Assessment of energy-saving techniques in direct-current-electrified mass transit systems

Railway rapid transit systems are key stones for the sustainability of mass transit in developed countries. The overwhelming majority of these railway systems are direct-current (DC) electrified and several energy-saving techniques have been proposed in the literature for these systems. The use of regenerative-braking in trains is generally recognised as the main tool to improve the efficiency of DC-electrified mass transit railway systems but the energy recovered in braking cannot always be handled efficiently, above all in low traffic-density situations. Several emerging technologies as energy storage systems or reversible traction substations have the potential for making it possible to efficiently use train-braking. However, a systematic evaluation of their effect is missing in the literature.In this paper, a deep, rigorous and comprehensive study on the factors which affect energy issues in a DC-electrified mass transit railway system is carried out. This study clarifies what the actual potential is for energy saving in each situation. Then, a methodology to asses several energy-saving techniques to improve energy efficiency in DC-electrified mass transit systems is presented, constituting the main contribution of this paper. This methodology has been conceived to help operators in assessing the effect of railway-infrastructure emerging technologies in transit systems, so making it possible to shape planning, capacity, etc. It is stepped out in three basic movements. First of all, a traffic-density scan analysis is conducted in order to clarify the effect of the headway on system behaviour. Secondly, several traffic-density scenarios are simulated for a set of infrastructure-expanded cases. Finally, annual energy saving is evaluated by applying a realistic operation timetable. This methodology has been applied to a case study in Madrid Metro (Spain) to illustrate the steps of its application and the effect of several energy-saving techniques on this specific system. Results confirm that regenerative braking generally leads to an important increase of system energy efficiency – especially at high traffic-density scenarios. It has also been proved that infrastructure improvements can also contribute to energy savings and their contributions are more significant at low traffic densities. Annual energy results have been obtained, which may lead to investment decisions by carrying out an appropriate economic assessment based on cost analysis.The main results of the study presented here are likely to apply to other electric traction systems, at least qualitatively.     

新型混合型限流熔断器在舰船综合电力系统中的应用分析

采用中压直流电网输配电是舰船综合电力系统的重点发展方向,但中压直流开关的分断能力不足成为中压直流电网发展的一个重要制约.本文提出在合理位置加装电弧触发式混合型限流熔断器（ATH-CLF）来限制中压直流电网短路电流的方法来解决这一问题.首先以IEEE Std 1709-2010推荐的一种舰船中压直流电网为例,建立了该电网的EMTP仿真模型和ATH-CLF的EMTP仿真模型,计算了有无ATH-CLF以及ATH-CLF安装在不同位置时各典型位置发生短路的电网短路电流及母线电压跌落.分析表明,合理的ATH-CLF加装方案可有效降低短路电流水平,并可使非故障区域的母线电压跌落在10 ms之内恢复.     

城市道路联网联控关键技术

从城市道路联网联控平台的系统构建出发,概述其系统构架的关键层次为交通信息感知层、模型层、应用层及信息发布层。阐述城市道路联网联控的关键技术,主要包括交通信息感知、道路运行状态分析、交通需求识别、交通信号控制和交通诱导。最后,讨论城市道路联网联控技术带来的社会效益。     

在资金预算不确定条件下路面维护和修复项目管理决策优化方法

一个得到良好开发和维护的路面管理系统（PMS）能够帮助管理者做出在什么时候,对哪些路段采用什么样的路面维护和修复方案的决定,从而实现可用资源的最大化.本文提出一种在资金预算不确定条件下路面维护和修复项目管理决策优化方法 (MPMRPBU),为确保管理者在一个决策规划时段内,从公路网中选择并优化一组路面维护和修复方案,建立随机线性规划模型求解MPMRPBU问题.通过案例分析,比较在确定性优化和随机规划两种不同条件下的优化方案,研究不同经济预算对优化方案的影响.结果表明,采用随机规划方法能产生高质量的MPMRPBU解决方案, 该算法可以解决实际问题.     

A novel approach to design robust fault detection filter for networked control systems

In this paper, an approach for designing robust fault detection filter (RFDF) of networked control systems (NCSs) with unknown inputs is studied. The design aims at implementing the optimal trade-off between robustness of unknown inputs (including the item produced by networked-induced delay) and sensitivity of fault. The key design issue is to introduce an optimal fault detection filter based on NCSs with the control law compensation as the reference residual model of NCSs and to formulate the RFDF design as a model-matching problem. By applying H _∞ optimization technique, linear matrix inequality (LMI) approach is given to solve the model-matching problem. The validity of the proposed approach is shown by a numerical example.      

D-B总承包模式的评标方法分析

近年来,D-B（设计-建设）总承包模式已被越来越多的业主所采用。对业主来讲,选择最有价值的总承包商（商务合理、技术先进、管理科学）是最重要的。通过对D-B总承包模式概念和优点的分析,提出D-B总承包模式的评标模型,并运用该模型综合评出最有价值的总承包商。     

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作为智能交通系统的一部分,在电子信息版显示的电子交通标识,由于能够为驾驶员提供清晰、准确且易于辨识的交通信息,在世界各地得到了日益广泛的应用。本文对韩国首尔市动态交通控制系统中的电子交通标识进行评价和设计。对之前研究中设计的部分标识改进,并在实际某路段的可变信息板显示试验。此外,通过部分驾驶员对这些交通标识的辨识进行分析,对不同方案进行评价,为确定最终的标识提供参考。结果表明,现有欧洲设计和韩国设计的表示交通事故的标志辨识正确率较低（分别为10%和43.5%）;表示拥堵和交通事件的标志辨识正确率在45%至55%间;欧洲设计的雪天警告标志的辨识正确率为17.5%,韩国设计的雪天警告标志相对易于辨识（正确率75.5%）。     

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应用视频处理技术对行人交通进行研究和分析受到广泛的重视和发展,已成为智能交通领域的研究热点之一,而行人跟踪是行人交通采集系统的基础,是后续交通参数提取,行为分析的前提.本文提出一种基于Kalman滤波的行人跟踪方法.首先,利用改进的混合高斯模型提取背景,并采用HSV颜色空间模型和目标重构方法得到消除阴影后的前景图像.其次,进行行人的特征提取,得到融合行人位置特征和形状特征的运动模板.最后,采用Kalman滤波对行人的运动轨迹进行预测,将检测到的目标与预测结果匹配,得到行人的跟踪匹配矩阵,根据匹配矩阵判断合并和分离的发生.试验结果表明,该方法不仅可以准确跟踪多目标,而且可以有效解决遮挡问题,具有很好的适应性和鲁棒性.     

私家车出行者ATIS信息选择影响因素研究——以大连市为例

私家车出行者对ATIS信息的选择意愿受到多种因素的影响。开展大连市私家车出行者ATIS信息需求意向调查,以探索性因子分析和累积Logit模型理论为基础,对ATIS信息内容进行分类,同时引入出行者性别、年龄、收入水平、交通补助情况等特性变量,建立私家车出行者ATIS信息选择模型。模型标定结果显示,私家车出行者个人特征与ATIS信息特性对ATIS信息选择意愿存在不同程度的影响：私家车出行者主要关注与出行质量相关的信息,收入水平、交通补助、驾照保有情况等对私家车出行者ATIS信息选择意愿影响显著。