January 2002

Briefs : Electronics & Computers
Real-Time-Programmable Reconfigurable-Vision Active-Pixel Sensors

Active-pixel integrated-circuit image sensors that can be programmed in real-time to effect artificial reconfigurable vision on demand have been developed and demonstrated. In imitation of a natural eye, the image sensor is designed to offer high resolution in a small region of...

Briefs : Mechanical & Fluid Systems
Instrumented Bolt Measures Bending Moments Within Itself

The Ultrabend bolt is a specially designed bolt instrumented with strain gauges (see figure) that are connected into twin Wheatstone-bridge circuits. The geometric arrangement of the strain gauges is such that by suitable electrical switching of the Wheatstone-bridge circuits, these...

Briefs : Physical Sciences
Tiger Fibers for Enhanced Optical Sensing of Volatiles

Improved fiber-optic transducers, denoted tiger fibers, have been proposed for sensing volatile compounds. Tiger fibers are so named because, as described below, their sensitive portions would be coated with periodically alternating stripes of different polymers, reminiscent of a tiger’s...

Briefs : Physical Sciences
Using Laser Diodes to Characterize Force and Pressure Sensors

A proposed method of characterizing microphones and other pressure and force sensors would exploit the temporally varying forces of impingement of amplitude-modulated light beams from inexpensive laser diodes. What makes the method likely to be practical is the surprising fact that...

Briefs : Mechanical & Fluid Systems
Improved Piezoelectrically Actuated Microvalve

Figure 1. The Previous Version of the Valve, like the present version, was opened by applying a voltage that caused the piezoelectric actuator to contract slightly.Efforts are underway to implement an improved design of the device described in "Normally Closed, Piezoelectrically Actuated Microvalve"...

Briefs : Electronics & Computers
Improved Continuity and Short-Circuit Tester

A relatively simple test circuit immediately and automatically provides indications of (1) the continuity (or the lack thereof) of the wires of a two-wire cable, plus (2) a short circuit (if any) between the wires. In the case of a coaxial cable, one of the wires can be the shield, the other wire, or...

Briefs : Electronics & Computers
Automated Detection of Streaks in Rocket-Engine Plumes

A high-speed observer (HSO) system comprising a high-frame-rate digital video camera and a high-speed computer that processes the camera output has been developed for use in monitoring the exhaust plume of the space shuttle main engine (SSME) during tests. The HSO system is designed to...

Briefs : Information Technology
Software for Analyzing Root Causes of Process Anomalies

Root Cause Analysis (RoCA) is a computer program that assists analysts in understanding the root causes of process anomalies. As used here, “process anomalies” includes incidents that have caused, or that can potentially cause, injuries to personnel, damage to facilities, abnormal...

Briefs : Mechanical & Fluid Systems
Program Computes Pointing Corrections for a Radiotelescope

TLC is a computer program that determines corrections for radiotelescopepointing errors associated with tilts and elastic deformations. These errors occur because for rotation in azimuth, a radiotelescope is mounted on wheels that move on a circular track that deviates from perfect...

Briefs : Information Technology
Ex — Software for Numerical Computation in Native Oberon

“Ex” is the name of a library of software modules from which one can rapidly develop prototype or production versions of efficient numerical-computation application programs in the Native Oberon programming environment. Mathematical constructs that can be represented and processed by...

Briefs : Materials
Annealing for Tailoring Au/GaN Schottky-Barrier Height

Annealing has been found to be an effective means of tailoring the height of a Schottky barrier between gold and gallium nitride. This finding offers promise for the development of improved metal contacts on GaN semiconductors. Heretofore, the commercialization of GaN semiconductor devices...

Briefs : Materials
Ceramics Made From Wood

The term “ecoceramics” (a contraction of “environment-conscious ceramics”) denotes a class of ceramics made partly from wood-based products, which can include natural wood, sawdust, cardboard, and/ or paper. In addition to the environmental advantage of renewability of the carbonaceous ingredients, the concept of...

Briefs : Mechanical & Fluid Systems
Lightweight, Low-Backlash Robot Wrist With Epicyclic Drive

A unique lightweight wrist with three degrees of rotational freedom has been developed as a prototype of wrists for future anthropomorphic robots that would perform a variety of tasks on Earth and in outer space. The three degrees of freedom (two rolling, one bending) intersect at the...

Briefs : Mechanical & Fluid Systems
Ice-Melting Probe Using Steam and Jets of Hot Water

An improved probe has been proposed for burrowing vertically into ice for scientific exploration of polar icecaps, glaciers, and the like. The predecessor of the improved probe is a Philbert probe, which contains an electric heater to melt the ice in contact with it and thereby make it descend...

Briefs : Manufacturing & Prototyping
Two Techniques for Removing Core-Drill Debris

Two alternative techniques make it possible to remove core-drill debris more rapidly and efficiently than was previously possible. Either technique is a vast improvement over the prior art. For industries in which ultrasonic core drills are used, these two techniques are expected to result in savings...

Briefs : Manufacturing & Prototyping
Electrical Monitoring of Thicknesses of Semiconductor Wafers

A technique based on electrical-continuity measurements has been proposed as a means of monitoring and controlling the thicknesses of semiconductor wafers during lapping, polishing, and etching. The technique is expected to contribute to the development of microelectromechanical...

Briefs : Medical
X-Ray Measurement of Kinematics in Muscles and Limbs

An x-ray photogrammetric technique for minimally invasive measurement of displacements in muscles, limbs, and organs is undergoing development. This technique could be alternative or complementary to the use of strain sensors. Measurements obtained by this technique could also be compared...

Briefs : Medical
Advanced System for Growing Plants in Microgravity

The figure depicts the Biomass Production System (BPS), which is an advanced system that provides controlled conditions for growing, manipulating, sampling, and harvesting plants in microgravity for both commercial purposes and scientific research. The design of the BPS incorporates lessons...

Briefs : Physical Sciences
Thermocouple Rakes for Measuring Boundary-Layer Flows

Thin-film devices that comprise heaters in combination with thermocouples have been developed for measuring flow velocities extremely close to solid surfaces, at several distances from the surface of interest. Devices that perform this function are denoted generally as "boundary-layer rakes."...

Briefs : Physical Sciences
Boundary Conditions for Computing Flows of Real Gas Mixtures

An improved formulation of equations of flow of a general gas mixture includes consistent boundary conditions that are applicable to real gases. An analysis of prior formulations, with focus on boundary conditions, led to the conclusion that boundary conditions based on ideal mixtures...

Briefs : Physical Sciences
Seed-Wing Flyers for Exploration

Small instrumented, free-flying (unpowered) rotary aircraft have been proposed for use in gathering scientific data from hazardous or inaccessible terrain on remote planets as well as on Earth. These aircraft are called "seed-wing flyers" because they would resemble winged seeds (e.g., maple seeds) in both...

Briefs : Physical Sciences
Long-Life Stratospheric Balloon System With Altitude Control

A proposed improved balloon system for carrying scientific instruments in the stratosphere would include a lightweight, ambient-pressure helium balloon and a vented infrared Montgolfiere (see figure). [An infrared Montgolfiere is an ambient-pressure warm-air balloon, named after the...

Briefs : Physical Sciences
Direct Methanol Fuel Cells With Aerosol Feed

Direct methanol fuel cells that would function with aerosol feed (instead of all-gas or all-liquid feed) have been proposed. As explained below, aerosol feed would afford the advantages of liquid feed, while reducing or eliminating some of the disadvantageous effects of liquid feed.

Briefs : Information Technology
Maximum-Likelihood Scheme for Tracking an Optical Source

A fine-pointing scheme that involves correlation of images and maximum-likelihood estimation has been proposed to enable tracking of optical sources. This scheme is intended for implementation in the pointing-control system of an imaging instrument (e.g., a telescope equipped with an image...

Briefs : Information Technology
Quantum Superluminal Transmission of Random Messages

In a proposed communication scheme, quantum entanglement and quantum nonlocality would be utilized to effect instantaneous transmission of randomly chosen messages to remote locations. Although the messages would not convey any information, they might nevertheless be of some value under...

Briefs : Information Technology
Goal-Based Fault Tolerance for Spacecraft Systems

A report discusses the concept of goal-based fault tolerance as implemented in NASA’s Mission Data System (MDS), which is a developmental architecture for unified flight, test, and ground software that is intended to be adaptable to a variety of next-generation deep-space missions. In...

Briefs : Electronics & Computers
PWM and Synchronous Rectifier Controller ASICs

A report describes two radiation-hard application-specific integrated circuits (ASICs) that constitute a mixed-signal chip set that performs all the control functions for a power-converter module (PCM) in a spacecraft power-supply system. One of these ASICs serves mainly as a pulse-width modulation...

Briefs : Physical Sciences
DNS of a Supercritical H₂/O₂ Mixing Layer

This report discusses direct numerical simulations (DNS) of a mixing layer between supercritical flows of oxygen and hydrogen. The governing conservation equations were those of fluctuation- dissipation (FD) theory, in which low-pressure typical transport properties (viscosity, diffusivity and...

Briefs : Information Technology
Remote Agent as Applied to the Deep Space 1 Spacecraft

A report presents updated information about the Remote Agent — a reusable artificial-intelligence software system that was described in “A Remote Agent Prototype for Spacecraft Autonomy” (NPO-19992), NASA Tech Briefs, Vol. 21, No. 3 (March 1997), page 106. This system was conceived to...

Briefs : Mechanical & Fluid Systems
Pneumatic Accelerator for Launching a Spacecraft

A report proposes the development of a ground-based launch-assist apparatus that would accelerate a spacecraft to a speed of about 270 m/s. The apparatus would include a track along which the spacecraft would ride on a sled coupled to a large piston driven by compressed air along a tube (more...

Briefs : Photonics/Optics
Hand-Held Optoelectronic Particulate Monitors

Optoelectronic instruments are being developed for use in measuring the concentrations and sizes of microscopic particles suspended in air. The instruments could be used, for example, to detect smoke, explosive dust in grain elevators, or toxic dusts in industrial buildings. Like some older,...

Briefs : Photonics/Optics
High-Performance Processor of Hyperspectral Images

The Remote Sensing Hyperspectral Engine (RSHE) is a special-purpose, portable computer that performs high-performance processing of hyperspectral image data collected by a remote-sensing optoelectronic apparatus. Typically, the remote-sensing apparatus is airborne or spaceborne, the images are...

Briefs : Photonics/Optics
Lateral-Current-Collection HgCdTe Infrared Detectors

Arrays of HgCdTe infrared photodetectors have been developed to satisfy stringent performance requirements for use in NASA’s Tropospheric Emission Spectrometer. The design of these detectors improves (relative to prior such arrays) manufacturing yield, current-versus-voltage characteristics,...

Briefs : Photonics/Optics
Portable Airborne Multispectral-Imaging System

A portable instrumentation system that includes an airborne and a ground-based subsystem acquires multispectral image data over swaths of terrain ranging in width from about 1/2 to 1 km. The system was developed especially for use in surveying coastal environments; it is also well suited for...

Briefs : Electronics & Computers
Lossless Image-Compression Algorithm Implemented in an FPGA

A lossless image-compression algorithm that can be executed entirely in electronic hardware has been developed. This algorithm yields about 15 percent more compression than does the Rice algorithm, which is a lossless-compression algorithm commonly used for transmitting images from...

Briefs : Physical Sciences
A Multifunctional Active-Excitation Spectral Analyzer

A highly sensitive, low-power, low-noise multifunctional active-excitation spectral analyzer (MAESA) that would span the wavelength range of 0.5 to 2.5 µm and would operate near room temperature is undergoing development. The fully developed MAESA is expected to be a portable and highly...

Briefs : Photonics/Optics
Hardware and Software for Air-to-Air Schlieren Imaging

Software and electronic hardware are being developed to provide cockpit guidance and camera control for an air-to-air schlieren photography system that is to be used to take high-resolution pictures of shock waves generated by a full-scale airplane (see Figure 1). For success in schlieren...

Briefs : Information Technology
Multirover Coordination Based on Contract Net Protocol

A computer program coordinates operations of multiple cooperating rovers (small exploratory robotic vehicles deployed from a lander spacecraft), each of which is equipped with computer hardware and software that schedule the tasks assigned to it. The program implements a contract net...


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