Sensor network architecture for intelligent high-speed train on-board monitoring

The China’s high-speed railway is experiencing a rapid growth. Its operating mileage and the number of operating trains will exceed 45 000 km and 1500 trains by 2015, respectively. During the long range and constant high-speed operation, the high-speed trains have extremely complex and varied work conditions. Such a situation creates a huge demand for high-speed train on-board monitoring. In this paper, architecture for high-speed train on-board monitoring sensor network is proposed. This architecture is designed to achieve the goals of reliable sensing, scalable data transporting, and easy management. The three design goals are realized separately. The reliable sensing is achieved by deploying redundant sensor nodes in the same components. Then a hierarchal transporting scheme is involved to meet the second goal. Finally, an electronic-tag based addressing method is introduced to solve the management problem.     

高速铁路运营过程中的关键问题：轮轨磨耗等

随着高速铁路运营里程和列车运营速度的不断增长,出现了一些和列车轨道耦合大系统密切相关的关键科学和技术问题。这些问题不仅影响到列车的运行品质,甚至威胁到安全运行,是当前高速铁路运用和发展中急需解决的问题。本文系统描述了高速铁路在运营过程中所出现的一些关键科学和技术问题,并述评了全世界有关这些问题的研究进展、现状和不足之处,提出了今后有利于认识和解决这些问题的发展方向。在长期高速运营的铁路大系统环境中,这些问题的形成的机理、发生、发展过程和预防措施的研究,需要从列车／轨道耦合大系统运营环境（速度、路况、气候和运用维修）、系统的自身参数匹配、材料选用和运营成本等全面系统考虑,并从理论、技术、工艺、监控和维修等方面解决。     

不同速度高速列车车外噪声的调查研究

研究目的：基于声源识别,得出车外噪声分布特性及场点主要噪声源。创新要点：1．研究高速列车噪声源强特性及频谱特性;2．揭示不同速度下不同声源频谱变化规律;3．分析车外声场场点噪声变化规律及主要声源。研究方法：1．利用车外声源识别系统（图2）分析高速列车声源分布规律及频谱特性;2．利用声源的垂向（图10）分布研究不同声源在各频率下垂向分布规律;3．利用场点声源与速度的拟合关系（图16）研究场点主要噪声源。重要结论：1．高速列车车外噪声源主要分布在轮轨区域、受电弓和车间连接区域;2．轮轨区域噪声包括滚动噪声和气动噪声,在各频率均为最显著声源;3．在整个列车高度,轮轨滚动噪声对总噪声贡献率大于气动噪声;4．车外场点噪声主要频率为630-2500Hz,主要来自轮轨滚动噪声。     

基于FPGA的磁浮列车空气弹簧控制系统设计

在磁浮列车运行时,需要调节空气弹簧的刚度来保证车体的平稳,本文设计了一种基于现场可编程逻辑门阵列(FPGA)信号处理的、以继电器为主要控制器件的磁浮列车空气弹簧充排气控制模块来调节空气弹簧的刚度.试验证明该设计是可行的,能够满足磁浮列车空气弹簧控制系统的要求.     

高速列车应急作业工效学实验系统研究

高速列车司机应急作业的可靠性对维护列车正点安全运行具有重要作用,但在实际列车运行中无法开展针对司机应急作业特性的工效学实验,因此有必要构建高速列车应急作业流程工效学实验系统,以便在实验室环境下开展相关研究。高速列车应急作业流程工效学实验系统由实验管理子系统、应急作业子系统和工效学数据采集子系统3个子系统组成,该系统设计中引入了故障注入技术,实现了故障注入、辅助处理等管理操作;系统还能完成司机应急作业操作中相关工效学数据采集功能。系统已成功应用于CRH2型高速列车应急作业流程工效学实验中。     

Dynamic analysis of a high-speed train operating on a curved track with failed fasteners

A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.     

Noisy chaotic neural network for resource allocation in high-speed train OFDMA system

High-speed train communication system is a typical high-mobility wireless communication network. Resource allocation problem has a great impact on the system performance. However, conventional resource allocation approaches in cellular network cannot be directly applied to this kind of special communication environment. A multidomain resource allocation strategy was proposed in the orthogonal frequency-division multiple access （OFDMA） of high-speed. By analyzing the effect of Doppler shift, sub-channels, antennas, time slots and power were jointly consid- ered to maximize the energy efficiency under the constraint of total transmission power. For the purpose of reducing the computational complexity, noisy chaotic neural network algorithm was used to solve the above optimization problem. Simulation results showed that the proposed resource allocation method had a better performance than the traditional strategy.     

Dynamic analysis of a high-speed train operating on a curved track with failed fasteners

A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a con- stant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. （1984） is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.     

Characteristics of interior noise of a Chinese high-speed train under a variety of conditions

This paper presents an investigation into the characteristics of interior noise of a Chinese high-speed train under several typical conditions. Interior noises within Vehicle TC01, which can be used as a head car or an end car, and Vehicle TP03, the third car counting from TC01, are measured for the train running at speeds from 260 km/h to 385 km/h, along two types of track including a slab track and a ballast track and either on the ground surface or in a tunnel. Data analyses are performed for sound pressure overall levels, frequency, area contributions, and possible generation mechanisms, showing how they are affected by train speed, running direction, track type, and tunnel. The results show that, whether TC01 is used as head car or end car, the interior noise characteristics in the VIP cabin are mostly related to aerodynamic noise. Differences in interior noise between tracks become smaller as the train speed increases. The effect of a tunnel on the interior noise is more important for the middle coach than that for the head coach. This study can provide a basis for noise control of high-speed trains.     

高速列车以400km/h通过隧道时气动效应的数值模拟与分析

基于三维瞬态可压缩雷诺时均N-S方程及κ-ε两方程湍流模型,对8节编组长度的某高速动车组以400km/h高速通过70m~2单线隧道所产生的压力变化进行数值模拟研究。研究结果表明:列车以300km/h通过单线隧道时,隧道壁面压力的正峰值、负峰值和变化幅值的最大值均出现在隧道中部,单线隧道的三维效应并不明显;车体表面的正峰值和压力变化幅值的最大值均出现在鼻尖处,列车中部测点压力区别不大;列车提速到400km/h时,列车和隧道表面最大峰值压力可分别达到10.733kPa和4.675kPa。该研究结果可为分析隧道空气动力对车体、隧道衬砌及隧道内附属设施的影响提供参考。     

Multi-objective aerodynamic optimization design of high-speed train head shape

To improve the aerodynamic performance of high-speed trains (HSTs) running in the open air, a multi-objective aerodynamic optimization design method for the head shape of a HST is proposed in this paper. A parametric model of the HST was established and seven design variables of the head shape were extracted. Sample points and their exact values of optimization objectives were obtained by an optimal Latin hypercube sampling (opt. LHS) plan and computational fluid dynamic (CFD) simulations, respectively. A Kriging surrogate model was constructed based on the sample points and their optimization objectives. Taking the total aerodynamic drag force and the aerodynamic lift force of the tail coach as the optimization objectives, the multi-objective aerodynamic optimization design was performed based on a non-dominated sorting genetic algorithm-II (NSGA-II) and the Kriging model. After optimization, a series of Pareto-optimal head shapes were obtained. An optimal head shape was selected from the Pareto-optimal head shapes, and the aerodynamic performance of the HST with the optimal head shape was compared with that of the original train in conditions with and without crosswinds. Compared with the original train, the total aerodynamic drag force is reduced by 2.61% and the lift force of the tail coach is reduced by 9.90% in conditions without crosswind. Moreover, the optimal train benefits from lower fluctuations in aerodynamic loads in crosswind conditions.     

Multi-objective optimization design method of the high-speed train head

With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces （moments）, possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objec- tives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load re- duction factor was reduced by up to 1.72%.     

高速列车到底能跑多快

高速列车的"门槛"是指列车最高时速达到或超过200公里。高速列车跑得快,既需要有大功率的牵引动力,也要求列车又轻又稳。由于列车阻力与速度相关,所以要采用流线型车体等一系列减少阻力的措施。另外,列车还要能及时停下来,因此高速列车不像普通列车那样依靠闸瓦与车轮摩擦来制动,而要采用先进的综合制动手段。     

Influence of aerodynamic braking on the pressure wave of a crossing high-speed train

When aerodynamic braking works, the braking wings can change the flow field around the train, which may impact on the comfort and safety. Based on a sliding mesh, the pressure wave and flow field around high-speed trains with aerodynamic braking are analyzed. By comparing three typical intersection situations, the pressure wave of a high-speed train during braking (with or without aerodynamic braking) is studied. The analyses indicate that the pressure wave around the high-speed train body will change while using the aerodynamic braking, causing several pressure pulses on the surface of crossing high-speed trains. The distances between the pressure pulses are equal to the longitudinal distances of the brake wings, but the magnitudes of the fluctuations are less than those induced by the head of crossing trains. During the crossing, a train without aerodynamic braking will not impact the crossing train.     

一种高速列车-轨道三维空间耦合动力学模型

研究目的：基于车辆-轨道耦合动力学理论分析方法,建立一种高速列车-轨道三维耦合动力学模型,并明确列车-轨道耦合模型与单节车辆-轨道耦合模型在高速列车-车九道耦合动力学性能分析中的差异。创新要点：建立一种高速列车-轨道三维耦合动力学模型,模型中考虑列车的纵向动力学行为以及车间连接装置对列车中不同车辆动态响应的影响,并基本明确完善的列车-轨道耦合模型在高速列车-轨道耦合动力学性能分析中的重要性。重要结论：单节车辆-轨道耦合模型会过高地估计高速列车在运营过程中的振动响应和动力学性能指标,而完善的列车-轨道耦合动力学模型的计算结果则更加接近实际情况。     

A numerical approach to the interaction between airflow and a high-speed train subjected to crosswind

Aerodynamic forces and dynamic performances of railway vehicles are coupled and affected by each other. On the one hand, aerodynamic forces change the displacements of a train. On the other hand, displacements affect aerodynamic forces. Based on vehicle-track coupling dynamics and aerodynamics, a numerical approach to the interaction between airflow and a high-speed train is presented in this paper. Aerodynamic forces and dynamic performances of a high-speed train subjected to crosswind were numerically simulated. Results showed that the interaction between airflow and a high-speed train has a significant influence on displacements and aerodynamic forces of the head coach. Therefore, it is necessary to consider the interaction between airflow and a high-speed train subjected to crosswind.     

Experimental analysis of the mechanism of high-order polygonal wear of wheels of a high-speed train

This paper presents a detailed investigation, via field experiment, into the mechanism of high-order polygonal wear of wheels of a new type of high-speed train. The investigation was carried out during the performance acceptance test of the train and its initial commercial operation. The investigation covered the performance acceptance test of 150 000 km and the commercial operation of about 150 000 km. In the performance acceptance test of the first stage of about 70 000 km, at 200–250 km/h with full loading and sometimes overloading by 30%, the serious polygonal wear of 23-order took place on all the wheels of the train, and was measured and analyzed in detail. All the polygonized wheels were re-profiled because the polygonal wear had caused strong vibration and damage to the train parts. After re-profiling, the vibration of the train and track and the wear status of the wheels were measured and analyzed at different test mileages according to the polygonal wear situation of the wheels. The measured vibration of the train includes the accelerations at different positions of a motor car and a trail car. The vibration modes of the key parts of the bogies of the two cars were calculated. Meanwhile, the track resonant frequencies were investigated at the site. The purpose of the above tests and analysis is try to find the frequency of work mode matching the passing frequency of the high-order wheel polygon. The present investigation shows that one of the working models causes the formation and development of the high-order wheel polygonal wear. The growth of this wear was effectively reduced through the frequent changing of the running speed of the train operating on the way back and forth every day.     

Aerodynamic modeling and stability analysis of a high-speed train under strong rain and crosswind conditions

With the development of high-speed train, it is considerably concerned about the aerodynamic characteristics and operation safety issues of the high-speed train under extreme weather conditions. The aerodynamic performance of a high-speed train under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper. The impact of heavy rainfall on train aerodynamics is investigated, coupling heavy rain and a strong crosswind. Results show that the lift force, side force, and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall rate of 60 mm/h. when considering the rain and wind conditions. The increases of the lift force, side force, and rolling moment may deteriorate the train operating safety and cause the train to overturn. A quasi-static stability analysis based on the moment balance is used to determine the limit safety speed of a train under different rain and wind levels. The results can provide a frame of reference for the train safe operation under strong rain and crosswind conditions.     

高速碰撞仿真计算的优化方法

针对高速碰撞仿真系统中计算量较大的有限元计算部分,建立了并行有限元模型和区域划分原则,利用逐元法(Element by Element,EBE)分析有限元结构和单个有限元的物理量,利用区域划分方法对有限元网格进行划分,并采用中心差分法求解拉格朗日运动方程,用以模拟圆柱形物体高速碰撞刚性墙的过程。分析了多核CPU架构的基本通信原理,提出了1种动态负载均衡策略,能够优化多核架构上高速碰撞过程中有限元计算的运行效率,选用MPICH2和FORTRAN编写了仿真计算程序。经过多次实验,该优化方法将有限元计算程序运行效率平均提高了8.7%以上。     

基于LS-SVM的高速列车广义非线性模型子空间辨识

针对高速列车动力建模问题,提出了基于最小二乘支持向量机(LS-SVM)的高速列车广义非线性模型子空间辨识方法。先给出描述高速列车单质点力学行为的随机离散非线性状态空间模型,并进一步构建了高速列车广义非线性模型;采用LSSVM回归方法构造广义非线性函数,并运用子空间辨识方法,直接由增广输入、输出数据得到高速列车广义非线性模型参数矩阵。最后对上述模型进行了数值仿真。结果表明:所提出的基于LS-SVM的子空间辨识方法比常规LS-SVM方法、线性子空间方法对列车模型具有更高的预报性能,用于高速列车的建模是有效的,可用于具有非线性、强耦合的高速列车运行过程数学模型的辨识。