October 2000

Briefs : Information Technology
MDICE: Software System for Multidisciplinary Computing

The Multi-Disciplinary Computing Environment (MDICE) is a software system for multidisciplinary analysis of complex engineering equipment, processes, and systems. Currently MDICE supports a variety of disciplines, including parametric computer aided design (CAD), grid generation,...

Briefs : Information Technology
Electronic Storage and Retrieval of Engineering Documents

The KSC Electronic Documentation System (KEDS) is a computer-intranet system at Kennedy Space Center (KSC) for the storage and retrieval of engineering drawings and other engineering documents that have been officially released. Prior to the development of the KEDS, microfilm copies of...

Briefs : Information Technology
Software Assists in the Development of Optimization Models

Optimization Modeling Assistant (OMA) is an expert-system computer program that assists its users in the development of mathematical and algorithmic models for optimization. As used here, "optimization" refers to a suite of powerful decision-support techniques that enable the modeling of...

Briefs : Information Technology
Interface Program for Generation of Computational Grids

Computer Aided Grid Interface (CAGI) is a computer program that serves as an interface between computer-aided design/computer-aided manufacturing (CAD/CAM) programs and computational fluid dynamics (CFD) programs. CAGI reads Initial Graphics Exchange Specification (IGES) files from CAD/CAM...

Briefs : Mechanical & Fluid Systems
Software Predicts Impacts of Orbital Debris on Spacecraft

The EXOS computer program numerically simulates impacts of orbital debris on spacecraft. EXOS can be used to simulate meteoroid- and orbital-debris-impact damage to commercial satellites, and to simulate effects of weapons on personal and vehicular protection systems. With further...

Briefs : Electronics & Computers
Tunable Terahertz Source Based on Near-Infrared Diode Lasers

The figure schematically depicts a heterodyne photonic apparatus built around three continuous-wave, near-infrared diode lasers. This apparatus generates electromagnetic radiation at an adjustable, precisely defined frequency in the terahertz range. The spectral width of the signal is...

Briefs : Electronics & Computers
Highly Efficient Thermoelectric Unicouples

Advanced unicouples that contain carefully tailored combinations of thermoelectric materials are being investigated in an effort to develop thermoelectric power generators that would operate with relatively high energy-conversion efficiencies between heat-source temperatures of about 1,000 K and...

Briefs : Test & Measurement
Room-Temperature Infrared Instrument Detects Trace Gases

A compact, portable, mid-infrared, laser-based instrument that operates at room temperature has been developed for use in detecting trace concentrations of CO or any of several other gases in air. The instrument utilizes infrared absorption spectroscopy in a sample cell which either holds...

Briefs : Test & Measurement
Personal Cabin Pressure Alarm

Compact instruments, similar in appearance to common personal pagers, have been proposed for warning aircraft crewmembers that cabin air pressure has decreased to a potentially dangerous level. An instrument of this type, called a "personal cabin pressure monitor and warning system" (PCPMWS), implements a warning...

Briefs : Mechanical & Fluid Systems
Software Predicts Noise From Rotor-Wake/Stator Interactions

V072 is a computer program that predicts the noise generated by the interaction between the rotor-blade wake (fan wake) and the stator vanes of a turbofan engine. The program is a combination of subroutines from prior NASA programs, with many added features.

Briefs : Software
Software for Obtaining Ideal SAR Chirps

A computer program introduces a predistortion into the chirp signal used to frequency-modulate a synthetic-aperture-radar (SAR) signal at the transmitter. The predistortion is intended to compensate for distortions introduced by nonideal performance of the various pieces of SAR equipment — especially the...

Briefs : Mechanical & Fluid Systems
Interlocking Wing-Leading-Edge Thermal-Protection Tiles

Insulating tiles with interlocking shaped gaps have been developed for use in protecting the leading edges of the wings of aerospacecraft against excessive heating during hypersonic flight (including re-entry into the atmosphere). Other thermal-protection systems have been studied for this...

Briefs : Manufacturing & Prototyping
Glass Cure Plates for Fabricating Flat Composite Panels

Glass plates are used as cure plates in a modified process for the fabrication of flat composite-material (matrix/fiber) panels. In the unmodified previous version of the process the cure plates were made of aluminum.

Briefs : Physical Sciences
Modifications of a Hydrazine Fueling Procedure and Equipment

A combination of procedure and equipment for loading liquid hydrazine into a spacecraft fuel tank that contains a diaphragm or bladder would be modified, according to a proposal. The purpose of the modifications is to enable fueling technicians to work safely, during all but a small...

Briefs : Physical Sciences
Ultrasonic Bubble-Sizing Instrument

An ultrasonic instrument has been developed for measuring the sizes of bubbles in the human body. A primary example is that of bubbles associated with decompression sickness (the "bends"); these bubbles consist mostly of nitrogen and can occur in both blood vessels and extravascular tissues. The bubbles can...

Briefs : Information Technology
Analyzing Time Series Using EMD and Hilbert Spectra

A recently developed theoretical and computational method is especially well suited for analyzing time-series data that represent nonstationary and nonlinear processes. The method stands in contrast to classical methods, including Fourier analysis, that are generally applicable only to periodic...

Briefs : Materials
Development of Progressive-Failure-Analysis Software

A report discusses the development of the GENOA-PFA computer program, which was described in "Software for Simulating Progressive Fracture in Braided PMCs" (LEW-16845), NASA Tech Briefs, Vol. 24, No. 3 (March 2000), page 52; and "Update on a Progressive-Failure-Analysis Software System...

Briefs : Physical Sciences
Surface and Gas Temperatures via Multiwavelength Pyrometry

A report describes experiments using multiwavelength pyrometry to determine the surface temperature of the end tip inside a BeO cylinder that is part of a probe designed to measure high-temperature gases. The cylinder is heated by the gas into which it is inserted, and the gas...

Briefs : Physical Sciences
Tribology for Aerospace Applications

"Tribology for Aerospace Applications" is a textbook and reference source written for designers of rotating machinery; users and designers of such mechanical components as bearings, gears, and seals; tribologists; university and industrial researchers; and students of machine design. The book incorporates...

Briefs : Materials
SiC/SiC Composites With Improved BN Coating on Fibers

A method of fabricating composites of pretreated silicon carbide fibers in silicon carbide matrices provides for the formation of improved boron nitride fiber/matrix interfacial layers. As explained below, these BN layers help to deflect matrix cracks away from the fibers.

Briefs : Materials
Carbon-Filled EPDM Rubbers as Ablative Insulating Materials

Carbon-fiber-filled polymers made from ethylene propylene diene monomer (EPDM) have been found to be useful as ablative thermal-insulation materials. Like the silica-filled EPDM polymers described in the preceding article, these polymers have been investigated as candidates to replace...

Briefs : Materials
Graphite/Conductive-Epoxy Electromagnetic Shielding

Lightweight shields for electromagnetic interference (EMI) can now be fabricated from composites of (1) electrically conductive fibers made of bromine-intercalated graphite in (2) matrices of electrically conductive epoxy. As shown in more detail below, the shielding ability of a given...

Briefs : Materials
Composite-Material Pipes for Corrosive and Cryogenic Liquids

A flexible design concept and an associated method of fabrication have been conceived as means to satisfy growing demands for lightweight composite-material pipes for corrosive and cryogenic liquids. The design concept and method can be applied to produce piping systems capable of...

Briefs : Motion Control
Rolling-Piston Compressor With Flow-Through Lubrication

The figure presents a simplified and partly schematic view of a two-stage rolling-piston compressor that is undergoing development for use as the prime mover in a vapor-compression heat pump. In comparison with equally rated compressors used heretofore in vapor-compression heat pumps, this...

Briefs : Motion Control
Closed/Momentary-Opening/Closed Solenoid Valve

A proposed solenoid-actuated valve would open for a short time to pass a very small quantity of fluid. The valve could be used to meter a specified total quantity of the fluid through repeated actuations.

Briefs : Manufacturing & Prototyping
Using Light To Fabricate Photonic Devices

A developmental apparatus and process for the fabrication of photonic devices utilize intense, focused laser light projected and/or diffracted in controlled patterns. The apparatus and process can be used in a microgravitational environment to form microscopic three-dimensional device structures (e.g.,...

Briefs : Motion Control
Formulation and Algorithm for Multi-Flexible-Body Dynamics

An improved formulation of the dynamics of multiple flexible bodies coupled via joints, and an algorithm that implements the formulation, have been developed at Johnson Space Center (JSC). A robot arm with multiple, somewhat flexible links is a prime example of a dynamic system to which...

Briefs : Electronics & Computers
Scanning Probe Position Encoder Yields Subnanometer Precision

In today's manufacturing world, the need for ultraprecise position measurement and control grows as feature sizes shrink in the semiconductor industry and the world of microelectromechanical systems (MEMS) impinges on conventional manufacturing. Now NanoWave, a startup company with...

Briefs : Motion Control
Myoelectric Teleoperation for Robotics and Prosthetics

Johnson Space Center is sponsoring continuing research on the use of myoelectric signals to control dexterous robotic and prosthetic hands. This research is expected to advance the state of the art beyond that of today's most common, commercially available, myoelectrically controlled...

Briefs : Electronics & Computers
Microelectromechanical SPDT Switches

Microelectromechanical single-pole, double-throw (SPDT) switches with predominantly planar configurations have been proposed for use in radio-frequency (RF) circuits. These switches would have overall dimensions of the order of a few millimeters and would be fabricated by micromachining techniques compatible...

Briefs : Manufacturing & Prototyping
Making Submicron Features by Ion Etching Through PMMA Masks

Experiments have shown that a substrate can be patterned with submicron features by the following procedure:

Briefs : Materials
Reactive-Ion Etching of Smooth Vertical Walls in Silicon

An advanced technique of deep reactive-ion etching (DRIE) has been developed for fabricating smooth vertical walls in silicon wafers. These walls are suitable for use as bounding surfaces of optical waveguides in photonic and optoelectronic devices. The roughness of a typical 8-µm-high...

Technology Leaders