Tech Briefs

A comprehensive library of technical briefs from engineering experts at NASA and major government, university, and commercial laboratories covering all aspects of innovations in electronics, software, photonics, imaging, motion control, automation, sensors, test, materials, manufacturing, mechanical, and mechatronics.

Briefs : Mechanical & Fluid Systems
Reconfigurable Exploratory Robotic Vehicles

A family of rugged, modular, reconfigurable, instrumented robotic vehicles has been proposed for use in exploration of the surfaces of Mars and other remote planets. These or similar vehicles could also be useful in such diverse terrestrial applications as exploration of volcanic craters or other...

Briefs : Medical
Engineered Bioremediation of Contaminated Soil

Electrokinetically enhanced bioremediation (EEB) is a method of engineered bioremediation of soil contaminated by such organic compounds as solvents and petroleum products. As depicted schematically in the figure, EEB involves the utilization of controlled flows of liquids and gases into and out of...

Briefs : Medical
Microgravity Tissue Engineering

A continuing program of research and development focuses on engineering of functional cartilage and cardiac muscle for scientific research and for eventual use in transplants. The program involves the use of cells, polymer scaffolds, and bioreactor vessels. A polymer scaffold serves as a three-dimensional...

Briefs : Photonics/Optics
Apparatus for Time- and Wavelength-Resolved Spectroscopy

An apparatus that includes a pulsed electron gun and a high-resolution ultraviolet spectrometer has been developed for use in (1) pulsed electron-impact excitation of transitions among the electron-energy states in a gas and (2) measurement of the spectrum of the resulting ultraviolet...

Briefs : Photonics/Optics
Infrared Sensors for Detecting Icing on Helicopter Blades

Infrared-sensor systems for real-time detection of accretion of ice on helicopter rotor blades are undergoing development. By providing early warnings of icing conditions, these systems would enable pilots to activate deicing equipment or take other corrective action to avoid the severe...

Briefs : Photonics/Optics
Back-Illuminated CCDs With Integral Ultraviolet-Pass Filters

Efforts are under way to develop back-surface-illuminated, thinned silicon charge-coupled devices (CCDs) with delta doping and integral optical filters to be used as image detectors in the ultraviolet wavelength range. The concept of delta doping of back-surface-illuminated, thinned...

Briefs : Photonics/Optics
Capture and Escape of Charge Carriers in Quantum Dots

A report describes an experimental investigation of effects of thermally induced intermixing of In0.6Ga0.4As and GaAs on the dynamics of photoexcited charge carriers in In0.6Ga0.4As/GaAs quantum dots. The quantum dots (nanometer-size islands of...

Briefs : Photonics/Optics
Rayleigh-Scattering Measurements in Underexpanded Jets

A report describes experiments in which time-averaged and unsteady local variations in the densities of underexpanded supersonic free jets issuing from a choked circular nozzle were measured by laser-induced Rayleigh scattering. This study is part of a continuing effort to understand the...

Briefs : Photonics/Optics
Common-Path Heterodyne Interferometers

Common-path heterodyne interferometers (COPHIs) have been proposed for measuring small variations in the heights of surfaces. A COPHI could be used, for example, to measure the deviation of the surface of a mirror or other optical component from nominal flatness or nominal sphericity. Like phase-shifting...

Briefs : Physical Sciences
Shared-Aperture Multiplexed Holographic Scanning Telescopes

Shared-aperture multiplexed holographic scanning telescopes have been proposed for use in lidar transceivers and other laser transmitters and receivers in remote sensing instruments. Examples of instruments that could incorporate the proposed telescopes include airborne terrain...

Briefs : Physical Sciences
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...

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