Tech Briefs

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A comprehensive library of technical briefs from engineering experts at NASA and major government, university, and commercial laboratories covering all aspects of innovations in electronics, software, photonics, imaging, motion control, automation, sensors, test, materials, manufacturing, mechanical, and mechatronics.

Briefs: Photonics/Optics
Trenches Would Reduce Cross-Talk Among Microlensed QWIPs

Cross-talk in integrated-circuit focal-plane arrays of quantum-well photodetectors (QWIPs) equipped with microlenses would be reduced, according to a proposal, by etching deep trenches into the substrates of these devices. The proposal applies, more specifically, to GaAs-based,...

Briefs: Materials

More accurate analyses of adhesive EA946 can now be accomplished using new mathematical models. Tests involving this adhesive (used in the space shuttle's reusable solid-rocket-motor nozzle and other...

Briefs: Photonics/Optics
Selective Metallization for High-Temperature Semiconductors

Inventors at the Cornell Research Foundation have devised a method of selective metallization of high-temperature semiconductors to produce ohmic or rectifying contacts. The process consists of three phases: a lithographic step to define the areas of contact, preparation of the...

Briefs: Electronics & Computers

An Internet-based software system, called the "Web Interface for Telescience" (WITS), enables geographically dispersed scientists to participate in scientific exploration of remote planets by use...

Briefs: Motion Control

When developing the guidance system of a missile, it is necessary to know the resonant frequencies and mode shapes of the missile in flight. Simulating the free vibration condition in the...

Briefs: Information Technology

The Multiple Object Orbital Dynamics Simulation (MOODS) computer program is a general, extensible, easily modifiable, and reusable software system for use in simulating the dynamics...

Briefs: Materials

The anode separators in rechargeable lithium-ion electrochemical cells that contain carbon lithium-intercalating anodes with copper current collectors would be modified, according to...

Briefs: Manufacturing & Prototyping

A method to process optical fiber composed of glass systems has been developed in support of the space shuttle and Space Station programs. This process, known as the Microgravity Fiber-Pulling Apparatus,...

Briefs: Photonics/Optics

The performances of large focal-plane arrays of quantum-well infrared photodetectors (QWIPs) would be improved, according to a proposal, by incorporating microlenses. In comparison with a similar...

Briefs: Photonics/Optics
Computer Code for Analysis of Stress in Silicon Wafers

The MacWafer™ code computes gravitational and thermal stresses in silicon wafers and uses these results to determine the maximum allowable temperature variation across a wafer, maximum processing temperatures, and maximum allowable heating and cooling rates. This information is of...

Briefs: Robotics, Automation & Control

Miniature, lightweight, low-power, low-vibration Joule-Thomson Rankine-Cycle refrigerators have been proposed for cooling portable scientific instruments. These refrigerators would be made...

Briefs: Mechanical & Fluid Systems

An acoustic-radiation-pressure phased array (ARPPA) is undergoing development at Lewis Research Center. ARPPAs are envisioned as general-purpose, nonintrusive tools for manipulating both...

Briefs: Information Technology
Software for Qualitative Flow-Path Modeling of Systems

A computer program called "the explicit global-modeling tool" implements a dynamic method of operation by which researchers can (1) determine global flow-path changes that occur during computational simulations of the behaviors of engineering systems; (2) analyze both normal and faulty...

Briefs: Electronics & Computers

Quantum-well infrared photodetectors (QWIPs) that are designed to exploit transitions between bound and quasi-bound electron quantum states and that incorporate random reflectors are...

Briefs: Photonics/Optics

A proposed miniature, electrically tunable, band-pass optical filter would have a Fabry-Perot configuration, but would be designed to trade the high spectral resolution (narrow-band pass)...

Briefs: Mechanical & Fluid Systems

Structural Analysis/Design (STRAND) and Neural Net Computation (NETCOM) are developmental modular computer programs that exploit the speedup afforded by parallel and neural-network...

Briefs: Materials

A microwave-heating technique has been developed for making a braze joint (1) between a tungsten carbide support and a surface layer of polycrystalline diamond or, alternatively,...

Briefs: Information Technology
Knowledge-Based Reasoning Tool for Diagnosing a Complex Flow System

This program is designed as a real-time aid to analyze system health.

The Propulsion Advisory Tool (PAT) is a knowledge-based computer program that monitors real-time data from more than 300 sensors in the space shuttle Main Propulsion System (MPS). The thermal conditions...

Briefs: Mechanical & Fluid Systems

Acoustic-radiation pressure can be used to improve performance in the dispensing of liquid drops into gases or vacuum and in dispensing gas bubbles into liquids. In a typical application...

Briefs: Electronics & Computers

Tracks for the guidance of magnetic bubbles propagating in the input and output lines of Vertical-Bloch-Line memory devices can be made in the form of ridges instead of in the traditional form of...

Briefs: Motion Control

The automated propellant-blending machine, a Johnson Space Center (JSC) innovation, refines the production processes of commercial rocket-propellant manufacturers by: (1) generating inert blends that...

Briefs: Electronics & Computers

"Free-Space Optical Communications Analysis Software" (FOCAS) is the name of a spreadsheet computer program for analysis of direct-detection (as distinguished from...

Briefs: RF & Microwave Electronics
Program Computes Flightpaths From Point Radar Sightings

A computer program estimates great-circle-arc (GARC) flightpaths of multiple aircraft, given time-tagged point locations from radar sightings of the aircraft. The problem of generating such estimates is called a "clustering" problem, and is solved in this instance by use of a...

Briefs: Test & Measurement
Noncontact Measurement of Surface Tension of Molten Material

An improved method of noncontact measurement of the surface tension of a molten material has been developed, partly to overcome the disadvantages of contact measurement techniques as described in the preceding article, "Noncontact Measurement of Resistivity of Molten Material"...

Briefs: Robotics, Automation & Control
Collision-Avoidance Experiments on 7-DOF Robot Arms

A report describes experiments on the concept described in "Real-Time Collision Avoidance for a Robot Arm" (NPO-19861), NASA Tech Briefs, Vol. 20, No. 12 (December 1996), page 98. Under this concept, collision-avoidance software processes data computed by model-based obstacle-detection...

Briefs: Test & Measurement
Noncontact Measurement of Resistivity of Molten Material

It is now possible to determine the electrical resistivity of a molten sample of a pure, electrically conductive material (a metal or semiconductor), without contact between the sample or any solid object. Once the electrical resistivity has been determined, the thermal conductivity can...

Briefs: Electronics & Computers

The term "space cube" denotes a scheme for three-dimensional stacking and interconnection of electronic-circuit modules. [This scheme should not be confused with a related one...

Briefs: Test & Measurement
Software for Automated Retesting of Electrical Connections

The Shuttle Connector Analysis Network Automated Electrical Retest Operations (SCAN/AERO) computer program assists in the tracking, management, and automation of the retesting of electrical connectors on the space shuttle orbiters. Among other things, SCAN/AERO analyzes test data to...

Briefs: Materials

Several modifications of the basic design of carbon lithium-intercalating anodes with copper current collectors in rechargeable lithium-ion electrochemical cells have been proposed. These...

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