July 2000

Briefs : Software
Software Improves Management of Dynamic Memory

The Dynamic Memory Management System (DMMS) is a computer program that was developed in response to some major shortcomings of dynamic-memory- management subsystems of typical operating systems. It is designed for use with the VxWorks operating system, but is easily ported to other operating...

Briefs : Physical Sciences
Sulfur Lamp With CaBr₂ Additive for Enhanced Plant Growth

Calcium bromide can be added to the sulfur filling in a sulfur lamp to increase the emission of red light for enhanced growth of plants. Red light is more efficacious for plant growth than is visible light at shorter wavelengths. The addition of CaBr2 increases the emission...

Briefs : Physical Sciences
Soaring to 100,000 ft on Stratospheric Mountain Waves

A research project now underway addresses the concept of utilizing stratospheric mountain waves to soar to high altitudes in sailplanes. Stratospheric mountain waves are mountain waves that propagate strongly, and with continuity, into the middle and upper stratosphere, and are not...

Briefs : Electronics & Computers
Data-Filter Algorithm for Monitoring a Power System

An algorithm has been developed for a computer-based electronic system that would aid human ground controllers in monitoring data from sensors in the electric-power system of the International Space Station. Among other things, the algorithm encodes knowledge of human experts; thereby...

Briefs : Electronics & Computers
Portable ECG/EGG Data Recorder

A portable electronic unit with no moving parts except button switches digitizes and stores a 48-hour record of the myoelectric activity of the stomach and heart as sensed via electrodes on the surface of the abdomen. Just as the more familiar electrocardiogram (ECG) is useful in diagnosing the condition of the...

Briefs : Information Technology
Software Facilitates Access to a Scientific Data Base

The Coordinated Data Analysis Workshop Web (CDAWeb) is a web-based service that facilitates access to a scientific data base of the International Solar-Terrestrial Physics (ISTP) program and other programs that generate public scientific information. In this data base, physical-science...

Briefs : Information Technology
A Standard for Scientific Data Files

The term "Instrument Data File Set" (IDFS) denotes both software and an underlying concept of a prescribed format for files of scientific data and metadata. The IDFS was developed to satisfy a need, in the space science community, to maintain data and metadata in a format that promotes efficient use of the...

Briefs : Information Technology
Software for Display and Analysis of Scientific Data

The Southwest Data Display and Analysis System (SDDAS) is a flexible, extensible software system intended to support analysis of space physics data from multiple instruments and multiple spacecraft missions. SDDAS was developed in response to the need of space scientists to be able to gain...

Briefs : Electronics & Computers
System Locates Lightning Strikes to Within Meters

A system for determining the locations of nearby lightning strikes from electric-field and acoustic measurements has been developed and built. The system includes at least three receivers, each equipped with an antenna and a microphone. For each strike, the system measures the difference between...

Briefs : Electronics & Computers
Flip-Chip W-Band Amplifier: a Prototype of Q-MMICs

A prototype W-Band, low-noise amplifier has been fabricated by bump-bonding a high-speed, low-noise InP high-electron-mobility (HEMT) transistor onto the previously fabricated passive portion of the amplifier circuit on a GaAs substrate (see figure). The passive portion of the circuit can be...

Briefs : Test & Measurement
Measuring NO and OH Concentrations at High Pressure

An apparatus based on line-of-sight resonant absorption of ultraviolet light yields measurement data from which one can calculate the concentrations of nitric oxide (NO) and of hydroxyl radicals (OH) in a laboratory flat flame at a pressure up to 30 atm ≈3 MPa). The basic measurement...

Briefs : Test & Measurement
Automated Apparatus for Testing Gyroscopes

The Gyroscope Automated Testbed is a computer-controlled apparatus designed primarily for automated testing of vibratory gyroscopes. It can also be used to test other devices: By changing testing-system/tested-device interface circuitry that is part of the apparatus, one can set up the apparatus to test...

Briefs : Test & Measurement
Electromechanical Testing of Microelectromechanical Devices

A method of electromechanical testing has been proposed for general diagnosis, evaluation of performance, and burn-in (accelerated life testing) of microelectromechanical devices. The tests would ordinarily be performed at the wafer level; that is, after the devices have been fabricated...

Briefs : Test & Measurement
Mechanism for Adjusting and Measuring Tension in a Cable

The figure illustrates a simple mechanism designed for anchoring one end of a cable on a structure and for adjusting the tension in the cable. Unlike turnbuckles and other conventional cable-tensioning mechanisms, this mechanism also facilitates direct measurement of the tension in the...

Briefs : Materials
Antioxidant Fiber Finishes for Polyimide-Matrix Composites

Polyimide-matrix/carbon-fiber composite materials with enhanced thermo-oxidative stability can be made from carbon fibers that have been coated with suitably formulated reactive finishing materials. These finishing materials were developed out of a need to increase thermo-oxidative...

Briefs : Materials
Enhanced Shield Against Meteoroids and Orbital Debris

NASA scientists, who are very concerned with the increasing hazard of impacts of orbital debris impact on spacecraft, have designed the "stuffed Whipple" shield — a lightweight, relatively inexpensive alternative to simple aluminum meteoroid/orbital-debris (M/OD) shield. The stuffed Whipple...

Briefs : Materials
High-Performance Zn Anodes for Ag/Zn and Ni/Zn Cells

Improved zinc anodes for silver/zinc and nickel/zinc rechargeable electrochemical cells have been invented. This invention will increase the usefulness and decrease cycle-life costs of Ag/Zn and Ni/Zn cells in NASA Space-Station-support applications, for which batteries with high energy...

Briefs : Materials
Tape-Spring Reinforcements for Inflatable Structural Tubes

Lightweight, inflatable tubular structural components containing tape-spring reinforcements are undergoing development. The basic (without tape-spring reinforcement) tubular components are made, variously, of aluminum laminates or composite materials and are under consideration for use...

Briefs : Mechanical & Fluid Systems
Mechanism for Planar Manipulation With Simplified Kinematics

The figure schematically illustrates three manipulator mechanisms for positioning an end effector (a robot hand or other object) in a plane (which would ordinarily be horizontal). One of these is a newer, improved mechanism that includes two coaxial, base-mounted rotary actuators...

Briefs : Mechanical & Fluid Systems
Improved Cable-Drive Pretensioner

An improved mechanism has been devised to facilitate the adjustment of tension in a cable in a cable-and-pulley drive. Cable-and-pulley drives are being used increasingly in robots and other high-performance, computer-controlled machines. Typically, a cable is looped around various drive pulleys with its ends...

Briefs : Mechanical & Fluid Systems
Path-Planning Program for a Redundant Robotic Manipulator

The Space Station Robot Manipulator System (SSRMS) Path Planning Program is a computer program that, in comparison with software developed previously for the same purpose, supports operations of faster and more complex robots. Two especially notable features of the program are that (1) it...

Briefs : Physical Sciences
Designing Purging Flows of Clean, Dry Gases

A method of designing purging flows of clean, dry gases to maintain acceptably low levels of contamination in enclosed volumes has been developed. The method is applicable to diverse enclosures that must be kept clean, including housings of precise optical instruments, clinical facilities, facilities...

Briefs : Materials
Update on a Progressive-Failure-Analysis Software System

A report presents additional information on the GENOA-PFA computer program, which was described in "Software for Simulating Progressive Fracture in Braided PMCs" (LEW-16845), NASA Tech Briefs, Vol. 24, No. 3 (March 2000), page 52. On the basis of material-property data, finite-element...

Briefs : Physical Sciences
Simulations of Evolving Transitional Mixing Layers

A report describes direct numerical simulations of single- and two-phase, temporally developing transitional mixing layers at Reynolds numbers (based on the initial vorticity thickness and mean velocity difference) from 200 to 600. As many as 300 × 332 ×180 grid points were used to discretize...

Briefs : Physical Sciences
Simulations of a Transitional Droplet-Laden Mixing Layer

A report describes direct numerical simulations of a droplet-laden mixing layer (e.g., evaporating droplets of a hydrocarbon fuel in air) undergoing a transition to mixing turbulence. The governing equations are those of Lagrangian transport of discrete droplets through a flowing gas,...

Briefs : Physical Sciences
Thermodynamic Instability of InxGa1–xAs/GaAs Quantum Dots

A report describes experiments that generated evidence of thermodynamic instability of nanometer-size islands (quantum dots) in InxGa1–xAs grown on GaAs. InxGa1–xAs/GaAs specimens were grown by metal-organic chemical vapor deposition,...

Briefs : Manufacturing & Prototyping
Maskless Gray-Scale X-Ray Lithography

In a proposed technique of maskless gray-scale x-ray lithography, a photoresist to be patterned would be exposed to a parallel beam of hard x-rays. As explained below, the photoresist would be translated across the beam at a varying rate to effect one-dimensional spatial variations in the radiation dose...

Briefs : Photonics/Optics
Nonsaturating Electronic Image Sensors

Focal-plane electronic image sensors that would not saturate when exposed to intense illumination have been proposed. These sensors could be used to acquire accurate, scientific-quality data on images (including spectral images), even when the images contain both very bright and very dark areas. The...

Briefs : Photonics/Optics
Readout for Fast IR Imaging With Large Detector Capacitance

A methodology for designing highly accurate readout circuits for infrared (IR) image detectors that have large pixel detector capacitances (of the order of tens of picofarads) and are required to operate with short exposure times (<100 µs) has been devised. In this context, "highly...

Briefs : Photonics/Optics
Ultrasonics With Laser In-Coupling and Air Out-Coupling

Efforts are under way to develop a technique of noncontact acousto-ultrasonic testing in which (1) a pulsed laser beam excites ultrasonic waves in a plate specimen and (2) the ultrasonic waves are detected by use of one or more focusing air-coupled ultrasonic transducer(s) placed at a...

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