国外典型大城市市郊轨道交通的发展及其启示

介绍了纽约、柏林、巴黎、伦敦和东京5个城市的市郊轨道交通的线网特征(线网发展、线网特点、车辆运用及供电技术),以及线网运营以及线网客流等发展情况,从中找出发展规律和可借鉴的经验.在此基础上,针对我国市郊轨道交通发展面临的问题,建议:重视市郊轨道交通的发展,提前做好规划;市郊轨道交通车站应根据沿线客流的需求布设,运营组织应有较大的灵活性,以提高运营效率;由于郊区的建筑密度较低,存在设置较高电压线的防护空间,应尽可能采用城市铁路系统制式.     

浦东铁路开行市郊列车的客流需求研究

讨论了浦东铁路开行市郊列车的客流需求预测问题,为浦东铁路是否开行市郊列车、如何开行市郊列车方案提供依据.通过对浦东铁路沿线的居民出行调查得到浦东铁路的站间客流分布现状;在此基础上,利用沿线土地和人口发展规划.建立方式划分模型对未来5年及10年的市郊铁路客流进行预测;分析了市郊列车起终点站、发车频率、行车组织、交通衔接等因素对客流预测结果的影响.     

城市轨道交通车站客流安全检测与应急管理系统

围绕为城市轨道交通车站安全应急管理决策提供技术支持的核心目标,设计和研发面向车站管理人员的城市轨道交通车站客流安全检测系统;深入研究建设和实现系统的相关集成技术及关键保障技术,有效实现客流安全问题的实时自动发现、人工确认,以及应急预案启动、预案实施效果实时跟踪及过程控制,以保障城市轨道交通车站安全事件处理的实时高效性,提高城市轨道交通车站安全管理水平.     

Comparison of HC species from diesel combustion modes and characterization of a heat-up doc formulation

This study summarizes engine speed and load effects on HC species emissions from premixed charge compression ignition (PCI) and conventional diesel combustion, and it evaluates diesel oxidation catalyst (DOC) formulations on a gas flow reactor for the purpose of diesel particulate filter regeneration or lean NO_x trap desulfation. HC emissions are sampled simultaneously by a Tedlar bag for light HC species and by a Tenax TA™ adsorption trap for semi-volatile HC species, and they are analyzed by gas chromatography with a flame ionization detector. The bulk temperature and residence time during combustion are key parameters that are important for understanding the effects of speed and load on engine-out HC emissions. The degree of post-flame oxidation is higher in PCI than in conventional combustion, and it is increased for PCI with a higher speed and load, as indicated by a lower fuel alkanes/THC ratio, a higher alkenes/fuel alkanes ratio, and a higher methane/THC ratio. Ethene and n-undecane are two representative HC species, and they are used as a surrogate mixture in the gas flow reactor to simulate PCI and conventional combustion with in-cylinder post fuel injection. Among the three DOC formulations tested, the catalyst with constituent precious metals of platinum and palladium (PtPd) showed the best light-off performance, followed by PtPd with an addition of cerium dioxide (PtPd+CeO₂), and platinum (Pt), regardless of exhaust compositions. Conventional combustion exhaust composition shows a lower light-off temperature than that of PCI, regardless of catalyst formulation.     

Desired yaw rate and steering control method during cornering for a six-wheeled vehicle

This paper proposes a steering control method based on optimal control theory to improve the maneuverability of a six-wheeled vehicle during cornering. The six-wheeled vehicle is believed to have better performance than a four-wheeled vehicle in terms of its capability for crossing obstacles, off-road maneuvering and fail-safe handling when one or two of the tires are punctured. Although many methods to improve the four-wheeled vehicle’s lateral stability have been studied and developed, there have only been a few studies on the six-wheeled vehicle’s lateral stability. Some studies of the six-wheeled vehicle have been reported recently, but they are related to the desired yaw rate of a four-wheeled vehicle to control the six-wheeled vehicle’s maneuvering during corning. In this paper, the sideslip angle and yaw rate are controlled to improve the maneuverability during cornering by independent control of the steering angles of the six wheels. The desired yaw rate that is suitable for a six-wheeled vehicle is proposed as a control target. In addition, a scaled-down vehicle with six drive motors and six steering motors that can be controlled independently is designed. The performance of the proposed control methods is verified using a full model vehicle simulation and scaled-down vehicle experiment.     

信号交叉口右转机动车与行人和非机动车冲突研究

研究的主要内容为:未设置右转专用相位的信号灯控制道路交叉口右转机动车流与行人和非机动车的冲突行为,包括冲突数据的采集和提取、右转车流受到干扰前后速度与过街时间对比分析以及机非冲突速度-距离模型。以现实交通数据为基础,通过软件提取右转机动车与行人和非机动车冲突数据,建立标准统一的冲突数据库,以此为基础对比分析右转车流正常行驶状态和受到干扰情况下通过道路交叉口时的车速和过街时间,并建立右转车辆距离机非冲突点不同位置时所对应不同速度的统计模型。研究结果对右转专用相位设立标准的建立和相应信号配时方案的设计具有一定的工程指导意义。     

公路施工企业现金流的风险与防范

文章通过对公路施工企业容易出现的现金流风险种类及成因进行分析,提出了一些有效的现金流风险防范措施,避免企业出现现金流风险而导致破产。     

Real-time freeway traffic state estimation based on extended Kalman filter: Adaptive capabilities and real data testing

This paper reports on real data testing of a real-time freeway traffic state estimator, with a particular focus on its adaptive capabilities. The pursued general approach to the real-time adaptive estimation of complete traffic state in freeway stretches or networks is based on stochastic macroscopic traffic flow modeling and extended Kalman filtering. One major innovative feature of the traffic state estimator is the online joint estimation of important model parameters (free speed, critical density, and capacity) and traffic flow variables (flows, mean speeds, and densities), which leads to three significant advantages of the estimator: (1) avoidance of prior model calibration; (2) automatic adaptation to changing external conditions (e.g. weather and lighting conditions, traffic composition, control measures); (3) enabling of incident alarms. These three advantages are demonstrated via suitable real data testing. The achieved testing results are satisfactory and promising for subsequent applications.     

超低频接收信号降噪研究

在建立超低频接收信号模型的基础上,对超低频接收信号误码率性能进行了分析。将小波降噪算法应用于超低频噪声处理中,通过Monte Carlo计算机仿真试验,对基于小波降噪和传统数字滤波的方法对模拟的超低频接收信号进行噪声处理,并对降噪后的误码率性能进行分析,结果表明,应用小波降噪的方法对超低频接收信号进行非线性噪声处理,比传统数字滤波的方法能带来更高的信噪比增益。     

Case Analysis on Vehicle Parking and Departure Plans for the National Stadium

As the main venue of the 2008 Beijing Olympic Games, the National Stadium hosted the opening and closing ceremonies, field and track events, and final football games. This paper intends to study the problems associated with vehicle evacuation from the parking lot, and develop evacuation plans. First, the paper analyzes the particular conditions of the parking lot in the National Stadium, as well as its layout and vehicle evacuation. Then, it simulates and evaluates the evacuation plans with the suitably given parameters, based on the real blueprint of the National Stadium and scenarios. Finally, it conducts a comparative analysis on the accuracy and practicability of the vehicle evacuation plans based on the field data collected at the opening ceremony of the Olympic Games. The simulation result shows that the total vehicle evacuation time was 26 minutes and the real evacuation time was 27 minutes on the day of the opening ceremony, which verifies that the study is accurate and practical.