May 2001

Briefs : Materials
Polyorganosiloxanes for Coating Porous Ceramic Insulation

Liquid and paste polyorganosiloxane formulations (which become high-temperature- and oxidation-resistant organosilicone-based ceramics upon curing) have been invented for use in (1) protecting porous, lightweight ceramic thermal insulation materials against aeroconvective thermal...

Briefs : Materials
Polyorganosiloxane Waterproofing for Porous Ceramics

Liquid waterproofing agents based on polyorganosiloxanes have been invented for use in treating porous, lightweight, fibrous ceramic thermal-insulation materials in both tile (rigid) and blanket (flexible) forms. Whereas silane-based waterproofing materials developed previously for this...

Briefs : Materials
Attachment of Small SiC Hoops to SiC-Based Ceramics and Composites

A technique for holding sensor lead wires in place on substrates made of SiC-based monolithic ceramic or SiC/SiC fiber-reinforced ceramic-matrix composite materials involves routing the wires through semicircular hoops that have been reaction-bonded to the substrates. These hoops...

Briefs : Materials
Improved Polymeric Composite Materials for Dental Fillings

Composite materials that include combinations of metal oxide and silica nanoparticles in polymeric matrices have been invented for primary use as dental fillings, dental and bone adhesives, and the like. There have been previous efforts to develop polymeric replacements for the amalgam...

Briefs : Materials
Polymer/Metal Laminate for Heat-Pipe and Radiator Envelopes

A thin polymer/metal laminate has been developed for use as an envelope material for lightweight heat pipes and heat-pipe radiators that operate at temperatures up to 360 K. The material is flexible enough to make it possible to roll or fold heat pipes compactly for transport and to...

Briefs : Materials
Hybrid Composite Structures Made From Polybenzoxazole Fibers

Hybrid composite-material (fiber/matrix) structures of a proposed type would incorporate recently developed polybenzoxazole (PBO) fibers that feature high strengths and high moduli of elasticity and which can be made in much thinner sections than are possible with graphite fibers. The...

Briefs : Test & Measurement
A Mass-Spectrometer System for Detecting Gas Leaks

The Hydrogen Umbilical Mass Spectrometer (HUMS) consists of an integrated sample delivery system, a commercial mass-spectrometer- based gas analyzer, and a set of calibration gas mixtures traceable to NIST (National Institute for Standards and Technology). The system, except for the calibration...

Briefs : Electronics & Computers
Oscillator-Stability Analyzer Based on a Time-Tag Counter

A proposed system for simultaneous characterization of the instability of several precise, low-noise oscillators of nominally equal frequency would be built around a commercially available time-tag counter. One of the oscillators would be deemed to be a reference oscillator, and each of...

Briefs : Electronics & Computers
Flexible Carrier-Signal-Tracking Loop for a Transponder

A proposed digital carrier-signal-tracking loop in a radio transponder could be programmed to operate in either a perfect-integration or an imperfect-integration mode. Although originally intended for use in a transponder aboard a spacecraft at a great distance from the Earth, the proposed...

Briefs : Electronics & Computers
Simplified Construction of Conical Log-Spiral Antenna

An improved design for a conical log-spiral antenna (see Figure 1) simplifies construction and improves alignment. The radiating-element substructure of such an antenna must be properly aligned with the signal-feed substructure to obtain the correct impedance match for efficient coupling of...

Briefs : Software
Programming Language for Automated Scheduling and Planning

The ASPEN Modeling Language (AML) has been developed for use in the Automated Scheduling and Planning Environment (ASPEN) software system. As described in prior NASA Tech Briefs articles, ASPEN is an object-oriented system that contains a modular, reconfigurable, reusable set of...

Briefs : Software
Communication Software for Distributed Application Programs

The Task Remote Asynchronous Message Exchange Layer (Tramel) software reduces the costs of distributing application programs across computer networks, including the Internet. Tramel implements robust, reliable, simple, highly portable interprocess communication, such that...

Briefs : Software
Software for Coordinating Multiple Exploratory Robots

A computer program coordinates the activities of multiple instrumented robotic vehicles of the "rover" type intended for use in scientific exploration. The program is a master/slave, distributed version of the ASPEN planning software, other versions of which have been reported in...

Briefs : Software
Program Creates Code to Parse Text

Saxj is a computer program that facilitates the development of programs that parse textual input in the Java programming language. Saxj is a parser generator that creates static Java parsers in the same sense in which YACC, Bison, and YACC++ are static parser generators that create static C-language...

Briefs : Software
Program Creates Java Lexical Analyzers

Luthorj is a computer program that creates static lexical analyzers in the Java programming language, in the same sense in which Flex and Lex create lexical analyzers in the C programming language. The majority of users of Luthorj are expected to be familiar with Lex, and Luthorj parses input files...

Briefs : Software
Program for Evaluating Spacecraft Designs and Missions

Design for X (DFX) is a computer program that assists, at the prelimary stage of planning, in the evaluaiton of alternative spacecraft designs and mission scenarios. The input required by DFX includes a set of operations goals (scientific and engineering goals and constraints), a...

Briefs : Mechanical & Fluid Systems
Micromachined Double Resonator

A double-resonator design has been devised for a cloverleaf-shaped silicon microelectromechanical resonator. The double-resonator design provides for an inner, higher-frequency resonator suspended on an outer, lower-frequency resonator. This design concept affords several advantages, as described below.

Briefs : Mechanical & Fluid Systems
Mechanical Breakaway Clutch

A proposed mechanical breakaway clutch would not rely on friction. The clutch would be useful in environments in which the inherent inaccuracies of friction would make friction clutches erratic. The proposed clutch would comprise two primary assemblies: a driver assembly and a slip flange. The slip flange would be...

Briefs : Mechanical & Fluid Systems
Molten-Carbonate Oxidation of Solid Waste

The molten-carbonate oxidation (MCO) process shows promise as a means of safe disposal and/or recycling of solid waste. The MCO process is being developed for use in regenerative life-support systems in outer space, but may also prove useful in managing institutional, industrial, and/or municipal solid...

Briefs : Mechanical & Fluid Systems
Water-Jet/Ultrasonic Removal and Real-Time Gauging of Paint

An improved robotic water-jet system for stripping paint from a ship or other large metallic structure is undergoing development. In addition to utilizing a high-pressure water jet to remove paint and a robotic crawler to scan the jet along the painted structure, the system utilizes...

Briefs : Manufacturing & Prototyping
Hermetic Wafer Bonding by Use of Microwave Heating

Microwave heating is the basis of a simple technique for quickly and gently bonding two metallized dielectric or semiconductor wafers to each other. The technique can be used, for example, to bond a flat, gold-coated silicon wafer to another gold-coated silicon wafer that is flat except for a...

Briefs : Medical
"Breathprint" Analysis of Microbial Communities

A technique for assessing changes in the densities and compositions of communities of microorganisms in environmental samples is based partly on redox chemistry. Suspensions of microbes from environmental samples are inoculated into 95-well microtiter plates. Each well contains an initially...

Briefs : Medical
Macroextraction for Purification of Nucleic Acids

A technique for extracting samples of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) for use in diagnosing and studying infectious and genetic diseases has been developed. The technique enables the concentration and purification of nucleic acids from large (in comparison with older...

Briefs : Physical Sciences
Simple Fiber-Optic Coupling for Microsphere Resonators

Simple fiber-optic couplers have been devised for use in coupling light into and out of the "whispering-gallery" electromagnetic modes of transparent microspheres. The need for this type of coupling arises in conjunction with the use of transparent microspheres as compact, high-Q (where Q is...

Briefs : Physical Sciences
Surface Gratings for Optical Coupling With Microspheres

A diffraction grating consisting of a periodic gradient in the index of refraction of a thin surface layer has been shown to be effective as a means of far-field coupling of monochromatic light into or out of the "whispering-gallery" electromagnetic modes of a transparent microsphere. This...

Briefs : Photonics/Optics
High-Performance Micromachined Linear Arrays of Thermopiles

Linear arrays of thermopile infrared detectors made of high-performance thermoelectric materials have been fabricated on silicon substrates by micromachining processes. Such detector arrays can be useful in dispersive spectrometers for chemical analyses, including exhaust and...

Briefs : Photonics/Optics
Dual-Target, Single-Laser Metrological System

A single-laser-based, heterodyne optoelectronic system that measures the displacements of two targets along the same lines of sight has been developed. Heretofore, it would have been necessary to construct a two-target laser metrological system as two partly or wholly independent subsystems, each...

Briefs : Photonics/Optics
Spatially Modulated Prism Interferometer

A spatially modulated prism interferometer (SMPI) has been developed that overcomes the complexities of traditional interferometers and the inherent limitations of diffraction gratings, dispersion prisms, and spectral selection filters. Applications include atmospheric sounding, geologic mapping,in-situ...

Briefs : Photonics/Optics
Optics for Compact, High-Performance Imaging Spectrometers

Several high-fidelity imaging spectrometers have been designed with convex diffraction gratings for wavelengths ranging from the ultraviolet to the thermal infrared. All the designs are telecentric and can be combined with a flat-field, three-mirror anastigmatic telescope that also...

Briefs : Photonics/Optics
Determining Particle Sizes From Scattered-Photon Statistics

A method of determining sizes of particles suspended in liquids and engaging in Brownian motion involves statistical analysis of counts of photons of laser light scattered by the particles. The method can be implemented by a compact, portable apparatus that can be used, for example, in...

Briefs : Photonics/Optics
Snapshot SEM Imaging of Moving MEMS Structures

A stroboscopic scanning electron microscope (SEM) has been proposed as a means of generating still or slow-motion pictures of moving structures in microelectromechanical systems (MEMS). Such imaging is used in characterizing the dynamics of MEMS; characterization of the dynamics is a critical...

Briefs : Test & Measurement
A Mass-Spectrometer System for Detecting Gas Leaks

The Hydrogen Umbilical Mass Spectrometer (HUMS) consists of an integrated sample delivery system, a commercial mass-spectrometer-based gas analyzer, and a set of calibration gas mixtures traceable to NIST (National Institute for Standards and Technology). The system, except for the calibration...

Briefs : Photonics/Optics
Imaging Lidar System Would Map Surface Heights

A proposed optoelectronic system based on imaging-lidar and differential-altimetry techniques would generate data equivalent to a height map of a surface area. Originally conceived for use in determining spatial-frequency characteristics of ocean waves with high temporal resolution, the system...