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.     

东风牌EQ3208G型平头柴油自卸车线束图解

描述了东风牌EQ3208G型平头柴油自卸车线束的组成和布局,详细剖析了该车线束各个分支插接件和连接件的示意形状、对应电器位置及其线路的相关属性,并采用了新的线路表达方式,绘出了该车的电路原理图。     

鱼骨图视野下提高炮兵旅作战效能的F-AHP评估

在一般情况下经常用F-AHP评判进行系统效能评估,定量的说明各种因素与最终结果的因果关系。文章引入了F-D（鱼骨图）方法的思想,对传统的F-AHP评判法进行了创新与改进,在F-AHP的基础上结合了F-D方法,通过F-D方法来弥补F-AHP中的主观性,已更加准确的找出其定性问题与定量结果的关系,得出更加精确的数据,使评估更加客观的反应真实,进而确定制约作战效能的因素,提出合理的意见,并进行实例研究。     

基于大数据的车门抖动解决方案

车门抖是指车门打开的瞬间,车门长时间的抖动,衰减过程较长.车门抖动给客户带来非常差的体验,影响对车身品质的整体评价.Z177车型量产过程中,突然出现右后门开门后窗框抖动的问题,持续了一段时间,一直没有彻底解决.此问题主要来自质量考核部门质量整车考核和客户考核抱怨,认为此问题会给客户带来非常差的感官体验,形成车身结构单薄...     

三维实体有限元模型网格图的消隐问题

本文讨论三维实体有限元模型网格图的消隐问题。分析了它的数据结构、几何特征及图形表达等方面的特珠性,并对这类图形的计算机绘制计算方法作了初步探讨,提出了一些实用算法,并给出实例。      

基于眼图分析的数字滤波选取方法分析

在数字通信系统中,由于存在码间串扰而影响通信质量,如何减小码间串扰的影响是数字信号传输面临的一个问题。经过分析发现,在传输过程中选取合适的滤波器及其特征参数能够不同程度地减小码间串扰影响。通过对相同干扰条件下,数字基带经过不同的滤波器后形成的眼图进行分析,进而选取了适合传输的滤波器及其特征参数,用最佳传输滤波器的方法减小了码间串扰,从而提高了信号的传输质量。     

基于ANSYS二次开发的实体单元模型内力图的实现

当依据规范对结构承载能力极限状态和正常使用极限状态进行设计验算时,需掌握其内力状态.有限单元法对复杂结构进行内力分析有时需要采用空间实体单元,而ANSYS软件不能直接输出实体单元模型的内力图,需另行开发.文中介绍了利用软件后处理中的面操作,通过面积分和矩阵运算并编制APDL宏程序求实体单元模型内力图的方法.给出了4种不同截面形式的连续梁求内力图示例,并对实体单元模型的有限元解与采用三弯矩方程求得的理论解进行了比较.结果表明,文中所述方法可以方便地求得实体单元模型的内力图.     

客运专线列车运行图编制模型及计算方法的研究

列车运行图是铁路行车组织工作的基础,其编制问题属于超大规模的多目标优化问题,求解难度较大。既有线列车运行图较为成熟的编制理论和计算方法对客运专线列车运行图的编制具有重要的借鉴作用。在既定客运专线运输组织模式的基础上,提出基于客运专线A类本线、B类跨线和本线城际列车运行图铺划的分层叠加数学模型,研究客运专线不同种类列车的布点模型和求解方法,设计了基于改进型遗传算法的客运专线列车运行图优化策略和算法。算例表明,该算法能有效地求解客运专线列车运行图编制方案,并达到快速准确的良好效果,为编图人员提供优选方案。     

旅客列车票额分配及周转图自动处理系统的设计开发

论述旅客列车票额分配方案重要性及现状,介绍运用现代化信息技术手段实现旅客列车票额分配及周转图自动生成的设计目标、方案、系统结构及技术特点.     

Agent-based network transmission model using the properties of macroscopic fundamental diagram

The field of research that has recently come to the fore is the perimeter control, which aims to control traffic demand for a large urban area prior to controlling internal flow inside the area. Such control concept needs to be tested by simulations, hence, it is necessary to develop a model that can appropriately estimate the network-wide flow dynamics. In this paper, agent-based network transmission model (ANTM) is proposed for describing the aggregated flow dynamics over an urban area of multiple large-scale networks. The proposed model is the combination of the cell transmission model (CTM), macroscopic fundamental diagram (MFD), and agent concept. The CTM-based simulation is adopted for the simplicity considering the computation requirements for real-time feasibility. The MFD concept is applied for representing the network properties, and a new approach is taken particularly for estimating network outflow affected by both demand patterns and boundary capacity. The agent concept is applied for representing drivers’ travel behaviors. The model is compared with microscopic simulations and shows reasonable accuracy for large areas. In addition, various travel direction choice behaviors are applicable to this model. Various perimeter control policies are applicable as well, thus, the proposed model can be a useful tool for testing various control methods, in terms of reducing the congestion in urban areas.