November 1999

Briefs: Mechanical & Fluid Systems
A 3D Navier-Stokes CFD Code for Analysis of Turbomachinery

The ADPAC software is a computational fluid dynamics (CFD) code for analysis of flows in turbomachines. The outstanding feature of ADPAC is the ability to solve the Navier-Stokes equations for complex three-dimensional (3D) flow fields that include multiple flow paths, and the modeling...

Briefs: Physical Sciences
Ion-Mobility Spectrometric Determination of Hydrazines

Hydrazine, monomethylhydrazine, and unsymmetrical dimethylhydrazine can be detected and measured at concentrations as low as 10 parts per billion in the presence of ammonia at concentrations as high as 10 parts per million (greater than the odor threshold concentration of ammonia,...

A laser-light-scattering method that includes cross-correlation processing of photodetector output signals has been devised for use in measuring the Brownian motions, and thereby...

Improved formulations and processes have been invented for manufacturing ceramic fibers that exhibit structural stability and retain tensile strength at temperatures up to 1,200...

Briefs: Robotics, Automation & Control
Insectile and Vermiform Exploratory Robots

A six-legged robot resembling an insect and a legless segmented robot resembling a worm (see figure) have been proposed as prototypes of biomorphic explorers  small, mobile, exploratory robots...

Briefs: Photonics/Optics
Robot Would Inspect Hanging Cables

A proposed automated apparatus would travel along a hanging cable, optically inspecting it all around. The proposal was made to eliminate lowering human inspectors in baskets along emergency-egress slidewires at Kennedy Space Center launch pads. The apparatus would include a motor drive system, a video camera...

Briefs: Materials
Tailoring Fiber/Matrix Interfaces Through Kirkendall Defects

In a proposed method of tailoring some of the mechanical properties of metal-matrix, oxide-matrix, and ceramic-matrix composite materials, Kirkendall defects (microscopic pores as described below) would be introduced into thin interfacial layers between the fibers and the matrices....

A spectrometer/radiometer now undergoing development is designed to be used aboard a spacecraft to measure the heights of cloud tops on Earth. The spectrometer/radiometer performs...

Briefs: Mechanical & Fluid Systems
Low-Energy Interplanetary Transfers Using Lagrangian Points

A paper summarizes early findings from a continuing study of the dynamics of the transport and distribution of matter within the Solar system. In the study, the stable and unstable manifolds of the periodic and quasi-periodic orbits around the Lagrangian points L1 and L2 of the...

Briefs: Physical Sciences
Computer Program for Analysis of Convective Heat Transfer

Glenn-HT is a computational fluid dynamics (CFD) computer code for the analysis of three-dimensional flow and convective heat transfer in a gas turbine. Glenn-HT has been evolving during the past few years at Glenn Research Center, and at least 35 technical papers relative to this code...

Briefs: Electronics & Computers
Watchdog Timer and Reset Control Circuit

A watchdog timer and reset control circuit has been designed for use with a microprocessor or microcontroller (hereafter "microcontroller" for short) that would otherwise lack the protection afforded...

Briefs: Physical Sciences
Continuous Electrolytic Generation of Hydrogen Peroxide

Electrolytic cells for the continuous generation of hydrogen peroxide in streams of water have been developed. Cells of this type could be incorporated into wastewater-treatment systems based on advanced oxidation processes that utilize hydroxyl radicals. In addition to...

The validation of computational-fluid-dynamics (CFD) software used for the design and analysis of turbomachinery has made it necessary to resolve measurement of the flow field more...

The Generic Spacecraft Analyst Assistant (GenSAA) computer program enables the rapid development of expert-system software for intelligent real-time monitoring and detection of...

Briefs: Mechanical & Fluid Systems
Digital PIV Measurements of Flow in a Centrifugal Compressor

A report describes experiments in which digital particle-image velocimetry (digital PIV) was used to measure the flow field in the diffuser of a high-speed centrifugal compressor. In digital PIV, a sheet of pulsed laser light illuminates a flow field seeded with small tracer particles,...

Briefs: Electronics & Computers
Inrush-Current-Control Circuit

The electronic circuit shown in the figure regulates the inrush current that arises upon initial application of voltage to capacitors. This inrush-current-control circuit is intended principally to be...

Briefs: Mechanical & Fluid Systems
Five Computer Codes for Analysis of Turbomachinery

A suite of five computational fluid dynamics (CFD) codes has been developed for analysis of flows in turbomachinery. Two of the codes are used to generate two-dimensional (2-D) or...

The P-Finite Element Integrated Thermal-Structural Program (PITS 2D) solves the equations for the combined effects of thermal expansion and elasticity in a two-dimensional or an...

Improved evaporators for loop heat pipes have been developed by incorporating bidisperse structures (in place of older monodisperse structures) into evaporator wicks. As explained in...

Briefs: Materials
Reducing Damage to Alumina Fibers in Metal-Matrix Composites

Coating alumina fibers with sputtered metal has been proposed as a means to enable the fibers to retain more strength when the fibers are incorporated into metal-matrix composites. If the alumina fibers could be made to retain more strength, then it would be possible to manufacture...

Briefs: Robotics, Automation & Control
Better Densification of Cryogenic Liquid Rocket Propellants

An improved system for densifying (by cooling) the liquid hydrogen and liquid oxygen used as propellants for the space shuttle has been proposed. These propellant liquids are...

Mathematical models to approximate the dynamics of aircraft are often generated by considering aircraft structures to be rigid bodies. These models may be unsuitable for evaluating...

A laser-diode-pumped thulium- and holmium-doped yttrium lithium fluoride (Tm,Ho:YLF) laser that operates at a single frequency and that can be both tuned and stabilized in frequency...

Briefs: Physical Sciences
Software for Probabilistic Thermal and Structural Analysis

NESTEM is a computer code that is a combination of a heat-transfer-analysis subprogram and a NASA in-house probabilistic-analysis code called "NESSUS" (for Numerical Evaluation of StochasticStructures Under Stress). NESTEM can be used to analyze a complex combustor thermal environment...

Briefs: Physical Sciences
Sun Shields for the Next Generation Space Telescope

A report discusses the design of inflatable Sun shields proposed for use in keeping the primary mirror of the Next generation Space Telescope (NGST) at a temperature "d60 K. The report summarizes a paper presented at the 33rd Intersociety Energy Conversion Engineering Conference in August 1998...

Briefs: Robotics, Automation & Control
Force-Reflecting, Finger-Position-Sensing Mechanism

An electromechanical device called the "Dexterous Master" (DM) is an exoskeletal mechanism that is worn on a human operator's hand for (1) measuring the positions and orientations of the...

Briefs: Photonics/Optics
Miniature Scanning Electron Microscope

A miniature scanning electron microscope (SEM) with a capability for x-ray microanalysis has been proposed. This SEM would be particularly suitable for analyzing samples of dust, soil, drill tailings,...

A continuing program of research is directed toward the development of crashworthy composite-material fuselages for small aircraft. These fuselages are required not only to withstand...

Briefs: Physical Sciences
SINDA/FLUINT Augmented To Represent Condensable Species

The Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) software system has been upgraded by addition of a capability for simulating fluid mixtures that include condensable vapors. SINDA/FLUINT is the NASA standard software system for computational simulation...

Briefs: Electronics & Computers
Video-Based Active Alignment System

An optoelectronic system senses rotational and translational misalignment between two objects. The system might be used in such diverse applications as aligning construction equipment, mating parts of...

Briefs: Physical Sciences
Telescope/Camera Systems Based on Inflation-Deployed Optics

A report proposes the development of spaceborne telescope/camera systems that would be lightweight, relatively inexpensive alternatives to current systems based on glass mirrors. In a system of the proposed type, the primary reflector (typically a paraboloid several meters in diameter)...

Briefs: Physical Sciences
Two-Spacecraft Laser Tracking for Detecting Gravitational Waves

A paper proposes a method of mutual coherent laser tracking of two spacecraft for detecting gravitational radiation. Each spacecraft would transmit a laser beam to, and receive a similar laser beam from, the other spacecraft. Each spacecraft would also coherently transpond a laser...

The supercritical air mobility pack (SCAMP) is a prototype self-contained breathing apparatus designed for use in rescue and fire-fighting operations (see figure). The SCAMP is based on the...

Briefs: Photonics/Optics
Improved Optical Sensor for Monitoring Dissolved Oxygen

An optical sensor for measuring the partial pressure of dissolved oxygen in water is based on the effect of oxygen quenching on the fluorescence lifetime of an optically excited ruthenium complex immobilized in a recently developed polymer. In the operation of this sensor, the fluorescence...

The figure shows a first-phase prototype of a miniature, rugged long-wavelength infrared (LWIR) spectrometer that incorporates recent advances in the design and fabrication of microelectronic and...

Briefs: Software
Software for Parallel Adaptive Refinement of Meshes

A software library has been developed for adaptive refinement of unstructured (that is, irregular) tetrahedral or triangular meshes that define two- or three-dimensional coordinates or volume elements used in parallel (that is, multiprocessor) finite-element or finite-volume computations. This...

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