420 research outputs found

    Dissenters and Dreamers

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    The CERN Detector Safety System for the LHC Experiments

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    The Detector Safety System (DSS), currently being developed at CERN under the auspices of the Joint Controls Project (JCOP), will be responsible for assuring the protection of equipment for the four LHC experiments. Thus, the DSS will require a high degree of both availability and reliability. After evaluation of various possible solutions, a prototype is being built based on a redundant Siemens PLC front-end, to which the safety-critical part of the DSS task is delegated. This is then supervised by a PVSS SCADA system via an OPC server. The PLC front-end is capable of running autonomously and of automatically taking predefined protective actions whenever required. The supervisory layer provides the operator with a status display and with limited online reconfiguration capabilities. Configuration of the code running in the PLCs will be completely data driven via the contents of a "Configuration Database". Thus, the DSS can easily adapt to the different and constantly evolving requirements of the LHC experiments during their construction, commissioning and exploitation phases.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 5 pages, PDF. PSN THGT00

    Experimental investigation of advanced concepts to increase turbine blade loading. 3 - Performance evaluation of tandem rotor blade

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    Performance evaluation of tandem rotor blade of single stage turbin

    Experimental investigation of advanced concepts to increase turbine blade loading. I - Analysis and design

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    Increased turbine rotor blade loading through use of boundary layer control devices - vortex generator, tangential slot blowing, tandem airfoil, and jet fla

    Experimental investigation of advanced concepts to increase turbine blade loading. 2 - Performance evaluation of plain rotor blade

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    Performance of single stage turbine with rotor blade surface diffusion factor of 0.

    Localization and superconducting proximity effect in sandwiched potassium films

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    Thin films of alkali metals when sandwiched at both surfaces by thin metal films loose their conductance. The superconducting proximity effect is used to investigate the change in the alkali film. On the length scale of the film thickness the electronic properties of the alkali film do not change noticeably although its conductance is dramatically reduced, corresponding to localized electrons.Comment: 13 pages, 5 figure

    Severe discrepancies between experiment and theory in the superconducting proximity effect

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    The superconducting proximity effect is investigated for SN double layers in a regime where the resulting transition temperature T_{c} does not depend on the mean free paths of the films and, within limits, not on the transparency of the interface. This regime includes the thin film limit and the normalized initial slope S_{sn}= (d_{s}/T_{s})|dT_{c}/dd_{n}|. The experimental results for T_{c} are compared with a numerical simulation which was recently developed in our group. The results for the SN double layers can be devided into three groups: (i) When N = Cu, Ag, Au, Mg a disagreement between experiment and theory by a factor of the order of three is observed, (ii) When N = Cd, Zn, Al the disagreement between experiment and theory is reduced to a factor of about 1.5, (iii) When N = In, Sn a reasonably good agreement between experiment and theory is observed

    The Superconducting Proximity Effect as a Tool to Investigate Metal Films and Interfaces

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    052The superconducting proximity effect is measured in sandwiches of thin Pb films and the alkali metals Cs, Rb, K and Na. The TcT_{c}-dependence provides information about the interface barriers between Pb and the alkalis. Such a barrier is particularly large in Pb/Cs sandwiches. It is not due to impurities or oxydation. In the presence of a sufficiently strong barrier a special form of the Cooper limit can be applied to calculate the transition temperature of the sandwich
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