无单元法在孔洞应力集中问题中的应用

基于滑动最小二乘近似的无单元法摆脱了有限元法节点和单元之间彼此联系的约束，能够比较自由地根据实际几何实体情况布置节点、积分子区域，并能够根据可能的位移形式采取合适的基函数。本文对无单元法的基本理论进行了简要阐述，并以孔洞应力集中问题作为数值算例来说明无单元法在求解边值总是上的灵活性。     

Effect of vehicle vibration environment of high-speed train on dynamic performance of axle box bearing

In this study, we developed a comprehensive three-dimensional vehicle–track coupled dynamics model considering the traction drive system and axle box bearing. In this model, dynamic interactions between the axle box bearing and other components, such as the wheelset and bogie frame, are considered based on a detailed analysis of the structural properties and working mechanism of the axle box bearing. A few complicated dynamic excitations, such as the time-varying mesh stiffness of gears, time-varying stiffness of bearing, bearing gaps and track irregularities, are considered. Then, the dynamic responses of the vehicle–track system are demonstrated via numerical simulations based on the established dynamics model. The results indicate that the traction drive system and track irregularities can significantly influence the dynamic interactions of the axle box bearing. The necessity of considering the excitation caused by gear meshing and track irregularities when assessing the dynamic performance of the axle box bearing is demonstrated.     

基于潜在冲突量的交叉口安全评价方法研究

提出了潜在冲突量的概念，并对其进行了分类。通过车速、交通量、车道宽度等易获取的交通参数来推算交叉口潜在冲突量。引入混合交通当量，将潜在冲突量与混合交通当量比值作为交叉口安全评价的指标，并选取灰色聚类的方法对交叉口进行安全程度的评价。对桂林市的9个交叉口进行了安全程度的评价，评价结果与实际状况相吻合。     

内燃机车柴油机动力系统关键零部件

1柴油机活塞柴油机活塞、活塞环和气缸套是柴油机的心脏。活塞从制造方法而青，有锻造与铸造之分；从材料与种类而言，主要有铝活塞、钢活塞、整体球铁活塞和钢顶铁裙、钢顶铝裙组合式活塞等。衡量活塞的制造水平，一般有几个方面：     

光纤陀螺罗经辅助ADCP导航方法研究

研究了利用光纤陀螺罗经辅助声学多普勒流剖面仪(acoustic Doppler current profile-ADCP)进行导航定位的方法,分析比较了ADCP独立进行航位推算和光纤陀螺罗经辅助ADCP进行组合导航的精度,研究结果表明,光纤陀螺罗经辅助ADCP进行组合导航的精度至少提高1倍以上.其定位精度可以达到130m/h.     

Prediction of hydrodynamic forces on a moored ship induced by a passing ship in shallow water using a high-order panel method

A three-dimensional high-order panel method based on non-uniform rational B-spline (NURBS) is developed for predicting the hydrodynamic interaction forces on a moored ship induced by a passing ship in shallow water. An NURBS surface is used to precisely represent the hull geometry. Velocity potential on the hull surface is described by B-spline after the source density distribution on the boundary surface is determined. A collocation approach is applied to the boundary integral equation discretization. Under the assumption of low passing speed, the effect of free surface elevation is neglected in the numerical calculation, and infinite image method is used to deal with the finite water depth effect. The time stepping method is used to solve the velocity potential at each time step. Detailed convergence study with respect to time step, panel size and Green function is undertaken. The present results of hydrodynamic forces are compared with those obtained by slender-body theory to show the validity of the proposed numerical method. Calculations are conducted for different water depths and lateral distances between ships, and the detail results are presented to demonstrate the effects of these factors.     

VD4型真空断路器故障分析

ABB公司生产的VD4型真空断路器在港口中压配电系统中被广泛使用,但在装设“五防”机构时,会出现由于机械连锁失灵而导致断路器无法合闸的现象。     

汽车交流发电机的匹配设计

交流发电机作为现代汽车电源部分的一个重要部件,其工作性能的好坏对车辆的运行非常重要。本文介绍交流发电机的分类、工作特性及其匹配设计。     

美国磁浮系统的经济分析及启示

通过介绍美国磁浮系统研究的有关基础数据和方法,包括研究背景、收入与成本的估算方法以及磁浮系统在单线和网络情况下的财务评价结论,对美国磁悬浮系统经济可行性研究进行了详细介绍.结合中国经济和交通运输业背景,认为磁浮建设应分阶段、分地域逐步进行,并应从提高设备国产化程度、提供高质量服务加强项目整体规划和商业运营等方面提高磁浮系统收益,降低成本.     

双层隔振系统结构参数改变对结构振动的影响

本文应用有限元法研究了流-固耦合条件下船舶隔振系统结构振动问题的计算方法,在考虑流-固耦合状态下,详细研究了双层隔振系统主要结构参数改变对系统结构振动响应的影响,如上下层隔振器刚度、中间体与被隔设备的质量比以及基座弹性模量等,同时进行了计算和试验结果对比分析.