January 1999

Briefs : Photonics/Optics
Video-Based Foreign Object Detection

The Boeing Company has developed an overhead camera system that can automatically spot small pieces of debris on a work surface that might otherwise go unnoticed. The system automatically analyzes inputs from one or more video cameras to detect undesirable colors representing materials that, if left in...

Briefs : Materials
Composite-Matrix Regenerators for Stirling Engines

A prototype Stirling-engine regenerator containing a matrix made of carbon-fiber-based composite materials has been developed. The concept underlying this development effort is one of exploiting the properties of composite materials (e.g., the anisotropy of thermal conductivity of carbon fibers...

Briefs : Electronics & Computers
Fabry-Perot Fiber-Optic Temperature Sensor

A class of developmental photonic temperature-measuring systems is based on the use of miniature, fiber-optic-coupled Fabry-Perot interferometers as temperature transducers. These systems are intended for monitoring and control of advanced aircraft engines, conventional and nuclear powerplants,...

Briefs : Electronics & Computers
Luneberg Lenses Made of Open-Cell Polyurethane Foams

A Luneberg lens is a microwave lens consisting of a series of concentric shells of differing dielectric constants. The highest dielectric constant, or refractive index, resides at the core and the lowest, at the outer shell. Microwaves passing through this arrangement of shells are focused in...

Briefs : Physical Sciences
Integrated Electrochemical Sulfur Dioxide Sensors

Integrated electrochemical sensors are being developed for use in measuring concentrations of sulfur dioxide in gas mixtures. These sensors are based on the electrochemical oxidation of SO2 and measurement of the resulting electric current. Conceived for sensing SO2 in...

Briefs : Electronics & Computers
Dual-Function Microelectronic Sensors

Integrated-circuit image sensors of a proposed type would be capable of operation in either the wavelength band of 0.5 to 2.5 *m, the wavelength band of 2.8 to 5.8 *m, or both bands simultaneously. Called "dual function, thermal optical image sensors" (DTOISs), these sensors could be useful in a variety of...

Briefs : Software
Program Simulates Performance of a Hybrid Automobile

The Hybrid Electric Vehicle Analysis (HEVA) computer program numerically simulates the performance of an automotive vehicle -- especially a hybrid vehicle. A vehicle is said to be hybrid if (1) it contains an energy-storage device (a battery, flywheel, or ultra-capacitor) that is charged with...

Briefs : Information Technology
Processing ScanSAR Data Using a Chirp z-Transform

An algorithm that processes bursts of data generated by scan-mode synthetic-aperture radar (scanSAR) offers some advantages over older scanSAR algorithms. With relatively high computational efficiency, the algorithm can shift and scale the position along the flight track, preserve the phase of...

Briefs : Physical Sciences
Experiments on Flow in a Model Compressor Drum

A report discusses experiments on the flow of water along the interior of a transparent rotating cylindrical drum, the interior of which was partitioned into five cavities by disks with central holes and outer edges attached to the cylindrical drum wall. This water-flow model was designed to provide...

Briefs : Physical Sciences
Reactive-Insulator SiC-Based Schottky Diodes as Gas Sensors

Improved silicon carbide-based Schottky diodes are undergoing development for use in detecting hydrocarbon (CxHy) and nitrogen oxide (NOx) gases at high temperatures. In comparison with gas sensors of other types, Schottky-diode gas sensors exhibit...

Briefs : Physical Sciences
Thermal-Isolation Structure for Low-Temperature Experiments

The figure shows a tension/compression structure that provides rigid suspension and a high degree of thermal isolation for a small instrument assembly used in low-temperature experiments. The structure is designed primarily for use in a microgravitational environment; specifically, to...

Briefs : Mechanical & Fluid Systems
Flutterometer for Flight Testing

A flutterometer is being developed for use as a data-analysis tool for flight flutter testing. The tool is based on an on-line implementation of a robust flutter-analysis technique, called the "* method," that was described in "Characterizing Worst-Case Flutter Margins From Flight Data" (DRC-97-03), NASA Tech...

Briefs : Photonics/Optics
Frequency-Agile Fiber-Optic Transceivers

Fiber-optic transceivers (FOTs) that can handle digital signals at any bit rate from 10 to 300 MHz have been developed. These variable-rate FOTs offer considerable advantages over fixed-rate FOTs that have been used until now. A fixed-rate FOT contains clock- and data-signal-recovery circuits tuned to the...

Briefs : Materials
Improved Alloy for Fabrication of Combustion Chambers by VPS

An alloy of 88Cu/8Cr/4Nb (numbers indicate atomic percentages) has been proposed for use in fabricating rocket-engine combustion chambers by vacuum plasma spraying (VPS). Relative to other techniques that could be used to fabricate rocket-engine combustion chambers, VPS is inexpensive....

Briefs : Physical Sciences
Electrostrictive Thermal Break Between Superfluid Reservoirs

A proposed technique would make it possible to maintain two reservoirs of superfluid helium at the same pressure but at different temperatures. Heretofore, a fountain effect (described below) has made this impossible. The proposed technique could be useful for low-temperature...

Briefs : Mechanical & Fluid Systems
Model of Response of Pressure Sensor in Rarefied Flow

A mathematical model represents the dynamic response of a pressure sensor that (a) comprises a transducer connected to a pressure-sensing port via a pneumatic tube and (b) is operated under flow conditions like those expected to be encountered on advanced hypersonic aerospace vehicles...

Briefs : Physical Sciences
In Situ Chemical Analysis via Acoustic-Emission Spectra

A method of in situ chemical analysis by use of small, simple, robust sensors has been proposed. The basis for the proposal is the discovery that chemical reactions emit acoustic waves, and that characteristic frequency spectra are associated with specific reactions. The acoustic...

Briefs : Electronics & Computers
Packaging Electronic Circuits in Multi-Board Modules

The Multi-Board Module (MBM) scheme has been conceived to provide a cost-effective way to combine digital electronic circuits into dense, lightweight packages, within which high-speed signals can be transmitted readily along three-dimensional conductive paths with minimal lengths. As the title...

Briefs : Electronics & Computers
High-Efficiency, Long-Life Pulsed Inductive Plasma Thrusters

Improved pulsed inductive plasma accelerators are undergoing development for use as long-life thrusters for propulsion of spacecraft on interplanetary missions and for maneuvering of spacecraft in orbit around the Earth. On Earth, plasma accelerators of this type could be used to...

Briefs : Medical
Imaging System Shows Ischemic Regions

A noninvasive medical-imaging system produces false-color images that show regions of ischemia (reduced oxygenated blood flow) in organs and tissues. The system operates in real time, providing immediate guidance for surgery or other treatment. For example, the system can be used to identify tissues that...

Briefs : Photonics/Optics
Wavelet-Based Image Compression Software

The Boeing Company has developed wavelet-based image compression software that offers state-of-the-art compression of still imagery, providing superior image quality at compression ratios ranging from several to one up to 200:1. The algorithm compares favorably with the Joint Photographic Experts Group...

Briefs : Physical Sciences
Apparatus for Faster Ultrasonic-Lamb-Wave Testing

An ultrasonic-transducer fixture containing multiple pairs of fixed transducers, plus associated electronic transducer-multiplexing circuitry have been developed to accelerate the acquisition of data on the dispersion of ultrasonic leaky Lamb waves (LLWs) in plate specimens of laminated composite...

Briefs : Electronics & Computers
Solar-Cell System With High Conversion Efficiency

A concept for obtaining high energy-conversion efficiency in a solar photovoltaic system involves (1) concentration and spectral dispersion of sunlight and (2) use of several types of solar photovoltaic cells, each placed at its optimum location in the spectrum. The spectral dispersion and...

Briefs : Mechanical & Fluid Systems
Improved Mufflers for General Aviation

Innovative designs of mufflers for engines of small airplanes have been investigated in an effort to satisfy conflicting demands to maximize the reduction of exhaust noise while minimizing back pressure, size, and weight. Automotive-type muffler designs are not suitable for this purpose because they entail...

Briefs : Photonics/Optics
Dielectric Coating Grading Method

In a filing before the U.S. Patent and Trademark Office, the Boeing Company has disclosed a post-processing method for dielectric combiner elements that may reduce the cost of grading dual combiner sets by 90 percent compared to currently produced dielectric types.

Briefs : Materials
Etching Solution for Removal of Silver Plating From Polymers

An etching solution has been developed for use in removal of silver plating from polymer-based (including composite-material) structural components, the surfaces of which are intended to serve as mirrors and waveguide structures. Such structures are often plated with aluminum, copper,...

Briefs : Robotics, Automation & Control
Performance of an Arc-Jet Thruster

A report discusses the design and testing of a laboratory-model arc-jet thruster designed to operate at a nominal power level of 300 W. This thruster is an intermediate product of continuing efforts to develop smaller, lower-power, higher-specific-impulse thrusters for use in a forthcoming generation of small...

Briefs : Medical
Neutrophil-Screening Assay Using Two-Color Flow Cytometry

An in vitro test that includes the use of two-color flow cytometry has been developed for use in screening of neutrophils for their ability to fight infections. Neutrophils constitute the first line of defense of the human body against infections. Neutrophils engulf invading bacteria in a...

Briefs : Photonics/Optics
Optical Cavity-Ring-Down Measurement of Soot Concentration

An optical technique for measuring the concentration of soot in air is based on the cavity-ring-down (CRD) principle, which is so named because it involves observation of the decay ("ring-down") of a signal echoing in a cavity. By use of (1) the observed rate of decay and (2) a known...

Briefs : Information Technology
The SPEEDES Qheap: A Priority-Queue Data Structure

The Synchronous Parallel Environment for Emulation and Discrete-Event Simulation (SPEEDES) is now using a new general-purpose priority queue data structure called the SPEEDES Qheap for managing its set of pending events in ascending time order. Empirical studies have shown this data structure to...