Tech Briefs

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A comprehensive library of technical briefs from engineering experts at NASA and major government, university, and commercial laboratories covering all aspects of innovations in electronics, software, photonics, imaging, motion control, automation, sensors, test, materials, manufacturing, mechanical, and mechatronics.

Briefs: Physical Sciences

"Health check" would be built into pressure transducers, according to a proposal, to enable occasional, rapid, in situ testing of the transducers between normal pressure-measurement...

Briefs: Electronics & Computers
Improvements in a Fast Transient-Voltage Recorder

Some improvements have been made in an instrument designed expressly for recording lightning-induced transient voltages on power and signal cables. The instrument as it existed prior to the improvements was described in "Fast Transient-Voltage Recorder" (KSC-11991), NASA Tech Briefs, Vol. 23,...

Briefs: Electronics & Computers

Microscopic cathodes based on field emission (in contradistinction to thermionic emission) are undergoing development with a view toward using them as miniature or scalable sources of electrons in diverse...

Briefs: Medical
Spacecraft-Facility Microbes Tolerate H2O2, NaCl, and Heat

A report describes experiments that were performed to isolate and characterize microbes that survive conditions of controlled circulation of air, desiccation, low nutrient concentrations, and moderately high temperatures in a spacecraft-assembly facility. These conditions are more severe...

Briefs: Materials

A methodology for predicting stresses and the resultant cracking in plasma-sprayed thermal-barrier coatings (TBCs) has been developed. The methodology is built around a computer code that...

Briefs: Materials

Experiments have shown that ultrasound could be an effective means of enhancing the removal of chlorinated hydrocarbon contaminants from groundwater by the zero-valent-metal treatment...

Briefs: Materials
Study of High-Performance Polyimide Foams

This report describes an experimental study of thermal-stability, mechanical, and flammability properties of foams of several different densities made of three different polyimides. The study was performed because (1) prior such studies were performed on polyimide films rather than foams and (2)...

Briefs: Mechanical & Fluid Systems

The magnetic/extendible boom docking aid is an improved mechanism that enables two spacecraft to capture and structurally mate with each other without inducing the large (and...

Briefs: Physical Sciences
Subgrid Analysis of Mixing Layer With Evaporating Droplets

This report presents an analysis of a database from computational simulations of a droplet-laden mixing layer (i.e., evaporating droplets of a liquid fuel in air) undergoing a transition to turbulence. The basic governing equations were those of transport of discrete droplets through a...

Briefs: Mechanical & Fluid Systems
Vapor-Compression Solar Refrigerator Without Batteries

A solar-powered vapor-compression refrigeration system developed for Johnson Space Center operates without batteries. The design of this system will make the cost of solar-powered refrigeration systems competitive and enable the use of such systems in long-distance spaceflights, military...

Briefs: Physical Sciences
Validated Model of a Fluid Drop for All Pressures

The report "A Validated All-Pressure Fluid Drop Model and Lewis Number Effects for a Binary Mixture" presents one in a series of theoretical and computational studies of the subcritical and subpercritical behaviors of a drop of fluid and, in particular, a drop of heptane surrounded by nitrogen...

Briefs: Medical

The microwave-sterilizable access port is an apparatus that functions in a simple, quick, and reliable manner to reduce significantly the risk of contamination during transfer of materials into or out of...

Briefs: Photonics/Optics

The figure depicts an example of a proposed type of optoelectronic oscillator (OEO) based on some of the same principles as those described in the preceding article. In the proposed...

Briefs: Photonics/Optics

A prototype ring laser in which a transparent microsphere serves as an electromagnetic-mode selector has been constructed in a continuing effort to develop optoelectronic...

Briefs: Photonics/Optics

A class of proposed photonic switching devices would utilize interactions among light bullets that have been studied theoretically. Because they function at speeds much greater than those of...

Briefs: Photonics/Optics

An assembly that includes electromechanical rotary actuators has been developed specifically for use as the shutter mechanism of a cryogenic infrared camera that will be part of an...

Briefs: Photonics/Optics

Optoelectronic oscillators (OEOs) of a proposed type would be based partly on the use of fiber-optic linear or ring resonators in place of the long fiber-optic delay lines that have...

Briefs: Electronics & Computers
The NASA Spacecraft Transponding Modem

A report describes the NASA Spacecraft Transponding Modem (STM) — a spacecraft transponder now under development for planned use on deep-space missions scheduled for launch in the year 2003. In comparison with a traditional deep-space transponder, the STM will be smaller and less power hungry; the...

Briefs: Information Technology
Advances in Parallel Computing on Adaptive Grids

Five papers address interrelated topics in parallel computing and the use of adaptive, unstructured computational grids. The titles of the papers and their general subject matters are the following:

Briefs: Software
Computing Diffusion in High-Temperature Coating Layer

COSIM is a computer program that numerically simulates oxidation and diffusion in a metallic coating layer on substrates made of nickel-base alloys. COSIM is primarily useful for analyzing the gradual deterioration and predicting the lifetimes of the protective coating on turbine blades...

Briefs: Materials
Making Ion-Accelerator Grids From Ti Instead of Mo

Titanium has been found to offer several advantages over molybdenum as the material used to construct electrostatic-accelerator and -screen grids for ion thrusters for spacecraft. These advantages could also be expected to extend to the manufacture of grids for ion accelerators used in...

Briefs: Mechanical & Fluid Systems

An improved configuration for large, thin-walled lenticular booms has been proposed to reduce their susceptibility to buckling. Lenticular booms have been used on spacecraft because they can be flattened and...

Briefs: Mechanical & Fluid Systems
Vacuum Pumping Station

A proposed valve unit called a "vacuum pumping station" would be incorporated into a plumbing system that supplies a vacuum for vacuum insulated cryogenic equipment. The vacuum pumping station is intended to perform functions now performed by, and to be a simpler and more reliable alternative to, an assembly of components...

Briefs: Physical Sciences
DNS of Mixing of Supercritical Heptane and Nitrogen

A report discusses direct numerical simulations (DNS) of a developing mixing layer between nitrogen and heptane initially at different temperatures and initially flowing at different velocities under supercritical conditions. The usual conservation equations for a binary fluid, along with the...

Briefs: Mechanical & Fluid Systems
Gas Generator for Inflating Structures in Outer Space

A report proposes a system that would supply gas for inflating one or more inflatable structure(s) in outer space. The system would include a small tank of helium for initial inflation, plus a catalytic hydrazine gas generator that would supply makeup gas over the long term. After...

Briefs: Materials
Thermal Insulation Would Use CO2 in the Martian Environment

A report describes the development of a lightweight thermal insulation system for Martian surface applications. The ambient Martian atmosphere, which is predominantly carbon dioxide at a pressure of 10 torr, is used as the insulation medium with a modest multiple radiation shield...

Briefs: Mechanical & Fluid Systems
Martian Landing Balls

A report describes Martian landing balls, which are under development for use in delivering scientific payloads to Mars. Martian landing balls are related to other soft-landing devices that resemble beach balls and that have been described in several previous NASA Tech Briefs articles. They are also related to the...

Briefs: Electronics & Computers

An analog very-large-scale integrated (VLSI) circuit was designed and built to implement Hebbian synapses with an improved method of modifying and storing the synaptic weights, for...

Briefs: Electronics & Computers
Design of a Highly Reliable Controller for an I2C Bus

The design of a highly reliable controller for a digital data bus incorporates improvements, in both hardware and software, over the basic design of a low-speed, low-power, serial bus known in the industry as "I2C." ("I2C" signifies "inter integrated circuit bus" — a...

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