A control theoretic formulation of green driving strategies based on inter-vehicle communications

Various green driving strategies have been proposed to smooth traffic flow and lower pollutant emissions and fuel consumption in stop-and-go traffic. In this paper, we present a control theoretic formulation of distributed, cooperative green driving strategies based on inter-vehicle communications (IVCs). The control variable is the advisory speed limit, which is designed to smooth a following vehicle’s speed profile without changing its average speed. We theoretically analyze the performance of a constant independent and three simple cooperative green driving strategies and present three rules for effective and robust strategies. We then develop a distributed cooperative green driving strategy, in which the advisory speed limit is first independently calculated by each individual vehicle and then averaged among green driving vehicles through IVC. By simulations with Newell’s car-following model and the Comprehensive Modal Emissions Model (CMEM), we demonstrate that such a strategy is effective and robust independently as well as cooperatively for different market penetration rates of IVC-equipped vehicles and communication delays. In particular, even when 5% of the vehicles implement the green driving strategy and the IVC communication delay is 60 s, the fuel consumption can be reduced by up to 15%. Finally we discuss some future extensions.     

绿波协调信号交叉口群的延误计算方法研究

在绿波协调控制交叉口群中,绿波段前沿交叉口对于交通流具有整流特性.针对单一交叉口延误计算方法对交叉口群整流特性考虑不足的问题,基于车流运行时间偏移呈正态分布的假设,采用非集计方法分别提出了绿波带内、绿波带间和右转车流的延误计算模型.分析了交叉口群对车流的整流作用,以最小二乘拟合法为基础,提出了交叉口进口道车辆到达函数拟合方法.分别考虑交叉口群绿波带内和绿波带间的车流运行时间偏移,以单车延误期望累积建立了交叉口进口道车流延误计算模型.利用交叉口车流数据验证了该方法的实用性和有效性.     

盐城市建军路单向(西-东)绿波控制

在对现有盐城市五个交叉口的交通情况分析基础上,指出其信号配时的不合理。通过比较设计前后道路通行能力的变化和延误的变化以及交通综合效应的改善,证明单向绿波协调控制能够在不增加各交叉口总延误前提下,使主干道上主流方向的车辆在规定车速下不间断的通过各交叉口,从而改善该主流方向的交通运行状况。最后对盐城市一条实际道路上的五个交叉口进行单向绿波协调控制设计。     

基于FCE-DEA-AHP的城市物流绿色度评价研究

针对城市物流的绿色化发展问题,运用层次分析法对城市物流绿色化体系进行划分,在此基础上构建模糊综合评判模型,利用数据包络分析法把多个城市物流在各单因素指标的绿色度表现量化,并结合相应各指标权重进行综合评价和排序,最后通过实例印证评价方法的直观性和高效性.     

Friction characteristics in green drilling titanium alloy Ti6Al4V

Titanium alloy Ti6Al4V, as difficult-to-cut material, has poor machinability. Conventional cutting fluid serves as a coolant and lubricant. In green drilling, water vapor is recognized as an effective coolant; however, its lubrication properties are not well known in drilling. This paper investigates the friction characteristics between chip and tool in green drilling Ti6Al4V, compared with that in sliding and turning process. A friction evaluation model is developed based on the equivalent model of drilling, then is used to calculate the effective friction coefficient. Results indicate that the friction coefficient on the tool-chip interface is considerably reduced in drilling by water vapor, so the drilling forces decrease, too. The friction coefficient decreases as velocity increases in drilling, which is different from the law of sliding tests; the friction coefficient increases when the distance to chisel edge increases.     

发展山地城市绿色自行车交通的探讨

自行车交通作为城市绿色交通方式,在山地城市开展更具有现实意义。分析重庆市地域及交通特征,探讨其自行车交通的功能定位和发展区域,并以冉家坝地区为例进行分析,为倡导与推广山地城市绿色自行车交通提供有益参考。     

近郊风景旅游区交通规划的新思路——以北京大西山风景区交通规划为例

大城市近郊风景旅游区交通系统是一个复杂的系统．如何能够实现其可持续发展,使大城市近郊风景旅游区系统走向有序发展,是一项重要课题。以北京市海淀区大西山风景旅游区交通规划为例,阐述该规划方案的特点,并提出风景旅游区交通规划的新方法——在保护自然环境的条件下,为产业化提供条件,并体现人文特征,进而得出风景旅游区交通规划应以可持续性发展为主题的结论。     

单点公交被动优先下信号配时方法研究

为尽可能减少公交优先对社会车流干扰,提出一种不依赖公交检测信息,只考虑社会车流流量实现公交优先的信号配时方法。这种信号配时方法采用搭接公交相位,可充分利用社会车流的相位绿灯时间,既满足社会车流通行,还能使公交车获得更多绿灯时间。论文从绿灯时间组成和共用相位角度分析搭接相位的可行性,研究有利于公交优先的相位相序方法,并建立了信号配时参数模型,最终通过模拟验证说明该信号配时方法不仅能减少公交车延误,还可提高绿灯利用率、保障交叉口服务水平。     

绿色技术创新——港口科技创新的新思路

绿色技术创新是发展低碳经济的一种趋势。介绍了张家港港务集团通过调整码头功能的布局、改造码头装卸工艺流程、利用空气源热泵等一系列的节能改造。最后得出结论,绿色技术创新手段达到节能减排的目的,能为港口企业带来良好的效益。     

绿色船舶发展现状及方向分析

随着环保要求的不断增强,绿色船舶已成为未来船舶发展的代名词。通过对绿色船舶定义的介绍,诠释了绿色船舶的内涵;在阐述目前绿色船舶研发现状的基础上,分析了绿色船舶未来的发展方向,具有一定参考价值。