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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Steady state and transient temperature distributions in the human thigh covered with a cooling pad

An analytical and experimental study was done on the performance of cooling pads attached to a human thigh. Each cooling pad consisted of a long, water cooled tube formed into a serpentine shape with uniform spacing between the parallel sections. The analytical work developed a cylindrical model for the human thigh. The transient times predicted by this model ranged from 25 to 80 minutes, which is reasonably close to the experimental results. Calculated and measured steady state temperature profiles were in fair agreement. The transient times associated with a change from a high metabolic rate of 1800 Btu/hr (528 w) to a low level of 300 Btu/hr (88 w), were found to be about 120 minutes. A change from 300 Btu/hr (264 w) to 300 Btu/hr (88 w) resulted in 90 to 100 minute transients. However, the transient times for a change in metabolic rate in the opposite direction from 300 Btu/hr (88 w) to 1800 Btu/hr (528 w) were 40 to 60 minutes.

Leo, R. J.↗
NASA NTRS1973

Digital simulation of the serpentuator using MARSYAS

Serpentuator is a serpentine teleoperator device for intravehicular and extravehicular activities in space. The serpentuator is simulated using simulation software system MARSYAS and using the Component-Connection Simulation model and the Direct Simulation model. A comparison of the results for the two cases shows that under identical conditions, simulation execution time in the Component-Connection model case is reduced by a factor of the order of 100. A visual display of the serpentuator positions is obtained using the AMTRAN system on the Datacraft DC 6024 computer.

Singh, S., P.↗
NASA NTRS1973

Compact thermoelectric converter systems technology

A schematic of the developed tubular thermoelectric module is shown. It consists of alternate washers of n- and p-type lead telluride, separated by thin natural mica washers. Electrical continuity within the circuit is accomplished by cylindrical conductor rings located at the I.D. and O.D. of the lead telluride washers. The conductor rings are also separated by the same mica which separate the lead telluride washers. The result is a radially serpentine current path along the length of the module. The circuit is isolated from the structural claddings by thin sleeves of boron nitride. Circuit containment and heat transfer surfaces are provided by the inner and outer cladding, heat being transferred from a heat source at the inner clad, conducted radially outward through the lead telluride to the outer clad where the waste heat is removed by a heat rejection system.

Source record↗
NASA NTRS1973

Pulsations, interpulsations, and sea-floor spreading.

It is postulated that worldwide transgressions (pulsations) and regressions (interpulsations) through the course of geologic time are related to the elevation and subsidence of oceanic ridge systems and to sea-floor spreading. Two multiple working hypotheses are advanced to explain major transgressions and regressions and the elevation and subsidence of oceanic ridge systems. One hypothesis interrelates the sea-floor spreading hypothesis to the hypothesis of sub-Mohorovicic serpentinization. The second hypothesis relates the sea-floor spreading hypothesis to a hypothesis involving thermal expansion and contraction.

Pessagno, E. A., Jr.↗
NASA NTRS1974

Serpentuator simulation using MARSYAS

The Serpentuator is a serpentine teleoperator device for intraand extravehicular activities in space. It is simulated using the digital simulation software MARSYAS. Direct Simulation (DS) and Component-Connection Simulation (CCS) models are set up. The simulation execution time for the CCS model is less than that of the DS model by a factor of the order of 100. A visual display of the Serpentuator positions is obtained using AMTRAN.

Singh, S. P.↗
NASA NTRS1975

The Igwisi Hills extrusive 'kimberlites'

The petrography and mineral chemistry of volcanic rocks from the Igwisi Hills in Tanzania are discussed. There is considerable evidence to suggest that the Igwisi rocks are extrusive kimberlites: a two-component nature with high P-T minerals in a low P-T matrix; the presence of chrome pyrope, Al enstatite, chrome diopside, chromite and olivine; a highly oxidized, volatile-rich matrix with serpentine, calcite, magnetite, perovskite; high Sr, Zr, and Nb contents; occurrence in a narrow isolated vent within a stable shield area. The Igwisi rocks differ from kimberlite in the lack of magnesian ilmenite, the scarcity of matrix phlogopite, and the overall low alkali content. They apparently contain material from phlogopite-bearing garnet peridotites with a primary mineral assemblage indicative of equilibrium at upper mantle temperatures and pressures. This primary assemblage was brought rapidly to the surface in a gas-charged, carbonate-rich fluid. Rapid upward transport, extrusion, and rapid cooling have tended to prevent reaction between inclusions and the carbonate-rich matrix that might otherwise have yielded a more typical kimberlite.

Reid, A. M.↗
NASA NTRS1976

Development and fabrication of an advanced liquid cooling garment

The elastomeric film fin/tube concept which was developed is a composite of polyurethane film, fine expanded silver mesh, a serpentine pattern polyurethane transport tubing and an integral comfort liner, all bonded via adhesive application and vacuum-bagged for final cure. As demonstrated by thermal analysis, the composite garment material is capable of removing a 293 watt (1000 BTU/hr) metabolic load through a head and torso cooling area of .46 sq m (5 sq ft) with tube spacing of slightly under one inch. A total of 60 test elements, each .15m x .15m (6 in. x 6 in.) were fabricated in support of the liquid cooling garment concept development. In parallel with the fabrication of these elements a continuing series of laboratory tests to support the fabrication techniques was carried out. The elements and supporting tests are described.

Leith, J. R.↗
NASA NTRS1977

Optical properties of ion beam textured metals

Copper, silicon, aluminum, titanium and 316 stainless steel were textured by 1000 eV xenon ions from an 8 cm diameter electron bombardment ion source. Simultaneously sputter-deposited tantalum was used to facilitate the development of the surface microstructure. Scanning electron microscopy of the ion textured surfaces revealed two types of microstructure. Copper, silicon, and aluminum developed a cone structure with an average peak-to-peak distance ranging from 1 micron for silicon to 6 microns for aluminum. Titanium and 316 stainless steel developed a serpentine ridge structure. The average peak-to-peak distance for both of these materials was 0.5 micron. Spectral reflectance was measured using an integrating sphere and a holraum reflectometer. Total reflectance for air mass 0 and 2, solar absorptance and total emittance normalized for a 425 K black body were calculated from the reflectance measurements.

Hudson, W. R.↗
NASA NTRS1977

Optical properties of ion beam textured metals

Copper, silicon, aluminum, titanium and 316 stainless steel were textured by 1000 eV xenon ions from an 8-cm diameter electron bombardment ion source. Copper, silicon, and aluminum developed a cone structure with an average peak-to-peak distance ranging from 1 micron for silicon to 6 microns for aluminum. Titanium and 316 stainless steel developed a serpentine ridge structure. The average peak-to-peak distance for both of these materials was 0.5 micron. Total reflectance for air mass 0 and 2, solar absorptance, and total emittance, normalized for a 425 K black body were calculated from the reflectance measurements. All materials had solar absorptances between 0.93 (stainless steel) and 0.97 (silicon and aluminum). Total emittance values of 0.75, 0.80, and 0.85 for Si, Al, and Cu, respectively, resulted in a solar absorptance/total emittance ratio of approximately 1.2. Titanium and 316 stainless steel had values of 2.6 and 2.9, respectively, for this ratio.

Hudson, W. R.↗
NASA NTRS1981

Improved cell for water-vapor electrolysis

Continuous-flow electrolytic cells decompose water vapor in steam and room air into hydrogen and oxygen. Sintered iridium oxide catalytic anode coating yields dissociation rates hundredfold greater than those obtained using platinum black. Cell consists of two mirror-image cells, with dual cathode sandwiched between two anodes. Gas traverses serpentine channels within cell and is dissociated at anode. Oxygen mingles with gas stream, while hydrogen migrates through porous matrix and is liberated as gas at cathode.

Aylward, J. R.↗
NASA NTRS1979

Characterization of submicron matrix phyllosilicates from Murray and Nogoya carbonaceous chondrites

The combined techniques of high-resolution transmission electron microscopy and energy-dispersive X-ray analysis have been used to study dispersed, submicron phyllosilicates and the 'poorly characterized phase' of C2 matrix material. Morphologies and structure types observed are similar to terrestrial chrysotile. Distinctive morphologies and 7.3-A characteristic basal spacings combined with composition information rule out phyllosilicates other than serpentine group minerals as the predominant phyllosilicate material. The 'poorly characterized phase' is composed of chemically similar very fine-grained phyllosilicate and amorphous material. The observation of interstratified phyllosilicate material sheds additional doubt on compositional data which is not accompanied by structural data from the same particle.

Mckee, T. R.↗
NASA NTRS1979

High resolution transmission electron microscopy of two stony meteorites - Murchison and Kenna

Matrix material from the Murchison C2(M) carbonaceous chondrite and less than micrometer-size pyroxene inclusions in an olivine from the Kenna ureilite have been characterized using high resolution transmission electron microscopy. A diversity of textures and mineral associations, including serpentine-type and brucite-type mixed-layering, occur in the Murchison matrix. Such mixed layer structures are new types of layer silicate. Their presence in the matrix may prove to be genetically significant. The Kenna inclusions, formed at the olivine grain margins, are of two types: (1) a disordered orthopyroxene-clinopyroxene which may have inverted from protopyroxene and (2) a pigeonite with narrow anti-phase domains (80 A to 250 A) and boundaries parallel to (100).

Mackinnon, I. D. R.↗
NASA NTRS1980

Carbonaceous chondrites. II - Carbonaceous chondrite phyllosilicates and light element geochemistry as indicators of parent body processes and surface conditions

Petrographic analyses of CM matrices characterized four phyllosilicates in Murray and Murchison meteorites and Fe- and Mg-serpentines in Nogoya. All phyllosilicates and bulk matrices show enrichment of K relative to Na when compared with bulk meteorites; the loss of Na and some Cl, and the addition of H2O, CO2, and water-soluble organics during alteration indicates a partially open system. Synthesis of soluble organic materials may have occurred in CM matrices before aqueous alteration of the precursive phases. Nogoya was 95% altered and has a bulk C content of 5.2%, higher than any meteorite; also, it has the lowest measured C-13/C-12 ratio of any carbonaceous chondrite except for Karoonda.

Bunch, T. E.↗
NASA NTRS1981

Europa's petrological thermal history

A path of geophysical development which takes into account the petrological sequence is presented to describe the thermal evolution of Europa. On the basis of considerations of the likely temperature-pressure conditions in the Europa zone of the circumjovian nebula during the condensation of the satellite on the one hand and of the early thermal evolution on the other, it is argued that most of the water of Europa can be in the form of hydrated silicates in a thick convective boundary layer or throughout the body of the satellite. Such silicates would include the minerals chlorite and/or serpentine, and brucite, and could be maintained in hydrated states by solid state convection within the body. The model predicts that the ice layer on the surface of Europa is considerably thinner than the 150 km that had been estimated before the Voyager mission.

Ransford, G. A.↗
NASA NTRS1980

Mode and mechanisms of plateau uplifts

The mode and mechanisms of plateau uplifts are reported, based on discussions which occurred as part of a conference on plateau uplifts sponsored by the Inter-Union Commission on Geodynamics and the Lunar and Planetary Institute. Major plateaus and high plains of the world are discussed with emphasis on the Colorado Plateau, which possesses a shield-like crust 45 km thick and occupies most of eastern Utah and parts of Colorado, Arizona, and New Mexico. Several uplift mechanisms are described, including thermal expansion due to a deep mantle plume or hot spot, and hydration reactions such as serpentinization. It is concluded that uplifts are most commonly associated with either subduction and its direct effects, or deep-seated thermal disturbances.

Mcgetchin, T. R.↗
NASA NTRS1980

Structures and textures of the Murchison and Mighei carbonaceous chondrite matrices

High-resolution transmission electron microscopy has confirmed earlier observations that the character of the Murchison and Mighei fine-grained matrices is complex in mineralogy and texture. Layer structure minerals occur as planar laths, rounded grains or subhedral grains, and range in size from less than 100 A to about 1 micrometer. Serpentine-type and brucite-type structures predominate in the CM matrices. The occurrence of Povlen chrysolite and a vein of disordered mixed-layer and brucite-type material cutting a large lizardite-type grain suggests that at least some of the matrix materials were formed by alteration of preexisting material.

Mackinnon, I. D. R.↗
NASA NTRS1982

An estimate of atmospheric contamination of Allende coarse-grained inclusion 3529Z

Studies conducted by Zaikowski and Schaeffer (1979) have shown that minerals can take up rare gases when exposed to the atmosphere. Herzog et al. (1980) have conducted a laser microprobe study of coarse-grained Ca-Al-rich inclusions from the Allende meteorite. The amount of Ar-40 found in the Allende minerals is less than the equilibrium amount found for a synthetic serpentine by Zaikowski and Schaeffer. The present investigation has the objective to obtain a better estimate for the absorption of atmospheric argon by the minerals in Allende. Ar-38 was used as a tracer to investigate the diffusion of argon into a coarse-grained Ca-Al-rich inclusion from Allende. On the basis of the results obtained in the current investigation, it is believed that atmospheric contamination is not the cause for the extra argon and the above 4.55 G.y. ages in the case of the considered Allende inclusion.

Warasila, R.↗
NASA NTRS1982

The evolution of an impact-generated atmosphere

The minimum impact velocities and pressures required to form a primary H2O atmosphere during planetary accretion from chondritelike planetessimals are determined by means of shock wave and thermodynamic data for rock-forming and volatile-bearing minerals. Attenuation of impact-induced shock pressure is modelled to the extent that the amount of released water can be estimated as a function of projectile radius, impact velocity, weight fraction of target water, target porosity, and dehydration efficiency. The two primary processes considered are the impact release of water bound in such hydrous minerals as serpentine, and the subsequent reincorporation of free water by hydration of forsterite and enstatite. These processes are described in terms of model calculations for the accretion of the earth. It is concluded that the concept of dehydration efficiency is of dominant importance in determining the degree to which an accreting planet acquires an atmosphere during its formation.

Lange, M. A.↗