用注浆充填法治理郑少高速公路采空区

公路路基采空区或下伏空洞是一种不良的地质现象,严重危害公路路基的稳定和正常运营。文章总结了采用注浆充填法处理郑少高速公路下伏采空区的设计方法、施工技术,为类似工程的治理提供施工方法和技术参数。     

A review of the Effect of α/W ratio on fracture toughness （Ⅱ） experimental investigation in LEFM

In part I of this series, experimental investigation in EPFM （elastic-plastic fracture mechanics） had been discussed. In this paper, experimental investigation in LEFM （ linear elastic fracture mechanics） is given. Fracture toughness tests had been carried out on three different strength steels, using both through-cracked specimens with different α/W ratio and semi-elliptical cracked specimens with variable crack size and shape. Results show that the fracture toughness KIC increases with decreasing α/W when α/W 〈 0.3 for three-point-bend specimens, and that for α/W 〉 0.3, it is independent of α/W. Shallow crack specimens, both through-cracked and surface-cracked, gave markedly higher values than deeply notched specimens. However, the effect of crack shape on fracture toughness is negligible. Results also show that the LEFM approach to fracture is not tenable for design stresses where αc is often very small, far less than 2.5 （ KIC/σy）^2.     

浅谈在公交企业推行方针目标管理的可行性

方针目标管理运用系统论、控制论和管理心理学的基本原理,对企业的全部活动实行全面系统有效的综合管理.公交企业是一个服务性生产企业,人多、面广、难于管理,而方针目标管理具有很强的激励性和应变性,在公交企业推行可以有效提高综合效益.     

侧向风作用下车桥系统气动性能及风屏障的影响研究

采用计算流体力学软件建立桥梁单体、车辆单体以及车桥组合体模型,湍流模型取标准κ-ε模型,计算各模型在不同风攻角时侧向风作用下的气动力系数.考虑风屏障对车辆、桥梁气动性能影响,建立风屏障、桥梁与车辆组合体模型,分析风屏障不同开孔率时车辆、桥梁气动力系数变化规律.结果表明:车辆位于桥上时,桥梁阻力和车辆侧力会增大;桥上车辆侧滚力矩系数明显大于车辆单独存在的情况,且车辆位于桥上迎风侧大于背风侧的情况;安装风屏障后,桥梁阻力和力矩系数随开孔率增大而降低,车辆侧力系数和力矩系数随开孔率增大而增大;为保证风屏障有效性,风屏障开孔率应小于40％.     

地铁环控与综合监控工作站的权限移交

主要讨论北京地铁9号线车站中机电设备的控制操作,通过正常移交和强制收回,在环境与设备监控系统(BAS)工作站与综合监控系统(ISCS)工作站之间实现权限转移,同时阐述权限转移的实现方法和过程,以及画面上权限按钮变化的含义。     

客运专线列车运行方式分析

客运专线采用了一系列新技术设备,动车组列车运行速度高,与既有线相比,客运专线的行车组织方式有其独有的特点。介绍了我国客运专线采用的列车运行控制系统及动车组列车的控车模式,从列车调度员直接指挥行车作业、设置临时限速、调度命令作为行车凭证等方面论述了调度集中的行车组织方式,阐述了跨线运输的概念,分析了动车组列车和普通旅客列车跨线运行的范围和技术条件,并针对目前执行的客运专线技术管理办法提出了建议。     

专用铁路综合数据通信网建设方案探讨

铁路综合数据通信网,是铁路信息化建设的基础平台,建设时首先应完善铁路基础通信网,然后从业务需求、网络结构、技术方案、网络管理、安全策略等几个方面综合考虑,合理规划,有效实现资源最大化的目标,使专用铁路信息化建设更科学、更合理。     

我国首次采用的高架车场及综合维修基地一武汉市轨道交通1号线一期工程石乔 口路车场

武汉市轨道交通1号线一期工程的硚口路车场及综合维修基地是我国目前城市轨道交通车场设计中首次采用的高架车场。设计人员在建筑、结构、工艺等的设计中克服了没有相适应的设计规范和用地面积狭小等特殊环境产生的困难,提出了较合理的布局、在列车荷载作用下房屋结构的荷载计算办法、减振降噪措施,以及对车场轨道布置采取的对策。     

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.