November 1999

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...

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,...

Briefs : Photonics/Optics
Multiple Scattering Suppression in Laser Light Scattering

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 indirectly the sizes, of particles suspended in liquids. Older laser-light-scattering methods for determining...

Briefs : Materials
Ceramic SiwBxCyOz Fibers From Organic Si/B Polymer Precursors

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 °C, or even 1,300 °C in some cases. The final compositions of these fibers are given in the following...

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 that would be equipped with microsensors and would feature animallike adaptability and mobility. Biomorphic...

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....

Briefs : Photonics/Optics
Spectrometer/Radiometer for Measuring Heights of Cloud Tops

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 functions of three instruments - two spectrometers and a radiometer - that share a common field of view....

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 by such a circuit. The circuit also has a register to remember the cause of a reset.

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...

Briefs : Electronics & Computers
Programmable Motion System for Positioning Flow Probes

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 finely by recording more points per survey. The demand for these measurements has resulted in additional...

Briefs : Software
Software for Creating Real-Time Monitoring Expert Systems

The Generic Spacecraft Analyst Assistant (GenSAA) computer program enables the rapid development of expert-system software for intelligent real-time monitoring and detection of faults in complex systems of hardware and software. The hardware/software systems to which GenSAA expert...

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 incorporated into an electronic instrument in which capacitors are used to filter out current spikes and noise...

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 three-dimensional (3-D) grids that describe the turbomachinery blade geometry. The other three codes solve the...

Briefs : Mechanical & Fluid Systems
Software for Finite-Element Analysis of Thermoelasticity

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 axisymmetric three-dimensional structure. The name of this program reflects the use of p-version finite...

Briefs : Physical Sciences
Loop Heat-Pipe Evaporator With Bidisperse Wick Structures

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 more detail below, the bidisperse structures feature two distinct pore sizes (see Figure 1), which helps...

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 cooled to minimize the sizes of tanks needed to store them and to reduce maximum operating pressures. The...

Briefs : Mechanical & Fluid Systems
Additive Beam for Modeling Dynamics of the SR-71 Fuselage

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 the maneuvering responses and flight characteristics of flexible aircraft. Computational simulations of the...

Briefs : Electronics & Computers
Tunable, Frequency-Stabilized Diode-Pumped Tm,Ho:YLF Laser

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 has been demonstrated in a laboratory setup. This demonstration is a significant achievement in a...

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 fingers relative to the palm and (2) applying, to the fingers, feedback forces from a remote robotic...

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, and other finely divided solids collected in various environments. Designed for use in the robotic...

Briefs : Mechanical & Fluid Systems
Composite-Fuselage Concept for Greater Crashworthiness

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 flight loads and exhibit the required aerodynamic characteristics, but also to protect occupants during...

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 prefabricated buildings, and aligning vehicles for docking. It could replace more-expensive alignment systems...

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...

Briefs : Physical Sciences
Breathing Apparatus Stores Cold Supercritical Air

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 storage of air at supercritical pressure in a temperature range slightly above that of liquid air. Like...

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...

Briefs : Photonics/Optics
Miniature, Rugged Infrared Spectrometer

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 integrated optical devices. Initial development efforts have been directed toward the intended use of the...

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