46,993 research outputs found

    Cable insulation cut-through tester

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    Device accurately measures cut-through load within specified time or time when cut-through occurs at specific load. Tests are performed at ambient conditions or in an environmental chamber

    Spool for releasing and retracting flat conductor cable

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    Spool design and operation permit installation of up to 8 cables on single unit. Heat treating the cables while wound in a coil obtains effective recoil action

    An 11-meter deployable truss for the SEASAT radar antenna

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    A folding three dimensional truss and tripod assembly which deploys the SEASAT Synthetic Aperture Radar Antenna is described. The folding structure with the antenna panels and rf components stows in an 8.5-inch-thick package. Upon deployment, the structure produced is a flat and rigid support for the antenna

    Centrifugal pumps for rocket engines

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    The use of centrifugal pumps for rocket engines is described in terms of general requirements of operational and planned systems. Hydrodynamic and mechanical design considerations and techniques and test procedures are summarized. Some of the pump development experiences, in terms of both problems and solutions, are highlighted

    High-temperature thermionic emission microscope

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    Thermionic emission microscope was designed to operate with metal specimen cathode temperatures of 2000 degrees C

    Twin-spool turbopumps for ''low'' net positive suction pressure operations

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    Modified single-shaft turbopump incorporates inducer and main pump, each separately driven at different speeds through coaxial-shaft arrangement. Inducer operates at low speed for low net positive suction pressure, main pump operates at high speed to generate high pressure. This arrangement requires no external control for the inducer

    Superflux I, II, and III experiment design: Remote sensing aspects

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    The Chesapeake Bay plume study called Superflux is described. The study was initiated to incorporate the disciplines of both resources management and remote sensing in accomplishing the following objectives: (1) process oriented research to understand the impact of estuarine outflows on continental shelf ecosystems; (2) monitoring and assessment to delineate the role of remote sensing in future monitoring and assessment programs; and (3) remote sensing research: to advance the state of the art in remote sensing systems as applied to sensing of the marine environment, thereby hastening the day when remote sensing can be used operationally for monitoring and assessment and for process oriented research

    Magnetic Excitations of Stripes Near a Quantum Critical Point

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    We calculate the dynamical spin structure factor of spin waves for weakly coupled stripes. At low energy, the spin wave cone intensity is strongly peaked on the inner branches. As energy is increased, there is a saddlepoint followed by a square-shaped continuum rotated 45 degree from the low energy peaks. This is reminiscent of recent high energy neutron scattering data on the cuprates. The similarity at high energy between this semiclassical treatment and quantum fluctuations in spin ladders may be attributed to the proximity of a quantum critical point with a small critical exponent η\eta.Comment: 4+ pages, 5 figures, published versio

    A study of the applicability of nucleation theory to quasi-thermodynamic transitions of second and higher Ehrenfest-order

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    The applicability of classical nucleation theory to second (and higher) order thermodynamic transitions in the Ehrenfest sense has been investigated and expressions have been derived upon which the qualitative and quantitative success of the basic approach must ultimately depend. The expressions describe the effect of temperature undercooling, hydrostatic pressure, and tensile stress upon the critical parameters, the critical nucleus size, and critical free energy barrier, for nucleation in a thermodynamic transition of any general order. These expressions are then specialized for the case of first and second order transitions. The expressions for the case of undercooling are then used in conjunction with literature data to estimate values for the critical quantities in a system undergoing a pseudo-second order transition (the glass transition in polystyrene). Methods of estimating the interfacial energy gamma in systems undergoing a first and second order transition are also discussed
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