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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Conceptual design study of a coal gasification combined-cycle powerplant for industrial cogeneration

A conceptual design study was conducted to assess technical feasibility, environmental characteristics, and economics of coal gasification. The feasibility of a coal gasification combined cycle cogeneration powerplant was examined in response to energy needs and to national policy aimed at decreasing dependence on oil and natural gas. The powerplant provides the steam heating and baseload electrical requirements while serving as a prototype for industrial cogeneration and a modular building block for utility applications. The following topics are discussed: (1) screening of candidate gasification, sulfur removal and power conversion components; (2) definition of a reference system; (3) quantification of plant emissions and waste streams; (4) estimates of capital and operating costs; and (5) a procurement and construction schedule. It is concluded that the proposed powerplant is technically feasible and environmentally superior.

Bloomfield, H. S.↗
NASA NTRS1981

Orbits of nine Uranian rings

Observations of a stellar occultation by Uranus and its nine rings are presented and used to examine the structures and kinematics of the rings. The observations of the occultation of the K giant star KM 12 were obtained in the K band with the 4-m CTIO telescope at a signal-to-noise ratio higher than any previously obtained. Ring occultation profiles reveal the alpha ring to possibly have a double structure and less abrupt boundaries than the gamma ring, which exhibits diffraction fringes, while the eta ring is a broad ring with an unresolved narrow component at its inner edge. The present timing data, as well as previous occultation timings, are fit to a kinematic model in which all nine rings are treated as coplanar eclipses of zero inclination, precessing due to the zonal harmonics of the Uranian gravitational potential to obtain solutions for the ring orbits. Analysis of the residuals from the fitted orbits reveals that the proposed model is a good representation of ring kinematics. The reference system defined by the orbit solutions has also been used to obtain a value of 0.022 + or - 0.003 for the ellipticity of Uranus and a Uranian rotation period of 15.5 h.

Elliot, J. L.↗
NASA NTRS1981

Application of microprocessors in an upper atmosphere instrument package

A servo-driven magnetometer table measuring offset from magnetic north has been developed by NASA to calculate payload azimuth required to point at a celestial target. Used as an aid to the study of gamma-ray phenomena, the high-altitude balloon-borne instrument determines a geocentric reference system, and calculates a set of pointing directions with respect to the system. Principal components include the magnetometer, stepping motor, microcomputer, and gray code shaft encoder. The single-chip microcomputer is used to control the orientation of the system, and consists of a central processing unit, program memory, data memory and input/output ports. Principal advantages include a low power requirement, consuming 6 watts, as compared to 30 watts consumed by the previous system.

Lim, T. S.↗
NASA NTRS1981

Basic research for the Earth dynamics program

The technique of range differencing with Lageos ranges to obtain more accurate estimates of baseline lengths and polar motion variation was studied. Differencing quasi simultaneous range observations eliminate a great deal of orbital biases. Progress is reported on the definition and maintenance of a conventional terrestrial reference system.

Source record↗
NASA NTRS1980

Environmental assessment overview

The assessment program has as its objectives: to identify the environmental issues associated with the SPS Reference System; to prepare a preliminary assessment based on existing data; to suggest mitigating strategies and provide environmental data and guidance to other components of the program as required; and to plan long-range research to reduce the uncertainty in the preliminary assessment. The key environmental issues associated with the satellite power system are discussed and include human health and safety, ecosystems, climate, and interaction with electromagnetic systems.

Valentino, A. R.↗
NASA NTRS1980

Offshore rectenna feasbility

A preliminary study of the feasibility and cost of an offshore rectenna to serve the upper metropolitan east coast was performed. A candidate site at which to build a 5 GW rectenna was selected on the basis of proximity to load centers, avoidance of shipping lanes, sea floor terrain, and relocated conditions. Several types of support structures were selected for study based initially on the reference system rectenna concept of a wire mesh ground screen and dipoles each with its own rectifier and filter circuits. Possible secondary uses of an offshore rectenna were examined and are evaluated.

Freeman, J. W.↗
NASA NTRS1980

Hazards to space workers from ionizing radiation

A compilation of background information and a preliminary assessment of the potential risks to workers from the ionizing radiation encountered in space is provided. The report: (1) summarizes the current knowledge of the space radiation environment to which space workers will be exposed; (2) reviews the biological effects of ionizing radiation considered of major importance to a SPS project; and (3) discusses the health implications of exposure of populations of space workers to the radiations likely to penetrate through the shielding provided by the SPS work stations and habitat shelters of the SPS Reference System.

Lyman, J. T.↗
NASA NTRS1981

Cost and performance projections for SPS photovoltaic blankets

An estimate, based on optimistic projections of current technology, is given for the specific power of photovoltaic blankets which might be achieved if the SPS concept was to be implemented. A simultaneous consideration of cost and technical requirements is used to identify key blanket technologies which must be developed for this reference system. The terrestrial photovoltaic experience coupled with new technology is used to develop cost estimates for the blanket, assuming an annual demand of 5 GW and a manufacturing industry dedicated to blanket production. The results indicate that blanket specific power goals may be exceeded, but there is little prospect that the cost goals can be met. This argues for a reconsideration of the photovoltaic option based on more expensive but higher performance blankets.

Scott-Monck, J. A.↗
NASA NTRS1981

Establishment of terrestrial reference frames by new observational techniques

It is anticipated that terrestrial reference systems for geodynamics studies which include adopted plate motion models will be introduced for the analysis of both LAGEOS satellite and very long baseline interferometry ranging data. One of the possible approaches involves adjustment of ground station coordinates in conjunction with solutions for Universal Time 1 (UT1) and polar motions as functions of time. Another method uses principal value decomposition to reduce the number of degrees of freedom being solved for by three. In a third alternative, the values of UT1 and polar motion derived from the available data by means of the initial set of coordinates are kept fixed, and an appropriate block of data is reanalyzed using the previously determined values of UT1 and polar motion so that a new set of station coordinates can be derived.

Bender, P. L.↗
NASA NTRS1983

Spectral decontamination of a real-time helicopter simulation

Nonlinear mathematical models of a rotor system, referred to as rotating blade-element models, produce steady-state, high-frequency harmonics of significant magnitude. In a discrete simulation model, certain of these harmonics may be incompatible with realistic real-time computational constraints because of their aliasing into the operational low-pass region. However, the energy is an aliased harmonic may be suppressed by increasing the computation rate of an isolated, causal nonlinearity and using an appropriate filter. This decontamination technique is applied to Sikorsky's real-time model of the Black Hawk helicopter, as supplied to NASA for handling-qualities investigations.

Mcfarland, R. E.↗
NASA NTRS1983

Estimating crustal deformations from a combination of baseline measurements and geophysical models

Three possible estimation algorithms are presented for the monitoring of crustal deformations from a combination of repeated baseline measurements and prior deformation information. Attention is given to best linear minimum bias estimation, best linear estimation, and Bayesian estimation. The application of the deformation estimators to the maintenance of a conventional terrestrial reference system is considered. It is shown that if no prior deformation model is available, the free adjustment is the preferred algorithm. In the presence of prior information, however, it is better to use a somewhat incorrect model than to ignore it altogether. The best estimation model of the ones tested is the best linear estimation.

Bock, Y.↗
NASA NTRS1984

Theoretical study of miscibility and glass-forming trends in mixtures of polystyrene spheres

A theoretical study of glass-forming trends and miscibility in mixtures of polystyrene spheres (polyballs) of different diameters, suspended in an aqueous solution, is presented. The polyballs are assumed to be charged and to interact via a Debye-Hueckel screened Coulomb potential. The Helmholtz free energy is calculated from a variational principle based on the Gibbs-Bogoliubov inequality, in which a mixture of hard spheres of different diameters is chosen as the reference system. It is found that when the charges of the two types of polyballs are sufficiently different, the variationally determined ratio of hard-sphere diameters differs substantially, leading to packing difficulties characteristic of glass formation. The experimentally observed range of glass formation corresponds to a ratio of hard-sphere diameters of 0.8 or less. Calculations of the free energy as a function of concentration indicate that the liquid polyball mixture is stable against the phase separation, even for widely different polyball charges.

Shih, W.-H.↗
NASA NTRS1984

OSTA-3 Shuttle payload

The Office of Space and Terrestrial Applications-3 payload, scheduled for flight on STS Mission 17, consists of four earth-observation experiments. The Feature Identification and Location Experiment-1 will spectrally sense and numerically classify the earth's surface into water, vegetation, bare earth, and ice/snow/cloud-cover, by means of spectra ratio techniques. The Measurement of Atmospheric Pollution from Satellite experiment will measure CO distribution in the middle and upper troposphere. The Imaging Camera-B uses side-looking SAR to create two-dimensional images of the earth's surface. The Large Format Camera/Attitude Reference System will collect metric quality color, color-IR, and black-and-white photographs for topographic mapping.

Dillman, R. D.↗
NASA NTRS1985

Global mean sea surface computation based upon a combination of SEASAT and GEOS-3 satellite altimeter data

A mean sea surface map was computed for the global ocean areas between 70 deg N latitude and 62 deg S latitude based upon the 70 day SEASAT and 3.5 year GEOS-3 altimeter data sets. The mean sea surface is presented in the form of a global contour map and a 0.25 deg x 0.25 deg grid. A combination of regional adjustments based upon crossover techniques and the subsequent adjustment of the regional solutions into a global reference system was employed in order to minimize the effects of radial orbit error. A global map of the crossover residuals after the crossover adjustments are made is in good agreement with earlier mesoscale variability contour maps based upon the last month of SEASAT collinear data. This high level of agreement provides good evidence that relative orbit error was removed to the decimeter level on a regional basis. This represents a significant improvement over our previous maps which contained patterns, particularly in the central Pacific, which were due to radial orbit error. Long wavelength, basin scale errors are still present with a submeter amplitude due to errors in the PGS-S4 gravity model. Such errors can only be removed through the improvement of the Earth's gravity model and associated geodetic parameters.

Marsh, J. G.↗
NASA NTRS1985

Circulation of the atmosphere from the surface to 100 km

A reference model of the atmospheric circulation on Venus based on available observations is presented. The reference atmosphere has the following main features: (1) the entire atmosphere below 85 km moves predominantly from east to west in the planet's reference system (in the same direction as the rotation of the solid planet itself) with the possible exception of the lowest 10 km where velocities are low, (2) a jet is present near the cloud-top level at 45 deg latitude in both hemispheres, with a magnitude of approximately 100 m/s, (3) a weak meridional (north-south component) flow directed towards either pole is superimposed on the zonal (east-west motion at cloud-top level (about 68 km) altitudes, and, (4) eddies or wave motions are present in the atmosphere, with amplitudes of less than 16/ms in the upper atmosphere.

Kerzhanovich, V. V.↗
NASA NTRS1987

A no hair theorem and the problem of initial conditions

It is shown that under very general conditions, any inhomogeneous cosmological model with a positive cosmological constant that can be described in a synchronous reference system will tend asymptotically in time towards the de Sitter solution. This renders the problem of initial conditions less severe.

Jensen, Lars Gerhard↗
NASA NTRS1989

AM0 efficiency measurements

Procedures for measuring the air mass zero (AM0) current versus voltage characteristics and calculating the efficiency are discussed. The various factors influencing the determination of the efficiency include the I-V measurement system, reference cell calibration, standard reporting conditions, area measurement, light source characteristics, temperature measurement and control, and the measurement procedures. Each of these sources contributes to the precision index and bias limit which is combined to obtain the total uncertainty in the efficiency. These factors are discussed as well as how to minimize differences in the reported AM0 efficiency of a given PV cell between various laboratories.

Emery, Keith↗
NASA NTRS1988

Celestial reference frames - Definitions and accuracies

The paper examines the accuracies of the three most prominent celestial reference frames: stellar catalogs, lunar and planetary ephemerides, and radio source catalogs. Among other findings, it is shown that the stellar reference systems presently shows uncertainties up to nearly a tenth of an arcsec. Radio-source catalogs have internal consistencies of 0.001 arcsec or less.

Standish, E. M.↗