June 2001

Briefs : Photonics/Optics
Polarization Recycling for Lighting LCD's More Efficiently

Two polarization-recycling techniques have been proposed to increase the efficiency of illumination of liquid-crystal display (LCD) panels. The motivation for this proposal lies in the inherent inefficiency of an LCD panel: For proper operation, illumination with polarized light is...

Briefs : Materials
Filled Skutterudites as Thermoelectric Materials

Filled skutterudites have shown promise as semiconducting materials with superior thermoelectric properties at temperatures up to at least 650 °C. This finding is a breakthrough in a continuing investigation of the potential utility of skutterudites as thermoelectric materials. Previous results...

Briefs : Physical Sciences
Fiber-Optic Transducers for Distributed Sensing of Volatiles: An Optical Nose

The term "optical nose" refers to a fiber-optic chemical sensor of a type that has been proposed to enable distributed measurement of the concentrations of volatile compounds. Optical noses should not be confused with electronic noses, which are single-point sensors...

Briefs : Mechanical & Fluid Systems
Pressure Sensor Based on Measurement of Vibration Damping

A compact, low-power device measures pressure via the pressure-induced damping of oscillation of a small mechanical resonator. To achieve compactness and low mass — and thus low-power consumption — the resonator is micromachined out of silicon. In addition to the resonator, the device...

Briefs : Electronics & Computers
Integrated Capacitive Wheel-Contact Sensors

A low-power capacitive proximity sensor has been developed as a prototype of wheel-contact sensors for a small robotic vehicle. The sensor is integrated into a wheel and consists of only a few components that add very little mass to the wheel. The output of the sensor serves as an indication of contact...

Briefs : Physical Sciences
Rare-Earth Optical Temperature Sensors

A recently developed type of fiber-optic temperature sensor utilizes narrow-band near-infrared radiation emitted by rare-earth ions. These sensors are suitable for use in harsh environments at temperatures above the maximum (1,700 °C) that Pt/Rh thermocouples can withstand. The maximum operating...

Briefs : Physical Sciences
Capacitive Sensor for Measuring Level of Liquid Nitrogen

The feasibility of a capacitive sensor for measuring the level of liquid nitrogen in a container has been demonstrated. The basic sensor design could also readily be adapted to measurement of the levels of cryogenic liquids other than nitrogen.

Briefs : Electronics & Computers
Black Jack GPS Receiver

The Black Jack (BJ) receiver is the revolutionary flight Global Positioning System (GPS) receiver developed by NASA to fill future needs for orbit-based GPS science. These range from a receiver to determine precise (1-cm radial accuracy goal for JASON-1) orbits, to missions using the GPS signals for remote sensing of the...

Briefs : Physical Sciences
Microelectromechanical Sensors Based on Magnetoresistance

Microelectromechanical sensors based on magnetoresistance have been proposed. Like other microelectromechanical sensors, these would be used to measure physical quantities that can be made to manifest themselves in small mechanical displacements. Potential applications for...

Briefs : Electronics & Computers
Digitally Programmable Analog Membership-Function Circuits

Digitally programmable analog membership-function circuits have been invented for use in fuzzy-logic systems. Heretofore, fuzzy membership functions have been implemented, variously, by use of purely analog or purely digital circuits. Purely digital circuits afford flexibility at the...

Briefs : Electronics & Computers
Regenerative Pseudonoise Ranging

In a proposed improved technique for pseudonoise turnaround ranging of a radio transponder, the pseudonoise modulating signal would be regenerated in the transponder. The net result of the regeneration would be an increase in the effective return ranging power. This increase would provide some margin for...

Briefs : Electronics & Computers
Biomorphic Analog Pulse-Coupled Neural Circuits

Analog electronic circuits that operate with pulsed input and output signals are undergoing development. The pulsing behavior of these circuits is modeled after a similar behavior, called "spiking," that occurs in biological neural networks. In these circuits, the pulse times and/or the...

Briefs : Electronics & Computers
Weighing Scales Based on Low-Power Strain-Gauge Circuits

Weighing scales (e.g., kitchen and bathroom scales) of a proposed type would incorporate sensory devices like the one described in "Low-Power, Microprocessor-Controlled Strain-Gauge Circuit" (NPO-19750), NASA Tech Briefs, Vol. 21, No. 1 (January 1997), page 45. Unlike other weighing scales...

Briefs : Software
Generating Maps of the Ionosphere From GPS Measurements

The Global Ionospheric Monitoring and Forecasting System (GIMSYS) computer program generates global maps of the total electron content (TEC) (electron density integrated over all altitude) of the ionosphere, maps of ionospheric irregularities, and related data byproducts. The maps are...

Briefs : Software
Program for Simulating Rotor Dynamics on Personal Computers

ARDS (Analysis of RotorDynamic Systems) is a public-domain computer program that simulates transient and steady-state dynamics of a rotary machine that can include as many as five interconnected flexible shafts. ARDS can be used to analyze the dynamics of such diverse machines as...

Briefs : Software
Software for Monitoring and Controlling DSN Operations

Network Monitor and Control (NMC) Automation Assembly (AA) is a component of the NMC software system, which is used for controlling an antenna connection in the Deep Space Network. NMC AA could also be adapted to commercial applications (e.g., chemical processing), in which human operators...

Briefs : Materials
Lithium Alkoxide Electrolyte Additives for Lithium-Ion Cells

Alkoxides of lithium have been found to be useful as electrolyte additives to improve the low-temperature performance of rechargeable lithium-ion electrochemical cells. As explained below, an additive of this type exerts beneficial electrochemical effects both within the bulk of the...

Briefs : Materials
Aliphatic Ester Electrolyte Additives for Lithium-Ion Cells

Aliphatic esters have been found to be useful as electrolyte additives for improving the low-temperature performances of rechargeable lithium-ion electrochemical cells. The discovery of the beneficial effects of these additives was made during continuing research directed toward...

Briefs : Materials
Ethyl Methyl Carbonate as a Cosolvent for Lithium-Ion Cells

Ethyl methyl carbonate (EMC) has been found to be a suitable cosolvent, along with three other carbonate solvents, for incorporation into electrolytes to enhance the low-temperature performance of rechargeable lithium-ion electrochemical cells. EMC is an asymmetric aliphatic carbonate,...

Briefs : Materials
Rechargeable Li-Ion Cells Containing TiS2 Anodes

Titanium disulfide has been found to be attractive as an alternative to graphite as the anode material in rechargeable lithium-ion electrochemical cells that are required to operate at temperatures below -20 °C. By using TiS2 as the anode material, LiCoO2 as the cathode...

Briefs : Manufacturing & Prototyping
Expendable Composite-Layup Dies From Rapid-Prototype Masters

A method that exploits rapid prototyping has been conceived to reduce the time and cost associated with the production of small quantities of composite-material parts that have complex shapes. In this method, mandrels and dies used in forming composite layups are sized and shaped by...

Briefs : Manufacturing & Prototyping
Punches and Dies for Rounding Corners of Metal Sheets

Punch-and-die sets have been designed for use in rounding corners of rectangular metal sheets to specified radii. One of the traditional procedures for rounding a corner on a rectangular metal sheet is to first make a rough cut with a band saw and/or hand metal snips, then to file the roughly...

Briefs : Physical Sciences
Model of Pyrolysis of Biomass in a Fluidized-Bed Reactor

A mathematical model has been formulated to describe the pyrolysis of biomass in a bubbling fluidized-bed reactor. The reactor is a vertical cylinder that contains a mixture of biomass particles and sand. Superheated steam enters the reactor through holes in the bottom and flows out freely...

Briefs : Physical Sciences
System for Delivering Gas Samples to Multiple Instruments

A system that samples gases at multiple remote locations and delivers the gases to two or possibly more gas-monitoring instruments (e.g., mass spectrometers) has been developed. The system includes a transport (suction) pump that draws the gases from the sampling locations, through...

Briefs : Physical Sciences
Atmospheric Source of Atomic Oxygen for Cleaning Paintings

A portable apparatus that operates at atmospheric pressure generates a beam of monatomic oxygen. The apparatus is designed to be used in a dry, noncontact process for removing organic contaminants from the surfaces of paintings. Organic contaminants that can be wholly or partly removed...

Briefs : Physical Sciences
General-Purpose Wavelet Program

"S+Wavelets" is the name of a computer program that implements a suite of mathematical "tools" for wavelet analysis of signals (including two-dimensional signals that represent images.) Wavelets, being localized in both time and frequency (or space and wave number), serve as means for transforming and extracting...

Briefs : Information Technology
Automated Generation of Reports of Mars Rover Operations

A document describes a system for the automated generation of reports of operations of a robotic exploratory vehicle (rover) on Mars. The automated report-generation system supplants a predominantly manual system, thereby making more information available in less time and reducing the...

Briefs : Physical Sciences
Hot Dielectrics as Light Sources for TPV Devices and Lasers

Experiments have demonstrated the feasibility of using flame-heated refractory dielectric solid bodies as wavelength-selective sources of light for special applications; in particular, for powering thermophotovoltaic (TPV) devices and for pumping lasers. A refractory dielectric...

Briefs : Electronics & Computers
Adaptive Focal-Plane Detector Arrays for Optical Communications

Arrays of photon-counting detectors and associated digital signal processors have been proposed for receivers in optical communication systems in which the optical signals propagate through the atmosphere and are relatively weak upon reception. The digital signal processor would...

Briefs : Motion Control
Packages of Circuitry for Controlling a Robotic Vehicle

Proposed packages called "remote engineering units" (REUs) would contain all the electronic circuitry needed to implement a subset of the design of the motor-control system of a robot. The REUs were conceived, specifically, for incorporation into small robotic vehicles (the Mars '03/05...

Briefs : Photonics/Optics
Pyramid-Shape Light Coupler for Multi-Quantum-Well Photodetectors

Wavelength-independent light couplers in the form of planar arrays of pyramids have been proposed for use on multiple-quantum-well infrared photodetectors. Wavelength-independent light couplers are needed for focal-plane arrays of QWIPs designed to operate in multiple and/or...

Briefs : Motion Control
Novel Radiator for a Space Suit

An improved radiator has been designed to provide inexpensive and highly reliable thermal control for an extravehicular mobility unit (EMU) [basically, a space suit equipped with a portable life-support system (PLSS)]. The amount of cooling fluid (which could be water) needed to obtain a given degree of thermal...

Briefs : Motion Control
Spin Bearings

Spin bearings have been invented as alternatives to such conventional rolling-element bearings as ball, spherical, needle, and roller bearings. Like a conventional bearing assembly, a spin-bearing assembly includes opposing complementary support members (more specifically, bearing races) spaced apart by rolling elements (more...

Briefs : Photonics/Optics
Two-Axis Scanning Mirror in a Small Package

A compact two-axis scanning-mirror assembly (see figure) has been developed for use as part of a laser rangefinder on a robotic vehicle. The assembly is designed to enable scanning of the laser beam throughout the space surrounding the vehicle for three-dimensional mapping of objects in the...

Briefs : Photonics/Optics
Noise-Reducing Slots in Quantum-Well Infrared Photodetectors

Quantum-well infrared photodetectors (QWIPs) that include two-dimensional surface grating light couplers would be modified, according to a proposal to incorporate crossed slots. It should be possible to increase signal-to-noise ratios by suitable positioning and dimensioning of the...

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