Dynamic track-soil interaction——calculations and measurements of slab and ballast tracks

The dynamic behaviour of slab and ballast tracks was investigated using measurements and calculations. Hammer impacts and train passages were analysed and measurements were made using geophones(velocity transducers) which had been time-integrated to displacements. The calculations were carried out in the frequency-wavenumber domain for multi-beamon-continuous soil models. The characteristics of the different tracks and track elements were established in theory and by experiment. The frequency-dependent compliances(displacement transfer functions) showed clear rail-on-railpad resonances or highly damped track-soil resonances. Compared to the rail and sleeper, the track slab had much lower amplitudes. The slab track usually had the highest rail amplitudes due to soft railpads. Train passage yielded track displacements which were a superposition of the axle loads from the two neighbouring axles of a bogie and from the two bogies of two neighbouring carriages. This global behaviour was characteristic of the track slab of the slab track, whereas the rails of the slab and the ballast tracks behaved more locally with only one bogie of influence. The measurements agreed very well with the theory of continuous soil in the case of the six measured slab tracks and acceptably well for the six measured ballast tracks. The measurements allowed us to find appropriate model parameters and to check the models. For example, the Winkler model of the soil was found to be less appropriate because it reacted more locally.     

鼠洞对铁路轨枕的危害研究及治理

在考虑轨道稳定性的过程中,要考虑鼠洞对轨枕的危害性.鼠洞会使轨枕底与道碴之间存在空隙,列车运行时鼠洞会使轨枕产生附加动力.对轨枕进行了动力学计算和强度校核,当鼠洞严重时,轨枕不能满足动力学强度条件.本文就鼠洞对轨枕的危害性进行了研究,介绍了大瑶山隧道治理鼠洞的实验,该实验效果较好,提出了治理鼠洞的基本方法,本文的研究结果为改进鼠洞对轨枕的危害提供了一定的科学依据,具有一定的指导意义和应用价值.     

High-finesse displacement sensor and a theoretical accelerometer model based on a fiber Fabry-Perot interferometer

A displacement sensor based on the fiber Fabry-Perot （F-P） cavity was proposed in this paper. Theoretical and experimental analyses were presented. Displacement resolution was demonstrated by spectrum-domain experiments to obtain the dynamic range of the F-P sensor, and a piezoelectric crystal unit （PZT） was used as the driver. The output signal was modulated by a piezoelectric ceramic ring and demodulated by a phase-locked oscillator. The experimental results show that the displacement resolution of the F-P sensor is less than 5 nm and the dynamic range is more than 100 μm. As acceleration is the second-order differential of displacement, an accelerometer model was proposed using the finite element method （FEM） nd ANSYS software.     

A Case for Coach Garfinkel: Decision Making and What We Already Know

The purpose of this article is to deconstruct the decision-making processes of sports coaches through the writings of the sociologist Harold Garfinkel. Specifically, the authors draw upon Garfinkel’s (1967) writings on jurors’ decision making to challenge current cognitivist bound conceptualization to better interpret coaches’ sense-making–why and how they make their decisions. The significance of the work lies in further deciphering the meaningful structures of daily coaching lives; within whose limits coaching decisions unfold. Following a brief review of literature related to coaches’ decision making, the principal tenets of Garfinkel’s work are outlined. This gives way to an examination of Erving Goffman’s (1974) work of “frames of reference” in terms of how coaches’ decision making can be developed and improved before a reflective conclusion summarizes the main points made and their implications for future coach education.     

A new principle and device for large aircraft components gaining accurate support by ball joint

How to obtain an accurate support for large components by ball joint is a key process in aircraft digital assembly. A novel principle and device is developed to solve the problem. Firstly, the working principle of the device is introduced. When three or four displacement sensors installed in the localizer are touched by the ball-head, the spatial relation is calculated between the large aircraft component’s ball-head and the localizer’s ball-socket. The localizer is driven to achieve a new position by compensation. Relatively, a support revising algorithm is proposed. The localizer’s ball-socket approaches the ball-head based on the displacement sensors. According to the points selected from its spherical surface, the coordinates of ball-head spherical center are computed by geometry. Finally, as a typical application, the device is used to conduct a test-fuselage’s ball-head into a localizer’s ball-socket. Positional deviations of the spherical centers between the ball-head and the ball-socket in the x, y, and z directions are all controlled within ±0.05 mm under various working conditions. The results of the experiments show that the device has the characteristics of high precision, excellent stability, strong operability, and great potential to be applied widely in the modern aircraft industry.     

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.     

基于深度学习的电子病历实体标准化

电子病历中同一医疗概念的提及形式具有多样性,阻碍了医疗数据的分析和利用,研究电子病历实体标准化具有现实意义。设计并实现了基于深度学习的电子病历实体标准化算法,使用Siamese网络架构和LSTM网络搭建模型,采用Pairwise方法训练模型,在测试集上与传统基于编辑距离的方法进行比较。对手术实体标准化的实验结果显示,深度学习算法正确率达到79.71%,比传统方法提高了17.4个百分点,表明深度学习算法在电子病历实体标准化方面具有有效性。     

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.     

A 2.5D finite element approach for predicting ground vibrations generated by vertical track irregularities

Dynamic responses of track structure and wave propagation in nearby ground vibration become significant when train operates on high speeds. A train-track-ground dynamic interaction analysis model based on the 2.5D finite element method is developed for the prediction of ground vibrations due to vertical track irregularities. The one-quarter car model is used to represent the train as lumped masses connected by springs. The embankment and the underlying ground are modeled by the 2.5D finite element approach to improve the computation efficiency. The Fourier transform is applied in the direction of train’s movement to express the wave motion with a wave-number. The one-quarter car model is coupled into the global stiffness matrix describing the track-ground dynamic system with the displacement compatibility condition at the wheel-rail interface, including the irregularities on the track surface. Dynamic responses of the track and ground due to train’s moving loads are obtained in the wave-number domain by solving the governing equation, using a conventional finite element procedure. The amplitude and wavelength are identified as two major parameters describing track irregularities. The irregularity amplitude has a direct impact on the vertical response for low-speed trains, both for short wavelength and long wavelength irregularities. Track irregularity with shorter wavelength can generate stronger track vibration both for low-speed and high-speed cases. For low-speed case, vibrations induced by track irregularities dominate far field responses. For high-speed case, the wavelength of track irregularities has very little effect on ground vibration at distances far from track center, and train’s wheel axle weights becomes dominant.     

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.     

红外传感器的温度漂移和非线性补偿技术研究

红外线列车轴温监测系统是目前铁路采用的一种列车运行安全动态监测装置,其中红外轴温探测器是其关键部件.针对红外探测器进行研究,详细讨论了红外轴温监测系统中存在的温度漂移和非线性问题,探讨了解决温度漂移和进行线性化补偿的各种方法和措施,并选择了合适的方案对热敏电阻红外传感器轴温监测装置进行温漂补偿和线性化补偿,建立了用于轴温测量的软件系统和硬件系统.     

提高学生英语听力水平的途径和方法

目前在多数英语考试中都有听力测试,听力能力的提高不仅需要时间,还需要采用一些合理的方法途径进行针对性训练,方可避免盲目性,求得有限的时间内获得一定的效果。     

武术散手运动员赛前心理研究

在参考文献的基础上，对武术散手运动员赛前心理状态进行了分析，并提出调整赛前心理训练的方法，希望对散手教练员有一定的参考价值．     

The Gerontologist: Counselor and Coach

Effective communication is the core of every helping relationship. Trained and experienced gerontology counselors bring skillful listening, the gift of reframing, the ability to suspend judgment, experience with confidentiality and ethics, and the ability to seek solutions and think of possibilities to the evolving field of life coach. Therefore, whether the older client is seeking psychological counseling or a personal evolution and ways to live their life more fully, the gerontologist is the most suitable professional to address their concerns. If practitioners are to meet the rapidly increasing needs of Baby Boomers, academic programs need to train them to fill the role of both counselor and coach. Clients will make the determination of who is the best fit for their current concern.     

项链的L(1,2)-边标号(英文)

给定一个图G和2个正整数j和k,图G的一个m-L(j,k)-边标号是从图的边集到非负整数集合{0,1,…,m}的一个映射,该映射满足相邻的边所对应的整数相差至少为j,距离为2的边所对应的整数相差至少为k.在图G的所有m-L(j,k)-边标号中,最小的整数m称为图G的L(j,k)-边标号数,记为λ'j,k(G).项链是一类特殊的Halin图,研究了项链的L(1,2)-边标号,给出了项链的L(1,2)-边标号数的上界和下界,并且此上界和下界都是可达的.     

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.     

论远程教育管理模式的创新

远程教育教学模式的改革呼唤着管理模式的创新,而远程教育管理模式的创新作为教育创新的重要内容,包括了教学计划、教学过程、自主化学习小组、日常教学以及实践性教学等管理模式的创新,这也构成了一项特殊的系统工程.     

大学生足球运动员赛前心理分析与调适

随着大学生足球运动竞技水平的提高，竞争更加激烈，运动员赛前的心理调适和训练问题日益突出．．教练员可以通过系统的赛前心理训练，帮助运动员进行有效的自我控制，摆脱不良心理因素干扰，净化思维和集中注意力，充分发掘运动员的潜力，形成最佳的竞技状态?同时为大学生运动员健康成长打下良好的基础。     

Field experiment on train-induced embankment vibration responses in seasonally-frozen regions of Daqing, China

The seasonal-frozen layer may have an influence on embankment motion from train-induced vibrations. Based on the field monitoring in a seasonally-frozen region of northeastern China, the effects of the frozen layer on the embankment responses to train-induced vibration were investigated in winter and summer via acceleration time histories and acceleration frequency spectrums. The results show that： （1） Compared to unfrozen soil conditions, the amplitudes of longitudinal and vertical vibrations at the points near the rail were increased, different influences of freight versus high-speed trains are the most evident. （2） With greater distance from the rail, the dominant frequency ranges of embankment with both frozen and unfrozen layers narrowed and shifted to low frequency bands. （3） The predominant frequency of embankment vibration with frozen soil layers shifted to higher frequencies with the increased train speed, although there was little change with unfrozen condition. Layer condition （frozen versus unfrozen） and distance to rail both play important roles in investigating the embankment vibration characteristics and rail transit field monitoring to improve the criterion of the rail construction in seasonally-frozen regions.     

Thermal error compensation for telescopic spindle of CNC machine tool based on SIEMENS 840D system

In this paper, eddy current sensors and thermocouple sensors were employed to measure the thermal field and thermal deformation of a spindle of a telescopic CNC boring-milling machine tool, respectively. A linear regression method was proposed to establish the thermal error model. Furthermore, two compensation methods were implemented based on the SIEMENS 840D system by using the feed shaft of z direction and telescopic spindle respectively. Experimental results showed that the thermal error could be reduced by 73.79% when using the second compensation method, and the thermal error could be eliminated by using the two compensation methods effectively.