运行中地铁列车的车内外压力变化特性研究

通过对我国某型地铁列车进行隧道空气动力学实车线路试验,得到地铁列车实际运行过程中车内、外压力变化规律。试验结果表明:该型地铁列车车内压力变化满足我国地铁设计规范舒适度评价标准及美国地铁人体舒适度评价标准。地铁列车运行过程中,最长隧道区间的车内、外压力变化幅值明显大于其它隧道;列车以不同速度和模式运行中,车内1.0 s、1.7 s、3.0 s时的压力变化幅值和车外各测点压力变化幅值均不相同,车体表面测点压力变化由车头至车尾方向呈逐渐减小的趋势。     

内燃机活塞温度场的轴对称组合边界元分析

采用常数-线性组合边界元计算轴对称热传导问题,既可减小奇异点计算的困难性,又提高了计算精度。本文运用FORTRAN77算法语言编制了包含有三种类型边界条件在内的轴对称组合边界元分析程序,具体分析了6135ZG柴油机活塞的温度分布。结果表明,应用边界元法分析轴对称活塞温度场,计算工作量比有限元的计算量显著减少,而计算结果同有限元结果吻合得较好,与实际测量结果相比,最大相对误差仅为1％。     

柱式桥墩盖梁内力计算方法探讨

笔者阐述了两种不同计算图式下盖梁内力计算方法,并进行了对比分析.分析表明,当考虑立柱刚度影响时,盖梁内力将进行二次分配,致使跨中正弯矩减小、支点负弯矩增大(称之为“刚架效应”),随着立柱与盖梁的线刚度比的增大,此种效应越显著.当立柱与盖梁的线刚度比较小时,可采用简化的双悬臂简支梁(连续梁)图式,但在支点截面应作适当的加强处理;而对于重要桥梁或立柱与盖梁的线刚度比较大的桥梁,宜采用双悬臂刚架结构图式进行计算.     

An Experimental Study on the Drag Property of High Temperature Particles Falling into Cold Liquid Pool

This experiment is to study the special resistant induced by the high-speed evaporation surrounding the moving high-temperature particles. An observable equipment was designed, in which the first 11 experiments were performed by pouring one or several Zirconia spheres with various high-temperature and a diameter of 3-10mm into a water pool. The particles falling-down speeds were recorded by high-speed photographic instrumentation,and pressures and water temperatures were measured. A comparison between the experiments with cold and hot spheres respectively, employing three different sphere types each, was presented. The experimental data, com-pared with the theory of the evaporation drag model, are nearly identical.     

基于曲轴扭振诊断内燃机各缸作功状况

提出依据实测曲轴某一个惯量的扭转振动，反算各缸的平均有效压力，藉以诊断多缸内燃机各缸作功状况。用子空间法找出各缸平均有效压力与测点扭振角度间的传递关系，再用最小二乘法求解矛盾方程，进而得到各缸的平均有效压力。在6135柴油机上验证了所采用方法的正确性。     

外、体内预应力混合配筋与节段预制拼装技术

体外、体内预应力混合配筋结构与节段预制拼装施工工艺相结合的解决方案具有广阔的发展前景，这种结构施工工艺简单、施工迅速、耐久性好，克服了一般后张预应力混凝土工艺复杂、耐久性差的缺点。结合凫洲大桥引桥工程（普通后张法施工的连续梁）进行对比分析。     

郑州至开封城市通道顶管施工监测方案探讨

对在建项目郑州至开封箱型通道顶管施工监测的目的、内容、方法等进行探讨,可为其方案的实施提供理论依据,并为今后此类箱型通道的设计、顶管施工及其监测积累一定的经验.     

完善企业内部会计控制制度的几点思考

内部会计控制制度是企业内部控制机制的一个重要组成部分,也是保证企业高效运行的重要制度。本文将从阐述内部会计控制与内部控制的关系入手,论述加强和完善内部会计控制制度的必要性,以及提出相应的策略。     

A new approach to inspect the internal pressure of vacuum switchgear

A new approach is developed to inspect the internal pressure within the vacuum switchgear by no means of magnet-exciting coil, micro-discharge threshold voltage Ud and field emission threshold voltage Ue, all of which are available in laboratory. Experimental results show that internal pressure is a function of the ratio of the micro-discharge threshold voltage to the field emission threshold voltage i.e., Ud/Ue. By this method, the internal pressure in the range of 100-10-4 Pa within vacuum chambers can be inspected without magnet-exciting coil which is required in conventional magnetron discharge method.     

某型舰船阀门内漏温差检测法可行性研究

文章针对某型舰船阀门的使用环境状况和内漏特性，提出一套方便可行的温差检测方法及检测系统，通过检测高温介质断流后阀门发生内漏时其前后温度的差异值，来确定阀门的内漏情况，使阀门内漏得到及时监控和处置。