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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 1,459 records · Page 81

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NASA NTRS1970

Code CUGEL: A code to unfold Ge(Li) spectrometer polyenergetic gamma photon experimental distributions

A FORTRAN code was developed for the Univac 1108 digital computer to unfold lithium-drifted germanium semiconductor spectrometers, polyenergetic gamma photon experimental distributions. It was designed to analyze the combination continuous and monoenergetic gamma radiation field of radioisotope volumetric sources. The code generates the detector system response matrix function and applies it to monoenergetic spectral components discretely and to the continuum iteratively. It corrects for system drift, source decay, background, and detection efficiency. Results are presented in digital form for differential and integrated photon number and energy distributions, and for exposure dose.

Steyn, J. J.↗

NASA NTRS1972

Mascon distribution on the moon

Results concerning the distribution of mascons on the moon have been obtained from an analysis of Apollo 8, 10, 11, and 12 lunar orbit missions. It was concluded that the tugging and pulling by the moon on the orbit plane of the Apollo spacecraft yields qualitative information concerning the distribution of the mascons.

Murphy, J.↗

NASA NTRS1972

Problem of photochemical equilibrium of ozone in planetary atmospheres: Ozone distribution in the lower atmosphere of Mars

The inherent errors of applying terrestrial atmospheric ozone distribution studies to the atmosphere of other planets are discussed. Limitations associated with some of the earlier treatments of photochemical equilibrium distributions of ozone in planetary atmospheres are described. A technique having more universal application is presented. Ozone concentration profiles for the Martian atmosphere based on the results of the Mariner 4 radio occultation experiment and the more recent results with Mariner 6 and Mariner 7 have been calculated using this approach.

Grams, G. W.↗

NASA NTRS1972

Polar cap electric field distributions related to the interplanetary magnetic field direction

The correlations between the azimuthal direction of the interplanetary magnetic field and the most simple polar cap signatures are discussed. Only the spatial distribution of the dawn-dusk polar cap field is considered. For each OGO 6 traverse across the northern or southern polar cap, the simultaneous values of the interplanetary magnetic field in solar-equatorial coordinates were recorded by the Explorer 33 magnetometer. Histograms of these values are presented and are discussed. The high degree of correlation with the longitudinal angle indicates that the relative geometry of the interplanetary magnetic field and magnetospheric magnetic fields must be fundamental to explaining the distribution of polar cap electric fields. The sign of the solar-equatorial component perpendicular to the sun-earth line appears to be a more critical parameter than the sign of the component toward the sun. The Svalgaard-Mansurov correlation and the correspondence between fast convection and parallel magnetospheric and interplanetary magnetic fields are described.

Heppner, J. P.↗

NASA NTRS1972

Coolant pressure and airflow distribution in a strut-supported transpiration-cooled vane for a gas turbine engine

An analysis to predict pressure and flow distribution in a strut-supported wire-cloth vane was developed. Results were compared with experimental data obtained from room-temperature airflow tests conducted over a range of vane inlet airflow rates from 10.7 to 40.4 g/sec (0.0235 to 0.0890 lb/sec). The analytical method yielded reasonably accurate predictions of vane coolant flow rate and pressure distribution.

Kaufman, A.↗

NASA NTRS1972

Optimal control of first order distributed systems

The problem of characterizing optimal controls for a class of distributed-parameter systems is considered. The system dynamics are characterized mathematically by a finite number of coupled partial differential equations involving first-order time and space derivatives of the state variables, which are constrained at the boundary by a finite number of algebraic relations. Multiple control inputs, extending over the entire spatial region occupied by the system ("distributed controls') are to be designed so that the response of the system is optimal. A major example involving boundary control of an unstable low-density plasma is developed from physical laws.

Johnson, T. L.↗

NASA NTRS1972

Observations of proton spectra (1.0 less than or equal to proton energy less than or equal to 300 keV) and pitch angle distributions at the plasmapause

Detailed proton spectral and pitch angle distribution observations were obtained from two proton detectors and a fluxgate magnetometer flown on Small Scientific Satellite A (Explorer 45). The data of interest are from orbit 99 in-bound occurring on 17 December 1971, some 8 hours prior to the sudden commencement of a magnetic storm. The data are consistent with the initiation of ion cyclotron instability when certain requirements are met. These criteria are met initially at the altitude at which the sudden intensity decrease occurs. However, after the initiation of the instability, the linear theory is unable to explain the further evolution of intensities, pitch angle distributions, and energy spectra of the ring current particles.

Williams, D. J.↗

NASA NTRS1972

Energy Distributions and spectra of Orion B stars

New MK spectral types and energy distributions are presented for B stars in Orion for which far ultraviolet flux excesses have recently been discovered. Significant differences between HD spectral energy distributions show the Orion late B stars to have smaller Balmer discontinuities than do field stars of the same spectral types. For the late B stars, these effects cause the 1500 A fluxes to be under-estimated by approximately 0.5 mag. No comparable systematic effects were found for the early B stars.

Schild, R. E.↗

NASA NTRS1972

Space vehicle electrical power processing distribution and control study. Volume 1: Summary

A concept for the processing, distribution, and control of electric power for manned space vehicles and future aircraft is presented. Emphasis is placed on the requirements of the space station and space shuttle configurations. The systems involved are referred to as the processing distribution and control system (PDCS), electrical power system (EPS), and electric power generation system (EPGS).

Krausz, A.↗

NASA NTRS1971

Three optical methods for remotely measuring aerosol size distributions.

Three optical probing methods for remotely measuring atmospheric aerosol size distributions are discussed and contrasted. The particular detection methods which are considered make use of monostatic lidar (laser radar), bistatic lidar, and solar radiometer sensing techniques. The theory of each of these measurement techniques is discussed briefly, and the necessary constraints which must be applied to obtain aerosol size distribution information from such measurements are pointed out. Theoretical and/or experimental results are also presented which demonstrate the utility of the three proposed probing methods.

Reagan, J. A.↗

NASA NTRS1971

Redshifts and absolute spectral energy distributions of galaxies in distant clusters.

Absolute spectral energy distributions were measured in galaxies of three distant clusters. Redshifts and information on evolutionary effects are inferred by a comparison of the results with the integrated light energy distribution for nearby giant elliptical galaxies. Evidence for evolution over the last 3 to 6 billion years could not be established for these galaxies.

Oke, J. B.↗

NASA NTRS1972

The temperature distribution in an infinite medium resulting from a plane source of finite duration.

The temperature distribution in an infinite slab during and following heat generation by a plane source of finite duration is studied. An expression for the instantaneous plane source is obtained. By integration of this expression, the temperature distribution following the end of heating can be obtained. Further, the treatment is extended to time-varying heat generation functions, and an example is presented.

Montealegre, A.↗

NASA NTRS1972

Size frequency distribution of Martian craters and relative age of light and dark terrains.

Light and dark terrains in and around Meridiani Sinus, mapped on the imagery from Mariner 6 and Mariner 7, were found to have significantly different cumulative size frequency distributions of craters. The light terrain on a mosaic of frames 6N11, 6N13, and 6N19 has a greater proportion of large craters and a lesser proportion of smaller craters than the dark terrain on the same frames. The light terrain is interpreted to be generally older than the dark terrain. The filling or partial filling of the smaller craters on the light terrain by surface detritus is suggested. Several wide-angle frames have remarkably similar cumulative crater size frequency distributions that may be representative of a large portion of the Martian surface.

Woronow, A.↗

NASA NTRS1972

A Bayesian approach to parameter and reliability estimation in the Poisson distribution.

For life testing procedures, a Bayesian analysis is developed with respect to a random intensity parameter in the Poisson distribution. Bayes estimators are derived for the Poisson parameter and the reliability function based on uniform and gamma prior distributions of that parameter. A Monte Carlo procedure is implemented to make possible an empirical mean-squared error comparison between Bayes and existing minimum variance unbiased, as well as maximum likelihood, estimators. As expected, the Bayes estimators have mean-squared errors that are appreciably smaller than those of the other two.

Canavos, G. C.↗

NASA NTRS1972

Changes in the frequency distribution of energy deposited in short pathlengths as a function of energy degradation of the primary beam.

The frequency distributions of event size in the deposition of energy over small pathlengths have been measured after penetration of 44.3 MeV protons through various thicknesses of tissue-equivalent material. Results show that particle energy straggling of an initially monoenergetic proton beam after passage through an absorber causes the frequency distributions of energy deposited in short pathlengths of low atomic number materials to remain broad. In all cases investigated, the ratio of the most probable to the average energy losses has been significantly less than unity.

Baily, N. A.↗

NASA NTRS1971

Transition element distribution in stony meteorites and in terrestrial and lunar rocks.

Discussion of the distribution of the transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) among the individual minerals of stony meteorites, and comparison with data on comparable lunar and terrestrial minerals. As an example of meteorite distribution patterns, data on the Modoc meteorite are presented. For the lunar rocks, microprobe data are used, along with published information from other investigators. For comparison with terrestrial igneous rocks, Skaergaard intrusion rocks are used. They present some striking analogies in mineralogy and petrology with the lunar igneous rocks and are thus peculiarly suitable for this cross comparison.

Mason, B.↗

NASA NTRS1972

Stability of distributed parameter systems.

A theorem is derived for the stability of solutions of general linear partial differential equations. A norm of the state space in the form of multiple integrals over the spatial domain is used for the Liapunov functional. Theorems and lemmas are also given for linear time-invariant constant coefficient distributed parameter systems, a class of nonlinear distributed parameter systems and for others with a Lure-type nonlinearity. The theorem conditions are similar to those known for corresponding ordinary differential equations but with operators replacing matrices.

Park, K. E.↗

NASA NTRS1972

Spatial distribution of energetic plasma sheet electrons.

The spatial distribution of energetic plasma sheet electrons (E greater than 50 keV) out to a radial distance of 24 earth radii using data from electron spectrometer and fluxgate magnetometer experiments on Ogo 5 is presented. A comparison of distributions in geocentric solar magnetospheric coordinates (GSM) prepared with and without the use of a neutral sheet model indicates that the use of such a model facilitates organization of plasma sheet data. The percentage of flux occurrence above a given flux threshold falls off rapidly with distance from the neutral sheet. Contours of constant percentage of occurrence diverge slightly from the neutral sheet at local times away from midnight. This effect decreases with increasing flux threshold.

Walker, R. J.↗