高速客车通过曲线时的动态响应及安全性研究

本文从国内外各型客车转向架中选取一组计算参数,在建立客车横向动力学模型的基础上,研究高速客车通过曲线时的动态响应及安全性,并对转向架各悬挂参数的合理选择进行分析,以及对适应于高速客运的线路提出了要求。     

Repair and Strengthening Assessment of Existing Bridges Based on Time-Dependent Reliability Analysis

The strategy on repair and strengthening of existing bridges based on time-dependent reliability was analyzed with the maximum expected benefit as the objective function. A sample of risk-ranking decision was illustrated based on updated inspection information with 35 survival age. The effect of improvement of live loads and difference of repair methods on time-dependent reliability of existing bridges are considered. The results show that the decision method can be used in real project, with the cost of failure consequence and the risk of failure considered.     

东风9型内燃机车车体的强度与刚度分析

本文在分析东风_9型内燃机车车体结构及载荷特点的基础上,建立了其计算模型,并用有限元法对机车车体进行了刚度和强度校核,提出了各种工况下许用应力的确定方法。     

低轮轨力转向架车轮辐板形状优化的可行性研究

增加列车轴重是提高铁路货运能力的一种有效手段,但货车轴重的增加,必然引起一系列的强度问题。采取把车轮直径由840mm增大为915mm,可以保证强度要求,但也增加了轮对死重。本文探讨了一种在不增加轮径的前提下,仅通过对车轮辐板进行形状优化,就可使其在25t轴重下可靠工作的优化设计方法。结果表明,对车轮轮辐断面形状优化后,可较大幅度地降低其温度应力,有可能使840mm车轮在25t轴重下的应力接近甚至低于原结构在21t轴重下的应力水平。     

机场跑道长度可靠性设计方法

将可靠性理论引入跑道长度计算,对有关变量作了统计分析,获得了空气相对密度、风速、驾驶误差系数、着陆接地点到跑道端的距离等变量的分布规律。采用遗传算法和重要抽样法进行了跑道长度可靠度分析,提出了一种基于可靠性理论的跑道长度设计方法,对永备机场进行了可靠性评价,其平均失效概率是4 75×10-4,实际失效概率为2×10-43×10-4,两者比较接近。计算结果表明可靠性方法对跑道长度设计和安全性评价是可行的。     

70%低地板轻轨车建模及动力学分析

建立了70％低地板轻轨车的动力学计算模型，对建模过程中非动力转向架、独立车轮、车体间的铰接结构等关键部件的处理方法进行了分析，并运用SIMPACK多体动力学仿真软件分析了该计算模型的运动稳定性、曲线通过性及运行平稳性等动力学性能。结果表明，该车具有良好的蛇行运动稳定性、曲线通过性及运行平稳性，能够满足运行的要求。     

Modified Weighting for Calculating the Average Concentration of Non-Point Source Pollutant

The concentration of runoff depends upon that of soil loss and the latter is assumed to be linear to the value of EI that equals the product of total storm energy E times the maximum 30-min intensity，I^30 for a given rainstorm．Usually，the maximum accumulative amount of rain for a rainstorm might bring on the maximum amount of runoff，but it does not equal the maximum erosion and not always lead the maximum concentration．Thus，the average concentration weighted by amount of runoff is somewhat unreasonable．An improvement for the calculation method of non-point source pollution load put forward by professor Li Huaien is proposed．In replacement of the weight of runoff，E1 value of a single rainstorm is introduced as a new weight．An example of Fujing Rive rwatershed shows that its application is effective．     

悬索桥的竖向振动分析与锚索弹性变形的影响

本文对单跨加劲式悬索桥竖向振动进行了分析。在Галёркин法的基础上导出了一种便于计算的简化计算方法。本文还分析了锚索弹性变形对悬索桥振动特性的影响。     

CREATE TRANSGENIC RABBITS BY MICROINJECTING HUMAN apoA-Ⅱ GENE INTO FERTILIZED EGGS

Objective To create transgenic rabbits by microinjecting human apolipoprotein A-Ⅱ (apoA-Ⅱ) geneinto one-cell embryos, to study apoA-Ⅱ gene function on plasma lipoprotein metabolism and atherosclerosis. Methods Superovulation and synchronization of estrus were induced in female Japanese White Rabbits by injecting hormone,then mating with male. After collected the fertilized eggs, the human apoA-Ⅱ gene was microinjected into the male pronucleus of eggs. The injected eggs were transferred into recipient female rabbits. Last, extract DNA from the new borns ear and determine whether the newborns were transgenic by polymerase chain reaction (PCR) or Southern blot analysis. Results A total of 822 embryos with microinjection of human apoA-Ⅱ gene were implanted into 28 recipient rabbits. The number of surviving newborns was 37. 3 transgenic positive surviving founders were found with humanapoA-Ⅱ.     

壳单元的“自锁”问题

本文以杂交／混事有限元为基础,讨论了壳单元“自锁”现象,论论了避免“自锁”的条件;指出与弯曲应力参数相耦合的膜应力参数和横剪应力参数对“自锁”现象不起任何作用。本文的结论可以推广到其他多变量有限元模型中。