Characteristics of operating mode distributions of light duty vehicles by road type,average speed,and driver type for estimating on-road emissions: Case study of Beijing

Abstract

Researchers have collected extensive vehicle activity data in Beijing using GPS and attempted to develop a comprehensive database of facility- and speed-specific operating mode (OpMode) distributions of various vehicle types for estimating on-road vehicle emissions. This study developed the specific OpMode distributions of light duty vehicles (LDVs) for both restricted access and unrestricted access road types at various average speeds for characteristic analysis. (1) Strong patterns are found in the variations in OpMode distributions with the increase in the average speed: the time fraction of Decelerating/Braking remains less than 7%. The fraction of Idling decreases dramatically from 95% to 0%, while the fraction of Cruising/Accelerating increases from 2% to 94%. The fraction of Coasting increases to 28% and then decreases. (2) The time fractions for restricted access and unrestricted access are significantly different at the same average speeds, especially in Operating Modes #0, #1, #11, #12, #13, #14, #21, and #22, possibly causing an error of 20% in the emissions estimations. (3) Taxis show different OpMode distributions than those for private cars in the operating modes of Decelerating/Braking, Idling, and high-VSP modes, especially at low average speeds. The differences are derived from the more skillful driving behaviors of taxi drivers and may cause an estimation error of over 10%. Thus, the activities of taxis and private cars should be modeled separately for on-road emissions estimations.     

高速公路养护经费测算方法研究

根据指标体系的确定原则,构建了高速公路养护维修率的指标体系;结合调研数据特点,提出养护维修率的定量预测方法及6个计算变量;建立了基于综合路况的公路公里养护维修费用计算模型,并提出模型中的关键参数基准值和权重系数的确定方法。实例验证结果表明,本研究方法可为养护经费的合理分配提供决策依据。     

沥青洒布量控制模式研究

分析了沥青洒布系统结构与影响沥青洒布精度的因素,对目前常用的沥青洒布量控制模式进行了介绍,研究了其本质与优缺点,为不同沥青洒布设备和洒布工况合理选用沥青洒布量控制模式提供了参考.     

基于顾客价值的高速公路市场营销模式

以广州北环高速公路为研究对象，对其高速公路市场营销模式进行分析研究。通过分析，得出该公司成功的最大原因是基于顾客价值链，在高速公路出人口周边经济带中有意识培育关联产业，有针对性地开发高盈利能力的顾客，最大限度吸引和稳住自己的盈利顾客群体，从而培育了自己的核心竞争能力，确保了收入和效益的稳定增长。     

锦白铁路扩能工程牵引方式的研究

牵引方式是铁路主要技术标准之一,合理的牵引方式能够为国民经济的发展带来巨大的效益。锦白铁路是一条以煤炭运输为主的货运铁路,运量到发地集中,通道独立性高,运量增长潜力大,采用电力牵引优势明显,这也符合国家能源政策及铁路规划,且运营期的费用较内燃牵引节省程度大,投资回报率高,回收期短,所以本线的牵引方式宜采用电力牵引。     

现代有轨电车售检票系统方案的研究

简要分析地铁售检票模式、快速公交售检票模式和公交汽车售检票模式的特点,结合分析现代有轨电车售检票系统技术的特点。以此为基础,从现代有轨电车售检票方案、系统票制方案、车票方案等方面内容重点阐述现代有轨电车售检票系统方案的研究。     

A multi-class model-based control scheme for reducing congestion and emissions in freeway networks by combining ramp metering and route guidance

The paper proposes a multi-class control scheme for freeway traffic networks. This control scheme combines two control strategies, i.e. ramp metering and route guidance, in order to reduce the total time spent and the total emissions in a balanced way. In particular, the ramp metering and route guidance controllers are feedback predictive controllers, i.e. they compute the control actions not only on the basis of the measured system state, but also on the basis of the prediction of the system evolution, in terms of traffic conditions and traffic emissions. Another important feature of the controllers is that they have a multi-class nature: different classes of vehicles are considered and specific control actions are computed for each class. Since the controllers are based on a set of parameters that need to be tuned, the overall control framework also includes a module to properly determine the gains of the controllers. The simulation analysis reported in the paper shows the effectiveness of the proposed control framework and, in particular, the possibility of implementing control policies that are specific for each vehicle type.     

兰新高速铁路综合维修天窗设置方式研究

在分析兰新高速铁路的线路、运输组织、车站、接触网、综合维修、供电制式等方面特点的基础上,研究兰新高速铁路综合维修天窗的时间需求,重点确定兰新高速铁路天窗开设方式,建议采用分段矩形天窗。并通过铺画列车运行图,分析兰新高速铁路开设分段矩形天窗对跨线旅客列车终到时间、通过能力、运行调整等方面的影响。按客流区段设置分段矩形天窗可以保证综合维修作业和行车的安全。     

Unraveling the relationship between trip chaining and mode choice: evidence from a multi-week travel diary

Abstract

Trip chaining (or tours) and mode choice are two critical factors influencing a variety of patterns of urban travel demand. This paper investigates the hierarchical relationship between these two sets of decisions including the influences of socio-demographic characteristics on them. It uses a 6-week travel diary collected in Thurgau, Switzerland, in 2003. The structural equation modeling technique is applied to identify the hierarchical relationship. Hierarchy and temporal consistency of the relationship is investigated separately for work versus non-work tours. It becomes clear that for work tours in weekdays, trip-chaining and mode choice decisions are simultaneous and remain consistent across the weeks. For non-work tours in weekdays, mode choice decisions precede trip-chaining decisions. However, for non-work tours in weekends, trip-chaining decisions precede mode choice decisions. A number of socioeconomic characteristics also play major roles in influencing the relationships. Results of the investigation challenge the traditional approach of modeling mode choice separately from activity-scheduling decisions.     

确定模糊控制最少推理规则数量的原则

提出在柴油机控制系统模糊规则的设计中 ,确定最少模糊推理规则的原则 ,指出在论域为正负偏差时 ,最小隶属函数个数是 3时仍可满足控制精度要求 ;并建立了柴油机模糊PID控制器的三维模糊数学模型 ,该模型被用于一个 4输入 3输出 (4I3O)柴油机模糊控制器的设计中。