基于滑模控制的时滞自动车辆跟随系统数学模型

基于非线性车辆动力学方程和固定车辆间距跟随策略,对具有时间滞后的自动化公路系统车辆纵向跟随控制问题进行了研究。在假定车队中的每个被控制车辆能够接收到车队领头车辆以及该车前面一个车辆的位移、速度和加速度信息的情况下,应用滑模变结构控制方法,通过对滑模运动方程的分析,得到了关于车辆间距误差的车辆纵向跟随系统的数学模型。该模型属于一类具有时间滞后的无限维非线性关联大系统。在具有时间滞后的车辆纵向跟随控制器设计中,利用该类非线性关联大系统的稳定性判定条件来设计控制参数,可确保车辆纵向跟随控制系统的稳定性。     

基于交通仿真条件下多功能车道设置的必要性分析

选取天津市快速环路的路段为仿真背景,在主线为双向6车道和8车道时,分别进行多功能车道设置的必要性分析。采用VISSIM微观仿真软件,在主路车道数相同时,将设与不设多功能车道两种情况下事故车辆每车停车时间均取为15 min,仿真每种情况在事故停车率分别为0.05%、0.1%下的通行能力及延误。通过比较设置与不设置多功能车道在车辆紧急停靠时主线的通行能力及其它车辆延误,来分析多功能车道设置的必要性。     

Flight and passenger delay assignment optimization strategies

This paper compares different optimization strategies for the minimization of flight and passenger delays at two levels: pre-tactical, with on-ground delay at origin, and tactical, with airborne delay close to the destination airport. The optimization model is based on the ground holding problem and uses various cost functions. The scenario considered takes place in a busy European airport and includes realistic values of traffic. A passenger assignment with connections at the hub is modeled. Statistical models are used for passenger and connecting passenger allocation, minimum time required for turnaround and tactical noise; whereas uncertainty is also introduced in the model for tactical noise. Performance of the various optimization processes is presented and compared to ration by schedule results.     

Strategic trade-off between vessel delay and schedule recovery: an empirical analysis of container liner shipping

In this paper, we empirically test the relationship between the delay of containerships and the scheduled operations in a terminal, based on a dataset containing information on 352 containership arrivals during a 9-month period at seven terminals of three North American ports. We find that a vessel is less likely to be delayed when there are more operations scheduled shortly (up to 3 days) after the vessel’s berthing window in the terminal. Moreover, we also find that the more containers a vessel needs to unload in the terminal, the less likely that it would be delayed. Both findings support the hypothesis that liners strategically balance the trade-off between delay cost and schedule recovery cost.     

A dispatching decision support system for countering delay propagation in intermodal logistics networks

This paper specifies a dispatching decision support system devoted to managing intermodal logistics operations while countering delay and delay propagation. When service disruptions occur within a logistics network where schedule coordination is employed, a dispatching control model determines through an optimization process whether each ready outbound vehicle should be dispatched immediately or held to wait for some late incoming vehicles. Decisions should consider potential missed-connection costs that may occur not only at the next transfer terminals but also at hubs located further downstream. Numerical examples and a sensitivity analysis with different slack time settings for attenuating delay propagation are presented.     

高铁晚点列车智能调度系统的研究与开发

为提升调度员对高铁晚点列车的调度指挥效率,研究晚点时间估算方法和晚点列车调整规则,利用雷达图和电子地图等可视化技术,开发高铁晚点列车智能调度系统,提供高铁列车运行晚点实时监控、重点监控列车晚点预警、列车晚点原因分析、调整方案协同制定等功能,具有一定程度的智能化水平,有助于减轻调度员的工作强度。目前,系统1.0版本已在中国国家铁路集团有限公司和铁路局集团公司两级单位正式启用,应用效果良好。     

基于SimEvents/Stateflow的CTCS-3级列控系统车地无线通信子系统建模与分析

根据CTCS-3级列控系统中无线通信子系统的分层结构和其具有随机性的特点,采用Matlab软件中SimEvents与Stateflow相结合的方式实现车地无线通信过程的建模与仿真,分析安全连接建立时间和不同长度无线应用消息传输延迟时间。结果表明:无线通信子系统安全连接建立时间符合《CTCS-3级列控系统GSMR网络需求规范》的要求,并且具有一定的安全余量;仿真得到不同长度的无线应用消息传输延迟时间,可为列控系统车地无线通信的实时性分析提供参考;建模方法简洁高效,模型能够较好地描述系统特性,仿真结果可为列控系统车地无线通信技术规范的完善、系统的设计与实现提供数据支持。     

CSD数据传输时延测试持续丢帧问题分析

GSM-R网络CSD传输时延测试中,常常发现持续丢帧/误帧现象,为此对问题原因、产生原理进行详细分析,在此基础上提出了测试方法的改进建议.     

QoS区分的高速移动OFDMA系统无线资源分配

针对高速移动环境下多业务多用户正交频分多址(OFDMA)系统下行链路提出一种动态资源分配方案。针对具有不同时延要求的多种类型数据包的数据流,提出了一种考虑多种时延服务质量(QoS)要求的动态资源分配算法。通过应用排队论原理,将用户的时延要求转化为速率约束,结合多普勒频移产生的中断概率的约束,形成一个高速移动环境下考虑用户不同QoS要求的最优化问题。该优化问题为混合整数非线性规划,直接求解的复杂度非常高。为了解决原问题,提出了次优方法。仿真结果表明,在高速移动环境下,提出的方法在保障用户各种QoS时延要求的同时,有效地提高了系统的容量。     

高速动车组半主动悬挂系统动力学性能仿真分析

介绍了基于天棚控制理论的半主动减振器原理,以CRH380A动车组头车为研究对象,对天棚阻尼系数和时滞对车辆动力学性能的影响进行了仿真分析.结果表明:天棚阻尼系数越大,车体横向减振性能越优,但系统允许的最大时滞减小;天棚阻尼系数的设计要同时考虑横向振动性能和系统时滞的影响.半主动控制模式比被动模式对车体横向振动的改善效果均比较明显,平均改善率超过20％.