在驾驶席“打坐”——体验特斯拉自动驾驶

人们常说,纪录是用来打破的。我曾经用31小时零4分驾车横穿美国。后来,Ed Bolian打破了这一纪录。而今年早些时候,Carl Reese,Deena Mastracci和几个朋友用特斯拉Model S创造了一项电动汽车横穿美国的纪录。老实说,2006年Polizei车队横穿美国时,我从未想过有天会驾驶一辆96％的时间都在自动驾驶的电动汽车再次横越美国。     

海洋工程深水开发浮式系统的耦合计算方法

当前海洋深水开发所用的浮式平台系统多为浮式船体与柔性系泊系统及立管系统的耦合体,这样,浮式船体与柔性系统之间必将有相互影响及相互作用.由于其整体系统的非线性及动力学特性,势必要求对深水浮式平台系统进行有效的时域耦合分析计算.本文首先简要介绍时域耦合分析的具体问题及解决方法,然后介绍作者近年来开发的HARP(Hull And Riser Program)耦合计算程序.     

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虽然多数先进技术应用的目的是改善路网的运行效率和安全性,但目前为止其在提高道路安全性方面的作用并不突出. 例如,可以提供大容量、多方面信息的可变信息板,其设立之初的唯一目的是引导驾驶员的道路行驶. 事实上,这种信息传达装置在不发布路段行驶信息的情况下,还可以发布交通安全信息以改善交通安全状况. 本文选取两种禁止超速信息为研究对象,分析了该信息的发布对于驾驶员态度和路段行驶车速的影响. 对近100名驾驶员进行抽样调查. 测试路段为加拿大埃德蒙顿市和卡尔加里市间2号高速公路. 研究结果表明,本文所选取的两种禁止超速标识对驾驶员态度和行驶车速产生的影响相对较小.     

The simple,efficient, elegant,and effective model (SE3M) of land use and transportation

Integrated land use/transportation forecasting models add significant policy and infrastructure alternatives analysis capabilities to the urban planning process. Historically, the financial, time, and staff requirements to develop one of these models has put them beyond the reach of most small- to medium-sized urban areas. The purpose of this paper is to present the large zone economic submodel of SE³M, an integrated model – founded upon economic base theory and bid-rent theory – that is reasonably accurate, yet simpler in form, function, and implementation than competing models. The US territory of Guam is used as the case study/proof of concept implementation for this model framework. The submodel presented here was validated against a horizon year with known data for zonal level population and employment totals together with control totals for the island as a whole. The model was able – across two base years and one validation, horizon year – to locate all jobs and a high percentage of the population on each zone on the island.     

Guaranteed prediction and estimation of the state of a road network

The paper presents an algorithm for the prediction and estimation of the state of a road network comprising freeways and arterials, described by a Cell Transmission Model (CTM). CTM divides the network into a collection of links. Each link is characterized by its fundamental diagram, which relates link speed to link density. The state of the network is the vector of link densities. The state is observed through measurements of speed and flow on some links. Demand is specified by the volume of vehicles entering the network at some links, and by split ratios according to which vehicles are routed through the network. There is model uncertainty: the parameters of the fundamental diagram are uncertain. There is uncertainty in the demand around the nominal forecast. Lastly, the measurements are uncertain. The uncertainty in each model parameter, demand, and measurement is specified by an interval. Given measurements over a time interval [0, t] and a horizon τ ? 0, the algorithm computes a set of states with the guarantee that the actual state at time (t + τ) will lie in this set, consistent with the given measurements. In standard terminology the algorithm is a state prediction or an estimate accordingly as τ > 0 or =0. The flow exiting a link may be controlled by an open- or closed-loop controller such as a signal or ramp meter. An open-loop controller does not change the algorithm, indeed it may make the system more predictable by tightening density bounds downstream of the controller. In the feedback case, the value of the control depends on the estimated state bounds, and the algorithm is extended to compute the range of possible closed-loop control values. The algorithm is used in a proposed design of a decision support system for the I-80 integrated corridor.     

Planning framework of analytical approaches applied to Zairean transportation

The purpose of the article is to provide an analytical planning framework which includes decision makers, organizations imposing operational and institutional constraints, direct customers and indirect beneficiaries. All these actors have differ-ent, only partially overlapping, interests; this increases the complexity of capital budgeting and imposes limitations on decision-making framework has important implica-tions for project selection, charging and depreciation policies. Although the illus-trations are limited to transport planning, the framework can be easily applied to any sector or country. For example, the English engineering students applied the framework to 18 industries in the U.K.: Auto-diesels, Bass, British Airways, British Gas, British Oxygen, British Petroleum, British Rail, British Steel, British Telecom, East Midland Electricity, Guinness, Imperial Chemical Industries (ICI), Inter-national Computers Limited (ICL), Marks & Spencer, Mercury Communications, National Westminster Bank, Rover and Thames Television (see A. Kelvin, 1993, Increasing student participation in the learning process. Higher Education, 26(4), December, 449-470).     

无线ECP制动系统在重载货物列车上的应用

介绍了澳大利亚BHP铁矿公司利用无线ECP等新技术开行重载列车的情况,阐述了采用新技术对提高运输效率、改善列车运行性能等所带来的好处。     

Empirical assessment of urban traffic congestion

This paper presents an empirical assessment of urban traffic congestion in Central London, UK. Compared with freeways or motorways, urban networks are relatively less studied because of its complexity and availability of required traffic data. This paper introduces the use of automatic number plate recognition technology to analyze the characteristic of urban traffic congestion in Central London. We also present the use of linear regression to diagnose the observed congestion and attribute them to different causes. In particular, we distinguish the observed congestion into two main components: one due to recurrent factors and the other due to nonrecurrent factors. The methodologies are illustrated through a case study of Central London Area. It is found that about 15% of the observed congestion in the region is due to nonrecurrent factors such as accidents, roadwork, special events, and strikes. Given the significance of London, the study will be valuable for transport policy evaluation and appraisal in other global cities. Copyright © 2013 John Wiley & Sons, Ltd.