道路行车系统中人的可靠性研究

随着人-车-路-环境系统复杂性的增加和交通事故数量的上升,新型交通设备对其使用者的素质与适应性提出了全面的要求,要提高道路行车系统的整体可靠性,必须对人的可靠性进行分析研究.从人的生理、心理、教育训练、驾车技能等因素对驾驶员可靠性的相关影响进行了探讨.分析了影响驾驶员的可靠性因素,研究了驾驶员的可靠性模型,提出建立有助于驾驶员可靠性分析研究的综合数据库,最后从理论上分析总结了提高驾驶员可靠性的措施从而得出提高道路行车安全的有效途径.     

轨道结构随机场模型与车辆-轨道耦合随机动力分析

将轨道结构视为一个参数随机系统,提出并建立了轨道结构的随机场模型.利用车辆-轨道耦合动力学的基本方法,将轨道系统有限单元模型与多刚体车辆模型相结合,建立了考虑铁路线路参数空-时随机变化的车辆-轨道动力计算模型.算例表明:所提出的方法较为可靠且高效;线路参数随机性对车辆-轨道系统的动力响应有明显的影响,随线路参数离散程度的增加,可能造成行车不安全、轨道损伤加剧等一些问题.     

自抗扰无人车纵向编队跟踪控制

针对空气阻力,非线性摩擦以及外部干扰等无法精确建模的复杂不确定性因素对无人车纵向编队跟踪控制的不利影响,为提升控制精度和收敛速度,文章提出了基于前车与自身状态信息的自抗扰无人车纵向编队跟踪控制设计方法.文章通过构造扩张状态观测器在线估计由前车与当前车辆系统内部未建模动态以及外部干扰等不确定性因素构成的总扰动,并在反馈控...     

多变点检验及在城市轨道交通中的应用

运用FDR-SMUCE方法对城市轨道交通进行多变点检验,通过模拟阶梯状高斯分布的多变点数据,对比不同α值下的两种不同σ取值方法的优劣,最终选取中位数极差方法来确定σ估计量,并将其应用到行人流交通领域,采用Kolmogorov-Smirnov(K-S)拟合检验,验证了上海地铁一号线人民广场站进出闸机口的行人数据服从对数正态分布,为保证其正态性质,将其进行对数化处理,并分别对进出闸机口行人数据进行了FDR-SMUCE的多变点检验,找出了地铁进出闸机口的行人变化规律及客流高峰时段.     

突发事件条件下列车运行k-最短路模糊蚁群算法

突发事件造成铁路线路区间的通过能力受损,在成网条件下,铁路行车调度指挥工作客观上需要搜索列车运行k-最短路。根据突发事件的影响程度设定区间距离的事故等级系数,针对突发事件的模糊性定义了模糊隶属度函数,得到了突发事件条件下模糊区间距离;考虑列车模糊停站时分对运行径路的影响,将列车的模糊停站时分转化为广义距离;将模糊区间距离与广义距离应用到突发事件条件下铁路路网构建中,很好地处理了突发事件条件下路网信息的不确定性问题。在应用蚁群算法求解最短路径的基础上,引入了C-enough概念,将其应用于搜索突发事件条件下k-最短路径问题中。以我国部分路网为例,与传统的Dijkstra算法对比验证了模糊蚁群算法的高效性和实用性,可为列车运行调度指挥提供一定的借鉴。     

基于灰色马尔科夫模型的陕西省铁路客运量预测

随着我国高铁客运的快速发展,从铁路客运历史趋势中探寻规律、把握铁路客运发展趋势,旨在对中国铁路公司及相关企业的决策提供科学依据.基于2005-2016年陕西省铁路客运量数据,在灰色GM(1,1)模型预测的基础上,运用马尔科夫过程对预测值进行修正,并对2017-2022年陕西省铁路客运量进行预测.结果表明:经过马尔科夫过程修正的灰色预测模型平均绝对误差由原来的4.64%降低到2.94%,预测效果明显.经检验,灰色马尔科夫模型的精度等级为一级,说明了方法对陕西省铁路客运量预测的有效性.     

公共交通调度实时发快车模型研究

在公共交通运行中 ,实时发快车模型是经常使用的一种调度控制手段 ,实时发快车模型旨在决定哪些车辆应打破计划实施发快车调度 ,对实施发快车调度的车辆应有多少车站被实施不停车策略以使乘客的总费用最小 .论文详细分析了行车间隔、车辆在站间的行驶时间、乘客候车时间之间的关系 ,通过使乘客的候车时间最小来建立实时发快车模型     

考虑可靠性的无车承运平台信息共享价值研究

实际承运人服务能力信息可靠性是无车承运平台商业模式开发的重要支撑,为了降低平台由于服务能力信息失真造成的货物承运、物流金融等领域的利益受损,从定量化角度重新界定实际承运人的服务能力,建立基于服务能力信息可靠性的信息共享价值模型.通过对模型的求解、分析及数值仿真,发现:实际承运人信息共享的意愿与其自身共享信息的成本以及无车承运人的激励机制有关,可靠性与自身资源条件、承诺兑现能力、补救服务能力的努力水平,无车承运人将信息转化为收益的能力、利润呈正相关,与服务能力努力水平的成本系数,收益共享比例呈负相关.     

区域经济均衡发展中铁路投资对策研究

铁路对经济的发展意义非凡,国家十分重视铁路行业的发展如何加快并保障我国铁路事业均衡、快速、可持续发展已引起人们的普遍关注.利用VAR模型研究铁路里程与经济发展的关系,可知铁路里程与经济发展互为格兰杰原因.文章利用一元二次回归模型,对1986-2015年全国平均铁路里程和云南平均铁路营运里程进行建模分析并预测.分析预测数据,若云南省计划于2030前达到全国平均水平,需要增加修建铁路2688KM,需要中央在原投资的基础上每年增加转移支付90亿元.     

带缓冲库存的物流直通配送运作时间优化

针对直通配送需要尽可能缩短配送中心内运作时间的问题.利用总运作时间与完成所有操作所需时间最长的出站口的操作时间等价的关系,构建了以最小化总运作时间为目标的进出车辆分配问题模型,同时解决了进出车辆的分配问题和分配到同一进(出)站口的车辆的排序问题.利用遗传算法进行实验,结果表明模型能够对配送中心内的运作时间进行有效优化,且在时间优化方面,与以最小化配送中心内搬运工具移动距离为目标相比更为有效.     

The Geometry of Railway Geometric Overthrow Revisited Using Computer Algebra Methods

There are size standards for railway coaches and freight wagons in order to allow trains to pass from one railway line or even network to another. The maximum size and shape of the rolling stock is denoted gauge. On curves, vehicles sweep a larger path than on straight track. We shall focus on the geometric overthrow of the different kind of rolling stock (the geometric overthrow is that part of the vehicle element offset which is due to the track curve). We shall detail the influence of the kind of vehicle (two axles, classic bogies, shared bogies or Talgo vehicles) in the geometric overthrow. The computations can be easily carried out with a computer algebra system such as Maple and some curious results are obtained (for instance, a negative value (!) is obtained for Talgo coaches).     

Branch-and-Price for a European variant of the Railroad Blocking Problem

In wagonload traffic, a production form in railway freight traffic, small groups of wagons have to be transported. In order to decrease transportation costs, wagons from different relations are consolidated. In railyards trains can be separated and rearranged to new trains. The costs arising from this process, which is called reclassification, must be balanced with the transportation costs. The minimization of total costs can be formulated as a network optimization model. We introduce a branch-and-price approach for the considered problem. Moreover, we present specialized cuts, which can be incorporated into the branching scheme. Solutions obtained from our implementation can keep up with results computed by CPLEX.     

The empty wagons adjustment algorithm of Chinese heavy-haul railway

The paper studied the problem of empty wagons adjustment of Chinese heavy-haul railway. Firstly, based on the existing study of the empty wagons adjustment of heavy-haul railway in the world, Chinese heavy-haul railway was analyzed, especially the mode of transportation organization and characteristics of empty wagons adjustment. Secondly, the optimization model was set up to solve the empty wagons adjustment of heavy-haul railway and the model took the minimum idling period as the function goal. Finally, through application and solution of one case, validity and practicability of model and algorithm had been proved. So, the model could offer decision support to transport enterprises on adjusting empty wagons.     

Control Strategy for Dispatching Multi-load Automated Guided Vehicles in a Deadlock-Free Environment

The issue of avoiding deadlocks in unmanned automated manufacturing systems with automated guided vehicle systems is addressed in this paper. In the automated guided vehicle systems, multi-load vehicles are used. A simple and easily adoptable deadlock-free real-time vehicle control strategy is developed for this type of vehicle, by using an intelligent rule-based method. The proposed strategy uses the global information and current states of the system to control the resource allocation. Based on the proposed strategy, the system resource can be appropriately allocated and utilized efficiently. A hypothetical system is built to investigate the performance of the proposed vehicle control strategy and to discuss the interactions between the fleet size, queuing capacity, and vehicle loading capacity by computer simulation tool.     

The single vehicle routing problem with toll-by-weight scheme: A branch-and-bound approach

Expressways in China make use of the toll-by-weight scheme, in which expressway tolls are collected based on the weight and traveling distance of the vehicle. Most vehicle routing models assume that the cost of traversing each edge is equivalent to edge length or some constant; as a result, such models cannot be practically applied to the Chinese expressway transportation system. This study addresses a new single vehicle routing problem that takes the vehicle’s (laden and unladen) weight into account. To solve this problem exactly, we provide a branch-and-bound algorithm with a provably valid lower bound measure, along with five dominance checkers for additional pruning. We analyze our algorithm using instances generated from standard TSP test cases, as well as two new sets of test cases based on real expressway information from the Gansu and Jiangxi provinces in China. The algorithm can be applied to any toll scheme in which the toll per unit distance monotonically increases with weight, even if the toll function is non-linear.     

The multi-commodity one-to-one pickup-and-delivery traveling salesman problem

This paper concerns a generalization of the traveling salesman problem (TSP) called multi-commodity one-to-one pickup-and-delivery traveling salesman problem (m-PDTSP) in which cities correspond to customers providing or requiring known amounts of m different commodities, and the vehicle has a given upper-limit capacity. Each commodity has exactly one origin and one destination, and the vehicle must visit each customer exactly once. The problem can also be defined as the capacitated version of the classical TSP with precedence constraints. This paper presents two mixed integer linear programming models, and describes a decomposition technique for each model to find the optimal solution. Computational experiments on instances from the literature and randomly generated compare the techniques and show the effectiveness of our implementation.     

Evolutionary Algorithms for the Vehicle Routing Problem with Time Windows

This paper surveys the research on evolutionary algorithms for the Vehicle Routing Problem with Time Windows (VRPTW). The VRPTW can be described as the problem of designing least cost routes from a single depot to a set of geographically scattered points. The routes must be designed in such a way that each point is visited only once by exactly one vehicle within a given time interval. All routes start and end at the depot, and the total demands of all points on one particular route must not exceed the capacity of the vehicle. The main types of evolutionary algorithms for the VRPTW are genetic algorithms and evolution strategies. In addition to describing the basic features of each method, experimental results for the benchmark test problems of Solomon (1987) and Gehring and Homberger (1999) are presented and analyzed.     

Polyhedral study of the capacitated vehicle routing problem

The capacitated vehicle routing problem (CVRP) considered in this paper occurs when goods must be delivered from a central depot to clients with known demands, usingk vehicles of fixed capacity. Each client must be assigned to exactly one of the vehicles. The set of clients assigned to each vehicle must satisfy the capacity constraint. The goal is to minimize the total distance traveled. When the capacity of the vehicles is large enough, this problem reduces to the famous traveling salesman problem (TSP). A variant of the problem in which each client is visited by at least one vehicle, called the graphical vehicle routing problem (GVRP), is also considered in this paper and used as a relaxation of CVRP. Our approach for CVRP and GVRP is to extend the polyhedral results known for TSP. For example, the subtour elimination constraints can be generalized to facets of both CVRP and GVRP. Interesting classes of facets arise as a generalization of the comb inequalities, depending on whether the depot is in a handle, a tooth, both or neither. We report on the optimal solution of two problem instances by a cutting plane algorithm that only uses inequalities from the above classes.This work was supported in part by NSF grant DDM-8901495.     

磁浮列车的模糊反馈控制

为了进一步提高了列车的承载能力，本文利用电流互感器、间隙传感器和加速度表作为敏感元件，对悬浮系统进行反馈控制，并根据悬浮质量的不同，对反馈参数进行模糊调整。分析的结果表明，这种设计的模糊反馈控制器可以提高磁浮列车的承载能力。     

Tabu Search heuristics for the Vehicle Routing Problem with Time Windows

This paper surveys the research on the Tabu Search heuristics for the Vehicle Routing Problem with Time Windows (VRPTW). The VRPTW can be described as the problem of designing least cost routes for a fleet of vehicles from one depot to a set of geographically scattered points. The routes must be designed in such a way that each point is visited only once by exactly one vehicle within a given time interval; all routes start and end at the depot, and the total demands of all points on one particular route must not exceed the capacity of the vehicle. In addition to describing basic features of each method, experimental results for Solomon’s benchmark test problems are presented and analyzed. This work was partially supported by the Emil Aaltonen Foundation, Liikesivistysrahasto Foundation, the Canadian Natural Science and Engineering Research Council and the TOP program funded by the Research Council of Norway. This support is gratefully acknowledged.