February 1999

Briefs : Test & Measurement
FT-IR Measurement of Hydraulic Fluids in Perchloroethylene

An improved solvent-extraction/infrared-analysis technique has been devised to replace an older technique for measuring very small concentrations of nonvolatile residues of industrial hydraulic fluids, oils, and greases on hardware that is required to be cleansed of such residues. The...

Briefs : Materials
Zn₄Sb₃: A High-Performance Thermoelectric Material

Zn4Sb3 has been identified as a high-performance thermoelectric material. In p-type, Zn4Sb3 samples have exhibited the greatest dimensionless thermoelectric figure of merit ever observed for a p-type material at temperatures from 200 to 350 °C. In...

Briefs : Electronics & Computers
Snapshot CCD Camera With Microelectromechanical Shutter

A proposed charge-coupled-device (CCD) camera would be mechanically shuttered by a planar array of micromachined, electromechanically actuated shutters. This proposal has arisen as part of the solution to the problem of designing a visible/near-infrared imaging spectrometer using a...

Briefs : Motion Control
Wipers Based on Electroactive Polymeric Actuators

Wiping devices that exploit fingerlike bending motions produced by electroactive polymeric (ionomeric) actuators are undergoing development. These wiping devices function similarly to conventional windshield wipers. However, unlike conventional windshield wipers, these devices contain no motors,...

Briefs : Electronics & Computers
Partitioned Frequency-Division Multiplex for Bandwidth Compression

Spectrum would be utilized more efficiently than in CDMA and FDMA.

Briefs : Test & Measurement
Passive Optical Measurement of Velocity in a Luminous Flow

A segmented-image emission velocimeter (SIEVE) is an optical instrument for measuring the velocity of a luminous turbulent flow. More specifically, it measures a component of flow velocity perpendicular to its line of sight. This instrument is not only nonintrusive but is also passive in...

Briefs : Electronics & Computers
Digital Approximation Premodulation Filter

This filter closely approximates the desired wave shape, regardless of the bit rate.

Briefs : Motion Control
Inflatable Strakes for Forebody Vortex Control

It is not necessary to allocate valuable forebody volume to strake-deployment mechanisms.

Briefs : Electronics & Computers
Magnetic Random-Access Memories

A Magnetic Random-Access Memory (MagRAM) is an array of bistable magnetic memory elements with semiconductor amplifier and addressing circuitry. MagRAMs are in the early stages of development, which has been motivated by a need for nonvolatile memories with high densities and unlimited cyclability -- a combination...

Briefs : Electronics & Computers
Three-Level Buck dc-to-dc Converter for Low Temperature

A dc-to-dc switching power converter of the three-level, pulse-width-modulated, buck type has been designed, built, and verified to operate at temperatures from ambient down to -196 °C (the temperature of liquid nitrogen). Circuits like this one could be useful for supplying electric power...

Briefs : Motion Control
Coupling Fixture Aligns and Seals Ends of Two Tubes

The figure presents a partial cross section of two poly(methyl methacrylate) (PMMA) tubes with machined ends butted and sealed together in a special coupling fixture. This coupling scheme, in conjunction with the careful selection of PMMA tubes to match inner diameters, ensures the precise...

Briefs : Robotics, Automation & Control
Ceramic Hybrid Electromechanical Systems

Ceramic hybrid electromechanical systems (CHEMS) have been proposed to overcome some of the disadvantages while retaining most of the advantages of microelectromechanical systems (MEMS). Whereas MEMS are fabricated mostly by micromachining of silicon and have typical feature sizes of the order of microns...

Briefs : Materials
Cold Hibernated Elastic Memory (CHEM) Expandable Structures

Experiments have confirmed the feasibility of a new class of lightweight, reliable, simple, and low-cost expandable structures. The concept called "cold hibernated elastic memory" (CHEM) utilizes the shape memory polymers (SMPs) in open cellular structures. Basically, these structures...

Briefs : Electronics & Computers
Metal/Dielectric-Film Interference Color Filters

Color interference filters for individual pixels in solid-state electronic image and display devices would be made of thin metal and dielectric films, according to a proposal. The proposed filters would overcome the primary disadvantage (high cost) of dye color filters like those used in...

Briefs : Electronics & Computers
Interdigital Overlay Capacitors for Integrated Circuits

Interdigital overlay capacitors have been invented to decrease the amount of integrated-circuit chip area needed to accommodate a given amount of capacitance. In most very-large-scale integrated (VLSI) circuits and monolithic microwave integrated circuits (MMIC), the integrated capacitors...

Briefs : Test & Measurement
Pressurization and Leak Testing of Sample-Return Canisters

A technique that involves pressurization with a radioactive gas has been proposed to solve two problems associated with canisters used to transport samples from remote bodies (planets, moons, asteroids, or comets) back to Earth. The canisters must be sealed at the sampling locations. The...

Briefs : Electronics & Computers
Optical Power Supply and Data Communication for APS Circuits

Active-pixel-sensor (APS) circuits and perhaps other dense complementary metal oxide/semiconductor (CMOS) very-large-scale integrated (VLSI) circuits would be powered by infrared beams transmitted by laser diodes and received by photodetectors, according to a proposal. Clock signals...

Briefs : Test & Measurement
A Technique for Axial/Torsional Thermomechanical Fatigue Testing

A technique for thermomechanical fatigue testing of thin-walled tubular specimens involves the application of cyclic axial (tension/compression) and torsional (shear) strains, along with thermal cycling. In this technique, the phase relationships among the two strain waveforms and...

Briefs : Mechanical & Fluid Systems
Equipping Quick-Disconnect Fittings To Detect Leaks

Quick-disconnect fittings on hoses and bellows can be equipped with sensors to detect leaks and misalignments that cause leaks. Experiments have shown that four types of sensors are effective for this purpose: force sensors, strain gauges, pressure transducers, and microphones. Of these, force...

Briefs : Electronics & Computers
"Natural Computing" System

A patent (U.S. Patent No. 5,680,557, "Natural Computing System and Environment") describes an invention that allows people to do computations by using time-tested and trusted ways of representing data and information. This method relies on equations, tables, graphs, worksheets, unit strips, text, and so forth in...

Briefs : Materials
High-Performance Thermoelectric Materials Based on β-Zn4Sb3

Materials based on β-Zn4Sb3have been found to exhibit unusually high values of the dimensionless thermoelectric figure of merit at temperatures between 200 and 400 °C. The discovery that p-type β-Zn4Sb3 is a high-performance thermoelectric...

Briefs : Software
Software for Developing Autopilots for Launch Rockets

Three integrated software products are being developed for use in the further development of autopilot systems for reusable launch vehicles (RLVs). The need for these products arises because of the unique nature of RLVs:

Briefs : Electronics & Computers
Novel Full-Color Cathode Ray Tube for Miniature-Display Applications

A novel cathode ray tube (CRT), using a single electron gun and a movable screen, has been developed that now enables miniaturization of a full-color CRT with the same excellent viewing quality customarily found in larger-screen CRTs. In addition to the benefits of wide viewing...

Briefs : Physical Sciences
Optoelectronic Liquid-Level Gauges for Aircraft Fuel Tanks

Gauges that would measure liquid levels optically have been proposed for use in aircraft fuel tanks. These gauges would contain no moving parts (no floats) and no wiring inside the tanks. Their overall function could be characterized as that of permanently immersed, self-reading...

Briefs : Electronics & Computers
Thermoplastic Weld Has Ergonomic and Environmental Benefits

Thermoplastic coupling is a patented welding process that is used to join thermoplastic parts. At the drill press, during a connector design brainstorming session, an engineer at Lucent Technologies' Bell Laboratories inserted a plastic rod into a cavity that was slightly too small in...

Briefs : Motion Control
Surface Micromachining of Diamond for Fabrication of MEMS Microstructures

A surface-micromachining process has been devised for use in fabricating microscopic polycrystalline diamond structures (e.g., bridges and cantilevers) as integral parts of microelectromechanical systems (MEMS). The general concept of MEMS encompasses such diverse objects...

Briefs : Electronics & Computers
Prolonging the Lives of Rechargeable Lithium-Ion Cells

Several modifications of the design and operation of lithium-ion rechargeable electrochemical cells have been proposed to prolong the cycle lives of the cells. As explained below, overdischarge can result in dissolution of a metal current collector in the anode of a cell, with consequent...

Briefs : Electronics & Computers
GaAs-Membrane-Diode Mixer for Operation at 2.5 THz

A prototype mixer designed for operation at input frequencies near 2.5 THz incorporates a planar Schottky-barrier diode and a radio-frequency (RF) filter that are parts of an integrated circuit on a GaAs membrane strip, plus several other unique features for which there are numerous potential...

Briefs : Electronics & Computers
Surface-Plasmon Reflective Flat-Panel Color Displays

Reflective flat-panel color display devices based on surface plasmons are undergoing development. Heretofore, no reflective flat-panel color display devices have been available. The active matrix liquid-crystal devices now used to provide flat-panel color displays must be lit internally, are...

Briefs : Materials
Nonchromic Acid Brightener for Brass and Copper

A process for precleaning brass and copper parts before processing them further in a clean room includes a brightening chemical treatment in solution of 85 volume percent phosphoric acid, 3 volume percent nitric acid, and 12 volume percent acetic acid. This solution acts rapidly and can be...

Briefs : Physical Sciences
Shape-Memory-Alloy Thermal-Conduction Switches

Variable-thermal-conduction devices containing shape-memory-alloy (SMA) actuators have been proposed for use in situations in which it is desired to switch on (or increase) thermal conduction when temperatures rise above specified values and to switch off (or decrease) thermal conduction when...

Briefs : Electronics & Computers
Using Surface-Plasmon Filters To Generate Scrolling Colors

Surface-plasmon tunable filters (SPTFs) have been proposed for use in generating scrolling colors on the faces of liquid-crystal display (LCD) devices. In comparison with a conventional color LCD device equipped with primary-color filters, a LCD device equipped with SPTFs according to...

Briefs : Electronics & Computers
Desktop Computer System Processes Satellite Data

The Desktop Satellite Data Processor (DSDP) is a prototype computer system for processing telemetry data received from, and command data to be transmitted to, a spacecraft in orbit around the Earth (see figure). The design of the system utilizes very-large-scale integrated (VLSI)...

Briefs : Mechanical & Fluid Systems
Analysis of Flutter of the APEX Sailplane

This airplane is expected to be safe from destruction by flutter instabilities.