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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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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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Continuous Carbon Nanofibers for Structural Composites

A program of research has addressed key issues in the production of continuous carbon nanofibers and the utilization of carbon nanofibers as the reinforcing components in matrix/fiber composite materials. The goal of this research is to contribute to the development of advanced lightweight structural composites in which the exceptionally high strengths of carbon nanofibers are exploited to obtain mechanical strengths, delamination toughnesses, and fatigue lives greater than would otherwise be possible.

Posted in: Briefs, Materials, Fabrication, Composite materials, Fibers, Lightweight materials, Nanomaterials
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High-Strain-Rate Tests of Epoxy/Aluminum-Powder Composites

Initial tests have been performed in a continuing experimental study to determine selected mechanical properties, at high strain rates, of an epoxy and of composite materials consisting of the epoxy filled with aluminum powders. These composites are examples of the large variety of polymer-matrix/particlefilling composites in general, which are widely used in military and civilian applications. The properties of such composites can be tailored for specific applications through appropriate choices of constituent materials, the proportions of the constituent materials, and the sizes of the particles. Especially in aerospace structural applications, the composites are exposed to complex, temporally varying loads. Therefore, the mechanical properties of such composites’ high strain rates are of increasing importance.

Posted in: Briefs, Materials
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High-Temperature Resins for Composite Materials

Improved, readily processable thermosetting polymer resins are being developed for use as matrix materials in composite-material structures in applications in which there are requirements for thermal stability and hot-wet performance. Heretofore, the development and utilization of polymer resins for such applications have been limited by adverse characteristics that include (1) toxicity of many of the chemicals used to make the resins; (2) poor performance during fires (excessive flame and smoke, dripping, and generation of hazardous substances); (3) significant absorption of water in humid environments, linked to delamination during rapid heating; and (4) in the cases of many of the polymers suitable for use at the highest temperatures, difficulties in the use of newer, less expensive fabrication techniques.

Posted in: Briefs, Materials
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Making Ultra-Hydrophobic Textured Silicone-Rubber Surfaces

Silicone-rubber surfaces microscopically textured in such a manner as to render them ultra-hydrophobic have been fabricated by a method in which breath figures are utilized. Originally, “breath figures” signified fog-like patches formed by condensation of microscopic droplets of water from air exhaled onto cooler surfaces. Now, “breath figures” refers more generally to patches formed by condensation, whether from natural breath or artificial sources. The essence of the method is to use a breath figure to form a pattern of microscopic, approximately hemispherical pits (each pit corresponding to a condensed water droplet) on the surface of a layer of polystyrene, then use the pitted polystyrene surface as a template to cast the silicone rubber having a surface pattern of nanometer- or micron-sized pillars corresponding to the pits.

Posted in: Briefs, Materials
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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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