April 2000

Briefs : Motion Control
Controller for Bistable Brakes

The circuit shown in the figure is a controller for bistable brakes. The use of bistable brakes reduces energy consumption and spurious heating, as explained below.

A bistable brake is one that can stay in the "on" or "off" position without consuming energy from an outside source. To switch a bistable brake...

Briefs : Electronics & Computers
Ultracapacitors Store Energy in a Hybrid Electric Vehicle

A government/ industry/ academic cooperative has developed a hybrid electric transit bus (HETB). The goals of the development program, which continues, include doubling the fuel economy of city transit buses currently in service, and reducing emissions to one-tenth of the levels allowed...

Briefs : Physical Sciences
Interferometric System Images Small Vibrating Structures

A commercial scanning imaging white-light interferometer designed for measuring surface profiles of stationary objects has been modified into an interferometric instrument for imaging vibrating microelectromechanical structures. The modified instrument operates in a stroboscopic mode,...

Briefs : Mechanical & Fluid Systems
Four-Message Electromechanical Display System

A proposed electromechanical display system would be capable of presenting as many as four different messages. Conventional electromechanical display systems are limited to three messages.

Briefs : Information Technology
Rapid-Prototyping Virtual-Reality Software Tool Kit

The VrTool computer program enables its user to rapidly develop a prototype virtual-reality (VR) application program. Users of VR application programs need software that can help them keep pace with the rapidly evolving VR field. None of the previously commercially available VR software tool...

Briefs : Electronics & Computers
Imaging With a Focal-Plane Array of Ultrasonic Transducers

A prototype system for acoustic imaging of gas leaks that emit ultrasound was developed at Kennedy Space Center. Potential government and commercial users concerned with leak imaging and safety expressed interest in this technology.

Briefs : Physical Sciences
Two-Photon Microscope Imaging Spectrometer

A two-photon microscope imaging spectrometer has been proposed for use in scanning confocal two-photon microscopy. The proposed instrument would solve a spectrum-overlap that sometimes arises, as explained below.

Briefs : Electronics & Computers
Improved HRTF-Based Pseudostereophony

An improved pseudostereophonic system utilizes digital filtering and head-related transfer functions (HRTFs) to afford tailorability and sound quality not available from older pseudostereophonic systems. Although the term "pseudostereophony" may not be widely known, the underlying concept has been studied...

Briefs : Electronics & Computers
Microwave Battery Charger

A simple microwave power-transmission system has been proposed for maintaining the charge on spacecraft batteries immediately prior to launch. The basic concept of this system could also be applied to other systems (e.g., emergency equipment) that must be kept in a state of high readiness for rapid deployment, without...

Briefs : Software
Software Interface Between MATLAB and a PC RS-232 Serial Port

A computer program establishes an interface between the MATLAB software and the serial data port of a personal computer (PC) that runs either the Windows 95 or the Windows NT operating system. The program makes it possible to utilize the graphical user interface (GUI) and the...

Briefs : Software
Program for Analysis of Spacecraft Telecommunication Systems

A computer program facilitates the analysis and design of a radio-communication system for transmitting data from an orbiting spacecraft to ground stations. Input data provided by the user include primarily (1) parameters of the spacecraft orbit (including parameters that specify...

Briefs : Software
Software for Spacecraft/Ground Communication via the Internet

The Space Communications Protocol Standards (SCPS) specify a developmental system of international protocols for data communications between spacecraft and points on Earth. SCPS protocols are intended to make a spacecraft appear, to a terrestrial computer user, as just another node...

Briefs : Materials
Improved Fabrication of YBa2Cu3O7 —x Superconductors

An improved method of manufacturing high-temperature superconductors of general composition YBa2Cu3O7— x and various grain structures has been devised. This method involves mixing, pressing, and heating of Y2O3, CuO, and...

Briefs : Materials
Susceptor-Coating Materials for Growth of 4H-SiC

Several materials have shown promise for coating graphite susceptors used in epitaxial growth of 4H-SiC. The development of appropriate susceptor-coating materials is an essential part of continuing efforts to produce high-quality, thick, undoped and lightly doped epilayers of 4H-SiC for use as...

Briefs : Materials
Priming Ceramic Materials for Better Waterproofing

An improved process for waterproofing ceramic materials — especially lightweight ceramic insulation materials in both rigid (tile) and flexible (blanket) form — has been invented. In this process, traditional waterproofing agents are used, but before the waterproofing agents are applied, the...

Briefs : Mechanical & Fluid Systems
Failure-Resistant Multiline Tethers

Hoytethers™ are failure-resistant multiline tethers named after their inventor, Robert Hoyt. They were originally intended for use in outer space to provide reliable tethering of satellites in the presence of orbital-debris and micrometeorite impacts that can sever single-line tethers. Hoytethers™ may also...

Briefs : Mechanical & Fluid Systems
Program Simulates Flights of Advanced Aerospace Vehicles

Marshall Aerospace Vehicle Representation in C (MAVERIC) is a C-language computer program developed for use in performing high-fidelity simulations of flights and analyses of the guidance and control performances of the X-33 aerospace vehicle and the VentureStar reusable launch vehicle...

Briefs : Medical
Determining Glucose Levels From NIR Raman Spectra of Eyes

A developmental noninvasive method of determining the concentration of glucose in blood is based on (1) the acquisition of a near-infrared (NIR) Raman spectrum from the aqueous humor of an eye, (2) analyzing the spectrum by a combination of techniques described below, and (3) recognition...

Briefs : Test & Measurement
Improved Electrical-Impedance Body-Fluids Monitor

The Johnson Space Center (JSC) body-fluids monitor advances the state of the art of measuring hydration levels in humans during spaceflight. Neither bulky nor heavy, this noninvasive instrument is built around a commercial inductance-capacitance-resistance meter, which is used to obtain...

Briefs : Test & Measurement
Software for Testing Access List Integrity

Many networks rely on firewalls or filtering routers for frontline network security. Packet filtering firewalls or routers filter incoming or outgoing packets based on a set of access rules. The IP (Internet Protocol) Packet Generator computer program assists in verifying that a packet filtering...

Briefs : Information Technology
Program for Parallel Distributed Processing

A software system has been devised to manage automatically (1) the distribution of mutually independent computing tasks to computer workstations in NASA's Flight Design and Analysis System (FADS) network and (2) the execution of those tasks on those workstations. This program parallelizes serial tasks,...

Briefs : Mechanical & Fluid Systems
Spacecraft Solar-Wind Trim Panels for Pointing

A report proposes that spacecraft assigned to orbits distant from the Earth be equipped with trim panels that would intercept the solar wind to generate small torques to correct for disturbance torques and thereby help to maintain the spacecraft pointed in the required directions. Paired panels...

Briefs : Materials
Reaction-Forming Method for Joining SiC-Based Parts

Two reports present additional details about the method described in "Reaction-Forming Method for Joining SiC-Based Ceramic Parts" (LEW-16661), NASA Tech Briefs, Vol. 23, No. 3 (March 1999), page 50. To recapitulate: A carbonaceous mixture (typically a paste) is applied to a joint between...

Briefs : Information Technology
Subpixel Map Registration and Estimation of Uncertainty

A method of determining the location and the uncertainty in the location of a mobile robot to subpixel resolution on a map grid has been devised. The method is applicable to a robot equipped with stereoscopic vision equipment for mapping the local terrain and with sensors for determining...

Briefs : Mechanical & Fluid Systems
Control Methodology To Alter Automobile Rollover Tendencies

A methodology of active control has been developed in an effort to alter (preferably to reduce) the tendency of a four-wheel land vehicle to roll over during tight turns and similar maneuvers. At the time of reporting the information for this article, hardware and software to implement...

Briefs : Mechanical & Fluid Systems
Program for Computing Dynamics of Multiple Bodies

Symbolic Generator-Based Efficient Multibody Dynamics Algorithm (SOMBAT) is a program that enables speedy and accurate computations that solve equations of motion of multiple bodies. Originally intended for space-based applications (i.e., solving equations for the dynamics of a cluster of...

Briefs : Electronics & Computers
High-Rate Modems for Wireless Data Communications

A NASA Small Business Innovation Research (SBIR) project has led to the development of high-rate (155.52-Mb/s) modems for use in high-quality wireless data communications. The research was directed toward conceiving innovative signal-processing techniques to reduce costs below those of...

Briefs : Motion Control
Neural Networks Monitor the Health of Space Shuttle Valve

The gaseous hydrogen flow control vale (GH2FCV; see Figure 1) is a critical space shuttle component that controls the pressure of the hydrogen external tank during launch and ascent to orbit. The valve is one of the components that are to be monitored by the Integrated Vehicle Health...

Briefs : Electronics & Computers
Dual-Tuning Microwave Phase Shifter

A microwave phase shifter that can be tuned by varying both electric and magnetic fields has been developed. This device combines all the advantages of prior electrically and magnetically tunable microwave devices, but in comparison with them, it is smaller and cheaper and it performs better. Devices like...

Briefs : Physical Sciences
Exploiting Ion/Atom Cold Collisions in Atomic Clocks

Recent advances in laser cooling and trapping of neutral atoms in magneto-optic traps (MOTs) would be exploited in ion-trap-based atomic clocks, according to a proposal. Beams of laser-cooled neutral atoms would be used to: (1) put the ions in the required quantum states (e.g., spin-polarize...

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