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Digital Library of NACA Reports

Aging paper NACA documents are scanned, then disseminated in electronic form. The NACA Technical Report Server (NACATRS) is both a node in the NASA Technical Report Server and a stand-alone World Wide Web (WWW) site. The NACATRS is dedicated to the preservation and dissemination of reports produced by the National Advisory Committee for Aeronautics (NACA).

Posted in: Information Sciences, Briefs, TSP

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A Method for Designing Low-Pass FIR Digital Filters

Time-domain filters are first constructed in the frequency domain, using special window functions. A class of finite-impulse-response (FIR) digital filters has been developed to perform certain frequency-limiting, decimation, and differentiation (with respect to time) functions on a time series of data samples. The method is implemented by use of design equations that contain parameters that can be adjusted to obtain the desired functionality while limiting such undesired effects as aliasing and gain ripple. The original application is processing of a time series of raw range data from the proposed Gravity Recovery and Climate Experiment (GRACE), in which microwave phase tracking between two small spacecraft orbiting the Earth would yield the time-tagged raw range data, which would be processed to extract information on the structure of the gravitational field of the Earth. The method is general enough to be applicable in other situations that involve similar signal-processing requirements.

Posted in: Information Sciences, Briefs, TSP

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High-Temperature Switched-Reluctance Electric Motor

Motors like this one would be incorporated into gas turbines as starter/generators. An eight-pole radial magnetic bearing has been modified into a switched-reluctance electric motor capable of operating at a speed as high as 8,000 rpm at a temperature as high as 1,000 °F (Å540 °C). The motor (see figure) is an experimental prototype of starter-motor/ generator units that have been proposed to be incorporated into advanced gas turbine engines and that could operate without need for lubrication or active cooling.

Posted in: Mechanics, Mechanical Components, Briefs

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Current Attractions

NASA's Innovative Partnerships Program (IPP) provides technology for NASA's mission directorates, programs, and projects through investment and technology partnerships with industry, academia, government agencies, and national labs. NASA Tech Briefs spoke with Doug Comstock, Director of NASA's Innovative Partnerships Program, about how the public and industry can access NASA technologies, and how NASA communicates its technology needs to those who can provide them.

Posted in: Blog

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Techs of the Week

PharmaDur™ is a polymer-based technology that provides benefits over conventional forms of transdermal drug delivery. Also used for transmucosal and ophthalmic applications, it is a topical application that yields an invisible and imperceptible hydrogel film that creates a monolithic reservoir from which drug substances are released at a controlled rate for transdermal transport. Unlike conventional gels and creams, it functions like a patch to provide controlled released delivery of APIs (active pharmaceutical ingredients).

Posted in: Blog

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New CPR



Posted in: Blog

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Thermocouple Rakes for Measuring Boundary-Layer Flows

Flows can be measured extremely close to surfaces. Thin-film devices that comprise heaters in combination with thermocouples have been developed for measuring flow velocities extremely close to solid surfaces, at several distances from the surface of interest. Devices that perform this function are denoted generally as “boundary-layer rakes.” The measurement data acquired by boundary-layer rakes are needed for calculating viscous shear forces, for developing mathematical models of turbulence to be used in computational fluid dynamics, and as feedback in some flow-control systems.

Posted in: Physical Sciences, Briefs, TSP

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