Study on wear characteristics and authorized limits of switch rails of high-speed turnout

Purpose-It is quite universal for high-speed turnouts to be exposed to the wear of the stock rail of the switch rail during the service process.The wear will cause the change of railhead profile and the relative positions of the switch rail and the stock rail,which will directly affect the wheel-rail contact state and wheel load transition when a train passes the turnout and will further impose serious impacts on the safety and stability of train operation.The purpose of this paper is to provide suggestions for wear management of high-speed turnout.Design/methodology/approach-The actual wear characteristics of switch rails of high-speed turnouts in different guiding directions were studied based on the monitoring results on site;the authorized wear limits for the switch rails of high-speed turnout were studied through derailment risk analysis and switch rail strength analysis.Findings-The results show that:the major factor for the service life of a curved switch rail is the lateral wear.The wear characteristics of the curved switch rail of a facing turnout are significantly different from those of a trailing turnout.To be specific,the lateral wear of the curved switch rail mainly occurs in the narrower section at its front end for a trailing turnout,but in the wider section at its rear end when for a facing turnout.The maximum lateral wear of a dismounted switch rail from a trailing turnout is found on the 15-mm wide section and is 3.9 mm,which does not reach the specified limit of 6 mm.For comparison,the lateral wear of a dismounted switch rail from a facing turnout is found from the 35-mm wide section to the full-width section and is greater than 7.5 mm,which exceeds the specified limit.Based on this,in addition to meeting the requirements of maintenance rules,the allowed wear of switch rails of high-speed turnout shall be so that the dangerous area with a tangent angle of wheel profile smaller than 43.68 will not contact the switch rail when the wheel is lifted by 2 mm.Accordingly,the lateral wear limit at the 5-mm wide section of the curved switch rail shall be reduced from 6 mm(as specified)to 3.5 mm.Originality/value-The work in this paper is of reference significance to the research on the development law of rail wear in high-speed turnout area and the formulation of relevant standards.

Analysis of Fault Arc in High-Speed Switch Applied in Hybrid Circuit Breaker

The behavior of fault arc in a high-speed switch （HSS） has been studied theoretically and experimentally. A simplified HSS setup is designed to support this work. A two-dimensional arc model is developed to analyze the characteristics of fault arc based on magnetic-hydrodynamic （MHD） theory. The advantage of such a model is that the thermal transfer coefficient can be determined by depending on the numerical method alone. The influence of net emission coefficients （NEC） radiation model and P1 model on fault arc is analyzed in detail. Results show that NEC model predicts more radiation energy and less pressure rise without the re-absorption effect considered. As a consequence, P1 model is more suitable to calculate the pressure rise caused by fault arc. Finally, the pressure rise during longer arcing time for different arc currents is predicted.

Design and Implementation of Dynamic High-Speed Switches in Super Base Station Architectures

Novel centralized base station architectures integrating computation and communication functionalities have become important for the development of future mobile communication networks.Therefore,the development of dynamic high-speed interconnections between baseband units(BBUs)and remote radio heads(RRHs)is vital in centralized base station design.Herein,dynamic high-speed switches(HSSs)connecting BBUs and RRHs were designed for a centralized base station architecture.We analyzed the characteristics of actual traffic and introduced a switch traffic model suitable for the super base station architecture.Then,we proposed a data-priority-aware(DPA)scheduling algorithm based on the traffic model.Lastly,we developed the dynamic HSS model based on the OPNET platform and the prototype based on FPGA.Our results show that the DPA achieves close to 100%throughput with lower latency and provides better run-time complexity than iOCF and HE-iSLIP,thereby demonstrating that the proposed switch system can be adopted in centralized base station architectures.

Development of High-Speed On-Of Valves and Their Applications

With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.

基于宽频带电流传感器的开关柜局部放电检测方法研究

开关柜局部放电信号的采集会受到噪声信号的影响,导致开关柜局部放电检测准确性较差,为此提出基于宽频带电流传感器的开关柜局部放电检测方法。该方法将宽频带电流传感器放置在开关柜的零序电流互感器处,采集宽频带电流,结合独立分量分析方法和经验模态分解方法,消除噪声信号对局部放电检测产生的影响,提取去噪后宽频带电流的集中度特征,将其输入更新后的高斯混合模型中,实现开关柜局部放电检测。实验结果表明:所提方法的电流检测误差在0.1 mA以内,错分率小于0.25%,放点检测耗时为23.5 s。证明了所提方法对开关柜局部放电检测的准确性及效率均较好,能够有效保障开关柜运行的安全稳定性。

Interruption Characteristics of High-speed Switches in 500 kV Fault Current Limiter with High Coupled Split Reactance

A 500 kV high-voltage AC fault current limiter(FCL)based on a high coupled split reactor(HCSR)is pro-posed by the National key R&D project team.Low impedance under normal conditions and high impedance under short-circuit conditions are accomplished by the cooperation of HCSR and high-speed switches.High-speed switches play an important role in current limiting processes,thus interruption characteristics of the high-speed switch in the 500 kV FCL are studied in this paper.The simulation model of the FCL and the external equivalent power grid are established.The short-circuit current and recovery voltage characteristics of the high-speed switch in FCL are simulated.The results show that maximum DC component of the short-circuit current of the high-speed switch reaches 91%,the maximum peak value is 118 kA,and the longest arcing time is 14.8 ms.There is a discontinuity in the curve of the short-circuit current peak and arcing time as a function of the short-circuit occurrence time;the peak recovery voltage of a single break of the high-speed switch has a maximum value of 87.5 kV under a three-phase ungrounded short-circuit condition,and the rate of rise of recovery voltage is o.22 kV/s.The recovery voltage peak shows a period change with the short-circuit occurrence time,and the period is 10 ms.The effects of the shunt capacitor value and short-circuit ground resistance on the recovery voltage of high-speed switching are also studied.The research can be used for reference by R&D personnel and testersof500kVFCLs.Index Terms-Fault current limiter(FCL),high coupled split reactor(HCSR),high-speed switch,interruption characteristics,short circuit current.

基于互感开关变压器的毫米波宽带数控振荡器

为满足宽频带、高性能的要求,设计了一款V波段毫米波宽带数控振荡器(DCO)。采用基于互感开关变压器的电感调谐技术,通过互感开关控制一组耦合变压器实现双模切换,输出低频子带或高频子带,从而实现宽带设计。采用离散电压控制可变电容器实现离散电容器调谐,与开关电容相比降低了寄生电容和损耗,能够实现更大的带宽和良好的相位噪声。电路基于40 nm CMOS工艺设计,核心芯片面积仅为0.053 mm^(2)。频率调谐范围为57.85~72.30 GHz,1 MHz频偏处相位噪声范围为-95.32~-91.07 dBc/Hz。

便携式宽带电磁骚扰自动检测系统设计与实现

针对自然环境中电子信息设备和系统的电磁环境效应、感知与防护问题,研发了一套便携式宽带电磁骚扰自动检测系统,实现了电磁骚扰强度、频谱和方位的自动测量。系统由全自动信号采集平台和数据分析处理平台两部分构成,基于μC/OS-Ⅲ嵌入式操作系统,采用LabVIEW软件控制上位机。通过交互式界面键入命令来控制频谱仪读取并显示测量数据,同时系统自动控制射频开关、云台等硬件设备,实现测量姿态的闭环控制与数据采集以及天线的最佳姿态自动调控,具有全方位扫描功能。实验结果表明,系统测量频率范围300 MHz~3.5 GHz,电场强度的相对误差均小于6.2%,方位角误差小于1.5°。该系统荣获了第十六届全国研究生电子设计竞赛西北赛区团队一等奖。

基于GaAs PHEMT工艺的Ka波段三通道开关滤波器

基于0.15μm GaAs赝配高电子迁移率晶体管(PHEMT)工艺设计了一款22~42 GHz的宽带三通道开关滤波器芯片。该开关滤波器由单刀三掷开关、带通滤波器、控制电路构成。开关采用场效应晶体管(FET)串并结合结构实现。带通滤波器采用梳状结构,一端加载金属-绝缘体-金属(MIM)电容实现。芯片集成了2∶4线译码器作为控制电路,实现通道的选择和切换。芯片尺寸为3.0 mm×2.4 mm×0.1 mm。测试结果表明,三个通道的插入损耗均小于8.5 dB,带内回波损耗均小于-10 dB,带外衰减均大于40 dB。该开关滤波器芯片具有插入损耗小、隔离度高、集成度高、阻带宽的特点。

基于多协议标签交换路由宽带均衡算法的电网通信负载缓冲研究

为了解决现有方法存在的数据包延迟和时间较长的问题,提出基于多协议标签交换(multi-protocol label switching,MPLS)路由宽带均衡算法的电网通信负载缓冲方法。获取建立电网通信信息路由的目标函数与约束条件,结合基于MPLS的动态带宽调度算法,实现MPLS路由宽带均衡,完成电网通信负载缓冲。结果表明:采用所提方法数据包的延迟时间得到了降低,方法的应用性能理想,为相关领域的深入研究提供了可靠依据。

一种宽带高隔离度2×4开关矩阵的3D模块设计

设计的开关矩阵3D模块采用球栅阵列(Ball Grid Array,BGA)植球工艺将上下2层陶瓷基板进行互联,以此实现三维电路结构。在需要对多种元器件进行布局和复杂布线的情况下,采用多层陶瓷基板来构建系统级封装(System In Package,SIP),更易于实现开关矩阵的强大功能。该3D模块开关矩阵的体积为21 mm×16 mm×3.6 mm,采用3D SIP集成技术解决了宽带射频信号的垂直互联、高密度集成、通道隔离度等难题,实现了对宽带信号的开关切换,可以同时实现4个输出端口对2个输入激励的任意切换。与传统的开关矩阵相比,该模块具有体积小、重量轻以及成本低等优点,可以广泛用于功分网络及其他微波系统的一体化、小型化设计。

一种基于电话终端的宽窄带自适应方法

恶劣的线路环境是电话通信的最大障碍,迫切需要安全可靠、适应性强的电话终端,为用户提供稳定优质的呼叫连接服务。通过对语音通信网络宽窄带切换的研究,设计了一种支持宽窄带自适应的电话终端实现方案。在呼叫控制中心采用号码绑定机制,保证宽窄双线接入网络,利用链路实时检测和网络质量分析,为语音呼叫的链路选择提供依据,最大程度地保证语音通话服务的可靠性,有效解决了单一网络线路不稳定的问题,对方案的可用性进行测试评估。

Performance analysis of an integrated scheme in optical burst switching high-speed networks

A new integrated scheme based on resource-reservation and adaptive network flow routing to alleviate contention in optical burst switching networks is proposed. The objective of the proposed scheme is to reduce the overall burst loss in the network and at the same time to avoid the packet out-of-sequence arrival problem. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution schemes based on conventional routing. Through extensive simulations, it is shown that the proposed scheme not only provides significantly better burst loss performance than the basic equal proportion and hop-length based traffic routing algorithms, but also is void of any packet re-orderings.

宽带pin二极管单刀双掷开关的设计与实现

采用两个pin二极管设计、仿真,制作了一个8～20 GHz并联结构的高功率容量的单刀双掷开关。首先通过采用一个新的电路结构,该电路结构除了传统的并联pin单刀双掷开关结构外,还有微带线匹配电路部分,克服了并联结构单刀双掷开关难以实现大的带宽的缺点。然后选择合适的二极管,根据其参数,建立开路、短路等效电路模型;利用Ansoft Designer软件对电路进行了仿真和优化。最后根据优化结果制作并测试了单刀双掷开关。该单刀双掷开关插入损耗在频率8～20 GHz内小于1.7 dB,在频率8～15 GHz内小于1.5 dB;开关隔离度在整个频带内大于21 dB;在14 GHz耐功率容量大于10 W(CW)。

宽频高精度电压比例测量装置

为了研究谐波对电力互感器误差特性的影响,文章基于Labview和NI PXI-5922双通道数字化仪,运用双通道交换技术,研制了一种宽频高精度电压比例测量装置。介绍了该装置的结构和工作原理,并通过试验对装置的基本误差、频率特性以及短期稳定性等性能进行了测试。研究结果表明通道交换技术有效降低了装置的比例测量误差,当两被测电压信号间的相位较接近时,装置在工频下的比值差小于1×10-6,相位差小于0.1μrad,在60Hz^10kHz范围内的频率响应非常平坦,比例测量性能较同类装置有较大提高。

宽带直接接触式RF MEMS开关

本文提出一种静电驱动直接接触式宽带MEMS开关,包含CPW传输线、双U型金属悬臂梁、触点和锚区,兼顾了开关接触可靠、克服微结构粘连和低驱动电压三大结构可靠性设计因素。本开关为三端口开关,使用低温表面微机械工艺,制作在400μm厚的高阻硅衬底上,芯片尺寸0.8mm×0.9mm。样品在片测试结果表明,在6GHz频点,开关本征损耗0.1dB,隔离度24.8dB,等效开关接触电阻0.6Ω,关态电容6.4fF,开关时间47μs,开关驱动电压为20-60V。

宽带RF-MEMS开关驱动电压的分析研究

根据国内外发展的经验,从绝缘介质膜的制备、微桥膜内的残余应力到微桥膜的弹性系数这些影响驱动电压的关键因素出发,提出了一些新的微加工工艺和设计方法,为设计性能优良的RF-MEMS开关提供一种有效的方案,也为RF-MEMS开关设计和研制提供了有意义的探讨。

数字控制增益可配置的射频宽带放大器

针对数字电视射频接收机越来越宽的覆盖范围,更低的噪声系数要求以及更高的线性度,提出一种可用于UV频段数字电视射频接收的数字控制增益可配置的射频宽带放大器电路,引入噪声消除技术减少噪声系数,采用线性度改进技术提高中间电路的线性度,利用改进的源级跟随器结构实现更低的步进精度.电路采用0.18umCMOS工艺,1.8V供电电源,在170～870MHz频率信号输入下,可以实现最低3.8dB的噪声系数,最大增益下提供-12dBm的三阶交调点,55dB的动态范围,步进精度为0.8dB,消耗14.76mW的功耗,面积为800um×600um.测试结果表明所设计的射频宽带放大器,相比传统的设计,在覆盖UV频段的同时能够提供更低的噪声系数,且提供更高的线性度.

DC～40GHz反射型GaAs MMIC SPST开关

介绍了基于GaAs PHEMT工艺设计的一款宽带反射型MMIC SPST开关的相关技术,基于成熟的微波单片集成电路设计平台开展了宽带SPST开关设计。工作频率范围为DC^40 GHz,插入损耗≤0.8 dB,隔离度≥25 dB,驻波比≤1.4∶1。同时,对电路的通孔特性进行了分析,对电路设计流程进行了阐述。要获得期望带宽的开关,如何选择控制器件的通孔连接方式,以及通孔数量对插入损耗等性能的影响。最终,具有小尺寸和优异微波性能的GaAs微波单片集成单刀单掷开关电路成功开发。

带有低噪声单端转差分电路的射频增益可控放大器

为了改进传统电路中单端转差分电路的噪声性能,提高传统射频可变增益放大器的覆盖范围和步进精度,该文设计了一种带有低噪声单端转差分电路的射频增益可控放大器。该文利用噪声抵消技术降低了噪声系数,利用电容交叉耦合技术展宽电路带宽,利用输出源级跟随器的增益可调功能实现更高的步进精度。电路采用0.18 mm CMOS工艺,1.8 V供电电源,在170-870 MHz频率信号输入下,可以实现最低3.8 dB的噪声系数,55 dB的动态范围,步进精度0.8 dB,消耗14.76 mW的功耗,面积800 mm×600 mm。测试结果表明在覆盖更宽的频段范围下,该文设计的射频可变增益放大器在消耗相同功率条件下与传统的单端转差分电路相比可以达到更低的噪声系数,同时整个可变增益放大器可以提供更高的步进精度。