Accelerated Evaluation of Properties of Polyphase Alloys

A methodology for accelerated evaluation of mechanical properties of polyphase alloys is based on digital representations of the alloys. For a given alloy material system, this representation is utilized in concert with (1) software tools and probes that simulate traditional laboratory testing equipment and instrumentation, and (2) real laboratory mechanical testing by nontraditional methods.

Posted in: Briefs, Materials, Computer simulation, Alloys, Materials properties, Test equipment and instrumentation, Test procedures

Plasma-Spray Coating as an Alternative to Chromium Plating

Plasma-spray application of coating materials that include tungsten carbide has been investigated as an alternative to electroplating of hard chromium onto internal metal surfaces that are required to be protected against wear or to be restored to within dimensional tolerances. Prime examples of such wear surfaces are the inner walls of cylinders in aircraft hydraulic actuators and dampers. The need for an alternative to chromium plating arises partly because chromium plating involves the use of hexavalent chromium, which is a highly toxic carcinogen subject to increasingly stringent government regulation and, therefore, increasingly expensive to use. Another reason for developing an alternative arises from a desire to reduce process time: To remove hydrogen that is unavoidably incorporated during chrome plating, it is necessary to perform a 24-hour bakeout. Process time could be reduced substantially if this bakeout could be eliminated. Plasma spraying involves fewer process steps than does electroplating, and for plasma-sprayed coatings, no hydrogen bakeout is necessary.

Posted in: Briefs, Materials, Spraying, Coatings Colorants and Finishes

Measuring Glucose Using pH-Sensitive Hydrogels

Sensors that exploit pH-sensitive hydrogels for measuring concentrations of glucose in aqueous solutions are undergoing development. Because the underlying chemical and physical principles are also applicable to sensing of biochemicals other than glucose, it is expected to be relatively easy to modify the glucose sensors to enable detection of such biochemicals.

Posted in: Briefs, Materials, Sensors and actuators, Water, Biomaterials, Chemicals

Two-Processor Autopilot System for a UAV

Atwo-processor autopilot control system for an unmanned aerial vehicle (UAV) has been proposed and partly developed. Relative to prior such systems, this would be a lightweight, inexpensive autopilot system offering enhanced computational power and flexibility that would enable the use of the system in a variety of advanced UAVs. The two-processor architecture represents a significant departure from most prior single-processor UAV-autopilot architectures. Moreover, because this particular two-processor architecture is an open one, based on the use of commercial- off-the-shelf (COTS) processors and other COTS electronic subsystems, the system could easily be upgraded to take advantage of available state-of-the-art equipment.

Posted in: Briefs, Information Technology, Architecture, Unmanned aerial vehicles

Automatic Abstraction of Information From Digitized Images

A research effort now underway addresses fundamental mathematical issues involved in a methodology of creating flexible machine vision systems that would be able to modify their behaviors and evolve in particular environments so as to recognize anything that human operators have designated as being "interesting" in those environments. It is intended that a person who is not a programmer could train such a machine vision system by drawing lines around objects in a scene (see figure) or otherwise indicating example objects and that thereafter, the system would adapt and evolve the ability to recognize such objects automatically.

Posted in: Briefs, Information Technology, Imaging

Thrust-Augmented Nozzles for Rocket Engines

The thrust-augmented nozzle (TAN) has been invented as a means of obtaining high performance from a rocket engine both during liftoff at sea-level atmospheric pressure and later during flight under near-vacuum conditions. In effect, the TAN rocket engine amounts to a booster rocket engine contained entirely within a sustainer rocket engine, and very little weight is associated with the incorporation of the TAN portion. Heretofore, it has been difficult or impossible to design the same rocket engine to perform well at both extremes of ambient pressure.

Posted in: Briefs, Mechanical Components, Performance upgrades, Nozzles, Booster rocket engines, Reliability

Thermal Design and Analysis of a Rocket-Engine TAN Injector

A subscale thrust - augmented - nozzle (TAN) rocket engine was designed, built, and hot-fire tested to demonstrate the validity of the TAN concept. As described in more detail in the immediately preceding article, in a TAN, during operation at sea level, thrust is augmented through injection and burning of secondary propellants (a fuel and an oxidizer) within the nozzle, downstream of the nozzle throat. The secondary propellants can be the same as, or different from, the primary propellants (the fuel and oxidizer burned during operation, in a near vacuum, in the absence of thrust augmentation).

Posted in: Briefs, Mechanical Components, Propellants, Nozzles, Booster rocket engines, Fuel injection

Front-End Mixed-Signal Receiver on a Chip

A mixed-signal receiver on a chip (RoC) now undergoing development is intended to be a prototype of the front ends of lightweight, compact, low-power, relatively inexpensive heterodyne radio receivers for future phased array radar systems. [As used here, "mixed-signal" refers to a design for utilization of both analog and digital signals, and "front end" signifies the portion of a heterodyne receiver that processes the raw radio-frequency (RF) input to produce an output at an intermediate frequency (IF) that is the difference between the RF and the frequency of a local oscillator (LO).] The RoC will include two integrated circuits, denoted IC1 and IC2 respectively, that comprise integrated chipsets designed and fabricated on the basis of the International Business Machines 7HP generation of SiGe bipolar complementary oxide/semiconductor (BiCMOS) technology.

Posted in: Briefs, Electronics & Computers, Radar, Radio equipment

Microwave Sources Utilizing Linear Induction Accelerators

Progress has been reported in a continuing effort to develop pulsed, high-power microwave signal sources based on (1) oscillators in the form of relativistic magnetrons containing transparent cathodes, and (2) hybrid antenna/ amplifiers powered via electronbeam generators. The underlying concept is that a compact, high-power microwave source could be constructed by integrating an electron-beam accelerator with a radiating antenna and an electrodynamic-interaction space.

Posted in: Briefs, Electronics & Computers, Amplifiers, Antennas

Accomplishments of the Microwave Power Research Initiative

Research performed under the auspices of the Microwave Power Research Initiative (MiPRI) between May 1, 2005 and April 30, 2006 has been reported. [The MiPRI is a congressionally mandated Air Force program to advance the science of high-power electron- beam-driven microwave and millimeter- wave signal sources.] The reported research was performed by a consortium of three universities led by the University of New Mexico and including the University of Michigan and the Massachusetts Institute of Technology (MIT). The research pertains to two signal sources of current interest to the Air Force: a relativistic Lband magnetron and a W-band source.

Posted in: Briefs, Electronics & Computers, Telecommunications, Research and development, Technical reference, Radiation