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Briefs: Electronics & Computers
Improvements in Fabrication of HgCdTe Photodetectors
Two improvements have been made to solve two problems that arise in conjunction with a fabrication process in which an HgCdTe photodetector is mounted on an alumina substrate with epoxy. Although most of the HgCdTe-photodetector industry has abandoned this process in favor of epitaxial...
Briefs: Electronics & Computers
GaAs/AlxGa1-xAs quantum-well infrared photodetectors (QWIPs) with broad-band responses are undergoing development. The broad-band responses are obtained by varying the depths and widths of the wells and...
Briefs: Physical Sciences
A robust sensor based on the electrochemical oxidation of methanol has been developed for use in measuring the concentration of methanol dissolved in water. The sensor is expected to be...
Briefs: Mechanical & Fluid Systems
Model-Based Monitoring for Spacecraft Thruster Leakage
A report describes a method of detecting leakage in one of the 16 thrusters of the Cassini spacecraft. The detection method, implemented as part of the spacecraft flight software, is based on the fact that the three-axis rotational motion of a spacecraft is governed by the Euler's equation. The...
Briefs: Electronics & Computers
Monolithic, tandem two-junction InxGa1-xP/InxGa1-x As-on-Ge Solar Photovoltaic Cells are being developed. The cells are designed to be used with solar concentrators to generate...
Briefs: Motion Control
Mobile System for Control of a Remote Rocket-Launching Range
The Wallops Flight Facility of the Goddard Space Flight Center has designed and built in-house a Mobile Range Control System (MRCS), which is a self-contained system to be deployed in support of rocket launches at remote ranges in cases in which termination of flight may be required for...
Briefs: Robotics, Automation & Control
Early experiments in a continuing research program have demonstrated that thermal batteries made from powdered solid electrode and electrolyte materials can be improved by use of smaller...
Briefs: Information Technology
The SourceDoubls algorithm efficiently solves for singletons and doubletons of a digraph reliability model (defined below). In the case of a complex system of hardware and/or software...
Briefs: Electronics & Computers
Doping with silver bromide has been found to be an effective technique for enhancing the optical homogeneity and other qualities of single crystals of lead bromide. These crystals are grown from...
Briefs: Energy
According to a proposal for small electric-power systems that must operate in cold environments, heat released in the operation of solar photovoltaic arrays with solar concentrators would be...
Briefs: Physical Sciences
Programmable multizone furnaces with enhanced designs have been proposed for use in processing materials by directional solidification or, optionally, by related techniques of...
Briefs: Electronics & Computers
High-Performance HgCdTe Detectors for Remote Sensing: Part 2
The split-geometry design for arrays of photoconductive HgCdTe infrared photodetectors described in the preceding article can also be used to mitigate the deleterious effect of a phenomenon called "sweepout," which degrades performance. Sweepout occurs in conventional small HgCdTe...
Briefs: Information Technology
A method for detecting and characterizing faults in a rotating machine involves analysis of selected aspects of the evolution of the spectral distribution function (SDF) of its...
Briefs: Manufacturing & Prototyping
An integrated suite of computer programs is undergoing development to address issues pertaining to the formation of burrs — undesired projections of metal that are generated on edges...
Briefs: Robotics, Automation & Control
Each member of the aircrew of an advanced fighter airplane wears a complex, multilayered ensemble that imposes a significant thermal burden by inhibiting normal transport of heat from the...
Briefs: Electronics & Computers
Improved electrical connections have been developed for thin-film thermocouples used to measure temperatures on the surfaces of ceramic-matrix composite-material specimens during...
Briefs: Electronics & Computers
High-Performance HgCdTe Detectors for Remote Sensing: Part 1
Focal-plane arrays of HgCdTe photoconductors have been designed and fabricated to satisfy special requirements for high-performance long-wavelength infrared (LWIR) photodetectors. The special requirements are the following:
Briefs: Materials
A method of fabricating membrane electrode structures for methanol fuel cells involves, among other things, the use of improved sprayers to deposit inks containing catalytic metals on...
Briefs: Physical Sciences
Scanning filters based on surface plasmons would be used as the adjustable wavelength-selective (band-pass) devices in a class of proposed miniature spectrometers. These filters would...
Briefs: Mechanical & Fluid Systems
The Perseus B remotely piloted vehicle (RPV) has achieved a record altitude for a single-engine, propeller-driven airplane of 60,260 ft (18,367 m) on June 27, 1998. The Perseus B is one of the...
Briefs: Robotics, Automation & Control
A spark-ignited reciprocating gasoline engine, intake-pressurized with three cascaded stages of turbocharging, was selected by NASA's Environmental Research Aircraft and Sensor...
Briefs: Manufacturing & Prototyping
Two mounting schemes were devised for attaching heater wires to special-purpose glass tubing used in a capillary-heat-transfer experiment. Not only were the wires required to supply...
Briefs: Mechanical & Fluid Systems
Streamlined fairings have been invented for housing single or multiple microphones to measure noise in flowing gases and liquids. Each fairing of this type is designed to minimize the...
Briefs: Information Technology
ParVox is a distributed visualization system consisting of a rendering core running on a parallel computer and a graphic user interface program (GUI) running on a Unix...
Briefs: Physical Sciences
Properties of Ni/Zr Melts Related to Formability of Glasses
A report describes a study of the relationships between (1) the viscosities and specific volumes of Ni/Zr melts and (2) the formability of Ni/Zr-alloy metallic glasses. Experiments were performed on electrostatically levitated, radiantly heated molten specimens of two compound-forming and...
Briefs: Photonics/Optics
Optical Diagnostics of High-Pressure Liquid Fuel Sprays
A report describes experiments in which nonintrusive optical diagnostic techniques were applied to high-pressure fuel sprays in simulated advanced turbine-engine combustor environments. The experiments involved three different fuel injectors in two unique optically accessible combustors: a...
Briefs: Software
Software Detects Small Satellites in Spacecraft Imagery
A computer program processes images acquired at different times by instrumentation aboard a spacecraft to detect small satellites of asteroids and other planetary bodies. The program coregisters the images, removes instrument artifacts and images of background stars, and performs a...
Briefs: Physical Sciences
An effective Lewis number has been defined for two-fluid mixtures under conditions of (1) supercritical temperature and pressure and (2) large gradients of temperature and composition. The Lewis...
Briefs: Materials
Polyimides have been used widely in fiber-reinforced composite materials for aerospace components and in thin films for packaging of electronic circuitry. Typically, the synthesis of a...
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