Thermal transport properties of defective graphene:A molecular dynamics investigation

In this work the thermal transport properties of graphene nanoribbons with randomly distributed vacancy defects are investigated by the reverse non-equilibrium molecular dynamics method. We find that the thermal conductivity of the graphene nanoribbons decreases as the defect coverage increases and is saturated in a high defect ratio range. Further analysis reveals a strong mismatch in the phonon spectrum between the unsaturated carbon atoms in 2-fold coordination around the defects and the saturated carbon atoms in 3-fold coordination, which induces high interfacial thermal resistance in defective graphene and suppresses the thermal conductivity. The defects induce a complicated bonding transform from sp2 to hybrid sp–sp2network and trigger vibration mode density redistribution, by which the phonon spectrum conversion and strong phonon scattering at defect sites are explained. These results shed new light on the understanding of the thermal transport behavior of graphene-based nanomaterials with new structural configurations and pave the way for future designs of thermal management phononic devices.     

玻色气体的量子简并性对不可逆布雷顿制冷循环性能的影响

基于不可逆布雷顿制冷循环模型和理想玻色气体的状态方程,导出以玻色气体为工质的布雷顿制冷循环的输入功、制冷系数、制冷量等重要参数的表示式,由此讨论玻色气体的量子简并性和不可逆绝热过程对循环性能的影响,揭示以玻色气体为工质的不可逆布雷顿制冷循环的一般性能特性,从而导出一些重要结论．进而给出几种特殊情况下循环的性能特性．得到的结果有助于进一步了解经典布雷顿制冷循环和量子布雷顿制冷循环之间的区别和联系．     

工程认证背景下的“大学物理”课程改革及教学研究

本文阐述了工程认证教育背景下,我校大学物理教学中存在的问题及改革的必要性,并根据我校的办学定位对教学目标、教学内容和教学方法进行改革。根据工程认证的要求重新明确了知识、能力、素质培养三个层次的教学目标,并设计了相应的评价体系。根据各个不同专业对教学内容进行调整,在教学内容中突出强调物理思想,突出工程技术中应用的案例介绍。教学方法上通过引导学生自学、探究性学习来调动学生的主动性,侧重培养学生的思维方法,激发学生的创造性,为培养未来的工程师打下良好的知识基础和方法基础。