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.     

Unsteady simulation for a high-speed train entering a tunnel

In order to study the unsteady aerodynamics effects in railway tunnels, the 3D Reynolds average Navier-Stokes equations of a viscous compressible fluid are solved, and the two-equation k-? model is used in the simulation of turbulence, while the dynamic grid technique is employed for moving bodies. We focus on obtaining the changing tendencies of the aerodynamic force of the train and the aerodynamic pressures on the tunnel wall and train surface, and discovering the relationship between the velocity of the train and the intensity of the micro pressure wave at the tunnel exit. It is shown that the amplitudes of the pressure changes in the tunnel and on the train surface are both approximately proportional to the square of the train speed, so are the microwave and the drag of the train.     

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。     

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。     

大型建筑群变配电智能监控系统开发与应用

针对大型智能建筑群变配电设备分布广,系统供电可靠性和连续性要求高的特点,开发设计基于TCP/IP的变配电智能化监控系统,对其底层监控仪表和智能元件采用现场总线通讯控制,通过前端工作站接入以太网,实现基于IP的变配电系统的智能化监控管理.在此基础上.为了满足大型建筑群的能源管理需要,应用网络通信技术与系统集成技术,开发了变配电监控与其他建筑设备监控有机结合的智能建筑能源管理平台,具备远程Web服务功能接口,并已在一项大型建筑群中应用.     

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。     

高速信号采集与分析系统硬件架构的研究

高速数据采集系统作为宽频带信号获取的手段在科学研究和工业生产中起着重要的作用。介绍了基于USB接口的高速信号采集与分析系统结构,以高速A/D ADS830E为对象给出了FIFO、双口SRAM和"CPLD+高速SRAM"3种高速采样及缓存方案,包括结构与逻辑框图、工作原理,并分别指出各自的优缺点。最后,采用"高速A/D+CPLD+高速SRAM"硬件结构,并结合USB接口组建了虚拟仪器系统,加以验证。     

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。     

用于WiMAX系统中LDPC译码器的改进型Benes网络结构

提出了一种性能优化的Benes网络结构作为开关网络用于WiMAX系统中的低密度奇偶校验码译码器．该网络结构在译码器的输入数目不是2的指数时,能获得最优化的性能．该网络结构是非阻塞的并且可以实现输入输出之间的任何排列组合,因此可以支持WiMAX系统中规定的19种模式．为了减少网络结构的硬件复杂度,提出一种用来产生该网络中所有2×2开关的控制信号的高效算法．同时,使用该高效算法可以减少整个网络的延时．结果表明,该控制信号的生成电路可以节省25．4％的芯片面积,并且总体网络的延时可以缩短36．2％．     

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。     

基于智能制造系统的物联网3D监控

针对柔性智能制造系统在生产过程中环境参数、操作行为、随机事件对产品质量的影响的判断数据不完善等问题,给出了一种有效的融合多种传感器为一体的三维虚拟监控的设计方法,模拟仿真和实现柔性智能制造系统中复杂的制造和控制过程。该系统实现了从数据的采集、分析、处理、建模、通信,以及工件的库存状态显示,构建了一个完整的物联网3D监控体系。仿真实验表明,与改造前相比,智能制造系统环境自适应、在线学习、系统运行状态得到了明显的提高。     

京沪高铁站点选址与其所在城市发展解析

基于京沪高铁22个设站城市2006年和2012年的卫星图片数据和地理信息系统软件,通过3个距离指标和1个角度指标来表征城市空间重心和高铁站点位置的关系。3个距离指标包括城市空间重心偏移的实际距离、高铁站点方向的分量距离、高铁站点方向的分量距离标准化偏移数值;1个角度指标为城市空间重心实际偏移方向与高铁站点方向的夹角。研究分析了高铁选址与其所在城市空间拓展的关系,结合案例实地踏勘和访谈,明确站点周边地区发展的问题,进而提出高铁站点这样的大型区域性交通设施进行选址的关键要素,为推进高铁站点周边地区和设站城市发展的有效互动,实现集约、高效和可持续的发展指供指导。     

BulkTree: an overlay network architecture for live media streaming

Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure.     

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.     

Sound quality evaluation of high-speed train interior noise by adaptive Moore loudness algorithm

An online experiment to acquire the interior noise of a China Railways High-speed (CRH) train showed that it was mainly composed of middle-low frequency components and could not be described properly by linear or A-weighted sound pressure level (SPL). Thus, the appropriate way to evaluate the high-speed train interior noise is to use sound quality parameters, and the most important is loudness. To overcome the disadvantages of the existing loudness algorithms, a novel signal-adaptive Moore loudness algorithm (AMLA) based on the equivalent rectangular bandwidth (ERB) spectrum was introduced. The validation reveals that AMLA can obtain higher accuracy and efficiency, and the simulated dark red noise conforms best to the high-speed train interior noise by loudness and auditory assessment. The main loudness component of the interior noise is below 27.6 ERB rate (erbr), and the sound quality of the interior noise is relatively stable between 300–350 km/h. The specific loudness components among 12–15 erbr stay invariable throughout the acceleration or deceleration process while components among 20–27 erbr are evidently speed related. The unusual random noise is effectively identified, which indicates that AMLA is an appropriate method for sound quality assessment of the high-speed train under both steady and transient conditions.     

高速网络取证系统证据存储模型

网络取证系统的最终目标是给法庭提供可靠的数字证据,而面对高速网络取证系统的海量数据其存储是一个挑战.文章提出一个有效的存储模型,完成海量证据的存储,建立证据获取平台.