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Table of Content

    28 March 2023, Volume 57 Issue 3 Previous Issue    Next Issue
    Mechanical Engineering
    Multi-Physics Field Coupling Simulation of Induction Leveling Process
    LIU Xuyang, CAI Changru, ZHAO Yixi, JU Liyang
    2023, 57 (3):  253-263.  doi: 10.16183/j.cnki.jsjtu.2021.312
    Abstract ( 503 )   HTML ( 4272 )   PDF (9849KB) ( 417 )   Save

    The electromagnetic induction leveling method has the characteristics of high efficiency and easy operation. It has a good application prospect in the thin plate leveling process. Based on the fixed inline coil induction leveling process used by the shipyard, this research uses COMSOL Multiphysics to establish a three-dimensional electromagnetic-thermal-mechanical coupling induction leveling finite element model. The model inputs the temperature-dependent physical properties as the material properties of the AH36 steel plate, and takes the residual stress and welding deformation of the butt weldment as the initial state. The method of sequential coupling is used to calculate the changes of electromagnetic field, temperature field, and structure field during the leveling process. The two-way coupling relationship between the temperature field and the electromagnetic field is verified and the deformation of the welded part after leveling is obtained. Through the self-built induction leveling experiment platform, the accuracy and effectiveness of the finite element model are verified.

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    Deformation Analysis and Optimal Design of Membrane for Differential Pressure Capacitance Sensor
    ZHAO Zhao, LEI Huaming
    2023, 57 (3):  264-272.  doi: 10.16183/j.cnki.jsjtu.2021.281
    Abstract ( 315 )   HTML ( 1132 )   PDF (2929KB) ( 169 )   Save

    The compression deformation of the measuring membrane of the differential pressure capacitance sensor is studied. The classical von Kármán thin plate theory is applied to the elastic circular thin plate subjected to pretension, and the approximate analytical solution is given by adopting the homotopy analysis method. The results are compared with the simulation results of the finite element software ANSYS, which shows that they have a high degree of agreement. The magnitude of pretension has a great influence on the deformation of the membrane under compression, thus affecting the capacitance output characteristics of the sensor. The effect of pretension on the nonlinear characteristic of the sensor is verified by the sensor performance test. The results suggest that the linearity of the sensor can be effectively improved by selecting the appropriate pretension, and the sensitivity of the output can be improved by appropriately reducing the membrane thickness. The analysis results have an important reference value for the design of membrane of differential pressure capacitance sensors.

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    Joint Group Maintenance Scheduling and Team Collaboration Sharing Strategy for Multi-Center Leasehold Manufacturing Network
    SI Guojin, LIN Zeyu, ZHENG Yu, XIA Tangbin, XI Lifeng
    2023, 57 (3):  273-284.  doi: 10.16183/j.cnki.jsjtu.2022.074
    Abstract ( 244 )   HTML ( 1065 )   PDF (3729KB) ( 199 )   Save

    With the wide application of the service-oriented manufacturing mode, the scale of leasing manufacturing enterprises continues to expand, which leads to the global multi-regional development of maintenance outsourcing services. To address the multi-location maintenance scheduling problem of multi-center leasehold networks in the provision of “products+services”, this paper proposes a multi-center collaboration maintenance scheduling (MCMS) strategy with the dynamic interaction between the system level and the network level. At the system level, it considers the impact of the maintenance downtime, cumulative failure, and system combination selection on maintenance decisions, then optimizes the maintenance grouping of machines in the same manufacturing system. Based on the proposed optimization model, the group maintenance set and the corresponding maintenance start time can be obtained by minimizing the total maintenance cost. At the network level, it further considers the impact of service routing optimization, team dispatch selection, and maintenance response speed on scheduling decision, and then outputs the optimal service route for each team by minimizing the total scheduling cost. It also verifies the feasibility and cost-effectiveness of the MCMS strategy in the field of multi-location maintenance scheduling problems by analyzing the case study.

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    Multi-Level Optimization Policy of Opportunistic Maintenance and Inventory Control of k-out-of-n System
    CAO Lei, AN Xiangxin, XIA Tangbin, ZHENG Meimei, XI Lifeng
    2023, 57 (3):  285-296.  doi: 10.16183/j.cnki.jsjtu.2022.030
    Abstract ( 265 )   HTML ( 191 )   PDF (2485KB) ( 169 )   Save

    For the maintenance outsourcing requirements of complex systems in service-oriented manufacturing, a multi-level optimization policy of opportunistic maintenance and inventory control (OMICP) is proposed by considering the challenges of redundant machine interference, high shutdown penalty, and spare parts inventory limit of k-out-of-n: G system. At the machine layer, the degeneration model of each machine is built. Then, preventive maintenance cycles of each machine are outputted in sequence by minimizing the maintenance cost rate. At the system level, these maintenance time points are taken as opportunities. In addition, a dynamic combination opportunistic maintenance policy is established by comprehensively considering inventory level, shutdown quantity, and redundancy interference. At the joint level, based on the opportunistic maintenance decision feedback, the inventory control policy is updated in real time by modeling and analyzing the profit balance of spare parts ordering. Through this multi-level interactive decision-making under outsourcing maintenance, the coupling relationship between complex system maintenance and inventory control is integrated to optimize the total cost of maintenance outsourcing services. The case study has shown that OMICP has the feasibility of complex decision-making and the effectiveness of cost optimization.

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    A Pallet Recognition Method Based on Adaptive Color Fast Point Feature Histogram
    ZHAN Yan, CHEN Zhihui, ZHU Baochang, ZHU Tingting, SHAO Yiping, LU Jiansha
    2023, 57 (3):  297-308.  doi: 10.16183/j.cnki.jsjtu.2021.301
    Abstract ( 326 )   HTML ( 169 )   PDF (14142KB) ( 441 )   Save

    Pallet recognition is one of the critical technologies of cargo handling for unmanned industrial vehicles. A pallet recognition method based on adaptive color fast point feature histogram (ACFPFH) is proposed to solve the problems of current recognition methods such as low efficiency, time-consuming, poor robustness and random parameter selection. The Kinect V2 sensor is used to collect the point cloud data which represents the whole scene including pallet. Next, outliers are removed and the optimal neighborhood radius of each point is obtained based on the minimum criterion of neighborhood feature entropy function. Then, the key points are extracted from scene point clouds. The ACFPFH consisting of color feature and adaptive geometric feature is applied for similarity matching between the template and scene point clouds. Finally, wrong feature correspondences are rejected and the pallet in the scene point cloud is recognized. A comparison of the fast point feature histogram with the fixed neighbor radius of 0.012 m shows that the pallet recognition precision and efficiency of the method based on ACFPFH is improved by 83.74% and 35.55% respectively, which verifies the superiority of the proposed method.

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    Comprehensive Analysis of Geometric Model of a Variable Thickness Scroll Expander
    ZHANG Pengcheng, PENG Bin, MA Jie
    2023, 57 (3):  309-315.  doi: 10.16183/j.cnki.jsjtu.2022.354
    Abstract ( 258 )   HTML ( 162 )   PDF (2891KB) ( 280 )   Save

    A novel variable thickness scroll expander composed of involutes of circle with different base circle radii is proposed. The generating method of profile is discussed, the general equation of profile is given, and a series of geometric models of the variable thickness scroll expander are established. According to the established geometric model, the influence of control coefficient on the volume change of the variable thickness scroll expander is analyzed. In addition, the geometric models of the traditional equal constant thickness and variable thickness scroll expander are constructed, and the advantages and disadvantages of the geometric models are compared. The results show that the novel variable thickness scroll expander model not only has the advantages of the traditional variable thickness model, but also greatly reduces the amount of calculation. To a certain extent, it enriches the types of variable thickness scroll expanders and provides reference for the development of high-performance scroll expanders.

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    Boiler Load Forecasting of CHP Plant Based on Attention Mechanism and Deep Neural Network
    WAN Anping, YANG Jie, MIAO Xu, CHEN Ting, ZUO Qiang, LI Ke
    2023, 57 (3):  316-325.  doi: 10.16183/j.cnki.jsjtu.2021.346
    Abstract ( 238 )   HTML ( 153 )   PDF (4458KB) ( 469 )   Save

    Accurate boiler load forecasting of cogeneration units plays a direct role in production management and dispatching of power plants. A long-term load forecasting model of combined heat and power (CHP) based on attention mechanism and the deep convolution long-short-term memory network (CNN-LSTM-AM) is proposed, which takes the historical data of boiler outlet steam flow (load) and multi-dimensional load influence factors as input to make long-term load forecasting. First, the original data is screened by Pearson correlation coefficient judgment. Then the processed data is processed by convolution layer for feature extraction and further dimensionality reduction, fitted through long-term and short-term memory layer, and optimized the weight by adopting attention mechanism, so as to achieve accurate load forecasting. The proposed model is verified by the measured data of Tongxiang Power Plant in Zhejiang Province. The results show that the MAPE of the proposed method is less than 1%. It can realize the accurate prediction of boiler load, which has a certain reference significance for the application of intelligent algorithm in the field of combined heat and power.

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    Experimental Study of Flame Characteristics in Simple Cubic Packed Beds
    YIN Zhicheng, WANG Ping, JIANG Linsong, SUN Ying, HE Zuqiang
    2023, 57 (3):  326-334.  doi: 10.16183/j.cnki.jsjtu.2021.317
    Abstract ( 223 )   HTML ( 165 )   PDF (7671KB) ( 194 )   Save

    The combustion of porous media is characterized by high efficiency and good stability. A simple cubic packed structure consisting of an alumina particle packed bed and double-layer silicon carbide foam ceramics was proposed to study the filtration combustion characteristics of the structure. By changing the premixed gas equivalent ratio and inlet velocity, the flammability limit of flame, flame propagation law, CO emission law, and combustion efficiency under different working conditions were studied. It is found that the stabilization and propagation of the flame depend on the regional temperature, the equivalent ratio, and the velocity. In the bed with a particle diameter of 40 mm, the flame is easy to spread and the combustion efficiency is high, while in the bed with a particle diameter of 20 mm, the flame is more stable.

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    Driving Dynamic Characteristics of Multi-Axle Special Vehicles in Shortage of Tires
    HUANG Tong, GAO Qinhe, LIU Zhihao, WANG Dong
    2023, 57 (3):  335-344.  doi: 10.16183/j.cnki.jsjtu.2021.236
    Abstract ( 259 )   HTML ( 138 )   PDF (7603KB) ( 193 )   Save

    In order to investigate the driving characteristics of multi-axis special vehicle under the limit condition of missing tires, a five-axis special vehicle dynamics simulation test model including vehicle parameters, power transmission and braking system, axle and suspension system, steering system, and tire system was established based on the vehicle dynamics software TruckSim. Focusing on the analysis of the effect of tire deficiency and based on the tire six component test, the simulation test model of tire parameter was modified and the 0—80—0 km/h linear acceleration brake comfort simulation test and double line operating stability simulation test were conducted to study the smooth features and stability characteristics under the condition of tire deficiency at different positions. Based on the deviation of the centroid of the vehicle, the maximum number of missing tires at different driving speeds was analyzed, and the tire layout methods as well as the degree of influence of each axle tire on the vehicle at different driving speeds were proposed. The results show that the multi-axle special vehicle has the limit condition of driving under the condition of tire deficiency, and the tire deficiency at different positions has little effect on the driving speed of the vehicle. The influence of each axle tire on the driving of this type of vehicle is ranked in order of importance, which are the first axle, the fifth axle, the third axle, the second axle, and the fourth axle. When the vehicle travels at 50 km/h, 30 km/h, and 20 km/h, the maximum numbers of missing tires are 1, 2, and 3, respectively. This paper can provide theoretical support for the assessment of driving safety of multi-axle special vehicles.

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    Electronic Information and Electrical Engineering
    A Method for Autonomous Driving Trajectory Planning in Parking Environments
    LIN Chun, HE Yuesheng, FANG Xingqi, WANG Chunxiang
    2023, 57 (3):  345-353.  doi: 10.16183/j.cnki.jsjtu.2021.443
    Abstract ( 456 )   HTML ( 157 )   PDF (4106KB) ( 383 )   Save

    Local trajectory planning is one of the key technologies of the autonomous valet parking system. In this scenario, there exist problems such as long planning time, discontinuous curvature, and insufficient safety in local trajectory planning methods for intelligent vehicles. Aimed at these problems, this paper proposes a trajectory planning method for intelligent vehicles in parking scenarios. This method improves the real-time performance and security of the initial path search by improving the analytic expansions of the hybrid A* algorithm and introducing the risk function. Further, according to the initial path, the quadratic programming method is used to realize path smoothing and speed planning. Finally, the trajectory generation is completed. Simulation experiments show that the method can improve the real-time, smoothness, and safety of intelligent vehicle trajectory planning. In addition, in actual parking environment, the feasibility of the method is verified in real-world vehicle experiments.

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    Robot Skill Learning Based on Dynamic Motion Primitives and Adaptive Control
    ZHANG Wenan, GAO Weizhan, LIU Andong
    2023, 57 (3):  354-365.  doi: 10.16183/j.cnki.jsjtu.2021.379
    Abstract ( 585 )   HTML ( 183 )   PDF (12357KB) ( 443 )   Save

    A novel robot skill learning method using dynamic movement primitive (DMP) and adaptive control is proposed. The existing DMP method learns actions from a single teaching trajectory, and its Gaussian basis function distribution mode is fixed, which is not suitable for multiple movement trajectories with different characteristics. Therefore, the Gaussian mixture model (GMM) and Gaussian mixture regression are introduced into DMP to enable the robot to learn skills from multi-teaching trajectory. Moreover, radial basis function neural network (RBFNN) is introduced into DMP to establish the RBF-DMP method, which is able to learn the central position and weight of Gaussian basis through gradient descent and improves the accuracy of skill modeling. Furthermore, an adaptive neural network controller is designed to control the learned actions of the manipulator in redemonstration. Finally, experiments on Franka Emika Panda manipulator prove the effectiveness of the proposed method.

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    An Image Dehazing Method for UAV Aerial Photography of Buildings Combining MCAP and GRTV Regularization
    HUANG He, HU Kaiyi, LI Zhanyi, WANG Huifeng, RU Feng, WANG Jun
    2023, 57 (3):  366-378.  doi: 10.16183/j.cnki.jsjtu.2021.238
    Abstract ( 274 )   HTML ( 182 )   PDF (42329KB) ( 304 )   Save

    Aimed at the problems of low resolution, low contrast,and dark color of images recovered by traditional dehazing processing, an improved images dehazing method is proposed and applied to the unmanned aerial vehicle (UAV) aerial building image processing. First, to solve the problem that the value of global atmospheric light is easily affected by the scene objects, a method of atmospheric light with minimum variance of color attenuation prior projection is proposed. The difference image of brightness and saturation is constructed to solve the region where the minimum variance occurres, and the estimation of global atmospheric light is determined. Then, the regional atmospheric light is fused with the global atmospheric light by using the depth information of the image scene, and a new atmospheric light image is obtained. Finally, the haze line based on the non-local information prior theory in view of the transmittance is optimized. Moreover, this paper proposes a method based on the theory of haze line and guide relative to the total variation regularization algorithm. The transmission rate is fixed through calculating transmittance reliability function. A large amount of useless texture information existing in the image is eliminated, which enhances the precision of transmission rate estimation. It effectively improves the image quality of thick haze and abrupt depth-of-field in UAV aerial shooting scene. The experimental results show that, compared with other algorithms, the average gradient, contrast, haze aware density evaluator, and blur coefficient of the recovered images are improved by 12.2%, 7.0%, 11.9%, and 12.5%, respectively. The operation time of the proposed algorithm is shorter than that of some other algorithms, and the processed aerial images are clearer, which are more consistent with the visual perception of human eyes.

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