天津港南疆复线公路桥特色设计总结

天津港南疆复线公路桥主桥是一个主跨64m的五跨悬浇连续梁,引桥是支架现浇的预应力箱梁。从表面上看,其跨径不大,桥型简单,似乎很普通。但是因其所处环境、位置的原因,大桥的设计和施工有很多独特的地方。该文从设计角度对其特殊设计加以总结阐述．可供借鉴参考。     

动力总成悬置系统的优化设计及仿真分析

建立了车辆动力总成悬置系统的动力学模型，应用能量法解耦理论进行了优化设计．并通过机械系统动力学仿真分析软件ADAMS对优化前后系统的动力性能作了仿真研究和对比分析。     

预应力在码头超长结构中的应用研究

该文利用通用有限元分析软件ANSYS,针对一典型的码头超长结构工程实例进行非线性分析,并对预应力的作用进行模拟,揭示了该种结构在渐变温度场作用下的应力和变形特征,所得结论可为实际工程提供理论上的指导。     

桩周土的损伤对桩基沉降的影响

在全深度——变深度的剪切弹簧模拟桩侧土对桩的约束的基础上,考虑桩周土的损伤对桩基沉降的影响,推导了一组确定桩的轴向荷载——沉降曲线的解析算式,经算例计算表明,考虑桩周土损伤来估计桩的承载力是合理的可行的。     

数字视频信息管理系统在高速公路监控联网中的应用

简述数字视频信息管理系统的总体设计原则、设计方案说明,以及数字视频信息管理系统在浙江省高速公路监控联网中的应用。     

摩托车接地线路的可靠性分析

通过分析NF125T-4摩托车的接地线路,提出了改进方案,消除了主撑回位时与起动踏杆间的碰火现象,保证了接地的可靠性.     

半承载式客车车身结构有限元分析

以梁单元模型为基础,通过将复杂部件建立实体单元模型来生成梁体混合模型的方法,建立半承载式客车车身结构有限元模型。并对车身结构进行4种典型工况下的强度、刚度以及模态分析。最后通过静态应力试验验证该模型的正确性。     

曲轴动态应力模拟及多轴疲劳计算

建立了某4缸柴油机曲轴轴系和主轴承座的有限元模型,采用EXCITE软件对曲轴轴系和连杆活塞组进行了多柔体的动态仿真,模拟了不同转速工况下曲轴随曲柄转角变化的动态应力。对曲轴动态应力结果进行了多轴疲劳计算,校核了不同运转工况下曲轴的疲劳安全系数,解决了弯扭耦合与多子系统交叉耦合时整体曲轴疲劳可靠性计算的难题。     

基于改进遗传算法的最优路径求解

动态路径诱导系统(dynamic route guidance system,DRGS)是通过提供基于实时交通信息的最优路径来引导交通流的,因此,最优路径的求解是关键.而遗传算法具有全局寻优和潜在并行的特点,对求解最优路径具有一定优势.但采用序号编码方式进行遗传操作时会产生大量无效路径.文中结合城市道路交叉口左转、右转、直行等转向行为,设计了一种新的基于转向行为的编码方式,减少了染色体在交叉、变异时的无效路径的生成.算例表明,这种编码方式可以有效提高算法收敛性,更容易获得最优解.     

Development of hydrogen-compressed natural gas blend engine for heavy duty vehicles

Natural gas fuel, as an alternative energy source of transportation, has been used widely since it has an advantage of low emission levels. However, new technologies are required in order to meet the reinforced emission regulations. For this purpose, research into the development of hydrogen-compressed natural gas (HCNG) blend engine was carried out to evaluate its feasibility and emission characteristics. The Engine Research Department at the Korea Institute of Machinery and Materials carried out a large number of tests based on various parameter changes that could affect the performance and emission of HCNG engine in different operating conditions. An earlier stage of the research project focused on the lean combustion of a HCNG engine for heavy duty vehicles to meet the EURO-VI standards. An 11-L/6-cylinder CNG engine was used for the test. The effects of the excess air ratio change were assessed based on various content ratios of hydrogen in the natural gas fuel. In the later part of the HCNG research, a stoichiometric mixture operation was suggested to meet reinforced emission regulation without requiring a De-NOx system. Additionally, an exhaust gas recirculation (EGR) system was introduced for the purpose of improving thermal efficiency and durability. The optimal operating conditions were selected to achieve the best thermal efficiency to meet the required emission levels. In this paper, we demonstrate that a HCNG engine can achieve a significant decrease in NOx emissions, as compared to that of a CNG engine, while meeting the requirements of the EURO-VI standards during a transient mode cycle test. EGR can suppress the weakness of stoichiometric mixture combustion strategy, such as the deterioration of the durability and thermal efficiency, while the emission level can be lowered with the use of a three-way catalyst. The possibility of further reduction of emissions and CO2 with EGR was evaluated to access practical application of a HCNG engine in the field. From that evaluation, the HCNG engine with stoichiometric mixture operation for heavy duty vehicles was developed. The emission levels of HCNG engine were 50 % lower when compared to the EURO-VI standards with a greater than 10 % decrease in CO₂ compared to that of a natural gas engine.