SEARCH · Search NASA

Results for “Contribution”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33

All sources NASA NTRS DOE OSTI

NASA NTRS1973

Nonlinear response of boron/aluminum angleplied laminates under cyclic tensile loading: Contributing mechanisms and their effects

The nonlinear response of boron/aluminum angleplied laminates subjected to cyclic loads was investigated. A procedure is outlined and criteria are proposed which can be used to assess the nonlinear response. The procedure consists of testing strategically selected laminate configurations and analyzing the results using composite mechanics. Results from the investigation show the contributions to nonlinear behavior are from: premature random fiber breaks where the ply orientation angle is small relative to the load direction, ply relative rotation at intermediate values of the ply orientation angle, and nonlinear aluminum matrix behavior at large values of the orientation angle. Premature fiber breaks result in progressively more compliant material; large ply relative rotations result in progressively stiffer material; and pronounced matrix nonlinear behavior results in no significant change in the stiffness of the initial load portion.

Chamis, C. C.↗

NASA NTRS1974

Contributions of satellite-determined gravity results in geodesy

Different forms of the theoretical gravity formula are summarized and methods of standardization of gravity anomalies obtained from satellite gravity and terrestrial gravity data are discussed in the context of three most commonly used reference figures, e.g., International Reference Ellipsoid, Reference Ellipsoid 1967, and Equilibrium Reference Ellipsoid. These methods are important in the comparison and combination of satellite gravity and gravimetric data as well as the integration of surface gravity data, collected with different objectives, in a single reference system. For ready reference, tables for such reductions are computed. Nature of the satellite gravity anomalies is examined to aid the geophysical and geodetic interpretation of these anomalies in terms of the tectonic features of the earth and the structure of the earth's crust and mantle. Computation of the Potsdam correction from satellite-determined geopotential is reviewed. The contribution of the satellite gravity results in decomposing the total observed gravity anomaly into components of geophysical interest is discussed. Recent work on the possible temporal variations in the geogravity field is briefly reviewed.

Khan, M. A.↗

NASA NTRS1973

Nonlinear response of boron/aluminum angleplied laminates under cyclic tensile loading - Contributing mechanisms and their effects

Chamis, C. C.↗

NASA NTRS1975

Rotor systems research aircraft (RSRA) requirements for, and contributions to, rotorcraft state estimation and parameter identification

Rotor System Research Aircraft (RSRA) is designed to provide the capabilities necessary for the effective and efficient in-flight test and verification of promising rotor concepts and supporting technology developments. The RSRA requirements for, and possible contributions to, rotorcraft state estimation and parameter identification technology are discussed.

Condon, G. W.↗

NASA NTRS1975

The infrared excess of cool giant stars - A chromospheric contribution

The idea that the infrared excesses of evolved M stars may contain a contribution from a chromosphere is explored using alpha Ori and W Hya as test cases. The spectrum of alpha Ori between 8 and 30 millimicrons can be interpreted satisfactorily in terms of three components: a photosphere, a silicate dust cloud, and a cool chromosphere (temperature about 5000 K), which is optically thick at 14 millimicrons. A similar modelling for W Hya suggests a hotter chromosphere (temperature about 8000 K), with unit optical depth at 30 millimicrons. Some consequences of these chromospheres are briefly discussed.

Lambert, D. L.↗

NASA NTRS1974

SEASAT-A scientific contributions

SEASAT-A planned instrument complement and capabilities are reported together with an estimate of expected scientific contributions from satellite oceanic measurements.

Source record↗

NASA NTRS1975

Contribution of the National Aeronautics and Space Administration Langley Research Center

As part of a special international effort, three nozzles were designed and tested on single nacelle models in wind tunnels of several nations belonging to the North Atlantic Treaty Organization. All three of these nozzles were investigated in the Langley 16-foot transonic wind tunnel at the National Aeronautics and Space Administration's Langley Research Center. Langley Research Center also contributed theoretical calculations of the jet plume boundary and afterbody pressures. The calculations were obtained using an iterative solution which combined the inviscid Douglas Neumann method for the external flow with the method of characteristics for the flow in the jet plume. For the investigation, the nozzles were mounted on a single nacelle model 15.24 centimeters in diameter and 162.56 centimeters long. Tests were made at free stream Mach number from 0.4 to 1.2, and at Reynolds numbers per meter from 7.38 million to 13.78 million depending on the Mach number. Four types of data were recorded: afterbody pressure data, afterbody force data, model boundary layer data, and tunnel wall pressure data. The ratio of jet total pressure to free stream static pressure ranged up to 8.5. A description of the wind tunnel, model, and test procedure is included.

Compton, W. B., III↗

NASA NTRS1976

Contributions to the National Geodetic Satellite Program by Goddard Space Flight Center

The major scientific contributions of Goddard Space Flight Center to the National Geodetic Satellite Program between 1965 and 1973 are presented and discussed. The primary results described are the determination of the earth's gravitational field from satellite tracking and surface gravimeter data to an accuracy of about 4 mGal for wavelengths of about 1000 km and larger; the construction of a detailed geoid suitable for geodetic, tectonic, and altimetry data analysis accurate to about 2 m over continents and to 2-5 m over the northeast Pacific and Atlantic oceans; and the positioning of globally distributed tracking stations to an accuracy of 5-10 m for the interconnecting of local geodetic datums. In addition, work on the observation of the earth and ocean tidal perturbations of satellites is discussed and reviewed.

Smith, D. E.↗

NASA NTRS1976

Can internal heat contribute to the high surface temperature of Venus

It is shown that current observational data on conditions at the Venusian surface are adequate to exclude the possibility that thermal energy from a hot interior contributes to the high surface temperature of the planet. The maximum energy flux conducted from the interior is estimated by assigning a maximum thermal conductivity and a minimum thickness to the crust. It is found that the crust must be at least 10 km thick and that the maximum thermal flux for this thickness is about 6 millionths of a calorie per sq cm/sec. The relative importance of this internal energy source is assessed by comparing it with the amount of solar energy deposited at the surface. The result demonstrates that the absorbed solar energy is at least one and probably two orders of magnitude higher than the minimum flux conducted from the interior. It is concluded that a very efficient atmospheric trapping mechanism (the greenhouse effect) is operating on Venus.

Morrison, D.↗

NASA NTRS1976

Amino acid precursors in lunar fines - Limits to the contribution of jet exhaust

A sample of lunar fines collected at a maximum distance, 6.5 km, from the descent engine on Apollo 17 has been analyzed for total amino acids obtainable by hydrolysis of aqueous extracts. The minimum amounts of amino acids, calculated for a disk of 6 km radius are 10,000 to 100,000 times those which could be contributed by the lunar module jet exhaust, on the basis of conservatively limiting assumptions. The amino acids thus obtained are not explainable as due to chemical or biological contamination; their source is accordingly inferred as lunar. Under the conditions of hydrolysis of lunar extracts, cyanide is found to be converted, almost exclusively to glycine, to an extent of 0.0001.

Fox, S. W.↗

NASA NTRS1976

Contribution of the Spacelab data management system to lower cost space research

This paper reviews the design and operation of the Spacelab data management system as it has evolved. Significant improvements and extensions of the original baseline system have been incorporated and will be discussed. They include the capability for the remote control of Spacelab subsystems, improved remote data acquisition units, a high-rate digital data multiplexer, and an improved high-rate digital recorder. Emphasis will be placed on the overall system aspects, including considerations on the use of minicomputers as an adjunct to the basic Spacelab data system. The approach for experiment related software production and integration will be addressed as well. The paper focuses on the contributions of the data management system in reducing the cost of research in Spacelab.

Burger, J. J.↗

NASA NTRS1977

Nuclear emulsion measurements of the dose contribution from tissue disintegration stars on the Apollo-Soyuz mission

A total of 996 disintegration stars were prong-counted in two 100 micron llford K.2 emulsions from the dosimeter of the Docking Pilot on Apollo-Soyuz. The change of slope of the distribution at a prong number of about 6 or 7 indicates 219 stars as originating in gelatin. Applying the QF values set forth in official regulations to the energy spectra of the proton and a alpha prongs of the gelatin stars leads to a tissue star dose of 7.8 millirad or 45 millirem. The quoted values do not include the dose contribution from star-produced neutrons since neutrons do not leave visible prongs in emulsion. Nuclear theory, in good agreement with measurements of galactic radiation in the earth's atmosphere, indicates that the dose equivalent from neutrons is about equal to the one from all ionizing secondaries of stars. Application of this proposition to the star prong spectrum found on Apollo-Soyuz would set the total tissue star dose for the mission at approximately 90 millirem.

Schaefer, H. J.↗

NASA NTRS1977

The large area crop inventory experiment: An experiment to demonstrate how space-age technology can contribute to solving critical problems here on earth

The large area crop inventory experiment is being developed to predict crop production through satellite photographs. This experiment demonstrates how space age technology can contribute to solving practical problems of agriculture management.

Source record↗

NASA NTRS1977

Soil spectra contributions to grass canopy spectral reflectance

The soil or background spectra contribution to grass canopy spectral reflectance for the 0.35 to 0.80 micron region was investigated using in situ collected spectral reflectance data. Regression analysis was used to estimate accurately the unexposed soil spectral reflectance and to quantify maxima and minima for soil-green vegetation reflection contrasts.

Tucker, C. J.↗

NASA NTRS1978

Viking lander tracking contributions to Mars mapping

The paper shows how analyses of Doppler and ranging tracking data from the Viking landers are contributing to the photogrammetric inputs in three specific areas: improved determination of the spin axis of Mars, improved determination of the spin rate, and accurate position determination of the landers with respect to the equator and the vernal equinox. The latest results for these parameters are presented along with applications of these and other recent results for improved mapping of Mars. The improvements obtained provide a new level of precision for Mars mapping.

Michael, W. H., Jr.↗

NASA NTRS1978

On the contribution of intramolecular zero point energy to the equation of state of solid H2

Experimental evidence shows that the internal zero-point energy of the H2 molecule exhibits a relatively strong pressure dependence in the solid as well as changing considerably upon condensation. It is shown that these effects contribute about 6% to the total sublimation energy and to the pressure in the solid state. Methods to modify the ab initio isolated pair potential to account for these environmental effects are discussed.

Chandrasekharan, V.↗

NASA NTRS1977

Gravitational and recoil contributions to surface mass fractionation by solar-wind sputtering

The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Two distinct contributions to this mechanism are considered: (1) the tendency for a greater fraction of the heavier sputtered atoms to fall back to the surface under lunar gravity; and (2) mass-dependent kinetic effects that arise in the sputtering process itself. Calculations predict that delta (O-18) is approximately 5.6% while delta (Si-30) is about 3.6% and that oxygen is depleted in the outer regions of grains relative to the bulk composition. The results are in reasonable agreement with experiment, and one must conclude that mass fractionation by solar wind is an important phenomenon on the lunar surface.

Haff, P. K.↗

NASA NTRS1978

The internal model: A study of the relative contribution of proprioception and visual information to failure detection in dynamic systems

The development of the internal model as it pertains to the detection of step changes in the order of control dynamics is investigated for two modes of participation: whether the subjects are actively controlling those dynamics or are monitoring an autopilot controlling them. A transfer of training design was used to evaluate the relative contribution of proprioception and visual information to the overall accuracy of the internal model. Sixteen subjects either tracked or monitored the system dynamics as a 2-dimensional pursuit display under single task conditions and concurrently with a sub-critical tracking task at two difficulty levels. Detection performance was faster and more accurate in the manual as opposed to the autopilot mode. The concurrent tracking task produced a decrement in detection performance for all conditions though this was more marked for the manual mode. The development of an internal model in the manual mode transferred positively to the automatic mode producing enhanced detection performance. There was no transfer from the internal model developed in the automatic mode to the manual mode.

Kessel, C.↗