Progress in high-speed train technology around the world

This is a review of high-speed train development in the sense of technology advances all over the world. Three generations of high-speed trains are classified according to their technical characteristics and maximum operating speed. Emphasis is given to the newly developed high-speed train in China, CRH380. The theoretical foundations and future development of CRH380 are briefly discussed.

Development and Prospectives of Ultra-High-Speed Grinding Technology

Ultra-high-speed grinding(UHSG)is a significant and powerful machining method in view of the enhanced productivity and precision demands.Previous researches regarding formation mechanisms and crucial technologies are comprehensively and thoroughly summarized to highlight state-of-art technology of UHSG.On the basis of the interdependence between process and machine innovations,theoretically,grinding mechanisms in strain hardening,strain rate strengthening,thermal softening,size effect and process characteristics need more in-depth studies to clarify the dominance of UHSG.Technically,CFRP wheel integrating with the brazed bonding has a prominent advantage in bonding strength and grit′s configuration over vitrified bonding,which would be superior in UHSG.Furthermore,external high pressure cooling combining with inner jet cooling methods,accompanied by scraper plates to alleviate the effect of air boundary,are crucial and practical measures for realizing effective cooling in UHSG.Grinding processes,especially those being related to grinding parameters and precise in-process measuring approaches,are also prerequisite for fitting and investigation of UHSG.

New technologies for high-risk tunnel construction in GuiyangGuangzhou high-speed railway

Based on the construction of high risk tunnels in Guiguang-Guangzhou high-speed railway, several new technologies were developed for high-risk tunnel con- struction. First, an integrated advanced geological predic- tion was developed for tunneling in karst area. Then, a new system of ventilation by involving the dedusting technol- ogy was proposed and used in the field, which received a good air quality. Finally, a method to minimize the dis- tance between the working face and the invert installation was proposed by optimizing the invert installation and adopting the micro bench method. Applying the method to the project obtained an excellent result. The achievement obtained for this study would be able to provide a valuable reference to similar projects in the future.

Key Technologies for High Speed WLAN

The rapid development of Wireless Local Area Network (WLAN) has not yet broken the bottleneck that the low transmission speed hinders the further development of WLAN. Now, some key technologies for next generation mobile communications can solve the problem by supporting high-speed transmission and ensuring reliable performance. IEEE 802.11n has made general amendment to 802.11. Based on IEEE 802.11n, the transmission speed can be doubled by the application of Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies on the physical layer. In addition, the enhanced Medium Access Control (MAC) system performance, optimized data frame and improved network throughput can all be achieved by the adoption of frame convergence, Transmission Opportunity (TXOP) and block-acknowledge technologies on the MAC layer. A new error correction method, called Low Density Parity Check Code (LDPC), can also be adopted for the receiver to enjoy low Bit Error Ratio (BER) with low S/N, thus improving signal coverage.

Study on the technologies development trend of high speed EMUs

High speed railway technologies are rapidly development in the world.The total distance of the high speed railway is more than 40,000 kilometers in China,and many types of high speed Electrical Multi-Units(EMUs)are operated.The top operation velocity of the train reaches 350 km/h.New science and technologies are developing rapidly.New generation technologies such as the information technology,intelligent manufacturing,new material and processing,innovating design philosophy have revolutionary influence on the high speed train.It promotes the high speed train performance such as intelligence,reliable operation and environment-friendly.Based on many years investigation of the trend of the technology development and requirement of general public,the trend of technology development in five aspects are presented in this paper.The five aspects include economic applicability,high speed and high efficiency,green and low carbon,intelligent safety,comfortable and high quality.

Investigation into the Independent Metering Control Performance of a Twin Spools Valve with Switching Technology-controlled Pilot Stage

In hydraulic area,independent metering control(IMC)technology is an effective approach to improve system efficiency and control flexibility.In addition,digital hydraulic technology(DHT)has been verified as a reasonable method to optimize system dynamic performance.Integrating these two technologies into one component can combine their advantages together.However,few works focused on it.In this paper,a twin spools valve with switching technologycontrolled pilot stage(TSVSP)is presented,which applied DHT into its pilot stage while appending IMC into its main stage.Based on this prototype valve,a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out.Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology.Rising time of flow response in excavator cylinder can be controlled within 200 ms,meanwhile,the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms.IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries.

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

A Study on the Structure of Linear Synchronous Motor for 600 km/h Very High Speed Train

Recently, an interest in a hybrid system combining only the merits of the conventional wheel-rail system and Maglev propulsion system is growing as an alternative to high-speed maglev train. This hybrid-type system is based on wheel-rail method, but it enables to overcome the speed limitation by adhesion because it is operated through a non-contact method using a linear motor as a propulsion system and reduce the overall construction costs by its compatibility with the conventional railway systems. Therefore, a comparative analysis on electromagnetic characteristics according to the structural combinations on the stator-mover of LSM （linear synchronous motor） for VHST （very high speed train） maintaining the conventional wheel-rail method is conducted, and the structure of coreless superconducting LSM suitable for 600 km/h VHST is finally proposed in this paper.

铁路施工中的智能监测技术及其在高铁项目中的应用

随着现代铁路建设规模的不断扩大和技术要求的提高,智能监测技术在铁路施工中的应用日益广泛。文章探讨了智能监测技术的基本原理及其在高铁项目中的实际应用,通过案例分析展示了该技术在施工过程中的显著优势。通过传感器、图像与视频监控、大数据分析等多种技术手段,智能监测技术不仅提高了施工精度与效率,还显著提升了安全保障水平,降低了工程风险。文章结合多个高铁建设项目,详细分析了这些技术在实际施工中的具体实施及其产生的效果,并提出了未来在铁路建设领域智能监测技术的发展方向。

Simulation on derailment base on a new wheel-rail contact method

The simulation package for special research on derailment of high speed vehicle is established.The process of derailment is different from other behaviors of vehicle dynamics because of large lateral displacement of wheelsets.To get correct results,a new fast algorithm to computing contact force is adopted and the exact geometry analysis is necessary to judge derailment happened.Variation of contact condition and coefficient of friction with speeds are also considered into vehicle-track coupled model.The structure of the package is presented in detail.The results are particular emphasis on investigation influence of maximum track defect,critical vehicle speed and various contact condition on derailment.The simulation can also be used to define the most risk factor leading to derailment.

直流快速开断技术研究进展和展望

由于直流电流无自然过零点且短路电流上升率高,直流电流快速开断与系统故障切除成为制约直流电力系统发展的一大瓶颈。该综述首先介绍了直流快速开断技术要求与难点。其次,详细分析了直流快速开断过程涉及的关键技术,包括电流转移技术、固态式直流开断技术、介质恢复技术和高速机械开关技术等,综述了各种技术的当前发展现状及其应用情况,对比了不同技术方案的特点及适应性。最后,对直流快速开断技术未来发展方向进行了讨论和总结,为小型化、高性能、低成本、高可靠快速直流断路器的研发及推广应用提供了新的技术思路。

基于FPGA的多通道高速串行数据采集系统设计

针对卫星导航信号抗干扰领域中进行高精度高速多通道数据采集的需要,系统采用ADI公司的16位高速串行AD转换芯片AD9653,完成模数转换,其转换精度可达16比特,转换速率最高为125MSPS。分析AD9653的高速串行数据接口特点,采用Xilinx公司的Kintex-7系列FPGA提供的片同步技术,进行位时钟自适应相位校准和数据帧调整研究,保证了高速串行数据传输的稳定性与正确性。采用内部FIFO数据缓存的方式实现多通道数据的片内同步以保证后续抗干扰算法的正确处理。研究结果表明,使用该方法进行高速串行数据采集时系统稳定可靠、正确无误。为多通道高速串行数据采集提供了一种切实可行的解决方案,对类似需求的数据采集系统具有一定的参考价值。

5G高铁专网覆盖综合解决方案研究和应用

5G高铁覆盖面临着资源占时短、瞬时容量高、车体损耗大、移动速度快、基站交替快和远近兼顾难等多重挑战。本文针对5G高铁专网的覆盖方案、容量方案、公专网频率协同方案、主设备与天线选型方案、优化创新方案五大关键点开展了对比论证和深入研究,并应用于某高铁规划建设优化实践中,提升了高铁客户的感知,满足了“5G高铁上车”过渡期的高铁场景5G覆盖需求,为后续高铁覆盖项目的应用推广提供了重要的参考。

膨胀土地基高速铁路路基变形控制分析

研究目的:膨胀土地基在我国分布广泛,浸水后其强度衰减显著,吸水失水产生的胀缩变形反复,工程危害极大,既有铁路、公路路基病害非常突出,膨胀土边坡稳定、基床翻浆冒泥问题现已基本解决,普速铁路和高速公路路基变形也得到了较好控制,但其变形控制标准为20~30 cm,高速铁路以毫米级变形作为控制标准,在膨胀土地基上修建高速铁路路基必须解决路堑和低路堤的膨胀上拱变形和高路堤的沉降变形两大技术难题。研究结论:(1)天然膨胀土地基浸水后膨胀量明显大于无砟轨道铁路工务养护的限值,路基柔性填筑体对膨胀土的膨胀和收缩变形具有较好的缓冲作用;(2)天然膨胀土地基填筑路基在施工期可完成总沉降的80%以上、复合地基加固处理可达90%以上,超固结膨胀土地基上填筑路基高度不大时,加固地基与天然地基的总沉降量均较小;(3)膨胀土地基路堑及低矮路堤工程宜采用路堤式路堑结构,基床范围全部换填,加强防排水措施,地基宜采用小直径、小间距CFG桩加固,一般路堤对浅层4~6 m进行加固处理,高路堤地基处理按一般土质地基进行沉降计算分析确定;(4)本研究结果可为膨胀土地基高速铁路建设提供有益参考。

格构技术在高铁隧道拱部防水板切割衬砌混凝土缺陷整治中的应用

[目的]许多与高铁隧道衬砌相关的缺陷随着高铁建成年限的增加逐渐凸显,防水板切割衬砌混凝土是其中较为严重的一种缺陷。为了减少结构扰动、降低对线路运行的影响,需采用新技术对高铁隧道拱部防水板切割衬砌缺陷进行整治。[方法]以我国西南地区某设计速度为200 km/h的高铁双线隧道为案例,对其发生拱部防水板切割衬砌混凝土后可采用的2个整治方案(现浇套拱、格构技术)进行了详细分析,并进行了结构的安全性、经济性对比评估。对格构技术缺陷整治方案的施工组织、工艺流程、防护措施及施工效果进行了重点论述。[结果及结论]与其他方案相比,格构技术整治方案充分利用了既有结构的承载能力,仅在局部区域修复隧道,对既有衬砌结构影响较小,对高铁线路的运营影响也较小。该方案能明显降低结构的主应力,减少结构位移,使缺陷衬砌的承载能力满足设计要求。

云桂铁路总体设计及技术创新

云桂铁路为中国“八纵八横”高速铁路主通道之一“广昆通道”的组成部分,路网地位突出。根据该项目的功能定位及项目特点,结合地形地质条件、城市规划、环境敏感点、工程安全以及投资合理性等方面,分析确定合理的枢纽引入、线路走向以及重点桥梁、隧道工程方案。项目设计过程中以“系统最优、风险可控”为核心思想,开展了科技攻关和工程实践工作,取得了系列技术创新成果,具有针对性、实用性和理论性,对复杂艰险山区高速铁路建设具有重要指导意义。

成渝中线高速铁路时速400 km关键技术创新研究

成渝中线高速铁路建成后将成为我国建设标准最高、运行速度最快的高速铁路。为贯彻国家创新驱动发展战略,结合中国国家铁路集团有限公司CR450科技创新工程,依托成渝中线高速铁路的建设,开展我国时速400 km高速铁路关键技术的创新研究和更高速度标准的综合试验验证,系统优化完善我国既有时速250~350 km高速铁路基础理论及规范标准,全面构建时速400 km全生命周期技术标准体系。研究成果不仅可助推我国高速铁路装备升级和高速铁路成套建造技术创新发展,还能指导我国的既有高速铁路网进一步提速,促进区域社会经济高质量发展。

高速铁路工程智能建造领域虚拟仿真实训教学改革研究与实践

针对服务高速铁路工程智能建造领域的高速铁道工程专业教学实训过程中存在的高难度、高投入、高风险、难再现、难实施、难观摩的教学实训难题,研究与虚拟仿真相适应的实训教学课程体系,将信息技术和专业群现有实训设施深度融合,着力开展虚拟仿真技术在实训项目中的应用。

被动式压力控制技术的高速列车车内压力计算方法研究

现有采用被动式技术的高速列车车内压力计算方法,未考虑压力保护阀实际工作状态及鸭嘴孔的影响,不利于准确预测通过隧道时的车内压力。基于被动式压力保护阀开闭控制技术路线和空调鸭嘴孔开闭对车体气密性的影响特征,建立列车通过隧道时的车内压力计算方法。在采用一维可压缩非定常不等熵流动模型黎曼变量特征线法获得车外压力后,分析单列车通过短、中长、长、特长隧道情况下压力保护阀开闭特征,并对比分析单列车通过隧道情景下现有计算方法与本文方法预测车内压力变化的差异;结合压力舒适性标准限值分析车内压力舒适性指标值。研究表明:本文计算方法合理可行,不仅能更精确预测被动式技术的高速列车车内压力变化规律,而且为压力保护阀开闭控制技术制定提供切实可行的空气动力学优化依据。

多GPU系统的高速互联技术与拓扑发展现状研究

多GPU系统通过横向扩展实现性能提升,以满足人工智能日趋复杂的算法和持续激增的数据所带来的不断增长的计算需求。对于多GPU系统而言,处理器间的互联带宽以及系统的拓扑是决定系统性能的关键因素。在传统的基于PCIe的多GPU系统中,PCIe带宽是限制系统性能的瓶颈。当前,面向GPU的高速互联技术成为解决多GPU系统带宽限制问题的有效方法。本文首先介绍了传统多GPU系统所采用的PCIe互联技术及其典型拓扑,然后以Nvidia NVLink、AMD Infinity Fabric Link、Intel X^(e) Link、壁仞科技BLink为例,对国内外代表性GPU厂商的面向GPU的高速互联技术及其拓扑进行了梳理分析,最后讨论了关于互联技术的研究启示。