Zhang H.,Harbin Institute of Technology |
Cao J.,Harbin Institute of Technology |
Lu H.,CSR Qingdao SiFang Locomotive and Rolling Stock CO.
Advanced Materials Research | Year: 2010
Joining Cu to Al has been carried out by vacuum contact reactive brazing without filler metal. Experimental results obtained showed that the eutectic structure and some Cu-Al intermetallic compounds were the main phases of the braze seam. The fracture surface of the joint presented typical brittle fracture for the existence of intermetallic compounds at the interface and the shear strength could reach 65MPa. © (2010) Trans Tech Publications.
Ji S.,Shenyang Aerospace University |
Meng X.,Shenyang Aerospace University |
Ma L.,Shenyang Aerospace University |
Lu H.,CSR Qingdao Sifang Locomotive and Rolling Stock Co. |
Gao S.,Shenyang Aerospace University
Materials and Design | Year: 2015
Vertical compensation friction stir welding (VCFSW) was developed to solve the existence of a big gap at the interface between two workpieces to be welded. By a self-designed tool system with external stationary shoulder, VCFSW is successfully used to weld 6061-T6 aluminum alloy with the thickness of 4. mm, while 2024-T4 aluminum alloy is chosen as compensation material. When using a traditional tool, it is difficult for VCFSW to attain a sound joint if the width of compensation strip is no less than 1.5. mm. The self-designed stationary shoulder tool system is more suitable for VCFSW. Defect-free VCFSW joints using the self-designed stationary shoulder are attained when the widths of strip vary from 1. mm to 2. mm. For VCFSW process, increasing the rotational velocity and decreasing the welding speed are beneficial to break the compensation strip into pieces to get the higher quality welding joint. When the width of compensation strip is 1. mm, the tensile strength and elongation of joint by the stationary shoulder tool system reach the maximum of 75.1% and 58.8% of base material (BM) when using the welding speed of 50. mm/min and rotational velocity of 2000. rpm, respectively. The fracture surface morphology of VCFSW joint presents the typical ductile fracture. © 2014 Elsevier Ltd.
Xi Y.-H.,Beijing Jiaotong University |
Mao J.,Beijing Jiaotong University |
Gao L.,Beijing Jiaotong University |
Yang G.-W.,CAS Institute of Mechanics |
Qu W.-Q.,CSR Qingdao Sifang Locomotive and Rolling Stock Co.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2012
The limited safe speed of a high-speed train under crosswind should be obtained by analyzing the aerodynamic and vehicle-track dynamic characteristics. A real high-speed train of Type CRH3 was taken for case study. The train was assumed to run on a plane area under 25 numerically simulated operating conditions when the train speeds were chosen as 200, 250, 300, 350 and 380 km/h, the crosswind velocities as 10, 15, 20, 25 and 30 m/s and the wind direction angle as 90°. The detailed characteristics of real bogies and pantographs and so on were taken into account. The dynamic vehicle-track charateristics corresponding to the above 25 operating conditions were calculated respectively and compared in line with the domestic measured track spectra and the German track spectra. In accordance with the National standards and technical specifications concerned, the relationship between the crosswind velocity and the maximum safe operating speed of the CRH3 train running on a plane area was found. The results will play a guiding role in control of safe operation of a train under crosswind.
Wen Y.,Beijing Jiaotong University |
Ma Y.,CSR Qingdao Sifang Locomotive and Rolling Stock Co. |
Zhang X.,Beijing Jiaotong University |
Jin X.,Beijing Jiaotong University |
Wang F.,Beijing Jiaotong University
Proceedings of the 2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC'12 | Year: 2012
In this paper, based on the measured data at Wuhan-Guangzhou high speed railway, the statistics characteristics of high speed mobile fading channel including long-term and short-term fading in this environment are presented. The measurement campaigns were conducted at GSM-R downlink band. The experimental data was analyzed to provide path loss model and short-term fading statistics including probability density functions (PDF) of signal amplitude, delay statistics, number of paths and path power statistics. From these statistics, it is shown that the path loss index at this railway area is n=2̃5 with standard deviation ranging from 3 to 6dB; the test PDF of the short-term fading in such channels approximately fit Nakagami distributions better; the cumulative density functions of average delay and root mean square delay demonstrated that the mean and root mean square delay are not larger than respectively 1.37μs and 1.69μs and maximum delays less than 6.7μs occur most frequently. At last, the PDFs of paths and PDFs of relative amplitude of paths with different threshold levels were computed and drawn. © 2012 IEEE.
Liang J.,CSR Qingdao Sifang Locomotive and Rolling Stock Co. |
Rong Z.,CSR Zhuzhou Institute Co. |
Zhang Z.,CSR Zhuzhou Institute Co. |
Luo W.,CSR Zhuzhou Institute Co.
Lecture Notes in Electrical Engineering | Year: 2016
A series of train net matching problems arising from the high-order harmonics of AC drive trains have severely affected the safe operation of the railway system. For the sake of analyzing and solving the problems in a systematic way, some basic conclusions and laws are obtained on the basis of making theoretical analysis for the traction current control model and harmonic characteristic of AC drive trains, and through considering the impedance model of traction nets and making the detailed simulation analysis for the voltage harmonic of traction nets, the harmonic relationship between current and voltage, as well as the train net system harmonic coupling relationships such as the mutual effect of harmonics when multiple locomotives are running, which provide guidance and reference for analyzing the practical problems and studying the subsequent suppression techniques in engineering application. © Springer-Verlag Berlin Heidelberg 2016.
Liu Z.,Northeastern University China |
Wang J.,Northeastern University China |
Wang H.,CSR Qingdao Sifang Locomotive and Rolling Stock Co.
Proceedings - 2011 International Conference on Cyber-Enabled Distributed Computing and Knowledge Discovery, CyberC 2011 | Year: 2011
To deal with the problem of tracking a maneuvering target in range-based sensor networks, we firstly derive the expression that describes the relation of the PCRLB and the distance from the sensor to the target, and on the basis of this expression, choose the sensor subset that may attend the incoming tracking event. Secondly, we design the cluster head selection strategy under communication constraint, and further pick up the optimal sensor or the cluster head. Thirdly, we can estimate the state of the maneuvering target and the model index by making use of the interacting multiple model (IMM) algorithm. Finally, the simulation results show the effectiveness of the proposed scheme. © 2011 IEEE.
Lu H.,Northeastern University China |
Zhang Y.,Northeastern University China |
Zhao C.,CSR Qingdao Sifang Locomotive and Rolling Stock Co. |
Zhu L.,Northeastern University China
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2012
Several potential failure modes may occur when mechanical components fail. For that all the failure modes have a certain impact on the reliability sensitivity of the components, it is necessary to take each failure mode into account as a reliability sensitivity estimation is performed. A reliability sensitivity analysis method for mechanical components with multiple failure modes is proposed. Concerning the unknown distributions of random variables, the random perturbation technique and the fourth moment method are employed to respectively calculate the first four moments and the reliability index of each performance function of the failure mode. The potential failure modes, only a few existed in the component, are regarded in series, and the failure of the component is thus the failure of a series system. The calculating formulas of reliability sensitivity with respect to the mean and variance of random variables are derived with the gradient method. The numerical example illustrates that the proposed method could quickly and effectively estimate the reliability sensitivity of the mechanical components with multiple failure modes, and is also applicable for nonlinear performance functions. ©2012 Journal of Mechanical Engineering.
Wu H.-C.,State Key Laboratory of Traction Power |
Wu P.-B.,State Key Laboratory of Traction Power |
Zeng J.,State Key Laboratory of Traction Power |
Wu N.,State Key Laboratory of Traction Power |
Shan Y.-L.,CSR Qingdao Sifang Locomotive and Rolling Stock Co.
Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering | Year: 2012
In order to consider the elastic vibration of carbody, the vertical coupling vibration model of carbody and equipment was established, the influence of rigid suspension and flexible suspension on the amplitude-frequency characteristic of carbody was studied, in which carbody was modeled as an Euler-Bernoulli beam. The 3D rigid-flexible coupling dynamics model of high-speed EMU was set up based on the modal superposition method and considering carbody elastic vibration and equipment, the influence of equipment's suspension types, partial loads and suspension parameters on carbody vibration was andyzed. The numerical analysis result of Euler-Bernoulli beam model shows that reasonable elastic suspension design based on the principle of dynamic vibration absorber can effectively suppress the elastic vibration of carbody and improve the vertical bend frequency of carbody. The simulation result of 3D rigid-flexible coupling dynamics model shows that the higher the speed is, the more obvious the advantage of elastic suspension is, equipment's lateral partial load affects the lateral riding index of carbody, and the longitudinal partial load mainly affects the vertical riding index. When the flexible suspension frequency of equipment is close to carbody bend frequency, the minimum vibration of carbody occurs. But as the suspension frequency of equipment is less than carbody bend frequency, rising damping can suppress carbody vibration to some extent.
Lu F.,North China Electrical Power University |
Guo Y.,North China Electrical Power University |
Li P.,CSR Qingdao Sifang Locomotive and Rolling Stock Co.
Gaodianya Jishu/High Voltage Engineering | Year: 2016
In order to accurately estimate leakage inductance in the design of high-power medium frequency transformer(MFT), on the basis of a one-dimensional leakage magnetic field model of MFT, we derived an analytical equation for leakage inductance of MFT by an energy method which is based on the characteristic of its distribution. Thereby, the conductivity of the winding and calculation altitude of the leakage magnetic field was corrected based on the difference between idealized assumptions and actual situation. Moreover, leakage inductance of two prototypes was calculated and measured from 50 Hz to 10 kHz, verifying that error could be reduced to less than 5% by correcting both the parameters. The reasons for the still existing error were analyzed. The comparison between prototype 1 and 2 demonstrates that cross arrangement for the windings can reduce the leakage inductance value of the transformer. © 2016, High Voltage Engineering Editorial Department of CEPRI. All right reserved.
Song X.,Northeastern University China |
Wang J.,Northeastern University China |
Li Q.,Northeastern University China |
Wang H.,CSR Qingdao Sifang Locomotive and Rolling Stock Co.
2012 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2012 | Year: 2012
The constant modulus algorithm (CMA) has been known as blind adaptive beamforming because it requires no knowledge about the signal except that the transmitted signal waveform has a constant envelope. But in practical applications, the performance of the linearly constrained CMA is known to degrade severely in the presence of even slight signal steering vector mismatches. To account for the mismatches, a novel robust CMA algorithm is proposed via the oblique projection of signal steering vector. To improve robustness, the weight vector is optimized to involve minimization of a constant modulus algorithm objective function with penalty for the worst-case signal steering vector by the Lagrange multiplier method, in which the parameter can be precisely derived at each iterative step. Moreover, the performance analysis of the proposed algorithm is presented in this paper. The proposed robust constrained CMA provides a significantly improved robustness against the signal steering vector mismatches and improves the mean output array SINR as compared with the conventional constrained CMA. The simulation experiments have been carried out to demonstrate the superiority of the proposed algorithm on beampattern control and output SINR enhancement. © 2012 IEEE.