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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Grain boundary mobility in anion doped MgO

Certain anions OH(-), F(-) and Gl(-) are shown to enhance grain growth in MgO. The magnitude of their effect decreases in the order in which the anions are listed and depends on their location (solid-solution, second phase) in the MgO lattice. As most anions exhibit relatively high vapor pressures at sintering temperatures, they retard densification and invariably promote residual porosity. The role of anions on grain growth rates was studied in relation to their effect on pore mobility and pore removal; the atomic process controlling the actual rates was determined from observed kinetics in conjunction with the microstructural features. With respect to controlling mechanisms, the effects of all anions are not the same. OH(-) and F(-) control behavior through creation of a defect structure and a grain boundary liquid phase while Cl(-) promotes matter transport within pores by evaporation-condensation. Studies on an additional anion, S to the minus 2nd power gave results which were no different from undoped MgO, possibly because of evaporative losses during hot pressing. Hence, the effect of sulphur is negligible or undetermined.

Kapadia, C. M.↗
NASA NTRS1972

Special nondestructive techniques for evaluating space shuttle surface insulation

NDT techniques have been developed for performing in-process evaluations for material variability and for process control. Several of these techniques show considerable promise for evaluating the reusable surface insulation during the operational phase of the shuttle. Considered are radiographic dosimetry, sonic velocity and modulus sounding, infrared coating evaluation, and beta backscatter monitoring of coating thickness.

Stinebring, R. C.↗
NASA NTRS1974

Hydrogen adsorption and diffusion, and subcritical-crack growth in high-strength steels and nickel base alloys

Coordinated studies of the kinetics of crack growth and of hydrogen adsorption and diffusion were initiated to develop information that is needed for a clearer determination of the rate controlling process and possible mechanism for hydrogen enhanced crack growth, and for estimating behavior over a range of temperatures and pressures. Inconel 718 alloy and 18Ni(200) maraging steel were selected for these studies. 18Ni(250) maraging steel, 316 stainless steel, and iron single crystal of (111) orientation were also included in the chemistry studies. Crack growth data on 18Ni(250) maraging steel from another program are included for comparison. No sustained-load crack growth was observed for the Inconel 718 alloy in gaseous hydrogen. Gaseous hydrogen assisted crack growth in the 18Ni maraging steels were characterized by K-independent (Stage 2) extension over a wide range of hydrogen pressures (86 to 2000 torr or 12 kN/m2 to 266 kN/m2) and test temperatures (-60 C to +100 C). The higher strength 18Ni(250) maraging steel was more susceptible than the lower strength 200 grade. A transition temperature was observed, above which crack growth rates became diminishingly small.

Wei, R. P.↗
NASA NTRS1972

Apollo 16 photographic standards documentation

The activities of the Photographic Technology Division, and particularly the Photo Science Office, the Precision Processing Laboratory, and the Motion Picture Laboratory, in connection with the scientific photography of the Apollo 16 manned space mission are documented. Described are the preflight activities involved in establishing a standard process for each of the flight films, the manned in which flight films were handled upon arrival at the Manned Spacecraft Center in Houston, Texas, and how the flight films were processed and duplicated. The tone reproduction method of duplication is described. The specific sensitometric and chemical process controls are not included.

Bourque, P. F.↗
NASA NTRS1972

Information management system: A summary discussion

An information management system is proposed for use in the space shuttle sortie, the modular space station, the tracking data relay satellite and associated ground support systems. Several different information management functions, including data acquisition, transfer, storage, processing, control and display are integrated in the system.

Sayers, R. S.↗
NASA NTRS1974

Rocket performance prediction technique

Attention is given to a semiempirical correlation technique based on the rational assumption that the turbulent mixing of reactants is the rate controlling process in combustors employing diffusion flames. Questions of performance computation are considered along with the flow conditions. Predictions of combustion efficiency are obtained with the aid of a standard finite-difference computational technique.-

Morgenthaler, J. H.↗
NASA NTRS1974

Human vs autonomous control of planetary roving vehicles

Supervisory or semiautonomous control has some compelling advantages over step-by-step human command and verification for the operation of roving vehicles on remote planetary surfaces. There are also disadvantages in relation to the complex system that must be mobilized and the chain of events that must be enacted to conduct a mission. Which of the two control methods is better on technical grounds may not be the deciding factor in its acceptance or rejection. Some of the issues that affect changes in spacecraft design and operation are summarized. To accelerate the movement toward more autonomous machines, it will be necessary to understand and to address the problems that such autonomy will create for other elements of the control system and for the control process.

Whitney, W. M.↗
NASA NTRS1975

A distributed data base management system

Major system design features of a distributed data management system for the NASA Deep Space Network (DSN) designed for continuous two-way deep space communications are described. The reasons for which the distributed data base utilizing third-generation minicomputers is selected as the optimum approach for the DSN are threefold: (1) with a distributed master data base, valid data is available in real-time to support DSN management activities at each location; (2) data base integrity is the responsibility of local management; and (3) the data acquisition/distribution and processing power of a third-generation computer enables the computer to function successfully as a data handler or as an on-line process controller. The concept of the distributed data base is discussed along with the software, data base integrity, and hardware used. The data analysis/update constraint is examined.

Bryan, A. I.↗
NASA NTRS1976

Growing crystals from eutectic melts

Inverted Bridgman Method yields crystals of higher homogeneity and better structure than those grown by ordinary Bridgman method. Process controls thermotransport by holding molten alloy in known temperature for known period of time. Rapid cooling quenches in state of segregation. Method is applicable to other eutectiferous systems where thermotransport is appreciable.

Bhat, B. N.↗
NASA NTRS1976

Relative humidity from psychrometric data

Analytical equation for computing relative humidity as function of wet bulb temperature, dry bulb temperature, and atmospheric pressure is suitable for use with calculator or computer. Analytical expressions may be useful for chemical process control systems and building environmental control systems.

Putnam, T. W.↗
NASA NTRS1976

Interconnnect and bonding technologies for large flexible solar arrays

Thermocompression bonding and conductive adhesive bonding are developed and evaluated as alternate methods of joining solar cells to their interconnect assemblies. Bonding materials and process controls applicable to fabrication of large, flexible substrate solar cell arrays are studied. The primary potential use of the techniques developed is on the solar array developed by NASA/MSFC and LMSC for solar electric propulsion (SEP) and shuttle payload applications. This array is made up of flexible panels approximately 0.7 by 3.4 meters. It is required to operate in space between 0.3 and 6 AU for 5 years with limited degradation. Materials selected must be capable of enduring this space environment, including outgassing and radiation.

Source record↗
NASA NTRS1976

Powder metallurgy processing of high strength turbine disk alloys

Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

Evans, D. J.↗
NASA NTRS1976

Mercury - Spectral reflectance measurements /0.33-1.06 microns/ 1974/75

The spectral reflectance (0.32-1.06 microns) of Mercury was measured during two elongations, September-October 1974 and March 1975. The spectra are much improved over the previously available measurements. The reflectance increases almost linearly with wavelength, and no electronic transition absorption bands are evident to the precision of the data. The new spectra agree very well with the reflectance of mature lunar mare and upland soils and are not similar to those of any other observed solar system object. This suggests that the surface materials and the weathering processes controlling their optical properties are similar for both the moon and Mercury. Differences between the spectra for the two-observation periods may indicate differences in the average composition for the different regions of Mercury observed.

Vilas, F.↗
NASA NTRS1977

Time-division multiplexer uses digital gates

Device eliminates errors caused by analog gates in multiplexing a large number of channels at high frequency. System was designed for use in aerospace work to multiplex signals for monitoring such variables as fuel consumption, pressure, temperature, strain, and stress. Circuit may be useful in monitoring variables in process control and medicine as well.

Myers, C. E.↗
NASA NTRS1976

Photographic consulting services to the Earth Resources program

The recommendations, procedures, and techniques are summarized which provided by the Kodak Apparatus Division to the Ames Research Center to support the Earth Resources Aircraft Program at that facility. Recommendations, procedures, and calibration data are included for sensitometry, densitometry, laboratory cleanliness, and determination of camera exposure. Additional comments are made regarding process control procedures and general laboratory operations.

Source record↗
NASA NTRS1978

Noise tolerant computer link

Inexpensive computer-to-computer link facilitates data communication in electrically noisy environments. Link can connect process-control computers while reducing errors from electrical noise of manufacturing operations.

Sievers, M. W.↗