December 1998

Briefs : Physical Sciences
Evaluation of Exhaust Flows From Thrust-Vectoring Nozzles

A unique dual-flow, cold-jet facility has been developed and operated by California Polytechnic State University (Cal Poly) at San Luis Obispo for NASA Dryden Flight Research Center. The facility supports flight research on thrust-vectoring nozzles and thrust-vector control systems. To...

Briefs : Physical Sciences
Monolithic Electrostatic Sector for Miniature Mass Spectrometers

An improved miniature electrostatic sector has been designed for a miniature double-focusing mass spectrometer (see figure). Miniature mass spectrometers are essential components of high-performance, miniature, low-power instruments that are being developed for use in analyzing...

Briefs : Motion Control
Hollow Shaft Actuators with Harmonic Drive Gearing

Harmonic drive gearing is recognized by designers for its zero backlash, high gear ratios, and compact design features. A recent development by HD Systems incorporates a large hollow shaft through the actuator, offering many benefits to the machine designer. The FHA hollow shaft actuator series...

Briefs : Electronics & Computers
Update on the Web Interface for Telescience

An Internet-based software system, called the "Web Interface for Telescience" (WITS), enables geographically dispersed scientists to participate in scientific exploration of remote planets by use of instrumented landers and robotic vehicles called "rovers." WITS at a previous stage of development was...

Briefs : Electronics & Computers
Eight-Channel WDM Fiber-Optic Data-Communication System

A proposed wavelength-division-multiplexing (WDM) optical communication system would feature a single optical fiber carrying eight channels of digital data signals. In the original application, the signal in each channel would be a serial digital video-camera output, but the system could...

Briefs : Software
Generic Graphical-User-Interface Program for FORTRAN Input

The NLEDIT computer program implements a generic graphical user interface for the preprocessing of FORTRAN namelist input files. The interface consists of a menu system, a message window, a help system, and data-entry forms. A form is generated for each namelist. The form includes an...

Briefs : Motion Control
Vibration Testing with Innovative Supports

When developing the guidance system of a missile, it is necessary to know the resonant frequencies and mode shapes of the missile in flight. Simulating the free vibration condition in the laboratory, however, is a difficult task, since the required supports can affect the test results.

Briefs : Information Technology
Modular, Extensible Program Simulates Dynamics of Systems

The Multiple Object Orbital Dynamics Simulation (MOODS) computer program is a general, extensible, easily modifiable, and reusable software system for use in simulating the dynamics of such diverse engineering systems as aircraft, missiles, automobiles, industrial process-control systems,...

Briefs : Materials
Protective Anode Separators for Rechargeable Lithium Cells

The anode separators in rechargeable lithium-ion electrochemical cells that contain carbon lithium-intercalating anodes with copper current collectors would be modified, according to a proposal, to give some protection against the internal short-circuiting that tends to occur during...

Briefs : Photonics/Optics
Trenches Would Reduce Cross-Talk Among Microlensed QWIPs

Cross-talk in integrated-circuit focal-plane arrays of quantum-well photodetectors (QWIPs) equipped with microlenses would be reduced, according to a proposal, by etching deep trenches into the substrates of these devices. The proposal applies, more specifically, to GaAs-based,...

Briefs : Manufacturing & Prototyping
Microgravity Fiber-Pulling Apparatus

A method to process optical fiber composed of glass systems has been developed in support of the space shuttle and Space Station programs. This process, known as the Microgravity Fiber-Pulling Apparatus, was designed to operate in a microgravity environment. It has the unique capability to produce heavy-metal...

Briefs : Photonics/Optics
Microlenses on Focal-Plane Arrays of QWIPs

The performances of large focal-plane arrays of quantum-well infrared photodetectors (QWIPs) would be improved, according to a proposal, by incorporating microlenses. In comparison with a similar QWIP array that lacked microlenses, a QWIP array with microlenses could be made to exhibit less dark current...

Briefs : Photonics/Optics
Computer Code for Analysis of Stress in Silicon Wafers

The MacWafer™ code computes gravitational and thermal stresses in silicon wafers and uses these results to determine the maximum allowable temperature variation across a wafer, maximum processing temperatures, and maximum allowable heating and cooling rates. This information is of...

Briefs : Robotics, Automation & Control
Miniature Joule-Thomson Rankine-Cycle Refrigerators

Miniature, lightweight, low-power, low-vibration Joule-Thomson Rankine-Cycle refrigerators have been proposed for cooling portable scientific instruments. These refrigerators would be made largely from silicon wafers by micromachining techniques like those used to fabricate integrated circuits....

Briefs : Mechanical & Fluid Systems
Manipulation of Liquids by Use of Sound: Part I

An acoustic-radiation-pressure phased array (ARPPA) is undergoing development at Lewis Research Center. ARPPAs are envisioned as general-purpose, nonintrusive tools for manipulating both liquids and objects suspended in liquids.

Briefs : Information Technology
Software for Qualitative Flow-Path Modeling of Systems

A computer program called "the explicit global-modeling tool" implements a dynamic method of operation by which researchers can (1) determine global flow-path changes that occur during computational simulations of the behaviors of engineering systems; (2) analyze both normal and faulty...

Briefs : Materials
Time-Dependent Nature of Adhesive EA946

More accurate analyses of adhesive EA946 can now be accomplished using new mathematical models. Tests involving this adhesive (used in the space shuttle's reusable solid-rocket-motor nozzle and other rocket-motor nozzles) indicated that the adhesive is nonlinearly viscoelastic at short equivalent times and...

Briefs : Software
Software for Analysis and Design of Turbomachinery Seals

Several computer programs, denoted collectively as the "CFD Seal Analysis Industrial Codes," have been developed to enable rapid parametric analyses and optimization of designs of a variety of turbomachinery seals. These programs could be used to design the seals that will be needed in...

Briefs : Electronics & Computers
Bound-to-Quasi-Bound QWIPs With Random Reflectors

Quantum-well infrared photodetectors (QWIPs) that are designed to exploit transitions between bound and quasi-bound electron quantum states and that incorporate random reflectors are undergoing development. Focal-plane arrays of such detectors are also undergoing development, all as part of a...

Briefs : Photonics/Optics
Miniature, Tunable, Wide-Band-Pass Optical Filters

A proposed miniature, electrically tunable, band-pass optical filter would have a Fabry-Perot configuration, but would be designed to trade the high spectral resolution (narrow-band pass) and small tuning range of a traditional Fabry-Perot filter for low spectral resolution (wide-band pass) and...

Briefs : Mechanical & Fluid Systems
Designing With Help of Neural-Network and Parallel Computing

Structural Analysis/Design (STRAND) and Neural Net Computation (NETCOM) are developmental modular computer programs that exploit the speedup afforded by parallel and neural-network computing to drastically reduce the computation time needed to solve large design-optimization problems....

Briefs : Photonics/Optics
Selective Metallization for High-Temperature Semiconductors

Inventors at the Cornell Research Foundation have devised a method of selective metallization of high-temperature semiconductors to produce ohmic or rectifying contacts. The process consists of three phases: a lithographic step to define the areas of contact, preparation of the...

Briefs : Materials
Microwave Brazing of Polycrystalline Diamond Onto Drill Bits

A microwave-heating technique has been developed for making a braze joint (1) between a tungsten carbide support and a surface layer of polycrystalline diamond or, alternatively, (2) between a tungsten carbide support and a relatively thin tungsten carbide backing layer with...

Briefs : Information Technology
Knowledge-Based Reasoning Tool for Diagnosing a Complex Flow System

This program is designed as a real-time aid to analyze system health.

The Propulsion Advisory Tool (PAT) is a knowledge-based computer program that monitors real-time data from more than 300 sensors in the space shuttle Main Propulsion System (MPS). The thermal conditions...

Briefs : Mechanical & Fluid Systems
Manipulation of Liquids by Use of Sound: Part II

Acoustic-radiation pressure can be used to improve performance in the dispensing of liquid drops into gases or vacuum and in dispensing gas bubbles into liquids. In a typical application involving dispensing a liquid, this is accomplished by use of a high-frequency, high-intensity acoustic...

Briefs : Electronics & Computers
Ridged Tracks for Guiding Magnetic Bubbles

Tracks for the guidance of magnetic bubbles propagating in the input and output lines of Vertical-Bloch-Line memory devices can be made in the form of ridges instead of in the traditional form of grooves. The ridge-type tracks offer advantages over the groove-type tracks, as explained below.

Briefs : Motion Control
Automated Propellant-Blending Machine

The automated propellant-blending machine, a Johnson Space Center (JSC) innovation, refines the production processes of commercial rocket-propellant manufacturers by: (1) generating inert blends that contain particles of uniform size; (2) eliminating manual mixing, thereby speeding production and reducing...

Briefs : Electronics & Computers
Program for Analyzing Free-Space Optical Communication Links

"Free-Space Optical Communications Analysis Software" (FOCAS) is the name of a spreadsheet computer program for analysis of direct-detection (as distinguished from heterodyne-detection) optical data-communication links. Implemented within the Microsoft Excel software system, FOCAS...