Merging bus routes in Hong Kong’s central business district: Analysis and models

A significant portion of the 200,000 people working in Hong Kong’s central business district (CBD) relies on buses as their primary means of transport. During peak hours, nearly a thousand double-decker buses pour into a tiny area of 150 ha. This causes traffic congestion and air pollution. Moreover, given that the flow is uni-directional (into the CBD in the morning and out of the CBD in the afternoon), the occupancy of buses in the CBD is actually low.In this paper, we propose to reduce traffic congestion and to increase bus occupancy by merging bus routes. We describe the peculiar situation of the CBD in Hong Kong and explain the necessary conditions for the possible success of merging routes. Our analysis shows that merging will lead to an overall benefit for all parties, including government, bus operators, and passengers. The actual merging decisions, which routes to merge and at what frequencies buses should run, are determined by a mathematical model. The model also shows quantitatively the benefits of merging routes and the impacts of other factors. The procedure that we follow and the model that we adopt can be applied to other CBD.     

Automotive Steering Control in a Split-µ Manoeuvre Using an Observer-Based Sliding Mode Controller

Summary In this paper a sliding mode integral action controller and sliding mode observer are used to enhance vehicle stability in a split- µ manoeuvre. Anti-lock braking systems (ABS) have become an integral part of modern cars, and they have dramatically improved vehicle handling in braking manoeuvres. However, when a vehicle attempts to brake on a surface with uneven friction coefficient such as on wet or icy roads, a so-called split- µ scenario, the yaw moment generated by the asymmetric braking can prove demanding for an inexperienced driver. The controller presented hereworks in conjunction with a conventional ABS system to provide safe and effective braking through steer-by-wire. This paper extends previous state-feedback work by only using certain measurable quantities in the controller, estimating further signals by employing an observer.     

A capacity related reliability for transportation networks

A capacity related reliability for transportation networks with random link capacity is introduced. It is defined as the probability that the road network can accommodate a certain level of traffic demand, and is built on the concept of network reserve capacity. Network reserve capacity is defined as the largest multiplier applied to an existing origin-destination demand matrix that can be allocated to a transportation network in a user-optimal way without violating the link capacities. Due to large variability associated with link capacities, a probabilistic approach is adopted to model the different physical and operational factors that often degrade the capacity of roadways. A Monte Carlo simulation procedure is developed to estimate the capacity related reliability measure. Numerical results are provided to demonstrate the feasibility of the approach.     

基于GPS和虚拟卫星的列车完整性检查方法研究

将GPS和列尾装置结合可以构成一个冗余的列车完整性检查系统。在列车行驶过程中,由于在列车尾部车钩安装的GPS天线容易被车厢遮挡,常规卫星定位方法受到限制,无法利用GPS进行列车完整性检查。本文提出一种基于GPS和虚拟卫星组合定位完成列车完整性检查的方法。利用列车首部的定位信息确定一颗虚拟卫星,虚拟卫星和3颗可视卫星即可实现列尾定位解算,通过列车首部和列车尾部的位置信息实时地测算车长变化,达到检查列车完整性的目的。本文分析GPS和虚拟卫星组合定位模型,推导定位模型算法和列车完整性检查算法,并进行可行性分析和算法验证。实验表明,列尾定位精度达到3m以内,列车长度误差在10m以内,该方法可满足列车完整性检查的要求。     

对等网络视频点播系统服务器流量模型

在流媒体服务研究领域,服务器流量是衡量系统性能的主要指标。P2PVoD系统中,用户作为视频资源的使用者和提供者,其行为模式对服务器流量产生较大影响。这一特点是以往其他流媒体系统所不具备的,而现有文献又缺乏对以上特点的研究分析及建模。本文以P2PVoD系统的实用网络测量数据为基础,研究用户行为模式与服务器流量的关系,建立用户行为的"时间性模式"模型,并由此推导出服务器流量与频道流行度及资源分布的关系模型,继而通过实测数据验证模型的合理性。最终确立了测评P2PVoD系统性能的模型,即服务器流量、用户规模(系统日用户数)、频道容量(系统总频道数)间的关系模型。此研究对于改善、提高P2PVoD系统性能具有理论和应用价值。     

铁路职业卫生信息系统构建及应用研究

目的为便于铁路职业卫生信息化管理,通过构建铁路卫生防疫管理系统职业卫生子系统,满足铁路卫生主管部门及用人单位的日常使用。方法采用B/S构架,后台采用Oracle关系型数据库,前段应用程序采用asp编程,将基层站段报告数据集成到铁道部内网服务器上,构建铁路职业卫生报告、监控网络。结果系统对各单位职业卫生信息进行技术审核和行政审核,可上报、分析、浏览、查询,形成统计报表,并具备查询某一时间、某一单位或管辖区内职业卫生相关的任一信息,为铁路卫生主管部门及时提供职业卫生信息。结论铁路职业卫生信息系统能及时掌握铁路职业卫生信息,有助于铁路职业病的预防、职业危害作业点的技术改造、接触职业病危害人员的保护,以及促进铁路职业卫生管理水平提高的作用。     

罕遇地震下城际铁路连续梁桥延性抗震设计

研究目的:罕遇地震作用下,城际铁路桥梁结构可能进入到弹塑性工作状态,对城际铁路桥梁结构进行弹塑性地震响应分析和延性抗震设计具有重要的工程价值和研究意义。结合大连市金州新区至普湾新区城际铁路工程的设计实例,基于纤维梁柱单元模型的基本原理,建立主桥(25+30+25)m预应力混凝土连续箱梁桥的弹塑性分析模型,采用傅里叶变换和反复迭代法将铁路规范反应谱拟合为地震动时程曲线,进行罕遇地震下桥梁的地震响应分析及桥墩延性抗震设计。研究结论:结果表明:地震激励下,仅制动墩进入到塑性状态,延性系数最大值为3.02,小于规范给定值4.8,抗震验算满足规范要求。本文给出的桥梁弹塑性分析方法和延性抗震设计结果为城际铁路连续梁桥的延性抗震设计提供了一种实用手段和依据。     

德法市郊铁路运营管理特点分析

以柏林、巴黎、法兰克福和慕尼黑4个城市的市郊铁路作为研究对象,概况介绍其运营里程长、运量大的总体特点和运营政策。着眼于线网布局和运输组织2个方面,通过各类成熟运营的实例,对线路布局、配套设施、列车运行网络、列车种类细分、开行时刻规律等具体做法进行深入分析和总结归纳。通过研究发现,德、法市郊铁路的规划设计与运营需求匹配良好,设备安全可靠,运输组织能最大限度地接近于客流分布,形成较完整、高效、灵活的市郊运输产品,对我国市郊铁路的发展具有一定的借鉴意义。     

地铁设备系统委外维护的风险与对策

基于天津地铁设备系统委外维护的现状,分析当前较流行的委外维护管理中存在的风险与对策。对天津地铁自我维护与委外维护的成本进行分析,阐明开展委外维护的必要性;通过综合分析天津地铁委外管理中存在的各种风险,对维护模式进行定位;根据定位实施相应的策略,为天津地铁委外风险管理乃至城市轨道交通行业设备委外维护风险控制提供参考。     

列控车载设备自动测试系统的设计及实现

针对列控车载设备的检测维修保障的迫切需求,基于VXI总线技术设计列控车载设备自动测试系统的结构及软硬件,集成多种仪器仪表,整合实验室测试设备,建立一个自动测试软件开发平台,完成对多类型被测对象的测试、分析与诊断,实现车载设备板卡自动化功能、性能和集成测试。