scholarly journals High-Speed Train Emergency Brake Modeling and Online Identification of Time-Varying Parameters

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yongze Jin ◽  
Guo Xie ◽  
Pang Chen ◽  
Xinhong Hei ◽  
Wenjiang Ji ◽  
...  
Keyword(s):  
Expectation Maximization ◽  
High Speed ◽  
Sliding Window ◽  
Time Varying ◽  
High Speed Train ◽  
Online Identification ◽  
Proposed Model ◽  
Uniform Noise ◽  
Gradient Optimization ◽  
Relative Errors

By analyzing the mechanism of pure air emergency brake for high-speed train, the discrete emergency brake model is established. Aiming at the problem that time-varying hidden parameters cannot be observed directly, the sliding window-based expectation maximization is proposed, and the unobserved time-varying brake parameters are identified. Firstly, the position and size of the sliding window are selected; then, the sliding window-based expectation maximization is used for brake parameter identification; finally, combined with the gradient optimization, the optimal identifications of emergency brake parameters are obtained. The simulation results show that the brake parameters can be identified quickly and accurately by the proposed method. Under uniform noise, the identification errors of friction coefficient and braking ratio are ±0.0068 and ±0.0349, respectively, and the maximum relative errors between the identifications and true values are 2.4807% and 1.3154%, respectively, which can meet the actual requirements of the brake system. The effectiveness and practicability of the proposed model and method are verified.

scholarly journals Transient Temperature Field Model of Wear Land on the Flank of End Mills: A Focus on Time-Varying Heat Intensity and Time-Varying Heat Distribution Ratio

2019 ◽  
Vol 9 (8) ◽  
pp. 1698 ◽  
Author(s):  
Du ◽  
Yue ◽  
Liu ◽  
Liang ◽  
Wang ◽  
...  
Keyword(s):  
Temperature Field ◽  
High Speed ◽  
Field Model ◽  
Transient Temperature ◽  
Time Varying ◽  
Peripheral Milling ◽  
Transient Temperature Field ◽  
Proposed Model ◽  
Temperature Field Model ◽  
End Mills

Modelling methods for the transient temperature field of wear land on the flank of end mills have been proposed to address the challenges of inaccurate prediction in the temperature field of end mills during the high-speed peripheral milling of Ti6Al4V that is a titanium alloy. A transient temperature rise model of wear land on the flank of end mills was constructed under the influence of heat sources in the primary shearing zone (PSZ), rake-chip zone (RCZ), flank-workpiece zone (FWZ), and dissipating heat source. Then the transient temperature field model of wear land on the flank of end mills was constructed. Finally, the transient temperature field model of wear land on the flank of end mills was constructed. Comparison of simulation result and experimental data verified the accuracy of the model. In sum, the proposed model may provide a temperature model support for future studies of flank wear rate in end mill modeling.

Identification of braking model for high speed train by using expectation maximization

2017 ◽  
Author(s):  
Yongze Jin ◽  
Guo Xie ◽  
Fucai Qian ◽  
Xinhong Hei ◽  
Xiaofan Wang ◽  
...  
Keyword(s):  
Expectation Maximization ◽  
High Speed ◽  
High Speed Train

scholarly journals A High-Speed Train Operation Plan Inspection Simulation Model

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Yang Rui ◽  
Mou Ruifang ◽  
Jiang Feng
Keyword(s):  
Information Transfer ◽  
High Speed ◽  
Random Disturbance ◽  
Simulation Tool ◽  
High Speed Train ◽  
Network Function ◽  
Proposed Model ◽  
Train Operation ◽  
Test Requirements ◽  
Location Change

We developed a train operation simulation tool to inspect a train operation plan. In applying an improved Petri Net, the train was regarded as a token, and the line and station were regarded as places, respectively, in accordance with the high-speed train operation characteristics and network function. Location change and running information transfer of the high-speed train were realized by customizing a variety of transitions. The model was built based on the concept of component combination, considering the random disturbance in the process of train running. The simulation framework can be generated quickly and the system operation can be completed according to the different test requirements and the required network data. We tested the simulation tool when used for the real-world Wuhan to Guangzhou high-speed line. The results showed that the proposed model can be developed, the simulation results basically coincide with the objective reality, and it can not only test the feasibility of the high-speed train operation plan, but also be used as a support model to develop the simulation platform with more capabilities.

scholarly journals A Discrete-Space Train Movement Model for a High-Speed Train under Temporary Speed Restriction

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Sihui Long ◽  
Lingyun Meng ◽  
Yihui Wang ◽  
Jianrui Miao ◽  
Xuan Li
Keyword(s):  
High Speed ◽  
Discrete Space ◽  
High Speed Train ◽  
Time Duration ◽  
Movement Model ◽  
High Speed Railway ◽  
Running Time ◽  
Proposed Model ◽  
The Impact ◽  
Block Section

This paper constructs a discrete-space train movement model to evaluate the impact of a temporary speed restriction (TSR) for a high-speed railway train. The established model can demonstrate train movement under different TSR conditions. The proposed model can reveal whether a train is affected by the block section influenced by the TSR within a time duration. Moreover, the model can output detailed train trajectories and the minimal train running time between two adjacent stations to analyse the impact of the TSR. Based on the experimental results, we carry out a comprehensive analysis of the impact of several factors on the running time and train trajectories, including the length of the affected area (i.e., number of affected block sections), the location of the TSR, the limited speed value, and the stopping patterns of the train at two adjacent stations. The experiments show that the proposed discrete-space train movement model can be used to analyse the impact of the TSR on a high-speed railway train under various considered TSR conditions.

scholarly journals Vibration and Stress Response of High-Speed Train Gearboxes under Different Excitations

2022 ◽  
Vol 12 (2) ◽  
pp. 712
Author(s):  
Wangang Zhu ◽  
Wei Sun ◽  
Hao Wu
Keyword(s):  
High Speed ◽  
Dynamic Stress ◽  
Coupling Model ◽  
Transmission Model ◽  
Railway Vehicle ◽  
Time Varying ◽  
High Speed Train ◽  
Dynamic Stresses ◽  
Vibration Data ◽  
Polygonal Wear

The vibration data of the gearbox on a high-speed train was measured, and the vibration characteristics were analyzed in this paper. The dynamic stress of the gearbox under the internal and external excitation was examined by a railway vehicle dynamic model with a flexible gearbox and a flexible wheelset. The ideal 20th polygonal wear was considered, and dynamic stresses of the gearbox under different polygonal wear amplitudes were calculated. The gear transmission model was established to study the dynamic stress of the gearbox under the influence of the time-varying stiffness of the gear meshing. Based on the rigid–flexible coupling model, and considering the influence of wheel polygonization, gear meshing time-varying stiffness, and wheelset elastic deformation, the dynamic stress of the gearbox was investigated with consideration of the measured polygonal wear and measured rail excitation. The results show that the dynamic stress of the gearbox is dominated by the wheel polygonization. Moreover, not only the wheel polygonization excites the resonance of the gearbox, but also the flexible deformation of the wheelset leads to the deformation of the gearbox, which also increases the dynamic stress of the gearbox. Within the resonant bandwidth of the frequency, the amplitude of the dynamic stresses in the gearbox will increase considerably compared with the normal case.

Vibration analysis of the axle bearings considering the combined errors for a high-speed train

2020 ◽  
Vol 234 (3) ◽  
pp. 481-497
Author(s):  
Jing Liu ◽  
Xinbin Li ◽  
Wennian Yu
Keyword(s):  
High Speed ◽  
Error Model ◽  
Manufacturing Processes ◽  
High Speed Train ◽  
The Road ◽  
Critical Elements ◽  
Proposed Model ◽  
Manufacturing Errors ◽  
High Speed Trains ◽  
Track Irregularities

Axle bearings are critical elements of high-speed trains. Although the quality and precision of axle bearings have been significantly improved, the manufacturing errors, such as the roundness and waviness errors, cannot be eliminated during their manufacturing processes. The axle bearings with the roundness and waviness errors have great influences on vibration performances of the high-speed trains. To obtain an in-depth understanding of the vibrations caused by the axle bearing with the combined errors considering both the roundness and waviness errors. This work conducts an improved analytical model for a high-speed train considering the axle bearings with the combined errors, which cannot be formulated by the previous train model considering single roundness or waviness errors. The combined errors are defined to include both the roundness and waviness errors. A new multiple cosine function is presented to model the combined errors. The time-depended force excitations produced by the combined errors are also considered in the dynamic model. A track irregularities model is utilized to formulate the road spectrum displacement excitations from the rail and roadbed. The influences of the error amplitude and order on the vibrations of high-speed train are analyzed. The results for the single roundness error model, single waviness error model, and combined errors model are compared to represent the superiority of proposed model. It depicts that this work can provide a more reasonable analytical method for understanding the vibrations of high-speed train considering the axle bearings with the combined manufacturing errors compared to the reported single error models.

Analysis of the Influence of Racks on High Speed Train Interior Noise Using Finite Element Method

2014 ◽  
Vol 675-677 ◽  
pp. 257-260 ◽  
Author(s):  
Di Wu ◽  
Jian Min Ge
Keyword(s):  
Finite Element ◽  
Sound Pressure Level ◽  
High Speed ◽  
Sound Pressure ◽  
Low Frequency ◽  
Sound Field ◽  
Pressure Level ◽  
High Speed Train ◽  
Fe Method ◽  
Proposed Model

In this paper, the finite element (FE) method was used for simulation of the low-frequency sound field in high speed train compartments. The proposed model was validated using experimental results. The FE models of the train compartments with and without racks were established respectively, and the sound pressure level of the standard point and sound field distribution in these two cases were compared. The results showed that the A-weighted sound pressure level of the standard point was 1.2 dB lower when there is no rack in the compartment.

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