后张法预应力钢绞线张拉伸长值的计算

桥梁预应力施工时,采用张拉应力和伸长值双控,实际伸长值与理论伸长值误差不得超过6%,所以伸长值的计算就相当重要,结合实际施工过程,通过对后张法现浇预应力箱梁预应力钢绞线张拉伸长值的计算,总结出一套较适用于现场施工的伸长值的计算法。     

机车车辆／轨道系统垂向耦合动力学分析

考虑到多刚体系统动力学研究方法在建模及计算方面的局限性，将有限元法引入到机车车辆／轨道大系统的垂向耦合振动研究中来．为了真实模拟在轨道上不同位置的轮轨接触关系，用有限元参数二次规划法求出了轮轨等效接触刚度曲线，建立了统一的机车车辆／轨道耦合系统．通过建立系统的有限元分析模型，利用精细时程积分算法求解系统振动方程，分析研究了机车车辆在无限长轨道上运行时，在轨道不平顺激扰下，轮／轨间相互作用力、机车车辆／轨道系统中各部件的振动加速度及位移变化规律．研究结果表明，该方法不但可行，而且具有其它传统方法无可比拟的优越性．     

Highway alignment optimization through feasible gates

An efficient optimization approach, called feasible gate (FG), is developed to enhance the computation efficiency and solution quality of the previously developed highway alignment optimization (HAO) model. This approach seeks to realistically represent various user preferences and environmentally sensitive areas and consider them along with geometric design constraints in the optimization process. This is done by avoiding the generation of infeasible solutions that violate various constraints and thus focusing the search on the feasible solutions. The proposed method is simple, but improves significantly the model's computation time and solution quality. Such improvements are demonstrated with two test examples from a real road project.     

刚构桥中的高墩计算研究

本文提出了刚构桥中高墩不仅要对单墩进行强度、稳定分析,还要对全桥整体稳定进行分析,并对高墩设计给出了比较完整的、清晰的、方便的计算方法和步骤,供同行参考和借鉴。     

Improving the efficiency of repeated dynamic network loading through marginal simulation

Currently, the applicability of macroscopic Dynamic Network Loading (DNL) models for large-scale problems such as network-wide traffic management, reliability and vulnerability studies, network design, traffic flow optimization and dynamic origin–destination (OD) estimation is computationally problematic. The main reason is that these applications require a large number of DNL runs to be performed. Marginal DNL simulation, introduced in this paper, exploits the fact that the successive simulations often exhibit a large overlap. Through marginal simulation, repeated DNL simulations can be performed much faster by approximating each simulation as a variation to a base scenario. Thus, repetition of identical calculations is largely avoided. The marginal DNL algorithm that is presented, the Marginal Computation (MaC) algorithm, is based on first order kinematic wave theory. Hence, it realistically captures congestion dynamics. MaC can simulate both demand and supply variations, making it useful for a wide range of DNL applications. Case studies on different types of networks are presented to illustrate its performance.     

电涡流缓速器制动力矩的计算方法

运用电磁场理论推导了电涡流缓速器的电流密度和制动力矩计算公式，这些计算公式反映了电涡流缓速器各设计参数的相互关系．可用于指导电涡流缓速器的产品开发。     

轨道不平顺分析程序

轨道不平顺是引起车体振动加速度、轮轨作用力和轮轨噪声增大的主要因素之一。车体振动加速度的大小与轨道不平顺具有密切的关系。随着列车速度的提高,对车辆振动影响的轨道不平顺不利波长也随之增长。轮轨噪声中的滚动噪声与轨面短波连续不平顺具有密切关系。轨道不平顺分析程序对轨检车测得的轨道不平顺数据进行处理,得到功率谱密度分布函数。利用此分布函数分析轨道不平顺在各波长的分布;根据测得的车体振动加速度,对轨道不平顺与车体振动加速度进行相干分析,确定引起车辆振动加速度增大的不利波长,以便有针对性地对这些波长的轨道不平顺作重点养护。