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951.
Transport models, philosophy and language 总被引:1,自引:0,他引:1
Paul Timms 《Transportation》2008,35(3):395-410
The aim of this paper is to encourage debate about the nature of transport modelling. It does so firstly by considering the
underlying philosophies of science (apparently) adopted by transport modellers, over a period of more than 50 years, from
the 1950s until the present day. The conclusion is that a new philosophy of science needs to be developed, which is more in
tune with how transport modelling is actually carried out (as opposed to how early transport modellers thought it ought to
be carried out). It is recommended that such a new philosophy perceives transport modelling as a linguistic activity within
the overall context of transport planning, which is in turn considered as a communication process. The paper outlines three
main approaches that could be taken in this respect, analysing transport models from metaphorical, narrative and aesthetic
perspectives. Conclusions are drawn upon the possible future research directions that might follow from the analysis provided
in the paper, emphasising the importance of bringing formal philosophical thinking into transport modelling research and practice.
Paul Timms is a Senior Research Fellow at the Institute for Transport Studies, University of Leeds. He has been involved for 20 years in research covering a wide range of transport modelling (from traffic signals to world futures), applied to various locations in Europe, Asia and Latin America. 相似文献
Paul TimmsEmail: |
Paul Timms is a Senior Research Fellow at the Institute for Transport Studies, University of Leeds. He has been involved for 20 years in research covering a wide range of transport modelling (from traffic signals to world futures), applied to various locations in Europe, Asia and Latin America. 相似文献
952.
浅埋大断面黄土隧道下穿既有铁路施工技术 总被引:6,自引:1,他引:5
在高桥隧道出口下穿南同蒲既有铁路施工中,根据黄土的特性对施工方案进行了优化,将设计的在总长100 m、φ159大管棚超前支护条件下采用双层支护形式的(外层为喷混凝土,内层为模筑混凝土)双侧壁导洞开挖法优化为双层支护形式的(两层均为喷混凝土)弧形导洞三台阶七步开挖法,并通过仰拱和二次衬砌紧跟的方法,开创性地解决了在大断面黄土隧道下穿构筑物施工中安全和进度的矛盾,有效地控制了洞内、外沉降变形,保证了下穿段隧道的安全快速施工和既有铁路的安全运营,并降低了工程造价,丰富了黄土隧道设计施工的理念。 相似文献
953.
Traffic microsimulation models normally include a large number of parameters that must be calibrated before the model can
be used as a tool for prediction. A wave of methodologies for calibrating such models has been recently proposed in the literature,
but there have been no attempts to identify general calibration principles based on their collective experience. The current
paper attempts to guide traffic analysts through the basic requirements of the calibration of microsimulation models. Among
the issues discussed here are underlying assumptions of the calibration process, the scope of the calibration problem, formulation
and automation, measuring goodness-of-fit, and the need for repeated model runs.
Yaron Hollander is a transport analyst, working for Steer Davies Gleave in London. His work combines advanced demand modelling, Stated Preference, appraisal, design of public transport systems, transport policy and network modelling. He completed his PhD at the Institute for Transport Studies in Leeds, and previously worked for the Technion – Israel Institute for Technology; for the Israeli Institute for Transportation Planning and Research; and for the public transport department at Ayalon Highways Co. Ronghui Liu is a Senior Research Fellow at the Institute for Transport Studies, University of Leeds. Her main research interests are modelling of traffic and microsimulation of driver behaviour and dynamical systems. She develops and applies network microsimulation models to a wide range of areas from transport policy instruments such as road pricing, to public transport operations and traffic signal controls. 相似文献
Ronghui LiuEmail: |
Yaron Hollander is a transport analyst, working for Steer Davies Gleave in London. His work combines advanced demand modelling, Stated Preference, appraisal, design of public transport systems, transport policy and network modelling. He completed his PhD at the Institute for Transport Studies in Leeds, and previously worked for the Technion – Israel Institute for Technology; for the Israeli Institute for Transportation Planning and Research; and for the public transport department at Ayalon Highways Co. Ronghui Liu is a Senior Research Fellow at the Institute for Transport Studies, University of Leeds. Her main research interests are modelling of traffic and microsimulation of driver behaviour and dynamical systems. She develops and applies network microsimulation models to a wide range of areas from transport policy instruments such as road pricing, to public transport operations and traffic signal controls. 相似文献
954.
955.
多学科设计优化方法用于船舶设计 总被引:2,自引:1,他引:1
为了提供更好地满足不断提高的军方和商业市场需求的产品.现代船舶设计需要获得真正的最优设计.它需要综合考虑所有学科以及它们之间的相互关系.船舶设计中涉及到的学科数目是如此众多,它们之间的相互关系是如此复杂以至于需要寻求一种新的设计技术来替代传统的设计螺旋方法.多学科设计优化(MDO)方法正是一种新的广泛应用于复杂工程系统的设计方法.在本文中,我们主要介绍了中国船舶科学研究中心将MDO应用于船舶设计的研究情况.我们应用iSlGHT软件集成美国弗吉尼亚大学公布的CGX设计模块来演示将MDO方法应用到船舶设计的整个过程,获得了比他们更优化的解.CGX模块也用来说明我们提出的子系统划分的概念.最后,基于我们的研究经验,我们也总结了一个在船舶设计中应用MDO方法的一般应包括的内容. 相似文献
956.
Arne Kesting Martin Treiber Martin Schnhof Dirk Helbing 《Transportation Research Part C: Emerging Technologies》2008,16(6):668-683
We present an adaptive cruise control (ACC) strategy where the acceleration characteristics, that is, the driving style automatically adapts to different traffic situations. The three components of the concept are the ACC itself, implemented in the form of a car-following model, an algorithm for the automatic real-time detection of the traffic situation based on local information, and a strategy matrix to adapt the driving characteristics (that is, the parameters of the ACC controller) to the traffic conditions. Optionally, inter-vehicle and infrastructure-to-car communication can be used to improve the accuracy of determining the traffic states. Within a microscopic simulation framework, we have simulated the complete concept on a road section with an on-ramp bottleneck, using empirical loop-detector data for an afternoon rush-hour as input for the upstream boundary. We found that the ACC vehicles improve the traffic stability and the dynamic road capacity. While traffic congestion in the reference scenario was completely eliminated when simulating a proportion of 25% ACC vehicles, travel times were already significantly reduced for much lower penetration rates. The efficiency of the proposed driving strategy even for low market penetrations is a promising result for a successful application in future driver assistance systems. 相似文献
957.
城乡客运组织优化措施探讨 总被引:1,自引:0,他引:1
城乡客运是道路旅客运输的重要组成部分。文章从百色路网的发展趋势入手,分析了现阶段百色城乡客运存在的主要问题,提出了促进城乡客运组织优化的举措和建议。 相似文献
958.
Herwig Schnuerer 《运输规划与技术》2013,36(3):237-246
This paper discusses the use of the concept of dynamic programming to the determination of road construction needs using accessibility criteria. An attempt is made to specify political and social goals such as quality of life and equal opportunity as parameters of road dimensioning. The objective of the method which is illustrated by a case study is to determine minimal total costs for various threshold values of conceivable accessibility standards. 相似文献
959.
Chenfeng Xiong 《运输规划与技术》2013,36(3):244-266
Many states in the USA have developed statewide travel demand models for transportation planning at the state level and along intercity corridors. Travel demand models at mega-region and provincial levels are also widely used in Europe and Asia. With modern transportation planning applications requiring enhanced model capabilities, many states are considering improving their four-step statewide demand models. This paper synthesizes representative statewide models developed with traditional four-step, advanced four-step, and integrated micro-simulation methods. The focus of this synthesis study is as much on model applications and data requirements as on modeling methods. An incremental model improvement approach toward advanced statewide models is recommended. Review findings also suggest model improvement activities should be justified by planning application needs. For statewide model improvement plans to be successful and financially sustainable, the return on model improvement investment needs to be demonstrated by timely applications that rely on improved model capabilities. 相似文献
960.
The GSOM (Generic second order modelling) family of traffic flow models combines the LWR model with dynamics of driver-specific attributes and can be expressed as a system of conservation laws. The object of the paper is to show that a proper Lagrangian formulation of the GSOM model can be recast as a Hamilton–Jacobi equation, the solution of which can be expressed as the value function of an optimal control problem. This value function is interpreted as the position of vehicles, and the optimal trajectories of the optimal control formulation can be identified with the characteristics. Further the paper analyzes the initial and boundary conditions, proposes a generalization of the inf-morphism and the Lax–Hopf formulas to the GSOM model, and considers numerical aspects. 相似文献