Special Coverage

Distributed Propulsion Concepts and Superparamagnetic Energy Harvesting Hummingbird Engine
Aerofoam
Wet Active Chevron Nozzle for Controllable Jet Noise Reduction
Magnetic Relief Valve
Locking Mechanism for a Flexible Composite Hinge
Active Aircraft Pylon Noise Control System
Unmanned Aerial Systems Traffic Management
Method of Bonding Dissimilar Materials
Sonar Inspection Robot System
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Security System Based on Bragg Gratings in an Optical Fiber

A fiber-optic key is small, rugged, and not easily duplicated.The figure schematically illustrates an optoelectronic security system in which binary information on the identity of a person or object is encoded in Bragg gratings in an optical fiber. This is not the first optoelectronic security system based on fiber-optic Bragg gratings, but it is the first in which such gratings constitute the basis of a key or an identification tag.

Posted in: Briefs, Electronics & Computers

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Higher-Resolution Optoelectronic Shaft-Angle Encoder

This encoder is an improved version of a related prior encoder.The apparatus shown schematically in the figure is an optoelectronic shaft-angle encoder that measures absolute angles with high resolution. This encoder is an improved version of the apparatus described in "High-Resolution Optoelectronic Shaft-Angle Encoder" (GSC-13543), Laser Tech Briefs, Vol. 2, No. 2, (Spring, 1994), page 32.

Posted in: Briefs, Electronics & Computers

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High-Power Laser Illuminator

Wavelength selectivity enhances tracking in the presence of background light.A laser illuminator system has been developed for use in automated tracking of objects. In its original application, the system illuminates a 5° conical region expected to contain a small satellite at a distance up to 750 m from the space shuttle. If the satellite comes within this region, then a receiving optoelectronic system aboard the space shuttle actively tracks the satellite by locking onto the laser illumination reflected by small mirrors on the satellite. The laser illuminator system could be adapted to other outer-space and terrestrial applications that involve illumination with or without tracking, or could be used as a beacon on a moving platform for tracking by an optoelectronic system located on another moving or stationary platform.

Posted in: Briefs, Electronics & Computers

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Communication Controller Board for a Wind-Tunnel Model

This would be a key component of a miniature, distributed, modular data-acquisition system. A communication controller circuit for a wind-tunnel model is undergoing development. The circuit is intended to serve as part of a highly miniaturized, distributed, modular electronic analog/digital data-acquisition system that would be installed inside a wind-tunnel model (see Figure 1). The data-acquisition system would include pressure, temperature, angle, shear-stress, and other sensors plus analog signal-conditioning modules in clusters of as many as eight sensors. The sensors and signal-conditioning modules in each cluster would be connected to a data-acquisition-system (DAS) module, which would contain additional analog signal-conditioning circuits and analog-to-digital converters. Each DAS module, in turn, would be connected to the communication controller, which would effect all digital control and data communications (1) among the sensor modules and (2) between the sensor modules and a remote host computer.

Posted in: Briefs, Electronics & Computers

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Software for Simulating Progressive Fracture in Braided PMCs

Simulations provide guidance to increase efficiency of design and testing efforts.GENOA-PFA is a commercial version of the Composite Durability Structural Analysis (CODSTRAN) computer program, which simulates the progression of damage ultimately leading to fracture in Polymer-Matrix Composite (PMC) material structures under various loading and environmental conditions. GENOA-PFA offers a number of capabilities beyond those of programs developed previously for the same purpose; these capabilities make GENOA-PFA preferable for use in analyzing the durability and damage tolerance of complex PMC structures in which the fiber reinforcements are in the forms of two- and even three-dimensional weaves and braids.

Posted in: Briefs, TSP, Software

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Molecular-Sieve Type 3Å

This clay-based material removes trace water and iron from nitrogen tetroxide/nitric oxide mixtures.The term "Molecular-Sieve Type 3Å" denotes a clay-based, zeolite material that revolutionizes a fluid-purification process by removing trace water and iron from nitrogen tetroxide/nitric oxide (MON-3) mixtures used as oxidizer components of spacecraft propellants. Older processes of this type removed only water or iron effectively, but never both. Because contamination of nitrogen tetroxide by trace amounts of water elevates the corrosion level of spacecraft hardware, the reduction of such contamination decreases the cost of facility maintenance and increases propellant-storage time. Consequent further benefits include increases in the usable lifetimes of rocket engines, flight components, deep-space probes, and satellites, along with reductions in their failure rates. All this is achieved by a process that involves the use of a revolutionary material and that supplants less-effective, energy-intensive distillation process.

Posted in: Briefs, Materials

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Composite Graphite Anodes Containing Cyclic Ether Additives

Lithium-ion cells can be made more rechargeable.Scientists have developed a type of composite graphite anode that will benefit the U.S. space program and private industry by increasing the rechargeability of lithium-ion batteries. Rechargeable lithium-ion batteries, which are used on the space shuttle and Space Station, are also used in laptop computers, portable telephones, and other portable electronic devices.

Posted in: Briefs, TSP, Materials

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