MEMs

Inexpensive Free-Form Fabrication of Titanium-Alloy Parts

A continuing effort to devise relatively inexpensive means of manufacturing titanium-alloy parts has been focused on a free-form fabrication approach. As used here, “free-form fabrication” refers generally to any or all of a number of methods and processes denoted, variously, as rapid prototyping or three-dimensional (3D) printing.

Posted in: Briefs, Manufacturing & Prototyping
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Advances in Fabrication of Nanoscale Devices

Some advances have recently been made on several fronts in a continuing effort to develop of means of fabricating electronic and magnetic devices having dimensions of the order of tens to hundreds of nanometers. This effort is a collaboration of members, from three universities, whose interests, expertise, and facilities span synthesis of materials, nanoscale characterization, nanoscale lithography, and non-lithographic processing of nanostructures.

Posted in: Briefs, Manufacturing & Prototyping
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Experiments in Vacuum Brazing of Titanium

An experimental study of vacuum brazing of titanium and of the effects of changes in brazing alloys and brazing process conditions has been performed. [As used here, “titanium” signifies both commercially pure titanium and an alloy nominally consisting of 90 weight percent of titanium, 6 weight percent of aluminum, and 4 weight percent of vanadium (commonly abbreviated “Ti-6Al-V”).] The knowledge gained in this study is intended to contribute to development of capabilities for fabricating titanium structures in circumstances in which welding — heretofore the typical method of joining titanium — cannot be performed because access is limited or adjacent nonmetallic components would be harmed. There is a particular need for such knowledge to enable fabrication of lightweight, durable titanium- based structures for armored vehicles. Examples of such structures include standard lightweight plate structures, titanium components encapsulating ceramics, and panels that comprise pyramidal frame cores sandwiched between face sheets.

Posted in: Briefs, Manufacturing & Prototyping
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Simulations of Brush Contacts of Homopolar Motor/Generators

A computational- simulation study of distributions of electric current and temperature in brushes and slip rings in two model homopolar- motor/generator configurations was performed in support of the development, by the U.S. Navy, of a superconducting homopolar motor/generator (SCHPMG) machine for ship propulsion. Electrical-contact performance (more specifically, brush/slip-ring contact performance) is a limiting factor in the performance of an SCHPMG machine. The present study and similar studies are needed to gain understanding of brush/slip-ring contact performance in order to enable optimal design of brushes for homopolar machines.

Posted in: Briefs, Mechanical Components
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Generic Miniature Airplane for Research and Development

The Air Force Research Laboratory has promulgated the geometrical design of a miniature airplane denoted the Generic Micro Aerial Vehicle (GENMAV). This design is intended to serve as a baseline for analyses of geometrical designs of other micro aerial vehicles (MAVs). As such, the GENMAV design is meant to be distributed openly among organizations engaged in research and development pertaining to MAVs. The need for the GENMAV or a similar standard of comparison has become more acute in recent years because of the increasing interest in the use of MAVs [a subset of uninhabited aerial vehicles (UAVs)] for diverse purposes, especially in military, law-enforcement, and rescue activities.

Posted in: Briefs, Mechanical Components
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Measuring Skin Friction in Complex Flows That Include Shocks

A methodology for measuring skin friction (also known as wall shear) in complex flows typical of those inside supersonic-combustion ramjet (scramjet) engines has been developed. The flows inside scramjet engines are turbulent and include shocks. Because the dynamic pressures of such flows are high, even small skin-friction coefficients can significantly degrade engine performance. Hence, it is desirable to measure skin friction in order to gain better understanding of engine performance and to enable calibration of skin-friction submodels of computational fluid dynamics models used to design scramjet engines. The presence of shocks and the large heat fluxes associated with flows in scramjet engines add to the challenge of measuring skin friction, and the present methodology provides means to meet the challenge. Major elements of the methodology are a generic design for a gauge and techniques for processing the readings of the gauge such that the wall shear at the gauge location can be determined fairly accurately, even when a shock impinges directly on the gauge.

Posted in: Briefs, Physical Sciences
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Miniaturized GPS Controlled-Reception-Pattern Antenna Array

Aminiaturized Global Positioning System (GPS) antenna array is being developed for use on aircraft on which the room available for installation of this or any other equipment is severely limited and there is a requirement for an anti-jamming capability. This miniaturized GPS antenna array is, more specifically, a controlled-reception-pattern antenna array (CRPA), which affords a capability for (1) electronic beam forming to maximize the signals received from GPS satellites and/or (2) electronic null forming to minimize signals received from jamming transmitters or to suppress multipath signals. Heretofore, it has been possible to equip some aircraft with fixed-receptionpattern antenna arrays (FRPAs) but not with CRPAs, which have tended to be larger. It is envisioned that the present development effort will eventually yield anti-jamming GPS CRPAs no larger than the GPS FRPAs now used on military aircraft.

Posted in: Briefs, Physical Sciences
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Biologically Inspired Processing of Image and Sound Data

A report describes progress in a research program oriented toward developing artificial-intelligence capabilities for processing images and sounds in changing environments. This research focuses on extending the state of the art in mid-level processing of visual and auditory signals, following a biologically inspired approach. Developments described in the report are summarized as follows:

Posted in: Briefs, Physical Sciences
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Silicone Cables

Cicoil Corp., Valencia, CA, offers Flexible Flat Cable assemblies for fighter and other military aircraft applications including targeting pods, fuel control systems, and missile gimbal and guidance systems. The silicone cables can be shaped to fit very tight spaces, low weight, and a broad temperature range extending from -65°F to +260°F. The extrusion process used to manufacture the cables produces a one-piece silicone encapsulation that will not delaminate or degrade due to vibration or exposure to oils and chemicals.

Posted in: Products
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Wireless Spread- Spectrum Radio

FreeWave Technologies, Boulder, CO, has released the MM2 small form factor 900-MHz radio. The MM2 measures 50.8 × 31.5 × 9.6 mm. The radio has a GAsFET RF front end with a combination of overload immunity and sensitivity. The radio is suited for advanced military equipment where space is at a premium, such as unmanned aerial vehicles, robotic, and guided parachute applications.

Posted in: Products
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