Briefs : Mechanical & Fluid Systems
Airlocks for Pressurized Rovers

A report presents a survey of the design engineering and scientific literature on airlocks and on planetary-exploration vehicles ("rovers"), from the perspective of evaluating existing and potential design concepts for airlocks for pressurized rovers. The airlocks are the key to designing a pressurized rover...

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
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 : 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 : 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 : Photonics/Optics
Closed-Loop Microsphere Laser for Optoelectronic Oscillator

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 oscillators for generating light signals amplitude-modulated by microwave signals, all with low phase noise....

Briefs : Physical Sciences
Photonic Switching Devices Using Light Bullets

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 electrically, magnetically, and acoustically actuated switching devices, these and other photonic switching...

Briefs : Photonics/Optics
Miniature Optoelectronic Oscillators Based on Microspheres

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 OEOs as in the OEOs of the preceding article, transparent (e.g., glass) microspheres that exhibit...

Briefs : Photonics/Optics
Low-Power Shutter Mechanism for a Cryogenic Infrared Camera

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 astronomical telescope. The camera will be cooled, by use of superfluid helium, to an operating...

Briefs : Photonics/Optics
Optoelectronic Oscillators Based on Fiber-Optic Resonators

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 been used to obtain low phase noise in some previously developed OEOs. Although the proposal to use...

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 : Electronics & Computers
Analog VLSI Circuits for Hebbian Learning in Neural Networks

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 use in neural-network circuits. (In Hebbian synapses, the synaptic weights are modified through Hebbian...

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...

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 : Electronics & Computers
Compact, Rugged Enclosure for PC-Based Electronic Circuits

Figure 1 depicts a compact enclosure enabling the operation of personal-computer (PC)-based electronic circuits in harsh environments. The electronic circuits in question are commercial off-the-shelf Industry Standard Architecture (ISA) and Extended Industry Standard Architecture (EISA)...

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