June 2002

Briefs : Mechanical & Fluid Systems
Hexfoil Rotary Flexures

Hexfoil rotary flexures have been proposed as pivots suitable for use in precise optical instruments. In the application that inspired the hexfoil concept, there is a requirement for a limited-rotation mirror gimbal that would maintain, with unprecedented accuracy, coincidence among the axes of rotation and a fiducial...

Briefs : Physical Sciences
Making Hydrogen by Electrolysis of Methanol

Scientists at NASA's Jet Propulsion Laboratory are developing apparatuses for electrolysis of methanol to produce pure hydrogen for use at industrial sites, in scientific laboratories, and in fuel cells. The state-of-the-art onsite hydrogen generators now in use are based on electrolysis of water to...

Briefs : Electronics & Computers
Remote Monitoring and Alarm System

The Remote Monitoring and Alarm System (RMAS) is a system of electronic hardware and software for monitoring of fiber-optic video transmission equipment at Kennedy Space Center (KSC). The RMAS could also monitor other equipment that generates discrete contact closures and/or analog voltages. The hardware...

Briefs : Electronics & Computers
Failure-Reporting Device Concept for Spacecraft and Remote Vehicles

Failure-reporting devices somewhat similar to the “black box” data recorders on aircraft have been proposed. These devices were conceived for use on spacecraft, but might also be useful on terrestrial autonomous underwater vessels or terrestrial remote exploratory robots....

Briefs : Software
Program Uses Terrain-Image Data To Locate Safe Landing Site

A computer program under continuing development strives to locate a safe landing site for a spacecraft through realtime processing of image data acquired by a video camera aimed at the terrain below while the spacecraft descends. The program might also be useful for aiding the selection...

Briefs : Information Technology
Measuring Sea Height and Roughness With GPS Reflections

A proposed technique of bistatic radar altimetry would utilize information available in Global Positioning System (GPS) signals reflected from the ocean surface. The signals would be monitored by an airborne or spaceborne receiver and would be processed to determine the height, roughness,...

Briefs : Electronics & Computers
Hybrid Electric-Field Sensor

The hybrid electric-field sensor (HEFS) has been proposed for measuring quasi-static electric fields — especially those associated with thunderstorms. The HEFS would combine the relative compactness, low cost, and low power consumption of prior inductionprobe- type electric-field sensors with the higher sensitivity...

Briefs : Electronics & Computers
Communication Antenna in a Helicopter Rotor

A proposed communication antenna for a helicopter would feature radiating elements in or on the blades of the main rotor, with a novel rotary radio-frequency coupling between the antenna and the radio equipment in the fuselage. The antenna would be suitable for communication along both predominantly...

Briefs : Electronics & Computers
GPS Attitude Determination Using Nonaligned Antennas

A method of determining the attitude of a vehicle equipped with a Global Positioning System (GPS) receiver with multiple nonaligned antennas has been invented. As used here, “nonaligned antennas” does not signify antennas that lack alignment; rather, it signifies antennas that generally...

Briefs : Electronics & Computers
A Semiautomated Coordinate-Measuring System

The Advanced Payload Transfer Measurement System (APTMS) comprises electromechanical sensors and sensor output-processing circuits. Designed specifically for measuring offsets between spacecraft payload trunnions and trunnion supports during ground-based payload-transfer operations, the APTMS could be...

Briefs : Software
Software Provides Thermal Optimization of a Computer CPU

Heat is the primary enemy of any electronic component. In order for an electronic device to have a long, problem-free life, cooling must be an important design consideration. The problem of cooling CPUs, in particular, has grown as processors have become more powerful. Water cooling...

Briefs : Software
Software for Automated Planning of Spacecraft Missions

An artificial-intelligence computer program generates and evaluates plans for spacecraft missions subject to constraints associated with spacecraft designs. The input to the program includes spacecraft design parameters (e.g., slew rates and battery capacities) and mission parameters (e.g.,...

Briefs : Photonics/Optics
Generalized-Time-Line Program for Planning and Scheduling

Generalized Timelines API is a computer program that provides (1) a means of representing arbitrary realworld state and resource information for use in planning, scheduling, and plan- and schedule-executing software and (2) an application-programming interface (API) that accelerates the...

Briefs : Mechanical & Fluid Systems
Improvements in the Use of Water Washes in Testing for NVR

Some improvements have been made to enhance the role of water as a test solvent for determining the amount of hydrocarbon nonvolatile residue (NVR) present on an item of hardware that is required to be totally or nearly devoid of such residue. Water is now used as an NVR-testing solvent...

Briefs : Materials
Using Polyimide Tape To Mask Against Reactive-Ion Etching

Polyimide tape (Kapton™ or equivalent) has been found to be effective as a material for masking selected areas of a semi- conductor wafer that is about to be processed in a reactive-ion etching (RIE) apparatus. The conventional etch- resistant masking materials for protecting selected...

Briefs : Mechanical & Fluid Systems
Flight Research on Supersonic Laminar Flow

Some airfoil designs have been shown by theory and small-scale tests to be capable of passively maintaining laminar flow at super -sonic speeds. More recently, flight tests have proven that these designs can maintain large runs of laminar flow at higher Reynolds numbers in harsh flight environments. The...

Briefs : Mechanical & Fluid Systems
Improved Flange Design for Cryogenic Vacuum O-Ring Seals

A compact spring-loading design has been proposed to increase the reliability of seals in the joints of vacuum cryogenic systems. Heretofore, such joints have been, variously, compact or reliable, but not both, for the following reasons: In all such joints, sealing is effected by...

Briefs : Physical Sciences
Aircraft-Mounted Cloud-Water-Content Probe

An aircraft-mounted instrument for high- resolution, in situ measurement of the abundances of liquid water and ice in clouds is undergoing development. This instrument is intended to overcome the dis- advantages of instruments developed previously for the same purpose. The disadvantages include various...

Briefs : Physical Sciences
Miniature NMR Spectrometers Without Magnets

Miniature, lightweight nuclear-magnetic-resonance (NMR) spectrometers suitable for characterizing ferromagnetic minerals in the field are undergoing development. In previously developed miniature NMR spectrometers, more than half the weight is contributed by permanent magnets. The present developmental...

Briefs : Electronics & Computers
MEMS Design Optimization With FEA

This report examines design considerations in one of the most promising new areas of engineering – Micro Electro Mechanical Systems (MEMS). Designing and optimizing MEMS devices involves unique challenges, including analyzing the inter- dependent physical phenomena to which MEMS devices are sensitive and...

Briefs : Electronics & Computers
Further Developments Regarding Noise-Reducing Slots in QWIPs

A report presents additional information on the devices described in “Noise-Reducing Slots in Quantum-Well Infrared Photodetectors” (NPO-20518), NASA Tech Briefs, Vol. 25, No. 6 (June 2001), page 6a. To recapitulate: it was proposed that incorporation of suitably dimensioned...

Briefs : Information Technology
Time-Parallel Algorithms for Solving PDEs

A report presents additional details about a class of massively parallel algorithms for finite-difference numerical solution of time-dependent partial differential equations (PDEs). Some aspects of these algorithms were described in two previous articles in NASA Tech Briefs; namely, “Massively Parallel...

Briefs : Mechanical & Fluid Systems
Algorithm Computes Kinematics of a Rover on Rocky Terrain

The Rover Analysis Modeling and Simulation (ROAMS) algorithm is to solve the kinematics of a wheeled mo- bile robot (rover) traversing on a rocky terrain. The rover is constructed using a “rocker-bogey-differential” type suspension and steering system as shown in the figure. By...

Briefs : Motion Control
Software for Simultaneous Control of Three Magnetic Bearings

Five-Axis, Three-Magnetic-Bearing Control Code (FATMaCC) is a C++-language computer program for controlling a magnetic thrust bearing in one degree of freedom and two magnetic radial bearings, each in two degrees of freedom. These bearings levitate a vertical-axis rotor for experiments...

Briefs : Motion Control
Crowned Races for Crossed Roller Bearings

Crowned races have been proposed for crossed roller bearings. Crowning of the races is expected to reduce scuffing of the cylindrical rollers. Crowning of the races is expected to be especially beneficial in bearings made of polymers (instead of metals) to reduce weight.

Briefs : Photonics/Optics
Fabricating Sapphire Optical Fibers for High-Temperature Use

A process for the fabrication of coated sapphire multimode optical fibers has been developed. Sapphire multimode optical fibers are suitable for use as embedded sensors for measuring mechanical and thermal stresses and strains in material specimens at temperatures up to about 1,500...

Briefs : Motion Control
Improved Array of Switches for Fiber-Optic Communications

A rectangular array of Y-junction electro-optical switches has been proposed as a prototype of reliable, high-speed cross-point switches for fiber-optic-based photonic communication systems. The proposed array would feature a hybrid digital/interference design. The proposed array would...

Briefs : Photonics/Optics
Microcavity Device for Measuring Direction of a Laser Beacon

An optoelectronic device based on interferometry in a resonant microcavity has been proposed for use in measuring the direction of arrival of a circularly polarized beam of light from a beacon laser. In comparison with prior optoelectronic direction sensors, the proposed device would...

Briefs : Photonics/Optics
Etching Mirror Facets on SOI Optical Waveguides

A process that would include a combination of dry and wet chemical etching has been proposed for making facets for low-loss mirrors on silicon-on-insulator (SOI) optical waveguides. Heretofore, such facets have been made by a process that includes dicing and polishing. This process is...


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