列车空气动力性能与流线型头部外形

采用数值计算、动模型试验、风洞试验、实车试验和理论分析等方法,研究列车流线型头部长度、宽度、高度及耦合外形对列车交会压力波、空气阻力和升力的影响,得到一系列理论关系式。研究结果表明:①增加列车流线型头部长度,可以有效地改善列车空气动力性能,列车交会压力波随流线型头部长度增加而呈对数减小,头车阻力、升力绝对值均随流线型头部长度的增加呈线性减小,尾车阻力与流线型头部长度呈二次幂减小;②流线型头部纵向对称面最大控制型线从外凸到内凹,列车空气阻力、空气升力和交会压力波基本不变,减小鼻尖部位过渡曲线的曲率半径可以有效降低列车交会压力波;③流线型头部俯视最大控制型线为方形时产生的交会压力波最小,尖梭形的头车空气阻力和升力绝对值较小;④减小列车空气阻力和降低列车交会压力波,既矛盾又统一,列车气动头部外形设计需要综合考虑各种因素。     

微分法在有限元分析中的应用

基于有限元原理及结构的平衡微分方程,提出了一种求解结构单元形函数的方法。首先,根据结构单元的变形微分方程求解结构变形的常系数解析式;其次,根据单元的边界条件求解相应的系数表达式,并将求出的系数表达式代到解析式中,形成关于单元局部坐标的解析式;最后,提取单元节点广义位移向量,形成单元的形函数矩阵。运用所提出的方法对结构典型杆单元、梁单元的形函数进行求解后发现,所获得的形函数与相关文献提供的形函数完全一致,表明所提方法正确有效,并且同样适用于其他结构单元形函数的求解,从而为有限元的进一步推广和拓展提供了一条行之有效的途径。     

三维形状投影光栅测量技术及其在船用柴油机设计中的应用

系统介绍了两种投影光栅三维形状测量技术的原理、方法、硬件和软件，并介绍在船用柴油机设计中的应用。这些技术具有实用、非接触、全场显示、直观、实现容易及便于设计人员接受等一系列优点，是光学、计算机图象处理和ＣＡＤ三种技术有机结合。     

双中间轴变速器副箱主轴的扭矩分析与验证

为提高变速器的承载能力,降低承载部件的失效风险,提高汽车运行的可靠性,对变速器主要零部件的承载能力进行分析与验证已成为变速器设计过程中最关键的环节。文章通过分析并利用静扭试验台架对变速器副箱主轴进行实际工况的加载与校核,进一步探究该部件的承载能力,以确保达到变速器的设计要求。台架试验方法在变速器设计过程中发挥着重要作用,是验证变速器性能的重要手段、     

城市综合交通枢纽静态标识布设研究

城市综合交通枢纽通过多种出行方式的整合,缩减了乘客的换乘时间;但庞大的枢纽建筑,增加了乘客寻找＂目的地＂的难度。通过对静态标识相关的现行国家标准和地方标准分析,提出静态标识的布设目标,梳理布设流程,制定布设的总体原则和各类静态标识布设原则。研究的结果将为相关的标准研究和设计工作提供帮助和支持。     

Integrated planning of static and dynamic charging infrastructure for electric vehicles

This paper investigates the optimal deployment of static and dynamic charging infrastructure considering the interdependency between transportation and power networks. Static infrastructure means plug-in charging stations, while the dynamic counterpart refers to electrified roads or charging lanes enabled by charging-while-driving technology. A network equilibrium model is first developed to capture the interactions among battery electric vehicles’ (BEVs) route choices, charging plans, and the prices of electricity. A mixed-integer bi-level program is then formulated to determine the deployment plan of charging infrastructure to minimize the total social cost of the coupled networks. Numerical examples are provided to demonstrate travel and charging plans of BEV drivers and the competitiveness of static and dynamic charging infrastructure. The numerical results on three networks suggest that (1) for individual BEV drivers, the choice between using charging lanes and charging stations is more sensitive to parameters including value of travel time, service fee markup, and battery size, but less sensitive to the charging rates and travel demand; (2) deploying more charging lanes is favorable for transportation networks with sparser topology while more charging stations can be more preferable for those denser networks.     

单叶片螺旋钢桩竖向承载特性数值分析

为分析单叶片螺旋钢桩在砂土地层竖向抗压承载特征,结合单叶片螺旋钢桩现场静载试验进行有限元软件模拟。将数值计算结果与现场实测数据进行对比分析,验证其数值计算结果的可靠性,其次采用该有限元软件分别模拟不同相对密实度砂土中几何参数不同的单叶片螺旋钢桩静载试验而得到不同荷载-位移曲线,同时将螺旋叶片直径的5%位移值对应荷载作为桩极限承载力。考虑砂土相对密实度,钢桩埋深,螺旋叶片直径,中心钢轴4个参数变化对单叶片螺旋钢桩极限承载力影响。结果表明:单叶片螺旋钢桩桩周土层的相对密实度和桩埋深是影响承载力的主要参数,螺旋钢桩叶片直径影响次之,钢轴直径的影响最小;同时,单叶片螺旋钢桩极限承载力增量百分比在松砂中最大,中密砂次之,密砂最小。     

大吨位异形钢桥塔施工支架设计研究

为研究不同支架方案对异形钢桥塔施工过程的影响,以新首钢大桥为背景工程做了对比分析,进而分析桥塔施工过程对桥塔-支架整体耦合模型内力、位形的影响,研究支架设计过程中的一些细部问题.结果表明:格构式支架受力明确、合理,施工方便且用钢量小,建议采用该支架方案;桥塔采用反变形的施工方案,可以很好地满足桥梁结构设计线形要求;在格构式支架设计中应避免多个斜撑相贯于立柱同一节点造成支架立柱受力不均匀、部分立柱受力急剧增大的问题;在有限元模拟中支架顶部与高塔连接建议采用铰接方式进行简化处理..     

Geometrical design of blade＇s surface and boundary control of Navier-Stokes equations

In this article a new principle of geometric design for blade＇s surface of an impeller is provided. This is an optimal control problem for the boundary geometric shape of flow and the control variable is the surface of the blade. We give a minimal functional depending on the geometry of the blade＇s surface and such that the flow＇s loss achieves minimum. The existence of the solution of the optimal control problem is proved and the Euler-Lagrange equations for the surface of the blade are derived. In addition, under a new curvilinear coordinate system, the flow domain between the two blades becomes a fixed hexahedron, and the surface as a mapping from a bounded domain in R2 into R3 , is explicitly appearing in the objective functional. The Navier-Stokes equations, which include the mapping in their coefficients, can be computed by using operator splitting algorithm. Furthermore, derivatives of the solution of Navier- Stokes equations with respect to the mapping satisfy linearized Navier-Stokes equations which can be solved by using operator splitting algorithms too. Hence, a conjugate gradient method can be used to solve the optimal control problem.     

钢桁腹组合梁桥静载试验分析

为检验某钢桁腹预应力混凝土组合梁桥的承载能力是否满足正常使用状况的要求,对该桥在静载作用下的挠度、应力进行试验分析.研究结果表明,该桥的受力性能和正常使用状态极限承栽力均满足设计要求,结构工作状况良好.