Forced Steering of Rail Vehicles: Stability and Curving Mechanics

A forced steering rail vehicle employs linkages between.the carbody and wheelsets to force a more radial wheelset alignment. It is shown that the curve negotiation capability of forced steering trucks is significantly improved over conventional and self steering radial trucks. Parametric curves are presented showing angle-of-attack and lateral flange force as a function of steering gain parameters and truck bending stiffness. It is also shown that the forced steering concept can produce kinematic instability and severely reduced critical speeds for low conicities and creep coefficients. Analytic expressions are derived that illustrate how these kinematic instabilities can be avoided.     

如何卖出一辆特斯拉？关于特斯拉，你所不知道的秘密

特斯拉的销售是最幸福的,因为只要是T粉（前提需要有足够的钱）不用你介绍他都会买的。特斯拉的销售是最悲惨的,因为世上还有很多人不知道特斯拉。     

The optimal dispatching of taxis under congestion: A rolling horizon approach

Taxis make an important contribution to transport in many parts of the world, offering demand‐responsive, door‐to‐door transport. In larger cities, taxis may be hailed on‐street or taken from taxi ranks. Elsewhere, taxis are usually ordered by phone. The objective of a taxi dispatcher is to maximize the efficiency of fleet utilization. While the spatial and temporal distribution of taxi requests has in general a high degree of predictability, real time traffic congestion information can be collected and disseminated to taxis by communication technologies. The efficiency of taxi dispatching may be significantly improved through the anticipation of future requests and traffic conditions. A rolling horizon approach to the optimisation of taxi dispatching is formulated, which takes the stochastic and dynamic nature of the problem into account. Numerical experiments are presented to illustrate the performances of the heuristics, taking the time dependency of travel times and passenger arrivals into account.     

Mathematical Models and Computer Simulation of Nitrogen Concentration Profiles in Pulse Ion Nitrided Layers

IntroductionThedireCtcrt(DC)ionndriding,whichhasbeenopliedfOrmanyyears,didn'tthoroughlysolvetheionnitridingproblemofsomecomPlexwOrkPlacesinshapeandstrUctUreunhlthepulse-iondridingPrOcessingaroseIl].Recentresultsshowthatthearc-CUttin-offsystemsincircuitcanbecancelled,thishasmadethecOntrOlsystemsofionnitridingequiPmentandhaacestwbessimPlnygreatiyMorehaPOrtantiy,theexcellentschcequalityofthewOrkPiecetreatedhasa1sobeenObtainedemPlovingPulseionchdingcomParedwithDCionnitriding.InOrdertOr…     

The future for in‐vehicle information systems: The technology and its impacts

In‐vehicle information has an important social role to play in improving the efficiency and safety of travel by all modes. In this review, three generations of system are identified. The first generation consists of simple in‐vehicle units relying heavily on external data. The second generation has more sophisticated in‐vehicle units with colour TFT screens and DVD players for maps and entertainment. The third generation again makes use of external data, using the mobile phone network to download map sections and other data as and when required, thereby obviating the need for beacons and map CDs. For locationing, GPS (and/or Galileo, the European version of GPS) remains the favoured technology. Portable devices offering multi‐modal information could improve inter‐modal transport efficiency.     

解读车轮轴承

像当今汽车上许多零部件一样,车轮轴承已变得越来越可靠,以至于在没有出现故障前我们往往会忽视它。然而,了解故障原因,即使是老化的原因,对我们来说都是有意义的。     

最安静的兰博基尼

<正>这款由兰博基尼推出的混合动力超级跑车既可以拥有669kW的恐怖输出,还可以以纯电动模式悄无声息地行驶在之前结束的巴黎车展上兰博基尼终于推出了一款与"3大"(保时捷918、迈凯伦P1、法拉利Laferrari)抗衡的插电式混合动力超级概念车。虽然这款车型的具体量产计划暂时还未知,但是其账面上的数据表现已经让我为之震惊。Asterion LPI 910-4采用了一台5.2L V10自然吸气发动机,配合3台电动机,总功率达到了惊人的669kW(910PS)。如此暴躁的动力输出使其0~100km/h加速只     

Variances and covariances for origin-destination flows when estimated by log-linear models

An expression is derived for the variances and covariances of the logarithms of origin- destination flows when estimated by one of a family of log-linear models. Among this family is the Furness growth factor model, the gravity model, the Willumsen model and the Van Zuylen-Bell model. Variances and covariances for the logarithms of the parameters incorporating prior information and for the values of the constraints with which the fitted values must conform are transformed linearly into approximate variances and covariances for the logarithms of the fitted values. Additional error due to misspecification of either the model or the constraints is not taken into account. Depending on the model, the prior information parameters may correspond to values of a deterrence function or to a base year trip matrix, while the constraints may represent design year trip end totals or traffic counts. As an illustration, the expression is applied to an example involving Willumsen's model.     

Multi-objective signal control of urban junctions – Framework and a London case study

This paper presents an approach to multi-objective signal control using fuzzy logic. The signal control uses fuzzy logic where the membership functions are optimised according to the Bellman–Zadeh principle of fuzzy decision-making. This approach is both practical for the decision-maker and efficient, as it leads directly to a Pareto-optimal solution. Signal control priorities are ultimately a political decision. Therefore the tool developed in this research allows the traffic engineer to balance the objectives easily by setting acceptability and unacceptability thresholds for each objective. Particular attention is given in the example to pedestrian delays. The membership functions of the fuzzy logic are optimised by a genetic algorithm coupled to the VISSIM microscopic traffic simulator. The concept is illustrated with a case study of the Marylebone Road–Baker Street intersection in London at which pedestrians as well as vehicle flows are high. The results prove the feasibility of the framework and show the vehicle delays for a more pedestrian friendly signal control strategy.     

CNR管线稳定水深再破记录

CNR国际负责一段穿过1250米深的海底峡谷的输气管线（宽6英寸）,这段管线从Baobab的海上油气浮船一直到西非的Espoir的主管线出口