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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

The minitrack tracking function description, volume 1

The treatment of tracking data by the Minitrack system is described from the transmission of the nominal 136-MHz radio beacon energy from a satellite and the reception of this signal by the interferometer network through the ultimate derivation of the direction cosines (the angular coordinates of the vector from the tracking station to the spacecraft) as a function of time. Descriptions of some of the lesser-known functions operating on the system, such as the computer preprocessing program, are included. A large part of the report is devoted to the preprocessor, which provides for the data compression, smoothing, calibration correction, and ambiguity resolution of the raw interferometer phase tracking measurements teletyped from each of the worldwide Minitrack tracking stations to the central computer facility at Goddard Space Flight Center. An extensive bibliography of Minitrack hardware and theory is presented.

Englar, T. S., Jr.↗
NASA NTRS1975

Resonance-line transfer with partial redistribution. VII Angle-dependent redistribution

A method is presented for treating radiative transfer in resonance lines, allowing for the full angle and frequency dependence of redistribution in the scattering process, as seen in the laboratory frame. The case of an equivalent-two-level-atom source function is considered; the problem to be treated is then linear in the radiation field. We apply this method to the Ca II lines in the solar atmosphere, using a redistribution function which takes into account a mixture of coherence in the atom's frame, with Doppler redistribution in the laboratory frame (for atoms which have not suffered an elastic collision), and of complete redistribution in the laboratory frame (for atoms that are collisionally perturbed during the emission process). Both the angle-averaged approximation and the full angle-dependent solution were obtained, and were compared to assess, differentially, the effects of angular redistribution upon the computed line profile and its center-to-limb behavior. For the Ca II line in a homogeneous solar chromosphere the angle-dependent effects are found to be negligible, indicating that one may use angle-averaged redistribution functions when studying partial redistribution effects in line profiles.

Milkey, R. W.↗
NASA NTRS1977

Pioneer 10 and 11 radio occultations by Jupiter

Results on the temperature structure of the Jovian atmosphere are reviewed which were obtained by applying an integral inversion technique combined with a model for the planet's shape based on gravity data to Pioneer 10 and 11 radio-occultation data. The technique applied to obtain temperature profiles from the Pioneer data consisted of defining a center of refraction based on a computation of the radius of curvature in the plane of refraction and the normal direction to the equipotential surface at the closest approach point of a ray. Observations performed during the Pioneer 10 entry and exit and the Pioneer 11 exit are analyzed, sources of uncertainty are identified, and representative pressure-temperature profiles are presented which clearly show a temperature inversion between 10 and 100 mb. Effects of zonal winds on the reliability of radio-occultation temperature profiles are briefly discussed.

Kliore, A. J.↗
NASA NTRS1980

Bulk processing techniques for very large areas - Landsat classification of California

In 1977, California Law AB452 was passed to provide a mandate for the California Department of Forestry (CDF) to design and implement an information system to assess the forest land base for multiple uses and values. In connection with this mandate, a land-cover map of the entire state, emphasizing forest types, was produced. In producing this map, the latest techniques in digital image mosaicking were combined with the highspeed processing capability available on the ILLIAC IV parallel processor and other computer systems at the Ames Research Center (ARC). An operational and very responsive analysis method was developed at ARC that permitted on-time response to weekly workshops conducted with CDF field personnel to identify all 1,200 spectral classes and to produce final products. Over 100,000,000 acres were classified in the period between December 1, 1978, and April 15, 1979. All analyses were conducted using existing software.

Newland, W.↗
NASA NTRS1982

Ageostrophic winds in the severe strom environment

The period from 1200 GMT 10 April to 0000 GMT 11 April 1979, during which time several major tornadoes and severe thunderstorms, including the Wichita Falls tornado occurred was studied. A time adjusted, isentropic data set was used to analyze key parameters. Fourth order centered finite differences were used to compute the isallobaric, inertial advective, tendency, inertial advective geostrophic and ageostrophic winds. Explicit isentropic trajectories were computed through the isentropic, inviscid equations of motion using a 15 minute time step. Ageostrophic, geostrophic and total vertical motion fields were computed to judge the relative importance of ageostrophy in enhancing the vertical motion field. It is found that ageostrophy is symptomatic of those mass adjustments which take place during upper level jet streak propagation and can, in a favorable environment, act to increase and release potential instability over meso alpha time periods.

Moore, J. T.↗
NASA NTRS1982

Lightning and surface rainfall during Florida thunderstorms

Lightning and surface rainfall data are presented which were obtained during summer air mass thunderstorms at the NASA Kennedy Space Center. Attention is given to a computer algorithm which employed abrupt changes in the thundercloud electric fields to detect and count flashes. Statistics are given for the occurrence of lightning in 79 storms during the summer seasons of 1976-1980, as well as 28 lightning storms from the summers of 1977 and 1978. The relationship between lightning and rainfall is examined in the case of two thunderstorms whose locations allow a direct comparison of measurements. It is found that when meteorological conditions favor the production of lightning, there is an almost direct proportionality between the total rain volume and the total number of flashes.

Piepgrass, M. V.↗
NASA NTRS1983

NASA/MSFC NASTRAN auxiliary I/O routines

Since the initial installation of NASTRAN on the UNIVAC 1100/82 computer at the Marshall Space Flight Center (MSFC), a number of local codes have been incorporated as user routines. This paper describes four of these codes and how interested users may obtain additional information.

Tagg, M.↗
NASA NTRS1985

Fundamental Algorithms of the Goddard Battery Model

The Goddard Space Flight Center (GSFC) is currently producing a computer model to predict Nickel Cadmium (NiCd) performance in a Low Earth Orbit (LEO) cycling regime. The model proper is currently still in development, but the inherent, fundamental algorithms (or methodologies) of the model are defined. At present, the model is closely dependent on empirical data and the data base currently used is of questionable accuracy. Even so, very good correlations have been determined between model predictions and actual cycling data. A more accurate and encompassing data base has been generated to serve dual functions: show the limitations of the current data base, and be inbred in the model properly for more accurate predictions. The fundamental algorithms of the model, and the present data base and its limitations, are described and a brief preliminary analysis of the new data base and its verification of the model's methodology are presented.

Jagielski, J. M.↗
NASA NTRS1986

A program for the accurate generation of ephemerides for Halley's Comet

This is a discussion of an orbit determination computer program designed at the Jet Propulsion Laboratory to support the International Halley Watch and the European Space Agency's Giotto flight project to comet Halley. The program processes observational data received from the Astrometric Network of the International Halley Watch for the purpose of generating very accurate, up-to-date cometary ephemerides for Halley. An accurate comet ephemeris is essential if the Giotto spacecraft is to be navigated closely enough to the comet to satisfy its encounter objectives. Features discussed include the modelling of the nongravitational properties of Halley and the associated variational equations. The software has been implemented on several computers including the Honeywell and Siemens computers at the European Space Operations Center in Darmstadt, West Germany.

Ekelund, J. E.↗
NASA NTRS1986

Modeling Ni-Cd performance. Planned alterations to the Goddard battery model

The Goddard Space Flight Center (GSFC) currently has a preliminary computer model to simulate a Nickel Cadmium (Ni-Cd) performance. The basic methodology of the model was described in the paper entitled Fundamental Algorithms of the Goddard Battery Model. At present, the model is undergoing alterations to increase its efficiency, accuracy, and generality. A review of the present battery model is given, and the planned charges of the model are described.

Jagielski, J. M.↗
NASA NTRS1988

General Rotorcraft Aeromechanical Stability Program (GRASP) version 1.03: User's manual

The Rotorcraft Dynamics Division, Aeroflightdynamics Directorate, U.S. Army Aviation Research and Technology Activity has developed the General Rotorcraft Aeromechanical Stability Program (GRASP) to perform calculations that will assess the stability of rotorcraft in hovering flight and ground contact conditions. The program is designed to be state-of-the-art, hybrid, finite-element/multibody code that can be applied to all existing and future helicopter configurations. While GRASP was specifically designed to solve rotorcraft stability problems, its innovative structure and formulation allow for application to a wide range of structures. This manual describes the preparation of the input file required by Version 1.03 of GRASP, the procedures used to invoke GRASP on the NASA Ames Research Center CRAY X-MP 48 computer, and the interpretation of the output produced by GRASP. The parameters used by the input file are defined, and summaries of the input file and the job control language are included.

Hopkins, A. Stewart↗
NASA NTRS1988

Recent advances at NASA in calculating the electronic spectra of diatomic molecules

Advanced entry vehicles, such as the proposed Aero-assisted Orbital Transfer Vehicle, provide new and challenging problems for spectroscopy. Large portions of the flow field about such vehicles will be characterized by chemical and thermal nonequilibrium. Only by considering the actual overlap of the atomic and rotational lines emitted by the species present can the impact of radiative transport within the flow field be assessed correctly. To help make such an assessment, a new computer program is described that can generate high-resolution, line-by-line spectra for any spin-allowed transitions in diatomic molecules. The program includes the matrix elements for the rotational energy and distortion to the fourth order; the spin-orbit, spin-spin, and spin-rotation interactions to first order; and the lambda splitting by a perturbation calculation. An overview of the Computational Chemistry Branch at Ames Research Center is also presented.

Whiting, Ellis E.↗
NASA NTRS1988

IMAT (Integrated Multidisciplinary Analysis Tool) user's guide for the VAX/VMS computer

The Integrated Multidisciplinary Analysis Tool (IMAT) is a computer software system for the VAX/VMS computer developed at the Langley Research Center. IMAT provides researchers and analysts with an efficient capability to analyze satellite control systems influenced by structural dynamics. Using a menu-driven executive system, IMAT leads the user through the program options. IMAT links a relational database manager to commercial and in-house structural and controls analysis codes. This paper describes the IMAT software system and how to use it.

Meissner, Frances T.↗
NASA NTRS1990

Graphics mini manual

The computer graphics capabilities available at the Center are introduced and their use is explained. More specifically, the manual identifies and describes the various graphics software and hardware components, details the interfaces between these components, and provides information concerning the use of these components at LaRC.

Taylor, Nancy L.↗
NASA NTRS1990

The new space and Earth science information systems at NASA's archive

The on-line interactive systems of the National Space Science Data Center (NSSDC) are examined. The worldwide computer network connections that allow access to NSSDC users are outlined. The services offered by the NSSDC new technology on-line systems are presented, including the IUE request system, Total Ozone Mapping Spectrometer (TOMS) data, and data sets on astrophysics, atmospheric science, land sciences, and space plasma physics. Plans for future increases in the NSSDC data holdings are considered.

Green, James L.↗
NASA NTRS1989

Establishing a measurement based maintenance improvement program - Lessons learned in the SEL

The Software Engineering Laboratory (SEL) is a joint venture between NASA's Goddard Space Flight Center, the University of Maryland, and Computer Sciences Corporation. The use of a goal-oriented approach to measurement to establish a maintenance improvement program within the SEL is discussed. Differences are found to exist between the initial phase of the program and its routine application. This approach is demonstrated through concrete examples, and lessons learned in the establishment of a measurement based, maintenance improvement program are summarized.

Rombach, H. Dieter↗
NASA NTRS1990

The new space and earth science information systems at NASA's archive

The on-line interactive systems of the National Space Science Data Center (NSSDC) are examined. The worldwide computer network connections that allow access to NSSDC users are outlined. The services offered by the NSSDC new technology on-line systems are presented, including the IUE request system, ozone TOMS data, and data sets on astrophysics, atmospheric science, land sciences, and space plasma physics. Plans for future increases in the NSSDC data holdings are considered.

Green, James L.↗
NASA NTRS1990

Radiation protection effectiveness of a proposed magnetic shielding concept for manned Mars missions

The effectiveness of a proposed concept for shielding a manned Mars vehicle using a confined magnetic field configuration is evaluated by computing estimated crew radiation exposures resulting from galactic cosmic rays and a large solar flare event. In the study the incident radiation spectra are transported through the spacecraft structure/magnetic shield using the deterministic space radiation transport computer codes developed at Langley Research Center. The calculated exposures unequivocally demonstrate that magnetic shielding could provide an effective barrier against solar flare protons but is virtually transparent to the more energetic galactic cosmic rays. It is then demonstrated that through proper selection of materials and shield configuration, adequate and reliable bulk material shielding can be provided for the same total mass as needed to generate and support the more risky magnetic field configuration.

Townsend, Lawrence W.↗