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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Two-dimensional radiant energy array computers and computing devices

Two dimensional digital computers and computer devices operate in parallel on rectangular arrays of digital radiant energy optical signal elements which are arranged in ordered rows and columns. Logic gate devices receive two input arrays and provide an output array having digital states dependent only on the digital states of the signal elements of the two input arrays at corresponding row and column positions. The logic devices include an array of photoconductors responsive to at least one of the input arrays for either selectively accelerating electrons to a phosphor output surface, applying potentials to an electroluminescent output layer, exciting an array of discrete radiant energy sources, or exciting a liquid crystal to influence crystal transparency or reflectivity.

Schaefer, D. H.↗
NASA NTRS1977

Conceptual design of an on-board optical processor with components

The specification of components for a spacecraft on-board optical processor was investigated. A space oriented application of optical data processing and the investigation of certain aspects of optical correlators were examined. The investigation confirmed that real-time optical processing has made significant advances over the past few years, but that there are still critical components which will require further development for use in an on-board optical processor. The devices evaluated were the coherent light valve, the readout optical modulator, the liquid crystal modulator, and the image forming light modulator.

Walsh, J. R.↗
NASA NTRS1976

Waves in active and passive periodic structures - A review

The theory and recent applications of waves in periodic structures are reviewed. Both the Floquet and coupled waves approach are analyzed in some detail. The theoretical part of the paper includes wave propagation in unbounded and bounded active or passive periodic media, wave scattering from periodic boundaries, source radiation (dipole, Cerenkov, transition, and Smith-Purcell) in periodic media, and pulse transmission through a periodic slab. The applications part covers the recent development in a variety of fields: distributed feedback oscillators, filters, mode converters, couplers, second-harmonic generators, deflectors, modulators, and transducers in the fields of integrated optics and integrated surface acoustics. Work on insect compound eyes, mechanical structures, ocean waves, pulse compressions, temperature waves, and cholesteric liquid crystals, and particles interaction with crystals is briefly reviewed, especially in the case of zeolite crystals and superlattices. Recent advances in fabrication techniques for very fine gratings are also covered.

Elachi, C.↗
NASA NTRS1979

Hybrid LCD driver

Display driver for hand-held signs monitor can be configured to operate either 4 digit or, by paralleling four drivers, to operate 16 digit liquid crystal display (LCD).

Rinard, G. A.↗
NASA NTRS1978

Coming cockpit avionics

Digital and display technology combined with human factors research under development today are expected to become operational in the commercial aircraft of the 1990s. Attention is given to reducing the pilot's workload and increasing aircraft reliability through integration of electronic systems, and through multi-mode displays. Recent advances in display technology are outlined, including electroluminescent panels, beam penetration color CRTs, liquid crystal modules, and LED panels and indicators. Research cockpits are described in terms of simplification of aircraft systems evaluation and control.

Mciver, D.↗
NASA NTRS1975

Origin of the Station 7 boulder - A note

The origin of the matrix types from the Apollo 17 Station 7 boulder is considered along with the origin of boulder material from Station 2, Boulder 1, and 73215. It is pointed out that the formation of the matrix rocks in this boulder and in the other Apollo 17 boulders in a single impact event is consistent with the isotopic evidence, ages, major-element chemistry, large ion lithophile (LIL) trace-element abundances, and textures. It had been suggested by Winzer et al. (1974), based on calculations from crystal-liquid partition coefficients for LIL trace elements, that target rocks corresponding in trace-element composition to the matrix types could have been produced by partial fusion of rocks similar to 77215. Using the same type of calculation, liquids quite similar in trace-element composition to the Station 7 boulder matrix types can be produced.

Winzer, S. R.↗
NASA NTRS1978

Multiphase dispersions by crystallization processing

The interaction between second-phase particles and crystal-liquid interfaces in the solidification process has been studied in ground-based experiments and experiments under microgravity conditions. An analysis of these data with a view toward the solidification processing of composite materials reveals a pronounced difference between high entropy of fusion and low entropy of fusion matrix materials, as well as a pronounced effect of differences in the thermal conductivity of particles and liquid on the behavior of materials. Effects of liquid viscosity surface topography of the particles, particle chemistry, and overall particle shape examined.

Uhlmann, D. R.↗
NASA NTRS1978

Development of an optical parallel logic device and a half-adder circuit for digital optical processing

The paper describes the fabrication and operation of an optical parallel logic (OPAL) device which performs Boolean algebraic operations on binary images. Several logic operations on two input binary images were demonstrated using an 8 x 8 device with a CdS photoconductor and a twisted nematic liquid crystal. Two such OPAL devices can be interconnected to form a half-adder circuit which is one of the essential components of a CPU in a digital signal processor.

Athale, R. A.↗
NASA NTRS1980

Flow visualization techniques in the Airborne Laser Laboratory program

A turret/fairing assembly for laser applications was designed and tested. Wind tunnel testing was conducted using flow visualization techniques. The techniques used have included the methods of tufting, encapsulated liquid crystals, oil flow, sublimation and schlieren and shadowgraph photography. The results were directly applied to the design of fairing shapes for minimum drag and reduced turret buffet. In addition, the results are of primary importance to the study of light propagation paths in the near flow field of the turret cavity. Results indicate that the flow in the vicinity of the turret is an important factor for consideration in the design of suitable turret/fairing or aero-optic assemblies.

Walterick, R. E.↗
NASA NTRS1980

The GSFC Mark-2 three band hand-held radiometer

A self-contained, portable, hand-radiometer designed for field usage was constructed and tested. The device, consisting of a hand-held probe containing three sensors and a strap supported electronic module, weighs 4 1/2 kilograms. It is powered by flashlight and transistor radio batteries, utilizes two silicon and one lead sulfide detectors, has three liquid crystal displays, sample and hold radiometric sampling, and its spectral configuration corresponds to LANDSAT-D's thematic mapper bands. The device was designed to support thematic mapper ground-truth data collection efforts and to facilitate 'in situ' ground-based remote sensing studies of natural materials. Prototype instruments were extensively tested under laboratory and field conditions with excellent results.

Tucker, C. J.↗
NASA NTRS1979

Apollo 12 feldspathic basalts 12031, 12038 and 12072 - Petrology, comparison and interpretations

The paper presents the petrology of Apollo 12 feldspathic basalts. Modal and chemical data indicate that basalts 12072, 12038, and 12031 cannot be related to the other Apollo rock types; 12072 contains phenocrysts of olivine and pigeonite, 12038 is a multiply saturated equigranular basalt, and 12031 is a coarse-grained rock with granular to graphic intergrowths of pyroxene and plagioclase. The bulk compositions indicate that these basalts could not have been derived from the Apollo 12 olivine or ilmenite basalts by crystal-liquid fractionation, and their petrologic similarities suggest that they were produced in the same or similar source regions.

Beaty, D. W.↗
NASA NTRS1979

Basaltic volcanism - The importance of planet size

The volumetrically abundant basalts on the earth, its moon, and the eucrite parent planet all have chemical compositions that are controlled to a large extent by dry, low-pressure, crystal-liquid equilibria. Since this generalization is valid for these three planetary bodies, we infer that it may also apply to the other unsampled terrestrial planets. Other characteristics of basaltic volcanism show variations which appear to be related to planet size: the eruption temperatures, degrees of fractionation, and chemical variety of basalts and the endurance of basaltic volcanism all increase with planet size. Although the processes responsible for chemical differences between basalt suites are known, no simple systematization of the chemical differences between basalts from planet to planet has emerged.

Walker, D.↗
NASA NTRS1979

Electronic recording of holograms with applications to holographic displays

The paper describes an electronic heterodyne recording which uses electrooptic modulation to introduce a sinusoidal phase shift between the object and reference wave. The resulting temporally modulated holographic interference pattern is scanned by a commercial image dissector camera, and the rejection of the self-interference terms is accomplished by heterodyne detection at the camera output. The electrical signal representing this processed hologram can then be used to modify the properties of a liquid crystal light valve or a similar device. Such display devices transform the displayed interference pattern into a phase modulated wave front rendering a three-dimensional image.

Claspy, P. C.↗
NASA NTRS1983

Improved Photosensor for Light Valves

Processing changes improve performance of liquid-crystal light valve for displaying projection TV images. New approach monitors performance of finished light valves for given changes in CdS process and experimentally to optimize process for good sensitivity and low negative memory.

Koda, N. J.↗
NASA NTRS1981

High speed techniques for synthetic aperture radar image formation

One possible approach to high speed synthetic aperture radar signal reconstruction involves the utilization of two dimensional real time spatial light modulators as recyclable replacements for photographic film in the input transducer plane of a modified synthetic aperture radar (SAR) coherent optical processor. Leading candidate spatial light modulators include modified Pockels readout optical modulators (PROM), charge coupled devices (CCD) addressed liquid crystal light valves, and CCD addressed membrane light modulators. The fundamental physical limitations affecting SAR processor performance characteristics of such real time devices are under investigation. Current research on PROM is focused on the effects of device operatonal mode, device constitutive parameters, electro-optic crystal orientation, writing wavelength, frame rate/data overwrite/presuming, erasure completeness, and image retention on the overall quality of SAR image formation. Both modulated laser scanning and intensified CRT temporal to spatial input approaches are being examined.

Psaltis, D.↗
NASA NTRS1982

The state of the art of conventional flow visualization techniques for wind tunnel testing

Conventional wind tunnel flow visualization techniques which consist of surface flow methods, tracers, and optical methods are presented. Different surface flow methods are outlined: (1) liquid films (oil and fluorescent dye and UV lighting, renewable film via porous dispenser in model, volatile carrier fluid, cryogenic colored oil dots, oil film interferometry); (2) reactive surface treatment (reactive gas injection, reversible dye); (3) transition and heat transfer detectors (evaporation, sublimation, liquid crystals, phase change paints, IR thermography); and (4) tufts (fluorescent mini tufts, cryogenic suitability). Other methods are smoke wire techniques, vapor screens, and optical methods.

Settles, G. S.↗
NASA NTRS1983

Mineralogy and chemistry of planets and meteorites

The data collection and the interpretation with respect to the mineralogy of meteoritic and terrestrial samples are summarized. The key conclusion is that the Moon underwent a series of melting episodes with complex crystal-liquid differentiation. It was not possible to determine whether the Moon melted completely or only partially. The stage is now set for a systematical geochemical and geophysical survey of the Moon. Emphasis was moved to meteorites in order to sort out their interrelationships from the viewpoint of mineral chemistry. Several parent bodies are needed for the achondrites with different chemical properties. Exploration of Mars is required to test ideas based on the possible assignment of shergottites, nakhlites and chassignite to this planet. Early rocks on the Earth have properties consistent with a heavy bombardment and strong volcanic activity prior to 4 billion years ago.

Source record↗
NASA NTRS1983

Recording and reproduction of microwave holograms using a scanning procedure and their subsequent optical processing

Intensity distributions in nonoptical wave fields can be visualized and stored on photosensitive material. In the case of microwaves, temperature effects can be utilized with the aid of liquid crystals to visualize intensity distributions. Particular advantages for the study of intensity distributions in microwave fields presents a scanning procedure in which a microcomputer is employed for the control of a probe and the storage of the measured data. The present investigation is concerned with the employment of such a scanning procedure for the recording and the reproduction of microwave holograms. The scanning procedure makes use of an approach discussed by Farhat, et al. (1973). An eight-bit microprocessor with 64 kBytes of RAM is employed together with a diskette storage system.

Hetsch, J.↗