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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 577 records · Page 32

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NASA NTRS1979

Retarding potential analyzer for the Pioneer-Venus Orbiter Mission

The retarding potential analyzer on the Pioneer-Venus Orbiter Mission has been designed to measure most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. To accomplish these measurements on a spinning vehicle with a small telemetry bit rate, several functions, including decision functions not previously used in RPA's, have been developed and incorporated into this instrument. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection. Extensive numerical simulation and plasma chamber tests have been conducted to verify adequacy of the design for the Pioneer Mission.

Knudsen, W. C.↗

NASA NTRS1980

Automated holographic drop-size analyzer

System analyzes drop-size distribution in liquid-droplet-spray combustion fields. Holographic camera takes "stop-motion" hologram of combustion volume; it is then viewed by vidicon camera connected to digital data-processing system that identifies particles or droplets, determining their size and count, and displays histogram of drop-size distribution in holographic field.

Feinstein, S. P.↗

NASA NTRS1979

Method for analyzing radiation sensitivity of integrated circuits

A method for analyzing the radiation sensitivity of an integrated circuit is described to determine the components. The application of a narrow radiation beam to portions of the circuit is considered. The circuit is operated under normal bias conditions during the application of radiation in a dosage that is likely to cause malfunction of at least some transistors, while the circuit is monitored for failure of the irradiated transistor. When a radiation sensitive transistor is found, then the radiation beam is further narrowed and, using a fresh integrated circuit, a very narrow beam is applied to different parts of the transistor, such as its junctions, to locate the points of greatest sensitivity.

Gauthier, M. K.↗

NASA NTRS1980

Closed loop models for analyzing engineering requirements for simulators

A closed loop analytic model, incorporating a model for the human pilot, (namely, the optimal control model) that would allow certain simulation design tradeoffs to be evaluated quantitatively was developed. This model was applied to a realistic flight control problem. The resulting model is used to analyze both overall simulation effects and the effects of individual elements. The results show that, as compared to an ideal continuous simulation, the discrete simulation can result in significant performance and/or workload penalties.

Baron, S.↗

NASA NTRS1980

Technique of electrical stimulation of the vestibular analyzer under clinical conditions

Vestibular reactions appear under the action of direct current (dc) on the labyrinth of man and animals. A decrease of the stimulation effect of dc on the extralabyrinthine nervous formations in the suggested method is achieved by the use of electric pulses with steep front and back parts, as well as by previous anesthetization of the skin in the electrode application area by means of novocain solution electrophoresis. For this purpose a pulse producer giving trapezoid pulses with smoothly changing fronts and duration was constructed. With the help of an interrupter it is possible to stop the current increase instantly, and stimulation is performed at the level of the pulse 'plateau'. To induce vestibular reactions under monopolar stimulation, it is necessary to apply the current twice as high as that with bipolar electrode position. The use of short pulses with steep front and back parts for electrode stimulation of the vestibular analyzer is considered to be inexpedient.

Khechinashvili, S. N.↗

NASA NTRS1980

PROCRU: A model for analyzing crew procedures in approach to landing

A model for analyzing crew procedures in approach to landing is developed. The model employs the information processing structure used in the optimal control model and in recent models for monitoring and failure detection. Mechanisms are added to this basic structure to model crew decision making in this multi task environment. Decisions are based on probability assessments and potential mission impact (or gain). Sub models for procedural activities are included. The model distinguishes among external visual, instrument visual, and auditory sources of information. The external visual scene perception models incorporate limitations in obtaining information. The auditory information channel contains a buffer to allow for storage in memory until that information can be processed.

Baron, S.↗

NASA NTRS1980

On the application of nonlinear load elements to thermal analyses using the NASTRAN thermal analyzer

The nonlinear load elements in thermal analysis are used to simulate an undocumented nonlinear thermal boundary condition. The treatment of the nonlinearity arising from the temperature-dependent convective film coefficients is shown in detail. As an illustration, emphasis is placed on the modeling techniques and their interrelationships with the solution accuracy as affected by a specific integration algorithm of the transient thermal analysis used in the NASTRAN Thermal Analyzer. Briefly shown is the underlying theory on which the maneuvering of terms pertinent to the modeling depends. This demonstration provides some insight into the intricacies of the method that would be general to all applications. A recommendation is also made to modify a nonlinear load element that will enhance the solution capability and broaden the scope of application.

Lee, H. P.↗

NASA NTRS1979

Modal testing with Asher's method using a Fourier analyzer and curve fitting

An unusual application of the method proposed by Asher (1958) for structural dynamic and modal testing is discussed. Asher's method has the capability, using the admittance matrix and multiple-shaker sinusoidal excitation, of separating structural modes having indefinitely close natural frequencies. The present application uses Asher's method in conjunction with a modern Fourier analyzer system but eliminates the necessity of exciting the test structure simultaneously with several shakers. Evaluation of this approach with numerically simulated data demonstrated its effectiveness; the parameters of two modes having almost identical natural frequencies were accurately identified. Laboratory evaluation of this approach was inconclusive because of poor experimental input data.

Gold, R. R.↗

NASA NTRS1980

Preliminary results on the plasma environment of Saturn from the Pioneer 11 plasma analyzer experiment

The Ames Research Center Pioneer 11 plasma analyzer experiment provided measurements of the solar wind interaction with Saturn and the character of the plasma environment within Saturn's magnetosphere. It is shown that Saturn has a detached bow shock wave and magnetopause quite similar to those at earth and Jupiter. The scale size of the interaction region for Saturn is roughly one-third that at Jupiter, but Saturn's magnetosphere is equally responsive to changes in the solar wind dynamic pressure. Saturn's outer magnetosphere is inflated, as evidenced by the observation of large fluxes of corotating plasma. It is postulated that Saturn's magnetosphere may undergo a large expansion when the solar wind pressure is greatly diminished by the presence of Jupiter's extended magnetospheric tail when the two planets are approximately aligned along the same solar radial vector.

Wolfe, J. H.↗

NASA NTRS1980

Performance of the Zeeman analyzer system of the McDonald Observatory 2.7 meter telescope

The paper describes a multichannel photoelectric Zeeman analyzer at the coude spectrograph of the McDonald 2.7 m reflector. A comparison of Lick and McDonald observations of HD 153882 reveals no significant difference in slopes or zero points of the two magnetic fields indicating that the systematic scale difference of 30-40% is probably instrumental in origin. Observations of the magnetic variable beta Cor Bor revealed a more nearly sinusoidal magnetic curve with less internal scatter than the photographically determined field measures of the Lick and Mauna Kea Zeeman systems. Investigation of periodicity in the secularly varying magnetic minima of beta Cor Bor did not yield evidence of previously noted periodicities other than that expected from the time structure of the data sampling.

Vogt, S. S.↗

NASA NTRS1980

Pioneer Venus Orbiter planar retarding potential analyzer plasma experiment

The retarding potential analyzer (RPA) on the Pioneer Venus Orbiter Mission measures most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. Several functions not previously used in RPA's were developed and incorporated into this instrument to accomplish these measurements on a spinning spacecraft with a small bit rate. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection.

Knudsen, W. C.↗

NASA NTRS1980

Ionospheric wave measurements with satellite-borne cross-power spectrum analyzers

The paper studies the feasibility of using the cross-power spectrum analyzer on a satellite such as the Space Shuttle to measure the spectrum of potential and charged particle density fluctuations and macroscopic parameters in the ionosphere. The integration time required to make a measurement of a cross-power spectral density to a given accuracy, or its equivalent, the spatial resolution of a measurement to a given accuracy is examined.

Harker, K. J.↗

NASA NTRS1982

Ultrasonic Transducer Analyzer

Ultrasonic transducer-beam-intensity distributions are determined by analyzing echoes from a spherical ball. Computers control equipment and process data. Important beam characteristics, such as location of best beam focus and beam diameter at focus, can be determined quickly from extensive set of plots generated by apparatus.

Grounds, M. K.↗

NASA NTRS1982

Improved Numerical Differencing Analyzer

SINDA, Systems Improved Numerical Differencing Analyzer, solves differential and algebric equations representing physical systems. SINDA solves numerically almost any set of ordinary differential equations that represent transient behavior of a lumped-parameter system or any set of nonlinear algebraic equations that represents the steady state conditions of a physical system.

Skladany, J. T.↗

NASA NTRS1982

Simplified Thermal Analyzer --VAX Version

DEC VAX 11/780 version of the Simplified Shuttle Payload Thermal Analyzer (SSPTA) aids in evaluating thermal design of instruments to be flown in the Space Shuttle cargo bay. SSPTA is a collection of programs that are currently used in thermal analysis of spacecraft, modified for quick, preliminary analysis of payloads.

Skladany, J. T.↗

NASA NTRS1981

Evaluation of integral exposure energy load on aural analyzer of miners

The individual exposure integral noise load on workers before the beginning of hearing impairment was determined for a group of 20 male miners who had worked with drilling equipment and harvesters for 8 to 20 years before the onset of the disability. Results show that the total exposure energy load of about 4 kw x h sq m, obtained by miners in the examined group, resulted in occupational injury to the auditory organ (cochlear neuritis) in 75% of the cases. The equivalent energy level of noise computed according to the date of total energy load is roughly 99 db A, which significantly exceeds the permissible amount of 85 db A. There is a correlation (r = 0.77) between the integral exposure energy noise on the aural analyzer in the degree of increase in the total threshold for the mean speech range.

Kornilov, A. N.↗

NASA NTRS1981

Analyzing and modeling gravity and magnetic anomalies using the SPHERE program and Magsat data

Computer codes were completed, tested, and documented for analyzing magnetic anomaly vector components by equivalent point dipole inversion. The codes are intended for use in inverting the magnetic anomaly due to a spherical prism in a horizontal geomagnetic field and for recomputing the anomaly in a vertical geomagnetic field. Modeling of potential fields at satellite elevations that are derived from three dimensional sources by program SPHERE was made significantly more efficient by improving the input routines. A preliminary model of the Andean subduction zone was used to compute the anomaly at satellite elevations using both actual geomagnetic parameters and vertical polarization. Program SPHERE is also being used to calculate satellite level magnetic and gravity anomalies from the Amazon River Aulacogen.

Braile, L. W.↗

NASA NTRS1981

Study program for design improvements of the X-3060 klystron. Phase 3: Electron gun fabrication and beam analyzer evaluation. Phase 4: Klystron prototype fabrication and testing

A full scale model was produced to verify suggested design changes. Through beam analyzer study, the correct electron beam diameter and cross sectional profile were established in conjunction with the desired confining magnetic field. Comparative data on the performance of the X-3060 klystron, design predictions for the improved klystron, and performance data taken during acceptance testing of the prototype VKS-8274 JPL are presented.

Goldfinger, A.↗