February 1998

Briefs : Mechanical & Fluid Systems
Latch-Release Pin Puller With Shape-Memory-Alloy Actuator

The figure illustrates one of several related pin-puller mechanisms that harness the recovery characteristics of a shape-memory alloy (SMA). Like some other SMA-actuated mechanisms described previously in NASA Tech Briefs, this pin puller is suitable for use in place of a pyrotechnically...

Briefs : Electronics & Computers
Coplanar-Stripline Transition and Band-Stop Filters

Three coplanar-stripline circuits have been designed to perform coupling and filtering functions in microwave systems. These circuits could be incorporated into feed networks for microwave antennas, for example. One of the circuits comprises two back-to-back coplanar-strip-to-microstrip...

Briefs : Electronics & Computers
Transmitting Data Signals via Fiber-Optic Power Lines

Data signals can be transmitted via the same optical fibers that are used to transmit power from base stations to remote stations containing sensors and associated circuitry. [A prototype system based on fiber-optic transmission of data and power is described in "General-Purpose Optically...

Briefs : Physical Sciences
Oscillating-Flow Heat-Transfer and Pressure-Drop Test Rig

The figure illustrates an apparatus for measuring heat-transfer and pressure-drop characteristics of porous plug specimens in oscillating flows. The apparatus is built around an oscillating-flow test rig that was originally designed for pressure-drop (but not heat-transfer) measurements...

Briefs : Materials
Testing Corrosion Prevention in Reinforced Concrete

An accelerated-testing method has been developed for evaluating the effectiveness of various measures taken to prevent the corrosion of steel reinforcing bars ("rebars") cast into concrete. Such measures can include chemical admixtures incorporated into the concrete, coatings, penetrants,...

Briefs : Medical
Compact, Noncontact Fiber-Optic Probe for Diagnosis of Eye Diseases

A compact fiber-optic probe has been found to be useful for noncontact diagnosis of interior parts of eyes. The probe was originally developed for performing dynamic-light-scattering measurements to determine transport properties of submicron particles suspended in fluids in...

Briefs : Photonics/Optics
Multicolor Transceiver for Optoelectronic Communication

A great increase in the effectiveness of fiber optic systems is possible with a device that allows for simultaneous two-way signalling of multiple data streams on a single optical fiber. By using a highly efficient multijunction solar cell to emit as well as detect two or more distinct...

Briefs : Physical Sciences
Generalized Mathematical Model of Pyrolysis of Biomass

A generalized mathematical model has been devised for use in analyzing the pyrolysis of arbitrarily specified (but typical) biomass feedstocks at atmospheric pressure. The model represents both the microparticle (kinetically controlled) and macroparticle (diffusion-limited) types of...

Briefs : Mechanical & Fluid Systems
Wheel Drive of Mars Rover

A brief report summarizes the design of the lightweight, high-torque wheel drive of a small robotic vehicle used to explore the surface of Mars. Planetary gearing was selected for compactness and high torque capability. The input stages were fitted with ball bearings to survive the cold (down to -100 °C) Martian...

Briefs : Electronics & Computers
Antiovershoot Position Control for Motors Run at Full Speed

An improved motor controller provides a circuit that will allow a motor to run at full speed while traveling from point A to point B, and still be able to obtain the desired damping coefficient when reaching point B. Previously, a motor would overshoot its desired stopping point when...

Briefs : Motion Control
Precision Actuator Positions Laser Grating

The tunable external cavity diode laser is an important new tool used to evaluate and test the latest fiber-optic components and building blocks of modern telecommunications systems. A key factor enabling operation of this type of laser is the ability to angle-tune the wavelength-dependent key component...

Briefs : Materials
Highly Selective Gas-Phase Etching of Silicon

A technique of gentle, highly selective gas-phase etching of silicon has been devised to enable the fabrication of microelectromechanical devices integrated with electronic circuits. For example, newly fabricated complementary metal oxide/semiconductor (CMOS) integrated-circuit chips can be...

Briefs : Materials
High-Performance Thermal Insulation for a Racing Car

Thermal-insulation blankets developed for use aboard the space shuttle can be adapted to a racing car to protect the driver against excessive cockpit heating. [Also see an earlier article under "Mission Accomplished," NASA Tech Briefs, Vol. 20, No. 8 (August 1996) page 20.] Thermal protection...

Briefs : Electronics & Computers
Signaling-and-Detection Scheme for Beacon Monitoring

A signaling-and-detection scheme has been proposed for use in conjunction with the remote-monitoring concept described in "Beacon Monitoring Would Reduce Interactions With Remote Systems" (NPO-19706), NASA Tech Briefs, Vol. 21, No. 5 (May 1997), page 54. To recapitulate: A remote system (a...

Briefs : Robotics, Automation & Control
Manipulator System for a Robotic Vehicle

A prototype manipulator system that includes two different arms has been tentatively selected for use on a semiautonomous robotic vehicle called Rocky 7 (see figure). [A previous version of this vehicle with a single manipulator arm was described in "High-Performance Robotic Vehicle" (NPO-19921) NASA Tech...

Briefs : Physical Sciences
Automated Window Inspection Device

The Automated Window Inspection Device (AWID) is a prototype apparatus for computer-controlled, noncontact inspection of windows, with reproducible positioning and electronic recording of data on the locations, sizes, and depths of flaws. The AWID was developed to accelerate and facilitate (1) postflight...

Briefs : Photonics/Optics
Multimode Optical Fiber as Imaging Probe

A proposed electro-optical image-processing system would enable remote viewing of an object through a multimode optical fiber, as though the fiber were a conventional image-transmitting optic like a lens or prism. Ordinarily, it would be impractical to use a multimode optical fiber as an imaging probe or...

Briefs : Mechanical & Fluid Systems
High-Wind Masts for Meteorological Instruments

Rigid, guyed masts of a proposed type for supporting meteorological instruments would be designed to withstand considerably stronger winds than those conventionally used. The proposed fairings would also help minimize perturbations of airflows and thereby minimize the contaminating effects of the...

Briefs : Physical Sciences
Mathematical Model of Pyrolysis of Biomass Particles

A mathematical model of a special class of solid/fluid chemical reactions has been developed for use in analyzing the pyrolysis of particles of cellulose, wood, and similar biomass materials. Although it involves some simplifying assumptions (as do all models of chemical and physical...

Briefs : Physical Sciences
Mathematical Model of a Direct-Contact Pyrolysis Reactor

A mathematical model has been developed for use in assessing the performances of direct-contact pyrolysis reactors used to convert particles of raw biomass materials (usually small wood chips) into char, tar, and gas. The optimal designs are here considered to be those that maximize the...

Briefs : Physical Sciences
Protecting a Micromachined Accelerometer During Handling

A highly sensitive micromachined accelerometer that is intended to be exposed to very small accelerations during operation incorporates features for protection against much larger accelerations during handling and transport. More specifically, the accelerometer is designed to measure...

Briefs : Information Technology
Software for Improving Operational Processes

The Schedule and Cost Risk Analysis Modeling System (SCRAM) computer program identifies important sources of schedule and cost risks in an operational process. The related Process Analysis and Improvement Support System (PASS) program assists in the overall analysis and improvement of an operational...

Briefs : Electronics & Computers
Multimedia Operator Interface for a Health-Care Robot

An operator interface is undergoing development along with other subsystems of a robot that would assist in caring for elderly and disabled patients. This development has been initiated in anticipation of an increasing need for long-term care, in both home and hospital environments, with...

Briefs : Information Technology
Software for Planning in a Hierarchical Processing Environment

Decision-support software based on discrete-event simulation (DES) has been undergoing development for use in planning and scheduling work in the Orbiter Processing Facility (OPF) at Kennedy Space Center. The software is also suitable for adaptation to similar use in other facilities...

Briefs : Physical Sciences
Evaluation of Droplet-Evaporation Models for Gas/Liquid Flow

A report presents an evaluation of eight mathematical models of the evaporation of liquid droplets — models that are used in the numerical simulation of a variety of gas/liquid flows, including cooling sprays, burning liquid-fuel sprays, fire-suppression sprays, and...

Briefs : Software
Program for Simulating Dynamics of Multibody Systems

The Dynamics Algorithms for Real-Time Simulation (DARTS) computer program solves the equations of motion of tree-topology, flexible, and/or multibody mechanical systems as diverse as molecules, mechanisms, robots, spacecraft, and ground vehicles. It has proven to be particularly useful for...

Briefs : Electronics & Computers
Hybrid Superconductor/Semiconductor Planar Oscillators

Hybrid high-temperature-superconductor (HTS)/semiconductor planar oscillator circuits that operate at a frequency of 8.4 GHz have been developed. In the original intended application, one of these circuits would serve as a local oscillator in a cryogenic heterodyne receiver in a spaceborne...

Briefs : Information Technology
Work-Measurement and Methods-Analysis Studies of the OPF

Two reports describe early phases of continuing studies directed toward the selection and adaptation of industrial work-measurement and methods-analysis procedures for application to the Orbiter Processing Facility (OPF) at Kennedy Space Center. These studies were prompted by a need to...

Briefs : Photonics/Optics
A High-Repetition-Rate Optical Communications Source

High-speed communications, medical applications, and semiconductor processing would all benefit from a laser that can produce stable, high-repetition-rate pulses at 1.55 micrometers. One goal of the Naval Research Laboratory's program in ultrahigh-speed communications research is to develop...

Briefs : Photonics/Optics
Transmitting Power to Sensor Circuitry via Modulated Light

Modulated (as opposed to steady) light can be used in the optical transmission of power to remotely located sensor circuitry in a system like that described in the preceding article, "General-Purpose Optically Powered Sensor and Control System" (NPO-19604). This is analogous to the use...

Briefs : Physical Sciences
Elevation Corrections for Absolute-Pressure Measurements

A method of correcting absolute-air-pressure measurements for small differences in the elevations of pressure taps and pressure transducers has been devised. The variation in air pressure with elevation is well documented; nevertheless, in such disciplines as process control and...

Briefs : Mechanical & Fluid Systems
Self-Contained Impact-Type Damper for Bellows-Type Face Seals

A self-contained impact-type damper for a bellows-type face seals suppresses dynamic instability or chatter. In current practice, damping in a typical seal is accomplished through rubbing contact between a ground (a stationary member) and a bellows or carrier as the seal translates....

Briefs : Electronics & Computers
General-Purpose Optically Powered Sensor and Control System

The figure schematically illustrates a prototype general-purpose, microprocessor-based sensor and control system in which power, data, and control signals are transmitted via optical fibers. This system serves as an experimental model for the further development of networks of remote...

Briefs : Information Technology
Model for Investigating Human Factors in an Organization

The Kennedy Space Center Human Factors Event Evaluation Model is a model to facilitate long-term gathering and analysis of data to investigate the effects of human factors on the operations of a complex organization. The model was developed specifically for use in comprehensive...

Briefs : Robotics, Automation & Control
All-Terrain Vehicle With Self-Righting and Pose Control

A small prototype robotic all-terrain vehicle features a unique drive and suspension system that affords capabilities for self righting, pose control, and enhanced maneuverability for passing over obstacles. The vehicle is designed for exploration of planets and asteroids, and could just...

Briefs : Photonics/Optics
Measuring Flow Using Spectrally Resolved Rayleigh Scattering

An experimental study has been conducted to demonstrate the feasibility of using spectrally resolved Rayleigh scattering to nonintrusively measure the instantaneous properties of the flow in a small supersonic wind tunnel. Unlike conventional probe flow measurements, Rayleigh...

Briefs : Information Technology
Consortium Benchmarking in a Competitive Environment

The Kennedy Benchmarking Clearinghouse (KBC) is an organization for implementing an emerging methodology called "consortium benchmarking" in a competitive business environment. The partners in the KBC include NASA Kennedy Space Center and a number of its contractors. Within the KBC, the...

Briefs : Physical Sciences
Thermographic Detection of Defects in Refractory Composites

Significant effort and resources are being expended to develop ceramic-matrix composite (CMC), metal-matrix composite (MMC), and polymer-matrix composite (PMC) materials for high-temperature engine components and other parts in advanced aircraft. The development of composite materials...

Briefs : Photonics/Optics
Pulse Shepherding in Nonlinear Fiber Optics

Pulse shepherding is a nonlinear signal-propagation phenomenon that can occur when several pulses of light at different wavelengths are launched simultaneously or nearly simultaneously along the same single-mode optical fiber under suitable conditions. As its name suggests, pulse shepherding involves...

Briefs : Software
Software for Scheduling Use of Shared Resources

The Quick Utility for Intelligence Planning and Scheduling (QUIPS) computer program automates the scheduling of resources that must be shared among multiple tasks or groups. Designed to aid coordination of military intelligence operations at the division and brigade levels, QUIPS might also prove...

Briefs : Mechanical & Fluid Systems
Passive Magnetic Bearings With Ferrofluid Stabilization

Permanent-magnet rotary bearings with ferrofluid stabilization in the axial degree of freedom are undergoing development. These bearings are totally passive, yet stable in all degrees of freedom. In contrast, previously developed electromagnet and permanent-magnet bearings all exhibit...

Briefs : Motion Control
Large Gimbal Mount Enables Focal-Plane Testing

The latest missile guidance and tracking guidance systems deliver unprecedented performance, in terms of range, precision, and the ability to function in very unfavorable atmospheric conditions. These systems rely on a new generation of high-resolution, multifunction focal plane arrays to image...

Briefs : Electronics & Computers
ASIC for Viterbi Decoding With 2 ≤ K ≤ 15 and 1/2 ≥ r ≥ 1/6

An application-specific integrated circuit (ASIC) serves as a building block for a digital system that effects maximum-likelihood decoding of a Viterbi code (a binary convolutional error-correcting code) with a constraint length (K) in the range of 2 through 15 and a rate (r) in...

Briefs : Electronics & Computers
Fabricating Diffusion-Cooled Hot-Electron-Bolometer Elements

Microbridges that constitute the superconducting-transition sensory elements of electron-diffusion-cooled hot-electron bolometers can now be fabricated in increased yield and quality. This improvement is made possible by a fabrication process that notably includes the use of a...

Briefs : Software
Software for Processing SAR Images of the Polar Oceans

The RADARSAT/ERS-1,2 Geophysical Processor System (RGPS) is an automated system of hardware and software that processes synthetic-aperture-radar (SAR) images of ice and open water in polar oceans to generate higher-level geophysical-data products. Information in such products includes the...

Briefs : Information Technology
Diagnosing Helicopter Gearboxes Using Connectionist Networks

A method of automated diagnosis of helicopter gearboxes involves processing of selected features of digitized outputs of vibration sensors via structure-based connectionist networks (SBCNs), which are mathematical constructs that incorporate elements from the disciplines of dynamical...

Briefs : Software
Software for Development of Spacecraft-Simulation Programs

DARTS Shell (Dshell) is a multimission spacecraft simulator for the development, integration, and test of flight software and hardware. Dshell reduces the time and cost of developing simulation programs by enabling the development of the software in modular, reusable form and by...

Briefs : Physical Sciences
Mass Analyzer With Rotating Electric Fields

A device for measuring the distribution of masses in an atmosphere or plasma exploits the electrostatic deflection of ions in a rotating magnetic field. A magnetic field is not required. The device is simple to construct, can be made small, and is amenable to micromachining techniques such as LIGA...

Briefs : Photonics/Optics
Program for Analysis of a Complex Optomechanical System

The IMOS computer program contains subprograms that, collectively, provide a unique capability for multidisciplinary analysis of a system represented by a combination of mathematical models of structural (mechanical), control, thermal, and optical characteristics. One example of such a...

Briefs : Electronics & Computers
Algorithm Estimates Doppler Shift in a Received DPSK Signal

An algorithm estimates the Doppler frequency shift in a received radio signal with square-wave-pulse binary differential-phase-shift-keyed (DPSK) modulation. [With little modification, the algorithm is also extensible to M-ary (where M is an integer > 2) DPSK modulation with pulse...

Briefs : Software
Software for Tracking the Performance of Other Software

The Flight Software Memory Tracker (FMT) computer program is a collection of utility subprograms developed for use on the ground to track images of the flight software (FSW) in the computers aboard the Cassini spacecraft. [As used here, "images" signifies both (1) the memory load and...

Briefs : Physical Sciences
Production of Tar in Pyrolysis of Large Biomass Particles

A paper presents a study of the production of tar in the pyrolysis of spherical biomass particles, with computational simulations performed by using the macroparticle portion of the model described in "Generalized Mathematical Model of Pyrolysis of Plant Biomass" (NPO-20068) elsewhere...

Briefs : Materials
Phospha-s-Triazines and Other Compounds for Use as Additives

A report describes research on selected compounds as additives to perfluoroalkyether (PFPAE) fluids that are used as synthetic lubricants for metal parts. Additives are needed to inhibit both thermo-oxidative degradation of, and corrosion of metals by, the PFPAE fluids in the presence...

Briefs : Photonics/Optics
Thermal Lens Spectrometer Yields High Sensitivity

Thermal lens spectrometry is a highly sensitive method for detecting very small quantities of material by the absorption of light from a laser source. It takes advantage of the thermal lens effect to measure the absorption spectrum of a sample. This invention utilizes an optical parametric...

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