4 research outputs found

    Thermal performance of peo coated lightweight brake rotors compared with grey cast iron

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    Brake rotors play a significant role in converting the vehicle kinetic energy into heat energy that is dissipated through conduction and convection. The automotive industry has been looking for many years to develop lightweight brake rotors to reduce vehicle weight and subsequently improve fuel efficiency and vehicle emissions targets. Uncoated wrought aluminium alloys and metal matrix composite (Al-MMC) rotors have been reported to have insufficient safety margin for most passenger car applications. In this study, the thermal performance of coated and uncoated lightweight aluminium disc brake rotors was investigated numerically and experimentally, using both small scale and full size brake dynamometers. Five small scale solid brake rotors were investigated: grey cast iron, forged aluminium alloy (6082), the same 6082 alloy but with an alumina surface layer applied by plasma electrolytic oxidation (PEO), cast aluminium MMC (AMC640XA), and the same MMC again with PEO alumina surface layer. The disc and pad temperatures, brake pressure, coefficient of friction and brake torque were monitored during the tests for each disc brake material. In addition, a two dimensional axisymmetric finite element model was developed using Abaqus software in order to investigate the temperature distribution through the disc. The 2D FE model demonstrated good overall agreement with the experimental results and showed the same general trends. It was found that the PEO coated aluminium alloy has the best overall performance of the lightweight rotors tested in terms of friction and structural integrity at elevated temperature

    Search for the standard model Higgs boson decaying into two photons in pp collisions at root s=7 TeV

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    A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a center-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 fb(-1). Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance >= 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved. RI Lokhtin, Igor/D-7004-2012; Perfilov, Maxim/E-1064-2012; Belyaev, Andrey/E-1540-2012; Dudko, Lev/D-7127-2012; Boos, Eduard/D-9748-2012; Snigirev, Alexander/D-8912-2012; Tomei, Thiago/E-7091-2012; Focardi, Ettore/E-7376-2012; Raidal, Martti/F-4436-2012; Palla, Fabrizio/F-4727-2012; Gregores, Eduardo/F-8702-2012; Novaes, Sergio/D-3532-2012; Padula, Sandra /G-3560-2012; Lujan Center, LANL/G-4896-2012; Tinoco Mendes, Andre David/D-4314-2011; Flix, Josep/G-5414-2012; Fruhwirth, Rudolf/H-2529-2012; Chen, Jie/H-6210-2011; Torassa, Ezio/I-1788-201
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