地铁不同场段分布对其规模分配和运营成本的影响

城市轨道交通的车辆段和停车场需要占用大量的城市土地,合理分配场段规模可以优化占地面积,提高运营效率。基于一场一段情况下,总结出不同接轨方案的场段规模分配计算方法,提出场段分布位置在线路中接近对称时,场段规模大致相等的研究结论。同时,提出地铁收发车空跑距离计算模型,并对不同场段分布对运营成本的影响因素进行分析,提出降低运营期间场段收发车空跑运营成本的途径。     

东新高速沙湾特大桥总体设计

沙湾特大桥主桥为177.5m+248m+117.5m的部分斜拉桥,桥宽达34.0m,无论跨度、桥宽及荷载均处于国内外同类型桥梁的前列,介绍了本桥的工程概况、技术标准及结构特点,为今后我国类似桥梁设计提供了借鉴和参考。     

自锚悬索桥异型主塔悬臂模板施工技术

南京长江隧道工程江心洲右汉大桥设计为独塔自锚式悬索桥，其主塔截面外轮廓是由多段凹圆弧、凸圆弧及过渡小圆弧围成的变截面，截面圆弧随着高度变化其自身曲率连续不规则变化。通过对异型截面主塔的施工实践，着重阐述悬臂模板对异型截面主塔施工的适用性及其施工工艺和控制措施。     

Bicriterion shortest path problem with a general nonadditive cost

A bicriterion shortest path problem with a general nonadditive cost seeks to optimize a combination of two path costs, one of which is evaluated by a nonlinear function. This paper first identifies a number of emerging transportation applications for which such a shortest path problem might be considered a core subproblem. We propose to first approximate the general nonlinear cost function with a piecewise linear counterpart, and then solve each linear subproblem sequentially. A specialized algorithm is developed to solve the subproblems, which makes use of the efficient path set (or the convex hull) to update upper and lower bounds of the original problem. Conditions under which the solution to a subproblem must belong to the efficient path set are specified. Accordingly, we show that the optimal path must be efficient if the nonlinear cost function is concave. If the optimal path to a subproblem is not efficient, partial path enumeration, implemented using a simple K-shortest path ranking procedure, is conducted to close the gap. The proposed algorithm includes strategies aiming to expedite path enumeration by using upper bounds derived from the efficient path set. Numerical experiments are conducted to demonstrate correctness and effectiveness of the proposed algorithm.     

The impact of a new rapid transit system on traffic on parallel highway facilities

This study analyzes data of traffic crossing San Francisco Bay and passing through the Berkeley Hills via Caldecott Tunnel to determine the effect of the opening in 1974 of the Bay Area Rapid Transit System (BART) transbay line. There was a sudden shift in trend lines in 1974; vehicle volumes dropped, transit patronage jumped, but total person trips in the short run followed roughly the trends of the previous eight years. Since 1974, the growth rate in person trips through the Berkeley Hills appears to have remained about the same, while transbay vehicle and transit traffic have increased at a more rapid rate. The increase in transit patronage is particularly noticeable between the morning and afternoon peaks and probably represents new trips by shoppers and sightseers. Whereas other factors, such as the increase in the price of gasoline between October 1973 and July 1974 may have contributed a little to the sudden change in the long‐range trends in 1974, it is believed that the major cause was the opening of the BART network to transbay travel.

     

What are the value and implications of two-car households for the electric car?

The major barriers to a more widespread introduction of battery electric vehicles (BEVs) beyond early adopters are the limited range, charging limitations, and costly batteries. An important question is therefore where these effects can be most effectively mitigated. An optimization model is developed to estimate the potential for BEVs to replace one of the conventional cars in two-car households and to viably contribute to the households’ driving demand. It uses data from 1 to 3 months of simultaneous GPS logging of the movement patterns for both cars in 64 commuting Swedish two-car households in the Gothenburg region.The results show that, for home charging only, a flexible vehicle use strategy can considerably increase BEV driving and nearly eliminate the unfulfilled driving in the household due to the range and charging limitations with a small battery. The present value of this flexibility is estimated to be on average $6000–$7000 but varies considerably between households. With possible near-future prices for BEVs based on mass production cost estimates, this flexibility makes the total cost of ownership (TCO) for a BEV advantageous in almost all the investigated households compared to a conventional vehicle or a hybrid electric vehicle. Because of the ubiquity of multi-car households in developed economies, these families could be ideal candidates for the initial efforts to enhance BEV adoptions beyond the early adopters. The results of this research can inform the design and marketing of cheaper BEVs with small but enough range and contribute to increased knowledge and awareness of the suitability of BEVs in such households.     

改进型EDF算法在计算机联锁全电子执行单元中的应用研究

针对计算机联锁全电子执行单元的安全性、可靠性、大数据量传输的要求,结合CAN总线的特点,提出一种基于指数分区的EDF动态调度算法,以此来提高CAN总线的实时性以及全电子执行单元发送消息的成功率。对改进后的EDF算法的编码进行详细的描述,通过使用量化误差的概念,推导任务的可调度性公式,以此来衡量算法的优化程度。使用Matlab中的truetime工具箱和全电子执行单元的通信数据,对该算法进行仿真实验,并与平均分区的EDF算法进行比较。仿真结果表明:本文算法能够平衡高低优先级的关系;发送消息的成功率更高。改进后的调度算法能够实现消息的动态调度,良好地解决了计算机联锁全电子执行单元中CAN总线网络资源不足时任务不可调度的问题。     

节拍生产在轨道交通制造业中的实践

通过轨道交通制造业导入节拍生产的实践,对节拍生产从定义到生产线设置方法进行了阐述,并通过举例对传统生产线和节拍生产线在生产效率、设备投资、物流设置、质量管理和人员管理等方面做了深入的分析。说明了节拍生产在成本改善方面的优势、相关应用和注意事项。     

现代房地产及建筑工程目标成本管理浅析

目标成本管理是现代房地产及建筑工程的重要管理工具,是企业的核心战略之一。通过系统的分析总结,研究如何建立企业的目标成本管理体系,并确保成本目标在项目管理的前、中、后期全面受控;结合成本管理的专业特点及当前企业管控情况,总结目标成本建立的方法;论证了目标成本要做到受控,必须设置科学合理的目标成本系统;最终目标成本管理必须全面运用到现代企业的生产管理之中,对外能大幅提升企业的市场竞争力,对内也能促进企业的生产管理水平提升,为企业经营提供良好的运营保证。     

运营公路隧道结构预防性养护经济性评价方法探讨

目前预防性养护思想在运营公路隧道养护领域的研究与应用处于起步阶段。为将预防性养护思想运用于运营隧道养护工作中，借鉴路面预防性养护的成熟理念，结合隧道养护工作的实际情况，对运营公路隧道预防性养护技术进行了分析及定义，并引入效益－费用分析法对隧道预防性养护的经济性进行了分析，提出了可行的评价指标和评价方法。运营公路隧道预防性养护的经济性主要包括对隧道养护费用和效益的界定与计量，其中养护费用包括直接成本和间接成本2大类，效益包括直接效益和间接效益2大类，并给出了隧道预防性养护各类成本及效益的计算方法。根据工程经济学提出了可选用的隧道预防性养护方案的经济评价指标，包括净现值（NPV）、费用年值（AC）、效益－费用比（RB/C）、净现值率（NPVR），供隧道养护方案决策参考。