An improved closed-loop, two-stage pulse-tube refrigerator provides 4 W of cooling power at a temperature of 15 K. The original intended application of this refrigerator is in preventing boiloff of liquid hydrogen from a propellant tank aboard a spacecraft. The basic refrigerator design can also be...

A report presents additional information about the Impairscope — an instrument for noninvasive meas- urement of fine neuromuscular control and, more particularly, for quantifying the degradation of neuromuscular performance under psychological stress. The instrument, previously called the...

A procedure has been devised for the use of steam to sterilize a water-purification cartridge, chrom- atographic column, or other closed packed column that is required to be kept filled with water and from which it is required to exclude air bubbles, which could impede flow. For the...

Electrostatic dust- collection systems that comprise wire grids connected to lightweight, low-power high-voltage sources have been invented for preventing the accumulation of dust on surfaces. Intended originally for use in keeping spacecraft solar panels free of dust, these systems could also be used on...

A report describes the completed first phase of a NASA/industry cooperative program of research on metal-matrix composites (MMCs) as lightweight, strong, high- temperature-resistant materials for use in future aircraft engines. The first phase of the research included assessment of life- and...

A report presents a study of the use of wavelet-based mathematical models to quantify the responses of humans in control loops. The report begins with a review of the traditional representation of manual control responses by use of transfer functions derived from Fourier transforms,...

A method of automated evolutionary synthesis of electronic circuits has been augmented by a concept called “morphing through fuzzy topologies.” Previous versions of the method provided for the evaluation of “crisp” topologies were precisely specified by open/closed (on/off)...

Integrated silicon microdisplays, such as liquid-crystal-on-silicon (LCOS) devices, are becoming the most effective image source for high-resolution viewfinders, head- mounted displays, and helmet-mounted displays (HMDs). Since these microdisplays are reflective in nature, they require...

Human factors engineering has been applied to the design of an overheadbridge crane control console for use by a seated operator in a clean-room environment. The crane console provides the operator with the ability to lift and move loads up to 27.5 tons (24.9 tonnes) in three vertical speed ranges and three...

Automated Rover Sequence Generation (ARSG) is a prototype computer program for ground-based automatic generation of sequences of commands that can be used for a robotic exploratory vehicle (rover) on Mars. ARSG is based on the Automated Scheduling and Planning Environment (ASPEN) computer...

Human data-transfer from space-shuttle checkout systems to shuttle business systems is slow, error-prone, and expensive. The Operations and Maintenance Requirement Specification-Automated Buy Off System (OMRS-ABOS) is a software system that automatically transfers test-validation data...

A computer program processes signal data in the instrument described in “Current- Signature Sensor for Diagnosing Solenoid Valves” (KSC-12152), NASA Tech Briefs, Vol. 25, No. 9 (September 2001), page 30. Ten-bit samples of the electric current in a solenoid valve are acquired at a rate of...

A computer program predicts the radiation forces on the TOPEX/ Poseidon satellite at any point in its orbit around the Earth. The program performs a unified analysis of the thermal, radiative, power-generation, and orbital-mechanics aspects of operation because these aspects are inter- dependent: The...

OwWwL and Agent- Nation are Java- language computer programs that act together, quickly scanning Internet databases for relevant information, then organizing the infor- mation into a format suited to the user. OwWwL is a search- engine program that, like other such programs, includes a “spider”...

Application Fault Injector (AFI) is a simple com- puter program for testing the fault tolerance of other programs. AFI is a library of subroutines designed to inject faults into memory, data structures, and registers. The library is modular, can easily be extended, and can easily be ported to different computer hardware...