Carbon emission from urban passenger transportation in Beijing

Urban passenger transport significantly contributes to global greenhouse gas emissions, especially in developing countries owing to the rapid motorization, thus making it an important target for carbon reduction. This article established a method to estimate and analyze carbon emission from urban passenger transport including cars, rail transit, taxis and buses. The scope of research was defined based on car registration area, transport types and modes, the stages of rail transit energy consumption. The data availability and gathering were fully illustrated. A city level emission model for the aforementioned four modes of passenger transport was formulated, and parameters including emission factor of electricity and fuel efficiency were tailored according to local situations such as energy structure and field survey. The results reveal that the emission from Beijing’s urban passenger transport in 2012 stood at 15 million tonnes of CO₂, of which 75.5% was from cars, whereas car trip sharing constitutes only 42.5% of the total residential trips. Bus travel, yielding 28.6 g CO₂, is the most efficient mode of transport under the current situations in terms of per passenger kilometer (PKM) emission, whereas car or taxi trips emit more than 5 times that of bus trips. Although a decrease trend appears, Beijing still has potential for further carbon reduction in passenger transport field in contrast to other cities in developed countries. Development of rail transit and further limitation on cars could assist in reducing 4.39 million tonnes CO₂ emission.     

FURUNO GPS导航仪的坐标转换算法

大地坐标系之间的转换一直是导航领域十分关注的课题。本文将对ＦＵＲＵＮＯＧＰ－５０００型ＧＰＳ接收机的大地坐标转换问题做了初步的探索,通过实际测量与理论计算来验证其坐标转换模型。     

考虑旅客选择行为的高铁席位动态控制策略

利用基于选择行为的网络收益管理原理研究高铁席位动态控制策略.首先,针对多列车多停站的高铁网络建立考虑旅客选择行为的席位控制动态规划模型.然后,设计两阶段控制机制：第一,采用近似动态规划技术,对价值函数进行线性近似,设计策略迭代算法离线获得时间依赖的投标价格;第二,采用能够描述多种选择行为机理的马尔科夫链选择模型刻画旅客选择行为,将投标价格作为输入参数,在线运行品类优化算法获得实时控制策略.最后以京沪高铁为背景设计仿真实验,结果表明该机制在需求水平较低时能够明显改善收益,且保护长途票额.该机制不仅可获得实时动态控制策略,而且通用性好,还可利用历史数据进行参数学习与更新,实现更为精细地连续优化.     

船用低速柴油机实时仿真模型开发及应用

以某型小缸径船用低速柴油机为对象,基于该柴油机一维性能模型,开展实时仿真模型的快速开发和标定。比较了简化后实时仿真模型与原性能模型的计算时间和仿真精度。应用该模型在硬件在环测试平台上测试新研制的柴油机控制器。试验结果表明,该模型可正常接收和反馈正确的控制器指令和柴油机运行参数,满足电控系统硬件在环测试的试验要求。     

基于ANSYS的大型船用升降平台密封性能研究

根据某大型船用升降平台的密封性能要求,对比分析了线密封形式与面密封形式的特点,确定了面密封的结构形式。基于ANSYS软件,采用2D-Model建立了三元乙丙橡胶材料的Mooney-Rivlin模型,分析了密封圈在不同压缩量时的密封性能,得到密封圈的最优压缩量,可为后续密封结构缩比样机的研制及密性试验提供参考。     

Classification modeling approach for vehicle dynamics model‐integrated traffic simulation assessing surrogate safety

To assess safety impacts of untried traffic control strategies, an earlier study developed a vehicle dynamics model‐integrated (i.e., VISSIM‐CarSim‐SSAM) simulation approach and evaluated its performance using surrogate safety measures. Although the study found that the integrated simulation approach was a superior alternative to existing approaches in assessing surrogate safety, the computation time required for the implementation of the integrated simulation approach prevents it from using it in practice. Thus, this study developed and evaluated two types of models that could replace the integrated simulation approach with much faster computation time, feasible for real‐time implementation. The two models are as follows: (i) a statistical model (i.e., logit model) and (ii) a nonparametric approach (i.e., artificial neural network). The logit model and the neural network model were developed and trained on the basis of three simulation data sets obtained from the VISSIM‐CarSim‐SSAM integrated simulation approach, and their performances were compared in terms of the prediction accuracy. These two models were evaluated using six new simulation data sets. The results indicated that the neural network approach showing 97.7% prediction accuracy was superior to the logit model with 85.9% prediction accuracy. In addition, the correlation analysis results between the traffic conflicts obtained from the neural network approach and the actual traffic crash data collected in the field indicated a statistically significant relationship (i.e., 0.68 correlation coefficient) between them. This correlation strength is higher than that of the VISSIM only (i.e., the state of practice) simulation approach. The study results indicated that the neural network approach is not only a time‐efficient way to implementing the VISSIM‐CarSim‐SSAM integrated simulation but also a superior alternative in assessing surrogate safety. Copyright © 2014 John Wiley & Sons, Ltd.     

船舶柴油发电机转速神经网络模型参考自适应控制

结合人工神经网络与模型参考自适应控制,形成船舶柴油发电机转速神经网络自适应控制。对由传感器检测后获取的特征值进行归一化处理,把经过处理的特征值作为神经网络的输入样本集,设计输出样本集,建立BP神经网络和ELMAN神经网络,用整理后的数据训练神经网络,使神经网络实现转速的自适应控制功能,并对神经网络模型进行仿真测试。仿真结果表明该方法控制精度高,动、静态特性好。     

公路数字化地面模型系统开发中的网格理论

介绍了公路数字化地面模型(DTM)系统开发中的核心算法即数模网格划分技术.     

Communicating something confidential while travelling by train: the use of a telephone conversation versus silent modes

Wireless ICTs are often used in public transport. Using survey data collected amongst 98 train travellers this article aims to gain insight into important factors that affect train travellers’ intentions to communicate with distant others while travelling. More specifically, the focus is on the decision-making process that leads to the intention to choose for a confidential conversation either via ‘audible’ mobile phone or via ‘silent’ SMS/e-mail. An approach that is related to the Extended Model of Goal-directed Behaviour (EMGB) is applied. Structural equation modelling results indicate that in particular past SMS behaviour, the desire to communicate (goal desire), the perceived efficacy and controllability influence the intention to conduct a confidential phone conversation in the train. The influence of the social environment (e.g. eavesdropping) seems to be less important. Several EMGB constructs are strongly influenced by age. It seems that older respondents have more negative attitudes towards telephoning while travelling by train, and find it more difficult to call other people in such a situation. Finally, they have a lower intention than younger respondents to conduct a confidential conversation over the phone while travelling.

涡激振动影响下细长海洋结构物的阻力特性

利用柔性圆柱体涡激振动水池模型试验对细长海洋结构物发生涡激振动时的阻力特性进行研究。利用试验测得的圆柱体模型顺流向平均弯曲应变,结合梁复杂弯曲理论,计算出模型各截面处的平均阻力,获得沿模型轴向分布的阻力系数,分析涡激振动影响下细长海洋结构物阻力系数的变化特性。研究结论表明:均匀流下细长海洋结构物的阻力为非均布载荷,涡激振动对阻力系数具有放大效应,导致阻力系数在1.4~2.5之间变化。