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在有些摩托车驾驶员的头脑中,有一种模糊观念:更换发动机要申请批准,那是对汽车而言.摩托车么,路面执勤警察查验发动机的情况很少,何况摩托车又没有报废期限,私下换个发动机,就可延长车子使用期.但这些人忽略了交通法规的有关规定,摩托车如要更换发动机,同样要办理变更手续,经批准方可更换.不然的话,也将受到处罚.江苏省海安县的一名"骑手"就因不懂此法规,擅自更换摩托车发动机,并尝到了苦头. 相似文献
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Molecular dynamics (MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires (NWs). For each concerned carbon/silicon core/shell NW with a specified diameter, it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio. The fact matches well with the results of theoretical model. Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support. On the other hand, thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell. The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases. In addition, by calculating the phonon density of state, we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes. These results provide an effective way to modify the properties of core/shell NWs for related application. 相似文献
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