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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 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Comparison of layer thickness as observed by Nimbus E microwave spectrometer and by radiosonde

Atmospheric layer thicknesses observed by the microwave spectrometer of the Nimbus E satellite are compared with radiosonde-derived thicknesses for selected short periods. An average 45 m rms discrepancy is found for the 100-50 kPa layer, and several sources of this discrepancy are quantified in the following way. Correlation coefficients between pairs of spectrometer observations and between pairs of radiosonde observations are each extrapolated to zero separation distance to provide measures of instrument noise. Microwave spectrometer noise is found to be 16 m rms and radiosonde noise 23 m rms. Estimates are also made of those portions of the total discrepancy which are due to different resolution of the sensors (about 15 m rms) and real spatial and temporal variation of the atmosphere between observations (about 17 m rms).

Wilcox, R. W.↗
NASA NTRS1977

Doubly-curved variable-thickness isoparametric heterogeneous finite element

This paper describes an element streamlined for the analysis of doubly-curved, variable-thickness structural components and illustrates its effective application to vibration and static problems. The element is isoparametric, doubly-curved, thin-shell and triangular with variable thickness and accounts for anisotropic, inhomogeneous elastic material behavior. The element has six nodes (three corner and three mid-side) with five degrees-of-freedom (DOF) per node - three translations and two rotations. Quadratic isoparametric interpolation polynomials are used to express the element geometry and displacement variables in terms of corresponding nodal variables.

Minich, M. D.↗
NASA NTRS1977

Microwave mixing with niobium variable thickness bridges

Niobium thin-film bridges 300-A thick, 1-micron wide, and 0.5-micron long joining two bulk films 5000-A thick and having normal resistance of the order of 1 ohm have been fabricated and used for microwave mixing at 10 GHz. They exhibit Josephson, bolometric, and multiple-flux-flow mixing and have useful response at 100-200 GHz. The data show in a direct way limitations imposed by flux flow and heating.

Wang, L.-K.↗
NASA NTRS1977

Laser drilling of vias in dielectric for high density multilayer LSHI thick film circuits

A design analysis of a high density multilevel thick film digital microcircuit used for large scale integration is presented. The circuit employs 4 mil lines, 4 mil spaces and requires 4 mil diameter vias. Present screened and fired thick film technology is limited on a production basis to 16 mil square vias. A process whereby 4 mil diameter vias can be fabricated in production using laser technology was described along with a process to produce 4 mil diameter vias for conductor patterns which have 4 mil lines and 4 mil spacings.

Cocca, T.↗
NASA NTRS1978

Coal thickness gauge using RRAS techniques, part 1

A noncontacting sensor having a measurement range of 0 to 6 in or more, and with an accuracy of 0.5 in or better is needed to control the machinery used in modern coal mining so that the thickness of the coal layer remaining over the rock is maintained within selected bounds. The feasibility of using the radiofrequency resonance absorption (RRAS) techniques of electron magnetic resonance (EMR) and nuclear magnetic resonance (NMR) as the basis of a coal thickness gauge is discussed. The EMR technique was found, by analysis and experiments, to be well suited for this application.

Rollwitz, W. L.↗
NASA NTRS1978

Effect of geometry on hydrodynamic film thickness

The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza's classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

Brewe, D. E.↗
NASA NTRS1979

Measuring the thickness of plastic films

Optical instrument measures thickness of translucent and transparent sheets in thickness range from 2 to 8 microns by monitoring attenuation of light as it passes through sheet.

Donohoe, K. C.↗
NASA NTRS1979

Measuring insulation thickness

Calibrated eddy-current meter measures thickness of thermal insulation on metal substrates with specially designed adapters; for example, thickness of fiberglass parts for boats or automobiles. Technique is particlarly useful for sprayed-on insulation.

Munn, D. M.↗
NASA NTRS1979

Vapor-deposited graded-thickness films

Rotating substrate and slotted mask allow varying film thickness to be deposited from vapor by exposing film substrate to metal vapor through circular mask. Useful for fabricating variable thickness coatings for controlling thermal, electrical, or other properties.

Herzig, H.↗
NASA NTRS1978

Experimental results on mass-thickness distribution in spacecraft equipment

A technique is described for evaluating the shielding properties of spacecraft equipment with respect to cosmic radiation. A gamma-ray source is used in conjunction with a scintillation detector to determine mass-thickness distribution both in plane geometry for equipment units, and in spherical geometry for given points within the spacecraft. Equations are presented for calculating mass-thickness distribution functions, and the results are compared with experimental measurements.

Bodin, V. V.↗
NASA NTRS1979

Influence of corrugation-roughness shape on aerodynamic heating in thick turbulent boundary layers

The results of an experimental program to evaluate the effects of wave shape on heat transfer and pressure distributions of corrugation roughened flat plates in thick turbulent boundary layers are presented. The wave shaping effects studied were wavelength, wave amplitude, and wave radius. The experimental program consisted of tests in the sidewall boundary layer of the Langley Continuous Flow Hypersonic Tunnel at a Mach number of 10.3 and Reynolds numbers from 1.3 to 8.2 x 10 to the 6th per meter. The effects of wave shape are analyzed, correlated and compared with previous data obtained in both thick and thin boundary layers. The correlations include the effects of a large range of geometric, inviscid flow, internal boundary layer, and bulk boundary layer parameters in supersonic and hypersonic flow.

Brandon, H. J.↗
NASA NTRS1978

Wind speed and aerosol optical thickness estimates from aircraft observations of sea glitter

A method is proposed whereby the optical characteristics of the bright glitter pattern of the sunlight reflected from water are used to determine wind speed and aerosol optical thickness in the troposphere. Radiances observed from an aircraft are used to derive the aerosol optical thickness and the surface wind speed. A scanning radiometer is used to measure the radiances in several spectral channels within 45 deg of the nadir and in a plane transverse to the aircraft motion. The observations are taken under nearly cloudless sky conditions over the Pacific Ocean (long. 130.4 deg, lat. 42.3 deg), and the aircraft height is 150 m above water with a 292-deg heading. It is shown that the derived wind speed depends strongly on the width of the glitter pattern, and that the width of the computed radiance pattern at the 150-m aircraft height diverges from the measured value, indicating overestimated wind speed.

Ahmad, Z.↗
NASA NTRS1979

Low tilt angle photometry and the thickness of Saturn's rings

Nine photographic plates taken by Focas and Dollfus (1969) at the moment of the 1966 passage of the earth through the ring plane of Saturn have been remeasured. The value 0.8 (+2.3, -0.8) km is obtained for the ring thickness. The observed transmitted radiation through the rings at two distances from the planet suggests that there are density fluctuations in Ring A with the low density areas having an optical thickness less than 0.13. The radiation reflected by the outermost part of the ring layer can be explained in terms of particles similar to those in the bulk of the rings. The time of the passage of the earth through the ring plane was found to be December 18 at 07h plus or minus 4h UT in 1966.

Lumme, K.↗
NASA NTRS1978

Effect of geometry on hydrodynamic film thickness

The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. Pressure-viscosity effects were not considered. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds boundary conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza's classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared with those using the exact expression for the film in the analysis. Contour plots are shown that indicate in detail the pressure developed between the solids.

Brewe, D. E.↗
NASA NTRS1978

How thick are lunar mare basalts

It is argued that De Hon's estimates of the thickness of lunar mare basalts, made by analyzing 'ghost' craters on mare surfaces, were inflated as the result of the crater morphometric data of Pike (1977) to reconstruct rim heights of degraded craters. Crater rim heights of 82 randomly selected highland craters of various states of degradation were determined, and median rim height was compared to that of corresponding fresh impact structures. Results indicate that the thickness estimates of De Hon may be reduced by a factor of 2, and that the total volume of mare basalt produced throughout lunar history could be as little as 1-2 million cubic kilometers. A survey of geochemical and petrographic evidence indicates that lateral transport of regolith components over distances of much greater than 10 km is relatively inefficient; it is suggested that vertical mixing of a highland substrate underlying the basaltic fill may have had a primordial role in generating the observed mare width distributions and high concentrations of exotic components in intrabasin regoliths.

Hoerz, F.↗
NASA NTRS1980

Some limitations in applying classical EHD film-thickness formulae to a high-speed bearing

Elastohydrodynamic film thickness was measured for a 20 mm ball bearing using the capacitance technique. The bearing was thrust loaded to 90, 448, and 778 N. The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa. Test speeds ranged from 400 to 14,000 rpm. Film thickness measurements were taken with four different lubricants: (1) synthetic paraffinic; (2) synthetic paraffinic with additives; (3) neopentylpolyol (tetra) ester; and (4) synthetic cycloaliphatic hydrocarbon traction fluid. The test bearing was mist lubricated. Test temperatures were 300, 338, and 393 K. The measured results were compared to theoretical predictions and are presented.

Coy, J. J.↗
NASA NTRS1980

Effects of supply conditions on film thickness in lubricated Hertzian contacts

A generalization of the hydrodynamic expression for Hertzian contacts is described and various methods for calculating the thickness of the oil film winter steady-state, isothermal conditions are given. This is important for engineering applications such as gears and bearings because these results are closer to real operating conditions. Theories of lubrication are discussed, and the mathematics involved are presented using approximately 30 equations and 13 figures. For lubricated, linear, elliptical or point Hertzian contacts it is demonstrated how to calculate the thickness of the oil film at the center of the contact for steady-state isothermal conditions.

Dalmaz, G.↗
NASA NTRS1980

Film thickness for different regimes of fluid-film lubrication

Film thickness equations are provided for four fluid-film lubrication regimes found in elliptical contacts. These regimes are isoviscous-rigid; viscous-rigid; elastohydrodynamic lubrication of low-elastic-modulus materials (soft EHL), or isoviscous-elastic; and elastohydrodynamic lubrication of high-elastic-modulus materials (hard EHL), or viscous-elastic. The influence or lack of influence of elastic and viscous effects is the factor that distinguishes these regimes. The results are presented as a map of the lubrication regimes, with film thickness contours on a log-log grid of the viscosity and elasticity for three values of the ellipticity parameter.

Hamrock, B. J.↗