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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 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

A simple, accurate depth check guage

Easily made, pen-light battery operated production check gauge has probe-activated switch with fail-safe features to insure proper operation. Parts can be reliably and quickly checked. Gauge is equipped with tolerance band adjustment and can use interchangeable probes for different applications. Accompanying tester permits frequent check of calibration.

Rauch, E. P.↗
NASA NTRS1973

Calculation of energy deposition distributions for simple geometries

When high-energy charged particles pass through a thin detector, the ionization energy loss in that detector is subject to fluctuations or straggling which must be considered in interpreting the data. Under many conditions, which depend upon the charge and energy of the incident particle and the detector geometry, the ionization energy lost by the particle is significantly different from the energy deposited in the detector. This problem divides naturally into a calculation of the energy loss that results in excitation and low-energy secondary electrons which do not travel far from their production points, and a calculation of energy loss that results in high-energy secondary electrons which can escape from the detector. The first calculation is performed using a modification of the Vavilov energy loss distribution. A cutoff energy is introduced above which all electrons are ignored and energy transferred to low energy particles is assumed to be equivalent to the energy deposited by them. For the second calculation, the trajectory of the primary particle is considered as a source of secondary high-energy electrons. The electrons from this source are transported using Monte Carlo techniques and multiple scattering theory, and the energy deposited by them in the detector is calculated. The results of the two calculations are then combined to predict the energy deposition distribution. The results of these calculations are used to predict the charge resolution of parallel-plate pulse ionization chambers that are being designed to measure the charge spectrum of heavy nuclei in the galactic cosmic-ray flux.

Watts, J. W., Jr.↗
NASA NTRS1972

A simple analytic approximation for dusty stromgren spheres.

We interpret recent far-infrared observations of H II regions in terms of true absorption by internal dust of a significant fraction of the Lyman-continuum photons. We present approximate analytic expressions describing the effects of internal dust on the ionization structure of H II regions, and outline a procedure for deducing the properties of this dust from optical and infrared observations.

Petrosian, V.↗
NASA NTRS1972

Activation energies for addition of O/3P/ to simple olefins.

Description of relative rate measurements for the addition of O(3P) to C2H4, C2F4, C3H6, and C4H8-1 in liquid argon at 87.5 K. The data strongly indicate that the activation energies for the addition of O(3P) to the double bonds of propylene and butene-1 are identical, probably to within 0.1 kcal/mole. It is very doubtful that differences in pre-exponential factors or other factors such as solvent effects, could invalidate this conclusion. A similar argument holds for the C2H4 and C2F4 reactions. Furthermore, the experiments suggest that the activation energy for addition of O(3P) to the double bond of butene-1 is about 0.1 kcal/mole.

Demore, W. B.↗
NASA NTRS1972

Bounding filter - A simple solution to lack of exact a priori statistics.

Wiener and Kalman-Bucy estimation problems assume that models describing the signal and noise stochastic processes are exactly known. When this modeling information, i.e., the signal and noise spectral densities for Wiener filter and the signal and noise dynamic system and disturbing noise representations for Kalman-Bucy filtering, is inexactly known, then the filter's performance is suboptimal and may even exhibit apparent divergence. In this paper a system is designed whereby the actual estimation error covariance is bounded by the covariance calculated by the estimator. Therefore, the estimator obtains a bound on the actual error covariance which is not available, and also prevents its apparent divergence.

Nahi, N. E.↗
NASA NTRS1973

Transient characteristics of simple systems to modulated random noise.

Discussed are the mean-square response exceedance characteristics of a single-tuned system to amplitude modulated noise. The results bear on the accuracy of spectral estimates of nonstationary data, and subsequently, relate directly to the design, analysis, and testing of structural systems in environments as gusts, earthquakes, and ignition transients. For noise correlated as an exponentially damped cosine, the nonstationary response may exceed its stationary value by a factor in excess of two. A time-varying shaping filter explanation is offered for this behavior. For white noise, such exceedances do not occur.

Barnoski, R. L.↗
NASA NTRS1973

Simple model for scanning-angle distribution of planetary albedo gamma-rays.

The planetary atmosphere is scanned from a satellite located at a point at an altitude of 500 km from the subsatellite point on the surface (the altitude of the satellite OSO-3). Results point out the possibility that by scanning a planet from the subsatellite point to the limb with a high resolution gamma ray detector on an orbiting satellite, the mean total baryonic scale height may be unfolded from the angular distribution of the gamma-ray flux without having to determine chemical composition and temperature.

Stecker, F. W.↗
NASA NTRS1973

Friction induced surface activity of some simple organic chlorides and hydrocarbons with iron.

Sliding friction studies were conducted on an iron surface with exposure of that surface to various hydrocarbons and organic chlorides. The hydrocarbons included ethane, ethylene, ethyl chloride, methyl chloride and vinyl chloride. Auger cylindrical-mirror analysis was used to follow interactions of the hydrocarbon and organic chlorides with the iron surface. Results with vinyl chloride indicate friction-induced surface reactivity, adsorption to surface oxides, friction sensitivity to concentration and polymerization. Variation in the loads employed influence adsorption and, accordingly, friction. Unlike results with ethyl and vinyl chloride, friction-induced surface reactivity was not observed with ethane and ethylene.

Buckley, D. H.↗
NASA NTRS1974

Convergence properties of simple genetic algorithms

The essential parameters determining the behaviour of genetic algorithms were investigated. Computer runs were made while systematically varying the parameter values. Results based on the progress curves obtained from these runs are presented along with results based on the variability of the population as the run progresses.

Bethke, A. D.↗
NASA NTRS1973

Verification of a simple relationship for shock-wave reflection in a relaxing gas

Shock-wave reflection study in a relaxing gas using pressure measurement techniques and aimed at verifying the relationship recently described by Hanson (1971) for such a shock wave reflection. The obtained results show good agreement with theory, the maximum discrepancy being about equal to the experimental uncertainty.

Hanson, R. K.↗
NASA NTRS1974

A simple two-fiber optical displacement sensor

An optical displacement sensor is described in which only a pair of large-diameter fibers is used rather than a branched bundle of many small-diameter fibers. The basic idea of the two-fiber sensor is that the axes of the fibers are at an angle to one another at the sensor face, rather than parallel as is the case for the many-fiber configuration. The sensitivity of this two-fiber sensor is approximately the same as the most sensitive configuration of the many-fiber sensor.-

Powell, J. A.↗