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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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Practical computational techniques developed. Report discusses practical considerations of calculation of three-dimensional radiative transfer. Extension of earlier theoretical developments described in "Calculating Atmospheric Effects in Satellite Imagery" NPO-16373.
Individual current feeds enable better uniformity and flexible control. Separate contacts for lasers in array enable control of output radiation pattern and compensation of manufacturing nonuniformities among lasers. Concept of separate current control described for two-laser array in "Semiconductor Laser Phased Array" (NPO-15963).
Proposed hot-dipping process prepares materials well suited to serve as substrates for high-temperature superconductors. Makes it possible to produce substrates combining properties needed for given application, such as flexibility, strength, long grains, and <001> crystal orientation. Properties favor growth of superconductive films carrying high current and fabricated in variety of useful shapes. Used in making solar cells, described in "Hot-Dipped Metal Films as Epitaxial Substrates" (NPO-15904).
Report discusses performance of automatic frequency-control (AFC) subsystem of differential minimum-shift-keying receiver described in "DMSK Receiver for Moblile/Satellite Service," NPO-16659. Describes efforts to quantify behavior of system during acquisition of carrier signal; including theoretical analysis leading to numerical simulation, and measurements of performance of receiving equipment.
Improved algorithm reduces complexity of calculations that must precede design of Massey-Omura finite-field normal-basis multipliers, used in error-correcting-code equipment and cryptographic devices. Algorithm represents an extension of development reported in "Algorithm To Design Finite-Field Normal-Basis Multipliers" (NPO-17109), NASA Tech Briefs, Vol. 12, No. 5, page 82.
Proposed high-performance spatial light modulator consists of multiple-quantum-well, strain-layer superlattice similar to one described in accompanying article, "Strain-Layer-Superlattice Light Modulator" (NPO-16915). Device differs from other one, operates in transmission rather than in resonant reflection and therefore includes only one stack of GaAs/InAs layers having total thickness less than penetration depth (1 to 2 micrometer) of optical modulating signal. Alternating, semitransparent semiconductor layers contain space-charge barriers forming quantum wells. Modulating light (with photon energy greater than semiconductor band gap) induces photovoltaic action, which affects transmission of modulated light (having photon energy less than band gap).
Symmetrical tangential streams control flow of radial primary streams. Vortex generator uses small secondary stream of fluid to control normally-larger primary stream. Improved version of vortex generator described in "Variable Control Port for Fluidic Control Device," (NPO-16603). Secondary, or control, flows entering tangentially through diametrically opposite ports set up swirling motion restraining primary flow. Pressure of secondary fluid in relation to primary fluid controlling factor. Like valve, vortex generator varies rate of flow of primary fluid from maximum value down to zero. When properly designed, requires low pressure differential between primary and secondary streams and expends relatively small amount of secondary fluid.
Sensitivity of electronic moisture sensor to low levels of moisture increased by new electrode configuration. Moisture-sensing circuit described in "Low-Cost Humidity Sensor" (NPO-16544). New twisted pair of wires takes place of flat-plate capacitor in circuit. Configuration allows for thermal expansion and contraction of polymer while maintaining nearly constant area of contact between polymer and wires.
Report presents theoretical study of effects of turbulence on ignition of drops of single-component liquid fuel. Closely related to article, "Turbulence and Evaporation in Clusters of Drops" (NPO-17323). Uses theoretical model for evaporation and model for ignition developed previously. Radial velocity, va, of gas at surface of sphere of influence taken as algebraic combination of rate of evaporation and speed with which radius changes. Weighting factors of algebraic combination are such that in dilute spray, all new vapor coming from drops trapped in cluster, whereas in dense spray where evaporation strong, maximum new vapor escapes to ambient.
Proposed insulated honeycomb structure similar to reinforced honeycomb structure described in NPO-17538. Panels of insulated honeycomb used to make supports for solar-energy collectors and radar antennas.
Report presents results of continuing theoretical research in behaviors of sprayed liquid fuels at temperatures characteristic of furnaces. Two earlier papers arising from this investigation described in "Evaporation of Dense Fuel Sprays" (NPO-16954).
Performance in presence of fades improved. Report amplifies and extends subject matter of "Performance of Fixed-Lag Phase-Smoothing Algorithms" (NPO-17202). Fixed-lag smoothers also used to mitigate effects of short, deep fades, including multipath effects, in mobile or fixed terrestrial receivers of frequency- or phase-modulated signals.
Spaceborne synthetic-aperture-radar (SAR) images useful for mapping of planets and investigations in Earth sciences. Produces multiframe mosaic by combining images along ground track, in adjacent cross-track swaths, or in ascending and descending passes. Images registered with geocoded maps such as ones produced by MAPJTC (NPO-17718), required as input. Minimal intervention by operator required. MOSK implemented on DEC VAX 11/785 computer running VMS 4.5. Most subroutines in FORTRAN, but three in MAXL and one in APAL.
Simple treatment increases and stabilizes quantum efficiency of charge-coupled-device photodetector illuminated on back surface at wavelengths less than 4,500 Angstrom. Must be biased in strong accumulation mode. Physical principle of enhancement explained more fully in "Metal Film Increases CCD Output" (NPO-16815). Useful for imaging at wavelengths from ultraviolet to blue; for example, in astronomical observations.
Usability extended to different environments. Application of thin film of iridium to back surface of back-surface-illuminated charge-coupled device expected to increase and stabilize quantum efficiency at wavelengths less than 4,500 Angstrom. Enhances quantum efficiency according to principle discussed in "Metal Film Increases CCD Output" (NPO-16815). Does not react with hydrogen, so device need not be kept in oxygen: Advantage where high absorption of ultraviolet light by oxygen undesirable; for example, when device used to make astronomical observations from high altitudes.
Quantum efficiency of back-surface-illuminated charge-coupled device (CCD) increased by coating back surface with thin layer of PtSi or IrSi on thin layer of SiO2. In its interaction with positively-doped bulk Si of CCD, silicide/oxide layer forms Schottky barrier that repels electrons, promoting accumulation of photogenerated charge carriers in front-side CCD potential wells. Physical principle responsible for improvement explained in "Metal Film Increases CCD Output" (NPO-16815).
Proposed mechanism retains protective shield until no longer needed, then releases shield and guides it away for safe ejection from vehicle (spacecraft, according to original concept). Intended for use with shield like one described in article "Crash-Resistant Shield" (NPO-17616). Mechanism for guided release separates shield from base and from supporting truss on command. Band holding shield on base released by explosive separator.
Four-wheel suspension system uses simple system of levers with no compliant components to provide three-point suspension of chassis of vehicle while maintaining four-point contact with uneven terrain. Provides stability against tipping of four-point rectangular base, without rocking contact to which rigid four-wheel frame susceptible. Similar to six-wheel suspension system described in "Articulated Suspension Without Springs" (NPO-17354).