April 1999

Briefs: Electronics & Computers

A proposed multilayer metal-film/dielectric-plate laminate would serve as a passive radio-frequency (RF) interlayer stripline transition. This device is designed to provide RF coupling from (a) an input...

Briefs: Materials

An improved method of fabricating membrane electrode structures for methanol fuel cells is similar to the method described in the preceding article, except that in this method, the...

Briefs: Electronics & Computers
Circuit for Automatic Tunneling-Controlled Golay Cell

An automatic tunneling-controlled, micromachined Golay cell has been implemented in a multichip integrated-circuit module. The module is designed specifically for sensing infrared radiation indicative of the concentration of glucose in blood, but its low noise, high gain, and low power...

Briefs: Physical Sciences

"HOTCFGM-1D" denotes a collection of four computer programs, plus the underlying theory, for calculating thermomechanical and inertial effects in axisymmetric cylindrical...

Briefs: Electronics & Computers

Vertical-Bloch-line (VBL) memory devices of a proposed type would include stacks of VBL memory chips plus other components (see figure on next page). Each chip would be square,...

Briefs: Physical Sciences
Details of Apparatus for Advanced Ultrasonic C-Scan Imaging

A report comprising the main contents of U. S. Patent 5,750,895 presents detailed information on the subject of "Apparatus for Advanced Ultrasonic C-Scan Imaging (GSC-13524), NASA Tech Briefs, Vol. 21, No. 4 (April 1997), page 34. The apparatus is a computer-controlled ultrasonic C-scan...

Briefs: Information Technology

A method of computational simulation of the aerodynamic- or hydrodynamic-flow performance features of objects involves the use of neural-network mathematical models implemented in...

Briefs: Electronics & Computers
Segmented-Aperture Michelson Interferometer

In a proposed modification of the basic design of a Michelson interferometer, the beam aperture would be split into a number (N ≧ 2) of smaller areas and the optics arranged so that the beam in each area would generate a distinct segment of the overall desired interferogram. Each segment of the...

Briefs: Materials

Electric arcs and electrochemical etching can be used to impart microscopic textures to surfaces of metals. In electric-arc texturing, one strikes an arc between a water-cooled...

Briefs: Robotics, Automation & Control

Small, lightweight sensors that exploit the unique characteristics of nanoceramics are being developed for use in measuring air/fuel ratios in the exhaust gas flows of advanced aircraft...

Briefs: Software
Software for Operating a Forward-Link-Simulator Card

A computer program has been developed to serve as the means for setting up, controlling, and receiving information on the status of a forward-link-simulator card in a Digital Equipment Corporation (DEC) Alpha computer that runs the Digital UNIX operating system. The program performs functions...

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...

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...

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....

Briefs: Electronics & Computers

Monolithic, tandem two-junction InxGa1-xP/InxGa1-x As-on-Ge Solar Photovoltaic Cells are being developed. The cells are designed...

Briefs: Electronics & Computers
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...

Briefs: Electronics & Computers

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...

Briefs: Materials

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...

Briefs: Electronics & Computers

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...

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...

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...

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...

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...

Briefs: Robotics, Automation & Control

Human-powered machines that can be operated as centrifuges or as stationary exercise stations have been invented. These machines are suitable for a variety of terrestrial and...

Briefs: Physical Sciences
Foam Heat Exchangers

Experiments have demonstrated the feasibility of heat exchangers with flow channels containing open-cell metallic foams. Nonmetallic foams could also be used. One proposed design calls for an open-cell foam in the annular region between an inner and an outer tube, with a heat-transfer fluid flowing along the annular region...

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