33,822 research outputs found

    Metric half-span model support system

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    A model support system used to support a model in a wind tunnel test section is described. The model comprises a metric, or measured, half-span supported by a nonmetric, or nonmeasured half-span which is connected to a sting support. Moments and forces acting on the metric half-span are measured without interference from the support system during a wind tunnel test

    Kinetics of non-equilibrium quasiparticle tunneling in superconducting charge qubits

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    We directly observe low-temperature non-equilibrium quasiparticle tunneling in a pair of charge qubits based on the single Cooper-pair box. We measure even- and odd-state dwell time distributions as a function of temperature, and interpret these results using a kinetic theory. While the even-state lifetime is exponentially distributed, the odd-state distribution is more heavily weighted to short times, implying that odd-to-even tunnel events are not described by a homogenous Poisson process. The mean odd-state dwell time increases sharply at low temperature, which is consistent with quasiparticles tunneling out of the island before reaching thermal equilibrium.Comment: Replaced Figure 1 with color version, corrected more typos. Version submitted to PR

    Design of a "Digital Atlas Vme Electronics" (DAVE) Module

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    ATLAS-SCT has developed a new ATLAS trigger card, 'Digital Atlas Vme Electronics' ("DAVE"). The unit is designed to provide a versatile array of interface and logic resources, including a large FPGA. It interfaces to both VME bus and USB hosts. DAVE aims to provide exact ATLAS CTP (ATLAS Central Trigger Processor) functionality, with random trigger, simple and complex deadtime, ECR (Event Counter Reset), BCR (Bunch Counter Reset) etc. being generated to give exactly the same conditions in standalone running as experienced in combined runs. DAVE provides additional hardware and a large amount of free firmware resource to allow users to add or change functionality. The combination of the large number of individually programmable inputs and outputs in various formats, with very large external RAM and other components all connected to the FPGA, also makes DAVE a powerful and versatile FPGA utility cardComment: 8 pages, 4 figures, TWEPP-2011; E-mail: [email protected]

    Electrochemical Characterization of Nonaqueous Systems for Secondary Battery Application Quarterly Report, May - Jul. 1968

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    Electrochemical characterization of nonaqueous systems for secondary battery applicatio

    Craft Design and Technology in Primary Schools

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    Craft, Design and Technology, with its problemsolving base is now well established in secondary schools and the recent DES statement on the organisation and content of the 5-16 curriculum has clearly set the Government's seal of approval on this aspect of the secondary curriculum. However, it is important to note that the document also places a strong emphasis on children making an early start in CDT type experiences by providing them right from the infant stage of the primary phase of education.The mere existence, let alone the far-reaching implications of such a statement may surprise both traditionally minded secondary CDT teachers - 'Young kids can't handle tools, let alone design "; and some primary teachers for whom 'science' and 'using tools and materials' have frightening connotations. Despite reactions of this kind, there are at least two crucial issues which must be faced when seriously considering this question

    Characteristics of an anechoic chamber for fan noise testing

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    Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the chamber, which is lined with an array of stepped wedges, is described. Results from the evaluation in terms of cut-off frequency and non-anechoic areas near the walls are detailed. Fan models are electrically driven to 20,600 RPM in either the inlet mode or exhaust mode to facilitate study of both fore and aft fan noise. Inlet noise characteristics of the first fan tested are discussed and compared to full-scale levels. Turbulence properties of the inlet flow and acoustic results are compared with and without a turbulence reducing screen over the fan inlet

    Antioxidant requirements of rats exposed to 100 % oxygen. Part 2 - Effects of dietary ascorbic acid

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    Dietary ascorbic acid effects as antioxidants in rats exposed to 100 percent oxyge

    Unsteady pressure measurements on a biconvex airfoil in a transonic oscillating cascade

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    Flush-mounted dynamic pressure transducers were installed on the center airfoil of a transonic oscillating cascade to measure the unsteady aerodynamic response as nine airfroils were simultaneously driven to provide 1.2 deg of pitching motion about the midchord. Initial tests were performed at an incidence and angle of 0 deg and A Mach number of 0.65 in order to obtain results in a shock-free compressible flowfield. Subsequent tests were performed at an incidence angle of 7 deg and Mach number of 0.8 in order to observe the surface pressures with an oscillating shock near the leading edge of the airfoil. Results are presented for interblade phase angles of 90 and -90 deg and at blade oscillatory frequencies of 200 and 500 Hz (semi-chord reduced frequencies up to about 0.5 at a Mach number of 0.8). Results from the zero-incidence cascade are compared with a classical unsteady flat-plate analysis. Flow visualization results depicting the shock motion on the airfoils in the high-incidence cascade are discussed. The airfoil pressure data are tabulated

    Experimental evaluation of shockless supercritical airfoils in cascade

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    Surface Mach number distributions, total pressure loss coefficients, and schlieren images of the flow are presented over a range of inlet Mach numbers and air angles. Several different trailing edge geometries were tested. At design conditions a leading edge separation bubble was observed resulting in higher losses than anticipated. The minimum losses were obtained at a negative incidence condition in which the flow was accelerating over most of the supercritical region. Relatively minor differences in losses were measured with the different trailing edge geometries studied
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