上海工程技术大学学报

Capacitance status identification of subway vehicles based on optimized VMD and energy relative entropy

LI Xiaobo, CAO Shuo, FENG Qiufeng, BAI Yannian, YANG Zhihao, ZHANG Hao

2024, 38(1): 1-6. doi: 10.12299/jsues.23-0083

Abstract:
Aiming at the problem that there is no obvious symptom of capacitance performance degradation on subway vehicles, a capacitance status identification method based on optimized variational mode decomposition (VMD) and energy relative entropy was proposed. By establishing a Matlab circuit model, the output voltage signals of the capacitance at normal status or different degradation conditions were extracted, then the characteristic samples were obtained by decomposition of optimized VMD. And the relative entropy analysis of the energy eigenvectors of the eigenmode components at the above status was carried out to obtain the identification threshold of capacitance degradation. In practical application, the relative entropy value of the energy of the circuit under test and the normal status was compared with the identification threshold to complete the capacitance status identification. The analysis result shows that this method can identify the capacitance status simply and effectively, and the accuracy is 93.3%.

[Abstract](232) [FullText HTML] (74) [PDF 1343KB](328)

Research on vehicle location of improved point cloud matching algorithm with laser odometer

ZHU Meng, MA Qihua

2024, 38(1): 7-14. doi: 10.12299/jsues.22-0282

Abstract:
Aiming at the problems that traditional iterative closest point (ICP) algorithm depends on initial position, long matching time and poor matching accuracy in the process of point cloud matching, a vehicle location method based on laser odometry improved point cloud registration algorithm was proposed. Firstly, point clouds were ordered and distorted point clouds were compensated in point cloud preprocessing. Then the static feature points were extracted stably after removing the dynamic feature points of the point cloud. Finally, in the process of point cloud registration, the point cloud was coarse registered to reduce the dependence of point cloud on the initial position, and then the bidirectional k-dimensional tree ICP algorithm was proposed for point cloud precise registration. Through the open source KITTI dataset and self-driving car platform for experimental test and analysis, the results show that compared with the traditional algorithm, the improved point cloud registration algorithm has faster matching speed and accuracy, small cumulative error of odometer trajectory.

[Abstract](232) [FullText HTML] (77) [PDF 2714KB](279)

Optimization of metro express stopping scheme based on OD pair of passenger flow

LI Yuhua, YANG Kaihe, DING Xiaobing, LIU Zhigang

2024, 38(1): 15-22, 69. doi: 10.12299/jsues.23-0111

Abstract:
In order to further determine the metro express stopping station, an optimization model of express stopping scheme based on origin-destination (OD) pair of passenger flow was established. Firstly, a road cost function was constructed to allocate OD passenger flow according to route cost. Secondly, taking the shortest travel time of passengers and the lowest operating cost of enterprises as the optimization objective, and taking multiple objective factors such as the cross section full rate, the station passenger flow demand, the number of times of the optimization period constraints as the model constraints, an express stop optimization model was builted according to passenger flow allocation. Finally, based on the basic data of metro line 16 in S city, the genetic algorithm with elite strategy and non dominated sorting, as well as GA hybrid (GA-NSGA-II) were used to solve the optimization model of stopping plan. The optimization results show that in peak hours, the per capita travel time of passengers is saved by 1.074 min, and the number of vehicles under each operation day is reduced by 6 columns.

[Abstract](205) [FullText HTML] (106) [PDF 1331KB](193)

Research on safety redundancy of automotive EPS system based on functional safety

CAO Zijian, WU Changshui, CHEN Li

2024, 38(1): 23-29. doi: 10.12299/jsues.23-0108

Abstract:
Electric power steering (EPS) system is a commonly used steering actuator for vehicles at present, and its failure will seriously affect the safety of drivers and passengers. A safety redundancy mechanism for the EPS system was established based on functional safety standards. Based on ISO26262, the EPS system was studied. Through the item definition, hazard analysis and risk assessment, the safety goal and functional safety requirements of the system were obtained and allocated. The architecture and fault-tolerant mechanism of EPS system were designed to improve the security of the system. Finally, the designed safety redundancy mechanism was tested on the bench. The results show that the system can achieve the expected response and meet the functional safety goal under the condition of fault injection such as unilateral bridge driver IC fault, unilateral motor position sensor fault and bilateral motor position sensor fault, which verifies the effectiveness of the designed safety redundancy mechanism.

[Abstract](455) [FullText HTML] (129) [PDF 1408KB](188)

Study on influence of pyramid baffle on PEMFC performance

WANG Yaochen, REN Hongjuan

2024, 38(1): 30-37. doi: 10.12299/jsues.22-0241

Abstract:
The flow channel structure of a proton exchange membrane fuel cell (PEMFC) has a significant impact on gas flow, diffusion and electrochemical reaction. By building the proposed three-dimensional PEMFC model of a pyramid-shaped baffle and running numerical simulations, the effects of different pyramid baffle ratios and baffle numbers on mass transfer and output performance of fuel cells were investigated. The results show that incorporating a pyramid baffle into the flow path can increase the vertical velocity component of the gas by up to 93.7% when compared to a flow path without baffle, thereby improving gas transfer performance from the flow path to the catalytic layer. When the pyramid baffle ratio is 0.25 and the number of baffles is 1, the net power of the fuel cell can reach a maximum of 0.107 W. Furthermore, increasing the baffle ratio and number of baffles can continuously improve mass transfer performance, but the flow path pressure drop can increase by up to 18.5%, which will reduce PEMFC output performance.

[Abstract](355) [FullText HTML] (219) [PDF 1866KB](705)

Influence analysis of parameters of bushing on oil film characteristics of piston/bushing interface in hydraulic piston pump

ZHU Xiling, ZHANG Yuhua

2024, 38(1): 38-43. doi: 10.12299/jsues.23-0175

Abstract:
To better the wear condition of the piston/bushing interface, the fluid-structure model was created, the interaction between fluid domain and solid domain was studied, the elastic deformations of the piston and bushing were considered, the impact of different thickness of bushing and material with different elastic moduli on the film thickness and deformations of bushing was discussed. The results show that the deformations of bushing decrease with increasing modulus of elasticity, bushing of copper lining materials with smaller elastic modulus or increasing of thicknesses of the bushing properly can improve lubrication conditions of the piston/bushing interface and the service life of the piston pump. Elastic deformations of piston and bushing have significant influences on the film thickness. The results provide a reference for the optimization design of the piston pumps.

[Abstract](152) [FullText HTML] (215) [PDF 1956KB](418)

Research on lightweight solver for welding thermal cycle based on Lagrange-Galerkin finite element method

ZHANG Hao, YE Xin, XIA Peng, PAN Nanxu, LI Xianfa, YU Tingting, ZHANG Pengfei

2024, 38(1): 44-49. doi: 10.12299/jsues.23-0152

Abstract:
The welding thermal cycle has many interfering factors, fast changing speed and wide influence range, so it is often necessary to predict and control them immediately to ensure the welding quality. Taking the temperature distribution and change of weld center as the research object, and it was simplified to the transient heat conduction problem of one-dimensional welding heat cycle. Based on Lagrange-Galerkin finite element method, a lightweight welding thermal cycle algorithm was developed to study the immediate changes of the temperature distribution curve and change curve of the weld center at different times. The results show that the calculation time is about 0.41~0.72 s, which meets the requirements of data and lightweight calculation.

[Abstract](256) [FullText HTML] (79) [PDF 1039KB](175)

Numerical simulation research of friction stir welding based on SPH method

HAN Zeping, CAO Lijie

2024, 38(1): 50-56. doi: 10.12299/jsues.23-0060

Abstract:
Smoothed particle hydrodynamics (SPH) is a meshless method based on Lagrangian. ABAQUS software was used to simulate the friction stir welding of AZ31B magnesium alloy based on the SPH method. By changing the rotation speed of the stirring too, the distributions of residual stress and temperature were studied. The results show that the distribution of residual stress on both sides of the weld is asymmetrical, and the stress on the retreating side is greater than that on the advancing side; the stress curve has bimodal characteristics, showing tensile stress in the welding area; as the rotational speed increases, the stress distribution of the workpiece becomes more uniform; the temperature distribution on both sides of the weld is asymmetrical, and the advancing side is higher than the retreating side, and the temperature rises with the increase of the rotational speed; the longitudinal temperature curve presents an M-shaped distribution. The simulation results have certain reference significance for the selection of welding parameters in the actual welding process.

[Abstract](215) [FullText HTML] (82) [PDF 1836KB](45)

Design and implementation of massage robot based on visual guidance

WU Xin, GONG Bin, YANG Hao, FANG Yu

2024, 38(1): 57-62. doi: 10.12299/jsues.23-0174

Abstract:
A traditional Chinese medicine (TCM) massage robot based on visual guidance was designed. By building a visual guidance platform, the massage robot platform was established based on the Franka multi-degree of freedom robotic arm, and the data mapping model between the two platforms was constructed. The robot arm was connected to the PC through the robot operating system (ROS) system to achieve real-time control. By integrating the optical motion capture technology with the multi-degree of freedom robotic arm, the learning and reproduction of TCM massage techniques were realized.

[Abstract](321) [FullText HTML] (124) [PDF 1789KB](60)

Force feedback control for variable parameter vascular interventional surgery robot based on terminal sliding mode

SUN Haoyue, HU Zhi

2024, 38(1): 63-69. doi: 10.12299/jsues.23-0082

Abstract:
Aiming at the problem of variable parameters and external disturbance in force feedback control system of master-slave vascular interventional surgery robot, a terminal sliding mode control method with continuous function characteristics was proposed. The parameters and changes of the force feedback control system of vascular interventional surgery were analyzed based on the calculation and force measurement methods. Then, a terminal sliding mode controller with continuous characteristic function was designed based on the terminal sliding mode control method, and the stability of the controller was proved by using the Lyapunov stability analysis method. Finally, simulation verification was carried out. It shows that from the two perspectives of tracking effect and controller output, the improved terminal sliding mode control method can not only effectively suppress chattering, but also improve the tracking accuracy of the signal, which proves that the strategy has important application value in improving the robustness and the control accuracy of variable parameter system.

[Abstract](256) [FullText HTML] (114) [PDF 1550KB](41)

Research on a new type of bolt axial force monitoring device

GAO Jian

2024, 38(1): 70-74. doi: 10.12299/jsues.23-0147

Abstract:
Most bolt axial force monitoring devices have complex structure, high cost, and are difficult to achieve real-time and effective judgment. A new type of anchor force monitoring device was proposed, that can judge the anchor force at this time by listening to the sound of different frequencies. Pro-E software was used to establish the entity model of the monitoring device was studied, ANSYS software was used to carry out statics and modal calculation of the monitoring device, and LMS Virtual.lab software was used to carry out acoustic simulation analysis of the device. The results show that the device is feasible and effective, and suitable for practical promotion and use.

[Abstract](172) [FullText HTML] (69) [PDF 1657KB](33)

Improved weed identification algorithm based on YOLOv5-SPD

YANG Zhifan, LI Haibo

2024, 38(1): 75-82. doi: 10.12299/jsues.23-0037

Abstract:
Accurate identification of weeds is the primary prerequisite for achieving machine replacement of manual weeding. The target of nascent weeds is small, making identification difficult. YOLOv5-SPD has good performance in small target recognition, but its robustness and accuracy still need to be improved. Adding channel attention mechanism on the basis of YOLOv5-SPD can strengthen the weight value of effective features, making the learning of the network more targeted. At the same time, replacing the generalized intersection over union (GIoU) loss function with complete intersection over union (CIoU) can effectively solve the problem of border coincidence, the height width ratio of the target box and the prediction box, and the relationship between the center point, there by making the weed prediction box closer to the real box. The experimental results on the weed dataset show that the improved network detection accuracy reaches 70.3% with an accuracy rate of 94.1% which is 4.7% and 2.8% higher than the original YOLOv5-SPD.

[Abstract](333) [FullText HTML] (102) [PDF 3649KB](54)

Self-training credit evaluation integrated classification model based on data editing

LIU Wenjie, WANG Guoqiang

2024, 38(1): 83-89. doi: 10.12299/jsues.23-0054

Abstract:
Aiming at the problems of unbalance of credit data and difficult acquisition of label data, a self-training credit evaluation integrated classification model based on data editing was proposed. Firstly, synthetic minority over-sampling technique (SMOTE) was used to sample labeled samples to alleviate data imbalance. Secondly, a Stacking integration model was constructed on a few labeled sample datasets and unlabeled samples were "falsified" to obtain label-like data. Finally, an improved semi-supervised double-weighted K-nearest neighbor algorithm was proposed, which was used to clip the pseudo-label data and expand the training set until the model converged. Simulation experiments of UCI and Kaggle credit evaluation dataset show that the model has better predictive performance and can identify a few types of samples more effectively.

[Abstract](169) [FullText HTML] (81) [PDF 775KB](39)

Effect of magnetic shearing on thermal transport of electrons in magnetic islands

LI Zekun, XIA Qinghao, ZHA Xuejun

2024, 38(1): 90-95, 100. doi: 10.12299/jsues.23-0029

Abstract:
The influence of magnetic shear parameters on the electron temperature distribution and heat transport in the magnetic island were studied by numerically solving the tokamak plasma energy transport equation. The results show that for different radial distributions of the safety factor, the magnitude of the magnetic shear parameter will affect the magnitude of the effective radial heat transport coefficient. The higher the shear degree, the greater the effective radial heat transport ${\chi _r}$ coefficient. And when the magnetic field perturbation degree is high enough, the effect of high shear on radial heat transport ${\chi _r}$ will be reduced.

[Abstract](109) [FullText HTML] (54) [PDF 2769KB](34)

Optimal control of acceptance ratio for feed cabin of China's Eye of Heaven

TANG Yuxiang, WANG Chenyang, YAO Weiyi, FANG Tao

2024, 38(1): 96-100. doi: 10.12299/jsues.23-0058

Abstract:
A mathematical model was established to optimize the acceptance ratio of the feed cabin of China's Eye of Heaven, the Five-hundred-meter Aperture Spherical Telescope (FAST), and the ideal parabolic equation of the reflector of FAST system was obtained. The adjustment scheme of the main cable node of the system was given based on the genetic algorithm. The numerical simulation shows that the reception ratio of the feed cabin is 61.43% when the observed celestial body's azimuth is 36.795° and elevation is 78.169°. The acceptance ratio of the feed cabin is about 55.97 percentage points higher than the base sphere.

[Abstract](373) [FullText HTML] (91) [PDF 1078KB](45)

Influence of willingness to accept fashion sharing in context of sustainable development

WANG Hongfeng, ZHANG Yunhe, ZHU Xiaoyu, TIAN Bingqiang, QU Hongjian

2024, 38(1): 101-110. doi: 10.12299/jsues.22-0350

Abstract:
Taking fashion sharing as the research object, a theoretical model of fashion sharing influencing factors and acceptance willingness was constructed on the basis of literature review. Based on the questionnaire survey data, factor and regression analysis were used to verify the relationship and influence. The study shows that economic benefits, fashion participation, self-pleasure experience, social projection, past sustainable behaviors, and shared services all affect the willingness to accept fashion sharing positively; perceived risk does not play a mediating role, and perceived value has a positive impact on factors influencing fashion sharing and willingness to share. Gender has a positive moderating effect between economic interests, self-pleasure experience and willingness to accept fashion sharing. The research conclusions can provide practical inspiration for the development of fashion sharing market.

[Abstract](147) [FullText HTML] (73) [PDF 750KB](31)

2024 Vol. 38, No. 1