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Table of Content

    29 April 2019, Volume 30 Issue 08
    A Surface Roughness Measurement Method Based on Ultrasonic Nondestructive Evaluations
    HAN Xiaoqin1,2;SONG Yongfeng1;LIU Yu1; LI Xiongbing1
    2019, 30(08):  883-889. 
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    Different thread cutting processes were used to prepare a set of 304 stainless steel blocks with different surface roughness. Based on boundary conditions, the mean amplitude, the rate of standard deviation and the average power of the surface echo were simultaneously used to characterize the roughness, a multi-parameter evaluation model dependent on surface roughness was established using PCA. Compared with the needle contact method, the experimental results show that the maximum error of the surface roughness measured by ultrasonic is as 3.09% and its uncertainty is lower. Moreover, the errors are no more than 5% of grain size evaluation when applied the surface roughness evaluation model. Thus the proposed method may realize integrative evaluation of surface roughness and microstructure to improve the applicability of ultrasonic automatic evaluation.
    Effects of Grinding Marks on Fatigue Damage of Rails under Water Conditions
    GUO Shuai;ZHAO Xiangji;HE Chenggang;LIU Qiyue;GUO Jun;WANG Wenjian
    2019, 30(08):  889-895. 
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    The object herein was to investigate the effects of different grinding marks directions on the rail fatigue crack propagations under water medium conditions using a MMS-2A wheel/rail friction wear testing apparatus. And the different grinding marks angles to the running direction were manufactured on rail specimens by brown corundum sand. The results indicate that the surface roughness of rail specimen with the grinding marks angle of 0° ~45° to the running direction is higher than that with the grinding marks angle of 7°and 90° under the water medium conditions. The grinding marks with the angle of 0°~45° to the running direction may accelerate the fatigue crack propagations compared with the smooth area on rail specimen without prefabricated grinding marks. And the crack propagation is particularly serious on the rail specimen surface with the angle of 20° grinding marks which has a lot of branch cracks. The growth of the fatigue cracks slows down for the rail specimen with the grinding marks angle of 70°, 90°, and there are only surface cracks on the rail specimen with the angle of 90° grinding marks. With the angle of grinding marks increases from 0° to 90°, the crack propagation depth of rail specimen increases firstly and then decreases, and the crack propagation angle tends to decrease gradually.
    Nonlinear Dynamics Model and Control Parameter Optimization of Roll System on High-speed Cold Rolling Mills
    WANG Qiaoyi;ZHU Yuan;GUO Shan;ZHANG Qiubo
    2019, 30(08):  896-901. 
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    The dynamics model of high-speed cold rolling mills considering nonlinear factors coupling was established based on the model of dynamic rolling forces of rolling processes, the model of segmented nonlinear elastic forces and nonlinear friction forces in rolling mill systems. Average method was used to solve the amplitude frequency response equation of this model and the influences of main parameters on the vertical vibration were analyzed. The results show that the primary stiffness of dynamic rolling forces is negatively proportional to the inherent frequency of the rolling system; jumping phenomenon is obvious when the cubic stiffness is not zero or when the nonlinear elastic forces plays a leading role; the nonlinear friction forces is negatively proportional to the vibration amplitude; the segmented characteristic is weakened when nonlinear friction forces is great; the extraneous forces is positively proportional to the vibration amplitude; the rate of vibration amplitude reduction is slower with the increase of linear damping.
    Driver Yawning Detection Based on Deep Convolutional Network and Tracking with Online Learning
    ZHANG Weiwei1;MI Zeyang1;XIAO Lingyun2;QIAN Yubin1
    2019, 30(08):  902-911. 
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    A method for driver yawning detection was proposed based on multi-information fusion. Firstly, the driver face database was built ,and the deep convolutional neural network was trained for driver face and nose detection in sequence. Secondly, an online nose detector was generated through training a random forest classifier with local binary feature,which was introduced to compensate the nose tracking errors caused by optical flow-based nose tracker. At last, the edge gradient changes were analyzed in the mouth area under the nose. The informations like nose tracking confidence and face lateral movement were combined to determine the drivers were yawning. The experimental results show that, compared with other face classification method, the deep convolution network may obtain better classification detection effectiveness. The online learning-based tracking method may reduce the drift errors greatly introduced by the optical flow-based tracker. The whole algorithm may detect driver yawning event with satisfactory accuracy under different driving conditions.
    Starting Performance of Emergency Diesel Engines Based on Vibration Monitoring
    JIANG Zhinong1;MAO Zhiwei1;WANG Zijia2;BAO Binbin3;ZHANG Jinjie2
    2019, 30(08):  912-918. 
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    Based on vibration monitoring an emergency starting performance analysis method  was proposed to make up the shortcoming of the current analysis based on thermal parameters. The precise conversion of vibration signals from time domain to angle domain was implemented based on key phase and instantaneous rotational speed. An envelope method was carried out to extract the futures of transient vibration signals measured during start processes by which the smooth could be adjusted. These futures were capable to reflect the combustion states and the high pressure air working conditions. The grey evaluation method was introduced to monitor and evaluate the working capacity of single cylinder during startup. The results of the actual test verified the effectiveness of this method, and shown practical value for field applications.
    Stability Analysis of High-lift Fully Balanced Hoist Vertical Ship Lift Systems
    CHENG Xionghao1,2;SHI Duanwei1,2;LI Hongxiang1;XIA Re2;ZHANG Yang1;ZHOU Ji1
    2019, 30(08):  919-925. 
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    A theoretical formulation for calculating critical distance of lifting points to make the fully balanced hoist vertical ship lift stable was presented through the theoretical analysis, with which the influence laws of the stability of the systems under higher lift were studied. Using the Lagrange equation of the second kind, a 7 DOF dynamics model of the ship lift was then established, including the ship chamber, the wire rope, the gravity counterweight, the hoist, the synchronous shaft, as well as the liquid in the ship chamber. Moreover, on the basis of the Descartes' rule, the theoretical formulation for calculating critical distance of lifting points maintained system's stability was proposed. The influence of the lifting exerted on the ship lift stability was studied. Besides, the dynamical characteristics of the fully balanced hoist vertical ship lift were analyzed numerically, applying fourth-order variable Runge-Kutta method, to obtain the various free degrees' displacements response. According to the convergence of displacement responses, the critical distance of lifting points may be assessed. Finally, the deviation between the calculations of the theoretical formula and that of the dynamical simulation with damped is as 9.02%, hence the rationality of the theoretical formulation was validated. It may be utilized to design the distance of lifting points, the wire rope's stiffness, the host's radius, as well as the synchronous shaft's stiffness, judging the stability of high-lift fully balanced hoist vertical ship lift.
    Dynamic Scheduling of RGV under Uncertain Environments
    LI Guomin;GAO Liang;LI Xinyu
    2019, 30(08):  926-931. 
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    To optimize the RGV scheduling under uncertainty environments,a kind of scheduling rule was proposed based on CCPP. Taking the RGV scheduling system in an intelligent workshop as research object,considering that the CNC machines might stop working due to a series of uncertainty factors such as tool replacement,machine faults,etc.,the scheduling rule was proposed to optimize the feeding sequence of RGV  in real time based on CCPP.Additionally,the nearest rule was presented to verify the superiority of CCPP scheduling rule. Results demonstrate that the capacity of intelligent workshops may be improved effectively by conducting CCPP scheduling rule,and the walking distance of RGV is reduced.
    Frictional Force Test of Rotor Compressor Slides-chute Movement Deputy Based on LuGre Mode
    WEI Wei1,2;GENG Kuihua1,2;GENG Ainong3;WANG Shaowei1;LI Xinmo3
    2019, 30(08):  932-938. 
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    In order to study the friction characteristics of rotor compressor slide-chute pairs, according to the modeling method of LuGre friction model and the operation and working conditions of the pair, a slide-slide equivalent frictional test system was designed and built, The phenomenon of frictional forces, the data acquisition area and the frictional force measurement repeatability of the system were analyzed, and the frictional force tests were carried out. The results show that the frictional test system may uniformly load the corresponding positive pressure FH based on the actual working conditions of the compressor and realize the frictional force measurement under uniform linear motions with different speeds vc. The phenomenon of friction jump may be effectively eliminated which caused by low speed lubrication non-uniform. Through the lubrication initialization, the expression of the friction forces may be obtained accurately  based on the change of the vane speed. The experimental results are in good agreement with the numerical ones, which provides an experimental basis for correctly identifying the parameters of the LuGre friction model.
    Review on sCO2 Brayton Cycle Power Generation Technology Based on Ship Waste Heat Recovery Utilization
    YAN Xinping1,2,3;WANG Jiawei1;SUN Yuwei1,2,3;YUAN Chengqing1,2,3;TANG Xujing1,2,3;GENG Haipeng4
    2019, 30(08):  939-946. 
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    In the processes of energy conversion and utilization of ship power systems, the realization of the maximum efficiency recovery of flue gas waste heat was an effective way to reduce the EEDI of the ships. sCO2 power generation system had the technical advantages of the ship's waste heat recycling, which caused the global shipbuilding industry's attention. How to organically integrate sCO2 power generation system  with the ship's power system to achieve high-efficiency and stable combined-cycle operation of power generation was the bottleneck that currently restricted the applications of the above-mentioned new technology on-board ships. The basic principles, typical technical features and cyclic structure of the sCO2 Brayton cycle power generation technology were outlined, and the research status of the sCO2 power generation system for the waste heat recycling of ships at home and abroad was analyzed herein. The key technical problems existing in the engineering applications of waste heat power generation for shipbuilding at the present stage were discussed, which may provide a theoretical reference for the promotion of basic theoretical research and engineering design of sCO2 Brayton cycle power generation technology in the field of waste heat recovery and utilization of ship flue gas.
    Terminal Sliding Mode Fault-tolerant Control for Space Robots under Partial Loss of Actuator Effectiveness
    LEI Ronghua1,2;CHEN Li1,2
    2019, 30(08):  947-953. 
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    A decentralized fault-tolerant control method was designed based on non-singular terminal sliding mode for a space robots subjected to partial losses of actuator effectiveness. Firstly, the dynamics equation of the system was established by using linear momentum conservation law and Lagrangian method. Subsequently, the system was decentralized into several subsystems based on the local informations of the carrier and joints, and the dynamics equations of subsystems were obtained. Then the effective factors were separated from the subsystems' dynamic equations, and the adaptive decentralized neural network was used to estimate the separated variables in real time. According to the estimation results, the corresponding control law was designed online to counteract the influences of the actuator faults on the stability of system and ensure good trajectory tracking performance. The asymptotic stability of the whole closed-loop system may be guaranteed under the proposed control scheme via Lyapunov function method. The simulation results demonstrate the effectiveness of the proposed control method.
    Dynamics Modelling and Optimization for Closed Five-bow-shaped-bar Linkages with Redundant Actuation
    YU Lianqing1;WANG Zhankun1;LI Hongjun1;MENG Yunhong2
    2019, 30(08):  954-960. 
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    The problem of the coordination and distribution of the driving torque during the dynamic rolling process of redundant drive closed five-bow-shaped-bar linkage was studied herein. The kinematics model of closed five-bow-shaped-bar linkage was established, the speed and acceleration of the driving links and constraint links were analyzed respectively, the acceleration matrix and the angular acceleration matrix of each link were obtained, the resultant forces and torques of each link were figured out, and the dynamics equation of the mechanism were obtained on the basis of Newton-Euler approach. Driving torques coordination was carried out with pseudo inverse method, so that the 2-norm of the instantaneous driving torque was minimal. The driving torques under non-redundant driving and redundant driving were calculated respectively according to the joint trajectories of the mechanisms during a rolling cycle. The calculation results indicate that redundant actuation may reduce the maximum instantaneous driving torque significantly.
    Topological Design and Kinematics of 3T1R PM with Single Degree of Freedom
    SHEN Huiping;LYU Meng;ZHU Xiaorong;LI Yunfeng
    2019, 30(08):  961-968. 
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    According to the topology design theory and decoupling-reducing design method of PM based on the position orientation characteristic(POC) equations, a new single degree of freedom(1-DOF) fewer-input more-output (Fi-Mo) PM with three-translation and one-rotation motion(3T1R) output was designed. Topological characteristic analysis of the PM was also performed, which includes POC set,DOF and coupling degree. Then, solution of direct kinematics was established according to the kinematics modeling principle based on ordered single opened chain(SOC), and numerical solutions of the PM were given. The inverse position solution formula as well as the velocity and acceleration formula were also solved and simulated. Finally, the 3D virtual prototype of the Fi-Mo PM was designed that may be used as a parallel vibrating screen. The research results herein lay a foundation for the dimensional optimization design and development of the 3T1R parallel vibrating screens.
    Shift Orbit Recognition Method of Aero-engines Based on SVM Decision Tree
    HE Liuhai;WU Guijiao;WANG Ping
    2019, 30(08):  969-974. 
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    It was difficult to automatically and exactly identify shift orbits of aero-engine rotors, a  recognition method was proposed based on two-dimensional feature invariant moments and SVM decision tree. First, the relatively clear shift orbits could be acquired after the noise reduction and frequency purification of the signals. The invariant moments were used to extract the graphic features of the shift orbits, then the invariant moment vectors were obtained, constructing the training and test samples of the characteristic faults. Finally, in order to construct SVM decision tree and identify faults, support vector machine was trained and studied. The accuracy rate of classification reaches 93.3%. The method was verified by measured signals of elastic support vibration stress. The results show that the method effectively resolve low recognition accuracy and small sample problems for shaft orbits of aero-engine rotors.
    A MINLP Model and Improved Simulated Annealing Algorithm for Double-layer Corridor Allocation Problem
    GUAN Chao;ZHANG Zeqiang;ZHU Lixia;MAO Lili
    2019, 30(08):  975-983. 
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    Considering the situation that facilities were distributed into multi-layers space, a double layer corridor allocation problem was proposed, and a MINLP model was built for this problem. Concerning the problem features, an improved simulated annealing algorithm was proposed, which was improved in annealing processes and sampling processes via adopting the two-stage improvement strategy. The algorithm replaced the Markov chain search length with adaptive searching strategy, combined the memory function and the tempering operation to improve the solving quality; the double threshold was also set to improve the efficiency of the solution. 24 benchmarks were tested with the proposed algorithm and the validity was verified compared with the results of the basic simulated annealing algorithm and GUROBI exact method.
    Public Bicycle System Fault Diagnosis Based on Naive Bayesian Classifier
    SHI Zhongchao;HAO Weina;DONG Hongzhao
    2019, 30(08):  983-987. 
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    In view of the facts that PBS was not equipped with on-board detection sensors, bicycle failure might not be found directly in time and make rider to suffer the safety risks. To solve such an issue, a bicycle fault diagnosis method was proposed based on naive Bayesian classifier. By analyzing the PBS historical data including rental records, maintenance records and user evaluation etc., 15 state classification features were extracted as feature vectors for bicycle fault detection. Based on the posterior probability of Naive Bayesian classifier, the contribution rate of each state classification feature to the class was obtained; the recall rate was used as an evaluation index to predict the diagnosis of failed bikes. Based on the running data of 2016 from Hangzhou PBS, the model was verified by experiments. Through the optimization of the input eigenvalue of the prediction model, the recall rate of the test samples reaches 85.79% with satisfactory accuracy.
    Drawing Process of Aluminum Plastic Film Shell for  Package of Flexible Packaging Lithium Battery Cores
    GUAN Yuming;ZHAO Yue;CUI Jia;YU Pan;LI Zhao;SHANG Peng
    2019, 30(08):  988-993. 
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    The properties of aluminum plastic films were analyzed by tensile test. The material properties of aluminum plastics were defined in Dynaform software. The simulations of aluminum plastic film drawing processes were carried ort. The process parameters that affected the formability of aluminum plastic films were analysed by single factor experiment and orthogonal test. The parameters which affected the formability of aluminum plastic shell films such as blank holder forces, die fillet radii, friction coefficients,and stamping speeds were optimized by using RSM, LHS and MOPSO. The thickness of the films is as 55 μm after optimization. The experimental results show that the optimization results of the aluminum plastic film forming processes are feasible.
    Preparation and Flexural Mechanics Properties of Carbon Fiber-Aluminum Laminates by Cold Rolling
    WANG Jian;ZHANG Liangliang;YU Yue;FU Changyun
    2019, 30(08):  994-1001. 
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    In order to study the feasibility and mechanics properties of the aluminum alloy/carbon fiber prepreg laminates by rolling processes, they were prepared based on different surface treatments of the aluminum sheets and rolling reductions, the effects of the surface treatment processes and reduction on the flexural mechanics properties of the laminates were analyzed by the three point bending tests. The results show that the surface treatment processes and the reductions have significant influences on the mechanics properties of the laminates. The bending performance of the laminatesis improved significantly by the anodizing processes, the flexural strength is as 573 MPa and the modulus is as 80.9 GPa, compared with the surface untreated samples they increase by 65.9% and 39.1% respectively, the interfacial bonding performance is obviously better than that of chemical cleaning and mechanical grinding processes. The failure mode of the laminates transformed the fiber integral fracture and the lamination into the fiber buckling deformation. When the reduction isas 6.5%, the interface of the aluminum alloy/fiber resin is neat and smooth, and the flexural performance of the laminates is optimal, It is indicated that the appropriate rolling pressure is beneficial to the resin flow infiltrating fiber, compacting interlayer porosity, and conducive to form a stable mechanical occlusal structure on the surface of the resin and aluminum alloy.
    Intelligent Manufacturing Scheduling First-A Guide of Manufacturing System Intelligent Scheduling Method and Cloud Service
    ZHANG Jie1;QIN Wei2
    2019, 30(08):  1002-1007. 
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    With more micro enterprises reflected the demands of  “all things perceive, interconnected, and smart” in manufacturing workshop, combining big data and cloud computing technologies, constructing multitype scheduling algorithm libraries and providing intelligent scheduling schemes were the keys to achieve efficient operations of manufacturing systems. In order to explore the principles, methods and cloud computing paths of intelligent scheduling, a book “Manufacturing System Intelligent Scheduling Method and Cloud Service” was written by authors. It comprehensively introduced a variety of complex scheduling problems of manufacturing systems, emphatically introduced the corresponding various scheduling methods, specifically introduced cloudbased technologies and implementation methods combined with the cloud service framework, and built a cloudbased manufacturing workshop intelligent scheduling algorithm library and service system. It is of great significance to enhance the core competitiveness of China's manufacturing industries.