primarily devoted to a discussion of the various attempts to compare measured and calculated F region electron temperatures.

Schunk, R. W.↗
NASA NTRS1978

EUV spectra from Skylab /1175-1940 A/ - Mass motions in the transition zone in regions of solar activity

The profiles of spectral lines in the 1100-2000-A range emitted by transition-zone ions in regions of solar activity are discussed. The data were recorded by the NRL spectrograph on Skylab. At the spatial resolution of the Skylab spectrograph (2 x 60 arcsec), it is shown that the line profiles result from the superposed emission of a number of physically distinct regions at different electron densities and with different mass motions. Although high densities are found for some surgelike phenomena at transition-zone temperatures, the densities can also be comparable to normal active-region densities. Line profiles, as well as spectral line intensities, must be considered if meaningful theoretical models of dynamic activity in the transition zone are to be constructed.

Doschek, G. A.↗
NASA NTRS1978

Ion convection and the formation of the mid-latitude F region ionization trough

Total ion concentration and ion drift velocity data from Atmospheric Explorer C are used to examine the convective flow of plasma in the vicinity of the midlatitude F region ionization trough. It is found that the low-latitude portion of the premidnight trough is a region of slow eastward plasma drift while the poleward portion is characterized by generally westward flow. The reversal from eastward to westward flow is described. It is proposed that the plasma flux tubes within the premidnight trough have corotated eastward into the evening local time sector from dusk before stagnating and flowing westward at higher latitudes in the nighttime sector. The role of F region recombination in trough formation is considered.

Spiro, R. W.↗
NASA NTRS1977

Separability of agricultural cover types in spectral channels and wavelength regions

Spectral channels and wavelength regions (visible, near infrared, middle infrared and thermal infrared) were evaluated with respect to their estimated probability of correct classification (Pc) in discriminating agricultural cover types. Multispectral scanner data in twelve spectral channels in the wavelength range of 0.4 to 11.7 microns acquired in the middle of July for three flightlines, were analyzed by applying automatic pattern recognition techniques. The same analysis was performed for the data acquired in the middle of August, 1971, over the same three flightlines, to investigate the effect of time on the results. The effect of deletion of each spectral channel as well as each wavelength region on Pc is given. Values of Pc for all possible combinations of wavelength regions in the subsets of one to twelve spectral channels are also given. The overall values of Pc were found to be greater for the data of the middle of August than the data of the middle of July.

Kumar, R.↗
NASA NTRS1978

Regional program for acquisition of medical experiments

A U.S. company was contracted to cover different regions of the country. A moderately detailed description of the highlights of the company activities along with some conclusions and recommendations are reported. In summary, the regional program effectively: (1) informed segments of the medical community of research opportunities; (2) validated formats for regional workshops; (3) assisted potential investigators with follow-up consultations and proposal preparations; and (4) identified a latent intersect requiring continual dialog at the scientist/engineer interface for successful cultivation and integration.

Vannordstrand, P. C.↗
NASA NTRS1979

Full-coverage film cooling: 3-dimensional measurements of turbulence structure and prediction of recovery region hydrodynamics

Hydrodynamic measurements were made with a triaxial hot-wire in the full-coverage region and the recovery region following an array of injection holes inclined downstream, at 30 degrees to the surface. The data were taken under isothermal conditions at ambient temperature and pressure for two blowing ratios: M = 0.9 and M = 0.4. Profiles of the three main velocity components and the six Reynolds stresses were obtained at several spanwise positions at each of the five locations down the test plate. A one-equation model of turbulence (using turbulent kinetic energy with an algebraic mixing length) was used in a two-dimensional computer program to predict the mean velocity and turbulent kinetic energy profiles in the recovery region. A new real-time hotwire scheme was developed to make measurements in the three-dimensional turbulent boundary layer over the full-coverage surface.

Yavuzkurt, S.↗