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.     

Lattice-based group signature with verifier-local revocation

Among several post quantum primitives proposed in the past few decades, lattice-based cryptography is considered as the most promising one, due to its underlying rich combinatorial structure, and the worst-case to average-case reductions. The first lattice-based group signature scheme with verifier-local revocation(VLR) is treated as the first quantum-resistant scheme supported member revocation, and was put forward by Langlois et al. This VLR group signature(VLR-GS) has group public key size of O(nm log N log q), and a signature size of O(tm log N log q log β). Nguyen et al. constructed a simple efficient group signature from lattice, with significant advantages in bit-size of both the group public key and the signature. Based on their work, we present a VLR-GS scheme with group public key size of O(nm log q) and signature size of O(tm log q). Our group signature has notable advantages: support of membership revocation, and short in both the public key size and the signature size.     

轴承压装力-位移曲线作轴承压装合格判定的可行性分析

通过对影响货车滚动轴承压装力因素的分析,得出了轴承压装力与位移之间的数学关系,并依据353130B滚动轴承及RE2B轮对的结构尺寸,得出了353130B滚动轴承压装力与位移之间的理论曲线。根据现场轴承压装相关经验数据统计,对压装理论曲线的边界条件进行了分析,为采用压装力一位移曲线判定轴承压装质量方法进行了可行性分析。     

25DT“神州号”动车组空调漏水原因及措施

分析了25DT动车组空调机组漏水原因及现行规程存在的问题,提出了相关防护措施及改进建议.     

城市轨道交通综合监控系统中时间表控制功能的应用

在城市轨道交通综合监控系统中,时间表控制功能可以按照预先指定的时间条件自动地进行设备控制,保证设备按照精确的时间进行起停,减少了各级调度员的工作量,降低了人为控制的出错概率.时间表控制能按工作日、周末、节假日采取不同的设备控制策略,也能按设备控制要求进行单次控制或者一定时间内指定时间间隔的多次控制.该功能已成功应用于成都地铁1号线的综合监控系统中.     

安全气囊气体发生器壳体精密成形方法的研究

论述了安全气囊气体发生器壳体的基本结构形式及其不同的成形方法。提出了流动控制成形力的计算公式、控制腔位置的判断准则及其形状和尺寸的设计方法。通过试验表明，所开发的流动控制成形技术可节约原材料、提高工作效率及产品质喇，具有显著的技术经济效益。     

基于试验的自动变速器故障诊断分析

通过现有的失速试验、时滞试验、油压试验、道路试验、故障码扫描等多种试验方法，可在变速器解体之前获得故障信息。在深入分析自动变速器结构及各元件功能的基础上，将各种试验进行合理的逻辑组合，对获得的故障信息进行逻辑分析，最终可将故障源限定在最小的范围之内。分析探讨了这种方法的可行性。     

自动变速器故障的功能分析法

功能分析法，即是通过对变速器各部分结构元件工作原理的分析，了解它们在整个系统中的作用，在此基础上分析得出各结构元件失效将产生的后果，并将故障现象与可能的故障源建立一一对应的联系，最后总结归纳出故障源群组的方法。它能较全面地概括出自动变速器可能产生的各类故障，为准确诊断自动变速器故障创造了有利条件。     

中国和美国汽车保险比较——谈投保人对保险费率的影响

汽车保险是我国财产保险中份额最重的一项，随着中国汽车工业的迅猛发展，我国的汽车保险业也将迎来一个黄金期。但是与汽车王国美国相比较，我国汽车保险费率的厘定，更多地关注汽车本身，而忽略投保人这一主体因素，更多地关注人的因素，是加入WTO后的我国汽车保险人值得重视的一个话题。     

现代轿车自动变速器技术分析

自动变速器作为现代汽车传动系统中一个十分重要的总成，对车辆诸多性能的提高起着重要的作用。世界轿车自动变速器技术的发展无疑反映了当今该项技术的潮流，自动变速器技术正朝着结构多挡化、性能高效化、换挡智能化和舒适化等方向发展。