基于SP调查的天津市居民出行行为时间价值

为揭示天津市居民出行行为时间价值的一般规律,采用SP调查中的卡片式面谈调查法,运用市场细分法确定调查规模及抽样率,采用计算包容性检查矩阵等数据处理手段,估算天津市居民出行行为时间价值。比较了出行行为时间价值与单位工作时间价值之间的关系,并分析了不同出行方式、出行目的、出行时段的时间价值,研究了出行收入与时间价值的变化规律。得出现阶段天津市居民出行行为时间价值的分布,表明大部分出行者不愿为出行支付较高费用,但随着收入增加,出行行为时间价值将会快速增长,使个体机动化出行方式的需求增大,城市出行方式结构可能出现拐点。     

Improving Tidal Turbine Performance Through Multi-Rotor Fence Configurations

Constructive interference between tidal stream turbines in multi-rotor fence configurations arrayed normally to the flow has been shown analytically, computationally, and experimentally to enhance turbine performance. The increased resistance to bypass flow due to the presence of neighbouring turbines allows a static pressure difference to develop in the channel and entrains a greater flow rate through the rotor swept area. Exploiting the potential improvement in turbine performance requires that turbines either be operated at higher tip speed ratios or that turbines are redesigned in order to increase thrust. Recent studies have demonstrated that multi-scale flow dynamics, in which a distinction is made between device-scale and fence-scale flow events, have an important role in the physics of flow past tidal turbine fences partially spanning larger channels. Although the reduction in flow rate through the fence as the turbine thrust level increases has been previously demonstrated, the within-fence variation in turbine performance, and the consequences for overall farm performance, is less well understood. The impact of turbine design and operating conditions, on the performance of a multi-rotor tidal fence is investigated using Reynolds-Averaged Navier-Stokes embedded blade element actuator disk simulations. Fences consisting of four, six, and eight turbines are simulated, and it is demonstrated that the combination of device- and fence-scale flow effects gives rise to cross-fence thrust and power variation. These cross-fence variations are also a function of turbine thrust, and hence design conditions, although it is shown simple turbine control strategies can be adopted in order to reduce the cross-fence variations and improve overall fence performance. As the number of turbines in the fence, and hence fence length, increases, it is shown that the turbines may be designed or operated to achieve higher thrust levels than if the turbines were not deployed in a fence configuration.

     

A logistics and supply chain management approach to port performance measurement

Although there is widespread recognition of the potential of ports as logistics centres, widely accepted performance measurements for such centres have yet to be developed. The essence of logistics and supply chain management is an integrative approach to the interaction of different processes and functions within a firm extended to a network of organizations for the purpose of cost reduction and customer satisfaction [1]. The logistics approach often adopts a cost trade-off analysis between functions, processes and even supply chains [2]. This approach could be beneficial to port efficiency by directing port strategy towards relevant value-added logistics activities. This paper seeks to show that through conceptualizing ports from a logistics and supply chain management approach, it is possible to suggest a relevant framework of port performance. A proposed framework is tested in a survey of port managers and other international experts.     

The 50<Superscript>th</Superscript> anniversary of container shipping the Admiral Sheldon Kinney (USN) lectures

The paper offers a historical overview of the container revolution. It starts from the origin more than 50 years ago, presenting how the pioneer Malcom McLean came to this idea that has changed the nature of Shipping. It then presents how and why container shipping was gradually accepted and what has been the main trends during the last 50 years: the increase in vessels’ and containers’ size and in vessels’ speed. Finally, the paper investigates what the future will bring and notably sheds light on the increase in containers’ size and on the improvements in terminal and rail services.     

Spark Ignition Engine Idle Speed Control Using a Novel Framework and Enabling Control of the Tradeoff between Fuel Consumption and Load Rejection Capability

In this paper, a new framework for idle speed control is presented [The idle control methodology described paper is protected by international patent law]. A simple new discrete event based engine model evolving in the crank domain is given and is parameterized using a combination of dynamic identification and steady state calibration. The majority of the non-linearities can then be inverted and a second synthetic output is introduced. This second output is the torque reserve of the engine and enables control of the tradeoff between disturbance rejection capabilities and engine efficiency. A linear controller is designed using the H 8 loopshaping technique and results are presented from dynamometer based engine tests.     

在常规线路上实现高速

介绍了在常规线路上实现高速的可行性,阐述了遇到的主要技术难题及解决方法。     

Metropolitan railways: present characteristics and future prospects

Urban bus operation in Chile is totally deregulated. This is the only example in the world where access to the urban bus transport market is totally free, and where the government does not exercise any control over the fares. This policy has been implemented progressively since 1979. Ten years later, it is possible to draw some conclusions from the experience. To summarize these conclusions, one could say that (i) the impact of deregulation has been almost exactly the opposite of what was expected: fares have risen and the diversity of services has been reduced, (ii) the reasons for this discrepancy lie less in the action of a cartel than in the specifics of urban transport supply and (iii) there is probably more to be expected from a refined deregulation policy, taking into account these specifics, than from a drive back to the traditional regulation system.     

Mapping evacuation risk on transportation networks using a spatial optimization model

The focus of this paper is on the development of a methodology to identify network and demographic characteristics on real transportation networks which may lead to significant problems in evacuation during some extreme event, like a wildfire or hazardous material spill. We present an optimization model, called the critical cluster model, that can be used to identify small areas or neighborhoods which have high ratios of population to exit capacity. Although this model in its simplest form is a nonlinear, constrained optimization problem, a special integer-linear programming equivalent can be formulated. Special contiguity constraints are needed to keep identified clusters spatially connected. We present details on how this model can be solved optimally as well as discuss computational experience for several example transportation networks. We describe how this model can be integrated within a GIS system to produce maps of evacuation risk or vulnerability. This model is now being utilized in several research projects, in Europe and the US.     

美国新泽西州马纳霍金海湾大桥的疲劳问题

美国新泽西州72号公路马纳霍金海湾大桥的上部结构由17跨连续及悬臂铆接钢板梁和横梁系统组成,其中包括5跨销钉一吊杆悬挂梁.由于桥梁的"结构性能不足",20世纪90年代初对大桥进行了系统的修复工作.修复实施过程中,在很多部位发现了疲劳裂纹和桥面板混凝土剥落,疲劳裂纹主要为出现在横梁腹板的水平裂纹、横梁与主梁间托板连接角钢...