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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 1,171 records · Page 65
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Efficiency and economics of large scale hydrogen liquefaction

Liquid hydrogen is being considered as a substitute for conventional hydrocarbon-based fuels for future generations of commercial jet aircraft. Its acceptance will depend, in part, upon the technology and cost of liquefaction. The process and economic requirements for providing a sufficient quantity of liquid hydrogen to service a major airport are described. The design is supported by thermodynamic studies which determine the effect of process arrangement and operating parameters on the process efficiency and work of liquefaction.

Baker, C. R.↗
NASA NTRS1976

Histamine H2 receptor - Involvement in gastric ulceration

The involvement of the H1 and H2 receptors for histamine in the pathogenesis of gastric ulcers was investigated in rats. Metiamide, an H2 receptor antagonist, reliably reduced ulceration produced by stress alone or by a combination of stress and aspirin. In contrast, pyrilamine, which blocks only the H1 receptor, was without effect under these same conditions. The results support the hypothesis that histamine mediates both stress and stress plus aspirin induced ulceration by a mechanism involving the H2 receptor.

Brown, P. A.↗
NASA NTRS1978

Computational aerodynamics and the numerical aerodynamic simulation facility

Technical and economic reasons for accelerating the maturation of the discipline of computational aerodynamics include the cost of conducting the experiments required to provide the empirical data base for new aeronautical vehicles and the limitations in test facilities (Reynolds number, wall and support interferences, aeroelastic distortions, real-gas effects, etc.) for simulating the full-scale vehicle environment. General purpose computers do not have the necessary capability for the next stage of development. Solution of the three dimensional Reynolds averaged Naiver-Stokes equations in a short time to be practical for design purposes will require 40 times the power of current supercomputers. However, it is feasible to construct a special purpose processor that will meet these requirements to enhance the nation's aerodynamic design capability in the 1980's.

Peterson, V. L.↗
NASA NTRS1978

Quasi-microscope concept for planetary missions - Stereo

The quasi-microscope has been used for stereo pictures using a small aperture placed at the right and left over the entrance aperture. A 16-degree stereo view angle yields an enhanced stereo effect. When viewed upward through a transparent support, all grains come into focus. The technique may be used for determining mineral constituents on the basis of cleavage and fracture patterns, grain details, and surface slopes used in estimating single-particle albedo and the illumination of scattering profiles.

Burcher, E. E.↗
NASA NTRS1985

USSR Space Life Sciences Digest, issue 1

The first issue of the bimonthly digest of USSR Space Life Sciences is presented. Abstracts are included for 49 Soviet periodical articles in 19 areas of aerospace medicine and space biology, published in Russian during the first quarter of 1985. Translated introductions and table of contents for nine Russian books on topics related to NASA's life science concerns are presented. Areas covered include: botany, cardiovascular and respiratory systems, cybernetics and biomedical data processing, endocrinology, gastrointestinal system, genetics, group dynamics, habitability and environmental effects, health and medicine, hematology, immunology, life support systems, man machine systems, metabolism, musculoskeletal system, neurophysiology, perception, personnel selection, psychology, radiobiology, reproductive system, and space biology. This issue concentrates on aerospace medicine and space biology.

Hooke, L. R.↗
NASA NTRS1985

What determines the location of satellites and planets?

The discrete structural pattern in the distribution of the satellites and planets around their primaries has since its discovery been thought to hold the key to the origin and evolution of the solar system. Different attempts to rationalize this distribution are reviewed with emphasis on theories with foundation in verifiable physical processes. Foremost among these is the band structure theory, which relates the emplacement of interstellar dust and gas source material around the magnetized primarily to the critical velocity for ionization of the four major interstellar gas components. The uncertainties, that are inevitable in all reconstructions, are in this theory compensated by the support from precise manifestations of the 2/3 effect in the Saturnian ring system and in the asteroid belt, and by the reproduction of related phenomena in laboratory and space experiments.

Arrhenius, G.↗
NASA NTRS1985

USSR Space Life Sciences Digest, issue 3

This is the third issue of NASA's USSR Space Life Sciences Digest. Abstracts are included for 46 Soviet periodical articles in 20 areas of aerospace medicine and space biology and published in Russian during the second third of 1985. Selected articles are illustrated with figures and tables from the original. In addition, translated introductions and tables of contents for seven Russian books on six topics related to NASA's life science concerns are presented. Areas covered are adaptation, biospherics, body fluids, botany, cardiovascular and respiratory systems, endocrinology, exobiology, gravitational biology, habitability and environmental effects, health and medical treatment, immunology, life support systems, metabolism, microbiology, musculoskeletal system; neurophysiology, nutrition, perception, personnel selection, psychology, radiobiology, and space physiology. Two book reviews translated from the Russian are included and lists of additional relevant titles available in English with pertinent ordering information are given.

Hooke, L. R.↗
NASA NTRS1986

Role of seasonality in the evolution of climate during the last 100 million years

A simple climate model has been used to calculate the effect of past changes in the land-sea distribution on the seasonal cycle of temperatures during the last 100 million years. Modeled summer temperature decreased over Greenland by more than 10 C and over Antarctica by 5 to 8 C. For the last 80 million years, this thermal response is comparable in magnitude to estimated atmospheric carbon dioxide effects. Analysis of paleontological data provides some support for the proposed hypothesis that large changes due to seasonality may have sometimes resulted in an ice-free state due to high summer temperatures rather than year-round warmth. Such 'cool' nonglacials may have prevailed for as much as one-third of the last 100 million years.

Crowley, T. J.↗
NASA NTRS1987

Analysis of the vibratory excitation arising from spiral bevel gears

Tools required to understand and predict in terms of its underlying causes the vibratory excitation arising from meshing spiral bevel gears are developed. A generalized three component transmission error of meshing spiral bevel gears is defined. Equations are derived that yield the three components of the generalized transmission error in terms of deviations of tooth running surfaces from equispaced perfect spherical involute surfaces and tooth/gearbody elastic deformations arising from the three components of the generalized force transmitted by the meshing gears. A method for incorporating these equations into the equations of motion of a gear system is described. Equations are derived for the three components of the generalized force transmitted by the gears which are valid whenever inertial effects of the meshing gears and their supports are negligible. Bearing offsets from the positions occupied by the shaft centerlines of perfect spherical involute bevel gears and bearing/bearing support flexibilities enter into the computation of these forces.

Mark, William D.↗
NASA NTRS1987

Environmental control and life support systems analysis for a Space Station life sciences animal experiment

NASA's Langley and Goddard facilities have evaluated the effects of animal science experiments on the Space Station's Environmental Control and Life Support System (ECLSS) by means of computer-aided analysis, assuming an animal colony consisting of 96 rodents and eight squirrel monkeys. Thirteen ECLSS options were established for the reclamation of metabolic oxygen and waste water. Minimum cost and weight impacts on the ECLSS are found to accrue to the system's operation in off-nominal mode, using electrochemical CO2 removal and a static feed electrolyzer for O2 generation.

So, Kenneth T.↗
NASA NTRS1989

Analysis of vibrations of the National Transonic Facility model support system using a 3-D aeroelastic code

Vibrations of the National Transonic Facility model support system were analyzed using Computational Aeroelasticity Program-Transonic Small Disturbance, a three-dimensional transonic small disturbance code designed for aeroelastic analysis of complete aircraft. The model support system was represented as a tunnel-spanning flexible wing whose structural properties were obtained from measured responses. Aeroelastic transients were calculated and analyzed to obtain modal stability characteristics. The results show that there is tendency to exhibit a hump mode instability in one of the modes, and that there are other weakly damped or unstable modes. Most of the motion is in the aft section of the model support system. The close proximity of the solid wind-tunnel diffuser side walls to the model support system is shown to have adverse effects on its aeroelastic stability characteristics. When the effects of the wind-tunnel walls are modeled, the analyses indicate the presence of wind-tunnel resonance modes which are not present when free-air boundary conditions are used.

Whitlow, Woodrow, Jr.↗
NASA NTRS1988

Base reaction optimization of redundant manipulators for space applications

One of the problems associated with redundant manipulators which were proposed for space applications is that the reactions transmitted to the base of the manipulator as a result of the motion of the manipulator will cause undesirable effects on the dynamic behavior of the supporting space structure. It is therefore necessary to minimize the magnitudes of the forces and moments transmitted to the base. It is shown that kinematic redundancy can be used to solve the dynamic problem of minimizing the magnitude of the base reactions. The methodology described is applied to a four degree-of-freedom spatial manipulator with one redundant degree-of-freedom.

Chung, C. L.↗
NASA NTRS1991

Systems special investigation group overview

The Systems Special Investigation Group (SIG) has undertaken investigations in the four major engineering disciplines represented in the Long Duration Exposure Facility (LDEF) hardware: electrical, mechanical, thermal, and optical systems. Testing was planned for the highest possible level of assembly, and top level system tests for nearly all systems were performed at this time. To date, testing was performed on a mix of LDEF and individual experimenter systems. No electrical or mechanical system level failures attributed to the spaceflight environment have yet been detected. Some low cost electrical components were used successfully, although relays were a continuing problem. Mechanical galling was observed unexpectedly, but no evidence of cold welding was identified yet. A working index of observed systems anomalies was created and will be used to support the tracking and resolution of these effects. The LDEF hardware currently available to the Systems SIG includes most of the LDEF systems hardware, and some significant experimenter hardware as well. A series of work packages was developed for each of several subsystem types where further testing is of critical interest. The System SIG is distributing a regular newsletter to the greater LDEF community in order to maintain coherence in an investigation which is widely scattered both in subject matter and in geography. Circulation of this informal document has quadrupled in its first year.

Mason, James B.↗
NASA NTRS1990

NASA/ASEE Summer Faculty Fellowship Program, 1990, Volume 1

The 1990 Johnson Space Center (JSC) NASA/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program was conducted by the University of Houston-University Park and JSC. A compilation of the final reports on the research projects are presented. The topics covered include: the Space Station; the Space Shuttle; exobiology; cell biology; culture techniques; control systems design; laser induced fluorescence; spacecraft reliability analysis; reduced gravity; biotechnology; microgravity applications; regenerative life support systems; imaging techniques; cardiovascular system; physiological effects; extravehicular mobility units; mathematical models; bioreactors; computerized simulation; microgravity simulation; and dynamic structural analysis.

Bannerot, Richard B.↗
NASA NTRS1990

A perspective on CELSS control issues

Some issues of Closed Ecological Life Support System (CELSS) analysis and design are effectively addressed from a systems control perspective. CELSS system properties that may be elucidated using control theory in conjunction with mathematical and simulation modeling are enumerated. The approach that is being taken to the design of a control strategy for the Crop Growth Research Chamber (CGRC) and the relationship of that approach to CELSS plant growth unit subsystems control is described.

Blackwell, Ann L.↗
NASA NTRS1991

Renormalization group analysis of reduced magnetohydrodynamics with application to subgrid modeling

The technique for obtaining a subgrid model for Navier-Stokes turbulence, based on renormalization group analysis (RNG), is extended to the reduced magnetohydrodynamic (RMND) equations. It is shown that a RNG treatment of the Alfven turbulence supported by the RMHD equations leads to effective values of the viscosity and resistivity at large scales, k yields 0, dependent on the amplitude of turbulence. The effective viscosity and resistivity become independent of the molecular quantities when the RNG analysis is augmented by the Kolmogorov argument for energy cascade. A self-contained system of equations is derived for the range of scales, k = 0-K, where K = pi/Delta is the maximum wave number for a grid size Delta. Differential operators, whose coefficients depend upon the amplitudes of the large-scale quantities, represent in this system the resistive and viscous dissipation.

Longcope, D. W.↗
NASA NTRS1989

Ames life science telescience testbed evaluation

Eight surrogate spaceflight mission specialists participated in a real-time evaluation of remote coaching using the Ames Life Science Telescience Testbed facility. This facility consisted of three remotely located nodes: (1) a prototype Space Station glovebox; (2) a ground control station; and (3) a principal investigator's (PI) work area. The major objective of this project was to evaluate the effectiveness of telescience techniques and hardware to support three realistic remote coaching science procedures: plant seed germinator charging, plant sample acquisition and preservation, and remote plant observation with ground coaching. Each scenario was performed by a subject acting as flight mission specialist, interacting with a payload operations manager and a principal investigator expert. All three groups were physically isolated from each other yet linked by duplex audio and color video communication channels and networked computer workstations. Workload ratings were made by the flight and ground crewpersons immediately after completing their assigned tasks. Time to complete each scientific procedural step was recorded automatically. Two expert observers also made performance ratings and various error assessments. The results are presented and discussed.

Haines, Richard F.↗
NASA NTRS1991

Photographic Image Restoration

Deblurring capabilities would significantly improve the Flight Science Support Office's ability to monitor the effects of lift-off on the shuttle and landing on the orbiter. A deblurring program was written and implemented to extract information from blurred images containing a straight line or edge and to use that information to deblur the image. The program was successfully applied to an image blurred by improper focussing and two blurred by different amounts of blurring. In all cases, the reconstructed modulation transfer function not only had the same zero contours as the Fourier transform of the blurred image but the associated point spread function also had structure not easily described by simple parameterizations. The difficulties posed by the presence of noise in the blurred image necessitated special consideration. An amplitude modification technique was developed for the zero contours of the modulation transfer function at low to moderate frequencies and a smooth filter was used to suppress high frequency noise.

Hite, Gerald E.↗