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Briefs: Mechanical & Fluid Systems
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...
Briefs: Mechanical & Fluid Systems
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,...
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 for...
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 the...
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, which...
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, using various partial pressures of AsH3....
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 systems.
Briefs: Test & Measurement
A lightweight, low-power-consumption power supply has been developed to generate a combination of radio-frequency (RF) and dc voltages needed for the operation of a miniature quadrupole...
Briefs: Electronics & Computers
Innovative optoelectronic encoders for measuring absolute, linear or angular position with super-high resolution have been invented. The new encoders rely on a combination of high-accuracy...
Briefs: Motion Control
The figure illustrates an improved electronic circuit that generates a signal proportional to either the instantaneous vibrational velocity or the instantaneous position (equivalently,...
Briefs: Electronics & Computers
Carbon Nanotubes as Anodes in Rechargeable Lithium-Ion Cells
Carbon nanotubes (also known as "bucky tubes") have shown promise for use as anode materials in rechargeable lithium-ion power cells. In comparison with graphite and other forms of carbon used under identical conditions, bucky tubes exhibit greater specific discharge capacity and greater...
Briefs: Motion Control
Pulse-Mode Reaction Control System Thruster
A spacecraft reaction-control-system (RCS) thruster now undergoing development generates a thrust of 870 lbf (3,870 N) by burning ethanol and liquid oxygen (LOX), which are nontoxic. The performance of the thruster has been tested in operation in multiple pulse modes with pulses as short as 160 ms; such...
Briefs: Motion Control
The figure illustrates an improved electronic circuit that excites constant-magnitude vibrations in an electrostatically actuated, capacitively sensed mechanical resonator. The circuit...
Briefs: Motion Control
Single crystals of Tb-Dy alloys exhibit magnetostrictive strains approaching 1 percent and can generate forces sufficiently large to make them useful as actuators in cryogenic...
Briefs: Motion Control
This is the first of four articles that address various issues concerning the generation and utilization of electronic signals in the operation of micromachined planar vibratory...
Briefs: Electronics & Computers
Fatigue cracks and plastic deformation of parts in jet aircraft engines could be detected, even during engine operation, by use of proposed in situ monitoring devices called "wireless...
Briefs: Motion Control
Electronic circuitry has been devised to compensate for variations in the resonance quality factor (Q) of a planar vibratory microgyroscope like that described in the first of the...
Briefs: Physical Sciences
A computer program (see figure) has been developed to serve as a time- and cost-effective means of automating thermal analyses of such hypersonic flight systems as the space shuttle orbiter, the...
Briefs: Physical Sciences
A computer program written within the Mathematica software system automatically generates FORTRAN computer codes that numerically simulate, with high accuracy, the acoustical physics...
Briefs: Physical Sciences
Dryden Flight Research Center has developed a computer program that performs signal management for analysis in real time (SMART). This program, called "SMART," has been effectively used since 1991 in...
Briefs: Mechanical & Fluid Systems
Comprehensive Micromechanics-Analysis Code (MAC/GMC)
Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC) is a comprehensive, user-friendly, efficient computer program that predicts the elastic and inelastic thermomechanical responses of continuous and discontinuous composite materials with arbitrary internal microstructures and...
Briefs: Information Technology
Forth Source Code Analysis Tool Set (FSCATS) is a computer program that provides a wide range of capabilities for documenting, analyzing, and reverse-engineering computer programs written in the Forth...
Briefs: Electronics & Computers
Planar arrays of cadmium zinc telluride photodetectors with readout electronic circuitry have been developed for use as hard-x-ray and y-ray image sensors. When a coded,...
Briefs: Materials
Ceramics Analysis and Reliability Evaluation of Structures/Creep (CARES/CREEP) is a computer program that predicts the creep lives of ceramic structural components. [CARES/CREEP should not be...
Briefs: Physical Sciences
The presence of corrosives in the Earth's atmosphere is of global concern. From acid rains that are destroying forests and disfiguring monuments like the Parthenon and the pyramids, to atmospheric pollutants that produce...
Briefs: Physical Sciences
Controlling Crystal-Growth Habit in Directional Freezing
A method of controlling the crystal-growth habit in directional freezing has been devised. A substance can be purified by directional-freeze crystallization, wherein (1) the liquid phase of the substance is partially frozen, causing impurities to become preferentially concentrated in the...
Briefs: Electronics & Computers
A transceiver has been developed to serve as a data-communication link between (1) the RS-232-standard serial communication port of a personal computer (PC) running the Windows 95 or Windows NT operating system...
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