Assessing the performance of SpeedInfo radar traffic sensors

Traffic speed is a crucial input for real-time traffic management applications. Operating agencies typically deploy their own sensors to collect the measurements, e.g., loop detectors. Recently, SpeedInfo emerged with a different paradigm for traffic speed collection: instead of selling hardware to operating agencies, at each link the company deploys its own Doppler radar in a self-contained wireless unit to measure traffic speeds and then sells the speed data. This study uses well-tuned loop detector-based speed measurements to evaluate 15 of the Doppler radar sensors over several months while the two traffic data collection systems were operating concurrently. The extended study period includes potentially challenging and transient conditions for the radar sensors: both recurrent (rush hour congestion and late night low flow) and nonrecurrent (incidents and precipitation). The analysis took a broad overview, comparing speed measurements from the radar sensors against the concurrent loop detector data and then explicitly looked for any anomalous pattern in the radar data such as latency and system outages. The work found the radar measurements are generally good, but also identified several points that should be considered before deployment, including latency, different biases in free flow and congestion, vulnerability to precipitation, and sensitivity to mounting angle.     

列车运行自动调整研究回顾与展望

描述列车运行自动调整问题,回顾国内外研究进展,分析该技术的应用现状,并展望该技术未来发展的若干方向。     

浅谈目标管理在汽运企业的应用

从制定科学的目标管理体系、建立完整的目标控制系统、采取有效的保证措施等几个方面阐述了目标管理方法在汽运企业的应用。     

TRANSVAGINAL COLOR DOPPLER STUDY OF UTEROPLACENTAL CIRCULATION IN NORMAL EARLY PREGNANCY

Ｔｈｅｐｈｙｓｉｏｌｏｇｉｃａｌｃｈａｎｇｅｓｏｆｕｔｅｒｉｎｅｈｅｍｏｄｙｎａｍｉｃｓｉｓｅｓｓｅｎｔｉａｌｆｏｒｃｌｉｎｉｃａｌｅｖａｌｕａｔｉｏｎｏｆｔｈｅｓｔａｔｕｓｏｆｔｈｅｕｔｅｒｉｎｅｃｉｒｃｕｌａｔｉｏｎ．Ｔｈｅｆｉｒｓｔｓｔｕｄｉｅｓｏｆｅａｒｌｙｕｔｅｒｏｐｌａｃｅｎｔａｌｂｌｏｏｄｆｌｏｗｗｅｒｅｃａｒｒｉｅｄｏｕｔｉｎｖｉｔｒｏｏｎａｂｏｒｔｉｏｎｔｉｓｓｕｅａｎｄｗｅｒｅｍａｉｎｌｙｒｅｓｔｒｉｃｔｅｄｔｏａｎａｔｏｍｉｃａｌｉｎｖｅｓｔｉｇａｔｉｏｎｏｆｔｈｅｕｔｅｒ…     

汽车转向泵恒流量控制的计算分析

通过模拟汽车转向泵恒流量控制的工作原理，给出合理的流量控制过程的理论分析方法，并计算分析转向泵的流量控制特性，确定其影响因素，同时也分析了令很多工程技术人员费解的两个流量控制现象。     

Trip Chain's Activity Type Recognition Based on Support Vector Machine

This paper focuses on support vector machine (SVM) based trip chain's activity type recognition. First, the time-series location information of person trip is processed to obtain the trip chain elements including moving processes and activities, and the activity options are extracted from the geographic information system (GIS) around the activity sites. Second, the activity features are drawn from spatio-temporal factors of trip chain to serve as the input feature vector of classifier. A SVM based one-to-one classifier is established and the method of one-to-one classifier voting is adopted to decide the most likely activity type from the activity options. Finally, the classifiers are trained with simulation data based on the Gaussian radial basis (RBF) kernel function and the multilayer perception (MLP) kernel function respectively, and then examined by cross validation. The result shows that in the one-to-one classifying scheme, the highest and lowest right recognition rate with RBF are 99% and 62%, and the corresponding results with MLP are 97% and 54%, respectively.     

混合交通流参数之间关系模型标定

提出了混合交通流参数之间关系模型的标定和超车换道率的计算方法,采用广深高速公路、广佛高速公路和沪宁高速公路的实测数据对模型进行了验证,并计算了各数据点的超车换道率.结果表明,流量、密度数据的相关系数都接近1,超车换道率介于-1和1之间.     

有效利用广播媒体 合理诱导社会车流

随着北京市机动车数量的激增,交通拥堵问题日趋严重,广播媒体在交通诱导中的作用越来越突出。基于多年的工作实践,浅谈了利用广播媒体进行交通信息发布和交通诱导的工作体会,希望能进一步加强广播媒体诱导交通的作用,实现交通诱导的主动性。     

Multimodal,multiclass stochastic dynamic traffic assignment for evaluating information provision strategies

A multimodal, multiclass stochastic dynamic traffic assignment model was developed to evaluate pre‐trip and enroute travel information provision strategies. Three different information strategies were examined: user optimum [UO], system optimum [SO] and mixed optimum [MO]. These information provision strategies were analyzed based on the levels of traffic congestion and market penetration rate for the information equipment. Only two modes, bus and car, were used for evaluating and calculating the modal split ratio. Several scenarios were analyzed using day‐to‐day and within day dynamic models. From the results analyzed, it was found that when a traffic manager provides information for drivers using the UO strategy and drivers follow the provided information absolutely, the total travel time may increases over the case with no information. Such worsening occurs when drivers switch their routes and face traffic congestion on the alternative route. This phenomenon is the 'Braess Paradox'.     

基于用户平衡分析的铁路旅客列车票额分配计划制定及评价方法

票额分配计划必须最大限度地满足旅客集体乘车选择行为下长途旅客的出行需求,其中的旅客集体乘车选择行为表现为基于客车开行方案的换乘网络上的用户平衡态,据此平衡态提出以直接人公里数最大为目标的票额分配计划制定方法。进而根据短途套用、票额共用和席位复用等售票策略、以及这些策略对旅客集体乘车选择行为的影响,设计基于票额分配计划的换乘网络,依据该换乘网络上的用户平衡态,提出以旅客出行费用和票额分配计划的直接人公里数两项指标组成的评价方法。通过算例展示了票额分配计划的制定过程,并对不同票额分配计划进行了评价分析。