Sensitivity analysis on stochastic equilibrium transportation networks using genetic algorithm

This study deals with the sensitivity analysis of an equilibrium transportation networks using genetic algorithm approach and uses the bi‐level iterative sensitivity algorithm. Therefore, integrated Genetic Algorithm‐TRANSYT and Path Flow Estimator (GATPFE) is developed for signalized road networks for various level of perceived travel time in order to test the sensitivity of perceived travel time error in an urban stochastic road networks. Level of information provided to drivers correspondingly affects the signal timing parameters and hence the Stochastic User Equilibrium (SUE) link flows. When the information on road system is increased, the road users try to avoid conflicting links. Therefore, the stochastic equilibrium assignment concept tends to be user equilibrium. The GATPFE is used to solve the bi‐level problem, where the Area Traffic Control (ATC) is the upper‐level and the SUE assignment is the lower‐level. The GATPFE is tested for six‐junction network taken from literature. The results show that the integrated GATPFE can be applied to carry out sensitivity analysis at the equilibrium network design problems for various level of information and it simultaneously optimize the signal timings (i.e. network common cycle time, signal stage and offsets between junctions).     

韩国高速列车防撞设计与评估

针对韩国高速列车(KHST)的防撞性能进行深入地研究。选定行驶速度为110km·h-1的列车与一个15t重的刚性障碍物的撞击、两列行驶速度为30km·h-1的列车相撞作为严重撞击的事故场景,两列行驶速度为8km·h-1的列车相撞作为轻度撞击的事故场景。用有限元方法对KHST的防撞性进行了数学评估。一维和二维的仿真分析表明该车整体上具有良好的耐撞性。同时,对动车的前端部分做了三维壳体单元的仿真分析。使用安全带的旅客伤亡试验的结果说明KHST的良好性能足以在设置的事故场景中保护旅客的安全。最后,用实比例的撞击试验对仿真方法进行了验证。     

Assessment of alternative ventilation schemes at public transport interchange

The provision of mechanical ventilation in a semi-confined public transport interchange is mandatory in Hong Kong. The authority recommends the general use of low-level-supply and high-level-exhaust airflow schemes that different from the traditional ventilation concept in that low-level emitted vehicle pollutants are best removed at source. Analyses of air quality at typical public transport interchange environments are conducted for the two airflow schemes. The CFD simulations are generalized by studying light and heavy traffic conditions with adjusted ventilation rates to match the change in vehicle emission levels to examine pollutant concentrations at passenger waiting areas and the elevated footbridges. While the conventional high-level-supply and low-level-exhaust scheme could perform better during light traffic loads, the difference diminishes with increased traffic loads during peak hours. On the other hand, the high-level exhaust scheme has an advantage of serving as a smoke extraction system during a fire outbreak.     

Crosswind Feedforward Control - A Measure to Improve Vehicle Crosswind Behaviour

The theory of crosswind feedforward control was explained using the example of a vehicle with active front-wheel steering. Beforehand, the calculation formulas and frequency responses of the transient crosswind force and of the wind yaw moment acting on the vehicle were derived using the example of a simple vehicle fluid model. The influence of the transiency of crosswind disturbance on the dynamic crosswind behaviour of a vehicle was then presented. The results of simulation confirmed the analyses carried out in the frequency domain for feedforward control with front, rear and all-wheel steering. With front-wheel steering, the influence of crosswind on one of the vehicle movement variables (lateral acceleration or yaw rate) could be almost completely compensated by dynamic feedforward control. With rear-wheel steering, it is only possible to compensate directly for the influence on the yawing rate. Due to the setting of the side force in the same direction as the lateral wind force at the start, active rear-wheel steering is not so successful as active front-wheel steering. Nevertheless, the crosswind behaviour of a vehicle can be considerably enhanced by feedforward control with rear-wheel steering. The best crosswind behaviour was obtained with active all-wheel steering: the vehicle hardly responds at all to crosswinds and remains on course despite heavy gusts of wind.     

Use of an activity-based diary to collect household travel data

The paper describes the results of a pilot survey that used a one-day activity diary to collect origin-destination data, as opposed to a travel-based diary. The design of the diary is discussed, together with a comparison to a more conventional travel diary. The paper examines the extent to which the activity diary appears to have been capable of collecting good travel data that is at least comparable to travel diary efforts. In addition, a substantial portion of the paper is concerned with a comparison of the retrieval methods for the diaries. Two alternative methods were pilot-tested, one being the use of telephone retrieval and the other being mailback retrieval. Although the pilot test used small samples, the evidence appears to be strong that mailback is preferable to telephone retrieval, while telephone retrieval did not seem capable of providing some of the benefits often ascribed to it.     

HSST将于日本2005国际博览会投入商业运营

介绍名古屋东部丘陵线的概况和该线所用的磁悬浮运输系统、磁悬浮车辆的技术特点.     

160 km/h～200 km/h客车高性能合成闸片研究

概述了国内外树脂基合成摩擦材料和我国提速列车半金属合成闸片的现状,详细介绍了160km/h～200km/h客车高性能合成闸片的研制情况,并提出了制定160km/h～200km/h客车高性能合成闸片标准时应考虑的主要因素。     

Trading strategies in the market for tankers

This paper introduces a new approach in timing the sale and purchase of ships in the tanker market and examines the performance of this trading strategy over the period January 1976 to September 2004. Based on the long-run cointegration relationship between earnings and price, we establish a trading model which can be used as an indicator of investment or divestment timing decisions. We also perform statistical tests using the bootstrap approach in order to discount the possibility of data snooping biases and test the robustness of our trading models. Our results indicate that trading strategies based on earning-price ratios significantly out-perform buy and hold strategies in the tanker market.