LBC6120A82型客车底盘冷却系统的设计

介绍LBC6120A82型客车底盘液压风扇冷却系统的组成、原理及主要特点。     

河谷型城市公交线网特征与规划

本文针对我国河谷型城市在现有公交线网规划中存在的诸多问题,从河谷型城市的定义与特征入手,分析了河谷型城市公交线网的特征和存在的问题,就河谷型城市公交起讫点和换乘枢纽的设置进行了研究,阐述了几种相应的布局模式各自的优缺点及适应条件。通过对河谷型城市所具备特点的综合分析,并结合现有的交通方式,提出了适合我国河谷型城市公共交通发展的规划模式,从多方面对河谷型城市公共交通规划提出了改进意见,对河谷型城市公交线网规划具有一定的指导作用。     

并联式混合动力客车传动系设计与仿真

对混合动力客车（HEB）的传动系种类进行分析与探讨,设计某种并联式HEB的传动系,在MATLAB／SIMLINK仿真环境下,在满足车辆动力性要求的前提下,利用ADVISOR软件,以燃油经济性为主要目标,确定传动系主要部件的具体参数,并与纯内燃机客车的仿真进行比较分析。     

Development of the Inner Spherical CVT for a motorcycle

An Inner Spherical CVT (ISCVT) transfers engine power by utilizing the traction force of the lubricant fluid film on the contact point between concave and convex spherical rolling bodies. Since the concave and the convex contact surfaces of the ISCVT are exactly spherical parts, they have a large circular (not elliptic) contact area, and the ISCVT mechanism has a larger torque capacity, less spin loss, and better stability than other traction drive mechanisms. The IVT (Infinitely Variable Transmission) performances also can easily be embodied in the ISCVT. In this work, we developed a prototype of the ISCVT for a motorcycle with a 125cc single cylinder engine having a maximum torque of 13.73 Nm at 8,000 rpm. The design parameters were determined, and the transmission performances were evaluated by optimal design procedure. The transmission efficiency, the life time, the maximum severe stresses on each part of the ISCVT, and the work needed for varying speed ratio were theoretically investigated, and the efficiency performances were experimentally measured. The manufactured prototype was installed in an actual motorcycle, which was fixed on the test-bench equipped with a dynamometer. The parasitic loss of the prototype and the cross-sectional road load performance were tested. The power efficiency of the simulated prototype was between 87∼92%, and the life span was more than 50,000 hours. The tested overall power efficiency was around 70∼92% under frequent driving conditions, which is an impressive performance in a motorcycle transmission despite the small difference from the simulation.     

Development of a corrected average speed model for calculating carbon dioxide emissions per link unit on urban roads

The purpose of our study is to develop a “corrected average emission model,” i.e., an improved average speed model that accurately calculates CO₂ emissions on the road. When emissions from the central roads of a city are calculated, the existing average speed model only reflects the driving behavior of a vehicle that accelerates and decelerates due to signals and traffic. Therefore, we verified the accuracy of the average speed model, analyzed the causes of errors based on the instantaneous model utilizing second-by-second data from driving in a city center, and then developed a corrected model that can improve the accuracy. We collected GPS data from probe vehicles, and calculated and analyzed the average emissions and instantaneous emissions per link unit. Our results showed that the average speed model underestimated CO₂ emissions with an increase in acceleration and idle time for a speed range of 20 km/h and below, which is the speed range for traffic congestion. Based on these results, we analyzed the relationship between average emissions and instantaneous emissions according to the average speed per link unit, and we developed a model that performed better with an improved accuracy of calculated CO₂ emissions for 20 km/h and below.     

Spatiotemporal evolution of China’s railway network in the 20th century: An accessibility approach

The interrelatedness of transportation development and economic growth has been a constant theme of geographic inquiries, particularly in economic and transportation geography. This paper analyzes the expansion of China’s railway network, the evolution of its spatial accessibility, and the impacts on economic growth and urban systems over a time span of about one century (1906–2000). First, major historical events and policies and their effects on railway development in China are reviewed and grouped into four major eras: preliminary construction, network skeleton, corridor building, and deep intensification. All four eras followed a path of “inland expansion.” Second, spatial distribution of accessibility and its evolution are analyzed. The spatial structure of China’s railway network is characterized by “concentric rings” with its major axis in North China and the most accessible city gradually migrating from Tianjin to Zhengzhou. Finally, the study indicates that railway network expansion has significantly improved economic development and heavily influenced the formation of urban systems in China.     

Telecommuting and urban sprawl

This study examines what happens to city size when telecommuting occurs. It assumes that more telecommuting occurs when telecommuters’ labor cost share increases and/or workers adopt a more favorable attitude toward working from home. The study shows that telecommuting produces opposing forces that regulate the city size, one centralizing and the other decentralizing urban activities. These forces are examined in a city where workers and firms are given the option to freely mix working at the office and at home, and the city’s land use is endogenously determined. A rise in the productivity of an economy due to telecommunications technology could work to centralize urban activities, while urban contraction can occur with a fixed city population.     

城市快速路交通流特性研究

本文利用我国城市快速路交通信息采集系统的实时交通检测数据,对城市快速路交通流的动态特性进行了分析;对比了多车道交通流量、密度、速度的横向分布差异;最后比选了适用于城市快速路的稳态交通流模型,并标定了模型参数,本文的研究成果将对城市快速路的规划、设计、运营、管理和评价提供科学依据和数据支持．     

道路检查井盖对行车的影响及预警方法

简要介绍了检查井病害的成因。从驾驶的舒适性和安全性方面,分析了城市道路检查井盖对行车的影响,并提出了新的预警方法。     

城市轨道交通快慢车运营模式综合评价体系研究

为满足长途客流的快速直达需求,我国城市轨道交通已经开始快慢车混跑运营模式的尝试。而快慢车运营模式,与传统的轨道交通系统相比具有其显著的特点,需建立一套比较客观、科学的评价体系对拟采用的快慢车运营模式进行客观、中肯地评估,以判定其运营效果,为前期项目决策提供依据。根据快慢车运营模式的特点,提出4个主要影响因素,包括对车站投资、车辆相关投资、运营能耗、出行时间的影响,并运用层次分析法建立快慢车运营模式综合评价指标体系,最终确定快慢车运营模式综合评价值。若快慢车运营模式综合评价值大于零,则说明快慢车运营模式社会效益良好,若快慢车运营模式综合评价值小于等于零,则说明需进一步采取措施优化方案,重新进行项目运营模式论证。