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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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New and versatile method has been developed to supplement or replace use of original CINDA thermal analyzer program in order to take advantage of improved systems software and machine speeds of third generation computers. CINDA-3G program options offer variety of methods for solution of thermal analog models presented in network format.
Computer program has been written to analyze group of 100-node areas and then provide for summation of any number of 100-node areas to obtain temperature profile. SINDA program options offer user variety of methods for solution of thermal analog modes presented in network format.
A method for calculating the geometric factor of cylindrical plate electrostatic energy analyzers with various detector geometries is described. The effects of the fringe-field are estimated. For a special simple case an exact geometric factor is calculated enabling an estimate of the inaccuracies of the approximations used in other cases. The results of some calculations are presented and a simple approximate expression for the geometric factor is deduced.
A computer program for determining the partial pressures of various gases from residual-gas-analyzer data is given. The analysis of the ion currents of 18 m/e spectrometer peaks allows the determination of 12 gases simultaneously. Comparison is made to ion-gage readings along with certain other control information. The output data are presented in both tabular and graphical form.
A model for each of the basic flow elements involved in the unsteady stall of a two-dimensional airfoil in incompressible flow is presented. The interaction of these elements is analyzed using a digital computer. Computations of the loading during transient and sinusoidal pitching motions are in good qualitative agreement with measured loads. The method was used to confirm that large torsional response of helicopter blades detected in flight tests can be attributed to dynamic stall.
A system was developed and applied at the NASA Manned Spacecraft Center for measuring and analyzing directional molecular flows in a large thermal vacuum chamber in order to verify molecular environment and identify characteristic and abnormal test article and chamber conditions. The system is described, and some results obtained in over 1200 hours of operation are given.
A technique which employs known gas mixtures to calibrate the residual gas analyzer (RGA) is described. The mass spectra from the RGA are recorded for each gas mixture. This mass spectra data and the mixture composition data each form a matrix. From the two matrices the calibration matrix may be computed. The matrix mathematics requires the number of calibration gas mixtures be equal to or greater than the number of gases included in the calibration. This technique was evaluated using a mathematical model of an RGA to generate the mass spectra. This model included shot noise errors in the mass spectra. Errors in the gas concentrations were also included in the valuation. The effects of these errors was studied by varying their magnitudes and comparing the resulting calibrations. Several methods of evaluating an actual calibration are presented. The effects of the number of gases in then, the composition of the calibration mixture, and the number of mixtures used are discussed.
A technique for analyzing the polarization properties of plane waves is developed which offers a number of advantages over methods currently used in the analysis of both ground and satellite observations of waves. This technique reduces the computations required to find the wave normal vector, is less sensitive to common noise sources, and is amenable to analog implementation. This technique is applied specifically to the analysis of a proton whistler, but may also be used in most studies of ULF, ELF, and VLF magnetic wave phenomena.
The program not only can render temperature distributions in solids subjected to various thermal boundary conditions, including effects of diffuse-gray thermal radiation, but is fully compatible in capacity and in the finite-element model representation with that of its structural counterpart in the NASTRAN system. The development history of the finite-element approach for determining temperatures is summarized. The scope of analysis capability, program structure, features, and limitations are given with the objective of providing NASTRAN users with an overall veiw of the NASTRAN thermal analyzer.
The NASTRAN thermal analyzer will include the capability to perform complete thermal analyses on structures. One of the inputs to NASTRAN required to simulate radiative heat transfer between surfaces will be the view factors (also called shape factors, form factors, configuration factors) between those surfaces. The purpose of the VIEW program is to compute these view factors and produce appropriate RADMTX and RADLST output to be used as NASTRAN bulk data.
One aspect of the degradation in performance of retarding potential analyzers caused by potential depressions in the retarding grid is quantitatively estimated from laboratory measurements and theoretical calculations. A simple expression is obtained that permits the use of laboratory measurements of grid properties to make first-order corrections to flight data. Systematic positive errors in ion temperature of approximately 16% for the Ogo 4 instrument and 3% for the Ogo 6 instrument are deduced. The effects of the transverse electric fields arising from the grid potential depressions are not treated.
A method for calculating the geometric factor of cylindrical plate electrostatic energy analyzers with various detector geometries is described. The effects of the fringe field are estimated. For a special simple case an exact geometric factor is calculated, enabling an estimate to be made of the inaccuracies of the approximations used in other cases. The results of some calculations are presented, and a simple approximate expression for the geometric factor is deduced.
Six-channel radiometer with three ultraviolet detection channels measures temperatures at 2-millisecond intervals. One infrared channel measures total radiation, and two infrared channels measure radiation in discrete spectral intervals at rate of 40 intervals per second. Analyzer consists of optical and electrical system.
Analyzer operates with broadband light from blackbody infrared source. Light is passed sequentially through two gas-filled chambers to suitable infrared detector while pressures in gas-filled chambers are modulated in sinusoidal manner. Because pressure of infrared-absorbing gases in chambers is modulated, amount of light absorbed by gases is also modulated.
The resolvability of point sources of incoherent light is analyzed by quantum detection theory in terms of two hypothesis-testing problems. In the first, the observer must decide whether there are two sources of equal radiant power at given locations, or whether there is only one source of twice the power located midway between them. In the second problem, either one, but not both, of two point sources is radiating, and the observer must decide which it is. The decisions are based on optimum processing of the electromagnetic field at the aperture of an optical instrument. In both problems the density operators of the field under the two hypotheses do not commute. The error probabilities, determined as functions of the separation of the points and the mean number of received photons, characterize the ultimate resolvability of the sources.
Combining human and computer interpretation capabilities to analyze ERTS-1 imagery
SRI satellite image analyzer console for mapping southern Arizona plant communities from ERTS-1 imagery
The human photointerpreter and the computer have complementary capabilities that are exploited in a computer-based data analysis system developed at the Forestry Remote Sensing Laboratory, University of California. This system is designed to optimize the process of extracting resource information from ERTS images. The human has the ability to quickly delineate gross differences in land classes, such as wildland, urban, and agriculture on appropriate ERTS images, and to further break these gross classes into meaningful subclasses. The computer, however, can more efficiently analyze point-by-point spectral information and localized textural information which can result in a much more detailed agricultural or wildland classification based on species composition and/or plant association. These human and computer capabilities have been integrated through the use of an inexpensive small scale computer dedicated to the interactive preprocessing of the human inputs and the display of raw ERTS images and computer classified images. The small computer is linked to a large scale computer system wherein the bulk of the statistical work and the automatic point-by-point classification is done.