关于上海地铁一号线轨道高低不平顺问题的探讨

对上海地铁一号线地铁车辆的车箱振动进行现场实测,得到不同区间段的地铁车厢振动加速度;采用上海地铁一号线车辆参数,建立整车模型,通过时域数值计算,分析得到了不同轨道谱输入下的地铁车厢垂向振动加速度和轮轨垂向力,并同实测的地铁车厢垂向振动加速度进行比较,初步探讨了上海地铁一号线的轨道高低不平顺问题。     

轨道长波不平顺检测系统设计

研究轨道不平顺，对于车辆、线路的设计以及轨道状态的科学评定都具有重要意义。通过利用功能强大的LabVIEW虚拟仪器开发平台，进行LabVIEW和MATLAB的混合编程设计的轨道长波不平顺性检测系统，能有效地从加速度信号中提取出了轨道的长波不平顺特征。该系统操作简单灵活，运行稳定可靠。通过实测数据的分析，证明该系统的研制是成功，具有较高的实用价值。     

客运专线轨道不平顺功率谱分析

轨道不平顺是车辆振动的主要激扰源,也是限制列车最高运行速度的主要因素之一,直接关系到列车运行的平稳性、安全性和舒适性。文章以秦沈客运专线轨检车实测轨道不平顺数据为统计样本,基于样本平稳性检验,采用FFT方法进行样本空间的谱估计,并由MATLAB编程得到轨道不平顺谱密度。基于轨道不平顺样本的总体平均,得出了谱密度频率平滑曲线和谱密度曲线拟合表达式,并与我国重载提速干线的谱密度曲线进行了对比分析。在此基础上,对秦沈客运专线的轨道状态进行了评估。     

Blackman-Tukey法的轨道不平顺数值模拟

概述了轨道不平顺的分类和描述方法。分析了估计功率谱密度的Blaekman-Tukey法，并将Blaekman-Tukey法进一步应用于自功率谱情况。根据功率谱密度与轨道随机不平顺的关系，提出了一种基于Blaekman-Tukey法的轨道不平顺数值模拟方法。数值模拟试验表明这种模拟方法简洁、实用、有效。     

线阵CCD传感器检测铁路轨道不平顺状态

介绍一种利用光电技术动态检测轨道不平顺的方法，装置安装在运营机车上，由线阵CCD传感器，红外线光源，轨道检测单元板，数据转储和地面微机处理系统等部分组成，阐述了直接测量法原理，硬件电路，浮动二值化以及双CCD的并行驱动采集，并给出了现场试验结果，检测曲线和故障点照片，该装置稳定可靠，数据准确率高，可对轨道状态进行定量分析和定性评价。     

不平顺条件下高速铁路轨道振动的解析研究

为了分析不平顺条件下高速铁路轨道结构振动,推导了移动车辆在轮对处和轨道结构在轮轨接触点处的柔度矩阵,考虑移动轴荷载和轨道不平顺,建立了移动车辆-轨道垂向耦合振动的解析模型.模型中,移动车辆考虑为弹簧和阻尼器连接的多刚体系统;有碴轨道结构模拟为连续弹性3层梁;轮轨间考虑为线性赫兹接触.算例分析了单台TGV高速动车引起的有碴轨道结构振动,得到轨道不平顺引起的动态轮轨力和轨道各部分的最大振动加速度,研究了列车速度、轨道不平顺以及轨下垫板及扣件、道床和路基等轨下基础刚度对轨道振动的影响.计算表明:随着列车速度和轨道不平顺的增加,轨道结构的振动响应不断增大;轨下基础刚度对轨枕和道床的振动影响较大,对钢轨振动的影响较小.     

基于小波的轨道不平顺信号分析

在强干扰的背景下，利用小波变换，提取出低频的轨道不平顺信号。为了能确切地反映出轨道不平顺信号，分别比较使用了Daubechies类小波，Meyer类小波与谐波小波，并对分析的结果作对比说明。结果表明，谐波小波变换可成功地提取到了轨道不平顺信号。     

轨道不平顺引起列车振动的技术改进

讨论铁路轨道之间的平滑联接问题,设计出几种能使列车车轮在有缝线路的轨道伸缩缝口处实现平滑无振动过度的联接结构。     

轨道不平顺检测中数字补偿滤波器的设计及仿真

轨道不平顺是影响列车安全舒适的主要因素，轨检车可实时准确的检测出轨道不平顺状态；但车速的变化会使传感器信号发生畸变和衰减，使分析数据失真。为了消除车速的影响，分析了轨检系统中数字补偿滤波器的理论及设计方法，最后进行了CCS5000仿真验证。结果表明，数字补偿滤波器能够消除前端有用信号的衰减，且可达到较高的精度。     

高速磁浮列车-轨道梁耦合系统轨道不平顺敏感波长研究

轨道不平顺是诱发车-桥系统耦合振动的主要激励源之一,探明系统耦合振动不平顺敏感波长,对线路管理具有重要参考价值。首先,建立了高速磁浮列车-轨道梁耦合系统空间模型,其中磁浮列车被模拟为具有537个自由度的多体动力学模型,轨道梁被模拟为空间有限元模型,两者之间通过基于比例-微分(proportional-differentiation, PD)控制理论的磁轨关系耦合。其次,以上海高速磁浮为研究背景,选用5车编组列车驶过20跨简支梁桥为计算条件,通过与实测结果对比,验证了模型的正确性。最后,考虑轨道谐波不平顺激励,探讨了不同方向的轨道不平顺组合、不同轨道不平顺幅值和不同车速对列车和桥梁动力响应敏感波长及列车运行平稳性的影响。结果表明：磁浮列车-桥系统横向振动和竖向振动耦合性很弱;在设计车速430 km/h下,车体竖向、侧滚和点头加速度敏感波长分别为140～180 m、60～100 m和120～160 m,车体横向和摇头加速度敏感波长大于200 m;当波长为80、105、115、140和160 m时,会分别引发车体侧滚、摇头、横向、点头和竖向方向的共振;车体和主梁的响应幅值与轨道不平顺幅值基本...     

基于双纵模热稳频激光源的6D激光测量系统

针对目前数控设备无法实现高速及多参数同时测量的问题,以双纵模热稳频激光源为基础,自主研发了高速6D激光测量系统,不仅允许测速高(可达1.3m/s以上),而且解决了现有5D/6D激光干涉仪未能有效解决的高精度测量滚转角的问题,具有很好的推广应用价值.     

The classification of biomedical journals by research level

A new method of classification of biomedical research journals by research level (RL) into clinical or basic, or somewhere in between, is described that updates the system developed by CHI Research Inc. nearly 30 years ago. It is based on counting articles that have one of about 100 “clinical” title words, or one of a similar number of “basic” title words, or both. It allows over 3000 journals in the Science Citation Index (or other databases) to be classified rapidly and transparently, for changes in their research level with time, and for many individual papers in “mixed” journals to be categorised as clinical or basic. This revised version was published online in June 2006 with corrections to the Cover Date.     

Scientific research with the UCSB free electron laser

The University of California at Santa Barbara (UCSB) free electron laser (FEL) operates as a high-power, continuously tunable, coherent source of radiation in the submillimeter and far infrared (FIR) region. As an initial phase of the UCSB FEL science research program, a set of experiments in condensed matter science have been selected to demonstrate the unique capabilities of this new source. A summary of the proposed studies is presented here.     

Operational specifications of the laser illuminated track etch scattering dosemeter reader

The personnel dosimetry operations team at the Los Alamos National Laboratory (LANL) has accepted the laser illuminated track etch scattering (LITES) dosemeter reader into its suite of radiation dose measurement instruments. The LITES instrument transmits coherent light from a He-Ne laser through the pertinent track etch foil and a photodiode measures the amount of light scattered by the etched tracks. A small beam stop blocks the main laser light, while a lens refocuses the scattered light into the photodiode. Three stepper motors in the current LITES system are used to position a carousel that holds 36 track etch dosemeters (TEDs). Preliminary work with the LITES system demonstrated the device had a linear response in counting foils subjected to exposures up to 50 mSv (5.0 rem). The United States Department of Energy requires that the annual general employee dose not exceed 50 mSv (5.0 rem). On a regular basis, LANL uses the Autoscan-60 reader system (Thermo Electron Corp.) for counting track etch dosemeters. However, LANL uses a 15 h etch process for CR-39 dosemeters, and this produces more and larger track etch pits than the 6 h etch used by many institutions. Therefore, LANL only uses the Autoscan-60 for measuring neutron dose equivalent up to exposure levels of approximately 3 mSv (300 mrem). The LITES system has a measured lower limit of detection of approximately 0.6 mSv (60 mrem), and it has a correlation coefficient of R (2) = 0.99 over an exposure range up to 500 mSv (50.0 rem). A series of blind studies were done using three methods: the Autoscan-60 system, manual counting by optical microscope and the LITES instrument. A collection of track etch dosemeters of unknown neutron dose equivalent (NDE) were analysed using the three methods, and the performance coefficient (PC) was calculated when the NDE became known. The Autoscan-60 and optical microscope methods had a combined PC = 0.171, and the LITES instrument had a PC = 0.194, where a PC less than or equal to 0.300 is considered satisfactory.     

激光燃烧诊断技术及应用研究进展

介绍了用于燃烧场温度、组分、火焰构造和流场速度等参数测量的相干反斯托克斯喇曼散射、自发振动喇曼散射、激光诱导荧光和OH示踪测速实验系统,给出了在预混火焰、高能固体推进剂瞬态燃烧场和超声速高温流场测量的部分实验结果,并分析了激光作用区域燃烧场温度、主要组分及流场速度的分布和火焰构造。     

基于AD8302的双纵模双频激光干涉仪信号处理系统

为了解决双纵模双频激光干涉仪原有信号处理电路两路信号易直流漂移、不正交对干涉仪系统测量精度和速度的限制及调整光路观察信号不方便等问题,利用AD8302的良好高频处理特性,设计了一种新的基于AD8302的双纵模双频激光干涉仪信号处理系统,给出了方案的总体框图和信号处理流程图,详细地分析了其工作原理以及提高相位测量精度方法.由于器件相位测量的高分辨率,该系统也可用于高分辨率双纵模双频激光轮廓仪的信号处理.     

Development of a pumping laser system for x-ray laser research

A two-beam chirped-pulse-amplification Nd:glass laser system dedicated to x-ray laser research is described. Each beam provides an output energy of 20 J with a typical pulse duration of 1.3 ps. A prepulse of variable duration is generated by use of a novel, to our knowledge, optical system. A reflection optical system, comprised of an off-axis parabolic mirror and a spherical mirror, produces a line focus with 6-mm length and 165-microm width without chromatic aberration. By use of this pumping laser system, the nickel-like silver x-ray laser at a wavelength of 13.9 nm has been demonstrated.