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Table of Content

    25 July 2017, Volume 28 Issue 14
    Coupling Characteristics of Independent Volume-in and Volume-out Control for Open Circuit Pump-controlled Asymmetric Cylinder Systems
    YAO Jing1,2,3;WANG Pei3;DONG Zhaosheng3;KONG Xiangdong1,2,3
    2017, 28(14):  1639-1645. 
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    In order to address the flow asymmetry problems of closed circuit pump-controlled asymmetric cylinder systems caused by two-chamber area differences, this paper proposed an independent control of open circuit pump-controlled asymmetric cylinder systems. While two chambers of asymmetric cylinder used two different control methods, the coupling among parameters was investigated. Taking position and pressure combined control method as example, mathematic models and coupling problems of the systems were established and analysed respectively. Thus, the control method of position feed-forward compensation decoupling were used to decouple. Based on 600kN pump-controlled hydraulic forging press test bench, the coupling and decoupling characteristics were verified. Experimental results indicate that position feed-forward compensation method may inhibit the hydraulic system couplings under sinusoidal disturbances. Specifically, when the frequencies are as 1Hz and 1.25Hz, the inhibition ratios are as 16.4% and 14.8% respectively.
    Study on Spark-ignited Two-stroke Direct Injection Heavy-oil Engines at Low Loads
    BEI Taixue1;WEI Minxiang1;LIU Rui1;YANG Guang2;YANG Baifan1
    2017, 28(14):  1646-1651. 
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    An experimental study on the performances was carried out on a two-stroke engine with low pressure air assisted injection technology by aviation kerosene. The influences of ignition angle advance, end angle of air injection and excess air coefficient on the performance of the engine was studied under the conditions of 3000r/min low loads. Test results show that: when end time of air injection is set to 50° and 80° before top dead center(BTDC), the increases of ignition advance angles may make the engine power increase and the fuel economy reduce. But, the increases may not be too much, or it will cause the increases of CO and HC. When the ignition advance angles are set to 15° and 30° BTDC, the engine powers, fuel consumptions and emission performances may be improved by the advances of the end time of the air injection. And, the rich mixture is beneficial to improve the power outputs, and the lean mixture is beneficial to reduce the emission.
    Erosion Prediction and Verification for Throttle Valve Materials about Incident Angles at High Pressure Fluids
    WANG Guorong1;QIAN Quan1;CHU Fei2;ZHANG Xiaoli3
    2017, 28(14):  1652-1657,1663. 
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    Aiming at the problems of spool outline seriously eroded, the service life of throttle valves was declined, which was caused by high speed solid particles in drilling fluids. An Euler-Lagrange model and discrete phase model were used to predict erosion mass loss, erosion rate and morphology distribution of 40Cr steels, which were impacted by the particles with different incident angles. Meanwhile, the calculation results were compared with the related experiments. Comparison results show that the depth of erosion pits, mass loss and erosion rate of 40Cr steels increase at first, and then decrease when the incident angle varies from 15° to 90°. The erosion profile of specimen changes from ellipse to circle gradually. As to the incident angle of 45°, the mass loss achieves the maximum. Accordingly, it is also recommended to avoid the particle incident angle of 45° to slow down the erosions of spool in optimum design.
    Dynamic Response of Shimmy Systems under Braking Conditions with Consideration of Clearances in Joints
    JIANG Junzhao1;LU Jianwei1;LI Jinhui1;YANG Shiqin2
    2017, 28(14):  1658-1663. 
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    A 7-DOF dynamic model under braking conditions was established, where time-varying characteristics of parameters and dynamic coupling among movement pairs with clearances were taken into account. Dynamic response analysis of shimmy system under braking conditions was carried out through numerical examples with MATLAB. Moreover, influences of load transfers, vehicle speeds, clearances and wheelbases on transient response of shimmy system were discussed. It is concluded that the time-varying characteristics of parameters under braking conditions and dynamic coupling in joints with clearances may have great influences on dynamic behaviors of shimmy, which should be taken into account in system modeling. The conclusions agree with the experimental results in general, which may verify the accuracy of the dynamic model.
    Research on Electric Vehicle Yaw Stability Based on Torque Optimum Distributions
    YANG Shen1;OU Jian1;YANG Echuan2;HU Jingqing1;ZHANG Yong1
    2017, 28(14):  1664-1668. 
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    With improving vehicle stability as objective, a combination control strategy of yaw rates and slip angles was designed for a four in-wheel-motor driven electric vehicle based on fuzzy control method. A hierarchical control structure was investigated, the upper layer obtained required additional yaw moments based on fuzzy control theory, while lower layer used weighted least squares method to optimize torque distributions by adopting an in-wheel motors/hydraulic brake system combined control strategy. And real-time simulation experiments were carried out based on real-time simulation platform, simulation results show that the optimal allocation control strategy of combined in-wheel motor and the hydraulic braking system may improve the stability of vehicles effectively.
    Impacts of Magnetic Flux Coupling on Force Arrangements of Radial Magnetic Bearings and Its Decoupling Control Strategies
    JING Xuan1;TAN Yuanqiang2;ZHU Jie3
    2017, 28(14):  1669-1676. 
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    Because of the magnetic flux coupling among the magnetic stator poles, the distribution of the magnetic force would suffer a great inaccuracy, which would result in the disability of the original control currents to provide an accurate restoring forces. In order to eliminate the magnetic coupling impacts, based on the Boit-Savart law, a magnetic flux distribution model was built to discuss what kind of factors would influence the magnetic field coupling. A magnetic force equivalent model with consideration of the gap variations was established. The flux coupling degree impacts on the magnetic force errors of an 8-pole magnetic bearing were analyzed. A decoupling control strategy was proposed, and its validity was tested by the ANSYS simulation and the steady state suspension test of magnetic bearings.
    Adaptive PID Control Based on RBF Neural Network for TBMs
    SONG Liye;WAN Yingcai
    2017, 28(14):  1676-1682. 
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    The matching problems for full cross section TBM thrust pressures and thrust speeds, the applications of RBF neural network algorithm were designed to make the thrust pressures and the thrust speeds matching and speed adaptive controller might quickly follow the set goals. The controller was simulated by MATLAB, and the hydraulic control model of propulsion systems was established in AMESim and co-simulation with MATLAB. By joint simulation, the controller might make the cutter driving speeds and thrust pressures follow the set target when the cutter load pressures were abrupt. Experiments show that the controller has a good ability to suppress the load disturbances, and may improve the propulsion speeds obviously and push the pressure coupling degrees and reduce the fluctuation ranges of the both.
    Multi-objective Optimization of Control Strategies for Four-wheel Drive PHEV Based on Immune Algorithm
    WANG Yongkuan1,2;QIAN Lijun1;NIU Limin2
    2017, 28(14):  1683-1690. 
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    To improve fuel economy and emission performance of a four-wheel drive PHEV, the rule-based energy management control strategy and vehicle simulation model were established firstly. Then, a multi-population immune algorithm was presented by introducing the concept of multi-population co-evolution. The algorithm was adopted to optimize the control strategies of four-wheel drive PHEV with multiple objectives. Finally, a hardware-in-the-loop simulation experiment was carried out on dSPACE real-time simulation system to test the control strategy before and after optimizations. Experimental results show that the optimized control strategy may achieve good control effectiveness, furthermore, the fuel consumption of engine is reduced by 12.71% while the HC, CO and NOx emissions are decreased by 15.74%, 15.92% and 12.69% respectively.
    Structural Modal Analysis and Optimization of Mini-car Doors Based on Response Surface Method
    QIN Xunpeng1,2;FENG Jiawei1,2;WANG Yongliang1,2;JIN Lei1,2
    2017, 28(14):  1690-1695. 
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    Sensitivity analysis method and response surface method were used to optimize structural modal of the mini-car doors. A finite element numerical simulation model was established, and the simulation model was calibrated by restraint modal tests. In order to screen out high sensitive plates, a sensitivity analysis for the thicknesses of door plates was proposed based on door's third order modal frequency. Sample points were obtained by face centered composite design while design variables were from the thicknesses of high sensitive plates, and a two order explicit response surface function of vehicle door's third order modal frequency was established. According to the response surface function, an optimization model was established. The final results show that the modal frequency matching of the door and body in white is optimized after changing the door thicknesses, while materials are saved about 5.83%.
    Structure Design of S-type Foldable Flexible Hinges
    YAN Kai1,2,3;ZHANG Jing1,2,3;KOU Ziming1,2,3
    2017, 28(14):  1696-1700. 
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    According to principles of flexure hinge series and parallel relationship, a S-type foldable flexible hinge was designed in order to reduce flexibility and get a larger corner of the flexible hinges. Using pseudo rigid-body method and energy method, the stiffness model of S-type flexure hinges was deduced. By ANSYS, a finite element model of the flexible hinges was built, and the stiffness and stress analyses of the S-type hinges were carried out. It is found that the stiffness of errors are about 3% by comparing the simulation values and theoretical values. As a result, the stiffness model of S-type flexure hinges is proved right. When the rotational degrees about the flexure hinge are up to ±35°, the safety of factor is as 4. So the S-type foldable flexible hinges fully meet the design requirements.
    Nonlinear-modeling and Coordinate Optimization of Semi-active Energy Regenerative Suspensions with Electro-hydraulic Actuators
    KOU Farong;DU Jiafeng;WANG Zhe;FAN Erjun;LI Dong
    2017, 28(14):  1701-1707. 
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    In order to coordinate damping performances and feed energy performances of energy regenerative suspensions with electro-hydrostatic actuators(EHA), a nonlinear model of semi-active energy regenerative suspensions with EHA was established, and mechanics property tests were carried out. According to the test results with recursive least squares algorithm which was carried out for parameter identification of the system model, influences of the main parameters of EHA on the damping performances and feed energy performances of suspension were analyzed, genetic algorithm was used to optimize main parameters of EHA, and the bench test was carried out. The test results show that when sinusoidal spectrum is input at frequency of 2Hz and amplitude of 30mm, the spring mass acceleration RMS value of optimized EHA semi-active energy regenerative suspension reduces 22.23%, and energy regenerative power RMS value increases 40.51%, which means under meeting the certain vehicle ride comfort and driving safety requirements, energy regenerative performance is improved significantly.
    Turbulence Model Correction and Internal Flow Characteristics Analysis of Hydraulic Manifold Blocks
    HU Jianjun1,3;CHEN Jin3;QUAN Lingxiao1,2;ZHANG Jin1,2;KONG Xiangdong1,2
    2017, 28(14):  1708-1713. 
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    A corresponding numerical calculation model was established and the three-dimensional flow field simulation was carried out based on the particle image velocimetry (PIV) measurements of the flow fields of right-angle turn channels with cavities. The predictive ability of the 7 kinds of turbulence models commonly used in engineering were investigated by comparison the typical vortex structure of numerical results. By defining the weight error function K, a S-A model was selected as the basic turbulence model and were modified. The results show that when the S-A model Cb1 is modified from the default value 0.1355 to 0.17, the weight errors of the outflows facing to the right angle cavity model increase by 25.0%, and the weight errors of the inflows facing to the right angle cavity model decrease by 34.7%. In general, the predictive accuracy of modified S-A turbulence model is improved in forecasting the flow fields of two kinds right-angle turn channels with cavities. The internal flow characteristics of four typical right angle channels were analyzed by using the modified S-A turbulence model, the results show that the arc right angle flow passages have smaller pressure losses than that of the turning flow channels with cavities.
    Influences of  Structural Parameters on Properties of Poppet Valves#br#
    FAN Yilin1;ZHANG Jiwei1;HU Chunyan1;LI Shuxun2
    2017, 28(14):  1714-1717. 
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    For the requirements that steam soot blowers of utility boiler should have high efficiency and low cost, based on immersed solid method, the influences of shrinkage angle α and expansion angle β on the opening dynamic characteristics were studied, and the flow curves of different shrinkage angles and different enlargement angles were obtained. The results show that flow rate increases 23% at the small opening when α increases from 20° to 50°, flow rate increases 56% at the large opening when β increases from 0° to 15°. Increasing shrinkage angle may improve the flow rate at the small opening, and increasing expansion angle may improve the flow rate at the large opening within the ranges of the structure.
    Multi-axis Linkage Servo System Simulation Considering Cutting Force Interferences
    ZHANG Quanbiao;WANG Guofeng;SONG Qingyue;WU Lirui;YANG Xinghuan
    2017, 28(14):  1718-1723. 
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    For the machine tool servo system performance analysis, a servo control model in both of X and Y directions was established. On the basis of the model, a four-quadrant interpolation algorithm was introduced into the control system simulation model, and the influences of PID parameters on command deviations of circular interpolation were studied in the case of multi-axis linkage. In addition, considering the impacts of the cutting forces in machining processes, the actual cutting force signals collected in machining processes were added into multi-axis linkage simulation model. Simulation results show that the actual cutting forces have significant effects on the control system characteristics, and it is necessary to consider the influences of real-time cutting forces in PID parameter optimization.
    Three Dimensional Structural Shape Optimization Based on Sensitivity Analysis Using Isogeometric Analysis
    CHEN Long;ZHANG Gaopeng
    2017, 28(14):  1723-1729. 
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    An isogeometric analysis method was used as numerical analysis method. As for three-dimensional structures of linear elastic problem, boundary control points that needed to be optimized were regarded as design variables, derivatives of internal control points as to design variables might be obtained by using Coons interpolation method. In shape optimization, sensitivity equation of element stiffness matrix as to control points coordinates was derived, and sensitivity equations of stresses and displacements were deduced. Numerical examples show that the method has high efficiency and good results.
    Part Position and Orientation Recognitions on Intelligent CMM
    HAN Zhenhua;LIU Shugui;GAO Lizhen;YU Fei
    2017, 28(14):  1730-1734,1741. 
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    In order to improve the intelligence of CMM for part detection, it was necessary to recognize positions and orientations of parts. A new visual recognition method for positions and orientations of parts was proposed. The new method firstly extracted actual 3D feature informations of parts more comprehensively, and then matched combinations of the 3D features were found in virtual space. Rotation matrix and translation matrix were computed by matched combinations. Finally, the positions and orientations were determined according to part contour matching similarity between real and virtual imaging. Experiments show that the positions and orientations may be recognized by the new method.
    Imitation Learning Control Method of Humanoid Robots Based on Coupling Algorithm
    LI Wenhua1;YANG Zining1;WANG Laigui2
    2017, 28(14):  1735-1741. 
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    To improve accuracy and efficiency in learning from demonstrations by humanoid robots, an imitation learning model was established based on improved PSO to optimize extreme learning machine, to learn human motions on the robots herein. A set of motions which was performed by a human demonstrator were collected to model as a nonlinear autonomous dynamical system. PSO was improved with the dynamic adaptive inertia weight. Then the improved PSO was merged with ELM to optimize network parameters. Using a mathematical model of improved PSO-ELM to learn the parameters of the dynamic system and reproduce human motions. The experimental results prove the method has a better fitting precision, adaptability and generalization ability on imitation learning of humanoid robots. The average relative errors are as 0.0172 of human motion reproductions.
    Fault Diagnosis Method of Bearings by Yu's Norm ART Based on Soft Competition
    MU Hailin, WANG Zhigang, XU Zengbing
    2017, 28(14):  1742-1746,1763. 
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    Fault interfaces were categorized wrongly by ART with hard competition. A new fault diagnosis method by Yu's norm ART was proposed based on soft competition. The soft competition method of fuzzy competitive learning(FCL) was introduced into Yu's norm ART, neural nodes in the competition layer were trained according to the degree of membership among the mode nodes and the inputs. Bearing fault data were used to validate the fault diagnosis model, which proves that the fault diagnosis model may distinguish different faults, and distinguish different fault degrees under the same fault types. Comparing with other methods for fault diagnosis, such as ART and fuzzy C-means clustering, the proposed method has higher diagnostic accuracy.
    Study on Frequency Spectrum Structure for Rolling Bearing Degradation Based on Full Vector Fusion and MEMD
    MA Yanli;JIN Bing;ZHANG Xuexin;HAN Jie
    2017, 28(14):  1747-1752. 
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    In order to recognize degradation processes of rolling bearings, a method combined MEMD with full vector fusion was proposed. Firstly, multi-channel synchronous analyses of vibration signals in different conditions were dealt with MEMD to obtain a series of multivariate intrinsic mode function(IMF) component. Then the most sensitive IMF component was selected by cross-correlation coefficient criterion to do full vector envelope analysis for extracting signal features. Analysis with simulated signal and actual signal was done to test effectiveness of the method respectively. It indicates that the method may reveal changes of frequency structure when faults appear, and shows the regularity that the more serious of the fault conditions is, the more complex of frequency spectrum structure becomes.
    Fracture Behavior of Aluminum Alloy Bars with V-shape Notchs under Dual Frequency Vibration Loads
    HUA Chunjian1,2;LU Yunjian1,2;YUAN Hao1,2
    2017, 28(14):  1753-1758. 
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    Aiming at problems of low crack initiations and propagation rates in low stress separation processes of metal bars, a new method was proposed based on double frequency vibrations. This method was used to explore the fracture behaviors of 7A09 aluminum alloy bars with V-shape notchs. The mechanism of double-frequency vibrations on the crack initiations and expansions of V-shaped metal bars was given. Experiments of the V-shaped groove 7A09 aluminum alloy bars were carried out by developed dual-frequency exciting device. Experimental results show that compared with the single frequency vibration loading method, double frequency vibration load may shorten separation time of 7A09 aluminum alloy bars with V-shape notchs significantly, improve the crack initiation rates and stability of the expansion effectively, also the bar section geometric accuracy is high.
    Comprehensive Optimization Technology of Roller Profiles in Continuous Annealing Furnaces
    BAI Zhenhua1;WANG Yunxiang1;WANG Rui1;CUI Yaya1;LI Xiaofeng1;GUO Zhensheng2
    2017, 28(14):  1759-1763. 
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    In order to solve the problems of strip deviation and buckling in continuous annealing processes, combined with advantages and disadvantages of single taper rollers and double taper rollers in prevention and treatment of the buckling and strip deviation, a new set of furnace roller profile curves was designed, and a set of optimization models suitable for furnace rollers was established in continuous annealing furnaces, with travelling stability of the strips as objective function of roller profile optimization designs. After field production practices, test results show that the roller profiles after optimization make the strip deviation distance and the buckling index decrease significantly, the high-speed and stable continuous productions of the unit are guaranteed.