Equivalent Kelvin Impact Model for Seismic Pounding Analysis of Bridges

Based on Hertz contact theory, a method to determine the parameters of Kelvin impact model for seismic pounding analysis of bridges is proposed. The impact stiffness of Kelvin model is determined by the ratio of maximum impact force to maximum contact deformation, which is calculated based on Hertz contact theory with considering the vibration effect. The restitution coefficient which has great influence on the damping coefficient of Kelvin impact model is investigated by numerical analysis. Numerical results indicate that the impact stiffness of Kelvin impact model increases with the increment of the Hertz contact stiffness, approaching velocity or the length ratio of short to long girders. Vibration effect has remarkable influence on the impact stiffness and cannot be neglected. The restitution coefficient decreases when approaching velocity increases or the length ratio of short girder to long girder decreasing. The practical ranges of impact stiffness and restitution coefficient are obtained as 3×108-6×108 N/m and 0.6-0.95 respectively.     

Mathematical models of canine right and left atria cardiomyocytes

The aim of this study is to build two mathematical models of canine ionic currents specific to right atria and left atria.The canine left atria mathematical model was firstly modified from the Ramirez-Nattel-Courtemanche(RNC) model using the recently available experimental data of ionic currents and was further developed based on our own experimental data.A model of right atria was then built by considering the differences between right atria and left atria.The two developed models well reproduced the exper...     

小球与均质定轴杆的非完全弹性碰撞

讨论了小球与定轴转动细杆碰撞过程中所遵从的物理规律,给出了非完全弹性碰撞的一般公式,分析了碰撞位置和恢复系数对小球和细杆的运动状态的影响,计算了系统的动能损失率,并讨论了其随撞击位置和恢复系数的变化关系。     

对生源地信用助学贷款的思考

该文系统分析了生源地信用助学贷款信用约束方面优势突出和贷款方式灵活便于跟踪等诸多优势,提出推广生源地信用助学贷款的必要性．对于补充、完善高校国家助学贷款,加大资助家庭经济困难学生的力度,具有重要的意义。本文也为保障生源地信用助学贷款健康持续开展提出了可行性建议。     

弧圈球碰台过程的力学分析

从力的基本原理,探讨弧圈球碰台时和碰台后速度变化的原因,针对弧圈球碰台后速度变化这一现象,结合理论力学和碰撞原理对碰台时和碰台后速度变化和飞行弧度加以理论推导,从三个方面ｒ ＞Ｖｃ、ｒ ＝ Ｖｃ、ｒ　＜ Ｖｃ及流体力学基本原理加以简述弧圈球弧线变化的原因。     

原因违反社会公德之给付能否请求返还——对《合同法》第58条的完善

尊重社会公德原则是我国合同法的一项基本原则。现实中,内容与形式符合法律规定的合同,却可能由于订立合同的原因违反社会公德导致合同无效。无效即意味着合同失去对当事人的拘束力,但是基于该类无效合同所为之给付能否请求返还呢,合同法并未给出明确答案,该问题殊值探讨。     

恢复原状:无效合同的处理原则

处理无效合同应当遵循恢复原状的原则。实现恢复原状就必然要求当事人应承担返还财产和过错赔偿的民事责任。然而返还财产和过错赔偿的适用非常复杂,因此只有具体问题具体分析,才能正确处理无效合同。     

手法整复治疗儿童伸直型严重移位肱骨髁上骨折

通过67例儿童严重移位的肱骨髁上骨折的手法整复治疗，认为骨折的尽早良好复位、合理的外固定和尽可能的缩短固定时间，肘部软组织损伤的及时有效处理，医生指导下的功能锻炼贯穿于治疗的全过程，解除固定后功能康复的综合治疗，可减少肱骨髁上骨折所引起的肘