Study on mean-standard deviation shortest path problem in stochastic and time-dependent networks: A stochastic dominance based approach

This paper studies a mean-standard deviation shortest path model, also called travel time budget (TTB) model. A route’s TTB is defined as this route’s mean travel time plus a travel time margin, which is the route travel time’s standard deviation multiplied with a factor. The TTB model violates the Bellman’s Principle of Optimality (BPO), making it difficult to solve it in any large stochastic and time-dependent network. Moreover, it is found that if path travel time distributions are skewed, the conventional TTB model cannot reflect travelers’ heterogeneous risk-taking behavior in route choice. This paper proposes to use the upper or lower semi-standard deviation to replace the standard deviation in the conventional TTB model (the new models are called derived TTB models), because these derived TTB models can well capture such heterogeneous risk-taking behavior when the path travel time distributions are skewed. More importantly, this paper shows that the optimal solutions of these two derived TTB models must be non-dominated paths under some specific stochastic dominance (SD) rules. These finding opens the door to solve these derived TTB models efficiently in large stochastic and time-dependent networks. Numerical examples are presented to illustrate these findings.     

牵引车和半挂车联合辅助制动设计

针对装有辅助制动装置的牵引车在下坡过程中不能与半挂车协调实现减速和制动常引起冲撞和折叠等不安全的现象,提出了一种可以实现牵引车和半挂车联合辅助制动的设计方案即通过控制器使半挂车预先制动,再按设定的速度实现汽车列车稳速下坡。     

上海港罗泾港区二期工程矿石码头升级改造工程设计概算要点分析

为适应船舶大型化的发展,罗泾矿石码头的靠泊等级急需提升,码头中部分破损结构要进行加固修复.介绍罗泾矿石码头升级改造工程中的设计方案,根据设计方案编制了工程概算.该工程中大量的改造项目在2004年出版的《沿海港口建设工程概算预算编制规定及配套定额》中没有相应的定额,概算编制过程中综合考虑了设计方案和现有的施工技术,为今后类似项目的实施提供了宝贵的基础资料.     

出行时耗预算机理解析

从20世纪60年代开始,一些学者发现城市居民人均日出行时耗在不同年份表现出一定的稳定性;扎·哈维提出日平均出行时耗预算相对恒定假设。首先,通过国内外全日、单次出行平均时耗变化的历史数据,验证了出行时耗的相对稳定性。在解析出行时耗相对恒定形成机理的基础上,重点分析单次通勤出行时耗分布机理,并提出相应的模拟公式。同时,探讨交通拥堵状况对出行时耗分布的影响作用,分析表明较小的出行时耗增加可能隐含较大程度的交通拥堵。最后指出,应结合中国城市居民的出行时耗预算,为其适宜的交通模式规划路网和城市用地布局。     

基于TD-LTE技术的无线链路物理模型构建及其预算方案

为提升培养通信专业人才的综合能力及其社会对无线通信新技术人才的需求,要将TD-LTE技术引入高校无线通信网络实验室建设,必须做好前期的网络链路预算,这是无线通信网络实验室建设的关键,也是核心.它对后续的频率规划、容量规划以及系统组网设计等至关重要.为此,依据网络链路预算原理,在构建链路预算物理模型的基础上,绘制了链路预算软件流程图,引入LTE链路预算参数,设计出LTE链路预算方案,为实现该实验平台建设的目标提供了重要思路,同时,也为算法仿真及系统设计提供研究基础.     

Water resources development in Turkey

The Southeastern Anatolia Projec(tGAP),one of the most important projects for developing remarkable natural resources of the world,is accepted as a change for getting benefit from rich water and agricultural resources of the Southeastern Anatolia Region.The GAP Project has been considered as a regional development projects through years,but the dimensions of sustainability,protection of environment and participatory have been attached to the master of the project in recent years.When the GAP Project is completed,the Upper Mesopotomia, the centers of many civilisation,will re-again its importance as it had in the ancient times,and will be alive a center of civilisation.Moreover,when the problem of water shortage and water supplies in the world for the future is kept in mind,the importance of Southeastern Anatolia′s water supplies will be doubled.For this reason,the GAP Project,developed by depending on water and natural resources of the region,will have an important place in the world.The aim of this study is to introduce the region with rich natural resources and the GAP Project.For this reason,firstly,the natural potential of the region will be introduced.Second,the GAP Project will be presented in details.In the third stage,the projects being processed for protecting the natural sources and environment will be analyzed.In the last stage,strategies and policies to develop and to protect the natural resources of the region in short,mid,and long terms will be proposed.     

新编《铁路信号工程预算定额》概况及分析

对新编《铁路信号工程预算定额》从结构编排、定额内容、施工工艺、费用及其他5个方面做了详细介绍，同时提出使用中应注意定额子目的应用要与工程实际相符、工程量不能重复计列、要掌握设备价的内涵等3个方面问题。此文旨在给读者正确理解和使用“新定额”提供帮助。     

谈通信工程造价的预结算审核

本文介绍了工程造价的预结算审核的内容和主要的审核方法。     

浅议水利工程施工管理

根据水利施工管理的特点,对水利工程施工管理工作进行分析和探讨,重点对管理特征、管理内容进行分析,并提出了水利工程施工管理工作应注意的事项。     

三峡工程设计中的重大技术问题

三峡工程为举世瞩目的水利工程,其工程规模之浩大、技术问题之复杂都是罕见的。该文选择了工程设计中坝址的选定及枢纽建筑物设计中的若干关键技术问题进行介绍和阐述,以期读者对三峡工程有更深入的了解。