An improved cellular automata model for heterogeneous work zone traffic

This paper aims to develop an improved cellular automata (ICA) model for simulating heterogeneous traffic in work zone. The proposed ICA model includes the forwarding rules to update longitudinal speeds and positions of work zone vehicles. The randomization probability parameter used by the ICA is formulated as a function of the activity length, the transition length and the volumes of different types of vehicles traveling across work zone. Compared to the existing cellular automata models, the ICA model possesses a novel and realistic lateral speed and position updating rule so that the simulation of vehicle’s lateral movement in work zone is close to the reality. The ICA model is calibrated and validated microscopically and macroscopically by using the real work zone data. Comparisons of field data and ICA for trajectories, speed and speed–flow relationship in work zone show very close agreement. Finally, the proposed ICA model is applied to estimate traffic delay occurred in work zone.     

基于泊松方程的磁罗盘磁域自差修正

电子磁罗盘是现代车辆导航中重要设备,但至今尚未应用到船舶导航上。针对船载磁航向测量中存在的各种误差,分析了船载情况磁罗盘系统误差的形成原因和机理,在此基础上系统地研究了船载特殊情况中数字磁罗盘误差校正问题,并且具体给出基于泊松方程的磁域的误差修正方法,实验结果表明,该方法简单有效地实现磁航向误差校正,且补偿精度高、成本低。     

基于IEEE1451.4的智能水听器设计

该文遵循IEEE1451.4标准和1-wire通信协议,分析了标准水听器的结构特点,在原来模拟水听器中加入可存放数据的TEDS存储器,并增加并行的数字接口,采用1-wire存储器件DS2433和1-wire转USB接口适配器核心芯片DS2490,开发了一款智能化的水听器及读写电路适配器,设计了基于OneWireViewer的读写软件,并研究了水听器校正模型,提出了一种可靠的智能化的水听器实现方案。     

微粒群优化理论在光电载荷安装误差修正中的应用

载荷安装误差是影响空中机动单站光电载荷无源定位精度的主要因素。针对传统解析方法建模复杂、精度不高的问题,采用一种微粒群优化方法对光电载荷安装误差进行修正。仿真分析表明,所采用的微粒群优化方法搜索效率高、搜索效果好,能够实现对安装误差的高精度修正,有望为实际应用提供一种简易可行的方法。     

The joint estimation of respondent-reported certainty and acceptability with choice

In the stated choice literature, increasing attention has been paid to methods that seek to close the gap between the choices from these experiments and the choices experienced in the real world. Attempts to produce model estimates that are truer to real market behaviours are especially important for transportation, where many important policy decisions rely on such experiments. A recent approach that has emerged makes use of a certainty index whereby respondents report how certain they are about each choice they make. Additional literature also posits that when making decisions, people first identify an acceptable set of alternatives (alternative acceptability) such that a consideration set if formed and it is from this reduced set that the ultimate choice is made. This paper presents two models that jointly estimates choice and choice certainty and choice and alternative acceptability. This joint estimation allows the modeller to overcome potential endogeneity that may exist between these responses. In comparing choices of differing certainty, surprisingly little difference in marginal sensitivities are found. This is not the case in the alternative acceptability models however. An important finding of this research is that what could be interpreted as preference heterogeneity may in fact be more closely linked to scale. The ramifications of these results on future research are discussed.     

Automatic calibration of agent-based public transit assignment path choice to count data

This work describes the calibration of a schedule-based transit assignment inside an iterative microscopic agent-based simulation. The calibration challenge implies that the behavioral rules should be modified in order to move the simulation closer to observed passenger counts. First, route choice set of agents is enriched with travel parameter utilities randomization. Secondly, the calibration interacts directly into the performance evaluation of individual daily plan of activities, so that the plan is also evaluated for its contribution to the count reproduction. In this way, appropriate plans from the calibration perspective can persist along simulation iterations. The Berlin public transport system with day-based counts is used as test scenario. The results show that the calibration approach can work with large scale scenarios, and that it is able to deal with the inter-temporal aspects implied by counts.     

船模航行试验技术及在航道工程中的应用

船模航行试验是在河工模型和船模相结合基础上发展起来的试验研究方法。论述了船模航行试验的相似条件和相关技术,指出这项技术适于研究通航水流条件和工程方案的优化布置以及船舶性能、航道尺度、航道水流三者的相互关系和提高通航能力的措施等。介绍了这项技术在航道工程中的应用。     

大宗散货计量中的实物检定装置研制

介绍目前国内外在散装货运输中的 3种重量计量设备 ,简述作者研制成功的“双秤取动累加称量装置”的概况 ,包括装置的工作原理、结构、称重控制、物料输入控制 ,以及整台设备使用结果分析等 ,最后介绍为试验而模拟使用“双秤并联试验机”的概况。该实物检定装置已于 2 0 0 1年 4月 5日通过由交通部科技司组织的鉴定和验收。     

机车、车辆整车称重试验台

机车、车辆整车称重试验台是为满足各种不同轨距、轴距的4轴、6轴机车,车辆整车出厂型式试验,例行试验称重而研制的测试设备。文章着重介绍该称重试验台的系统组成、设计原理及其计量校准等。