October 1999

Briefs : Electronics & Computers
Sensor Webs

Sensor webs are developmental collections of sensor pods that could be scattered over land or water areas or other regions of interest to gather data on spatial and temporal patterns of relatively slowly changing physical, chemical, or biological phenomena in those regions. Each sensor pod would be a node in a data-gathering/...

Briefs : Electronics & Computers
Microplasmic Coating Shows High Resistance to Wear, Heat and Corrosion

The process of anodizing, or controlled oxidation, of aluminum and aluminum alloys is more than seven decades old. The primary intent of anodizing aluminum and aluminum-alloy parts is to protect the highly reactive surface against corrosion in aqueous environments, such as...

Briefs : Electronics & Computers
Inflatable Reflectarray Antennas

A type of reflectarray antenna now undergoing development is based on the concept of a reflector membrane that is stretched flat by attaching it to an inflatable frame (see figure). Antennas of this type are meant to serve as lightweight, compactly stowable, reliable alternatives to conventional antennas with...

Briefs : Software
Software Library for Parallel Adaptive Mesh Refinement

A software library has been developed for use in parallel adaptive refinement of unstructured (irregular) meshes and grids in parallel scientific and engineering computing. This library can be used in finite-difference, finite-volume, and finite-element application programs that use...

Briefs : Manufacturing & Prototyping
Modified Wire Tie

A common self-locking plastic wire tie has been modified (see figure) to enable the installer to snap off excess tie material after installation, without need for a cutting tool and without creating a potentially hazardous sharp end. A typical unmodified wire tie of this type is available in any of a variety of sizes and is...

Briefs : Motion Control
Vibratory Accelerometer and Gyroscope

A device that measures both translational acceleration and rotation exploits the dynamics of a vibratory structure that resembles a clover leaf. This device is related to other vibratory accelerometers and vibratory gyroscopes in which vibrations in suitably shaped structures are excited electrostatically...

Briefs : Software
Configuration Management of Software for Designing HSCT4.0

A report discusses the development of a highly complex system of distributed-computing, multidisciplinary design-optimization software, called "CJOpt," for use in research on model 4 of the High-Speed Civil Transport (HSCT) airplane (HSCT4.0). The emphasis in the report is on the...

Briefs : Materials
Update on SiC Fiber/[MoSi₂-Matrix/Si₃N₄ Particle] Composites

A report presents updated information on the developments described in "MoSi2-Based Composite Materials for Aircraft Engines" (LEW-16617),NASA Tech Briefs, Vol. 22, No. 9 (September 1998), page 62. To recapitulate: Hybrid composites of (1) SiC-based fibers within (2)...

Briefs : Motion Control
Proper Orthogonal Decomposition in Optimal Control of Fluids

A methodology proposed for actively controlling flows involves the use of proper orthogonal decomposition (POD) to derive computational models of reduced order. The methodology could be particularly useful for controlling flows of gases and liquids in real time.

Briefs : Physical Sciences
Mathematical Modeling of Two-Phase Flow With Evaporation

A mathematical model constructed within a theoretical framework applicable to direct numerical simulation (DNS) predicts the behavior of evaporating liquid drops entrained in a turbulent shear layer.

Briefs : Mechanical & Fluid Systems
Computational Test Cases for a Rectangular Supercritical Wing

A report describes wind-tunnel experiments on a rectangular supercritical wing and presents test cases that have been selected from the archived sets of experimental data for comparison with computational fluid dynamics (CFD) predictions. In the experiments, the wing was driven in...

Briefs : Electronics & Computers
Data-Acquisition System Takes 8-Bit Samples at 1 GHz

A unique data-acquisition system converts analog input voltages to 8-bit digital data at a rate as high as 109 samples per second (1 GHz), stores the data, and makes the data available for further processing. The system is compact, is highly resistant to ionizing radiation,...

Briefs : Materials
Cheaper Polymeric Electrolyte Membranes for Fuel Cells

Proton-conductive (solid-electrolyte) membranes made from sulfonated poly(phenylether sulfone), plus membrane/electrode assemblies containing these membranes, have been developed for use in methanol fuel cells. These membranes offer two important advantages over traditional fuel-cell...

Briefs : Motion Control
Noncontact Hall-Effect Position Sensor for Harsh Environments

Spectrol has produced an innovative design for a three-terminal voltage output device that integrates a Hall-effect sensor and a patented magnetic circuit to convert radial motion into a voltage-output signal. Standard electrical angles are at 60, 75, 90, 105, 120, 135, and 150...

Briefs : Electronics & Computers
Third-Generation Data-Acquisition System Now in Operation

Dryden Flight Research Center's Flight Loads Laboratory (FLL) was constructed in 1964 for use in performing combined mechanical and thermal tests of structural components and complete flight vehicles. The FLL is also used to calibrate and evaluate flight-loads instrumentation under the...

Briefs : Information Technology
Software for Managing Distributed Real-Time Data

An all-software data server has been invented to enable any set of connected application programs to create or gain access to live data streams. (As used here, "connected" signifies running on either the same computer or on different computers and communicating via the Internet, an intranet, or...

Briefs : Electronics & Computers
Filtering To Increase Effective Yields of Image Sensor

The addition of special-purpose signal-processing circuitry has been proposed to overcome some of the deleterious effects of hardware faults in integrated-circuit image sensors of active-pixel-sensor (APS) type and possibly of other types. The mathematical basis of the method is median...

Briefs : Medical
Whole-Blood-Staining Device

A whole-blood-staining device provides a means of (1) staining white blood cells by use of monoclonal antibodies conjugated to various fluorochromes, followed by (2) lysing and fixing of the cells by use of a commercial reagent that has been diluted according to NASA safety standards. More stable than whole blood,...

Briefs : Robotics, Automation & Control
Device Assists Actuation of a Joint in a Pressure Suit

An electromechanical device implements a unique method of actuating a fabric joint in an inflatable structure  in particular, the joint in an astronaut's pressure suit. The method is based on the principle that power from an external source can be applied to a non-constant-volume joint in...

Briefs : Physical Sciences
EPRI of Distributions of Free Radicals in Polyimide Samples

A report describes experiments in which electron paramagnetic resonance imaging (EPRI) was used to determine one-dimensional spatial distributions of free radicals in two plate specimens of PMR-15 polyimide. One specimen had been postcured at a temperature of 315 °C in nitrogen, then...

Briefs : Software
On-Line System Provides Accurate Ephemeris and Related Data

The Horizons On-Line Ephemeris and Data System ("Horizons" for short) is a computer program that provides data on the locations, motions, and dynamical parameters of solar-system objects, including the Sun, nine planets, 61 natural satellites, more than 16,000 comets and asteroids, and...

Briefs : Information Technology
Strategies for Optimal Placement of Sensors and Actuators

A paper presents a survey of sensor- and actuator-placement problems from various applications that involve a wide range of engineering disciplines. "Smart" structures that contain sensors (e.g., microphones or strain sensors) and actuators (e.g., loudspeakers or piezoelectric actuators)...

Briefs : Physical Sciences
Temperature-Stable Magnetic Sector for Mass Spectrometer

A magnetic sector in a proposed miniature mass spectrometer would include (1) a permanent magnet made of a high-energy-product material, (2) a conventional ferromagnetic yoke, and (3) a small temperature-compensating magnetic shunt. In the absence of the temperature compensation, it would...

Briefs : Electronics & Computers
Improved Control of Charging Current for Ni/H Battery

In a proposed method of controlling the electric current supplied for charging a nickel/hydrogen battery, the rate of evolution of heat would be taken into account along with the electrical quantities (voltage, current, and/or charge as functions of time) that are traditionally taken into...

Briefs : Software
Software for Planning and Execution in an Autonomous System

A software system for planning and execution of actions by an autonomous spacecraft engaged in scientific exploration has been developed to satisfy requirements to (1) maintain positive resource margins and avoid short-sighted decisions in order to achieve long-term scientific and...

Briefs : Electronics & Computers
Fast Transient-Voltage Recorder

The figure schematically illustrates an instrument designed expressly for recording lightning-induced transient voltages on power and signal cables. The principal advantage of this instrument over previously available transient-voltage recorders is high speed, as explained below.

Briefs : Robotics, Automation & Control
Modifications of the Ventricular Assist Device

A report discusses some modifications of the ventricular assist device (VAD), which was described in "Small Implantable Pump Would Assist Circulation of Blood" (MSC-22424), NASA Tech Briefs, Vol. 20, No. 7 (July 1996), page 86. The VAD is a surgically implantable, miniature rotary pump designed to...

Briefs : Motion Control
Biomorphic Robot With Distributed Power

The biomorphic robot with distributed power (BIROD) is a prototype of a class of robots that will contain simple, reliable distributed actuators that will consume power from local sources - a design concept inspired in part by biological actuators like muscles in limbs. The BIROD concept stands in...

Briefs : Manufacturing & Prototyping
Heated Weights for Adhesive Bonding

Heated weights have been found to be useful in adhesive bonding of clips, doublers, and other small parts to lightweight structures and structural components (e.g., face-sheet/honeycomb-core sandwich panels). The heated weights provide both the heat needed to accelerate curing of the adhesive and the force...

Briefs : Electronics & Computers
Improved Lightning-Current Measurements on a Protective Wire

A test procedure has been devised to increase the accuracy with which lightning currents on a protective wire can be determined from raw current measurements. The procedure was conceived specifically for determining lightning currents on a steel cable used to protect the space shuttle...

Briefs : Software
Program Generates Maps From IFSAR Data

A computer program provides for automated generation of maps from data acquired via C-band interferometric synthetic-aperture radar (IFSAR). The program reads in height, radar-brightness, and correlation data generated by IFSAR processors and computes a series of image features to be used in classifying...

Briefs : Robotics, Automation & Control
Model X-33 Subscale Flight Research Program

A program of flight testing of an instrumented subscale model of the X-33 aerospace vehicle is underway. The objectives of this program are the following:

Briefs : Electronics & Computers
Low-Power, Moderate-Speed Serial Data Communication Link

A low-power serial data communication link has been designed to transmit data among subsystems of a spacecraft instrumentation system, at rates up to 5 × 105 bits per second. The design of the link is adaptable to other spacecraft systems and to terrestrial applications that...

Briefs : Motion Control
Fault-Tolerant Feedback System for Robot Control

A fault-tolerant feedback (FTF) system has been integrated into a robot control system to prevent robot-arm runaways that could be caused by failure of one or more transducers such as joint-position, torque, and motor-temperature sensors, or in associated wiring harness channels. The FTF system...

Briefs : Materials
Lightweight, Oxidation-Resistant CwSixOyBz Ceramics

Lightweight, monolithic ceramics that retain their shapes and strengths and resist oxidation at temperatures up to 1,200 °C have been invented. These ceramics are made of carbon, silicon, oxygen, and boron. These ceramics are made by (1) using a sol-gel process to infiltrate noncarbon...

Briefs : Mechanical & Fluid Systems
Shrouds Would Catch Debris From Disintegrating Machines

Kinetic-energy-absorbing shrouds have been proposed to protect nearby persons and equipment against high-speed debris ejected by disintegrating machines. Examples of machines that could eject high-speed debris include turbines and gyroscopes. The shrouds would be laminated composites of...

Briefs : Electronics & Computers
Active-Pixel-Sensor ICs With Photosites in Substrates

Focal-plane arrays of active-pixel sensors (photodetectors integrated with in-pixel readout transistors) would be designed and fabricated within the emerging technological discipline of silicon-on-insulator (SOI) complementary metal oxide/semiconductor (CMOS) integrated circuits (ICs),...

Briefs : Electronics & Computers
Frequency-Scanning Capaciflectors

Capacitive proximity sensors of this proposed type would be based on the capaciflector concept, with an extension of hardware and software designs to incorporate capabilities for scanning in frequency and analyzing the resulting capacitance-vs.-frequency data. The proposed frequency-scanning sensors would...

Briefs : Electronics & Computers
Evolvable Multiagent Approach to Spacecraft Communication

A paper presents the concept of a system for autonomous communication among multiple satellites and other spacecraft. The design of the system would be based on an evolvable architecture of multiple intelligent agents (that is, artificial-intelligence constructs implemented in software...

Briefs : Electronics & Computers
Acoustic Sensor to Monitor Physiology and Voice

The Army Research Laboratory (ARL) has developed a new method of measuring human physiological stress parameters. This consists of an acoustic sensor positioned inside a fluid-filled bladder in contact with the body. Packaging the sensor in this manner minimizes outside environmental...

Briefs : Electronics & Computers
Integrated Infrared- and Visible-Image Sensors

Integrated circuits capable of sensing both infrared and visible images have been proposed. Until now, the usual practice for simultaneous imaging at both infrared and visible wavelengths in the same camera has involved splitting of the optical path into an infrared and a visible branch, each...

Briefs : Electronics & Computers
GaN-Based Linear Array of Ultraviolet Detectors

A recently developed gallium nitride-based linear array of ultraviolet detectors is blind to most of the visible spectrum, with a cutoff wavelength of 370 nm. This device is a prototype of GaN detector arrays for ultraviolet-light imaging in the presence of significant visible radiation, without...