高速公路与地面道路衔接部交通安全改善研究

高速公路出口匝道与地面道路衔接部是高速公路与地面道路交通流转换的枢纽,交通流溢出现象时有发生,是交通事故的频发区域之一,研究其交通安全改善的方法,对提高高速公路交通安全状况和整体效益的发挥具有重要的意义.本文在分析国内外出口匝道与地面道路衔接部研究的基础上,提出了衔接部的交通安全改善方法,从影响范围的界定、交通安全诊断...     

基于海底接驳盒的电能管理系统的研制

研制了一套基于海底观测网络接驳盒的电能管理系统,实现对海底接驳盒的电能分配和管理,可以控制外接负载的电能供给,能够对各路电压、电流,控制腔、高压电源腔的温度和漏水情况进行实时监控和异常处理,并将监测数据通过网络上传到基站上位机,实现了基站上位机对系统的远程控制和管理.系统灵活、可靠、响应快,为海底观测网的长期稳定运行提供了重要保障.     

变高式导堤和导流墩在峡谷枢纽船闸下引航道中的应用

以广西黔江大藤峡枢纽所处峡谷段为例,通过改变导堤和导流墩的高度,采用变高式导堤和淹没式导流墩布置,配合调整洪水航线,解决了中枯水期航道的碍航问题,同时改善了洪水期航道通航水流条件和河道泄洪条件。     

湘江土谷塘航电枢纽工程船舶进出闸方式研究

结合枢纽整体水工物理模型试验、船模试验结果,针对"曲进直出"和"直进曲出"两种方案,从口门区通航条件、船舶过闸效率、枢纽湘江大桥的跨径布置、预留二线船闸的施工影响和对枢纽泄流能力的影响等方面对土谷塘航电枢纽工程船舶进出闸方式进行了对比分析,为最终确定船舶进出闸方式提供了依据。     

大众AJR发动机电路图解读

大众车系电路图,绘制独特,内容详细,对检修工作有重要的指导意义。本文以大众AJR发动机电路图为例进行分析、解读,有助于对全车电路图的掌握和使用。     

中央电气接线盒的通用性设计

中央电气接线盒作为汽车整车电源分配及信号传输的中枢单元,由于跟整车各用电器都相关,一般很难做到通用性设计。本文通过分析整车电源分配,总结出一般规律,设计出一种通用化的中央电气接线盒。     

电缆接续引起的信号故障分析

ZPW-2000系列移频自动闭塞设备电缆接续广泛使用免维护型地下电缆接续盒,结合现场电缆接续问题引起的事故,说明信号免维护地下电缆接续盒使用中注意问题。     

广东东莞西部干道立交设计方案

随着广东省东莞市各级公路及市政道路的发展及完善,公路与市政道路间的交叉日益增多,交叉形式多样化。为更好解决道路交叉问题,以西部干道立交为例,从地形、地物、地质、规划等角度考虑,通过工程设计实例,为类似互通立交设计提供实践经验。     

船用太阳能光伏接线盒设计

本文主要论述了太阳能在船舶中的应用及船用光伏系统,光伏系统可将太阳的光能直接转换成电能供船舶和其设备加以利用,而光伏接线盒是光伏系统电能的传输的必备件之一,作为光伏电池的电力传输和性能保障部分,接线盒的设计尤为重要,它影响着整个光伏组件的电力效率,加上船用太阳能光伏接线盒所处的海洋海洋环境极为苛刻,含有大量的盐分、水气及酸碱性物质,所以光伏接线盒设计必须根据船舶设备的特点,充分其考虑机械性能,电气性能和环境性能.     

A kinematic wave approach to traffic statics and dynamics in a double-ring network

Recently there has been much interest in understanding macroscopic fundamental diagrams of stationary road networks. However, there lacks a systematic method to define and solve stationary states in a road network with complex junctions. In this study we propose a kinematic wave approach to defining, analyzing, and simulating static and dynamic traffic characteristics in a network of two ring roads connected by a 2 × 2 junction, which can be either an uninterrupted interchange or a signalized intersection. This study is enabled by recently developed macroscopic junction models of general junctions. With a junction model based on fair merging and first-in-first-out diverging rules, we first define and solve stationary states and then derive the macroscopic fundamental diagram (MFD) of a stationary uninterrupted network. We conclude that the flow-density relationship of the uninterrupted double-ring network is not unique for high average network densities (i.e., when one ring becomes congested) and unveil the existence of infinitely many stationary states that can arise with a zero-speed shockwave. From simulation results with a corresponding Cell Transmission Model, we verify that all stationary states in the MFD are stable and can be reached, but show that randomness in the retaining ratio of each ring drives the network to more symmetric traffic patterns and higher flow-rates. Furthermore we model a signalized intersection as two alternate diverge junctions and demonstrate that the signalized double-ring network can reach asymptotically periodic traffic patterns, which are therefore defined as “stationary” states in signalized networks. With simulations we show that the flow-density relation is well defined in such “stationary” states, and asymptotic traffic patterns can be impacted by signal cycle lengths and retaining ratios. But compared with uninterrupted interchanges, signalized intersections lead to more asymmetric traffic patterns, lower flow-rates, and even gridlocks when the average density is higher than half of the jam density. The results are consistent between this study and existing studies, but the network kinematic wave model, with appropriate junction models, is mathematically tractable and physically meaningful. It has offered a more complete picture regarding the number and type of stationary states, their stability, and MFD in freeway and signalized networks.