Micro-Grinding Performance of Hard-Brittle Chip Materials in Precision Micro-Grinding Microgroove

The micro-structure on hard-brittle chip materials (HBCMs) surface can produce predominant functions and features. The micro-grinding with diamond wheel micro-tip is an efficient method to machine microstructure on HBCMs. However, different HBCMs and crystal orientation may have a significant influence on the micro-grinding performance. In this paper, the micro-grinding performance along different crystal orientation of HBCMs is investigated. First, a dressed 600^# diamond grinding wheel is used to micro-grind micro-structure on HBCMs. Then, the experiment of micro-grinding force test is completed. Finally, the quality of microgroove, the grinding ratio and the micro-grinding force are investigated and they are related to the crystal orientation of HBCMs. It is shown that the stronger resistance to the micro-crack propagation has the best quality of microgroove and the smallest grinding ratio. Moreover, the hardest single-crystal SiC has the best machinability and the micro-grinding force is 38.9%, 10.8% and 46.8% less than the one of sapphire, single-crystal Si and quartz glass, respectively. The direction to micro-grind easily is the crystal orientation 〈10\(\overline 1 \)0〉 for single-crystal SiC and sapphire. In addition, the micro-grinding force increases with the increase of the micro-grinding depth and feed rate and decreases with the increase of the grinding wheel speed.     

济南轨道交通R1线工程新技术探索及应用

R1线是济南首条轨道交通线路,在工程建造过程中探索、应用了多项绿色技术,详细介绍结构工程中的清水混凝土技术,深基坑支护及稳定性控制技术,混凝土刚性防水技术及预制构件应用技术;车辆基地上盖物业开发和建筑废弃物再利用技术;设备系统中的可调通风型站台门和隧道嵌装型蒸发冷凝技术等改造工艺,以及"海绵"设施应用、高架车站光伏发电和中压能馈等自然资源利用技术,以期为后续济南和其他城市轨道交通建设提供参考和借鉴。     

铁路车地广播通信系统中喷泉码的应用研究

铁路通信系统具有其特殊的行业应用需求,如高可靠性,低误码率。研究喷泉码(RaptorQ)技术,作为一种前向纠错的编码方式应用于铁路广播通信系统中,可在保证系统误码率的同时,最大限度的利用系统资源。同时,依赖于喷泉码自身的编码特点,译码是否成功仅与接收到信息数量相关,部分信息的丢失不会对应用层信息造成影响。对不同丢包率条件下,达到不同误码率等级要求时所需的译码开销进行仿真,实现对喷泉码性能研究的目的。     

The Reinforcement Analysis of Prestressed Anchor Frame Beam in the Deep Cutting Slope under Three Dimensional Strong EarthquakeEI北大核心

Research purposes: In order to further study the reinforcement of prestressed anchor frame beam in the deep cutting slope under three dimensional strong earthquake, a model of the deep cutting slope is built through FLAC 3D simulation software, the seismic wave to the model from three directions of x,y and z is input, and the dynamic response of the slope is analyzed. Then, the prestressed anchor frame beam reinforcement measures are applied to the model, and this paper analyzes the reinforcement effect of the prestressed anchor frame beam to the deep cutting slope under three dimensional strong earthquake. Research conclusions:(1) The prestressed anchor frame beam has a good effect on restraining the horizontal displacement of the deep cutting slope. (2) Under the three dimensional strong earthquake, the prestressed anchor frame beam has a good effect on the horizontal acceleration and horizontal velocity of the deep cutting slope, which reduces the peak of horizontal acceleration and horizontal velocity. (3) Through the comparison of the response before and after the reinforcement of the prestressed anchor frame beam is given under the 9 degrees three dimensional strong earthquake, it can be concluded that the prestressed anchor frame beam can provide good reinforcement effect to the deep cutting slope. (4) This research can be used for reference to the earthquake resistance of the slope engineering. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

车载ATP系统总线技术分析

针对城市轨道交通车载ATP系统的总线应用,分析车载ATP总线的发展趋势及应用案例,提出ATP总线设计思路。     

坚持高标准、讲科学、不懈怠 以客专建设为契机 以体制创新为手段 推进电务工作全面发展——在2010年全路电务工作会议上的报告(节选上)

今天召开2010年全路电务工作会议。这次会议是在全路深入学习实践科学发展观,铁路建设进入快速发展的形势下召开的。这次会议的主要任务是：深入贯彻部党组的总体部署,落实全国铁路工作会议和运输安全工作会议精神,以科学发展观为指导,按照“高标准、讲科学、不懈怠”的要求,进一步加强和改进电务安全管理,认真总结2009年工作,全面部署2010年电务重点任务。     

T.J D2-B型车辆减速器使用情况分析

车辆减速器是重要的调速设备,其产品质量与维护状态的好坏,直接影响着驼峰解编作业的效率与安全。对这种设备在唐山东站驼峰的使用维修及试验效果进行了分析探讨。     

浅谈“窑村站事故”教训

为了吸取窑村站事故教训,从工程的设计、施工、验收,开通后维修等环节分析事故原因,找出事故根源,指出ZPW-2000制式轨道电路定型组合图的缺陷,并提出改进建议。     

基于TCP/IP协议的信号集中监测与CTCS-3级列控系统各子系统连接架构分析

CTCS-3级列控系统是多子系统高度集成化的列车运行控制系统,其各个子系统需要运转协调才能确保整体系统有序平稳地工作,而各子系统间无缝合理的连接架构无疑是各子系统实时交互通信的重要保证。着重解析信号集中监测子系统与其他各子系统的网络连接架构,从而完成对各子系统信息的集中监测,为用户提供及时迅捷的问题解决方案。     

城市轨道交通CBTC中准无缝切换的研究

在城市轨道交通中,当列车运行跨越由多个AP构成的大型无线网络时,存在切换的问题,切换过程中不可避免引起时延和丢包率问题。安全性是轨道交通永恒的主题,过长的时延和重要数据丢失都会引起行车安全。提出了基于位置的切换算法,减少切换时延的同时实现在相邻AP点间接力数据传输,消除丢包率,实现准无缝切换。