July 1998

Briefs : Electronics & Computers
Single-Event Latchup Protection of Integrated Circuits

Many commercially available advanced-technology CMOS and bipolar integrated circuits are susceptible to single-event latchup (SEL) effects caused by heavy ions or protons from cosmic rays or solar flares, making them unsuitable for satellite applications. Remanufacturing the integrated...

Briefs : Electronics & Computers
Inverse Rectennas for Two-Way Wireless Power Transmission

The term "inverse rectenna" may seem like an oxymoron at first glance. However, preliminary experiments have demonstrated that a rectenna of suitable design can be made to operate in an inverse mode, in which radio-frequency (RF) power is generated in the rectenna rectifier circuits and...

Briefs : Mechanical & Fluid Systems
Laser Anemometer Measures Flow in a Centrifugal Compressor

Detailed measurements of complex flow fields within the NASA Low Speed Centrifugal Compressor (LSCC) have been acquired. The measurement data provide insight into the fundamental physics of flow in centrifugal compressors, and can be used to assess computational fluid dynamics codes and...

Briefs : Electronics & Computers
Heat Pipes for Temperature Control in Electronics

As electronic circuits become more densely packaged and higher in power, maintaining them within permissible temperature ranges becomes a major issue. This is especially true in the case of such portable devices as laptop computers, cellular telephones, and other hand-held units. Cooling by a...

Briefs : Electronics & Computers
SQUID-Based Asymmetric Planar Gradiometer

Berkeley Laboratory researchers have demonstrated a novel superconducting gradiometer that helps to reduce ambient magnetic field noise generated by relatively distant sources in favor of tiny magnetic signals generated by a local source. This is another step toward the operation of SQUID-based...

Briefs : Mechanical & Fluid Systems
Emergency-Shutoff Valves Would Be Triggered by Accelerations

Automatic valves have been proposed for shutting off flows of liquids when abnormally large accelerations occur. These valves could be used, for example, to prevent outflows of flammable, valuable, or toxic liquids from pipelines that have been struck by vehicles or that have become...

Briefs : Robotics, Automation & Control
Lightweight "Beach-Ball" Robotic Vehicles

Lightweight, inflatable robotic vehicles (rovers) that superficially resemble beach balls and that could be driven by wind and/or electric power are undergoing development. These rovers were conceived for carrying scientific instruments across rocky terrain on Mars, and are intended to move faster,...

Briefs : Electronics & Computers
GPS Drives Interactive Map Showing Position of Test Airplane

An electronic system that comprises airborne and ground-based subsystems generates data for a global real-time interactive map (GRIM) that displays the current position and velocity of the NASA F-18 Systems Research Aircraft (SRA). This system utilizes the Global Positioning System...

Briefs : Mechanical & Fluid Systems
Software for Navigation of a Spacecraft Flying in Formation

The Spacecraft Autonomous Navigation System using GPS for Earth Orbiters (SANS-GEO) computer program is designed to perform the navigation calculations that will enable the New Millennium Program's Earth Orbiter-1 (EO-1) spacecraft to fly in formation with the Landsat-7 (LS-7)...

Briefs : Electronics & Computers
Training Neural Networks With Fewer Quantization Bits

A method for reducing the number of bits of quantization of synaptic weights during training of an artificial neural network involves the use of the cascade back-propagation learning algorithm. The development of neural networks of adequate synaptic-weight resolution in very-large-scale...

Briefs : Mechanical & Fluid Systems
Program Performs High-Precision Spacecraft-Constellation Navigation

The Multiple Interferometric Ranging Analysis using GPS Ensemble (MIRAGE) computer program processes spacecraft-tracking data to determine orbits of single satellites, or of multiple satellites with intersatellite tracking, to within position errors as small as a few...

Briefs : Electronics & Computers
Terrestrial Portable Spacecraft-Mission-Support Stations

A data-communication and -processing network of compact, laptop-computer-based portable stations communicating via the World Wide Web (WWW) has been proposed as a relatively inexpensive end-to-end ground support system for future spacecraft missions. At present, end-to-end ground support...

Briefs : Mechanical & Fluid Systems
Finite-Element Model of Piezoelectric and Thermal Effects

A mathematical model that includes layerwise finite elements has been developed for use in numerical simulation of the coupled electrical, mechanical, and thermal responses of composite plate structures that incorporate piezoelectric sensors and actuators. Typically, the sensors and...

Briefs : Mechanical & Fluid Systems
Passive Capture Joint WithThree Degrees of Freedom

A new joint, proposed for use on an attachable debris shield for the International Space Station Service Module, has potential for commercial use in situations where hardware must be assembled and disassembled on a regular basis.

Briefs : Physical Sciences
Automatic Thermal Switches With No Moving Parts

Quasi-thermostatic gas-gap thermal switches have been proposed. These switches would operate automatically, would contain no moving parts, would not require power supplies or controls, would not consume any materials, and would not create vibrations. The operation of a switch of this type would be...

Briefs : Robotics, Automation & Control
Simulations in Support of Towed Flight Demonstration

The Eclipse flight project was established to demonstrate a reusable-launch-vehicle concept developed by Kelly Space and Technology, Inc. An F-106 delta-wing aircraft was chosen as the towed vehicle, and a C-141A transport-type airplane was selected for the towing vehicle. These airplanes are...

Briefs : Electronics & Computers
Improved Two-Wavelength Focal-Plane Array of QWIPs

A focal-plane array (FPA) of GaAs-based quantum-well infrared photodetectors (QWIPs) that would detect images in two wavelength bands simultaneously is undergoing development. From ratios between image intensities at the two wavelengths, one can calculate the temperatures of imaged objects by...

Briefs : Materials
Software for Probabilistic Analysis of Composite Structures

GENOA is an advanced, completely integrated, hierarchical software package for computationally simulating the thermal and mechanical responses of high-temperature composite materials and of structures made of those materials. The development of GENOA was guided partly by the need for a...

Briefs : Materials
Ion-Beam-Deposited DLC Coatings on Fine-Grain CVD Diamond

Ion-beam-deposited surface layers of diamond-like carbon (DLC) on fine-grain chemical-vapor-deposited (CVD) diamond have been found to be effective in reducing friction and wear in a variety of environments, including ultrahigh vacuum. This discovery opens the possibility of taking...

Briefs : Robotics, Automation & Control
Miniature Side-Bore Sample-Acquisition Mechanism

The figure illustrates various aspects of a proposed mechanism that would be mounted in an instrumented penetrator dart for use in acquiring a sample of soil. In operation, the dart would be dropped from a height to make it penetrate the ground to a suitable depth, then the mechanism would be...

Briefs : Electronics & Computers
Delta-Doped CCDs for Measuring Energies of Positive Ions

Research closely related to that reported in the preceding article has shown that δ-doped charge-coupled devices (CCDs) could be used to detect incident protons and perhaps other positive ions, and to measure the kinetic energies of the ions, down to about 1.25 keV. Prior to the...

Briefs : Robotics, Automation & Control
Microscopic Heat Exchangers, Valves, Pumps, and Flowmeters

Microscopic forced-flow heat-transfer systems containing heat exchangers, flow channels, electrostatically driven peristaltic pumps, and related components have been proposed. These systems would be made largely of silicon, by use of micromachining processes similar or identical to...

Briefs : Electronics & Computers
Delta-Doped CCDs as Low-Energy-Particle Detectors

Charge-coupled devices (CCDs) of a type developed previously for imaging in ultraviolet light have been found to be useful as detectors of electrons and other charged particles with kinetic energies as low as about 100 eV. Heretofore, solid-state electronic devices have generally not been useful...

Briefs : Materials
Matrix and Coating Polymers for Composite LOX Containers

Two poly(arylene ether phosphine oxide)s (PAEPOs) have been found to be suitable as matrix and coating materials for composite-material (matrix/fiber) tanks and pipes that contain liquid oxygen (LOX). One of these PAEPOs is denoted by the trade name "Triton Oxygen Resistant" (TOR); this...

Briefs : Robotics, Automation & Control
Procedure for Designing Safe Robots

A methodology for designing robots provides for satisfying both safety and performance requirements. Heretofore, most robot-design efforts have been focussed on maximizing performance, with only incidental regard for safety, under the assumption that humans and delicate equipment would be excluded from robot...


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