48,064 research outputs found

    Circuit minimizes current drain caused by neon indicator lamps

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    Circuit lights neon lamp by back leakage current of the driving transistor, rather than by the transistors saturation or ''on-state'' current, thereby eliminating lowering of the voltage necessary for indication. Circuit has operating speed greater than indication circuit using a saturation principle and aids in power rationing

    A New Solution of The Cosmological Constant Problems

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    We extend the usual gravitational action principle by promoting the bare cosmological constant (CC) from a parameter to a field which can take many possible values. Variation leads to a new integral constraint equation which determines the classical value of the effective CC that dominates the wave function of the universe. In a realistic cosmological model, the expected value of the effective CC, is calculated from measurable quantities to be O(t_U), as observed, where t_U is the present age of the universe in Planck units,. Any application of our model produces a falsifiable prediction for Λ\Lambda in terms of other measurable quantities. This leads to a specific falsifiable prediction for the observed spatial curvature parameter of Omega_k0=-0.0055. Our testable proposal requires no fine tunings or extra dark-energy fields but does suggest a new view of time and cosmological evolution.Comment: 5 pages; v3: version accepted by Phys. Rev. Let

    Devolution as process: institutional structures, state personnel and transport policy in the United Kingdom

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    Devolution has been described as a key ‘global trend’ over recent decades as governments have decentralised power and responsibilities to subordinate regional institutions (Rodriguez-Pose and Gill, 2003). UK devolution is characterised by its asymmetrical nature with different territories granted different institutional arrangements and powers. In this paper, we seek examine the role of state personnel in mobilising the new institutional machinery and managing the process of devolution, focusing on transport policy. Our research shows a clear contrast between London and Northern Ireland, on the one hand, and Scotland and Wales, on the other, in terms of the effectiveness of political leaders in creating clear policy priorities and momentum in transport

    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

    Device and method for frictionally testing materials for ignitability

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    Test apparatus for determining ignition characteristics of various metal in oxidizer environments simulating operating conditions for materials is invented. The test apparatus has a chamber through which the oxidizing agent flows, and means for mounting a stationary test sample therein, a powered, rotating shaft in the chamber rigidly mounts a second test sample. The shaft is axially movable to bring the samples into frictional engagement and heated to the ignition point. Instrumentation connected to the apparatus provides for observation of temperatures, pressures, loads on and speeds of the rotating shaft, and torques whereby components of stressed oxygen systems can be selected which will avoid accidental fires under working conditions
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