Tech Briefs

Low-Density, Aerogel-Filled Thermal- Insulation Tiles

Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6

Posted in: Materials, Briefs

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Glass Frit Filters for Collecting Metal

Filter disks made of glass frit have been found to be effective as means of high throughput collection of metal oxide particles, ranging in size from a few to a few hundred nanometers, produced in gas phase condensation reactors. In a typical application, a filter is placed downstream of the reactor and a valve is used to regulate the flow of reactor exhaust through the filter. The exhaust stream includes a carrier gas, particles, byproducts, and unreacted particle precursor gas. The filter selectively traps the particles while allowing the carrier gas, the byproducts, and, in some cases, the unreacted precursor, to flow through unaffected. Although the pores in the filters are much larger than the particles, the particles are nevertheless trapped to a high degree: Anecdotal information from an experiment indicates that 6-nm-diameter particles of MnO2 were trapped with >99-percent effectiveness by a filtering device comprising a glass-frit disk having pores 70 to 100 µm wide immobilized in an 8-cm-diameter glass tube equipped with a simple twist valve at its downstream end.

Posted in: Materials, Briefs

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Anhydrous Proton-Conducting Membranes for Fuel Cells

Operating temperatures could be as high as 200 °C. Polymeric electrolyte membranes that do not depend on water for conduction of protons are undergoing development for use in fuel cells. Prior polymeric electrolyte fuel-cell membranes (e.g., those that contain perfluorosulfonic acid) depend on water and must be limited to operation below a temperature of 125 °C because they retain water poorly at higher temperatures. In contrast, the present developmental anhydrous membranes are expected to function well at temperatures up to 200 °C.

Posted in: Materials, Briefs, TSP

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Improved Compression of Wavelet-Transformed Images

Code parameters are selected adaptively to achieve high compression performance. A recently developed data-compression method is an adaptive technique for coding quantized wavelet-transformed data, nominally as part of a complete image-data compressor. Unlike some other approaches, this method admits a simple implementation and does not rely on the use of large code tables.

Posted in: Information Sciences, Briefs, TSP

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Predicting Numbers of Problems in Development of Software

A method has been formulated to enable prediction of the amount of work that remains to be performed in developing flight software for a spacecraft. The basic concept embodied in the method is that of using an idealized curve (specifically, the Weibull function) to interpolate from (1) the numbers of problems discovered thus far to (2) a goal of discovering no new problems after launch (or six months into the future for software already in use in orbit). The steps of the method can be summarized as follows:

Posted in: Information Sciences, Briefs

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Computationally Lightweight Air-Traffic-Control Simulation

This algorithm simulates ATC functions for a busy airport.An algorithm for computationally lightweight simulation of automated airtraffic control (ATC) at a busy airport has been derived. The algorithm is expected to serve as the basis for development of software that would be incorporated into flight-simulator software, the ATC component of which is not yet capable of handling realistic airport loads. Software based on this algorithm could also be incorporated into other computer programs that simulate a variety of scenarios for purposes of training or amusement.

Posted in: Information Sciences, Briefs, TSP

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Generating Solid Models From

Topographical Data Topographical data are converted into forms useable by rapid-prototyping machines.A method of generating solid models of terrain involves the conversion of topographical data into a form useable by a rapid-prototyping (RP) machine. The method was developed to enable the use of the RP machine to make solid models of Martian terrain from Mars Orbiter laser-altimeter topographical data. The method is equally applicable to the generation of models of the terrains of other astronomical bodies, including other planets, asteroids, and Earth.

Posted in: Information Sciences, Briefs, TSP

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