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Update on NASA’s Unmanned Aerial Vehicle

In the August issue of Defense Tech Briefs, we highlighted NASA’s Altair/Predator B unmanned aerial vehicle (UAV) for Earth science missions. A lot has happened in the past two months, so we’re providing an update on the latest aircraft and applications in NASA’s growing UAV program.

Posted in: Articles, Aerospace
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SpaceWire: The Standard for Aerospace Communications

Developed in 1999 under the auspices of the European Space Agency, SpaceWire answered a longstanding spaceflight problem: no standard, high-speed communications protocol existed for flight electronics. Therefore, all spaceflight electronic payloads (such as processing units and onboard computers) were customdesigned, which resulted in long development periods, high costs, and elevated risks. The SpaceWire standard was developed as a network of nodes and routers interconnected through bidirectional, high-speed serial links, limiting the customdesign problem by designing a standard with flexibility, modularity, and reusability.

Posted in: Articles, Aerospace
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Error-Free Data Acquisition and Archival for High-Bandwidth Military Applications

Acquiring data from sensors, transporting the data, and then archiving it for future reference has changed dramatically over the last few years. The traditional approach of collecting data from an analog-to-digital converter (ADC) with a small microprocessor to monitor the slow-changing levels of a signal is for the most part no longer adequate. Today's new advanced military systems now employ complex sensors capable of generating streams of data with rates of 100 megabytes and greater. To transfer this high-speed data from the sensor to a processor without losing signal characteristics, designers now must digitize the data at the sensor. To meet this requirement, designers needed a protocol that would transport the digital data with minimum processing or latency. This problem was pursued by several companies, including Curtiss- Wright, and the result was the ANSI/VITA 17.1-2003 Serial Front Panel Data Port standard (S-FPDP).

Posted in: Briefs, Information Technology
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The Dataflow Interchange Format for Designing DSPs

The dataflow interchange format (DIF) is a conceptual framework for helping designers of digital signal-processing (DSP) systems to integrate diverse dataflow models, dataflow techniques, DSP-design software tools, DSP software libraries, and embedded processing platforms. Somewhat more specifically, the DIF is intended to afford a unique combination of capabilities for (1) developing dataflow models and techniques for exploring the complex design spaces for embedded DSP systems; (2) porting DSP designs across various software tools, libraries, and embedded processing platforms; and (3) synthesizing software implementations from high-level, dataflow-based program specifications.

Posted in: Briefs, Information Technology
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System for Imaging Turbulent Combustion Flows

The Components of the System enable diverse types of imaging, acquisition of image data, and processing of the data to extract information on multiple aspects of high-speed combustion flows.Asystem of scientific instrumentation and data-processing equipment has been assembled for research and education in turbulence, mixing, and chemical reactions (especially combustion) in high-speed laminar and turbulent flows. The system is designed to enable study of temporally varying, three- dimensional structures in flow regimes that have been inaccessible to prior instrumentation systems, with emphasis on flow regimes relevant to the operation of ramjet and scramjet engines.

Posted in: Briefs, Physical Sciences
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Variable-Data-Rate Speech Encoder

Avariable-data-rate (VDR) speech encoder has been designed to be interoperable with, and eventually to supplant, the many different voice encoders now used in military communication systems. Because these older systems were designed to utilize specific radio links with fixed and limited channel capacities, these systems utilize many different voice compression algorithms operating at various fixed rates. The incompatibility of these systems is an obstacle to interoperability. Emerging net-centric communication systems promise to provide connectivity to all military users, but compatible encoding will be necessary for interoperability, and encryption will be necessary for secure communications.

Posted in: Briefs, Electronics & Computers
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Apparatus Generates CE-Phase-Stable Two-Cycle Optical Pulses

A n apparatus that includes two optical parametric chirped pulse amplification stages has been built as a means of generating few-cycle, common-envelope (CE)-phase-stable, high-energy optical pulses. [CE phase is the phase of an optical carrier-signal waveform relative to the pulse envelope waveform. CE phase is an important property of fewcycle pulses, and CE-phase stability is essential in typical applications involving few-cycle pulses.] The apparatus can generate two-cycle (14-fs-duration) pulses at a nominal middle wavelength of 2 μm, and two-cycle (5-fs-duration) pulses at a nominal middle wavelength of 800 nm at a repetition rate of 1 kHz, without need for pulse compression by an external apparatus. The apparatus is intended for use in high-harmonic generation (HHG) of extreme ultraviolet (EUV) and soft x-rays in the near term, extending to production of attosecond EUV and soft-x-ray pulses in the longer term. Moreover, this apparatus is expected to enable exploration of generation of fewand single-cycle laser pulses over the wavelength range from 700 to 2.6 μm.

Posted in: Briefs, Photonics
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Terahertz Fiber-Optic Lasers for Detection of Explosives

Fiber-optic lasers of a proposed type would serve as sources of coherent radiation at frequencies between 0.5 and 4.0 THz and output power levels ≥100 mW. In the original application envisioned in the proposal, these lasers would be parts of compact, man-portable instruments for detection of explosives.

Posted in: Briefs, Photonics
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Research on Quantum Communication Repeaters

A program of research during the years 2001 through 2006 was devoted to building theoretical and practical foundations for the development of quantum repeaters as means of overcoming losses of photons in long-distance quantum communication systems. The idea underlying this research was to investigate means of utilizing suitably prepared ensembles of atoms (e.g. rubidium vapors) as means of storing and transferring the information encoded in the states of photons. The main accomplishments of this research, in approximate chronological order, include the following:

Posted in: Briefs, Photonics
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Alloys for Nozzles of Hypersonic Wind Tunnels

Alloys are being developed for nozzles of hypersonic wind tunnels to be used in testing components of future hypersonic missiles, aircraft, and space transportation systems. The nozzle components made from these alloys will be required to retain sufficient strength to withstand stresses of as much as 600 MPa at throat surface gas temperatures as high as 1,700 K while resisting erosion and oxidation by impinging hypersonic flows of air and possibly other gases. In some applications, back-side cooling or film/transpiration cooling may be used to reduce the temperature rises in nozzles. Alternatively, in some applications, nozzles may be used, without active cooling, in either of two heat-sink modes. In one mode, exposure time would be limited in order to limit the maximum temperature rise. In the other mode, denoted the self-limiting heat-sink mode, a nozzle throat would be exposed long enough to come into thermal equilibrium with the gas, and, hence, the nozzle throat material must be chosen to withstand the maximum surface gas temperature (e.g., 1,700 K) for an indefinite time.

Posted in: Briefs, Materials
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