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Zhao Z.,Shijiazhuang University | Zhao Z.,Key Laboratory of Traffic Safety and Control of Hebei Province | Yang S.,Key Laboratory of Traffic Safety and Control of Hebei Province | Liu Y.,Key Laboratory of Traffic Safety and Control of Hebei Province
Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis

Aimed at feature extraction in machinery fault diagnosis, this paper proposes a new fault feature extraction method based on multi-wavelet coefficients. The original vibration signals of each fault category are decomposed into time-frequency representations using multi-wavelet transform. Then the maximum, minimum, mean and standard deviation of the multi-wavelet coefficients in each subband are calculated and used as the feature vector. The support vector machine method is used for machinery fault classification. Experiments are conducted on the real vibration signal of the roller bearing with normal conditions, inner fault, ball fault and outer fault. The experimental results indicate that the proposed approach can reliably identify the different fault categories, works better than the single wavelet method, and thus has potential for machinery fault diagnosis. ©, 2015, Nanjing University of Aeronautics an Astronautics. All right reserved. Source

Chen J.-J.,Shijiazhuang University | Chen J.-J.,Key Laboratory of Traffic Safety and Control of Hebei Province | Lu X.-K.,Shijiazhuang University | Lu X.-K.,Key Laboratory of Traffic Safety and Control of Hebei Province
Tiedao Xuebao/Journal of the China Railway Society

Introduction of energy saving gradient design into railway route profile optimization of high-speed railways is an effective way to reduce energy consumption and operation costs. High-speed railways are featured by high-speed traffic, long section distances and large curve radius, etc. These features make it complicated to apply energy saving gradient design in high-speed railway route profile optimization. In this paper, a mathematical nonliner constrained optimization mode for energy saving train operation was developed. The energy saving gradient design method was proposed on the basis of the table of control modes and the improved real-code genetic algorithm. This method made the energy saving gradient design applicable in high-speed railway section design. Test results prove that the proposed method can help to realize optimization of high-speed railway section energy saving gradient design in the largest scope of sections and to the highest extent. Source

Li H.-Y.,Shijiazhuang University | Li H.-Y.,Key Laboratory of Traffic Safety and Control of Hebei Province | Yang S.-P.,Shijiazhuang University | Qi Y.-Q.,Shijiazhuang University | Xu B.-Q.,Shijiazhuang University
Gongcheng Lixue/Engineering Mechanics

In order to study the interaction mechanism between vehicles and the pavement, a vehicle-pavement-subgrade interaction system is established by simplifying a moving vehicle as a 1/2 suspension model with four degrees of freedom and modeling the asphalt pavement as an infinite two-layer Kirchhoff plate on Kelvin foundation. By means of Fourier integral transform, the analytical solutions of dynamic responses of the pavement are derived by linking pavement surface roughness and a moving vehicle. The vibration characteristics of pavement under moving stochastic loads are analyzed by a numerical method. A parameter study then follows to show the effect of pavement surface roughness, loading capacity, suspension stiffness, suspension damping, tire stiffness, and tire damping on the dynamic responses of the pavement structure. A full systematic method to study the pavement damage due to vehicles is made. The results show that improving the pavement surface roughness level, prohibiting vehicle overload and tire overpressure, and optimizing suspension stiffness and suspension damping can reduce the dynamic response of the pavement structure effectively. The conclusions obtained from this work may be benefit to avoiding pavement early damage and extending pavement life-span. Source

Liu Y.,Shijiazhuang University | Liu Y.,Key Laboratory of Traffic Safety and Control of Hebei Province | Yang S.,Shijiazhuang University | Yang S.,Key Laboratory of Traffic Safety and Control of Hebei Province | Liao Y.,Shijiazhuang University
Journal of Intelligent Material Systems and Structures

A quantizing method, single parameter adjustment method (SPAM), is proposed so that the selection of controlled damping parameters of the magnetorheological (MR) damper models can be well founded. By using SPAM, only one parameter is identified each time, and the controlled damping parameters are selected according to their damping controllability. The relationships between the selected parameters and applied currents are determined by curve fitting. Genetic algorithm (GA) and pattern search (PS) are used to identify parameter values of the MR damper models. A modified Bouc-Wen model is considered and its parameters are obtained using these methods. Then the experimental data with different frequencies, amplitudes, and currents are used to verify the proposed SPAM. The results show that the simulation data agree well with the measured experimental data. Compared with the traditional identification method that relies on assumption and visual inspection, errors produced by SPAM are greatly reduced. At last, Bouc-Wen model and modified Dahl model are considered and analyzed using SPAM. © SAGE Publications 2011. Source

Chen J.,Shijiazhuang University | Chen J.,Key Laboratory of Traffic Safety and Control of Hebei Province | Lin S.,HCIG Communication Investment Co. | Jin L.,Equipment Technology Center | And 4 more authors.
Beijing Jiaotong Daxue Xuebao/Journal of Beijing Jiaotong University

Optimization on railway network in Hebei province was done under the background of the coordinated development of Beijing-Tianjin-Hebei (CDBTH). Firstly, based on analysis on the factors such as CDBTH, transport demand across Hebei province which affecting the railway network layout, according to the existing railway network, the preliminary scheme was achieved. Secondly, research object was divided into 20 traffic districts, passenger and freight volumes in 2020 and 2025 of 20 traffic districts were acquired by forecasting on traffic generation and traffic distribution. Then, the optimization scheme was obtained after traffic flow distributions. Lastly, the evaluation on the optimization scheme was done through the index of railway network density. The result shows the optimization scheme is reasonable and can meet the demand of economic development in the future in Hebei province. © 2016, Journal Northern Jiaotong University. All right reserved. Source

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