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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Program and charts for determining shock tube, and expansion tunnel flow quantities for real air

A computer program in FORTRAN 4 language was written to determine shock tube, expansion tube, and expansion tunnel flow quantities for real-air test gas. This program permits, as input data, a number of possible combinations of flow quantities generally measured during a test. The versatility of the program is enhanced by the inclusion of such effects as a standing or totally reflected shock at the secondary diaphragm, thermochemical-equilibrium flow expansion and frozen flow expansion for the expansion tube and expansion tunnel, attenuation of the flow in traversing the acceleration section of the expansion tube, real air as the acceleration gas, and the effect of wall boundary layer on the acceleration section air flow. Charts which provide a rapid estimation of expansion tube performance prior to a test are included.

Miller, C. G., III↗
NASA NTRS1975

The Bulk Lunar Electrical Conductivity

The electrical conductivity structure was studied of a spherically layered moon consistent with the very low frequency magnetic data collected on the lunar surface and by Explorer 35. In order to obtain good agreement with the lunar surface magnetometer observations, the inclusion of a void cavity behind the moon requires a conductivity at shallow depths higher than that of models having the solar wind impinging on all sides. By varying only the source parameters, a conductivity model can be found that yields a good fit to both the tangential response upstream and the radial response downstream. This model also satisfies the dark side tangential response in the frequency range above 0.006 Hz, but the few data points presently available below this range do not seem to agree with the theory.

Leavy, Donald Lucien↗
NASA NTRS1975

Catalog of particles and fields data 19581965

Available particles and fields data, covering the period 1966 to 1973 inclusive, are announced. Most data result from individual experiments carried on board individual spacecraft. A variety of user-oriented data are included. A newly created composite interplanetary magnetic field data set is discussed and other data products, that may interest the particles/fields community are mentioned, including geomagnetism, magnetopause and bow shock positions, and magnetospherically trapped particles.

King, M. L.↗
NASA NTRS1971

The fabrication, testing and delivery of boron/epoxy and graphite/epoxy nondestructive test standards

A description is given of the boron/epoxy and graphite/epoxy nondestructive test standards which were fabricated, tested and delivered to the National Aeronautics and Space Administration. Detailed design drawings of the standards are included to show the general structures and the types and location of simulated defects built into the panels. The panels were laminates with plies laid up in the 0 deg, + or - 45 deg, and 90 deg orientations and containing either titanium substrates or interlayered titanium perforated shims. Panel thickness was incrementally stepped from 2.36 mm (0.093 in.) to 12.7 mm (0.500 in.) for the graphite/epoxy standards, and from 2.36 mm (0.093 in.) to 6.35 mm (0.25 in.) for the boron/epoxy standards except for the panels with interlayered shims which were 2.9 mm (0.113 in.) maximum thickness. The panel internal conditions included defect free regions, resin variations, density/porosity variations, cure variations, delaminations/disbonds at substrate bondlines and between layers, inclusions, and interlayered shims. Ultrasonic pulse echo C-scan and low-kilovoltage X-ray techniques were used to evaluate and verify the internal conditions of the panels.

Pless, W. M.↗
NASA NTRS1975

A B-B-G-K-Y framework for fluid turbulence

A kinetic theory for fluid turbulence is developed from the Liouville equation and the associated BBGKY hierarchy. Real and imaginary parts of Fourier coefficients of fluid variables play the roles of particles. Closure is achieved by the assumption of negligible five-coefficient correlation functions and probability distributions of Fourier coefficients are the basic variables of the theory. An additional approximation leads to a closed-moment description similar to the so-called eddy-damped Markovian approximation. A kinetic equation is derived for which conservation laws and an H-theorem can be rigorously established, the H-theorem implying relaxation of the absolute equilibrium of Kraichnan. The equation can be cast in the Fokker-Planck form, and relaxation times estimated from its friction and diffusion coefficients. An undetermined parameter in the theory is the free decay time for triplet correlations. Some attention is given to the inclusion of viscous damping and external driving forces.

Montgomery, D.↗
NASA NTRS1975

Power processing for electric propulsion

The inclusion of electric thruster systems in spacecraft design is considered. The propulsion requirements of such spacecraft dictate a wide range of thruster power levels and operational lifetimes, which must be matched by lightweight, efficient, and reliable thruster power processing systems. Electron bombardment ion thruster requirements are presented, and the performance characteristics of present power processing systems are reviewed. Design philosophies and alternatives in areas such as inverter type, arc protection, and control methods are discussed along with future performance potentials for meeting goals in the areas of power process or weight (10 kg/kW), efficiency (approaching 92 percent), reliability (0.96 for 15,000 hr), and thermal control capability (0.3 to 5 AU).

Finke, R. C.↗
NASA NTRS1975

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 143

This supplement to Aerospace Medicine and Biology (NASA SP-7011) lists 251 reports, articles and other documents announced during June 1975 in Scientific and Technical Aerospace Reports (STAR) or in International Aerospace Abstracts (IAA). The first issue of the bibliography was published in July 1964; since that time, monthly supplements have been issued. In its subject coverage, Aerospace Medicine and Biology concentrates on the biological, physiological, and environmental effects to which man is subjected during and following simulated or actual flight in the earth's atmosphere or in interplanetary space. References describing similar effects of biological organisms of lower order are also included. Such related topics as sanitary problems, pharmacology, toxicology, safety and survival, life support systems, exobiology, and personnel factors receive appropriate attention. In general, emphasis is placed on applied research, but references to fundamental studies and theoretical principles related to experimental development also qualify for inclusion.

Source record↗
NASA NTRS1974

Rotational-vibrational coupling in the theory of electron-molecule scattering

The adiabatic-nuclei approximation of vibrational-rotational excitation of homonuclear diatomic molecules can be simply augmented to describe the vibrational-rotational coupling by including the dependence of the vibrational wave function on j. Appropriate formulas are given, and the theory, is applied to e-H2 excitation, whereby it is shown that deviations from the simple Born-Oppenheimer approximation measured by Wong and Schultz can be explained. More important, it can be seen that the inclusion of the j-dependent centrifugal term is essential for transitions involving high-rotational quantum numbers.

Temkin, A.↗
NASA NTRS1974

Metal-olivine associations and Ni-Co contents in two Apollo 12 mare basalts

Olivine crystals in mare basalts 12004,8 and 12022,12 are normally zoned with Cr-poor rims. The Ni content of rare 2- to 10-micron metal inclusions in olivine decreases markedly as Fe/Mg in their immediate olivine hosts increases. Each metal grain appears to have been enclosed by late olivine almost immediately after it crystallized. The fractionation trend for the olivine and metal contrasts with the subsolidus equilibration trend for pallasites. For the basalts, not even local equilibrium of Fe, Ni and Co at metal/olivine interfaces can be detected by microprobe. Ni and Co concentrations range from about 300 ppm in olivine cores to about 70 ppm in rims. The limits of detection, at 95% confidence, are 36 ppm (Ni) and 25 ppm (Co). The distribution of Ni and Co in olivine, like that of Mg and Cr, records the depletion of these elements in the melt.

Hewins, R. H.↗
NASA NTRS1974

Nodular growth in thick-sputtered metallic coatings

Thick-sputtered S-Monel, silver, and 304 stainless steel coatings were deposited on mica and metal substrates with various surface finishes to investigate the nodular growth in the coating by scanning electron microscopy. The geometry and the surface structure of the nodules are characterized. Compositional changes within the coating were analyzed by energy dispersive X-ray analysis. Defects in the surface finish (i.e., scratches, inclusions, etc.), act as preferential nucleation sites and form isolated and complex nodules and various surface overgrowths in the coating. The nodule boundaries are very vulnerable to chemical etching and these nodules do not disappear after full annealing. Further, they have undesirable effects on mechanical properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces. These effects are illustrated by micrographs. Nodular growth within a coating can be minimized or eliminated by increasing the surface smoothness.

Spalvins, T.↗
NASA NTRS1975

Gas adsorption on crushed quartz and basalt

The new surfaces generated by crushing rocks and minerals adsorb gases. Different gases are adsorbed to different extents so that both the total amount and composition of the released gases are changed. This affects the interpretation of the composition of the gases obtained by vacuum crushing lunar basalts, meteorites and minerals with fluid inclusions.

Barker, C.↗
NASA NTRS1974

Lower bounds to energies for cusped-gaussian wavefunctions

Calculations for the ground states of H, He, and Be, conducted by Steiner and Sykes (1972), show that the inclusion of a very small number of cusp functions can lead to a substantial enhancement of the quality of the Gaussian basis used in molecular wavefunction computations. The properties of the cusped-Gaussian basis are investigated by a calculation of lower bounds concerning the ground state energy of the hydrogen atom.

Eaves, J. O.↗
NASA NTRS1975

Full non-linear treatment of the global thermospheric wind system. I - Mathematical method and analysis of forces. II - Results and comparison with observations

The equations of horizontal motion of the neutral atmosphere between 120 and 500 km are integrated with the inclusion of all nonlinear terms of the convective derivative and the viscous forces due to vertical and horizontal velocity gradients. Empirical models of the distribution of neutral and charged particles are assumed to be known. The model of velocities developed is a steady state model. In Part I the mathematical method used in the integration of the Navier-Stokes equations is described and the various forces are analyzed. Results of the method given in Part I are presented with comparison with previous calculations and observations of upper atmospheric winds. Conclusions are that nonlinear effects are only significant in the equatorial region, especially at solstice conditions and that nonlinear effects do not produce any superrotation.

Blum, P. W.↗
NASA NTRS1974

Fine structural changes in the lateral vestibular nucleus of aging rats

The fine structure of the lateral vestibular nucleus was investigated in Sprague-Dawley rats, that were sacrified at 4 weeks, 6-8 weeks, 6-8 months, and 18-20 months of age. In the neuronal perikaria, the following age-associated changes were seen with increasing frequency with advancing age: rodlike nuclear inclusions and nuclear membrane invaginations; cytoplasmic dense bodies with the characteristics of lipofuscin; and moderate disorganization of the granular endoplasmic reticulum. Dense bodies were also seen in glial cells. Rats 18 to 20 months old showed dendritic swellings, axonal degeneration, and an apparent increase in the number of axosomatic synaptic terminals containing flattened vesicles (presumed to be inhibitory in function).

Johnson, J. E., Jr.↗
NASA NTRS1974

Earth resources technology satellite /ERTS/ data collection and transmission buoys for inland, neritic and oceanic waters

As a result of a consortium of several industries and organizations, an economical, versatile, and stable data collection and transmission buoy has been designed, developed, and deployed to gather and transmit water quality data to a ground receiving station at three-minute intervals and to the earth resources technology satellite (ERTS) as it passes over the deployed buoy every 12 hours. The buoy system, designed for both fresh and salt water application, gathers data inclusive of temperature measurement, conductivity, relative acidity, dissolved oxygen, current speed, and direction. The mechanical design philosophy used to determine and satisfy boundary conditions involving stability, ease of deployment, servicing and maintenance, minimal manufacturing costs, and fresh and salt water installation capability is discussed. The development of peripheral handling equipment and anchoring systems is described.

Chapman, W. S.↗
NASA NTRS1975

Design considerations in the creation and maintenance of electrostatic cleanliness for solar electrically propelled spacecraft

Charge build-up on spacecraft surfaces and resulting zones of electrostatic contamination have been examined for electrically active and electrically passive spacecraft with both conducting and dielectric surface materials, illuminated and nonilluminated surface conditions, and for both inclusion and neglect of free charge effects from photocurrents and ambient space plasma particles. Techniques for measurement and reduction of electrostatic contamination zone extent have been developed for spacecraft with charge release capability. Indicated limitations for contamination cleanup are about 1 volt potential variation from spacecraft to ambient plasma. Bandwidths of electrostatic monitoring and clamping devices extend to several hundred kilohertz for both DC and 'broadband' AC electrostatic cleanliness.

Sellen, J. M., Jr.↗
NASA NTRS1975

Resonance line transfer with partial redistribution. III Mg II resonance lines in solar-type stars

We discuss the gravity dependence of the Mg II resonance lines calculated with inclusion of effects of partial redistribution in frequency. Using chromospheric models scaled from a solar model, we demonstrate the increased decoupling of the radiation temperature of the k1 feature from the minimum electron temperature in lower-gravity models. The limb darkening of the k-line in the main-sequence model is also discussed.

Milkey, R. W.↗
NASA NTRS1975

Fatigue failure of hydrogen embrittled high strength steels

Results of an experimental investigation are presented concerning the fracture behavior of cathodically charged, quenched and tempered martensitic steels under cyclic load conditions. Introduction of H2 by cathodic charging reduced fatigue life by as much as 60%. It is proposed that subsurface transverse fatigue cracks nucleate simultaneously at multiple sites, such as at microcracks, voids, or inclusions. Fatigue crack growth then occurs on planes perpendicular to the major applied stress axis in the presence of the critical combination of applied external stress and hydrogen.

Kim, Y. G.↗