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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 127 records · Page 7
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NASA NTRS1972

The use of linear programming techniques to design optimal digital filters for pulse shaping and channel equalization

A time domain technique is developed to design finite-duration impulse response digital filters using linear programming. Two related applications of this technique in data transmission systems are considered. The first is the design of pulse shaping digital filters to generate or detect signaling waveforms transmitted over bandlimited channels that are assumed to have ideal low pass or bandpass characteristics. The second is the design of digital filters to be used as preset equalizers in cascade with channels that have known impulse response characteristics. Example designs are presented which illustrate that excellent waveforms can be generated with frequency-sampling filters and the ease with which digital transversal filters can be designed for preset equalization.

Houts, R. C.↗
NASA NTRS1972

Microwave signatures of first-year and multiyear sea ice

A combination of remote sensing from an aircraft and simultaneous surface measurements have confirmed the feasibility of identifying old and new sea ice according to its emission of thermal radiation at wavelengths between 0.3 and 3 cm. Emissivity of first-year thick ice with a surface temperature of about 260 K is 0.95 or greater for wavelengths between 0.81 and 11 cm; the emissivity of multiyear ice is 0.8 at 0.81 cm and 0.95 at 11 cm, increasing monotonically in this wave length interval. The ease with which multiyear ice can be distinguished from first-year ice using a passive microwave radiometer is demonstrated by comparing mosaics prepared both from photographs and images of 1.55 cm radiation.

Gloersen, P.↗
NASA NTRS1972

Hand tools: A compilation

A selection of new hand tools, modifications of existing tools, and techniques developed in the course of NASA research and development projects are presented. The items are presented in two sections: tools for cable and connector applications, and tools for welding applications. Safety is emphasized, together with ease of operation and use in restricted areas or hazardous environments. The discussions are directed primarily toward the technician engaged in assembly or maintenance of mechanical or electrical equipment.

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NASA NTRS1972

Gamma ray satellite to be launched from Africa

The announcement is presented of the launch of NASA's Small Astronomy Satellite B (SAS-B) on 2 Nov. 1972, to study gamma rays. The launch is to be from the Italian-operated San Marco Equatorial Range in the Indian Ocean for ease in acquiring an equatorial orbit. The spacecraft systems described include: stabilization and control, communication, and spark chamber gamma ray telescope. The results of Uhuru (Explorer 42) are also presented.

Allaway, H. G.↗
NASA NTRS1971

The use of the transmission windows of the Fabry-Perot interferometer in the detection of Raman scattered radiation from atmospheric gases.

Demonstration that the use of the Fabry-Perot interferometer as a filter with transmission windows occurring at regular intervals in wave numbers provides a highly sensitive method for detection of atmospheric gases using their rotational Raman spectra excited by a suitable laser. Some of the operating advantages include signal gains of several orders of magnitude, a simple direct interpretation of the results in terms of the density and types of the gaseous constituents, size and weight reductions from conventional apparatus, ease of operation, and relative freedom from interference from other molecules in the scattering volume. This method is compared with the techniques that have been discussed in the literature by other workers in the field.

Smith, W. H.↗
NASA NTRS1971

Remote sensing of some sedimentary rocks.

Sedimentary rocks including varying sized clastics and carbonates were overflown by aircraft between 1966 and 1971 producing data in the ultraviolet to microwave regions of the electromagnetic spectrum. This paper reports that multispectral analysis increases the ease and rapidity of discrimination of rock types having subtle differences in physical characteristics, but fails to enhance and may degrade distinctions where physical characteristics are significantly different. Brief resumes of color and color IR photographic data are presented. Thermal infrared is found to be useful in the mapping of rock units, but limitations such as moisture variation, soil cover, and vegetation may exceed in one formation the distinction between differing lithologies. A brief review of previously published SLAR data is included for completeness. Remote sensing techniques should reduce field geological effort by as much as 50%.

Brennan, P. A.↗
NASA NTRS1972

Deformation, recrystallization, strength, and fracture of press-forged ceramic crystals.

Sapphire and ruby were very difficult to press-forge because they deformed without cracking only in a limited temperature range before they melted. Spinel crystals were somewhat easier and MgO, CaO, and TiC crystals much easier to forge. The degree of recrystallization that occurred during forging (which was related to the ease and type of slip intersections) varied from essentially zero in Al2O3 to complete (i.e., random polycrystalline bodies were produced) in CaO. Forging of bi- and polycrystalline bodies produced incoherent bodies as a result of grain-boundary sliding. Strengths of the forged crystals were comparable to those of dense polycrystalline bodies of similar grain size. However, forged and recrystallized CaO crystals were ductile at lower temperatures than dense hot-pressed CaO. This behavior is attributed to reduced grain-boundary impurities and porosity. Fracture origins could be located, indicating that fracture in the CaO occurs internally as a result of surface work hardening caused by machining.-

Rice, R. W.↗
NASA NTRS1972

Active controls - Changing the rules of structural design.

Approaches making use of aerodynamic surfaces in combination with advanced flight computers, and electrohydraulic systems could be used to improve economics of commercial aircraft operation, smooth the passenger's ride, reduce terminal-area noise, and ease terminal-area congestion. This emerging technology is becoming known as active controls technology. Maximum benefits from active controls can come only by considering controls early in the design cycle. Active controls can save weight by reducing the structural strength necessary. Some of the technical benefits of active controls would increase return on investment and raise profits. Details of a proposed active controls research program are discussed.

Hood, R. V.↗
NASA NTRS1972

A compact MOST model for design analysis.

A generalized extension of Kotani's (1970) design analysis model is described that is accurate for a majority of modern MOST structures. The generalized model retains much of the ease of parameter measurement characteristics of the original and enough physical correspondence to accurately represent important steady-state environmental effects, such as those caused by radiation.

Kalinowski, J. J.↗
NASA NTRS1972

The use of models in structural testing.

The design, construction and instrumentation of plastic model shells used in elastic stability studies is discussed. The work demonstrates that specimens made of such materials are of great value in parametric studies because of their ease of manufacture and the simplicity of modification. Additionally, it is shown that they are most useful in the development of nondestructive test techniques. The paper indicates how deformation measurements made at low load levels can be used to accurately predict critical conditions.

Horton, W. H.↗
NASA NTRS1973

Mass flow controller for gaseous propellants

Gaseous propellants exhibit large variations in pressure and temperature and hence in fuel delivery. All-mechanical, mass flow controller which compensates for these variations has been developed to maintain constant fuel rate of gas. Further work is necessary to ease inlet pressure limitation.

Source record↗
NASA NTRS1973

Tool for installing or extracting small bulbs in limited-access spaces

Installing and extracting component of tool is plastic tubing with inside diameter which provides snug fit over bulb. Other components, which provide sturdiness and ease of operation, consist of metal tube, with collar near one end, and plunger, with knob on one end and Teflon tip on the other.

Snyder, E. B.↗
NASA NTRS1972

Modular thermal analyzer routine, volume 1

The Modular Thermal Analyzer Routine (MOTAR) is a general thermal analysis routine with strong capabilities for performing thermal analysis of systems containing flowing fluids, fluid system controls (valves, heat exchangers, etc.), life support systems, and thermal radiation situations. Its modular organization permits the analysis of a very wide range of thermal problems for simple problems containing a few conduction nodes to those containing complicated flow and radiation analysis with each problem type being analyzed with peak computational efficiency and maximum ease of use. The organization and programming methods applied to MOTAR achieved a high degree of computer utilization efficiency in terms of computer execution time and storage space required for a given problem. The computer time required to perform a given problem on MOTAR is approximately 40 to 50 percent that required for the currently existing widely used routines. The computer storage requirement for MOTAR is approximately 25 percent more than the most commonly used routines for the most simple problems but the data storage techniques for the more complicated options should save a considerable amount of space.

Oren, J. A.↗
NASA NTRS1972

Aerodynamic study of a turbine designed for a small low-cost turbofan engine

An eight inch mean diameter two-stage turbine was experimentally investigated over a range of speeds from 0 to 110 percent of equivalent design speed and over a range of pressure ratios from 2.2 to 4.2. The principal results indicated that the performance level was substantially higher than that assumed in the design. As part of the program to reduce manufacturing costs, the first stage blading was reduced in thickness for ease in coining. Tests of the modified blades indicated that the aerodynamic performance of a stator or rotor blade with a large amount of reaction was effected very little by a significant change of the pressure surface.

Kofskey, M. G.↗
NASA NTRS1972

Analytical design and performance studies of nuclear furnace tests of small nuclear light bulb models

Analytical studies were continued to identify the design and performance characteristics of a small-scale model of a nuclear light bulb unit cell suitable for testing in a nuclear furnace reactor. Emphasis was placed on calculating performance characteristics based on detailed radiant heat transfer analyses, on designing the test assembly for ease of insertion, connection, and withdrawal at the reactor test cell, and on determining instrumentation and test effluent handling requirements. In addition, a review of candidate test reactors for future nuclear light bulb in-reactor tests was conducted.

Latham, T. S.↗
NASA NTRS1972

Analysis of space tug operating techniques. Volume 2: Study results

The design requirements for space tug systems and cost analysis of the refurbishment phases are discussed. The vehicle is an integral propulsion stage using liquid hydrogen and liquid oxygen as propellants and is capable of operating either as a fully or a partially autonomous vehicle. Structural features are an integral liquid hydrogen tank, a liquid oxygen tank, a meteoroid shield, an aft conical docking and structural support ring, and a staged combustion main engine. The vehicle is constructed of major modules for ease of maintenance. Line drawings and block diagrams are included to explain the maintenance requirements for the subsystems.

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NASA NTRS1973

Ecological effects of strip mining in Ohio

The author has identified the following significant results. One result significant as a practical application and for cost benefit analysis is the relative ease with which ERTS-1 will monitor new and unclaimed stripping activities in Southeastern Ohio and in all of Appalachia. Band 5 resolution appears to be better than the often reported 80 meters. The strip mines stand out well enough to be easily identified without other graphic aids. Standing water within the strip mined area stands out in either bands 6 or 7. Areas of several acres are visible. Significant increases in surface extent of water of stripped areas should be detectable on a comparative basis. The degree of reclamation is observable in the imagery in rather gross percentage steps and for areas larger than the bare earth sizes in the table. The gradation in tones in the different bands indicates that probability density imagery using the four bands in CCT data (and statistical processing) is likely to separate degrees of vegetative reclamation.

Chase, P. E.↗
NASA NTRS1972

Electromagnetic radiation screening of semiconductor devices for long life applications

A review is presented of the mechanism of interaction of electromagnetic radiation in various spectral ranges, with various semiconductor device defects. Previous work conducted in this area was analyzed as to its pertinence to the current problem. The task was studied of implementing electromagnetic screening methods in the wavelength region determined to be most effective. Both scanning and flooding type stimulation techniques are discussed. While the scanning technique offers a considerably higher yield of useful information, a preliminary investigation utilizing the flooding approach is first recommended because of the ease of implementation, lower cost and ability to provide go-no-go information in semiconductor screening.

Hall, T. C.↗