Multibody dynamics modelling of the freight train bogie system

Previous work in the railway technology laboratory at Virginia Polytechnic Institute and State University (Virginia Tech) focused on better capturing the dynamics of the friction wedge, modelled using three-dimensional rigid body dynamics with unilateral contact conditions. The current study extends the previous work to a half-bogie model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the sideframe. The half-bogie model was derived using MATLAB and functions as a three dimensional, dynamic, and multibody dynamics model comprised of four rigid bodies: a bolster, two friction wedges, and a sideframe assembly. This expanded model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and sideframe), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the sideframe are constrained to have only the vertical degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialised with a pre-defined yaw (rotation around the vertical axis) and the sideframe may be initialised with a pre-defined pitch/toe (rotation around the lateral axis). The results of the multibody dynamics in half-bogie model simulation are shown in comparison with results from NUCARS^®, an industry standard in train-modelling software, for similar inputs.     

重大突发公共卫生事件下城市应急医疗物资优化调度研究

针对新型冠状病毒肺炎（新冠肺炎）疫情防控中应急医疗物资调度不尽合理、集配中心中转效率不够高等问题，重新设计了重大突发公共卫生事件下城市应急医疗物资调度与配送体系，并给出了应急医疗物资的分类方法。从医疗物资使用需求和库存估计可使用时间2个维度构建需求点紧急度指标，考虑突发公共卫生事件特征，以加权的需求满足率最大化为主要目标、车辆行驶距离最小化为次要目标，构建应急医疗物资动态分配模型，并通过算例验证了模型的有效性和可行性。结果表明：所构建的模型能够兼顾医疗物资分配的公平和效率，符合突发公共卫生事件中应急医疗物资供给和需求的动态变化特性，确保在物资短时间供给不足的情况下各需求点也能公平获取一定比例的物资；且模型仅要求各需求点上报各种品类医疗物资的使用人数和库存量，同时模型还给出数据缺失时的自动计算办法，可操作性更强；运用紧急度指标对需求满足率最大化目标进行校正，解决了各需求点因需求量差异对公平分配造成的影响，使得应急医疗物资分配更加合理。研究成果结合了新冠肺炎疫情防控中应急医疗物资调度的具体过程，使得分配模型更符合实际需要，可为城市应急医疗物资优化调度提供决策依据。     

城市轨道交通交直流一体化电源成套装置资源共享可行性分析

对地铁车站低压配电EPS(应急照明电源装置)设计及供电系统交直流操作电源设计方案进行了总结。经过对现有EPS与变电所交直流操作电源合并及分开设置方案进行经济技术性比较,综合考虑可靠性、运营管理便利性、系统综合维护成本后,推荐EPS与变电所操作电源分开设置方案。     

关于大口径给水管道穿越既有公路的安全评价分析

针对某给水管线穿越既有公路项目实际情况,对其安全审查和安全评价进行深入分析,最后得出安全审查和评价合格,能满足现行法律法规和规范标准要求,但仍需重视施工过程中的安全控制工作的结论,为类似工程项目施工提供可靠的参考和借鉴,进而从根本上保证施工安全。     

Serial private infrastructures

This paper investigates private supply of two congestible infrastructures that are serial, where the consumer has to use both in order to consume. Four market structures are analysed: a monopoly and 3 duopolies that differ in how firms interact. It is well known that private supply leads too high usage fees, and that a serial duopoly leads to even higher fees than a monopoly, as firms are monopolists on their sections. But, as this paper finds, a duopoly can also lead to a different capacity rule than the first-best one, and this distortion differs from with two parallel facilities. Finally, four auction formats for the right to build and operate facilities are investigated. With a bid auction, the competition is on how much to pay the government. This auction leads to the same outcome as no auction. An auction on the facility’s capacity leads to an even lower welfare than no auction, as firms set overly large high capacities. Conversely, an auction on the generalised price or number of users leads to the first-best outcome, which they do when the facilities go to one or two winners and both with serial as with parallel facilities.     

构建港口服务供应链 提高港口物流效率

阐述了港口与港口物流的关系,提出了港口服务型供应链的概念,指出提高港口物流效率的重点是提升其管理水平。并就具体做法提出了若干切实可行的措施。     

转K1型转向架组装工艺

介绍了转K1型转向架的结构特点和关键技术参数,着重分析了侧架导框的加工、侧架与支撑座板的组焊和转向架的组装工艺等。     

对部颁标准《客运专线铁路信号产品标准（暂行）铁路信号电源屏》的思考

对铁道部新颁布的《客运专线铁路信号产品标准（暂行）铁路信号电源屏》标准进行了探讨，指出与现行铁路信号电源屏部颁标准不同部分，以及暂行标准尚存在的问题，并提出改进建议或思路。     

长沙机务段整备场隔离开关故障分析及对策

在各机务段整备场广泛使用的电动隔离开关,由于环境复杂,缺乏良好的工作环境而时常发生故障,本文通过对株洲机务段长沙整备场隔离开关电动操作机构(二次系统)的故障原因进行分析,阐述了对电动操作机构(二次系统)进行保护的对策.     

京沪线南翔牵引变电所有源无源混合补偿方案

介绍了采用低压侧两相式有源与无源混合补偿方案，可以有效降低补偿装置的补偿容量，减小补偿装置的体积，并将该方案实际应用于工程实践，仿真结果验证了补偿方案的正确性与有效性，该装置已投入运行，为新补偿方案在国内推广应用奠定了基础。