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;...

The figure illustrates an improved electronic circuit that excites constant-magnitude vibrations in an electrostatically actuated, capacitively sensed mechanical resonator. The circuit...

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...

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...

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...

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...

An optoelectronic instrument, known as a plant fluorescence sensor, is being developed for use as a working tool in agricultural settings. This instrument is a remote, passive...

A method of correcting for defective pixels in an integrated-circuit image sensor of the active-pixel sensor (APS) type has been proposed. The corrections would be made by additional...

Briefs: Mechanical & Fluid Systems
Surface Micromachined Silicon Carbide Accelerometers

Surface micromachined silicon carbide accelerometers are undergoing development for eventual use in high-temperature environments like those inside turbines, internal-combustion engines,...

Briefs: Physical Sciences
Software for Predicting Behavior of a Pyrotechnic Actuator

A theoretical model that predicts the time-dependent behavior of a pyrotechnically actuated mechanism and a computer program that implements the model have been developed. The model and program are especially applicable to a pyrotechnic device known as the NASA Standard Initiator (NSI)....

Briefs: Physical Sciences
Dither Sensing for Controlling a Segmented-Mirror Telescope

Image-plane multidither sensing has been found to be suitable for adaptive wavefront correction in a large telescope in which the main optic is a precise reflector divided into lightweight, controllably actuated segments. In image-plane multidither sensing, the telescope is aimed at a...

Briefs: Physical Sciences
Self-Temperature-Compensated Ceramic Strain Gauges

Ceramic static-strain gauges capable of generating mechanical-strain signals much larger than spurious thermal signals have been invented. These gauges are intended for use at temperatures from room temperature to 1,250 °C. Heretofore, external circuits have been used to provide temperature...

Magnetostrictive actuators that would hold their displacements with power turned off have been proposed for use at temperatures from about 10 to about 77 K. Such "set and hold with power off"...

Briefs: Electronics & Computers
Electrobiotic Toxic-Agent Sensors

Electrobiotic sensors have been proposed for detecting toxic substances in a variety of environments. Electrobiotic sensors would be inexpensive, compact units that would be easy to use and could be deployed...

Briefs: Electronics & Computers
Magnetoelectric Sensors and Electric Generators

Electric generators and magnetic-field sensors of a proposed type would be based on the magnetoelectric effect. A simple device of this type (see figure) would consist mainly of an inner layer...

Submillimeter-sized thermoelectric devices based on thick films of Bi2–xSbxTe3 are undergoing development. As electronic circuits are designed with...

Briefs: Electronics & Computers
High-Speed Complex-Amplitude Liquid-Crystal SLMs

High-speed complex-amplitude spatial light modulators (SLMs) containing liquid crystals with pixel electronic circuitry on single-crystal-silicon backplanes are undergoing development. The basic approach taken in this project is to use fast-switching liquid-crystal materials and...

Briefs: Test & Measurement
Laser Heating for Testing Rocket-Engine Insulating Phenolic

A continuous-wave CO2 laser has been selected as a source of heat for testing the thermal response of carbon-cloth phenolic like that used as insulating material in a reusable solid-fuel rocket motor (RSRM). The particular thermal response of interest, observed during...

Briefs: Software
SIMON — School Internet Manager Over Networks

School Internet Manager Over Networks (SIMON) is a software tool, exclusively for use on Macintosh computers, that is designed to provide access to, and management of, Internet information for teachers and students in kindergarten through twelfth grade. By eliminating the requirement for advanced...

A number of matrix resins that contain thermosetting plasticizers have been developed for use in the resin-transfer molding (RTM) of composite-material (fiber/matrix) parts. These...

Briefs: Mechanical & Fluid Systems
Molded Plastic Simulated Landscapes

Simulated landscapes of Mars have been made of thermoplastic sheets molded to shapes derived from images of the Martian terrain. These simulated landscapes can be used to advantage in scientific experiments, simulations, educational displays, and other applications, in which unitary molded plastic sheets...

Investigators at the Johnson Space Center White Sands Test Facility (WSTF) have developed specifications of the amounts of alloying elements needed to increase the specific strengths of nickel alloys...

Briefs: Materials
Aerogels With Gradients of Density

Aerogels with gradients in density have been produced in experiments, as part of an effort to develop materials that will be used in outer space to capture particles traveling at high speeds for the STARDUST mission.

Irradiation by the beam from a CO2laser has been found to be an effective means of marking a black anodized aluminum surface. In general, this process works on any dark...

A proposed focal-plane array (FPA) of quantum-well infrared photodetectors (QWIPs) would sense images in three different infrared wavelength bands simultaneously. These and other QWIP infrared...

Briefs: Photonics/Optics
Update on Fuzzy-Logic-Enhanced Digital-PIV Software

Two reports present additional information on the subject matter of "Software for Processing Data in Particle-Image Velocimetry" (LEW-16857),NASA Tech Briefs, Vol. 24, No. 1 (January 2000), page 26a. Like the cited prior article, both reports discuss the principles and the practical aspects of...

Briefs: Photonics/Optics
Two-Color Random Reflectors for QWIPs

Random reflectors of a proposed type would be fabricated on the back surfaces of quantum-well infrared photodetectors (QWIPs) to increase the coupling efficiency of infrared light into the QWIPs in two...

Tridirectional diffraction gratings have been proposed to provide optical coupling to quantum-well infrared photodetectors (QWIPs) in focal-plane arrays. The tridirectional gratings...

Briefs: Photonics/Optics
Optical Filters Based on Dense Arrays of Microscopic Pillars

A proposal for development of a class of high-transmission and antireflection optical filters is derived from the observation that the eyes of moths reflect almost no light, regardless of the wavelength or the angle of incidence of illumination. The low-reflection property of moth...

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