基于可控性分类的航班延误问题应对策略建议

本文从航班延误的主要原因入手,对航班延误问题进行可控性分类,提出了应对延误问题的两种思路及其适用阶段,针对不同可控类型的航班延误问题,从风险管理的角度分别提出不同的应对策略与措施建议。     

新型城镇化建设与机场网络化发展:中小机场的战略价值

新型城镇化是我国实现现代化的战略选择,构建沿"两横三纵"聚集的新型城市网络集群是我国城镇化发展的战略布局目标。本文提出了新型城镇化需要构建结构合理的网络化综合机场体系的重要观点,指出了中小机场建设对于新型城镇化建设与机场网络化发展的战略价值。通过分析我国现有机场体系与新型城镇化发展目标及其发展历程的适应程度,提出在新型城镇化发展战略中,我国机场建设的重点方向是,在功能及布局结构优化的基础上增加机场数量,特别是增加城市群内中小机场的数量。阐述了国家扶持中小机场发展对于构建东部世界级城市群、培育西部地区性城市群的重要性。     

Optimal speed detector density for the network with travel time information

In the expressway network, detectors are installed on the links for detecting the travel time information while the predicted travel time can be provided by the route guidance system (RGS). The speed detector density can be determined to influence flow distributions in such a way that the precision of the travel time information and the social cost of the speed detectors are optimized, provided that each driver chooses the minimum perceived travel time path in response to the predicted travel time information. In this paper, a bilevel programming model is proposed for the network with travel time information provided by the RGS. The lower-level problem is a probit-based traffic assignment model, while the upper-level problem is to determine the speed detector density that minimizes the measured travel time error variance as well as the social cost of the speed detectors. The sensitivity analysis based algorithm is proposed for the bilevel programming problem. Numerical examples are provided to illustrate the applications of the proposed model and of the solution algorithm.     

A Heuristic Algorithm for the Allocation of Airport Runway System Capacity

Abstract

This paper develops a heuristic algorithm for the allocation of airport runway capacity to minimise the cost of arrival and departure aircraft/flight delays. The algorithm is developed as a potential alternative to optimisation models based on linear and integer programming. The algorithm is based on heuristic (‘greedy’) criteria that closely reflect the ‘rules of thumb’ used by air traffic controllers. Using inputs such as arrival and departure demand, airport runway system capacity envelopes and cost of aircraft/flight delays, the main output minimises the cost of arrival and departure delays as well as the corresponding interdependent airport runway system arrival and departure capacity allocation. The algorithm is applied to traffic scenarios at three busy US airports. The results are used to validate the performance of the proposed heuristic algorithm against results from selected benchmarking optimisation models.     

三峡工程泄洪深孔弧门液压启闭机管道安装工艺

详细介绍了三峡工程泄洪深孔弧门液压启闭机系统管道安装工艺 ,并对管道焊接工艺进行了具体阐述。特别是针对施工现场的特定环境改变传统的管道安装顺序 ,采取先装泵房及管道 ,后装油缸的工艺 ;对系统管道采取了一次串接注油、分次试压及线性循环冲洗与在线检测的新工艺。实践表明 :该工艺在工程中取得较好的应用效果 ,为深孔孤门液压启闭机系统按期调试奠定了坚实的基础。     

Optimal distance- and time-dependent area-based pricing with the Network Fundamental Diagram

Given the efficiency and equity concerns of a cordon toll, this paper proposes a few alternative distance-dependent area-based pricing models for a large-scale dynamic traffic network. We use the Network Fundamental Diagram (NFD) to monitor the network traffic state over time and consider different trip lengths in the toll calculation. The first model is a distance toll that is linearly related to the distance traveled within the cordon. The second model is an improved joint distance and time toll (JDTT) whereby users are charged jointly in proportion to the distance traveled and time spent within the cordon. The third model is a further improved joint distance and delay toll (JDDT) which replaces the time toll in the JDTT with a delay toll component. To solve the optimal toll level problem, we develop a simulation-based optimization (SBO) framework. Specifically, we propose a simultaneous approach and a sequential approach, respectively, based on the proportional-integral (PI) feedback controller to iteratively adjust the JDTT and JDDT, and use a calibrated large-scale simulation-based dynamic traffic assignment (DTA) model of Melbourne, Australia to evaluate the network performance under different pricing scenarios. While the framework is developed for static pricing, we show that it can be easily extended to solve time-dependent pricing by using multiple PI controllers. Results show that although the distance toll keeps the network from entering the congested regime of the NFD, it naturally drives users into the shortest paths within the cordon resulting in an uneven distribution of congestion. This is reflected by a large clockwise hysteresis loop in the NFD. In contrast, both the JDTT and JDDT reduce the size of the hysteresis loop while achieving the same control objective. We further conduct multiple simulation runs with different random seed numbers to demonstrate the effectiveness of different pricing models against simulation stochasticity. However, we postulate that the feedback control is not applicable with guaranteed convergence if the periphery of the cordon area becomes highly congested or gridlocked.     

Optimal land use and transport planning for the Greater Oslo area

The aim of this paper is to describe and apply a comprehensive framework to derive optimal and acceptable land use and transport strategies. The framework includes a constrained optimisation algorithm that approximates and maximises an objective function with respect to available land use and transport instruments and constraints. We apply the framework to Greater Oslo based on output from a land use and transport model for this area (RETRO). Available instruments are toll ring charges, public transport frequency and a discrete land use instrument. Constraints represent acceptable levels on the available instruments, and acceptable levels on equity between geographical zones, accident cost reductions and the financial balance of the actual strategy. Strategies are found in situations with increased and reduced fuel taxes, and the direct and indirect land use and transport effects of the optimal strategies are assessed.     

企业道路运输车辆卫星定位系统评价方法研究

自2010年交通运输部组织开展道路运输动态监控系统建设以来,道路运输动态监控系统在道路运输安全管理中发挥了越来越重要的作用,目前已建成覆盖全国31个省市四级架构的全国重点营运车辆联网联控系统.目前对各运输企业在系统使用效果方面缺少完善公正的评价方法.本文重点研究了企业道路运输车辆卫星定位系统评价方法,从评价内容、评价指标、指标权重等方面建立了企业道路运输车辆卫星定位系统评价方法.     

双层保温层经济厚度的优化计算

通过对双层保温的总费用分析，并考虑到保温的国家标准和工程实际，建立了双层保温层经济厚度优化设计的数学模型，并采用最优化方法进行了编程求解，得到了每层的最佳经济厚度。导出的模型和编制的软件可帮助设计人员合理地选择保温材料并确定其经济厚度，有助于提高设计效率和设计质量。