城市交通运行状况对机动车碳排放的影响研究

为定量分析不同城市交通运行状况对机动车碳排放的影响，利用高德平台提供的拥堵延时指数(Congestion Delay Index, CDI)数据，在分析我国交通拥堵城市时空分布特征以及CDI特征的基础上，通过构建基于速度的CO2排放因子，利用VISSIM模拟不同交通运行状况时的交通量， 实现不同交通运行状况下机动车碳排放的估算。结果显示：交通拥堵城市分布具有空间依赖性和聚集性，在长三角经济区和珠三角经济区形成两个高聚集中心；CDI具有明显的周期性(7 d)波动规律，且受天气和人类活动等的影响较大，疫情打破了此规律；城市交通运行状况(CDI)对机动车CO2排放有较大的影响，当交通处于轻度拥堵时(CDI为1.582)，交通高峰期我国城市机动车年排放的CO2总量约为0.77亿 t，是畅通状态下的4.51倍；当交通保持基本畅通时(CDI为1.35)，交通高峰期我国城市机动车CO2年排放总量可减少0.29亿 t；当交通达到中度拥堵时(CDI为1.909)，交 通高峰期我国城市机动车CO2的年排放增加0.22亿 t；当处于交通严重拥堵时(CDI达2.394)，交通高峰期我国城市机动车CO2的年排放总量可达1.33亿 t。改善城市交通运行状况，可大幅度降低机动车的CO2排放量。     

基于改进因子评点法的公交专用道服务水平分级

通过引入因子评点法及分析其原理，提出了改进的因子评点法，拓展了理论方法 的应用范围.提出以单位公交专用道延误作为评价公交专用道的服务水平分级的指标；针对 既有的上游停靠站延误估算模型，通过实际调研确定模型中解释变量的取值，从而获取容量 为15 288 的延误样本；然后基于延误样本对单位公交专用道延误进行频次分析，得到其累积 分布，采用改进的因子评点法对公交专用道服务水平进行分级.本文研究成果为公交专用道 的运营评价和规划设计提供了指导依据.     

Closing the loop in real-time railway control: Framework design and impacts on operations

Railway traffic is heavily affected by disturbances and/or disruptions, which are often cause of delays and low performance of train services. The impact and the propagation of such delays can be mitigated by relying on automatic tools for rescheduling traffic in real-time. These tools predict future track conflict based on current train information and provide suitable control measures (e.g. reordering, retiming and/or rerouting) by using advanced mathematical models. A growing literature is available on these tools, but their effects on real operations are blurry and not yet well known, due to the very scarce implementation of such systems in practice.In this paper we widen the knowledge on how automatic real-time rescheduling tools can influence train performance when interfaced with railway operations. To this purpose we build up a novel traffic control framework that couples the state-of-the art automatic rescheduling tool ROMA, with the realistic railway traffic simulation environment EGTRAIN, used as a surrogate of the real field. At regular times ROMA is fed with current traffic information measured from the field (i.e. EGTRAIN) in order to predict possible conflicts and compute (sub) optimal control measures that minimize the max consecutive delay on the network. We test the impact of the traffic control framework based on different types of interaction (i.e. open loop, multiple open loop, closed loop) between the rescheduling tool and the simulation environment as well as different combinations of parameter values (such as the rescheduling interval and prediction horizon). The influence of different traffic prediction models (assuming e.g. aggressive versus conservative driving behaviour) is also investigated together with the effects on traffic due to control delays of the dispatcher in implementing the control measures computed by the rescheduling tool.Results obtained for the Dutch railway corridor Utrecht–Den Bosch show that a closed loop interaction outperforms both the multiple open loop and the open loop approaches, especially with large control delays and limited information on train entrance delays and dwell times. A slow rescheduling frequency and a large prediction horizon improve the quality of the control measure. A limited control delay and a conservative prediction of train speed help filtering out uncertain traffic dynamics thereby increasing the effectiveness of the implemented measures.     

An analytical model to conduct a person-based evaluation of transit preferential treatments on signalized arterials

The complexities of urban transportation networks where multiple modes with different characteristics and needs travel in combination with constraints on space and funding make the sustainable management of these systems a challenge. In order to improve transit service, space (e.g., dedicated bus lanes) and time (e.g., transit signal priority strategies) Transit Preferential Treatments (TPT) are deployed to improve transit operations. The objective of this paper is to develop an analytical model that allows for a person-based evaluation of alternative TPTs when considered individually and in combination. In particular, the analytical model is developed to assess person delay and person discharge flow at any intersection that is part of a signalized arterial, where auto arrivals are in platoons. The performance of TPTs is evaluated using both the analytical model and through microsimulation tests on two intersections of San Pablo Avenue in Berkeley, CA. Space TPTs such as dedicated bus lanes and queue jumper lanes are beneficial in reducing bus person delay when provided in addition to the existing lanes; however, the effectiveness of time TPTs such as green extension depends on the level of auto demand in combination with signal settings. Changes in person discharge flow are not significant for any of the treatments tested with the exception of the bus lane substitution with and without green extension, which led to a significant decrease in person discharge flow. Increased bus frequency increases the effectiveness of transit signal priority in reducing total and bus person delay. The analytical model results produce ranking outcomes that are comparable with the microsimulation ones and therefore, the model may be used for a quantitative evaluation of TPTs without the need for data intensive and time consuming calibration efforts required for microsimulation models. The developed model can be used to guide infrastructure and investment decisions on where such TPTs should be implemented and under what conditions space TPTs should be combined with time TPTs to improve person mobility.     

快速公交专用道形式对其运行效率的影响研究

选取包含有四段不同专用道形式的济南市BRT-3线路为研究对象,通过实时采集各区段和站间的运行数据,运用数理统计方法和多元分析理论,对该线路中不同区段和站间的BRT车辆运行效率、该线路具有的车辆配置、信号配时以及道路基础条件的特点对BRT运行效率的差异性,不同区段上交叉口停车延误和停靠站延误进行对比分析.提出了实行部分交叉口有条件的BRT信号优先;优化行人街交叉口;实时调度控制车辆运行时间和距离等改进措施.     

基于Direct3D的雷达P显在通用计算机上的实现

随着电子技术和计算机技术的发展,基于计算机的多功能光栅显示器已成为雷达显示的一种趋势。多功能雷达显示器功能丰富但是运算量大,文章提出了利用Direct3D组件的强大功能驱动显示处理器（GPU）实现雷达的PPI显示。利用Direct3D灵活的坐标变换功能实现了雷达量程切换、舰首向上、偏心、空心、挖心显示功能。基于Direct3D的PPI显示可以节省大量CPU运算资源,并能取得更快的显示速度和更好的显示效果。     

基于Petri网的舰艇对空自防御作战时延仿真

以一种典型的舰艇对空自防御作战流程为例,分析其中的时延性因素,并将其划分为七类典型的时延性因素;建立基于Petri网的舰艇对空自防御流程模型,针对Petri网数值仿真模拟能力不足的问题,采用一种模拟Petri网仿真的方法,通过MATLAB进行数值仿真试验;并对作战流程中某些阶段时延长度的改变对总的作战结果的影响作了分析。     

动态输出反馈实时网络控制系统稳定性分析

研究了以实时以太网作为控制网络的系统稳定性。针对线性时不变被控对象,基于Ethernet/IP实时工业以太网,建立动态输出反馈实时网络控制系统模型,给出了系统渐进稳定的充分条件。仿真算例说明分析方法和结果是有效可行的。     

基于改进LS-SVM算法的列车通信网络时延预测方法

由于通信网络诱导时延的存在会对列车牵引制动系统造成影响,因此对时延精准预测并实现补偿十分重要。提出了一种基于改进粒子群(PSO)算法优化的最小二乘法支持向量机(LS-SVM)算法对列车通信网络时延进行预测,搭建了列车网络控制系统半实物平台,使数据通过多功能车辆总线(MVB)进行传输,分别改变车辆控制单元(VCU)特征周期及负端口数量大小,以获取大量不同特性的时延数据。将数据分组后利用改进的PSO算法优化LS-SVM算法进行预测仿真。仿真结果表明,与传统的LS-SVM算法及Elman神经网络算法的预测方法相比,所提出的方法在列车通信网络的时延预测方面具有更好的快速性和准确性。     

Arterial traffic signal optimization: A person-based approach

This paper presents a real-time signal control system that optimizes signal settings based on minimization of person delay on arterials. The system’s underlying mixed integer linear program minimizes person delay by explicitly accounting for the passenger occupancy of autos and transit vehicles. This way it can provide signal priority to transit vehicles in an efficient way even when they travel in conflicting directions. Furthermore, it recognizes the importance of schedule adherence for reliable transit operations and accounts for it by assigning an additional weighting factor on transit delays. This introduces another criterion for resolving the issue of assigning priority to conflicting transit routes. At the same time, the system maintains auto vehicle progression by introducing the appropriate delays associated with interruptions of platoons. In addition to the fact that it utilizes readily available technologies to obtain the inputs for the optimization, the system’s feasibility in real-world settings is enhanced by its low computation time. The proposed signal control system is tested on a four-intersection segment of San Pablo Avenue arterial located in Berkeley, California. The findings show the system’s capability to outperform pretimed (i.e., fixed-time) optimal signal settings by reducing total person delay. They have also demonstrated its success in reducing bus person delay by efficiently providing priority to transit vehicles even when they travel in conflicting directions.