Finite element calculations of rail vibration countermeasures

Elastic waves may constitute a nuisance for people living close to high-speed lines. In order to decrease the spread of vibrations, it is common to reinforce the ground with lime cement columns. This article presents the results of simulations of three different ways to install the columns. The calculations have been done with an integrated rigid body—finite element model. Equations from various physical domains are merged into one big system. The results indicate that the straight configuration works best to protect the track. When attention is focused on preventing vibrations from the soil, the leaning column method is more effective. The chosen technique would depend on the aims of the countermeasure.     

关于构建大城市中央商务区综合交通体系的探讨

中央商务区是一个城市的核心区,同时也是城市交通高度集中的区域。如何构建一个高效的综合交通系统,有效地解决中央商务区的交通问题,一直是各大城市关注的重点问题。文中以广州珠江新城为例,探讨如何构建一个高效的综合交通体系,为解决CBD的交通问题提供参考和借鉴。     

波形钢腹板组合箱梁加载效率试验研究

体外预应力波形钢腹板组合箱梁是一种新型的钢-混凝土组合结构,其剪力主要由钢腹板承担,混凝土顶底板承受绝大部分弯矩;由于充分发挥了材料性能,提高了材料效率,有着很好的应用前景。为了研究波形钢腹板的加载效率,制作了2根模型梁,通过测试预应力张拉时结构应变和变形规律,利用空间有限元方法进行分析,试验结果与理论结果吻合较好,并得到了该组合结构在预应力作用下的加载效率规律。对不同厚度腹板的普通混凝土梁进行了参数对比分析,结果表明,波形钢腹板组合箱梁在预应力加载效率方面具有较强的优势。     

海上平台管道施工效率研究

一个工程项目的开展需充分考虑其运作的成本，在施工方面，提高施工效率是降低工程成本的一个重要方面。在海洋石油平台上进行管线施工作业，条件艰苦且风险较大，降低风险也是节约成本的重要方法。提出了提高海上平台管线施工的工作效率，减少施工时间措施。阐明从设计方法、建造施工方法两方面提高施工效率。     

模糊AHP法及其在电子战系统效能评估中的应用

电子战系统的效能评估是基于系统单项效能评估的基础之上的。本文的分析方法是在分析单项效能指标的基础上,应用模糊层次分析法（FAHP）对多个电子战系统进行综合评估。首先构造区间数判断矩阵,然后运用区间数特征向量法（IEM）求取权重向量,最后求出层次的组合区间权及排序指数,得出最佳方案。     

调度指挥的革命信息化建设的硕果——郑州局调度指挥工作信息化

介绍了郑州铁路局调度管理信息系统的建设与应用.该系统的应用改变了多年来运输调度的人工作业模式,提高了运输生产效率和管理工作质量,减轻了调度员的劳动强度,实现了运输调度指挥工作的一次革命.深受调度人员和领导的欢迎与好评.     

公路施工企业降低生产成本提高经济效益的对策

文章分析公路施工企业生产成本高利润率低的现状及成因,针对当前的市场环境,提出公路施工企业降低生产成本,提高经济效益的六大对策,论证提高企业管理能力和核心竞争力是改变现状的根本办法。     

An integrated framework for assessing service efficiency and stability of rail transit systems

A well-designed service plan efficiently utilizes its infrastructure and ensures an acceptable level of service stability with consideration of potential incidents that disturb or disrupt the rail transit services. To perform service evaluation, an integrated process combining capacity, resource usage, and system reliability is required to quantify service efficiency and stability in a consistent way. This study adopts capacity-based indices, “capacity utilization” and “expected recovery time”, as the attributes for service efficiency and stability, and develops a comprehensive evaluation framework with three corresponding modules to incorporate capacity, service plan, and system reliability and maintainability simultaneously. The capacity analysis module computes the rail transit capacities under normal and degraded operations. The reliability module classifies and fits the proper reliability and maintainability distributions to the historical interruption data. The service efficiency and stability module analyzes the results of the previous two modules and evaluates the service efficiency and stability of rail transit service plans. Empirical results show that the established evaluation framework can not only evaluate the service efficiency and stability but also identify critical sections and time slots. This tool can help rail transit operators rapidly assess their operational changes and investment strategies related to efficiency and stability so as to provide efficient and stable services to their customers.     

Field implementation feasibility study of cumulative travel‐time responsive (CTR) traffic signal control algorithm

The cumulative travel‐time responsive (CTR) algorithm determines optimal green split for the next time interval by identifying the maximum cumulative travel time (CTT) estimated under the connected vehicle environment. This paper enhanced the CTR algorithm and evaluated its performance to verify a feasibility of field implementation in a near future. Standard Kalman filter (SKF) and adaptive Kalman filter (AKF) were applied to estimate CTT for each phase in the CTR algorithm. In addition, traffic demand, market penetration rate (MPR), and data availability were considered to evaluate the CTR algorithm's performance. An intersection in the Northern Virginia connected vehicle test bed is selected for a case study and evaluated within vissim and hardware in the loop simulations. As expected, the CTR algorithm's performance depends on MPR because the information collected from connected vehicle is a key enabling factor of the CTR algorithm. However, this paper found that the MPR requirement of the CTR algorithm could be addressed (i) when the data are collected from both connected vehicle and the infrastructure sensors and (ii) when the AKF is adopted. The minimum required MPRs to outperform the actuated traffic signal control were empirically found for each prediction technique (i.e., 30% for the SKF and 20% for the AKF) and data availability. Even without the infrastructure sensors, the CTR algorithm could be implemented at an intersection with high traffic demand and 50–60% MPR. The findings of this study are expected to contribute to the field implementation of the CTR algorithm to improve the traffic network performance. Copyright © 2017 John Wiley & Sons, Ltd.     

Improved driver responses at intersections with red signal countdown timers

Traffic Signal Countdown Timers (TSCTs) are innovative, practical and cost effective technologies with the potential to improve efficiency at signalized intersections. The purpose of these devices is to assist motorists in decision-making at signalized intersections with real-time signal duration information. This study focused specifically on driver responses in the presence of a Red Signal Countdown Timer (RSCT). A Linear Mixed Effect (LME) model was developed to predict the effect of RSCT on the headway of the first vehicle waiting on a red signal. The model predicted 0.72 s reduction in the headway of the first queued vehicle resulting from the presence of RSCT, while the observed difference in mean headway was 0.82 s. This result is suggestive of a reduction in start-up lost time at signalized intersections, i.e., an improvement in signalized intersection efficiency when an RSCT is present.