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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Low-intensity x-ray and gamma-ray imaging device

Low-dosage, low-power X-ray system can be made completely self-contained, allowing fluoroscopy and radiography to be carried out in field and remote locations. New device, known as "lixiscope," can be used with conventional X-ray machine turned down to low level, or, it can be operated with radioisotope source for hand-held portable applications. Originally developed for X-ray astronomy, lixiscope obtains high sensitivity by using intermediate stages of photoelectron conversion and electron amplification to generate image suitable for direct viewing or for recording on film.

Yin, L. I.↗
NASA NTRS1978

The effect of minor additions of titanium on the fracture toughness of Fe-12Ni alloys at 77K

Titanium additions ranging from 0.18 to 0.99 atomic percent and heat treatments of 2 hours at 550, 685 and 820 C respectively followed by a water quench were considered. Cubic and rectangular shaped inclusions were noted in the SEM fractographs of the alloys with the Ti additions. A fine precipitate was observed by TEM for the Fe-12Ni-0.18Ti alloys heat treated at 550 C; this precipitate was not observed for the 685 and 820 C heat treatments of the same alloy. Auger mappings of the fracture surfaces indicated a weak to moderate association of the interstitials C, N and O with Ti, the degree of which depended on the particular interstitial and the heat treatment temperature.

Conrad, H.↗
NASA NTRS1978

The Lixiscope: a Pocket-size X-ray Imaging System

A Low Intensity X ray Imaging device with the acronym LIXISCOPE is described. The Lixiscope has a small format and is powered only by a 2.7V battery. The high inherent gain of the Lixiscope permits the use of radioactive sources in lieu of X-ray machines in some fluoroscopic applications. In this mode of operation the complete X ray imaging system is truly portable and pocket-sized.

Yin, L. I.↗
NASA NTRS1975

ESCA studies on solar-wind reduction mechanisms

In a continuing study of solar-wind darkening on the lunar surface, ESCA techniques have been used to examine surface reduction and optical darkening by ion bombardment. Experimental results on transition metal fluorides have shown that ion-bombardment reduction is (a) accompanied by the loss of anion species, (b) relatively independent of the incident ion mass, and (c) not simply related to physical sputtering itself. The reduction mechanism may be more chemical in nature and the rate may be determined primarily by the transition metal ion

Yin, L.↗
NASA NTRS1979

Low intensity X-ray and gamma-ray imaging device

A radiation to visible light converter is combined with a visible light intensifier. The converter is a phosphor or scintillator material which is modified to block ambient light. The intensifier includes fiber optics input and output face plates with a photocathode-microchannel plate amplifier-phosphor combination. Incoming radiation is converted to visible light by the converter which is piped into the intensifier by the input fiber optics face plate. The photocathode converts the visible light to electrons which are amplified by a microchannel plate amplifier. The electrons are converted back to light by a phosphor layer and piped out for viewing by the output fiber optics faces plate. The converter-intensifier combination may be further combined with its own radiation source or used with an independent source.

Yin, L. I.↗
NASA NTRS1978

Forecast of Future Aviation Fuels. Part 1: Scenarios

A preliminary set of scenarios is described for depicting the air transport industry as it grows and changes, up to the year 2025. This provides the background for predicting the needs for future aviation fuels to meet the requirements of the industry as new basic sources, such as oil shale and coal, which are utilized to supplement petroleum. Five scenarios are written to encompass a range of futures from a serious resource-constrained economy to a continuous and optimistic economic growth. A unique feature is the choice of one immediate range scenario which is based on a serious interruption of economic growth occasioned by an energy shortfall. This is presumed to occur due to lags in starting a synfuels program.

English, J. M.↗
NASA NTRS1978

The low intensity X-ray imaging scope /Lixiscope/

A fully portable, small-format X-ray imaging system, Lixiscope (low intensity X-ray imaging scope) is described. In the prototype, which has been built to demonstrate the feasibility of the Lixiscope concept, only well-developed and available components have been used. Consideration is given to the principles of operation of the device, some of its performance characteristics as well as possible dental, medical and industrial applications.

Yin, L. I.↗
NASA NTRS1978

The role of rotor impedance in the vibration analysis of rotorcraft

In an improved method which retains the advantage of separate treatment of rotor and airframe, the rotor impedance is used to correct the input to the airframe. This improved method is illustrated for a strongly idealized case of vertical excitation and then for rolling and pitching moment excitation of a four bladed hingeless rotor on an up-focussing flexible mount. Contrary to the usual approach that represents aeroelastic blade motions by a series of normal blade modes in vacuum, the aeroelastic rotor impedances are computed directly with a finite blade element method that includes aerodynamics. The rotor impedance matrix for three or more blades is determined from the root moment impedance for a single blade by a simple multiblade transformation rule. Force and moment amplitudes transferred from the rotor to the support are found to be critically dependent on the support dynamics.

Hohenemser, K. H.↗
NASA NTRS1978

Trace element partitioning between ionic crystal and liquid

The partitioning of trace elements between ionic crystals and the melt has been correlated with lattice energy of the host. The solid-liquid partition coefficient has been expressed in terms of the difference in relative ionic radius of the trace element and the homogeneous and heterogeneous strain of the host lattice. Predictions based on this model appear to be in general agreement with data for alkali nitrates and for rare-earth elements in natural garnet phenocrysts.

Tsang, T.↗
NASA NTRS1979

A low-energy gamma-ray imaging detector

We describe a hard-X-ray/soft-gamma-ray imaging detector, incorporating a microchannel-plate (MCP) electron multiplier for possible use in future telescopes. In contrast to previous attempts using MCP's this approach promises to achieve high quantum detection efficiencies in addition to high spatial and temporal resolution. Preliminary results indicate not only the capability of simultaneous imaging and single-photon counting, but also coarse energy resolution.

Yin, L. I.↗
NASA NTRS1978

The Lixiscope concept

A portable X-ray imagery instrument which utilizes a converter phosphor or scintillator to convert the X-ray image into visible light image is described. The potential medical as well as industrial applications of the Lixiscope are presented.

Yin, L. I.↗
NASA NTRS1978

Some contemplated improvements to the prototype Lixiscope

Some contemplated improvements on the Lixiscope are described. These can be divided roughly into two categories: those which are well within existing technology, and thus can be implemented immediately; and those which are more at the state-of-the-art level, and which are directly related to applications in X-ray and gamma ray imaging in astronomy.

Yin, L. I.↗
NASA NTRS1980

New position-sensitive hard X-ray spectrometer

The design and features of a new prototype Lixiscope (Low intensity X-ray imaging scope) is described. It is shown that in addition to good spatial and temporal resolution in the 20 keV to 200 keV region, it is capable of single-photon counting, imaging as well as good energy resolution. It is concluded that the device is well suited for future low-flux applications in astronomy, medicine, and industry.

Yin, L. I.↗
NASA NTRS1980

Three-dimensional imaging of X-ray and gamma-ray objects in real time

A simple device is described that is capable of providing real-time 3-D viewing of extended X-ray and gamma-ray objects. The visible-light images produced by the device are not merely stereoscopic, i.e., one perspective, but possess both horizontal and vertical parallax with a reasonably large field of view.

Yin, L. I.↗
NASA NTRS1982

Improved Lixiscope

Improved lixiscope utilizes fast-decay scintillators and multiple or curved microchannels to achieve high energy and spatial resolution as well as single-photon counting. New unit, with higher energy resolution, is intended for X-ray astronomy, although it could be applied terrestrially wherever a sensitive portable radiation spectrometer is required for 20-to-200-keV range.

Yin, L. I.↗
NASA NTRS1981

Real-time observation of X-ray diffraction patterns with the Lixiscope

The feasibility of the Lixiscope (Low Intensity X-ray Imaging Scope) is demonstrated for real-time observation of transmission Laue patterns. Making use of the high-gain capability of microchannel plate (MCP) visible-light image intensifier tubes, X-ray images are converted to visible-light images by a scintillator. Pb discs are taped to the center of the Lixiscope input face, and crystal samples are held on a goniometer stage with modeling clay. With a compact size to facilitate off axis viewing, and real-time viewing to allow instantaneous response, the Lixiscope may prove useful in dynamic studies of the effects of plastic flows, stresses, high pressures, and low temperatures.

Chung, D. Y.↗
NASA NTRS1981

Computer aided manual tracking

A scheme was developed to assist the human operator by augmenting an optic sight manual tracking loop with target rate estimates from a computer control algorithm which can either be a Kalman Filter or an alpha, beta, gamma filter. The idea is for the computer to provide rate tracking while the human operator is responsible for nullifying the tracking error. A simple schematic is shown to illustrate the implementation of this concept. A hybrid real-time man-in-loop simulation was used to compare the tracking performance of the same flight trajectory with or without this form of computer-aided track. Preliminary results show the advantage of computer-aided track against high speed aircraft at close range. However, good tracking before target state estimator maturity becomes more critical for aided track than without. Results are presented for a constant velocity flight trajectory.

Yin, Y. K.↗