Safety of the express freight train running over a long-span bridge

Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge.Besides,the blunt car body of vehicle has poor aerodynamic characteristics,bringing a greater challenge on the running stability in the crosswind.Design/methodology/approach-In this study,the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test.The dynamic model of the train-long-span steel truss bridge coupling system is established,and the dynamic response as well as the running safety of vehicle are evaluated.Findings-The results show that wind speed has a significant influence on running safety,which is mainly reflected in the over-limitation of wheel unloading rate.The wind speed limit decreases with train speed,and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/value-This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems.It also provides a new theoretical basis for the safety assessment of express freight trains.

China-Europe Freight Train Promotes Bilateral Trade

On October 8,the'Belt and Road'Leading Group office published the'ChinaEurope Freight Train Development Plan',which is a fiveyear plan in accordance with China’s13th'Five-Year Plan'.The document formulated the major tasks for the construction of China-Europe freight train project for the next five years,and clarified three space layouts,including the China-Europe

An Algorithm for the Optimal Matching Speeds of Pass enger and Freight Trains in Mixed Operations

This paper models the calculation of the optimal matching speeds of passenger and freight trains with various stage control methods for speed in mixed operations, presents a algorithm for the solution and justifies it with a practical example.

Research on Optimization of Freight Train ATO Based on Elite Competition Multi-Objective Particle Swarm Optimization

In view of the complex problems that freight train ATO (automatic train operation) needs to comprehensively consider punctuality, energy saving and safety, a dynamics model of the freight train operation process is established based on the safety and the freight train dynamics model in the process of its operation. The algorithm of combining elite competition strategy with multi-objective particle swarm optimization technology is introduced, and the winning particles are obtained through the competition between two elite particles to guide the update of other particles, so as to balance the convergence and distribution of multi-objective particle swarm optimization. The performance comparison experimental results verify the superiority of the proposed algorithm. The simulation experiments of the actual line verify the feasibility of the model and the effectiveness of the proposed algorithm.

Wheel Profile Optimization of Speed-up Freight Train Based on Multi-population Genetic Algorithm

The geometric shape of the wheel tread is mathematically expressed,and geometric parameters affecting the shape of the wheel were extracted as design variables.The vehicle dynamics simulation model was established based on the vehicle suspension parameters and track conditions of the actual operation,and the comprehensive dynamic parameters of the vehicle were taken as the design objectives.The matching performance of the wheel equivalent conicity with the vehicle and track parameters was discussed,and the best equivalent conicity was determined as the constraint condition of the optimization problem;a numerical calculation program is written to solve the optimization model based on a multi-population genetic algorithm.The results show that the algorithm has a fast calculation speed and good convergence.Compared with the LM profile,the two optimized profiles effectively reduce the wheelset acceleration and improve the lateral stability of the bogie and vehicle stability during straight running.Due to the optimized profile increases the equivalent conicity under larger lateral displacement of the wheelset,the lateral wheel-rail force,derailment coefficient,wheel load reduction rate,and wear index are reduced when the train passes through the curve line.This paper provides a feasible way to ensure the speed-up operation of a freight train.

A review on design and testing methodologies of modern freight train draft gear system

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

Theoretical and Experimental Study on The Speed-up of Freight Train with Mixed Marshaling of Light and Heavy Vehicle

To study the influence of the speed-up of a freight train with mixed marshaling of light and heavy vehicles on the dynamic behavior,a dynamic model of the freight train was established based on the modular method of cyclic variables,and the dynamic behavior of the freight train was simulated and analyzed under different marshaling patterns,speeds and line conditions.On-site speed-up test with different marshaling freight trains was carried out,and the stability and ride-index of the train before and after the speed-up were compared and analyzed.The feasibility of increasing the speed of freight trains with mixed marshaling of light and heavy cars was demonstrated theoretically and experimentally.The results show that the theory is in good agreement with the test,which can effectively reflect the dynamic behavior of the vehicle.The dynamic behavior of the freight train in the study meets the requirements of increasing speed to 90 km/h.This paper provides a theoretical basis and method for railway freight transportation and the speed-up of freight vehicles.

基于多目标进化的超限超重货物运输专列路径优化方法

针对超限超重货物运输专列路径优化问题,引入限界改造和桥梁加固要素,以铁路运能损失、运输时间和运输费用的最小化为优化目标,构建铁路超限超重货物运输专列路径优化模型;考虑专列同时运送多件超限超重货物的特点,设计货物综合投影算法,并以Pareto支配关系框架下的NSGA-Ⅱ多目标进化算法为基础,结合基于移动不可行解的自适应惩罚函数的约束处理技术及超限超重货物运输专列开行特征,提出一种基于多目标进化的铁路超限超重货物运输专列路径优化算法。实例分析结果表明:该方法能高效合理地处理路径优化任务中的多个目标;与常用的3种约束多目标算法相比,设计的优化算法能使计算耗时降低0.24%~29.94%、超体积指标值提高4.25%~13.11%,并得到一组收敛性和多样性更好的相对最优方案。该方法克服了传统专列路径优化中单纯依靠经验或从备选方案中择优的弊端,可为铁路超限超重货物运输专列路径决策提供技术支持。

关于打通铁路网运输能力堵点对策探究

国铁企业落实党中央部署要求并加快推进铁路货运市场化改革,采取有效措施尽快打通铁路网运输能力堵点,有效降低物流成本。通过分析路网总体规模、旅客运输供给能力、货物运输保障能力等铁路网运输能力现状,剖析铁路网运输能力堵点及成因。在此基础上,提出加强铁路网运输能力经验借鉴,探析打通铁路网运输能力堵点对策,即:畅通普速干线通道,加强煤运通道能力保障,强化中欧班列通道能力,完善港口铁路通过能力,增强西部陆海新通道线路能力,完善枢纽点线配套能力,强化铁路货运设施设备卸车能力等方面,在助力降低全社会物流成本中发挥“火车头”的重要作用。

贸易便利化与沿线城市产业结构升级——基于中欧班列的准自然实验

中欧班列的国际货运属性导致其对中国贸易便利化和技术创新的影响有别于一般国内铁路。基于2004—2021年中国地级市的数据,将中欧班列开通视为“准自然实验”,运用多期双重差分法探究贸易便利化对沿线城市产业结构升级的影响。结果显示:第一,中欧班列开通能够推动沿线城市产业结构朝着高级化方向发展,在进行三种稳健性检验后结果仍然显著。第二,技术创新、融资支持和数字智能三种机制能对开通城市的产业结构升级产生显著的正向影响。第三,中欧班列对沿线城市产业结构升级的推动作用主要存在于非中心城市。未来城市应利用贸易便利化这一有力“引擎”,通过提升融资便利与数字智能水平,充分发挥交通基础设施在促进创新要素流动中的作用,为沿线城市产业结构调整提供支撑。

基于PSENet区域分割的列车车厢号定位研究

针对自然场景中行驶列车的车厢号采用现有文本定位方法容易存在严重畸变,从而导致漏检率高的问题,提出一种基于区域分割的列车车厢号精确定位方法。该方法所采用的网络模型基于PSENet,首先采用引入通道域注意力的ResNet50网络提取特征,使模型更加关注卷积通道信息,从通道域的角度对权重进行再分配,提高车厢号的定位精度;然后采用特征金字塔和自底向上路径增强模块融合多尺度特征图,将浅层网络中的强定位特征传播到深层网络,以从复杂环境中准确定位车厢号区域,降低车厢号的漏检率;最后采用基于广度优先算法的渐进尺度扩展模块对融合的特征图进行目标区域的从小尺度到大尺度的拓展分割,使用结合集合相似度度量Dice系数的损失函数对分割结果进行分类回归,输出定位结果。实验结果表明:通过在真实列车车厢号图像数据集上进行训练验证,本文提出的网络模型在铁路货运列车车厢号定位精度达到97.47%,召回率为94.14%,综合F1分数为95.78%,预测单张图约需0.2 s。相比于基础PSENet对车厢号的定位精确率提升3.78%,召回率提升1.71%,总体上车厢号的F1分数提升2.73%。研究成果可为列车车厢号自动检测识别系统提供一种高精度的车厢号检测定位方法。

基于级联干扰观测器的货运列车分布式控制研究

针对货运列车在多源扰动下的跟踪控制问题,提出一种基于级联干扰观测器的固定时间替换滑模控制方法。首先构建了考虑车间作用力的多质点动力学模型,针对匹配与非匹配扰动同时存在的情形,设计了一种级联结构扰动观测器同时估计多源扰动,放宽了传统扰动观测器要求“扰动缓慢变化”的前提条件。基于扰动观测信息,将非匹配扰动下的列车动力学模型转化为匹配模式。最终,提出了一种基于替代滑模法的分布式控制策略。仿真结果表明,所提的级联干扰观测器能够在0.5 s内准确估计多源干扰;相比于传统的列车跟踪控制研究,所提出的控制策略能够在快速处理多源扰动带来的一系列失稳问题,在保障车间作用力稳定的同时,实现了速度-位移双指标鲁棒跟踪控制;相对于传统控制方法系统收敛时间提高5 s以上,体现了较好的实时性与鲁棒性。

面向实时需求的高铁快运列车运输组织方案协同优化研究

近年来,我国电商行业高速发展,快递需求随之快速增长。高铁快运凭借其运量大、速度快、能耗低的特点,成为现代快递运输的重要方式。在保证高铁快运产品时效性的基础上,为解决现阶段我国高铁快运列车时刻表、停站方案与货物装配方案三者协同优化研究不足而导致的高铁运力资源利用效率较低的问题,建立二次0-1混合整数规划模型。借鉴铁路阶段计划的思想,将全天分为多个时段,以每个时段的货运需求为导向,针对下个时段的高铁快运货物装配方案和新增快运列车停站方案和时刻表进行协同优化。针对已知新增快运列车数量的情况,建立了考虑货物时效性的新增列车的停站方案、时刻表和装配方案协同优化模型(简称协同优化模型)。针对模型约束进行线性化处理,并根据模型特点设计并使用两阶段求解方法,利用LINGO软件求解。以宁杭高铁线路为例,针对9:00-12:00的列车运行图进行优化分析。从结果来看,协同优化模型相比于传统优化方法,可以同时减少列车在途时间和货物在途时间,保证运力资源的充分利用。对比两阶段求解的求解结果可以发现,相比第1阶段,第2阶段得到的货物在途时间更短,货物装配方案更合理,由此可见两阶段求解方法也是合理且有效的。研究结果可以为进一步优化高铁快运列车运输组织方案,提高运输效率提供参考。

神华铁路动态货物列车开行方案编制优化研究

重载铁路作为我国大型战略物资的重要运输通道,其货物流向及列车径路较为简单。货物列车开行方案既是货物运输组织的重要计划,也是影响货主装运需求与货运到达时限的关键。以神华铁路为研究对象,以重车作业时间与空车延误时间最小化为目标,构建神华铁路动态开行方案编制优化模型,并设计两阶段遗传-禁忌搜索算法的求解策略。最后以包神南线与神朔线作为实例验证,优化后总目标函数值为30010min,其中重车运输作业时间30010min,空车延误时间0min。实现了重空车的合理接续,最大化的保障了货主运输需求,证明了上述模型与算法的有效性。

重载组合列车中部机车车钩自由角对轮轨动态相互作用影响分析

针对2万吨重载组合列车中部机车的运行安全性问题,基于102型机车车钩结构特性,建立“1+1”编组形式的重载组合列车动力学模型,探究车钩自由角对轮轨动态相互作用的影响规律。此外,结合机车轮轴横向力的限值,进一步分析不同线路条件下机车的抗压钩能力。计算结果表明:2万吨重载组合列车的中部机车在纵向压钩力作用下,车钩自由角的大小对列车运行安全性指标有显著影响,列车各项运行安全性指标随着车钩自由角增加而显著增大;在直线制动工况下,且当机车车钩自由角达8°时,压钩力超过800 kN将导致轮轴横向力超限;在R300m小半径曲线制动工况下,车钩自由角达7°时,压钩力600 kN将导致机车轮轴横向力超限。因此,合理控制车钩自由角,同时降低列车运行时的纵向冲动对保障列车安全运行具有重大意义。

侧风作用下不同装载敞车气动性能研究

针对不同装载情况的敞车,开展敞车在空载、半载、满载3种情况下气动性能的研究。研究结果表明:单节敞车气动力的变化规律与整车气动力的变化规律一致;空载敞车所受的气动阻力最大,半载敞车次之,满载敞车最小;满载敞车所受的气动升力最大,半载敞车次之,空载敞车最小;3种敞车所受的侧向力非常接近,最大差距仅为1.9%;空载敞车和半载敞车所受的气动力较为接近,而满载敞车与前两种车型有明显差距。

基于需求链的中欧班列开行方案优化

中欧班列是往来于中国与欧洲以及一带一路沿线各国的集装箱国际铁路联运班列,自开行以来,双方在“一带一路”的框架下展开了卓有成效的合作。从目前发展形势来看,货运服务将迎来更加广阔的前景,因此开行方案的编制尤为重要,开行方案编制通常以铁路运营方经济效益为出发点,很少考虑运营方与客户双方需求。在平衡铁路运营方和客户双方需求的基础上,提出基于需求链的中欧班列开行方案优化方法。开行方案编制分为两阶段实现,首先基于K短路原则生成备选集,得到初始中欧班列开行方案解集合,可有效提高模型求解效率;其次基于“一弧多服务多货流”网络来构建双层规划模型,并设计在粒子群算法中嵌入拉格朗日松弛算法进行求解,可有效简化复杂的原有模型。上层模型从铁路运营方角度出发,考虑货物运输时间、碳排放、能力限制等约束,以实现运输效益最大化;下层模型根据实际客户需求,拓展为允许货流拆分的物流服务选择模型。通过上下层模型交互体现供需双方的博弈行为,使需求链管理思想在中欧班列开行方案中得以运用。算例表明,货流允许拆分情况下,铁路运营方利润增加41.67%,充分证实了本模型的优越性。

基于铁路货物列车节能开行方案的优化研究

为了更好地发挥铁路绿色运营的优势,本文提出面向节能的铁路货物列车开行方案的优化方法。通过对铁路货运线路上的列车运行能耗进行仿真分析,发现不同区间内的运行能耗、不同车站的起停附加能耗差异较大,因此可以通过合理的车流组织来降低能耗。据此,结合铁路实际运输情况,综合考虑铁路运营效益、铁路运输效率、货主时间利益和铁路节能需求,建立铁路货物列车节能开行方案优化模型。选取某铁路线路作为算例验证模型,并对算例结果进行对比分析,结果表明,所构建的优化模型相比其他方案具有更好的优化效果,能够有效降低列车运行能耗并提升运输效率。

基于有限时空域的铁路运行图货物列车运行线铺画方法研究

目前我国部分普速铁路干线仍然存在客货列车争能现象,为此铁路部门时常采用“调客增货”的方式以满足部分时段货物运输需求。但由于普速铁路列车运行图编制时,货物列车运行线的铺画优先级往往低于旅客列车,缺少旅客列车停开后的货物列车运行线自动分析和编制方法,导致货运市场与运行图编制无法适配。为此,将普速铁路旅客列车停开后的货物列车运行线铺画问题转化为动态规划问题,从运行线的函数特征、车站间隔时间和货物列车运行线铺画区域3个方面阐述模型原理,构建基于双计算周期的动态规划模型,并以京广铁路平南至邯郸南一场区段为例对模型进行了有效性验证。结果表明,该方法能有效求解有限时空域内的货物列车运行线连续铺画问题,对提高普速铁路通过能力利用率、优化普速铁路客货列车结构具有理论与实际意义。

高原地区客货共线铁路综合维修天窗设置研究

研究高原地区双线客货共线铁路列车运行图与天窗一体化编制问题对保障行车安全,提升列车运行效率具有重要意义。以旅客列车总运行时间最小为目标函数,考虑了线路区间内动车组列车和货物列车不交会、天窗开设时段设定在白天等约束条件,构建了双线客货共线铁路列车运行图与天窗一体化编制的混合整数规划模型,采用商业求解器GUROBI求解模型,并设计算例进行验证。结果表明,构建的模型能够实现高原地区双线客货共线铁路列车运行图与天窗的一体化编制,并且能满足每个区间内开设4小时的综合维修天窗,保证了每日维修作业的需要。