August 1999

Briefs : Electronics & Computers
Three-Phase Sine-Wave Generator

A variable-frequency, three-phase, sine-wave generator circuit has been designed for use as a source of polyphase excitation in studies of the propagation of traveling waves in plasmas. This circuit, combined with three power-amplifier channels and three high-voltage transformers, is used to power the plasma...

Briefs : Motion Control
Apparatus for Attaching Two Spacecraft Under Remote Control

An apparatus called a "pneumatic stinger" has been developed to enable a first spacecraft, operating under remote control, to grasp a second spacecraft that is in orbit or other unpowered flight. The pneumatic stinger, which is mounted on the first spacecraft, is inserted in a...

Briefs : Mechanical & Fluid Systems
FoilSim: Software for Teaching About Airfoils

FoilSim is a computer program that calculates and graphically depicts information on flows of air around airfoils of various shapes. Although it is useful primarily as a teaching tool to enhance mathematical and scientific curricula, it was derived from "real-life" flow-computing software of...

Briefs : Motion Control
Motor Feedback Systems Raise Performance Level

Servomotor drive manufacturers agree that the performance of today's digital drive is largely determined by the performance of its feedback device. Clearly, previous feedback solutions, such as resolver technology and conventional encoders, no longer meet the increasing market demands for higher...

Briefs : Mechanical & Fluid Systems
Experiment on Reducing Drag on an Aerospace Launch Vehicle

Current proposed shapes for single-stage-to-orbit vehicles like the Lockheed-Martin X-33 and VentureStar reusable launch vehicle have extremely large base areas when compared with previous hypersonic-vehicle designs. As a result, base drag - especially in the transonic flight regime -...

Briefs : Software
Program Estimates Loads in Launch Vehicles

Version 1.4 of the Launch Vehicle Loads Analysis for Preliminary Design (VLOADS 1.4) computer program calculates in-flight launch-vehicle structural loads (that is, spacecraft-launching rockets) for preliminary design. The program can also be used to calculate structural loads in upper stages and...

Briefs : Materials
Magnetostrictive Micropositioner for Cryogenic Applications

A magnetostrictive linear-translation mechanism has been designed to function as a micropositioning device at any temperature from ambient down to the temperature of liquid helium (about 4 K). Still undergoing development at the time of reporting the information for this article, this...

Briefs : Electronics & Computers
Managing Wire Harness Design Information

Wiring is a major deliverable in just about all electromechanical equipment. From airplanes to semiconductor capital equipment, the key component tying together all of the technological innovations in these machines is the wiring. Until recently wiring system design has merely been an afterthought, the...

Briefs : Motion Control
Finding a Solution for Bellows Coupling Failure

When a problem such as breaking bellows couplings threatens to halt a machinery production line, it is necessary to look beyond the obvious. In an application in which the coupling works on a Heidenhain encoder for an X-Y table that positions circuit boards, representatives of the user company and...

Briefs : Software
Software for Detecting Anomalies and Responding to Faults

The Automated Test Monitor computer program provides for continuous monitoring of the operations of a complex system (e.g., a spacecraft). This program implements a rigorous analytic (instead of an ad hoc) technique that prescribes exactly how to express requirements for the operation of...

Briefs : Information Technology
Program Generates Graphics To Help in Planning Space Flights

The Mission Planning Graphical Tool (MPGT) computer program provides a mouse-driven graphical representation of data on a spacecraft and its environment, for use in planning a space flight. MPGT is designed to be a generic software tool that can be configured to analyze any specified...

Briefs : Materials
Magnetostrictive Filter-Wheel Drive

The figure shows a prototype of a magnetostrictively actuated mechanism that would rotate an optical filter wheel for a high-performance infrared camera or telescope. Typically, a high-performance infrared instrument and its filter wheel are operated inside a cryogenic system. In conventional practice, the...

Briefs : Electronics & Computers
Supplementing Overvoltage Protection

Low-voltage high-current loads requiring precision voltage regulation are served by power systems that sense voltage remotely at the load. This creates the risk of an overvoltage (OV) condition at the load if the remote sense contacts are incorrectly connected. A new technique to supplement standard OV...

Briefs : Materials
Magnetostrictive Heat Switch for Cryogenic Use

A magnetostrictively actuated heat switch has been proposed for use in a variety of cryogenic equipment, including adiabatic-demagnetization refrigerators, calorimeters, and coolers for high-performance infrared cameras. Heretofore, the heat switches in such equipment have generally been of two...

Briefs : Robotics, Automation & Control
Small Hybrid Rocket Engines Fabricated via X-Ray Lithography

Small hybrid rocket engines of a proposed type would burn specially shaped hollow cylinders of solid fuel containing slanted oxygen-injection channels, as shown in the figure. These engines would exploit a vortex flow phenomenon associated with the radial inflow of the oxygen in the...

Briefs : Information Technology
Software for Viewing Results of Computational Simulations

Parallel Visual 3 (pV3) is an interactive computer program that provides selected displays of data generated in numerical simulations - especially simulations that involve parallel processing. pV3 was originally designed to aid in the visualization of numerical results from computational...

Briefs : Materials
Push/Pull Magnetostrictive Linear Actuator

A proposed "kinematic inchworm"-type linear actuator would move a mass as large as 2 kg along rails, with lengthwise position controllable in increments as small as 50 nm. The actuator could be operated in microgravity or in normal Earth gravitation and at any temperature from ambient down to...

Briefs : Motion Control
Variable-Speed Motor Drives with Digital Control

Energy efficiency is a continuing focus of the power electronics industry. Motors consume the most electricity in commercial and industrial applications (followed at a distant second by lighting). More than 85 percent of electric motors are single-phase motors that are installed in numerous...

Briefs : Materials
Polycrystalline Tb/Dy Alloy for Magnetostrictive Actuators

Research has shown that with suitable processing, one can produce a polycrystalline version of a terbium/dysprosium alloy suitable for use in a magnetostrictive actuator for generating small motions. Prior to this research, only the single-crystal version had been used, and that in only...

Briefs : Physical Sciences
Exploiting Crossed Magnetic Antennas in a Natural Waveguide

A technique that involves the use of crossed magnetic antennas in a natural waveguide has been proposed for tracking Martian dust storms from a single observing station; that is, without having to triangulate from multiple observing stations. The technique is applicable to tracking...

Briefs : Robotics, Automation & Control
Miniature Turbomolecular Pump for High Vacuum

A proposed miniature turbomolecular pump would be a prototype of high-vacuum sources for a forthcoming generation of miniature, portable mass spectrometers and other scientific instruments. The miniature turbomolecular pump would be an attractive alternative to currently available high-vacuum...

Briefs : Materials
Extruding Tb/Dy for Magnetostrictive Actuators

A process that is undergoing development would be used to mass-produce textured polycrystalline rods of a terbium/dysprosium alloy for cryogenic magnetostrictive actuators. The rolling-and-heat-treatment process described in the preceding article yields a high degree of crystal orientation, but is...

Briefs : Electronics & Computers
Microwave Heating of Fibers for Chemical Vapor Deposition

A microwave-cavity applicator has been developed for coating multiple fibers by chemical vapor deposition (CVD). A prototype of the applicator was used to deposit silicon carbide onto carbon fibers; the design of the applicator can just as well be optimized for coating fibers made of...

Briefs : Materials
Improved Magnetostrictive Valve for Use at Low Temperature

An improved magnetostrictive valve for remotely controlling a flow of liquid helium has been developed. Heretofore, flows of liquid helium have been controlled by use of valves with mechanical or gas connections to actuators in warmer locations. The connections act as heat-leak paths....

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